Chlorine at low flows ....

John Shott shott at
Thu May 29 15:51:14 PDT 2008

Raith community:

This morning, Elmer did a nice job of cleanly re-installing the local 
chlorine pressure regulator at the back of the machine so that it can 
control the chlorine pressure to the pquest without affecting pressure 
to either the lampoly or the p5000 etch.  I believe that he has it set 
at 8 PSI which we found allowed him to control flows to as low as 0.6 
SCCM and yet still get full flows in excess of 40 SCCM.  In the process 
of doing this, however, he also found that the zero on the flowmeter was 
off by a significant amount .... 1.1 SCCM as I recall.

I know that some of you run a recipe that has chlorine flows in the 1.5 
- 2.5 SCCM range.  As a result, particularly if your use one of these 
low chlorine flow recipes, I suggest that you do a test run to make sure 
that you are getting the etch results that you expect.

Secondly, we have received reports that the matching network (during 
auto match, I think) may be misbehaving.  At this point, however, it 
does not seem to be failing consistently.  Accordingly, it would be of 
great help to is if you could:

1. Keep an eye on the performance of the matching network during your 

2. If you see problems, please let us know what you observed and which 
recipe and RF power levels you found to be problematics.  This will help 
us to more quickly resolve the problems.



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