Influence of oxygen precipitation along dislocations on the strength of silicon crystals

The mechanical strength of dislocated crystals of Czochralski-grown silicon as influenced by the precipitation of oxygen impurities on dislocations was investigated. The yield strength increases during the early stage of precipitation of silicon oxide, but decreases remarkably during the later stage of precipitation. The enhancement of the yield strength is brought about by the immobilization of dislocations due to locking by closely aligned precipitates along the dislocations during the early stage of precipitation. The locking effect diminishes during the late stage when precipitates on dislocations coalesce with the generation of free portions of dislocations with large separation.