Wisconsin Center for Applied Microelectronics
1550 Engineering Drive
Madison, WI 53706
Phone: 608/262-6877
Fax: 608/265-2614
STS MULTIPLEX ICP SYSTEM
OPERATING PROCEDURE
Rev. 5/6/14
Material Restrictions:
All materials allowed for use in this equipment are
listed in PDF form on the WCAM My Web Space. To
view the listing following these steps:
A. Open the UW website
https://mywebspace.wisc.edu for My
WebSpace.
B. Log on using your UW NetID and password.
C. Click on the star in the upper left corner.
D. Under Bookmarks click on Group Directories.
E. Scroll down the list of organizations to WCAM.
F. Click on WCAM.
G. Double click on the first file folder to open
“Approved Materials.”
H. Double click on the WebsiteRpt to view the
approved materials for equipment.
I. Within the PDF you can perform a search.
STS Operating Procedure - 1 -
System Requirements
1. The materials allowed in the STS are very limited. Mainly only silicon and photoresist is
allowed in the STS. Absolutely no exposed metals allowed on your sample!
Check the website for allowed materials!
2. The system requires 100mm (4in) wafers. If you have smaller wafers or pieces, you will
need to use the STS Carrier Mounting Procedure to secure them to a 100mm
carrier wafer.
3. If you intend to etch deeper than 200 microns, you must mount your sample to a
100mm carrier wafer using the STS Carrier Mounting Procedure. It is the
responsibility of the user to make sure they do not etch thru their carrier wafer.
i)
ii)
iii)
If a silicon wafer is used for a carrier wafer for deep etches it must be
considerably thicker than the samples.
A thick dielectric layer of SiO2 or SiN can be put on the carrier wafer to
reduce the etch rate of the carrier wafer in relation to the silicon
samples, but the carrier wafer can still be etched thru so care still needs
to be taken.
A good carrier wafer for deep etches is a quartz wafer. The middle
portion of a quartz carrier wafer must be covered with the silicon
substrate samples so the STS detection system recognizes that there is a
100mm wafer in the load lock.
4. The outer 10mm of the top of the wafer and the
complete backside of the wafer should be a
completely clean bare silicon wafer surface.
STS Carrier Mounting Procedure
1. On a 4-inch carrier wafer drop a small amount of PR
1827 onto the wafer. DO NOT SPIN. No samples or
photoresist should be within 10 mm of the wafer
edge.
2. Put silicon wafer sample on photoresist. Bake 10 minutes
in 90C oven.
STS Operating Procedure - 2 -
A carrier wafer must be used for:
A) The sample to be etched is
smaller than 4-inch wafer; or
B) The etch depth will be greater
than 200 microns.
TIP: A lower helium leak
up rate occurs when the
polished side of the wafer
is downward and
unpolished side is used for
mounting.
Log Into CRESS
Interacting with the control computer
Locate the system control computer on the table next to
the system.
You should see several system windows on the screen.
The windows are titled:
A) Process Control - ICP
B) ICP View
C) Sequencer
D) Plan View
E) Transfer
Process Control–ICP
Sequencer
Plan View
ICP View
These windows will control the system and inform you about the operating status.
In the red banner across the top of the screen you should see the term Monitor Mode.
STS Operating Procedure - 3 -
Transfer
System Pre-Check
1. On the controller rack check the following:

