STS PECVD, sts
Picture and Location
The tool is located at B5 on the Lab Map.
The sts deposition system is in the "Gold Equipment Group".
Materials control policies are governed by equipment
groups; for the description of this policy, click <here>.
For equipment compatibility with specific materials, click <here>.
Performance of the Tool
What the Tool CAN do
- Item A.
What the Tool CANNOT do
- Item A.
Contact List and How to Become a User
The following people make up the Tool Quality Circle:
- Process Staff: TBA
- Maintenance: Jim Hayden
Training to Become a Tool User
This system is Gold contaminated. The PECVD STS deposition tool is mainly used for depositing of silicon nitride film. A mix-frequency program is available for this process. A low frequency program is available for the silicon dioxide process. The system is equipped with 13.56 MHz and 187.5 kHz frequencies. The temperature of the system is always kept at 350 degrees. Therefore, only the materials that are stable at this temperature are allowed in the STS deposition system. Please make sure you wear only latex gloves when you are working with this system. Don’t wear any vinyl gloves. Use only clean metal tweezers. You can process 4 of 4" wafers at a time (in the center of the wafer platen). With prior approval from staff, additional training is required for special processing of wafers coming out of the STS PEVCD with clean (non-contaminated) wafers. Separate tools needed for this procedure. To find out about the status of the system, check the run sheet filled out before you. Please make sure that you fill out a run sheet while you are running a process on the STS.
- Stand by mode:
- Make sure the Ar to the pump key is open (up). This key is the black toggle key located in the right hand side of the system. If the Ar Purge key is left off for a long time while you are not running any process, the chamber will get oil back fill from the pump. This will contaminate the chamber as well as your wafer. To clean this contamination the O2 descum program should be run prior to any process.
- Make sure that lights to the RF power supplies are on (green).
- Start up, Loading the wafer & deposit:
- Enable the STS on Coral. The keyboard on the STS will not work if the system is not enabled.
- Switch off the Ar purge key (switch down)
- Use the keys on the keyboard to select (F3) "vent" from
- Pause for at least 5second before Selecting "open valve" (F1). DOS software is old and slow to respond.
- This will start venting the chamber. Make sure you hear the sound of valve opening. A message" venting the chamber, please wait" will appear on the screen. Check the process chamber lid seal. Wait until the seal is opened and there is a gap between the lid and the base of the chamber. This will take 2 -5 minutes.
- While pressing the two blue buttons located under the chamber
on the panel to lift the lid all the way up. This should rise slowly so that you do not release any particles.
- Make sure there are no particles on the wafer platen. You can use the N2 gun located next to the system to remove the particles. Please make sure that the N2 gun is aimed downward to avoid any particle trapping in the shower head.
- Locate wafers in the center of the platen. Please note that the wafers start to move
on the platen, when the pump down starts. So please load your wafers accordingly surrounding your samples with pieces so they don't move to an edge during pump down.
- Select "close valve" (F1) to close the lid
- While pushing in both blue buttons until the lid is completely down, and the computer screen will has changed showing the Mimic or Text page.
- Only at this time you may use a slow pump if desired by turning the black knob under the chamber in the direction of the line, waiting approximately five minutes. Close by turning the knob perpendicular to the line.
- Using the arrow keys selecting the desired recipe, then press enter . This will start the pump down of the system. This will take about 5 minutes. Wait until the pump down is complete.
- Select "Deposit" (F1) to start the process.
- Unloading the wafer, shut down:
- When the process step is completed, the program will go to the next step, which is "16 hours Warm down". This step is the last step of all processes, which will perform a N2 purge to the chamber for 16 hours to protect the chamber from any pump oil back fill. You should abort this step to end the program. To abort this step select "Abort " ( F1)
- Wait until the purging of the gas lines is complete and system is in the standby mode (this usually takes about 5 minutes for the silicon nitride process)
- Then select "vent" (F3)
- Select "Open the vent valve" (F1)
- Using the two blue buttons in front of the hardware, pressing both buttons until the Lid is completely up before releasing.
- Unload your wafer
- Select "Close Lid" (F1)
- Using the two blue buttons in front of the hardware, wait until the Lid is completely down before releasing.
- If no wafers are loaded in the chamber, it is not necessary to use the slow pump knob at this time. Select desired recipe using the arrow keys and then enter.
- This will start to pump down the chamber. Wait until the pump down is
complete (takes about 2-5 minutes). Once you see the four F1, F2, F3, F4 on the screen.
- Turn on the Ar Purge key (key up)
- Disable the system on Coral.
- Modifying a program:
- Select "Main Menu" (F6). This only work if the F1, F2, F3, F4 on the bottom of the screen.
