Patent ID: 7906416

Claim:
A method for manufacturing a semiconductor device from a semiconductor wafer having a first major surface, a recess provided inside a periphery on opposite side of the first major surface and surrounded by the periphery, and a second major surface provided at bottom of the recess, the method comprising: fitting into the recess a doping mask having selectively formed openings to selectively cover the second major surface with the doping mask; selectively introducing dopant into the second major surface; and forming a semiconductor layer of a first conductive type on a surface portion of the second major surface of the semiconductor wafer by introducing dopant into an entire surface of the second major surface of the semiconductor wafer and activating the introduced dopant, wherein the selectively introducing dopant into the second major surface includes selectively introducing dopant of a second conductivity type into the semiconductor layer of the first conductivity type, and the doping mask includes a circular plate having the openings and selectively covering the second major surface; and a sidewall integrally provided at a periphery of the circular plate and covering an inner peripheral surface of the periphery in the semiconductor wafer.