Patent ID: 8809903

Claim:
A semiconductor device comprising: a first semiconductor layer of a first conductive type; a second semiconductor layer of a second conductive type formed in the vicinity of a surface of the first semiconductor layer; a third semiconductor layer of the second conductive type adjacent to the first semiconductor layer and formed in the vicinity of a surface of an opposite side of the second semiconductor layer; a fourth semiconductor layer of the first conductive type selectively formed on the third semiconductor layer; a trench penetrating through the fourth semiconductor layer and the third semiconductor layer into the first semiconductor layer; a gate insulating layer formed along an internal face of the trench; an insulating layer formed in the trench; a first conductive layer formed on a surface of the gate insulating layer; and a second conductive layer formed on a surface of the insulating layer, wherein the first conductive layer in the trench of at least one cross-sectional structure is divided by the insulating layer and the second conductive layer, a width “a” of the trench is wider than a width “b” of an area in which the trench is not formed, the first conductive layer is formed on a lateral face of the trench having the width “a”, the insulating layer is thicker than the gate insulating layer, the insulating layer of an active area in the semiconductor device is thinner than the insulating layer of a peripheral area in the semiconductor device, a capacitor made up of the insulating layer and a third conductive layer is formed in the trench, and a fifth semiconductor layer of the second conductive type is formed on a first semiconductor layer side of the third semiconductor layer.