Patent ID: 7212082

Claim:
A method of producing a piezoelectric thin film device in which a piezoelectric laminated structure including a piezoelectric thin film, an upper electrode and a lower electrode formed on the upper and lower surfaces of the film, respectively, is supported by a substrate, and in which a space for oscillation is formed to allow the oscillation of the piezoelectric laminated structure, comprising: a step of forming an insulating layer capable of being etched by a specific chemical substance on the upper surface of the substrate; a step of forming a sacrificial layer made of a substance having a higher etching rate by the specific chemical substance than the insulating layer on a partial region of the insulating layer; a step of forming a lower electrode on a region including a part or entirety of the sacrificial layer; a step of forming the piezoelectric thin film on a region including a part of the lower electrode; a step of forming an upper electrode on a region including a part of the piezoelectric thin film; a step of forming via hole so as to expose a part of the sacrificial layer or a part of the insulating layer provided under the sacrificial layer; and a step of forming the space for oscillation by etching both the sacrificial layer and the insulating layer provided under the sacrificial layer with the same specific chemical substance by introducing the specific chemical substance through the via hole.