METHOD OF RECYCLING SCRAP WAFER AND PROCESS FOR PRODUCING SILICON SUBSTRATE FOR SOLAR CELL

摘要

A method of recycling scrap silicon wafers in which a waste of resources in recycling is diminished and silicon wafers can be formed into a regenerated ingot without being dissolved. The regenerated ingot enables the silicon to be reused in a state akin to the single-crystal state. Also provided is a process for producing a silicon substrate for solar cells. The method of scrap wafer recycling comprises in the following order: a film removal step (S3) in which films formed on scrap wafers (W) are removed; a mirror polishing step (S5) in which the front and back sides of each scrap wafer from which the films have been removed are mirror-polished; an arrangement step (S8) in which the scrap wafers which have been mirror-polished are superposed so as to be uniform in crystallographic direction and are cylindrically arranged; and a heating step (S9) in which the scrap wafers arranged cylindrically are placed in a heating oven and heated at a temperature in the range of 400-1,350°C to thereby bond the scrap wafers to each other by diffusion to thereby produce a regenerated ingot (IG).