JP6175956B2 - ELECTRO-MECHANICAL CONVERSION ELEMENT, DROPLET DISCHARGE HEAD HAVING ELECTRO-MACHINE CONVERSION ELEMENT, AND DROPLET DISCHARGE DEVICE HAVING DROPLET DISCHARGE HEAD - Google Patents

Description

  The present invention relates to an electro-mechanical conversion element used as a drive source of a liquid droplet ejection head for ejecting a liquid droplet of ink or the like provided in an ink jet image forming apparatus, and a liquid droplet in which such electro-mechanical conversion element is arranged. The present invention relates to an ejection head and a droplet ejection apparatus provided with such a droplet ejection head.

A configuration example of a liquid droplet ejection head that is provided in an ink jet recording apparatus (liquid droplet ejection apparatus) used as an image recording apparatus or an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, etc. There is something as shown in 1.
That is, in the configuration of FIG. 1, a nozzle 102 that ejects ink droplets and a pressure chamber 101 (this is also referred to as an ink flow path, a pressurized liquid chamber, a pressure chamber, a discharge chamber, a liquid chamber, and the like) that communicate with the nozzle. ), An electro-mechanical conversion element 109 such as a piezoelectric element that pressurizes ink in the pressurizing chamber (or an electro-thermal conversion element such as a heater), and a diaphragm that forms the wall surface of the ink flow path [base (105)] And an energy generating means composed of an electrode opposed to the ink, and an ink droplet is ejected from the nozzle 102 by pressurizing the ink in the pressure chamber 101 with the energy generated by the energy generating means. In FIG. 1, a voltage is applied to the lower electrode (106) and the upper electrode (108) to vibrate the electromechanical conversion film 107 to generate the energy. In FIG. 1, reference numeral 103 denotes a nozzle plate, and 104 denotes a pressure chamber substrate (Si substrate).

  The droplet discharge head uses a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of an electro-mechanical conversion element (abbreviated as “piezoelectric element”) and a flexural vibration mode piezoelectric actuator. Two types have been put into practical use. As an actuator using a flexural vibration mode actuator, for example, a uniform electro-mechanical conversion film (piezoelectric material layer: abbreviated as “piezoelectric film”) is formed over the entire surface of the diaphragm by a film forming technique. A known piezoelectric element is formed by cutting this piezoelectric film into a shape corresponding to a pressure chamber by lithography and forming each piezoelectric chamber independently. In such a piezoelectric actuator, when the vector component of the spontaneous polarization axis of the piezoelectric film coincides with the electric field application direction, the expansion and contraction accompanying the increase and decrease of the electric field application intensity occurs effectively, and a large piezoelectric constant is obtained. Most preferably, the spontaneous polarization axis of the film and the electric field application direction completely coincide. Further, in order to suppress variations in the ink discharge amount, it is preferable that the in-plane variation in the piezoelectric performance of the piezoelectric film is small. Considering these points, a piezoelectric film having excellent crystal orientation is preferable.

  As a technique related to crystal orientation, for example, in Patent Document 1, a piezoelectric film having excellent crystal orientation can be formed by forming a piezoelectric film on a Ti-containing noble metal electrode having Ti deposited in an island shape on the surface. It is described. Patent Document 2 describes that a piezoelectric film having excellent crystal orientation can be formed by using an MgO substrate as a substrate. Patent Document 3 describes a method of manufacturing a ferroelectric film in which an amorphous ferroelectric film is formed and then the film is crystallized by a rapid heating method. Alternatively, Patent Document 4 discloses a perovskite-type composite oxide having a crystal structure of any one of a tetragonal system, an orthorhombic system, and a rhombohedral system in the step of forming a piezoelectric film having crystal orientation. (Which may contain unavoidable impurities) and is preferentially oriented to any one of the (100) plane, (001) plane, and (111) plane, and the degree of orientation is 95% or more. A manufacturing method is described.

In Patent Documents 1 to 4, PZT (lead zirconate titanate) is formed as a piezoelectric film or a ferroelectric film on a platinum (Pt) electrode, and the adhesion between Pt and the substrate (SiO ₂ ). Titanium (Ti) is used for improving the property, and TiN or the like is used as a diffusion barrier layer of Pb or the like. For this reason, in addition to a complicated electrode structure, there is a problem that oxidation of Ti, diffusion of Ti into Pt, and accompanying crystallinity deterioration of PZT occur, and electrical characteristics such as piezoelectric characteristics deteriorate. Since there is such a problem when PZT is formed on a Pt electrode, conductive oxide electrode materials such as RuOx and IrO ₂ have been studied as an alternative to the Pt electrode in fields such as ferroelectric memory. .
Among them, strontium ruthenate (SrRuO ₃ : abbreviation, “SRO”) has the same perovskite crystal structure as PZT, and therefore has excellent bonding properties at the interface, facilitates the epitaxial growth of PZT, and is a Pb diffusion barrier. Excellent properties as a layer.

Patent Documents 5 to 7 have been proposed as techniques using strontium ruthenate (SRO) having a perovskite structure.
For example, Patent Document 5 discloses a lower electrode including a (111) -oriented strontium ruthenate (SRO) having a perovskite structure and having a structure in which an iridium or platinum layer is sandwiched between two SRO layers. A piezoelectric actuator is described that includes an electrode, a piezoelectric layer made of PZT with (111) orientation formed on the lower electrode, and an upper electrode formed on the piezoelectric layer.
Patent Document 6 describes a semiconductor device having a capacitor that includes an SRO and sandwiches a dielectric film between at least one of an upper electrode and a lower electrode.
Patent Document 7 describes a structure in which an epitaxial film (100) mainly composed of SRO is formed on a Si (100) substrate and the surface roughness (average roughness) is 10 nm or less. Yes.
Further, in Patent Document 8, a perovskite-type metal oxide comprising a lower electrode [a conductive film selected from a noble metal film and a noble metal oxide film, and an SRO film provided between the dielectric film and the conductive film. A material film (having a thickness of 5 nm or less) and a metal film made of a Ti film provided between the conductive film and the metal oxide film], an upper electrode, the lower electrode, and the upper electrode And a dielectric film provided between the capacitor and the capacitor.
In Patent Document 9, as a constituent material of the lower electrode (first electrode) instead of Pt, for example, a conductive oxide such as RuOx or IrO ₂ , particularly a perovskite structure such as strontium ruthenate (SrRuO ₃ ) is used. Electronic devices using metal oxides are described.
Further, in Patent Document 10, a diaphragm formed on a Si substrate, a buffer layer (consisting of (100) -oriented or (110) -oriented SRO), and a lower electrode ((100) -oriented having a perovskite structure). A piezoelectric actuator comprising a strontium ruthenate, a piezoelectric layer made of (100) oriented PZT, and an upper electrode is described.
Patent Document 11 describes a piezoelectric thin film element in which a titanium oxide film is provided below a lower electrode (a crystal body made of a compound of platinum and titanium oxide).
In Patent Documents 12 to 16, there is a description of domains and twin planes composed of (100) and (001) planes, particularly with respect to (100) and (001) planes of a tetragonal crystal of PZT. For example, Patent Document 13 describes that there is an optimal ratio of the volume ratio of tetragonal a-domain and c-domain.
In Patent Document 17, an electrode 14 made of a Pt group element having (111) orientation, an electrode 15 formed on the electrode 14, and PZT formed on the electrode 15 and having (111) as a preferred orientation. It has an electromechanical conversion film 16, an individual electrode 17 formed on the film 16, and a metal individual electrode 18 formed on the electrode 17. The electrodes 15 and 17 are made of strontium ruthenate, and the electrode 15 Describes an electromechanical conversion element having a (111) orientation having a perovskite structure, a surface roughness of 4 nm to 15 nm, and a thickness of 40 nm to 150 nm.

In Patent Documents 1 to 4, in addition to the complicated electrode structure for forming PZT (lead zirconate titanate) on a platinum (Pt) electrode, oxidation of titanium (Ti) and Ti There is a problem that the crystallinity of PZT is lowered with the diffusion into Pt and the piezoelectric characteristics are deteriorated.
In Patent Document 5, there is no specific and detailed description of the degree of orientation or the like for the (111) orientation of SRO. For this reason, even if the (111) orientation is preferentially compared with the (110) orientation, the (100) orientation, or the (001) orientation, a problem occurs when the piezoelectric actuator is continuously operated depending on the degree. According to the study by the present inventors, after driving an electro-mechanical conversion element provided with a lower electrode having a (111) -oriented SRO and a piezoelectric layer made of PZT, how much deterioration occurs compared to the initial displacement. As a result of the investigation, it was confirmed that the state of deterioration changes depending on the (111) orientation degree defined below.
In Patent Document 6, RTA treatment is performed after room temperature film formation for SRO film formation. However, when PZT is formed on SRO, it is difficult to obtain a (111) -oriented film. Furthermore, when the SRO film thickness is 10-20 nm, when used as a piezoelectric actuator in this range, sufficient initial displacement cannot be obtained, and further problems occur when continuously operated.
In Patent Document 7, a ferroelectric film manufactured on an epitaxial film (100) containing SRO as a main component has a (100) orientation. In order to suppress the deterioration of the displacement characteristics when continuously operating as a piezoelectric actuator, (111) is preferable as the orientation of the piezoelectric film, and the (100) oriented material cannot sufficiently suppress the deterioration.
In Patent Document 8, the stability of SRO is improved by substituting part of Ru contained in SRO with Ti. However, as described in Patent Document 8, the crystallinity containing a large amount of RuO _{2 and the} like. Therefore, the SRO film having a low SRO (111) orientation cannot be obtained.
In Patent Document 9, since the titanium film or the titanium oxide film is not provided under the lower electrode, there is a problem in the adhesion between the diaphragm and the lower electrode.
Patent Document 10 has the same problem as Patent Document 5.
In Patent Document 11, a crystal body made of a compound of platinum and titanium oxide is used as a lower electrode, and a titanium oxide film is provided below the lower electrode. The grain boundary of the crystal body is perpendicular to the film surface of the piezoelectric film. Existing. In this case, with platinum alone, it is difficult to suppress the deterioration of the displacement characteristics when the piezoelectric actuator is continuously operated.
In Patent Documents 12 to 16, there is a description of the initial displacement amount of the piezoelectric film, but there is no description of displacement characteristic deterioration when continuously operating. Moreover, there is no description about the state (for example, twin plane) in the film thickness direction of the PZT film.
That is, in an electro-mechanical conversion element in which PZT (lead zirconate titanate) is formed as a piezoelectric film (electro-mechanical conversion film) on the lower electrode, the amount of displacement of the electro-mechanical conversion film improves the ink ejection characteristics. There is a demand for the development of an electro-mechanical conversion element that is sufficiently secured as long as it can be held, and that the deterioration of the displacement amount is sufficiently suppressed even after continuous ejection.
In addition, with respect to Patent Documents 12 to 16, as will be described later, in order to efficiently obtain the amount of displacement, the present inventors can increase the amount of displacement even if the (100) plane is not preferentially oriented in the entire PZT film. It is considered that a part of the twin structure such as the (100) plane can suppress a decrease in displacement during continuous driving durability.
The present invention has been made in view of the above-described prior art, and the amount of displacement of the electromechanical conversion film is sufficiently ensured to maintain good ink ejection characteristics, and the amount of displacement is sufficiently deteriorated even after continuous ejection. An object of the present invention is to provide an electro-mechanical conversion element that is suppressed and can obtain stable ink ejection characteristics.

