Connie,

Most likely you have a wafer that was slightly offcut from the <110> plane
which would result in angled channels.  Where did you get your wafers?  What
was the tolerance on the <110> specification?  Many vendors are unable to
maintain tight tolerances.

Andrew J. Nielson

-----Original Message-----
From: Connie Kathleen Smith [mailto:[email protected]]
Sent: Monday, January 07, 2002 8:41 AM
To: '[email protected]'
Subject: RE: [mems-talk] 110 Si etching with 20%KOH


From literature and others' suggestions I was led to believe that to get
vertical walls I would have to use 110 Si wafers.  The channel I am
etching is only about 200um wide and 500um deep.

Connie Smith
Rice University


On Mon, 7 Jan 2002, Knighton, Ed wrote:

> Hi Connie, If you switch to <100> Si Wafers Your problem will go away.
>
> Ed Knighton, Process Engineer
> Constellation Technology Corp.
>
> > -----Original Message-----
> > From:       Connie Kathleen Smith [SMTP:[email protected]]
> > Sent:       Friday, January 04, 2002 1:40 PM
> > To: [email protected]
> > Subject:    [mems-talk] 110 Si etching with 20%KOH
> >
> > I am trying to fabricate a flow channel with vertical side walls using a
> > <110> Si wafer.  When I etch all the way through the wafer (which is
> > desired) the side walls are slanted.  The wafers are coated with SiO2
and
> > Si3N4 as protective barriers during etching.  I expected to lose several
> > microns vertically during etching but the slanted walls were unexpected.
> >
> > Thank you,
> > Connie Smith
> > Rice University
> > Department of Chemical Engineering
> > 6100 Main MS 362
> > Houston, TX  77005
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