Ceramic substrate, layered body, and saw device

Patent metadata

Field	Value
Publication number	US-10340886-B2
Application number	US-201615317563-A
Country	US
Kind code	B2
Filing date	Apr 26, 2016
Priority date	Mar 22, 2016
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

A ceramic substrate is formed of a polycrystalline ceramic and has a supporting main surface. The supporting main surface has a roughness of 0.01 nm or more and 3.0 nm or less in terms of Sa. The number of projections and depressions with a height of 1 nm or more in a square region with 50 μm sides on the supporting main surface is less than 5 on average, and the number of projections and depressions with a height of 2 nm or more in the square region is less than 1 on average.

First claim

The invention claimed is:

1. A ceramic substrate formed of a polycrystalline ceramic and having a supporting main surface,
wherein the supporting main surface has a roughness of 0.01 nm or more and 3.0 nm or less in terms of Sa, and
a number of projections and depressions with a height of 1 nm or more in a square region with 50 μm sides on the supporting main surface is less than 5 on average, and a number of projections and depressions with a height of 2 nm or more in the square region is less than 1 on average.

2. The ceramic substrate according to claim 1 , wherein the supporting main surface has a roughness of 0.5 nm or less in terms of Sq.

3. The ceramic substrate according to claim 1 , wherein the polycrystalline ceramic is made of at least one material selected from the group consisting of spinel, alumina, magnesia, silica, mullite, cordierite, calcia, titania, silicon nitride, aluminum nitride, and silicon carbide.

4. A layered body comprising:
the ceramic substrate according to claim 1 ; and
a piezoelectric substrate disposed on the supporting main surface and formed of a piezoelectric body,
wherein the ceramic substrate and the piezoelectric substrate are bonded to each other through Van der Waals force.

5. The layered body according to claim 4 , wherein bonding strength between the ceramic substrate and the piezoelectric substrate is 0.5 J/m 2 or more.

6. A SAW device comprising:
the layered body according to claim 4 ; and
an electrode formed on a main surface of the piezoelectric substrate, the main surface being located opposite to the ceramic substrate.

Assignees

• Sumitomo Electric Industries

Inventors

• Geshi Keiichiro
• Nakayama Shigeru

Classifications

• H03H9/02543

  Characteristics of substrate, e.g. cutting angles · CPC title

• H03H9/25 Primary

  Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)} · CPC title

• C04B35/195

  Alkaline earth aluminosilicates, e.g. cordierite {or anorthite} · CPC title

• C04B35/565

  based on silicon carbide · CPC title

• C04B35/46

  based on titanium oxides or titanates (containing also zirconium or hafnium oxides, zirconates or hafnates C04B35/49) · CPC title