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Mario,</div>
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Jing brings up a good point. I do not permit 25% TMAH in my facility; while it is indeed a strong base, it is also a contact poison (and so are 2.5% developers). </div>
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Note that this is not something that shows in the SDS for some developers. </div>
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I require users to wear chemical gloves/apron/shield and safety glasses during manual development. The attached paper should provide some insight. </div>
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Regards,</div>
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Jeff</div>
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<b>From: </b>labnetwork <labnetwork-bounces@mtl.mit.edu> on behalf of Jing Guo <jg78@rice.edu><br>
<b>Date: </b>Tuesday, April 21, 2026 at 19:47<br>
<b>To: </b>Beaudoin, Mario <beaudoin@physics.ubc.ca><br>
<b>Cc: </b>labnetwork@mtl.mit.edu <labnetwork@mtl.mit.edu><br>
<b>Subject: </b>Re: [labnetwork] Cleanroom gowning to handle resists and developers<br>
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<div class="ms-outlook-mobile-reference-message skipProofing">Hi Mario, </div>
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<div class="ms-outlook-mobile-reference-message skipProofing">For most photolithography spin-coating and development processes, we don’t request extra PPE. Generally users are wearing cleanroom coveralls, nitrile gloves and safety goggles. Most positive MIF
developers are TMAH (2.1~2.3% weight concentration) solutions. </div>
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<div class="ms-outlook-mobile-reference-message skipProofing">But we will always bring up the high concentration TMAH, 25% TMAH (Aqueous solution) to attention. Some users use 25% TMAH as a HSQ ebeam resist developer. 25% TMAH is a strong base which could cause
severe caustic burns. Users <b>must </b>wear a secondary PPE to use 25% TMAH including Tychem 4000 Apron, double/triple long sleeve nitrile gloves (disposable) , safety goggles plus face shield and silver shield chemical resistant boot covers.
<b>Photolitho users should never touch TMAH 25% bottles even they are also stored in the general base cabinets. </b></div>
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<div class="ms-outlook-mobile-reference-message skipProofing">We set up secondary PPE stations beside our benches. HF bench has its own. Users can always protect themselves when necessary. </div>
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<div class="ms-outlook-mobile-reference-message skipProofing">Best,</div>
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<div class="ms-outlook-mobile-reference-message skipProofing">Jing </div>
<div class="ms-outlook-mobile-reference-message skipProofing">---------------------------------------<br>
Jing Guo Ph.D.<br>
Cleanroom Manager/Research Scientist<br>
SEA Cleanroom (SST 017)<br>
Rice University<br>
Houston, TX <br>
jeanne.guo@rice.edu<br>
713-348-8227</div>
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<div class="ms-outlook-mobile-reference-message skipProofing">On Apr 20, 2026, at 5:37 PM, Beaudoin, Mario <beaudoin@physics.ubc.ca> wrote:</div>
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<p class="ms-outlook-mobile-reference-message skipProofing">Dear Network,</p>
<p class="ms-outlook-mobile-reference-message skipProofing">In our cleanrooms, we handle photoresists and developers with common cleanroom apparel (coveralls, hoods, nitrile gloves and eye protection). Do any of you require extra special aprons, full visors
and 4H gloves? I've worked in many cleanrooms and never encountered such requirements.</p>
<p class="ms-outlook-mobile-reference-message skipProofing">Mario</p>
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<Mario Beaudoin SBQMI sig 3.jpg></div>
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