Gabe,

How thick are your SU-8 layers?

Is it the first soft bake that causes the problem?

Does the adhesion fail during or after the bake?

I did not have a lot of success with HMDS and Microchem's promoter
Omnicoat is for metals, not Si/SiO2.  The SU-8 normally has really good
adhesion to Si/SiO2.

I don't know what a YES oven is, but generally, you want to stay away
from ovens with SU-8.  You want hotplates so that the solvent bakes out
from the bottom up.

Here are some things to watch for:

Make sure you are baking the water out of the wafer before you apply the
SU-8.

Don't thermally shock it.  Make sure you are doing a two step or ramped
bake.  Let it cool on a thermal insulator, like a plastic container.

If your trouble comes after exposure, make sure you are filtering out
stray wavelengths shorter than i-line.

Hope this helps.

Good luck,
Greg Reimann
Boston University

--------------------------------------------------------
The SiO2 is currently present on the wafer.
Would the adhesion benefit from HMDS or perhaps a YES oven
process?

 - thanks - Gabe

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