7 - Silicon Carbide Crystals — Part II: Process Physics and Modeling

Abstract

The vapor transport growth of silicon carbide crystals involves induction heating, electromagnetic field, radiative and conductive heat transfer, sublimation and condensation, chemical reaction, stoichiometry, mass transport, thermal stresses, as well as defect and micropipe generation and propagation. The irregular geometry, complicated boundary conditions, and lack of information on thermophysical properties at high temperatures make this process very difficult to understand, model, and control. As defects and micropipes in silicon carbide (SiC) crystals are directly related to transport phenomena, it is critical to develop better understanding of these phenomena to grow crystals of higher quality and larger size and to examine the effects of various parameters individually and collectively. Modeling and simulation has been widely used in industry to optimize the system geometry and growth processes. The components of the growth system can be redesigned in order to grow crystals with low thermal stresses. Industry has used the model to design the furnace for growing 50–100 mm diameter SiC crystals. It is observed that a convex shape of interface can ensure an outward growth to expand a small size seed into a large diameter crystal.