JPH11157068A - Piezoelectric element, ink jet recording head, and method for producing them - Google Patents

Abstract

(57) [Problem] To provide a manufacturing method for forming a thin low dielectric constant layer in a piezoelectric element. SOLUTION: A step of forming a lower electrode made of a conductive material, a step of applying a piezoelectric material which causes a volume change when an electric field of the lower electrode is applied, and after applying the piezoelectric material, from 850 ° C. to 950 ° C. A step of forming a piezoelectric layer by firing at a temperature between ℃ and a step of forming an upper electrode made of a conductive material on the fired piezoelectric layer.
By firing at the above temperature, the development of the low dielectric constant layer can be suppressed as much as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element used for an ink jet recording head. In particular, the present invention relates to a method for manufacturing a piezoelectric element that provides high piezoelectric characteristics.

[0002]

2. Description of the Related Art Piezoelectric elements produce an electromechanical conversion effect in which a volume change occurs when an electric field is applied or a voltage change occurs when pressure is applied. Element. Many ceramics having a perovskite crystal structure exhibit this effect remarkably, and are therefore used as materials for piezoelectric elements.

Conventionally, a method for manufacturing a piezoelectric element has been to develop a perovskite crystal structure by laminating piezoelectric ceramics such as PZT by a sol-gel method and performing heat treatment at a relatively low temperature. For example, JP-A-3-695
No. 12 discloses that a precursor containing an alkoxide in which hydrogen of an organic compound is substituted with a metal is hydrolyzed using a metal cation, and the aqueous solution is applied to a substrate.
A procedure for forming a thin film having piezoelectric characteristics by annealing at a temperature of about 0 ° C. to 700 ° C. is described.

Further, such a conventional method for manufacturing a piezoelectric element is described in, for example, Communications of the American Cer.
amic Society, vol. 79, no. 8, 2189-92 (1996).

[0005] An ink jet recording head is provided on a diaphragm forming one surface of a pressure chamber substrate for storing ink.
It is configured by providing this piezoelectric element. When the volume of the piezoelectric element changes, the diaphragm provided in the pressure chamber is deformed, and pressure is applied to the ink in the pressure chamber to discharge the ink.

[0006]

According to J. Mater. Res. 9 (1994), pp. 2540, which is a known document, in the process of forming a piezoelectric element, an interface between a piezoelectric thin film and an electrode film is formed. It is described that a layer containing the composition of the electrode film naturally occurs in manufacturing. This layer is generated because the reaction between the piezoelectric material and the electrode material is at a high temperature. Since this layer contains the composition of the electrode film and deviates from the composition of the piezoelectric thin film, it has a lower dielectric constant than the piezoelectric thin film.

There is a problem that the thicker the low dielectric constant layer, the lower the dielectric constant and piezoelectric characteristics of the entire piezoelectric element.

[0008] In order to solve the above problem, the first aspect of the present invention is as follows.
It is an object of the present invention to provide a piezoelectric element and an ink jet recording head which exhibit good piezoelectric characteristics by reducing the thickness of a low dielectric constant layer generated during the production of a piezoelectric element.

A second object of the present invention is to provide good piezoelectric characteristics by providing specific manufacturing conditions for preventing the formation of a layer having a low dielectric constant during the manufacture of a piezoelectric element. An object of the present invention is to provide a method for manufacturing a piezoelectric element and an ink jet recording head.

[0010]

In order to solve the above-mentioned problems, the applicant of the present invention changed the temperature at which the piezoelectric material was fired in the process of manufacturing the piezoelectric element, and compared the characteristics of the piezoelectric element. And the thickness of the generated low dielectric constant layer was compared.
As a result, it has been found that by performing firing under certain conditions, the thickness of the low dielectric constant layer can be reduced, and the characteristics of the entire piezoelectric element can be improved.

That is, a piezoelectric element which solves the first problem is a piezoelectric element having a piezoelectric layer sandwiched between electrodes, and has a low dielectric constant lower than that of the piezoelectric layer. The layer is provided with a thickness of 10 nm or less along the lower electrode film.

The relative dielectric constant of the low dielectric constant layer is, for example, 100 or less. In addition, the low dielectric constant layer contains a component constituting an electrode in contact with the low dielectric constant layer.

