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<font face="Times New Roman, Times, serif">Mario,<br>
<br>
Just a guess here: You can try dilute HF, say 3-5 % v/v at room
temperature. Copper is passivated by the formation of a fluoride. </font><br>
<br>
<div class="moz-cite-prefix">On 3/14/2025 4:14 PM, Beaudoin, Mario
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:16283bb1-f0c4-4cd1-a509-54e9dae5add8@physics.ubc.ca">
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<p>Dear Network,</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?</p>
<p>Best <br>
</p>
<p>Mario<br>
</p>
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<pre class="moz-signature" cols="72">--
Prashant Srinivasan
Teaching Cleanroom Engineer
Electrical & Computer Engineering
University of California, Santa Barbara
Santa Barbara, California 93106
<a class="moz-txt-link-freetext" href="https://www.ece.ucsb.edu/department-resources/electronics-shop/tcr">https://www.ece.ucsb.edu/department-resources/electronics-shop/tcr</a></pre>
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