Patent ID: 8501571

Claim:
A method of manufacturing a semiconductor device comprising: forming a gate insulating film and a gate electrode over a semiconductor substrate; forming first concave portions in the semiconductor substrate by etching the semiconductor substrate using the gate electrode as a mask; forming first side wall spacers on side walls of the gate electrode after forming the first concave portions; forming second concave portions in the first concave portions by etching the semiconductor substrate using the gate electrode and the first side wall spacers as masks; forming first carbon doped silicon layers including carbon at a first carbon concentration and including phosphorus at a first phosphorus concentration, in the second concave portion; removing the first side wall spacers after forming of the first carbon doped silicon layers; and forming second carbon doped silicon layers, which include phosphorus at a second phosphorus concentration higher than the first phosphorus concentration, in the first concave portions and over the first carbon doped silicon layers, after removing of the first side wall spacers, wherein the second carbon doped silicon layers includes carbon at the second carbon concentration lower than the first carbon concentration.