In the case of the above-mentioned Patent Document 4 (Japanese Patent Laid-Open No. 2007-258389), for example, when the (111) plane is preferentially oriented and the degree of orientation is 95% or more, if the degree of orientation becomes extremely high, the displacement with respect to the electric field strength There is a problem that the amount is saturated in the middle and a sufficient amount of displacement cannot be obtained under a high electric field strength (see FIG. 2). As shown in FIG. 3, the displacement of the entire piezoelectric film (electro-mechanical conversion film) is obtained by (1) increasing the piezoelectric strain due to voltage application and (2) increasing the strain due to domain rotation. It is done.
That is, when lead zirconate titanate (PZT) is used as the electro-mechanical conversion film, for example, if the plane orientation of PZT is completely oriented to PZT (111), the displacement of the electro-mechanical conversion film is caused. The contributing terms are only (1) the effect of increasing the piezoelectric strain, and (2) the effect of increasing the strain by domain rotation is almost eliminated. For this reason, the displacement amount is saturated in the middle, and a problem that the entire displacement amount becomes small occurs.
In order to eliminate the problem due to the saturation of the displacement amount of the entire electro-mechanical conversion film, even if the PZT (111) plane is preferentially oriented, in order to obtain an increase in the displacement amount based on the domain rotation, PZT ( It is considered necessary to have an orientation other than the (111) plane.
As a result of intensive studies, the present inventors have found that the crystal structure constituting the electro-mechanical conversion film of the electro-mechanical conversion element has two or more plane orientations including a preferential plane orientation, and one electrode (upper electrode) It has been found that having a twin structure on a part of the) side suppresses a decrease in displacement during continuous driving, and can efficiently improve the displacement while maintaining durability.
That is, the above-described problem includes a lower electrode formed on a substrate or a base film, an electro-mechanical conversion film formed on the lower electrode, and an upper electrode formed on the electro-mechanical conversion film. An electro-mechanical transducer element
When the electro-mechanical conversion film is measured by X-ray diffraction (XRD) at θ-2θ, the plane orientation preferential to the crystal structure is (l m n) plane [l, m, n is 0 or 1]. When expressed, the crystal structure constituting the electro-mechanical conversion film has a (111) plane that is a plane orientation to be a priority plane and a plane orientation that is a non-priority plane other than the (111) plane,
In the electro-mechanical conversion film, the occupation ratios occupied by the priority surface and the non-priority surface existing on the lower electrode layer side are R _lower (priority surface) and R _lower (non-priority surface), respectively, and the upper electrode layer the priority face and the non-priority face occupies occupancy respectively _on R present on the side (priority face), when the _on R (non-priority face), R _under (priority plane)> _on R (priority face) And R _top (non-priority surface)> R _bottom (non-priority surface)
When the hysteresis loop is measured by applying an electric field strength of ± 150 kV / cm to the electro-mechanical transducer, the initial polarization at 0 kV / cm is Pin (μC / cm ² ), and a voltage of +150 kV / cm is applied. When the polarization at 0 kV / cm when returned to 0 kV / cm is Pr (μC / cm ² ), the polarizability calculated by Pr-Pind is 10 μC / cm ² or less. -Solved by mechanical transducer elements.

  According to the present invention, the displacement amount of the electro-mechanical conversion film is sufficiently ensured to maintain the ink ejection characteristics satisfactorily, and the deterioration of the displacement amount is sufficiently suppressed even when continuously ejected, thereby obtaining stable ink ejection characteristics. An electro-mechanical conversion element that can be provided can be provided.

It is a schematic sectional drawing which shows the structural example of the droplet discharge head provided with the electromechanical conversion element. It is the figure which showed the relationship between the displacement amount of an electromechanical conversion element when using PZT, and the orientation rate of a surface orientation (111) as a parameter. It is explanatory drawing which shows typically that the displacement of the whole electromechanical conversion film is obtained by the distortion by a piezoelectric distortion and domain rotation. It is explanatory drawing which shows typically that a displacement amount improves with the surface orientation (111) by the side of the lower electrode which does not contribute to domain rotation, and the twin structure of the upper electrode side which contributes to domain rotation. It is a schematic sectional drawing which shows the structural example of the electromechanical conversion element which concerns on this invention. It is a schematic sectional drawing which shows another structural example of the electromechanical conversion element which concerns on this invention. The dependence of the SRO film forming temperature (300 ° C., 600 ° C.) on the peak intensity when 2θ = 32 ° is fixed in the θ-2θ measurement and the tilt angle (χ) is shaken is shown. It is a figure which shows the result of having investigated the crystal orientation of the electromechanical conversion film (PZT) produced on SRO formed into a film at 300 degreeC and 600 degreeC by the X ray diffraction method (XRD). It is a figure for demonstrating the half value width (FWHM) of (omega) in the maximum peak value obtained by shaking only an incident angle ((omega)) by the surface orientation (111) of a 1st electrode (Pt). It is a figure which shows typically a structure when PZT after film-forming is measured by XRD. It is a figure which shows the relationship between the peak intensity | strength and tilt angle ((chi)) when PZT produced by controlling film-forming conditions is measured by XRD. It is a figure which shows the relationship between the peak intensity | strength and tilt angle ((chi)) when measuring PZT produced by the conventional method without controlling film-forming conditions by XRD. It is the figure which mapped the occupation state of the crystal structure between the lower electrode side of PZT produced by controlling film-forming conditions and the upper electrode side by the EBSD method. It is the figure which mapped the occupation state of the crystal structure by the EBSD method between the lower electrode side and the upper electrode side of PZT produced by the conventional method without controlling film-forming conditions. It is a figure which shows the relationship between each electric field strength and displacement amount in case the crystal structure of PZT between the lower electrode side and the upper electrode side is FIG.13 and FIG.14. It is a figure which shows typically the occupation state of the crystal structure of PZT between the lower electrode side and upper electrode side shown in FIG. It is a figure which shows typically the structure of a surface orientation (110) surface when PZT is measured by XRD. It is the side view and top view which show the structure (an insulation protective film and an extraction wiring are included) of the electromechanical conversion element which concerns on this invention. It is a schematic diagram which shows the structural example of the polarization processing apparatus used in order to inject an electric charge into the electromechanical conversion element which concerns on this invention, and to perform a polarization process. It is a figure for demonstrating the state before the polarization process of the electromechanical conversion element which concerns on this invention (a), and after the polarization process (b). It is explanatory drawing which shows that the electric charge is accumulate | stored when the cation generated by the discharge of the corona electrode (corona wire) of FIG. 19 flows into a piezoelectric element, and is polarized. It is a figure which shows the typical PE hysteresis curve at the time of evaluating the characteristic of the electromechanical conversion element produced in the Example. FIG. 5 is another schematic cross-sectional view showing a configuration example of a droplet discharge head configured by arranging a plurality of electro-mechanical conversion elements shown in FIG. 1. It is a perspective explanatory view showing an example of a droplet discharge device (inkjet recording device) provided with a droplet discharge head according to the present invention. It is side surface explanatory drawing of the mechanism part of the droplet discharge apparatus (inkjet recording device) shown in FIG.

  As described above, the electro-mechanical conversion element of the present invention includes the lower electrode formed on the substrate or the base film, the electro-mechanical conversion film formed on the lower electrode, and the electro-mechanical conversion film. And the crystal structure constituting the electro-mechanical conversion film has two or more plane orientations including a preferred plane orientation, and the occupation ratio of the preferred plane orientation is lower. It differs along the film thickness direction between the electrode side and the upper electrode side.

Here, the preferential (l m n) plane is preferably a (111) plane. The electro-mechanical conversion film is preferably made of lead zirconate titanate (PZT).
For example, in the case of the configuration of the droplet discharge head as shown in FIG. 1, when the base (film) is deformed due to the distortion of the electromechanical conversion film, the lower electrode with the substrate restraint as shown in FIG. Even if it is made of a material that does not contribute to domain rotation like the (111) surface on the side, the (100), (001) surface and (( 101), having a twin structure like the (011) plane is expected to improve the displacement due to the contribution of domain rotation. In other words, even if the (111) plane is not preferentially oriented in the entire electro-mechanical conversion film (for example, PZT film), a part of the upper electrode side has a twin structure such as the (100) plane. In addition, the displacement amount is improved, and a decrease in displacement amount during continuous driving durability is suppressed.

