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<p>Hi Joe,</p>
<p>Adding Glycerin to an HF solution will reduce the Al etching or
even inhibit it. I learned about this many years ago and do not
have the references handy. But by a quick search I found this:</p>
<p><a class="moz-txt-link-freetext" href="https://gnusha.org/~nmz787/mems/unorganized/wet_etch.pdf">https://gnusha.org/~nmz787/mems/unorganized/wet_etch.pdf</a></p>
<p>Good luck,</p>
<p>Alireza Mesgar</p>
<p>Equipment Engineer<br>
Texas Instruments<br>
</p>
<p> <br>
</p>
<div class="moz-cite-prefix">On 10/26/21 15:48, Maduzia, Joseph
Walter wrote:<br>
</div>
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<p class="MsoNormal">Hello,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Does anyone have any suggestions for mask
materials to protect Al in HF 49% for SiO2 removal in SOI
wafer? The device is SOI, ICP DRIE etched to glass, HF etch to
undercut and free devices, but have Al contact pads and AL is
dep’d first. Typically we use PR as pattern mask, but the Al
is etching behind the PR. In this case the Al is deposited
first, so although order of operations change might help, it’s
not a good option atm.<o:p></o:p></p>
<p class="MsoNormal"><br>
Thank you for any suggestions you might have!<o:p></o:p></p>
<p class="MsoNormal"><b><span
style="color:#13294B;text-transform:uppercase">JOE MADUZIA</span></b><span
style="color:black"><br>
</span><i><span style="color:#13294B">MNMS Laboratory
Specialist</span></i><span style="color:black"><br>
<br>
</span><span style="color:#13294B">The Grainger College of
Engineering</span><span style="color:black"><br>
</span><span style="color:#13294B">Mechanical Science and
Engineering</span><span style="color:black"><br>
<br>
</span><span style="color:#13294B">2239 Sidney Lu Mechanical
Engineering Bldg</span><span style="color:black"><br>
</span><span style="color:#13294B">1206 W. Green</span><span
style="color:black"><br>
</span><span style="color:#13294B">Urbana, IL 61801</span><span
style="color:black"><br>
</span><span style="color:#13294B">217.244.6302 | </span><a
href="mailto:jmaduzi2@illinois.edu" moz-do-not-send="true"><span
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