request for a pquest user meeting very soon

Randy True true at snf.stanford.edu
Wed Jun 18 15:40:36 PDT 2003


Pquest Users, Dr. McVittie, and Henry:

In the past couple weeks, I have heard rumors about GaAs users having 
problems with their processes and the possibility of restricting the 
access of non-GaAs users to the pquest. Technical problems with standard 
etch processes (such as etch rates and strange films being deposited) 
should be logged in the log book and if serious, sent out to the 
pquest at snf email list or typed up in coral. I propose that we have a 
pquest users meeting in the next couple of days to discuss these issues. 
In the meantime, can all users who have had problems in the Pquest in 
the last month, please send out an email to pquest at snf describing the 
probelms in detail, so then we can complie a list and make informed 
decisions.

I informally found out today that there was a problem with a film being 
deposited on a dummy wafer and Dan Pickard sent the film out for 
analysis and determined that the film was particles of silicon oxide. 
This is significant information that needs to be shared with all pquest 
users. I had problems plating into wafers etched on 6/4, and I thought 
this was due to an adhesion problem. But now that I know that people 
have seen unwanted films deposited in the Pquest, I am also considering 
that as the source of this problem. I always etch do a 20min seasoning 
with my recipe on the Si dummy wafer and did not see any obvious film 
deposition. Dr. McVittie told me today that the system went through a 
wet clean on Mon. Have the GaAs users with problems done any etches 
since then? Are the problems still there?

 This is why it is important for users to COMMUNICATE about technical 
problems with a machine. I realize that users may want to take some time 
to figure out what the problem is, but the current situation has gone 
far past that. GaAs users have substantial problems and instead of 
addressing them in an open format, they are having important discussions 
behind closed doors. That is simply not right. I and other non-GaAs 
users have spent considerable time and money developing processes on the 
pquest and we should have a voice in talks about policy changes. If you 
are a non-GaAs user and you want to keep using the pquest, then please 
speak up before it's too late.

I completely agree that maintaining GaAs etch processes is a top 
priority, but I think that the current problems can be solved without 
drastic changes in the materials policy of the pquest.  There are 
approved processes that can be run concurrently with GaAs etching, and 
problems with GaAs etching will most likely also cause problems with 
these etches. As a first step to preserving all approved processes (GaAs 
and non), we need to come up with good diagnostics to determine if 
chamber conditions are abnormal, and then good cleaning procedures to 
return the system to normal. Problems with GaAs etching are a recurring 
issue (see pquest archive from last summer) and we need to solve it once 
and for all. Let's all get in the same room and figure this out.

--Randy True


Summary of my recent problems:
5/20 - good etch, no plating problems
6/4 - bad etch, at least 10% reduction in etch rate, no plating

Data on Pquest Usage:
June 03    45 Logs, 14 Users, Non GaAs Materials: PI, Cyclotene, 
Al/Ti/Er/Yb, SiO2, Ni, Zr0, Al
May 03    49 Logs, 13 Users, Non GaAs Materials: PI, Al/Ti/Er/Yb, SiO2, Ni
April 03    12 Logs, 6 Users, Non GaAs Materials: PI, SiO2
Mar 03    18 Logs, Non GaAs Materials: PI, Al/Ti/Er/Yb, SiO2
Feb 03    10 Logs, Non GaAs Materials: PI, Al/Ti/Er/Yb
Jan 03    20 Logs,  Non GaAs Materials: PI, Al/Ti/Er/Yb

More info on pquest usage for the last year, including when new 
processes were introduced, are listed on my cube.




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