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Precision Ion Polishing System

Owner’s Manual and User’s Guide

Part Number: 691.82001February 2008

Revision 4

Gatan, Inc.5794 W. Las Positas Blvd.Pleasanton, CA 94588

Tel. (925) 463-0200Fax. (925) 463-0204

ii PIPS Owner’s Manual and User’s Guide

Preface

About this Manual

This PIPS Owner’s Manual and User’s Guide provides information and instruc-tions for installing and using the Gatan Precision Ion Polishing System (PIPS). Routine maintenance and service procedures are also included in this manual, along with troubleshooting tips.

The following typographical conventions are used for special comments:

NOTE: Recommendations for getting the best performance from the equipment.

The PIPS Owner’s Manual and User’s Guide consists of the following two chap-ters.

● The Owner’s Manual (starting on page 1) includes specifications for the prod-uct and step-by-step installation instructions. A parts list provides numbers for ordering spares or replacements.

● The User’s Guide (starting on page 19) explains the operation of the unit, including sample preparation, troubleshooting, and routine maintenance and servicing.

● PIPS Options (starting on page 75) describes options available for use with the PIPS system.

Copyright and Trademarks

© 2007 Gatan, Inc. The Gatan logo is a registered trademark of Gatan, Inc.

The product names AutoFilter, BioScan, Clipring, DigiPEELS, DigiScan, Digi-talMicrograph, DigitalMontage, Duo Mill, DuoPost, Gatan LowDose, GIF, Hex-lok, Hexring, HotHinge, MSC, PECS, PIPS, Toggle Tilt, and Whisperlok are trademarks belonging to Gatan, Inc.

CAUTION: Precautionary notes and advice to avoid personal injury or damage to the equipment.!

PIPS Owner’s Manual and User’s Guide iii

The PIPS is protected by US Patents 4,272,682; 5,009,743; and 5,472,566. Other patents are pending.

Disclaimer

Gatan, Inc., makes no express or implied representations or warranties with respect to the contents or use of this manual, and specifically disclaims any implied warranties of merchantability or fitness for a particular purpose. Gatan, Inc., further reserves the right to revise this manual and to make changes to its contents at any time, without obligation to notify any person or entity of such revisions or changes.

Support

Gatan, Inc. provides free technical support via phone, fax, and electronic mail. To reach Gatan technical support, contact the facility nearest you, or send electronic mail to [email protected].

USA, Canada, & Latin America

Field ServiceGatan, Inc.5933 Coronado LanePleasanton, CA 94588Tel. +1 (925) 224-7360Toll Free: +1 888-887-3377Fax. +1 (925) 463-0204Contact: service @gatan.com

Parts and ConsumablesGatan, Inc.5933 Coronado LanePleasanton, CA 94588Tel. +1 (925) 224-7314Fax. +1 (925) 463-0204Contact: service @gatan.com

Factory ServiceGatan, Inc. 780 Commonwealth DriveWarrendale, PA 15086Tel. +1 (724) 779-2552Toll Free: +1 888-778-7933 Fax. +1 (724) 776-3360 Contact: service @gatan.com

iv PIPS Owner’s Manual and User’s Guide

Asia & Pacific Rim Nippon GatanHibarigaokaminamikan 6F3-27-11 Yato-cho, Nishi-Tokyo-ShiTokyo 188-0001 JapanTel: 011-81-424-38-7230Fax: 011-81-424-38-7228Contact: [email protected]

Gatan Singapore10 Eunos Road 8#12-06Singapore Post CentreSingapore 408600Tel: (65) 6293 3160Fax: (65) 6293 3307Contact: [email protected]

Europe Gatan GmbH, München GermanyIngolstadterstr. 12D-80807 MünchenGermanyTel. +49 89 358084-0Fax. +49 89 358084-77Contact: [email protected]

Gatan UK25 Nuffield WayAbingdon, OX14 1RLUnited KingdomTel. +44 1235 540160Fax. +44 1235 540169Contact: [email protected]

Gatan France3bis, Chemin du Haut Breuil78113 GRANDCHAMPFRANCETel : 33 1 34 94 44 07Mobile : 33 6 80 13 51 39Fax : 33 1 34 87 16 68Contact: [email protected]

PIPS Owner’s Manual and User’s Guide v

Returns

If there is a need to return equipment to the factory, please call Gatan to obtain a Returned Merchandise Authorization Number (RMA #). This RMA number must appear on your shipping document, to help in tracking and to ensure that proper action will be taken to repair or replace your equipment.

Product Safety and Compliance

CE Marking The Precision Ion Polishing System is designed to meet regulatory standards and CE requirements. This product has been tested by an independent accredited third party and has been found to be in compliance with applicable CE marking require-ments per the EMC Directive and the Low Voltage Directive. See the Declaration of Conformity at the end of this manual for applicable standards and tests.

Safety All the hazardous voltage and energy are enclosed with no operator accessible or serviceable parts. For safety of personnel and equipment, it is the user's responsi-bility to ensure that operators are properly trained and all safety instructions are provided and followed, including the instructions provided in this manual.

Safety Labels and Instructions

Fuse Label

Model and Serial Number Label with CE mark

High Voltage Warning

Caution/Hazard Label

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Electromagnetic Compatibility (EMC)

The Precision Ion Polishing System has been designed to comply with the EMC Directive per CE Mark requirements. Good EMC design practices are used such as the use of metal-to-metal contact (masking and EMI gaskets), and shielded cables with 360 degree termination. To ensure EMC and CE Mark compliance, all replacement parts should be Gatan's parts and all services shall be performed by Gatan personnel or Gatan authorized representatives only.

Safety Ground Label

General Hazard Label

PIPS Owner’s Manual and User’s Guide vii

viii PIPS Owner’s Manual and User’s Guide

Table of Contents

PIPS Owner’s Manual 1

1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.1.1 Features of the Precision Ion Polishing System . . . . . . . . . . .11.1.2 Main Work Chamber . . . . . . . . . . . . . . . . . . . . . . . .31.1.3 Vacuum System . . . . . . . . . . . . . . . . . . . . . . . . . . .51.1.4 Gas-Control System . . . . . . . . . . . . . . . . . . . . . . . . .71.1.5 Electrical System . . . . . . . . . . . . . . . . . . . . . . . . . .9

1.2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101.2.1 Site Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 101.2.2 Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101.2.3 Setting up the Diaphragm Pump. . . . . . . . . . . . . . . . . . 111.2.4 Connecting the Argon Source . . . . . . . . . . . . . . . . . . . 111.2.5 Mounting the Microscope . . . . . . . . . . . . . . . . . . . . . 121.2.6 Aligning the Microscope . . . . . . . . . . . . . . . . . . . . . 12

1.3 Spares and Consumables . . . . . . . . . . . . . . . . . . . . . . . . . . 151.3.1 List of O-Rings . . . . . . . . . . . . . . . . . . . . . . . . . . 161.3.2 List of Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

PIPS User’s Guide 19

2.1 Starting up the PIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2.2 Loading and Unloading Specimens . . . . . . . . . . . . . . . . . . . . 202.2.1 Raising the Specimen Mount/Piston . . . . . . . . . . . . . . . 202.2.2 Lowering the Specimen Mount/Piston . . . . . . . . . . . . . . 20

2.3 Viewing Specimens . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222.3.1 Illuminators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222.3.2 Shutter Control . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.4 Rotating Specimens . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.5 Purging Ion Guns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.6 Adjusting Gun Gas Flow . . . . . . . . . . . . . . . . . . . . . . . . . . 24

2.7 Aligning the Beam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

PIPS Owner’s Manual and User’s Guide ix

2.8 Using the Digital Process Timer . . . . . . . . . . . . . . . . . . . . . . 282.8.1 Setting the Time Base . . . . . . . . . . . . . . . . . . . . . . . 282.8.2 Setting Time Intervals . . . . . . . . . . . . . . . . . . . . . . . 292.8.3 Starting and Stopping the Timer . . . . . . . . . . . . . . . . . . 29

2.9 Ion-Beam Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.9.1 Home Position . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.9.2 Ion-Beam Modulator Panel . . . . . . . . . . . . . . . . . . . . 31

2.10 End-Point Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.11 Sample Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342.11.1 Disc Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . 342.11.2 Pre-Thinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382.11.3 Sample Mounting . . . . . . . . . . . . . . . . . . . . . . . . . 412.11.4 Ion-beam Milling . . . . . . . . . . . . . . . . . . . . . . . . . 48

2.12 Routine Maintenance and Servicing . . . . . . . . . . . . . . . . . . . . 502.12.1 Cleaning the Viewing Window . . . . . . . . . . . . . . . . . . 502.12.2 Cleaning the Airlock Vacuum Seal . . . . . . . . . . . . . . . . 512.12.3 Cleaning Specimen-Mount Assembly . . . . . . . . . . . . . . . 522.12.4 Cleaning the Cold-Cathode Gauge Tube . . . . . . . . . . . . . 542.12.5 Cleaning the Shutter . . . . . . . . . . . . . . . . . . . . . . . . 572.12.6 Care of the Penning Ion Guns . . . . . . . . . . . . . . . . . . . 582.12.7 Molecular Drag Pump Maintenance . . . . . . . . . . . . . . . . 622.12.8 Diaphragm Pump Maintenance . . . . . . . . . . . . . . . . . . 642.12.9 Argon Leak Detection . . . . . . . . . . . . . . . . . . . . . . . 652.12.10 Clean Work Chamber . . . . . . . . . . . . . . . . . . . . . . . 672.12.11 Backing Pressure Calibration . . . . . . . . . . . . . . . . . . . 682.12.12 Microscope-Lamp Replacement . . . . . . . . . . . . . . . . . . 712.12.13 Motor Drive Replacement . . . . . . . . . . . . . . . . . . . . . 72

2.13 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

PIPS Options 75

3.1 Cold Stage Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . 753.1.1 Safety and Serviceability . . . . . . . . . . . . . . . . . . . . . 773.1.2 Controller Specifications. . . . . . . . . . . . . . . . . . . . . . 773.1.3 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773.1.4 Filling the Dewar . . . . . . . . . . . . . . . . . . . . . . . . . 783.1.5 Loading a Sample . . . . . . . . . . . . . . . . . . . . . . . . . 783.1.6 Removing a Sample . . . . . . . . . . . . . . . . . . . . . . . . 79

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3.1.7 Raising the LN Dewar Temperature. . . . . . . . . . . . . . . . 793.1.8 Setting a Sample Temperature. . . . . . . . . . . . . . . . . . . 793.1.9 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . 803.1.10 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 803.1.11 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 823.1.12 Spares and Consumables . . . . . . . . . . . . . . . . . . . . . 953.1.13 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . 95

3.2 Liquid-Nitrogen Trap Option . . . . . . . . . . . . . . . . . . . . . . . 99

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xii PIPS Owner’s Manual and User’s Guide

List of Figures

Figure 1-1 PIPS, front view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Figure 1-2 Work chamber, top view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Figure 1-3 Work chamber, cross-sectional view . . . . . . . . . . . . . . . . . . . . . . . .4

Figure 1-4 Pumping manifold, top view . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Figure 1-5 Vacuum system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Figure 1-6 Gas-Control system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Figure 1-7 Microscope front-to-back alignment . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 1-8 Microscope left-to-right alignment. . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 2-1 Specimen mount in working position . . . . . . . . . . . . . . . . . . . . . . 21

Figure 2-2 Specimen mount in raised position. . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 2-3 Shutter control and light shield. . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 2-4 Operating characteristics of the ion guns. . . . . . . . . . . . . . . . . . . . . 25

Figure 2-5 Beam profile and gas flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 2-6 X and z-alignment drive screws . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 2-7 Alignment ellipse observed in the beam . . . . . . . . . . . . . . . . . . . . . 27

Figure 2-8 Digital process timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 2-9 Autoterminator sensor top and side view . . . . . . . . . . . . . . . . . . . . 32

Figure 2-10 The autoterminator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 2-11 Gatan Model 601 Ultrasonic cutting tool . . . . . . . . . . . . . . . . . . . . 34

Figure 2-12 Gatan Model 659.00001 Disc punch . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 2-13 Cross-section sample preparation, steps 1 and 2 . . . . . . . . . . . . . . . . . 36



Figure 2-16 Gatan Model 623 Disc Grinder. . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 2-17 Disc grinding: Initial and Final. . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 2-18 Sample disc after dimple grinding (not to scale) . . . . . . . . . . . . . . . . . 39

Figure 2-19 Gatan Model 656 Dimple Grinder . . . . . . . . . . . . . . . . . . . . . . . . 40

PIPS Owner’s Manual and User’s Guide xiii

Figure 2-20 DuoPosts, glue type and clamp type . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 2-21 Clamp-type post and loading dock . . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 2-22 Mounting a sample, steps 1 and 2 . . . . . . . . . . . . . . . . . . . . . . . . 44

Figure 2-23 Mounting a sample, steps 4 and 5 . . . . . . . . . . . . . . . . . . . . . . . . 45

Figure 2-24 Mounting a sample, step 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Figure 2-25 Graphite holder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Figure 2-26 Graphite holder loading dock . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Figure 2-27 Viewing window and O-rings . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Figure 2-28 Specimen mount removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Figure 2-29 Specimen-mount and window assemblies . . . . . . . . . . . . . . . . . . . . 54

Figure 2-30 Cold-cathode gauge tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Figure 2-31 Shutter removal and cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Figure 2-32 Ion source and magnet assembly . . . . . . . . . . . . . . . . . . . . . . . . . 59

Figure 2-33 Removal of anode assembly and anode cup insulator . . . . . . . . . . . . . . 60

Figure 2-34 Removing anode cup assembly/front polepiece . . . . . . . . . . . . . . . . . 61

Figure 2-35 Removal of MDP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Figure 2-36 Replacement of oil cartridge . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Figure 2-37 Argon leak-detection points . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Figure 2-38 VAC sensor PCB assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Figure 2-39 VAC sensor interconnects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Figure 2-40 Microscope-lamp replacement . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Figure 2-41 Motor drive removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Figure 3-1 PIPS with cold stage installed . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Figure 3-2 PIPS cold stage in raised position . . . . . . . . . . . . . . . . . . . . . . . . 76

Figure 3-3 PIPS Cold Stage Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Figure 3-4 Sample and conductor temperature over time, stage lowered at zero minutes . . 81

Figure 3-5 Sample and conductor temperature over time, stage raised at zero minutes . . . 82

Figure 3-6 Viewing port and O-rings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Figure 3-7 Interior chamber showing cold conductor with new brushes. . . . . . . . . . . 85

Figure 3-8 Open chamber showing access to cold stage . . . . . . . . . . . . . . . . . . . 86

Figure 3-9 Cold stage with heater disconnected from conductor . . . . . . . . . . . . . . 86

Figure 3-10 Front panel open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Figure 3-11 Removing cables from power supply. . . . . . . . . . . . . . . . . . . . . . . 89

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Figure 3-12 Removing the viewing port. . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Figure 3-13 Removing sputter shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Figure 3-14 Disconnecting cable from Whisperlok . . . . . . . . . . . . . . . . . . . . . . 90

Figure 3-15 Removing Whisperlok screws . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Figure 3-16 Whisperlok assembly removed. . . . . . . . . . . . . . . . . . . . . . . . . . 91

Figure 3-17 Removing the stage spring . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Figure 3-18 Quad-ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Figure 3-19 Correct alignment of bellows assembly . . . . . . . . . . . . . . . . . . . . . 93

Figure 3-20 Inserting Whisperlok assembly. . . . . . . . . . . . . . . . . . . . . . . . . . 93

Figure 3-21 Heater assembly installed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Figure 3-22 Checking the specimen height . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Figure 3-23 Correct beam angle setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

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xvi PIPS Owner’s Manual and User’s Guide

List of Tables

Table 1-1 Main assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 1-2 Chamber assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 1-3 Cabinet assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 1-4 Needle valve assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 1-5 Microscope assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 1-6 Whisperlok assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 1-7 Penning ion gun assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 1-8 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 1-9 List of O-rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 1-10 List of fuses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Table 2-1 Time bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table 2-2 Typical milling rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 2-3 Bulk/rim thickness vs. minimum milling angle . . . . . . . . . . . . . . . . . 49

Table 2-4 PIPS milling parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 2-5 Maintenance operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Table 2-6 Leak-detection flow chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Table 2-7 Troubleshooting guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

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PIPS Owner’s Manual

1.1 Overview

The Model 691 Precision Ion Polishing System (PIPS™) is a self-contained, com-pact, bench-top system designed to produce high-quality TEM specimens with exceptionally large, clean, electron-transparent areas. The PIPS employs single-function manual controls for easy operation.

1.1.1 Features of the Precision Ion Polishing System

1.1.1.1 Dual ion sources

Ion polishing is done by two variable-angle, miniature Penning ion guns. The operating angles of the guns, ± 10 , are independent of one another. Both guns

accurately center the beam onto the specimen at any angle within this range. The guns incorporate powerful rare-earth magnets and are capable of very high thin-ning rates. Each gun is mounted in a universal joint so that the x- and z-alignment drives can be used to center the beams on the specimen. These features make it possible to thin specimens at very low angles in a reasonably short time.

1.1.1.2 Optimum gun design

The gun’s ion optics have virtually eliminated cathode-aperture erosion. As a result, specimen contamination from the ion guns is minimized, and the PIPS requires little gun maintenance and no gun consumables.

1.1.1.3 Stereo microscope

An optical stereo microscope is used to inspect the specimen in its working posi-tion at any time during the thinning process to achieve precise control over the final stage of specimen thinning. This feature is especially important for insulators and semi-conductors since these materials are transparent to light and the interfer-ence-fringe technique can be used to control the final specimen thickness in the region of interest to an accuracy of about ±10 nm.

