I etched SCQ a year ago in STS-AOE in our lab with a depth of 36um. If you
are interested with it please contact me.

If you want to use HF still, a high quality (LPCVD) nitride mask should be
tougher than Cr mask.

Good luck.

Hongjun Zeng, PhD
Microfabrication Application Laboratory(MAL)
University of Illinois at Chicago

-----Original Message-----
From:Oliver Horn
Subject: [mems-talk] How to etch single crystal quartz?

How to etch single crystal quartz? I tried HF (49%) at room temperture.
This had an etchrate of  only 3 um/h. I need to etch at least 40 um, and I
think my mask (Cr) will not withstand this long time. I also tried ammonium
fluoridel, this only etched 14 nm/h.