Depending on the aspect ratio of your trenches, you can ion implant at an
angle.
This was done a few years back at Stanford to form sidewall piezoresistors
for accelerometers.
    --Kirt Williams

----- Original Message -----
From: 
To: 
Sent: Thursday, May 04, 2006 4:23 PM
Subject: [mems-talk] forming boron and arsenic doped sidewalls in a
siliconwafer


>I am trying to form boron and arsenic doped sidewalls in trenches in a
>silicon wafer.  I thought of doing reactive ion or electrochemical etching
>of the trench bottom after isotropic doping, but I'm worried that the
>reaction will be hard to time correctly because the silicon underneath
>would etch much faster than the doped layer.  Any thoughts you have on the
>most efficient process to form doped sidewalls would be greatly
>appreciated.
>