Patent ID: 8549716

Claim:
A method for manufacturing a piezoelectric actuator, comprising: preparing a vibration plate formed of a metal; forming a diffusion-preventive layer on a surface of the vibration plate, a part of a surface of the diffusion-preventive layer not facing the vibration plate having an electrical conductivity; forming a piezoelectric layer in a first area, of the surface of the vibration plate, in which the diffusion-preventive layer is formed and in a second area, of the surface of the vibration plate, in which the diffusion-preventive layer is not formed; forming an electrode in a third area, of a surface of the piezoelectric layer not facing the vibration plate, which overlaps with the part of the surface of the diffusion-preventive layer; forming an extraction electrode in a fourth area, of the surface of the piezoelectric layer, which does not overlap with the diffusion-preventive layer; and heating the piezoelectric layer and the vibration plate so as to diffuse metallic atoms in the vibration plate to the piezoelectric layer, after the piezoelectric layer is formed, wherein in the heating of the piezoelectric layer and the vibration plate, the metallic atoms in the vibration plate are diffused to the piezoelectric layer such that a portion of the surface of the piezoelectric layer, which is located in the fourth area and which is in contact with the vibration plate is electrically conducted with the surface of the vibration plate so as to make the part of the surface of the diffusion-preventive layer be in conduction with the extraction electrode, in the forming of the diffusion-preventive layer, a diffusion-preventive film having an insulation property is formed on the surface of the vibration plate, and a first electrode is formed to cover both a surface of the diffusion-preventive film not facing the vibration plate and the surface of the vibration plate; in the forming of the extraction electrode, the extraction electrode is formed in an area, of the surface of the piezoelectric layer not facing the vibration plate, which does not overlap with the diffusion-preventive film, and in the heating of the piezoelectric layer and the vibration plate, the first electrode is conducted with the extraction electrode.