SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE
Disclosed is a semiconductor device in which a diode and a transistor coexist on the same substrate, and in which leakage current that is generated unrelated to control performed by a gate electrode of the transistor is suppressed, and also provided is a method for manufacturing the semiconductor device. A P-type well diffusion layer and a P-type extraction electrode region are formed in an N-type semiconductor layer, which is formed by a high resistance N-type substrate, and are fixed to ground potential by an electrode. The potential near the surface of the P-type well diffusion layer is held at the ground potential because a depletion layer that spreads toward the P-type well diffusion layer does not reach the boundary surface with an embedded oxide film. When a voltage is applied from a power supply voltage to the rear surface of the N-type semiconductor layer and a cathode electrode, the generation of leakage current unrelated to the control performed by the gate electrode can be suppressed because a channel region on the embedded oxide film side of a MOS-type transistor formed in the P-type semiconductor layer does not act.