Piezoelectric device and method for manufacturing piezoelectric device
In a method of manufacturing a piezoelectric device, among a +C plane on a +Z axis side of a piezoelectric thin film and a −C plane on a −Z axis side of the piezoelectric thin film, the −C plane on the −Z axis side of the piezoelectric thin film is etched. Thus, −Z planes of the piezoelectric thin film on which epitaxial growth is possible are exposed. Ti is epitaxially grown on the −Z planes of the piezoelectric thin film in the −Z axis direction such that the crystal growth plane thereof is parallel to the −Z planes of the piezoelectric thin film. Al is then epitaxially grown on the surface of the Ti electrode in the −Z axis direction such that the crystal growth plane thereof is parallel to the −Z planes of the piezoelectric thin film.
1. A method for manufacturing a piezoelectric device including a support and a piezoelectric thin film formed on or over the support, polarized along a +Z axis and a −Z axis that are crystal axes, and including a +C plane and a C plane, the +C plane being a first main surface on a side of the +Z axis of the piezoelectric thin film, and the C plane being a second main surface on a side of the −Z axis of the piezoelectric thin film, the method comprising:
a dielectric film-forming step of, among the +C plane and the −C plane, forming a dielectric film on the +C plane of the piezoelectric thin film;
a support-forming step of forming a support on the dielectric film;
an etching step of, among the +C plane and the −C plane, etching the −C plane; and
an electrode-forming step of forming an electrode by epitaxially growing an electrode material on a crystal plane, exposed by the etching, of the piezoelectric thin film perpendicular to the −Z axis in the −Z axis direction such that a crystal growth plane thereof is parallel to the crystal plane of the piezoelectric thin film.
2. The method for manufacturing a piezoelectric device according to claim 1 , wherein the electrode material is aluminum or an aluminum-based material.
3. The method for manufacturing a piezoelectric device according to claim 2 , wherein the electrode is formed in the electrode-forming step by epitaxially growing the aluminum on the crystal plane of the piezoelectric thin film in the −Z axis direction such that a (111) crystal growth plane of the aluminum is parallel to the crystal plane of the piezoelectric thin film.
4. The method for manufacturing a piezoelectric device according to claim 3 , wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.
5. The method for manufacturing a piezoelectric device according to claim 2 , wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.
6. The method for manufacturing a piezoelectric device according to claim 1 , wherein the piezoelectric thin film comprises single-crystal lithium niobate or single-crystal lithium tantalate.
7. The method for manufacturing a piezoelectric device according to claim 1 , further comprising:
an ion implantation step of implanting an ionized element into a single-crystal piezoelectric substrate to form a region in which a concentration of the element implanted into the single-crystal piezoelectric substrate peaks; and
a splitting step of splitting off the piezoelectric thin film from the single-crystal piezoelectric substrate along the region in which the concentration of the implanted element peaks.
8. The method for manufacturing a piezoelectric device according to claim 7 , wherein the single-crystal piezoelectric substrate is a rotated Y-cut substrate.