Hello Evelyn,
I just happen to know what happened. Oxygen plasma oxidizes platinum.
You're likely measuring Pt-Ox. You can reduce the oxygen in a hydrogen
atmosphere. There are a number of references in a paper I recently wrote
(shameless plug):
Hydrogen Detection by Polyaniline Nanofibers on Gold and Platinum
Electrodes
Jesse D. Fowler, Shabnam Virji, Richard B. Kaner, Bruce H. Weiller
The Journal of Physical Chemistry C 2009 113 (16), 6444-6449
Jesse Fowler
>From Evelyn B
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