Try to use vapor HF etch system.

Xu

-----Original Message-----
From: Oudalov, A. (EL) [mailto:A.Oudalov@el.utwente.nl]
Sent: Sunday, October 24, 2004 12:50 PM
To: 'mems-talk@memsnet.org'
Subject: [mems-talk] Sticking of fragile MEMS structures

Hi there,

I am trying to release a comb drive structure etched by deep reactive
ion
etching (DRIE) on a SOI silicon wafer. I try to make very thin gaps
between
the comb drives to have a large electrostatic force. Since the spring
constant of my supporting structure is small I get problems when I
release
the chips in buffered hydro-fluoric acid (BHF). The adjacent combs stick
permanently and the device is broken. I also tried critical point
drying,
the yield is little higher but not satisfactory. Who knows about
another,
more gentle method to release my combs?

Thanks a lot,
Alexander