Patent ID: 7193268

Claim:
A semiconductor device comprising: a first conductive layer of a first conductive type; a second conductive layer of the first conductive type laminated on the first conductive layer; a third conductive layer of a second conductive type opposite to the first conductive type, the third conductive layer being laminated on the second conductive layer; a fourth conductive layer of the first conductive type laminated on the third conductive layer; a plurality of first grooves formed so as to extend the second conductive layer through the third conductive layer; a plurality of second grooves formed so as to extend in a direction across the first grooves from the surface of the fourth conductive layer to the third conductive layer through the fourth conductive layer, separately from the first grooves; conductive areas of the second conductive type formed so as to be exposed from at least the bottom faces of the second grooves; first insulating films formed on the side faces and bottom face of the first groove; gate electrode films formed on the surfaces of the first insulating films; second insulating films formed on the gate electrode films; a conductive film connected to the gate electrode films so as to be across the first grooves; a third insulating film formed so as to cover the conductive film; a source electrode film formed at least on the surface of the fourth conductive layer, and on side faces and bottom faces of the second grooves; a drain electrode film formed on the surface of the first conductive layer; and a conductive area for easing an electric field, the conductive area being formed between the second conductive layer and the third conductive layer, so as to cover the corners of the first grooves.