Coupled resonator filter comprising a bridge and frame elements

• US 9,148,117 B2
• Filed: 06/24/2011
• Issued: 09/29/2015
• Est. Priority Date: 02/28/2011
• 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, Shirakawa, Alexandre, Feng, Chris, Nikkel, Phil, Bader, Stefan
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US13/167,939
• Publication Number:
  US 20120218058A1
• Time in Patent Office: 1,558 Days
• Field of Search: 333187-189, 310/312, 310321-324, 310/334, 310/335, 310/366
• US Class Current: 1/1
• CPC Class Codes: H03H 3/04 for obtaining desired frequency or temperature coefficient
• CPC Class Codes: H03H 9/02007 of bulk acoustic wave devices
• CPC Class Codes: H03H 9/0211 of reflections
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/584 Coupled Resonator Filters [CFR]
• CPC Class Codes: H03H 9/587 Air-gaps
• CPC Class Codes: H03H 9/589 Acoustic mirrors

Abstract

In accordance with a representative embodiment, a bulk acoustic wave (BAW) resonator structure, comprises: a first BAW resonator comprising a first lower electrode, a first upper electrode and a first piezoelectric layer disposed between the first lower electrode and the first upper electrode; a second BAW resonator comprising a second lower electrode, a second upper electrode and a second piezoelectric layer disposed between the second lower electrode and the second upper electrode; an acoustic coupling layer disposed between the first BAW resonator and the second BAW resonator; and a bridge disposed between the first lower electrode of the first BAW resonator and the second upper electrode of the second BAW resonator. An inner raised region or an outer raised region, or both are disposed over the second upper electrode.

Claims

1. A bulk acoustic wave (BAW) resonator structure, comprising:

a first BAW resonator comprising a first lower electrode, a first upper electrode and a first piezoelectric layer disposed between the first lower electrode and the first upper electrode;

a second BAW resonator comprising a second lower electrode, a second upper electrode and a second piezoelectric layer disposed between the second lower electrode and the second upper electrode;

an acoustic coupling layer disposed between the first BAW resonator and the second BAW resonator;

a bridge disposed between the first lower electrode of the first BAW resonator and the second upper electrode of the second BAW resonator;

an inner raised region disposed over the second upper electrode and at an inner portion of the second upper electrode, wherein the inner raised region comprises an electrically conductive material and

an outer raised region disposed over the second upper electrode, the outer raised region comprising a conductive material.

2. A BAW resonator structure as claimed in claim 1 further comprising a gap defined between the inner raised region and the outer raised region.

3. A BAW resonator structure as claimed in claim 2, wherein the gap has a width of approximately 1 μ

m to approximately 10 μ

m.

4. A BAW resonator structure as claimed in claim 1, wherein the conductive material of the inner raised region and the outer raised region is the same as a conductive material of the first lower electrode, the first upper electrode, the second lower electrode or the second upper electrode.

5. A BAW resonator structure as claimed in claim 1, wherein the conductive material of the inner raised region and the outer raised region comprises one of tungsten (W), molybdenum (Mo) and copper (Cu).

6. A BAW resonator structure as claimed in claim 1, wherein the inner raised region has a thickness of about 50 Å

to about 500 Å

, and the outer raised region has a thickness of approximately 500 Å

to approximately 5000 Å

.

7. A BAW resonator structure as claimed in claim 1, wherein the BAW resonator structure has a first perimeter bounding an active region of the BAW resonator structure, the bridge is disposed along the first perimeter, and the inner raised region is disposed over the active region.

8. A BAW resonator structure as claimed in claim 1, wherein the BAW resonator has a-perimeter, and the bridge is disposed along the perimeter.

9. A BAW resonator structure as claimed in claim 1, further comprising a fill material disposed in the bridge.

10. A BAW resonator structure as claimed in claim 1, wherein the bridge has a trapezoidal cross-sectional shape.

11. A BAW resonator structure as claimed in claim 1, wherein the first BAW resonator comprises a first film bulk acoustic wave resonator (FBAR) and the second BAW resonator comprises a second FBAR.

12. A BAW resonator structure as claimed in claim 1, wherein the BAW resonator structure comprises a solidly mounted resonator (SMR).

13. A BAW resonator structure as claimed in claim 1, wherein the inner portion of the second upper electrode is disposed at substantially a geometric center of the second upper electrode.

