Patent ID: 7262477

Claim:
A semiconductor device, comprising: a semiconductor substrate with a trench, the semiconductor substrate comprising a first semiconductor layer of a first conductivity type and a second semiconductor layer disposed above the first semiconductor layer, and the second semiconductor layer including a first impurity diffusion region of the first conductivity type, a second impurity diffusion region of a second conductivity type, the second impurity diffusion region and the trench sandwiching the first impurity diffusion region, a base region of the second conductivity type which faces the first semiconductor layer with the first and second impurity diffusion regions interposed therebetween and is spaced apart from the trench, and a source region of the first conductivity type which faces the first semiconductor layer with the base region and the second impurity diffusion region interposed therebetween and is spaced apart from the first impurity diffusion region; a particulate insulating layer filling at least a lower portion of the trench and comprising insulating particles, wherein an average diameter of the insulating particles falls within a range of 100 nm to 500 nm or a range of 100 nm to half a width of opening of the trench; a reflowable dielectric layer covering an upper surface of the particulate insulating layer, the insulating particles being stable at a melting point or a softening point of the reflowable dielectric layer; a gate electrode facing a portion of the base region interposed between the first impurity diffusion region and the source region; a gate insulating film interposed between the gate electrode and the base region; a source electrode covering the source region; and a drain electrode covering the first semiconductor layer, the drain and source electrodes sandwiching the semiconductor substrate.