Hereinafter, the present invention will be described in detail.
A structural example of the electromechanical conversion element of the present invention is shown in a schematic cross-sectional view of FIG.
5 includes a substrate 101, a diaphragm 102, a lower electrode 103, an electromechanical conversion film 104, and an upper electrode 105. Here, with respect to the lower electrode and the upper electrode, it is preferable to provide a conductive layer capable of obtaining a sufficient specific resistance value electrically. As such a conductive layer, for example, the first electrode 203 and the fourth electrode 207 described in another schematic cross-sectional view of FIG. 6 correspond thereto. 6 includes a substrate 201, a diaphragm 202, a first electrode 203, a second electrode 204, an electromechanical conversion film 205, a third electrode 206, and a fourth electrode 207.
Further, in order to suppress a decrease in displacement or the like during continuous driving when the electromechanical conversion element is operated as an actuator, the lower electrode and the upper electrode on the side in contact with the electromechanical conversion film 105 shown in FIG. It is preferable that the oxide electrode layer have As such an oxide electrode layer, for example, the second electrode 204 and the third electrode 206 illustrated in FIG. 6 correspond thereto. Each constituent layer will be described in detail below.

〔substrate〕
As the substrate, it is preferable to use a silicon single crystal substrate, and it is usually preferable to have a thickness of 100 μm to 600 μm. There are three types of plane orientations, (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry. In this configuration, for example, ( A single crystal substrate having a plane orientation of 100) was mainly used. In addition, when a pressure chamber as shown in FIG. 1 is manufactured, a silicon single crystal substrate is processed using etching. In this case, anisotropic etching is generally used as an etching method. Is.
Anisotropic etching utilizes the property that the etching rate differs with respect to the plane orientation of the crystal structure. For example, in anisotropic etching immersed in an alkaline solution such as KOH, the (111) plane has an etching rate of about 1/400 compared to the (100) plane. Therefore, while a structure having an inclination of about 54 ° can be produced in the plane orientation (100), a deep groove can be removed in the plane orientation (110), so that the arrangement density is increased while maintaining rigidity. In this configuration, it is possible to use a single crystal substrate having a (110) plane orientation. However, in this case, SiO ₂ which is a mask material is also etched, so this area is also used with attention.

[Vibration version]
As shown in FIG. 1, the base plays the role of a diaphragm, receives the force generated by the electromechanical conversion film, and the base is deformed and displaced to discharge ink droplets in the pressure chamber. Therefore, it is preferable that the base has a predetermined strength. Examples of the material include Si, SiO ₂ , and Si ₃ N ₄ produced by the CVD method. Furthermore, it is preferable to select a material close to the linear expansion coefficient of the element constituent material, such as a lower electrode and an electromechanical conversion film as shown in FIG. In particular, as an electro-mechanical conversion film, since lead zirconate titanate (PZT) is generally used as a material, as a linear expansion coefficient close to 8 × 10 ⁻⁶ (1 / K), A material having a linear expansion coefficient of 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ (1 / K) is preferable, and a linear expansion coefficient of 7 × 10 ^{−6 to} 9 × 10 ⁻⁶ (1 / K) is further preferable. The material it has is more preferred.
Specific examples of the material include aluminum oxide, zirconium oxide, iridium oxide, ruthenium oxide, tantalum oxide, hafnium oxide, osmium oxide, rhenium oxide, rhodium oxide, palladium oxide, and compounds thereof. It can be produced by a spin coater using a Sol-gel method. The film thickness is preferably from 0.1 to 10 μm, more preferably from 0.5 to 3 μm. If the film thickness is thinner than 0.5 μm, it is difficult to process the pressure chamber as shown in FIG. 1, and if it is thicker than 10 μm, the substrate is difficult to deform and displace, and ink droplet ejection becomes unstable.

[First electrode and fourth electrode]
Both the first electrode and the electrode 4 shown in FIG. 6 are preferably made of metal, and as these metal materials, conventionally known platinum having high heat resistance and low reactivity is used. However, it may not be said that it has a sufficient barrier property against lead, and a platinum group element such as iridium or platinum-rhodium or an alloy film thereof may be used as necessary.
Further, when platinum is used, it is preferable that Ti, TiO ₂ , Ta, Ta ₂ O ₅ , Ta ₃ N _5, etc. are laminated first because of poor adhesion to the base (particularly SiO ₂ ). As a manufacturing method, vacuum film formation such as sputtering or vacuum deposition is generally used. As a film thickness, 0.05-1 micrometer is preferable and 0.1-0.5 micrometer is further more preferable. At this time, when PZT is selected as the electro-mechanical conversion film, the crystallinity thereof preferably has (111) orientation. Therefore, it is preferable to select Pt having a high (111) orientation as the first electrode material.

[Second electrode and third electrode]
As the second electrode and the third electrode, it is preferable to use strontium ruthenate (SrRuO ₃ : SRO) as a constituent material, but other than the left, Sr _x A _(1-x) Ru _y B _{(1- y)} Also mentioned are materials as described in the formula: A = Ba, Ca, B = Co, Ni, x, y = 0 to 0.5.
As a method for forming the second electrode and the third electrode, for example, a sputtering method or the like is used. In this case, although the film quality of the SrRuO ₃ (SRO) thin film varies depending on the sputtering conditions, in particular, the crystal orientation is emphasized, and the SRO film is also (111) oriented following the Pt (111) of the first electrode. The film is preferably formed by heating the substrate at a temperature of 300 ° C. or higher.
For example, under the SRO film formation conditions described in Japanese Patent No. 3249696, thermal oxidation is performed by RTA treatment at a crystallization temperature of 650 ° C. after film formation at room temperature. However, although the SRO film formed in this case is sufficiently crystallized to obtain a sufficient value as the specific resistance as an electrode, (110) tends to be preferentially oriented as the crystal orientation of the film. There is also a problem that the PZT film formed thereon is easily (110) oriented.

For example, with respect to the SRO film formation conditions described in Japanese Patent No. 3249696, it is preferable to perform thermal oxidation at a crystallization temperature (650 ° C.) by RTA treatment (Rapid Thermal Annealing treatment) after film formation at room temperature. In this case, the SRO film is sufficiently crystallized and a sufficient specific resistance value can be obtained as an electrode. However, as the crystal orientation of the film, (110) is likely to be preferentially oriented, and a film is formed thereon. PZT is also preferentially oriented to the (110) orientation.
FIG. 2 shows the relationship between the amount of displacement of the electromechanical conversion element and the electric field strength, using the PZT orientation rate as a parameter when PZT having a plane orientation (111) is used. As shown in FIG. 2, when the degree of orientation of PZT is attempted to be completely aligned to (111), there is a problem that a sufficient amount of displacement cannot be obtained under high electric field strength. It is necessary to adjust the degree of orientation of the film not with perfect (111) but with the degree of orientation including components other than (111).
For example, it is preferable that the second electrode has a perovskite structure, the preferred plane orientation is the (111) plane, and the non-preferred plane orientation is the (110) plane or the (100) plane.

  Regarding the crystallinity of SRO produced on Pt (111), since the lattice constants of Pt and SRO are close to each other, in the normal θ-2θ measurement, the 2θ positions of SRO (111) and Pt (111) are overlapped. Is difficult. For Pt, if the tilt angle is 35 ° with respect to the sample surface and an attempt is made to obtain the diffraction intensity at a position where 2θ is about 32 °, the diffraction lines cancel each other and the diffraction intensity is reduced. can not see. Therefore, it is possible to confirm whether the SRO is preferentially oriented to (111) by inclining the Psi direction by about 35 ° and judging from the peak intensity where 2θ is about 32 °.

For example, FIG. 7 shows the relationship between the peak intensity and the SRO film forming temperature dependence when the tilt angle (χ) is swung with θ 2θ fixed at 2θ = 32 °.
When the SRO film forming temperature is set to 600 ° C., almost no diffraction intensity is seen at χ = 0 ° and 45 °, and the diffraction intensity is seen around χ = 35 °.
From this, it can be confirmed that the SRO is (111) oriented in the film produced under this film forming condition. On the other hand, when the SRO film forming temperature is set to 300 ° C., the diffraction intensity can be slightly confirmed at χ = 0 °. For this reason, SRO (111) is preferentially oriented for the film formed at 300 ° C., but it is composed of SRO (111) and SRO (110) as compared with 600 ° C. film formation. The peak intensity in the vicinity of = 0 ° is SRO (110) _Int, the peak intensity in the vicinity of χ = 35 ° is SRO (111) _Int, the peak intensity in the vicinity of χ = 45 ° is SRO (100) _Int, and SRO ( 111) _Int / (SRO (100) _Int + SRO (110) _Int + SRO (111) _Int) is small.

FIG. 8 shows the results of examining the crystal orientation of the electro-mechanical conversion film (PZT) formed on the SRO formed at 300 ° C. and 600 ° C. by X-ray diffraction (XRD). From this result, it can be seen that the peak intensity other than PZT (111) is generated in the case where the film formation temperature of the SRO film is set to 300 ° C., compared to the film temperature set to 600 ° C.
As shown in FIG. 8, in order to control PZT (111) in a certain range, it is preferable to set SRO (111) _Int to 0.5 or more and 0.99 or less, and 0.7 to 0.85 or less. More preferably it is. If it exceeds this range, a problem such that a sufficient initial displacement cannot be obtained occurs, and if it is less than this range, sufficient characteristics cannot be obtained for displacement degradation after continuous driving.
That is, in the present invention, the second electrode has a perovskite structure, and the plane orientation in which the crystal structure is preferential is the (111) plane, and the non-preferred plane orientation other than the (111) plane is (110). Peak at the position of 2θ = 32 ° when the tilt angle (χ) is swung with respect to the sample surface in the θ-2θ measurement by the X-ray diffraction method (XRD). Strength below
Peak intensity near χ = 0 °: SRO (110) Int,
Peak intensity near χ = 35 °: SRO (111) Int,
Peak intensity near χ = 45 °: SRO (100) Int,
And when
SRO (111) Int / [SRO (100) Int + SRO (110) Int + SRO (111) Int] is preferably 0.5 or more and 0.99 or less.

