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Very deep indeed.
<div>You would need a thick metal mask (Al or Ni) to do that (my experience with a PlasmaTherm ICP etch tool).</div>
<div>Perhaps laser cutting or ultrasonic? Or just a dicing saw.</div>
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<div>Jim Beall</div>
<div>NIST Boulder Microfab<br>
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<div>On Jan 18, 2023, at 5:05 PM, Howard Northfield <Howard.Northfield@uottawa.ca> wrote:</div>
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That's a very deep etch.</span></div>
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<span class="ContentPasted1" style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; background-color: rgb(255, 255, 255);">Regarding dry etching:<br>
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<span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; background-color: rgb(255, 255, 255);">I have recently done etch tests on PEVCD SiO2 with a SAMCO 10NR RIE:</span></div>
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<span class="ContentPasted0" style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; background-color: rgb(255, 255, 255);">- 50W, 80sccm CF4, 16sccm O2, 3.0Pa: ~21nm/min
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<div class="ContentPasted0">- 25W, 25sccm SF6, 10sccm O2, 3.0Pa: ~7nm/min</div>
<div class="ContentPasted0">- 50W, 25sccm SF6, 10sccm O2, 3.0Pa: ~19nm/min</div>
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... yes for 500um that would be around a 417 hour etch .... not feasible/realistic.<br>
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<span class="ContentPasted0" style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; background-color: rgb(255, 255, 255);">So you can probably rule out these etch recipes.</span></div>
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<span class="ContentPasted0 ContentPasted2" style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; background-color: rgb(255, 255, 255);">Regarding wet etching, generally I find it very hard to control and mask under-cut is significant.<br class="ContentPasted2">
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<span class="ContentPasted0 ContentPasted2 ContentPasted3" style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; background-color: rgb(255, 255, 255);">Howard Northfield
<div class="ContentPasted3">Research Associate</div>
<div class="ContentPasted3">Advanced Research Complex (ARC)</div>
University of Ottawa<br>
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<font face="Calibri, sans-serif" style="font-size: 11pt;"><b>From:</b><span class="Apple-converted-space"> </span>labnetwork <<a href="mailto:labnetwork-bounces@mtl.mit.edu">labnetwork-bounces@mtl.mit.edu</a>> on behalf of Ningzhi Xie <<a href="mailto:nzxie@uw.edu">nzxie@uw.edu</a>><br>
<b>Sent:</b><span class="Apple-converted-space"> </span>Wednesday, January 18, 2023 4:23 PM<br>
<b>To:</b><span class="Apple-converted-space"> </span><a href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a><span class="Apple-converted-space"> </span><<a href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>><br>
<b>Subject:</b><span class="Apple-converted-space"> </span>[labnetwork] Deep anisotropic etching of SiO2</font>
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<div style="font-size: 9pt; font-family: calibri; color: rgb(255, 66, 51);"><b>Attention : courriel externe | external email</b></div>
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<div dir="ltr"> Dear college,
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<div>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).</div>
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<div>Thank you very much.</div>
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<div dir="ltr">Best regards,
<div>Ningzhi Xie</div>
<div>Department of Electrical and Computer Engineering</div>
<div>University of Washington</div>
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