RESONATOR AND RESONANT DEVICE

• US 20200136587A1
• Filed: 12/31/2019
• Published: 04/30/2020
• Est. Priority Date: 08/16/2017
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Inoue, Yoshihisa, Kawai, Ryota
• Granted Patent: US 11,368,141 B2
• Time in Patent Office: Days
• CPC Class Codes: H03H 9/02157 Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness
• CPC Class Codes: H03H 9/02259 Driving or detection means
• CPC Class Codes: H03H 9/02338 Suspension means
• CPC Class Codes: H03H 9/02393 Post-fabrication trimming of parameters, e.g. resonance frequency, Q factor
• CPC Class Codes: H03H 9/02448 of temperature influence
• CPC Class Codes: H03H 9/0595 the holder support and resonator being formed in one body
• CPC Class Codes: H03H 9/1035 the enclosure being defined by two sealing substrates sandwiching the piezoelectric layer of the BAW device
• CPC Class Codes: H03H 9/1057 for microelectro-mechanical devices
• CPC Class Codes: H03H 9/2457 Clamped-free beam resonators
• CPC Class Codes: H03H 9/2489 with more than two fork tines

Abstract

A resonator is provided that includes a base, and three or more vibrating arms each including a first and second electrodes and a piezoelectric film disposed therebetween and having a top surface facing the first electrode. The piezoelectric film vibrates in a predetermined vibration mode when a voltage is applied between the first and second electrodes. Moreover, the three or more vibrating arms include two first arms each located on an outermost side in a direction in which the three or more vibrating arms are arranged and that vibrate in a same phase, and one or more second arms disposed between the two first arms. Each first arm is greater in mass than each second arm.

Claims

1. A resonator comprising:

a base; and

three or more vibrating arms that are each coupled to the base and extend in a same direction away from the base, with each vibrating arm including a first electrode, a second electrode, and a piezoelectric film disposed between the first and second electrodes and configured to vibrate in a predetermined vibration mode when a voltage is applied between the first and second electrodes,

wherein the three or more vibrating arms include two first arms each positioned on an outermost side in a direction in which the three or more vibrating arms extend and are configured to vibrate in a same phase, and at least one second arm disposed between the two first arms, and

wherein each of the two first arm has a greater mass than each of the at least one second arm.

2. The resonator according to claim 1, wherein the three or more vibrating arms each comprise a fixed end coupled to a first end of the base and a free end that extends in a direction away from the fixed end.

3. The resonator according to claim 1, wherein each of the two first arms is greater in mass at a distal end than each of the at least one second arm.

4. The resonator according to claim 1, wherein each of the two first arms is greater in thickness at least at a distal end than each of the at least one second arm.

5. The resonator according to claim 3, further comprising:

an adjusting film disposed to face the piezoelectric film with the first electrode interposed between the adjusting film and the piezoelectric film and exposed at least at the distal end in each of the three or more vibrating arms,

wherein the adjusting film disposed in each of the two first arms comprises a greater thickness than the adjusting film disposed in each of the at least one second arm.

6. The resonator according to claim 4, further comprising:

an adjusting film disposed to face the piezoelectric film with the first electrode interposed between the adjusting film and the piezoelectric film and exposed at least at the distal end in each of the three or more vibrating arms,

wherein the adjusting film disposed in each of the two first arms comprises a greater thickness than the adjusting film disposed in each of the at least one second arm.

7. The resonator according to claim 3, further comprising:

a protective film disposed to face the piezoelectric film with the first electrode interposed between the protective film and the piezoelectric film and provided over a range from the three or more vibrating arms to the base; and

an adjusting film exposed at least at the distal end in each of the three or more vibrating arms,

wherein the adjusting film disposed in each of the two first arms comprises a greater thickness than the adjusting film disposed in each of the at least one second arm.

8. The resonator according to claim 7, wherein an inner end of the adjusting film is less than an outer end of the adjusting film in the direction in which the three or more vibrating arms are arranged.

9. The resonator according to claim 4, further comprising:

a protective film disposed to face the piezoelectric film with the first electrode interposed between the protective film and the piezoelectric film and provided over a range from the three or more vibrating arms to the base; and

an adjusting film exposed at least at the distal end in each of the three or more vibrating arms,

wherein the adjusting film disposed in each of the two first arms comprises a greater thickness than the adjusting film disposed in each of the at least one second arm.

10. The resonator according to claim 9, wherein an inner end of the adjusting film is less than an outer end of the adjusting film in the direction in which the three or more vibrating arms are arranged.

11. The resonator according to claim 10, wherein the adjusting films disposed on each of the three or more vibrating arms have a tapered shaped.

12. The resonator according to claim 7, wherein the adjusting film comprises a material having a rate of reduction in mass caused by etching that is higher than a rate of reduction in mass of the protective film caused by etching.

13. The resonator according to claim 5, wherein the protective film is an electrically insulating material, and the adjusting film is a metal.

20. A resonant device comprising:

the resonator according to claim 1;

a lid element covering the resonator; and

an outer electrode.

14. A resonator comprising:

a base; and

a plurality of vibrating arms that are each coupled to the base and extend therefrom, with each vibrating arm including a first electrode, a second electrode, and a piezoelectric film disposed between the first and second electrodes and configured to vibrate in a predetermined vibration mode when a voltage is applied between the first and second electrodes,

wherein the plurality of vibrating arms include a pair of outer vibrating arms that are positioned on outermost sides of the plurality of vibrating arms and that are configured to vibrate in a same phase, and at least one inner vibrating arm disposed between the pair of outer vibrating arms, and

wherein a mass of each of the outer vibrating arms is greater than a mass of the at least one inner vibrating arm.

15. The resonator according to claim 14, wherein the plurality of vibrating arms each comprise a fixed end coupled to a first end of the base and a free end that extends in a direction away from the fixed end.

16. The resonator according to claim 14, wherein each of the pair of outer vibrating arms is greater in mass at a distal end than the at least one inner vibrating arm.

17. The resonator according to claim 14, wherein each of the pair of outer vibrating arms is greater in thickness at least at a distal end than the at least one inner vibrating arm.

18. The resonator according to claim 16, further comprising:

an adjusting film disposed to face the piezoelectric film with the first electrode interposed between the adjusting film and the piezoelectric film and exposed at least at the distal end in each of the plurality of vibrating arms,

wherein the adjusting film disposed in each of the pair of outer vibrating arms comprises a greater thickness than the adjusting film disposed in the at least one inner vibrating arm.

19. The resonator according to claim 16, further comprising:

a protective film disposed to face the piezoelectric film with the first electrode interposed between the protective film and the piezoelectric film and provided over a range from the plurality of vibrating arms to the base; and

an adjusting film exposed at least at the distal end in each of the plurality of vibrating arms,

wherein the adjusting film disposed in each of the pair of outer vibrating arms comprises a greater thickness than the adjusting film disposed in the at least one inner vibrating arm.