Patent ID: 7968414

Claim:
A method of manufacturing a semiconductor device, comprising: forming a gate insulating film over a silicon substrate; forming a gate electrode over the gate insulating film; implanting a first impurity having first conductivity into the silicon substrate using the gate electrode as a mask; forming a first side wall insulating film on a side wall of the gate electrode, a portion of the first side wall insulating film extending over the silicon substrate; forming a second side wall insulating film on the first side wall insulating film; implanting a second impurity having the first conductivity into the silicon substrate using the gate electrode, the first side wall insulating film, and the second side wall insulating film as masks; forming a trench in the silicon substrate by etching the silicon substrate using the gate electrode, the first side wall insulating film, and the second side wall insulating film as masks; removing a portion of the first side wall insulating film to form a concave portion between the silicon substrate and the second sidewall insulating film; forming a semiconductor mixed crystal layer in the trench and in the concave portion; and performing a heat treatment to diffuse an impurity in the semiconductor mixed crystal layer formed in the concave portion into the silicon substrate.