Patent ID: 6958279

Claim:
A method for manufacturing a semiconductor device comprising the steps of: forming a gate insulator film and a gate electrode on a semiconductor substrate, forming a layered stack including two or more insulator films having etching rates different from one another on an entire surface of said semiconductor substrate, forming a mask sidewall adjacent to said gate electrode via said layered stack, said mask sidewall having an etching rate different from an etching rate of the outermost film among said insulator films in said layered stack, implanting a first ion dopant into said semiconductor substrate using said gate electrode, portions of said layered stack adjacent to said gate electrode, and said mask sidewall as a mask, removing said mask sidewall, performing anisotropic etching on an entire surface of said layered stack, thereby allowing part of said layered stack to remain only on a side of said gate electrode, and implanting a second ion dopant of the same conductivity type as that of said first ion dopant into said semiconductor substrate using said gate electrode and said layered stack as a mask, thereby forming a dopant diffusion layer.