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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Teflon cassette story. We did a phosphoric acid/reflux operation at 180 degrees C for the removal front and backside of siicon nitride for a CMOS process we were doing. There was around 500 angstroms of silicon dioxide under the nitride to begin with at the start of the process. We dedicated new Teflon cassettes for the operation and immediately found out that the outgassing of fluorine from the cassettes etched away all of the silicon dioxide film. It took several hundred wafers before action was taken to eliminate the problem. If I remember right it took 8 hours of soaking in hot phosphoric to deplete the outgassing of the fluorine for the new cassettes. After that only those cassettes were used for the nitride removal operation with little of no etching of the oxide underneath the nitride. Bob Henderson<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 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>Keith Franklin<br><b>Sent:</b> Friday, April 29, 2016 8:19 AM<br><b>To:</b> Mary Tang<br><b>Cc:</b> Labnetwork<br><b>Subject:</b> Re: [labnetwork] Piranha processing vessels<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Thank you all for the feedback. Very helpful! Please keep them coming should anyone else be willing to contribute.<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Best,<o:p></o:p></p></div><div><p class=MsoNormal>Keith<o:p></o:p></p></div></div><div><p class=MsoNormal><br clear=all><o:p></o:p></p><div><div><div><div><div><div><div><div><div><div><p class=MsoNormal><u><span style='font-size:7.5pt'> </span></u><span style='font-size:7.5pt'> </span><o:p></o:p></p></div><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>Keith Franklin</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>Operations Manager</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>University of Alberta - nanoFAB</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>W1-060 ECERF Building</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>9107 - 116 Street</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>Edmonton, Alberta</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>Canada T6G 2V4 Ph: 780-492-0170</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'><a href="http://www.nanofab.ualberta.ca" target="_blank">www.nanofab.ualberta.ca</a> </span><o:p></o:p></p></div></div></div></div></div></div></div></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>On Fri, Apr 29, 2016 at 7:29 AM, Mary Tang <<a href="mailto:mtang@stanford.edu" target="_blank">mtang@stanford.edu</a>> wrote:<o:p></o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'>Thanks Bob!<br><br>A wonderful example of how "contamination" can be managed by means other than the paranoia -- something we struggle with as we try to serve a broader community while trying to keep our electronics and detector researchers happy. I would hazard a guess that this works in industry because distillation is vacuum rather than heated and that an additional RCA-equivalent clean is used before high temperature processing steps, thus minimizing the risk of driving in mobile ions.<br><br>That said, at Stanford, we do promote paranoia when it comes to dedicated teflon cassettes in MOS stations because of their propensity to absorb whatever chemical they are exposed to. I've not seen any data that shows cross-contamination due to this, but have seen the results of off-gassing on wafers stored or heated in chemical bath cassettes. The risk of significant carryover of HF into piranha may be very low, but might be worth considering dedicated cassettes when using pyrex.<span style='color:#888888'><br><br><span class=hoenzb>Mary<o:p></o:p></span></span></p><p><o:p> </o:p></p><pre><span style='color:#888888'>-- <o:p></o:p></span></pre><pre><span style='color:#888888'>Mary X. Tang, Ph.D.<o:p></o:p></span></pre><pre><span style='color:#888888'>Stanford Nanofabrication Facility<o:p></o:p></span></pre><pre><span style='color:#888888'>Paul G. Allen Bldg 141, Mail Code 4070<o:p></o:p></span></pre><pre><span style='color:#888888'>Stanford, CA 94305<o:p></o:p></span></pre><pre><span style='color:#888888'><a href="tel:%28650%29723-9980" target="_blank">(650)723-9980</a><o:p></o:p></span></pre><pre><span style='color:#888888'><a href="mailto:mtang@stanford.edu" target="_blank">mtang@stanford.edu</a><o:p></o:p></span></pre><pre><span style='color:#888888'><a href="http://snf.stanford.edu" target="_blank">http://snf.stanford.edu</a><o:p></o:p></span></pre><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>On 4/28/2016 1:21 PM, Robert M. HAMILTON wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>Keith, <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I'll stick my neck out! <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>The UC Berkeley NanoLab uses fused silica tanks with encased heaters and ground-fault detection for our piranha baths. I am guessing your suggestion of Pyrex or an alternative borosilicate glass will raise the hackles of some Labnetwork readers. And, I cannot claim experience with the impact of borosilicate glasses, used for piranha cleans, for MOS devices. <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>However, I can point to a patent issued to Alameda Instruments that made H2SO4 reclaim/reprocessing systems for a number of major semiconductor manufacturers. I also have known, since boyhood the research glassblower who made their vacuum stills. The glass used was Pyrex or an alternative Duran, which is Schott's equivalent. This leads me to the conclusion H2SO4 from a pyrex still was good enough for Intel, Pyrex is probably good enough for you.