Hi all,
   Few days back I sent a mail to the group saying that a silicon sample
(subjected to wet etching) was black on the surface.
I corrected it from some of your replies asking me to use 40grams of KOH
with 100ml of DI water and 2 ml of IPA. I got a perfect silicon wet etched
sample. Thanks for all your help.

Now that I got a perfect wet etched sample, I was wondering why was it black
on the surface when I used 10 grams of KOH. Is it because of KOH and Silicon
reaction?     In that case, teflon coated on silicon substrate will not be
affected by this KOH. But my sample as a whole was blackened on the
surface.(My sample is teflon coated silicon substrate with patterns on
teflon layer)

 I request you to explain me the reason for the blackening.

Thanks in advance,
Regards,
Jeeva S