Influence of Back-Diffusion of Iron Impurity on Lifetime Distribution near the Seed-Crystal Interface in Seed Cast-Grown Monocrystalline Silicon by Numerical Modeling

Abstract

The distribution of minority carrier lifetime near the seed–crystal interface found in seed cast-grown monocrystalline silicon was clarified in this work. The distribution of lifetime first decreases and then increases from a seed to a crystal. Modeling of the temperature- and time-dependent iron diffusion and segregation during crystal growth showed a concentration distribution of an increase followed by a decrease from a seed to a crystal. The consistency between lifetime and iron distribution near the seed–crystal interface indicates that the back-diffusion of iron impurity from silicon melt into the seed at the duration stage before crystal growth is one of the main reasons for lifetime variation near the seed–crystal interface. Therefore, it is essential to reduce the duration time before crystal growth to obtain good-quality monocrystalline silicon.