general purpose and p-type mini-brute ......3.3.5 pick up the quartz push rod (see fig. 11) notice...

GENERAL PURPOSE AND P-TYPE MINI-BRUTE FURNACE SYSTEM OPERATING PROCEDURE Version: 1.0 June 2012

UNIVERSITY OF TEXAS AT ARLINGTON

Nanofabrication Research and Education

Center

DOCUMENT: MINI-BRUTE FURNACE SYSTEM OPERATING PROCEDURES Version: 1.0

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TABLE OF CONTENTS

1.0 INTRODUCTION…………………………………………….…….… 3

1.1 SCOPE OF WORK…………………………………….…....... 3

1.2 DESCRIPTION…………………………………….…….……. 3

1.3 SAFETY……………………………………………....…..….. 3

2.0 HARDWARE..............................…………………………….….... 3

3.0 OPERATING PROCEDURES.………………………..…..………...... 4

3.1 PREPARING THE SYSTEM FOR PROCESSING.….…..……..... 4

3.2 LOADING THE FURNACE…………..……...…….….…..……. 8

3.3 PROCESSING YOUR WAFERS….…………..…….……...... 10

3.4 FURNACE SHUTDOWN……………………………………... 12


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1.0 Introduction

1.1 Scope

These procedures apply to the Mini-Brute General Purpose and P-Type

furnace systems. All maintenance should follow the procedures set forth in

the manufacturer’s maintenance and operations manuals. This document

is for reference only. Users must be trained by Nanofab staff before

operating this equipment.

1.2 Description

The Mini-Brute General Purpose furnace is for wet/dry oxidation and

annealing processes. The P-Type Mini-Brute furnace is intended to be

used for P-Type silicon doping processes. Both furnaces are capable of

operating to 1200 Deg C.

1.3 Safety

Due to the high operating temperatures associated with these system’s

extreme caution should be observed when handling any components that

have been inside or near this system. Always use the heat insulating

gloves when touching any component used in the system.

2.0 Hardware

2.1 Resistive heating element furnaces

2.2 Analog TC based temperature controllers

2.3 Manual N2 & O2 flow metering, 4 lpm maximum flow


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3.0 Operating Procedures

3.1 Preparing the system for processing

** System Note ** If you are going to run a new process it is highly

recommended that you first run a trial process by heating the

furnace without a sample and verifying the temperature set point

setting with the hand held digital TC meter. This takes more time but

will result in the most accurate process temperature. To do this,

perform the following procedures, but load an empty quartz boat

when prompted to load your sample.

3.1.1 Go the service chase directly behind the system and turn ON the main

power contactor for the furnace you intend to run by lifting the RED

handle to the ON position. The power contactors are located on the wall

to the right of the system (Fig. 1). The labels on the power contactors

indicate which furnace they supply power to. Only turn on the power to

the furnace you need to run.

(Fig. 1)

Power

Contactors


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3.1.2 While in the service chase you may now turn ON the process gas you will

be using and set up your gas flow by adjusting the GAS FLOW

METERING VALVES. If O2 will be used then it will be necessary to open

the O2 cylinder valve. The O2 cylinder is located next to the system and

is visible in the picture (Fig. 2). If N2 gas will be used there is no cylinder

valve to open, N2 is supplied by the bulk N2 system and is always on.

The gas flow meters can only supply gas to one furnace at a time. Ensure

that the GAS SELECTOR VALVE is rotated so that gas flow is being

provided to the proper furnace. Rotate the GAS SELECTOR valve of the

desired gas to point UP for the upper furnace and DOWN for the lower

furnace.

(Fig. 2)

3.1.3 If you will be performing a Wet Ox process then you should now fill and

begin heating the water reservoir located at the rear of the system. Ideally

the water should begin a very slight boil by the time the furnace has fully

heated. O2 can be set up to flow through the bubbler to act as a carrier

gas during processing.

Gas flow

metering

valves

Furnace

gas

selector

valves

O2 Cylinder


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3.1.4 Return to the front of the system and turn ON both of the front panel

power switches (Fig. 3).

(Fig. 3)

3.1.5 Set the desired Boat-In temperature. Boat-In temp is typically ≤ 500

Degrees and maintains a lower risk of thermal shock and breakage of the

sample. To adjust the temperature set point turn only the MIDDLE

SETPOINT KNOB to a value that when added to the REAL TEMP ADD

number (Fig. 4) will match the desired BOAT-IN temperature. Example

shown In the image below the requested process temp would be 500 +

180 = 680C set point. NEVER adjust the outer two knobs they adjust

the outer two heating zones relative to the center zone. Setting them

to a value other than where they are set can result in incorrect

process temperatures.

(Fig. 4)

500 + 180

= 680C

setpoint.

DO NOT

ADJUST


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3.1.6 After a period of time [typically 30 minutes or more] the system front panel

TEMPERATURE INDICATOR (Fig. 5) will stabilize at the desired BOAT-

IN temperature.

(Fig. 5)

3.1.7 If you are unsure of the accuracy of the front panel meter you may use

the long furnace thermocouple and a hand held digital temperature meter

(Fig. 6) to verify the furnace temperature. If the temperature indicated is

incorrect then adjust the MIDDLE SETPOINT KNOB (See Fig. 4) and let

the temperature stabilize for a few minutes. Contact a staff member if you

are unsure of this procedure.