An ink jet recording head which solves the first problem is configured to be capable of discharging ink from a nozzle communicating with a pressure chamber by applying a voltage to a piezoelectric element to cause a volume change. It is a recording head. The piezoelectric element comprises, between two electrode films, (a) a piezoelectric layer made of a piezoelectric material whose volume changes when an electric field is applied, and (b) 10n
m and a low dielectric constant layer having a dielectric constant lower than that of the piezoelectric layer.

A method of manufacturing a piezoelectric element which solves the second problem includes: (a) a lower electrode film forming step of forming a lower electrode film made of a conductive material; and (b) the two electrode films. (C) applying a piezoelectric material that changes in volume when an electric field is applied between the piezoelectric layer and (c) firing the piezoelectric material at a temperature between 850 ° C. and 950 ° C. after applying the piezoelectric material; And (d) an upper electrode film forming step of forming an upper electrode film made of a conductive material on the fired piezoelectric layer.

In this firing step, firing at a temperature of 900 ° C. is particularly preferred. In this baking step, it is preferable to bake for about 1 minute.

The applying step includes repeating a plurality of times of applying the piezoelectric material to a predetermined thickness, heating the applied piezoelectric material, firing the piezoelectric material, and drying the applied piezoelectric material. It is.

According to a second aspect of the present invention, there is provided a method of manufacturing an ink jet type recording head, comprising: using the method of manufacturing a piezoelectric element according to any one of claims 5 to 8. Is the way. According to the present invention, further, (a) after forming the piezoelectric element composed of the lower electrode film, the piezoelectric layer and the upper electrode film on the substrate on which the insulating film is formed, Etching a substrate into a shape corresponding to a pressure chamber for discharging ink formed on the substrate; and (b) etching the substrate corresponding to a position where the etched piezoelectric element is provided. The method includes a step of forming a pressure chamber, and a step of (c) bonding a nozzle plate provided with a nozzle for discharging ink to a position corresponding to the pressure chamber to the substrate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the best embodiments of the present invention will be described with reference to the drawings. In this embodiment, the piezoelectric element of the present invention is applied to an ink jet recording head.

(Configuration of Inkjet Printer) FIG.
FIG. 1 shows a perspective view of an ink jet printer using the ink jet recording head of the present embodiment. As shown in FIG.
02, the inkjet recording head 10 according to the present invention.
1, a tray 103, a discharge port 104, and the like. The tray 103 is configured so that the paper 105 can be placed thereon. The ink jet recording head 101 is configured to be able to be transported in the width direction (arrow direction) of the paper 105 by an internal transport mechanism (not shown).

In this configuration, when printing data is supplied to the ink jet printer 100 from a computer or the like, an internal roller (not shown)
02. The paper 105 is printed by an ink jet recording head 101 driven in the direction of the arrow in FIG.

FIG. 2 is a perspective view illustrating the structure of the ink jet recording head according to the present embodiment. As shown in FIG.
The nozzle plate 1 provided with the pressure plate 1 and the pressure chamber substrate 2 provided with the vibration plate 3 are fitted into a housing 5. The pressure chamber substrate 2 has a cavity (pressure chamber) 21, a side wall 22, a reservoir 23, and the like formed by the manufacturing method according to the present invention.

In this embodiment, the reservoir for storing the ink is provided on the flow path substrate. However, the nozzle plate may have a multi-layer structure and the reservoir may be provided therein.

(Configuration of Inkjet Recording Head) FIG. 3 is a partially enlarged perspective view of the inkjet recording head of the present embodiment. Some are cross-sectional views. This figure corresponds to an enlarged view of the pressure chamber substrate 2 and the vibration plate 3 from the opposite side in the structure of the ink jet recording head shown in FIG. As shown in FIG. 1, the main part of the ink jet recording head 101 includes a nozzle plate 1,
It comprises a pressure chamber substrate 2, a diaphragm 3 and a piezoelectric element 4.

The nozzle plate 1 is bonded to the pressure chamber substrate 2 so that the nozzles 11 are arranged at positions corresponding to the plurality of cavities 21 provided in the pressure chamber substrate 2.

