Nitin, can you do it mechanically by lapping or polishing, SiO2 is very
soft compared to Al2O3.  If you polished with Cerium oxide for instance you
could likely remove the Silica and not begin to touch the Sapphire. Gary

Gary Hillman
Service Support Specialties, Inc.
9 Mars Court
PO Box 365
Montville, NJ 07045
973-263-0640
973-263-8888.

-----Original Message-----
From:   Nitin Shukla [SMTP:[email protected]]
Sent:   Wednesday, March 14, 2007 10:37 AM
To:     [email protected]
Subject:        [mems-talk] Etching SiO2 but not sapphire!

Hi,
  I want to remove a thin layer of SiO2 (200 nm)  from my sapphire wafer. I
tried using HF but it etches sapphire as well. Can anyone suggest me what
chemical do I use to remove oxide but not sapphire.