Carbon Inclusions in the Growth of an 8-inch 4H-SiC Crystal

Abstract

During the physical vapor transport (PVT) growth of a 4H silicon carbide (4H-SiC) crystal carbon inclusion may be incorporated, which substantially degrade the performance of devices based on 4H-SiC. In this work, carbon inclusions in the growth of an 8-inch 4H-SiC crystal are investigated. The distribution and size of carbon inclusions within the crystal are systematically characterized. Numerical simulations are employed to analyze the effects of drag, thermophoretic, and gravitational forces on the motion of graphite particles, from which carbon inclusions originate. It is found that the critical gas velocity required at the powder surface to suppress carbon inclusions of a given size and determination of the critical size for graphite particles detach from the powder surface under specific conditions. The calculated critical carbon inclusions size agrees well with experimental measurements. Studies have shown that increasing pressure and reducing axial temperature difference can effectively reduce the size of carbon inclusions. This study provides valuable insights for controlling and reducing the size of carbon inclusions in SiC crystals during their growth.