You can use a chromium/photoresist mask and etch in a HF:HNO3:H20 mixture.
If you clean the glass and chromium you get a pretty good adhesion and get
isotropic etching.

/Mikael

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of Nathan McCorkle
Sent: Tuesday, November 03, 2009 1:52 PM
To: mems-talk
Subject: [mems-talk] Looking for a way to do deep etch in glass (25uM)

I am currently working with lexan (polycarbonate) and am experiencing
optical blurring when I use O2 plasma etch for too long, as well as
warping. I have decreased power and time to alleviate this problem,
but it takes many more runs to achieve the 20 - 30 micron etches that
I desire.

I asked an advisor about switching to glass, maybe a quartz or
borosilicate, and he said that I would need a gold hard mask to get
around having mask lift off during etch. I feel like there should be
some way to get a nice isotropic etch with a glass, using the current
lab equipment that we have.

Any ideas?

Nathan McCorkle