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<p class="MsoNormal">Savitha P.,<br>
<br>
It is difficult to predict the purity of the N2 in your
atmospheric process
tube with<st1:personname w:st="on">out</st1:personname>
knowing more ab<st1:personname w:st="on">out</st1:personname>
the geometry of the tube. Is it a horizontal or
vertical furnace? <br>
<br>
Backstreaming will play a role in the furnace atmosphere. One
presumes the tube
has an exit opening(s) which ports into a scavenger.
Back-diffusion/partial
pressure laws will invariably increase O2, CO2 and water vapor
partial pressures
in the furnace environment.<br>
<br>
At <st1:place w:st="on"><st1:city w:st="on">Berkeley</st1:city></st1:place>,
we
reduced O2 contamination by modifying our OEM's furnace tube
exit port design. In
addition to reducing overall exit orifice area, we increased
the number of exit
ports and positioned them symmetrically around the
circumference for better
cross-wafer uniformity.<br>
<br>
Our go/no go standard for N2 atmospheres in our atmospheric
furnaces was >5 nm oxide/1000 C/12 hours.<br>
<br>
Also, the furnace pre-clean step is important. I'll defer to
others on the
labnetwork who are more qualified to discuss this.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Bob Hamilton<br>
<br>
</p>
</o:smarttagtype>
<pre class="moz-signature" cols="60">Bob Hamilton
Marvel NanoLab
University of CA at Berkeley
Rm 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
<a class="moz-txt-link-abbreviated" href="mailto:bob@eecs.berkeley.edu">bob@eecs.berkeley.edu</a>
(e-mail preferred)
510-809-8600
510-325-7557 (mobile - emergencies)
</pre>
On 2/11/2013 3:22 AM, Savitha P wrote:<br>
</div>
<blockquote
cite="mid:5d0af029dc1917735edf3912835de621.squirrel@www.ece.iisc.ernet.in"
type="cite">
<pre wrap="">Dear Colleagues:
We had done a N2 anneal in our atmospheric furnace for 10hrs at 1100 deg
C, substrate was silicon <100>, P-type. The oxide thickness obtained was
~16nm (variation of 15.2 - 17.6nm). For one hr anneal, the thickness
obtained was ~5nm. It would be really helpful if we could know the silicon
dioxide thickness expected for N2 annealing experiments. The percentage of
O2 impurity in our N2 is supposed to be <1.000 ppb according to our
purifier specs.
Regards,
Savitha
</pre>
</blockquote>
<br>
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