You could try greatly extending the time, and perhaps also increasing
the temp, of the initial softbake to drive out more solvents prior to
exposure/develop/hardbake.  I would make sure your softbake temperatures
are well above the hardbake temperature also (maybe try 105 degrees C
for softbake when hardbaking at 85 degrees C).

For example with AZ4620, we sometimes use 60 minute convection bakes.
The longer exposures and develops are followed by a 30 minute hardbake
at the same temperature and very little sidewall change occurs.

AZ9260 may be tougher because it may have an even slower photospeed if
you softbake it so long.

- Justin

Justin C. Borski
MEMS Program Manager
Advanced MicroSensors Inc
www.advancedmicrosensors.com


-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Xiaoguang "Leo" Liu
Sent: Thursday, August 31, 2006 6:25 PM
To: General MEMS discussion
Subject: [mems-talk] Photoresist Hard Bake question

Dear all
I'm using AZ926 photoressit for a thickness of 20um. However, after
hardbake (85 degree C for 20minutes), the photoresist reflows and does
not maintain the near vertical profile. I wonder if anybody knows anyway
to prevent the reflow of photoresist during the hardbake process?