Patent ID: 8283223

Claim:
A method of manufacturing a semiconductor device including a first-conduction-type MOSFET and a second-conduction-type MOSFET over a semiconductor substrate, comprising: forming a gate insulating film in a first-conduction-type MOSFET forming region and a second-conduction-type MOSFET forming region of said semiconductor substrate; forming a hard mask that has an opening at a position corresponding to said gate insulating film formed in said first-conduction-type MOSFET forming region and covers said gate insulating film formed in said second-conduction-type MOSFET forming region; forming a first metal layer over said gate insulating film disposed in said first-conduction-type MOSFET forming region and said hard mask formed in said second-conduction-type MOSFET forming region; performing a heat treatment to thermally diffuse a metal material forming said first metal layer into said gate insulating film formed in said first-conduction-type MOSFET forming region; removing said remaining first metal layer from said first-conduction-type MOSFET forming region and said second-conduction-type MOSFET forming region; removing said hard mask from said second-conduction-type MOSFET forming region; forming a second metal layer that is made of a metal material different from that forming said first metal layer over said gate insulating film in said first-conduction-type MOSFET forming region and said second-conduction-type MOSFET forming region of said semiconductor substrate, said second metal layer being part of gate electrodes of said first-conduction-type MOSFET and said second-conduction-type MOSFET; and forming a silicon layer over said second metal layer, said silicon layer being part of said gate electrodes of said first-conduction-type MOSFET and said second-conduction-type MOSFET, wherein said forming said gate insulating film includes: forming a first insulating film; and forming a second insulating film with a dielectric constant greater than that of said first insulating film, wherein said forming said hard mask includes: forming a film that is made of the same material as that forming said hard mask over the entire surface of said gate insulating film in said first-conduction-type MOSFET forming region and said second-conduction-type MOSFET forming region; forming a resist so as to cover the entire surface of said film; forming an opening in said resist in said first-conduction-type MOSFET forming region to expose said film; removing said film exposed from said opening of said resist to expose said gate insulating film in said first-conduction-type MOSFET forming region; and removing said resist using a wet process.