Joe:

Those conditions should have produced a much deeper etch than that so there must
be something wrong with your etch tool. What was the reflected power indicator
during etch. If it was less than 10 watts then it should have etched properly.
If not you might get the results you described. Might not be a bad idea to run
at a higher pressure say around 100 mtorr as SF6 being electronegative can be
hard to tune to under certain conditions. Bob Henderson


-----Original Message-----
From: Joseph Grogan 
To: General MEMS discussion 
Sent: Thu, 30 Aug 2007 12:58 pm
Subject: [mems-talk] RIE Question

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??