THREE-DIMENSIONAL FLOW OF SILICON MELT IN A ROTATING SHALLOW ANNULAR POOL

摘要

In order to understand the mechanism of the surface patterns on silicon melt in Czochralski furnaces, we conducted a series of unsteady three-dimensional numerical simulations of silicon melt flow in a rotating shallow annular pool in the counter-clockwise direction under micro-gravity. The pool is heated from the outer cylindrical wall and cooled at the bottom of an inner cylinder. The temperature differences between the vertical outer wall and the inner wall are 16 K, 21 K, 26 K and 32 K. Bottom and top surfaces of the melt pool are adiabatic. When the rotation rate is very slow, the hydrothermal waves are dominant in the pool and propagate in a direction opposite to the pool rotation. When the rotation rate exceeds the first critical value, the phase velocity of the hydrothermal waves increases rapidly and its propagating direction becomes same as that of the pool rotation. With much larger rotation rate, the flow becomes an axisymmetric steady flow. Details of the flow and temperature disturbances are discussed and the critical rotation rates are determined.