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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I’ve seen similar bubbles in the past, but not consistently. While I’m aware that the clean room I have access to is only loosely humidity controlled, what should be an acceptable range. The resist
I use doesn’t mention anything. My relaxation time between pre-bake and exposure is typically 1 hour to let the substrates cool, does anyone have a guide to working that out?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:2.0pt"><span style="font-size:9.0pt;color:#1F497D">Daniel Lloyd<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:2.0pt"><span style="font-size:9.0pt;color:#1F497D">Development Engineer,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> labnetwork <labnetwork-bounces@mtl.mit.edu>
<b>On Behalf Of </b>Morrison, Richard H., Jr<br>
<b>Sent:</b> 04 November 2021 15:45<br>
<b>To:</b> Maduzia, Joseph Walter <jmaduzi2@illinois.edu>; labnetwork@mtl.mit.edu<br>
<b>Subject:</b> Re: [labnetwork] PR bubbles where exposed<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">HI,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">These look like Nitrogen bubbles, how thick is the resist? Is the thickness in the recommended range?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">We have this issue when the humidity is out of control, we solved the issue by reducing the thickness, to be in the recommended range and changing the prebake per advice form the resist supplier.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Rick<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Richard Morrison<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">PMTS<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Draper Laboratory<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">555 Technology Square<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Cambridge Ma 02139<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Office: 617-258-3420<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Cell: 508-930-3461<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> labnetwork <<a href="mailto:labnetwork-bounces@mtl.mit.edu">labnetwork-bounces@mtl.mit.edu</a>>
<b>On Behalf Of </b>Maduzia, Joseph Walter<br>
<b>Sent:</b> Thursday, November 4, 2021 9:59 AM<br>
<b>To:</b> <a href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a><br>
<b>Subject:</b> [labnetwork] PR bubbles where exposed<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Hello All!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thank you again for all your feedback on SiO2 etch around Al. It has been very helpful and we are moving down multiple paths suggested via the Lab Network to try to solve the issue. More to come once we solve it!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I have another issue I was hoping for feedback on. We have bubbling in our PR (SPR-220-4.5) (pos tone) that we haven’t been able to track the source of. It only bubbles during exposure and only where it is exposed. Unexposed
areas are unaffected. I’ve attached some images of the bubbling where you can see the exposed (lighter) and unexposed (darker) areas. The bubbles are visible to the naked eye. The wafer is silicon w a dry thermally grown SiO2 surface. We typically expose via
EV620 mask aligner with Vac+HardContact. However, even in a flood exposure with the mask just set lightly down it still bubbles. Without a mask there are also bubbles randomly distributed across the wafer, but they don’t get stuck to the mask so they don’t
pop. We tried various pre-bakes, HMDS coat vs not, piranha treat vs not. In the past these bubbles show up, we trial and error to get rid of them and suddenly they disappear. Our process, although seemingly repeatable, does not yield repeatable results.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thank You,<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="color:#13294B;text-transform:uppercase">JOE MADUZIA</span></b><span lang="EN-US" style="color:black"><br>
</span><i><span lang="EN-US" style="color:#13294B">MNMS Laboratory Specialist</span></i><span lang="EN-US" style="color:black"><br>
<br>
</span><span lang="EN-US" style="color:#13294B">The Grainger College of Engineering</span><span lang="EN-US" style="color:black"><br>
</span><span lang="EN-US" style="color:#13294B">Mechanical Science and Engineering</span><span lang="EN-US" style="color:black"><br>
<br>
</span><span lang="EN-US" style="color:#13294B">2239 Sidney Lu Mechanical Engineering Bldg</span><span lang="EN-US" style="color:black"><br>
</span><span lang="EN-US" style="color:#13294B">1206 W. Green</span><span lang="EN-US" style="color:black"><br>
</span><span lang="EN-US" style="color:#13294B">Urbana, IL 61801</span><span lang="EN-US" style="color:black"><br>
</span><span lang="EN-US" style="color:#13294B">217.244.6302 | </span><span lang="EN-US"><a href="mailto:jmaduzi2@illinois.edu">jmaduzi2@illinois.edu</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><a href="https://cleanroom.mechse.illinois.edu/">https://cleanroom.mechse.illinois.edu/</a><span style="color:black"><br>
<br>
</span></span><a href="http://illinois.edu/"><span lang="EN-US" style="color:windowtext;text-decoration:none"><img border="0" width="134" height="35" style="width:1.3958in;height:.3645in" id="Picture_x0020_1" src="cid:image001.png@01D7D22E.664E3910"></span></a><span lang="EN-US" style="color:black"><br>
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</span><i><span lang="EN-US" style="color:#666666">Under the Illinois Freedom of Information Act any written communication to or from university employees regarding university business is a public record and may be subject to public disclosure.</span></i><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Notice: This email and any attachments may contain proprietary (Draper non-public) and/or export-controlled information of Draper. If you are not the intended recipient of this email, please immediately notify the sender
by replying to this email and immediately destroy all copies of this email. <o:p>
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