PIPS Owner’s Manual and User’s Guide 1

Overview

Figure 1-1 PIPS, front view

1.1.1.4 Compact vacuum system

Specimen contamination is reduced with a vacuum system consisting of a molec-ular drag pump (MDP) backed by a two-stage diaphragm pump (DP), both com-pletely contained within the bench-top unit. Additionally, an optional liquid-nitrogen trap further reduces contaminants and water vapor.

1.1.1.5 Versatile sample holders

The Gatan specimen post, for single-sided milling, and the DuoPost, for double-sided milling, eliminate transfer of material onto the specimen by secondary sput-tering from the specimen platform and provide excellent thermal contact with the

2 PIPS Owner’s Manual and User’s Guide

Overview

specimen to reduce specimen heating. Both specimen posts allow the specimen to have an unobstructed view of the ion beam, allowing ion polishing to be per-

formed at angles approaching 0 .

1.1.1.6 Quick sample turnaround time

Quick specimen exchange (<30 sec) is achieved using a miniaturized version of Gatan’s pneumatically controlled Whisperlok™. Specimens can be easily trans-ferred and viewed at frequent intervals during the final moments of the thinning process.

1.1.2 Main Work ChamberFigure 1-2 is a top view of the PIPS main work chamber. The figure shows the right and left ion guns and the Faraday cups opposite each gun to measure the ion beam current. The airlock cover is removed to reveal the main airlock O-ring and a top view of the specimen mount.

Figure 1-3 is a cross-sectional view through the main work chamber of the PIPS. The airlock cover is in place with the specimen in its working position at the cen-ter of the chamber.

Specimens are mounted on posts that plug into the specimen mount and can be milled on both surfaces with proper orientation of the ion beam. One of the guns is

shown inclined at a positive angle (+10 ) to the horizontal (beam incident to the top surface of sample). By simply grasping the gun knob and rotating it, the gun

angle can be reduced down through 0 continuing on to a negative angle (-10 , beam incident to the bottom surface of sample).

The shutter is shown in its inserted position, which prevents sputtered material from being deposited on the specimen viewing window.


Overview

Figure 1-2 Work chamber, top view

Figure 1-3 Work chamber, cross-sectional view


Overview

1.1.3 Vacuum SystemThe PIPS has a compact vacuum system consisting of a molecular drag pump (MDP) backed by a two-stage diaphragm pump (DP). The vacuum system is designed to hold vacuum when the power is turned off. The working vacuum can be reached very quickly when the power is resumed.

1.1.3.1 The pumping system

The MDP has an argon pumping speed of 71 L/sec. It is in series with a 2-stage diaphragm pump (DP) that maintains a backing pressure for the MDP of less than 10 Torr and a chamber base pressure in the 10-6 Torr range. The pumping time from atmosphere to near the base pressure is typically less than 15 minutes. The console is cooled by a single fan mounted on the rear panel that directs air onto the MDP.

1.1.3.2 The pumping manifold

The pumping manifold contains the cold-cathode gauge tube and the MDP, which is offset from the Work Chamber to minimize any possibility of debris falling into the pump (see Figure ).

Pressure is monitored by the cold-cathode gauge tube, which will not turn on unless the MDP is close to its normal running speed.

1.1.3.3 Airlock vacuum

The airlock vacuum is controlled by two pneumatic solenoid valves, SV2 and SV3 (see Figure 1-4). SV2 evacuates the airlock and closes automatically when the airlock is vented. SV3 vents the airlock and can only be actuated when the air-lock switch on the front panel is in the UP position.


Overview

Figure 1-4 Pumping manifold, top view


Overview

Figure 1-5 Vacuum system

1.1.4 Gas-Control SystemThe gas-control system controls the argon gas supply to the ion guns, the Whis-perlok piston, and the pneumatic shutter. The gas-control system consists of a pressure regulator, two normally open three-way solenoid valves, SV4 and SV5, and two normally closed two-way solenoid valves, SV6 and SV7, mounted to nee-dle valves.

Figure 1-6 shows the gas-control system and the hose-clamping points used to quickly find the exact locations of a system gas leak. Refer to Section 2.12.9, “Argon Leak Detection” and to Table 2-6, “Leak-detection flow chart,” on page 65 for explanation of the fault-finding steps.

1.1.4.1 Gas supply to the guns

The PIPS requires a clean, high purity (99.998%) argon supply at 25 psi (1.72 bar). The argon gas for the ion guns is regulated by a pressure regulator that reduces the incoming gas supply from 25 psi down to about 1 psi (69 mbar). Two solenoid valves (SV6 and SV7) control the gas flow to the two guns. Two O-rings form vacuum seals in the gun housing and the ionizing gas is fed into the guns between the O-rings. Solenoid valves SV6 and SV7 shut off the gas supply to each ion gun when the front panel gas-valve switches are operated.


Overview

Figure 1-6 Gas-Control system

NOTE: Do not use the gas-flow controls (needle valves) to shut off gas to the guns. Use the toggle switches instead.

1.1.4.2 Gas supply to the Whisperlok

The Whisperlok assembly is controlled by a normally open three-way solenoid valve (SV4). When SV4 is energized, argon pressurizes the Whisperlok assembly and lowers the piston. When the power to SV4 is switched off, the gas pressure is cut and the piston is raised. This means that in the event of a power failure, the specimen will automatically be raised into the airlock.

1.1.4.3 Gas supply to the pneumatic shutter

The pneumatically operated shutter is designed to minimize sputtered material from depositing on the specimen viewing window and is controlled by the 3-way solenoid valve, SV5. When the power to SV5 is switched off, the shutter piston cylinder is vented and the shutter is opened by the action of a coil spring mounted behind the shutter piston. This means that in the event of a power failure the shut-ter will automatically retract and allow the specimen to rise into the airlock.


Overview

1.1.5 Electrical SystemThe total power consumption of the PIPS is relatively small and varies between 275 W at 60 Hz and 300 W at 50 Hz. The beam energy has been limited to 6.0 keV as the best compromise between maximizing the specimen thinning rate and minimizing specimen radiation damage and heating effects.

1.1.5.1 Air flow

The cabinet interior is cooled by a single fan mounted on the rear panel directing air onto the MDP. The air flow to the fan and the slots on the rear panel should not be blocked since this may cause the MDP to overheat and shut down, possibly damaging other electrical components in the instrument.

1.1.5.2 The circuit

A main power transformer accepts a wide range of input voltages (100 VAC to 240 VAC) and outputs a range of lower AC voltages to a distribution board located next to the transformer. The distribution board regulates and distributes the specific power sources required by the various electrical subassemblies in the system, i.e., 18, 32 VAC (center tapped), and 90 VAC to the HV power supply; 28 VDC for the MDP; 24 VDC to the solenoid valves and LED indicator lamps; and 3.6 VAC for the chamber illuminator.

1.1.5.3 DC power supply

DC power supply for the cold-cathode gauge is mounted on the rear panel just above the fan and is activated when the MDP reaches 60% of the normal running speed. The supply operates from 117 VAC, which is controlled by a relay mounted on the distribution board.

1.1.5.4 HV power supply

The high voltage (HV) power supply provides the ionization voltage and the acceleration voltage for the ion guns. The two voltages are programmed with a defined relationship to give the optimum beam parameters for each beam energy.

The HV supply has safety features built into it such that it will not operate unless the MDP is at its normal running speed, the specimen piston is lowered, the pro-cess timer is running, and the keV Set control is switched on.

1.1.5.5 Standard operating mode

Gatan recommends the PIPS be left running continuously 24 hours a day, seven days a week. This will ensure optimum performance of the vacuum system and the ion guns and minimize or eliminate purge time.


Installation

1.2 Installation

Although the PIPS is a small, bench-top system, it is relatively heavy (38 kg) and should not be lifted by a single person. It can be lifted safely by two people who are experienced in the techniques of lifting heavy objects. Alternatively, proper laboratory lifting equipment should be used.

1.2.1 Site RequirementsThe PIPS requires a sturdy bench top area approximately 1 m (39.3 in.) wide by 50 cm (19.6 in.) deep by 72 cm (28.3 in.) high, located near a power outlet and a source of 99.998% purity argon (Grade 4.8). A molded power cord is supplied with the PIPS to fit the local standard power socket. If the power cord supplied is not suitable, the plug should be replaced with a suitable one. Before connecting the new plug, make sure the voltage requirement conforms to the specifications on the label on the rear panel of the PIPS. The wiring color codes should conform as shown:

A 3-m nylon tubing with compression fittings is supplied to connect the argon cyl-inder to the gas input of the PIPS, located on the rear panel of the console. The PIPS is air cooled and does not require connection to a water supply.

1.2.2 UnpackingBe sure to have the necessary personnel or use proper laboratory lifting equipment when unpacking the PIPS. Follow the steps outlined below.

1. Inspect the exterior and interior of the shipping box for damage.

Note or photograph any external visible damage.Open the box and inspect for any internal damage. If any damage is observed, inform the shipper immediately.

2. Remove the two accessory boxes.

Lift off the top layer of support foam and unfold the protective plastic cover.

3. Lift the PIPS out of the box (see lifting precautions above).

4. Keep all packing material.

Replace all packing material into the shipping box and store in case the instru-ment must be returned for factory repair or maintenance.

5. Verify accessory items.

Live Black or BrownNeutral White or BlueGround Green or Green/Yellow


Installation

Inspect the contents of the accessory boxes against the items ordered and those listed on the packing list.If there are any discrepancies, inform your local Gatan Sales Office immedi-ately.

6. Place the PIPS on an appropriate work bench, close to a suitable power outlet and a cylinder of compressed argon.

7. Proceed with the installation steps described in the following sections.

1.2.3 Setting up the Diaphragm PumpA red locking screw is used to secure the diaphragm pump (DP) to the cabinet base during transit. This screw must be removed before starting the instrument.

Look on the left underside of the PIPS to find this screw. Once removed, the screw should be stored in the nearby threaded hole (toward the front of the unit) so it will be readily available in case the instrument needs to be returned for factory service.

NOTE: Securing the DP prior to shipping is very important. The pump has consid-erable degree of motion within the cabinet due to the flexible isolators used to control pump vibration. If not properly secured, the pump and any components within close proximity may be damaged.

1.2.4 Connecting the Argon SourceNOTE: Be sure the argon supply is properly secured.

1. Adjust your argon tank regulator to 25 psi (1.72 bar).

2. Connect the gas-supply hose.

Connect one end of the nylon gas-supply hose to the regulator on the cylinder bottle.

3. Purge the gas-supply hose.

Crack open the main valve on the cylinder to purge the gas-supply hose.

4. Connect hose to the console.

With the argon flowing, connect the hose to the gas-inlet port on the rear panel of the PIPS.Do not over-tighten the fitting as this may fracture the hose.

5. Check the pressure.

Turn off the main gas valve and check that the pressure reading on the high pressure side of the regulator does not decrease over a 5-min period.This will verify that the gas-inlet line is not leaking.

6. Turn on the main gas valve again to restore the argon supply.


Installation

1.2.5 Mounting the Microscope1. Properly engage the microscope slide into the pivoting slide on the Mani-

fold.

See Figure 1-4.

2. Lower the microscope to its working position.

Rotate the focus knob CCW to lower the microscope to its working position where it can pivot to the left or right rest position.

3. Plug the microscope into the reflection illuminator power jack.

The jack is next to the shutter control switch on the right side of the support plate (see Figure 1-4).

4. Rotate the microscope objective turret to the 2x position.

Adjust the focus knob to clearly view the hex shape at the top of the piston.

1.2.6 Aligning the MicroscopeThe microscope is shipped prealigned so the hex shape at the top of the piston should appear concentric with the microscope field-of-view. Keep in mind the field-of-view is a true image such that if a gap exists between the post and the field-of-view at the 6 o’clock position, the microscope must be shifted toward the rear of the PIPS for centering.

NOTE: Alignment should be performed only when the PIPS is under vacuum and the piston can be lowered into the chamber.

If alignment is necessary, you will need a 1.5-mm and a 3.0-mm hex wrench and a small spanner wrench, all supplied in the accessory kit.

1. Insert a copper specimen post into the top of the piston to use as a target.

See Section 2.2 for instructions on loading a specimen.

2. Turn on the reflection illuminator.

Toggle the illuminator paddle switch toward the front of the instrument (see Figure 1-4). This initiates a timed-interval mode that allows the lamp to remain on for about 3 minutes.

3. Determine the direction the microscope must move to properly center the target.

Front-to-back alignment

1. Loosen sufficiently the two socket-head screws on the pivoting slide.

Use the 3.0-mm hex wrench to loosen the two screws. This will permit the microscope to slide back and forth with minimal side motion.

2. Center the specimen post; tighten the two screws.

Be sure the two socket-head screws are tight before proceeding.


Installation

Figure 1-7 Microscope front-to-back alignment

Left-to-right alignment

1. Loosen the socket-set screw on the pivoting slide.

Use the 1.5-mm hex wrench to loosen the socket-set screw (facing the rear on the pivoting slide itself).

2. Position the microscope.

Look between the microscope slide and the pivoting slide to find a brass cam (see Figure 1-8).Engage the spanner wrench in the cam and rotate left or right in small incre-ments to position the microscope.Rotate CW to move the microscope to the right. Rotate CCW to move the microscope to the left.


Installation

Figure 1-8 Microscope left-to-right alignment

3. Once centered, tighten the set screw.


Spares and Consumables

1.3 Spares and Consumables

Table 1-1 Main assembly

PART NUMBER DESCRIPTION

03510 Fuse (F5) 5 x 20 mm Slo-Blo 1.0A (x5)03602 Fuse (F1, F3, F4), plug-in 3A microfuse (x5)03718 Fuse 3AG Slo-Blo-3A (x5) 120V03722 Fuse 3AG Slo-Blo 1.5A (x5) 220V

Table 1-2 Chamber assembly


07874 Viewing window (x2)

Table 1-3 Cabinet assembly


07194 Programmable timer07616 Cold-cathode ignitor kit (compression ring, O-ring, 3x igni-

tors)

Table 1-4 Needle valve assembly


691.04000 Needle valve assembly

Table 1-5 Microscope assembly


04215 Lamp 2.7 volt T-1 size (x2)

Table 1-6 Whisperlok assembly


691.08102 Piston bellows assembly691.08400 Specimen mount assembly691.08460 Multi-purpose tool691.08470 Beam alignment screen691.08510 Rimmed specimen post (Mo)691.08600 DuoPost, glue type, 3 mm691.08601 DuoPost, clamping type, 3 mm



1.3.1 List of O-Rings

691.08630 Specimen post (copper) 5/Set691.08700 Whisperlok PCB, six sensor

Table 1-7 Penning ion gun assembly


691.09030 Front polepiece691.09040 Anode cup insulator691.09050 Anode cup691.09120 Contact pin691.09131 Magnet assembly691.09530 Potted PCB End cap assembly691.09550 HV feedthrough assembly691.09610 Rear polepiece

Table 1-8 Accessories


623.01100 Mounting wax (3.5 x 32 mm) 12 rods691.11000 Liquid nitrogen trap691.14000 Light shield691.14030 Precision point tweezers691.14051 Specimen post storage block691.14070 Specimen post carrier SS (x4)691.14080 Complete O-ring kit

Table 1-6 Whisperlok assembly (Continued)


Table 1-9 List of O-rings

DESCRIPTION SIZE QTY LOCATION

Main assembly 010 1 Diaphragm pump input hoseChamber assembly 005

011012019022030042044

11311112

Shutter rod sealShutter rod pistonAirlock1, Shutter Guide 2Airlock windowAirlock window retainerFront plateChamber topAirlock top plate or cover



1.3.2 List of FusesThe PIPS is protected by the fuses listed in the following table.

† 3 A if input voltage is 100-120 VAC

† 1.5 A if input voltage is 220-240 VAC

The total power consumption of the PIPS is relatively small and varies between 100 W with guns off and 200 W with guns on. A main power transformer takes a wide range of input voltages (100 VAC to 240 VAC) and outputs a range of lower AC voltages to a distribution board located next to the transformer. This board regulates and distributes the specific power sources required by the various elec-trical subassemblies in the system, e.g., 18 VAC, 32 VAC (center tapped), and 90 VAC to the HV power supply, 24 VDC to the solenoid valves and LED indica-tor lamps, and 3.6 VAC for the specimen illuminators.

Manifold assembly 010012039123136

11111

Vent valveVent valveVent valveCold-cathode gauge tubeChamber flange

Needle valve assembly 012 2 OrificeFaraday cup assembly 015

02222

Current probeHousing

Whisperlock assembly 008031035135

1111

Specimen mountBellows housingCylinder bodyPiston

Penning ion gun assembly 020030

24

HV feedthroughHousing

Liquid nitrogen trap 008039

11

Vent valveBody

Table 1-9 List of O-rings (Continued)

DESCRIPTION SIZE QTY LOCATION

Table 1-10 List of fuses

LOCATION PROTECTS VALUE

Corcom connector on rear panel Main power transformer †Power distribution board (F1) +28 VDC to the pressure sensor board 3 APower distribution board (F2) +28VDC to Purge valve 2.5 APower distribution board (F3) 117 VAC to rear outlet and Penning board 3 APower distribution board (F4) +24 VDC to solenoid valves, fan, gas flow

panel, auto terminator, and dual beam modu-lator board

3 A

Power distribution board (F5) 90 VAC to high voltage power supply 1.0 A


PIPS User’s Guide

The PIPS is relatively simple to operate. The ability of the operator to obtain good TEM specimens depends more on the quality of the starting specimen disks than on any other factor. Specimen-preparation times are relatively short if the starting disks are thin and well polished mechanically.

2.1 Starting up the PIPS

1. Turn on the power to the PIPS.

Press the upper portion of the main power switch (see Figure 1-1). The dia-phragm (DP) and turbomolecular drag pumps (MDP) will start and the digital display on the left side of the front panel will light up. The (amber) DP High indicator will come on and stay on until the backing pressure drops below 12 Torr. After approximately 15 minutes, the MDP indicator will light up (green) indi-cating the MDP has reached 60% running speed. Work chamber pressure appears on the analog meter.

