Acoustic wave device

Patent metadata

Field	Value
Publication number	US-12451865-B2
Application number	US-202318510873-A
Country	US
Kind code	B2
Filing date	Nov 16, 2023
Priority date	May 17, 2021
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

An acoustic wave device is provided that includes a piezoelectric layer and first and second resonators. The first resonator includes a first functional electrode and a first dielectric film on the piezoelectric layer. The second resonator includes a second functional electrode and a second dielectric film on the piezoelectric layer. The piezoelectric layer includes first and second resonator portions respectively including portions of the first and second resonators. Moreover, a resonant frequency of the first resonator is lower than that of the second resonator. A thickness of the first resonator portion is greater than that of the second resonator portion, and ts 1 /tp 1 ≤ts 2 /tp 2 is satisfied, where tp 1 , tp 2 , ts 1 , and ts 2 are respectively thicknesses of the first and second resonator portions and the first and second dielectric films.

First claim

What is claimed:

1. An acoustic wave device comprising:
a first resonator including:
a piezoelectric substrate including a piezoelectric layer;
a first functional electrode on the piezoelectric layer; and
a first dielectric film on the piezoelectric layer and covering the first functional electrode; and

a second resonator that includes the piezoelectric layer, the second resonator including:
a second functional electrode on the piezoelectric layer; and
a second dielectric film on the piezoelectric layer and covering the second functional electrode,

wherein the piezoelectric layer includes a first resonator portion and a second resonator portion, a portion of the first resonator being in the first resonator portion, a portion of the second resonator being in the second resonator portion;
wherein a resonant frequency of the first resonator is lower than a resonant frequency of the second resonator and, in the piezoelectric layer, a thickness of the first resonator portion is greater than a thickness of the second resonator portion, and
wherein ts 1 /tp 1 ≤ts 2 /tp 2 , where tp 1 is the thickness of the first resonator portion, tp 2 is the thickness of the second resonator portion, ts 1 is a thickness of the first dielectric film, and tp 2 is a thickness of the second dielectric film.

2. The acoustic wave device according to claim 1 , wherein the first resonator and the second resonator are configured to use a thickness resonance mode.

3. The acoustic wave device according to claim 1 , wherein ts 1 /tp 1 =ts 2 /tp 2 .

4. The acoustic wave device according to claim 1 , wherein the first dielectric film of the first resonator and the second dielectric film of the second resonator comprise a same dielectric material.

5. The acoustic wave device according to claim 1 , wherein the first dielectric film of the first resonator and the second dielectric film of the second resonator comprise different dielectric materials.

6. The acoustic wave device according to claim 1 , wherein the piezoelectric layer comprises lithium tantalate or lithium niobate.

7. The acoustic wave device according to claim 6 , wherein the first resonator and the second resonator are configured to use bulk waves in a thickness-shear mode that is a thickness resonance mode.

8. The acoustic wave device according to claim 7 , wherein:
Euler angles (φ, θ, ψ) of the piezoelectric layer are within one of the ranges represented by the following expressions (1), (2), and (3):
(0°±10°, 0° to 20°, ψ of any value)  (1);

(0°±10°, 20° to 80°, 0° to 60°(1−(θ−50) 2 /900) 1/2 ) or (0°±10°, 20° to 80°, [180°−60° (1−(θ−50) 2 /900) 1/2 ] to 180°)   (2); and

(0°±10°, [180°−30°(1−(ψ−90) 2 /8100) 1/2 ] to 180°, ψ of any value)  (3).

9. The acoustic wave device according to claim 6 , wherein:
each of the first functional electrode and the second functional electrode includes at least one pair of electrodes, and
the piezoelectric substrate includes a support and the piezoelectric layer on the support.

10. The acoustic wave device according to claim 9 , further comprising a first acoustic reflector and a second acoustic reflector disposed in the support, with the first acoustic reflector overlapping at least a portion of the first functional electrode in a plan view, and the second acoustic reflector overlapping at least a portion of the second functional electrode in the plan view.

11. The acoustic wave device according to claim 10 , wherein the first resonator and the second resonator each satisfy a condition where d/p is less than or equal to 0.5, where d represents a thickness of the piezoelectric layer and p represents a distance between centers of adjacent electrodes of the at least one pair of electrodes, respectively.

12. The acoustic wave device according to claim 11 , wherein d/p is less than or equal to about 0.24.

13. The acoustic wave device according to claim 11 , wherein, in each of the first functional electrode and the second functional electrode, an excitation region is a region where the adjacent electrodes overlap each other in a direction in which the adjacent electrodes face-to-face.

14. The acoustic wave device according to claim 13 , wherein MR≤1.75(d/p)+0.075, where MR is a metallization ratio of the at least one pair of the electrodes to the excitation region.

15. The acoustic wave device according to claim 10 , wherein each of the first acoustic reflector and the second acoustic reflector is a cavity.

16. The acoustic wave device according to claim 10 , wherein each of the first acoustic reflector and the second acoustic reflector are at least one Bragg reflector.

17. An acoustic wave device comprising:
a first resonator including at least one piezoelectric layer, a first electrode on the at least one piezoelectric layer, and a first dielectric film on the at least one piezoelectric layer and the first electrode; and
a second resonator including the at least one piezoelectric layer, a second electrode on the at least one piezoelectric layer, and a second dielectric film on the at least one piezoelectric layer and the second electrode,
wherein the at least one piezoelectric layer includes a first resonator portion tp 1 that includes the first resonator and a second resonator portion tp 2 that includes the second resonator,
wherein a thickness of the first resonator portion tp 1 is greater than a thickness of the second resonator portion tp 2 , and
wherein ts 1 /tp 1 ≤ts 2 /tp 2 , where ts 1 is a thickness of the first dielectric film, and tp 2 is a thickness of the second dielectric film.

18. The acoustic wave device according to claim 17 ,
wherein a resonant frequency of the first resonator is lower than a resonant frequency of the second resonator,
wherein the first resonator and the second resonator are configured to use a thickness resonance mode.

19. The acoustic wave device according to claim 17 , wherein:
each of the first electrode and the second electrode includes at least one pair of electrodes, and
wherein the first resonator and the second resonator each satisfy a condition where d/p is less than or equal to about 0.5, where d represents a thickness of the at least one piezoelectric layer and p represents a distance between centers of adjacent electrodes of the at least one pair of electrodes, respectively.

20. The acoustic wave device according to claim 19 , wherein d/p is less than or equal to about 0.24.

Assignees

• Murata Manufacturing Co

Inventors

• Nagatomo Sho
• Garcia Bryant
• Yantchev Ventsislav
• Turner Patrick
• Hammond Robert B
• Jachowski Douglas

Classifications

• H03H9/02157

  Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness · CPC title

• H03H9/02015

  Characteristics of piezoelectric layers, e.g. cutting angles · CPC title

• H03H2003/0442

  of a non-piezoelectric layer · CPC title

• H03H9/568

  consisting of a ladder configuration · CPC title

• H03H9/174

  Membranes · CPC title