Hi All:
What are the possible causes of a flickering plasma in an
RIE system?  We have an ICP-RIE system and the plasma
flickers at any pressure above 4 mT or so.  This was not
observed in the system until the past few weeks, and the
system is about 6 years old.

I have cleaned the chamber thouroughly (flickering plasma in
the past has been an indication of a dirty chamber) and yet
the plasma still flickers at all but the lowest pressures.

Also, it the system will glow with a dim, very unstable
plasma at low power levels ( < 30 W RF1 ) even though the
matching network tunes to 0 reflected power.  Through manual
tuning of the matching network, I can get a bright, much
more stable plasma (also with 0 reflected power).  This
might be a sign of something wrong with the matching network
and possibly unrelated, but I thought I'd mention it.

Any thoughts on this are greatly appreciated!

Bill Lanford
University of Illinois
Micro and Nanotechnology Laboratory