standard operating manual - hong kong university of ...mfz140.ust.hk/eq_manual/sop of lam 490...

NANOSYSTEM FABRICATION FACILITY (NFF), HKUST

Copyright © 11.2015 by Hong Kong University of Science & Technology. All rights reserved.

Standard Operating Manual ___________________________________________________________

LAM490 AutoEtch System



Contents

1. Picture and Location

2. Process Capabilities

2.1Cleanliness Standard

2.2 Possible Etching Materials

2.3 Process Specification

2.3.1What the LAM490 CAN do

2.3.2. What the LAM490 CANNOT do

2.4 Etching Process Useful Information

3. Useful information to work in NFF

3.1 Emergency Responses and Communications

3.2Become a Qualified LAM490 User

4. Operating Safety and Rules

4.1 Operation Safety

4.1.1General Safety

4.1.2 Equipment Safety

4.2 Operation Rules

5. System operation

5.1 LAM490 System Description

5.2 Initial Status Check

5.3 Initial System Check

5.4 Preparation before Etching Process

5.4.1 Gas Supply

5.4.2 Wafer Alignment Preparation

6. Introduction to LAM490 operation control system

6.1 Load and Edit Recipe

6.1.1 Load a Recipe

6.1.2 Edit a Recipe

6.1.3 Edit end point parameters

6.1.4 Signal Options Page

7. Auto Process Run

7.1 Set Wafer Cassette

7.2 Send and Load Wafer

7.3 Pump down and Wafer loading

7.4 Run etching recipe

7.5 Unload Wafer

7.6 Return Wafer

7.7 Chamber Clear

8. Process Recording

9. Clean up

10. Check out

Appendix

https://snf.stanford.edu/SNF/equipment/metalization-sputtering/evaporation/innotec-es26c-e-beam-evaporator/#section-9



LAM 490 AutoEtch System

1. Picture and Location

Fig.1 LAM 490 AutoEtch System

The LAM 490 AutoEtch System is located at NFF Phase II cleanroom, Room 2240.

2. Process Capabilities

2.1 Cleanliness Standard

The LAM490 AutoEtch system is being classified as CLEAN equipment.

2.2 Possible Etching Materials

Poly-Silicon, nitride, α-Si film.

Silicon mark.



2.3 Process Specification

The masking material can be photo-resist prepared in CLEAN standard equipment.

2.3.1. What the LAM 490 CAN do

Individual 4 inches full silicon or quartz substrate in CLEAN cleanliness standard.

2.3.2. What the LAM490 CANNOT do

Substrate not in 4 inches in diameter

The films that not in the list.

Defect appearance of the substrate.

Fragile appearance of the substrate.

Appearance of the photo-resist is not well baked.

Appearance of the photo developer on the back side of the substrate.

Substrate appears will generate particles during etching process.

Photoresist that coated on the backside of the substrate.

2.4 Etching Process Useful Information

Before starting your etch process, please make sure a dummy condition run must be

performed in order to ensure the stability of the equipment.

The typical etch rate for silicon nitride film is around 900A/min, selectivity to oxide is

around 3.5, and selectivity to photoresist is 1.5.

The typical etch rate for polysilicon film (SF6) is around 4500A~6500A/min, selectivity

to oxide is around 20, and selectivity to photoresist is 3. However, the etching uniformity

of polysilicon film is not good, ~10%.

The typical etch rate for polysilicon film (Cl2) is around 5000A/min, selectivity to oxide

is around 30, and selectivity to photoresist is 2. However, the etching uniformity of

polysilicon film is not good, ~10%.

The typical 1200A silicon mark etching time is 26~30 seconds. However, please pay

special attention to the existing native oxide, and also a descum process will be

recommended after lithography processes. In addition, not less than 5 dummy wafers

must be performed in order to get a stable etching rate.



For more details information about the process of LAM490, please consult NFF etching

module staffs. For recipe details, please check the appendix attached.

3. Useful information to work in NFF

3.1 Emergency Responses and Communications

In case of emergency issues, please contact NFF staffs,

Preason Lee – Deputy Safety office (x7900).

CK Wong – senior technician (x7226).

In case of technical help, please contact NFF staffs,

CK Wong – senior technician (x7896).

Casper Chung –technician (x7896).

Brial Kwok – technician (x7896).

