Patent ID: 7633139

Claim:
A semiconductor device comprising a diode element on a semiconductor substrate, the device comprising: a semiconductor substrate; a well layer of a first general conductivity type formed in the substrate and connected with a cathode electrode of the diode element; a first impurity layer of a second general conductivity type formed in the well layer and connected with an anode electrode of the diode element; a second impurity layer of the second general conductivity type formed in the well layer and connected with the cathode electrode of the diode element, the second impurity layer being separated from the first impurity layer; an electrode layer disposed on the well layer between the first impurity layer and the second impurity layer; and an insulation film interposed between the well layer and the electrode layer, wherein the first impurity layer, the well layer and the second impurity layer are configured to form a lateral bipolar transistor, the first impurity layer comprises a first island portion and a second island portion, and the electrode layer surrounds the first and second island portions of the first impurity layer completely in plan view of the semiconductor device.