JP2003133605A - Ferroelectric substance element as well as actuator, ink jet head and ink jet recording device employing the element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ferroelectric substance element capable of contriving the improvement of the insulating property, reliability and resistance to pressure of a ferroelectric substance film. SOLUTION: The ferroelectric substance element is provided with a common electrode 11, a ferroelectric substance functional film 10 formed on the common electrode 11 and an individual electrode 3 formed on the ferroelectric substance functional film 10 while the ferroelectric substance functional film 10 is constituted of a ferroelectric substance film 10a and an insulation reinforced film 10b including at least one kind of the constituting elements of the ferroelectric substance film 10a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric element, an actuator using the same, an ink jet head and an ink jet recording apparatus.

[0002]

2. Description of the Related Art An ink jet head of an ink jet type recording apparatus comprises a pressure chamber component having a pressure chamber for containing an ink liquid, and a ferroelectric element which is an actuator portion for ejecting an ink droplet from this pressure chamber. ing. The ferroelectric element is provided with a ferroelectric film and individual electrodes and a common electrode that contract and expand by applying a voltage to the ferroelectric film, and the vibration that is displaced by the piezoelectric effect of the ferroelectric film is provided. The plate is configured to eject an ink droplet from the nozzle hole of the pressure chamber.

[0003]

Here, in the ferroelectric element, when a ferroelectric film is formed, a crystal structure defect or an abnormal growth of crystal grains occurs inside due to inclusion of foreign matter, Defects such as gaps and pinholes occur at the interface between the ferroelectric film and the abnormally grown grains. Then, when a ferroelectric element is formed using such a ferroelectric film, even if a voltage lower than the withstand voltage originally possessed by the film is applied between the individual electrode and the common electrode from the defect as a starting point. Dielectric breakdown may occur.

In addition, there is a problem that the insulating property of the film remarkably deteriorates when moisture enters the above defects. Therefore, in order to strengthen the insulating property of the ferroelectric film and prevent dielectric breakdown,
The following techniques are disclosed.

That is, Japanese Patent Laid-Open No. 2-49471 discloses a lower electrode, a polysilicon oxide film formed on the lower electrode, a ferroelectric film formed on the polysilicon oxide film, and a ferroelectric film. A semiconductor device including an upper electrode formed on a body film is disclosed.

Further, Japanese Patent No. 3111416 discloses that
An active element such as a transistor formed on a semiconductor,
The main component is SiN between the ferroelectric capacitor
A technique of forming an insulating film made of is disclosed.

In Japanese Patent No. 3139491, a ferroelectric element having a structure in which a ferroelectric material is sandwiched between two electrodes is provided with SiO between a peripheral portion of at least one electrode and the ferroelectric film. A technique for forming a paraelectric layer composed of _two films is disclosed.

[0008]

In the conventional technique as described above, a polysilicon oxide film or a SiN film is laminated to improve the withstand voltage of the ferroelectric film. There was a problem with reliability because of poor adhesion with.

The dielectric constant of the polysilicon oxide film or SiN film is 10 or less, and the dielectric constant of the ferroelectric film is 100 to 1
Since it is significantly smaller than 000, the voltage applied to the ferroelectric film is lowered if the film thickness is increased and sufficient pressure resistance is secured. Therefore, there is a problem that the drive voltage of the actuator becomes high.

Therefore, the present invention provides a ferroelectric element capable of improving the insulation property of the ferroelectric film as well as the reliability and the pressure resistance, an actuator using the same, an ink jet head and an ink jet recording apparatus. The purpose is to

[0011]

In order to solve this problem, a ferroelectric element of the present invention comprises a first electrode, a ferroelectric functional film formed on the first electrode, and a ferroelectric film. And a second electrode formed on the body function film, wherein the ferroelectric function film comprises:
It is composed of a ferroelectric film and an insulation strengthening film containing at least one element of the constituent elements of the ferroelectric film.

