# US 2021/0083643 A1 · Gradient raised frames in film bulk acoustic resonators

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- Number: US 2021/0083643 A1
- Document ID: US20210083643A1
- Status: Published application
- Kind: A1
- Application number: 17/018,847
- Filed: 2020-09-11
- Published: 2021-03-18
- Earliest claimed: 2019-09-13
- Assignees: Skyworks Global Pte. Ltd.
- Applicants: Skyworks Solutions, Inc.
- Inventors: Jiansong LIU; Kwang Jae SHIN; Jae Hyung LEE; Benjamin Paul ABBOTT; Chun Sing LAM
- Web page: https://patentgrep.com/patent/US20210083643A1

## CPC

- H03H 9/0211: {of reflections}
- H03H 9/02118: {of lateral leakage between adjacent resonators}
- H03H 3/02: for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence)
- H03H 9/174: {Membranes}
- H03H 9/564: {implemented with thin-film techniques}
- H03H 2003/023: {the resonators or networks being of the membrane type}
- Y10T 29/42: Piezoelectric device making
- Y10T 29/4908: Acoustic transducer
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Gradient raised frames in film bulk acoustic resonators. In some embodiments, a film bulk acoustic resonator device can include a substrate, first and second metal layers implemented over the substrate, a piezoelectric layer between the first and second metal layers, and a gradient raised frame implemented relative to one of the first and second metal layers and configured to improve reflection of lateral mode waves and to reduce conversion of main mode waves into lateral mode waves.

## Claims

### Claim 1

A film bulk acoustic resonator device comprising:
a substrate;
first and second metal layers implemented over the substrate;
a piezoelectric layer between the first and second metal layers; and
a gradient raised frame implemented relative to one of the first and second metal layers and configured to improve reflection of lateral mode waves and to reduce conversion of main mode waves into lateral mode waves.

### Claim 2 (depends on 1)

The film bulk acoustic resonator device of claim 1 wherein the gradient raised frame is implemented at a position along a direction perpendicular to the first and second metal layers and the piezoelectric layer.

### Claim 3 (depends on 1)

The film bulk acoustic resonator device of claim 1 wherein the second metal layer is above the piezoelectric layer and the first metal layer is below the piezoelectric layer.

### Claim 4 (depends on 3)

The film bulk acoustic resonator device of claim 3 wherein the gradient raised frame is implemented above the second metal layer.

### Claim 5 (depends on 3)

The film bulk acoustic resonator device of claim 3 wherein the gradient raised frame is implemented below the second metal layer.

### Claim 6 (depends on 3)

The film bulk acoustic resonator device of claim 3 wherein the gradient raised frame has an angle relative to a direction parallel to the first and second metal layers and the piezoelectric layer.

### Claim 7 (depends on 6)

The film bulk acoustic resonator device of claim 6 wherein the angle is less than 90°.

### Claim 8 (depends on 3)

The film bulk acoustic resonator device of claim 3 wherein the gradient raised frame is made of one or more of a heavy material or a low acoustic impedance material.

### Claim 9 (depends on 3)

The film bulk acoustic resonator device of claim 3 further comprising a second gradient raised frame implemented relative to one of the first and second metal layers and configured to improve reflection of lateral mode waves and to reduce conversion of main mode waves into lateral mode waves.

### Claim 10 (depends on 9)

The film bulk acoustic resonator device of claim 9 wherein the gradient raised frame is implemented above the second metal layer and the second gradient raised frame is implemented below the second metal layer.

### Claim 11 (depends on 9)

The film bulk acoustic resonator device of claim 9 wherein the gradient raised frame is implemented above the second metal layer and the second gradient raised frame is implemented above the first metal layer.

### Claim 12 (depends on 9)

The film bulk acoustic resonator device of claim 9 wherein the gradient raised frame is implemented below the second metal layer and the second gradient raised frame is implemented below the first metal layer.

### Claim 13 (depends on 9)

The film bulk acoustic resonator device of claim 9 wherein the gradient raised frame and the second gradient raised frame have respective angles relative to a direction parallel to the first and second metal layers and the piezoelectric layer.

### Claim 14 (depends on 13)

The film bulk acoustic resonator device of claim 13 wherein each of the respective angles is less than 90°.

### Claim 15 (depends on 9)

The film bulk acoustic resonator device of claim 9 wherein the gradient raised frame and the second gradient raised frame are made of one or more of a heavy material or a low acoustic impedance material.

### Claim 16 (depends on 15)

The film bulk acoustic resonator device of claim 15 wherein the gradient raised frame is made of a heavy material and the second gradient raised frame is made of a low acoustic impedance material.

### Claim 17 (depends on 3)

The film bulk acoustic resonator device of claim 3 wherein a passivation layer is implemented above the gradient raised frame.

### Claim 18 (depends on 17)

The film bulk acoustic resonator device of claim 17 wherein the passivation layer includes a recessed frame adjacent to an active region.

### Claim 19 (depends on 1)

The film bulk acoustic resonator device of claim 1 wherein the film bulk acoustic resonator device is a radio-frequency filter.

### Claim 20

A method for fabricating a film bulk acoustic resonator device, the method comprising:
forming a first metal layer over a substrate;
forming a piezoelectric layer;
forming a second metal layer, the piezoelectric layer positioned between the first and second metal layers; and
forming a gradient raised frame implemented relative to one of the first and second metal layers and configured to improve reflection of lateral mode waves and to reduce conversion of main mode waves into lateral mode waves.

### Claim at position 21

-43. (canceled)