CHF3 is often used for etching SiO2.

I have had good results using both nickel and chromium as masking materials
for deep plasma etch applications.  Aluminum can also be used but, but
unless it is sufficiently thick you may sputter it away before your etch is
complete.
-----Original Message-----
From: Wouter van der Wijngaart 
To: [email protected] 
Date: Tuesday, March 30, 1999 6:51 AM
Subject: DRIE etching of pyrex/quartz/other glass


>Dear MEMS society,
>Has any of you heard of /experience with Deep Reactive Ion Etching of
>glass/pyrex/quartz substrates ?
>We want to etch in the range 20-100 5m with vertical sidewalls.
>Which mask materials should be used ?
>Any comments and/or etch recipes are welcome !
>Sincerely,
>Wouter
>
>