# US 12,009,799 B2 · Acoustic wave device, high-frequency front-end circuit, and communication device

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- Number: US 12,009,799 B2
- Document ID: US12009799B2
- Status: Granted
- Kind: B2
- Application number: 17/567,918
- Filed: 2022-01-04
- Published: 2022-04-28
- Granted: 2024-06-11
- Earliest claimed: 2019-07-05
- Assignees: Murata Manufacturing Co., Ltd.
- Applicants: Murata Manufacturing Co., Ltd.
- Inventors: Hideki Iwamoto
- Web page: https://patentgrep.com/patent/US12009799B2

## CPC

- H03H 9/02551: {of quartz substrates}
- H03H 9/02015: {Characteristics of piezoelectric layers, e.g. cutting angles}
- H03H 9/02228: {Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer}
- H03H 9/02559: {of lithium niobate or lithium-tantalate substrates}
- H03H 9/02574: {of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate}
- H03H 9/6483: {Ladder SAW filters}
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

An acoustic wave device includes a support substrate, a piezoelectric layer, and an IDT electrode. The support substrate is made of quartz. The piezoelectric layer is provided on the support substrate and is made of LiTaO3. The IDT electrode is on the piezoelectric layer and includes electrode fingers. The IDT electrode is on a negative surface side of the piezoelectric layer. The cut angle of the piezoelectric layer is equal to or more than about 39° Y and equal to or less than about 48° Y.

## Claims

### Claim 1

An acoustic wave device comprising:
a support substrate made of quartz;
a piezoelectric layer on the support substrate and made of LiTaO3; and
an IDT electrode on the piezoelectric layer and including a plurality of electrode fingers; wherein
the IDT electrode is on a negative surface side of the piezoelectric layer;
a cut angle of the piezoelectric layer is equal to or more than about 39°Y and equal to or less than about 48°Y; and
an angle defined by a Z-axis of the support substrate and an X-axis of the LiTaO3 is equal to or less than about +20°.

### Claim 2 (depends on 1)

The acoustic wave device according to claim 1, wherein an acoustic velocity of a slow transversal wave propagating through the support substrate is equal to or higher than about 3950 m/s.

### Claim 3 (depends on 2)

The acoustic wave device according to claim 2, wherein the acoustic velocity of the slow transversal wave propagating through the support substrate is equal to or higher than about 4100 m/s.

### Claim 4 (depends on 3)

The acoustic wave device according to claim 3, wherein the cut angle of the piezoelectric layer is equal to or more than about 42°Y.

### Claim 5 (depends on 2)

The acoustic wave device according to claim 2, wherein the cut angle of the piezoelectric layer is equal to or more than about 42°Y.

### Claim 6 (depends on 1)

The acoustic wave device according to claim 1, wherein the cut angle of the piezoelectric layer is equal to or more than about 42°Y.

### Claim 7 (depends on 6)

The acoustic wave device according to claim 6, wherein the cut angle of the piezoelectric layer is equal to or more than about 44°Y.

### Claim 8 (depends on 1)

The acoustic wave device according to claim 1, wherein the piezoelectric layer is directly laminated on the support substrate.

### Claim 9 (depends on 1)

A high-frequency front-end circuit comprising:
a filter that includes the acoustic wave device according to claim 1 and allows a high-frequency signal in a predetermined frequency band to pass through the filter; and
an amplifier circuit connected to the filter and configured to amplify an amplitude of the high-frequency signal.

### Claim 10 (depends on 9)

A communication device comprising:
the high-frequency front-end circuit according to claim 9; and
a signal processing circuit to process the high-frequency signal.

### Claim 11 (depends on 1)

The acoustic wave device according to claim 1, wherein the Z-axis of the support substrate and the X-axis of the LiTaO3 are parallel or substantially parallel to each other.

### Claim 12 (depends on 11)

The acoustic wave device according to claim 11, wherein the cut angle of the piezoelectric layer is equal to or more than about 42°Y.

### Claim 13

An acoustic wave device comprising:
a support substrate made of quartz;
a piezoelectric layer on the support substrate and made of LiTaO3; and
an IDT electrode on the piezoelectric layer and including a plurality of electrode fingers; wherein
the IDT electrode is on a negative surface side of the piezoelectric layer;
a cut angle of the piezoelectric layer is equal to or more than about 39°Y and equal to or less than about 48°Y;
an acoustic velocity of a slow transversal wave propagating through the support substrate is equal to or higher than about 3950 m/s; and
an angle defined by a Z-axis of the support substrate and an X-axis of the LiTaO3 is equal to or less than about ±20°.

### Claim 14

An acoustic wave device comprising:
a support substrate made of quartz;
a piezoelectric layer on the support substrate and made of LiTaO3; and
an IDT electrode on the piezoelectric layer and including a plurality of electrode fingers; wherein
the IDT electrode is on a negative surface side of the piezoelectric layer;
a cut angle of the piezoelectric layer is equal to or more than about 42°Y and equal to or less than about 48°Y; and
an angle defined by a Z-axis of the support substrate and an X-axis of the LiTaO3 is equal to or less than about +20°.