If oxide is preferred I would recommend thermal oxide which is stronger as
mask material than PECVD oxide. However, for Liu's case, using all kinds of
oxide will meet challenges of selectivity. The best selectivity of the best
oxide is ~1:100. So 550 um wafer needs >6 um oxide. It is hard to get so
thick.
Strong baked thick resist is still the solution for his case. If still not
enough, combined mask of resist and oxide is an option. If the feature size
is not critical, it SHOULD strong enough.
Best,
--------------------------------------
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 Xiaoguang "Leo" Liu
Sent: ה 31 אוגוסט 2006 23:24
To: General MEMS discussion
Subject: [mems-talk] Metal mask for DRIE
Dear all
I'm trying to do a through wafer etch (550um) using silicon Deep RIE.
I've tried with the AZ9260 photoresist. However, the reflow of the
photoresist after hard bake makes the etching profile non-uniform.
Does anybody know if metal can be used in the DRIE process. I've heard
that people have done 2mm etching using Ni as a mask. However, our
staff here says metal is not allowed in the chamber. It would be great
if anybody could give some references on that. Thanks a lot
