Mohamed,
If your mask is Si, use concentrated HF it is the fastest way. The etch will
be isotropic at best, unless you have very good adhesion between the Si and
the glass, the lateral etch rate will be higher than the vertical one,
especially at the interface. if you need better aspect ratio, try ultrasonic
drilling or abrasive blasting.
Good luck
Shay

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Mohamad Hajj Hassan
Sent: Friday, May 18, 2007 7:53 PM
To: General MEMS discussion
Subject: [mems-talk] wet etching of glass

Hello Everyone,

Could anyone provide me with a recipe for wet etching of glass to a depth of
500um? The masking layer is silicon, on which, a multilayer of metal Cr/Au
is
deposited.