In addition to the film formation temperature of the SRO film, the degree of orientation of PZT can be adjusted by the quality of the Pt crystal serving as the first electrode. Specifically, 2θ (near 39.7 °) that can obtain the surface orientation (111) of the first electrode when measured by X-ray diffraction (XRD) is fixed, and only the incident angle (ω) is obtained. The same effect can be obtained by setting the FWHM (FWHM) of ω at the maximum peak value of the diffraction peak obtained by shaking to 2.5 ° to 7.0 °. That is, the FWHM (half width) of the rocking curve when Pt (111) is scanned by ω is set to 2.5 ° to 7 °, more preferably 3.0 ° to 4.5 °. The same effect as described for the film temperature can be obtained. When FWHM is larger than 7 °, there is a problem that a sufficient initial displacement amount cannot be obtained. When FWHM is smaller than 2.5 °, sufficient characteristics cannot be obtained for displacement deterioration after continuous driving.
FIG. 9 is an explanatory diagram for explaining the full width at half maximum (FWHM) of ω at the maximum peak value obtained by swinging only the incident angle (ω) in the plane orientation (111) of the first electrode (Pt). As shown in FIG. 9, with respect to the FWHM of Pt (111), the diffraction obtained when only ω is shaken with 2θ fixed in the vicinity of 2θ = 39.7 ° where the Pt (111) plane is obtained. It means the width of a half value from the maximum peak position.

Regarding the composition ratio of Sr and Ru of SRO after film formation, Sr / Ru is preferably 0.82 or more and 1.22 or less. If it is out of this range, the specific resistance increases, and sufficient conductivity as an electrode cannot be obtained.
Furthermore, the film thickness of SRO as the second electrode is preferably 20 nm to 150 nm, and more preferably 30 nm to 50 nm. If the thickness is smaller than this range, sufficient characteristics cannot be obtained with respect to initial displacement and displacement deterioration after continuous driving. If it is thicker than this film thickness range, the withstand voltage of PZT subsequently formed on the SRO becomes very poor and leaks are likely to occur.

Furthermore, in addition to the temperature and film thickness at the time of film formation and the quality of the Pt (111) crystal serving as the first electrode, by controlling the chamber environment at the time of sputter film formation, PZT after film formation becomes X The structure shown in the schematic diagram of FIG. 10 when measured by the line diffraction method (XRD). Then, as shown in FIG. 11, the tilt angle (χ) is ± 25 with respect to the sample surface at the 2θ position (around 21.8 °) where PZT (001) or PZT (100) gives the strongest peak intensity. When tilted in the range of °, it is confirmed that a strong peak intensity is obtained in the vicinity of ± 15 ° compared to the tilt of 0 °.
On the other hand, in the case of the conventional manufacturing method, as shown in FIG. 12, even when the tilt angle (χ) is swung with respect to the sample surface, the strongest peak only at the tilt of 0 ° in the range of the tilt angle (χ) ± 25 °. Strength is obtained.

Furthermore, the crystal structure in the film thickness direction can be confirmed by TEM analysis, etc., but each crystal plane should be analyzed using the EBSD (Electron BackScatter Diffraction Pattern) method, which can easily obtain the mapping in the plane direction. You can also.
FIG. 13 shows a diagram in which the occupied state of the crystal structure between the lower electrode side and the upper electrode side of PZT manufactured by controlling the film forming conditions is mapped by the EBSD method.
As shown in FIG. 13, in addition to the temperature and film thickness during the SRO film formation and the quality of the Pt (111) crystal serving as the first electrode, by controlling the chamber environment during the SRO sputter film formation, The occupation ratio of the plane orientation preferentially along the film thickness direction of PZT which is the electro-mechanical conversion film is different between the lower electrode side and the upper electrode side. That is, PZT (111) grows due to the seed effect of the base on the lower electrode side, but PZT (001) or PZT (100) is inclined by 15 ° with respect to the substrate surface from the middle to the upper electrode side. Things that have grown up are obtained.
On the other hand, FIG. 14 shows a diagram in which the occupied state of the crystal structure between the lower electrode side and the upper electrode side of PZT produced by a conventional method without controlling the film forming conditions is mapped by the EBSD method.
As shown in FIG. 14, in the conventional SRO film forming method, there is only a PZT (111) plane along the thickness direction of PZT between the lower electrode side and the upper electrode side.

FIG. 15 shows the relationship between the electric field strength and the amount of displacement when the crystal structure of PZT between the lower electrode side and the upper electrode side is that shown in FIGS.
As shown in FIG. 15, the amount of displacement is larger when the crystal structure occupation state of PZT is different in the occupation ratio of the plane orientation preferential along the film thickness direction of PZT as shown in FIG.
For this reason, since the substrate restraint is small on the upper electrode side, the crystal can be freely deformed, whereby the crystal structure (PZT) plane orientation (100) or (001) is changed to the substrate on the upper electrode side. It can be considered that the amount of displacement is improved because it can have a twin structure obtained from a plane inclined by 15 ° with respect to the plane and can efficiently receive the contribution of domain rotation.

FIG. 16 schematically shows the occupied state of the crystal structure of PZT between the lower electrode side and the upper electrode side shown in FIG.
In FIG. 16, when the electro-mechanical conversion film is measured at θ-2θ by X-ray diffraction (XRD), the plane orientation preferential to the crystal structure is (l m n) plane [l, m, n is 0 Or 1], the occupying ratio of the (l m n) plane existing on the lower electrode side is R _lower (lmn), and is present on the upper electrode side (l
The occupancy rate of m n) plane is occupied when the _on R (lmn), it is preferable to satisfy the _under R (lmn)> _on R (lmn).
In FIG. 16, when the crystal structure of the electro-mechanical conversion film is measured at θ-2θ by X-ray diffraction (XRD), the plane orientation preferential to the crystal structure is the (lmn) plane [l, m , N is 0 or 1], and the non-preferred plane orientation other than the priority plane is the (l ₂ m ₂ n ₂ ) plane [l ₂ , m ₂ , n ₂ is 0 or 1], the seed The electro-mechanical conversion film existing on the lower electrode side has a number of preferentially oriented (lmn) planes controlled by the layers, and the (lmn) plane of the electro-mechanical conversion film existing on the upper electrode side. It is preferable that the ratio occupied by (l ₂ m ₂ n ₂ ) that can efficiently improve the contribution of domain rotation other than is high.
That is, the occupation ratios of the (lmn) plane and the (l ₂ m ₂ n ₂ ) plane of the crystal structure existing on the lower electrode layer side are respectively R _lower (lmn) and R _lower (l ₂ m ₂ n ₂ ). and then, the (lmn) plane of the crystal structure present in the upper electrode layer side, and _{(l 2} m _{2 n 2)} face occupies occupancy respectively _on R (lmn), _{on R (l 2 m 2 n 2} ) It is preferable that R _below (lmn)> R _above (lmn) and R _above (l ₂ m ₂ n ₂ )> R _below (l ₂ m ₂ n ₂ ) are satisfied.

Further, as the tilt angle (χ) corresponding to the (100) and (001) planes, it is preferable that the tilt angle has a peak intensity in the range of χ = ± 5 to 25 °. FIG. 17 schematically shows the structure of the plane orientation (110) plane when PZT is measured by XRD. FIG. 17 shows an orientation plane of (110) [or (101)]. This plane is equivalent to (001) or (100) inclined by 45 ° and inclined.
For this reason, when the plane orientation (001) or (100) is inclined, if an inclination exceeding 22.5 ° is observed, in this case, the main surface is inclined (110) or (101) Can be considered. In general, when considering only domain distortion (not considering domain rotation), the (001) plane is considered to have the largest amount of distortion, so the main plane is (001) or (100) as much as possible. , I think that it is easier to distort when it is tilted, and the amount of displacement increases.
For example, the plane orientation (l m n) [l, m, n is 0 or 1] which is the priority of the crystal structure when measured at θ-2θ by X-ray diffraction (XRD) is the (111) plane, The non-preferred plane orientation (l ₂ m ₂ n ₂ ) plane [l ₂ , m ₂ , n ₂ is 0 or 1] other than the priority plane may be the (101) or (011) plane.

[Third electrode]
The film thickness when SRO is used as the third electrode is preferably 20 nm to 80 nm, and more preferably 30 nm to 50 nm. If the thickness is less than 20 nm, sufficient characteristics cannot be obtained for the initial displacement and displacement deterioration characteristics. If it exceeds 80 nm, the dielectric strength voltage of PZT is very poor and leaks easily.

[Electro-mechanical conversion membrane]
Examples of the electro-mechanical conversion film include materials composed of complex oxides, but lead zirconate titanate (PZT) was mainly used. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and titanic acid (PbTiO ₃ ), and the characteristics differ depending on the ratio. In general, a composition exhibiting excellent piezoelectric characteristics is obtained when the ratio of PbZrO ₃ and PbTiO ₃ is 53:47, and is expressed as Pb (Zr _0.53 , Ti _0.47 ) O _{3 in} the chemical formula. It is indicated as PZT (53/47).
Examples of composite oxides other than PZT include barium titanate. In this case, it is also possible to prepare a barium titanate precursor solution by dissolving barium alkoxide and a titanium alkoxide compound in a common solvent. is there.
Such a composite oxide is described by the general formula ABO ₃ and corresponds to a composite oxide mainly composed of A = Pb, Ba, Sr; B = Ti, Zr, Sn, Ni, Zn, Mg, Nb. As a concrete description, for _{example, (Pb 1-x, Ba} x) (Zr 1-y, Ti y) O 3, (Pb 1-x, Sr x) (Zr 1-y, Ti y) O ₃ etc. are mentioned. These are cases where Pb at the A site in the general formula ABO ₃ is partially substituted with Ba or Sr. Such substitution is possible with a divalent element, and the effect thereof has an effect of reducing characteristic deterioration due to evaporation of lead during heat treatment.

  As a method for producing the electro-mechanical conversion film, it can be produced by a spin coater using a sputtering method or a Sol-gel method. In that case, since patterning is required, a desired pattern is obtained by photolithography etching or the like.

