Semiconductor device and manufacturing method thereof

A semiconductor device comprising a first conductivity type MOSFET and a second conductivity type MOSFET,

• wherein the first conductivity type MOSFET comprises:
• a first insulating film formed over a semiconductor substrate;
• a second insulating film formed over the first insulating film and containing hafnium, a rare earth element or Mg, and oxygen as main components, comprised of an insulating material having a higher dielectric constant than the first insulating film;
• and
• a first gate electrode formed over the second insulating film and having a first metal layer comprising any one of TiN and TaN;
• and
• wherein the second conductivity type MOSFET comprises:
• a third insulating film aligned with the first insulating film over the semiconductor substrate over which the first insulating film is placed;
• a fourth insulating film formed over the third insulating film and containing hafnium and oxygen as main components, comprised of an insulating material having a higher dielectric constant than the third insulating film;
• a cap layer formed over the fourth insulating film and containing a rare earth element or Mg;
• a second gate electrode formed over the cap layer and having a second metal layer comprising any one of TiN and TaN;
• and
• a diffusion barrier film formed between the fourth insulating film and the cap layer to prevent diffusion of the rare earth element or Mg into the fourth insulating film,
• wherein the diffusion barrier film comprises Al2O3 or AlN.