[labnetwork] Cryopump configuration on a CVD tool

[Dennis Schweiger]

Errol,

we have a gas phase MBE tool here at UofM that is using pure Arsine and
Phosphine for process gases.  Typically during process we'll use a turbo
pump, with the cryo only used in stand-by state.  We had the same concerns
you do in regard to the cryopump warming up, and off-gassing the
contaminated material.  What we did was install a check valve (pressure
relief) in the vent line.  The front side of the check is exposed to the
cryopump internals, and the back side of the check valve is on our HPM
venturi header that runs throughout the fab area.  The back side is always
under vacuum (it's on a UPS system so even a power outage won't effect us),
and so far has worked flawlessly (+ 4 years).  I've attached a picture of
the mechanical connections.  Let me know if you'd like to discuss this
further.
Dennis Schweiger
University of Michigan/LNF

734.647.2055 Ofc


On Thu, Dec 6, 2012 at 11:31 AM, Errol V. Porter <evporte at uark.edu> wrote:

>  Greetings members,****
>
> ** **
>
> I wanted to see if there are any members currently using a cryopump on a
> CVD tool utilizing any of the following gases; germane, hydrogen, methane,
> silane, diborane or phosphine. Note the main pump being used during
> processing is a turbopump with the cryopump being used to keep the tool
> under vacuum while the tool is not being operated. If there are any users
> using  a similar configuration, how was the pump installed specifically to
> deal with the effluent that is released during a normal regeneration cycle.
> ****
>
> ** **
>
> Regards,****
>
> ** **
>
> Errol Porter****
>
> University of Arkansas / HiDEC****
>
> 700 W. Research Center Blvd****
>
> Fayetteville, AR 72701****
>
> Tel. 479 575-2519****
>
> Fax 479 575-2719****
>
> email: evporte at uark.edu****
>
> http://www.hidec.uark.edu****
>
> ** **
>
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