3.2 Become a Qualified LAM490 User

Please follow the procedures below to become a qualified user of LAM490:

Read all materials provided on the NFF website about the LAM490.

Request the LAM490 operation training and examination online.

4. Operation Safety and Rules

4.1. Operation Safety

4.1.1 General Safety

LAM490 user must familiar themselves with the following general safety issues:

Location of emergency exits and assembly points

Procedures for obtaining first aid assistance must be known.

Various alarm sounds and emergency call procedures must be known.

4.1.2 Equipment Safety

LAM490 user must be aware themselves of the following equipment safety issues:

https://snf.stanford.edu/SNF/equipment/metalization-sputtering/evaporation/innotec-es26c-e-beam-evaporator/#section-9



In emergency when using the equipment, please turn the POWER button off (Fig. 2) to

interrupt the equipment power, and report to the NFF staffs immediately. DO NOT

attempt to resume the equipment on before the problem is solved.

In case there is gas leakage from the equipment and hazard alarm sounds, leave the

cleanroom immediately after pushing the emergency button. DO NOT attempt to collect

any substrates or belongings.

If the equipment fails while being used, never try to fix the problem by your own, please

write down the alarm information and report to NFF etching module staffs.

Alarm/warning message will be shown in the control screen (Fig.3). DO NOT attempt to

resume the equipment on before the alarm/warning message is verified.

Be careful to the components of the equipment, which involves electric power, RF

radiation and high temperature hazard.

Fig 2 Emergency Power button



Fig.3 Alarm/Warning message

4.2 Operation Rules

Do not operate the equipment unless you are properly trained and authorize to operate

the equipment.

Reserve the equipment in NFF website in advance.

Reservation will be forfeited if user never shows up and check-in within half of the

session time and it may cause a $200 penalty.

Fill all the details of the log-sheet attached, i.e. date, name, project number, email,

project details, material …

Do not leave an on-going etching process unattended.

Do not skip any pump and purge steps during process running.

Do not change details of the recipe unless you are authorized to do. If you need to start a

new recipe, please consult NFF etching module staffs.



5.0 System Operation

5.1 LAM490 System Description

The Lam490 AutoEtch System is fully automated; etching single wafers using plasma dry

etch process. This equipment includes loadlock transport system, and process chamber. A

loadlock transport system consists of send/receive cassette indexers, belt drive system,

entrance/exit lifters, entrance/exit arms, and entrance/exit loadlocks. The process chamber

consists of electrode assembly; electrode gap drive, gas delivery system and RF match system.

The electrode gap drive provides space adjustment between the upper electrode and the wafer,

which provides a wider process window. The gas delivery system employs different kind of

process gases, including He, O2, Cl2, SF6 and C2F6. Typically, Cl2 gas can be used for

poly-silicon etch, SF6 can be used for silicon, poly-silicon, and nitride etch. On the other

hand, C2F6 can be used for native oxide removal or process chamber cleaning. Then RF

matching assembly automatically matches the impedance of the chamber to the RF generator,

according to different setting of RF power, electrode gap spacing, gas mixture, and chamber

pressure.

5.2 Initial Status Check

Users are required to do the following checks before doing the etching process:

Please check the equipment status from the shutdown notice board in the NFF

reservation website.

If the equipment has been reserved, then check the user name and project number that

displayed on the dedicated LCD screen are correct (Fig. 4).

Please check-in the reserved equipment on your own within half of the session time. To

do the check-in, please scan your NFF access card over the card reader attached. After

checked-in the equipment, the red LED on the card reader will be ON.

If you are failed to do the check-in, there is an interlock, and you cannot operate the

equipment normally.

Before operate the equipment, make sure you have read and ready to fill the details of



the log-sheets attached.

Fig.4 Reservation and Equipment check-in status LCD

5.3 Initial System Check

Turn on the CRT display if necessary.

Check any wafer left in the cassette of entry/exit load lock.

Check the base pressure is below 0.05Torr (Fig. 5). Otherwise, please contact NFF staffs

for help.

Please check the chiller is running. The default temperature is 20oC and default

resistance of the DI water circulate is 15Mohm (Fig.6)

Visual check any water leakage from the equipment.

Check any abnormal sound coming from the equipment.

Check there is no alarm/warning message displayed in the main control screen.



