Semiconductor device and method for manufacturing the same

A method for manufacturing a semiconductor device comprising:

• forming a gate insulating film containing oxide of Ti, Zr, Hf or Ta on a silicon substrate;
• forming a gate electrode on the gate insulating film;
• forming first diffused layers on a surface of the silicon substrate which sandwich the gate electrode;
• forming first gate side walls on the gate insulating film which sandwich the gate electrode in a gate length direction;
• converting a part of the gate insulating film which is not covered with the gate electrode and the first gate side wall into a low resistance precursor layer by supplying nitrogen, boron or carbon;
• converting the low resistance precursor layer into a low resistance layer by forming a mixture of nitride, boride or carbide of Ti, Zr, Hf or Ta and oxide of Ti, Zr, Hf or Ta by heat treatment;
• forming second gate side walls which sandwich the gate electrode and the first gate side wall;
• and
• forming second diffused layers in the silicon substrate which sandwich the gate electrode, the first gate side wall and the second gate side wall.