Material Utilization and Waste Reduction through Kerf Recycling

A major loss of the expensive silicon used in the production of photovoltaic (PV) solar cells occurs at the wafering stage, where as much as 50% of this valuable material ends up as a disposal problem rather than being recycled. The waste results from the use of a loose abrasive used with the multi-wire slurry saws currently used to cut the silicon wafers; this abrasive contaminates the swarf silicon and eliminates the possibility of recycling this silicon. This project will develop technology for recycling the swarf silicon via a fixed diamond abrasive process called Fixed Abrasive Slicing Technology (FAST). In Phase I, silicon was wafered on a FAST machine and the recovered swarf was analyzed. The swarf was simulated in composition, phase, and particle size, and then processed in a silicon furnace to produce solar grade feedstock. In Phase II, the processing technology will be scaled-up to demonstrate a clear path to the commercialization of the fixed diamond abrasive slicing of silicon wafers. Commercial Applications and other Benefits as described by the awardee: Converting to a recyclable slicing technology would eliminate one of the largest waste streams in PV and reduce the costs and environmental impacts of PV by 50% or more. The technology should lead to a $30 million business, which could grow by over a factor of 100 as the industry converted to fixed abrasive wafering