I've two suggestions

If you can modify your structures try to minimize footprint of SU-8. e.g by
introducing cavities into large structures etc.

Try a prolonged soft PEB bake (50 C 5-15 min) and then a regular PEB

Regards

Erhan Ata
-----Original Message-----
From: Thomas KF Lei [mailto:kflei@acae.cuhk.edu.hk]
Sent: Wednesday, July 02, 2003 9:38 AM
To: General MEMS discussion
Subject: Re: [mems-talk] SU-8 problem


Greg Reimann,

Thank you for your suggestions.
Actually, I tried using hot plate before. But I also have the same symptoms.
When PEB temperature goes over 60C, the surface of SU-8 becomes wrinkling
every time.
And I would like to ask whether the SU-8 pattern appears after exposure
before PEB?
I tried two cases:
board band UV: after 10secs exposure, SU-8 pattern appears before PEB.
board band UV with WB-360 fiter(360nm high pass): after 900secs exposure,
SU-8 pattern doesn't appear before PEB.
Thank you very much.

Regards,
Thomas

----- Original Message -----
From: "Greg Reimann" 
To: "'General MEMS discussion'" 
Sent: Wednesday, July 02, 2003 11:41 PM
Subject: RE: [mems-talk] SU-8 problem


> Thomas,
>
> Try switching at least your soft bake to a hot-plate. Microchem wrote
> all of its specs with hotplates in mind, so in an oven you may not be
> baking of all of the solvent, or more likely given your symptoms, you
> are baking off the top layer of solvent and trapping the rest in lower
> layers which dissolve in the develop.
>
> Since a hot plate heats from the bottom, this is less likely to happen.
>
> Greg Reimann
> Boston University
>
> -----Original Message-----
> From: mems-talk-bounces+gjreiman=bu.edu@memsnet.org
> [mailto:mems-talk-bounces+gjreiman=bu.edu@memsnet.org] On Behalf Of
> Thomas KF Lei
> Sent: Wednesday, July 02, 2003 8:16 AM
> To: mems-talk@memsnet.org
> Subject: [mems-talk] SU-8 problem
>
> Dear collegues,
>
> I have some problems in doing MicroChem SU-8 2075 PR on Si. My process
> is:
> spin 500rpm and 3000rpm 30secs
> soft bake: 95C 15mins in oven
> UV explore with filter WB-360: 300secs
> PEB: 95C 10mins in oven
> Develop: about 10mins
>
> I found that the surface of SU-8 becomes wrinkling after PEB and my
> pattern peer off after develop. Can anyone give me some suggestions?
> Thank you very much.
>
> Thomas
>
> _______________________________________________
> MEMS-talk@memsnet.org mailing list: to unsubscribe or change your list
> options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk
> Hosted by the MEMS Exchange, providers of MEMS processing services.
> Visit us at http://www.memsnet.org/
>
>
> _______________________________________________
> MEMS-talk@memsnet.org mailing list: to unsubscribe or change your list
> options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk
> Hosted by the MEMS Exchange, providers of MEMS processing services.
> Visit us at http://www.memsnet.org/