[labnetwork] 回复: Re: Carbon contamination from Ar

[Yulong Chen]

Dear Kevin Under high pressure, gold film from black gold (porous) Maybe it's black gold, you can simply identify it by use KI/I2 gold ethant. Regards 陈宇龙(CHEN Yulong) 南方科技大学/工学院/材料科学与工程系 深圳市南山区学苑大道1088号 在2017年10月28日 23:03 ，Kevin McPeak写道： Dear Mike, That is a good point. We should totally do that and will. What else do you think this black stuff could be? Regards, Kevin -- Kevin McPeak Assistant Professor Department of Chemical Engineering Louisiana State University email: kmcpeak at lsu.edu phone: 225-578-0058 On Oct 28, 2017 09:58, "Mike Young" <myoung6 at nd.edu> wrote: Hi Kevin. Have you confirmed the deposits are in fact carbon? Scrape some off and perfom EDX in a SEM, for example? --Mike On 10/28/2017 12:19 AM, Kevin McPeak wrote: Dear Colleagues,

In my lab at LSU we are interested in evaporating Au under high Ar
pressures, 10 - 50 mTorr. We are using Ar 5.0 purity (99.999%), which
has a THC of 1 ppm.

Our procedure is such:

1). Pump chamber down to low -7 Torr range
2). Inject 30 SCCM Ar and throttle gate valve to the desired pressure
(say 50 mTorr)
3). Increase power to Tungsten boat till Au pellets evaporate

When we vent the chamber we notice a lot of carbon deposition near the
outlet of the Ar line (see attached image). We have a THC of 1 ppm in
the Ar tank. We also tried hooking up a GP-100 gas purifier from RD
Mathis. Unfortunately, that didn't solve the problem, still lots of
carbon deposition in the chamber. The GP-100 is currently connected
upstream from the MFC. I am using SS tubes with all VCR fittings
(total length 6 ft). We could move the GP-100 closer to the chamber,
post-MFC.

Based on the photo I think it is pretty clear that the carbon is
coming from the Ar. So my current thought is that either I have a leak
in my tubes post GP-100 or I need to flame bake the lines (I have not
done this). I am trying to get access to an RGA to investigate this
more quantitatively. I do have access to a He checker so I could try
pumping on the Ar lines.

Have any of you seen Carbon contamination like this before when doing
high-pressure evap (I know that is not a normal thing)? I am curious
what people think. Thanks!

Regards,
Kevin

 -- 
Michael P. Young                                (574) 631-3268 (office)
Nanofabrication Specialist                      (574) 631-4393 (fax)
Department of Electrical Engineering            (765) 637-3784 (cell)
University of Notre Dame                         mike.young at nd.edu
B-38 Stinson-Remick Hall
Notre Dame, IN 46556-5637
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