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<p class="MsoNormal">Hi Sa’ad,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We regularly use SPR220 or S1813 as masks for III-V etches in BCl3-based ICP etches. I wouldn’t characterize them as an “etch stop” as they do etch to some degree. The selectivity is generally fairly good with III-V compounds however.
<o:p></o:p></p>
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<p class="MsoNormal">In our PlasmaTherm 770 ICP tool we typically see resist etch rates of ~30nm/min in a BCl3/Ar plasma. Depending on the III-V material we are etching this leads to a selectivity of at least 2.5:1, but often much better. The actual etch rates
you see will vary depending on your equipment and etch conditions of course. Selectivity will likely be even better with low or no Ar flow if your devices can be etched in pure BCl3.<o:p></o:p></p>
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<p class="MsoNormal">-Dave<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#BB0000;background:white">Dave Hollingshead </span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333"><br>
<span style="background:white">Senior Research Associate – Nanotech West Lab<br>
<b>The Ohio State University</b></span><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333;background:white">Suite 100, 1381 Kinnear Road, Columbus, OH 43212</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333"><br>
<span style="background:white">614.292.1355 Office</span><br>
</span><span style="color:#333333"><a href="mailto:hollingshead.19@osu.edu"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:blue;background:white">hollingshead.19@osu.edu</span></a></span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333;background:white"> </span><span style="color:#333333"><a href="http://osu.edu/"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:blue;background:white">osu.edu</span></a></span><span style="color:#333333"><o:p></o:p></span></p>
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<p class="MsoNormal"><b>From:</b> labnetwork-bounces@mtl.mit.edu <labnetwork-bounces@mtl.mit.edu>
<b>On Behalf Of </b>Sa'ad H<br>
<b>Sent:</b> Monday, April 6, 2020 13:59<br>
<b>To:</b> labnetwork@mtl.mit.edu<br>
<b>Subject:</b> [labnetwork] Etching GaP with PhotoResist as a etch stop<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I'm currently working on a process to etch GaP in BCl3. I know Zep works as an etch stop for BCl3, but I want to move away from Zep so I can use optical litho instead of ebeam. Does anyone know
if standard photoresists (s1805) or SPR-220 (these are just examples) would work as etch stops?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Alternately, are there any hard masks or oxides that anyone could suggest?<o:p></o:p></span></p>
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