<div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">Dear <span style="font-family:Arial,Helvetica,sans-serif;color:rgb(34,34,34)">Sa’ad,</span></div><div class="gmail_default" style="">I had seen this problem and lost a few good processed wafers. </div><div class="gmail_default" style="">The reason I found is overexposure to UV. If you are using EVG 620 or any MJB tool, please expose the wafers for 90-100 mJ/Cm2 only. If you are using any direct UV bulb, make sure you are exposing for a very brief period of time and also the bulb or the stage is not very hot. </div><div class="gmail_default" style=""><br></div><div class="gmail_default" style="">The best way to recover the
dies which are cemented to the tape is by dipping the whole diced wafer in PG remover solution for about 12 hours. After that you can remove the tape very easily. However, you might see a glue stain at the back of the wafer. Try to ash it for about 5 min and your devices will work. </div><div class="gmail_default" style=""><br></div><div class="gmail_default" style="">Thanks & best regards,</div><div class="gmail_default" style="">vamsi</div><div class="gmail_default" style=""><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, May 17, 2019 at 5:31 AM Paolini, Steven <<a href="mailto:spaolini@cns.fas.harvard.edu">spaolini@cns.fas.harvard.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal">Sa’ad,<u></u><u></u></p>
<p class="MsoNormal"> Are you applying your tape manually on the hotplate at temperature? If so, UV tape adhesive will cross link at higher temperatures than your UV source delivers. Another possibility is overexposure. Best way to handle it is with a D.O.E
using different exposure times. You will find that the window between underexposing and overexposing is fairly generous. I do suspect the elevated temperature on the hotplate being the root cause if that’s what you’re doing.<u></u><u></u></p>
<p class="MsoNormal"> I hope this helps,<u></u><u></u></p>
<p class="MsoNormal"> Steve (Equipment Dood)<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><span style="font-size:14pt">Steve Paolini<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt">Principal Equipment Engineer<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt">Harvard University Center for Nanoscale Systems<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt">11 Oxford St.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt">Cambridge, MA 02138<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt">617- 496- 9816<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt"><a href="mailto:spaolini@cns.fas.harvard.edu" target="_blank">spaolini@cns.fas.harvard.edu</a><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:14pt"><a href="http://www.cns.fas.harvard.edu" target="_blank">www.cns.fas.harvard.edu</a></span><span style="font-size:14pt"><u></u><u></u></span></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><b>From:</b> <a href="mailto:labnetwork-bounces@mtl.mit.edu" target="_blank">labnetwork-bounces@mtl.mit.edu</a> <<a href="mailto:labnetwork-bounces@mtl.mit.edu" target="_blank">labnetwork-bounces@mtl.mit.edu</a>>
<b>On Behalf Of </b>Hassan, Sa'ad<br>
<b>Sent:</b> Thursday, May 16, 2019 1:40 PM<br>
<b>To:</b> <a href="mailto:labnetwork@mtl.mit.edu" target="_blank">labnetwork@mtl.mit.edu</a><br>
<b>Subject:</b> [labnetwork] Diced Samples Glued to UV Release Tape<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Hello All,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">As part of the last step of processing, I take wafers (Si and SiC), with photoresist on top, dice them, die expand them on a hotplate at 55 degrees Celsius. And finally UV release the tape. I’ve noticed that sporadically, rather than the
tape losing adhesion, the opposite happens: the die end up cemented to the tape. Has anyone experienced anything like this before?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Cheers,<u></u><u></u></p>
<p class="MsoNormal">Sa’ad<u></u><u></u></p>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><font style="font-family:verdana,sans-serif;color:rgb(0,0,102)" size="2"><span style="color:rgb(102,102,102)">--<br>Thanks & Best Regards,<br>-----------------<br><b>N.P.Vamsi Krishna</b></span></font></div><div dir="ltr"><span style="color:rgb(0,0,102);font-family:verdana,sans-serif">Center for Nano Science and Engineering,</span><font style="font-family:verdana,sans-serif;color:rgb(0,0,102)" size="2"><br></font></div><div dir="ltr"><font style="font-family:verdana,sans-serif;color:rgb(0,0,102)" size="2"><span>Indian Institute of Science (IISc), Banga<font size="2">lore.</font><br><font size="2">INDIA</font></span>-</font><font style="font-family:verdana,sans-serif;color:rgb(0,0,102)" size="2"><span>560012</span></font></div></div></div></div></div></div></div></div>