METHOD OF MANUFACTURING SEMICONDUCTOR PRESSURE SENSOR

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor pressure sensor in which, even when both of a pressure detection element and a circuit part are formed on a single semiconductor substrate, it is possible to secure the atom-level flatness of the semiconductor substrate.SOLUTION: An SOI substrate 31 is prepared, and recesses 32a and 32b are formed on the side of a surface 31d of a first semiconductor layer 31a of the SOI substrate 31. On a bottom of each of the recesses 32a and 32b, a plurality of gage resistances 33 and a circuit part 35 are formed (a circuit formation step). A diffusion layer 36 connecting between each of the gage resistances 33 and the circuit part 35 is also formed. On the other hand, a cap part 40 is prepared. Polishing by a CMP method is performed to the surface 31d of the SOI substrate 31 (a flattening step). Then, the surface 31d of the SOI substrate 31 and the cap part 40 are bonded together (a bonding step). Thus, even if the flatness of the surface 31d of the first semiconductor layer 31a is lost in the circuit formation step, the atom-level flatness of the surface 31d can be secured before the bonding step is performed.