<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:windowtext;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Rick, Silicon nitride via LPCVD is an extremely dirty process from the perspective of the vacuum pump. In my experience, I have had the most success with this approach; heat the pumping line from where the transition from quartz to steel is and continue with heat trace up to a liquid cooled trap. This method actually enhances the growth of by-products (mainly ammonium chloride) in an area that can be easily serviced. When I was in manufacturing and we ran these furnaces constantly, this configuration along with a spare water cooled trap, significantly reduced downtime since we controlled where the by-products collected. Here at Harvard we simply use a stainless mesh filter on the pumping line and service the transitional fitting that connects to the quartzware every few months but we don’t run nearly as much as a production facility.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>I am unfamiliar with adding hydrogen to LPCVD nitride, just DCS and NH3. I would choose a pyrolizing type scrubber for any excess SIH4 and if there was added H2 it would mitigate that as well.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Regards,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'> Steve Paolini<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'> Harvard University CNS<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><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>Morrison, Richard H., Jr.<br><b>Sent:</b> Wednesday, April 11, 2012 8:09 AM<br><b>To:</b> labnetwork@mtl.mit.edu<br><b>Subject:</b> [labnetwork] Silicon Nitride question<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi Everyone,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am restarting a Silicon Nitride LPCVD process and I have a few questions. The process will use a EBARA dry pump therefore should I use a trap on the vacuum pump inlet to catch any particulate generated? <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Any issue with excess hydrogen from the process going into the dry pump, do I need a burn box on the vacuum pump exhaust?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>2<sup>nd</sup> question has anybody tried to run the LPCVD process on a wafer with a platinum metal pattern on the surface? I was wondering if there maybe some adverse effect because of the catalytic nature of Platinum.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks<o:p></o:p></p><p class=MsoNormal>Rick<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Rick Morrison<o:p></o:p></p><p class=MsoNormal>Senior Member Technical Staff <o:p></o:p></p><p class=MsoNormal>Group Leader Microfabrication Operations<o:p></o:p></p><p class=MsoNormal>Draper Laboratory<o:p></o:p></p><p class=MsoNormal>555 Technology Square<o:p></o:p></p><p class=MsoNormal>Cambridge, MA 02139<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>W 617-258-3420<o:p></o:p></p><p class=MsoNormal>C 508-930-3461<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>