SILICON CARBIDE SEMICONDUCTOR DEVICE AND PROCESS FOR PRODUCING THE SILICON CARBIDE SEMICONDUCTOR DEVICE

摘要

Disclosed is a silicon carbide semiconductor device comprising a substrate of silicon carbide and an active layer having a reduced defect density provided on the substrate. Also disclosed is a process for producing the silicon carbide semiconductor device. A semiconductor device (1) comprises a substrate (2) of silicon carbide having an off angle to a plane direction {0001} of not less than 50° and not more than 65°, a buffer layer (21), an epitaxial layer (3) as an active layer, a p-type layer (4), and n+ regions (5, 6). The buffer layer (21) is provided on the substrate (2) and is formed of silicon carbide. The active layer is provided on the buffer layer (21) and is formed of silicon carbide. The micropipe density in the active layer is lower than that in the substrate (2). In the active layer, the density of dislocation in which the direction of a burgers vector is [0001] is higher than that in the substrate (2). Regarding film forming conditions in the step of forming the buffer layer (S20), the composition and flow rate of a starting material gas for the formation of the buffer layer (21) are determined so that the ratio of carbon atoms to silicon atoms in the starting material gas, i.e., C/Si ratio, is lower than the C/Si ratio in the step of forming the active layers (3 to 6) (S30).