Hi everyone

I'm facing a severe problem of stripping off of the patterned Post
Exposed Baked resists [negative resist, for both SU-8 25, SU-8 100 ]when
the wafer is immersed into a BOE solution.

I am following the receipe bellow for SU-8 100 from MicroChem

Substrate: SiO2 over Si

Clean: using acetone and methanol in an ultrasonic bath, rinsed in  a DI
tank.

Dehydration Bake: at 200C, over a hotplate, for 10 min

Spin Coat: for 10 sec upto 500rpm/s and then 30 sec upto 3000 rpm/s

Pre Exposure Bake: using hot plate,10 min at 65C, then 30min at 95C

Exposure: Sufficient [e.g. 60 sec UV exposure in a Cobilt Alligner]

Post Exposure Bake: using hot plate 3 min at 65C, then 10 min at 95C

Develop: 10 to 15 min in Nano SU-8  developer

Rinse and Dry: Rinsed with IPA and Nitrogen blow dried.

But when i dip this wafer into BOE, the patterned  resist just comes off.
Where is the mistake that i'm doing in all those steps??

I'd appriciate any sort of suggestion as i need to overcome this problem.

Thanks

M A Hadi

CISM- The Ohio State University

Columbus, Ohio

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