Message-Id:   <199802150639.WAA21659@mail1.teleport.com>

Yagang- The premiere source of etching techniques is the J. of the
Electrochemical Society. I seem to remember from my past in IC research
that dilute HF will etch SiO2 but not strongly attack Al2O3, but _please_
check this before you try it. Also, if you use HF, be very careful.

Charles Bickford