  When PZT is produced by the Sol-gel method, PZT precursor solution can be produced by using lead acetate, zirconium alkoxide, and titanium alkoxide compound as starting materials and dissolving them in methoxyethanol as a common solvent to obtain a uniform solution. . Since the metal alkoxide compound is easily hydrolyzed by moisture in the atmosphere, an appropriate amount of a stabilizer such as acetylacetone, acetic acid or diethanolamine may be added to the precursor solution as a stabilizer.

  When a PZT film is formed on the entire surface of a substrate or a base film, an electro-mechanical conversion film is formed by forming a coating film by a solution coating method such as spin coating and performing heat treatments such as solvent drying, thermal decomposition, and crystallization. can get. Since the transformation from the coating film to the crystallized film involves volume shrinkage, it is necessary to adjust the precursor concentration so that a film thickness of 100 nm or less can be obtained in one step in order to obtain a crack-free film.

  In the case where the PZT film is manufactured by the ink jet method, a patterned film can be obtained by the same manufacturing flow as that of the second electrode. As for the surface modifying material, although it varies depending on the material of the base (first electrode), the silane compound is mainly selected when the oxide is the base, and the alkanethiol is mainly selected when the metal is the base.

  The film thickness of the electro-mechanical conversion film is preferably 0.5 μm to 5 μm, more preferably 1 μm to 2 μm. If the thickness is less than 0.5 μm, a sufficient displacement cannot be generated, and if it is thicker than 5 μm, many layers are stacked, which is not preferable because the number of steps increases and the process time becomes long.

  FIG. 7 shows the result of examining the crystal orientation by XRD after forming a film of 1 μm by spin coating using a solution in which PZT is produced by the Sol-gel method on the second electrode. As described above, it is suggested that the orientation state of the obtained PZT (111) also changes depending on the orientation state of the SRO.

As the PZT (111) orientation degree, when the following formula (1) is used, the (111) orientation degree is preferably 0.5 or more and 0.99 or less, and more preferably 0.8 or more and 0.9. More preferably, it is as follows. When the degree of orientation exceeds 0.99, there is a problem that a sufficient initial displacement amount cannot be obtained. When the degree of orientation is less than 0.5, sufficient characteristics cannot be obtained with respect to displacement deterioration after continuous driving.
ρ = I (l m n) / ΣI (l m n) (1)
[In the formula (1), ρ represents the average degree of orientation, l, m, and n represent 0 or 1, the denominator represents the sum of the peak intensities, and the numerator represents the peak intensity of an arbitrary orientation. ]
That is, the formula (1) is a calculation formula for calculating the ratio of the respective orientations, that is, the average orientation degree (ρ) when the sum of the peaks of the respective orientations obtained by XRD is 1.

Further, as shown in FIG. 11, the crystal structure of SRO is X-ray diffracted at a position where 2θ corresponding to the non-priority (100) plane or (001) plane of the electro-mechanical conversion film (PZT) is the maximum peak. The peak intensity near the tilt angle (χ = 0 °) when measured by the method (XRD) is Int (χ = 0 °), and the peak intensity near the tilt angle (χ = ± 5 to 20 °) is When Int (χ = ± 5 to 20 °), Int (χ = ± 5 to 20 °) / Int (χ = 0 °) is preferably 0.5 or more and 5.0 or less, and more preferably Is 1.0 or more and 2.5 or less.
When Int (χ = ± 5 to 20 °) / Int (χ = 0 °) is larger than 2.5, there is a problem that sufficient characteristics cannot be obtained with respect to displacement deterioration after continuous driving. If it becomes smaller than this, there arises a problem that a sufficient initial displacement cannot be obtained.

  FIG. 18 shows a configuration (including an insulating protective film and a lead-out wiring) of the electro-mechanical conversion element according to the present invention. In FIG. 18, the first insulating protective film 184 has a contact hole 189, the first and second electrodes 181 (a), (b) and the fifth electrode 185 (a) conduct, The third and fourth electrodes 182 (a) and 182 (b) are electrically connected to the sixth electrode 185 (b). At this time, the second electrode 185 (a) is used as a common electrode and the sixth electrode 185 (b) is used as an individual electrode to form a second insulating protective film 186 that protects the common electrode and the individual electrode. And configured as an electrode PAD. The electrode prepared for the common electrode is referred to as a common electrode PAD 188, and the electrode manufactured for the individual electrode is referred to as an individual electrode PAD 187. In FIG. 18, reference numeral 183 denotes an electro-mechanical conversion film.

The electro-mechanical conversion element (hereinafter sometimes referred to as “piezoelectric element”) manufactured in the above-described configuration is preferably subjected to polarization treatment by injection of electric charges generated by corona discharge. The polarization process can be performed using, for example, a polarization processing apparatus as shown in FIG.
As shown in FIG. 19, the polarization processing apparatus is provided with a corona electrode 191 and a grid electrode 192, and the sample stage 195 for setting the sample has a temperature adjustment function (temperature adjustment function) by a heating means (not shown). It is provided, and polarization treatment can be performed while applying a temperature up to about 350 ° C. Note that a ground 196 is installed on the sample stage provided with the temperature control function, and if this is not added, the polarization process cannot be performed.
The grid electrode 192 is meshed so that when a high voltage is applied to the corona electrode 191, ions, charges, and the like generated by corona discharge are efficiently poured onto the lower sample stage. By adjusting the voltage applied to the corona electrode and the grid electrode by the corona power source 193 and the grid power source 194 and the distance between the sample and each electrode, it is possible to increase or decrease the corona discharge.

Here, the state of polarization processing can be determined from the PE hysteresis loop.
In the PE hysteresis when an electric field strength of ± 150 kV / cm is applied to the polarized electro-mechanical transducer, the maximum polarization Pm value is preferably 35 μC / cm ² or more and 55 μC / cm ² or less.
Further, as shown in FIG. 20, the hysteresis loop is measured by applying an electric field strength of ± 150 kV / cm, and the polarization at the time of initial 0 kV / cm is Pind, 0 kV when returning to 0 kV / cm after applying +150 kV / cm voltage. When the polarization at / cm is Pr, the value of Pr-Pind is defined as the polarizability, and the quality of the polarization state is judged from this polarizability.
Here polarizability Pr-Pind is preferably at 10 [mu] C / cm ² or less, and more preferably still 5 [mu] C / cm ² or less. When the polarizability Pr-Pind exceeds 10 μC / cm ² , sufficient characteristics cannot be obtained for displacement deterioration after continuous driving as a piezoelectric actuator of PZT.

As described above, it is preferable that the electromechanical conversion element is polarized by injection of electric charges generated by corona discharge using a polarization processing apparatus as shown in FIG. For example, as shown in the explanatory diagram of FIG. 21, when corona discharge is performed using a corona wire, positive ions are generated by ionizing molecules in the atmosphere, and the positive ions flow through the PAD portion of the piezoelectric element. Thus, electric charges can be accumulated in the piezoelectric element. In other words, it is considered that the internal potential difference is caused by the charge difference between the upper electrode and the lower electrode and the polarization process is performed.
Here, considering the charge amount Q necessary for the polarization treatment, it is preferable that a charge amount of 1 × 10 ⁻⁸ C or more is accumulated, and it is further preferable that a charge amount of 4 × 10 ⁻⁸ C or more is accumulated. . If the charge amount Q is less than 1 × 10 ⁻⁸ C, the polarization treatment cannot be performed sufficiently, and sufficient characteristics cannot be obtained for displacement deterioration after continuous driving as a PZT piezoelectric actuator.
In order to obtain a preferable polarizability Pr-Pind, it can be achieved by adjusting the corona, grid electrode voltage, sample stage and corona, distance between grid electrodes, and the like as shown in FIG. However, in order to obtain a desired polarizability, it is necessary to generate a high electric field with respect to the electromechanical conversion film.

Details of the configuration of the electromechanical conversion element including the insulating protective film and the lead wiring shown in FIG. 18 will be described below.
[First insulating protective film]
The first insulating protective film is made of a dense inorganic material because it is necessary to select a material that prevents moisture in the atmosphere from passing through while preventing damage to the electromechanical conversion element in the film forming / etching process. There is a need. In the case of using an organic material, it is not suitable as the first insulating protective film because it is necessary to increase the film thickness in order to ensure sufficient protective performance. When the first insulating protective film is thickened, the vibration displacement of the diaphragm is remarkably hindered, resulting in a droplet discharge head having a low droplet discharge performance.

  In order to obtain a high protection performance with a thin film as the first insulating protective film, it is preferable to use a film of oxide, nitride, carbide, etc., but the electrode material, electro-mechanical conversion film, which is the base of the insulating protective film It is necessary to select a material having high adhesion to the piezoelectric material, diaphragm material, and the like that form the film. In addition, it is necessary to select a film forming method that does not damage the piezoelectric element. That is, a plasma CVD method in which a reactive gas is turned into plasma and deposited on a substrate, or a sputtering method in which a film is formed by causing a plasma to collide with a target material and flying away is not preferable. Examples of preferable film forming methods include vapor deposition methods and ALD (Atomic Layer Deposition) methods, but ALD methods with wide choices of usable materials are preferable.

As a preferable material for the first insulating protective film, an oxide film used for a ceramic material such as Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , and TiO ₂ can be given as an example. In particular, the ALD method is used to produce a thin film with a very high film density and to suppress damage during the process.

  The thickness of the insulating protective film needs to be thin enough to ensure the protection performance of the electromechanical conversion element, and at the same time, it needs to be as thin as possible so as not to disturb the displacement of the diaphragm. The film thickness of the preferable first insulating protective film is in the range of 20 nm to 100 nm. If it is thicker than 100 nm, the displacement of the diaphragm is reduced, so that a droplet discharge head with low discharge efficiency is obtained. On the other hand, when the thickness is less than 20 nm, the function of the piezoelectric element as a protective layer is insufficient, so that the performance of the piezoelectric element is deteriorated as described above.

