JP2013187445A - Electro-mechanical conversion element, droplet discharge head, and droplet discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-mechanical conversion element which sufficiently achieves the improvement of the reliability.SOLUTION: An electro-mechanical conversion element 500 includes: a substrate 230 or a deposition diaphragm 231; a lower electrode 300 formed on the substrate 230 or the deposition diaphragm 231 through a first adhesion layer 232; an electro-mechanical conversion film 243 formed on the lower electrode 300; and an upper electrode 400 formed on the electro-mechanical conversion film 243. The lower electrode 300 includes: a first electrode 233 formed on the first adhesion layer 232 and formed by a metal film; a second electrode 234 formed on the first electrode 233 and formed by an oxidative product; a second adhesive layer 235 formed on the second electrode 234; and a third electrode 236 formed on the second adhesion layer 235. The upper electrode 400 includes a fourth electrode 244 formed on the electro-mechanical conversion film 243 and formed by an oxidative product; and a fifth electrode 245 formed on the fourth electrode 244 and made of a metal.

Description

  The present invention relates to an electromechanical conversion element having an electromechanical conversion function, a droplet discharge head including the electromechanical conversion element, and a droplet discharge apparatus including the droplet discharge head.

  2. Description of the Related Art Conventionally, an electro-mechanical conversion element used for a printer head of an ink jet printer is known (see Patent Document 1).

  Such an electro-mechanical conversion element includes a substrate, a lower electrode layer formed on the substrate, an electro-mechanical conversion film formed on the lower electrode layer, and an electro-mechanical conversion film on the electro-mechanical conversion film. And an upper electrode layer formed.

  This electro-mechanical conversion element becomes a thin film actuator by applying an electric field to the electro-mechanical conversion film via the upper and lower electrodes, and these are used for an ink jet head.

  However, this electro-mechanical conversion element has a problem in that it is insufficient in terms of reliability (piezoelectric characteristics deteriorate as the number of repeated application of electric field).

  An object of the present invention is to provide an electro-mechanical conversion element capable of sufficiently improving the reliability, a droplet discharge head including the electro-mechanical conversion element, and a droplet discharge apparatus including the droplet discharge head. Is to provide.

The invention of claim 1 includes a substrate or a base film, a lower electrode formed on the substrate or the base film via a first adhesion layer, an electro-mechanical conversion film formed on the lower electrode, An electro-mechanical conversion element comprising an upper electrode formed on the electro-mechanical conversion film,
The lower electrode is formed on the first adhesion layer and is made of a first electrode made of a metal film, a second electrode made of an oxide formed on the first electrode, and the second electrode. A second adhesion layer formed on the electrode, and a third electrode formed on the second adhesion layer,
The upper electrode includes a fourth electrode made of an oxide formed on the electro-mechanical conversion film, and a fifth electrode made of a metal formed on the fourth electrode. To do.

  According to the present invention, the reliability of the electromechanical conversion element can be improved.

1 is a perspective view showing an appearance of a main part of an ink jet recording apparatus according to the present invention. It is sectional drawing which showed the structure of the inkjet recording device shown in FIG. FIG. 2 is a cross-sectional view conceptually showing the configuration of an electromechanical conversion element of an ink jet head of the ink jet recording apparatus shown in FIG. 1. It is explanatory drawing which showed schematically the structure which integrated the inkjet head shown in FIG. It is a graph which shows the relationship between Psi and diffraction intensity when fixed to 2θ = 32 °. It is a graph which shows the relationship between 2 (theta) when a crystal structure is investigated by XRD, and diffraction intensity. It is explanatory drawing which showed the laminated film. It is sectional drawing which showed the structure of the droplet discharge head of 1st Example. 1A is a cross-sectional view showing a configuration of a droplet discharge head, and FIG. It is the graph which showed the typical PE hysteresis curve of an Example. It is the table | surface which showed durability evaluation of the Example and the comparative example.

  Hereinafter, an example which is an embodiment of an electromechanical conversion element (piezoelectric element) according to the present invention will be described with reference to the drawings.

FIG. 3 shows a configuration of a recording head (inkjet head) 94 which is a droplet discharge head using the electro-mechanical conversion element according to the present invention.
[Recording head]
The recording head 94 includes a pressure chamber substrate 220 that forms a pressure chamber (pressurizing chamber) 221 and has a U-shaped cross-section with an opening at the bottom, and a nozzle plate 210 that closes the opening at the bottom of the pressure chamber substrate 220. The pressure chamber substrate 220 is formed of an Si substrate and has a substrate 230 as a base made of the Si substrate. The nozzle plate 210 is formed with nozzle holes 211 that are ink discharge ports.

  A film formation vibration plate 231 that is a base film is formed on the substrate 230, and a first adhesion layer 232 is formed on the film formation vibration plate 231. Further, the first electrode 233 is formed in layers on the first adhesion layer 232, the second electrode 234 is formed on the first electrode 233, and the second electrode 234 is formed on the second electrode 234. The adhesion layer 235 is formed, and the third electrode 236 is formed in layers on the second adhesion layer 235.

