Silicon carbide semiconductor device

摘要

A silicon carbide layer is epitaxially formed on a main surface of a substrate. The silicon carbide layer is provided with a trench having a side wall inclined relative to the main surface. The side wall has an off angle of not less than 50° and not more than 65° relative to a {0001} plane. A gate insulating film is provided on the side wall of the silicon carbide layer. The silicon carbide layer includes: a body region having a first conductivity type and facing a gate electrode with the gate insulating film being interposed therebetween; and a pair of regions separated from each other by the body region and having a second conductivity type. The body region has an impurity density of 5×1016 cm−3 or greater. This allows for an increased degree of freedom in setting a threshold voltage while suppressing decrease of channel mobility.

主权项

1. A method for manufacturing a silicon carbide semiconductor device comprising the steps of:
preparing a substrate made of silicon carbide having a hexagonal crystal structure and having a main surface; forming a silicon carbide layer of a first conductivity type on said main surface of said substrate; forming a body region of a second conductivity type having an impurity density of 5×1016 cm−3 or greater at said silicon carbide layer; forming a trench having a side wall inclined relative to said main surface to extend through said body region using a thermal etching; forming a gate insulating film on said side wall of said trench; and forming a gate electrode on said gate insulating film such that said gate electrode has a threshold voltage which allows a weak inversion layer to be formed in said body region, said threshold voltage being 2 V or greater in a temperature range of not less than a room temperature and not more than 100° C. and such that channel mobility of electrons is 30 cm2/Vs or greater at a room temperature.