- Change the level from operator to service level by:
- In front of the command, type in" level", then enter
- Will ask for a password, leave blank and press enter
- Type in "setup"
- Using the arrow keys select load/save and then enter
- Select "load process" then enter
- Select the desired program, then enter
- Select Dep. Def’N, then enter, you'll have five options.
- Select "modify step" then enter. This will show three steps of the process which are: 15 min. warm up, Mix Freq. Nit., and 16 h warm down.
- Using arrow keys, highlight the 2nd step "Mix Freq. Nit.", then enter
- Highlight "R.F. info.", then enter
- Select "Low RF setting", enter
- Select "Process Time", enter
- Enter the desired process time as: hh:mm:ss, enter
- Push "Esc" key 3 times.
- Highlight " Load/Save"
- Select "Save", enter
- Enter the file name. Please note that each user will have only one program. It will warn you about over writting your file. Answer yes.
- Push any key first then "Esc" key 2 times.
- Then there will be a message "Do you want to quit now?"
- Answer: yes "Y" then enter. This will take you to the main menu screen
- Select "Text page" (F8). This will take you to the text page.
- Select "new process" (F2)
- Select the desired program from the list
- Choose "deposit" (F1)
- Loading a new program:
The procedure for loading a new program without opening the chamber to air is as follows:
- Select "new process" (F2)
- Select the desired program from the list. This will load the program to the system
- Select "deposit" (F1)
- Cleaning the Chamber:
The total thickness of the film deposited in the chamber including predep. steps should not exceed 4.5 micron. A seven steps cleaning procedure is required for cleaning of the STS chamber as follows:
- Run program "Etchbak3". This program which takes about 2 1/2 hours, cleans the walls and the platen of the chamber using CF4 gas and O2.
- Vent the system and lift the lid. Then use folded clean wipe soaked with IPA to wipe the upper part of the wall then lower part of the wall and quartz window. Then clean the o-ring. Use the N2 gun to remove all the particle from the platen and under the platen. The last part that you need to wipe is under the hot platen. Please make sure that during the wipe don’t touch the shower head or the hot platen. Also don’t squeeze any IPA on the hot platen.
- Run the o2descum recipe. This recipe is set for 15 minutes.
- Run oxpredep recipe. This will coat the chamber with 1 micron of silicon dioxide. This recipe is set for 30 minutes
- Repeat step 2 of the cleaning procedure, exactly the same way with soaked clean wipes.
- Run the o2descum recipe, time is set for 15 minutes.
- Run the silicon nitride recipe for the thickness of 0.25 micron only if the next user is going to deposit nitride. This will take about 26 minutes. The purpose of this step is seasoning the chamber with the process that you are interested to run after cleaning procedure.
When the cleaning procedure is completed the chamber will be coated with a
total thickness of 1.25 micron. So please add this thickness to the film thickness
that you get on the first run after cleaning and record it in the run sheet. If nitride wasn't needed or deposited the total thickness will be recorded on the log sheet as
last updated 9/20/11 JP
Process Monitoring and Machine Qualification
Tool Qualification Run:
November 2012, STS is up for high frequency Nitride ONLY. RMS (Roughness) for SiNx is 0.49 nm (1000A) 350C.
November 2012 STS is up for high frequency Oxide ONLY. RMS (Roughness) for SiOx is 0.381 nm (1000A) 350C. 20:1 ER 523A/min
Unable to do dual frequency nitride at this time.
Four test wafers;
Oxide deposition rate 348A/min, 352A/min, 354A/min, 360A/min, index of reflection 1.46.
Nitride deposition rate 96A/min, 96A/min, 95A/min. Etch rate in BOE 6:1 156A/min. Index of refraction 2.05.
Nitride is tensile, 428.5 MPa
On Jan. 2010 ran a nitride test using both high and low frequencies for total time of 10 minutes. Average thickness 944 angstroms. Dep. rate 94 A/min. Nitride etch rate using 6:1 134A/min.
Recommendation to users with critical processes:
Before committing wafers, you should always verify by running a process test.
Machine Status States
Red: Unable to use
Yellow: Some restrictions or problem.
Green: Able to use equipment under normal conditions.
Process Monitoring Results: Ran four wafers ran through Low Frequency and four through High Frequency oxide. Average results for each wafer listed below.
Low Frequency test wafers High Frequency test wafers
B 357 A /min *6:1 BOE 1566 A/min 394 A/min *6:1 BOE 2269 A/min
R 362 A/min 6:1 BOE 1327 A/min 405 A/min 6:1 BOE 2643 A/min
F 364 A/min *20:1 BOE 379 A/min 415 A/min *20:1 BOE 596 A/min
L 368 A/min 20:1 BOE 454 A/min 397 A/min 20:1 BOE 593 A/min
Etche Rates with an Asterisk indicate that the etch test was repeated.