Silicon melt convection in large size Czochralski crucibles

Abstract

The melt flow in large diameter crucibles during the growth of silicon (Si) single crystals of 300 mm diameter is characterized by turbulent large-scale velocity and temperature fluctuations. Strong efforts of the crystal growth industry are dedicated to the control of the interface shape and the related point defect distribution in the crystal, of the oxygen and particle transport in the melt, of the crucible overheating and of the conditions for dislocation free growth. Static and time-dependent electromagnetic fields offer new possibilities to meet the continuously increasing demands on crystal quality and yield improvement. Numerical simulation helps to investigate a wide range of possible process conditions, and to reduce experimental costs and time to market significantly. Depending on the required accuracy and available computation resources, two-dimensional (2D) or three-dimensional (3D) models are used. Temperature measurements in the melt, carried out during crystal growth and in model facilities, provide data for the verification of the numerical models, for direct process optimization and for a better understanding of the heat and mass transport behavior.