Bulk acoustic wave resonator device comprising a bridge in an acoustic reflector

• US 9,099,983 B2
• Filed: 10/18/2012
• Issued: 08/04/2015
• 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, Choy, John, Nikkel, Phil
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US13/654,718
• Publication Number:
  US 20130038408A1
• Time in Patent Office: 1,020 Days
• Field of Search: 333187-189, 333/133, 310/334, 310/335
• US Class Current: 1/1
• CPC Class Codes: H03H 9/0211 of reflections
• 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 9/175 Acoustic mirrors
• CPC Class Codes: H03H 9/589 Acoustic mirrors

Abstract

A bulk acoustic wave (BAW) resonator device includes an acoustic reflector formed over a substrate and a resonator stack formed over the acoustic reflector. The acoustic reflector includes multiple acoustic impedance layers. The resonator stack includes a first electrode formed over the acoustic reflector, a piezoelectric layer formed over the first electrode, and a second electrode formed over the piezoelectric layer. A bridge is formed within one of the acoustic reflector and the resonator stack.

Claims

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

an acoustic reflector formed over a substrate, the acoustic reflector comprising a plurality of acoustic impedance layers;

a resonator stack formed over the acoustic reflector, the resonator stack comprising a bottom electrode formed over the acoustic reflector, a piezoelectric layer formed over the bottom electrode, and a top electrode formed over the piezoelectric layer;

a first bridge formed in the acoustic reflector; and

a second bridge formed in the resonator stack.

2. The BAW resonator device of claim 1, wherein the first bridge is formed between adjacent acoustic impedance layers of the acoustic reflector.

3. The BAW resonator device of claim 2, wherein the first bridge is formed between a first acoustic impedance layer adjacent the bottom electrode and a second acoustic impedance layer formed adjacent the first acoustic impedance layer.

4. The BAW resonator device of claim 3, wherein the first acoustic impedance layer is formed of a first material having a relatively low acoustic impedance and the second acoustic impedance layer is formed of a second material having a relatively high acoustic impedance.

5. The BAW resonator device of claim 4, wherein the first material comprises one of silicon oxide (SiO_x) or carbon-doped silicon oxide (CDO), and the second material comprises one of tungsten (W), molybdenum (Mo) or silicon nitride (SiN_x).

6. The BAW resonator device of claim 1, wherein the acoustic reflector comprises a distributed Bragg reflector (DBR).

7. The BAW resonator device of claim 1, wherein the first bridge is formed between a first acoustic impedance layer adjacent the bottom electrode and a second acoustic impedance layer formed adjacent the first acoustic impedance layer.

8. The BAW resonator device of claim 7, wherein the second bridge is formed between the bottom electrode and the piezoelectric layer.

9. The BAW resonator device of claim 1, wherein the first bridge comprises an unfilled bridge, containing air.

10. The BAW resonator device of claim 1, wherein the first bridge comprises a filled bridge, containing a dielectric material.

11. The BAW resonator device of claim 10, wherein the dielectric material comprises one of non-etchable borosilicate glass (NEBSG), carbon doped silicon dioxide (CDO), or silicon carbide (SiC).

12. The BAW resonator device of claim 1, wherein the first bridge comprises a filled bridge, containing a metal.

13. The BAW resonator device of claim 1, further comprising:

an active region having a perimeter, at least a portion of which is formed by at least one of the first bridge and the second bridge.

14. The BAW resonator device of claim 13, wherein the at least a portion of the perimeter of the active region is formed by one of the first bridge and the second bridge extending furthest toward a center of the BAW resonator device.

15. A bulk acoustic wave (BAW) resonator device, comprising:

an acoustic reflector formed over a substrate, the acoustic reflector comprising a plurality of acoustic impedance layers;

a resonator stack formed over the acoustic reflector, the resonator stack comprising a bottom electrode formed over the acoustic reflector, a piezoelectric layer formed over the bottom electrode, and a top electrode formed over the piezoelectric layer; and

a bridge formed within the acoustic reflector, the bridge defining at least part of a perimeter along an active region of the BAW resonator device.

16. The BAW resonator device of claim 15, further comprising another bridge formed within the resonator stack.

17. The BAW resonator device of claim 15, further comprising another bridge formed within the acoustic reflector.

18. The BAW resonator device of claim 15, wherein the plurality of acoustic impedance layers are arranged in pairs, each pair comprising an acoustic impedance layer with a relatively low acoustic impedance and an acoustic impedance layer with a relatively high acoustic impedance, and

wherein the bridge is formed between the acoustic impedance layers of a pair.

19. The BAW resonator device of claim 18, where the bridge comprises a filled bridge, containing a material different from a material of an acoustic impedance layer of the plurality of acoustic impedance layers in which the bridge material is formed.

20. A bulk acoustic wave (BAW) resonator device, comprising:

a distributed Bragg reflector (DBR) formed over a substrate, the DBR comprising a plurality of acoustic impedance layers;

a resonator stack formed over the DBR, the resonator stack comprising a bottom electrode formed over the DBR, a piezoelectric layer formed over the bottom electrode, and a top electrode formed over the piezoelectric layer;

a first bridge formed between adjacent layers of the plurality of acoustic impedance layers of the DBR; and

a second bridge formed between the piezoelectric layer and one of the bottom electrode and the top electrode of the resonator stack.