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IBM Finds Greener Way To Recycle Silicon

IBM Corp. says it has developed a greener method for recycling precious silicon that is wasted during computer chip manufacturing.

For microprocessors and other computer chips to be made, discs of silicon known as wafers get circuitry imprinted on them and then are cut into hundreds of tiny pieces that become the chips. Because chips have to be essentially flawless, imperfect portions or even the entire wafers sometimes get discarded.

It has been possible to salvage that silicon. Some gets resold to the solar-panel industry, while other pieces get reused as "monitors," the wafers that are fed into semiconductor assembly lines for test purposes.

Often, however, recyclers use acidic chemicals to erase the circuitry from wafers. IBM had been sandblasting its wafers to be sure no trade secrets on the wafers got out.

Now IBM engineers have developed a process for removing the circuitry with an abrasive pad and water, which saves money and leaves the silicon in better shape for reuse. IBM, which makes chips for server computers, video game consoles and other electronics, has been using the process at its chip facility in Essex Junction, Vt., and plans to do so at its plant in East Fishkill, N.Y.

Eric White, one of the engineers behind the process, said it would let IBM get five or six monitor wafers out of one that otherwise would be scrapped. By extending the life of the silicon, IBM believes it will save about $1.5 million a year and leave more of the material available for the solar industry, where supplies have been tight.

Analyst Richard Doherty of the Envisioneering Group said he was unaware of a similar development elsewhere. And while the cost benefits appear small, he said they could matter given the thin margins in the semiconductor industry.

"In today's world, anything that gives you a 1, 2, 3, 4, 5 percent improvement is a real breakthrough," he said.