RIE with pure SF6 tends to be isotropic.  Adding O2 will promote
formation of a sidewall inhibitor. With the right amount of O2 (10-50%)
in SF6, with RF bias on the substrate should give nearly vertical
sidewalls with minimal undercut.

Roger Shile

-----Original Message-----
From: baobao
Subject: [mems-talk] Any good recipe for Si etch in ICP?

I am trying to do some Si etch. I use SF6 and Ar.
I hope to get straight side wall that is around 1
micro deep. But when I cleave and look it using SEM,
there are some undercut and the side looks like wet
etch.

i am not sure if anyone can give me some idea about
the recipe that i could use.