2. Once the chamber pressure is < 5 x 10-4 Torr, turn on the gas-valve switches for both guns.

3. Rotate the gas-flow control knobs CW to the fully closed position, then back them off 3 full turns.

This process will purge the guns. For more detail on gun purging, see Section 2.5. While waiting for the guns to purge, check the following:● The specimen mount is in the raised position. Press the upper part of the

airlock control switch to raise the specimen mount if it is in the lowered position.

● The airlock cover is in place and the airlock chamber is evacuated. If the vent LED is illuminated, the airlock is vented. Evacuate the airlock cham-ber by pressing the VAC button while rotating the airlock cover to make sure the O-ring is well seated.

● Periodically press the DP Test button to monitor the backing pressure (should be <10 Torr) as the airlock chamber is evacuated.The pressure will be displayed on the Beam Energy digital display (center display).


Loading and Unloading Specimens

2.2 Loading and Unloading Specimens

Specimens are mounted either on a Gatan DuoPost or a single-sided specimen post. The specimen post plugs into a specimen mount located at the top of the Whisperlok piston. The following procedure assumes the piston/specimen mount is in the work chamber.

2.2.1 Raising the Specimen Mount/Piston1. Press the upper part of the airlock control switch.

This will raise the specimen mount/piston (see Figure 2-1) into the airlock to allow specimen loading.The piston will not rise immediately but waits for the specimen mount to rotate to its reference or home position (see Section 2.4). The piston then rises and seals off the work chamber from the airlock chamber.

2. Vent the airlock chamber by holding down the Vent button.

Once vented, the airlock’s cover can be removed and a new specimen post can be inserted or an old one removed. A special pair of angled tweezers is sup-plied to facilitate this operation.

NOTE: Do not rotate the specimen mount when exchanging specimens. Any rotation of the mount will displace the home position of the specimen and will cause misalignment for beam modulated milling.

NOTE: When loading a specimen post, make sure it is properly seated in its low-est position. The height of the post is critical if the ion beams are to polish at the center of the specimen.

2.2.2 Lowering the Specimen Mount/Piston1. Replace the airlock cover.

2. Press the VAC button.

Rotate the airlock cover to be sure the airlock O-ring is properly seated.


Loading and Unloading Specimens

Figure 2-1 Specimen mount in working position

Figure 2-2 Specimen mount in raised position

3. Hold down the VAC button and press the DP Test button.

Read the backing pressure on the Beam Energy digital display when the DP button is pressed.

4. Once the airlock chamber pressure reaches the preset level, the green VAC light will illuminate.

5. Press the airlock control switch to lower the specimen mount/piston. See Figure 2-1.


Viewing Specimens

NOTE: If the airlock piston will not go down, check the following things:

● The Vent LED must be Off.If the Vent LED is On, the airlock is still at atmospheric pressure. Evacu-ate the airlock.

● The Rotation Control is in the ON position.At the OFF position, the rotate motor is not rotating so the piston will not lower.

2.3 Viewing Specimens

The PIPS has been designed so that the specimen is clearly visible both with the naked eye or with the stereo microscope either raised (in the airlock) or lowered (in the work chamber). The wide-angle view with the naked eye is necessary when aligning the ion guns using the beam alignment screen (see Section 2.7). The microscope is essential when one uses interference fringes to control the final stages of the thinning process. The microscope is also crucial when observing the final stages of polishing of specimens that do not show interference fringes.

2.3.1 IlluminatorsThe reflection and transmission illuminators used in conjunction with the micro-scope are controlled by corresponding paddle switches on the top support plate of the PIPS (see Figure 1-4 on page 6). When the switch paddle is toggled toward the front of the instrument, the lamp will remain on for approximately 3 minutes. When toggled toward the rear, the lamp will remain on only as long as the paddle is held down. Therefore, the illuminators cannot be accidentally left on for extended periods when not in use.

Figure 2-3 Shutter control and light shield


Rotating Specimens

2.3.2 Shutter ControlThe shutter protects the specimen viewing window from sputter deposits, operates automatically, and works in conjunction with the HV timer. It closes when the timer is counting down and retracts when the timer stops. The shutter will also retract when the piston is raised (since this operation stops the timer).

2.3.2.1 Shutter overrides

A (momentary) manual shutter control switch located on the right side of the cen-ter support plate provides the necessary manual override to allow the specimen or beam alignment screen to be viewed when the ion beams are on. When the switch paddle is toggled toward the front, it retracts the shutter to permit viewing during ion milling. The shutter will remain in the retracted position for approximately 120 seconds, after which it closes automatically. If the switch paddle is toggled toward the rear, the shutter will close immediately.

The illuminator paddle switches can override the shutter control switch so that if you wish to view the specimen while milling, toggle either switch to open the shutter.

The autoterminator (see Section 2.10) incorporates a special shutter-control fea-ture to minimize the amount of sputtered material accumulating on the viewing window.

2.4 Rotating Specimens

The specimen is rotated in a CCW direction by a variable-speed DC motor (see Figure 2-41 on page 72). The rotation speed can be varied from zero (Off) through 6 rpm using the rotation speed control on the front panel. The motor drives a bevel gear mounted to the Whisperlok piston. The gear automatically disengages when the specimen is raised.

Mounted to the bevel gear, as part of the ion beam modulator, is an encoded plate enabling the piston’s rotational angle to be referenced so that the piston rotates to the home position each time the piston is raised. This is discussed in more detail in Section 2.7.

2.5 Purging Ion Guns

The ion guns are very efficient and operate with an extremely low gas throughput. However, even when the argon gas flow to the guns is turned off, small amounts of outgassing from materials in the ion guns will produce significant ion currents (>5 μA). In extreme cases, outgassing will result in sudden bursts of ionization that make the guns unstable in operation. To minimize this effect, the guns must be purged with dry argon. Typically, this is necessary whenever the gun compo-


Adjusting Gun Gas Flow

nents have been exposed to a poor vacuum, i.e., whenever the PIPS has been switched off for more than a few hours or the chamber has been vented.

To purge the guns: 1. HV to the ion guns must be OFF.

2. Switch OFF the right gas control switch.

3. Switch ON the left gas control switch.

Adjust the left needle valve to raise the chamber pressure to 1 x 10-4 Torr.

4. Switch OFF the left gas control switch.

5. Switch ON the right gas control switch.

Adjust the right needle valve to raise the chamber pressure to 1 x 10-4 Torr.

NOTE: Switch on both guns and purge for about 15 minutes. Turn OFF both left and right gas switches and turn ON HV. Confirm maximum beam current of <5 µA is obtained for each gun with an accelerating voltage of 5.0 keV.

2.6 Adjusting Gun Gas Flow

The optimum operating gas flow must be obtained once the guns have been thor-oughly purged. Adjust the flow one gun at a time and without a specimen post or beam alignment screen in place.

NOTE: The post or the screen will block the path between the ion guns and the Faraday cups and will substantially reduce the ion current.

1. Turn off the gas-valve switch for the left gun and work only with the right gun.

2. Set the rotate speed control dial to 3 (rpm).

3. Be sure beam modulator is turned off.

4. Press the VAC button to evacuate the airlock chamber.

5. Toggle the airlock control button to LOWER.

Lowers the piston to its working position.

6. Set the HV timer to 30 minutes and press START.

Scroll with the Up Arrow button to set the interval. Press the Start/Stop button to start the timer.

7. Adjust the ion gun voltage control until the beam energy display indicates 5.0 keV.

8. Adjust the right needle valve.

Rotate the needle valve CCW until the chamber pressure just enters the 10-4 region.


Aligning the Beam

Slowly rotate the needle valve CW to reach the peak current.

9. Operating range

Rotate the needle valve back CCW until the current drops by ~10% to 15% of its maximum value (if peak current is 45 µA, focused current is 38–40 µA). This completes the gas-flow adjustment of the right gun. A typical curve relating operating chamber pressures to ion current is shown in Figure 2-3. The operating range indicated has been chosen because it gives the most focused beam and the highest milling rate.

10. Repeat the procedure for the left gun.

Turn off the right gun gas-valve switch and repeat for the left gun.

11. Be sure both gas-valve switches are turned back on when adjustment to both guns is completed.

NOTE: Variations of ±20% in the performance of the two ion guns are typical and are caused by small differences in the properties of the rare-earth mag-nets used to enhance the gas-ionization rate.

Figure 2-4 Operating characteristics of the ion guns

2.7 Aligning the Beam

The ion beams produced by the guns contain both ions and fast neutrals. Electro-static beam alignment does not work with the fast neutrals and the ion guns in the PIPS must be aligned mechanically. This is done with the aid of the beam align-ment screen.

This screen plugs into the standard specimen mount and is precisely positioned at the standard specimen height. It consists of a 7-mm diameter fluorescent screen with a 0.5-mm diameter hole at its center. After lowering the screen to its standard working position, place the light shield over the airlock (see Figure 2-3) and turn on the guns. The ion beams will be seen through the light shield port as two blue

lines intersecting at 120 on the fluorescent screen.


Aligning the Beam

NOTE: Beam alignment is required only if the x- or z-alignment drives have been accidentally moved, or the guns have been removed for servicing. If one suspects gun misalignment, a quick check with the beam alignment screen will confirm whether there is a problem.

1. Rotate both gun knobs to align the gun angles at 10 Top.

When properly aligned at 10 , there will be no need to realign the guns at any other angle.

2. Turn off the gas-flow switch for the left gun and work only with the right gun.

3. Turn on the rotate speed control and set it at position 3 on the dial.

4. Evacuate the airlock chamber and lower the piston to its working posi-tion.

5. Set the HV timer to 30 minutes.

Scroll with the Up Arrow button to set the interval.Press the Start/Stop button to start the timer.

6. Adjust the ion gun voltage control until the beam energy display indicates 5.0 keV.

7. Vary the gas-flow control (CW and CCW) and note the change in the beam profile.

While viewing the alignment screen, adjust the gas flow until the beam width is a minimum. If gas flow is increased too much, the pressure in the gun will become too high to support a discharge and the ion beam will turn off.

Figure 2-5 Beam profile and gas flow

8. Adjust the z-alignment drive screw (vertical adjust).

While viewing the beam crossing the screen, use the tool provided to adjust the z-alignment drive screw.

NOTE: A portion of the line crossing the screen has a higher intensity than the rest. The higher-intensity zone is elliptical in shape and several


Aligning the Beam

millimeters in length. Adjust the drive screw to center this zone over the center hole in the screen.

Figure 2-6 X and z-alignment drive screws

Figure 2-7 Alignment ellipse observed in the beam

9. Adjust the x-alignment drive screw (horizontal adjust).

Adjust the drive screw to center the beam over the center hole in the screen.

10. Adjust the gas-flow control until the beam is slightly larger than the width of the center hole.

11. Switch off the gas-valve switch for the right gun and repeat the preceding steps for the left gun.

After completing this procedure for each gun, turn on the gas-valve switch to both guns and view both beams on the screen. If the two beams do not precisely inter-sect the screen center, the “x” drive requires further adjustment. Once both lines intersect at the screen center and they appear sharp and bright across the screen diameter, then beam alignment is complete.


Using the Digital Process Timer

NOTE: Narrowing the beam (by increasing the gas flow to the gun) decreases the amount of the beam incident upon the Faraday cup and hence increases the amount of the beam hitting the specimen. (The reverse is true for a smaller ion current.) Some flickering of the beams across the screen is normal and is due to electrostatic charging and discharging of the screen, which is an insulating material.

Once the guns have been aligned, it should not be necessary to realign them for several samples unless someone has tampered with the adjustment. When polish-ing the first specimen, it is recommended that the ion current and the beam angle be noted. When polishing subsequent specimens, adjust the parameters to these values to provide a good degree of beam calibration.

2.8 Using the Digital Process Timer

The process timer is a countdown interval timer with a digital display, an LED to indicate status, and an audible alarm to indicate the end of the timing cycle.

Three buttons control the operation of the timer: the Up and Down buttons, and the Start/Stop button. The first two allow you to set the desired time interval for ion milling. The last controls several functions related to starting and stopping the timer.

2.8.1 Setting the Time Base Timing intervals from 0.1 sec to 23 hr 59 min can be set using four user-selectable programmable time bases.

The instrument is shipped preset to time base Code 1: 59:59 Minutes:Seconds. You can reset it to another time base using the following instructions.

Table 2-1 Time bases

CODE TIME BASE

0 000.1 - 999.9 Seconds1 00:01 - 59:59 Minutes:Seconds2 0001 - 9999 Seconds3 00:01 - 23:59 Hours:Minutes


Using the Digital Process Timer

Figure 2-8 Digital process timer

1. Turn off the main power switch.

2. Press the Down Arrow button while turning on the main power switch.

Release the Down Arrow button once the display comes on.

3. Use the Up Arrow button to select the desired code.

A number from 0–3 will appear corresponding to the codes in Table 2-1. Use the Up Arrow button to select the desired code.

4. Turn off the main power switch and wait 2 seconds.

5. Turn on the main power switch.

The timer will now remain in the new time base unless reprogrammed.

2.8.2 Setting Time IntervalsUse the Up and Down Arrow buttons to set the interval. The longer each button is pressed, the faster the display will change.

2.8.3 Starting and Stopping the TimerNOTE: The Start/Stop button functions differently depending on whether or not

the timer is active.

To start the timer when the timer is not active:

Press the Start/Stop button. This will cause the timer to begin count down of the selected time interval.

The digital display will count the time down until it reaches 0 at which time the audible alarm will sound and the initial preset time will again appear.

To stop the timer when the timer is active:

Press the Start/Stop button.This will stop the timer and turn off the flashing LED. The remaining time will be displayed.

Should it be necessary to change the preset time, press the Up or Down Arrow button to set the new time.


Ion-Beam Modulation

Press the Start/Stop button again to activate the timer and continue timing from the point at which it was stopped.

To reset the timer when the timer is not active:

Press the Start/Stop button.

To reset the timer to the preset time interval, press the Start/Stop button for more than 2 seconds when the Timer is not active.

To reset the timer after a power failure:

Power up the unit.

The timer will remember the last time interval selected and, when powered up, will reset the time to the last 5 seconds in that timing cycle.

2.9 Ion-Beam Modulation

Ion-beam modulation is used primarily for polishing cross-sectional TEM materi-als that are “glued” together or have interfaces of materials of different hardness. Beam modulation consists of fast on/off electronic switching of the guns with variable specimen-rotation speeds within polishing sectors to minimize differen-tial thinning rates of specimens. Variable rotation speeds within the sector of up to 6 rpm are achieved while outside the polishing sector, the speed is fixed at 12 rpm to reduce total specimen preparation time. With this feature, the ion beam is turned off when the support arms of the DuoPost enters the path of the ion beam. This effectively reduces specimen contamination of sputtered material from these parts and extends the life of the post in addition to providing higher quality speci-mens. On particularly fragile specimens, it is preferable to simultaneously work the top and bottom of the specimen to prevent stresses that could break the speci-men. Beam modulation is controlled from the ion-beam modulator panel (see Figure 1-1).

There are two different configurations for beam modulation on the PIPS: single- or dual-beam modulation.

Single-beam modulation

Single-beam modulation activates both ion guns milling a cross section from the front in a single sector subtending an angle of 60° (±30° normal to the glue line). Each ion gun activates once per revolution.

Dual-beam modulation

Dual-beam modulation activates both ion guns milling a cross section from the front and back side in a double sector subtending an angle of 60° (±30° normal to the glue line). Each ion gun activates twice per revolution.

2.9.1 Home PositionWhen loading a cross-sectional specimen, it is important to insert the specimen such that the cross-sectional interface (glue line) is parallel to the front panel

(home position). This procedure ensures that the polishing sectors will be ±30 normal to the glue line during operation of the Beam Modulator. It is also impor-


End-Point Detection

tant to note that the specimen will automatically rotate to this home position before the piston will rise into the airlock.

2.9.2 Ion-Beam Modulator PanelIndicators and toggle switch on the ion-beam modulator panel function as described in the following table.

2.10 End-Point Detection

The PIPS is equipped with a reflection illuminator, a stereo light microscope, and a transmission illuminator. The latter two can be used with the interference-fringes technique to monitor specimen thickness of semiconductors and insulators to aid in end-point detection. With silicon, for example, each colored fringe repre-sents a thickness change of a few hundred Angstroms. When a specimen ceases to produce new fringes, perforation is imminent.

There is usually no warning prior to perforation in the case of opaque materials so the autoterminator can be used to detect perforation. However, the HV timer should be used during the early stages of thinning to prevent accidental overruns.

SWITCH/INDICATOR DESCRIPTION

Single/Off/Double toggle switch

This switch enables selection of single- or double-sector mode. ● SINGLE (up): The system is operating in the single-sector mode. ● OFF (center): Beam modulation is disabled and there is continuous

milling. ● DOUBLE (down): The system is operating in the double-sector mode.

NOTE: In either single- or dual-beam modulation, two-gun operation can be con-verted to single-gun operation by manually switching off one of the gas-valve switches.

Angle Status LED During milling, the LED will illuminate momentarily once per revolution whenever the specimen glue line is at home position (parallel to the front panel). It will be illuminated continuously when the specimen is raised in the airlock for the specimen is in home position. This LED operates independent of the status of the three-position toggle switch.

Beam Status LED This indicator shows the beam status, i.e., amber when the HV to the gun(s) is on and green when the HV is off. This LED is independent of the status of the three-position toggle switch.


End-Point Detection

Figure 2-9 Autoterminator sensor top and side view

2.10.0.1 Perforation detection

Light from the transmission illuminator enters a condensing lens in the autotermi-nator, through an optional optical filter, and is directed onto a sensor to produce a digital readout. When the light intensity is high and the readout exceeds 99, the HV to the guns is switched off and the display will start to flash.

