Xiang,

As Florian has said, SU8 is not a good masking material. Generally SU8 is
good for fabricating devices or molding masters, but not mask. If you want
to use negative resist, S5214 might be OK for you considering your Si
etching is only several microns (piece of cake for Bosch tube!).

Good luck,

Hongjun

------------------------------------
Hongjun Zeng, PhD
MEMS/Nano Scientist
Nanotechnology Core Facility
(NCF formerly MAL)
University of Illinois at Chicago
3064 ERF Building
842 W. Taylor St., Chicago, IL 60607
Tel. 312-355-1259, Fax: 312-413-0447
------------------------------------



-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of D. Zhou
Sent: Monday, July 31, 2006 9:17 AM
To: MEMS_BBS
Subject: [mems-talk] Patterning SU-8 for DRIE process

Dear all,

I am trying to use SU-8 photoresist as the etch mask for the DRIE etch of
Si substrate ( ~5um (or above) thick resist is needed). Did anyone have any
experiences in this? What is the selectivity of the typical Bosh process
between SU-8 and Si? And how can I pattern it (typical recipe for UV
exposure and development)? I have not used SU-8 before and hope someone can
give me a hand. Many thanks.