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<p class="MsoNormal">Hi everyone,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have a strange problem that I need some help with. We have an Ulvac NE-550 RIE system with an electrostatic chuck. The wafer is a double sided polish with 1um of SiO2. One side has an AZ4620 resist pattern 8um thick to etch the 1um of
oxide. Because the process runs hot we break the etch into 9 different steps and move into the LL after every step. On the polished side that is down on the ESC check we have craters on the surface that look like a lightning strike or meteor strike, this is
fairly deep several microns.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have attached a photo of the damage. Have any of you seen anything like this? I need to fix the issue because the side that is down ends up being the frontside of the wafer and that is a killer defect. We think the oxide is charging and
when the lift pins come up (at ground potential) we get a discharge.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Rick<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Draper Laboratory<o:p></o:p></p>
<p class="MsoNormal">Principal Member of the Technical Staff<o:p></o:p></p>
<p class="MsoNormal">Group Leader Microfabrication Operations<o:p></o:p></p>
<p class="MsoNormal">555 Technology Square<o:p></o:p></p>
<p class="MsoNormal">Cambridge Ma, 02139-3563<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">www.draper.com<o:p></o:p></p>
<p class="MsoNormal">rmorrison@draper.com<o:p></o:p></p>
<p class="MsoNormal">W 617-258-3420<o:p></o:p></p>
<p class="MsoNormal">C 508-930-3461<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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