Patent ID: 7485936

Claim:
A semiconductor device comprising: a first MIS transistor with a first conductivity type channel, including a first semiconductor region of a second conductivity type formed in a semiconductor substrate, a first gate insulating film formed on the first semiconductor region, a first gate electrode formed on the first gate insulating film, the first gate electrode being formed of a material for which a work function shows a value suitable for second conductivity type MIS transistors, and first source and drain regions formed in the first semiconductor region at both sides of the first gate electrode; and a second MIS transistor with a second conductivity type channel, including a second semiconductor region of the first conductivity type formed in the semiconductor substrate, a second gate insulating film formed on the second semiconductor region, a second gate electrode formed on the second gate insulating film, the second gate electrode being formed of a material for which a work function shows a value suitable for second conductivity type MIS transistors, and second source and drain regions formed in the second semiconductor region at both sides of the second gate electrode, wherein in a region in the first gate electrode 1 nm or less apart from an interface with the first gate insulating film in a film thickness direction, a concentration of oxygen is 1×10 20 cm −3 or more and 1×10 22 cm −3 or less, and only the oxygen is capable of causing work function modulation of the first gate electrode.