Hi JJ--

In my etch-rate tests, silicon dioxide sputtered with an ion mill had about
the same etch rate in 80 deg C KOH as did thermally grown silicon dioxide.
Normally oxide etches too fast in KOH to be used as a mask. In your case,
you're only etching down about 1 um, so the oxide should work OK. Note that
the longer you leave your wafers in the KOH, the more the oxide mask will be
etched sideways, making your trenches wider.
For the densest, sturdiest oxide, sputter at a high power.

   --Kirt Williams


-----Original Message-----
From: mems-talk-bounces+kirt_williams=sbcglobal.net@memsnet.org
[mailto:mems-talk-bounces+kirt_williams=sbcglobal.net@memsnet.org] On Behalf
Of JJ HU
Sent: Saturday, February 11, 2012 10:26 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Sputtered oxide as KOH anisotropic wet etching mask

Hello everyone,

I am planning to perform some KOH anisotropic wet etching of silicon to
create V-grooves with ~ 1 um width, and for that I am wondering if I may use
sputtered oxide as the etch mask. I have seen a lot of papers using thermal
oxide but I would like to see if sputtered oxide would work as well, since I
have easy access to a sputtering station. Any advice would be very much
appreciated!

Thank you in advance,
JJ