MINIMIZATION OF THERMOELASTIC STRESSES IN CZOCHRALSKI GROWN SILICON - APPLICATION OF THE INTEGRATED SYSTEM MODEL

A quasi-steady-state, integrated system model describing high temperature heat transfer, solidification, and the action of capillarity in the Czochralski crystal growth process for silicon is applied as a design tool to find optimum processing conditions and system configurations. The objective of this analysis is to minimize the thermoelastic stresses generated in the growing crystal as a result of nonuniform cooling. The modifications to the basic CZ heat transfer system that are tested include employing three separately controlled heaters, using a cold sink, and changing the geometrical configuration of the heat shield. The details of the temperature field that is generated for each test configuration gives insight into what other modifications should be made to achieve the desired low thermal gradients in the crystal.