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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-AU link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi,<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'>Indeed I do agree with John about the issue related to an open furnace tube. I assumed a sealed furnace tube with vacuum pump.<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'>Regards, Fouad <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><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> labnetwork-bounces@mtl.mit.edu [mailto:labnetwork-bounces@mtl.mit.edu] <b>On Behalf Of </b>John Shott<br><b>Sent:</b> Wednesday, 14 November 2012 12:09 PM<br><b>To:</b> labnetwork@mtl.mit.edu; Aebersold,Julia Weyer<br><b>Subject:</b> Re: [labnetwork] Anneal temp for aluminum on silicon with forming gas<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Julia:<br><br>Fouad is correct that things like epitaxial reactors and MOCVD equipment run pure hydrogen at high temperatures. They also have careful pre- and post-run purging to remove residual air before hydrogen is introduced and typically also have some form of hydrogen burning/scrubbing at the exhaust end. In short, epi reactors and MOCVD systems go to great lengths to make sure that oxygen and hydrogen NEVER mix at high temperatures. I certainly wouldn't want to be in the room if you tried to run pure hydrogen at 800 C in a typical horizontal annealing furnace. I suspect that Fouad would agree that this would be a very bad idea. Long ago, when running an oxidation furnace with a hydrogen torch to generate steam, I learned why you want to make sure that the ratio of hydrogen to oxygen is safely less than 2.0: I turned a cassette of wafers into fine glitter all over the laboratory floor.<br><br>But, back to the issue of forming gas anneals:<br><br>For a comparatively open forming gas anneal setup, I believe that your numbers of 5% forming gas at 400 C or slightly higher are right in the proper ball park. I'll be surprised if others aren't very close to this range in their own usage.<br><br>We at Stanford run 4% forming gas and the great majority of our lab members likely do their annealing at either 400 or 450 C typically for about 30 minutes. The furnace used for this typically idles close to 400 C so there isn't too much of a ramp up/down even if the actual anneal will be at 450 C.<br><br>At 450 you probably get slightly better annealing of interface traps than you would at 400 C ... but you can also see more in the way of hillock formation if you have aluminum or aluminum-alloy metalization on your wafers.<br><br>Good luck,<br><br>John<br><br><br>On 11/13/2012 2:07 PM, Fouad Karouta wrote: <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>Hi Julia,</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>Pure H2 is commonly used in epitaxy reactors at temperature well above 600°C. MOCVD of GaAs/AlGaAs is performed at T=600-800C.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>In the past I did liquid phase epitaxy of GaAs/AlGaAs around 800C in pure H2.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>Moreover Flammability of H2 in air is between 4 to 80%. So in inert gas like N2 the flammability are different.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>Hope this would help.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>Fouad Karouta</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>