Epitaxial trench refill of 4H-SiC by chlorinated chemistry

Abstract

Trench epitaxy of 4H-SiC is investigated with the supersaturation of chlorinated chemistry at a growth temperature of 1550 °C. Coupled with a lower growth temperature than has been previously reported, the integrity of the 4H-SiC trenches is retained and minimal rounding effects of H2 annealing prior to growth are observed. The system gives different growth rates of materials on the various crystal faces of the trenches and can be used to improve the refilling process, resulting in the reduced void formation. The addition of excessive levels of HCl can suppress trench epitaxy by reducing the growth rate on the sidewalls of trenches in favor of growth on the surface. The processes demonstrated offer a scalable and reproducible method to fabricate SiC-based superjunction device structures for applications in high voltage power electronics.