Evelyn,
      Are these thickness test wafers, patterned wafers, product wafers
in process? How did you measure it? Did you take a V/I measurement, a
profilometer, X-ray fluorescence, or other?

Ed

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Evelyn B
Sent: Tuesday, April 28, 2009 6:05 PM
To: General MEMS discussion
Subject: [mems-talk] Ashing effects


To all,

I measured the average thickness of a Ti/Pt stack-up on a Si wafer at
three different locations as summarized below:

                  *  Before ashing        After ashing      Delta*
Structure #1: 139.7 nm              219.00 nm         79.30 nm
Structure #2: 122.5 nm              199.75 nm         77.25 nm
Structure #3: 117.0 nm              200.00 nm         83.00 nm

After doing the ashing I did not observe any damage to the Pt layer but
can't explain the increase in thickness above, especially when I had
already calculated an etch rate of 11 nm/min and had only etched for 3
minutes.  The ashing recipe is 150 W, 44 sccm, 250 mT for 3 minutes in
O2 plasma (PE mode).

Can anyone think of anything that could cause a change of 80 nm in
thickness?

--
EVELYN BENABE