Abstract: A semiconductor pressure sensor according to the present invention includes a semiconductor substrate having a first surface, a second surface opposite to the first surface and a recess formed in the first surface, the recess defining an interior surface including a bottom surface; and a diffusion region extending from the adjacency of the bottom surface to the second surface. A pressure-sensitive resistance of the semiconductor pressure sensor is formed in the vicinity of the bottom surface of a diaphragm. Therefore, the pressure-sensitive resistance can be formed so as to be brought into alignment with the position of the diaphragm after the formation of the diaphragm. Accordingly, the semiconductor pressure sensor, which does not cause a displacement in position between the diaphragm and the pressure-sensitive resistance and has excellent accuracy, can be easily fabricated.

Abstract: A semiconductor pressure sensor according to the present invention comprises a semiconductor substrate having a first surface, a second surface opposite to the first surface and a recess formed in the first surface, the recess defining an interior surface including a bottom surface; and a diffusion region extending from the adjacency of the bottom surface to the second surface. A pressure-sensitive resistance of the semiconductor pressure sensor is formed in the vicinity of the bottom surface of a diaphragm. Therefore, the pressure-sensitive resistance can be formed so as to be brought into alignment with the position of the diaphragm after the formation of the diaphragm. Accordingly, a semiconductor pressure sensor, which does not cause a displacement in position between the diaphragm and the pressure-sensitive resistance and is excellent in accuracy, can be easily fabricated.

Abstract: A fabrication process of a semiconductor pressure sensor is described. A first recess and a second recess, which is deeper than the first recess, are formed in a first surface of a semiconductor substrate. A reinforcement layer is formed on the entire first surface. A second surface of the semiconductor substrate is then polished until a part of the second recess appears on a side of the second surface. After that, a resistance element is formed in the second surface at a region opposing the first recess.

Abstract: A process of manufacturing a Bi-CMOS type semiconductor integrated circuit according to the present invention by to providing an isolation procedure wherein PMOS and NMOS transistor isolation areas are selectively oxidixed so as to form a second isolation oxide film, simultaneous with the selective oxidation of the polysilicon layer deposited on the bipolar transistor area after the semiconductor substrate in the bipolar transistor isolation area, which has been removed to a required thickness and selectively oxidized so as to form a thick first isolation oxide film for the bipolar transistor.