Patent ID: 8618606

Claim:
A semiconductor device, comprising: a semiconductor substrate; a first layer of a first conductivity type formed at a surface of the semiconductor substrate and having an impurity concentration higher than an impurity concentration of the semiconductor substrate; a second layer of a second conductivity type formed at the surface of the semiconductor substrate to be in contact with the first layer and having an impurity concentration higher than the impurity concentration of the semiconductor substrate; a base layer of a first conductivity type formed at the surface of the semiconductor substrate in the first layer and having an impurity concentration higher than the impurity concentration of the first layer; a collector layer of a second conductivity type formed at the surface of the semiconductor substrate in the second layer and having an impurity concentration higher than the impurity concentration of the second layer; an emitter layer of the second conductivity type located between the base layer and the collector layer, formed at the surface of the semiconductor substrate in the first layer, and having an impurity concentration higher than the impurity concentration of the first layer; and an electric field relaxation layer of a second conductivity type formed between the collector layer and the first layer to be in contact with the collector layer and having an impurity concentration lower than the impurity concentration of the collector layer and higher than the impurity concentration of the second layer.