Numerical investigation of impact of crystal diameter fluctuations on intrinsic point defects distribution in Si crystal grown by Czochralski method

Abstract

Intrinsic point defects distribution is primarily controlled by the crystal pulling rate and temperature gradient directly at growth interface in silicon crystals grown using the Czochralski (Cz) method. The fluctuation in crystal diameter during the Cz process is one of the primary features associated with the temporal variation in growth process parameters, such as the pulling rate and heater power in the growth system, and which is expected to affect the thermal stress, defects, and dopant incorporation in a growing crystal. In this study, we numerically investigated the effect of temporal variation in crystal diameter on the intrinsic point defects distribution in a silicon crystal grown using the Cz method. The point defect dynamics in the crystal were numerically evaluated within a two-dimensional axisymmetric unsteady global heat and mass transport model for dynamically pulled silicon crystals, considering the shape of the crystal and diameter variation. Unsteady numerical simulations showed that the distribution of intrinsic point defects near crystal side surface in a growing silicon crystal significantly depends on the temporal variation in the crystal diameter.