[labnetwork] LPCVD pumps

[Paolini, Steven]

Savitha,
    I would be less concerned with the make and model of the pump as I would be about how the effluent is being handled. LPCVD nitride is a notoriously dirty process and produces large amounts of condensable ammonium chloride. The best way, in my experience is to promote the condensation in a serviceable area before it gets to the pump. I would recommend a water cooled trap in the pumping line as close to the furnace as possible. Maintenance intervals are directly proportional to processing hours. A simple flow vs pressure test with the throttle valve wide open is a great indicator of when maintenance of the trap is needed. If you were to have a spare trap, it could be swapped out with a clean one during maintenance to reduce downtime. Soaking the trap in warm water will dissolve the ammonium chloride but be sure to do this in a fume hood since it gives off ammonia gas when breaking down.

Steve Paolini
Principal Equipment Engineer
Harvard University Center for Nanoscale Systems

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Savitha P
Sent: Friday, May 10, 2013 8:24 AM
To: labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] LPCVD pumps

Hello!

We are using BUSCH COBRA BOB BA 100 model pumps with our LPCVD furnaces.
We have a lot of maintenance issues with the same, especially with the silicon nitride and low temperature oxide processes. Is there anyone else using these pumps for their LPCVD processes. If yes, could you please tell us how you are maintaining it. Also, has anyone ever been replaced these with similar capacity pumps from other companies?

Thanks and regards,

Savitha

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Dr.Savitha P
Facility Technology Manager
National Nanofabrication Centre
Centre for Nano Science and Engineering (CeNSE) Indian Institute of Science Bangalore - 560012
Ph: +91 80 2293 3254
www.nano.iisc.ernet.in

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