Hello,

  One problem of the double spincoat is the thickness is not uniform. I have
done it for couple times (I do not remeber the name of that PR), the thickness
in the middle of the wafer is thinner than the boundary. It means the thinkness
of the PR will increase gradually from the middle to the boundary. But hopefully
this will not affect your process.

  One more than may help is, you can slow the the speed of the spincoat to about
1000rpm, which may help you to get a thicker PR. But the spin time should be
longer, about 2 minutes.

  Good luck.
  CHEN

[email protected] wrote:
  Thanks a lot the input I've received. It looks like I have two choices.
1. Double spincoat with az4562 or 9260. Is there anything special in
the double coat process?
2. Ultrasonic development (I don't have magasonic transducer) using
su8. Recently I found my su8 doesn't stick very well onto wafer during
development. Features simply came off. This never happened to me
before. I was following the datasheet and not using HMDS or other
primer.