IBM recycles silicon wafers for solar cell use
By Ann Steffora Mutschler, Senior Editor -- 10/30/2007
To repurpose scrap semiconductor wafers for use in silicon-based solar panel manufacturing, IBM Corp. today detailed a reclamation process that was developed at its Burlington, Vermont manufacturing facility which uses a specialized pattern removal technique.
The reclamation process allows IBM to remove the intellectual property from the wafer surface, making them available either for reuse in internal manufacturing calibration as “monitor wafers” or for sale to the solar cell industry as it is the same silicon material used to produce photovoltaic cells for solar panels, IBM explained.
IBM said it intends to provide details of the process to the semiconductor manufacturing industry. The process is currently in use at the Burlington facility and is also in the process of being implemented at Big Blue’s East Fishkill, N.Y.-based semiconductor manufacturing plant.
Charles Bai, CFO of ReneSola, one of China's fastest growing solar energy companies said one of the challenges facing the solar industry is a severe shortage of silicon, which threatens to stall its rapid growth, which is why the company said it has turned to reclaimed silicon materials sourced primarily from the semiconductor industry to supply the raw material the company needs to manufacture solar panels.
The Semiconductor Industry Association (SIA) estimates that 250,000 wafers are started per day worldwide, and IBM estimates that up to 3.3 percent of these wafers are scrapped, amounting in the course of the year to approximately three million discarded wafers.
Because wafers contain intellectual property, most cannot be sent to outside vendors to reclaim, so they are crushed and sent to landfills, or melted down and resold.
Mike Cadigan, general manager for IBM’s semiconductor solutions business unit noted in a statement that “IBM’s commitment to environmental conservation spans its business, from the repurposing of materials used in semiconductor manufacturing to enabling customers to manage, measure, and run the most power efficient datacenters on the planet,” and that the wafer-to-solar panel program has generated other conservation initiatives in its manufacturing operations.
The company explained that the wafer reclamation process produces monitor wafers from scrap product wafers and generates an overall energy savings of up to 90 percent because repurposing scrap means that IBM no longer has to procure the usual volume of net new wafers to meet manufacturing needs.
When monitors wafers reach end of life they are sold to the solar industry and depending on how a specific solar cell manufacturer chooses to process a batch of reclaimed wafers, they could save between 30 and 90 percent of the energy that they would have needed if they had used a new silicon material source, the company said.
These estimated energy savings translate into an overall reduction of the carbon footprint – defined as the measure of the total amount of carbon dioxide (CO2) and other greenhouse gases emitted over the full life cycle of a product or service -- for both the semiconductor and solar industries, IBM believes.
Further, IBM said the program has resulted in reduced spending on monitor wafers and increased efficiency in its wafer reclaim program. Annual savings last year for IBM’s Burlington site were more $500,000, with the ongoing annual savings this year expected to be nearly $1.5 million. The one-time savings for reclaiming stockpiled wafers is estimated to be more than $1.5 million.
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James Procopio, an IBM chip manufacturing project manager, holds a semiconductor wafer prior to refurbishment and Michelle Bolz, an IBM manufacturing engineer, displays a solar panel. IBM intends to provide details of the new process to the broader semiconductor manufacturing industry. (Source: IBM Corp.)
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