A configuration in which the first insulating protective film has two layers is also conceivable. In this case, in order to increase the thickness of the second insulating protective film, a configuration in which the second insulating protective film is opened in the vicinity of the second electrode so as not to significantly impede the vibration displacement of the diaphragm can be cited.
At this time, as the second insulating protective film, any oxide, nitride, carbide, or a composite compound thereof can be used, but SiO ₂ generally used in semiconductor devices can be used.
Arbitrary methods can be used to form the second insulating protective film, and examples include CVD and sputtering, and isotropic deposition can be performed considering the step coverage of the pattern forming part such as the electrode forming part. It is preferable to use a CVD method. The thickness of the second insulating protective film needs to be a thickness that does not cause dielectric breakdown by the voltage applied to the lower electrode and the individual electrode wiring. That is, it is necessary to set the electric field strength applied to the insulating protective film within a range not causing dielectric breakdown. Further, considering the surface property of the base of the second insulating protective film, pinholes, etc., the film thickness is required to be 200 nm or more, and more preferably 500 nm or more.

[Fifth electrode, sixth electrode]
The fifth electrode and the sixth electrode are each preferably a metal electrode material made of any one of an Ag alloy, Cu, Al, Au, Pt, and Ir. As a method for manufacturing the fifth electrode and the sixth electrode, a metal film is manufactured using a sputtering method, a spin coating method, or the like, and then a desired electrode pattern is obtained by photolithography etching or the like.
As a film thickness of each electrode, 0.1-20 micrometers is preferable and 0.2-10 micrometers is more preferable. If the film thickness is less than 0.1 μm, the resistance increases and it becomes impossible to pass a sufficient current through the electrode, and the discharge of the droplet discharge head becomes unstable. If the film thickness is more than 20 μm, the process time is long. There is a problem of becoming.
Further, the contact resistance at the contact hole portion (10 μm × 10 μm) as the common electrode and the individual electrode is preferably 10Ω or less as the common electrode, 1Ω or less as the individual electrode, and more preferably 5Ω or less as the common electrode. The electrode is 0.5Ω or less. If the contact resistance exceeds 10Ω as a common electrode and exceeds 1Ω as an individual electrode, a sufficient current cannot be supplied, and a problem occurs when ink is ejected from the droplet ejection head.

[Second insulating protective film]
The function as the second insulating protective film is a passivation layer having the function of a protective layer for individual electrode wiring and common electrode wiring. As shown in FIG. 18, the second insulating protective film covers the individual electrode and the common electrode except for the individual electrode lead portion and the common electrode lead portion (not shown). This makes it possible to use inexpensive Al or an alloy material mainly composed of Al as the electrode material. As a result, a low-cost and highly reliable ink jet head can be obtained.
As the material of the second insulating protective film, any inorganic material or organic material can be used, but it is necessary to use a material with low moisture permeability. Examples of the inorganic material include oxides, nitrides, and carbides, and examples of the organic material include polyimide, acrylic resin, and urethane resin. However, in the case of an organic material, it is necessary to form a thick film, which is not suitable for patterning described later. Therefore, it is preferable to use an inorganic material that can exhibit a wiring protection function with a thin film. In particular, it is preferable to use Si ₃ N ₄ on the Al wiring because it is a proven technology for semiconductor devices.

  The thickness of the second insulating protective film is preferably 200 nm or more, more preferably 500 nm or more. When the film thickness is small, a sufficient passivation function cannot be exhibited, so that disconnection due to corrosion of the wiring material occurs, and stable ink discharge from the droplet discharge head cannot be performed, and the reliability of the ink jet is lowered.

  Further, a structure having openings on the electromechanical conversion element and the surrounding diaphragm is preferable. This is the same reason that the individual liquid chamber region of the first insulating protective film is thinned. As a result, a highly efficient and highly reliable droplet discharge head can be obtained.

Since the electromechanical conversion element is protected by the first insulating protective film and the second insulating protective film, photolithography and dry etching can be used to form the opening. In addition, the area of the PAD part is preferably 50 × 50 μm ² or more, and more preferably 100 × 300 μm ² or more. If the value is less than this value, sufficient polarization processing cannot be performed, and there arises a problem that sufficient characteristics cannot be obtained for displacement deterioration after continuous driving.

The droplet discharge head of the present invention includes a nozzle that discharges a droplet, a pressurization chamber that communicates with the nozzle, and a discharge drive unit that pressurizes the liquid in the pressurization chamber. A part of the wall of the pressure chamber is constituted by a diaphragm, and the electro-mechanical conversion element of the present invention is arranged on the diaphragm.
If the droplet discharge head is configured using the electromechanical conversion element of the present invention, the ink droplet discharge characteristics can be maintained with the same driving force as that of the ceramic sintered body, and stable ink droplet discharge characteristics can be obtained even when continuously discharged. Can be maintained.

In addition, by providing the droplet discharge head of the present invention, a droplet discharge device can be configured.
FIG. 23 shows a configuration in which a plurality of droplet discharge head configurations shown in FIG. 1 are arranged.
According to the present invention, an electro-mechanical conversion element having performance equivalent to that of bulk ceramics can be formed, and then etching is removed from the back surface for forming a pressure chamber, and a droplet is obtained by joining a nozzle plate having nozzle holes. A discharge head is formed. In the figure, descriptions of liquid supply means, flow paths, and fluid resistance are omitted. 23, reference numeral 901 is a pressure chamber, 902 is a nozzle, 903 is a nozzle plate, 904 is a pressure chamber substrate (Si substrate), 905 is a vibration plate, 906 is an adhesion layer, and 907 is an electro-mechanical conversion element.
If the droplet discharge head of the present invention is used, the discharge stability, durability, and image quality are good, so that the droplet discharge head can be applied to printers, MFPs and other droplet discharge devices used in offices and personal computers.

  An example of a droplet discharge apparatus equipped with the droplet discharge head of the present invention will be described with reference to FIGS. FIG. 24 is a perspective view of the recording apparatus, and FIG. 25 is a side view of the mechanism of the recording apparatus.

  The droplet discharge device shown in FIGS. 24 and 25 (sometimes referred to as an “inkjet recording device”) includes a carriage 93 that can move in the main scanning direction inside the recording apparatus main body 81, and a book mounted on the carriage 93. A droplet discharge head 94 embodying the invention, a printing mechanism portion 82 including an ink cartridge 95 for supplying ink to the droplet discharge head, and the like are housed. A paper feed cassette (or a paper feed tray) 84 on which sheets of paper 83 can be stacked can be removably mounted, and a manual feed tray 85 for manually feeding the paper 83 is opened. The paper 83 fed from the paper feed cassette 84 or the manual feed tray 85 is taken in, and a required image is recorded by the printing mechanism unit 82 and then mounted on the rear side. To discharge the discharge tray 86.

  The printing mechanism 82 holds a carriage 93 slidably in the main scanning direction by a main guide rod 91 and a sub guide rod 92 which are guide members horizontally mounted on left and right side plates (not shown). The droplet discharge head 94 of the present invention that discharges ink droplets of each color (Y), cyan (C), magenta (M), and black (Bk) crosses a plurality of ink discharge ports (nozzles) with the main scanning direction. The ink droplets are mounted with the ink droplet discharge direction facing downward. In addition, each ink cartridge 95 for supplying ink of each color to the droplet discharge head 94 is replaceably mounted on the carriage 93.

  The ink cartridge 95 has an air port that communicates with the atmosphere upward, a supply port that supplies ink to the droplet discharge head 94 below, and a porous body filled with ink inside. The ink supplied to the droplet discharge head 94 is maintained at a slight negative pressure by the capillary force of the body. Further, although the droplet discharge heads 94 for the respective colors are used here as the recording heads, a single droplet discharge head having nozzles for discharging the ink droplets of the respective colors may be used.

  Here, the carriage 93 is slidably fitted to the main guide rod 91 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 92 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 93 in the main scanning direction, a timing belt 100 is stretched between a driving pulley 98 and a driven pulley 99 that are rotationally driven by a main scanning motor 97, and the timing belt 100 is moved to the carriage 93. The carriage 93 is driven to reciprocate by forward and reverse rotation of the main scanning motor 97.

  On the other hand, in order to convey the paper 83 set in the paper feed cassette 84 to the lower side of the droplet discharge head 94, the paper feed roller 101 and the friction pad 102 for separating and feeding the paper 83 from the paper feed cassette 84, and the paper 83 A guide member 103 that guides the sheet 83, a conveyance roller 104 that conveys the fed sheet 83 in a reversed manner, a conveyance roller 105 that is pressed against the circumferential surface of the conveyance roller 104, and a feed angle of the sheet 83 from the conveyance roller 104. A leading end roller 106 is provided. The transport roller 104 is rotationally driven by a sub-scanning motor 107 through a gear train.

  A printing receiving member 109 is provided as a sheet guide member for guiding the sheet 83 fed from the conveying roller 104 below the droplet discharge head 94 in accordance with the movement range of the carriage 93 in the main scanning direction. . A conveyance roller 111 and a spur 112 that are rotationally driven to send the paper 83 in the paper discharge direction are provided on the downstream side of the printing receiving member 109 in the paper conveyance direction, and the paper 83 is further delivered to the paper discharge tray 86. A roller 113 and a spur 114, and guide members 115 and 116 that form a paper discharge path are disposed.

  During recording, the droplet discharge head 94 is driven according to the image signal while moving the carriage 93, thereby ejecting ink onto the stopped paper 83 to record one line, and transporting the paper 83 by a predetermined amount. After that, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 83 has reached the recording area, the recording operation is terminated and the paper 83 is discharged.

  Further, a recovery device 117 for recovering the ejection failure of the droplet ejection head 94 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 93. The recovery device 117 includes a cap unit, a suction unit, and a cleaning unit. While waiting for printing, the carriage 93 is moved to the recovery device 117 side and the droplet discharge head 94 is capped by the capping unit, and the discharge port portion is kept in a wet state to prevent discharge failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.