The pressure chamber substrate 2 includes a cavity 21 and a side wall 2.
2, a reservoir 23 and a supply port 24 are provided. A plurality of cavities 21 of the pressure chamber substrate 2 are formed by etching a substrate such as silicon, and each cavity is formed so as to be filled with ink. The side wall 22 is a portion left without being etched, and is configured to partition between the cavities 21. The reservoir 23
Each of the cavities 21 is configured as a common flow path that can supply ink. The supply port 24 is configured so that ink can be introduced into each cavity 21.

The vibration plate 3 is provided on one surface of the pressure chamber substrate 2. A part of the diaphragm 3 has an ink tank opening 3
3 is provided so that ink from an ink tank (not shown) can be supplied to the reservoir 23 via the housing 5.

The piezoelectric element 4 is a member according to the present invention, and is formed on the diaphragm 3 in a predetermined shape.

(Layer Structure of Piezoelectric Element) FIG.
And a layer structure of the piezoelectric element 4 is shown in a sectional view. As shown in the figure, the vibration plate 3 is configured by laminating an insulating film 301 and a lower electrode film 302, and the piezoelectric element 4 includes a low dielectric constant layer 401, a piezoelectric layer 402, and an upper electrode film 403. It is configured by lamination.

The insulating film 301 is made of a material having no conductivity, for example, silicon dioxide formed by thermally oxidizing a silicon substrate, and is deformed by a volume change of the piezoelectric element.
The pressure inside the cavity 21 can be instantaneously increased.

The lower electrode film 302 is an electrode for applying a voltage to the piezoelectric layer, which is paired with the upper electrode film 403, and is made of a plurality of conductive materials, for example, platinum (Pt).
It is composed of layers. The lower electrode film may be formed so as to overlap all the regions of the thermal oxide film 301 as shown in the figure, or may be formed only below the piezoelectric element 4. Further, the thickness in the lower portion of the piezoelectric element 4 and the thickness in other regions may be different.

The upper electrode film 403 is an electrode for applying a voltage to the piezoelectric element, and is formed of a conductive material, for example, platinum (Pt) having a thickness of 0.1 μm.

The piezoelectric layer 402 is made of a piezoelectric ceramic having piezoelectric characteristics. For example, lead titanate (PbTiO ₃ ), lead zirconate titanate (Pb
(Zr, Ti) O ₃ : PZT), lead zirconate (PbZ)
rO ₃ ), lead lanthanum titanate ((Pb, La) TiO
₃ ), lead lanthanum zirconate titanate ((Pb, La)
(Zr, Ti) O ₃ ): PLZT) or magnesium zirconium niobate lead titanate (Pb (Zr _0.56
Ti _0.44 ) _0.8 (Mg _1/3 Nb _2/3 ) _0.1
O ₃ ).

The low dielectric constant layer 401 is a layer having a low dielectric constant formed during the manufacturing process. This layer is formed naturally because the reaction between the piezoelectric material and the electrode material is at a high temperature in the process of forming and firing the piezoelectric layer by a sol-gel method or the like. The composition of the lower electrode film 302 is mixed in the layer. For example, P
When Pt is used as the piezoelectric ceramics, Pt, O, Ti, Zr, Pb
Etc. are included. Among them, the composition ratio of O and Ti is larger and the composition ratio of Zr and Pb is smaller than the composition of the other piezoelectric layers. The low dielectric constant layer 401 has a dielectric constant of about 3000 in other parts of the piezoelectric layer 402, whereas the low dielectric constant layer 401 has a relative dielectric constant of 100 or less.

Since the low dielectric constant layer lowers the dielectric constant of the entire piezoelectric element, the piezoelectric characteristics of the entire piezoelectric element deteriorate. In the conventional low dielectric constant layer, a crystal was not formed more favorably and was sometimes amorphous. In order to improve the piezoelectric characteristics of the entire piezoelectric element, it is preferable that the low dielectric constant layer be crystallized to be thin. In the present invention, the crystallized low dielectric constant layer has been successfully reduced in thickness by the manufacturing method described below.

Specifically, when a piezoelectric element is formed by a conventional manufacturing method, a low dielectric constant layer is formed with a thickness of 20 nm or more, and the low dielectric constant layer having this thickness has a piezoelectric characteristic of the piezoelectric element. Had deteriorated. On the other hand, when the piezoelectric element is formed by the manufacturing method of the present invention, the thickness of the low dielectric constant layer is suppressed to 10 nm or less when manufactured under suitable conditions, and is suppressed to 5 nm or less when manufactured under optimal conditions. be able to.

