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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Matthew,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> TGMS sensors should be placed in gas cabinets, tool gas jungles, VMB’s and anywhere else in the circuit that has a mechanical (non welded) connection, valve,
or pressure gauge. Sensors should not be placed in any part of the pump exhaust stream, before or after the scrubber unless you wish to dump your fab every time someone runs with toxic/flammables. The N2 commonly used to dilute exhaust streams in pumps simply
does not dilute it enough to avoid detection since most TGMS’s are detecting PPM.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Sensors in gas cabinets and VMB’s should be placed in the furthest upstream location of the ductwork in order for it to capture any event within the cabinet.
Please keep in mind that the exhaust from the sensor (providing you have Honey **** style with a little vacuum pump) should be placed further downstream to avoid re-detection as the sensor is clearing itself out. An equally, if not more important placement
is that of the vacuum generator (venturi) exhaust line, this line should be the furthest downstream connection in the ductwork (at least 12” away from detection points).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Ambient sensors are recommended to be placed wherever people are standing when running the tool or any other sensible area that needs detection. In the past,
I have poked them through bulkheads in the cleanroom wall aiming at the area that humanoids tend to congregate and have even had them installed from overhead for more difficult installations. I’m not sure if there are specific rules as to how far from a person
the end of the nozzle has to be but I have always passed internal safety and insurance expectations.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">One caveat about ambient sensors; When the occasion comes up that a vacuum chamber needs to be opened (aside from PVD or clean processes) the ambient sensors
can and will trip from the residual chemical “fragrances”. We have addressed this by purchasing a portable air cleaner with a flexible intake duct that can be pointed right at the offending odor. The charcoal filter abates acid gas odors and is in series with
a HEPA to keep clean room bosses happy. My only regret is not buying one 30 years ago (“cough, cough”).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Steve Paolini<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Equipment Dood<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Harvard University Center for Nanoscale Systems<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> labnetwork-bounces@mtl.mit.edu [mailto:labnetwork-bounces@mtl.mit.edu]
<b>On Behalf Of </b>Matthieu Nannini, Dr.<br>
<b>Sent:</b> Wednesday, February 11, 2015 12:40 PM<br>
<b>To:</b> Labnetwork<br>
<b>Subject:</b> [labnetwork] point of detection - Gas sensors<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Colleagues, first thanks Vito for initiating this discussion. Very important points where made which led me to explore the labnetwork archives about sub-atmospheric setup and TGMS. Fore those interested I will save you the search:
<o:p></o:p></p>
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<p class="MsoNormal"><a href="https://www-mtl.mit.edu/pipermail/labnetwork/2012-August/000541.html">https://www-mtl.mit.edu/pipermail/labnetwork/2012-August/000541.html</a><o:p></o:p></p>
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<p class="MsoNormal"><a href="https://www-mtl.mit.edu/pipermail/labnetwork/2013-August/001004.html">https://www-mtl.mit.edu/pipermail/labnetwork/2013-August/001004.html</a><o:p></o:p></p>
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<p class="MsoNormal"><a href="https://www-mtl.mit.edu/pipermail/labnetwork/2014-July/001346.html">https://www-mtl.mit.edu/pipermail/labnetwork/2014-July/001346.html</a><o:p></o:p></p>
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<p class="MsoNormal"><a href="https://www-mtl.mit.edu/pipermail/labnetwork/2013-August/000998.html">https://www-mtl.mit.edu/pipermail/labnetwork/2013-August/000998.html</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Since we are in a gas discussion timing,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If you had to prioritize the following position of the sensors, what would you recommend ?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">- exhaust of gas cabinet<o:p></o:p></p>
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<p class="MsoNormal">- gas cabinet at the tool<o:p></o:p></p>
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<p class="MsoNormal">- VMB if any<o:p></o:p></p>
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<p class="MsoNormal">- exhaust of pump after the tool ?<o:p></o:p></p>
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<p class="MsoNormal">- exhaust after abatement system ?<o:p></o:p></p>
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<p class="MsoNormal">- free space sensors scattered around most sensitive areas: where human presence is usually high<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-family:"Helvetica","sans-serif";color:black">-----------------------------------
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Helvetica","sans-serif";color:black">Matthieu Nannini<br>
McGill Nanotools Microfab<br>
Manager<br>
t: 514 398 3310<br>
c: 514 758 3311<br>
f: 514 398 8434<br>
<a href="http://mnm.physics.mcgill.ca/">http://mnm.physics.mcgill.ca/</a><br>
------------------------------------<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Le 2015-02-11 à 10:53, Vito Logiudice <<a href="mailto:vito.logiudice@uwaterloo.ca">vito.logiudice@uwaterloo.ca</a>> a écrit :<o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Hi Dennis,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Great insights – thanks very much for sharing.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Our aim is to avoid cold spots and keep the entire system at 19C to 20C, especially since the DCS line traverses a loading dock between the gas bunker and the fab. The two
roll-up dock doors are equipped with heated air curtains but we wanted the added insurance of a heated/insulated line. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">In our particular case, we've got a single 120 foot line between the gas cabinet and the point of use (no VMB's) and we did our best to stay true to the use of large radius
bends all along the run. The DCS panel design was kept as simple as possible (no regulator) and the entire cabinet is located in a heated bunker in which temperature trends are monitored.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Good point about the possible risk of fire. While the heat trace controller is capable of outputting a limited amount of power, we did see some odd "burn" marks at some locations
which lead us to conclude that the Armaflex insulation's upper use limit of 105C may have been exceeded at some of the void locations. In light of these findings we've decided to use fiberglass insulation instead of Armaflex for the repair.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Best,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Vito<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:
</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Dennis Grimard <<a href="mailto:dgrimard@umich.edu">dgrimard@umich.edu</a>><br>
<b>Date: </b>Tuesday, 10 February, 2015 10:32 PM<br>
<b>To: </b>Vito Logiudice <<a href="mailto:vito.logiudice@uwaterloo.ca">vito.logiudice@uwaterloo.ca</a>><br>
<b>Cc: </b>Labnetwork <<a href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>><br>
