Piezoelectric device and production method for piezoelectric device

A production method for a piezoelectric device including a piezoelectric film including a functional conductor provided thereon, a fixing layer provided on a principal surface of the piezoelectric film such that a void overlaps a region where the functional conductor is provided in plan view, and a support substrate provided on a principal surface of the fixing layer opposite to the piezoelectric film, the production method comprising the steps of:

• forming a sacrificial layer on a principal surface of a piezoelectric substrate;
• forming the fixing layer on the principal surface of the piezoelectric substrate to cover the sacrificial layer;
• attaching the support substrate to a surface of the fixing layer opposite to the piezoelectric substrate;
• forming the piezoelectric film from the piezoelectric substrate;
• forming the functional conductor on the piezoelectric film;
• forming a through hole in the piezoelectric film by performing a dry etching at positions on the piezoelectric film straddling a boundary between the fixing layer and the sacrificial layer in plan view to define a step in an inner wall surface of the fixing layer;
• and
• removing the sacrificial layer by wet etching using the through hole, to form the void.