<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body text="#000066" bgcolor="#ffffff">
Hello Mattieu,<br>
IMHO, from a health perspective, TMAH appears far more dangerous
than KOH. We <br>
recently prepared a lab-wide notification concerning TMAH and its
known but often <br>
overlooked dangers based on skin adsorption as opposed to ingestion
as an identified <br>
route of exposure.<br>
<br>
"Materials Safety Bulletin <br>
September 24, 2010<br>
<br>
TMAH: New Hazard Awareness Concerning an Old Chemical<br>
Tetramethylammonium hydroxide (TMAH) is widely used in micro- or
nanofabrication<br>
as an etchant and developer. In MSD, TMAH is typically one of
several ingredients in <br>
commercial etching/stripping mixtures, although it may also be used
as a pure chemical.<br>
<br>
While it has long been known to be very toxic if ingested, recent
industrial experience<br>
indicates that skin exposure may result in serious injury/illness or
even death. Since 2007,<br>
there have been 3 recorded fatalities from skin exposure to TMAH
solutions as dilute as<br>
25%. Two of the recorded fatalities occurred due to heart attack
despite immediate<br>
decontamination and prompt medical care. Thus skin, exposure to
>1% TMAH over a<br>
few percent of the body must be treated as a life-threatening event.
MSDSs may be out of<br>
date and not properly describe this high dermal toxicity.<br>
<br>
When handling this material, the minimum set of personal protective
equipment includes:<br>
safety goggles (not glasses), disposable nitrile gloves, a buttoned
lab coat, leg covering and<br>
closed-toe shoes. The disposable gloves may only provide brief
protection and must be<br>
replaced if they become wetted. More protective gloves are the
Stansolv or Tri-Ionic glove<br>
models sold by MAPA.<br>
<br>
In the event of a splash, contaminated clothing must be removed and
the wetted area<br>
thoroughly washed with soap and water, using the emergency shower if
necessary.<br>
Call 911 and summon emergency medical help.<br>
<br>
You should not handle TMAH containing materials when working alone.<br>
Tri-Ionic clean room gloves provide excellent protection from TMAH
exposure."<br>
<br>
<br>
<pre class="moz-signature" cols="80">David A. Bunzow
User Facilities Program Manager
The Molecular Foundry
Materials Science Division
Lawrence Berkeley National Laboratory
1 Cyclotron Road MS 67-3207
Berkeley, CA 94720
Office: 510-486-4574
FAX: 510-486-7424
Cell: 701-541-2354
</pre>
<br>
On 5/18/2011 9:20 AM, Matthieu Nannini, Dr. wrote:
<blockquote
cite="mid:71E97FE4-1EC5-4997-9DF7-1B8177CF974D@mcgill.ca"
type="cite">
<pre wrap="">Dear all,
Having only one base dedicated bench running TMAH @ 85C I have now to make a choice between TMAH and KOH since new researcher are asking for KOH. Maintaining the 2 chemicals requires resources that I don't have.
Process wise, TMAH is better with oxide masks but KOH is better with SiN masks. KOH also etches faster and nicer.
My questions are in terms of safety: could you share your experiences with KOH vs TMAH in terms of ease of use, safety, etc...
Thanks
-----------------------------------
Matthieu Nannini
McGill Nanotools Microfab
Manager
t: 514 398 3310
c: 514 758 3311
f: 514 398 8434
<a class="moz-txt-link-freetext" href="http://miam2.physics.mcgill.ca/">http://miam2.physics.mcgill.ca/</a>
------------------------------------
_______________________________________________
labnetwork mailing list
<a class="moz-txt-link-abbreviated" href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>
<a class="moz-txt-link-freetext" href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</a>
</pre>
</blockquote>
</body>
</html>