Piezoelectric thin-film resonator, piezoelectric filter, and electronic component including the piezoelectric filter
A piezoelectric thin-film resonator includes a supporting substrate. A piezoelectric thin-film is formed on the supporting substrate. A lower electrode and an upper electrode are formed with the piezoelectric thin-film therebetween. The stiffness of at least one of the lower and upper electrodes is higher than that of the piezoelectric thin-film.
1. A piezoelectric thin-film resonator comprising:
a supporting substrate;
a piezoelectric thin-film disposed on the supporting substrate; and
a first electrode and a second electrode facing each other with the piezoelectric thin-film therebetween;
wherein a stiffness of at least one of the first and second electrodes is higher than a stiffness of the piezoelectric thin-film;
an insulating film is formed between the piezoelectric thin-film and the supporting substrate; and
the insulating film includes a plurality of insulating thin-films having different temperature coefficients.
2. The piezoelectric thin-film resonator according to claim 1 , wherein the insulating film includes at least one of a Al 2 O 3 , SiO 2 , and SIN.
3. The piezoelectric thin-film resonator according to claim 1 , wherein the piezoelectric thin-film includes at least one of ZnO, AlN , PZT, and CdS.
4. A piezoelectric filter comprising the piezoelectric thin-film resonator according to claim 1 .
5. An electronic component comprising the piezoelectric filter according to claim 4 .
6. The piezoelectric thin-film resonator according to claim 1 , wherein the piezoelectric thin-film resonator has a cantilever structure or an overhang structure.
7. The piezoelectric thin-film resonator according to claim 1 , wherein one of the first electrode and the second electrode includes at least one of Pt, Ir, Ni, Ta, Nb, W, Cu, Mo, Al alloy, and elinvar.
8. The piezoelectric thin-film resonator according to claim 1 , wherein
the difference between a lattice constant in a direction vertical to a vibration direction of the piezoelectric thin-film and the lattice constant in a direction vertical to a vibration direction of a material of the electrode is about 5% or less.
9. The piezoelectric thin-film resonator according to claim 8 , wherein the stiffness of the at least one of the first and second electrodes is higher than the stiffness of the piezoelectric thin-film in a direction that is substantially parallel to a vibration direction of the piezoelectric thin-film.
10. The piezoelectric thin-film resonator according to claim 8 , wherein at least one of the first and second electrodes includes at least one of Ta, Nb, Mo, Pt, W, Cu, Ir, Ni, Al alloy, and elinvar.
11. The piezoelectric thin-film resonator according to claim 8 , wherein the piezoelectric thin-film includes at least one of ZnO, AlN , PZT, and CdS.
12. A piezoelectric filter comprising the piezoelectric thin-film resonator according to claim 8 .
13. An electronic component comprising the piezoelectric filter according to claim 12 .
14. The piezoelectric thin-film resonator according to claim 8 , wherein the piezoelectric thin-film resonator has a cantilever structure or an overhang structure.
15. A piezoelectric filter comprising at least one piezoelectric thin-film resonator according to claim 8 and a balanced-unbalanced conversion function.
16. The filter according to claim 15 , wherein the balance-unbalanced conversion function is provided by a multimode filter.
17. An electronic component comprising the piezoelectric filter according to claim 15 .
18. The piezoelectric thin-film resonator according to claim 8 , wherein the first electrode is disposed between the supporting substrate and the piezoelectric thin-film and includes at least one of Pt and Al.
19. A piezoelectric filter comprising at least one piezoelectric thin-film resonator according to claim 1 and a balanced-unbalanced conversion function.
20. The filter according to claim 19 , wherein the balance-unbalanced conversion function is provided by a multimode filter.
21. An electronic component comprising the piezoelectric filter according to claim 19 .
22. A piezoelectric thin-film resonator comprising:
a supporting substrate;
a piezoelectric thin-film disposed on the supporting substrate; and
a first electrode and a second electrode facing each other with the piezoelectric thin-film therebetween;
wherein a stiffness of at least one of the first and second electrodes is higher than a stiffness of the piezoelectric thin-film;
an insulating film is formed between the piezoelectric thin-film and the supporting substrate; and
the insulating film comprises a plurality of insulating thin-films and wherein at least one of the plurality of insulating thin-films generates compressive stress and at least another of the plurality of insulating thin-films generate tensile stress.
23. The piezoelectric thin-film resonator according to claim 22 , wherein one of the first electrode and the second electrode includes at least one of Pt, Ir, Ni, Ta, Nb, W, Cu, Mo, Al alloy, and elinvar.