Patent ID: 6815284
Filing Date: 2004-11-09
Classification: H01L

Abstract:
A manufacturing method of a semiconductor device comprising:providing a semiconductor substrate of a first conductivity type; forming a first well region of a second conductivity type in the semiconductor substrate; forming a second well region of the second conductivity type having an impurity concentration higher than an impurity concentration of the first well region; forming a first gate insulation film on the first well region; forming a second gate insulation film thinner than the first gate insulation film on the second well region; ion-implanting first impurity ions of the first conductivity type into the substrate so that the first impurity ions reach the first and second well regions through the first and second gate insulating films; and ion-implanting second impurity ions of the first conductivity type into the substrate so that the second impurity ions reach the second well region through the second gate insulating film and do not reach the first well region through the first gate insulating film.