Acoustic resonator comprising collar and frame

• US 9,490,771 B2
• Filed: 02/28/2013
• Issued: 11/08/2016
• Est. Priority Date: 10/29/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Burak, Dariusz, Choy, John, Shirakawa, Alexandre, Nikkel, Phil
• Primary Examiner(s): Summons, Barbara
• Assistant Examiner(s): Salazar, Jr., Jorge
• Application Number:
  US13/781,491
• Publication Number:
  US 20140118087A1
• Time in Patent Office: 1,349 Days
• Field of Search: 333/133, 333186-191, 310/324, 310/365
• US Class Current: 1/1
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/02157 Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/171 implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
• CPC Class Codes: H03H 9/173 Air-gaps
• CPC Class Codes: H03H 9/54 comprising resonators of piezoelectric or electrostrictive material H03H9/64 takes precedence
• CPC Class Codes: H03H 9/584 Coupled Resonator Filters [CFR]

Abstract

An acoustic resonator structure comprises a first electrode disposed on a substrate, a piezoelectric layer disposed on the first electrode, a second electrode disposed on the piezoelectric layer, a frame disposed within a main membrane region defined by an overlap between the first electrode, the piezoelectric layer, and the second electrode, and having an outer edge substantially aligned with a boundary of the main membrane region, and a collar formed separate from the frame, disposed outside the main membrane region, and having an inner edge substantially aligned with the boundary of or overlapping the main membrane region.

Claims

1. An acoustic resonator structure, comprising:

an acoustic reflector disposed in or over a substrate;

a first electrode disposed over the substrate;

a piezoelectric layer disposed over the first electrode;

a second electrode disposed over the piezoelectric layer;

a frame disposed within a main membrane region, the membrane defined by an overlap between the first electrode, the piezoelectric layer, the second electrode, and the acoustic reflector, and the frame having an outer edge substantially aligned with a boundary of the main membrane region, wherein the frame is disposed at a bottom portion of the second electrode; and

a collar, which is separate from the frame, disposed adjacent to the main membrane region, and the collar having an inner edge substantially aligned with the boundary of or overlapping the main membrane region.

2. The acoustic resonator structure of claim 1, further comprising an additional frame disposed within the main membrane region and having an outer edge substantially aligned with the boundary of the main membrane region, wherein the additional frame is disposed at a bottom portion of the first electrode.

3. The acoustic resonator structure of claim 1, further comprising an additional frame disposed within the main membrane region and having an outer edge substantially aligned with the boundary of the main membrane region, wherein the additional frame is disposed at a top portion of the bottom first electrode.

4. The acoustic resonator structure of claim 1, wherein the frame is an add-on frame or a composite frame.

5. The acoustic resonator structure of claim 1, wherein the collar comprises borosilicate glass, carbon-doped silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, zinc oxide, lead zirconium titanate, diamond or diamond-like carbon.

6. The acoustic resonator structure of claim 1, wherein the frame comprises a layer of

copper, molybdenum, aluminum, tungsten, iridium, borosilicate glass, carbon-doped silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, zinc oxide, lead zirconium titanate, diamond or diamond-like carbon.

7. The acoustic resonator structure of claim 1, wherein the acoustic reflector is an air cavity located below the first electrode, and the boundary of the main membrane region is defined by an edge of the second electrode above the acoustic reflector.

8. The acoustic resonator structure of claim 1, wherein the collar defines a collar region having a cutoff frequency that is substantially the same as a cutoff frequency of the main membrane region.

9. The acoustic resonator structure of claim 1, wherein the frame defines a frame region and is configured to create at least one of a cut-off frequency mismatch and an acoustic impedance mismatch between the frame region and a center portion of the main membrane region.

10. The acoustic resonator structure of claim 1, further comprising an additional frame connected to the first electrode within the main membrane.

11. The acoustic resonator structure of claim 10, wherein the frame is disposed in a first frame region and is configured to shift a cutoff frequency of the first frame region in a first direction, and wherein the additional frame is disposed in a second frame region and is configured to shift a cutoff frequency of the second frame region in a second direction opposite the first direction.

12. The acoustic resonator of claim 1, wherein the acoustic reflector is disposed between the first electrode and the substrate.

