JP5998537B2 - Electro-mechanical conversion element, droplet discharge head, and droplet discharge apparatus - Google Patents

Description

  The present invention relates to an electro-mechanical conversion element, a droplet discharge head, and a droplet discharge device.

  In recent years, electromechanical transducers using piezoelectric ceramics have been used in various fields.

  For example, it is used in a droplet discharge head of an ink jet recording apparatus used as an image recording apparatus or an image forming apparatus such as a printer, a facsimile machine, and a copying apparatus.

  The liquid droplet ejection head includes a nozzle that ejects liquid droplets and a pressure chamber (an ink channel, a pressure liquid chamber, a pressure chamber, a discharge chamber, a liquid chamber, etc.) that contains ink and the like that communicates with the nozzle. Also, it is composed of a piezoelectric element or the like as a drive source that pressurizes the ink in the pressurizing chamber, pressurizes the ink in the pressurizing chamber by the piezoelectric element, and ejects ink droplets from the nozzles.

  As piezoelectric actuators used as drive sources, film structures such as semiconductor devices and electronic devices are known. A piezoelectric vibration actuator that uses a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of the piezoelectric element when the ink in the pressurizing chamber is pressurized by the piezoelectric element that is an electro-mechanical conversion element, and a piezoelectric actuator that operates in the flexural vibration mode. There are two types of products that use the.

  For example, in the case of using a flexural vibration mode piezoelectric actuator, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric material layer is formed into a shape corresponding to the pressure generating chamber by lithography. A known piezoelectric element is formed so as to be separated into each pressure generating chamber.

  In such a piezoelectric actuator, when the vector component of the spontaneous polarization axis of the piezoelectric film matches 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 piezoelectric 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 relating to crystal orientation, Patent Document 1 discloses a technique for forming a piezoelectric film having excellent crystal orientation by forming a piezoelectric film on a Ti-containing noble metal electrode on which Ti is deposited in an island shape. Is disclosed.

  Patent Document 2 discloses a technique for forming a piezoelectric film having excellent crystal orientation by using an MgO substrate as a substrate.

  Patent Document 3 discloses a method for manufacturing a ferroelectric film in which an amorphous ferroelectric film is formed and then crystallized by a rapid heating method.

  Patent Document 4 includes a perovskite complex oxide having a crystal structure of any one of a tetragonal system, an orthorhombic system, and a rhombohedral system, and includes (100) plane, (001) plane, and (111). ) Discloses a method for forming a piezoelectric film which is preferentially oriented to any one of the planes and has an orientation degree of 95% or more.

Many of the techniques disclosed in the above patent documents produce a PZT film on Pt. Pt is frequently used in this way because Pt has a face-centered cubic lattice (FCC) having a close-packed structure, and thus has a strong self-orientation and is a material such as amorphous SiO ₂ that is a material of a diaphragm. This is because even if the film is formed thereon, it is strongly oriented to (111) and the orientation of the piezoelectric film formed thereon is also improved. However, since the orientation is strong, columnar crystals grow, and there is also a problem that Pb and the like are easily diffused into the base electrode along the grain boundary. In general, Ir, Ru, Ti, Ta, Rh, Pd, etc. are used as electrode materials in addition to Pt.

  Further, it has been pointed out that oxygen vacancies in the piezoelectric body may increase over time when the piezoelectric body operates. For this reason, a conductive oxide electrode has come to be used at the contact interface between the lower electrode material and the dielectric material as a supply source of the deficient oxygen component.

Examples of the material used as the conductive oxide electrode include IrO ₂ , LaNiO ₃ , RuO ₂ , SrO, SrRuO ₃ , and CaRuO ₃ .

Among the materials of the conductive oxide electrode described above, strontium ruthenate represented by SrRuO ₃ (hereinafter, also simply referred to as “SRO”) has the same perovskite crystal structure as PZT. For this reason, it is excellent in bondability at the interface with PZT, is easy to realize the epitaxial growth of PZT, has excellent characteristics as a diffusion barrier layer of Pb, and various studies have been made on its application to piezoelectric actuators. .

  In Patent Document 5, a lower electrode having a structure in which an iridium or platinum layer is sandwiched between two (111) -oriented SROs having a perovskite structure is used, and (111) -oriented PZT is formed on the lower electrode. A piezoelectric actuator provided with a piezoelectric layer and an upper electrode is described. However, according to the study by the present inventors, depending on the degree to which the (111) orientation of the SRO is preferentially compared with the (110) orientation, the (100) orientation, and the (001) orientation, it is necessary as a piezoelectric actuator. It has been found that problems occur with the initial displacement and the deterioration of the displacement during continuous operation.

  Patent Document 6 describes a semiconductor device having a capacitor in which an SRO film is provided on at least one of an upper electrode and a lower electrode, and a dielectric film is sandwiched between both electrodes. Here, it is described that after forming an SRO film at room temperature, an amorphous SRO film is obtained, and then a crystallized SRO film is obtained by the RTA method. However, since the film thickness of the SRO film is 10 to 20 nm, when the same configuration is used as a piezoelectric actuator, the initial displacement cannot be obtained sufficiently, and a problem occurs when the continuous operation is performed. Further, according to the study by the present inventors, when the SRO film is formed by such a method, the (110) is easily preferentially oriented, and the PZT formed thereon is also (110) oriented. In this case, there is a problem that displacement deterioration cannot be suppressed.

  Patent Document 7 describes a structure in which an epitaxial film mainly composed of SRO is formed on a substrate having a Si (100) surface on the surface, and the surface roughness (average roughness) is 10 nm or less. . The ferroelectric film fabricated thereon has a (100) orientation. In order to suppress the deterioration of displacement characteristics when continuously operating as a piezoelectric actuator, when a PZT film is used as the piezoelectric film, the orientation is preferably (111), and the (100) oriented material cannot sufficiently suppress the deterioration. There was a problem.

Further, as a lower electrode, an electrode having a laminated structure in which a titanium film, a platinum film, and an SrRuO ₃ film are sequentially formed on a vibration plate has been conventionally studied. The reason why the titanium film is used is to improve the adhesion between the diaphragm and the lower electrode. However, when the titanium film is used as an adhesion layer, there is a problem that fine pores of 100 nm or less may be generated in the lower electrode film and on the lower electrode surface after the formation of platinum and SrRuO ₃ . This is presumably because voids were formed in the platinum film due to diffusion of titanium into the platinum film when the SrRuO ₃ film was formed at a high temperature.

