ICP Oxford
Oxford ICP Procedure
NTS, 06/12/2013
[Note: This tool is for etching III-V. Si wafers are used for sample carrying and dummy wafers.]
[Note: There must always be a wafer in the chamber to protect the chuck/stage from arcing.]
[Note: The reservation horizon for this tool is one week.]
Prep
1. Log onto the tool using the LabAccess terminal.
Log into the tool’s systems software by selecting SYSTEM and PASSWORD. Type your logon and password then select OK.
If someone else failed to logout, select VERIFY then OK to log them out, or you can just log in over them.
To verify you are logged into the tool, select SYSTEM then PASSWORD. Select OK.
Never close the tool’s software.
Never Stop all auto processes.
[Note: Pumping window should be standard open screen.]
[Note: At the screen top there is SYSTEM, PROCESS, and UTILITIES. Under the SYSTEM menu you will only use PASSWORD to log in and out, and PUMPING. Under the PROCESS menu you can use RECIPES, LOG View, and CHAMBER 1. You can use LOG VIEW to see what process have been run; press the red X to close LOG VIEW only. You will never use UTILITIES.]
3a. If the provided carrier wafer is in the load lock, you don’t have to vent the load lock before you run a clean. Skip to Step 8.
3b. Stop/Vent the tool by selecting SYSTEM and PUMPING. Select STOP, wait, and then VENT.
3c. As you select the stop and vent buttons, they will highlight yellow.
3d. This tool is vented when a Warning!! Window pops up, which takes ~1.5 mins. Select ACCEPT.
3e. The tool will vent once the timer reaches about 112 seconds.
4. Open the load lock by lifting the door up by the knob. Do not turn the knob.
[Note: These are general loading instructions, load a dummy wafer when doing a clean. Never run the chamber without a wafer in it!]
5a. Load your Si wafer into the load lock, properly. Be careful of the clear pulley tape line.
5b1. The system can only handle X” wafers. Smaller samples must be mounted on X” Si carrier wafers.
5b2. X is whatever the current size is. Advanced move, there is a way to use 8” wafers if the current approved size is 6”.
5c. Samples can be mounted with pump oil (in squirt bottle, may be hard to release), Kapton tape (may burn in plasma), or not at all (sample might move or be lost).
5d. I recommend Kapton (done right). Mount your sample in the middle for best results.
5e1. Load the wafer so the flat/divot is flush at the 9 o’clock position.
5e2. The flat needs to be between the two posts, aligned nicely. This is west on a compass.
5e3. The wafer must be flush against the posts.
6. Close the load lock.
7a. To Stop/Evacuate the tool, select STOP, wait, and then EVACUATE. As you select the stop and evacuate buttons, they will highlight yellow.
7b. A window will pop up to log your run. Enter a label if you want, or don’t, and select OK.
8a. Select the clean recipe by selecting PROCESS then RECIPES. Select LOAD to scroll through the recipe list, select OPT-O2 CLEAN.
8b. The software may ask you to overwrite a recipe. Select OK, this is only the copy of the recipe in the cache.
8c. Recipes must contain three steps: a pumpdown step, main etch recipe step, and pumpdown step for optimum processing.
8d. Verify the recipe is correct, left click on the clean step, select EDIT STEP.
8e. Edit/change the time of the main clean/etch step to desired time. This is Step Time in the top left corner.
9a. Select RUN in the Recipe Edit window to begin processing. The Process Chamber screen pops up. See Step 17 to see more about running recipes.
9b. The PUMPING screen will show what’s happening in the tool.
10. You’ll notice there are six boxes at the bottom of the PUMPING screen. The first one, Gas/MFC, will turn red when the load lock gate valve is open, or MFC box on the wall is open. If any other box turns red, the system will shut down.
11. Back on the Process Chamber screen, you’ll want to make sure the Wafer Loaded icon at top center turns from grey to green. Then the run starts. Monitor the forward power, DC bias, chamber pressure, and gas flow. Don’t leave the tool til plasma strikes.
