[labnetwork] Thank you / Re: question to cleanroom colleagues: distributed vs. manifolded gases...

Fri Sep 21 10:34:38 EDT 2012

Dear Colleagues,

Thank you for taking time to discuss this.  It is very helpful to us.

best to you all!

--Ian

Begin forwarded message:

From: John Shott <shott at stanford.edu>
Subject: Re: [labnetwork] question to cleanroom colleagues: distributed vs. manifolded gases...
Date: September 21, 2012 8:00:54 AM MDT
To: labnetwork at mtl.mit.edu, Ian Harvey <IRHarvey at eng.utah.edu>

Ian:

Like some of the others, we tend to have tapped lines for inerts/freons and VMBs for some (but not all) of our hazardous/corrosive/toxic lines.

In addition to the comments of others, let me add a couple of additional thoughts relative to use of VMPs/VMBs for hazardous/corrosive gases.

There seems to be a broader range of configuration options in VMBs than there are in cabinets themselves.  There are the "Cadillac" fully automated systems ... nice, but pricey.  We have fully manual VMBs.  Even there, however, there are options.  We have nitrogen purge capability for each line in our 4- or 8-stick boxes, but no venturi.  Our assumption is that all tools connect downstream of a VMB will be able to pump out the line, but it's nice to be able to backfill with N2/He for a manual cycle-purge.  My guess is that others will have different configurations and reasons for using them.

In addition to the cost of the VMB/VMP .... particularly for hazardous gases ... you should think about whether this will require additional gas detectors, whether you'll also need to be adding extra panels/cylinders for purge of your VMBs etc.    While I like VMBs for things like BCl3 and chlorine, these additional items increase the cost.  Of course, an all welded BCl3 or Cl2 system is problematic if you ever want/need to make changes. I've yet to find a welder willing to certify a weld on a system that has been used for these gases.  Most jurisdictions will require all non-welded connections to most toxic/corrosive gases be in an exhausted (and in some cases monitored) enclosure.  The incremental cost of VMPs/VMBs also depends one the distance between the gas cabinet, a potential VMB, and the tools.  In our case where the distance between the gas bunker is large (we typically have 400-500 feet of line between gas cabinet and tool/VMB) and the distance between VMB and tool is more like 30-50 feet, the VMB isn't such a large incremental expense.

Good luck,

John

Begin forwarded message:

From: "Daniel C. Christensen" <dcchrist at wisc.edu>
Subject: Re: [labnetwork] question to cleanroom colleagues: distributed vs. manifolded gases...
Date: September 20, 2012 2:46:15 PM MDT
To: Ian Harvey <IRHarvey at eng.utah.edu>, labnetwork at mtl.mit.edu
Reply-To: dan at engr.wisc.edu

Another PRO for VMP's - when I need to replace an MFC in a tool, I am able to go to the VMP and evacuate AND PURGE the gas line for that particular tool while not disrupting the gas supply to the other tools. Replacing MFC's seems to occur more often in our case than adding and subtracting tools.

At Univ of Wisconsin we have VMP's and VMB's (hazardous gases). I would set the threshold for non-haz. gases to be >2 tools then use a VMP. For haz gases, I would use the VMB even for 2 tools. Certainly buy extra sticks in the VMP/B for future use. I am happy we spent the money to have them.

Dan C
--
Daniel C Christensen
Wisconsin Center for Applied Microelectronics
University of Wisconsin-Madison
dan at engr.wisc.edu 
608-262-6877
Begin forwarded message:

From: Iulian Codreanu <codreanu at seas.upenn.edu>
Subject: Re: [labnetwork] question to cleanroom colleagues: distributed vs. manifolded gases...
Date: September 20, 2012 1:49:52 PM MDT
To: Ian Harvey <IRHarvey at eng.utah.edu>
Cc: labnetwork at mtl.mit.edu

Ian,

I use VMBs for hazardous gases (the threshold is 2).

I use the shared supply line for inerts.

Iulian
---
iulian Codreanu, Ph.D.
Director, Penn NanoFab
200 South 33rd Street
Room 376 GRW Bldg
Philadelphia, PA 19104-6314
P: 215-898-9308
F: 215-573-2068
www.seas.upenn.edu/~nanofab
> 
Begin forwarded message:

From: "Morrison, Richard H., Jr." <rmorrison at draper.com>
Subject: RE: [labnetwork] question to cleanroom colleagues: distributed vs. manifolded gases...
Date: September 20, 2012 12:42:25 PM MDT
To: Ian Harvey <IRHarvey at eng.utah.edu>

HI,

I like to use manifolds at all gas bottles so that we can setup a nice purge system for bottle changes. Equipment such as plasma tools come with distribution panels, so we use those. Otherwise we have a great company that does all of our piping and we go direct to the tool from gas mains running overhead. We have all of our gases in one central gas room and run all the gases around and tee off where needed.

