Patent ID: 8563382

Claim:
A semiconductor device manufacturing method comprising: forming a gate insulating film over a first conductive type silicon substrate; forming a gate electrode over the gate insulating film; forming a first sidewall spacer at a sidewall of the gate electrode; implanting a first impurity with a second conductive type to the silicon substrate by using the first sidewall spacer as a mask; forming a second sidewall spacer at the first sidewall spacer; implanting a third impurity with the second conductive type to the silicon substrate by using the second sidewall spacer as a mask to form a second diffusion region over the silicon substrate; forming a trench portion in the silicon substrate by etching the silicon substrate by using the sidewall spacer as a mask; forming a first Si mixed crystal layer that includes a second impurity with a first concentration in the trench portion; forming a second Si mixed crystal layer that includes the second impurity with a second concentration higher than the first concentration over the first Si mixed crystal layer; and forming a third Si mixed crystal layer that includes the second impurity with a third concentration lower than the second concentration over the second Si mixed crystal layer.