As described above, since the ferroelectric functional film composed of the ferroelectric film and the insulation strengthening film containing at least one element of the constituent elements of the ferroelectric film is formed between the electrodes, the ferroelectric film is formed. Defects (such as gaps and pinholes that occur at the interface between the ferroelectric film and abnormally grown grains) that cause a decrease in the insulating property of the body film are completely covered by the insulation strengthening film to improve the insulation property of the ferroelectric film. In addition, the adhesion between the ferroelectric film and the insulation-strengthening film is good, and the dielectric constant of the insulation-strengthening film is close to that of the ferroelectric film, so that the reliability and pressure resistance of the ferroelectric film are improved. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention comprises a first electrode, a ferroelectric functional film formed on the first electrode, and a ferroelectric functional film formed on the ferroelectric functional film. And a second electrode, and the ferroelectric functional film is composed of a ferroelectric film and an insulation-strengthening film containing at least one element of constituent elements of the ferroelectric film. That is, the defect of the ferroelectric film is covered with the insulation strengthening film to improve the insulation property of the ferroelectric film, and the adhesion between the ferroelectric film and the insulation strengthening film is good and the dielectric property of the insulation strengthening film is good. The coefficient is close to the dielectric constant of the ferroelectric film, which has the effect of improving the reliability and pressure resistance of the ferroelectric film.

According to a second aspect of the present invention, in the first aspect of the invention, the ferroelectric film is Pb, La or Z.
A ferroelectric element which is a perovskite type oxide containing at least one element of r and Ti, in which defects of the ferroelectric film are covered with an insulation strengthening film to improve the insulation property of the ferroelectric film, Adhesion between the ferroelectric film and the insulation-strengthening film is good, and the dielectric constant of the insulation-strengthening film is close to that of the ferroelectric film, so that the driving voltage is reduced.

A third aspect of the present invention is the ferroelectric element according to the second aspect, wherein the Pb content of the insulation strengthening film is higher than the Pb content of the ferroelectric film. This has the effect of increasing the Pb concentration on the surface of the dielectric film, lowering the crystallinity, and further strengthening the insulating property of the insulating reinforcing film.

The invention according to claim 4 of the present invention is the ferroelectric element according to the invention according to claim 2 or 3, wherein the oxygen content of the insulation strengthening film is higher than the oxygen content of the ferroelectric film. Also, it has an effect that the insulation property of the insulation strengthening film can be enhanced.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the crystallinity of the insulation strengthening film is lower than that of the ferroelectric film. The device is a body element, and the defects of the ferroelectric film are covered with the insulation strengthening film to improve the insulation property of the ferroelectric film, and the adhesion between the ferroelectric film and the insulation strengthening film is good and the insulation strengthening film is also provided. Has the effect of improving the reliability and withstand voltage of the ferroelectric film by making the dielectric constant thereof close to that of the ferroelectric film.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the insulating reinforcing film is at least one of a pyrochlore type oxide and a perovskite type oxide. It is a ferroelectric element that is a polycrystalline film or an amorphous film containing, and the defects of the ferroelectric film are covered by the insulation strengthening film to improve the insulation property of the ferroelectric film and to enhance the insulation between the ferroelectric film and Adhesion to the film is good, and the dielectric constant of the insulation-strengthening film is close to that of the ferroelectric film, so that the reliability and pressure resistance of the ferroelectric film are improved.

The invention according to claim 7 of the present invention is an actuator using the ferroelectric element according to any one of claims 1 to 6, and is capable of performing stable displacement operation. Has the effect of becoming.

The invention according to claim 8 of the present invention is an ink jet head provided with the actuator according to claim 7 and a plurality of pressure chambers in which ink liquid is accommodated and on which the displacement of the actuator acts, which is stable. It has an effect of enabling ink ejection.

According to a ninth aspect of the present invention, there is provided an ink jet recording apparatus including the ink jet head according to the eighth aspect, which is capable of performing high-quality printing by stable ink ejection. Have.

