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

Patent metadata

Field	Value
Publication number	US-2023270013-A1
Application number	US-202118012920-A
Country	US
Kind code	A1
Filing date	Mar 16, 2021
Priority date	Jun 30, 2020
Publication date	Aug 24, 2023
Grant date	—

Abstract

There is provided a piezoelectric stack, including: a substrate; an oxide film on the substrate, containing zinc and oxygen as main elements; an electrode film on the oxide film; and a piezoelectric film on the electrode film, being an alkali niobium oxide film containing potassium, sodium, niobium, and oxygen and having a perovskite structure.

First claim

1 . A piezoelectric stack comprising:
a substrate; an oxide film on the substrate, containing zinc and oxygen as main elements; an electrode film on the oxide film; and a piezoelectric film on the electrode film, being an alkali niobium oxide film containing potassium, sodium, niobium, and oxygen and having a perovskite structure.

2 . The piezoelectric stack according to claim 1 , wherein a (001) orientation ratio of crystals constituting the piezoelectric film is 80% or more.

3 . The piezoelectric stack according to claim 1 , wherein a (001) orientation ratio of crystals constituting the piezoelectric film is 90% or more.

4 . The piezoelectric stack according to claim 1 , wherein a relative dielectric constant of the piezoelectric film is 250 or more and 300 or less when measured by applying a voltage of −1 V to +1 V to a top electrode film being a film on the piezoelectric film and different from the electrode film, with a triangular wave having a frequency of 3 kHz while the electrode film is grounded.

5 . The piezoelectric stack according to claim 1 , wherein a thickness of the oxide film is 1 nm or more.

6 . The piezoelectric stack according to claim 1 , further comprising a top electrode film, being an electrode film different from the electrode film, on the piezoelectric film.

7 . A piezoelectric element comprising:
a substrate; an oxide film on the substrate, containing zinc and oxygen as main elements; a bottom electrode film on the oxide film; a piezoelectric film on the bottom electrode film, being an alkali niobium oxide film containing potassium, sodium, niobium, and oxygen and having a perovskite structure; and a top electrode film on the piezoelectric film.

8 . The piezoelectric element according to claim 7 , wherein a (001) orientation ratio of crystals constituting the piezoelectric film is 80% or more.

9 . The piezoelectric element according to claim 7 , wherein when a positive voltage is applied at a temperature of 200° C., to the top electrode film such that an electric field of 300 kV/cm is generated between the top electrode film and the bottom electrode film, it takes 1500 seconds or more, from a start of the voltage application until a density of a leakage current flowing through the piezoelectric film exceeds 30 mA/cm 2 .

10 . The piezoelectric element according to claim 7 , wherein a (001) orientation ratio of crystals constituting the piezoelectric film is 90% or more.

11 . The piezoelectric element according to claim 10 , wherein when a positive voltage is applied at a temperature of 200° C., to the top electrode film such that an electric field of 300 kV/cm is generated between the top electrode film and the bottom electrode film, it takes 1800 seconds or more, from a start of the voltage application until a density of a leakage current flowing through the piezoelectric film exceeds 30 mA/cm 2 .

12 . A method of manufacturing a piezoelectric stack, comprising:
depositing an oxide film on a substrate, containing zinc and oxygen as main elements; depositing an electrode film on the oxide film; and depositing a piezoelectric film on the electrode film, being an alkali niobium oxide film containing potassium, sodium, niobium, and oxygen and having a perovskite structure.

13 . The method of manufacturing a piezoelectric stack according to claim 12 , wherein in the deposition of the oxide film, the oxide film is deposited under a temperature condition of 200° C. or more, and
In the deposition of the electrode film, the electrode film is deposited under a temperature condition of 200° C. or more.

14 . The piezoelectric stack according to claim 2 , wherein a relative dielectric constant of the piezoelectric film is 250 or more and 300 or less when measured by applying a voltage of −1 V to +1 V to a top electrode film being a film on the piezoelectric film and different from the electrode film, with a triangular wave having a frequency of 3 kHz while the electrode film is grounded.

15 . The piezoelectric stack according to claim 3 , wherein a relative dielectric constant of the piezoelectric film is 250 or more and 300 or less when measured by applying a voltage of −1 V to +1 V to a top electrode film being a film on the piezoelectric film and different from the electrode film, with a triangular wave having a frequency of 3 kHz while the electrode film is grounded.

16 . The piezoelectric stack according to claim 2 , wherein a thickness of the oxide film is 1 nm or more.

17 . The piezoelectric stack according to claim 3 , wherein a thickness of the oxide film is 1 nm or more.

18 . The piezoelectric stack according to claim 4 , wherein a thickness of the oxide film is 1 nm or more.

19 . The piezoelectric stack according to claim 2 , further comprising a top electrode film, being an electrode film different from the electrode film, on the piezoelectric film.

20 . The piezoelectric stack according to claim 3 , further comprising a top electrode film, being an electrode film different from the electrode film, on the piezoelectric film.

Assignees

• Sumitomo Chemical Co

Inventors

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

Classifications

• C23C14/165

  by cathodic sputtering · CPC title

• C23C14/088

  of the type ABO3 with A representing alkali, alkaline earth metal or Pb and B representing a refractory or rare earth metal · CPC title

• C23C14/086

  of zinc, germanium, cadmium, indium, tin, thallium or bismuth · CPC title

• C23C14/024

  Deposition of sublayers, e.g. to promote adhesion of the coating (C23C14/027 takes precedence) · CPC title

• C04B35/495 Primary

  based on vanadium, niobium, tantalum, molybdenum or tungsten oxides or solid solutions thereof with other oxides, e.g. vanadates, niobates, tantalates, molybdates or tungstates · CPC title