Acoustic resonator structure comprising a bridge

• US 8,248,185 B2
• Filed: 06/24/2009
• Issued: 08/21/2012
• Est. Priority Date: 06/24/2009
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies Wireless IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Choy, John, Feng, Chris, Nikkel, Phil
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US12/490,525
• Publication Number:
  US 20100327697A1
• Time in Patent Office: 1,154 Days
• Field of Search: 333187-192, 310/322, 310/324, 310/334, 310/335, 310/365
• US Class Current: 333/187
• 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 9/173 Air-gaps

Abstract

An acoustic resonator comprises a first electrode a second electrode and a piezoelectric layer disposed between the first and second electrodes. The acoustic resonator further comprises a reflective element disposed beneath the first electrode, the second electrode and the piezoelectric layer. An overlap of the reflective element, the first electrode, the second electrode and the piezoelectric layer comprises an active area of the acoustic resonator. The acoustic resonator also comprises a bridge adjacent to a termination of the active area of the acoustic resonator.

Claims

1. An acoustic resonator, comprising:

a first electrode;

a second electrode;

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, an 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.

2. An acoustic resonator as claimed in claim 1, further comprising an electrical connection to one of a plurality of sides of the second electrode, wherein the bridge is disposed between the connection and the one side of the second electrode.

3. An acoustic resonator as claimed in claim 1, wherein adjacent to termination of the active area of the acoustic resonator, the piezoelectric layer comprises a transition comprising defects.

4. An acoustic resonator as claimed in claim 3, wherein the second electrode does not contact the transition.

5. An acoustic resonator as claimed in claim 1, wherein the bridge comprises a gap.

6. An acoustic resonator as claimed in claim 5, wherein the gap comprises a region between the second electrode and the piezoelectric layer.

7. An acoustic resonator as claimed in claim 6, wherein adjacent to termination of the active area of the acoustic resonator, the piezoelectric layer comprises a transition comprising defects, and the transition is disposed beneath the region of the gap.

8. An acoustic resonator as claimed in claim 1, wherein the second electrode comprises an upper surface with a side and a recess is disposed along the side.

9. An acoustic resonator as claimed in claim 1, wherein the second electrode comprises an upper surface with a side, and a frame element is disposed along the side.

10. A film bulk acoustic resonator (FBAR), comprising:

a first electrode;

a second electrode;

a piezoelectric layer disposed between the first and second electrodes;

a cavity disposed beneath the first electrode, the second electrode and the piezoelectric layer, an overlap of the cavity, 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 cavity, 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.

11. An FBAR as claimed in claim 10, further comprising an electrical connection to one of a plurality of sides of the second electrode, wherein the bridge is disposed between the connection and the one side of the second electrode.

12. An FBAR as claimed in claim 10, wherein adjacent to termination of the active area of the acoustic resonator, the piezoelectric layer comprises a transition comprising defects.

13. An FBAR as claimed in claim 12, wherein the second electrode does not contact the transition.

14. An FBAR as claimed in claim 10, wherein the bridge comprises a gap.

15. An FBAR as claimed in claim 14, wherein the gap comprises a region between the second electrode and the piezoelectric layer.

16. An FBAR as claimed in claim 15, wherein adjacent to termination of the active area of the acoustic resonator, the piezoelectric layer comprises a transition comprising defects, and the transition is disposed beneath the region of the gap.

17. An FBAR as claimed in claim 10, wherein the second electrode comprises an upper surface with a side and a recess is disposed along the side.

18. An FBAR as claimed in claim 10, wherein the second electrode comprises an upper surface with a side, and a frame element is disposed along the side.

19. An FBAR as claimed in claim 10, further comprising a low acoustic impedance material beneath the bridge.

20. A filter element comprising an acoustic resonator, the acoustic resonator comprising:

a first electrode;

a second electrode;

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, an 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.