| US 7,348,714 B2 | ||
| Piezoelectric resonator, filter and electronic component using the same | ||
| Kenji Inoue, Tokyo (Japan); and Hisatoshi Saitou, Tokyo (Japan) | ||
| Assigned to TDK Corporation, Chuo-ku, Tokyo (Japan) | ||
| Filed on Jul. 29, 2004, as Appl. No. 10/901,382. | ||
| Claims priority of application No. 2003-205137 (JP), filed on Jul. 31, 2003. | ||
| Prior Publication US 2005/0023932 A1, Feb. 03, 2005 | ||
| Int. Cl. H01L 41/04 (2006.01); H01L 41/08 (2006.01) | ||
| U.S. Cl. 310—335 [310/334; 333/187; 333/189] | 19 Claims |
| 1. A piezoelectric resonator comprising:
a first electrode film formed on a substrate;
a piezoelectric film formed on the first electrode film;
a second electrode film formed on the piezoelectric film and obtaining, in collaboration with the first electrode film, a
signal having a predetermined resonance frequency by a propagation of a bulk acoustic wave inside the piezoelectric film;
and
an oscillation energy confining film including a first acoustic film having a predetermined acoustic impedance and a second
acoustic film having an acoustic impedance higher than the first acoustic film, and reflecting the bulk acoustic wave, the
first acoustic film and the second acoustic film being alternately stacked on the second electrode film, and the first acoustic
film being in contact with the second electrode film,
wherein the resonance frequency of the second acoustic film is higher than the resonance frequency of the first acoustic film,
wherein the oscillation energy confining film substantially eliminates loss of oscillation energy of the piezoelectric resonator,
and
wherein a thickness of at least one of the first acoustic film and the second acoustic film is selected to optimize a temperature
characteristic and a Q-value of said resonator.
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