Accoustic resonator having integrated lateral feature and temperature compensation feature

• US 9,444,426 B2
• Filed: 02/14/2013
• Issued: 09/13/2016
• Est. Priority Date: 10/25/2012
• 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, Grannen, Kevin J.
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US13/766,993
• Publication Number:
  US 20140118092A1
• Time in Patent Office: 1,307 Days
• Field of Search: 333/187, 333/189, 310/346
• US Class Current: 1/1
• CPC Class Codes: H03H 9/02086 Means for compensation or elimination of undesirable effects
• CPC Class Codes: H03H 9/02102 of temperature influence cutting angles H03H9/02015
• CPC Class Codes: H03H 9/131 consisting of a multilayered structure
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/173 Air-gaps
• CPC Class Codes: H03H 9/175 Acoustic mirrors

Abstract

A bulk acoustic wave (BAW) resonator device includes a bottom electrode on a substrate over one of a cavity and an acoustic mirror, a piezoelectric layer on the bottom electrode, a top electrode on the piezoelectric layer, and a temperature compensation feature having positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer. At least one of the bottom electrode and the top electrode includes an integrated lateral feature configured to create at least one of a cut-off frequency mismatch and an acoustic impedance mismatch.

Claims

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

a lower electrode disposed over a substrate over one of a cavity and an acoustic mirror;

a piezoelectric layer on the lower electrode; and

an upper electrode disposed over the piezoelectric layer, at least one of the lower electrode and the upper electrode being a hybrid electrode comprising a temperature compensating layer having a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer, and an integrated frame configured to create at least one of a cut-off frequency mismatch and an acoustic impedance mismatch, wherein the hybrid electrode comprises an outside electrode layer, an inside electrode layer and an interposer layer, the temperature compensating layer being formed between the inside electrode layer and the interposer layer and the interposer layer being formed between the temperature compensating layer and the piezoelectric layer.

2. The BAW resonator device of claim 1, wherein the integrated frame comprises an integrated low velocity frame formed by a first material located at an outer region of the hybrid electrode and an inner portion formed by a second material located at a center region of the hybrid electrode, the first material having a lower sound velocity than the second material.

3. The BAW resonator device of claim 1, wherein the integrated frame comprises an integrated high velocity frame formed by a second material located at an outer region of the hybrid electrode and an inner portion formed by a first material located at a center region of the hybrid electrode, the first material having a lower sound velocity than the second material.

4. The BAW resonator device of claim 1, wherein the lower electrode comprises the hybrid electrode and the upper electrode comprises a frame electrode having an integrated frame.

5. The BAW resonator device of claim 1, wherein the upper electrode comprises the hybrid electrode and the lower electrode comprises a frame electrode having an integrated frame.

6. The BAW resonator of claim 1, further comprising a cavity disposed in the substrate, over which the lower electrode is disposed.

7. The BAW resonator of claim 1, further comprising a Bragg mirror disposed beneath the lower electrode.