I would increase flow rates to reach a pressure of 100-200mT and boost power to
250-350W.  The white powder is likely sputtered silicon /silicon dioxide
redeposition. You might consider running a cleaning cycle before processing.
It's been our experience that this improves repeatability, particularly for a
multiuser piece of equipment.

-Michael Marin
 U. of Louisville

>>> Joseph Grogan  8/30/2007 3:58 PM >>>
Hi All,

We have a very old Plasmalab RIE in our facility that I tried using to
etch a Si wafer patterned with 1813 resist. I used the following parameters:

02 flow rate: 5 sccm
SF6 flow rate: 20 sccm
pressure: 20 mT
power: 150 W
time: 1 hr

I had hoped to get a depth in the neighborhood of 60um or more with
these settings (based on literature such as Williams' etch rates paper).
Unfortunately, I only got around 4.5 um deep, and that was only in the
center 2" of my 4" wafer. The outer 2" of my wafer was coated in an odd
white chalky film that smudged off a little if I wiped it.

Does anyone have a guess as to what my problem is?