  In Patent Document 8, a crystal body made of a compound of platinum and titanium oxide is formed as a lower electrode on a titanium oxide film serving as an adhesion layer of a lower electrode, and the grain boundary of the crystal body is the piezoelectric film. A piezoelectric thin film element that exists in a direction perpendicular to the film surface is disclosed. However, in this case, there is a problem that such a structure cannot suppress displacement deterioration when continuously operating as a piezoelectric actuator.

  In Patent Document 9, in order to improve the thermodynamic stability of the conductive perovskite-type metal oxide, a portion of Ru contained in SRO was replaced with Ti by disposing titanium in the lower layer of SRO. Are disclosed. However, the electrode configuration disclosed in the examples is SRO / Ti / Pt / Ti, and Pt / Ti is alloyed. For this reason, there has been a problem that displacement deterioration when continuously operating as a piezoelectric actuator cannot be sufficiently suppressed.

  As described above, various studies have been made on the structure of the electro-mechanical conversion element. However, there has been a problem that the displacement deterioration characteristic when the piezoelectric actuator is continuously operated cannot be suppressed.

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, an object of the present invention is to provide an electro-mechanical conversion element that has a relatively simple structure, suppresses displacement deterioration, and can obtain a stable driving force over time. To do.

In order to solve the above problems, the present invention provides a first adhesion layer formed on a substrate or a base film, a first electrode made of metal, formed on the first adhesion layer, and the first A second adhesion layer formed on the first electrode, and a strontium ruthenate film formed on the second adhesion layer and preferentially oriented in the (111) plane orientation, and having a thickness of 40 nm to 150 nm. Two electrodes, an electro-mechanical conversion film formed on the second electrode, a third electrode made of an oxide formed on the electro-mechanical conversion film, and the third electrode has a fourth electrode, a made of formed metal, said third and fourth electrodes are individual electrodes, the first contact layer is made of metallic oxide film, the second The adhesion layer is made of a metal film and has a thickness of 5 nm to 20 nm. Mind - to provide a mechanical conversion element.

  The electromechanical conversion element of the present invention can suppress displacement deterioration even when performing continuous operation, and can obtain a stable driving force over time.

Explanatory drawing of the structure of the electromechanical conversion element which concerns on the 1st Embodiment of this invention. X-ray diffraction pattern of SrRuO ₃ film in the first embodiment of the present invention Explanatory drawing of the crystallinity change of the PZT film | membrane by the presence or absence of the 2nd contact | adherence layer in the 1st Embodiment of this invention Explanatory drawing of the structure of the electromechanical conversion element which concerns on the 2nd Embodiment of this invention. Explanatory drawing of the structure of the droplet discharge head which concerns on the 3rd Embodiment of this invention. Explanatory drawing of the structure of the droplet discharge head which concerns on the 3rd Embodiment of this invention. FIG. 9 is a perspective explanatory view of a configuration of a droplet discharge device according to a fourth embodiment of the present invention. Side surface explanatory drawing of the mechanism part of the droplet discharge apparatus which concerns on the 4th Embodiment of this invention. Explanatory drawing of the manufacturing process of the PZT film in Example 1 of this invention Explanatory drawing of the structure of the electromechanical conversion element which concerns on Example 1 of this invention. Explanatory drawing of the structure of the electromechanical conversion element which concerns on Example 2 of this invention. Explanatory drawing of the structure of the electromechanical conversion element which concerns on the comparative example 1 FIG. 4 is an exemplary diagram of a PE hysteresis curve of the electromechanical transducer of the present invention.

Hereinafter, modes for carrying out the invention will be described with reference to the drawings, but the present invention is not limited to these examples.
[First Embodiment]
In the present embodiment, an electromechanical conversion element having the following configuration will be described.

  First, a first adhesion layer formed on a substrate or a base film, a first electrode made of metal formed on the first adhesion layer, and a first electrode formed on the first electrode 2 adhesion layers. Furthermore, a second electrode having a thickness of 40 nm or more and 150 nm or less formed of strontium ruthenate formed on the second adhesion layer and preferentially oriented in the (111) plane direction, and on the second electrode An electro-mechanical conversion film formed; a third electrode made of an oxide formed on the electro-mechanical conversion film; and a fourth electrode made of a metal formed on the third electrode; have. The third and fourth electrodes are individual electrodes, the first adhesion layer is made of a film obtained by oxidizing a metal film by an RTA method, and the second adhesion layer is made of a metal film, and the film thickness is It is 5 nm or more and 20 nm or less.

  A cross-sectional view of the electromechanical conversion element of this embodiment is schematically shown in FIG.

  As shown in FIG. 1, the electromechanical conversion element 10 of this embodiment includes a first adhesion layer 13 and a first electrode 14 on a vibration plate (film formation vibration plate) 12 as a base film on a substrate 11. The second adhesion layer 15 and the second electrode 16 are provided as the lower electrode 21. An electro-mechanical conversion film 17 as a piezoelectric film is provided on the lower electrode 21, and a third electrode 18 and a fourth electrode 19 are provided on the electro-mechanical conversion film 17 as the upper electrode 22. It is an element. As described above, the electro-mechanical conversion element 10 of the present embodiment has a structure in which the respective layers (films) are stacked in the above order. In the manufacture of a film structure such as a semiconductor manufacturing process as described later. The film is formed and formed by the technique used.

  Hereafter, each member which comprises the electromechanical conversion element of this embodiment is demonstrated.

  The substrate 11 is not particularly limited, but a silicon single crystal substrate is preferably used. Moreover, it is preferable that it is 100-600 micrometers as the thickness. There are three types of plane orientations of silicon single crystal substrates, (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry, and are available and processed. From the standpoint of ease, it is preferable to use a single crystal substrate having a (100) plane orientation.

  As will be described later, when the pressure chamber is manufactured by processing the substrate 11 when the droplet discharge head is formed, the processing is generally performed using etching. In this case, as an etching method, It is common to use anisotropic etching. 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, a structure having an inclination of about 54 ° can be produced in the plane orientation (100), whereas a deep groove can be dug in the plane orientation (110), so that the arrangement density is increased while maintaining rigidity. can do. For this reason, when processing a substrate using anisotropic etching to create a pressure chamber or the like, it is also possible to use a single crystal substrate having a (110) plane orientation.

  When the vibration plate 12 is a droplet discharge head as described above, the vibration plate 12 (base) is deformed and displaced by the force generated by the electro-mechanical conversion film 17, and ink droplets in the pressure chamber are discharged. It works to discharge. Therefore, it is preferable that the diaphragm 12 has a predetermined strength (required by the droplet discharge head).