Fig.5 base pressure reading

Fig.6 Water chiller

5.4 Preparation before Etching Process

You are advised to do the following steps before start do the etching process.

5.4.1 Gases Supply

LAM490 users must confirm with etching module staffs that Cl2 gas are ready to use when

you are going to do a polysilicon etch with chlorine gas.



5.4.2 Wafer Alignment Preparation

Use the flat align tool to align the flat position of wafers on the LOAD cassette. First,

hold down the lever at the left side, then turn the knob until the flat aligned (Fig.7).

Make sure an empty UNLOAD cassette has been placed on the designated slot of the

exit load lock for receiving the etched wafers (Fig.8).

If you have any problem about using the cassette and flat align tool, please consult NFF

etching module.

Fig.7 Flat align tool

Fig. 8 Empty UNLOAD cassette located at the exit load lock chamber

6.0 Introduction to LAM490 operation system

6.1 Load and Edit recipe

6.1.1 Load a Recipe

Please make sure you load a right recipe, a wrong recipe may get unexpected results. Please

read the following recipe loading procedures:



1. Select right recipe cartridge.

2. Insert recipe cartridge into the port located under CRT display as shown (Fig. 9)

3. Click “LOAD” key to load the recipe stored in the cartridge (Fig. 9).

4. Click “RECIPE” key to access the Recipe page. Then view and confirm the details of

the loaded recipe from the CRT display. All the recipe steps and details can be

displayed in the recipe page by using the four arrow keys (Fig.9).

5. If the loaded recipe is correct, pull out the cartridge from the slot. Do not attempt to

click “SAVE” key to change any parameters stored in the cartridge.

Fig.9 Recipe loading keys and Recipe cartridge

6.1.2 Edit a Recipe

Please be reminded only Completion field, Etching step time, and Over-etch step time is

allowed to be changed in the recipe page by user. However, it is strictly prohibited to change

other parameters, including Pressure, RF power, Gap spacing, Gases flow rate, and other step

time.

In the Completion field, you can click the “FIELD” key to select different termination

methods of a particular step. There are 5 selections are available: Time, Stability or Time,

Time and Endpoint, Over-etch, and Recipe (Fig.10).



Fig.10 Recipe details in the main screen

Time: when Time field is selected, then step completes after a certain amount of time as

specified in the Wait field.

Stability or Time: when Stability or Time field is selected, then the recipe advances to the

next step after all the desired parameters in the current step are reached. If stability is not

achieved within the time limit specified in the Max field, the machine suspends processing

until you reset the alarm on the Machine Parameters page or by activating the Manual

Endpoint field on the Status page. When the alarm is cleared, the process continues to the

next step without verifying that stability was ever achieved.

Time and Endpoint: when Time and Endpoint field is selected, then the etching step

terminates optically with the endpoint detector or after a certain period of time as specified in

the Wait field. The endpoint setting parameters should be entered for that step on the

Endpoint Parameters page describe in the following section.

Over-etch: when Over-etch field is selected, it is associated with a percentage field. In etch

step that RF is on, the duration of that step is timed. When an over-etch step executes, the

time of over-etch is determined by that etch time multiplied by the specified percentage.



Recipe: when Recipe field is selected, it signifies that the previous step is the last recipe step,

and the recipe will be ended.

6.1.3 Edit endpoint parameters

To access the Endpoint Parameters page, click the “PARAMETERS” key to the Machine

Parameters page, then move the cursor to the top “PARAMETERS: [MACHINE]” field, and

click “FIELD SELECT” key to switch to the “PARAMETERS: [ENDPNT]”, then Endpoint

Parameters page can be achieved (Fig.11)

Fig.11 Endpoint setting page

In Endpoint parameters page, there are few parameters can be edited: Sampling input, Active

during recipe, Delay time before Normalizing, Normalize Time, and Endpoint Triggering %. A

description of field parameters follows:

Sampling Input: This field set the endpoint channels required to provide the endpoint

algorithm for up to 4 etching steps in any recipe. Typically, Channel A will be used for

endpoint detecting that employing Cl2 as the etching gas, and Channel B will be used for

endpoint detecting that employing SF6 as the etching gas.



Active During Recipe Step: This field specify the step number where the endpoint parameters

will be active.

Delay Time Before Normalizing: This field specify a time period for plasma stabilization prior

to establishing a normalized value.

