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Made In Wisconsin

Sigma-Aldrich adds organometallics production, purification at U.S. site

by Michael McCoy
May 12, 2008 | A version of this story appeared in Volume 86, Issue 19

Credit: SAFC Hitech
A new distillation unit helps SAFC achieve parts-per-trillion purity.
Credit: SAFC Hitech
A new distillation unit helps SAFC achieve parts-per-trillion purity.

SIGMA-ALDRICH'S chemical plant in Sheboygan, Wis., has come a long way since its days as the site of a failed experiment by the makers of Schlitz beer. Today, it is a thriving site where a $9 million clean room just opened to serve the electronics industry.

Joseph Schlitz Brewing built the plant some 25 years ago to produce diethyl pyrocarbonate, a sanitization chemical expected to revolutionize the beer-making process. But according to Frank D. Wicks, president of SAFC, Sigma-Aldrich's fine chemicals division, Schlitz scientists discovered that using the chemical created potentially carcinogenic nitrosamines. The brewer abandoned the program and sold the plant to what was then Sigma Chemical.

Today, the site is home to some 360 Sigma-Aldrich employees who run several chemical plants on behalf of various company businesses. More and more, these employees are serving Wicks's SAFC Hitech electronic materials business.

Although Sigma-Aldrich has long supplied electronics manufacturers with high-purity chemicals, the company stepped up its participation in the industry early last year with the $60 million acquisition of Epichem, a British maker of organometallic compounds for semiconductors. The purchase more than doubled the size of SAFC Hitech to about $70 million in annual sales.

The deal was the brainchild of Geoffrey J. Irvine, SAFC Hitech's director of commercial development and marketing, who holds a Ph.D. in organometallic chemistry from New Zealand's University of Auckland. Since then, according to Irvine and Wicks, SAFC has been working to add production of Epichem materials to the larger reactors it operates in Sheboygan.

Last month, during a tour for reporters of the Sheboygan site organized by SAFC, a new reaction vessel was being readied to produce tetrakis(dimethylamino)hafnium. Known as TDMAH, this organometallic compound is used to create thin films of hafnium oxide in transistors.

In the new clean room there, SAFC can distill TDMAH and other electronic materials made at the site to ultrahigh purity and then analyze and package them before shipment to customers.

Construction was supervised by Xiaohong Chen and Reaves Prater, electronics industry veterans whom Irvine recruited to SAFC in 2005. They previously helped build high-purity facilities in California for the Japanese electronic chemicals manufacturer Tri Chemical Laboratories.

Before entering the clean room, staffers must don a full-body Tyvek "bunny suit," complete with booties, gloves, hairnet, and facemask. They then enter an "air shower" where they are buffeted by jets of air to remove dust and other particles.

To minimize contamination, the floors and walls of the facility are covered with polyvinyl chloride panels. SAFC avoids the use of metal in chairs, desks, and laboratory fixtures to reduce the introduction of trace metals. The result, the company says, is that metal contamination in its products is held to parts per billion or even parts per trillion.

Sheboygan is far from the semiconductor manufacturing centers on the U.S. West Coast and in Asia, but SAFC executives say shipping costs aren't important in an industry where products can sell for thousands of dollars per kilogram. Nonetheless, Irvine says the new clean room can provide a template for Sigma-Aldrich electronic materials facilities planned for South Korea and China.


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