Subject: [DCHAS-L] Hexachlorosilane
Date: Wed, 21 Jun 2017 07:00:31 -0700
Reply-To: neal**At_Symbol_Here**
Message-ID: 000601d2ea96$bf38f260$3daad720$**At_Symbol_Here**

(I apologize if this is a re-post)
This is posted for our colleague Eugene Ngai

Hexachlorodisilane (HCDS) is finding increasing use in PECVD
and ALD processes. Unfortunately it has a tendency to form a
solid crystalline deposit that can flash/explode when
disturbed (Popping Gel). Numerous incidents have occurred in
user and supplier systems. In some cases fires and
explosions have occurred when the systems have been taken
apart for maintenance. Vacuum pumps routinely autoignite
when taken apart. Recently in 2014, a deadly explosion
occurred in the high-purity polycrystalline silicon
manufacturing facility at the Yokkaichi Plant of Mitsubishi
Materials Corporation (MMC), Japan, resulting in 5
fatalities and 13 injuries. The Popping Gel ignited when the
heat exchanger was opened and the gel disturbed. A second
explosion occurred during the government investigation.

I am spearheading a study on how these are formed and what
they are, ?Characterization of Energetic Deposits from
Hexachlorodisilane?. This is currently underway (Phase 1),
funded by a supplier to better understand how it is formed
and how to safely dispose of it when it is formed. Phase 2
to be funded by 5+ users and suppliers will investigate
other aspects of the formation.

Please advise Eugene eugene_ngai**At_Symbol_Here** if you have an
interest or have had incidents

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