NOTE: An optical filter is normally used when working with transparent materials such as semiconductors and ceramics to reduce the amount of light transmitted. It should not be used with metal specimens or other opaque materials.

NOTE: Contamination of the viewing window can be reduced by delaying the use of the autoterminator until the last stages of the thinning process. To remove the optical filter, unscrew the condenser lens mount and remove the filter.

2.10.0.2 Sensitivity

Operating at maximum sensitivity, the smallest hole the autoterminator can detect in an opaque specimen is approximately 35 µm in diameter. This diameter can be reduced by manually stopping the HV timer before the autoterminator display reaches 99 and visually checking the specimen to determine how much more thin-ning is required.

The actual light level corresponding to a reading of 99 can be adjusted within cer-tain limits using the Sensitivity control on the autoterminator. This control enables the operator to select varying termination hole sizes in the specimen and also to compensate for varying degrees of specimen transparency. The hole should not be allowed to become too large because this may allow the underside of the specimen to become contaminated.

NOTE: Maximum sensitivity setting should be used for metals. Lower sensitivities may be preferred for semiconductors and ceramics. For best results, make sure the specimen viewing window is clean before using the auto-terminator.


End-Point Detection

Figure 2-10 The autoterminator

The autoterminator is mounted on the airlock cover and plugs into a socket located to the right of the pumping manifold. The autoterminator incorporates a special shutter-control feature to minimize the amount of sputtered material accu-mulating on the viewing window. When the autoterminator is in place and the guns are operating, the shutter will open for about 1 second every 120 seconds for sampling of the transmitted light intensity. This corresponds to a total sampling time of 30 sec/h of gun operation. This sampling rate is maintained until the auto-terminator shows 10 on the digital display, whereupon the sampling rate is auto-matically increased to about 1 second every 16 seconds with this rate maintained until termination.

2.10.0.3 Installing the autoterminator

NOTE: The PIPS must be powered on, under vacuum, and with a specimen post (but no specimen) in place.

1. Set up the autoterminator.

Place the autoterminator onto the airlock cover. Plug its cable into the socket by the pumping manifold.

2. Turn down the sensitivity control to its minimum (full CCW) position.

3. Reset the autoterminator.

While holding down the transmission illuminator switch, press the Reset but-ton on the autoterminator. The display will read approximately 90.

4. Increase the sensitivity by one graduation and again reset the autotermi-nator.

The display will begin flashing since the reading will have exceeded the trip point (100).

5. Checkout is complete.


Sample Preparation

2.11 Sample Preparation

The majority of TEM samples ion milled by broad beam instruments are prepared from bulk materials in three broad stages:

● Disc preparation

● Pre-thinning

● Ion milling to electron transparency

2.11.1 Disc PreparationAll TEMs manufactured today require samples that are 3.05mm in diameter. The following methods are suggested to prepare plan view 3mm discs from bulk mate-rial:

1. Polish, slice, or cleave the starting bulk material to obtain a slab about 500um thick.

NOTE: For brittle materials (ceramics, geological materials and semiconductors), the Gatan Model 601 Ultrasonic cutting tool (see Figure 2-11) is ideal to core or cut 3mm discs.

For ductile materials (metals and alloys), use the Model 659.00001 Disc punch (see Figure 2-12) to punch discs without mechanical damage to the central region or tearing of the edges.

Figure 2-11 Gatan Model 601 Ultrasonic cutting tool


Sample Preparation

Figure 2-12 Gatan Model 659.00001 Disc punch

2.11.1.1 Preparing Cross-sectional Sample Discs

TEM cross-sectioned samples are essential for studying the microstructure of multilayered materials. Preparation of cross sections is somewhat more involved than the preparation of regular plan view discs. The preparation of cross sections is greatly facilitated by the use of the Gatan Model 601.07000 Cross-section kit. Follow these basic steps, described in detail in the following sections, to prepare cross-sectional samples:

1. Cut rectangular wafers

2. Coat the stack

3. Pressure bond the stack

4. Cut a cylindrical sample

5. Strengthen the cylindrical sample

6. Slice the reinforced specimen discs

Step 1: Cut rectangular wafers

1. Glue a bulk sample face down onto a glass microscope slide with mount-ing wax.

2. Secure the glass slide to the disc cutter table with mounting wax.

3. Fit the disc cutter with a 4mm x 5mm cutting tool to cut out rectangular dummy wafers. See Figure 2-13.


Sample Preparation

Figure 2-13 Cross-section sample preparation, steps 1 and 2

Step 2:Build a sample stack

A sample stack consists of about six 4mm x 5mm wafers stacked as shown in Figure 2-13.

1. Place the wafers having the surface or interface of interest face to face in the middle of the stack.

If the original bulk sample is only large enough to obtain one or two wafers, the remaining dummy wafers can be cut from pure silicon. An advantage of using silicon for the dummy wafers (even for cross-sectioning other material types) is that during dimpling the interference fringes can be used to accu-rately gauge the sample thickness at levels below 10 µm.

2. After cutting multiple dummy and sample wafers, coat them with a thin layer of G-1 epoxy.

G-1 has characteristics similar to M-Bond 610 epoxy but offers specific advantages:● Faster curing time (5-10 min at 130 °C).● Ease of filling both thick and thin gaps (< 1um) between wafers.● Long shelf life (1 yr without refrigeration).● High temperature stability (heated in a TEM hot stage up to 1000 °C).

Step 3:Pressure bond the sample stack

1. Use the spring-loaded vise to bond the sample stack together during cur-ing.

2. Place the vice on a hot plate for 10 min at 130°C to cure the stack under pressure to obtain a strong thin (< 1um) glue line.

Minimum glue thickness is recommended.


Sample Preparation

3. When the curing process is complete, cool the assembly to room tempera-ture.


Step 4:Cut the cylindrical sample stack

1. Glue the stack into a slotted sample mount with mounting wax.

2. Use a 2.3mm diameter cutting tool to cut a cylinder from the middle of the stack.

Step 5:Strengthen the cylindrical sample stack

1. Glue the 2.3-mm cylinder with G-1 epoxy inside a 3-mm diameter metal reinforcing tube.

2. Cure it for 10 minutes on a hot plate at 130 °C.

NOTE: The tube holds the fragile cross-sectioned structure together during grind-ing, dimpling, ion milling, and subsequent clamping in the TEM sample holder.


Sample Preparation


Step 6:Slice the cylindrical sample stack into sample discs

1. Slice the metal reinforcing tube containing the sample cylinders into a series of 250-400 µm thick discs with a thin blade diamond saw.

See Figure 2-15.

2.11.2 Pre-ThinningThe importance of pre-thinning prior to ion polishing cannot be overemphasized. Pre-thinning is usually done by mechanical grinding and polishing but chemical polishing can sometimes be employed as well. Ion milling is a relatively slow pro-cess so pre-thinning can greatly reduce the time required to make a TEM sample. The shorter the ion-polishing time, the smoother the TEM sample.

2.11.2.1 Mechanical Pre-Thinning

It is now possible to thin samples mechanically all the way to electron transpar-ency so that ion-polishing can be avoided altogether. Unfortunately, mechani-cally-thinned samples are difficult to clean and usually show artifacts due to mechanical damage that can make them unsuitable for most TEM work.

The damage depth depends on many factors, such as the material being thinned, the polishing compound used, and the polishing force applied. For semiconduc-tors, ceramics, and minerals, it appears that TEM samples free from mechanical damage can be obtained if mechanical pre-thinning is performed down to about 5 µm. For metals, the pre-thinning thickness is generally greater than this and usu-ally the optimum value must be determined on a trial and error basis by pre-thin-ning to a smaller and smaller thickness until artifacts start to appear in the TEM samples.


Sample Preparation

Simple parallel grinding techniques can be used to produce large thin areas but the resulting samples are so weak mechanically that they must be glued to a support ring or grid to avoid fracture during subsequent handling. Chances of sample frac-ture during parallel grinding are higher as well.

These problems can be avoided by mechanically pre-thinning the sample in two steps: Disc grinding and Dimple grinding.

Disc Grinding Use the Gatan Model 623 Disc Grinder (Figure 2-16) to mechanically thin the previously prepared 500 µm thick sample discs down to about 40-70 µm (see Figure 2-17).

Figure 2-16 Gatan Model 623 Disc Grinder

Figure 2-17 Disc grinding: Initial and Final

Dimple Grinding Dimple grinding produces a large amount of thin area in the center of the sample disc surrounded by a thick rim (see Figure 2-18). This provides the mechanical strength required for subsequent sample handling. Dimple grinding is achieved using the Gatan Model 656 Dimple Grinder (see Figure 2-19)

Figure 2-18 Sample disc after dimple grinding (not to scale)


Sample Preparation

Figure 2-19 Gatan Model 656 Dimple Grinder

To obtain best results with dimple grinding, follow the steps described below (Refer to the Gatan Model 656 Dimple Grinder User's Guide for detailed operat-ing instructions.)

1. After disc grinding to 40-70 µm, coarse dimple grind the sample with the 15mm phosphor bronze wheel to a thickness of 20-25 µm using 2-4 µm diamond paste, 15-20 gm load and low to medium speed.

2. Dimple polish with felt wheel for 3-5 min using 2-4 µm diamond paste, 20-25 gm load and low to medium speed.

(This is equivalent to a thickness of about 10 µm when measurable, and is possible with transmitted light for certain ceramics and semiconductors.)

3. Dimple polish with a new felt wheel for 5-6 min (or to a thickness of 6-8 µm) using 0-2 µm diamond paste, 20-25 gm load and medium speed.

4. Dimple polish with a new felt wheel for 8-10 min (or to a thickness of about 5 µm) using 0.05 µm Alumina suspension, 20-30 gm load and medium speed.

NOTE: Use different felt wheels for different abrasives to avoid cross-contamination.

Please note that the loads and speeds suggested above work best for silicon and silicon-based materials. For materials that are more brittle, lower loads and speeds are preferable. For most metals and alloys, slightly higher loads and speeds work better.

Also note that samples are normally dimpled from one side only. How-ever, it is extremely important that the side chosen to be the flat side must first be fine polished (0.1-µm abrasive or lower) prior to dimple grinding.


Sample Preparation

2.11.2.2 Chemical Pre-Thinning

Pre-thinning of sample discs is sometimes carried out by electrolytic or chemical jet polishing. Subsequent ion polishing is performed to better control the final thickness of the electron-transparent sample or to reduce the effects of differential chemical attack in multiphase samples. Chemically pre-thinned samples have the advantage of being free from mechanically induced artifacts and can be made extremely thin prior to ion polishing. Ion polishing is also useful for cleaning up electropolished samples that have become contaminated during storage or have areas that are a little too thick for satisfactory TEM imaging or analysis.

2.11.3 Sample MountingAfter pre-thinning, the sample discs are mounted on a PIPS sample holder and placed into the PIPS for ion milling to electron transparency. The sample holder plugs into the sample-mount assembly located in the airlock chamber and can be lowered pneumatically to the working position for ion polishing. The PIPS does not use any sample clamps and hence it will accept a large variety of sample shapes.

Five kinds of sample holders are available with the PIPS:

● DuoPosts (clamp-type and glue-type)

● Graphite holder

● Molybdenum rimmed post

● Copper sample post

2.11.3.1 DuoPosts

DuoPosts are available in two kinds: glue-type and clamp-type. The glue-type DuoPost is used in conjunction with wax to secure the sample. The clamp-type DuoPost employs spring loaded arms to secure the sample in the recess and is used if securing with wax is undesirable. However, using a glue-type holder has its advantages in that the heat transfer rate is much greater due to increased con-tact area. Both posts allow the use of the transmission illuminator and the Auto-Terminator.


Sample Preparation

Figure 2-20 DuoPosts, glue type and clamp type

An important aspect of the DuoPost is its use in conjunction with the beam-modu-lation feature of the PIPS. When mounting cross-sections, the main interface of the sample should be aligned parallel to the support arms of the post and the post then inserted into the sample-mount assembly with the arms parallel to the front panel. This procedure ensures the polishing sectors will be ±30° normal to the interface when using the beam modulator (see Section 2.9 on page 30), thereby effectively minimizing differential milling.

2.11.3.2 Clamp-type DuoPost

The clamp type DuoPost offers fast and easy sample loading. A loading dock is available for use with the clamp-type DuoPost to facilitate sample loading and unloading. Follow the procedure described here for use with this loading dock.

NOTE: This procedure is best performed under a stereo microscope.

Figure 2-21 Clamp-type post and loading dock


Sample Preparation

To mount a sample on a clamp-type DuoPost:

1. Slide the tray back completely.

2. Place the clamp-type DuoPost into the recess of the loading dock.

Use the grooves provided on the post to hold with tweezers.

3. Rotate the knob to open up the gap in the clamp.

4. Rotate one of the knobs on the side of the fixture to open the gap between the upper and lower arms of the clamp.

5. Place the sample into the recess of the sliding tray and slide the tray for-ward.

This will locate the sample in the center of the clamp.

6. Rotate the knob in the opposite direction from step 2, until you hear one click.

This lifts the lower arms of the post and lifts the sample from the tray.

7. Carefully retract the tray from between the arms.

8. Rotate the knob in the same direction until you hear another click.

This step makes the arms of the posts firmly clamp the sample.

9. Rotate the knob in the same direction again, till you hear a third click.

The post is now raised and ready to pick up with a pair of tweezers.

To remove a sample from a clamp-type DuoPost:

1. Transfer the DuoPost to the loading dock and slide the empty tray beneath the sample.

2. Rotate the knob on the side of the fixture to open up the gap between the upper and lower arms of the clamping post.

This motion will place the sample onto the tray.

3. Retract the tray and carefully lift the sample from the tray.

2.11.3.3 Glue-type DuoPost

The glue-type holder requires the use of wax to secure the sample. As a result of the increased contact area, heat transfer during ion milling is greater. Therefore, the glue-type DuoPost is preferred when the sample is heat sensitive.

To mount a sample on a glue-type DuoPost:

Prepare the mounting wax. 1. Using a clean Petri dish, dissolve a small amount of mounting wax in an

equal volume of acetone.


Sample Preparation

Figure 2-22 Mounting a sample, steps 1 and 2

2. Place the sample post in the carrier provided and use a tooth pick to place a thin layer of the diluted wax around the recess edge of the post.

NOTE: This operation is best performed under a stereo microscope. Do not allow any wax to flow into the central hole of the sample post.

3. Evaporate the acetone in air or use a hot plate to form an ultra-thin layer of dry wax.

Position a sample (dimpled side up) on the sample post.4. Carefully center the sample over the dry wax (see Figure 2-23).


Sample Preparation

Figure 2-23 Mounting a sample, steps 4 and 5

Bond the sample to the sample post.5. Transfer the complete assembly to a hot plate to melt the wax and bond

the sample to the sample post.

6. The final position of the sample on the post can be set by quickly trans-ferring the sample post in the carrier from the hot plate to a stereo micro-scope while the wax is melted.

7. Air cool to bond the sample.

Figure 2-24 Mounting a sample, step 8

Transfer the sample post to the PIPS.8. Inspect the sample under the microscope to make sure the center region

of the sample is clean, then transfer the sample post to the PIPS for ion polishing.


Sample Preparation

To remove a sample from a glue-type DuoPost:

1. Dissolve the wax in acetone.

Place the post with sample on a piece of lint-free tissue in a Petri dish contain-ing clean acetone.After a few minutes, the sample will fall off the post onto the tissue.

2. Transfer to a second clean acetone bath.

Pick up the wet tissue with the sample and post on it and transfer them to a second dish of clean acetone.

3. Dry off excess acetone.

Transfer the wet tissue with sample onto a clean, dry tissue to soak up any excess acetone.

2.11.3.4 Graphite Holder

The graphite holder (Figure 2-25) offers quick and easy sample loading/unload-ing. The sample is secured between two independent slides that grip the sample at edge. The graphite holder is most useful for very brittle samples. If heat transfer is a concern, the graphite holder can even be used with low melting point wax. A loading dock (see Figure ), with a built-in high intensity transmission illuminator, is available for use with the graphite holder.

Follow the steps described here for use with this loading dock. This procedure is best performed under a stereo microscope.

Figure 2-25 Graphite holder

To mount a sample on a graphite holder:

1. Completely retract the loading dock tray.

2. Rotate the knob forward completely to raise the post for the graphite holder.


Sample Preparation

Figure 2-26 Graphite holder loading dock

3. Use the grooves on the graphite holder to hold with tweezers and gently plug the holder onto the designated post on the loading dock (see Figure ).

4. Rotate the knob back to completely lower the graphite holder.

5. Place the sample into the recess of the sliding tray and slide the tray for-ward.

6. Rotate the knob forward one click.

This allows the slides of the graphite holder to lift the sample off the tray.

7. Carefully retract the tray completely.

8. Use the holder slides and the transmitted light (for materials that trans-mit light) to center dimple or align a specific area on the sample to the center of rotation in the PIPS (see Figure 2-25).

9. Rotate the knob forward two clicks.

The post is now raised and ready to pick up with a pair of tweezers.

NOTE: The transmitted light comes on and stays on for 3 minutes each time the knob is rotated.

2.11.3.5 Molybdenum Sample Post

The molybdenum sample post is for mounting samples without wax, the post has a raised rim within which the sample is placed. This post allows ion milling only from the top surface and there are heat transfer considerations.


Sample Preparation

2.11.3.6 Copper Sample Post

Unlike the molybdenum post, the copper post does not have a raised rim, therefore sample mounting requires wax. Wax mounting, coupled with good heat conduc-tivity of copper, makes this post very useful for milling extremely heat sensitive materials. However, ion milling is possible only from the top. Also, since copper sputters easily, if the ion guns are misaligned or continue to run after a perforation occurs, re-deposition can be a concern.

