Piezoelectric thin film element
View Patent ↗A thin-film piezoelectric element has a substrate, a lower electrode, a piezoelectric portion, and an upper electrode that are sequentially formed on the substrate. The piezoelectric portion has a dielectric thin film that has an alkali niobium oxide-based perovskite structure expressed by general formula (Na x K y Li z )NbO 3 (0<x<1, 0<y<1, 0≦z<1, x+y+z=1), and a high voltage-withstand dielectric that has a dielectric strength voltage greater than that of the dielectric thin film.
1. A thin-film piezoelectric element, comprising:
a substrate, a lower electrode, a piezoelectric portion, and an upper electrode that are sequentially formed on the substrate,
wherein the piezoelectric portion comprises a dielectric thin film that comprises an alkali niobium oxide-based perovskite structure expressed by general formula (Na x K y Li z )NbO 3 (0<x<1, 0<y<1, 0≦z<1, x+y+z=1), and a high voltage-withstand dielectric that has a dielectric strength voltage greater than that of the dielectric thin film.
2. The thin-film piezoelectric element according to claim 1 , wherein:
the high voltage-withstand dielectric is inserted in a layered form between the dielectric thin film and the lower or upper electrode.
3. The thin-film piezoelectric element according to claim 1 , wherein:
the high voltage-withstand dielectric is inserted in a layered form between the dielectric thin film and the lower electrode and between the dielectric thin film and the upper electrode, respectively.
4. The thin-film piezoelectric element according to claim 1 , wherein:
the high voltage-withstand dielectric is inserted in a layered form in the dielectric thin film.
5. The thin-film piezoelectric element according to claim 1 , wherein:
the high voltage-withstand dielectric is mixed as an additive in the dielectric thin film.
6. The thin-film piezoelectric element according to claim 1 , wherein:
the high voltage-withstand dielectric comprises SrTiO 3 , α-Al 2 O 3 , Ta 2 O 5 , or SiO 2 .
7. The thin-film piezoelectric element according to claim 1 , wherein:
the high voltage-withstand dielectric has a dielectric strength voltage of 1 MV/cm or higher.
8. The thin-film piezoelectric element according to claim 1 , wherein:
the substrate comprises a MgO monocrystalline substrate or a Si substrate.
9. The thin-film piezoelectric element according to claim 1 , wherein:
at least one of the substrate, the lower electrode, the piezoelectric portion and the upper electrode comprises a microfabrication with a width of 1 mm or less.
10. The thin-film piezoelectric element according to claim 1 , wherein:
at least one of the lower electrode, the piezoelectric portion and the upper electrode is formed by RF magnetron sputtering.
11. The thin-film piezoelectric element according to claim 1 , wherein:
at least one of the lower electrode, the piezoelectric portion and the upper electrode is formed by aerosol deposition.
12. The thin-film piezoelectric element according to claim 1 , wherein:
the piezoelectric portion is sandwiched between the upper electrode and the lower electrode.