Thermal oxide is a very good mask for long TMAH etches (although not for
KOH).

David Nemeth
Senior Engineer
Sophia Wireless, Inc.
14225-C Sullyfield Circle
Chantilly, VA 20151

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Ziaur Rahman
Sent: Friday, May 12, 2006 2:08 PM
To: [email protected]
Subject: [mems-talk] TMAH Etching mask


I need to do anitropic etching of Si and planning to etch around 200 um.
  As we do not have DRIE we have to do wet etching. I tried KOH solution
  with different kind of masks like PECVD Nitride, Cr, Cr and Gold. But
nothing
  survived more than 2 hours. So I am planning to use TMAH for etching.

  What kind of material can  survive without peeling for more than 3 hours
in TAMH?
  I want to use sputter Cr. Is it a good idea? I know a lot of people are
using
  oxide and nitrides. But I prefer to use Cr as I have to etch for long
time.

  Any suggestions, comments will be highly appreciated.

  Best,