Study on the effects of rotational and heating methods on the melt flow and crystal growth rate in SiC growth systems by the TSSG method

Abstract

The top-seeded solution growth (TSSG) method facilitates the production of large-sized silicon carbide (SiC) single crystals with low defect density. However, the process of growing SiC is intricate, involving multiple physical and chemical interactions such as heat and mass transfer. The closed-system nature of crystal growth presents challenges in monitoring the thermal and flow fields. To elucidate the molten flow dynamics during SiC crystallization and optimize growth rate uniformity via thermal system engineering, this study first validated the numerical simulation methodology through small-scale crystal growth experiments. Subsequently, an orthogonal experimental design was implemented to systematically investigate the effects of the heating configuration, crystal rotation rate, and crucible rotation direction on temperature uniformity, flow field characteristics, crystal growth kinetics, and carbon distribution homogeneity in a large-scale SiC growth system. The results indicate that the centrifugal force generated by the rotation of the crystal and crucible during the growth process has the most significant effect on the flow, followed by the Lorentz force from electromagnetic induction heating, while the buoyancy force caused by temperature gradients has the least effect. The order of factors affecting the average crystal growth rate during the SiC growth process is the heating mode, crystal rotation speed, and crucible rotation speed. However, the effects of these factors on the uniformity of grown crystals exhibit an inverse trend. This study suggests that the most effective combination of factors for achieving the desired outcome would be simultaneous electromagnetic induction and resistive heating, a rotation speed of 30 rpm for the crystal and a rotation speed of −10 rpm for the crucible. These parameters may be combined as [ER, 30, −10].