12a. When the run is complete, a green text “Ready” will appear on the process then chamber screen.
12b. For best results, wait to press Continue on the pop up box til the wafer is in the load lock. **12c. The wafer should transfer back to the load lock whether or not you hit continue before it does so.
12d. Do not Stop/Vent the load lock until the wafer is fully in the isolated load lock.
12e. If the wafer gets stuck in the process chamber, make sure the load lock is pumped down.
Load Sample and Setup Recipe
13a. Stop/vent the chamber to unload the cleaning wafer, refer to Step 3.
13b. I like to setup a little work area with room for my sample dish and a wipe to put the carrier wafer on.
14a. Load your sample, refer to Steps 14, 4-6.
14b. When using Kapton, I suggest using scissors to cut the end of the tape to be thin (10 mm long, 4-5 mm wide). You will have to peel some Kapton off the end, then tear it from the roll.
14c. Fold over the other end so you’ll have a tab to remove it later.
14d. Place tweezers slightly off center (toward your strong hand) on the carrier wafer, and apply the skinny tip of the Kapton to your tweezer tips. Fasten tape without letting the skinny tip touch the wafer.
14e. Use the tweezers to fold back the skinny tip from where the skinny tip meets the normal width.
14f. Fasten edge/corner of sample with as little Kapton as possible.
14g. Make sure sample is mostly flat on carrier
15. Stop/Evacuate the chamber, refer to Step 7.
16a. Load the recipe needed for appropriate etching, refer to Step 8. Select your recipe or create a new recipe.
16b. Users are not allowed to save recipes, so just load a recipe and edit as desired, or create one from scratch. If you want to save a recipe, ask staff.
16c. Recipe steps can be dragged and dropped from the right to the left of the RECIPE screen.
16d. Left click and select EDIT to edit steps.
Run Recipe and End Use
17a. Select RUN. The screen will change to the process chamber window. Monitor the forward power, DC bias, chamber pressure, and gas flow.
17b. Never hit Start, Step or Pause. You can hit Jump only. Never Jump the first or last step.
17c. The Process Chamber screen has Recipe status, APC controller, Power control, Gas flow, and Endpoint portions.
17d. Status shows some info, including time of step, time remaining and whether the tool is in Auto (usual, recipe runs), Manual (never), Ready (waiting on you), or Fault (error).
17e. Use pressure control on the APC controller (yellow dot there).
17f. RF power is in the 10’s or 100’s, keep Refl <1. ICP is in the 100’s or 1000’s, keep Refl <10.
17g. Gas Flow will show target sccm and actual sccm for each gas (going from right to left). Green valves are open.
17h. There are Endpoint capabilities, and a private company installed a camera, but I don’t know how to use them.
[Note: BCl3 and SiCl4 have special recipe and cleaning rules that affect running the etch recipe! See Step 21 below.]
18. When the run is over, press continue (after the wafer has transferred to the load lock), and stop/vent the chamber (refer to Step 3) to remove the wafer.
19a. Repeat as desired for all samples.
19b. Once you are done processing, place a cleaning wafer (the carrier wafer) back in, close the load lock, and stop/evacuate the chamber, refer to Steps 5-7.
20. Run a chamber clean that is appropriate for whichever process you just ran. Use Steps 8-13 as a guideline.
21a. If you use BCl3, you must clean the chamber for 30 minutes after every hour of etching.
21b. If you use SiCl4, you must clean the chamber for 45 minutes after every hour of etching.
21c. This means if you need to do a 4 hour BCl3 etch, you must stop every hour to run a 30 minute clean. If you do a 30 minute BCl3 etch, you must clean the system for 15 minutes.
21d. Other etches only require a 10 minute minimum etch. The actual cleaning time will vary by etch duration.
22a. Log out of the tool by selecting SYSTEM then PASSWORD then VERIFY then OK.
22b. Or you can just enter anything into username and press OK, no password needed.
23. Log out of the tool using the LabAccess terminal.