Conductivity meter – should read <
1.8

Turbo mag drive 1000 – should
read “R” for remote,
“NORMAL”, and 600Hz

Temperature of the chamber lid – should read 45
2. At the computer monitor check:
 On the Process Control ICP Window – should be in ACTIVE MODE.
3. Make sure the water recirculator temperature is at 5C.
*See staff if these conditions are not met
STS Operating Procedure - 4 -
Vacuum Pump – Getting started
You will need to turn on the nitrogen to ONE of the vacuum pumps for the system. The
control box is located near the computer monitor.
a. Press the SETUP button and the SETUP indicator
should light.
b. The display will ask for a password — 202.
c. Use the UP Arrow to enter a 2 as the first digit.
d. Press ENTER.
e. 0 is the second digit so just press ENTER.
f. Use the UP arrow to enter a 2 as the third digit
g. Press ENTER.
h. Now the display should read
“SETUP MENU, Inlet Purge”
i.
Press the DOWN arrow once
j.
Now the display should read
“SETUP MENU, Gas Ballast”
k. Press ENTER
l.
Now the display should read
“GAS BALLAST, OFF”
m. Press the UP arrow to turn on the gas ballast.
n. Press ENTER.
o. Press NORMAL button.
Operator Mode – Activating the system
1. Using the mouse, click on EDIT in the tool bar on the top of the screen
2. Click on the OPERATOR MODE.
3. Chose the Standard
4. Type in the password
Mode and click on CHANGE.
wafer and hit enter.
5. Click on CHANGE.
6. In the red banner across the top of the screen you should see the term Standard Mode.
STS Operating Procedure - 5 -
Sequencer Window – Choosing your process sequence
1. Using the mouse, click on Select
in the sequencer window.
a. A pop-up window will
arise; there are several
sequences in the window
to choose from.
b. Using the mouse click on
the sequence you desire.
Example: WIETCH.
c. Click on Select.
2. Using the mouse, click on BATCH
in the sequencer window.
a. A pop-up window will arise; using the keyboard type in the number (1, 2, 3, etc.)
of wafers you intend to etch in this session.
b. Click on OK.
3. Confirm Naming Mode window is MANUAL.
4. Click on Next Carousel window.
5. Type in the name of your wafer and press ENTER.
System Load Lock – Loading your wafer
1. You may now unlatch and lift the lid (It should open very easily – very little effort is
required).
2. Place your wafer onto the carousel with the wafer flat in line with the white lines on the
wafer holder.
3. Close the lid and latch it using the handle.
Sequencer Window – Starting the sequence
1.
Click on RUN.
2.
The load lock will now pump down. The Transfer status display will indicate
“Acquiring [your wafer name].”
3.
The wafer will automatically be placed in the chamber.
Plan View Window – Wafer Transfer
You can watch the wafer transfer from the load lock to the chamber by watching the screen
in the Plan View window.
STS Operating Procedure - 6 -
Process Control – ICP Window
Helium leak up check
Once the wafer transfer is complete, the system will automatically begin your etch process.
1.
The display will first tell you that it is “Running process
[SEQUENCE] on [your wafer name]”
2.
The system will first perform a Helium leak up check.
The display will indicate “[SEQUENCE]: XXXXX: Checking
Helium Leak Up Rate.”
3.
4.
Observe the display directly above the Process Status
display; it will indicate the helium leak up rate (He LUR)
in mT/min.
The Helium leak up rate must be < 8.0 mT/min or
the system will alarm and wait for the user to run the
In the Process Control –ICP
window locate the helium
leak up check icon.
He
Helium icon located directly
above the Process Status
Display.
abort procedure.
5.
When the Helium leak up check is complete
record the rate in the run log.
See Trouble Shooting #1 for
LEAK CHECK ABORT
procedures.
Process Control – ICP Window
Setting etch time
1.
DURING HELIUM LEAK UP CHECK, you can change your etch time and this will be the
only chance.
Locate the display with HH:MM:SS displayed — above and left of the Process Status
display.
HH:MM:SS
The icon for the etch time looks like:
2.
Click on the display and change the time to your etch time. The data is in the form:
HH:MM:SS
3.
The etch will automatically begin once the gas stabilization is complete.
STS Operating Procedure - 7 -
Process Control – ICP Window
Etch
The HOLD button during an etch can be used to pause the etch so the user can leave the
tool temporarily. Hitting the HOLD button during an etch will turn off the RF power and
plasma, but keep the gas flows and chamber pressure stable. A window will pop-up
notifying that a user induced hold has been placed. When ready to resume the etch click
CLOSE on the pop-up window, and then click RESUME in the Process Control-ICP window.
Process Control – ICP Window
Etch Complete
At the end of the etch process, the Process Status display
will indicate “Standby Step: pumping out”
The system will automatically remove the wafer from the
chamber and place it in the load lock.
See Trouble Shooting #3
for tips on etch profiles.
The load lock will vent.
System Loadlock – Unloading your wafer
1.
A Red Alarm Screen will pop-up to indicate that you
need to be ready to unload your wafer. Click CLOSE
in the pop-up to acknowledge the alarm.
During the venting, the ICP process will be running
DEFAULT.
See Trouble Shooting #2
if excessive venting
error occurs.
2.
Once the load lock has vented, the lid will be slightly
open.
3.
Lift lid and remove your wafer from the carousel.
4.
Close the lid and latch it using the handle.
5.
Before proceeding to the next step, ensure TRANSFER window status reads: Release
of [your wafer name] complete. Ready.
If additional etch time for same wafer is needed, go to Page 6 and begin at
“SEQUENCER WINDOW: Choosing Your Process Sequence.”
STS Operating Procedure - 8 -
Sequencer Window – Chamber clean
CLEAN CHAMBER AFTER PROCESSING
1.
Locate the STS CLEAN WAFER and load it into the loadlock.
2.
Go to Page 6 and begin at “SEQUENCER WINDOW: Choosing Your Process Sequence.”
3.
Select the O2CLEAN sequence and follow the etch procedures.
4.
Input the lesser of these 2 process times:

Clean time equal to your etch time if etch was less than 30 minutes; or

30 minutes.
5.
After cleaning time, unload and return the STS CLEAN WAFER to its storage container.
6.
Proceed to deactivating the system.
Process Control – ICP Window
De-activating the system
In the red banner across the top of the screen you should see the term Standard Mode.
1. Using the mouse, click on EDIT in the tool bar on the top of the screen
2. Click on the OPERATOR MODE.
3. Chose the MONITOR MODE and click on CHANGE.
4. In the red banner across the top of the screen you should see the term Monitor Mode.
5. You will need to turn off the nitrogen to one of the vacuum pumps for the system. The
control box is located near the computer monitor.
a. Press the SETUP button and the SETUP indicator should light.
b. The display will ask for a password — 202.
c. Use the UP Arrow to enter a 2 as the first digit.
d. Press ENTER.
e. 0 is the second digit so just press ENTER.
f. Use the UP arrow to enter a 2 as the third digit
g. Press ENTER.
h. Now the display should read
“SETUP MENU, Inlet Purge”
STS Operating Procedure - 9 -
i.
Press the DOWN arrow once
j.
Now the display should read
“SETUP MENU, Gas Ballast”
k. Press ENTER
l.
Now the display should read
“GAS BALLAST, ON”
m. Press the DOWN arrow to turn off the gas ballast.
n. Press ENTER.
o. Press NORMAL button.
6. Complete the run log entry.
7. Log out of CRESS.
STS Operating Procedure - 10 -
STS Multiplex Plasma Etch Recipes
PRESSURE CONTROL
PROCESS NAME
SEQUENCE NAME
[CYCLES]
MIX1010
[1]
ASTROH
NASA
[973]
ASTROH2
HANDLING
O2CLEAN
OXIDDISC
PILLAR5
SHALASEQ
SIO2DISC
TAPETCH2
TAPETCH3
TAPRETCH
THRUETCH
THRUNOPA
WIETCH
O2CLEAN
MIX1010
[1]
NASA
[973]
O2CL_NHE
DEFAULT
O2CLEAN
OXIDEETC
SIO2DISC
PILLARS5
[100]
SHALLOWA
[80]
SIO2DISC
TAPETCH2
[973]
TAPETCH3
[973]
TAPRETCH
NASA
[973]
THRUNOPA
SMPLEASE
[100]
PHASE
Etch
Pass.
Etch
Pass.
Etch
Etch
Pass.
Etch
Pass.
Etch
Etch
Etch
Etch
Etch
Etch
Pass.
Etch
Pass.
Etch
Etch
Pass.
Etch
Pass.
Etch
Etch
Pass.
Etch
Etch
Pass.
TIME
(sec)
5.8
5.0
10.5
6.0
N/A
5.8
5.0
10.5
6.0
N/A
N/A
N/A
N/A
N/A
10.0
7.0
7.0
6.0
N/A
10.5
3.0
12.0
2.0
N/A
10.5
6.0
N/A
11.0
8.0
AUTO
(mT)
MANUAL
THROTTLE (%)
64.5
64.5
64.5
64.5
GAS FLOW (SCCM)
C4F8
O2
SF6
110
110
13
13
13
101
101
101
40
13
13
13
101
101
101
Ar
97
40.0
64.5
64.5
64.5
64.5
RF Power (W)
110
110
97
40.0
40
0.1
40
40
60
15
20
20
18
18
15
28
13
6
100
130
13
130
13
100
101
13
101
60
13
75
101
13
13
101
130
50
110
120
64.5
64.5
64.5
64.5
83.0
64.5
64.5
64.5
66.0
66.0
50
97
97
5
97
85
STS Operating Procedure - 11 -
COIL
600
800
600
600
800
600
800
600
600
800
0
800
800
450
600
600
600