The thickness of the piezoelectric layer 402 is set to a thickness of 800 nm or more and 2000 nm or less. If the thickness of the piezoelectric layer is too large, a high driving voltage is required,
If the thickness is too small, when a driving voltage is applied, a high electric field may occur in the PZT film, the characteristics of the film may be deteriorated, or the film may be subjected to dielectric breakdown.

(Function) When the piezoelectric layer is dried and degreased, and finally the entire piezoelectric layer is baked, a dense perovskite crystal structure is developed from the amorphous molecular structure. It is thought that crystallization proceeds rapidly during firing, but if the firing temperature is too low and the firing time is long, constituent molecules of the lower electrode film are mixed into the piezoelectric material,
Segregation of the piezoelectric material occurs, and a low dielectric constant layer develops. Even if the firing time is short, if the firing temperature is too high, the constituent molecules of the lower electrode film are also mixed, segregation of the piezoelectric material occurs, and the low dielectric constant layer develops.

In the present invention, since the firing of the piezoelectric layer is performed under a constant condition, the generation of the low dielectric constant layer can be suppressed, and the thickness of the low dielectric constant layer is reduced to, for example, 10 nm or less. Can be. According to the piezoelectric element having the thin low dielectric constant layer, good piezoelectric characteristics are exhibited.

The ink jet recording head of the present embodiment is provided with a piezoelectric element exhibiting such good piezoelectric characteristics.
The operation principle of this ink jet recording head will be described. When no voltage is applied between the lower electrode 302 and the upper electrode 403 of the piezoelectric element 4, the volume of the piezoelectric layer 402 exhibiting piezoelectric characteristics does not change. Therefore, the pressure does not change in the cavity 21 formed corresponding to the piezoelectric element 4 to which no voltage is applied, and the nozzle 11
No ink droplet is ejected from the nozzle.

On the other hand, when a voltage causing a change in volume of the piezoelectric element 4 is applied between the lower electrode 302 and the upper electrode 403 of the piezoelectric element 4, the piezoelectric layer 402 changes in volume. Therefore, the diaphragm 3 to which the piezoelectric element 4 to which the voltage is applied is attached is largely bent,
The volume in the cavity 21 is changed. Therefore, the pressure in the cavity 21 changes, and ink droplets are ejected from the nozzles 11. According to the present invention, since the low-k layer 401 is thin, the piezoelectric characteristics of the piezoelectric element 4 do not deteriorate. For this reason, the volume change of the piezoelectric element is larger than that of the conventional one, and more ink can be ejected by applying a smaller voltage.

(Description of Manufacturing Method) Next, a method of manufacturing the ink jet recording head of the present invention will be described.

Oxide film forming step (FIG. 5A):
An insulating film 301, for example, a silicon dioxide film is formed on a silicon substrate 201 which is a base of the pressure chamber substrate 2. The silicon substrate 201 is, for example, about 200 μm
Is formed to a thickness of about 1 μm. For the production of insulating films,
A known thermal oxidation method or the like is used.

Lower electrode film forming step (FIG. 7B): Next, a lower electrode film 302 is formed on the insulating film 301. The lower electrode film 302 is formed, for example, by stacking a platinum layer with a thickness of 0.5 μm. For the production of these layers, a known direct current sputtering method or the like is used.

Piezoelectric layer forming step (FIG. 3C): The piezoelectric layer is preferably formed by a sol-gel method. However, a sputtering method or the like can also be used. Even when using a sputtering method or the like, it is necessary to control the firing temperature as described below.

In order to form the piezoelectric layer 402, first, a solution in which a piezoelectric ceramic having the above-described composition is mixed is prepared. Next, a solution mixed with a polymer substance is applied on the lower electrode film 302 to a certain thickness. For example, when a known spin coating method is used, 500 revolutions per minute is 30 seconds, 1500 revolutions per minute is 30 seconds, and finally 500 revolutions per minute.
Apply by rotation for 10 seconds. After application, a constant temperature (for example, 1
(80 degrees) for a certain period of time (for example, about 10 minutes).

After drying, a predetermined high temperature (for example, 400
Degreasing for a certain period of time (30 minutes).

