[labnetwork] HPM gas survey

[Dennis Schweiger]

Michael,

here at UofMichigan/LNF we're doing the following;

1) We use coaxial lines for all of our Toxic (NF3, HBr, NH3, BCl3, Cl2,
SiH4, AsH3, PH3, Si2H2Cl2, and mixes of SiH4 and PH3 as dopant) gases.  In
this facility we did not use preformed directional changes for the coaxial
material.  All of the directional changes were accomplished with a 10D
bender.  We do not include the flammable gases (H2, CH4, C2H2, and C2H4) as
toxic gases so they are in single wall material.  We are not using
Hastelloy on any of our gas systems.  All of our gas wetted delivery tubing
is 316L EP finished tubing, typically a Valex 401 series material.

2) All breakable connections in either the Toxic and Flammable gas systems
are in exhausted enclosures.  We're also sampling for those gases in those
enclosures.  In addition, all of the annular spaces in the coax lines are
purged back to the previous "gas cabinet/box".

3) Our flammable gases are delivered from a bunker, where the cylinders are
free standing in the room.  The room is exhausted, and we're actively
sampling for the flammable gases in the bunker.

4) Our LP gases are delivered from a general location, and we have it
installed similar to what your contractor set up.  We're running the supply
header (3/8" tubing) at about 40PSI, and then stepping the delivery
pressure down (20PSI) at the branch (1/4" tubing) to each tool.  We also
have isolation valves at each branch off of the header.  Currently we
haven't had any issues with "starving" the process tools for gas, or in
condensing the gases out within the delivery system.

Nowhere in our facility do we heat the cylinder to increase the vapor
pressure.  We do have sub atmospheric regulators on some of the very low
pressure gases (BCl3, Cl2, HBr).

Take care, and good luck,

Dennis Schweiger
University of Michigan/LNF

734.647.2055 Ofc

On Tue, Dec 6, 2016 at 10:17 AM, Michael Khbeis <khbeis at uw.edu> wrote:

> Dear Colleagues,
>
> Once again, I am pitted against my capital projects group. This time
> regarding HPM gas infrastructure. Thanks to your prior input, we were able
> to obtain a proper toxic gas monitoring system. However, now I am in a code
> interpretation debate with their process piping consultants on the use of
> VMBs for multi-tool feeds and coaxial lines. They don't want either in our
> project. They specified hastelloy for Chlorine and BCl3 but single walled
> 316ss (after much debate that 304 was not sufficient) for all our other
> gasses. In ALL my prior sites we always used coaxial lines as a secondary
> containment for HPMs, but currently this project has no coax specified.
>
> I am also in debate on whether or not 100% hydrogen (large 330cf
> cylinders) can be in the Cleanroom without a cabinet vs a bunker in a
> cabinet. Their interpretation is that an H-5 facility can store 9000cf;
> however, I believe they are ignoring the vented enclosure requirements.
>
> We will have the following HPM gasses:
> 100% Silane
> 100% Hydrogen
> Ammonia
> Chlorine
> Boron Trichloride
> Phosphine
> Diborane
>
> Can you please weigh in on your sites use of:
>
> 1) coaxial lines, which gasses and if any HPMs are excluded or use single
> hastelloy
>
> 2) use of valve manifold boxes / vented enclosures for distributing HPMs
> to multiple tools (or anywhere else there's a mechanical connection)
>
> 3) location and enclosure or not for 100% hydrogen
>
> And on a non-safety related note, we asked for panels with multi-stick
> feeds to each tool; however, the process piping designer just teed all of
> our lines from a single point and put a regulator at each tool instead to
> "save money". I am very concerned about LP gasses (e.g C4F8) being starved
> when multiple tools are running. We distinctly had issues with past lab
> with shared C4F8 bottles. Their recommendation is to ONLY heat the cylinder
> to increase vapor pressure, but given my limited knowledge, I believe with
> high flow rate and lacking heating of the panel and lines we will have gas
> condensation issues. To date, my input is still being dismissed so please
> state:
>
> 4) how you handle LP gas distribution to multiple tools
>
> I thank you so much for taking the time out of your busy schedules to
> provide this input. This community/forum has been such a blessing.
>
> Most gratefully,
>
> Dr. Michael Khbeis
> Washington Nanofab Facility
> University of Washington
> Fluke Hall, Box 352143
> (O) 206.543.5101
> (C) 443.254.5192
> khbeis at uw.edu
>
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>
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