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Hi Linda,<br>
<br>
At Harvard CNS we only allow 25% TMAH usage in the dedicated
"strong" acid/base benches, with full PPE at all times (extra
chemical gloves, poly chemical apron with sleeves, faceshield,
safety glasses). We are trying to phase it out. For Si etching, we
encourage the use of KOH instead.<br>
<br>
For 2.5-3.0% (i.e. MIF developer), we are not as rigorous, but we
are reviewing that PPE as well.<br>
<br>
For those who are not familiar with TMAH, it has been recently
re-appraised by groups in Taiwan, IBM, and elsewhere, in light of
the discovery that, in a small sample of people who had exposures to
either 25% and 3% TMAH, 3 out of the 4 exposed to 25% TMAH died, one
of whom reportedly got under a safety shower within 30 seconds (he
still died.). The minimum exposed area in the review was, I
believe, 7.5% body area exposed. Toxicity appears unrelated to, but
exacerbated by the extreme caustic nature of the material. The
current bottom line is 25% TMAH appears to be a potent neurotoxin,
and there is no known antidote. The reason this is a problem is
that TMAH is the active ingredient in most "metal-ion-free"
developers, although this is only in the ~3% concentration, where
neurotoxicity is much reduced, and manifests itself in lessor
symptoms like tingling, blurred vision, etc. 25% TMAH is used in Si
etching, and for some E-beam resist purposes, as a developer for
HSQ.<br>
<br>
<br>
Mac Hathaway<br>
Safety Officer<br>
Harvard CNS<br>
<br>
<br>
On 9/4/2012 2:06 AM, Linda Macks wrote:
<blockquote
cite="mid:E1BB1BEF080F69459C0EC180B055285738E00BD0@INFPWXM012.ad.unsw.edu.au"
type="cite">
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<p>Hi all,</p>
<p> </p>
<p>We are currently reviewing our processes using TMAH, and I
would be grateful for any feedback re. safety controls or
substitute chemicals, particularly for Si etching involving
25% concentration TMAH.</p>
<p> </p>
<p>Many thanks,</p>
<p> </p>
<p>Linda</p>
<p> </p>
<p> </p>
<div><font face="Tahoma" size="2">
<div><font face="tahoma" size="2"><strong>Dr Linda Macks</strong></font></div>
<div><font face="tahoma" size="2">Facility Manager,
ANFF-NSW</font></div>
<div><font face="tahoma" size="2">Australian National
Fabrication Facility</font></div>
<div> </div>
<div><font face="tahoma">School of Electrical Engineering
& Telecommunications</font></div>
<div><font face="tahoma">University of New South Wales</font></div>
<div><font face="tahoma">UNSW Sydney NSW 2052</font></div>
<div><font face="tahoma">Australia</font></div>
<div> </div>
<div><font face="tahoma">Phone: +61 (2) 9385 7845</font></div>
<div><font face="tahoma">Fax: +61(2) 9385 5114</font></div>
<div><font face="tahoma">Email: <a moz-do-not-send="true"
href="mailto:linda.macks@unsw.edu.au">linda.macks@unsw.edu.au</a></font></div>
<div> </div>
</font></div>
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</blockquote>
<br>
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