Try evaporate CrAU or magnetron sputtered CrAu. With 48% HF

-----Original Message-----
From: mems-talk-bounces+shay=mizur.com@memsnet.org
[mailto:mems-talk-bounces+shay=mizur.com@memsnet.org] On Behalf Of Xin Yan
Sent: Monday, December 13, 2010 2:50 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Adhesion problem during 7740 glass wafer wet etching
process

Hi everyone,

i want to etch the 7740 about 4 to 20 um deep.  Using Cr with Photoresist
5214E  as the mask,  Cr layer was produced by DC sputtering about 200nm
thick. The etchant is 1 HF : 2 HNO3 : 2 H2O to get high etch rate about
2um/min  to the 7740.

we met a problem that  Cr can not stand in this solution even 2minutes.
 After about 2 min, Cr begin to  peel off.

 In the 49%HF without HNO3, Cr cannot stand even 1minutes.

what cause the Cr so unstable or it is supposed to be like this?  or  i need
to change the etchant ?

Thank you

Yan Xin