Dopants will have neglible impact on the SiO2.

The dopants will be oxidized into unconductive oxides. Even with a
heavily doped wafer the atomic % of dopants is low. It will be very
insulating.

The differences in different types of silicon oxides made in different
types of situations is measured by break down voltages and not
conductivity. They are all insulators. The differences is how much
electrical strain they can bear before they break down.

If you are really asking about break down voltages, that is a whole
different topic than conductivity. Even so, your wafer should have oxide
with great electrical characteristics, in terms of having high break
down.

For interfaces of the silicon dioxide, you should have a little O2 in
the gas flow while the wafers are pushed in and ramped so they get 30 to
100 angstroms oxide before you start the wet oxidation at a higher
temperature. For dry oxidation during Drive processes have a little O2
at the push in and temperature ramp also. Don't ever start an oxidation
on bare silicon at a high temperature. The cross-sections will look
wretched.

Ed

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Wenlin Jin
Sent: Wednesday, January 09, 2008 8:06 AM
To: General MEMS discussion
Subject: RE: [mems-talk] conductivity of SiO2 layer grown on top of
heavilydoped silicon

Hi, All,

I didn't put the condition right in the previous email. The starting
wafer is heavily doped. Here is the question again:

I'm considering grow a silicon oxide layer on a heavily doped silicon
wafer through wet or dry oxidation process. The question is: will the
oxide layer obtained in such a way be conductive? Advices are
appreciated.