Trace impurity analysis method of silicon in the substrate

摘要

PROBLEM TO BE SOLVED: To execute impurity quantitative analysis accurately and stably without being influenced by boron included in a silicon substrate. SOLUTION: A silicon component is decomposed and sublimated from the silicon substrate 15, and micro impurities included in the substrate 15 is recovered as a residue 18. A mixed acid solution 19 of hydrofluoric acid and nitric acid is added to the residue 18 and the mixture is heated up to 150-220 deg.C, or a mixed acid solution of hydrochloric acid and nitric acid is added thereto and the mixture is heated up to 60-90 deg.C, to thereby decompose and sublimate the residual silicon component included in the residue. Then, a mixed acid 23 solution of hydrofluoric acid, nitric acid and sulfuric acid or a mixed acid solution of hydrochloric acid, nitric acid and sulfuric acid is added thereto and the mixture is heated up to 150-220 deg.C, to thereby decompose and sublimate a boron component included in the residue 18, and the quantitative analysis of the impurities included in the substrate 15 is executed from the residue 24.