| 摘要 |
PURPOSE: To obtain a high-purity polycrystal silicon having the surface which is not contaminated by iron atom though it is a mechanical workpiece. CONSTITUTION: This polycrystal silicon has <=10000atom/μm<2> iron atom concentration of the surface per unit surface area. The polycrystal silicon is produced by successively cleaning a polycrystal silicon with aqua regia, water and hydrofluoric acid, e.g. aqua regia having 1:1 volume ratio of nitric acid to hydrochloric acid, water and 1-20wt.% of hydrofluoric acid in this order.
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