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Hello Aaron,<br>
<br>
I my previous research, I did a lot of oxide MBE growth and we used
a H2 plasma to clean the substrate surface (GaAs, GaN,...). The
cryopump on the MBE system worked well for these gases. The regen
was not a big concern for us, H2 comes off of the cold head at 20K
while O2 comes off at 90K. We regened the cryo with a dry backing
pump (not the standard flowing N2 method), so the cryopump was
always under vacuum and thus we never had a critical build up of
H2. But I think you will be fine even if you use the flowing N2
regen method for the cryo (like most sputter tools), the dilution of
the H2 will occur pretty quickly and the pump body will have a LOT
of N2 inside.<br>
<br>
Best Regards,<br>
Brent<br>
<div class="moz-signature"><br>
-- <br>
Brent P. Gila, PhD.<br>
Director, Nanoscale Research Facility<br>
1041 Center Drive<br>
University of Florida<br>
Gainesville, Florida 32611<br>
<a class="moz-txt-link-freetext" href="Tel:352-273-2245">Tel:352-273-2245</a><br>
Fax:352-846-2877<br>
<a class="moz-txt-link-abbreviated" href="mailto:email:bgila@ufl.edu">email:bgila@ufl.edu</a><br>
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<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 3/15/2019 12:12 PM, Aaron Hryciw
wrote:<br>
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<blockquote type="cite"
cite="mid:CAPt+QB856DVfjrg4FzEy_r+NYZeWL920ru3kS-xUDc5oY0KDXw@mail.gmail.com">
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<div dir="ltr">Dear colleagues,
<div><br>
</div>
<div>Our open-access facility has a cryo-pumped, manual
sputtering system plumbed with argon, oxygen, and nitrogen,
which is often used for reactive sputtering (mostly oxides).
One of our users has requested the addition of forming gas (5%
H₂ + balance Ar) to enable sputtering of <i>a</i>-Si:H / SiO₂
multilayers, as described in <a
href="https://urldefense.proofpoint.com/v2/url?u=https-3A__www.osapublishing.org_ao_abstract.cfm-3Furi-3Dao-2D43-2D17-2D3548&d=DwMFaQ&c=sJ6xIWYx-zLMB3EPkvcnVg&r=gl_2fLZA_-_JfH_dOmx7ug&m=RQnKj8jWOJDys3S59ErGq_i0RC9WpIgTRWwy5pLQGlw&s=Y612MfcUhUpXHR-N8n8jvwfaICCA0O05B7NKvZGZvws&e="
moz-do-not-send="true">this paper</a>. A concern was
raised, however, about the possibility of explosions in the
cryo during regeneration, as the frozen mixture of argon,
oxygen, ozone, and hydrogen is released as the pump is warmed
up.</div>
<div><br>
</div>
<div>Does anyone have experience with using forming gas in a
cryo-pumped system, and/or know of any measures that could be
taken to ensure these sputtering processes could be performed
safely? Doing this on a system equipped with a turbo pump
would be better, but we are leery of putting a turbo on a
manual system, where users fairly routinely crash the cryo.
As always, any advice would be greatly appreciated.</div>
<div><br>
</div>
<div>Many thanks.</div>
<div><br>
</div>
<div>Cheers,</div>
<div><br>
</div>
<div> – Aaron</div>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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