If the walls are next to one another, then you could e-beam deposition metal
using a shadow mask and a 45 degree angle between them with a 45 degree
offset of the rectangular hole in the mask to the hole in the substrate. If
you need them opposite, then you can use a shadow mask with the wafer at 45
degrees to the mask and the sidwalls aligned to the shadow mask opening;
then rotate the wafer 180 degrees and deposit again.

They probably won't be very uniform coatings though. Also, make sure that
all the polymer from the DRIE process is gone.

Mike


Dr. Michael H. Beggans
Naval Surface Warfare Center, Indian Head
101 Strauss Ave. Bldg. 302            Phone: (301) 744-1927
Indian Head, MD 20640                  Fax:    (301) 744-6406

-----Original Message-----
From: Xiaoguang "Leo" Liu [mailto:liuxiaoguang@gmail.com]
Sent: Friday, October 13, 2006 7:32 PM
To: General MEMS discussion
Subject: [mems-talk] Partial Metallization of Vertical Walls

Dear all
I've been working on a project in fabricating cavity electromagnetic
resonators that require partial metallization of the side walls. For
example, I would like to produce a rectangular cavity  in the silicon
substrate by DRIE. I would then want 2 of the 4 side walls to be metallized
with gold while keeping the other 2 silicon. I've thought really hard about
this but could not find a way to meet the requirement. The cavity in
consideration is about 1mmx1mm big.

Does anybody have good suggestions? Thanks a lot