Patent ID: 7259424

Claim:
A semiconductor device, comprising: a channel region of a first conduction type formed in a surface layer portion of a semiconductor substrate, the channel region having a trench penetrating therethrough; a source region of a second conduction type formed adjacent to a rim portion of the trench; a base region of the first conduction type formed in the surface layer portion of the semiconductor substrate adjacent to the source region; a gate insulation film formed on an inner sidewall surface of the trench; a gate electrode placed inside the trench to oppose the channel region with the gate insulation film in between; and an insulation film disposed above the gate electrode, and having a portion inside of the trench, and a further portion outside of the trench which protrudes above the rim portion and from an end of the gate insulation film opposite to a bottom of the trench, the portion of the insulation film inside of the trench having a side surface extending along a sidewall surface of the gate insulation film the portion of the insulation film outside of the trench also having a side surface that is contiguous with, and in a same plane as, the side surface of the portion inside of the trench, so that a transition between the portion of the insulation film outside of the trench inside of the trench and the further portion outside of the trench is step-free.