Acoustic resonator performance enhancement using alternating frame structure

• US 7,714,684 B2
• Filed: 05/06/2008
• Issued: 05/11/2010
• Est. Priority Date: 10/01/2004
• 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: Bradley, Paul D., Feng, Hongjun, Ruby, Richard C., Fazzio, Ronald S.
• Primary Examiner(s): Summons; Barbara
• Application Number:
  US12/115,666
• Publication Number:
  US 20080258842A1
• Time in Patent Office: 735 Days
• Field of Search: 333187-189, 310/312, 310/335, 310/322, 310/365
• US Class Current: 333/187
• CPC Class Codes: H03H 2003/0428 of an electrode
• CPC Class Codes: H03H 3/02 for the manufacture of piezoelectric or electrostrictive resonators or networks H03H3/08 takes precedence
• CPC Class Codes: H03H 9/02086 Means for compensation or elimination of undesirable effects
• CPC Class Codes: H03H 9/02149 of ageing changes of characteristics, e.g. electro-acousto-migration
• CPC Class Codes: H03H 9/13 for networks consisting of piezoelectric or electrostrictive materials H03H9/145 takes precedence
• CPC Class Codes: H03H 9/132 characterized by a particular shape
• CPC Class Codes: H03H 9/173 Air-gaps

Abstract

Disclosed is an acoustic resonator that includes a substrate, a first electrode, a layer of piezoelectric material, a second electrode, and an alternating frame region. The first electrode is adjacent the substrate, and the first electrode has an outer perimeter. The piezoelectric layer is adjacent the first electrode. The second electrode is adjacent the piezoelectric layer and the second electrode has an outer perimeter. The alternating frame region is on one of the first and second electrodes.

Claims

1. An acoustic resonator comprising:

a substrate;

a first electrode disposed over the substrate;

a piezoelectric layer adjacent the first electrode;

a second electrode adjacent the piezoelectric layer;

an alternating frame region on one of the first and second electrodes, wherein a portion of the alternating frame region satisfies a Bragg condition at a selected wavelength of an acoustic lateral mode.

2. An acoustic resonator as claimed in claim 1, wherein the first electrode, the second electrode and the piezoelectric layer comprise a resonator membrane, and the resonator membrane is disposed over a recess in the substrate.

3. An acoustic resonator as claimed in claim 1, wherein the first electrode, the second electrode and the piezoelectric layer comprise a resonator membrane, and the resonator membrane is disposed over an acoustic mirror disposed within substrate.

4. An acoustic resonator as claimed in claim 1, wherein the alternating frame region further comprises a first region having a first acoustic impedance and a second region having a second acoustic impedance, the first and second acoustic impedances being different such that certain wavelengths of signals within the acoustic resonator reflect and interfere to improve Q.

5. The acoustic resonator of claim 1, wherein the alternating frame region comprises at least a first raised frame and a second raised frame on the second electrode, the first and second raised frames being spaced apart from each other.

6. The acoustic resonator of claim 5, further including a recessed region inside the first and second raised frames.