SILICON WAFER

摘要

PURPOSE: To obtain silicon wafer excellent in gettering effect of impurities by keeping fluctuation of interstitial oxygen concentration in silicon wafer prepared from silicon single crystal produced by Czochralski process to a prescribed value or below. CONSTITUTION: The fluctuation of interstitial oxygen concentration is kept to <=0.4ppma (expressed in terms of 1979 ASTM). The fluctuation of the interstitial oxygen concentration is measured by the method shown below. A silicon single crystal rod is roundly cut into several parts and further cut parallel to growing shaft direction to prepare silicon slub having 2 mm thickness and the both sides are chemically polished and scanned by a microstep in the growing axial direction of a sample using a microscopic FTIR in which a microscope is attached to FTIR (Fourier-transform spectrophotometer). Thereby, interstitial oxygen concentration is measured using a peak generated from Si-O bond between interstitial oxygen having 1107cm<-1> and silicon and concentration difference in parts of mount and valley of the peak in the measured value is calculated to provide an index (uniformity of interstitial oxygen concentration) in evaluation of growth stripe of interstitial oxygen.