Impact of light-element impurities on crystalline defect generation in silicon wafer

In multi-crystalline silicon grown by unidirectional solidification, there are many origins of crystalline defects. In this study, we investigated the effect of light-element impurities on the generation of crystalline imperfections during crystal growth. In order to control the interfusion of impurities, we regulate the Ar gas flow in the atmosphere on the basis of a computer simulation. The etch pit densities in the sample fabricated without and with Ar gas flow control in the atmosphere were 1.5 × 10 ⁵-7.0 × 10 ⁷ and 5.0 × 10 ³-4.0 × 10 ⁵ cm ^-2, respectively. In the sample fabricated without Ar gas flow control, the precipitates consisting of light-elements were observed in the region where the etch pit density markedly increased. In the region with the highest etch pit density, there were small-angle grain boundaries consisting of dislocations. We believed that the precipitates consisting of light-element impurities were the potential origins of small-angle grain boundaries. The light-element impurities should affect the crystalline defect generation induced during crystal growth, and thereby should be controlled.