FIG. 1 shows an embodiment of the present invention.
It will be described with reference to FIG. In addition, in these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

FIG. 1 is a perspective view showing an overall schematic structure of an ink jet recording apparatus using a ferroelectric element according to an embodiment of the present invention, and FIG. 2 shows an ink jet head in the ink jet recording apparatus of FIG. FIG. 3 is a cross-sectional view showing the overall structure, FIG. 3 is a perspective view showing a main part of FIG. 2, FIG. 4 is a cross-sectional view showing the structure of an actuator part of the inkjet head of FIG. 2, and FIG. 5 is an embodiment of the present invention. 6 is a sectional view showing the ferroelectric element, FIG. 6 is an explanatory view showing the configuration of a cantilever for measuring piezoelectric displacement, and FIG. 7 is a sectional view showing a method for manufacturing an actuator.

The ink jet recording apparatus 40 shown in FIG.
Is equipped with an inkjet head 41 of the present invention for recording by utilizing the piezoelectric effect of a ferroelectric element, and ink droplets ejected from this inkjet head 41 are made to land on a recording medium 42 such as paper to form a recording medium 42. It is to record. The inkjet head 41 is mounted on a carriage 44 provided on a carriage shaft 43 arranged in the main scanning direction X, and reciprocates in the main scanning direction X as the carriage 44 reciprocates along the carriage shaft 43. Move. Further, the inkjet recording apparatus 40 includes a plurality of rollers (moving means) 45 for moving the recording medium 42 in the sub-scanning direction Y which is substantially perpendicular to the width direction of the inkjet head 41 (that is, the main scanning direction X). .

FIG. 2 shows the overall construction of the ink jet head 41 according to the embodiment of the present invention, and FIG. 3 shows the construction of the essential parts thereof.

2 and 3, A is a pressure chamber component in which the pressure chamber opening 1 is formed. B is an actuator portion arranged so as to cover the upper end opening surface of the pressure chamber opening portion 1, and C is an ink liquid flow path component arranged so as to cover the lower end opening surface of the pressure chamber opening portion 1. The pressure chamber opening 1 of the pressure chamber component A is partitioned by the actuator unit B and the ink liquid flow channel component C located above and below to form a pressure chamber 2. In the actuator section B, an individual electrode (second electrode) 3 located above the pressure chamber 2 is arranged. These pressure chambers 2 and individual electrodes 3 are arranged in a zigzag pattern, as can be seen from FIG. In the ink liquid flow path component C, a common liquid chamber 5 that is shared between the pressure chambers 2 arranged in the ink liquid supply direction, a supply port 6 that connects the common liquid chamber 5 to the pressure chamber 2, and a pressure chamber 2 An ink flow path 7 through which the ink liquid flows is formed. D is a nozzle plate having nozzle holes 8 communicating with the ink flow paths 7. Also,
In FIG. 2, E is an IC chip, which supplies a voltage to a large number of individual electrodes 3 via the bonding wires BW.

Next, the structure of the actuator section B will be described with reference to FIG.

In the figure, the actuator section B is a sectional view in a direction orthogonal to the ink liquid supply direction shown in FIG. In the figure, a pressure chamber component A having four pressure chambers 2 arranged in the orthogonal direction is drawn for reference.

The actuator section B is displaced by the individual electrode 3 located above each pressure chamber 2, the ferroelectric functional film 10 located immediately below the individual electrode 3, and the piezoelectric effect of the ferroelectric functional film 10. And a vibrating plate 11 that vibrates.
The diaphragm 11 is made of a conductive material and also serves as a common electrode (first electrode) common to the pressure chambers 2. Further, the actuator portion B has a vertical wall 13 located above the partition wall 2a that partitions the pressure chambers 2 from each other. In addition,
In the figure, reference numeral 14 is an adhesive for bonding the pressure chamber component A and the actuator portion B. Each vertical wall 13 does not adhere to the diaphragm 11 even if a part of the adhesive 14 protrudes to the outside of the partition wall 2a at the time of bonding with the adhesive 14. It has a role of expanding the distance between the upper surface of the pressure chamber 2 and the lower surface of the vibration plate 11 so that the displacement and vibration of the vibration plate 11 occur as expected. However, the diaphragm and the common electrode may be separate bodies.

Then, the individual electrode 3 and the ferroelectric functional film 10
Further, the common electrode 11 constitutes a ferroelectric element.

