Pquest users' meeting summary
mtang at stanford.edu
Wed Dec 1 18:39:56 PST 2010
Dear pquest users --
Many thanks to those who attended and for the contributions by those who
couldn't. The meeting was well attended (even two faculty!) and
well-represented by many different groups. Here's a summary:
1. Chlorine versus fluorine, 2011. Because there are many more
chlorine than fluorine users, it was decided to increase the
chlorine-only time. Starting in 2011, the schedule will be 1.5 weeks of
chlorine-only after chamber clean followed by 0.5 weeks of
fluorine-allowed. Chamber cleans will be done on alternate Fridays.
This will keep the current chamber clean frequency, which is good, and
allow fluorine users access twice/month.
2. Chlorine versus fluorine, 2010. The system will remain
chlorine-only until next Friday, Dec. 10, when it becomes
fluorine-allowed. A chamber clean will be done over the shutdown.
3. Process problems. Several people have observed variable etch rates
in ZEP, PMMA, and GaAs. One group's problems seem to be recently
resolved. Some reminders on pquest operation which will help with
process control: monitor DC bias voltage (and adjust RF accordingly);
run O2 clean until DC bias stabilized; check (and rezero if needed) the
VAT pressure controller; run recipes with chlorine flows within
controllable range (3 sccm is recommended); use ellipsometry to measure
resist thicknesses below 1000 A.
4. Shutdown. Elmer plans to repair the noisy clamp, clean the chamber,
check for chips in the darkspace, and adjust the clamp pressure to try
to get the helium blow by down a little. Stray chips in the darkspace
have been historically known to cause variable etch rate or plasma
flickering. The clamp pressure is a balancing act between good backside
cooling and wafer breakage so needs to be done carefully.
5. Other stuff discussed: instituting logsheet data entry on Coral
disable - this will allow us to collect and monitor data (like DC bias);
defining a basic process qual, to check machine functionality;
temperature dots are available to check for substrate heating; optical
spectroscopy testing for fluorines or chamber cleanliness.
Again, thanks all. We would also like to encourage everyone to share
observations about pquest process performance, especially any problems
Team Pquest Etch (Jim and Jimmer, Elmer, Mary)
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA 94305
mtang at stanford.edu
More information about the pquest