Pquest users' meeting summary

Roger T. Howe rthowe at stanford.edu
Wed Dec 1 22:22:55 PST 2010

Mary, Elmer, Jim, and Jim + PQuest user community:

Thanks for coming to a good solution on the PQuest.  Let's hope that a 
year from now, or sooner, we're dealing with the initial ramp-up of a 
new III-V etcher.

I'd have been there if I wasn't lecturing.


  On 12/1/10 6:39 PM, Mary Tang wrote:
> 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 
> you encounter.
> Team Pquest Etch (Jim and Jimmer, Elmer, Mary)

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