Oxford ICP Operating Procedures

The loading chamber picture: 

ICP tool in cleanroom is used primarily for etching III-V materials (Ga/In/Al :As/Sb/N). Shown is the picture of the ICP tool. All the commands are given using the PC (on the right in the pic) and the wafer is loaded in the loading chamber (on the left in the picture)

← Shown is the main screen of the ICP desktop. This is the "Pump Control" section. The ICP has 2 pumping sections separated by a gate valve (shaded purple in the picture). The left side pump evacuated the loadlock (loading chamber) and the right side evacuates the process chamber. The process chamber always stays in vacuum mode while we only vent/evacuate the loadlock. 

To do any process in ICP, one would need to check if they have the access. If not, System → Password
Enter name: guest

Enter password: guest

1. Load the wafer: To do so, we need to vent the loadlock chamber. Go to loadlock pump control (bottom left control) → Stop → window appears as shown on the left → press Yes → Vent

Once the vent time left reaches 0 sec, we can open the loading chamber. Use the black handle on the loading chamber gate to pull it up.

Before we load our sample, we first do O2 clean so that there are no contaminants in the process chamber while it is etching. To do that, we only load the backing wafer without any sample mounted on it.

(Our samples are normally too small to load as it is, so, we use the backing wafer (6" Si wafer, single-sided polished) and use tape/fomblin oil as adhesive to mount our sample wafer on the backing wafer. Make sure the bottom side of backing wafer is unpolished. )

Load the sample wafer mounted on the backing wafer in the loading chamber. (the flat side of backing wafer is centered between the 2 screws that are on the left side of loading arm, when you get trained, you'll know.

After loading, go back to ICP desktop. Go to loadlock pump control → 

1. Stop → Evacuate (if any pop-up window appears, just press yes/continue)
2. Evacuation begins and you can see pressure drop in the Pirani section
3. Once the pressure in Pirani section ~ 5e-4 torr , the penning turns on and it will show pressure 7.5e-9 torr.
4. Now, we are ready to begin the etching process. For that, we need to select the right recipe.

In this documentation, O2 clean process is shown.

Process→ Recipes

Load → pop-up window appears → Yes

Find O2 chamber clean in the list. Once you find it, click on the recipe and Press OK

The recipe is loaded and the name of process can be seen in "Recipe Name". In the case of O2 Chamber clean, there are 3 steps. 1st and 3rd are just pumpdowns (meaning, the process chamber pumps down to low pressure which in normal case is in order of 1e-6 torr) 2nd step (O2 clean in this case) is the actual process when plasma turns on.

To change etching parameters, go to the step 2, right click and Edit Step

Change duration, process temperature, forward power, gas flow and set pressure accordingly. Normally, for an already built recipe, we only change the time duration. Once you are happy with the parameters, press OK.

You come back to the recipe window. Now, we have set the recipe parameters and press run. The process begins and you can see that it has when you see the process arm moving and loading the wafer in the process chamber and then come back. You will also see in the pumping window (system→pumping), that the process chamber circle is green which means the wafer is in there.

To see what is going on in process chamber, go to Process → Chamber

Chamber window tells what the status of etching process, what step you are at and how much time is left to finish the step. When plasma window is on, RF power bar turns pink. The chamber pressure should seem consistent and same or close to set pressure.

After the process finishes, the status window on top center says "loading wafer in loadlock".

Two Pop up window appears one after the other.

1. one is yellow when the process is finished 
2. other is blue saying process finished when the transfer arm brings back the wafer to loading chamber. Press ok/yes for both. The process is complete. Go back to pumping window.

Vent the loadlock:

Stop → pop-up window appears→ press Yes → Vent

Once vented, take wafer out.

Evacuate the loadlock:

Stop → Evacuate 

And you're done!

Have a nice day!