<div dir="ltr"><div class="gmail_default" style="color:rgb(0,0,102)"><br><p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif">Hi Tom,</font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif">Thank you for this question. I had a similar problem with Cryo
etch in the Oxford tool. I didn't understand why this is happening, but I was
able to make some repeatable samples. </font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif"> </font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif">My Cryo etch process was on dies and not on the full wafer.
I bond the die to the carrier wafer. Here are my observations: </font></p>
<p class="gmail-MsoListParagraphCxSpFirst" style="margin:0in 0in 0in 0.25in"><font face="verdana, sans-serif">1.<span style="font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal">
</span>Pre-conditioning of the chamber with the cryo
process helped a lot. </font></p>
<p class="gmail-MsoListParagraphCxSpMiddle" style="margin:0in 0in 0in 0.75in"><font face="verdana, sans-serif">a.<span style="font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal">
</span>After the condition run, if I see the black
silicon, chamber cleaning is required. </font></p>
<p class="gmail-MsoListParagraphCxSpMiddle" style="margin:0in 0in 0in 0.75in"><font face="verdana, sans-serif">b.<span style="font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal">
</span>Ar + Oxygen clean and then oxygen clean helped. </font></p>
<p class="gmail-MsoListParagraphCxSpLast" style="margin:0in 0in 0in 0.75in"><font face="verdana, sans-serif">c.<span style="font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal">
</span>Followed by repeating the conditioning. </font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif">2. Etching fewer dies worked better than multiple dies on
the wafer. </font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif">3. After some successful runs, I generally observe black
silicon starting on one of the corners of the carrier wafer.
Once I see the black silicon, it's better to discard the carrier wafer and
use a fresh one. Using the same wafer resulted in full black silicon affecting
the die and chamber needing cleaning and condition again. </font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif">4. Also, the results were bad if the temperature was unstable.
</font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif"> </font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif">To the best of my knowledge, chamber conditioning is the key.
</font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif"> </font></p>
<p class="MsoNormal" style="margin:0in"><font face="verdana, sans-serif">Once your issue is fixed, I request you to share the knowledge
and experience. </font></p></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066"> </div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">Thanks & br,</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">Vamsi</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Apr 9, 2021 at 4:16 PM Ferraguto, Thomas S <<a href="mailto:Thomas_Ferraguto@uml.edu" target="_blank">Thomas_Ferraguto@uml.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">
<div lang="EN-US">
<div>
<p class="MsoNormal">Colleagues,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I’ve been doing some deeper than usual silicon etch on my Oxford ICP 380 in Cryo mode using and SiO2 mask (SF6 & O2)<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I’ve been getting what I believe to be a “Black silicon” artifact, and would either like to NOT get it or remove it.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">If anyone has thoughts or could point me in the right direction , I’d appreciate it.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Best Regards<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Tom<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thomas S. Ferraguto<u></u><u></u></p>
<p class="MsoNormal">Saab ETIC Nanofabrication Laboratory Director<u></u><u></u></p>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><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></span></font><p class="MsoNormal"><span style="color:black">___________________________________________________<u></u><u></u></span></p><p class="MsoNormal"><span style="color:black">N.P. Vamsi Krishna, PhD</span><u></u></p><p class="MsoNormal"><span style="font-variant:inherit;color:black;font-family:Arial,sans-serif;font-size:10pt;margin:0px;padding:0px;border:0px;font-stretch:inherit;line-height:inherit;vertical-align:baseline"><i><b>Staff Scientist</b></i></span><br></p><p style="margin:0in 0in 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif;color:rgb(32,31,30)"><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:10pt;line-height:inherit;font-family:Arial,sans-serif;vertical-align:baseline;color:maroon;background-image:initial;background-position:initial;background-repeat:initial">Pritzker School of Molecular Engineering, </span><span style="margin:0px;padding:0px;border:0px;font-variant:inherit;font-stretch:inherit;font-size:10pt;line-height:inherit;font-family:Arial,sans-serif;vertical-align:baseline;color:black"><i><b>The University of Chicago </b></i></span></p><p style="margin:0in 0in 0.0001pt"><span style="color:black;font-family:Arial,sans-serif;font-size:10pt;margin:0px;padding:0px;border:0px;font-variant:inherit;font-stretch:inherit;line-height:inherit;vertical-align:baseline"><i><b>Resident </b></i></span><font color="#000000" face="Arial, sans-serif"><span style="font-size:13.3333px"><b><i>Associate</i></b></span></font></p><p style="margin:0in 0in 0.0001pt;font-size:11pt;font-family:Calibri,sans-serif;color:rgb(32,31,30)"><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:10pt;line-height:inherit;font-family:Arial,sans-serif;vertical-align:baseline;color:black"><span style="color:rgb(128,0,0);font-size:13.3333px">Center for Nanoscale Materials, </span></span><b style="font-size:13.3333px;color:black;font-family:Arial,sans-serif"><i>Argonne National Laboratory </i></b></p><p style="margin:0in 0in 0.0001pt;color:rgb(32,31,30)"><font face="Arial, sans-serif"><span style="font-size:13.3333px">Phone: 1 (331) 757-8565</span></font></p></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div>