<b>Subject: </b>Re: [labnetwork] Conclusion: Heat trace issues on DCS gas lines<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Vito:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">I have watched with great pleasure the discussion on this topic. I too agree that much good info has been discussed ... Great feedback from some very knowledgable people
indeed.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">I need to throw a wrench in the discussion (or prove my ignorance). I have always resisted heat taping for the following reasons: 1) when the tube enters a VMB or any ventilated
enclosure there is a significant temperature drop due to the large purging flow rate within the enclosure ... Tending to cool the line at the worst possible point, 2) the VMB type enclosures tend to have many right angle welds and valves which promote condensation
.... Rather than long graceful bends typically used external to the enclosure, 3) SS is a horrible heat conductor ... As is n2 gas ... So if I heat trace a double wall tube how much heat actually gets to the inner tube? how consistent is that heat? What
is the temperature gradient?, and 4) the actual cold to hot temperature gradient (desired) is difficult to institute along the length of line ... A good feedback loop is required. Also, heat tape gives me the district impression that it can contribute to
an out of control heating failure with a possible fire as a result.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">So, not that it solves your problem but here is what I have tried to always implement: 1) short runs (home runs not a distribution), 2) minimum short radius right angles,
3) minimize VMB's ... Mini gas cabinets with multiple outputs in the cabinet, 4) chilled bottles, 5) vacuum delivery, and 6) large radius bends.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Just food for thought ...<br>
<br>
Dennis S Grimard, Ph.D. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Associate Director of Operations, MIT.nano<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Massachusetts Institute of Technology<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">60 Vassor Street, Bldg 39-556<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Cambridge, MA 02149<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">C: (734) 368-7172<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">EM: <a href="mailto:dgrimard@mit.edu">dgrimard@mit.edu</a><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><br>
On Feb 10, 2015, at 1:30 PM, Vito Logiudice <<a href="mailto:vito.logiudice@uwaterloo.ca">vito.logiudice@uwaterloo.ca</a>> wrote:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Dear Colleagues,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Thank you very much to everyone whom took the time to write in with their insights on this issue. Special thanks to John Shott and Tom Britton for the photos and reference
documents provided.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">So that others may perhaps benefit from our experience, we've concluded that the cause of the premature failure appears to have been the presence of several "voids" where
the heat trace was not in intimate contact with the SS tubing. This occurred even though the trace had been taped every 12 inches per the manufacturer's recommendations. We also noted voids at some elbows where maintaining contact was/is difficult. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">To keep the issue from repeating itself in the future, our plan is to reinstall two new heat traces along the length of the tubing, one on the bottom and one on the top.
One of these will remain active while the backup trace will be kept off and act as an insurance policy should the primary unit fail in the future. If anyone sees a problem with this particular approach, I would be glad to hear from you.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">In the new installation, conductive putty will be used to fill any voids before aluminum tape is applied along the entire length of the line much like John showed in his
attached photo. The entire assembly will then be re-insulated per the original design specification. Fortunately, the problem occurred under warranty so our only out-of-pocket cost will be limited to the cost of the backup heat trace (a few hundred dollars).<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Regards,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Vito<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:
</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Vito Logiudice <<a href="mailto:vito.logiudice@uwaterloo.ca">vito.logiudice@uwaterloo.ca</a>><br>
<b>Date: </b>Wednesday, 21 January, 2015 12:23 PM<br>
<b>To: </b>Labnetwork <<a href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>><br>
<b>Subject: </b>[labnetwork] Heat trace issues on DCS gas lines<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Dear Colleagues,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">We are experiencing an issue with the heat trace on our Dichlorosilane gas line. The all-welded 1/4" SS line is encapsulated with a 1/2" SS outer containment line which
is itself heat traced with a single strand of heat trace that runs the entire length of the coax assembly. The 120 foot line is insulated as shown in the attached photo. A portion of the heat-trace appears to have failed prematurely (it was installed less
than one year ago) and we are wondering if the method of installation may be the cause.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">The heat trace was not installed in a spiral fashion around the outer 1/2" tube. Rather it was installed in a straight fashion along its entire length with "heat trace fastening
tape" located every four feet or so. A member of my team has suggested that such a straight rather than spiral installation may have caused hot spots (at the fastening locations) which may have in turn caused the failure.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">I would appreciate hearing from the community on this point: Are the heat traces around your low pressure gas lines spiral-wound around the lines or are they installed in
a straight fashion and somehow fastened along the entire length?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Other insights/suggestions on the proper heat tracing of gas lines by experts in the field as well as comments on possible causes of premature heat trace failure are very
much welcome and appreciated. Thank you.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Regards,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">Vito<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">--</span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Vito Logiudice P.Eng.</span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Director of Operations, Quantum NanoFab</span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">University of Waterloo</span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Lazaridis QNC 1207</span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">200 University Avenue West</span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Waterloo, ON Canada N2L 3G1</span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Tel.: (519) 888-4567 ext. 38703</span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Email: <a href="mailto:vito.logiudice@uwaterloo.ca">vito.logiudice@uwaterloo.ca</a></span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Website: </span><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><a href="https://fab.qnc.uwaterloo.ca/">https://fab.qnc.uwaterloo.ca</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.5pt;font-family:"Calibri","sans-serif"">_______________________________________________<br>
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