After four years of intensive development, MEMC Electronic Materials has begun mass-producing the world's first polished silicon wafer that is completely free of defects. Called Optia, the substrate comes in 150- and 200-mm sizes. The Missouri-based supplier says its researchers modified existing science in order to make volume production of the pristine substrates cost-effective.

The science of making a polished wafer devoid of defects "has been around for a long time, probably 10 to 20 years," says Brett Avants, the unit's public relations director. It's a science that carried a heavy price tag, however. Researchers at MEMC worked over the past several years on the crystal-pulling process and temperature control to create the patented processes that enabled the company to give the Optia a customer-friendly price, Avants says. "We made a lot of modifications having to do with crystal pulling and cooling."

The wafer has no crystal-originated pits and is free of agglomerated imperfections related to crystal growth either on its surface or throughout its thickness, according to the company. In addition, a patented proprietary thermal treatment called Magic Denuded Zone (MDZ) produces "robust internal gettering protection."

Avants claims that initial customers are already reporting "noticeable and substantial" improvements in yield. The company has approximately 20 customers around the world, which Avants declined to name.

Even though MEMC's costs enable the company to mass-produce the wafers, "we do charge a premium" for the substrates, Avants points out. "Not a huge premium; just a few cents more per square inch per wafer." MEMC sales staff tells customers that the Optia makes a "great test wafer," Avants says, adding, "we don't want to sell them as test wafers, though." But such use would enable chipmakers to eliminate the wafers as a source of contaminated die off the bat, he notes.

The 200-mm Optia costs "a few percent more" than the standard polished 200-mm, says the PR director. Avants says MEMC has a production capacity of "tens of thousands" of Optia wafers per month.