13. An acoustic resonator structure, comprising:

an acoustic stack comprising a piezoelectric layer sandwiched between first and second electrode layers and having a main membrane region defined by an overlap between the first electrode, the piezoelectric layer, the second electrode, and a substrate having an air cavity, wherein the first electrode layer is disposed over the substrate having the air cavity;

a frame disposed within the main membrane region, and between the piezoelectric layer and the second electrode layer, the frame having an outer edge substantially aligned with a boundary of the main membrane region; and

a collar disposed adjacent to the main membrane region, and between the substrate and the first electrode, the collar having an inner edge substantially aligned with the boundary of or overlapping the main membrane region,

wherein the frame and the collar are located at different layers of the acoustic stack.

14. An acoustic resonator structure, comprising:

an acoustic reflector disposed in or over a substrate

a first electrode disposed over a substrate;

a piezoelectric layer disposed over the first electrode;

a second electrode disposed over the piezoelectric layer;

a frame disposed within a main membrane region defined by an overlap between the first electrode, the piezoelectric layer, the second electrode, and the acoustic reflector, the frame having an outer edge substantially aligned with a boundary of the main membrane region; and

a collar, which is separate from the frame, disposed adjacent to the main membrane region, and the collar having an inner edge substantially aligned with the boundary of or overlapping the main membrane region, the collar being disposed between the first electrode and the piezoelectric layer, or between the first electrode and the substrate.

15. The acoustic resonator structure of claim 14, further comprising an additional frame disposed within the main membrane region and having an outer edge substantially aligned with the boundary of the main membrane region, wherein the frame is disposed at a bottom portion of the second electrode and the additional frame is disposed at a bottom portion of the first electrode.

16. The acoustic resonator structure of claim 14, further comprising an additional frame disposed within the main membrane region and having an outer edge substantially aligned with the boundary of the main membrane region, wherein the frame is disposed at a bottom portion of the second electrode and the additional frame is disposed at a top portion of the first electrode.

17. The acoustic resonator structure of claim 14, wherein the frame is an add-on frame or a composite frame.

18. The acoustic resonator structure of claim 14, wherein the collar comprises borosilicate glass, carbon-doped silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, zinc oxide, lead zirconium titanate, diamond or diamond-like carbon.

19. The acoustic resonator structure of claim 14, wherein the frame comprises a layer of

copper, molybdenum, aluminum, tungsten, iridium, borosilicate glass, carbon-doped silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, zinc oxide, lead zirconium titanate, diamond or diamond-like carbon.

20. The acoustic resonator structure of claim 14, wherein the boundary of the main membrane region is defined by an edge of the second electrode above the acoustic reflector.

21. The acoustic resonator structure of claim 14, wherein the collar defines a collar region having a cutoff frequency that is substantially the same as a cutoff frequency of the main membrane region.

22. The acoustic resonator structure of claim 14, wherein the frame defines a frame region and is configured to create at least one of a cut-off frequency mismatch and an acoustic impedance mismatch between the frame region and a center portion of the main membrane region.

23. The acoustic resonator structure of claim 14, further comprising an additional frame connected to the first or second electrode within the main membrane and arranged in a side by side configuration with the frame.

24. The acoustic resonator structure of claim 23, wherein the frame is disposed in a first frame region and is configured to shift a cutoff frequency of the first frame region in a first direction, and wherein the additional frame is disposed in a second frame region and is configured to shift a cutoff frequency of the second frame region in a second direction opposite the first direction.

25. An acoustic resonator structure, comprising:

a first electrode disposed over a substrate;

a piezoelectric layer disposed over the first electrode;

a second electrode disposed over the piezoelectric layer;

a frame disposed within a main membrane region defined by an overlap between the first electrode, the piezoelectric layer, and the second electrode, and the frame having an outer edge substantially aligned with a boundary of the main membrane region;

a collar, which is separate from the frame, disposed adjacent to the main membrane region, and the collar having an inner edge substantially aligned with the boundary of or overlapping the main membrane region; and

a planarization layer disposed over the piezoelectric layer adjacent to the second electrode, wherein the collar is disposed over the planarization layer and the second electrode.