Method for manufacturing a semiconductor device having a gate electrode

Claim 1

A method for manufacturing a semiconductor device, comprising the steps of: forming an element isolating region on a semiconductor substrate of a first conductivity type; forming an insulating film at the surface of an element region of said semiconductor substrate which is isolated by said element isolating region; selectively forming a gate electrode on said insulating film; doping an impurity of a second conductivity type in the element region as a first doping step with the gate electrode and element isolating region as masks; sequentially forming an oxidizable first film and a second film on the surface of the resultant structure; anisotropically etching the second film to leave partly said second film on that portion of oxidizable first film which is located on the side wall of the gate electrode; doping an impurity of a second conductivity type in said element region, as a second doping step, with the left second film, gate electrode and element isolating region as masks, said impurity of said second conductivity type being higher than that of said second conductivity type in said first doping step; removing said left second film; and converting said oxidizable first film to an oxide film.

Claim 2

A method for manufacturing a semiconductor device, comprising the steps of: forming an element isolating region on a semiconductor substrate of a first conductivity type; forming an insulating film at the surface of an element region of said semiconductor substrate which is isolated by said element isolating region; selectively forming a gate electrode on said insulating film; doping an impurity of a second conductivity type in the element region as a first doping step with the gate electrode and element isolating region as masks; sequentially forming an oxidizable first film and a second film on the surface of the resultant structure; anisotropically etching the second film to leave partly said second film on that portion of oxidizable first film which is located on the side wall of the gate electrode; doping an impurity of a second conductivity type in said element region, as a second doping step, with the left second film, gate electrode and element isolating region as masks, said impurity of said second conductivity type being higher than that of said second conductivity type in said first doping step; removing said left second film; and converting said oxidizable first film to an oxide film.

Claim 6

A method of manufacturing a complementary semiconductor device comprising the steps of: forming a well of a second conductivity type in a semiconductor substrate of a first conductivity type; forming element isolating regions on said semiconductor substrate and said well and thus forming a first element region in said well and a second element region in said semiconductor substrate; forming an insulating film on the surface of said first and second element regions; selectively forming a first gate electrode on said insulating film overlying said first element region and a second gate electrode on said insulating film overlying said second element region; doping an impurity of a first conductivity type into said first and second element regions, as a first doping step, with said first and second gate electrodes and said element isolating regions as masks; sequentially forming an oxidizable first film and a second film on the whole surface of the resultant structure; anisotropically etching said second film to partly leave said second film on that portion of said oxidizable first film which is located on the side wall of said first and second gate electrodes; doping an impurity of a first conductivity type into said first element region as a second doping step with said left second film, first gate electrode and element isolating region as masks; removing said left first film; converting said oxidizable first film to an oxide film; and doping, subsequent to either one of said removing step and said converting step, an impurity of said second conductivity type in said second isolating region as a third doping step with said second gate electrode and element isolating region as masks.

Claim 7

A method of manufacturing a complementary semiconductor device comprising the steps of: forming a well of a second conductivity type in a semiconductor substrate of a first conductivity type; forming element isolating regions on said semiconductor substrate and said well and thus forming a first element region in said well and a second element region in said semiconductor substrate; forming an insulating film on the surface of said first and second element regions; selectively forming a first gate electrode on said insulating film overlying said first element region and a second gate electrode on said insulating film overlying said second element region; doping an impurity of a first conductivity type into said first and second element regions, as a first doping step, with said first and second gate electrodes and said element isolating regions as masks; sequentially forming an oxidizable first film and a second film on the whole surface of the resultant structure; anisotropically etching said second film to partly leave said second film on that portion of said oxidizable first film which is located on the side wall of said first and second gate electrodes; doping an impurity of a first conductivity type into said first element region as a second doping step with said left second film, first gate electrode and element isolating region as masks; removing said left first film; converting said oxidizable first film to an oxide film; and doping, subsequent to either one of said removing step and said converting step, an impurity of said second conductivity type in said second isolating region as a third doping step with said second gate electrode and element isolating region as masks.