Andrea,

I've found that the biggest challenge when using evaporated metal this
way is particles.  Every particle results in a pinhole in your mask that
allows the etchant to get under the mask.

Dan

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf
Of Andrea Mazzolari
Sent: Friday, April 02, 2010 10:41 AM
To: [email protected]
Subject: [mems-talk] metallic mask

Hi all,

i need to thermal evaporate a metallic mask on a polished silicon wafer.
The mask should withstand 40% KOH etch for 5 hours.
I tried 20/30 Cr/Au, but it seams that it is not working: after about 1
hour etch many pinholes are generated in the Cr/Au layer, KOH penetrates
such pinholes and etch silicon.

Any suggestion on how to improve the resistance of Cr/Au layer ?
Any alternative to Cr/Au ?

Thanks,
Andrea