You could also oxidize and then strip the oxide off. Any angled areas (hole
edges) will be rounded off. I used this to clean up rough polished wafers
for bonding.

It won't get you more than about a micron taper though so if you need more,
do an isotropic wet etch.

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: Roger Shile [mailto:[email protected]]
Sent: Monday, February 05, 2007 4:14 PM
To: 'General MEMS discussion'
Subject: RE: [mems-talk] DRIE etching : how to enlarge the cavities

Does "un DRIE etching" refer to filling the hole that you previously etched?

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of RABBIA Laurent
Sent: Monday, February 05, 2007 12:37 AM
To: '[email protected]'
Subject: [mems-talk] DRIE etching : how to enlarge the cavities

Hello everybody,

After un DRIE etching (Bosch process), I would like to enlarge the entry of
the cavities.

I heard about :

- HNO3/HF
- TMAH
- KOH
- different post-bake for photoresist

Has someone already done this ?

If yes, what's the process to follow ?