  Examples of the material of the diaphragm 12 include silicon, silica, and silicon nitride. In this case, the diaphragm 12 can be manufactured by a CVD method.

Further, as the diaphragm 12, it is preferable to select a material close to the linear expansion coefficient of the lower electrode 21 and the electromechanical conversion film 17. For this reason, for example, since PZT is generally used as the material for the electro-mechanical conversion film, it is preferable to select a material having a linear expansion coefficient of 8 × 10 ⁻⁶ (1 / K). Specifically, a material having a linear expansion coefficient of 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ (1 / K) is preferable, and further 7 × 10 ^{−6 to} 9 × 10 ⁻⁶ (1 / K). A material having a linear expansion coefficient of is more preferable. Specific examples of the material in this case include aluminum oxide, zirconium oxide, iridium oxide, ruthenium oxide, tantalum oxide, hafnium oxide, osmium oxide, rhenium oxide, rhodium oxide, palladium oxide, and compounds thereof. These can also be used as the material of the diaphragm 12.

  The manufacturing method is not limited, and an appropriate method can be selected depending on the material. For example, it can be manufactured by a spin coater using a sputtering method or a Sol-gel method.

  The film thickness of the diaphragm 12 is not particularly limited, but is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 3 μm or less. If the thickness is smaller than this range, it may be difficult to process the pressure chamber when a droplet discharge head described later is used. If it is thicker than this range, the vibration plate (underground) is difficult to deform and displace, and in the case of a droplet discharge head, the discharge of ink droplets may become unstable.

The first adhesion layer 13 is obtained by forming a metal film and then oxidizing it (thermal oxidation) by an RTA method using a rapid thermal annealing (RTA) apparatus to form an oxide film. Conditions for the oxidation (thermal oxidation) are not limited, and can be selected depending on the material of the metal film to be used. For example, a method of thermally oxidizing a metal film by an RTA method in an O ₂ atmosphere at 650 to 800 ° C. for 1 to 30 minutes can be given. The metal film can be formed by sputtering, for example. As a material for the metal film, materials such as Ti, Ta, Ir, and Ru can be preferably used, and among these, Ti can be preferably used.

  As a method for producing the metal oxide film, reactive sputtering may be used. However, when producing by reactive sputtering, the substrate 11 also needs to be heated together at a high temperature, so that a special sputtering chamber configuration is required. It is not preferable in terms of cost.

  The reason why oxidation is performed by the RTA apparatus is that the crystallinity of the metal oxide film is better when the RTA apparatus is used than when oxidation is performed by a general heating furnace. This is because, for example, when a titanium oxide film is manufactured, if an oxidation process is performed in a general heating furnace, the easily oxidized titanium film forms several crystal structures at a low temperature, so that it is necessary to break it once. On the other hand, if the oxidation is performed by the RTA method, the rate of temperature rise is fast, so that it is not necessary to go through such a process, and a good crystal can be formed.

  The thickness of the first adhesion layer 13 is not particularly limited, but is preferably 10 nm or more and 50 nm or less, and more preferably 15 nm or more and 30 nm or less. When the film thickness is thinner than the above range, the adhesion between the diaphragm 12 and the first electrode 14 may deteriorate. Further, if the film thickness is larger than the above range, the crystal quality of the film of the first electrode 14 formed thereon may be affected. For this reason, it is preferable to select the said range.

  In the present invention, a film made of a metal oxide obtained by thermally oxidizing a metal film by the RTA method as described above is employed as the first adhesion layer, and the first adhesion layer has good crystallinity. Yes. For this reason, it becomes possible to prevent the diffusion of the metal component to the first electrode even if a heat treatment is performed when the second electrode is formed later.

  Examples of the material for the first electrode 14 and the fourth electrode 19 include platinum having high heat resistance and low reactivity, and iridium and platinum-rhodium, which have higher barrier properties against lead than conventional platinum. Examples include platinum group elements and alloys thereof.

Conventionally, in the case where platinum is used as the first electrode 14, the adhesion with the base (particularly when SiO ₂ is used as the diaphragm 12) may be deteriorated. Since the layer 13 is provided, platinum can be used as the first electrode 14 without any problem.

  Therefore, in the present invention, it is preferable to use platinum having high heat resistance and low reactivity as the first electrode 14.

  The first electrode 14 and the fourth electrode 19 can be produced by vacuum film formation such as sputtering or vacuum deposition.

  The film thicknesses of the first electrode 14 and the fourth electrode 19 are preferably 80 nm or more and 200 nm or less, and more preferably 100 nm or more and 150 nm or less.

  The second adhesion layer 15 is preferably a metal film. Specific examples of the material include Ti and Ta, and it is particularly preferable to use Ti.

  The film thickness is preferably 5 nm or more and 20 nm or less, and more preferably 10 nm or more and 15 nm or less. When the film thickness is thinner than the above range, the adhesion with the first electrode 14 and the second electrode 16 may deteriorate. If the film thickness is larger than the above range, the crystal quality of the second electrode film 16 and the electro-mechanical conversion film 17 formed on the second adhesion layer may be affected.

  The second adhesion layer 15 is preferably produced by sputtering. Further, after the film formation, it is preferable to continuously form the next second electrode 16 without breaking the vacuum. In this case, the second electrode is formed with the substrate heated at 500 ° C. or more. It is more preferable. This is because the crystal quality of the electro-mechanical conversion film produced after producing the second electrode 16 can be further improved, and the electro-mechanical conversion element obtained thereby is used as a piezoelectric actuator. This is because displacement deterioration after continuous driving can be suppressed.

As the second electrode 16, strontium ruthenate (SrRuO ₃ ) can be used as a material. Further, a material in which a part of strontium ruthenate is substituted, specifically, Sr _x (A) _1-x Ru _y (B) _(1-y) O ₃ (where A is Ba, Ca, B is Co, Ni, x, y = 0 to 0.5) can also be used.

For example, the second electrode can be formed by sputtering. The sputtering conditions are not limited. However, since the film quality of the SrRuO ₃ thin film varies depending on the sputtering conditions, it can be selected according to the required crystal orientation.

  For example, the electro-mechanical conversion film 17 to be described later is preferably oriented in the (111) plane orientation as its crystallinity in order to suppress deterioration of displacement characteristics when continuously operated. In order to obtain such an electromechanical conversion film, it is preferable that the second electrode 16 disposed in the lower layer is also oriented in the (111) plane orientation.

