Semiconductor device and method for manufacturing same

A method for manufacturing a semiconductor device including an nMOS region and a pMOS region set therein, the method comprising:

• forming a first insulating film including silicon and oxygen on a semiconductor substrate in the nMOS region and the pMOS region;
• forming a second insulating film on the first insulating film in the nMOS region and the pMOS region;
• removing the second insulating film from the pMOS region;
• forming a third insulating film on the first insulating film of the pMOS region and on the second insulating film of the nMOS region, the third insulating film having a dielectric constant higher than a dielectric constant of the first insulating film,
• forming a conducting film containing aluminum on the third insulating film;
• and
• diffusing the aluminum contained in the conducting film to an interface between the first insulating film and the third insulating film in the pMOS region.