Dear all,
i am using SU-8 25 to fabricate a 27 micron feature on a 3 inch
glass wafer (Ti seed layer).After the completion of this process, i am
fabricating a 200 microns thick channel as a second layer using SU-8
50.The process parameters for the 200 microns are the following:
200 process parameters (7ml SU-8 50)

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Spin: 500rpm for 10sec (100rpm/s ramp)
    1500rpm for 30 sec (300rpm/s ramp)
i.e 500.100.10 and 1500.300.30

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Leave for 1 min

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Prebake : 65C for 6 minutes and 95C for 22 minutes
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Exposure: 160microJ/cm2
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Postbake: 2min at 65C and 95C for 7 minutes
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Development: 8-10 min with EC Solvent, Clean with IPA afterwards

The problem is that during the prebake phase,the su-8 wrinkles
irreversibly.as a result the structures are very rough
I would very much appreciate any help and/or recommendations on this
problem.Thank you in advance for your help.I am looking forward to your
reply.


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