Acoustic resonator comprising integrated structures for improved performance

• US 9,748,918 B2
• Filed: 11/27/2013
• Issued: 08/29/2017
• Est. Priority Date: 02/14/2013
• 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, Nikkel, Phil, Grannen, Kevin J.
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US14/092,793
• Publication Number:
  US 20140225683A1
• Time in Patent Office: 1,371 Days
• Field of Search: 333187, 333189, 310346-349
• CPC Class Codes: H03H 9/02102 of temperature influence cutting angles H03H9/02015
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/173 Air-gaps

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, and an air cavity disposed in the substrate below at least a portion of a main membrane region defined by an overlap between the first electrode. The acoustic resonator structure may further comprise various integrated structures at or around the main membrane region to improve its electrical performance.

Claims

1. An acoustic resonator structure comprising:

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;

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;

a temperature compensation feature having a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer, the first electrode, and the second electrode; and

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

2. The acoustic resonator structure of claim 1, wherein the frame is disposed at a bottom portion of the second electrode.

3. The acoustic resonator structure of claim 1, wherein the piezoelectric layer is doped with at least one rare earth element for offsetting at least a portion of degradation of an electromechanical coupling coefficient of the acoustic resonator structure caused by the temperature compensation feature having the positive temperature coefficient.

4. The acoustic resonator structure of claim 1, wherein the temperature compensation feature comprises a temperature compensation layer embedded in the first electrode.

5. The acoustic resonator structure of claim 1, wherein the temperature compensation feature comprises a temperature compensation layer embedded in the second electrode.

6. The acoustic resonator structure of claim 1, wherein the temperature compensation feature comprises a temperature compensation layer embedded in the piezoelectric layer.

7. An acoustic resonator structure comprising:

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;

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; and

a temperature compensation feature having a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer, the first electrode, and the second electrode, wherein

the frame is disposed at a bottom portion of the second electrode.

8. The acoustic resonator structure of claim 7, further comprising a planarization layer disposed on the piezoelectric layer adjacent to the second electrode, wherein the collar is disposed on the planarization layer and the second electrode.

9. The acoustic resonator structure of claim 7, wherein the collar is disposed between the first electrode and the piezoelectric layer.

10. The acoustic resonator structure of claim 7, wherein the collar is disposed between the first electrode and the substrate.

11. The acoustic resonator structure of claim 7, wherein the piezoelectric layer is doped with at least one rare earth element for offsetting at least a portion of degradation of an electromechanical coupling coefficient of the acoustic resonator structure caused by the temperature compensation feature having the positive temperature coefficient.

12. The acoustic resonator structure of claim 7, wherein the temperature compensation feature comprises a temperature compensation layer embedded in the first electrode.

13. The acoustic resonator structure of claim 7, wherein the temperature compensation feature comprises a temperature compensation layer embedded in the piezoelectric layer.

14. An acoustic resonator structure comprising:

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;

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; and

a temperature compensation feature having a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer, the first electrode, and the second electrode, wherein

the frame is disposed at a bottom portion of the first electrode.

15. The acoustic resonator structure of claim 14, wherein the temperature compensation feature comprises a temperature compensation layer embedded in the second electrode.

16. The acoustic resonator structure of claim 14, further comprising a planarization layer disposed on the piezoelectric layer adjacent to the second electrode, wherein the collar is disposed on the planarization layer and the second electrode.

17. The acoustic resonator structure of claim 14, wherein the collar is disposed between the first electrode and the piezoelectric layer.

18. The acoustic resonator structure of claim 14, wherein the collar is disposed between the first electrode and the substrate.

19. The acoustic resonator structure of claim 14, wherein the piezoelectric layer is doped with at least one rare earth element for offsetting at least a portion of degradation of an electromechanical coupling coefficient of the acoustic resonator structure caused by the temperature compensation feature having the positive temperature coefficient.