The individual electrode 3 is, for example, Pt (platinum).
The vibration plate 11 is made of, for example, Cr (chrome), Cu (copper),
It is formed of Mo (molybdenum) or Ta (tantalum). The individual electrode 3 has a thickness of 0.1 to 1.0 μm.
In addition, the ferroelectric functional film 10 has a thickness of 2 to 6 μm and the diaphragm 1
1 has a thickness of 3 to 10 μm.

As shown in FIG. 5, the ferroelectric functional film 10
Is a ferroelectric film 10a which is a perovskite type oxide made of, for example, lead zirconate titanate (PZT), and at least one element of the constituent elements of the ferroelectric film 10a (in this case, Pb, Zr , And at least one kind of element of Ti).

A PLT film {eg (Pb _0.9 La _0.1 ) TiO ₃ } or a PLZT film {eg (Pb _0.9 La _0.1 ) (Zr _0.52 Ti _0.48 ) O ₃ } is applied to the ferroelectric film 10 a. You can also So in this case,
The insulation-strengthening film 10b contains at least one element of Pb, La, and Ti.

FIG. 5 shows the actuator section B, in which the common electrode 11 and the ferroelectric film 1 are formed on the substrate corresponding to the vertical wall 13.
0a, the insulation-strengthening film 10b, and the individual electrode 3 are sequentially formed, so that the insulation-strengthening film 10b is located between the ferroelectric film 10a and the individual electrode 3. , Ferroelectric film, insulation strengthening film, common electrode,
When the MgO substrate is removed by etching after it is bonded to the substrate corresponding to the vertical wall, the insulation strengthening film is located between the ferroelectric film and the common electrode. Therefore,
In FIG. 5, the ferroelectric film 10a is on the diaphragm 11 side,
Although the insulation strengthening film 10b is formed on the individual electrode 3 side,
The reverse is also acceptable. Furthermore, the insulation strengthening film 10b need not be a single layer, and may be formed on both sides of the ferroelectric film 10a. Further, the ferroelectric film 10a and the insulation strengthening film 10
It may have a repeating structure of stacked layers b.

If the PLT film is formed and the ferroelectric film 10a such as the PZT film is formed on the PLT film, the crystallinity of the ferroelectric film 10a is improved.

Here, the insulation strengthening film 10b is a low crystalline film such as a polycrystalline film of a pyrochlore type oxide film, a polycrystalline film of a perovskite type oxide, or an amorphous film having no crystallinity. The insulation-strengthening film 10b may be formed of a pyrochlore-type oxide polycrystalline film and a perovskite-type oxide polycrystalline film.

Such a low crystalline film is produced, for example, under any of the following conditions or a combination thereof.

That is, the first condition is that the film forming temperature is lower than that at the time of manufacturing the ferroelectric film (500 to 600 ° C.). As a result, an amorphous film is formed at room temperature, and a pyrochlore film is formed at 350 to 450 ° C., for example. Note that the first condition has an advantage that a desired thin film can be easily formed because a separate sputtering device is not necessary and film forming conditions are changed.

The second condition is that the pressure at the time of sputtering is made higher than that at the time of manufacturing the ferroelectric film (0.1 to 0.3 Pa),
For example, it is set to 2 to 3 Pa.

The third condition is the oxygen partial pressure (O ₂ /
The Ar flow rate ratio) is set to be, for example, 30 to 50% higher than that at the time of manufacturing the ferroelectric film (2 to 10%).

However, the film formation is not limited to the sputtering method, for example, MO-CV using an organic metal.
Of course, other film forming techniques such as the D method and the sol-gel method can be applied.

As described above, in the ferroelectric element of the present embodiment, the ferroelectric film 10a and the insulation strengthening film 10 containing at least one element of the constituent elements of the ferroelectric film 10a.
Since the ferroelectric functional film 10 made of b is formed between the electrode 3 and the diaphragm (common electrode) 11, the ferroelectric film 10a
Gaps and pinholes that occur at the interface between
Defects that cause deterioration of the insulation property of the ferroelectric film 10a are completely covered with the insulation strengthening film 10b, and the insulation property of the ferroelectric film 10a is improved.