The steps of coating, drying and degreasing are repeated a plurality of times. After the four layers are stacked, heat treatment is further performed in a predetermined atmosphere to promote crystallization of the ceramic layer and improve characteristics as a piezoelectric body. For example, after laminating four layers, rapid heat treatment (RAT) is performed in an oxygen atmosphere.
Then, heat at 600 degrees for 5 minutes and further at 725 degrees for 1 minute.

Final heat treatment step ((d) in the same figure): Next, after laminating eight layers, 6
Heat at 50 ° C. for 5 minutes and at the heat treatment temperature of the present invention for a short time (for example, 1 minute). This heat treatment temperature is 850.
It is important to set it between ℃ and 950 ℃. If the temperature is lower than this temperature, a long-time heat treatment is required to complete the crystallization, so that the mixing of the lower electrode material promotes the segregation of the piezoelectric material. Therefore, even if the heat treatment is short, the lower electrode material is mixed and the segregation of the piezoelectric material is promoted. In particular, heat treatment at a temperature of about 900 ° C. is preferable.
This is because, at this temperature, the thickness of the generated low dielectric layer 401 can be minimized.

By the above processing, the development of the low dielectric constant layer 401 is suppressed to a thickness of at least 10 nm or less, preferably 5 nm or less. The piezoelectric layer 402 has, for example, 0.8
It is formed with a thickness of about μm to 2 μm.

Upper electrode forming step (FIG. 9E): An upper electrode film 403 is further formed on the piezoelectric layer 402 by using a technique such as an electron beam evaporation method or a sputtering method. As a material of the upper electrode, platinum (Pt) or the like is used. The thickness is 100
nm.

Etching step (FIG. 6A): After forming each layer, the diaphragm film 3 (the insulating film 301 and the lower electrode film 30) is formed.
2) The above laminated structure (401, 402 and 403)
A mask is formed so as to have a shape corresponding to the shape of each cavity 21, and the periphery thereof is etched. That is, the low dielectric constant layer 401, the piezoelectric layer 402, and the upper electrode film 403 are removed. At the time of etching, a resist having a uniform thickness is applied using a method such as a spinner method or a spray method, and is exposed and developed to form a resist on the upper electrode film 403. Unnecessary layer structure portions are removed by applying ion milling, dry etching, or the like that is usually used. By removing unnecessary parts by etching,
The piezoelectric element 4 is formed.

Pressure chamber forming step (FIG. 2B): The other surface of the pressure chamber substrate on which the piezoelectric element 4 is formed is etched to form a cavity 21. For example, the cavity 21 space is etched using anisotropic etching using an active gas such as anisotropic etching and parallel plate type reactive ion etching. The portion left without being etched becomes the side wall 22. The pressure chamber substrate 2 has a cavity or the like formed by etching.

Bonding step (FIG. 10C): The nozzle plate 1 is bonded to the etched pressure chamber substrate 2 using a resin or the like. At this time, each nozzle 11 is
1 Align so that they are arranged in each space. When the pressure chamber substrate 2 to which the nozzle plate 1 is attached is attached to the housing 5 (see FIG. 2), the ink jet recording head 101
Is completed.

Example An example of a piezoelectric element manufactured according to the manufacturing method of the above embodiment will be described. The material constituting the piezoelectric layer is Pb (Zr _0.56 Ti _0.44 ) _0.9
One having a composition of (Mg _1/3 Nb _2/3 ) _0.1 O ₃ was used.

Table 1 shows the results of comparison between the embodiment of the ink jet recording head manufactured by the manufacturing method of the present invention and a comparative example of an ink jet recording head manufactured by the conventional manufacturing method. The comparison items are the piezoelectric d constant, the piezoelectric g constant, and the dielectric constant ε that determine the piezoelectric characteristics of the piezoelectric element, and the thickness of the piezoelectric layer. The suffix 31 of the piezoelectric d constant and the piezoelectric g constant indicates a constant in the thickness direction of the piezoelectric element.

[0056]

[Table 1]

As can be seen from Table 1, the heat treatment temperature was 850.
In the embodiment performed at a temperature in the range of 950 ° C. to 950 ° C., a low dielectric constant layer was successfully formed. Therefore, it can be seen that the dielectric constant of the entire piezoelectric element is high, and the piezoelectric d constant and the piezoelectric g constant are also high. On the other hand, in the comparative example where the heat treatment temperature is too high, the low dielectric constant layer is thick and the piezoelectric characteristics are poor. On the other hand, if the heat treatment temperature is lower than 850 ° C., the crystallinity of the piezoelectric layer deteriorates, and the piezoelectric characteristics also deteriorate.

