STS PECVD

Trainers

This PECVD can be used for silicon nitride or silicon dioxide depositions. It is equipped with 2% silane in nitrogen (SiH4/N2), ammonia (NH4), nitrous oxide (N₂O), nitrogen (N2), oxygen (O₂and tetrafluoromethane (CF₄).

Typical deposition rates range from 100 Å/s to 400 Å/s. This PECVD is usually used for processes with higher deposition rates than are possible in the Plasma-Therm PECVD. It may be easier to handle samples other than 3 - 6 inch silicon wafers in the Plasma-Therm PECVD. Thicker samples can not be run in this PECVD because they will not fit into the chamber.

Operating Instructions

I. Loading Sample

1. Press F3 to select the load/unload screen.
2. Press V to vent the loadlock.
3. The loadlock pressure will cycle between 2-3Torr to 70-80mTorr several times before it reaches 716 Torr. Check the black rubber O-ring around the loadlock lid, by which you can see whether the loadlock is still under vacuum.
4. Once the loadlock finishes venting, open the loadlock and place the sample to be processed so that it is held in one of the rings on the sample holder.

Caution: This system is designed to handle whole wafers only. If you are processing wafer fragments or small wafers, put the 4" sample holder which has a shallow ridge around it to prevent sliding and put your sample on top of it.

5. Once your sample is securely seated on the sample holder, close the loadlock cover.
6. Press 'L' to load your sample. The loadlock will be pumped down before the sample is transferred to the process chamber. Sometimes the change in air pressure will cause the sample to move. If this happens, press F1 immediately to abort the loading process.
7. Press F3 to return to the main operating screen.

II. Running a Process

1. Press F2 and select the process that you want to run.
2. After you have selected a process to run, the PECVD will wait for the chamber temperature to reach the operating temperature set in the process. This may take a long time. The computer will display "Waiting for Temperature Compliance" message in the lower right portion of the screen and will give you an option to either "abort" or "resume". Wait until the chamber temperature displayed on the left side of the screen reaches to the set temperature. Once the temperature is reached, hit "resume".
3. After the process is loaded, press F1 to start.

III. Checking for plasma

1. To reset the system, first flip the reset switch on the switch box
2. After flipping the reset switch, leave the chase and go back to the STS.
3. Before resetting the STS, make sure there is no wafer present in the chamber. If a wafer is present, remove the wafer before continuing to the next step. If you are not sure a wafer is present, visually inspect the chamber through the chamber window.
4. Reset the STS: On the front of the STS panel on the left are two buttons: "Plant On" and "Plant Off". Hit the Plant Off button, wait a couple of seconds, and hit the Plant On button. This resets the STS. At this point, the two pumps feeding the STS will turn off (you should audibly notice this).
5. Reset the software: After resetting the STS, you will need to reset the software. To do this, hit the F4 "Shutdown" key on the lower right of the screen. This exits from the STS control program. Double click on the screen icon to restart the software. At some point a red screen will come up that warns about purging the gas lines--just hit Enter to continue. After restarting the software, you should hear the pumps for the STS turn back on.
6. The system is now reset

IV. Watch Process

V. Unloading Sample

1. Press F3 to select the load/unload screen.
2. Press 'U' to unload your sample.
3. After your sample has been moved back into the loadlock, press 'V' to vent the loadlock. This will take a few minutes.

Editing Recipes

To start the recipe editor press F6 (Menu) to view the menu bar. Type "SETUP" and press enter. If "SETUP" is not a valid command, type "LEVEL" and enter "PROCESS". Now try "SETUP" again.

You will now see a menu with three options: Load/Save, Dep/Def'n, and Standby/Purge. Select File then Load Process to load a recipe.

Select Dep / Def'n. You will have several options such as add step, remove step, and modify step. To add a step, choose add step. To remove a step, choose remove step. To modify a step, choose modify step. Then select the step to modify.

The parameters for the step will be displayed. You can change one of the parameters by selecting it from the menu at the top and entering a new value.

Press Esc to return to the menu bar. Choose File, Save to save your recipe.

To exit the recipe editor, press Esc to display the menu bar, then press Esc again. When asked if you want to quit, answer Y.

Problems that may occur

1. The loadlock will not pump down after loading a wafer into it.
Solution: See MiRC staff.
2. "Gas flow" errors, "out of tolerance" errors in first few minutes of run.
Solution: For the first instance of the error, hit F2 "Resume" to continue the process. If the problem persists, try F1 "Abort" and restart your process.
3. Screen Lock
Solution: Solution: Hit CTRL-ALT-DELETE and restart the software. If you intend to edit a process, you will need to re-login to the machine.