# US 12,763,753 B2 · Composite substrate and method of producing composite substrate

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- Number: US 12,763,753 B2
- Document ID: US12763753B2
- Status: Granted
- Kind: B2
- Application number: 17/818,040
- Filed: 2022-08-08
- Published: 2022-12-15
- Granted: 2026-10-13
- Earliest claimed: 2021-06-11
- Assignees: NGK Insulators, Ltd.
- Applicants: NGK Insulators, Ltd.
- Inventors: Minori Tani
- Web page: https://patentgrep.com/patent/US12763753B2

## CPC

- H03H 9/02574: {of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate}
- H03H 3/08: for the manufacture of resonators or networks using surface acoustic waves
- H03H 9/02559: {of lithium niobate or lithium-tantalate substrates}
- H10N 30/086: by polishing or grinding
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A composite substrate according to includes: a support substrate; and a piezoelectric layer arranged on one side of the support substrate, wherein an amplitude of a waviness having a spatial frequency of more than 0.045 cyc/mm according to a shape of the support substrate is 10 nm or less.

## Claims

### Claim 1

A composite substrate, comprising:
a support substrate; and
a piezoelectric layer arranged on one side of the support substrate,
wherein an amplitude of waviness of a shape of the support substrate at a spatial frequency of more than 0.045 cyc/mm is 10 nm or less.

### Claim 2 (depends on 1)

The composite substrate according to claim 1, wherein a difference between a thickness T1 of the piezoelectric layer at a first point and a thickness T2 thereof at a second point has an absolute value of 100 nm or less.

### Claim 3 (depends on 1)

The composite substrate according to claim 1, wherein the piezoelectric layer has a thickness of 5 μm or less.

### Claim 4

A method of producing a composite substrate, comprising:
joining a support substrate to a first main surface side of a piezoelectric substrate having a first main surface and a second main surface facing each other; and
polishing a surface of the piezoelectric substrate on a second main surface side thereof,
wherein an amplitude of waviness of a shape of the support substrate at a spatial frequency of more than 0.045 cyc/mm is 10 nm or less.

### Claim 5 (depends on 4)

The production method according to claim 4, wherein a difference between a thickness T1 of a piezoelectric layer, which is obtained by polishing the piezoelectric substrate, at a first point and a thickness T2 thereof at a second point has an absolute value of 100 nm or less.

### Claim 6 (depends on 4)

The production method according to claim 4, wherein a piezoelectric layer, which is obtained by polishing the piezoelectric substrate, has a thickness of 5 μm or less.

### Claim 7 (depends on 2)

The composite substrate according to claim 2, wherein the piezoelectric layer has a thickness of 5 μm or less.

### Claim 8 (depends on 5)

The production method according to claim 5, wherein the piezoelectric layer has a thickness of 5 μm or less.