FIG. 7 shows comparative photographs of the example of the present invention heat-treated at 900 ° C. and a conventional comparative example heat-treated at 1050 ° C. FIG (a) and (c) are in each examples and comparative examples, the cross-sectional TEM in the vicinity of the interface between the piezoelectric layer and the lower electrode film (T ransmission E lectron M icroscop
y) It is a photograph. FIGS. 3B and 3D are photographs showing cross-sectional transmission electron diffraction patterns of the low dielectric constant layer.

In FIGS. 7A and 7C, the line indicated by the arrow is the interface between the piezoelectric layer and the lower electrode film. The layer that looks white above the interface is the low dielectric constant layer. In the example (FIG. (A)), the low dielectric constant layer is suppressed to a thickness of 10 nm or less, but in the comparative example (FIG. (C)), the low dielectric layer develops to a thickness of 30 nm or more. doing. Also, in FIGS. 7B and 7D, white spots indicate crystals.

[0060] The cross-sectional EDX (E lectron D ispersive X -
Table 2 shows the compositions of the low dielectric constant layer and the piezoelectric layer analyzed by (ray).

[0061]

[Table 2]

As can be seen from Table 2, Pt which is the composition of the lower electrode film is mixed in the low dielectric constant layer. It can also be seen that the low dielectric layer has a higher composition of Ti and O and a lower composition of Pb and Zr, as compared to the piezoelectric layer.

As described above, according to the present embodiment, the development of the low dielectric constant layer can be suppressed by keeping the firing temperature and time of the piezoelectric layer constant. For this reason, the piezoelectric characteristics of the piezoelectric element can be improved.
Therefore, in the piezoelectric element manufactured by the manufacturing method of the present embodiment, a larger volume change can be caused in the piezoelectric element than in a conventional piezoelectric element. Further, in an ink jet recording head using this piezoelectric element, more ink can be ejected with a lower voltage than in the past.

<Other Modifications> The present invention can be applied to various modifications without depending on the above embodiments. For example, in the above embodiment, the piezoelectric layer is formed using the sol-gel method, but the piezoelectric layer may be formed using another method, for example, a sputtering method.

In the above embodiment, the piezoelectric layer is formed of a single piezoelectric material, but a different piezoelectric material may be used for each layer. Even when a different piezoelectric material is used, the generation of the low dielectric constant layer can be minimized if the final heat treatment temperature is controlled according to the above embodiment.

The piezoelectric element of the present invention is not limited to the piezoelectric element used in the above-mentioned ink jet recording head, but also includes a nonvolatile semiconductor memory device, a thin film capacitor, a pyroelectric detector, a sensor, and a surface acoustic wave optical waveguide. Piezoelectric devices such as tubes, optical storage devices, spatial light modulators, frequency doublers for diode lasers, dielectric devices, pyroelectric devices,
And the manufacture of electro-optical devices.

[0067]

According to the present invention, a layer having a low dielectric constant, which is generated at the time of manufacturing a piezoelectric element, is thinned, so that a piezoelectric element exhibiting good piezoelectric characteristics can be provided. Therefore, it is possible to provide a piezoelectric element having higher electromechanical conversion efficiency than before. In an ink jet recording head using this piezoelectric element, more ink can be ejected with a lower voltage than in the past.

Further, increasing the thickness of the piezoelectric layer is as follows.
Since the thickness of the low dielectric layer is relatively reduced, good piezoelectric characteristics and piezoelectric characteristics with little fluctuation can be obtained.

According to the present invention, when the piezoelectric element is manufactured,
Since specific manufacturing conditions for preventing generation of a layer having a low dielectric constant are provided, it is possible to manufacture a piezoelectric element having higher electromechanical conversion efficiency than before. In the ink jet recording head manufactured by the manufacturing method of the present invention,
More ink can be ejected with a smaller voltage than before.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a structure of an inkjet printer according to an embodiment.

FIG. 2 is a perspective view illustrating the structure of an ink jet recording head according to the embodiment.

FIG. 3 is a perspective view and a partial cross-sectional view of the ink jet recording head of the embodiment.

