Acoustic resonator structure having an electrode with a cantilevered portion

• US 9,520,856 B2
• Filed: 01/27/2014
• Issued: 12/13/2016
• Est. Priority Date: 06/24/2009
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Choy, John, Feng, Chris, Nikkel, Phil
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US14/165,301
• Publication Number:
  US 20140139077A1
• Time in Patent Office: 1,051 Days
• Field of Search: 333187-192, 310/334, 310/335
• US Class Current: 1/1
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/02149 of ageing changes of characteristics, e.g. electro-acousto-migration
• 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 9/706 Duplexers

Abstract

An acoustic resonator comprises a first electrode and second electrode comprising a plurality of sides. At least one of the sides of the second electrode comprises a cantilevered portion. A piezoelectric layer is disposed between the first and second electrodes. A bridge disposed adjacent to one of the sides of the second electrode.

Claims

1. An acoustic resonator, comprising:

a first electrode;

a second electrode comprising a plurality of sides, at least one of the plurality of sides comprising a cantilevered portion, wherein the second electrode comprises a first surface disposed substantially at a first height, and the cantilevered portion comprises a second surface disposed substantially at a second height, which is higher than the first height;

a piezoelectric layer disposed between the first and second electrodes, the cantilevered portion extending above the piezoelectric layer, wherein a gap exists between the cantilevered portion and the piezoelectric layer, wherein the piezoelectric layer extends over an edge of the first electrode; and

a bridge disposed adjacent to one of the sides of the second electrode.

2. The acoustic resonator as claimed in claim 1, further comprising a reflective element disposed beneath the first electrode, the second electrode and the piezoelectric layer, wherein a contacting overlap of the reflective element, the first electrode, the second electrode and the piezoelectric layer comprises an active area of the acoustic resonator, and the bridge is disposed adjacent to the active area of the acoustic resonator.

3. The acoustic resonator as claimed in claim 2, wherein the cantilevered portion of the second electrode extends beyond a termination of the active area.

4. The acoustic resonator as claimed in claim 2, further comprising a frame element.

5. The acoustic resonator as claimed in claim 4, wherein the frame element is a recessed frame element.

6. The acoustic resonator claimed in claim 4, wherein the frame element comprises a raised frame element.

7. The acoustic resonator as claimed in claim 1, wherein the gap is a first gap, and the bridge comprises a second gap, which exists in a region between the second electrode and the piezoelectric layer.

8. The acoustic resonator as claimed in claim 1, wherein all but one of the plurality of sides of the second electrode comprises a cantilevered portion.

9. The acoustic resonator as claimed in claim 8, further comprising an electrical connection to the one of the plurality of sides of the second electrode that does not comprise a cantilevered portion.

10. The acoustic resonator as claimed in claim 9, wherein the electrical connection is made to the one of the plurality of sides of the second electrode that is connected to the bridge.

11. The acoustic resonator of claim 1, wherein the bridge comprises a third surface disposed substantially at a third height, and the third height is higher than the first height.

12. An acoustic resonator, comprising:

a first electrode;

a second electrode comprising a plurality of sides, at least one of the plurality of sides comprising a cantilevered portion, wherein the second electrode comprises a first surface disposed substantially at first height, and the cantilevered portion comprises a second surface disposed substantially at a second height, which is higher than the first height;

a piezoelectric layer disposed between the first and second electrodes;

a reflective element disposed beneath the first electrode, the second electrode and the piezoelectric layer, a contacting overlap of the reflective element, the first electrode, the second electrode and the piezoelectric layer defining an active area of the acoustic resonator, wherein the first electrode substantially covers the reflective element, and the piezoelectric layer extends over an edge of the first electrode; and

a bridge adjacent to a termination of the active area of the acoustic resonator, wherein the bridge overlaps a portion of the first electrode.

13. An acoustic resonator as claimed in claim 12, wherein the cantilevered portion of the second electrode extends beyond a termination of the active area.

14. An acoustic resonator as claimed in claim 12, further comprising a frame element.

15. An acoustic resonator as claimed in claim 14, wherein the frame element is a recessed frame element.

16. An acoustic resonator as claimed in claim 14, wherein the frame element comprises a raised frame element.

17. An acoustic resonator as claimed in claim 12, wherein the bridge comprises a gap, and the gap exists in a region between the second electrode and the piezoelectric layer.

18. An acoustic resonator as claimed in claim 12, wherein the bridge comprises a third surface disposed substantially at a third height, and the third height is higher than the first height.

19. An acoustic resonator as claimed in claim 12, wherein all but one of the plurality of sides of the second electrode comprise the cantilevered portion.

20. An acoustic resonator as claimed in claim 19, further comprising an electrical connection to the one of the plurality of sides of the second electrode that does not comprise a cantilevered portion.

21. An acoustic resonator as claimed in claim 20, wherein the electrical connection is made to the one of the plurality of sides of the second electrode that is connected to the bridge.

22. An acoustic resonator, comprising:

a first electrode;

a second electrode comprising a plurality of sides, at least one of the plurality of sides comprising a cantilevered portion, wherein the second electrode comprises a first surface disposed substantially at a first height, and the cantilevered portion comprises a second surface disposed substantially at a second height, which is higher than the first height; and

a piezoelectric layer disposed between the first and second electrodes, the cantilevered portion extending above the piezoelectric layer, wherein a gap exists between the cantilevered portion and the piezoelectric layer, wherein the piezoelectric layer extends over an edge of the first electrode.

23. The acoustic resonator as claimed in claim 22, further comprising a reflective element disposed beneath the first electrode, the second electrode and the piezoelectric layer, wherein a contacting overlap of the reflective element, the first electrode, the second electrode and the piezoelectric layer comprises an active area of the acoustic resonator, and a bridge is disposed adjacent to the active area of the acoustic resonator.

24. The acoustic resonator as claimed in claim 23, wherein the cantilevered portion of the second electrode extends beyond a termination of the active area.

25. The acoustic resonator as claimed in claim 23, further comprising a frame element.

26. The acoustic resonator as claimed in claim 25, wherein the frame element is a recessed frame element.

27. The acoustic resonator claimed in claim 25, wherein the frame element comprises a raised frame element.

28. The acoustic resonator as claimed in claim 22, wherein all but one of the plurality of sides of the second electrode comprises a cantilevered portion.

29. The acoustic resonator as claimed in claim 28, further comprising an electrical connection to the one of the plurality of sides of the second electrode that does not comprise a cantilevered portion.