Piezoelectric film, piezoelectric layered body, piezoelectric element, and method for manufacturing piezoelectric layered body

Patent metadata

Field	Value
Publication number	US-2022254988-A1
Application number	US-202017624555-A
Country	US
Kind code	A1
Filing date	Jul 2, 2020
Priority date	Jul 4, 2019
Publication date	Aug 11, 2022
Grant date	—

Abstract

A piezoelectric stack including: a substrate; an electrode film; and a piezoelectric film as a poly-crystal film comprising an alkali niobium oxide of a perovskite structure represented by a composition formula of (K1-xNax)NbO3 (0<x<1), wherein the piezoelectric film contains at least one element selected from a group consisting of Cu and Mn, and an amount of the element present at a grain boundary of crystals constituting the piezoelectric film is greater than that of the element present in a matrix phase of the crystals.

First claim

1 . A piezoelectric film,
being a poly-crystal film comprising a potassium sodium niobium oxide, and containing at least one element selected from a group consisting of Cu and Mn, wherein an amount of the element present at a grain boundary of crystals is greater than that of the element present in a matrix phase of the crystals.

2 . The piezoelectric film according to claim 1 ,
wherein when a positive or negative electric field of 300 kV/cm is applied at a temperature of 200° C. to an electrode film provided on the piezoelectric film, it takes 7600 seconds or more from a start of applying the electric field until a leakage current density flowing through the piezoelectric film exceeds 30 mA/cm 2 under at least one electric field applying condition.

3 . The piezoelectric film according to claim 1 ,
wherein the piezoelectric film is constituted by crystal grains having an average grain size of 100 nm or more.

4 . The piezoelectric film according to claim 1 ,
wherein a content of the element is 0.2 at % or more and 2.0 at % or less.

5 . A piezoelectric stack, comprising:
a substrate; an electrode film; and a piezoelectric film as a poly-crystal film comprising a potassium sodium niobium oxide, wherein the piezoelectric film contains at least one element selected from a group consisting of Cu and Mn, and an amount of the element present at a grain boundary of crystals constituting the piezoelectric film is greater than that of the element present in a matrix phase of the crystals.

6 . The piezoelectric stack according to claim 5 ,
wherein when a positive or negative electric field of 300 kV/cm is applied at a temperature of 200° C. to the electrode film provided on the piezoelectric film, it takes 7600 seconds or more from a start of applying the electric field until a leakage current density flowing through the piezoelectric film exceeds 30 mA/cm 2 under at least one electric field applying condition.

7 . A piezoelectric element, comprising:
a substrate; a piezoelectric film deposited on the substrate as a poly-crystal film comprising a potassium sodium niobium oxide; and an electrode film deposited on the piezoelectric film, wherein the piezoelectric film contains at least one element selected from a group consisting of Cu and Mn, and an amount of the element present at a grain boundary of crystals constituting the piezoelectric film is greater than that of the element present in a matrix phase of the crystals.

8 . A method of manufacturing a piezoelectric stack, comprising:
depositing a piezoelectric film on a substrate as a poly-crystal film comprising a potassium sodium niobium oxide; providing a layer containing or consisting of at least one element selected from a group consisting of Cu and Mn on the piezoelectric film; depositing an electrode film on the layer containing or consisting of the element; and performing a heat-treatment to a stack including the substrate, the piezoelectric film, the layer containing or consisting of the element, and the electrode film, wherein by performing the heat-treatment, the element in the layer containing or consisting of the element is allowed to diffuse into the piezoelectric film, and the piezoelectric film becomes a film which contains the element and in which an amount of the element present at a grain boundary of crystals constituting the piezoelectric film is greater than that of the element present in a matrix phase of the crystals.

Assignees

• Sumitomo Chemical Co

Inventors

• Kuroda Toshiaki
• Shibata Kenji
• Watanabe Kazutoshi
• Kimura Takeshi

Classifications

• H03H9/02543 Primary

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

• H03H3/02

  for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence) · CPC title

• H03H9/02015

  Characteristics of piezoelectric layers, e.g. cutting angles · CPC title

• H03H3/08

  for the manufacture of resonators or networks using surface acoustic waves · CPC title

• H01L41/316

  Electricity · mapped topic