Impacts of surface C/Si ratio on in-wafer uniformity and defect density of 4H-SiC homo-epitaxial films grown by high-speed wafer rotation vertical CVD

Abstract

Surface C/Si ratio was demonstrated as a useful indicator for the control of in-wafer distribution of thickness and carrier concentration in 4H-SiC homo-epitaxial films on large-diameter wafers. Close investigation of the dependence of growth rate and carrier concentration on the radial distance from the center of the 150 mm wafer revealed that the actual C/Si ratio just above the wafer: surface C/Si ratio, is quite different to the introduced C/Si ratio. In-wafer distribution of thickness and carrier concentration in the epitaxial films can be explained by the surface C/Si ratio, which suggests that the surface C/Si ratio could be a useful indicator for the precise control of uniform growth on large-diameter wafers. It is also found that two types of SiC films, one with extremely low defect density and the other with low pit density, both with highly uniform growth rate and carrier concentration, could be grown by controlling of the surface C/Si ratio on the whole wafers.