Silicon wafers are used in semiconductor manufacturing. For more than 10 years, TI has worked to recycle its scrap wafers for use in solar panels.

For more than 10 years, TI has been recycling scrap silicon wafers, keeping this material left over from the chipmaking process out of the waste stream.

TI not only rescues scrap silicon that is otherwise destined for the smelter or waste heap, but ensures that the silicon is put to good use, for example in solar panels.

TI's recycled wafers have produced enough solar panels to supply electricity year-round to approximately 1,600 homes. Use of solar panels has helped prevent an estimated 10,900 metric tons of carbon dioxide from being released into the atmosphere, the equivalent to planting half a million trees.

Paul Westbrook, TI's sustainable development manager, said TI recycled 95 percent of its waste in 2010, scrap silicon being one example.

"Scrap silicon is 'upcycled' into a high value product – a solar electric panel which produces renewable power. Interestingly, TI's good silicon is used to make TI chips used in solar inverters, the component that connects the solar electric panel to the power grid," Westbrook said.

Salvaging the silicon
Before scrap wafers are sold to solar panel manufacturers, they are used as "test wafers" to calibrate equipment, fill partial lots in process, and collect environment readings from equipment. When repeated reuse of the wafers makes them too thin or dirty for further use, they can then be sold to the solar panel industry.

The unusable silicon is sent through a wafer pattern and coating removal process that eliminates any circuitry or films, making the remaining silicon a valuable raw material for solar panel fabricators. TI, along with Silfine, a Korean company that purchases scrap silicon from semiconductor manufacturers around the world, cleans and refines the silicon and sells it to solar cell companies.

Silfine has established an operation in Dallas that will be used as the model for similar operations being established near other TI wafer fabs in Freising, Germany; Miho, Hiji, and Aizu Japan; and Chengdu, China.

"Silfine America has worked closely with TI to develop and implement a process that complies with TI security requirements and business practices. These processes also meet TI's expectations for cost recovery and resolution of end of use materials," said Jeff Harte, executive vice president of Silfine America. "We are very optimistic about the start of operations to support TI's Dallas fabs as well as facilities in Germany, Japan and China."

Advancing the green movement
Mike Hayden, TI's silicon purchasing manager, said he wants to eventually see the trash-to-treasure silicon recycling program come full circle. "We would like to achieve an end state where our scrap silicon is turned into solar panels by these solar cell manufacturing companies so we can install them on TI buildings to capture energy from the sun."

Because TI is committed to protecting the environment, keeping scrap silicon out of the landfills and making it available to the solar industry is "just the right thing to do," Hayden said.

While TI's silicon recycling program is geared toward minimizing solid waste and conserving manufacturing energy, the company also follows steps to reduce emissions and manage its water supply by either substituting or recycling water from its manufacturing operations. The company recycles water used in its fabrication processes by feeding it to utility plant cooling towers for heating and cooling purposes.