  When ejection failure occurs, the capping means seals the ejection port (nozzle) of the droplet ejection head 94, sucks out bubbles and the like from the ejection port with the suction means through the tube, and adheres to the ejection port surface. The dust and the like are removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

Thus, in the droplet discharge device of the present invention, since the droplet discharge head manufactured using the electro-mechanical conversion element of the present invention is mounted, there is no ink droplet discharge failure due to vibration plate drive failure, Stable ink droplet ejection characteristics can be obtained, and image quality can be improved.
Examples of the present invention will be described below.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples at all.

<Example 1>
A thermal oxide film (film thickness: 1 micron) is formed on a 6-inch silicon wafer, and a titanium film (film thickness: 30 nm) is formed thereon by a sputtering apparatus at a film formation temperature of 350 ° C., and then 750 ° C. by an RTA method. Was thermally oxidized to form an adhesion film. Subsequently, a first electrode made of metal and a second electrode made of oxide were sequentially formed on the adhesion film as lower electrodes. That is, a platinum film was formed with a sputtering apparatus at a film formation temperature of 550 ° C. to form a first electrode made of a metal film with a film thickness of 100 nm. A strontium ruthenate (SrRuO ₃ : abbreviated as “SRO”) film was formed on the first electrode by a sputtering apparatus to form a second electrode made of an oxide film with a thickness of 50 nm. The substrate heating temperature during the SRO sputter deposition was 450 ° C., and post-annealing (550 ° C.) after the deposition was performed using an RTA (Rapid Thermal Annealing) treatment method (rapid heat treatment). As the sputtering apparatus, film formation was carried out using an apparatus provided with a plurality of targets for one chamber.
Next, a solution adjusted to Pb: Zr: Ti = 115: 53: 47 was prepared as a precursor coating solution for an electro-mechanical conversion film (lead zirconate titanate: PZT).
For the synthesis of a specific precursor coating solution, lead acetate trihydrate, isopropoxide titanium and isopropoxide zirconium were used as starting materials. Crystal water of lead acetate was dissolved in methoxyethanol and then dehydrated. The lead amount is excessive with respect to the stoichiometric composition. This is to prevent crystallinity deterioration due to so-called lead loss during heat treatment. Isopropoxide titanium and isopropoxide zirconium were dissolved in methoxyethanol, the alcohol exchange reaction and the esterification reaction were advanced, and the PZT precursor solution was synthesized by mixing with the methoxyethanol solution in which the lead acetate was dissolved. The PZT concentration was 0.5 mol / l.
Using the synthesized PZT precursor solution, a film was formed by spin coating, and a PZT film thickness of about 2 μm was obtained by a total of 24 film forming steps. That is, after film formation of one or two layers, the temperature is raised to 120 ° C. to 500 ° C. and pyrolyzed, and after the third layer pyrolysis treatment, crystallization heat treatment (temperature 750 ° C.) is RTA (rapid heat treatment). The process performed in step (film thickness is 240 nm) was performed a total of 8 times (24 layers) to obtain a PZT film thickness of about 2 μm.

Next, as the upper electrode, a third electrode made of an oxide and a fourth electrode made of a metal were sequentially formed. On the PZT film, a strontium ruthenate (SRO) film (film thickness: 40 nm) was formed by a sputtering apparatus to form a third electrode made of an oxide film. The film forming temperature was 550 ° C. Next, a platinum film (film thickness: 125 nm) was formed on the third electrode by a sputtering apparatus at a film formation temperature of 550 ° C. to form a fourth electrode made of a metal film.
Thereafter, a photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. is formed on the fourth electrode surface by spin coating, a resist pattern is formed by ordinary photolithography, and then a predetermined pattern is formed using an ICP etching apparatus (manufactured by Samco). An electrode pattern was prepared.
Next, as the first insulating protective film, an Al ₂ O ₃ film was formed to a thickness of 50 nm using an ALD (Atomic Layer Deposition) method. TMA (Sigma Aldrich) was used for the raw material Al, and O ₃ generated by an ozone generator was used for oxygen (O). Thereafter, contact hole portions were formed by etching. Thereafter, Al was sputtered as the fifth and sixth electrodes and patterned by etching. Further, Si ₃ N ₄ was deposited to a thickness of 500 nm by plasma CVD as the second insulating film, and an electro-mechanical conversion element was produced.

  The produced electro-mechanical conversion element was subjected to polarization treatment by corona charging treatment using a polarization treatment apparatus. For the corona charging treatment, a tungsten wire of φ50 μm is used. The polarization treatment conditions were a treatment temperature of 80 ° C., a corona voltage of 9 kV, a grid voltage of 2.5 kV, a treatment time of 30 s, a corona electrode-grid electrode distance of 4 mm, and a grid electrode-stage distance of 4 mm. Further, the common electrode and the individual electrode PAD for connecting to the fifth and sixth electrodes were formed, and the distance between the individual electrodes PAD was set to 80 μm.

<Example 2>
As the adhesion film, a titanium film is formed at a film formation temperature of 400 ° C. by a sputtering apparatus with a film thickness of 20 nm, and as the first electrode, a platinum film is formed at a film formation temperature of 200 ° C. by a sputtering apparatus, and a second film is formed. An electro-mechanical transducer was prepared in the same manner as in Example 1 except that an SRO film was formed by a sputtering apparatus to a film thickness of 20 nm.

<Example 3>
As the adhesion film, a titanium film is formed by a sputtering apparatus at a film formation temperature of 250 ° C., and as the second electrode, an SRO film is formed by a sputtering apparatus, and the substrate heating temperature during the sputtering film formation is 550 ° C. An electromechanical conversion element was produced in the same manner as in Example 1 except that the post-annealing treatment was omitted and the film thickness was 150 nm.

<Example 4>
As the adhesion film, a titanium film is formed at a film formation temperature of 300 ° C. by a sputtering apparatus with a film thickness of 50 nm, and as the second electrode, an SRO film is formed by a sputtering apparatus, and the substrate heating temperature during the sputtering film formation Was made at 300 ° C., and post-annealing was performed at 550 ° C. to obtain a film thickness of 60 nm.

<Example 5>
Example 1 except that a platinum film was formed as a first electrode by a sputtering apparatus at a film formation temperature of 300 ° C., and an SRO film was formed as a second electrode by a sputtering apparatus to a film thickness of 60 nm. As in Example 1, an electromechanical conversion element was produced.

<Comparative Example 1>
As the adhesion film, a titanium film is formed at a film formation temperature of 200 ° C. with a sputtering apparatus with a film thickness of 50 nm, and as the second electrode, an SRO film is formed with a sputtering apparatus, and the substrate heating temperature during the sputtering film formation Was made at 600 ° C. and the post-annealing treatment was omitted to obtain a film thickness of 180 nm.

<Comparative example 2>
As the adhesion film, a titanium film is formed at a film formation temperature of 450 ° C. by a sputtering apparatus with a film thickness of 15 nm, and as the first electrode, a platinum film is formed at a film formation temperature of 150 ° C., and as the second electrode, Electro-mechanical conversion element as in Example 1 except that the SRO film is formed by a sputtering apparatus, the substrate heating temperature during sputtering film formation is room temperature, and the post-annealing process is performed at 550 ° C. to a film thickness of 10 nm. Was made.

The electromechanical transducers produced in Examples 1 to 5 and Comparative Examples 1 to 2 were evaluated for crystallinity by X-ray diffraction (XRD) immediately after film formation or RTA treatment in the process. It was.
In addition, EBSD analysis (evaluation of the occupation state of the crystal structure between the lower electrode side and the upper electrode side was evaluated by the EBSD method) was performed on the devices manufactured in Examples 1 to 5 and Comparative Examples 1 and 2 this time.
Regarding Examples 1 to 5, as shown in FIG. 13, the (111) plane is seen on the second electrode film side, and the (100) plane, (001) plane, or on the third electrode film side. It was confirmed that the (101) plane, the (011) plane, the (100) plane, and the (001) plane tilted by 15 ° were obtained as orientations.
On the other hand, regarding Comparative Examples 1 and 2, as shown in FIG. 14, the PZT (111) plane, the PZT (001) plane, or the (100) plane randomly exist in the plane on the lower electrode side. The crystal structure has only a single plane for each direction.

About the electromechanical conversion element of Examples 1-5 and Comparative Examples 1-2, the FWHM of the first electrode (Pt), the film thickness of the second electrode (SOR), and the (orientation) of the second electrode (SOR) Degree), orientation degree of the preferred plane orientation as the whole electro-mechanical conversion film (PZT)), Int (χ = ± 5 to 20 °) / Int (χ = 0 °), maximum polarization Pm value, polarizability The results of evaluating (Pr-Pind) are summarized in Table 1 below.
The FWHM fixes 2θ (near 39.7 °), which is the plane orientation (111) when the first electrode is measured by X-ray diffraction (XRD), and swings only the incident angle (ω). The full width at half maximum of ω at the maximum peak value obtained by
The above Int (χ = ± 5 to 20 °) / Int (χ = 0 °) is an X-ray diffraction at a position where 2θ corresponding to the plane orientation (100) or (001) of the electromechanical conversion film is the maximum peak. The peak intensity near the tilt angle (χ = 0 °) when measured by the method (XRD) is Int (χ = 0 °), and the peak intensity near the tilt angle (χ = ± 5 to 20 °) is It is determined as Int (χ = ± 5 to 20 °).
The maximum polarization Pm value is the value of maximum polarization in the PE hysteresis measurement (electric field strength: ± 150 kV / cm) of the electromechanical conversion element subjected to the polarization treatment.
The polarizability (Pr-Pind) is the initial polarization at 0 kV / cm when a hysteresis loop is measured by applying an electric field strength of ± 150 kV / cm to a polarized electro-mechanical transducer. / cm ² ), and the polarization at 0 kV / cm when the voltage is returned to 0 kV / cm after applying a voltage of +150 kV / cm is obtained as Pr (μC / cm ² ).
Electrical characteristics and electro-mechanical conversion ability (piezoelectric constant: d31) were evaluated using the electromechanical conversion elements prepared in Examples 1 to 5 and Comparative Examples 1 and 2.
A typical PE hysteresis curve is shown in FIG. The electromechanical conversion ability was calculated from the amount of deformation caused by electric field application (150 kV / cm) measured with a laser Doppler vibrometer and adjusted by simulation. After evaluating the initial characteristics, durability (characteristics immediately after applying the applied voltage 10 to ¹⁰ times) was evaluated. These detailed results are summarized in Table 1.

