Hi Vinay,

I think you have too much of IPA.  I would try 1-2% IPA. (i.e 1-2ml IPA for
100ml of Water+40gr KOH).

Serhan


From: Vinay 
Reply To: General MEMS discussion 
To: [email protected]
Subject: [mems-talk] KOH etching
Sent: Wednesday, January 11, 2006 4:55 AM
Hello all,
I am trying to etch Si using KOH. I tried various concentrations at
different temperatures and it looks 40% KOH [40gms KOH, 100ml water,
25ml IPA] at 80 degrees C works the best [15 mins of etching resulted
in a depth of 15um]. But i am unable to get a smooth surface. I see
black spots scattered all over the wafer. I was wondering if any of
you have experienced this before. Is there any other etchant or
another concentration of KOH that could be used as a 2nd step to
smoothen the surface, once the target depth is reached? Any
suggestions would be greatly appreatiated.

Thanks,
vinay