Piezoelectric resonator, filter and electronic component using the same
First Claim
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, andwherein 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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Accused Products
Abstract
A piezoelectric resonator includes; a lower electrode 24 formed on a substrate 11; a piezoelectric film 23 formed on the lower electrode 24; an upper electrode 25 formed on the piezoelectric film 23 and obtaining, in collaboration with the lower electrode 24, a signal having a predetermined resonance frequency by a propagation of a bulk acoustic wave inside the piezoelectric film 23; and an acoustic multilayer reflective film 28 including an SiO2 film 28a having a predetermined acoustic impedance and an AIN film 28b having an acoustic impedance higher than the SiO2 film 28a, and reflecting the bulk acoustic wave, the SiO2 film 28a and the AIN film 28b being alternately stacked on the upper electrode 25, and the SiO2 film 28a being in contact with the upper electrode 25.
16 Citations
19 Claims
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1. A piezoelectric resonator comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A piezoelectric resonator comprising:
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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 assuming that the wavelength of the bulk acoustic wave is λ
, the thickness of the first acoustic film falls within the range of 0.18 λ
to 0.225 λ
, and that of the second acoustic film falls within the range of 0.05 λ
to 0.225 λ
, andwherein 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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19. A piezoelectric resonator having a single piezoelectric film, the piezoelectric resonator comprising:
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a first electrode film formed on a substrate; the single 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 oscillation energy confining film substantially eliminates oscillation of the piezoelectric resonator, wherein the resonance frequency of the second acoustic film is higher than the resonance frequency of the first acoustic film, 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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Specification