Patent ID: 7300836

Claim:
A method of manufacturing a semiconductor device comprising a semiconductor substrate of a first conductivity type, comprising: forming a well of a second conductivity type in the semiconductor substrate; forming an element separation layer and a gate insulation film on the well; forming a gate electrode on the gate insulation film and adjacent the element separation layer; forming on the well a first photoresist layer having an opening above a portion of the well surrounded by the element separation layer; doping a low concentration of impurities of the first conductivity type into the well using the first photoresist layer as a mask so as to form a diffusion resistance layer of the first conductivity type; forming an insulation film to cover a top surface and a side wall of the gate electrode and to cover the diffusion resistance layer after removing the first photoresist layer; forming on the diffusion resistance layer a second photoresist layer having an opening; etching the insulation film and the gate insulation film so that a sidewall spacer is formed on the sidewall of the gate electrode and that a part of the diffusion resistance layer is exposed through the opening of the second photoresist layer; and doping a high concentration of impurities of the first conductivity type into the well using the second photoresist layer as a mask so that a source layer and a drain layer are formed adjacent the gate electrode and that a high impurity concentration layer is formed in the diffusion resistance layer.