[labnetwork] Silane and Dichlorosilane Line Evacuation

[Clark O.D.]

We operate in a similar fashion at Southampton. Lines run to the facility, distributed to tools inside extracted wall manifold boxes, separated lines run to extracted tool point of use gas manifolds. All points where compression fittings are used are extracted and gas detectors placed in the extract ducting. All enclosures are locked to prevent unauthorised access. The manifold tool feeds act as extensions to the chambers and are therefore kept at vacuum when not processing (as standard). Lines are emptied for extended shutdowns and backfilled as required. All lines orbitally welded, nastier gases are shrouded with negative extract given to the shroud back at the cylinder panel.

We have a long DCS line, possibly 100m. No condensation problems yet, we use no more line pressure than is required for maximum MFC flow at the point of use and the natural temperature increase from gas rooms to cleanroom seems sufficient to prevent localised condensation. The last few metres of line and MFC are heated.

Apart from leak safety a significant part of risk minimisation seems to be that on no account should a user of the facility should have access to any valve or compressed fitting in the line. Competent staff only, any potentially live gas line modification requires a method statement/risk assessment and permit to work signed off before picking up tools.

Regards, Owain.

From: labnetwork-bounces at mtl.mit.edu <labnetwork-bounces at mtl.mit.edu> On Behalf Of Paul Spizzirri
Sent: 15 February 2019 01:49
To: Bill Kiether <wjkiethe at ncsu.edu>
Cc: labnetwork at mtl.mit.edu; Bruce Tolleson <betemc at rit.edu>
Subject: Re: [labnetwork] Silane and Dichlorosilane Line Evacuation

Hi Guys

We also use these gases here in Australia too and use the xmas shutdown period to completely pump them out and perform a leak decay test for integrity reporting - otherwise they are left live throughout the year.  Same configuration as mentioned above with DC, restricted flow control, gas montoring and DC monitoring etc to life safety systems with central shutdown. Note that the pump down for DCS is tricky as you are likely to get liquid condensing in the lines - depending on how long they are, you could be pumping for days to get them cleared.

Cheers

Paul

On Fri, 15 Feb 2019 at 12:43, Bill Kiether <wjkiethe at ncsu.edu<mailto:wjkiethe at ncsu.edu>> wrote:
We do not evacuate between uses, but do evacuate if the lab or system is going to be down (and tagged out)  for an extended time (months).

For example, we were shutting a lab for 6 months for construction reasons, all of the toxic and flammables were evacuated and backfilled with UHP nitrogen ( or Argon).  The backfilling is important as you don't want to leave silane lines at vacuum.  Also, once in grad school, we did the same thing for a tool on which the only user was studying for 2 months for his prelims. That process saved lives as a new post doc decided to "borrow" a quarter turn valve off of the system without discussing it.

Bill Kiether



On Thu, Feb 14, 2019 at 7:47 AM Bruce Tolleson <betemc at rit.edu<mailto:betemc at rit.edu>> wrote:
Dear users of Silane and Dichlorosilane,
When your systems that use silane and dichlorosilane are not in use do you evacuate the lines going to the tool? We are looking for the best practices for gas line safety in a student environment microelectronic clean room.
The gas lines are wall mount or overhead coaxial stainless steel all welded lines with excess flow sensors.
What are you doing with you silane and dichlorosilane lines?
Thank you,

Bruce E. Tolleson
Rochester Institute of Technology
82  Lomb Memorial Drive, Bldg 17-2627
Rochester, NY 14623-5604
(585) 478-3836
[http://www.rit.edu/~962www/logos/tiger_walking_rit_color.jpg]

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Dr Paul Spizzirri
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Melbourne Centre for Nanofabrication
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Australian National Fabrication Facility (Victorian Node)

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