We set the gas mains at the highest pressure needed and then regulate down at the tool. Most tools use specialty gases at 30psig or lower so the regulators are not that big or expensive. This way we stay flexible and can change gases without needing to make new gas panels
Rick

Draper Laboratory
Group Leader Microfabrication Operations
555 Technology Square
Cambridge Ma, 02139-3563

www.draper.com
rmorrison at draper.com
W 617-258-3420
C 508-930-3461

Begin forwarded message:

From: "King, Dave" <kingdc at rpi.edu>
Subject: RE: [labnetwork] question to cleanroom colleagues: distributed vs. manifolded gases...
Date: September 20, 2012 12:30:00 PM MDT
To: Ian Harvey <IRHarvey at eng.utah.edu>

At Rensselaer, we use VMP’s for every non-hazardous gas which we consider to be a “house gas” (in other words, for every gas which is distributed from our central gas rack).  When we add a new gas, if we think that there is any possibility that we will want that gas on another tool later, we put it in the central place and install a VMP.  Therefore, we have some VMP’s which only have one active stick.  For us, the ability to isolate and possibly regulate each line individually is well worth the cost of the VMP. 

If we don’t believe that a new gas will ever be used in multiple places, then we just put a bottle by the tool.  (We also do this for some short-term experiments.)  In no case do we daisy-chain multiple tools off the same gas line; our old gas set-up was like this and it turned out to be a terrible design.

Our hazardous gases all go to exhausted VMB’s, and are distributed to tools from there.

Dave King

Begin forwarded message:

From: "Rizik" <rizik at intengr.com>
Subject: RE: [labnetwork] question to Cleanroom colleagues: distributed vs.	manifolded gases...
Date: September 20, 2012 12:22:24 PM MDT
To: "'Ian Harvey'" <IRHarvey at eng.utah.edu>, <labnetwork at mtl.mit.edu>

Ian,

I usually like to install VMP’s with a minimum of 4- Valve stick where I populate as many sticks as the installation calls for. However, in aisle or service chases where you could have more than four (4) tools requiring this gas, I would install 8-valve stick panels.  The cost of a 4-stick manifold is negligible compared to the cost of running one new ¼” EP SS316L tubing from the lateral to a new drop location. Let alone that you will have to shutdown the gas source and all tools utilizing the gas in question.

Rizik Michael, PE
Principal
Integrated Engineering Services
Office: +408 261 3500, Ext. 201
Cell:      +408 718 0927
www.iesengineering.net

From: "Goodman, James R" <James_Goodman at uml.edu>
Subject: RE: [labnetwork] question to cleanroom colleagues: distributed vs. manifolded gases...
Date: September 20, 2012 12:10:59 PM MDT
To: Ian Harvey <IRHarvey at eng.utah.edu>

Ian,

For our new facility we chose a hybrid approach for the toxic gas distribution. Since our gas room was adjacent to the service chase we incorporated distribution manifolds into the gas cabinets with home runs to each process tool. The downside is to take any system off line for service all tools that use that gas supply are affected. The upside is lower cost of installation since we did not have the capitol cost associated with the VMP’s and the extra monitoring points for the toxic gas monitoring system.

For non-toxic gas we used a common distribution system throughout the clean room.

Jay.

James Goodman
Equipment Manager, ETIC Nano Fabrication Laboratory
40 University Ave.
Room 121
Lowell, MA -01854
Office (978) 934-3469
Cell (603) 235-1496

Begin forwarded message:

From: Ian Harvey <IRHarvey at eng.utah.edu>
Subject: [labnetwork] question to cleanroom colleagues: distributed vs. manifolded gases...
Date: September 20, 2012 9:58:22 AM MDT
To: labnetwork at mtl.mit.edu

Dear micro/nano cleanroom colleagues:

Please critique the following thought process and give your insight which approach is best in planning the process gas piping for a new installation.  

Which do you use (VMP/distributed) in your new facility or new tool installations and are you happy?

If VMP's, what is the threshold number of tools for which you consider it justifiable to use VMP's?

valve manifold panels:
pro's: 
• clean, organized installation, flexible to any future installation, populated when needed
• system contamination attained by ability to purge regulators with venturi
• leaks or failures within isolated runs do not contaminate other processes or cause downtime on other tools
• prevent cross-talk between process MFC's, using the same gases
• does not cause system downtime when installing new processes

Con's
• up front cost is greater, though not sure how much

Process gases distributed through shared supply line, and laterals / drops:
pro's:
• Up front cost is lower (not sure how much-- it depends...)
• cross-talk can be minimized by a regulator at each tool

Con's:
• system downtime for all tools sharing the gases during
• cost may be comparable depending upon number of valved drops, and how good the planning is for predicting future installation points
• see pro's above in VMP

Thank you all!

--Ian

********************************************
Ian R. Harvey, Ph.D.
Research Associate Professor
Department of Mechanical Engineering
Adjunct Associate Professor
Department of Electrical & Computer Engineering
2511 SMBB (USTAR)

Associate Director,
Utah Nanofab & 
Micron Microscopy Core

801/585-6162 (voicemail)
801/581-5676 (lab main number)
www.nanofab.utah.edu

mail to:
Utah Nanofab / University of Utah
36 South Wasatch Drive
Suite 2500
Salt Lake City, Utah   84112-9011
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