Piezoelectric stack, piezoelectric element, and method of manufacturing piezoelectric stack

Patent metadata

Field	Value
Publication number	US-11800808-B2
Application number	US-202016942813-A
Country	US
Kind code	B2
Filing date	Jul 30, 2020
Priority date	Aug 2, 2019
Publication date	Oct 24, 2023
Grant date	Oct 24, 2023

Abstract

There is provided a piezoelectric stack, including: a substrate; an electrode film; and a piezoelectric film which is comprised of alkali niobium oxide of a perovskite structure represented by a composition formula of (K 1-x Na x )NbO 3 (0<x<1), wherein the piezoelectric film comprises crystals having a grain size with a standard deviation of 0.42 μm or less.

First claim

What is claimed is:

1. A piezoelectric stack, comprising:
a substrate;
an electrode film; and
a piezoelectric film which is comprised of alkali niobium oxide of a perovskite structure represented by a composition formula of (K 1-x N ax )NbO 3 (0<x<1),
wherein crystals of the alkali niobium oxide have an average grain size of 0.3 μm or more and 0.5 μm or less
with a standard deviation of 0.42 μm or less.

2. The piezoelectric stack according to claim 1 , wherein the piezoelectric film contains a metallic element selected from a group consisting of copper and manganese at a concentration of 0.2 at % or more and 2.0 at % or less.

3. A piezoelectric element, comprising:
a substrate;
a bottom electrode film formed on the substrate;
a piezoelectric film formed on the bottom electrode film, and comprised of alkali niobium oxide of a perovskite structure represented by a composition formula of (K 1-x Na x )NbO 3 (0<x<1); and
a top electrode film formed on the piezoelectric film,
wherein crystals of the alkali niobium oxide have an average grain size of 0.3 μm or more and 0.5 μm or less
with a standard deviation of 0.42 μm or less.

4. A method of manufacturing a piezoelectric stack, comprising:
forming an electrode film on a substrate; and
forming a piezoelectric film on the electrode film, the piezoelectric film being comprised of alkali niobium oxide of a perovskite structure represented by a composition formula of (K 1-x Na x )NbO 3 (0<x<1),
wherein in the formation of the piezoelectric film, an initial deposition rate faster than a latter deposition rate, the initial deposition rate being a deposition rate in an initial stage of depositing the piezoelectric film and the latter deposition rate being a deposition rate in a latter stage of depositing the piezoelectric film.

5. The method of manufacturing a piezoelectric stack according to claim 4 , wherein the initial deposition rate is more than 2 μm/hr and 6 μm/hr or less, and the latter deposition rate is 0.5 μm/hr or more and 2 μm/hr or less.

Assignees

• Sumitomo Chemical Co

Inventors

• Shibata Kenji
• Watanabe Kazutoshi
• Kuroda Toshiaki

Classifications

• H10N30/8542 Primary

  Alkali metal based oxides, e.g. lithium, sodium or potassium niobates · CPC title

• H10N30/05

  Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes · CPC title

• H10N30/074

  by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing · CPC title

• H10N30/10516

  Electricity · mapped topic

• H03H9/02031 Primary

  consisting of ceramic · CPC title