Further, since the insulation strengthening film 10b is a film containing at least one element of the constituent elements of the ferroelectric film 10a, the adhesion with the ferroelectric film 10a is improved. As a result, the reliability of the ferroelectric film 10a is improved.

Further, the insulation strengthening film 10b is the ferroelectric film 1
Since the film contains at least one of the constituent elements of 0a, the dielectric constant of the insulation strengthening film 10b becomes close to the dielectric constant of the ferroelectric film 10a, and it is possible to reduce the driving voltage. Become.

Here, the insulation strengthening film 10 is formed at the time of film formation.
If the Pb content of b is made larger than the Pb content of the ferroelectric film 10a, the Pb concentration on the surface of the ferroelectric film 10a becomes high, the crystallinity is lowered, and the crystal grains inside the ferroelectric film 10a are reduced. Abnormal growth can be stopped, and since the defective portion is covered, the insulation property of the insulation strengthening film 10b is further strengthened.

In addition, during film formation, the insulation strengthening film 10b is formed.
If the oxygen content of the above is made higher than the oxygen content of the ferroelectric film 10a, it is possible to enhance the insulating property of the insulation strengthening film 10b.

Further, if the crystallinity of the insulation strengthening film 10b is made lower than that of the ferroelectric film 10a, the insulation property of the insulation strengthening film 10b can be similarly enhanced.

Here, the crystallinity is measured by the X-ray diffraction method or the electron beam diffraction method. For example, when the ferroelectric film is an epitaxial single crystal film, the electron beam diffraction pattern shows a spot pattern, but when the low crystalline film is polycrystalline, it has a ring pattern. Furthermore, in the case of an amorphous film, the ring shape becomes unclear and becomes a halo pattern. In the case of the X-ray diffraction method, the crystallinity is judged by the half width of a specific diffraction peak obtained from the ferroelectric film. A case where perovskite type PZT is used for the ferroelectric film will be described. For example, it is diffracted from the PZT film (001)
The full width at half maximum of the diffraction peak represents the crystallinity of the PZT film. This P
When a low crystalline film is formed on the ZT film as an insulation strengthening film,
The half-width of the PZT (001) diffraction peak increases due to the diffraction line from the PZT film being scattered by the low-crystal film formation. PZ
When the half-width increase rate when the half-width of the T (001) diffraction peak increases from a0 to a is defined as p = (a−a0) / a0, 1 <p ≦ 2.5 is desirable. Furthermore, 1.2 <
It is desirable that p ≦ 2.5, more desirably 1.5 <p ≦ 2.5. When p> 2.5, the characteristics of the ferroelectric film are significantly deteriorated and the driving voltage is increased, which is not desirable. In order to suppress the increase in driving voltage within 30%, 1 <p ≦ 2.
Must be 5. 1.2 <p ≦ 2.5 is required to improve the dielectric strength by 20% or more, and further 50%
In order to improve above, it is necessary that 1.5 <p ≦ 2.5.

Here, as an embodiment, in FIG. 5, the MgO substrate is used for the vertical wall 13, and the MgO substrate is
Pt is used for the diaphragm 11 and PZT {Pb is used for the ferroelectric film 10a.
_{(Zr 0. 53 Ti 0.47) O} 3}, using the Pt individual electrodes 3, evaluation of the piezoelectric properties and the insulating properties of the film using a variety of film reinforced insulation film 10b.

First, a Pt film 0.2 μm and a PZT film 2.7 μm were continuously formed on a MgO single crystal substrate having a (100) orientation. An RF magnetron sputtering device was used as the film forming device. Pt film is Ar gas, 0.3 Pa, substrate temperature 6
The PZT film is formed at 50 ° C., and the PZT film is made of Ar with an oxygen partial pressure of 10%.
The film was formed at a mixed gas of r, 0.3 Pa, and a substrate temperature of 620 ° C. When the crystal structure of the film was analyzed using a powder X-ray diffractometer, both the Pt film and the PZT film were epitaxial films aligned in the (001) orientation of the MgO single crystal substrate.

Next, using the same PZT target, RF
Insulation enhancement film 0.3μm by magnetron sputtering equipment
Was formed.