Normalize Time: This field specify the duration of the signal sampling done to establish a

normalized signal reference level. A sample signal is taken every 0.25s for the period of time

selected. The average of the samples taken becomes the normalized value, representing 100%

signal.

Endpoint Triggering %: This field allows users to input a percentage of the normalized

endpoint signal used for triggering the endpoint.

The following table provides typical setting in Endpoint parameter page, user can use as

reference.

Si3N4 on SiO2 Poly-Si on SiO2 (SF6) Poly-Si on SiO2 (Cl2)

Typical thickness >1000A >5000A >5000A

Endpoint channel B only B only A only

Analog I/P channel 13 13 12

Step 03 03 06

Delay 20s 20s 20s

Normalize 10s 10s 10s

Trigger 90% 95% 94%

Signal 154 to 98 86 to 50 190 to 140

Table 1 Endpoint default setting

6.1.4 Signal Options Page

To observe the analog input signal readout from the endpoint detector, a signal options page

must be accessed by clicking “OPTIONS” key. In this Options page, all the analog input

readout will be shown at the bottom part of the display. Typically, channel 12 is used for

monitoring the signal from endpoint detection channel A, and channel 13 is used for

monitoring the signal from endpoint detection channel B (Fig.12).



Fig.12 Analog Input signal

7.0 Auto Process Run

The whole etching sequence involves, 1) Set Wafer Cassette, 2) Send and Load wafer, 3)

Pump down and wafer loading, 4) Start Etching Process, 5) Unload Wafer, and 6) Return

Wafer.

7.1 Set Wafer Cassette

Set wafer cassette on the designated slot of the entrance load lock for sending wafer into the

process chamber (Fig. 13).

Fig.13 Set wafer cassette



7.2 Send and Load wafer

Once the wafer cassette is ready, then click the keyboard “START” key to start the wafer

sending procedures and etching steps. Firstly, the send indexer loads a wafer from the send

cassette onto the wafer belt drive system (Fig.14a). Then, the belt takes wafers to the entrance

station lifter (Fig.14b). Finally, loadlock arm takes the wafer into the loadlock chamber

(Fig.14c). However, user must pay attention to the wafer sending status; it may have chance

the wafer is not sending out. If it happens, take out the wafer, put back to the load cassette,

wafer align and start the process again.

However, make sure do not start a process without wafer in the chamber; otherwise it will

seriously damage the chamber’s pin lifter.

Fig.14a wafer send indexer Fig.14b belt drive wafer Fig.14c wafer loading

7.3 Pump down and wafer loading

Once the loadlock arm returned, then outer door close and loadlock chamber will be

evacuated. When the loadlock reaches a set crossover pressure, the inner door opens and the

arm loads the wafer into the process chamber.

7.4 Run etching recipe

When the wafer loaded into the electrode, then process recipe start to run, gases are

introduced, and power is applied to the upper electrode. In order to check the status of the

chamber, click the “STATUS” key to the chamber status page (Fig.15). In this page, step

number, step time remaining, gas flow, RF forward and reflected power, gap spacing,

electrode temperature, and all vacuum conditions can be obtained.

Typically, the upper left hand corner displays the machine status and alarms. Once process

starts, the recipe step number will display at the top of the Status page along with the time

remaining for that particular step. Then, the gas system is represented by five boxes; each gas

box is labeled with a gas name and displays the gas flow rate or set point. To display the set



point or monitor the current flow rate, move the cursor to the SETPT/MON field in the Status

page, and click keyboard “FIELD SELECT” key to toggle the field back and forth between

set point (SETPT) or monitor (MON).

At the center of the status display, it shows chamber pressure, RF power, electrode gap

spacing, temperature, and bias. However, recipe set point values are only displayed for a

recipe step in process.

Fig.15 Chamber status page

When the etching process starts, once the RF power successfully matched, then the plasma

ignite, and the color of plasma can be observed through the view port at the rear part of the

machine (Fig.16). The plasma color will be vary and depends on the etching gases and

pressure used.



Fig.16 Plasma ignition

During the etching, a “STOP” key can be used to stop releasing any more wafers from the

send cassette, and wafers previous sent will complete the remaining process cycles. However,

to skip/terminate a recipe step, move the cursor to the MANUAL ENDPT field in the right

middle of Status page, and click keyboard “FIELD SELECT” key to select ON. Then a recipe

step will be skipped or terminated (Fig.15).

