[labnetwork] BCL3 - Gas Line Heaters and Protocols

[Craig Cheney]

Dean,

   We have done numerous BCL3 systems for different customers, mostly
semiconductor, but a few others.  Here are the major points we hit with
customers that cover code compliance, safety, and the proper design for a
BCl3 system.  Some of these have been mentioned before but will run through
them quick for you.

	1. Keeping the gas source as close to the point of use is very
beneficial, reduces line length etc. and all the problems that come with
that, given the nature of BCL3.

	2. The gas cabinet needs to be ventilated properly, this does two
things, first, in the event of a leak its exhausted.  Second, if  your
building is 72F or cooler, this will help chill the cylinder.

	3. A typical BCL3 system has the cylinder chilled with a cooling
blanket (you can get them from accurate gas, http://accurategas.com/).   And
the delivery panel as well as the gas line should 	be heat traced also.
68 - 70F on the cylinder, and 75 F or higher on the gas line.
	
	4. The process delivery line is supposed to be coaxial, closed/open
design so the gas is forced to your gas detection point, the gas delivery
system should be Orbitally welded throughout.

	5. Use high quality electro-polished seamless stainless steel for
the wetted portion of the gas line.  The gas panel needs to be capable of
performing cycle purges on the panel, gas line, and 	pigtail.

	6. All regulators, valves, etc. should be rated for use with extreme
corrosives.

	7. If you are delivering this gas to more than one tool and you the
required coaxial gas lines, you will need to use a Valve Manifold Box to
deliver gas to more than one point.

	8. The vapor pressure of BCL3 is 4 psi, if you try to deliver a
higher pressure than 4 psi, you will not get it, and if you try heating the
cylinder to raise the pressure, you will add numerous 	problems to your
system, the gas will turn back into a liquid on the first surface it hits
that is in the 70F range, trashing MFC's, reducing gas flow, and pulling
liquid into your process chamber.

	9. Your gas delivery panel should incorporate a nitrogen bleed on
the pigtail during cylinder changes to prevent moisture from entering any of
the wetted components, failure to do this will 	result in failed components
such as regulators, MFC's, etc.

	10. Minimizing bends and changes in direction is always best, but if
the gas line is properly heat traced and the cylinder is chilled, you should
not have any problems.  We have installed 	systems for BCL3 where the
line length is over 100' with no problems. 

	11. One key point, if the gas delivery line has gas in it, it should
be heated 24X7, if the usage of this gas is low (once a week or less) than
you should consider doing a cycle purge on the gas 	line and leaving it
under vacuum when not in use.

Hope that helps, and feel free to give me a call if you have any other
questions.


Craig Cheney
Infinity High Purity Systems
 
Desk:  (608)834-4200
Fax:     (608)834-4299
Cell:    (608)438-8714

This e-mail transmission and any attachments to it are intended solely for
the use of the individual or entity to whom it is addressed and may contain
confidential and privileged information. If you are not the intended
recipient, your use, forwarding, printing, storing, disseminating,
distribution, or copying of this communication is prohibited. If you
received this communication in error, please notify the sender immediately
by replying to this message and delete it from your computer.

-----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 2:10 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



_______________________________________________
labnetwork mailing list
labnetwork at mtl.mit.edu
https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork