A rapid thermal process for silicon recycle and refining from cutting kerf-loss slurry waste

Abstract

More than 40% of the high-purity silicon has been wasted as kerf loss during wafer slicing. This waste not only causes the environmental burden, but also increases the cost for silicon wafers. Although Si could be enriched easily to 85wt% from the waste, it was extremely difficult to further increase the purity of over 99wt% due to tiny SiC particles and metallic debris. We proposed a novel rapid thermal process, which was about one hundred times faster than the previous high-temperature treatment, to agglomerate Si in a couple minutes from the pretreated solid powder. With proper conditions, SiC particles and metals could be easily segregated to the surface of Si agglomerates. The high purity Si could be obtained by surface etching, and the best recycle yield was over 70%. The factors, such as temperature, holding time, and the surface oxidation of Si, were further discussed.