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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi Eva,<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">Given the size of the defects and the lack of a comet tail in the resist, it looks like small droplets landed on the photoresist film near the end or after the
wafer finished spinning. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">The droplets could be from aerosolized photoresist/solvent micro droplets generated during spin coating.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Another possibility would be splashed acetone droplets, from wetting a fabwipe in close proximity.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">The defects appears to be surface wrinkling whose pattern is the result of stress minimization in the photoresist skin as the extra solvent dries.<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"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Bill<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> labnetwork <labnetwork-bounces@mtl.mit.edu>
<b>On Behalf Of </b>Lino Eugene<br>
<b>Sent:</b> Saturday, October 23, 2021 9:28 AM<br>
<b>To:</b> Eva Rose <eva.rose@gno.de><br>
<b>Cc:</b> labnetwork@mtl.mit.edu<br>
<b>Subject:</b> Re: [labnetwork] Defects after resist spinning<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Eva,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">It looks like that there is dendritic cristallisation in your defects.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Was the subtrate immersed in RCA 1 or BOE or any solution involving a salt? If so, my first thought is that the substrate was not rinsed properly prior spin coating.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Best,<o:p></o:p></p>
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<p class="MsoNormal">Lino Eugene<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Oct. 23, 2021 07:46, Aaron Hryciw <<a href="mailto:ahryciw@ualberta.ca">ahryciw@ualberta.ca</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hi Eva, <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Out of curiosity, did you previously inspect the wafer in an optical microscope using a higher-mag objective than the one used to capture the images? Given how circular these defects look, and the concentric pattern, my guess is that this
is a heating effect, the result of staying too long in one position with a high light intensity.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Cheers, <o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"> – Aaron<o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal"><u><span style="font-size:10.0pt"> </span></u><span style="font-size:10.0pt"> </span><o:p></o:p></p>
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<p style="margin:0in;margin-bottom:.0001pt"><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:black">Aaron Hryciw, PhD, PEng</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">Fabrication Group 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: 780-940-7938</span><span style="font-size:7.5pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><a href="http://www.nanofab.ualberta.ca/"><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#1155CC">www.nanofab.ualberta.ca</span></a><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:black">
</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Oct 22, 2021 at 5:55 PM Eva Rose <<a href="mailto:eva.rose@gno.de">eva.rose@gno.de</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Dear all,<br>
<br>
<br>
did anybody ever see any defects like this on the resist surface after resist spinning. The diameter varies from about 20um to over 150um.<br>
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<img border="0" width="32" height="32" style="width:.3333in;height:.3333in" id="_x0000_i1026" src="cid:17caaeab150a3a20b871" alt="cid:17caaeab150a3a20b871"><br>
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<img border="0" width="32" height="32" style="width:.3333in;height:.3333in" id="_x0000_i1025" src="cid:17caaeab15074e3f89d2" alt="cid:17caaeab15074e3f89d2"><br>
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Any idea what the reason could be?<br>
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Best regards,<br>
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Eva<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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