Thermally induced microdefects in Czochralski-grown silicon crystals

Abstract

Thermally induced microdefects in Czochralski- grown silicon crystals were investigated by an infrared absorption technique, etching/optical microscopy and transmission electron microscopy. It was fou nd that the microdefect nature varies with the temperature and the density increases exponentially with decreasing annealing temperature. The microdefect formation strongly depends on the thermal history during crystal growth. When the annealing temperature is 800°C or higher, the induced microdefects are caused by the growth of microprecipitates present in the as-grown crystal, but not by the nucleation of oxygen precipitates. When the annealing temperature is as low as 650°C, nuclei of oxygen precipitates can be formed during the annealing. Furthermore, it is concluded that the microprecipitates or nuclei are heterogeneously formed at the sites closely correlated with carbon impurities in the crystal. And, the size distribution of microprecipitates strongly depends on the thermal history.