Global analysis of a small Czochralski furnace with rotating crystal and crucible

Abstract In order to understand the influence of crystal and crucible rotations on the silicon melt flow and oxygen transport in a small Czochralski (Cz) furnace, a set of global numerical simulations, based on the pseudo-steady and axisymmetric laminar flow model, was conducted using the finite-element method. The crystal rotation rates ranged from 0 to 20 rpm and the crucible rotation rates from 0 to −2.5 rpm. The model evaluated the effects of the thermocapillary force on the radial distributions of oxygen concentration and ( V s,n / G n ) at the melt/crystal interface, where V s,n and G n are the crystal pulling rate and temperature gradient in the direction normal to the melt/crystal interface, respectively. Simulation results indicate that the thermocapillary force causes significant changes in the flow pattern and temperature distribution in the melt but gives small effect on the oxygen concentration in the crystal in the case of a small Cz furnace without a gas guide. On the contrary, installation of a gas guide has a significant effect on the flow fields and the oxygen concentration in the grown crystal.