FIG. 4 is a cross-sectional view illustrating a laminated structure of the ink jet recording head of the present invention.

FIG. 5 is a manufacturing process sectional view for explaining the method for manufacturing the ink jet recording head of the present invention. (A) is an insulating film forming step, (b) is a lower electrode film forming step, (c) is a piezoelectric layer forming step, (d) is a heat treatment step, and (e) is an upper electrode film forming step.

FIG. 6 is a cross-sectional view showing a manufacturing process for explaining a method for manufacturing an ink jet recording head of the present invention. (A) is an etching step, (b) is a pressure chamber forming step, and (c) is a bonding step.

FIG. 7 is a comparative photograph of an example and a comparative example in the piezoelectric element of the present invention. (A) is a cross-sectional TEM photograph of the interface between the piezoelectric layer and the lower electrode film in the example, and (b) is a cross-sectional transmission electron diffraction photograph of the low dielectric constant layer in the example.
(C) is a cross-sectional TEM photograph of the interface between the piezoelectric layer and the lower electrode film in the comparative example, and (d) is an electron diffraction photograph of the low dielectric constant layer in the comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Nozzle plate 11 ... Nozzle 2 ... Pressure chamber substrate 21 ... Cavity 22 ... Side wall 23 ... Reservoir 201 ... Silicon substrate 3 ... Vibration plate 301 ... Insulating film 302 ... Lower electrode film 4 ... Piezoelectric element 401 ... Low dielectric constant layer 402 … Piezoelectric layer 403… Upper electrode film

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masami Murai 3-3-5 Yamato, Suwa-shi, Nagano Prefecture Seiko Epson Corporation

Claims (9)

[Claims] 1. A piezoelectric element having a piezoelectric layer sandwiched between electrode films, wherein a low dielectric constant layer having a lower dielectric constant than the piezoelectric layer has a thickness of 10 nm or less along the lower electrode film. A piezoelectric element characterized by being provided with a thickness. 2. The low dielectric constant layer has a relative dielectric constant of 1
2. The piezoelectric element according to claim 1, wherein the value is not more than 00. 3. The piezoelectric element according to claim 1, wherein the low dielectric constant layer contains a component constituting an electrode in contact with the low dielectric constant layer. 4. An ink-jet recording head configured to be able to eject ink from a nozzle communicating with a pressure chamber by applying a voltage to a piezoelectric element to cause a volume change, wherein the piezoelectric element comprises two piezoelectric elements. A piezoelectric layer formed of a piezoelectric material that changes in volume when an electric field is applied between the electrode films, and a piezoelectric layer having a thickness of 10 nm or less and having a dielectric constant lower than that of the piezoelectric layer. An ink jet recording head comprising: a dielectric layer. 5. A lower electrode film forming step of forming a lower electrode film made of a conductive material, and applying a piezoelectric material which changes in volume when an electric field is applied between the two electrode films. And baking the piezoelectric material at a temperature between 850 ° C. and 950 ° C. after the application of the piezoelectric material to form a piezoelectric layer. A method for manufacturing a piezoelectric element, comprising: an upper electrode film forming step of forming an electrode film. 6. The method for manufacturing a piezoelectric element according to claim 5, wherein in the firing step, firing is performed at a temperature of 900 ° C. 7. The method according to claim 5, wherein in the firing step, firing is performed for approximately one minute. 8. The method according to claim 1, wherein the applying step includes applying the piezoelectric material to a predetermined thickness, heating the applied piezoelectric material, firing the piezoelectric material, and drying the applied piezoelectric material a plurality of times. The method for manufacturing a piezoelectric element according to claim 5, wherein the method is repeated. 9. A method of manufacturing an ink jet recording head using the method of manufacturing a piezoelectric element according to claim 5, wherein the lower electrode is provided on a substrate on which an insulating film is formed. Forming the piezoelectric element composed of a film, a piezoelectric layer, and an upper electrode film, and then etching the piezoelectric element into a shape corresponding to a pressure chamber for discharging ink formed on the substrate. Forming the pressure chamber by etching the substrate corresponding to the position where the etched piezoelectric element is provided; and forming a pressure chamber with a nozzle for discharging ink to a position corresponding to the pressure chamber. Bonding the provided nozzle plate to the substrate, and manufacturing the ink jet recording head.