I think the answer depends on your bonding polymer, also the glass
composition.

If your glass is an alkali oxide glass (soda glass) then you could etch
the glass with NaOH or KOH. However, if your polymer reacts in base that
would not be good. The advantage of this is that you aren't working with
fluoride solutions.

I think that a fluoride solution that was buffered, Buffered Oxide Etch
(BOE), would be best. It could etch the glass with soda glass or just
SiO2, be at a pH near 7, and not either acid hydrolyze or base hydrolyze
the polymer.

I would also, not let the wafer sit in the solution long after you get
the glass etched off. Minimize exposure to the wet chemical.

It might be possible to get the polymer/glass interface to break down
and just lift off the glass. A hot acid solution might do it or base
system might do it. Though again, there is risk of chemical attack or
hydrolyzation of the polymer film.

Ed Sebesta


-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of NL
Sent: Wednesday, September 02, 2009 4:00 AM
To: mems-talk
Subject: [mems-talk] Glass Etching


Dear All:

  I'm working on silicon-glass bonding with polymer. Now I want to
inspect the interface between silicon and glass. Though the glass is
transparent for optical microscope inspection, the uncovered interface
is better for me. Thus I need to etch the glass without hurt the polymer
interface. Are there some good methods for this purpose? Hope for your
help.

Best Regards!

Bugnie
KAIST, ROK
bugnie@163.com
2009-09-02