Bulk acoustic resonator comprising non-piezoelectric layer and bridge

• US 8,350,445 B1
• Filed: 06/24/2011
• Issued: 01/08/2013
• Est. Priority Date: 06/16/2011
• 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: Shirakawa, Alexandre, Burak, Dariusz, Nikkel, Phil
• Primary Examiner(s): DOUGHERTY, THOMAS M
• Application Number:
  US13/168,101
• Publication Number:
  US 20120319534A1
• Time in Patent Office: 564 Days
• Field of Search: 310/320, 310/365, 333/187
• US Class Current: 310/320
• CPC Class Codes: H03H 2003/021 the resonators or networks being of the air-gap type
• CPC Class Codes: H03H 3/02 for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/173 Air-gaps

Abstract

A bulk acoustic wave (BAW) resonator, comprises: a first electrode formed on a substrate; a piezoelectric layer formed on the first electrode; a second electrode formed on the first piezoelectric layer; a non-piezoelectric layer formed on the first electrode and adjacent to the piezoelectric layer; and a bridge formed between the non-piezoelectric layer and the first or second electrode.

Claims

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

a first electrode formed on a substrate;

a piezoelectric layer formed on the first electrode;

a second electrode formed on the first piezoelectric layer;

a non-piezoelectric layer formed on the first electrode and adjacent to the piezoelectric layer; and

a bridge formed between the non-piezoelectric layer and the first or second electrode.

2. The BAW resonator of claim 1, wherein the bridge is an air-bridge.

3. The RAW resonator of claim 1, wherein the bridge comprises a cavity Idled with a dielectric material or a metal.

4. The BAW resonator of claim 1, wherein the non-piezoelectric layer is polycrystalline.

5. The BAW resonator of claim 1, wherein the piezoelectric layer comprises a material, and the non-piezoelectric layer is a non-crystalline form of the material.

6. The RAW resonator of claim 5, wherein the material is aluminum nitride.

7. The RAW resonator of claim 1, further comprising an acoustic reflector disposed beneath the first electrode.

8. The BAW resonator of claim 7, wherein the acoustic reflector comprises a cavity, and the bridge overlaps the cavity in a lateral direction of the BAW resonator.

9. The BAW resonator of claim 1, wherein the piezoelectric layer has a piezoelectric coupling coefficient (e33) and the non-piezoelectric layer has a piezoelectric coupling coefficient that is less or equal to 80% of the first piezoelectric coupling coefficient.

10. The BAW resonator of claim 1, wherein the bridge is formed on multiple sides of a BAW resonator structure formed in an apodized pentagon shape.

11. The BAW resonator of claim 1, wherein the bridge has a trapezoidal shape.