Patent ID: 9688528
Date: 2017-06-27
CPC Classifications: B81B,B81C,G01C,G01P,H01L,H03H,H04R

Claim:
1. A method for producing a diaphragm-type resonant micro electro mechanical system device, the method comprising the steps of: forming a first silicon oxide film by thermal oxidation or by a process including a heat treatment at 900° C. or above; forming a second silicon oxide film having a stress with an absolute value of 100 MPa or less; forming a lower electrode; forming a piezoelectric film; forming an upper electrode; laminating, on a first surface of a silicon substrate, the first silicon oxide film, the second silicon oxide film, the lower electrode, the piezoelectric film, and the upper electrode in this order; and etching the opposite side surface of the first surface of the silicon substrate by deep reactive ion etching until the first silicon oxide film is exposed so as to form a recess, and thereby forming a diaphragm structure including a diaphragm having the first silicon oxide film and the second silicon oxide film, wherein when the film thickness of the first silicon oxide film is designated as t