For this reason, the second electrode 16 is preferably made of a SrRuO ₃ film preferentially oriented in the (111) plane orientation.

The SrRuO ₃ film preferentially oriented in the (111) plane orientation with respect to the second electrode 16 is obtained by heating the substrate to 500 ° C. or higher and forming the second electrode thereon by sputtering. The first electrode 14 as the lower layer is preferably made of a platinum film and is oriented in the (111) plane direction as the plane direction. This is because an SrRuO ₃ film preferentially oriented in the (111) plane orientation for the second electrode 16 is easily obtained.

Here, for example, when a platinum film oriented in the (111) plane direction is used as the first electrode 14 and a second electrode (SrRuO ₃ film) is formed thereon, the crystallinity of the second electrode is expressed as X A method for evaluation by line diffraction measurement will be described. Since Pt and SRO have close lattice constants, in the θ-2θ measurement in the normal X-ray diffraction measurement, the 2θ positions of the (111) plane of the SRO film and the (111) plane of Pt overlap, making it difficult to discriminate. There's a problem. However, when Pt is tilted to Psi = 35 ° due to the extinction law, the diffraction lines cancel each other at a position where 2θ is about 32 °, and the diffraction intensity of Pt cannot be seen. Therefore, it is possible to confirm whether the SRO is preferentially oriented in the (111) plane orientation by inclining the Psi direction by about 35 ° and judging from the peak intensity where 2θ is about 32 °.

In FIG. 2, after a titanium oxide film is formed on a silicon substrate, a Pt film oriented in the (111) plane direction is formed, and a second adhesion layer (Ti film) is formed thereon. after, while heating the substrate to 550 ° C., it illustrates a SrRuO ₃ film X-ray diffraction measurement results of the formed sample by sputtering.

  FIG. 2 shows data when 2θ = 32 ° is fixed and Psi is changed. At Psi = 0 °, almost no diffraction intensity is observed on the diffraction line of the (110) plane of SRO, and diffraction intensity is observed at around Psi = 35 °. Therefore, this measurement method allows SRO to be in the (111) plane orientation. It can be confirmed that the orientation is preferential. In addition, from this result, it was confirmed that SRO was preferentially oriented in the (111) plane direction for those produced under the present film forming conditions.

The surface roughness of the SrRuO ₃ film used for the second electrode 16 is preferably 4 nm or more and 15 nm or less, and more preferably 6 nm or more and 10 nm or less. In addition, about the surface roughness here, the surface roughness (average roughness) measured by AFM is meant.

The surface roughness of the SrRuO ₃ film affects the film formation temperature. When the substrate is heated from room temperature to 300 ° C., the surface roughness is very small and is 2 nm or less. In this case, the surface roughness is very small and flat, but the crystallinity of the SrRuO ₃ film is not sufficient. For this reason, sufficient characteristics cannot be obtained for the initial displacement as a piezoelectric actuator of the electro-mechanical conversion film (for example, PZT film) to be formed thereafter and the deterioration of the displacement after continuous driving.

Accordingly, the surface roughness obtained without deteriorating the crystallinity of the SrRuO ₃ film is within the above range in view of the film forming conditions, and thus preferably has the above range.

When deviating from the above range, the crystallinity of the SrRuO ₃ film may be deteriorated, and the withstand voltage of the electro-mechanical conversion film to be formed thereafter is deteriorated and may easily leak, which is not preferable.

In order to obtain the SrRuO ₃ film having crystallinity and surface roughness as described above, the film formation conditions (temperature) are 500 ° C. to 700 ° C., preferably 520 ° C. to 600 ° C. It is preferable to form a film by heating and sputtering.

  The composition ratio of Sr and Ru after film formation is not particularly limited, and is selected according to required conductivity, but it is preferable that Sr / Ru is 0.82 or more and 1.22 or less.

  This is because if it is out of the above range, the specific resistance increases, and sufficient conductivity as an electrode may not be obtained.

  Furthermore, the film thickness of the SRO film as the second electrode 16 is preferably 40 nm or more and 150 nm or less, and more preferably 50 nm or more and 80 nm or less. If the thickness is less than the above range, sufficient characteristics may not be obtained for initial displacement and displacement deterioration after continuous driving. Further, if the film thickness exceeds the above-mentioned film thickness range, the dielectric strength voltage of the PZT formed thereafter is deteriorated and it may be likely to leak.

  As the third electrode 18, an oxide, that is, a conductive oxide can be used. By using a conductive oxide, when the electromechanical conversion element operates, it can function as a supply source for oxygen vacancies in the piezoelectric body that occur over time.

Specific examples of materials that can be used for the conductive oxide electrode layer include IrO ₂ , LaNiO ₃ , RuO ₂ , SrO, SrRuO ₃ , and CaRuO ₃ . In particular, it is preferable to use the same material as that of the second electrode 16. That is, it is preferable to use a SrRuO ₃ film (or a partially substituted material).

  When an SRO film is used as the third electrode 18, the film thickness is preferably 40 nm or more and 80 nm or less, and more preferably 50 nm or more and 60 nm or less. If it is thinner than the above film thickness range, sufficient characteristics may not be obtained for the initial displacement and displacement deterioration characteristics. On the other hand, exceeding the above range is not preferable because the dielectric strength voltage of PZT is deteriorated and may easily leak.

  As the electro-mechanical conversion film 17, any material having piezoelectricity can be used.

  For example, PZT that is widely used can be preferably used.

PZT is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTiO ₃ ), and the characteristics differ depending on the ratio. However, the ratio is not limited, and the required piezoelectric performance, etc. Can be selected accordingly. Among them, the ratio (molar ratio) of PbZrO ₃ and PbTiO ₃ is 53:47, and it is expressed by the chemical formula PZT (PZT (53/47)) represented by Pb (Zr _0.53 , Ti _0.47 ) O _3. Can be preferably used because it exhibits particularly excellent piezoelectric properties.

  Barium titanate can also be used as a material other than PZT.

The PZT and barium titanate are represented by the general formula ABO _{3. In} addition to PZT and barium titanate, ABO ₃ (A = Pb, Ba, Sr, B = Ti, Zr, Sn, Ni, Zn, A composite oxide mainly composed of a composite oxide represented by Mg, Nb) can be used.