2.11.4 Ion-beam MillingOnce the sample disc is pre-thinned and mounted on a sample post, it is then ready to be ion-milled to electron transparency. Follow the steps outlined below:

1. Check gun gas flow adjustment and beam alignment (see Section 2.6 on page 24).

2. Load the sample holder into the sample mount inside the airlock cham-ber and lower it to the working position for ion milling (see Section 2.2 on page 20).

3. Set the gun angles for each gun.

4. Set the rpm using the rotation speed control.

5. Set the desired time interval on the digital process timer (see Section 2.8 on page 28).

6. Toggle the beam modulation switch to “Single,” “Double,” or “Off” (see Section 2.9 on page 30).

7. Press the "Start" button on the HV timer.

8. Adjust the ion beam energy (keV) using the beam energy knob and watching the digital display readout.

9. After milling is complete, unload the sample holder from the airlock chamber (see Section 2.2 on page 20).

2.11.4.1 Milling Rates

Milling rates depend on the relative masses of the ion and sample atom, ion energy, atomic density and crystalline structure of the sample and the angle of incidence of the ion beam. The higher the beam energy and the beam angle, the faster the milling rate.

Shown below are some typical milling rates obtained at a milling angle of 4° for various materials using two ion guns operating at 5.0 keV, a gun current of 25 µA, and sample rotation off.


Sample Preparation

Table 2-2 Typical milling rates

2.11.4.2 PIPS Milling Parameters

As mentioned earlier, higher beam energies (keV) and milling angles lead to higher milling rates. However, they also lead to relatively more damage (on the order of a few nanometers) to the surface of the sample. Lower energies and mill-ing angles produce not just a lower amount of surface damage but also a larger amount of thin area. Therefore, it is essential to arrive at a reasonable compromise between the amount of damage and the milling time.

While setting the milling angles, one must be careful that the rim around the dim-pled sample does not cast a shadow over the central region. Table 2-3 shows the minimum milling angle that can be chosen, depending on rim/initial bulk thick-ness.

NOTE: Values are for samples dimpled down to 5 µm with a 15 mm wheel.

Table 2-3 Bulk/rim thickness vs. minimum milling angle

Use the sample recipe below as a starting guide to choosing PIPS milling parame-ters. This recipe works best for a silicon-based sample of bulk thickness 60 µm dimpled to 5 µm with a 15 mm wheel.

Table 2-4 PIPS milling parameters

MATERIAL MILLING RATE (µM/HR/GUN PAIR)Copper 22Silicon 24

Silicon carbide 16Stainless steel 316 14

Tantalum 8

BULK/RIM THICKNESS (µM) MINIMUM MILLING ANGLE

40 3°50-70 4°70-100 5°

100-150 6°150-200 7°

GUN KEV GUN ANGLE BEAM MODULATION ROTATION TIME

4.0 5° Top3° Bottom

Dual Beam 3 rpm Until perforation reaches area of interest


Dual Beam 3 rpm About 5 min


Dual Beam 3 rpm About 2 min for clean-up


Routine Maintenance and Servicing

2.12 Routine Maintenance and Servicing

The maintenance operations listed in Table 2-5 should be carried out on a routine basis.

NOTE: Use only the special Krytox vacuum grease shipped with the PIPS for all O-rings and any other lubrication requirements.

2.12.1 Cleaning the Viewing WindowThe viewing window should be cleaned on a weekly basis with regular use.

NOTE: This operation can be performed without requiring the PIPS to be shut down and vented.

1. Raise the sample and vent the airlock chamber.

2. Lift off the viewing window capsule.

Table 2-5 Maintenance operations

SECTION OPERATION FREQUENCY SYMPTOM

Section 2.12.1 Clean viewing window Weekly Specimen viewing becomes difficult.Section 2.12.2 Clean airlock vacuum seals Monthly Piston will not fully raise into airlock.Section 2.12.3 Clean Specimen-Mount assembly Monthly Poor vacuum during specimen rotation.Section 2.12.4 Clean Cold-Cathode gauge tube As required Vacuum meter all the way to the right.Section 2.12.5 Clean shutter Every 3 months Sputtered material falling onto specimen.Section 2.12.6 Clean ion gun As required Gun shorted.Section 2.12.7 MDP pump maintenance Every 10,000 hr Required servicing.Section 2.12.8 Diaphragm Pump maintenance Every 25,000 hr Backing pressure above 8 Torr.Section 2.12.9 Argon leak detection As required Excessive argon usage.Section 2.12.10 Clean work chamber As required,

after 2 yearsExcessive flaking of sputtered material.

CAUTION: Do not use acetone as a cleaning agent. It will cause irreparable damage to instrument parts.!



Figure 2-27 Viewing window and O-rings

3. Check and clean the capsule O-rings.

If necessary, replace.

4. Clean the window.

Use a nonabrasive cleaner or a 2–4 µm diamond polishing compound. Replace the window if deposits are too difficult to remove.

5. Replace the window into the capsule O-rings.

6. Replace the viewing window capsule.

7. Evacuate airlock chamber.

Press the VAC button while pushing down on the window to properly seat it.

2.12.2 Cleaning the Airlock Vacuum SealThe airlock vacuum seal should be cleaned on a monthly basis with regular use.

NOTE: This procedure is necessary when the piston cannot be completely raised to its upper position due to buildup of sputtered material on the airlock O-ring.

1. Shut down the power to the PIPS.

Wait at least 10 minutes to allow the MDP to come to a complete stop. Then vent the work chamber by opening the manual vent valve.



2. Lift off the viewing window.

Press the airlock piston down into the work chamber if it hasn’t already low-ered itself.

3. Remove top cover plate.

Using the pin end of the specimen mount removal tool, insert the pin into one of the holes in the top cover plate, push gently and tilt the plate up and out for removal (see Figure ).

4. Remove the smaller O-ring (#012) from its groove in the cover.

Use a wooden toothpick to remove the O-ring. Never use a metal tool to remove an O-ring.

5. Lubricate the # 012 O-ring with Krytox vacuum grease.

6. Clean the underside of the plate and the O-ring grooves with a grease sol-vent.

7. Replace the top cover plate, the viewing window, and close the vent valve.

8. Turn on the power and pump down the system.

Pump down to keep the system free of moisture and minimize oxidation of sputtered materials around the guns.

2.12.3 Cleaning Specimen-Mount AssemblyMilling the bottom surface of specimens will sputter material directly onto the lower window of the specimen-mount assembly. This deposit will reduce the light intensity transmitted by the transmission illuminator and may become a problem particularly when using the autoterminator. For this reason, the specimen-mount and window assemblies can be removed to provide unobstructed access for clean-ing purposes. The O-ring seal on the specimen-mount assembly is a rotating seal that requires frequent cleaning and lubrication (approximately once a month).

NOTE: Removal of the specimen mount can be performed without venting the PIPS.

1. Raise the piston into the airlock chamber and vent chamber.

2. Remove the viewing window and the specimen post, if any.

CAUTION: Do not push down on the piston when removing the specimen mount as this will immediately vent the main work chamber.!



Figure 2-28 Specimen mount removal

3. Remove the specimen mount.

Use the hex end of the specimen mount removal tool to remove the specimen mount. Rotate CCW to unscrew the specimen mount from the piston (see Figure 2-28).

NOTE: If the specimen mount only rotates but does not unscrew, remove the left side cover from the PIPS cabinet and manually restrain the large gear at the bottom of the Whisperlok to prevent it from rotating while the specimen mount is being unscrewed (see Figure 2-28).

4. Remove the specimen-mount assembly from the PIPS.

5. Clean and lubricate the specimen-mount assembly O-ring.



Figure 2-29 Specimen-mount and window assemblies

6. Separate the window assembly from the specimen mount.

Gently pull the two pieces apart.

7. Clean top and bottom surfaces of the window assembly.

The top window surface may be cleaned with a small amount of 2–4 µm dia-mond paste on a cotton swab. The under side of the window should only require cleaning with a tissue.

8. Clean and lubricate the O-ring in the window assembly.

Also clean its mating surface down inside the piston rod.

9. Insert the window assembly back onto the specimen mount.

10. Screw the specimen-mount assembly back into the piston.

Hold the large gear at the bottom of the Whisperlok to prevent the specimen mount from rotating while it is being screwed back in (CW rotation).

11. Replace the side cover and pump down the airlock chamber.

2.12.4 Cleaning the Cold-Cathode Gauge TubeContamination of the measuring chamber within the tube will affect the pressure reading and generally produce an indication that the pressure is poor. If contami-nation becomes severe, instability may occur resulting in shorts that may cause the needle on the vacuum meter to jump to the right end of the scale. If this occurs, the gauge tube must be dismantled and cleaned.

Tools required: Hex wrenches (1.5 mm and 3.0 mm), open-end wrench (7.0 mm), and locking-ring or snap-ring pliers.

To disassemble the gauge tube:




Wait at least 10 minutes to allow the MDP to come to a complete stop. Then vent the work chamber by opening the vent valve.

2. Unplug the connector from the gauge tube.

Unscrew the retaining screw at the center of the connector.

Figure 2-30 Cold-cathode gauge tube

3. Remove the gauge tube.

Pull it straight out from the manifold.

4. Remove the electronic module.

Use the 1.5-mm hex wrench to loosen the set screw on the top of the module and slide the module from the gauge tube (see Figure 2-30).

5. Remove the retainer.

Use the 3.0-mm hex wrench to remove the two socket-head screws at the back of the tube and remove the retainer.

6. Carefully remove the anode, support ring, and Viton O-ring.

These parts can be individually cleaned or replaced if necessary.Use compressed air to blow out loose particles from within the gauge tube.If the inside of the gauge tube must be cleaned with an abrasive, continue with Steps 7 and 8.

7. Separate the anode assembly from the magnet.

Use the 7.0-mm wrench to remove the hex-head screw from the magnet and slide off the anode assembly from the magnet.

8. Remove the locking ring and the pole insert from the front of the measur-ing chamber of the anode assembly.



To clean gauge tube parts:

1. Clean the inside of the tube and the front pole insert. See Figure 2-30.

Use a Scotchbrite pad or polishing cloth (500 grain).

2. Rinse both parts with methanol.

Dry with compressed air or nitrogen gas.

3. Carefully clean the anode and ignitor with a polishing cloth.

The ignitor can be moved on the anode by sliding it up or down. The ignitor is fragile and can easily be damaged, use extreme care when moving or cleaning it. Do not bend the anode pin or damage the ceramic part since it forms the vac-uum seal.

To reassemble the gauge tube:

1. Position the ignitor 20 mm from the end of the anode pin.

2. Insert the O-ring and support ring into the tube.

The sealing surface, O-ring, and ceramic part must be clean.

3. Carefully insert the anode and ignitor into the tube.

4. Replace the retainer and tighten the screws uniformly until the stop posi-tion is reached.

5. Slide the pole insert into the front of the tube and mount the snap ring against the pole insert.

NOTE: Visually check that the anode pin is centered within the hole of the pole insert.

6. Mount the magnet onto the anode assembly.

Lock it with the hex-head screw and clamp.

7. Carefully push on the electronics module until it stops.

8. Position the connector rotated 180º from the magnet retaining screw.

Secure the module snugly in place with the socket-set screw.

9. Replace the gauge tube into the manifold.

Locate the magnet retaining screw into the notch at the bottom of the mani-fold.

10. Plug the connector into the gauge tube.

Secure the retaining screw.

CAUTION: Do not tighten down hard on the set screw.!



11. Close the vent valve, restart the PIPS, and pump down the system.

2.12.4.1 Gauge tube power supply

The gauge tube power supply is mounted on the rear panel just above the fan. It operates from 117 VAC that is controlled by a relay mounted on the distribution board and is activated when the MDP reaches its normal running speed.

2.12.5 Cleaning the ShutterThe pneumatically operated shutter is designed to operate for an extended period of time with only a minimal amount of maintenance. The shutter prevents buildup of sputtered material on the viewing window and instead accumulates material on its underside.

Over a period of time, the accumulated material may crack, peel, and flake off onto the specimen. Venting to atmosphere also may cause the sputtered material to lose adhesion and to peel and flake. For these reasons, the underside of the shut-ter must be examined and cleaned periodically, every 3 months or so with regular use.

Figure 2-31 Shutter removal and cleaning

1. Raise the piston and vent the airlock chamber.


Wait at least 10 minutes to allow the MDP to come to a complete stop. Then vent the work chamber by opening the Vent valve.

CAUTION: Do not allow the PIPS to run for more than 1 hour with the cold-cathode gauge at pressures above 10-3 Torr since a glow discharge will occur in the tube causing it to become contaminated.

!



3. Lift off the viewing window.

4. Press the airlock piston down into the work chamber.

5. Remove the top cover plate with the removal tool (see Figure 2-28).

6. Pull out the shutter guide.

7. Grasp the shutter guide at the front of the chamber and pull it straight out.

There are two O-rings (#012) on the guide that may need periodic cleaning (see Figure 2-31 on page 57).

8. Rotate the shutter manually 180 to view the underside.

9. Use a tissue saturated with freon or methanol and wipe off the underside.

If the shutter is relatively clean, it may only require manual wiping.

10. Remove the shutter for more thorough cleaning.

If a more thorough cleaning is required, the shutter must be removed by unscrewing the M2 x 6 mm retaining screw.

11. Clean the shutter.

Sputter deposits on the shutter should be removed with an abrasive cleaner after which the shutter should be cleaned with hot soapy water and thoroughly dried before replacing in the chamber.

2.12.6 Care of the Penning Ion GunsGood care and maintenance of the ion guns are absolutely essential to obtaining good specimen thinning. The most common problems encountered are gun shorts.

NOTE: The ion guns should only be dry cleaned, use NO solvents.

2.12.6.1 Dry method cleaning

The dry method of cleaning involves wiping the parts with a clean dry tissue, then using dry nitrogen or clean compressed air to remove any dust, lint, or metallic whiskers that are the primary cause of shorts in the guns. This method is preferred because the cleaning time and the actual time the gun parts are out of the vacuum is reduced to a minimum. Additionally, since no solvents are used, the required argon purging time for the guns after start-up is greatly reduced.

To remove the gun: 1. Shut down the power to the PIPS.


CAUTION: The shutter will not operate if the blade is bent by improper handling during cleaning.!



There is no need to unplug the HV cables nor remove any of the side covers from the PIPS.

2. Remove the gun knob from the gun housing.

Rotate the gun knob to the 10 Top position. Use the 3.0-mm hex wrench to remove the two screws from the gun knob and pull the knob from the gun housing.

Figure 2-32 Ion source and magnet assembly

3. Withdraw the ion source from the gun housing.

Use the 3.0-mm hex wrench to remove the single screw from the molded con-nector assembly. Slowly pull on the toggle stick to withdraw the ion source from the gun housing.

NOTE: The use of gloves is recommended in handling all parts. Special attention must be paid to the cleanliness of all the parts, especially the magnet assembly. The disassembly and subsequent assembly should be done with the aid of a x10 stereo microscope.

To disassemble the gun:

1. Remove the magnet assembly from the rear polepiece.

Hold the potted end cap assembly with one hand and grasp the magnet assem-bly with the other hand. Tilt the magnet by pushing from one side near the top and lift off (see Figure 2-32).

NOTE: The rear polepiece can remain on the potted end cap (without disas-sembly). Dust it off using dry nitrogen or clean compressed air. If any particles remain, use a tissue to remove them and dust again with compressed air.

2. Remove the anode cup assembly from the magnet.



Lightly tap the assembly on its edge until enough of the anode protrudes to be pulled out of the magnet.

Figure 2-33 Removal of anode assembly and anode cup insulator

3. Remove the anode cup insulator with the eraser end of a pencil.

4. Separate magnet from the front polepiece.

Holding the magnet in one hand, place the eraser end of a pencil into the mag-net and push against the front polepiece to separate it from the magnet.



Figure 2-34 Removing anode cup assembly/front polepiece

To inspect and clean the gun:

1. Carefully examine the inside face of the front polepiece and the top of the anode cup.

Look for any small whiskers that may cause a short. If burn marks are visible on the front polepiece or the anode cup insulator, the insulator must be replaced.

2. Clean the anode cup.

Clean the anode cup by wiping with a clean dry tissue and dusting it with dry nitrogen or clean compressed air. Clean all the loose sputtered material on the inside surface and the face of the cup using a coarse abrasive pad such as Scotchbrite (brown or red). Wipe clean with a dry tissue and dust with dry nitrogen or compressed air.

3. Remove the O-ring (#020) from the ion source, if necessary.

Squeeze and push up from both sides with thumb and index finger to remove the O-ring from the ion source. Clean, apply vacuum grease (Krytox), and replace (see Figure 2-32).

4. Dust inside the gun housing and the inside face of the front polepiece.

To reassemble the gun:

1. Insert the anode cup into the anode cup insulator (sliding fit).

2. Insert the anode assembly into the magnet assembly (loose sliding fit).

WARNING: Never use polish or fine abrasive on the anode cup or front pole piece as they will be permanently damaged. Use only very coarse abrasive paper (100 grit) or coarse Scotchbrite pad (brown or red).

WARNING: The magnet is extremely powerful and requires careful handling to prevent it from attracting metallic whiskers and from being attracted to any other magnetic material that may shatter it.

!



3. Carefully place the magnet assembly against the edge of the rear polepi-ece.

Slowly lower the magnet assembly in place until the rear polepiece is within the magnet shield. The parts will be perfectly concentric to one another.

4. Slip the ion source into the gun housing.

Pay particular attention that the O-ring is not damaged in the process. Carefully align the white reference dot at the back of the gun to the mating groove machined into the outside diameter of the gun housing.

5. Insert the screw into the molded connector assembly and tighten.

This assembly should be aligned relatively square with the chamber. Guide the knob over the toggle stick until it is firmly in place and screw in the two retaining screws. Repeat this procedure on the second gun if necessary.

2.12.7 Molecular Drag Pump MaintenanceThe MDP requires the oil cartridge to be changed every two years. Refer to pump manual for all maintenance.