Sample A was formed at a substrate temperature of 400 ° C. The other sputtering conditions were the same as for the PZT film.

Sample B was deposited at a sputtering pressure of 2 Pa. The other sputtering conditions were the same as for the PZT film.

Sample C was deposited at an oxygen partial pressure of 50%. The other sputtering conditions were the same as for the PZT film.

In Comparative Example D, a SiO ₂ film was formed by sputtering as a comparative example.

Comparative example E is PZT 3 μm as a comparative example.
Was formed, but the insulation-strengthening film was not formed.

When the crystal structure of the films of Samples A, B, and C was analyzed using a powder X-ray diffractometer, the structure of the insulation-strengthening film was amorphous, pyrochlore polycrystal, perovskite polycrystal, or a mixture of these crystal phases. I found out. Further, the compositions of the ferroelectric film and the insulation-strengthening film were measured by EPMA analysis, and the results shown in (Table 1) were obtained. The insulation strengthening film has a Pb content (Pb / (Zr +
Ti) atomic ratio) or oxygen content (O / (Zr +
There are many Ti) atomic ratios.

[0058]

[Table 1]

A Pt film was sputtered on the above sample at room temperature to form an upper electrode. The relative values of the dielectric breakdown voltage of each sample and the voltage (driving voltage) applied to the upper and lower electrodes to obtain the same piezoelectric displacement are summarized in (Table 2). The dielectric breakdown voltage was defined as the voltage at which the leakage current density of the device was 1 μA / cm ² or more. Piezoelectric displacement has a length of 15
A plate-shaped cantilever having a width of 2 mm and a width of 2 mm was prepared, and the displacement at the other end when one end was fixed and a voltage was applied was measured by a laser Doppler displacement meter.

[0060]

[Table 2]

As described above, the use of the present invention makes it possible to obtain high insulation and reduce the driving voltage.

In the present embodiment, Mg of the (100) orientation is used.
Although the ferroelectric film epitaxially grown on the O single crystal substrate is used, the effect of the present invention is not impaired even if, for example, a Pt polycrystalline film or a ferroelectric polycrystalline film is formed on a Si substrate or a quartz substrate. .

Next, the production of the actuator for the ink jet head will be described with reference to FIG. FIG. 7A shows the structure of Sample A, 71 is a MgO single crystal substrate, and 72 is
Is a Pt film that serves as a diaphragm and a common electrode, 73 is a PZT epitaxial film that is a ferroelectric film, 74 is a low crystal film that is an insulation strengthening film, and 75 is a Pt film that is an individual electrode. Next, a desired portion of the MgO substrate is removed by etching to form the structure shown in FIG. 7B. For etching the MgO substrate, an aqueous phosphoric acid solution heated to 80 ° C. was used. A resist may be applied to portions where MgO is desired to remain to prevent etching by phosphoric acid. Since the Pt film is not dissolved by phosphoric acid, the MgO etching does not proceed any further when it reaches the Pt film. Alternatively, a part of MgO may be left and used as a diaphragm. Further, a resist or polyimide is formed as the ink blocking layer 76 on the surface of the MgO substrate side. With such a construction method, an actuator corresponding to the actuator section B in FIG. 5 can be manufactured, and further, the inkjet head shown in FIG. 4 can be manufactured.

In the present embodiment described above, the case where the ferroelectric element of the present invention is applied to an actuator used for ink ejection of an ink jet recording apparatus has been described, but a temperature sensor utilizing its pyroelectricity is used. And optical modulators that utilize the electro-optic effect, optical actuators that utilize the photoelastic effect, and SAW devices,
It can be applied to various other uses.

Further, in the present embodiment, for convenience of explanation,
Although the individual electrode 3 is used as the second electrode and the common electrode 11 is used as the first electrode, the individual electrode 3 may be used as the first electrode and the common electrode (diaphragm 11) may be used as the second electrode.

It should be noted that the actuator using the ferroelectric element described above makes it possible to perform a stable displacement operation, and the ink jet head using such an actuator ensures stable ink ejection. It will be possible to do. Then, according to the ink jet type recording apparatus including such an ink jet head, it is possible to perform high quality printing by stable ink ejection.

