| 摘要 |
It is an object of this invention to provide a piezoelectric film element which has structural characteristics capable of preventing the generation of cracks in the steps of manufacturing the piezoelectric film element and of increasing the thickness of a piezoelectric film. The piezoelectric film element of this invention comprises a dislocation layer in the piezoelectric film. This "dislocation layer" is the layer of which atoms in crystals are partly defective, which is caused by lattice defects. In the step of forming the piezoelectric film, when a sol which is a piezoelectric film precursor is turned into a gel by means of thermal treatment and when crystal grains of the sol grow, a lattice arrangement over the surfaces of the crystal grains is disturbed moderately. Accordingly, when the piezoelectric film is formed over the gel, the dislocation layer can be formed in the piezoelectric film. It is particularly desirable that the piezoelectric film have a plurality of dislocation layers in its film thickness direction and that the dislocation layers be formed in a manner such that the distances between the adjacent dislocation layers are the same or gradually become shorter from the lower electrode side to the upper electrode side. As stresses caused at the time of formation of the piezoelectric film strongly affect the surface of the piezoelectric film (on the upper electrode side), the above-described structure can effectively relax the stresses caused at the time of formation of the piezoelectric film. Therefore, it is possible to increase the thickness of the piezoelectric film.
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