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Colleagues,<br>
<br>
Following up on Kamal's 1/9 post, in the case of excimer laser gas
the expiration date is critical. This is confirmed by higher firing
voltages, (bad) required with old excimer mix. <br>
<br>
As in the case of eximcer gas, acid gases react with steel cylinder
walls. I would argue smaller cylinders, with a larger
surface-to-volume ratio exacerbate this situation. This, along with
the often higher price for smaller cylinders is another argument
against "smaller is better (safer)" when discussing reactive gas
cylinders. <br>
<br>
In the case of diborane, its stability vs. time is influenced by its
percentage and the diluent it is mixed with. From memory diborane's
equilibrium is better in H2 than in SiH4. When, after years of use,
plumbing for a diborane delivery line is reviewed, one sees the
higher order borane polymers coating surfaces. This is an argument
to routine evacuate the gas-stick (valves, mfc, P xducer, etc.) post
deposition.<br>
<br>
Bob Hamilton <br>
<br>
<pre class="moz-signature" cols="72">--
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Equipment Eng. Mgr.
Room 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>
Phone: 510-809-8600
Mobile: 510-325-7557 (Emergencies only poor cell phone service in lab)e-mail preferred
</pre>
<br>
<br>
<div class="moz-cite-prefix">On 1/9/2015 11:47 PM, Kamal Yadav
wrote:<br>
</div>
<blockquote
cite="mid:CAOfoCyhnMN050902rB7XoYKGAa5=Tk+wBPekSveNshFyX226zg@mail.gmail.com"
type="cite">
<meta http-equiv="Context-Type" content="text/html; charset=UTF-8">
<p dir="ltr">Hi, </p>
<p dir="ltr">I was also trying to find the affects of<br>
expiration of NH3 and Diborane in Hydrogen and silane. </p>
<p dir="ltr">In pure gases it does not matter and you can use
after expiration we have used 6 years post expiration for NH3.
When we changed new cylinder process did not improve... So it
does not matter. </p>
<p dir="ltr">In Diborane mixtures or similar I have been told that
the ratio is not maintained post expiration.. </p>
<p dir="ltr">Thanks, <br>
Kamal <br>
IITBNF <br>
</p>
<div class="gmail_quote">On Jan 10, 2015 3:45 AM, "Himmer, Phil"
<<a moz-do-not-send="true" href="mailto:PhilH@ee.montana.edu">PhilH@ee.montana.edu</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote">
<div>
<div>Hello</div>
<div><br>
</div>
<div><br>
</div>
<div>Thanks to all for your input about the expired gas. The
general consensus is that expiration dates are not
relevant for process stability so I’ll continue using what
I have. </div>
<div><br>
</div>
<div>regards</div>
<div>phil</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
<div>
<div>
<div>
<div>Dr. Phillip Himmer</div>
<div>Manager Montana Microfabrication Facility</div>
<div>Montana State University</div>
<div>Bozeman Mt 59717</div>
<div><br>
</div>
<div>Office Ph: <a moz-do-not-send="true"
href="tel:406-994-7178" value="+14069947178"
target="_blank">406-994-7178</a></div>
<div>email:<span> </span><a moz-do-not-send="true"
href="mailto:philh@ece.montana.edu"
target="_blank">philh@ece.montana.edu</a></div>
</div>
</div>
<br>
<br>
</div>
<br>
<div>
<div>On Jan 7, 2015, at 2:44 PM, Janney, Peter J. <<a
moz-do-not-send="true"
href="mailto:janney.9@osu.edu" target="_blank">janney.9@osu.edu</a>>
wrote:</div>
<br>
<blockquote type="cite">
<div>
<div>It's my understanding that the gas doesn't
really expire, it's only the certification on the
tank. </div>
<div><br>
</div>
<div><br>
</div>
--
<div>Pete Janney</div>
<br>
<br>
<div>-------- Original message --------</div>
<div>From: "Himmer, Phil" </div>
<div>Date:01/07/2015 2:14 PM (GMT-05:00) </div>
<div>To: <a moz-do-not-send="true"
href="mailto:labnetwork@mtl.mit.edu"
target="_blank">labnetwork@mtl.mit.edu</a> </div>
<div>Subject: [labnetwork] expired process gas </div>
<div><br>
</div>
<div>Hello,
<div><br>
</div>
<div>Does anyone have any practical experience
using Chlorine and Hydrogen Bromide gas past
it’s expiration date? We use the gas for ICP
etching of chrome and aluminum.</div>
<div>We have small cylinders(air liquide 7-size)
of each that still have gas in them but are now
years past the expiration date. I have pulled
them from the gas cabinet with the plan to
replace them but am having difficulty finding a
vendor who offers these gasses in these small
volumes. We are trying to not use lecture
bottles due to disposal considerations.</div>
<div><br>
</div>
<div>looking forward to suggestions</div>
<div>phil</div>
<div><br>
</div>
<div><br>
</div>
<div>
<div>
<div>
<div>Dr. Phillip Himmer</div>
<div>Manager Montana Microfabrication
Facility</div>
<div>Montana State University</div>
<div>Bozeman Mt 59717</div>
<div><br>
</div>
<div>Office Ph: <a moz-do-not-send="true"
href="tel:406-994-7178"
value="+14069947178" target="_blank">406-994-7178</a></div>
<div>email:<span> </span><a
moz-do-not-send="true"
href="mailto:philh@ece.montana.edu"
target="_blank">philh@ece.montana.edu</a></div>
</div>
</div>
<br>
<br>
</div>
<br>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</div>
<br>
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</blockquote>
</div>
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</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Equipment Eng. Mgr.
Room 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>
Phone: 510-809-8600
Mobile: 510-325-7557 (Emergencies only poor cell phone service in lab)e-mail preferred
</pre>
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