Hugo,

the reason for using thermal oxide for bonded SOI wafers is the "better"
structure of the oxide and so different electrical, physical and chemical
properties than a deposited oxide.
In few words: the thermal oxide is most homogenous and without organics (in
best case). Organics can cause voids in the bond interface. TEOS or other
deposited oxides are "porous".


Regards,
Markus.

SUSS MicroTec
Business Field MEMS
Markus Gabriel
Schleissheimer Str. 90
85748 Garching
Germany
Fon     +49 89 32007 - 313
Fax     +49 89 32007 - 390
email   m.gabriel@suss.de
http://www.suss.com/mems


Date: Thu, 02 Jan 2003 14:07:14 -0800
From: "Hugo Jazo" 
To: mems-talk@memsnet.org
Subject: [mems-talk] SOI fabrication
Message-ID: <4.2.0.58.20030102140120.00aa9540@mailsd1.spawar.navy.mil>
Content-Type: text/plain; charset="us-ascii"; format=flowed
MIME-Version: 1.0
Precedence: list
Reply-To: General MEMS discussion 
Message: 2

In bonded SOI wafers, it seems that everyone uses thermal oxide as the in
between layer.  Is there any reason why deposited oxides (PETEOS) can not
be used?

Ultimately, we'd like to get low stress SOI wafers, if there is such a
thing.

Thanks,
Hugo Jazo