THE EFFECT OF INTERFACE SHAPE ON ANISOTROPIC THERMAL-STRESS OF BULK SINGLE-CRYSTAL DURING CZOCHRALSKI GROWTH

Both three-dimensional nonlinear anisotropic thermoelastic and two-dim ensional nonlinear heat conduction finite element programs, which take into consideration the effects of the shape of the solid-liquid inter face, elastic anisotropy and temperature-dependent material properties , were developed and implemented in this article to calculate the dist ributions of the temperature and the thermal stress in bulk single cry stals during Czochralski growth. Thermal stress analyses of a GaAs bul k single crystal were carried out for the general form and, therefore, could be performed in an arbitrary pulling direction. However, only t he results in the cases of the [001] and [111], which are of practical significance, were studied in this article. The influence of the elas tic anisotropy and the shape of the solid-liquid interface; modeled as parabolic, upon the distributions of temperature, stress and the disl ocation density parameter were investigated and discussed.