I had the same problem: my photoresist (s1813) was under-exposed.

Andrea

-----Messaggio originale-----
Da: [email protected] [mailto:[email protected]] Per
conto di madhav rao
Inviato: venerdì 15 agosto 2008 19.39
A: [email protected]
Oggetto: [mems-talk] Photolithography - Resist peeling

Hi,
       I am experiencing a problem in patterning on silicon-di-oxide wafers;
I am using SHIPLEY 1818 resist to get a thickness of 2.5 micron; 6 seconds
of exposure time. After developing for 60 seconds, I observe, the resist
layer peels off; leaving no patterns on the wafer. Also I had soft-baked the
resist at 95 C for 2 minutes in hot-plate.
This seems strange to me, as a month ago, I had successfully transferred the
patterns on to silicon-di-oxide wafers.
I am using mylar film masks.
Please let me know, if any one had experienced similar problems before; and
if so, could you let me know suggestions to solve ?

Thanks

Regards,
Madhav Rao,
Graduate student,
University of Alabama.