Patent ID: 8183606
Filing Date: 2012-05-22
Classification: H01L

Abstract:
1. A semiconductor device comprising: an insulated gate field effect transistor having a gate electrode, a source and a drain, the gate electrode having a poly-silicon layer buried in a trench formed in a first area of a semiconductor substrate via the a gate insulating film, the source and the drain being formed in the first area of the semiconductor substrate; a first silicon oxide film formed on a second area of the semiconductor substrate adjacent to the first area, the first silicon oxide film being thicker than the gate insulating film and containing larger amount of impurities than the gate insulating film; a poly-silicon layer formed on the first silicon oxide film; a protection diode having a plurality of PN-junctions formed in the poly-silicon layer, the protection diode being connected between the gate electrode and the source; a second silicon oxide film formed at a corner formed of a main surface of the semiconductor substrate and a side surface of an end of the trench, the second silicon oxide film being thicker than the gate insulating film, containing larger amount of impurities than the gate insulating film and being in contact with the gate insulating film; and a gate wiring in contact with the end of the gate electrode, the gate wiring having a poly-silicon layer formed at the corner, so as to cover the second silicon oxide film.