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<p class="MsoNormal"><span style="font-size:11.0pt">Mario,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I have always found the CRC Handbook of Metal Etchants to be useful. It is a collection of over 50 years’ worth of references to papers that would give some level of data on an etchant mixture and you could
usually find one that indicated some level of selectivity to what you wanted. Often you need to find the original paper to get the full story, but it is a good starting point. I had purchased it years ago, but recently found a copy on the web:
<a href="https://www.vector.umd.edu/images/links/Handbook_of_Metal_Etchants.pdf">
https://www.vector.umd.edu/images/links/Handbook_of_Metal_Etchants.pdf</a>.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;mso-ligatures:standardcontextual">Dan<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-ligatures:standardcontextual"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-ligatures:standardcontextual">Daniel Woodie<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-ligatures:standardcontextual">Director, Micro/Nano Fabrication Center, Princeton Materials Institute<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> labnetwork <labnetwork-bounces@mtl.mit.edu>
<b>On Behalf Of </b>Beaudoin, Mario<br>
<b>Sent:</b> Friday, March 14, 2025 7:15 PM<br>
<b>To:</b> labnetwork@mtl.mit.edu<br>
<b>Subject:</b> [labnetwork] Etching WO3<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Dear Network,<o:p></o:p></p>
<p>I have a big copper sputter target holder on which a WO3 (tungsten tri-oxide) target on it. I'd like to etch away the WO3 and keep the copper. Anyone can recommend some appropriate wet chemistry?<o:p></o:p></p>
<p>Best <o:p></o:p></p>
<p>Mario<o:p></o:p></p>
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