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Having said this if there is accidental contamination via HF your Pyrex will contribute alkali and your devices will be DOA. We have seen HF contamination in our baths on a few occasions.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>For reference see: <a href="https://www.google.com/patents/US4980032" target="_blank">https://www.google.com/patents/US4980032</a><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Bob Hamilton<o:p></o:p></p></div></div></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>PS Caveat emptor! Corning now uses the term Pyrex for a broader number of glasses than their traditional 7740.<o:p></o:p></p></div></div><div><p class=MsoNormal><br clear=all><o:p></o:p></p><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div><p class=MsoNormal><br>Robert Hamilton<o:p></o:p></p></div><p class=MsoNormal>University of CA, Berkeley<br>Marvell NanoLab Equipment Manager<o:p></o:p></p></div><p class=MsoNormal>Rm 520 Sutardja Dai Hall, MC 1754<o:p></o:p></p></div><p class=MsoNormal>Berkeley, CA 94720<o:p></o:p></p></div><p class=MsoNormal>Phone <a href="tel:510-809-8618" target="_blank">510-809-8618</a> (desk - preferred)<o:p></o:p></p></div><p class=MsoNormal>Mobile <a href="tel:510-325-7557" target="_blank">510-325-7557</a> (my personal mobile)<o:p></o:p></p></div><p class=MsoNormal>E-mail preferred: <a href="mailto:bob@eecs.berkeley.edu" target="_blank">bob@eecs.berkeley.edu</a><br><a href="http://nanolab.berkeley.edu/" target="_blank">http://nanolab.berkeley.edu/</a><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div></div></div></div></div></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>On Thu, Apr 28, 2016 at 10:59 AM, Keith Franklin <<a href="mailto:keithf@ualberta.ca" target="_blank">keithf@ualberta.ca</a>> wrote:<o:p></o:p></p><div><p class=MsoNormal>Good day all, <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>We're currently revisiting what vessels or tanks we use for processing with hot piranha. Our most common application is for cleaning a partially filled cassette of 4" Si wafers. We typically purchase Pyrex 6944 vessel and have our glass shop cut them down to a more reasonable height. In our last purchase cycle, we noticed that the ID has changed ever so slightly and it's now challenging to squeeze our standard Entegris cassette into this vessel. We're currently looking into custom machined PVC, PP, Teflon & Quartzware, as well as off the shelf small volume tanks, etc.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I'm hoping to better understand what other similar labs are using for this application (& potentially 6" wafers as well). Any advice or feedback would be greatly appreciated.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Kind Regards,<o:p></o:p></p></div><div><p class=MsoNormal>Keith<o:p></o:p></p></div><div><div><div><div><div><div><div><div><div><div><div><p class=MsoNormal><u><span style='font-size:7.5pt'> </span></u><span style='font-size:7.5pt'> </span><o:p></o:p></p></div><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>Keith Franklin</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>Operations Manager</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>University of Alberta - nanoFAB</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>W1-060 ECERF Building</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>9107 - 116 Street</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>Edmonton, Alberta</span><span style='font-size:7.5pt'><o:p></o:p></span></p><p style='margin:0in;margin-bottom:.0001pt'><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'>Canada T6G 2V4 Ph: <a href="tel:780-492-0170" target="_blank">780-492-0170</a></span><span style='font-size:7.5pt'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:black'><a href="http://www.nanofab.ualberta.ca" target="_blank">www.nanofab.ualberta.ca</a> </span><o:p></o:p></p></div></div></div></div></div></div></div></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt'><br>_______________________________________________<br>labnetwork mailing list<br><a href="mailto:labnetwork@mtl.mit.edu" target="_blank">labnetwork@mtl.mit.edu</a><br><a href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork" target="_blank">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</a><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><pre>_______________________________________________<o:p></o:p></pre><pre>labnetwork mailing list<o:p></o:p></pre><pre><a href="mailto:labnetwork@mtl.mit.edu" target="_blank">labnetwork@mtl.mit.edu</a><o:p></o:p></pre><pre><a href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork" target="_blank">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</a><o:p></o:p></pre></blockquote><p class=MsoNormal><o:p> </o:p></p></div></div></div></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>