# US 2016/0250855 A1 · Piezoelectric device, inkjet head, inkjet printer, and method of manufacturing piezoelectric device

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- Number: US 2016/0250855 A1
- Document ID: US20160250855A1
- Status: Published application
- Kind: A1
- Application number: 15/032,449
- Filed: 2014-10-10
- Published: 2016-09-01
- Earliest claimed: 2013-10-29
- Assignees: Konica Minolta, Inc.
- Applicants: Konica Minolta, Inc.
- Inventors: KAZUKI SHIBUYA
- Web page: https://patentgrep.com/patent/US20160250855A1

## CPC

- B41J 2/14209: {of finger type, chamber walls consisting integrally of piezoelectric material}
- B41J 2/14233: {of film type, deformed by bending and disposed on a diaphragm}
- B41J 2/1607: {Production of print heads with piezoelectric elements (B41J2/1606, B41J2/162 take precedence)}
- 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 2/1645: {thin film formation by spincoating}
- B41J 2/1646: {thin film formation by sputtering}
- H10N 30/06: Forming electrodes or interconnections, e.g. leads or terminals
- H10N 30/07: Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
- H10N 30/074: by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
- H10N 30/079: using intermediate layers, e.g. for growth control
- H10N 30/2047: {Membrane type}
- H10N 30/708: {Intermediate layers, e.g. barrier, adhesion or growth control buffer layers}
- H10N 30/8554: {Lead-zirconium titanate [PZT] based}
- H10N 30/877: {Conductive materials}
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

An actuator as a piezoelectric device has a bonding layer including titanium, a lower electrode including platinum, a piezoelectric thin film, and an upper electrode formed in this order on a substrate. Ti particles precipitate from the bonding layer onto the lower electrode. Pt that forms the lower electrode has a crystal grain size of 75 nm to 150 nm.

## Claims

### Claim 1

A piezoelectric device comprising: a substrate; a bonding layer comprising titanium; a lower electrode comprising platinum; a piezoelectric thin film; and an upper electrode, wherein the bonding layer, the lower electrode, the piezoelectric thin film, and the upper electrode are formed in this order on the substrate,
titanium from the bonding layer forms a precipitate on the lower electrode, and
the platinum that forms the lower electrode has a crystal grain size of 75 nm to 150 nm.

### Claim 2 (depends on 1)

The piezoelectric device according to claim 1, wherein the piezoelectric thin film comprises lead zirconate titanate.

### Claim 3 (depends on 1)

The piezoelectric device according to claim 1, further comprising an orientation control layer for controlling orientation of the piezoelectric thin film between the lower electrode and the piezoelectric thin film.

### Claim 4 (depends on 3)

The piezoelectric device according to claim 3, wherein the orientation control layer comprises lead lanthanum titanate.

### Claim 5 (depends on 1)

The piezoelectric device according to claim 1, which has a thickness ratio t1/t2 of 1/17 to 1/8, wherein t1 represents the thickness (nm) of the bonding layer, and t2 represents the thickness (nm) of the lower electrode.

### Claim 6 (depends on 1)

An inkjet head comprising:
the piezoelectric device according to claim 1; and
a nozzle substrate having a nozzle hole for ejecting ink to outside from an opening that is formed in the substrate of the piezoelectric device to contain the ink.

### Claim 7 (depends on 6)

An inkjet printer comprising the inkjet head according to claim 6, the inkjet printer being configured to eject ink from the inkjet head to a recording medium.

### Claim 8

A method of manufacturing a piezoelectric device, the method comprising the steps of:
forming a bonding layer comprising titanium on a substrate; forming a lower electrode comprising platinum on the bonding layer;
forming a piezoelectric thin film on the lower electrode; and
forming an upper electrode on the piezoelectric thin film, wherein
the step of forming the lower electrode comprises forming the lower electrode in such a way that titanium is precipitated from the bonding layer onto the lower electrode and the platinum has a crystal grain size of 75 nm to 150 nm.

### Claim 9 (depends on 8)

The method of manufacturing a piezoelectric device according to claim 8, wherein the lower electrode is formed by sputtering.

### Claim 10 (depends on 8)

The method of manufacturing a piezoelectric device according to claim 8, wherein the piezoelectric thin film comprises lead zirconate titanate.

### Claim 11 (depends on 8)

The method of manufacturing a piezoelectric device according to claim 8, further comprising the step of providing an orientation control layer for controlling orientation of the piezoelectric thin film between the lower electrode and the piezoelectric thin film.

### Claim 12 (depends on 11)

The method of manufacturing a piezoelectric device according to claim 11, wherein the orientation control layer comprises lead lanthanum titanate.

### Claim 13 (depends on 8)

The method of manufacturing a piezoelectric device according to claim 8, wherein the bonding layer and the lower electrode provide a thickness ratio t1/t2 of 1/17 to 1/8, wherein t1 represents the thickness (nm) of the bonding layer, and t2 represents the thickness (nm) of the lower electrode.

### Claim 14 (depends on 8)

The method of manufacturing a piezoelectric device according to claim 8, wherein the lower electrode is deposited at a temperature of 500° C. to 700° C.

### Claim 15 (depends on 1)

The piezoelectric device according to claim 1, wherein the lower electrode includes titanium inside.