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<p class="MsoNormal">Hello Ningzhi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">It is extremely hard to finish this process by using the etch machines. I have some descriptions of SiO2 etching. They can be found in my book. Please see the link below:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="https://www.amazon.com/Semiconductor-Microchips-Fabrication-Practical-Manufacturing/dp/1119867789/ref=sr_1_1?crid=2VVS3G261R22A&keywords=yaguang+lian&qid=1674147165&sprefix=%2Caps%2C293&sr=8-1">Semiconductor Microchips and Fabrication:
A Practical Guide to Theory and Manufacturing: Lian, Yaguang: 9781119867784: Amazon.com: Books</a><o:p></o:p></p>
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<p class="MsoNormal">Good luck,<o:p></o:p></p>
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<p class="MsoNormal">Yaguang Lian<o:p></o:p></p>
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<p class="MsoNormal"><b>From:</b> labnetwork <labnetwork-bounces@mtl.mit.edu> <b>
On Behalf Of </b>Ningzhi Xie<br>
<b>Sent:</b> Wednesday, January 18, 2023 3:23 PM<br>
<b>To:</b> labnetwork@mtl.mit.edu<br>
<b>Subject:</b> [labnetwork] Deep anisotropic etching of SiO2<o:p></o:p></p>
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<p class="MsoNormal"> Dear college,<o:p></o:p></p>
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<p class="MsoNormal">We want to perform a highly anisotropic, very deep (~500um) etching of SiO2 with a vertical side wall. On top of the SiO2 is nanostructures protected by photoresist. The etch depth needs to be controlled with a precision of 20% (we are
thinking of using another material as the substrate underneath the SiO2 layer, which acts as an etch-stopper). The structure and dimensions are shown in the attached image. It would be very helpful if anyone has any idea of this kind of etching (either dry
and wet chemical etch is fine).<o:p></o:p></p>
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<p class="MsoNormal">Thank you very much.<o:p></o:p></p>
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<p class="MsoNormal">Best regards,<o:p></o:p></p>
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<p class="MsoNormal">Ningzhi Xie<o:p></o:p></p>
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<p class="MsoNormal">Department of Electrical and Computer Engineering<o:p></o:p></p>
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<p class="MsoNormal">University of Washington<o:p></o:p></p>
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