Semiconductor device and manufacturing method thereof, a power converter, a three-phase motor system, the motor vehicle rail vehicle,

The present invention is a high performance, and aims to provide a highly reliable power semiconductor device. The semiconductor device of the present invention includes a semiconductor substrate of a first conductivity type, a drain electrode formed on the back surface side of the semiconductor substrate, a drift layer of a first conductivity type formed on a semiconductor substrate, a first conductive -type source region, a first conductivity type current diffusion layer in electrical drift layer connected in contact with the source region and the current diffusion layer, a second conductivity type opposite the first conductivity type and the body layer, a source region, a body layer, extends and the current diffusion layer, the shallower than the body layer, a trench bottom surface is in contact with the body layer, a gate insulating formed on the inner wall of the trench It has a film, a gate electrode formed on the gate insulating film, and a gate insulating film protective layer layer formed between the current spreading layer and the gate electrode.