Further, as in (Pb _1-x , Ba _x ) (Zr, Ti) O ₃ , (Pb _1-x , Sr _x ) (Zr, Ti) O ₃ , part of Pb at the A site is replaced with Ba or Sr. It is also possible to use the composite oxide. The element used for the substitution can be any divalent element, and when heat treatment is performed when the electromechanical conversion film 17 is formed by substituting a part of Pb with the divalent element. There is an effect of reducing characteristic deterioration due to evaporation of lead.

  The method for producing the electro-mechanical conversion film 17 is not particularly limited, and for example, it can be produced by a sputtering method or a Sol-gel method.

  Then, after film formation, patterning can be performed by photolithography etching or the like to obtain a desired pattern.

  The case where the electromechanical conversion film 17 made of PZT is manufactured by the Sol-gel method will be described as an example.

  PZT precursor solution is prepared by using lead acetate, zirconium alkoxide, and titanium alkoxide compound as starting materials, using methoxyethanol as a common solvent, and dissolving the above starting materials in a common solution so as to have a predetermined ratio to obtain a uniform solution. To do.

  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 can be added to the precursor solution as a stabilizer. In addition, since the lead component may evaporate during heat treatment in the film forming process, it can be added in a larger amount than the stoichiometric ratio.

  When a PZT film is obtained on the entire surface of the substrate, the PZT film can be obtained by forming a coating film by a solution coating method such as spin coating and applying heat treatments such as solvent drying, thermal decomposition, and crystallization. Since the transformation from the coating film to the crystallized film involves volume shrinkage, it is preferable to adjust the precursor concentration so as to obtain a film thickness of 100 nm or less in one step in order to obtain a crack-free film, A PZT film having a desired film thickness can be obtained by repeatedly performing the film forming process.

  In the case of a barium titanate film, for example, a barium alkoxide, titanium alkoxide compound is used as a starting material, and dissolved in a common solvent to prepare a barium titanate precursor solution. It is possible to form a film by the Sol-gel method in the same procedure as in the case.

  The film thickness of the electro-mechanical conversion film is not limited and may be selected according to the required piezoelectric characteristics, but is preferably 0.5 μm or more and 5 μm or less, and preferably 1 μm or more and 2 μm or less. Is more preferable. This is because if the thickness is smaller than the above range, sufficient displacement may not be generated when used as a piezoelectric actuator. If the thickness is larger than the above range, many layers are laminated in the manufacturing process. This is because film formation increases the number of steps and the process time.

  Here, on the silicon substrate on which the thermal oxide film is formed, as described above, the first adhesion layer made of titanium oxide, the first electrode made of platinum, the second adhesion layer made of titanium, and the film thickness is 0. FIG. 3 shows an X-ray diffraction pattern of a sample prepared by forming a 0.06 μm strontium ruthenate second electrode and further forming a PZT film having a thickness of 2 μm by the Sol-gel method.

  FIG. 3 also shows an X-ray diffraction pattern of a sample prepared in the same manner except that the second adhesion layer is not provided as a comparative sample.

  According to this, when compared with the presence or absence of the second adhesion layer, the crystallinity of the PZT film can be further enhanced when the second adhesion layer is inserted, and the (111) plane orientation is preferentially oriented. It can be seen that a film is obtained. For this reason, when the electro-mechanical conversion element is used as a piezoelectric actuator, it is possible to suppress displacement deterioration and obtain a stable driving force with time.

  Here, the electro-mechanical conversion film using PZT has been described as an example, but even when other materials are used, the crystallinity can be similarly improved by providing the second adhesion layer. An effect is obtained.

As described above, the electromechanical conversion element 10 of the present embodiment has a simple structure, suppresses displacement deterioration even when continuous operation is performed, and obtains a stable driving force over time. [Second Embodiment]
In this embodiment, an electromechanical conversion element having the following configuration will be described.

  First, a first adhesion layer formed on a substrate or a base film, a first electrode made of metal formed on the first adhesion layer, and formed on the first electrode, A second electrode having a thickness of 40 nm to 150 nm made of strontium ruthenate preferentially oriented in the (111) plane orientation. Furthermore, a third adhesion layer formed on the second electrode, an electro-mechanical conversion film formed on the third adhesion layer, and an oxidation formed on the electro-mechanical conversion film A third electrode made of a material, and a fourth electrode made of metal formed on the third electrode. The third and fourth electrodes are individual electrodes, the first adhesion layer is made of a film obtained by oxidizing a metal film by an RTA method, and the third adhesion layer is made of a metal film, and the film thickness is It is 1 nm or more and 10 nm or less.

  FIG. 4 shows a specific configuration of the electromechanical conversion element of this embodiment.

  The electro-mechanical conversion element 40 shown in this embodiment has the configuration shown in FIG. 4, and the second adhesion layer 15 is not provided in the electro-mechanical conversion element 10 described in the first embodiment. Since this is provided with the third adhesion layer 41, this point will be described. For the configuration of other films (layers), refer to the first embodiment. In FIG. 4, the same members as those in FIG.

  As shown in FIG. 4, the third adhesion layer 41 is provided on the second electrode 16.

  The third adhesion layer 41 is preferably a metal film, and specific materials thereof include, for example, Ti and Ta, and it is particularly preferable to use Ti.

  The third adhesion layer can be produced, for example, by sputtering.

  The film thickness is preferably 1 nm or more and 10 nm or less, and more preferably 3 nm or more and 7 nm or less. When the film thickness is thinner than the above range, there may be a case where a sufficient effect cannot be obtained for suppressing displacement deterioration after the obtained electro-mechanical conversion element is continuously driven. When the film thickness is larger than the above range, the crystal quality of the electromechanical conversion film 17 formed on the third adhesion layer 41 is affected.

By providing the third adhesion layer 41, as in the case of the second adhesion layer described in the first embodiment, it is possible to increase the crystallinity of the electromechanical conversion element 17 formed thereon. Become. For this reason, the electromechanical conversion element 40 of the present embodiment has a simple structure, and even when continuous operation is performed, it is possible to suppress displacement deterioration and obtain a stable driving force over time. is there.
[Third Embodiment]
In this embodiment, a droplet discharge head including the electro-mechanical conversion element 10 (40) described in the first embodiment and the second embodiment will be described.

  A droplet discharge head described in this embodiment is shown in FIGS. 5 is a schematic diagram showing an example of the configuration of one nozzle, and FIG. 6 is a liquid formed by arranging a plurality of one-nozzle droplet discharge heads 50 shown in FIG. An outline of the droplet discharge head 60 is shown.

