Evaluation of interstitial oxygen along striations in CZ silicon single crystals with a micro-FTIR mapping system
Growth striations in CZ and MCZ silicon wafers were studied by the striation-etching method, spreading resistance measurements and the micro-FTIR mapping method. Microvariations in oxygen concentration were successfully measured using the micro-FTIR mapping system and the results were in good agreement with other results obtained by etching and resistance measurements. Two kinds of striations were observed in CZ and MCZ wafers with high oxygen concentration: weak striations at regular intervals and strong striations at irregular intervals. It was concluded that the former were related to the microsegregation of dopant impurities caused by remelting of the crystal during growth, while the latter were related to the fluctuation of oxygen concentration in the silicon melt.