The oil cartridge consists of a stack of felt discs saturated with oil and is replaced as a unit. Changing the cartridge requires the chamber to be vented to atmosphere and the MDP to be completely removed from the PIPS. This provides an opportu-nity to service other parts of the vacuum system. The removal of the MDP is made easier if the HV power supply is first removed.

Changing the oil cartridge requires the following:

● Venting the work chamber.

● Removing the diaphragm pump (to facilitate MDP removal) (see Section 2.12.8).

● Removing the HV power supply (to facilitate MDP removal).

● Removing the MDP.

To remove the HV power supply:


Wait at least 10 minutes to allow the MDP to come to a complete stop. Then vent the chamber by opening the vent valve.

2. Unplug the power cord from the power entry module (rear panel).

3. Remove both side covers from the cabinet.

4. Unplug the four gun leads from the HV supply.

5. Unplug the HV power supply cable from the distribution board.

6. Remove the two Phillips-head screws from the HV supply base then lift the HV power supply out.



NOTE: The oil in the MDP is for lubrication of the bearings only, and does not come in contact with the vacuum chamber hence eliminating any concern for hydrocarbon contamination.

To remove the MDP: 1. Remove the control cable from the MDP.

Rotate the connector sleeve CCW and pull the cable straight out.

Figure 2-35 Removal of MDP

2. Remove the SV2–SV3 solenoid-valve assembly.

Loosen and remove the KF clamp and centering ring from the exhaust port in order to remove the SV2–SV3 solenoid-valve assembly.

3. Loosen the 4 MDP mounting screws on the support plate.

Use the 2-mm hex wrench to loosen the screws. These screws retain the flange clamps used to lock the MDP to the manifold. Remove two of the screws and clamps completely; then support the MDP from the underside with one hand while removing the other two screws and clamps.

4. Lower the MDP and remove it from inside the cabinet.

The oil cartridge can be replaced upon removal of the MDP from the cabinet.

To replace the oil cartridge:

1. Cover the input of the pump with aluminum foil.

Place the pump foil-side-down on a clean table (pump is upside down).



2. Use a wide blade screwdriver and unscrew the cap at the bottom of the pump.

Figure 2-36 Replacement of oil cartridge

3. Remove the existing cartridge.

Use a pair of tweezers to remove the cartridge. Properly dispose of the car-tridge.

4. Clean the cover and the oil well from which the cartridge was removed.

5. Insert the new cartridge (already saturated with oil) and install the cap.

6. Remove the foil and remount the MDP.

7. Reconnect the MDP control cable and the valve assembly.

8. Install the HV power supply, plugging in the supply cable, the four gun leads, and screwing in the mounting screws.

9. Install the DP.

2.12.8 Diaphragm Pump MaintenanceIn order to service the diaphragm pump (DP), it must first be removed from the PIPS cabinet. Refer to pump manual for all maintenance.

NOTE: If the PIPS is going to be shipped, the pump assembly must be secured by the special locking screw mounted on the underside of the cabinet.



To remove the diaphragm pump:


Wait at least 10 minutes to allow the MDP to come to a complete stop. Then vent the work chamber by opening the Vent valve.

2. Unplug the power cord from the power entry module (rear panel).

3. Remove both side covers from the cabinet.

This will reveal the MDP and the DP assembly.

4. Unplug the two electrical connectors from the DP.

5. Disconnect the vacuum hose running from the pump to the Tee fitting (mounted on the rear panel).

Unscrew and remove the knurled nut from the pump.

6. Retract the two slide-latch fasteners that hold the pump assembly in place (underside of pump).

7. Lift the assembly out.

2.12.9 Argon Leak DetectionTypically, a bottle of argon gas will last approximately nine months to a year. If a leak is suspected, close off the main valve of the argon cylinder and observe the high pressure gauge. If the pressure deteriorates within a few minutes, a signifi-cant leak is indicated.

NOTE: The leak-detection operation should be performed without shutting down the PIPS, with the Whisperlok lowered, and all four side covers removed from the cabinet. You will need the use of two clamping tools, e.g., nee-dle-nose pliers, hemostat clamps, or Tygon-tubing clamps.

Open the main valve on the argon cylinder and clamp off the hose at the hose-clamping points shown in Figure 2-37. Use the flow chart provided in Table 2-6 to leak test the system.

Table 2-6 Leak-detection flow chart

CLAMPINGPOINTS

PRESSUREDROPS PROBABLE LEAK AREA(S) GO TO

Clamp #1 YesNo

Between clamp #1 and argon bottle.In the rest of the system. Clamp #2

Clamp #2 YesNo

In SV4 and/or subsequent lines.In regulator and/or SV5 and/or subsequent lines.

Clamp #3Clamp #4

Clamp #3 YesNo

In SV4.In work chamber/airlock.

Clamp #4 YesNo

In regulator and/or subsequent lines.In SV5 and/or subsequent lines.

Clamp #5Clamp #6



Clamp #5 YesNo

In regulator and/or SV7 and subsequent lines.In SV6 and subsequent lines.

Clamp #8Clamp #7

Clamp #6 Yes No

In SV 5.In SV7 and subsequent lines.

Clamp #7Clamp #8

Clamp #7 YesNo

In SV6 (leaking to atmosphere).In SV6 (leaking to chamber). With #7 clamped off, chamber pressure will improve.

Clamp #8 Yes No

In regulator.In SV7 and subsequent lines. Clamp #9

Clamp #9 YesNo

In SV7 (leaking to atmosphere).In SV7 (leaking to chamber). With #9 clamped off, chamber pressure will improve.

Table 2-6 Leak-detection flow chart (Continued)

CLAMPINGPOINTS

PRESSUREDROPS PROBABLE LEAK AREA(S) GO TO



Figure 2-37 Argon leak-detection points

2.12.10 Clean Work ChamberClean the work chamber when you have vented the system for other maintenance to reduce overall down time.



2. Lift off the viewing window and the top cover plate from the chamber. See Section 2.12.1.

3. Clean the chamber.

There is no need to polish the chamber. Simply remove flakes of loose sput-tered materials by vacuuming and/or wiping with a Kimwipe. Methanol can be used but it will increase pumpdown time.

4. Replace the top cover plate and the viewing window.

5. Power up the PIPS.



6. Periodically press the DP Test button to monitor pump down.

The system will start evacuating. Monitor the pressure and wait for the green MDP indicator to come on.

2.12.11 Backing Pressure CalibrationThe vacuum system uses an electronic circuit containing two solid-state pressure sensors, one to monitor the foreline pressure generated by the diaphragm pump (DP) and the other to monitor the vacuum in the airlock. These two sensors are mounted to a Vac/Sensor PCB assembly located on the rear panel directly behind the DP.

Figure 2-38 VAC sensor PCB assembly

The foreline sensor is not critical to the operation of the instrument, but simply provides a means of confirming the operational status of the DP. This sensor may be monitored by pressing the DP Test switch on the right side of the front panel and reading the actual pressure (Torr) under Beam Energy on the front meter. This sensor is also connected to the DP High indicator on the top right side of the front panel, which illuminates when the backing pressure exceeds 12 Torr. Should an occasion arise where the readings generated are questionable, some trouble shoot-



ing or calibration of the circuit may be in order. Some typical scenarios are as fol-lows:

2.12.11.1 Scenario 1

If the chamber vacuum is not good (> 1 x 10–4 Torr), the MDP is not at its normal running speed (green MDP illuminator off), the DP High illuminator is on, and the digital display indicates a pressure above 12 Torr, the conclusion is that there could either be a vacuum leak in the system or the DP has failed.

To troubleshoot Scenario 1:

1. Turn on the power to the unit.

Wait at least 2 or 3 minutes to allow pumps to stabilize.

2. Clamp off the hose between the Tee fitting on the rear panel and the MDP.

Use a hemostat or a tubing clamp to clamp off the hose. This isolates the DP from the rest of the vacuum system.● Should the DP High illuminator be extinguished and the digital display

shows the backing pressure dropping to normal levels (< 7 Torr), a vac-uum leak exists somewhere in the main system.

● Should the DP High illuminator stay on and the backing pressure stay high, the DP is likely to be at fault and must be inspected.

2.12.11.2 Scenario 2

If the work-chamber vacuum is good (<1 x 10–4 Torr), the MDP is at its normal running speed (green MDP illuminator on), the DP High illuminator is on, and the digital display is indicating a pressure above 12 Torr, the conclusion is most prob-ably the foreline sensor circuit is out of calibration. Run the following procedure to trouble shoot.

The following items are necessary to perform this procedure: (1) vent-valve assembly; (2) a length of test tubing; and (3) a digital voltmeter.

Scenario 1

SYMPTOM MDP STATUS RESOLUTION

DP High indicator is illuminated and the digital display indicates a pressure above 12 Torr.

MDP not up to speed Possible vacuum leak or DP failure.

Scenario 2

SYMPTOM MDP STATUS RESOLUTION

DP High indicator is illuminated and the digital display indicates a pressure above 12 Torr.

MDP at full speed. Chamber vac-uum good (> 1 x 10–4 Torr). See Figure 2-40.

Check sensor cali-bration.



NOTE: The test tubing must consist of two different sized tubing connected by a fitting or inserted into each other since one end is to be connected to the vent valve (smaller end) and the other to the vac sensor (larger end).

To troubleshoot Scenario 2:

1. The PIPS must be turned off and the vent valve assembly must be in the manifold.

2. Clamp off the hose between the tee fitting on the rear panel and the fore-line sensor.

Use a hemostat or a hose clamp to clamp off the hose at the X in Figure 2-39.

3. Attach the test tubing.

Detach the tubing from the sensor and connect the larger end of the test tubing to the sensor and the smaller end of the test tubing to the fitting on the Vent valve (see Figure 2-39).

4. Connect a digital voltmeter across MON 2 (see Figure 2-38) and ground on the PCB.

The voltage range for the meter will be from -8.5 mV to 7.60 VDC.

5. Start the instrument.

Allow the MDP to come up to normal operating speed (green MDP illumina-tor on) and chamber vacuum at 5 x 10–5 Torr or better.

6. Open the Vent valve.

Allow the tubing and sensor to equilibrate to chamber pressure.

7. Press and hold down the DP Test switch.

The panel display reading should be 0.0; adjust VR3 (Offset 2) trim pot until the digital voltmeter across MON 2 test point reads -8.5 mV (± 3 mV).

8. Close the vent valve and remove the tubing from the vent-valve fitting.

Adjust VR4 (CAL) trim pot until the MON 2 TP voltage is 7.60 VDC (1% of local atmospheric pressure).

9. Reconnect the tubing to the vent-valve fitting and open the valve.

Press and hold down the DP Test switch, the panel display reading should be 0.0 and MON 2 test point -8.5 mV. Adjust VR3 (Offset 2) trim pot if neces-sary.

10. Close the vent valve and remove the tubing from both the Vent valve and the sensor.

11. Connect the vacuum line back to the sensor and remove the hose clamp.

Calibration is complete, the DP High illuminator should be off and the back-ing pressure should read < 7 Torr.



Figure 2-39 VAC sensor interconnects

2.12.12 Microscope-Lamp ReplacementThe microscope lamp is powered at well below its maximum rating and should not require frequent replacement.

1. Pull off the reflector to expose the miniature incandescent lamp (see Figure 2-40).

2. Pull out the lamp, plug in a replacement, and replace the reflector.

NOTE: Gatan replacement lamp is P/N 04215 - Lamp T-1, 2.7V.



Figure 2-40 Microscope-lamp replacement

2.12.13 Motor Drive ReplacementThe specimen motor drive is located under the specimen chamber.

To remove the motor drive:


Wait at least 10 minutes to allow the MDP to come to a complete stop.

2. Unplug the motor from the Whisperlok PC board.

3. Remove the four M2 socket head screws that hold the motor to the bracket (see Figure 2-41).

The motor has specific characteristics for the PIPS and should only be replaced with one of the same type.

Figure 2-41 Motor drive removal


Troubleshooting

2.13 Troubleshooting

Table 2-7 Troubleshooting guide

SYMPTOM PROBABLE CAUSE SOLUTION

MDP Ready, LED does not come on after 10 min.

High backing pressure >8 Torr.Confirm MDP is spinning up (high pitched whine).Vacuum leak.

Check backing pressure.

DP High LED remains on.Backing pressure will not go below 19.9 Torr.

Backing pressure >12 Torr.Manual Vent valve open.Viewing window not seated properly.Defective diaphragm pump.

See Section 2.12.13.Close vent valve.Press down on port and window while pressing VAC button.See Section 2.12.8.

Specimen difficult to see in working position.

Sputtered material obscuring viewing win-dow.

Clean or replace viewing window. See Section 2.12.1.

Specimen will not raise fully into the airlock.

Dry or contaminated O-ring. Service vacuum seal.See Section 2.12.2.

Poor vacuum when specimen mount rotation is operated.

Dirty or dry O-ring in specimen mount assembly.

Clean and lubricate specimen O-ring. See Section 2.12.3.

Piston cannot be lowered into the chamber.

Argon supply interrupted or Rotation Con-trol off.

Check argon pressure 25 psi (1.72 bar) or main valve closed.Turn ON rotation control.

Shutter will not close or closes only part way.

Argon supply interrupted.

Shutter dirty or bent.Shutter piston needs lubricated.

Argon valve closed. Argon pressure below 25psi (1.7bar).Clean or replace shutter blade.Clean and lubricate shutter piston.

Excessive argon use. Argon leak. Check for leaks. See Section 2.12.9.Cold cathode gauge meter pegged to right.

Gauge tube shorted. Service/clean gauge tube.See Section 2.12.4.

Cold cathode gauge meter pegged to left.

Confirm LED at back of gauge tube is ON LED off, either no 24VDC or module bad.

Ion beam current 0.0, keV is good, Argon ON.

Gun shorted, (metal whiskers between anode cup and magnet).

Clean gun. See Section 2.12.6.1.

Ion beam current 0.0, keV is 0.0 or poor.

Gun shorted, (metal whiskers between out-side of magnet and inside of gun).

Clean gun. See Section 2.12.6.1.

Ion beam current very erratic. Guns need purging. Purge guns. See Section 2.5.


Troubleshooting


PIPS Options

3.1 Cold Stage Upgrade

NOTE: This option may be installed at the factory on a new PIPS, or by the cusr-tomer on an existing PIPS. See the PIPS Cold Stage Upgrade User’s Guide for more complete information about installing the Cold Stage option on an existing system.

The PIPS Cold Stage upgrade components replace existing PIPS components as follows:

● The dewar assembly replaces the existing PIPS vent-valve assembly or liquid-nitrogen trap

● The cold stage assembly replaces the existing Whisperlok assembly

● The PIPS cold stage controller connects to the dewar via a cable, and provides a readout of the cold conductor temperature as well as control of two heaters.

The first heater controls the temperature of the cold conductor, and the second is used to boil-off the liquid nitrogen in the dewar. For instance, if a sample has a phase-transition temperature at -100 C that you would like to avoid, the conductor temperature can be set to -50 C prior to inserting the sample. In addition, if the stage is cold and you would like to mill at room temperature, you can set the con-ductor temperature to 23 C.

When the dewar is filled with liquid nitrogen, it cools a copper plate that extends into the specimen chamber. Thin copper strips connect that plate to a cold conduc-tor that sits next to the cold stage spindle. Brushes thermally connect the cold con-ductor to the cold stage spindle. When the Whisperlok is lowered into the milling position, it makes thermal contact with the cold conductor and the sample is cooled. When the Whisperlok is raised into the air lock, it no longer makes ther-mal contact with the cold conductor. The Whisperlok then makes thermal contact with the o-ring in the air lock and comes into thermal equilibrium with the cham-ber walls.

When the stage is in the airlock position, the specimen mount assembly can be removed using the specimen mount removal tool provided with the PIPS. A thin glass disk (window screen) is installed below the specimen mount in order to shield the vacuum window from sputtered material. This disk can be removed and polished clean, or replaced with a 3 mm disk cut from a thin glass coverslip. The


Cold Stage Upgrade

vacuum window cannot be easily cleaned, so it is important that the glass disk is always installed.

Figure 3-1 PIPS with cold stage installed

Figure 3-2 PIPS cold stage in raised position

Dewar

Controller


Cold Stage Upgrade

3.1.1 Safety and ServiceabilityThe PIPS Cold Stage Controller (691.17000) is intended to be used only with a PIPS Cold Stage. There are no user serviceable parts inside the controller. The control cable should only be connected to a PIPS Cold Stage Dewar.

If this system is used in a manner not specified in this manual or in the installation instructions, the safety protection provided by the equipment may be impaired.

3.1.2 Controller Specifications

3.1.3 OperationFill the dewar with liquid nitrogen prior to loading a sample into the PIPS. Once the stage is cold, you may insert and remove samples from the airlock as required.

It is important when removing a cold sample that you allow enough time (10 min-utes) for the sample to warm up after raising the stage and before venting the Air-lock. This will prevent water from condensing on a cold sample.

The controller has a display and two controls on the front panel. The display indi-cates either the temperature reading of the sensor on the conductor, or the set-point of the conductor heater. The mode switch controls the heaters.

When the mode switch is set in the Conductor Heater position, the conductor heater controller is active and pressing the set-point knob displays the conductor set-point temperature. The heater will run constantly until the set point tempera-ture is reached, then it will cycle off until the temperature falls below the set point. This scheme will result in a small variation in temperature at the conductor, but the sample temperature will be constant.

CAUTION: Unplug the AC mains cable of the PIPS before opening the system, to avoid electric shock. Dangerous high voltages and currents may be present inside the case during operation. Do not reach your hands inside the system while the power is on or if the AC mains cable is plugged in.

!