About Examples 1-5, it had the characteristic equivalent to a general ceramic sintered compact also about the initial characteristic and the result after a durability test (piezoelectric constant is about -130 to -160 pm / V).
On the other hand, Comparative Example 1 is slightly inferior to the general ceramic sintered body in terms of initial characteristics. In yet characteristic after 10 ¹⁰ times (immediately after the addition of 10 ¹⁰ times repeatedly applied voltage) as compared with Examples 1-5, Comparative Example 2's has deteriorated significantly in the piezoelectric constant has been confirmed.

  A droplet discharge head shown in FIG. 23 was manufactured using the electro-mechanical conversion element manufactured in Examples 1 to 5, and ink discharge was evaluated. That is, when the applied state of -10 to -30V was applied with a simple Push waveform using ink whose viscosity was adjusted to 5 cp, it was confirmed that all of the nozzle holes could be discharged. did.

In other words, the electro-mechanical conversion element of the present invention has a sufficient amount of displacement of the electro-mechanical conversion film as long as it can maintain the ink ejection characteristics satisfactorily. Ink discharge characteristics can be obtained, and characteristics (piezoelectric constant) equivalent to those of the ceramic sintered body are maintained.
If a droplet discharge head is configured using such an electro-mechanical conversion element, it has excellent discharge stability and durability, so it can be applied to printers used in offices, personal printers, MFPs, and other droplet discharge devices. Application to three-dimensional molding technology is also possible.

(Figure 1)
101 Pressure chamber 102 Nozzle 103 Nozzle plate 104 Pressure chamber substrate (Si substrate)
105 Base 106 Lower electrode 107 Electro-mechanical conversion film 108 Upper electrode 109 Electro-mechanical conversion element (FIG. 5)
101 Substrate 102 Vibrating plate 103 Lower electrode 104 Electric-mechanical conversion film 105 Upper electrode (FIG. 6)
201 Substrate 202 Vibrating plate 203 1st electrode 204 2nd electrode 205 Electromechanical-mechanical conversion film 206 3rd electrode 207 4th electrode (FIG. 18)
181 (a), (b) First electrode, second electrode 182 (a), (b) Third electrode, fourth electrode 183 Electro-mechanical conversion film 184 First insulating protective film 185 (a ), (B) 5th electrode, 6th electrode 186 2nd insulation protective film 187 Individual electrode PAD
188 Common electrode PAD
189 Contact hole 183 Electro-mechanical conversion film 184 First insulating protective film (FIG. 19)
191 Corona electrode 192 Grid electrode 193 Corona power supply 194 Grid power supply 195 Sample stage 196 Ground (FIG. 23)
901 Pressure chamber 902 Nozzle 903 Nozzle plate 904 Pressure chamber substrate (Si substrate)
905 Vibration plate 906 Adhesion layer 907 Electro-mechanical conversion element (FIGS. 24 and 25)
81 Recording Device Body 82 Printing Mechanism Unit 83 Paper 84 Paper Feed Cassette 85 Tray 86 Paper Discharge Tray 91 Main Guide Rod 92 Subordinate Guide Rod 93 Carriage 94 Head 95 Ink Cartridge 97 Main Scanning Motor 98 Drive Pulley 99 Driven Pulley 100 Timing Belt 101 Feed Paper roller 102 Friction pad 103 Guide member 104 Transport roller 105 Transport roller 106 Front roller 107 Sub-scanning motor 109 Printing receiving member 111 Transport roller 112 Spur 113 Discharge roller 114 Spur 115 Guide member 116 Guide member 117 Recovery device

JP 2004-186646 A JP 2004-262253 A JP 2003-218325 A JP 2007-258389 A Japanese Patent No. 4099818 Japanese Patent No. 3249696 Japanese Patent No. 3472877 Japanese Patent No. 3784401 JP 2003-282987 A Japanese Patent No. 3817729 Japanese Patent No. 4572346 JP 2008-24532 A JP 2007-96248 A Japanese Patent No. 4717344 Japanese Patent No. 5127268 Japanese Patent No. 5041765 JP 2013-065697 A

Claims (16)

A lower electrode formed on a substrate or a base film;
An electro-mechanical conversion film formed on the lower electrode;
Electrical - electrical to have a upper electrode formed on the transducer layer - a transducer,
When the electro-mechanical conversion film is measured by X-ray diffraction (XRD) at θ-2θ, the plane orientation preferential to the crystal structure is (l m n) plane [l, m, n is 0 or 1]. When expressed, the crystal structure constituting the electro-mechanical conversion film has a (111) plane that is a plane orientation to be a priority plane and a plane orientation that is a non-priority plane other than the (111) plane,
In the electro-mechanical conversion film, the occupation ratios occupied by the priority surface and the non-priority surface existing on the lower electrode layer side are R _lower (priority surface) and R _lower (non-priority surface), respectively, and the upper electrode layer the priority face and the non-priority face occupies occupancy respectively _on R present on the side (priority face), when the _on R (non-priority face), R _under (priority plane)> _on R (priority face) And R _top (non-priority surface)> R _bottom (non-priority surface)
When the hysteresis loop is measured by applying an electric field strength of ± 150 kV / cm to the electro-mechanical transducer, the initial polarization at 0 kV / cm is Pin (μC / cm ² ), and a voltage of +150 kV / cm is applied. When the polarization at 0 kV / cm when returned to 0 kV / cm is Pr (μC / cm ² ), the polarizability calculated by Pr-Pind is 10 μC / cm ² or less. A mechanical transducer. 2. The electromechanical transducer according to claim 1, wherein the non-priority plane is a (100) plane or a (001) plane. 3. The electromechanical transducer according to claim 2 , wherein the (100) plane or the (001) plane is inclined within a range of ± 5 ° to 25 ° with respect to the substrate surface. The (111) plane of electricity according to any one of claims 1 to 3 mean degree of orientation is calculated by the following equation (1) is characterized in that 0.50 to 0.99 - transducer .
ρ = I (l m n) / ΣI (l m n) (1)
[In the formula (1), ρ represents the average degree of orientation, l, m, and n represent 0 or 1, the denominator represents the sum of the peak intensities, and the numerator represents the peak intensity of an arbitrary orientation. ] Near the tilt angle (χ = 0 °) when measured by X-ray diffraction (XRD) at the position where 2θ corresponding to the plane orientation (100) or (001) of the electro-mechanical conversion film is the maximum peak. When the peak intensity of Int (χ = 0 °) and the peak intensity in the vicinity of the tilt angle (χ = ± 5 to 20 °) is Int (χ = ± 5 to 20 °),
Int (χ = ± 5~20 °) / Int electrical of claim 2 or 3 (χ = 0 °) is characterized in that 0.5 to 5.0 - mechanical conversion element. The electro-mechanical conversion element according to any one of claims 1 to 5 , wherein the electro-mechanical conversion film is made of lead zirconate titanate (PZT). The said lower electrode is formed from the 1st electrode consisting of a metal, and the 2nd electrode consisting of the oxide provided on this 1st electrode, The any one of Claim 1 thru | or 6 characterized by the above-mentioned. An electro-mechanical conversion element according to claim 1. 8. The electricity according to claim 7, wherein the upper electrode is formed of a third electrode made of an oxide and a fourth electrode made of a metal provided on the third electrode. A mechanical transducer. Claim 8, wherein the first electrode is made of platinum (Pt) group element having a plane orientation (111), said second electrode and the third electrode is characterized by comprising a strontium ruthenate (SRO) The electromechanical conversion element described in 1. The second electrode has a perovskite structure, the preferential plane orientation is the (111) plane, and the non-preferred plane orientation is the (110) plane or the (100) plane,
The second electrode is measured by X-ray diffractometry (XRD) at θ-2θ, and each peak intensity at a position of 2θ = 32 ° when the tilt angle (χ) with respect to the sample surface is used as a parameter is as follows:
Peak intensity near χ = 0 °: SRO (110) Int,
Peak intensity near χ = 35 °: SRO (111) Int,
Peak intensity near χ = 45 °: SRO (100) Int,
When expressed as
SRO (111) Int / [SRO (100) Int + SRO (110) Int + SRO (111) Int] is according to any one of claims 7 to 9, characterized in that 0.5 to 0.99 electro - Mechanical conversion element. Electrical according to any one of claims 7 to 10, wherein the thickness of the second electrode is 20nm or more 150nm or less - mechanical conversion element. When the first electrode is measured by X-ray diffraction (XRD), 2θ (near 39.7 °) which is the plane orientation (111) is fixed and only the incident angle (ω) is shaken. The electromechanical conversion element according to any one of claims 7 to 11 , wherein a half width (FWHM) of ω at the maximum peak value is 2.5 ° or more and 7.0 ° or less. The electro - mechanical conversion element, an electric according to any one of claims 1 to 12, characterized in that is polarized by the injection of electric charges generated by corona discharge - mechanical conversion element. The maximum polarization Pm value is 35 μC / cm ² or more and 55 μC / cm ² or less in PE hysteresis when an electric field strength of ± 150 kV / cm is applied to the polarized electro-mechanical transducer. The electromechanical conversion element according to claim 13 . A nozzle for discharging droplets, a pressurizing chamber that communicates with the nozzle, and a discharge driving unit that pressurizes the liquid in the pressurizing chamber, and vibrates a part of the wall of the pressurizing chamber as the discharge driving unit. and a plate, an electric according to any one of claims 1 to 14 in the diaphragm on - droplet discharge head is characterized in that a mechanical conversion element. A droplet discharge apparatus comprising the droplet discharge head according to claim 15 .