  5 and 6 includes a nozzle that discharges droplets, a pressurizing chamber that communicates with the nozzle, a diaphragm that forms part of the wall of the pressurizing chamber, and a diaphragm on the diaphragm. A droplet discharge head comprising the electro-mechanical conversion element described in the first and second embodiments.

  The configuration of the droplet discharge head 50 will be specifically described with reference to FIG.

  The discharge driving means for increasing the pressure of the liquid in the pressurizing chamber 53 is constituted by the vibration plate 12 constituting a part of the wall of the pressurization chamber, and the electro-mechanical conversion element 10 (40) is disposed on the vibration plate. . In addition, a pressurizing chamber (pressure chamber) that is an ink chamber that is formed by etching the substrate 11 on which the electro-mechanical conversion element 10 (40) is formed and stores a liquid such as ink (hereinafter referred to as “ink”). 53 and a nozzle plate 55 as an ink nozzle provided with a nozzle 54 as a nozzle hole as an ink discharge port for discharging the ink in the pressurizing chamber 53 in the form of droplets.

  As a mechanism by which the droplet discharge head 50 discharges droplets, power is supplied to the lower electrode 21 and the upper electrode 22 to generate stress in the electro-mechanical conversion film 17, thereby causing the vibration plate (vibration plate) 12 to move. Vibrate. Along with this vibration, the ink in the pressurizing chamber 53 is ejected from the nozzle 54 in the form of droplets. Note that illustration and description of liquid supply means, ink flow paths, and fluid resistance, which are ink supply means for supplying ink into the pressurizing chamber 53, are omitted.

  According to such a droplet discharge head, since the electro-mechanical conversion element of the present invention described in the first and second embodiments is used, there is no ink droplet discharge failure due to vibration plate drive failure, and stable ink droplets. Discharge characteristics can be obtained.

Further, the electro-mechanical conversion element has a simple structure (and has performance equivalent to that of bulk ceramics), and further, etching removal from the back surface for forming a pressure chamber, and a nozzle plate having nozzle holes By joining the droplets, a droplet discharge head can be easily obtained.
[Fourth Embodiment]
In the present embodiment, a droplet discharge device including the droplet discharge head described in the third embodiment will be described.

  An example of the droplet discharge device is an ink jet recording device, and a specific configuration example of the ink jet recording device will be described with reference to FIGS.

  7 is an explanatory perspective view of the recording apparatus, and FIG. 8 is an explanatory side view of a mechanism portion of the recording apparatus.

  The ink jet recording apparatus includes a carriage 71 movable in the main scanning direction inside the recording apparatus main body 70, a recording head comprising the ink jet head embodying the present invention mounted on the carriage 71, and an ink cartridge 72 for supplying ink to the recording head. A paper feed cassette (or a paper feed tray) 75 on which a large number of sheets 74 can be stacked from the front side is freely detachable at the lower part of the apparatus main body 70. The manual feed tray 76 for manually feeding the paper 74 can be opened, the paper 74 fed from the paper feed cassette 75 or the manual feed tray 76 is taken in, and the printing mechanism After recording a required image by the unit 73, the image is discharged to a discharge tray 77 mounted on the rear side.

  The printing mechanism 73 holds a carriage 71 slidably in the main scanning direction by a main guide rod 78 and a sub guide rod 79 which are guide members horizontally mounted on left and right side plates (not shown). (Y), cyan (C), magenta (M), and black (Bk). The head 80 formed of the inkjet head according to the present invention that discharges ink droplets of each color has a plurality of ink discharge ports (nozzles) as the main scanning direction. They are arranged in the intersecting direction and mounted with the ink droplet ejection direction facing downward. Further, each ink cartridge 72 for supplying ink of each color to the head 80 is replaceably mounted on the carriage 71.

  The ink cartridge 72 has an air port that communicates with the atmosphere upward, a supply port that supplies ink to the inkjet head 80 below, and a porous body filled with ink inside, and a capillary tube for the porous body. The ink supplied to the inkjet head is maintained at a slight negative pressure by force. Further, although the heads 80 of the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets of the respective colors may be used.

  Here, the carriage 71 is slidably fitted to the main guide rod 78 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 79 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 71 in the main scanning direction, a timing belt 84 is stretched between a driving pulley 82 and a driven pulley 83 that are rotationally driven by a main scanning motor 81, and the timing belt 84 is moved to the carriage 71. The carriage 71 is reciprocated by the forward and reverse rotation of the main scanning motor 81.

  On the other hand, in order to convey the paper 74 set in the paper feed cassette 75 to the lower side of the head 80, the paper 74 is guided from the paper feed cassette 75 to the paper feed roller 85 and the friction pad 86 for separating and feeding the paper 74. A guide member 87, a transport roller 88 that reverses and transports the fed paper 74, a transport roller 89 that is pressed against the peripheral surface of the transport roller 88, and a tip that defines the feed angle of the paper 74 from the transport roller 89 A roller 90 is provided. The transport roller 88 is rotationally driven by a sub-scanning motor 91 through a gear train.

  A printing receiving member 92 is provided as a paper guide member for guiding the paper 74 fed from the transport roller 88 below the recording head 80 corresponding to the range of movement of the carriage 71 in the main scanning direction. On the downstream side of the printing receiving member 92 in the sheet conveyance direction, a conveyance roller 93 and a spur 94 that are rotationally driven to send the sheet 74 in the sheet discharge direction are provided, and the sheet 74 is further discharged to the sheet discharge tray 77. A roller 95 and a spur 96, and guide members 97 and 98 that form a paper discharge path are disposed.

At the time of recording, the recording head 80 is driven according to the image signal while moving the carriage 71 to eject ink onto the stopped paper 74 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 74 has reached the recording area, the recording operation is terminated and the paper 74 is discharged.
In FIG. 7, a recovery device 99 for recovering the ejection failure of the head 80 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 71. The recovery device 99 includes a cap unit, a suction unit, and a cleaning unit. The carriage 71 is moved to the recovery device 99 side during printing standby, and the head 80 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection 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 a discharge failure occurs, the discharge port (nozzle) of the head 80 is sealed with a capping unit, and bubbles and the like are sucked out from the discharge port with the suction unit through the tube. Is removed by the cleaning means to recover the ejection failure. 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.

  In such an ink jet recording apparatus, by mounting the droplet discharge head (inkjet head) using the electro-mechanical conversion element described in the third embodiment, ink droplet discharge failure due to vibration plate drive failure is prevented. Therefore, stable ink droplet ejection characteristics can be obtained, and image quality can be improved.

