Precipitation and redistribution of oxygen in Czochralski-grown silicon

Abstract

Thermally induced oxygen precipitation and redistribution phenomena in Czochralski-grown silicon crystals are investigated by means of transmission electron microscopy and differential-infrared absorption (DIR). In order to investigate the role of thermal history and the oxygen supersaturated condition for oxygen precipitation, a two-step annealing process is adopted. Evident existence of SiO2 (crystobalite) is observed in as-grown crystals by DIR at 1225 cm−1. As a result, it is ascertained that oxygen precipitation does not occur by homogeneous nucleation depending on the ratio of supersaturated oxygen but occurs by heterogeneous nucleation. A model of a grown-in nucleus for oxygen precipitation by heat treatment is also proposed.