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<div class="moz-cite-prefix">Siva Penmetsa,<br>
<br>
Can you better describe your process, i.e. is it atmospheric or
subatmospheric? Have you considered BCl3 in a diluent such as Ar
in lieu of diborane?<br>
<br>
I am not qualified to write about your resistivity issues;
however, I have fair experience using diborane in gas jungles and
in furnace applications. Diborane is usually diluted in hydrogen
(10%, bal. H2 is common) when used as a gas source in
semiconductor applications. Diborane is unstable and forms higher
order boranes which deposit on the surfaces of gas jungles. This
can be problematic with valves and mass flow controller. I have
witnessed the issues with regulators and valves, and read
discussions about drift in mfc's because of polymerization of
diborane within the capillary of the heated gas bypass sensor.
Because of this we routinely programmed our recipes to pump
diborane from the gas jungle upon completing a process. There's no
cost or downside with this precaution. .<br>
<br>
Because diboranes decompose at high temperatures it can be
difficult to maintain uniform dopant distribution within the wafer
load. This is even more problematic when diborane is used via an
injector tube because of the higher pressure within an injector,
the greater surface to volume ratio and that injectors invariably
pass through the guard zones of a furnace, which operate at higher
temperature than the flat zone.<br>
<br>
We have obviated diborane for furnace processing and we currently
use a 1% BCl3 in Ar for both atmospheric doping and for lpcvd
Si/Ge films with good success.<br>
<br>
Bob Hamilton <br>
<br>
<pre class="moz-signature" cols="60">Robert M. 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 8/9/2012 4:44 AM, Siva Penmetsa wrote:<br>
</div>
<blockquote
cite="mid:CAHmH2YTaKeqT05Jp7HYfG4JJ-K=xjxDGeT8irRE0115dcNqCyg@mail.gmail.com"
type="cite">
<div>Hi All,</div>
<div> </div>
<div>We are trying to optimise Diborane furnace in a new CVD
equipment.</div>
<div> </div>
<div>We have performed few trials(all the souces are gases) at </div>
<div> </div>
<div>Temperature 1000 C </div>
<div>Diborane Flow rate in the range 40 sccm to 100 sccm</div>
<div>Oxygen flow rate 2 SLPM</div>
<div>Nitrogen flow rate is 3 SLPM</div>
<div>Time 30 minutes</div>
<div> </div>
<div>Instead of decrese in resistance we observed that the
resistance incresed to around 500 ohm/sq from around 50 ohm/sq</div>
<div> </div>
<div>We apprecite your experience and inputs on how we can resduce
the resisitivity with better Diborane diffussion.<br clear="all">
<br>
-- <br>
</div>
<div>Thanks & Regards,</div>
<div><strong>Siva Prasad Raju Penmetsa</strong></div>
<div><em>Senior Facility Technologist</em></div>
<div>National Nano Fabrication Center</div>
<div><em>Indian Institute of Science(IISc)</em></div>
<div>Bangalore, India 560 054</div>
<div> </div>
<br>
<br>
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</blockquote>
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