Patent ID: 7820476

Claim:
A method for manufacturing a semiconductor device, comprising: forming a first region and a second region at a main surface of a semiconductor substrate; forming a gate insulating film containing Hf or Zr and oxygen on said first region and said second region; forming a first metallic film on said gate insulating film; forming a second metallic film on said first metallic film; removing a portion of said second metallic film to expose said first metallic film on said second region under the condition that said second metallic film on said first region can remain; forming a third metallic film on said second metallic film and a portion of said first metallic film exposed by removing said portion of said second metallic film; forming a gate electrode including the first metallic film, the second metallic film, and the third metallic film; thermally treating so that constituent elements of said second metallic film is diffused into said gate insulating film via said first metallic film at a temperature of at least 1000 ° C.; and after the thermally treating, forming source and drain regions using the gate electrode as a mask.