Hello all,

I tried yesterday to introduce a layer of SU8 on the top of a layer of
exposed-SU8, i.e. the process was like this:

1) spin SU8, bake
2) expose in UV
3) develop -> a layer of hard plastic is formed
4) spin SU8 on top of the previous layer, bake.
5) photolithography some structures, bake, develop

However, there was a serious problem during the stage 4. The resist
refused to adhere to the layer no.1 (the hard exposed layer). The 1st
layer seems to act as "SU8-phobic": the spinned resist on it during the
bake gathered in big drops rather than remained uniformly spinned layer.

Have you ever met such a problem? Do you have any idea how to improve
adhession of SU8 to exposed-SU8?

Thank you,

Gorelick S.,
University of Jyväskylä,
Finland.