Try using more resist and slowing down the spin speed.  Alternatively, use a
double coat process.  I have had much success with a double coat process to 500
µm using SU-8 2100.

Best Regards,
Garrett Oakes

EV Group
invent * innovate * implement
Regional Sales Manager North America - Direct: +1 (480) 305 2443, Main: +1 (480)
305 2400 Fax: +1 (480) 305 2401
Cell: +1 (480) 516 6724
E-Mail: G.Oakes@EVGroup.com, Web: www.EVGroup.com

-----Original Message-----
From: jiang Liudi [mailto:ldjiang@hotmail.com]
Sent: Wednesday, August 06, 2008 5:51 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Su 8 thickness

Dear all,

I was trying to obtain >100um thick of patterned SU8 2075. The used receipe is
as follows:

spin: 500rpm/10s+1700rpm/30sec
soft bake: 65 C/5 mins +95 C/20min
UV expose: 28 sec.
PEB: 65 C/5 mins +95 C/10 min
develop: 10 mins.

all designed patterns are large ( all around 50-200um). However, using profiler,
the  step of the developed patterns is only about 66 um thick.

Could anyone kindly suggest the possible reasons for such thin resist?

Many thanks.
Jiang