Oxford Plasmalab 100

Responsible: Anders Liljeborg, Adrian Iovan

Process gases O₂, Ar, CF₄, CHF₃, SF₆, Cl₂.
Inductive Coupled Plasma (ICP), Helium backside cooling, temperature controlled electrode.

Manufacturers manual (limited access).     Suggested process recipes from Oxford Plasma Tech. (limited access).

Manual, rough pump, Alcatel 2033

Sample holder is designed for four inch wafers only! For mounting smaller chips you have to use a four (4) inch substrate, silicon, glass plate or teflon.

You should get your own, personal four inch fused silica wafer
when you start using the system on your own.      Some results of cooled Si-etch.

Bosch process

Important! Cleaning recipes after each session

Use of LN₂ cooling

How to refill LN₂ dewar

Service Mode     Replacing a gas bottle

Simple animation of the load procedure using the loadlock.

Overview of pumping window.
To the left is the loadlock with its pump controls,
to the right is the main chamber with controls.

When you arrive at the system the load lock should be pumped down.

Start venting the load lock by pressing first STOP and then VENT

Wait until the venting cycle is complete.
It takes about two minutes.

Here the lid of the load lock is open, and you mount your wafer / sample. Please note that ABSOLUTE maximum size for the sample is two inches! If the sample is close to two inch in diameter it has to be carefully aligned to the center of the carrier wafer. If you are using cooling, attach your sample to the carrier wafer with a small amount of vacuum grease (Fomblin). Take care that no grease is showing around the edges of your sample. Please try to keep the load lock door open as short time as possible.

Close the lid of the load lock.
Start pumpdown of loadlock by pressing EVACUATE

Please enter your name to be able to identify wafer and process run.
Never choose No Wafer when there actually is a wafer loaded.

Go to the RECIPES page and check that AUTOMATIC is enabled. This will ensure that the loading is fully automatic. It means that the loading will happen automatically when you start to run your recipe. The unloading will happen automatically after the end of your recipe. Never run a process without a carrier wafer loaded, e.g. a cleaning process for the chamber. The carrier wafer is protecting the center lifting pins which would otherwise be etched and destroyed.

Overview of Process control window.

Here you select a recipe. Please note that Automatic should be enabled.
This will ensure that the unloading is fully automatic after the recipe has finished.

This recipe consist of three steps:

1. Cooldown to reach set temperature of sample
2. Etching with CHF₃
3. Flushing with argon

If you are going to use CRYO COOLING, this is a good time to start that using LN₂.

Here is the step running, etching with CHF3 using only the RF-power, no ICP, step length is 7 minutes, 30 seconds. Helium backside cooling is used, and the sample is heated to 30°C. Please note the very low Set Pressure at 3.0 mTorr. This requires a Strike Pressure of 40 mTorr to be able to start the plasma. Then the pressure is decreased to the Set Pressure at a certain rate, the Ramp Rate, here set to 10, which means 10 steps of one second each, i.e. ten seconds ramp down time. Also note the heating used in this recipe, to 30° C, the HELIUM BACKING is used, the Pressure Controller is set to 5.0 Torr, which is a common value, both for cooling and heating. If you are using cooling (e.g. -50°C), always do the cooling in a separate step in the recipe, say only cooling for ten minutes. That way the set temperature is always reached before the etching is started. You can just set the temperature in the step doing the etching, but the tolerance for having reached the set temperature is quite wide, you may start the etching already at -30°C.

Here is the last step, Ar flush, 30 seconds, only flushing the chamber with argon to get rid of aggresive rests of the previous etching gas. No RF-power is used. This is good practice and should always be used after etching with Cl2. Please note that absolute maximum pressure for Set Pressure is 100 mTorr, and then the regulation is unstable. Always use 90-95 mTorr as your maximum set pressure.

When the recipe has run to its end, there is a yellow alert,
you just click accept to close the alert window.

Then the automatic unload procedure starts.

At end of session: Vent the load lock. Open load lock and remove your wafer. Close load lock. Evacuate load lock, Make note of you session in the log file, see below. Always read all prompts, do not just click "OK".

Please fill out the log completely:
date, name, complete recipe, what kind of wafer, if there were any problems.