Has the resist been opened for longer than a year? If yes, I would say
it is probably due to excess water absorbed from the air in the resist.
You are trying to push the resist to the limits (thick layer, it's
designed for 1.1um thickness, btw), image reversal is always tricky.
What are your feature size? If you notice ragged walls, I bet it's
small.
And with a 2 year too old resist - no wonder it's not working very well.
The dehydration bake prior to application of PR is mighty critical.

-----Original Message-----
From: Krishna Vummidi
Subject: [mems-talk] 5214E resist

Im using 5214E in image reversal mode. below is my process

On Si wafers (BOE, Acetone, IPA clean)
spin: 2000rpm (2 um)
soft bake: 110C for 1m30s
expose for 10.4 sec at 8.7 mW/cm2 (i-line)
Reverse bake: 118-120C for 1m
flood expose: 90 sec same lamp power as above
dev: MIF-327 or AZ 400K (1:4) for 1m

After i develop, my resist doesnt seem to have a straight edge. the
walls are really rugged. the expiration date on the resist is 2003
march. is that an issue or do i have to correct my process. or is it the
surface preparation of my wafer. is the dehydration bake of Si wafer
before process that critical. The resist development seems to be better
in case of normal positive exposure. any thoughts, ideas are much
appreciated.

thanks,
krishna