Dear Lin,

In my work with KOH etching. A 0.6 micron Silicon dioxide mask lasted
for 1 hour and 30 mins for a conc. Of 40-45% and temp of 85 degrees. The
etch selectivity for nitride must definitely be a lot better. The
stirring rate is also really important and is good to keep it quite
high. Make sure the there is easy access for the etchant to attack the
etch surface.

Hope it helps!
Regards Ashwin

-----Original Message-----
From: mems-talk-bounces+ashwin_uta=hotmail.com@memsnet.org
[mailto:mems-talk-bounces+ashwin_uta=hotmail.com@memsnet.org] On Behalf
Of g915705@oz.nthu.edu.tw
Sent: Saturday, May 01, 2004 9:38 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Mask against TMAH and KOH Etching

Dear all:

I have questions about the TMAH and KOH etching.
I use a layer of LPCVD nitride with 1500A thick.
After 3 hours KOH etching (30% w.t., 80C), the nitride layer is etched
seriously.
Similarly, the nitride layer cannot survive in TMAH (8% w.t., 90C) for
more than 5 hours.
Is there any method or material that can be used as the etching mask in
TMAH and KOH for at least 11 hours?
Please give me some advice.
I really appreciate it.

Regards,

Y.C. Lin

Dept. of Power Mechanical Engineering,  National Tsing Hua University,
Taiwan.








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