Crystal Growth of Silicon Carbide: Evaluation and Modeling

Abstract

Silicon carbide ingots were grown by a sublimation method, also called the modified Lely method. The modeling and simulation of heat and mass transfer during the growth of single crystals and the characterization tools used, mainly X-ray imaging, polarized light microscopy, and Raman spectroscopy imaging, are described in this paper. These are powerful tools for a better understanding of the process and for its optimization. The influence of pressure and geometry on the crystal shape, the growth rate, and the enlargement process was investigated. X-ray topography on as-grown ingots showed the influence of seed characteristics such as seed polarity or structural quality on the stabilization of the polytype and on defect propagation. The occurrence of macro defects and micro defects was related to the thermal field by using thermodynamic modeling. Finally, the stress and the densities of structural defects in the wafer were evaluated by X-ray topography , birefringence imaging, and Raman spectroscopy. The relations between the stress, the distribution of defects, and the thermal gradient in the crucible have been quantified by simplified thermoeleastic considerations.