Jeff,

SU-8 is a photopatternable epoxy, not a photoresist.

As such, once fully crosslinked (as is necessary for proper
development), it is impervious to pretty much all solvents, including
NMP, acetone, methanol, SU-8 developer (which is simply PGMEA).

I have seen studies that piranha can work, but it definitely has to be
at elevated temperatures, and it still can take many hours, or even
days.

I have also seen studies showing the successful ashing of SU-8, but
again is a long, drawn out process. The etch resistance of SU-8 is much
greater than standard photoresists.

SU-8 is not intended to be used in place of a standard resist - it is
not intended for masking or molding purposes, since it cannot be
removed.  Instead it tends to see use as a permanent portion of the
device structure.

If you wish to have a material of a similar performance to SU-8 but is
removable, look into KMPR 1000 from MicroChem (the same guys who
manufacture SU-8).

Best Regards,
Chad Brubaker


-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jeff chen
Sent: Monday, July 24, 2006 8:47 AM
To: [email protected]
Subject: [mems-talk] SU 8 removal

Hi, all,

Does anyone have some experience to completely remove SU8 after
development?
I tried PG Remover and it didn't work well. And also plasma cleaning
under oxygen, still not working.