A Commercial-Simulator-Based Numerical-Analysis Methodology for 4H-SiC Power Devices Formed on Misoriented (0001) Substrates

A commercial-simulator-based numerical-analysis methodology for 4H-SiC power devices formed on misoriented (0001) substrates is proposed and applied for analyzing avalanche breakdown of floating-field-ring-terminated p-n diodes. Due to the inexpedience of a fixed orientation of the (0001) surface in current commercial device simulators, 4H-SiC (0001) surface is etched to form a miscut to separate the known effects of asymmetric nature of impact ionization and asymmetric aluminum concentration contours. 2-D process simulation of etching a 4H-SiC (0001) surface to expose a sloped surface, patterning the sloped surface with a mask, vertically implanting aluminum ions into the masked surface, removing the mask, and forming electrodes and a SiO₂ passivation film was carried out. This process simulation revealed asymmetric lateral straggling of implanted aluminum acceptors. The subsequent device simulation, which assumed fixed charge at the SiO₂/4H-SiC interface, revealed asymmetric avalanche breakdown voltage in the misoriented direction and the opposite direction. This asymmetric breakdown qualitatively explains the previously reported nonuniform luminescence at breakdown. The proposed methodology is considered to be applicable to other power devices with other termination structures formed on misoriented 4H-SiC (0001) substrates.