[labnetwork] BCL3 - Gas Line Heaters and Protocols

[Paolini, Steven]

I agree with Bob Hamilton. I have gone through all the problems associated with low vapor pressure liquid source gases and the only method that has worked flawlessly for me is to lower the delivery pressure to keep the material in vapor form. This is a common problem with gases such as Boron Trichloride and Dichlorosilane.  In the past, we have heated lines, cylinders, and any other object in the gas circuitry in an effort to keep the gas from condensing into liquid but the material always finds something cooler (like an MFC) and it results in condensation problems. Good ole' high school physics tells us if you lower the pressure surrounding a liquid, you lower the boiling point proportionally.  I now purchase sub-atmospheric regulators and run these gases at the lowest possible pressure that will still deliver full flow and then add about 10% more. Typical pressures for Dichlorosilane are around 1 in Hg to 1 PSI and for Boron Trichloride about 3 PSI due to the higher flows used. Luckily, these gases are almost always used in a vacuum system.
Steve Paolini
Equipment Dood
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 Dean Sutter
Sent: Monday, August 26, 2013 3:10 PM
To: <labnetwork at mtl.mit.edu>
Cc: Rose, Robert W; Michael Sullivan; Vinh Nguyen
Subject: [labnetwork] BCL3 - Gas Line Heaters and Protocols

Hello,

AT GT Nano we have a hard plumbed BCL3 line coming from a central gas room, running several hundred feet into the sub fab eventually connecting to the tools.

We have been internally debating the necessary protocols and physical installations necessary  to ensure a safe and properly functioning delivery mechanism.

These discussions have included the elimination of the central approach, replaced with a local gas cabinet and shorter runs since maintaining and being able to monitor line heaters on a several hundred foot of line, buried in plumbing up in the ceiling  is our primary concern.

So, we are seeking a benchmark from existing facilities that use BCL3.

Anyone care to volunteer to explain their installation and operating/safety protocols?

Thanks

--
Dean A. Sutter
Associate Director,
Research Operations and Industry Engagements

dean.sutter at ien.gatech.edu
404 894 3847 - Office
404 558 1844 - Cell
www.ien.gatech.edu



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