[labnetwork] Using CDA, rather than N2, as pump purge in Bosch-like processes?

[N P VAMSI KRISHNA]

Dear John,
Even we face same problem. Our Dry etch and PECVD tools drink more N2 than
any other pumps in the clean room.
We found our DRIE tool has an inbuilt software option which restricts the
pump N2 flow during stand by mode, which is really helping us to save a lot
of N2. For the same option we had a long discussion with our RIE and PECVD
manufacturer; recently we got to know that they also developed a software
for the same, which we still need to purchase and install.
For your tools you may need to talk to the manufactures if they have any
option as such.
So as Fouad mentioned that would be great if the all the manufactures work
on this.


Thanks & Regards,

*Vamsi Krishna*
Sr.Facility Technologist - Dry Etch & Process Integration
National Nano Fabrication Center
Center for Nano Science and Engineering (CeNSE)
Indian Institute of Science(IISc)
Bangalore 560012, INDIA
Mobile:  +91 9880988239



On Fri, Apr 12, 2013 at 1:16 AM, Lavallee, Guy P. <gpl107 at psu.edu> wrote:

> John,
>    I believe the issue with the Fluorine chemistries is the formation of
> HF if you ever have water in the CDA which then gets into the pumps.  The
> potential of creating this would obviously be dependent on how much
> unreacted fluorine would reach the pump as well as how reactive the
> effluents would be with water leading to the formation of HF.
>
> The other issue you have to think about besides water (which the pumps
> won't like either regardless of HF formation) would be the potential of oil
> being in the CDA.  This will be highly dependent on the type of CDA system
> you have at your facility.
>
> We have thought about changing from N2 to CDA as well but have been very
> hesitate due to the many unknowns and not wanting to risk it.  It would be
> interesting to hear others inputs.
>
> Thanks,
> Guy
>
> Penn State University's Nanofabrication Laboratory
> Lead Etch Engineer
> Materials Research Institute
> N-105 Millennium Science Complex (MSC Bldg)
> University Park, PA 16802
> Email: gpl107 at psu.edu
> Phone: 814-865-9339
> Cell: 814-777-0719
>
>
> -----Original Message-----
> From: labnetwork-bounces at mtl.mit.edu [mailto:
> labnetwork-bounces at mtl.mit.edu] On Behalf Of John Shott
> Sent: Thursday, April 11, 2013 11:48 AM
> To: Labnetwork
> Subject: [labnetwork] Using CDA, rather than N2, as pump purge in
> Bosch-like processes?
>
> Labnetwork Community:
>
> Like many of you, I suspect, nitrogen is the single largest non-salary
> expense associated with running our facility.
>
> Much of our nitrogen is used for pump purges in dry pumps.  Our average
> dry pump seems to use about 1 CFM (sorry, 25-30 SLM ...) which, at our
> pricing is about $4k per year.  For virtually all deposition processes
> using reactive gases and etch processes using corrosive gases, using
> nitrogen as a pump purge seems to be a firm requirement.  It is not as
> obvious, to me at least, that nitrogen is required in something like a
> SF6/fluorocarbon-based etch process like the switched Bosch processes that
> many of us run.  While I know that CDA isn't "free", in our case, the LN2
> bill definitely comes out of our pocket whereas as CDA is a University
> supplied and supported building utility.
>
> What experience, recommendations, or cautions can you offer related to
> switching our Bosch process tools from nitrogen to CDA pump purges?  If it
> matters, the dew point of our CDA is believed to be less than -40 C, but is
> not monitored continuously (and maybe not even monitored periodically ...).
>
> Thanks for your consideration,
>
> John
>
>
>
>
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-- 
Thanks & Regards,

*Vamsi Krishna*
Sr.Facility Technologist - Process Integration
National Nano Fabrication Center
Center for Nano Science and Engineering (CeNSE)
Indian Institute of Science(IISc)
Bangalore 560012, INDIA
Mobile:  +91 9880988239

*A bird sitting on the branch of a tree is not afraid of the branch shaking
or breaking, because it trusts not the branches but its OWN WINGS.

*
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