Jeeva,

  The KOH concentration you used is too low (only ~10%). To get smooth  etched
surface, the KOH concentration has to be over 30% (w/w). Also,  higher the
concentration, lower the etching rate. If you want to get  more smooth surface,
you may add IPA. But it will lower the rate.

  Tom

jeeva S  wrote:  Hi all,
   I did KOH (anisotropic ) wet etching of silicon. I used 10g of KOH
pellets and mixed it with 100ml of DI water at 65 deg.
Then I immersed the Silicon substrate in this solution. After one minute (as
it was the time limit for 1 micron depth of substrate) when I removed the
substrate from this solution, it was rough on the surface and also it was
darkened (Black colored rough surface).
Can anyone explain me why this has happened and give me correct procedure
for the KOH wet etching with composition of KOH and water?