Patent ID: 8716782
Filing Date: 2014-05-06
Classification: H01L

Abstract:
1. A semiconductor device comprising: a semiconductor layer of a first conductivity type; a first semiconductor layer of the first conductivity type provided on a first surface of the semiconductor layer of the first conductivity type; a second semiconductor layer of a second conductivity type provided on the first semiconductor layer; a trench provided from the second semiconductor layer to the first semiconductor layer; a gate insulating film composed of an oxide film and a protective layer, the oxide film covering the second semiconductor layer exposed at a sidewall of the trench and including at least one of aluminum and yttrium, and the protective layer being formed on the oxide film; a gate electrode made of n-type polysilicon buried in the trench in direct contact with the gate insulating film and opposed to the second semiconductor layer across the oxide film and the protective layer; an interlayer insulating film provided on the gate electrode; a third semiconductor layer of the first conductivity type selectively formed on a surface of the second semiconductor layer, and in contact with the gate insulating film at the sidewall of the trench; a first electrode electrically connected to a second surface of the semiconductor layer on an opposite side of the first surface; and a second electrode electrically connected to the third semiconductor layer, wherein the protective layer includes one of a silicon oxide film, a silicon nitride film, and a silicon oxynitride film.