SPECIFICATION VALUE

Weight 5.5 lbs/2.5 kgDimensions 4"H x 5.5"W x 9"D

100mmH x 140mmW x 225mmDClearance Allow clearance to the back for ventilation and cable connections.Power 100-240 VAC, 50/60 Hz, 68 WattsFuse 1.6 A, 250 V, Slo-blowEnvironment 15-35 C, non-condensing Temperature -210 - +100 C Readout Range

-200 - +100 C Control RangeTemperature Sensor Silicon diode


Cold Stage Upgrade

When the mode switch is in the Dewar Heater position, the dewar heater is active. The dewar heater will run constantly until the conductor temperature reaches +23 C, then will shut off. You should manually set the switch to the off position after the dewar heater has shut off. When the mode switch is in the dewar heater posi-tion, pressing the set-point knob will have no effect.

3.1.4 Filling the Dewar1. Raise the stage into the airlock.

2. Fill the dewar with liquid nitrogen. Do not overfill; the starting level should be just below the bottom of the dewar neck.

3. The liquid nitrogen will boil off in a few minutes. Continue refilling the dewar for about ten minutes to replenish the liquid nitrogen.

NOTE: Note: it may take more than one "top off" to initially cool down the dewar.

4. After about ten minutes the boil-off rate will have slowed dramatically. Top off the dewar.

5. Place the supplied lid on the dewar.

6. The system is ready for a sample to be installed. The liquid nitrogen in the dewar should last 3-4 hours if the heater is not being used.

3.1.5 Loading a Sample1. Raise the stage into the airlock (if not already raised).

2. Wait ten minutes

NOTE: It is not necessary to wait if the stage has been in the raised position for at least ten minutes previously.

3. Vent the airlock by holding down the vent button, and remove the airlock cover.

4. Insert sample (specimen post). Be sure the specimen post is properly seated in its lowest position.

5. Replace the airlock cover. Hold down the Vac button.

6. When the Vac light illuminates, press the airlock control switch.

7. After the stage is lowered and begins to rotate, wait ten minutes for the sample to cool down. If your sample has poor thermal conductivity you may want to wait longer.

8. Begin milling.


Cold Stage Upgrade

3.1.6 Removing a Sample1. Raise the stage into the airlock.

2. Wait ten minutes.

3. Vent the airlock by holding down the Vent button, then remove the airlock cover.

4. Remove specimen post.

3.1.7 Raising the LN Dewar Temperature1. Remove the sample (see Section 3.1.6 above).

2. On the PIPS Cold Stage Controller, switch the toggle switch to the Dewar Heater position.

3. Wait until the display reads 23 C and the Dewar Heater LED switches from orange to green. This typically takes less than one hour.

4. Switch the PIPS Cold Stage Controller toggle switch to the Off position.

Figure 3-3 PIPS Cold Stage Controller

3.1.8 Setting a Sample Temperature 1. Raise the stage into the airlock.

2. Fill LN dewar (if not already filled).

3. On the PIPS Cold Stage Controller, set the set-point to the desired tempera-ture.

● Press and hold down the Set-Point knob. The current set-point should be displayed.

● Rotate the Set-Point knob until the desired set-point is displayed.


Cold Stage Upgrade

● Release the Set-Point knob.

4. On the PIPS Cold Stage Controller, switch the toggle switch to the Conductor Heater position. The temperature will rise until it reaches the set point, then will switch off (LED will be green). When the temperature falls below the set point, the heater will turn on again (LED will be orange). The controller will cycle this way as long as it is in the Conductor Heater mode. The sample will not experience temperature swings because there is a long time lag between the conductor and the sample.

5. Lower the stage.

6. Wait ten minutes for the sample temperature to stabilize.

NOTE: The range of the set point for the Conductor Heater is -200 C to 105 C. Setting a set-point temperature lower than the minimum temperature of the stage (~-120 C) will not result in a lower temperature. The controller can only raise the conductor temperature.

3.1.9 RecommendationsFor best results, consider these additional factors:

● Crystal bond can fail at low temperatures, in addition to being thermally insu-lating. If you use a glue-type post or a Cu post, consider using silver paint instead of crystal bond.

● Samples that are thicker at the outside rim will generally have better thermal conductivity. Note that this can limit the range of milling angles that can be used.

● Lower ion beam density results in lower sample temperature. Using the gas flow to defocus the beam will result in lower sample temperatures. Likewise, milling at lower beam energy results in lower sample temperature. If you are using beam modulation, increasing the rotation speed will result in a lower sample temperature.

3.1.10 PerformanceA sample post will reach a temperature of approximately -120 C +/- 25 C. The sample post will typically cool to nearly -100 C in ten minutes. It will reach its lowest temperature in 20-30 minutes. The sample will typically reach the same temperature as the post; how long this takes depends upon the thermal conductiv-ity of the sample and its thickness.

With the ion guns on at 5 kV, 5 degrees, and dual beam modulation a bulk sample (e.g. Ta) mounted in a clamp-type duopost will increase in temperature by about 25-50 C. The temperature of a thin specimen will increase more, depending on the thermal conductivity of the sample, the thickness of the sample, and the power density of the ion beam. In general, lower energy and a more defocused (broader) beam will result in a smaller temperature rise during milling.


Cold Stage Upgrade

The temperature measured at the cold conductor is typically about 50-75 C cooler than the temperature at the sample. In addition, there is a time delay of about ten minutes between a change in cold conductor temperature and the corresponding change in sample temperature. For instance, if the stage is lowered and you fill the dewar with liquid nitrogen, the conductor will reach -100 C about ten minutes before the sample.

Figure 3-4 Sample and conductor temperature over time, stage lowered at zero minutes

NOTE: When the stage is raised into the airlock, the temperature of the sample post will typically increase to nearly room temperature in ten minutes.

PIPS Cold StageSample Temperature vs Time

-200

-150

-100

-50

0

0 10 20 30 40 50 60

Time (min)

Tem

pera

ture

(C)

Sample Temp (C)Conductor Temp (C)


Cold Stage Upgrade

Figure 3-5 Sample and conductor temperature over time, stage raised at zero minutes

3.1.11 Maintenance

3.1.11.1 Cleaning the Airlock Vacuum Seals

The airlock vacuum seals should be cleaned on a monthly basis, with regular use. Lubricating the small o-ring in the top cover plate also serves to lubricate the cold conductor brushes, and to remove worn brush material. Brush lifetime will suffer if the O-ring is not lubricated properly.

NOTE: This procedure is necessary when the piston cannot be completely raised to its upper position due to buildup of sputtered material on the airlock O-ring.

To clean the airlock seals


2. Wait at least ten minutes to allow the MDP to come to a complete stop. Then vent the work chamber by opening the vent valve.

3. Lift off the viewing port.

4. Press the airlock piston down into the work chamber if it hasn't already lowered itself.

5. Remove top cover plate.

● Using the pin end of the specimen mount removal tool, insert the pin into one of the holes in the top cover plate.

PIPS Cold StageSample Temperature vs Time

-200

-150

-100

-50

0

0 5 10 15 20

Time (min)

Tem

pera

ture

(C)

Sample Temp (C)Conductor Temp (C)


Cold Stage Upgrade

● Push gently and tilt the plate up and out for removal.

6. Remove the large O-ring (#044) from the top cover.

7. Remove the smaller Quad-ring (#012) from its groove in the cover.

NOTE: Use a wooden toothpick or an O-ring removal tool to remove the O-ring. Never use a metal tool to remove an O-ring.

8. After cleaning, lubricate with MoS2 powder (supplied with the PIPS Cold Stage) and replace. The quad-ring can be lubricated by placing it in a bag with MoS2 powder and shaking the bag. Then work the powder into the quad-ring with gloved fingers until it is evenly coated. Shake off excess powder.

9. Clean the underside of the plate and the O-ring grooves with a grease solvent.

10. Clean and lubricate the O-rings on the chassis (#044, #042) with silicone vac-uum grease and replace.

11. Replace the top cover plate. Clean the #044 O-ring and the O-ring groove in the top cover plate. Replace the #044 O-ring.

12. Replace the viewing port and close the vent valve.

13. Turn on the power and pump down the system.

14. Pump down to keep the system free of moisture and minimize oxidation of sputtered materials around the guns.

Figure 3-6 Viewing port and O-rings


Cold Stage Upgrade

3.1.11.2 Cleaning the Window Screen

Clean the window screen when the intensity of the transmitted light from below the stage is reduced by deposited material.

1. Raise the stage into the airlock.

2. Remove the specimen post.

3. Remove the specimen mount assembly using the specimen mount removal tool provided with the PIPS. Rotate the assembly counter clock-wise until it is released.

4. Remove the glass window with tweezers.

5. Polish the top side of the window until deposited material is removed and the window is clear.

● Use a nonabrasive material or 2-4 um diamond polishing compound. ● Replace the window if the deposits are too difficult to remove.

6. Re-install the window in the Whisperlok.

7. Replace the specimen mount assembly.

● Make sure the assembly is installed to its mechanical stop, but not over-tightened.

● If the assembly is loose, the sample height will be wrong and the position of the beams will be different for top and bottom gun angles.

3.1.11.3 Checking the Cold Conductor Brush Wear

The brushes that make contact between the cold conductor and the spindle exhibit wear. They are expected to last several years, but should be inspected every six months. The Cold Conductor Assembly brushes can be replaced only with Gatan provided parts, which are designed to meet specific requirements of thermal con-ductivity, electrical conductivity, and lubricity in vacuum.

1. Raise the stage and vent the airlock by pressing the Vent button on the front panel.

2. Turn off the power to the system.

3. Wait ten minutes for the MDP to spin down, then slowly vent the system.

4. Remove the viewing port.

5. Remove the cover using the specimen mount removal tool.

6. Remove the shutter using a small Phillips screwdriver, then remove the sput-ter shield.

7. Visually inspect the brushes for wear.

CAUTION: Do not operate the system without this window because it is not possible to clean the vacuum window below it!!


Cold Stage Upgrade

● The thinnest part of the brushes are 0.050" (1.27 mm) thick when they are new. When the brushes reach a thickness of about 0.015" (.38 mm), they should be replaced.

● Note that there is a mechanical stop which prevents the brushes from wearing too thin.

● If the two sides of the mechanical stop are in contact with each other, then the cold conductor assembly must be replaced.

Figure 3-7 Interior chamber showing cold conductor with new brushes

8. Vacuum out any powder or flakes of brush material that has fallen to the region below the brushes. This material is a normal part of the wear process of the brushes. If an excessive amount of material is built up on the brushes, you may want to remove the cold conductor assembly and clean the material from the brushes with a dry applicator or similar soft material.

3.1.11.4 Replacing the Cold Conductor Assembly

1. Remove the shutter (one Phillips screw).

Specimen mount

Brush (no wear evident)

Mechanical stop


Cold Stage Upgrade

Figure 3-8 Open chamber showing access to cold stage

2. Remove the sputter shield by lifting it upward.

3. Remove the two M2.5 screws and washers on the top of the cold conductor assembly.

4. Move the heater out of the way.

5. Loosen the M2 screw that holds the cold conductor assembly to the bellows assembly.

Figure 3-9 Cold stage with heater disconnected from conductor

6. Carefully lift the cold conductor assembly out of the chamber, making sure not to excessively bend the Cu strips that connect to the cold conductor

Faraday Cup

M2 Screw is at bottom of this hole

Cold Conductor Assy


Cold Stage Upgrade

assembly, or to damage the brushes. You may need to remove the Faraday cups to make room for the Cu strips.

7. Insert the brush arms into the new cold conductor base. Do not install the spring yet.

8. Install the cold conductor base into the system. Be careful not to damage or drop the brushes.

9. Tighten the M2 screw.

10. Install the spring onto the two posts on the brush arms.

● Place one side over the first post, then use tweezers to stretch the spring over the second post. There is an indent in the posts to capture the spring.

● Make sure the brushes are aligned to the spindle (i.e. there is not a gap between them).

11. Attach the Cu strips and heater to the cold conductor assembly with the M2.5 screws and washers. The heater must be installed on top of the Cu strips.

12. Install the sputter shield. Make sure it is not touching any metal part of the cold conductor assembly.

13. Install the shutter.

14. Replace the cover and viewing port.

15. Close the vent valve.

16. Turn on the power and wait for the ion gauge to turn on.

3.1.11.5 Lubricating or Replacing the Piston Quad-seal

A quad-ring separates the chamber from atmosphere and allows for rotation of the piston. If this seal begins to leak, then it should be cleaned and lubricated or replaced. When this seal leaks, a pressure burst is typically observed periodically with each rotation. If this is observed, stop rotation and see if the periodic pressure bursts stop. If you see periodic pressure bursts only when the piston is rotating, then this seal is probably leaking. In this case, follow the procedure below to lubricate or replace this seal.

1. Raise stage and vent airlock.

2. Turn machine off. Wait 10 minutes for the MDP to spin down, then slowly vent chamber.

3. Remove both side covers.

4. Remove front panel screws to allow panel opening.


Cold Stage Upgrade

Figure 3-10 Front panel open

5. If the system has a diaphragm pump (DP) mounted in the left side of the cabi-net, remove and set aside, using the following steps. (Disregard this step if the DP is mounted in an external cabinet.)

● Wait at least 10 minutes from the time the power was shut down to allow the molecular drag pump (MDP) to come to a complete stop. Then vent the work chamber by opening the vent valve.

● Unplug the electrical connector(s) from the DP.● Disconnect the vacuum hose running from the pump to the Tee fitting

(mounted on the rear panel).● Retract the two slide fasteners holding the pump assembly in place

(underside of pump).● Lift the DP assembly out of the cabinet.

6. Unplug the following cables from the high voltage power supply:

● Four ion gun leads connected to the top of the HV supply.● Multi-pin connector on the right side at the base connected to the power

distribution board.● Multi-pin connector at the center front of the switching module (if switch-

ing module is installed).


Cold Stage Upgrade

Figure 3-11 Removing cables from power supply

7. Remove the two screws holding the HV supply to the base of the cabinet. Save these screws to use later. Slide the power supply to the left and remove from cabinet.

8. Remove viewing port.

Figure 3-12 Removing the viewing port

9. Remove top cover using the specimen mount removal tool.

10. Remove shutter (one screw).


Cold Stage Upgrade

Figure 3-13 Removing sputter shield

11. Disconnect cable from the Whisperlok PC board.

Figure 3-14 Disconnecting cable from Whisperlok

12. Using the 2.5mm hex tool, remove the 3 screws retaining the Whisperlok assembly and carefully remove it.

Sputter shield

Shutter

Whisperlok mounting screw

Cable connector


Cold Stage Upgrade

Figure 3-15 Removing Whisperlok screws

Figure 3-16 Whisperlok assembly removed

13. Lift off the bellows assembly from the Whisperlok.

14. Remove the stage spring from the hinged conductor assembly. Use tweezers to lift one side of the spring off of the post, while holding the brush arms in place.


Cold Stage Upgrade

Figure 3-17 Removing the stage spring

15. Remove the brush arms from the hinged conductor assembly.

16. Remove the piston from the bellows assembly. It is helpful to rotate the piston while slowly pulling it out of the bellows assembly.

Figure 3-18 Quad-ring

17. If the quad-ring is damaged or contamination has moved between it and the piston, then remove and clean the quad-ring with a lint-free wipe. Lubricate the quad-ring with Krytox GPL vacuum grease or equivalent, then install it on the piston. If the quad-ring was not damaged and contamination has not moved between it and the piston, then wipe the outside of the quad-ring with a lint-free cloth and re-lubricate it with Krytox GPL-206 vacuum grease.

18. Apply a thin layer of Krytox GPL-206 vacuum grease on the inside surface of the bellows assembly where it contacts the quad-ring.

19. Install the piston into the bellows assembly. Replace the brush arms and the spring on the hinged conductor assembly. Be sure the piston does not lose contact with the brushes, that is, don’t extend the bellows so far that the piston moves below the brushes. The brushes can be severely damaged.

Quad-ring


Cold Stage Upgrade

20. Install the bellows assembly into the Whisperlok assembly.

21. Mount the complete Whisperlok assembly onto the bottom of the chamber. Secure the Whisperlok with three screws.

NOTE: For ease of installation, hold the screws onto the hex key with a small piece of tape.

22. Plug the cable back into the PC board.

Figure 3-19 Correct alignment of bellows assembly

Figure 3-20 Inserting Whisperlok assembly

CAUTION: Ensure correct orientation. The yellow tab with a slot must be aligned to the front of the instrument (within about +/- 2 degrees). Use the screw hole for the shutter as an alignment guide. This will take some care and patience to align correctly.

!

Correct orientation of bellows assembly. Tab of cold conductor base is aligned with the front of the chamber and opposite the motor . This alignment is critical!

Tilt Whisperlok assembly for insertion


Cold Stage Upgrade

23. Attach the copper strips and heater assembly to the hinged conductor as shown in Figure 3-21.

Figure 3-21 Heater assembly installed

NOTE: The temperature sensor is on the underside of the heater assembly, which is attached to the cold conductor assembly. The sample is mounted at the top of the rotating spindle, which is connected thermally to the cold conductor by the spring loaded brushes. For this reason, the temperature displayed on the PIPS Cold Stage Controller is not the same as the sam-ple temperature.

The cold conductor assembly is connected thermally to the dewar by the copper strips. These strips allow the conductor to be heated to a higher temperature than the dewar. Over time the brushes will exhibit wear and should be inspected every 6 months. The cold conductor assembly should be replaced when the brushes have worn to about 0.38mm thick. A mechanical stop under the spring prevents the brushes from wearing beyond this thickness.

24. Insert the sputter shield over the piston and attach the shutter blade.

25. Install top cover and viewing port.

26. Replace the high voltage power supply and diaphragm pump if applicable.

27. Turn on the PIPS main power.

CAUTION: Make sure the sputter shield is aligned accurately to the shutter, so that the shutter will slide into the depression in the shield. Make sure the sputter shield is seated flat against the top of the bellows.

Flex cable must not touch center rib or chamber wall!