600
450
600
600
600
600
700
600
600
600
600
600
PROCESS
STEP
PLATEN
11.7
Continuous
0
11.7
Discrete
0
20
Discrete
11.7
Continuous
0
11.7
Discrete
0
20
Discrete
0
Discrete
20
Discrete
20
Discrete
8
Discrete
11
Discrete
0
11
Discrete
0
8
Discrete
11.7
Discrete
0
11.7
Discrete
0
15
Discrete
11.7
Discrete
0
11.7
Discrete
13
Discrete
0
He
LEAK
TEST DESCRIPTION
Y
Faster ASE
Y
Faster ASE
Y
O2 clean
Y
Faster ASE
N
Faster ASE
N
N
Y
Y
Y
O2 clean
O2 clean
oxide
Si
NOTES
Etch Si IR filters
No He leak test
between processes
Wafer transport
Post SF6 chamber clean
Etch breaks thru native
oxide then etches Si
Y
Y
Shallow Si
etch
Y
Y
Taper etch
Y
Taper etch
No passivation cycle
Y
Y
Y
Y
Faster ASE
No passivation cycle
Sample advanced
silicon etch
Trouble Shooting—Situation #1
Problem: Wafer did not pass helium leak up test.
Causes: Backside of wafer not clean or the stage o-ring is not clean. The helium leak up rate of the
STS Etcher must be less than 8.0 mT/min. or the system will alarm.
Solution:
Abort sequence and remove wafer. Clean the backside of the wafer and attempt sequence again.
The following procedure will stop the process and unload the wafer:
ALARM WINDOW:
1. Alarms and Requests window will pop up.
2. Click on CLOSE.
PROCESS CONTROL WINDOW:
3. Click on ABORT.
4. The PROCESS STATUS line will read “ICP process . . . aborting”
5. Wait until the PROCESS STATUS line reads “ICP process . . . aborted”
SEQUENCER WINDOW:
6. Click on STOP.
TRANSFER WINDOW:
7. Click on UNLOAD.
8. When the VENT button becomes available, click on it.
9. The Alarms and Requests window will pop up to indicate that you need to be ready to
load your wafer. Click CLOSE to acknowledge.
10. Once the load lock has vented the lid will automatically open.
11. Lift lid gently and remove your wafer from the carousel.
12. Close the transfer station lid and latch.
STS Operating Procedure - 12 -
Trouble Shooting—Situation #2
Problem: Wafer in load lock and the chamber not vented. “Excessive Vent Time”
Cause: User not present during load lock vent sequence.
Solution:

Try clicking FINISH in the Sequencer Window; or

Notify staff to manually vent the load lock.
o Log in as Staff
o Click ABORT
o Click STOP
Trouble Shooting—Situation #3
Problem: Optimizing STS etch profiles
Cause: Etch parameters
Definitions:
Negative profile
Positive profile
Solution: Control of profile is best done by controlling the ratio of the etch time to deposition time.
An increase in the C4F8 deposition time will result in a more positive profile.
An increase in the SF6 etch time will result in a more negative profile.
STS Operating Procedure - 13 -