Method of making semiconductor device using oblique ion implantation

Abstract

The process of making a semiconductor device in which an n-channel MOSFET and a p-channel MOSFET are formed on the same semiconductor substrate is shortened. An impurity of p-type is ion-implanted vertically of a major surface of the semiconductor substrate to form p-type impurity doped layers in the embedding layers and p-type highly-concentrated impurity doped layers in the diffusion layers. Next, an impurity of n-type impurity is ion-implanted from obliquely above the semiconductor substrate major surface to form n-type highly-concentrated impurity doped layers in uppermost surfaces of the embedding layers. In the oblique ion-implantation, the n-type impurity is ion-implanted obliquely of the semiconductor substrate at a predetermined angle or more measured from a normal of the major surface of the semiconductor substrate so that semiconductor substrate portions (diffusion layers) at bottom ends of the contact holes for the p-channel MOSFET may not be viewed from obliquely above the semiconductor substrate major surface.