When you say you "could not get the features cleared" do you mean that
you could not fully dissolve the unexposed areas, or did you meant
that all the SU8 washed away with nothing remaining? You need to
clarify more what you meant by "I did not get anything useful."

Also, 4um features on a 5um thick resist will require some care. You
have to make sure the exposure gap is minimized and the edge bead is
not large.



On Tue, Jan 10, 2012 at 1:26 PM, Yingtao Tian  wrote:
> Hi Everyone,
>
> I would like to ask advice for SU-8 processing because this is my first time
to use this famous stuff. I just tried to put down 4-5 um thick SU-8 5 resist
and follow the recipe from MicroChem. However, I did not get anything useful.
>
> The sample was Au coated silicon wafer, soaked in acetone for 5 mins, rinsed
with IPA and dried. The wafers were put in the oven at 150 degree for 20 mins to
dehydrate. Spin coating consists of two steps: 500 rpm, 100 r/s acc for 10
seconds; then 4000 rpm, 500 r/s for 30 seconds. Soft bake was done at 65 C for 1
min then 95 C for 3 mins. Exposure time ranged from 7 seconds to 10 seconds.
Post exposure bake was done at 65 C for 1 min and 95 C for 1 min. Development
was done in EC Solvent for 10 mins.
>
> Most of the features were about 4 micron big with relatively large pitch size.
However, I could not get the features cleared.
>
> Anybody has some ideas or suggestions on this? Any reply will be appreciated.
>
> Thanks,
> Yingtao