BIPOLAR SEMICONDUCTOR DEVICE

PURPOSE:To improve the easiness of the design of an integrated circuit mask pattern and reduce the unit cost of a product by a method wherein a collector electrode aperture is divided in the case of a vertical device and a base electrode aperture is divided in the case of a lateral device, etc. CONSTITUTION:A first conductivity type high impurity concentration buried region 21 provided near the surface of a semiconductor substrate 20, a first conductivity type low impurity concentration semiconductor layer 4 which is adjacent to and continuous with the buried layer 21 and a second conductivity type base region which is provided from the surface toward the inside of the semiconductor layer 4 are provided. Further, a first conductivity type emitter region which is provided from the surface part toward the inside of the base region, a first conductivity type diffused region 23 which reaches the buried region 21 from the surface of the semiconductor layer 4 and which has approximately the same surface impurity concentration as the semiconductor layer 4 and an insulator layer 22 which covers the surface of the semiconductor layer 4 are provided. Moreover, contact electrodes which are electrically connected to the high impurity concentration region 23 through an aperture which pierces through the insulator layer 22 and exposes the surfaces of the respective regions and through the other aperture which pierces through the insulator layer 22 covering the diffused region 23 selectively are provided.