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<span style="font-family: Times, "Times New Roman", serif;">Hello All,</span></div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof ContentPasted0">
<br>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">Thanks for all your responses regarding potential replacements for TMAH.</span></div>
<div class="ContentPasted0"><br>
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<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">It appears that some folks have been making their own investigations along these lines, and others are interested in doing so. Since some of this work is on-going, the
idea was suggested that we create an email list where we can coordinate these efforts. This will be called the
</span><span style="font-family: Times, "Times New Roman", serif;"><b>TMAH Working Group</b></span><span style="font-family: Times, "Times New Roman", serif;">, so that it can encompass a wide membership, including NNCI member institutions as well as others,
including perhaps some industry folks as well.</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;"><br>
</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">As we find out more, we'll keep the main Labnetwork apprised of our progress.</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;"><br>
</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">So, if you have an interest in furthering this work, or would like to share your findings or recommendations, email me at hathaway@cns.fas.harvard.edu, and I'll put you
on the mailing list.</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;"><br>
</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">The first notable finding is that Sachem Envure 3330 and Transene SE-33 appear to be the same stuff, i.e. Envure is repackaged in smaller lots for smaller companies and
labs by Transene. As Graham at Queens pointed out, Huntsman seems to develop novolac photoresists reasonably well, with some variation in develop time.</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;"><br>
</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">As mentioned previously, the active ingredient in Envure/Transene is TEMAH (triethyl methyl ammonium hydroxide), while Huntsman uses (hydroxyethyl) methyl ammonium hydroxide.
With regard to safety, we only have, as yet, whatever the manufacturers say. The marketing info suggests one of the Transene products (SE-33) is around 8x less toxic, while the others may be 15x less toxic. Huntsman just says their stuff is "safer". Clearly,
a bit more digging in is called for!</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;"><br>
</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">The initial email for the TMAH Group will go out shortly,
<br>
</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;"><br>
</span></div>
<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">Thanks,</span></div>
<div><br class="ContentPasted0">
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<div class="ContentPasted0"><span style="font-family: Times, "Times New Roman", serif;">Mac Hathaway</span></div>
Harvard CNS<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Graham Gibson <gibsong@queensu.ca><br>
<b>Sent:</b> Saturday, June 17, 2023 2:42 PM<br>
<b>To:</b> Hathaway, Malcolm R <hathaway@cns.fas.harvard.edu>; Labnetwork Mailing List <labnetwork@mtl.mit.edu><br>
<b>Subject:</b> RE: TMAH alternatives</font>
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<p class="x_MsoNormal"><span style=""> Hi Mac,</span></p>
<p class="x_MsoNormal"><span style=""> </span></p>
<p class="x_MsoNormal"><span style=""> I have tried Huntsman’s E-Grade THEMAH as well as another of their products, E-Grade CHOLINE OH, as a developer for standard Novolac photoresists, though not for HSQ (yet). I was pretty happy with their performance in
general, though THEMAH was a bit slow compared to standard TMAH developer.</span></p>
<p class="x_MsoNormal"><span style=""> </span></p>
<p class="x_MsoNormal"><span style=""> Cheers,</span></p>
<p class="x_MsoNormal"> </p>
<p class="x_MsoNormal"><span lang="EN-US">Graham Gibson</span></p>
<p class="x_MsoNormal"><span lang="EN-US"> </span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="font-size:9.0pt">Operations Manager, NanoFabrication Kingston</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="font-size:9.0pt">Queen’s University</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="font-size:9.0pt">945 Princess Street</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="font-size:9.0pt">Kingston, Ontario, Canada</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="font-size:9.0pt">K7L 0E9</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="font-size:9.0pt"><a href="mailto:gibsong@queensu.ca"><span style="color:#0563C1">gibsong@queensu.ca</span></a></span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="font-size:9.0pt"><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__www.nanofabkingston.ca_&d=DwMFAg&c=WO-RGvefibhHBZq3fL85hQ&r=TEMLD8-VsxCGtcVzmvpT5GFNSczskEKHzW6aYlttmIY&m=OsyPDb0Ur6EvRRta3mwKsTIMksoH8kgvJF4CjMEccxyIPWc8KlY75EEy4r7Mkh_e&s=C1IJR82INSIBlZMD65yCnLorWFHWjaFNg1gJ81DnzVI&e="><span style="color:#0563C1">www.nanofabkingston.ca</span></a></span></p>
<p class="x_MsoNormal"> </p>
<p class="x_MsoNormal"><span style=""> </span></p>
<p class="x_MsoNormal"><span style=""> </span></p>
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<p class="x_MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> labnetwork <labnetwork-bounces@mtl.mit.edu>
<b>On Behalf Of </b>Hathaway, Malcolm R<br>
<b>Sent:</b> Thursday, June 15, 2023 2:20 PM<br>
<b>To:</b> Labnetwork Mailing List <labnetwork@mtl.mit.edu><br>
<b>Subject:</b> [labnetwork] TMAH alternatives</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Hello Labnetworkers,</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Has anyone tried one of the TMAH substitutes that have become available?</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">How do they work? Are your users satisfied with their results?</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
</div>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">For background, TMAH (tetramethylammonium hydroxide) is widely used in commercial resist developers (3%) and for HSQ developing (25%). In its 25% concentration, TMAH is a potent contact neurotoxin,
which is fatal roughly 75% of the time, for exposures greater than 7.5% of body area. Nasty stuff.</span></p>
</div>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Several companies now have safer alternatives available, which we'd like to try out, such as:</span></p>
</div>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span><span style="font-size:12.0pt; font-family:"Times New Roman",serif; color:black">Envure 3330</span><span style="font-size:12.0pt; color:black"> (Sachem Chemical),
</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">E-Grade THEMAH SLM ((hydroxyethyl) methylammonium hydroxide, from Huntsman Chemical), and</span></p>
</div>
<div>
<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Novo-safe SE-33 (ethyl tri-methy ammonium hydroxide from Transene).</span></p>
</div>
<div>
<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
</div>
<div>
<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">We are particularly interested in using one of these as an HSQ developer, so we can do away with 25% TMAH.</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Any experiences, good or bad, will be most welcome.
</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Thanks,</span></p>
</div>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Mac Hathaway</span></p>
</div>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Senior Process and Systems Engineer</span></p>
</div>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">Harvard Center for Nanoscale Systems</span></p>
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