The present invention will be described below with reference to specific examples and comparative examples, but the present invention is not limited to these examples [Example 1].
The electromechanical conversion element was produced by the following procedure.

  A thermal oxide film (film thickness 1 μm) serving as a vibration plate was formed on a silicon wafer.

  Next, after forming a titanium film (film thickness: 30 nm) with a sputtering apparatus, the first adhesion layer was formed by thermal oxidation at 750 ° C. by the RTA method.

Subsequently, a platinum film (film thickness: 150 nm) was formed as the first electrode, a titanium film (film thickness: 10 nm) as the second adhesion layer, and an SrRuO ₃ film (film thickness: 60 nm) as the second electrode. The substrate was heated at 550 ° C. when the second electrode was formed by sputtering.

Next, as a precursor solution for forming an electromechanical conversion film, two types of solutions (PZT-1 and PZT-2) containing metal species at the molar ratio shown below are prepared, as shown in FIG. A laminated film was produced.
PZT-1 (Pb: Zr: Ti = 110: 53: 47)
PZT-2 (Pb: Zr: Ti = 120: 53: 47)
In each of the above PZT solutions, 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.

  A procedure for synthesizing a specific precursor coating solution will be described.

  First, 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.

  By dissolving isopropoxide titanium and isopropoxide zirconium in methoxyethanol at a predetermined ratio, proceeding with alcohol exchange reaction and esterification reaction, and mixing with methoxyethanol solution in which lead acetate is dissolved to a predetermined ratio. A PZT precursor solution was synthesized. At this time, the PZT concentration in the solution was adjusted to 0.5 mol / L.

  Using this liquid, it apply | coated to the base material with the spin coat method, and after apply | coating about each layer, it dried at 120 degreeC and also thermally decomposed at 500 degreeC.

  As shown in FIG. 9, the PZT-1 solution was used for the first and second layers, and the PZT-2 solution was used for the third layer. After the thermal decomposition treatment of the third layer, crystallization heat treatment (temperature 750 ° C.) was performed on the first to third layer portions by the RTA method (rapid heat treatment). The film thickness of PZT obtained at this time was 240 nm. This process was repeated a total of 8 times (24 layers) to obtain a PZT film having a thickness of about 2 μm.

Next, a SrRuO ₃ film (film thickness 40 nm) was formed as a _third electrode, and a Pt film (film thickness 125 nm) was formed as a fourth electrode by sputtering. Thereafter, a photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. was formed by spin coating, a resist pattern was formed by ordinary photolithography, and then a pattern was prepared using an ICP etching apparatus (manufactured by Samco).

  Next, as the insulating protective film 107, a parylene film (film thickness: 2 μm) was formed by CVD. Thereafter, a photoresist made by Tokyo Ohka Co., Ltd. (TSMR8800) was formed by spin coating, a resist pattern was formed by ordinary photolithography, and then a pattern as shown in FIG. 10 was produced using RIE (manufactured by Samco).

  Finally, an Al film (film thickness 5 μm) was formed by sputtering as the fifth and sixth electrodes. Thereafter, a photoresist made by Tokyo Ohka Co., Ltd. (TSMR8800) was formed by spin coating, a resist pattern was formed by ordinary photolithography, and then a pattern as shown in FIG. 10 was produced using RIE (manufactured by Samco). An electromechanical conversion element was produced.

  Through the above steps, an electromechanical transducer having the structure shown in FIG. 10 was produced. An upper view (a) of FIG. 10 shows a cross-sectional view, and a lower view (b) shows a top view. In the figure, the same members as those in FIG.

  Specifically, on the substrate 11, the diaphragm 12, the first adhesion layer 13, and the first electrode 14, the second adhesion layer and the second electrode 101, the electromechanical conversion film 17, the third The fourth electrode 102 and the fourth electrode 102 are formed, and an insulating protective film 107 is formed so as to cover it. Contact holes 103 and 104 are formed at predetermined positions of the insulating protective film 107, and the fifth electrode 105 and the sixth electrode 106 are respectively connected to the lower electrode and the upper electrode of the electromechanical transducer through the contact holes. It is connected to the electrode.

  The fifth electrode 105 is a common electrode, so that the lower electrode of the electromechanical conversion element functions as a common electrode. Further, the sixth electrode 106 is an individual electrode, so that the upper electrode of the electro-mechanical conversion element functions as an individual electrode.

  Table 1 shows the results of evaluation of the obtained electro-mechanical conversion element. The evaluation method will be described later.

[Example 2]
An electromechanical conversion element was produced by the following procedure.

  A thermal oxide film (film thickness 1 μm) serving as a vibration plate was formed on a silicon wafer.

  Next, after forming a titanium film (film thickness: 30 nm) with a sputtering apparatus, the first adhesion layer was formed by thermal oxidation at 750 ° C. by the RTA method.

Subsequently, a platinum film (thickness: 150 nm) was formed as a first electrode, a SrRuO ₃ film (thickness: 60 nm) as a second electrode, and a titanium film (thickness: 5 nm) as a third adhesion layer. The substrate was heated at 550 ° C. when the second electrode was formed by sputtering. Other than that was carried out similarly to Example 1, and produced the electromechanical conversion element as shown in FIG.

  Note that FIG. 11 shows a cross-sectional view of the upper view (a) and a top view of the lower view (b) as in the case of FIG. The same members as those in FIG. 10 are denoted by the same reference numerals, and instead of the second adhesion layer and the second electrode 101 as described above, the second electrode and the third adhesion layer 108 are used. Is different.

[Example 3]
An electromechanical conversion element as shown in FIG. 10 was produced in the same manner as in Example 1 except that a SrRuO ₃ film (film thickness: 145 nm) was used as the second electrode.

[Example 4]
An electro-mechanical conversion element as shown in FIG. 10 was produced in the same manner as in Example 1 except that the second electrode was a SrRuO ₃ film (film thickness 45 nm).

[Example 5]
An electromechanical conversion element as shown in FIG. 10 was produced in the same manner as in Example 1 except that a titanium film (film thickness: 15 nm) was used as the second adhesion layer.

[Example 6]
An electromechanical conversion element as shown in FIG. 11 was produced in the same manner as in Example 2 except that a titanium film (film thickness: 8 nm) was used as the third adhesion layer.

[Example 7]
An electromechanical conversion element as shown in FIG. 11 was produced in the same manner as in Example 2 except that a titanium film (film thickness: 2 nm) was used as the third adhesion layer.

