Patent ID: 8188521

Claim:
A power semiconductor device comprising: a first semiconductor layer of a first conduction type; second semiconductor layers of the first conduction type and third semiconductor layers of a second conduction type alternately provided transversely on the first semiconductor layer; fourth semiconductor layers of the second conduction type provided on the surfaces of the third semiconductor layers; fifth semiconductor layers of the first conduction type provided selectively on the surfaces of the fourth semiconductor layer; sixth semiconductor layers of the second conduction type and seventh semiconductor layers of the first conduction type alternately provided transversely on the second and the third semiconductor layers; a first main electrode electrically connected to the first semiconductor layer; an insulation film provided on the fourth semiconductor layers, the sixth semiconductor layers and the seventh semiconductor layers; a control electrode provided on the fourth semiconductor layers, the sixth semiconductor layers and the seventh semiconductor layers via the insulation film; and a second main electrode joined to the surfaces of the fourth semiconductor layers and the fifth semiconductor layers, the sixth semiconductor layers being connected to the fourth semiconductor layers and to at least one of the third semiconductor layers, which is provided between two of the fourth semiconductor layers, and an impurity concentration of the third semiconductor layers provided below the sixth semiconductor layers being higher than an impurity concentration of the third semiconductor layers provided under the fourth semiconductor layers.