Dear Mr. Williams,

  Thanks for your suggestion. I did use the sputter clean before doing the
sputter coating. I will reduce my film thickness and planning to clean the wafer
backside
  before doing the 2nd coating. Backside Cr of the wafer was peeled off but the
front
  side Cr became dull. So I I assume Cr was also etching in KOH. Do you have any
good recipe for Cr sputtering?

  I highly appreciate your kind cooperation. Thank you once again and with best
regards,

  Zia

Kirt Williams  wrote:
  Zia--

Peeling is partially the result of poor adhesion, which is often due to the
surface being dirty.
Because you have Cr on both sides of the wafer, I'm guessing that you coated
the top side first, then flipped the wafer over and coated the back.
The back may have gotten dirty during this process.
One solution would be to use Kapton (polyimide) tape or a metal clip to hold
your device wafer to a clean dummy wafer.
If you can sputter-clean the surface of your wafer, do that as well.

Another thing that helps a film peel is high stress, either tensile or
compressive. The worse the adhesion and the thicker the film, the less
stress it takes for the film to peel.
Due to the relatively low pressure you are using, you might double the
sputtering pressure to shift the stress toward tensile.
If you have a wafer-curvature-measurement tool, you should use it to
determine stress and adjust the pressure accordingly.

I would not recommend annealing the Cr, as it will form chromium silicide
above some temperature, which may be harder to remove.

--Kirt Williams