[0067]

As described above, according to the present invention, the ferroelectric functional film composed of the ferroelectric film and the insulation strengthening film containing at least one element of the constituent elements of the ferroelectric film is provided between the electrodes. Since it is formed on the ferroelectric film, the defect that causes the deterioration of the insulation property of the ferroelectric film is completely covered with the insulation strengthening film to improve the insulation property of the ferroelectric film, and the ferroelectric film and the insulation strengthening film are Adhesiveness with is good, and the dielectric constant of the insulation-strengthening film is close to that of the ferroelectric film, so that an effective effect that the driving voltage can be reduced can be obtained.

Further, if the Pb content of the insulation strengthening film is made higher than the Pb content of the ferroelectric film, P on the surface of the ferroelectric film is increased.
An effective effect is obtained in which the b concentration is increased, the crystallinity is lowered, and the insulation property of the insulation strengthened film is further strengthened.

When the oxygen content of the insulation-strengthening film is made larger than that of the ferroelectric film, the effective effect of enhancing the insulation property of the insulation-strengthening film can be obtained.

If the crystallinity of the insulation-strengthening film is made lower than that of the ferroelectric film, the effective effect that the insulation property of the insulation-strengthening film can be enhanced can be obtained.

According to the actuator using such a ferroelectric element, an effective effect that a stable displacement operation can be performed can be obtained.

According to the ink jet head using such an actuator, an effective effect that it becomes possible to perform stable ink ejection can be obtained.

According to the ink jet recording apparatus equipped with such an ink jet head, it is possible to obtain an effective effect that high quality printing can be performed by stable ink ejection.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall schematic configuration of an ink jet recording apparatus using a ferroelectric element according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the overall configuration of an inkjet head in the inkjet recording apparatus of FIG.

FIG. 3 is a perspective view showing a main part of FIG.

FIG. 4 is a cross-sectional view showing a configuration of an actuator section of the inkjet head shown in FIG.

FIG. 5 is a sectional view showing a ferroelectric element according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a configuration of a cantilever for measuring piezoelectric displacement.

FIG. 7 is a cross-sectional view showing a method for manufacturing an actuator.

[Explanation of symbols]

3 Individual electrodes (second electrode) 10 Ferroelectric functional film 10a Ferroelectric film 10b Insulation reinforced film 11 Vibration plate (also serves as the common electrode (first electrode)) 41 inkjet head 40 Inkjet recording device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuo Nishimura             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Shintaro Hara             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2C057 AF65 AF70 AF93 AG43 AG47                       AP16 AP52 BA04 BA14

Claims (9)

[Claims] 1. A ferroelectric film having a first electrode, a ferroelectric functional film formed on the first electrode, and a second electrode formed on the ferroelectric functional film. The ferroelectric element is characterized in that the dielectric functional film is composed of a ferroelectric film and an insulation-strengthening film containing at least one element of the constituent elements of the ferroelectric film. 2. The ferroelectric film is Pb, La, Zr, T.
The ferroelectric element according to claim 1, which is a perovskite type oxide containing at least one element of i. 3. The ferroelectric element according to claim 2, wherein the Pb content of the insulation strengthening film is higher than the Pb content of the ferroelectric film. 4. The oxygen content of the insulation-strengthening film is higher than the oxygen content of the ferroelectric film.
Alternatively, the ferroelectric element described in 3 above. 5. The ferroelectric element according to claim 1, wherein the crystallinity of the insulation strengthening film is lower than the crystallinity of the ferroelectric film. 6. The insulation-strengthening film is a polycrystalline film or an amorphous film containing at least one of a pyrochlore type oxide and a perovskite type oxide, and any one of claims 1 to 5. 2. The ferroelectric element according to. 7. An actuator comprising the ferroelectric element according to any one of claims 1 to 6. 8. An ink jet head, comprising: the actuator according to claim 7; and a plurality of pressure chambers in which ink liquid is contained and on which displacement of the actuator acts. 9. An ink jet recording apparatus comprising the ink jet head according to claim 8.