I tried a number of wet etchants on sapphire and found nothing that really
worked because sapphire is so inert. Some kind of sputtering like ion
milling with argon will etch anything because it's a physical removal
process.

   --Kirt Williams

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf
Of G. Puebla-Hellmann
Sent: Tuesday, June 14, 2011 1:06 PM
To: [email protected]
Subject: [mems-talk] Etching 200 nm into a Saphirre Wafer

Hi,

I need to isotropically etch ~200 nm into a saphirre wafer to suspend a
small gold wire. Unfortunately I don't have access to an ICP RIE, and
H2SO4 with H3PO at 300 plus degrees is not an option. The etch does'nt
need to be fast, it can take a couple of hours if necessary. I tried
HF,BHF and NH4OH at 80 degrees, but so far the only etching is into the
niobium metallization ( which will be masked on the final wafer ). Does
anyone have any suggestions?

Thanks for your help,

Gabe