Cold conductor

Brush

!


Cold Stage Upgrade

28. Plug control cable from Cold Stage Controller into the electrical connector on the back side of the dewar. Plug Cold Stage Controller power cable into an electrical outlet.

29. Wait for the PIPS to fully power up, then lower stage.

3.1.12 Spares and Consumables

3.1.13 TroubleshootingThe PIPS Cold Stage Controller (691.17000) is intended to be used only with a PIPS Cold Stage. There are no user-serviceable parts inside the controller. If the controller fails, it should be returned to Gatan for service.

NOTE: The cold stage will continue to function without the capabilities of display-ing the conductor temperature and activating the heaters. Do not connect any other equipment to the cold stage dewar connector.

3.1.13.1 Error Codes

The controller checks for open or shorted connections to the sensor and heaters. The following error codes are displayed if an error is detected:


691.17300 Hinged Conductor Assembly, Field Replacement691.14080 Complete O-ring kit691.08405 Specimen Mount691.08452.FR Window Screen (3 mm diameter x 1 mm thick, Qty 10)18824 Spring for Hinged Conductor06985 Quad-ring, viton, #11140138 Quad-ring #012, coated with MoS2691.17305 Molybdenum Disulfide Powder (~1 gram)11371 Fuse, 1.6A, 5x20mm, Slo Blo

ERROR CODE DESCRIPTION

Shr1 Sensor shortedUnd2 Sensor out of rangeOPn3 Sensor open or reversedOPn4 Conductor Heater 1 openOPn5 Dewar Heater 2 openShr8 Conductor heater shorted**Shr9 Dewar heater shorted**EPr1 EEPROM corruptedrEr1 Watchdog timer timed-out


Cold Stage Upgrade

** The system is disabled until the next power-on cycle. If a direct (low resistant) short on a heater occurs, the system will continue to cycle through a reset and start-up causing the front-panel indicators to flash.

3.1.13.2 Pin Assignments

The shielded cable between the controller and the dewar consists of five 24 AWG wires. The connector on the controller side is a Hirose RM12BPE-5PH, and on the dewar side is a Fischer S102A054-130+. The connectors are wired pin 1 to pin 1 through pin 5 to pin 5.

3.1.13.3 Checking the specimen height

The specimen height is pre-set at the factory, and should not need adjustment. The height can be checked by aligning the beams to the center of the beam alignment screen, then changing the gun tilt. It is helpful to increase the gas flow so as to decrease the length of the ellipse illuminated on the screen. As the gun tilt is changed, the beams will increase or decrease in length and rotate about the center of the screen.

Figure 3-22 Checking the specimen height

If the specimen is not held at the eucentric height of the guns, the ellipses will move toward or away from the guns as the tilt is adjusted. See Figure 3-22. This will result in a lower milling rate from below. In extreme cases, there will be rede-position on the bottom surface of the sample. If the center of the ellipse moves by more than about 1 mm, then you should consider adjusting the specimen height as described below. As an alternative, you may designate one gun to be used from the top always and the other gun to be used from the bottom. Align the top gun using the alignment screen as usual, and align the bottom gun using a glass disk

Pin 1 Conductor heater returnPin 2 Dewar heater returnPin 3 Heaters supply voltage (+15 VDC)Pin 4 Temperature sensor supplyPin 5 Temperature sensor return


Cold Stage Upgrade

mounted to a glue type duo-post. In each case, choose the most common average tilt angle; for example 6 degrees top and 4 degrees bottom.

1. Set the specimen height during milling.

The specimen height must be set so that when the tilt of a gun is rotated from top to bottom the beam always strikes the center of the sample. This is illus-trated in Figure 3-23. The beam is typically aligned to the center of the sample when striking the sample from above by using the Beam Alignment Screen provided with the PIPS. ● If the height is set at the correct height, the beam will strike the center of

the sample from both the top and the bottom. ● If the height is set too high, the top beam will be centered and the bottom

beam will strike the sample past the center. ● If the height is set too low, the top beam will be centered and the bottom

beam will strike the sample before the center. ● If the height is set either too high or too low the sample will not mill

evenly on the top and bottom.

Figure 3-23 Correct beam angle setting

2. Mount a 3 mm glass screen (provided with upgrade kit) onto a glue-type Duo-Post. Be sure the screen is flush against the recessed area of the post.

3. Purge the ion guns.

● Switch on the left gun gas-valve switch.● Adjust the gas flow with the left gun gas-flow control until the chamber

pressure is about 1 x 10-4 Torr.● Repeat this procedure for the right gun● Switch on both guns and purge for 15-20 minutes.● Continue purging until a gun current of <8 μA is obtained with an accel-

erating voltage of 5.0 keV and the gas-valve switch is turned off to both guns.


Cold Stage Upgrade

4. Inspect the wires between the left gun and the high voltage power supply. Be sure they are not worn or frayed such that touching them could constitute a danger. You may want to move the high voltage power supply back slightly to allow easier access to the height adjustment screw.

5. Insert the alignment screen into the PIPS.

6. Turn on both guns at 10° top, 6.0 keV, no modulation.

7. Adjust the tilt of each gun to align both beams to the center of the alignment screen. Adjust the gas flow so each beam forms an ellipse on the screen that is about 2-3 mm long. This will require more gas flow than is typically used.

8. Remove the alignment screen and insert the duopost with the glass screen.

9. Turn on both guns at 10° bottom, 6.0 keV, dual-beam modulation.

10. If the height is set properly, the beams will be centered on the glass screen.

11. Adjust the height of the sample by turning the height adjustment screws located on the bottom side of the Whisperlok, using the specimen removal tool that shipped with the PIPS (or a paper clip). There are two height adjust-ment screws, one located on either side of the manifold.

● Insert the small end of the specimen removal tool into one of the small holes cross-drilled in the head of either adjustment screw, then tilt the tool around the screw. Turn the other adjustment screw by the same amount.

● Adjust both height adjustment screws in the same direction until the cen-ter of the beams are halfway between their starting position and the center of the glass screen. It is not critical that both adjustment screws are turned by exactly the same amount, only that they are close.

NOTE: Some newer systems have needle valve assemblies that interfere with this adjustment. If you cannot access the height adjust screw with the specimen removal tool, it may help to move the needle valve assemblies out of the way. Be careful not to pull the gas lines off the needle valve or the chamber while doing this. Remove the gas flow knobs from the front of the system. Remove the nuts from the needle valves (also on the front panel). Pull the valve assemblies slightly into the cabinet assembly and let them hang downward out of the way.

CAUTION: We recommend that you turn off the gun voltage while adjusting the screw, in case the high voltage wires are frayed or worn. Be careful not to touch exposed components or wires on the Whisperlok PCA.

!


Liquid-Nitrogen Trap Option

NOTE: If the height is far off, the beams may not be striking the glass screen. In this case you may want to initially reduce the gas flow so the beams are larger. You may also adjust the tilt of the beams to determine if the sam-ple is too high or too low.

12. Repeat the above procedure until the center of the beams moves less than ~1 mm between 10° top (alignment screen – adjust tilt of guns) and 10° bottom (glass screen – adjust height of stage).

Note that both guns may not be aligned identically. In this case, find the best compromise height for both guns.

3.2 Liquid-Nitrogen Trap Option

The liquid-nitrogen trap option is used to reduce contaminants and water vapor, which is usually the major contaminant of the vacuum system.

To load the dewar: 1. Turn off power to the PIPS.


2. Remove the vent-valve assembly completely from the pumping manifold.

Insert the dewar into the manifold being careful not to pinch the O-ring.

3. Close the vent valve on the dewar.

Specimen mount removal tool

CW = lower heightCCW = raise height(as viewed from above)


Liquid-Nitrogen Trap Option

4. Restart the PIPS.

Wait till chamber pressure is down to around 10-4 Torr.

5. Fill the dewar.

NOTE: Do not overfill the dewar; the starting level should be just below the bottom of the dewar neck. After about 10 minutes, boiling in the dewar will cease and more liquid nitrogen may be added. The dewar will last about 5 hours between refills.


Index

PIPS O

Aair flow 9airlock

cleaning seals 51piston will not go down 22start-up procedure 19venting 20

argonbottle life 65connecting to source 11leak detection 65purging ion guns 23source requirements 10

autoterminatorcheckout 33installation 33optical filter 32perforation detection 32removing optical filter 32sensitivity 32shutter control 23

Bbacking pressure calibration 68beam alignment

about 25beam profile 26gas flow 26when required 25x-alignment 27z-alignment 26

Ccautions iiiceramics, sensitivity setting 32circuitry 9cold-cathode gauge tube, see gauge tubeconsumables part numbers 15conventions, typographical iiicooling system 9

DDC power supply 9dewar, loading 99

diaphragm pumpabout 2installing 11maintenance 64removing 65securing during shipping 11start-up procedure 19

digital process timer, see timerdouble-sided milling 2dry cleaning ion guns 58DuoPosts

double-sided milling 2

Eelectrical system

circuitry 9cooling 9DC power supply 9HV power supply 9list of fuses 17overview 9

end-point detection, see autoterminatorenvironmental requirements 10

FFaraday cups

illustration 3narrow beam 28

fuses list 17

Ggas-control system

gas supply to guns 7gas supply to shutter 8gas supply to Whisperlok 8overview 7

gauge tubecleaning 54location 5power supply 57

Hhardware returns 105horizontal alignment 27

wner’s Manual and User’s Guide 101

HV power supplyabout 9removing 62

Iilluminators

overview 22shutter control 23

installationconnecting argon source 11diaphragm pump 11microscope 12overview 11

ion gunsbeam alignment 25configuration 1disassembling 59dry cleaning 58Faraday cups 3inspecting and cleaning 61maintenance 58operating characteristics 25optimum design 1performance 25purging 23reassembling 61removing 58

ion-beam modulationabout 30beam status 31dual beam 30home position 30panel features 31polishing sector 30rotation speed 30single beam 30

Llamp, replacing in microscope 71light shield 22liquid-nitrogen trap 99

Mmaintenance schedule 50metals, sensitivity settings 32microscope

aligning 12lamp replacing 71mounting 12stereo 1

molecular drag pump (MDP)about 2maintenance 62monitoring pressure of 5

oil cartridge 63overview 5removing 63start-up procedure 19

motor drive, replacing 72mount assembly

cleaning 52raising 20

Nnote, use of iii

Ooil cartridge, replacing 63operating mode, standard 9O-rings

list 16viewing window 51

Ppart numbers

fuses 17O-rings 16spares and consumables 15

Penning ion guns, see ion gunsperforation detection 32pneumatic shutter, see shutterpower requirements 10power supplies, about 9pressure, calibrating 68problems, troubleshooting 73process timer, see timerpumping manifold 5pumping system 5

Rreflection illuminators 22requirements

beam alignment 25environment 10

returns or repairs, equipment 105rotation, specimens 23

Ssemiconductors, sensitivity setting 32sensitivity settings, autoterminator 32shutter

cleaning 57control 23gas supply 8guide 58manual control switch 23


PIPS O

overrides 23overview 23

single-sided milling 2site requirements 10spare part numbers 15specimens

cleaning mount assembly 52fragile 30illuminators 22loading and unloading 20mount assembly 20reducing contamination 2, 30rotation 23short prep times 19

start-up procedure 19stereo microscope 1

Ttimer

about 28operating 29setting time base 28starting and stopping 29

transmission illuminators 22troubleshooting guide 73typographical conventions iii

Uunpacking 10

Vvacuum system

airlock vacuum 5overview 5pumping manifold 5pumping speed 5pumping system 5reducing contamination 2

vertical alignment 26viewing window

cleaning 50O-rings 51reducing contamination 32

Wwarranty information 105weight 10Whisperlok

gas supply 8sample turnaround time 3

work chamber, cleaning 67

wner’s Manual and User’s Guide 103

Gatan Product WarrantyGatan warrants that products manufactured by Gatan shall be free of defects in materials and workmanship for the warranty period, which com-mences at date of shipment. Gatan tests the performance of a unit as part of its final test procedure, prior to shipment from its factory. Gatan war-rants that the unit meets Gatan’s published specifications at time of shipment from its factory. All product warranties provide, for a period of one year after shipment to customer, parts (excluding all normal consumable, wear, and maintenance items) and labor. For Specimen Preparation Equipment and Specimen Holders, Gatan will correct any defects in the instrument either by repair in our facility or replacing the defective part, with the shipping party responsible for shipping costs. For products which attach to the column (Cameras, DigiScan, GIF, and PEELS), travel of up to 100 miles from a Gatan authorized repair center (Pleasanton, CA; Warrendale, PA; Munich, GmbH; and Corby, UK) is included. Travel expenses for service beyond 100 miles will be charged for. Instruments, parts, and accessories not manufactured by Gatan will be warranted by Gatan for the specific items and periods in accordance with and provided by the warranty received by Gatan from the Original Equipment Manufacturer. All such accessory warranties extended by Gatan are limited in accordance with all the terms, conditions, and other provisions stated in this Original Equipment Manufacturer warranty. Gatan makes no warranty whatsoever concerning products or accessories not of its manufacture, except as noted above.Customer ResponsibilitiesThe customer bears the following responsibilities with regard to maintaining the warranty. The customer shall:1. Perform the routine maintenance and cleaning procedures at the required intervals as specified in Gatan’s operating manuals. Failure to per-

form specified maintenance will automatically void warranty.2. Use Gatan replacement parts. Failure to use the specified replacement parts will automatically void warranty.3. Use Gatan or Gatan-approved consumables.4. Provide Gatan authorized service representatives access to the products during normal Gatan working hours during the coverage periods to

perform service.5. Provide adequate and safe working space around the products for servicing by Gatan authorized service representatives.6. Provide access to, and use of, all information and facilities determined necessary by Gatan to service and/or maintain the products. (Insofar as

these items may contain proprietary or classified information, the customer shall assume full responsibility for safe-guarding and protecting them from wrongful use.)

Repairs and ReplacementsGatan will, at its option, either repair or replace defective instruments or components with conforming goods. Repair or replacement of products or parts under warranty does not extend the original warranty period. With the exception of consumable and maintenance items, the replacement parts or products used on instruments out of warranty are themselves warranted to be free of defects in materials and workmanship for 90 days.Any products, part, or assembly returned to Gatan for examination or repair shall have Gatan’s prior approval, with the customer requesting a Returned Material Authorization (RMA) approval. This RMA and the associated RMA number may be obtained through Gatan Service or directly from Gatan’s Warrendale facility at 724-776-5260. If the item is not under warranty, to obtain an RMA, the customer must provide a Purchase Order (PO) for the repair. If the item is under warranty and the customer is requesting an expedited exchange, as may be the case for a printed cir-cuit board, a PO will be required. A credit against this PO will be issued by Gatan upon receipt of the item as returned in accordance with the RMA instructions. The returned item should be shipped prepaid by the customer with the RMA number clearly marked on the exterior of the shipping container and on the enclosed shipping documents. If the returned item is under warranty, return transportation will be prepaid by Gatan. If the returned item is not under warranty, return transportation will be charged to the customer. Warranty LimitationsThe warranty does not cover:1. Parts and accessories which are expendable or consumable in the normal operation of the instrument.2. Any loss, damage, and/or instrument malfunction resulting from shipping or storage, accident (fire, flood, or similar catastrophes normally

covered by insurance), abuse, alteration, misuse, neglect, or breakage or abuse of parts by User.3. Operation other than in accordance with correct operational procedures and environmental and electrical specifications.4. Performance to specifications or safety of use (including X-ray emissions) if the unit is physically installed on, used in conjunction with, or

used as part of a third party’s equipment and is not installed by a Gatan service engineer. 5. Performance to specifications or safety of use (including X-ray emissions) as a result of the use of Gatan’s equipment with that of a third

party due to the third party’s product design.6. Modification of, or tampering with, the system.7. Improper or inadequate care, maintenance, adjustment, or calibration by User.8. User-induced contamination or leaks.9. Any loss, damage, and/or instruments malfunction resulting from use of User-supplied software, hardware, interfaces, or consumables other

than those specified by Gatan.Warranty ExclusionsIn the course of normal use and maintenance, certain parts have finite lifetimes. For this reason, the consumables, wear, and maintenance parts as specified in Gatan’s operating manuals carry a 90-day warranty unless otherwise specified.Post Warranty Period Support and Product ObsolescenceAfter the expiration of the warranty period described above, Gatan will provide service support for Gatan manufactured products at Gatan’s service labor rates and parts pricing in effect at the time of the repair. Gatan will continue to provide billable service support for the products for a period of three years after discontinuance or design obsolescence by Gatan. After this three year period, service support will be offered at the sole discre-tion of Gatan. Liability LimitationsThis warranty is in lieu of and excludes all other expressed or implied warranties, including (but not limited to) warranties of merchantability of fitness for a particular purpose. Under no circumstances will Gatan Inc. or Gatan International be liable for any direct, indirect, special, inciden-tal or consequential damages (including lost profit) or loss of any kind, whether based on warranty, contract, tort, or any other legal theory. The limits of Gatan liability in any dispute shall be the price received from the purchaser for the specific equipment at issue. The laws of the state of Pennsylvania apply to all aspects of this warranty.

Declaration of Conformity(According to ISO/IEC GUIDE 22 and EN 45014)

Manufacturer’s Name: Gatan Inc.Manufacturer’s Address: 5933 Coronado Lane

Pleasanton, CA 94588 U.S.A.

DECLARES THAT THE PRODUCT

Product Name: Precision Ion Polishing System

Model Number: 691

CONFORMS TO THE FOLLOWING EUROPEAN DIRECTIVES

Low Voltage Directive 73/23/EECEMC Directive 81/336/EECAs Modified by Directive 93/68/EEC

I, the undersigned, hereby declare that the equipment specified above conforms to the above Directives and Standards.

Place: Pleasanton, CA Signature:

Date: November 1998 Full Name: Robert Buchanan

Position: President and CEO

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