Method of manufacturing semiconductor device capable of suppressing impurity concentration reduction in doped channel region arising from formation of gate insulating film

Abstract

A method of manufacturing a semiconductor device is provided that can suppress impurity concentration reduction in a doped channel region arising from formation of a gate insulating film. With a silicon oxide film () and a silicon nitride film () being formed, p-type impurity ions () are implanted in a Y direction from diagonally above. As for an implant angle α of the ion implantation, an implant angle is adopted that satisfies the relationship tan(W/T)<α≦tan(W/T), where Wis an interval between a first portion () and a fourth portion () and an interval between a third portion () and a sixth portion (); Wis an interval between a second portion () and a fifth portion (); T is a total film thickness of the silicon oxide film () and the silicon nitride film (). When the implant angle α is controlled within that range, impurity ions () are implanted into a second side surface (A) and a fifth side surface (A) through a silicon oxide film ().