Global simulation of silicon crystal Czochralski growth II. Characteristics of mass transfer
硅单晶Czochralski法生长全局数值模拟II．质量传递特性

In order to understand the basic characteristics of oxygen transport, a set of global analyses for mass transfer in small Czochralski (Cz) furnaces was carried out using the finite-element method. It was assumed that the flow was axisymmetric stable laminar in both the melt and the gas, and the melt was incompressible. The results reveal that in these small Cz furnaces the oxygen concentration in the crystal is mainly dependent on the melt flow pattern and gas phase mass transfer rate. The dissolved Oxygen in the melt is evaporated into the gas phase through the melt/gas interface and the oxygen-concentration on the surface is low. The low-oxygen-concentration melt on the surface is effectively carried to the area below the melt/crystal interface by the Marangoni effect, which reduces the oxygen concentration in the crystal. By installing a gas guide in the hot zone, the mass transfer coefficient is significantly enhanced and the melt flow pattern is changed.