Pressure sensor apparatus and method of manufacturing wherein the

Abstract

A semiconductor silicon single-crystal substrate is used in which the crystallographic axes are inclined by a predetermined angle with respect to a normal to a thicknesswise face of the semiconductor silicon single-crystal substrate. A conductive-type epitaxial layer is grown on this semiconductor silicon single-crystal substrate to a predetermined thickness such that the direction of the crystallographic axes of the conductive-type epitaxial layer coincides with the direction of the crystallographic axes of the semiconductor silicon single-crystal substrate. Accordingly, since side surfaces of a cavity portion provided in the semiconductor silicon single-crystal substrate by the etching of the substrate, i.e., side walls of the semiconductor silicon single-crystal substrate provided respectively in the longitudinal direction of a diaphragm, are each formed at an angle of 90.degree. with respect to the thicknesswise lower surface of the conductive-type epitaxial layer. Accordingly, an ultra-compact pressure sensor is formed in which the dimensional accuracy of the diaphragm is high. In addition, when etching is performed, etching stops at the epitaxial layer. Namely, since the epitaxial layer acts as an etching stopper, the dimensional accuracy in the thickness of the diaphragm is excellent over an entire wafer region for forming the substrate, and the yield in the wafer state improves remarkably.