(Fig. 6)


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3.2 Loading the Furnace

3.2.1 Load the wafers to be processed into a Mini-Brute compatible quartz boat

(Fig. 7). If multiple wafers will be processed at the same time then it may

be appropriate to space the wafers apart by several slots. If a sample

smaller than a 4” wafer will be processed contact a staff member to assist

you in setting up your process run.

(Fig. 7)

3.2.2 Put on the HOT WORK GLOVES and remove the QUARTZ END CAP

from the furnace. Sit the quartz end cap on top of the FIBERGLASS

INSULATING PAD (Fig. 8) on the table directly below the furnace.

Warning - the quartz end cap will be extremely hot, do not allow it to

touch anything other than the insulating pad.

(Fig. 8)


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3.2.3 Sit the quartz boat and sample into the BOAT LOADER (Fig. 9).

(Fig. 9)

3.2.4 Hold the BOAT LOADER in a position straight in-line with the furnace

tube opening. Using the QUARTZ PUSH ROD (Fig. 10) begin pushing

the quartz boat slowly into the furnace. Once the quartz boat has been

pushed completely off of the boat loader you may sit the boat loader back

on the rack.

(Fig. 10)


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3.2.5 Continue using the quartz push rod (Fig. 11) to push the boat/samples

until they are located in the center of the furnace.

(Fig. 11)

3.2.6 Once the quartz boat has been pushed to the center of the furnace

reinstall the QUARTZ END CAP (Fig. 12) which you removed earlier. Be

careful to only put it on loosely, DO NOT PUSH THE END CAP

COMPLETELY FLUSH/TIGHT WITH THE FURNACE OR ELSE IT WILL

LOCK IN PLACE AND YOU WILL NOT BE ABLE TO REMOVE IT.

(Fig. 12)

3.3 Processing Your Wafers

3.3.1 Once the Quartz End Cap has been properly reinstalled onto the end of

the furnace you may now set the MIDDLE SETPOINT KNOB to the

setting that when added to the REAL TEMP ADD number will give you

the desired PROCESS TEMPERATURE SET POINT (See Step 3.1.4).

The furnace should now begin heating to the desired process

temperature. As soon as the correct temperature is displayed on the

TEMPERATURE INDICATOR (See Fig. 5) proceed to the next step.


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3.3.2 If a Wet Ox or Dry Ox process is going to be run you may now turn OFF

the N2 flow and then turn ON the O2 flow, ensure that the steam injector

is connected to the furnace.

3.3.3 Begin timing the process with a stop watch, once the necessary process

time has elapsed turn OFF both of the FRONT PANEL BREAKERS (Fig.

13). Immediately go to the service chase and turn OFF the O2 gas flow if

an oxidation was being run and then turn ON the N2 gas flow. DO NOT

TURN OFF THE MAIN POWER CONTACTOR IN THE SERVICE

CHASE AT THIS TIME. The furnace will now begin cooling. Allow the

furnace to cool to the desired BOAT-OUT temperature as displayed on

the front panel temperature indicator (See Fig. 5) before proceeding to

the next step. BOAT-OUT temp is typically ≤ 500 Degrees and maintains

a lower risk of thermal shock and breakage of the sample.

(Fig. 13)

3.3.4 You may now begin the BOAT-OUT process. Put on the HOT WORK

GLOVES again and remove the QUARTZ END CAP sitting it on the

FIBERGLASS INSULATING PAD (See. Fig. 8) on the table directly

below the system.

3.3.5 Pick up the QUARTZ PUSH ROD (See Fig. 11) notice it has a hook on

the end of it. Use this hook to engage the quartz boat and slowly pull it

out of the furnace until it reaches the edge of the furnace opening and

then stop.

3.3.6 Align the BOAT LOADER straight in-line with the furnace opening (See

Fig. 10).

3.3.7 Using the QUARTZ PUSH ROD begin pulling the quartz boat out of the

furnace and onto the BOAT LOADER. If the boat loader is being properly

used the TUBE & BOAT LOADER will line up perfectly and allow the

boat to slide out of the furnace without any disturbance to your sample.


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3.3.8 Once the boat has been pulled completely out of the furnace leave the

QUARTZ BOAT in the BOAT LOADER and sit them onto a stable

surface. Allow the quartz boat/sample to cool for a minimum of 5 minutes

before attempting to unload the sample. Care should be observed as the

sample can still be hot.

3.3.9 Once the quartz boat has cooled completely, place both the QUARTZ

BOAT and the BOAT LOADER back in their respective storage locations.

3.4 Furnace Shutdown

3.4.1 Allow the furnace to cool to < 200C as indicated on the system’s front

panel temperature indicator (See Fig. 5). This must be done before

proceeding to the next step or system damage can result.

3.4.2 Turn OFF all gas flows to the system and close the O2 cylinder valve if it

was opened earlier (See step 3.1.2).

3.4.3 Go to the service chase directly behind the system and turn OFF the

main power contactor (See Fig. 1)

general purpose and p-type mini-brute ......3.3.5 pick up the quartz push rod (see fig. 11) notice...

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