Method of making a metal-oxide semiconductor field-effect transistor

Claim 1

A method of making a metal-oxide semiconductor field-effect transistor comprising the steps of: preparing a semi-fabricated product comprising a semiconductor substrate of one conductivity type with a gate insulating layer formed on its top surface, and a gate built on said gate insulating layer; injecting an impurity of the other conductivity type into said semiconductor substrate perpendicular to the top surface of said semiconductor substrate to form two opposite diffusion layers of least concentration of impurity in said semiconductor substrate, extending from first and second locations under one and the other edge of said gate respectively in the opposite directions; forming a side wall surrounding said gate on said semiconductor substrate; injecting the impurity of the other conductivity type into said semiconductor substrate at a given acute angle with respect to the normal line perpendicular to the top surface of said semiconductor substrate to form two opposite diffusion layers of less concentration of impurity in said semiconductor substrate, extending short of the terminal ends of said diffusion layers of least concentration of impurity; injecting the impurity of the other conductivity type into said semiconductor substrate perpendicular to the top surface of said semiconductor substrate to form two opposite diffusion layers of relatively high concentration of impurity in said semiconductor substrate, extending from the first and second locations under one and the other edge of said side wall in the opposite directions; and forming drain, source and gate electrodes respectively.

Claim 2

A method of making a metal-oxide semiconductor field-effect transistor comprising the steps of: preparing a semi-fabricated product comprising a semiconductor substrate of one conductivity type with a gate insulating layer formed on its top surface, and a gate built on said gate insulating layer; injecting an impurity of the other conductivity type into said semiconductor substrate perpendicular to the top surface of said semiconductor substrate to form two opposite diffusion layers of least concentration of impurity in said semiconductor substrate, extending from first and second locations under one and the other edge of said gate respectively in the opposite directions; forming a side wall surrounding said gate on said semiconductor substrate; injecting the impurity of the other conductivity type into said semiconductor substrate at a given acute angle with respect to the normal line perpendicular to the top surface of said semiconductor substrate to form two opposite diffusion layers of less concentration of impurity in said semiconductor substrate, extending short of the terminal ends of said diffusion layers of least concentration of impurity; injecting the impurity of the other conductivity type into said semiconductor substrate perpendicular to the top surface of said semiconductor substrate to form two opposite diffusion layers of relatively high concentration of impurity in said semiconductor substrate, extending from the first and second locations under one and the other edge of said side wall in the opposite directions; and forming drain, source and gate electrodes respectively.