Patent ID: 8859365

Claim:
A method for manufacturing a semiconductor device, comprising: forming a plurality of trenches in an upper surface of a semiconductor substrate of a first conductivity type; forming a gate insulating film on an inner surface of the trench; burying a gate electrode in a lower portion in the trench; burying an insulating member in an upper portion in the trench; projecting the insulating member from the upper surface of the semiconductor substrate by removing an upper layer portion of the semiconductor substrate; forming a base layer of a second conductivity type in a portion of the semiconductor substrate above a lower end of the gate electrode by doping the semiconductor substrate with impurity; forming a mask film so as to cover the projected insulating member; forming a first semiconductor layer of the first conductivity type in an upper layer portion of the base layer by doping the base layer with impurity, the upper layer portion having a lower surface below an upper end of the gate electrode; forming a carrier ejection layer of the second conductivity type in part of the base layer and part of the first semiconductor layer by implanting impurity into the semiconductor substrate using a portion of the mask film formed on a side surface of the insulating member as a mask, the carrier ejection layer having a higher effective impurity concentration than the base layer; forming a first electrode so as to be connected to the upper surface of the semiconductor substrate; and forming a second electrode so as to be connected to a lower surface of the semiconductor substrate.