To increase the selectivity, you can

1. Make a long hard bake for the photoresist.
2. Reduce the RF power.
3. Increase the chamber pressure.

I used Shipley 1818 (also about 1.5um thick)for mask of Bosch process DRIE.
It survived even 20 minutes etch.

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: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of K. V. Sridhar
Sent: Tuesday, February 07, 2006 10:38 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Photoresist RIE

Hello All,

I am using photoresist AZ5214 (thickness 1.5um) as a
mask for my ICP-RIE process(SF6 gas ) and the resist
dosent last for more than 2 min . I am  looking for a
photoresist that would last atleast 10 min. Can anyone
suggest a process involving photoresist lasting for
more time regarding the above.