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

摘要

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 (20) and a silicon nitride film (21) being formed, p-type impurity ions (23.sub.1, 23.sub.2) are implanted in a Y direction from diagonally above. As for an implant angle .alpha. of the ion implantation, an implant angle is adopted that satisfies the relationship tan⁻¹ (W2/T)α≦tan⁻¹ (W1/T), where W1 is an interval between a first portion (21₁) and a fourth portion (21₄) and an interval between a third portion (21₃) and a sixth portion (21₆); W2 is an interval between a second portion (21₂) and a fifth portion (21₅); T is a total film thickness of the silicon oxide film (20) and the silicon nitride film (21). When the implant angle α is controlled within that range, impurity ions (23₁, 23₁) are implanted into a second side surface (10A₂) and a fifth side surface (10A₅) through a silicon oxide film (13).