[labnetwork] TMAH alternatives

[Hathaway, Malcolm R]

Hello All,

Thanks for all your responses regarding potential replacements for TMAH.

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 TMAH Working Group, so that it can encompass a wide membership, including NNCI member institutions as well as others, including perhaps some industry folks as well.

As we find out more, we'll keep the main Labnetwork apprised of our progress.

So, if you have an interest in furthering this work, or would like to share your findings or recommendations, email me at hathaway at cns.fas.harvard.edu, and I'll put you on the mailing list.

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.

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!

The initial email for the TMAH Group will go out shortly,

Thanks,

Mac Hathaway
Harvard CNS
________________________________
From: Graham Gibson <gibsong at queensu.ca>
Sent: Saturday, June 17, 2023 2:42 PM
To: Hathaway, Malcolm R <hathaway at cns.fas.harvard.edu>; Labnetwork Mailing List <labnetwork at mtl.mit.edu>
Subject: RE: TMAH alternatives


   Hi Mac,



   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.



  Cheers,



Graham Gibson



Operations Manager, NanoFabrication Kingston

Queen’s University

945 Princess Street

Kingston, Ontario, Canada

K7L 0E9

gibsong at queensu.ca<mailto:gibsong at queensu.ca>

www.nanofabkingston.ca<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=>







From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Hathaway, Malcolm R
Sent: Thursday, June 15, 2023 2:20 PM
To: Labnetwork Mailing List <labnetwork at mtl.mit.edu>
Subject: [labnetwork] TMAH alternatives



Hello Labnetworkers,



Has anyone tried one of the TMAH substitutes that have become available?



How do they work?  Are your users satisfied with their results?



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.



Several companies now have safer alternatives available, which we'd like to try out, such as:



 Envure 3330 (Sachem Chemical),



E-Grade THEMAH SLM ((hydroxyethyl) methylammonium hydroxide, from Huntsman Chemical), and



Novo-safe SE-33 (ethyl tri-methy ammonium hydroxide from Transene).



We are particularly interested in using one of these as an HSQ developer, so we can do away with 25% TMAH.



Any experiences, good or bad, will be most welcome.



Thanks,





Mac Hathaway

Senior Process and Systems Engineer

Harvard Center for Nanoscale Systems
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20230623/f9b9d13a/attachment.html>