Method for producing a field-effect type semiconductor device

Claim 1

A method for producing a field-effect type semiconductor device, said method comprising the steps of: forming a first insulator film, which serves as a gate insulator film, on a semiconductor substrate of a first conductivity type; forming a first conductor film on the first insulator film; forming a second conductor film on the first conductor film and patterning the second conductor film; implanting impurity ions in the semiconductor substrate through the first insulator film and the first conductor film from an inclined direction with the use of the patterned second conductor film as a mask for the purpose of controlling the threshold of the device; implanting impurity ions in the semiconductor substrate through the first insulator film and the first conductor film from a substantially perpendicular direction with the use of the patterned second conductor film as a mask to form a first semiconductor region of a second conductivity; thereafter forming a second insulator film on the entire surface and removing parts of said second insulator film by anisotropic etching, the remainder of said second insulator film forming a spacer composed of parts of the patterned second insulator film which are left on the side walls thereof after anisotropic etching of the second insulator film; and implanting impurity ions in the semiconductor substrate through the first insulator film from a substantially perpendicular direction with the use of the second conductor film and the spacer present on the side walls thereof as a mask to form a second semiconductor region of the second conductivity, wherein the first and second conductor films are employed as a gate electrode and the first and second semiconductor regions serve as a lightly doped drain (LDD) and source/drain region, respectively.

Claim 2

A method for producing a field-effect type semiconductor device, said method comprising the steps of: forming a first insulator film, which serves as a gate insulator film, on a semiconductor substrate of a first conductivity type; forming a first conductor film on the first insulator film; forming a second conductor film on the first conductor film and patterning the second conductor film; implanting impurity ions in the semiconductor substrate through the first insulator film and the first conductor film from an inclined direction with the use of the patterned second conductor film as a mask for the purpose of controlling the threshold of the device; implanting impurity ions in the semiconductor substrate through the first insulator film and the first conductor film from a substantially perpendicular direction with the use of the patterned second conductor film as a mask to form a first semiconductor region of a second conductivity; thereafter forming a second insulator film on the entire surface and removing parts of said second insulator film by anisotropic etching, the remainder of said second insulator film forming a spacer composed of parts of the patterned second insulator film which are left on the side walls thereof after anisotropic etching of the second insulator film; and implanting impurity ions in the semiconductor substrate through the first insulator film from a substantially perpendicular direction with the use of the second conductor film and the spacer present on the side walls thereof as a mask to form a second semiconductor region of the second conductivity, wherein the first and second conductor films are employed as a gate electrode and the first and second semiconductor regions serve as a lightly doped drain (LDD) and source/drain region, respectively.