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<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hello,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">At Delft University we have an atmospheric exhaust system (scavenger) on the alloy furnace using 10% hydrogen in nitrogen, the system works fine
since 1991.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Kind regards, Henk<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" 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"><span lang="EN-GB" style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D">Delft University of Technology / DIMES<br>
POBox 5053<br>
NL-2600 GB DELFT<br>
The Netherlands<br>
phone: ++31 15 2781092<br>
Mobile: ++31 6 24373305<br>
fax: ++31 15 2787369<br>
Email: h.w.vanzeijl@tudelft.nl</span><span lang="EN-GB" style="font-size:11.0pt;font-family:"Tahoma","sans-serif";color:#1F497D"><o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" 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 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>Fouad Karouta<br>
<b>Sent:</b> 14 November 2012 03:44<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>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-AU" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-AU" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-AU" 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 lang="EN-AU" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-AU" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Regards, Fouad
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-AU" 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 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">
<a href="mailto:labnetwork-bounces@mtl.mit.edu">labnetwork-bounces@mtl.mit.edu</a> [<a href="mailto:labnetwork-bounces@mtl.mit.edu">mailto:labnetwork-bounces@mtl.mit.edu</a>]
<b>On Behalf Of </b>John Shott<br>
<b>Sent:</b> Wednesday, 14 November 2012 12:09 PM<br>
<b>To:</b> <a href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>; Aebersold,Julia Weyer<br>
<b>Subject:</b> Re: [labnetwork] Anneal temp for aluminum on silicon with forming gas<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-AU"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-AU">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></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" style="color:#1F497D">Hi Julia,</span><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" style="color:#1F497D"> </span><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" 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><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" style="color:#1F497D">In the past I did liquid phase epitaxy of GaAs/AlGaAs around 800C in pure H2.</span><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" 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><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" style="color:#1F497D"> </span><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" style="color:#1F497D">Hope this would help.</span><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" style="color:#1F497D">Fouad Karouta</span><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-AU" style="color:#1F497D"> </span><span lang="EN-AU"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-AU"><o:p> </o:p></span></p>
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