# US 10,369,787 B2 · Piezoelectric thin film, piezoelectric actuator, inkjet head, inkjet printer, and method for manufacturing piezoelectric actuator

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- Number: US 10,369,787 B2
- Document ID: US10369787B2
- Status: Granted
- Kind: B2
- Application number: 15/575,644
- Filed: 2016-05-11
- Published: 2018-06-21
- Granted: 2019-08-06
- Earliest claimed: 2015-05-25
- Assignees: Konica Minolta, Inc.
- Applicants: Konica Minolta, Inc.
- Inventors: Kenji Mawatari
- Web page: https://patentgrep.com/patent/US10369787B2

## CPC

- B41J 2/14: Structure thereof {only for on-demand ink jet heads}
- B41J 2/16: Production of nozzles
- B41J 2/161: {of film type, deformed by bending and disposed on a diaphragm}
- B41J 2/1623: {bonding and adhesion}
- B41J 2/1628: {dry etching}
- B41J 2/1631: {photolithography}
- B41J 2/1642: {thin film formation by CVD [chemical vapor deposition]}
- B41J 2/1643: {thin film formation by plating}
- B41J 2/1645: {thin film formation by spincoating}
- B41J 2/1646: {thin film formation by sputtering}
- C04B 35/491: based on lead zirconates and lead titanates {, e.g. PZT}
- C04B 35/493: containing also other lead compounds
- C23C 14/0036: {Reactive sputtering}
- C23C 14/025: {Metallic sublayers}
- C23C 14/08: Oxides (C23C14/10 takes precedence)
- C23C 14/088: {of the type ABO3 with A representing alkali, alkaline earth metal or Pb and B representing a refractory or rare earth metal}
- C23C 14/165: {by cathodic sputtering}
- H10N 30/076: by vapour phase deposition
- H10N 30/079: using intermediate layers, e.g. for growth control
- H10N 30/20: with electrical input and mechanical output, e.g. functioning as actuators or vibrators
- H10N 30/2047: {Membrane type}
- H10N 30/706: {characterised by the underlying bases, e.g. substrates}
- H10N 30/708: {Intermediate layers, e.g. barrier, adhesion or growth control buffer layers}
- H10N 30/853: Ceramic compositions
- H10N 30/8554: {Lead-zirconium titanate [PZT] based}
- B41J 2202/03: Specific materials used
- C04B 2235/3227: Lanthanum oxide or oxide-forming salts thereof
- C04B 2235/3251: Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
- C04B 2235/79: Non-stoichiometric products, e.g. perovskites (ABO3) with an A/B-ratio other than 1
- C04B 2235/96: Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A piezoelectric thin film is formed by adding a donor element to lead zirconate titanate. In the piezoelectric thin film, a molar ratio of lead to a total sum of zirconium and titanium is 105% or higher, and, when positive and negative coercive electric fields in polarization and electric field hysteresis are referred to as Ec (+) and Ec (−), respectively, a value of |Ec (+) |/|Ec (−) | is 0.5 or more and 1.5 or less.

## Claims

### Claim 1

A piezoelectric thin film obtained by adding a donor element to lead zirconate titanate, wherein a molar ratio of lead to a total sum of zirconium and titanium is 105% or higher, and
wherein, when positive and negative coercive electric fields in polarization and electric field hysteresis are referred to as Ec (+) and Ec (−), respectively, a value of |Ec (+) |/|Ec (−) | is 0.5 or more and 1.5 or less;
wherein the donor element is lanthanum,
wherein a molar ratio of the lanthanum to the total sum of the zirconium and the titanium is 6% or more and 10% or less, and
wherein a molar ratio of the zirconium to the total sum of the zirconium and the titanium is 54% or more and 59% or less.

### Claim 2 (depends on 1)

The piezoelectric thin film according to claim 1, wherein internal stress of the film is 50 MPa or more and 250 MPa or less.

### Claim 3 (depends on 1)

The piezoelectric thin film according to claim 1, wherein breaking stress of the film is 400 MPa or more.

### Claim 4 (depends on 1)

The piezoelectric thin film according to claim 1, wherein the donor element is niobium,
wherein a molar ratio of the niobium to the total sum of the zirconium and the titanium is 10% or more and 20% or less, and
wherein a molar ratio of the zirconium to the total sum of the zirconium and the titanium is 52% or more and 59% or less.

### Claim 5 (depends on 1)

A piezoelectric actuator comprising:
the piezoelectric thin film according to claim 1; and
a substrate adapted to support the piezoelectric thin film.

### Claim 6 (depends on 5)

The piezoelectric actuator according to claim 5, wherein, between the substrate and the piezoelectric thin film, a seed layer adapted to control crystalline orientation of the piezoelectric thin film is formed.

### Claim 7 (depends on 6)

The piezoelectric actuator according to claim 6, wherein the seed layer is made of lead lanthanum titanate.

### Claim 8 (depends on 5)

The piezoelectric actuator according to claim 5, further comprising:
a pair of electrodes adapted to apply voltage to the piezoelectric thin film.

### Claim 9 (depends on 6)

A method for manufacturing the piezoelectric actuator according to claim 6, comprising:
forming the piezoelectric thin film on the seed layer at a film forming rate of 2.5 μm/h or less.

### Claim 10 (depends on 5)

An inkjet head comprising:
the piezoelectric actuator according to claim 5; and
a nozzle substrate including a nozzle hole through which ink contained in an opening portion formed in the substrate of the piezoelectric actuator is ejected outward.

### Claim 11 (depends on 10)

An inkjet printer comprising:
the inkjet head according to claim 10,
wherein ink is ejected from the inkjet head toward a recording medium.

### Claim 12 (depends on 1)

The piezoelectric thin film according to claim 1,
wherein the donor element is lanthanum.

### Claim 13 (depends on 5)

A method for manufacturing the piezoelectric actuator according to claim 5, comprising:
forming the piezoelectric thin film at a film forming rate of 2.5 μm/h or less.

### Claim 14 (depends on 2)

The piezoelectric thin film according to claim 2, wherein breaking stress of the film is 400 MPa or more.

### Claim 15 (depends on 2)

The piezoelectric thin film according to claim 2, wherein the donor element is lanthanum,
wherein a molar ratio of the lanthanum to the total sum of the zirconium and the titanium is 6% or more and 10% or less, and
wherein a molar ratio of the zirconium to the total sum of the zirconium and the titanium is 54% or more and 59% or less.

### Claim 16 (depends on 2)

The piezoelectric thin film according to claim 2, wherein the donor element is niobium,
wherein a molar ratio of the niobium to the total sum of the zirconium and the titanium is 10% or more and 20% or less, and
wherein a molar ratio of the zirconium to the total sum of the zirconium and the titanium is 52% or more and 59% or less.

### Claim 17 (depends on 2)

A piezoelectric actuator comprising:
the piezoelectric thin film according to claim 2; and
a substrate adapted to support the piezoelectric thin film.

### Claim 18 (depends on 3)

The piezoelectric thin film according to claim 3, wherein the donor element is lanthanum,
wherein a molar ratio of the lanthanum to the total sum of the zirconium and the titanium is 6% or more and 10% or less, and
wherein a molar ratio of the zirconium to the total sum of the zirconium and the titanium is 54% or more and 59% or less.

### Claim 19 (depends on 3)

The piezoelectric thin film according to claim 3, wherein the donor element is niobium,
wherein a molar ratio of the niobium to the total sum of the zirconium and the titanium is 10% or more and 20% or less, and
wherein a molar ratio of the zirconium to the total sum of the zirconium and the titanium is 52% or more and 59% or less.