[Comparative Example 1]
An electromechanical conversion element as shown in FIG. 12 was produced in the same manner as in Example 1 except that the second adhesion layer and the third adhesion layer were not provided.

  In FIG. 12, as in FIG. 10, the upper diagram (a) shows a cross-sectional view and the lower diagram (b) shows a top view. The same members as those in FIGS. 1 and 10 are denoted by the same reference numerals.

[Comparative Example 2]
An electromechanical conversion element as shown in FIG. 10 was produced in the same manner as in Example 1 except that the second electrode was a SrRuO ₃ film (film thickness: 165 nm).

[Comparative Example 3]
An electromechanical conversion element as shown in FIG. 10 was produced in the same manner as in Example 1 except that a titanium film (film thickness 30 nm) was used as the second adhesion layer.

[Comparative Example 4]
An electromechanical conversion element as shown in FIG. 10 was produced in the same manner as in Example 1 except that a titanium film (film thickness: 2 nm) was used as the second adhesion layer.

[Comparative Example 5]
An electromechanical conversion element as shown in FIG. 11 was produced in the same manner as in Example 2 except that a titanium film (film thickness: 30 nm) was used as the third adhesion layer.

[Comparative Example 6]
An electro-mechanical conversion element as shown in FIG. 11 was produced in the same manner as in Example 2 except that a titanium film (film thickness: 0.5 nm) was used as the third adhesion layer.

[Comparative Example 7]
After forming a titanium film (thickness 30 nm) as a first adhesion layer with a sputtering apparatus, RTA treatment is not performed, and a platinum film (thickness 150 nm) is continuously used as the first electrode. An electro-mechanical conversion element as shown in FIG. 10 was produced in the same manner as in Example 1 except that a titanium film (film thickness: 10 nm) as a layer and a SrRuO ₃ film (film thickness: 60 nm) as a second electrode were formed by sputtering. did.

About the electromechanical conversion element produced in Examples 1-7 and Comparative Examples 1-7, the electrical property and the electromechanical conversion ability (piezoelectric constant) were evaluated. A typical PE hysteresis curve is shown in FIG. The electro-mechanical conversion ability was calculated from the amount of deformation due to electric field application (150 kV / cm) measured by a laser Doppler vibrometer and adjusted by simulation. After evaluating the initial characteristics, durability (characteristics immediately after applying the voltage ¹⁰ times ¹⁰ times) was evaluated. These detailed results are summarized in Table 1.

In Examples 1 to 7, the results of the initial characteristics were similar to those of a general ceramic sintered body (residual polarization Pr: 20 to 27 μC / cm ² , piezoelectric constant: −120 to −140 pm / V). ). Furthermore, it was confirmed that the performance hardly changed even after the durability test.

On the other hand, immediately after the comparative example 1-7, the initial characteristics is a common ceramic sintered body and the same degree that the repeatedly applied voltage to 10 ¹⁰ times repetition durability after the test plus voltage (10 ¹⁰ times ), It was confirmed that both the remanent polarization and the piezoelectric constant were greatly deteriorated as compared with Examples 1-7.

  Using the electro-mechanical conversion elements produced in Examples 1 to 7, the droplet ejection heads shown in FIGS. 5 and 6 were produced, and liquid ejection was evaluated. Using ink with viscosity adjusted to 5 cp and confirming the discharge status when an applied voltage of -10 to -30 V was applied with a simple Push waveform, it was confirmed that ink could be discharged from all nozzle holes. It was.

  According to the above results, in Examples 1 to 7 which are the electromechanical conversion elements of the present invention, it is confirmed that even when continuous operation is performed, displacement deterioration is suppressed and a stable driving force is obtained over time. did it. Further, it was confirmed that the ink droplet ejection head has stable ink droplet ejection characteristics even when it is a droplet ejection head.

11 substrate, base film 12 diaphragm 13 first adhesion layer 14 first electrode 15 second adhesion layer 16 second electrode 17 electro-mechanical conversion film 18 third electrode 19 fourth electrode 10, 60 electricity Mechanical conversion element 20 droplet discharge head 23 pressurizing chamber 24 nozzle 61 third adhesion layer

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. 4572346 Japanese Patent No. 3784401

Claims (9)

A first adhesion layer formed on a substrate or a base film;
A first electrode made of metal formed on the first adhesion layer;
A second adhesion layer formed on the first electrode;
A second electrode having a thickness of 40 nm or more and 150 nm or less formed of strontium ruthenate formed on the second adhesion layer and preferentially oriented in the (111) plane orientation;
An electro-mechanical conversion film formed on the second electrode;
A third electrode made of an oxide formed on the electro-mechanical conversion film;
A fourth electrode made of metal formed on the third electrode,
The third and fourth electrodes are individual electrodes,
Said first contact layer is made of metallic oxide film,
The electro-mechanical conversion element, wherein the second adhesion layer is made of a metal film and has a thickness of 5 nm to 20 nm. A first adhesion layer formed on a substrate or a base film;
A first electrode made of metal formed on the first adhesion layer;
A second electrode having a thickness of 40 nm or more and 150 nm or less made of strontium ruthenate formed on the first electrode and preferentially oriented in the (111) plane orientation;
A third adhesion layer formed on the second electrode;
An electro-mechanical conversion film formed on the third adhesion layer;
A third electrode made of an oxide formed on the electro-mechanical conversion film;
A fourth electrode made of metal formed on the third electrode, and the third and fourth electrodes are individual electrodes,
Said first contact layer is made of metallic oxide film,
The electro-mechanical conversion element, wherein the third adhesion layer is made of a metal film and has a thickness of 1 nm to 10 nm.   The electromechanical transducer according to claim 1, wherein the second adhesion layer is made of titanium.   The electro-mechanical transducer according to claim 2, wherein the third adhesion layer is made of titanium.   5. The electromechanical conversion element according to claim 1, wherein the first adhesion layer has a thickness of 10 nm to 50 nm. The first adhesion layer, electric according to any one of claims 1 to 5, characterized in that a metal oxide film of titanium emissions - mechanical conversion element. The electromechanical conversion element according to any one of claims 1 to 6, wherein the first electrode is made of platinum and has a thickness of 80 nm to 200 nm. A nozzle for discharging droplets;
A pressurizing chamber to which the nozzle communicates;
A diaphragm constituting a part of the wall of the pressurizing chamber;
A liquid droplet ejection head comprising: the electro-mechanical conversion element according to claim 1 formed on the vibration plate.   A droplet discharge apparatus comprising the droplet discharge head according to claim 8.

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