Granted Patent B2

US 12,289,094 · App. 18/193,043 · Granted Apr 29, 2025

Inventors: Ventsislav Yantchev (Sofia, BG); Sho Nagatomo (Nagaokakyo, JP); Kazunori Inoue (Nagaokakyo, JP)

Assignee: MURATA MANUFACTURING CO., LTD.

H03H9/205H03H9/02015H03H9/02157H03H9/02228H03H9/54

Abstract

Claims (36)

1. An acoustic resonator comprising:

a substrate having a surface;

a piezoelectric layer attached to the surface of the substrate either directly or via one or more intermediate layers and having a portion forming a diaphragm over a cavity, with the diaphragm having first and second surfaces;

an interdigital transducer (IDT) having interleaved IDT fingers on the first surface of the diaphragm; and

dielectric fingers on the second surface of the diaphragm, the dielectric fingers being a different material than the interleaved IDT fingers.

2. The acoustic resonator according to claim 1 , wherein the second surface of the diaphragm faces the cavity.

3. The acoustic resonator according to claim 1 , wherein the cavity extends into the substrate.

4. An acoustic resonator comprising:

a substrate having a surface;

a piezoelectric layer attached to the surface of the substrate either directly or via one or more intermediate layers and having a portion forming a diaphragm over a cavity, with the diaphragm having first and second surfaces;

an interdigital transducer (IDT) having interleaved IDT fingers on the first surface of the diaphragm; and

dielectric fingers on the second surface of the diaphragm,

wherein the interleaved IDT fingers have a first thickness and the dielectric fingers have a second thickness, with the first and second thicknesses measured in a direction substantially orthogonal to the surface of the substrate.

5. The acoustic resonator according to claim 4 , wherein the second thickness is greater than the first thickness.

6. The acoustic resonator according to claim 4 , wherein the second thickness is different than the first thickness.

7. The acoustic resonator according to claim 1 , further comprising a first dielectric layer on the first surface of the diaphragm and between the interleaved IDT fingers.

8. The acoustic resonator according to claim 7 , further comprising a second dielectric layer on the second surface of the diaphragm.

9. The acoustic resonator according to claim 8 , wherein the second dielectric layer has a same thickness as the dielectric fingers, which are embedded in the second dielectric layer.

10. The acoustic resonator according to claim 1 , wherein each dielectric finger of the dielectric fingers is aligned with a corresponding IDT finger of the interleaved IDT fingers.

11. The acoustic resonator according to claim 10 , wherein a mass per unit length of each dielectric finger is equal to a mass per unit length of the corresponding IDT finger.

12. The acoustic resonator according to claim 1 , wherein the interleaved IDT fingers have a substantially equal width and thickness as the dielectric fingers.

13. The acoustic resonator according to claim 1 , wherein a pitch of the dielectric fingers on the second surface of the diaphragm is substantially equal to a pitch of the interleaved IDT fingers on the first surface of the diaphragm.

14. The acoustic resonator according to claim 1 , wherein the IDT is configured to excite a primary shear acoustic mode within the piezoelectric layer.

15. A filter device comprising:

a plurality of acoustic resonators each comprising:

a substrate having a surface;

a piezoelectric layer attached to the surface of the substrate either directly or via one or more intermediate layers and having a portion that forms a diaphragm over a cavity, the diaphragm having opposing first and second surfaces;

a conductor pattern having an interdigital transducer (IDT) with interleaved fingers on the first surface of the diaphragm; and

dielectric fingers on the second surface of the diaphragm, the dielectric fingers being a different material than the interleaved fingers.

16. The filter device according to claim 15 , wherein the second surface of each diaphragm faces the cavity of the respective acoustic resonator, which extends into the respective substrate.

17. The filter device according to claim 15 , wherein the interleaved fingers of each of the plurality of acoustic resonators have a first thickness and the dielectric fingers have a second thickness, with the first and second thicknesses measured in a direction normal to the surface of the respective substrate.

18. The filter device according to claim 17 , wherein the second thickness is different than the first thickness.

19. The filter device according to claim 15 , wherein a pitch of the dielectric fingers on the second surface of the diaphragm of each of the plurality of acoustic resonators is substantially equal to a pitch of the interleaved fingers on the first surface of the respective diaphragm.

20. The filter device according to claim 15 ,

wherein each dielectric finger of the dielectric fingers of the diaphragm of each of the plurality of acoustic resonators is aligned with a corresponding finger of the interleaved fingers on the first surface of the respective diaphragm, and

wherein a mass per unit length of each dielectric finger is equal to a mass per unit length of the corresponding finger of the interleaved fingers of the IDT.

Assignments (3)

Continuity (3)

References Cited (239)