After all the etching steps, a purge and pump down steps will be carry out to purge and pump

out all the hazard gases used in the process.

7.5 Unload wafer

After process, wafer will be unloading to the exit loadlock. Then, loadlock chamber will vent

to atmosphere for further unloading to the exit belt drive system.

7.6 Return wafer

Finally, the exit belt drive will send the wafer back to the cassette placed on the exit station.

However, if you failed to place the receiver cassette, then the wafer transportation will be

halted until it detected a receiver cassette.

7.7 Chamber clear

In case, there is problem during running, and wafers need to be returned. Then, a “Wafer

Cleanout” command can be used to do this. To do this, access the “PARAMETERS:



[MACHINE]” page, click the main keyboard “PARAMETERS” key, then click “FIELD

SELECT” key to switch between “PARAMETERS: [MACHINE]” field or “PARAMETERS:

[ENDPNT]” field (Fig.17). In the page, click the “Wafer Cleanout” command to initiate the

wafer clean out procedures automatically. When this command was used, then all the function

keys will be disabled until the cleanout procedures complete.

Fig. 17 Wafer clean out

8.0 Process Recording

1. Please be reminded you are required to fill all the details of the log sheets. If users fail to

do this, a heavy punishment will be given.

2. Write down the problems happened or any comments in the log sheets.

9.0 Clean up

1. Clean up the area.

2. Return the cassettes to its original position.

3. Return alignment tool to their proper position.

10.0 Check out

Check out the equipment immediately after use.



Appendix

Silicon Mark

STEP 1 2 3 4 5 6

PRESSURE (mT) 0 500 500 1T 0 0

RF TOP (w) 0 0 100 0 0 0

GAP (cm) 1.5 1.5 1.5 1.5 1.5 1.5

CL2 0 0 0 0 0 0

O2 0 50 50 0 0 0

He 0 50 50 100 0 0

SF6 0 100 100 0 0 0

C2F6 0 0 0 0 0 0

COMPL Time Stable Endpoint Time Time Recipe

TIME (s) 10 60 28 10 15

Silicon Nitride/SiO2

STEP 1 2 3 4 5 6 7

PRESSURE (mT) 0 435 435 435 1T 0 0

RF TOP (w) 0 0 130 130 0 0 0

GAP (cm) 1.35 1.35 1.35 1.35 1.35 1.35 1.35

CL2 0 0 0 0 0 0 0

O2 0 0 0 0 0 0 0

He 0 50 50 50 100 0 0

SF6 0 90 90 90 0 0 0

C2F6 0 0 0 0 0 0 0

COMPL Time Stable Endpoint Over-etch Time Time Recipe

TIME (s) 5 60s 10% 10 10



Polysilicon (SF6)/SiO2

STEP 1 2 3 4 5 6 7

PRESSURE (mT) 0 400 400 400 1T 0 0

RF TOP (w) 0 0 130 100 0 0 0

GAP (cm) 1.25 1.25 1.25 1.25 1.25 1.25 1.25

CL2 0 0 0 0 0 0 0

O2 0 40 40 40 0 0 0

He 0 0 0 0 100 0 0

SF6 0 150 150 150 0 0 0

C2F6 0 0 0 0 0 0 0

COMPL Time Stable Endpoint Over-etch Time Time Recipe

TIME (s) 10 60 30% 10 10

Polysilicon (Cl2)/SiO2

STEP 1 2 3 4 5 6 7 8 9 10 11

PRESSURE (mT) 0 400 400 0 500 500 500 0 150 0 0

RF TOP (w) 0 0 300 0 0 300 250 0 0 0 0

GAP (cm) 1 1 1 1 1 1 1 1 1 1 1

CL2 0 0 0 0 110 110 110 0 0 0 0

O2 0 0 0 0 0 0 0 0 0 0 0

He 0 90 90 0 80 80 80 0 120 0 0

SF6 0 0 0 0 0 0 0 0 0 0 0

C2F6 0 50 50 0 0 0 0 0 0 0 0

COMPL Time Stable Time Time Stable Endpt Overtime Time Time Time Recipe

TIME (s) 10 30 10 20 30 10 20 15 20

standard operating manual - hong kong university of ...mfz140.ust.hk/eq_manual/sop of lam 490...

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