14. A bulk acoustic wave (BAW) resonator structure, comprising:

a first BAW resonator comprising a first lower electrode, a first upper electrode and a first piezoelectric layer disposed between the first lower electrode and the first upper electrode;

a second BAW resonator comprising a second lower electrode, a second upper electrode and a second piezoelectric layer disposed between the second lower electrode and the second upper electrode;

an acoustic coupling layer disposed between the first BAW resonator and the second BAW resonator;

a bridge disposed between the first lower electrode of the first BAW resonator and the second upper electrode of the second BAW resonator;

an outer raised region disposed over the second upper electrode; and

an inner raised region having a thickness, wherein a gap exists between the inner raised region and the outer raised region, the gap having a width that is selected to be inversely proportional to the thickness of the inner raised region.

15. A BAW resonator structure as claimed in claim 14, wherein the outer raised region comprises a conductive material.

16. A BAW resonator structure as claimed in claim 15, wherein the conductive material of the outer raised region is the same as a conductive material of the first lower electrode, the first upper electrode, the second lower electrode or the second upper electrode.

17. A BAW resonator structure as claimed in claim 15, wherein the conductive material of the outer raised region comprises one of tungsten (W), molybdenum (Mo) and copper (Cu).

18. A BAW resonator structure as claimed in claim 14, wherein the outer raised region comprises a dielectric material.

19. A BAW resonator structure as claimed in claim 18, wherein the dielectric material of the outer raised region comprises one of silicon dioxide (SiO₂), silicon nitride (SiN), silicon carbide (SiC), zinc oxide (ZnO), aluminum nitride (AlN) and lead zirconium titanate (PZT).

20. A BAW resonator structure as claimed in claim 14, wherein the outer raised region has a thickness of approximately 500 Å

to approximately 5000 Å

.

21. A BAW resonator structure as claimed in claim 14, wherein the BAW resonator structure has a perimeter bounding an active region of the BAW resonator structure, the bridge is disposed along the perimeter, and the outer raised region overlaps a portion of the active region.

22. A bulk acoustic wave (BAW) resonator structure, comprising:

a first BAW resonator comprising a first lower electrode, a first upper electrode and a first piezoelectric layer disposed between the first lower electrode and the first upper electrode;

a second BAW resonator comprising a second lower electrode, a second upper electrode and a second piezoelectric layer disposed between the second lower electrode and the second upper electrode;

an acoustic coupling layer disposed between the first BAW resonator and the second BAW resonator;

a first bridge disposed between the first lower electrode of the first BAW resonator and the second upper electrode of the second BAW resonator;

a second bridge disposed between the first upper electrode of the first BAW resonator and the second lower electrode of the second BAW resonator; and

an inner raised region disposed over the second upper electrode.

23. A BAW resonator structure as claimed in claim 22, further comprising a fill material disposed in the first bridge.

24. A BAW resonator structure as claimed in claim 22, further comprising a fill material disposed in the second bridge.

25. A BAW resonator as claimed in claim 22, wherein the inner raised region is disposed substantially at a geometric center of the second upper electrode.

26. A BAW resonator structure as claimed in claim 22, further comprising an outer raised region disposed over the second upper electrode.

27. A BAW resonator structure as claimed in claim 26, further comprising a gap defined between the inner raised region and the outer raised region.

28. A BAW resonator structure as claimed in claim 27, wherein the gap has a width of approximately 1 μ

m to approximately 10 μ

m.

29. A BAW resonator structure as claimed in claim 26, wherein each of the inner raised region and the outer raised region comprises a conductive material.

30. A BAW resonator structure as claimed in claim 29, wherein the conductive material of the inner raised region and the outer raised region is the same as a conductive material of the first lower electrode, the first upper electrode, the second lower electrode or the second upper electrode.

31. A BAW resonator structure as claimed in claim 29, wherein the conductive material of the inner raised region and the outer raised region comprises one of tungsten (W), molybdenum (Mo) and copper (Cu).

32. A BAW resonator structure as claimed in claim 26, wherein each of the inner raised region and the outer raised region comprises a dielectric material.

33. A BAW resonator structure as claimed in claim 32, wherein the dielectric material of the inner raised region and the outer raised region comprises one of silicon dioxide (SiO₂), silicon nitride (SiN), silicon carbide (SiC), zinc oxide (ZnO), aluminum nitride (AlN) and lead zirconium titanate (PZT).

34. A BAW resonator structure as claimed in claim 26, wherein the inner raised region has a thickness of about 50 Å

to about 500 Å

, and the outer raised region has a thickness of approximately 500 Å

to approximately 5000 Å

.