<div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">Hi Pallavi,</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">If all of a sudden you are seeing grass in all the recipes (without any open chamber repairs):</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">1. Do long oxygen clean: This will help you in removing excess polymer on the chuck or any metal contamination in the chamber. Observe the plasma for any sparks or fluctuations in Vpp or DcBias. </div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">2. Use your standard recipe and try increasing platen temperature. Inspect your platen temperature.</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">3. Check the condition of ESC for any black spots or particles (open chamber).</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">If there is any change in the chamber conditions like recently AMC done or ESC replacement? The picture below might help you tuning the recipe. <br></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">1. First I would try increasing the platen temperature (In most of the cases this will work)</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">2. Then try to reduce polymer flow. If there is a change in profile, increase it. </div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066"><div><img src="cid:ii_kd51yz2e0" alt="Screen Shot 2020-07-27 at 4.47.23 PM.png" width="490" height="408"><br></div></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">Hope this helps. </div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#000066">Thanks & Regards,</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 Mon, Jul 27, 2020 at 2:53 PM Pallavi Sharma <<a href="mailto:pnsharma@unm.edu" target="_blank">pnsharma@unm.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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<span>Hello all,</span></div>
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<span>I am having problem with anisotropic etching of silicon by Deep Reactive ion etch. Grass or black silicon is the issue all the time, attaching some of the SEM pictures of the sample. Every recipe I tried to fine tune result in grass formation, even as
the process initiates in tool wafer surface starts to turn brown and ultimately black. I tried varying SF6 gas flow, Bias power, Substrate temperature but every time I see is highly dense grass with no clean surface. </span></div>
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<span>Any help will be greatly appreciated.</span></div>
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<span>Thank you,<br>
Pallavi</span></div>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr"><div dir="ltr"><div><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="color:rgb(32,31,30);font-family:Arial,sans-serif;font-size:13.3333px">Postdoctoral Fellow</span></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;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></div>