Field effect transistor and method of manufacturing the same

A method for manufacturing a field effect transistor, comprising the steps of:

• forming a first insulating film on an n-type semiconductor region;
• depositing a material containing Ge on the first insulating film;
• forming a second insulating film to cover the material containing the Ge;
• heating for diffusing the material containing the Ge in an interface region including an interface between the first insulating film and the second insulating film;
• forming a gate electrode on the second insulating film;
• and
• forming a source region and a drain region which are separated from each other in the n-type semiconducotr region by using the gate electrode as a mask.

A method for manufacturing a complementary field effect transistor, comprising the steps of:

• forming a first element region and a second element region on a semiconductor substrate;
• forming a first insulating film on an entire area on the semiconductor substrate;
• nitriding a surface of the first insulating film on the second element region in the first and second element regions;
• depositing a material containing phosphorous (P), arsenic (As), sulfur (S), and selenium (Se) and a material containing Ge;
• forming a second insulating film to cover the material containing the Ge;
• first heat treatment for diffusing the material containing the Ge in an interface region including an interface between the first insulating film and the second insulating film;
• forming a gate electrode on the second insulating film;
• forming a source region and a drain region which are separated from each other in the first element region and the second element region by using the gate electrode as a mask.