This is a well known polymer that is deposited during that type of
process, many use this to their advantage as it can be manipulated
greatly to achieve all kinds of parameters. You can also try CF4 or
C2F6, with all of those you can add just a little O2. Then with some
tweaking you should have a great recipe. Remember with Gases and Plasma
you have many parameters to tweak, keep lots of notes and only change
one thing at a time. Eventually you will have a great number of recipes
with information on what each does best.

Good luck,

Joe Lonjin
Penn State Nanofabrication Facility

-----Original Message-----
From: Shile [mailto:rshile@nanoink.net]
Subject: RE: [mems-talk] About the RIE etch of SiO2

With CHF3 RIE of SiO2 there is a tendency to leave what I call a phantom
film on the underlying silicon.  This can drive you nuts because it
looks like a thin oxide remaining.  A few years ago I read a study that
indicated that a fluorocarbon was left on the Si, under which was a
layer of fluorinated Si.  Damage to the Si extended as deep as a micron.
Adding oxygen to the CHF3 may reduce the amount of polymer left behind
at the expense of selectivity.

Roger Shile