  The first electrode 233, the second electrode 234, the second adhesion layer 235, and the third electrode 236 constitute the lower electrode 300.

  An electro-mechanical conversion film 243 is formed on the third electrode 236, a fourth electrode 244 is formed on the electro-mechanical conversion film 243 in a layered manner, and a fifth electrode 245 is formed on the fourth electrode 244. Are formed in layers. The upper electrode 400 is configured by the fourth electrode 244 and the fifth electrode 245, and the electro-mechanical conversion element 500 is configured by the lower electrode 300, the electro-mechanical conversion film 243, and the upper electrode 400.

  In addition, the substrate 230 and the electromechanical conversion element 500 constitute discharge driving means for increasing the pressure of the liquid (not shown) in the pressure chamber 221.

FIG. 4 shows an example in which the inkjet head (single bit) shown in FIG. 3 is integrated.
[Pressure chamber substrate]
As the pressure chamber substrate 220, it is preferable to use a silicon single crystal substrate, and it is preferable to have a thickness of 100 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. 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. In this case, however, SiO2 as a mask material is also etched, and this area is also used with attention.
[Diaphragm]
As shown in FIG. 3, the substrate 230 that is a vibration plate receives the force generated by the electro-mechanical conversion film 243, and the substrate 230 that is the base is deformed and displaced, thereby ejecting ink droplets in the pressure chamber 221. Therefore, it is preferable that the base has a predetermined strength.

  Examples of the material include Si, SiO2, and Si3N4 produced by a CVD (chemical vapor deposition) method. Furthermore, it is preferable to select a material close to the linear expansion coefficient of the lower electrode 300 and the electromechanical conversion film 243 as shown in FIG. In particular, as the electromechanical conversion film 243, since PZT is generally used as a material, the linear expansion coefficient close to 8 × 10 ^ -6 (1 / K) is 5 × 10 ^ -6. A material having a linear expansion coefficient of ˜10 × 10 ^ −6 is preferable, and a material having a linear expansion coefficient of 7 × 10 ^ −6 to 9 × 10 ^ −6 is more preferable.

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 it is smaller than this range, the processing of the pressure chamber as shown in FIG. 1 becomes difficult, and if it is larger than this range, the base becomes difficult to be deformed and displaced, and ink droplet ejection becomes unstable.
[First adhesion layer]
As the first adhesion layer 232, after Ti is formed by sputtering, a titanium film is thermally oxidized in an O 2 atmosphere at 650 to 800 ° C. for 1 to 30 minutes using an RTA (rapid thermal annealing) apparatus (rapid heat treatment apparatus). Then, the titanium film is changed to a titanium oxide film. To form the titanium oxide film, reactive sputtering may be used, but thermal oxidation of the titanium film at a high temperature is desirable. The production by reactive sputtering requires a special sputtering chamber configuration because the silicon substrate needs to be heated at a high temperature. Furthermore, the crystallinity of the titanium O2 film becomes better in the oxidation by the RTA apparatus than in the oxidation by a general furnace. This is because, according to oxidation in a normal heating furnace, a titanium film that is easily oxidized forms several crystal structures at a low temperature, and thus it is necessary to break it once. Therefore, oxidation by RTA (rapid heat treatment) with a high temperature rise rate is advantageous for forming a better crystal. As materials other than Ti, materials such as Ta, Ir, and Ru are also preferable.

  The film thickness is preferably 10 nm to 50 nm, and more preferably 15 nm to 30 nm. If it is below this range, there is a concern about the adhesion, and if it exceeds this range, the crystal quality of the electrode film produced thereon will be affected.

As the first and fifth electrodes 233 and 245, platinum having high heat resistance and low reactivity has been conventionally used as a metal material, but although it has sufficient barrier properties against lead. In some cases, platinum group elements such as iridium and platinum-rhodium, and these alloy films are also included. In addition, when platinum is used, it is preferable that the previous adhesion layer is laminated first because adhesion to the base (particularly SiO2) is poor. As a manufacturing method, vacuum film formation such as sputtering or vacuum deposition is generally used. The film thickness of the first and fourth electrodes is preferably 0.05 to 1 μm, and more preferably 0.1 to 0.5 μm.
[Second adhesion layer]
As the second adhesion layer 235, it is desirable to produce Ti by sputtering. At this time, it is important that after the Ti film is formed, the next third electrode 236 is continuously formed without breaking the vacuum, and the third electrode 236 is manufactured with the substrate heated at 500 ° C. or more. is there. This is because the crystal quality of the electro-mechanical conversion film 243 produced after this can be further improved, and this is very effective for displacement deterioration after continuous driving as a piezoelectric actuator.

The film thickness is preferably 1 nm to 20 nm, and more preferably 5 nm to 15 nm. If this range is exceeded, the crystal quality of the electro-conversion film will be affected.
[Second, third and fourth electrodes]
As the second, third, and fourth electrodes 234, 236, and 244, SrRuO3 (SRO) is used as a material. In addition to the left, Srx (A) (1-x) Ruy (1-y), A = Ba, Ca, B = Co, Ni, x, y = 0 to 0.5 Also mentioned. The film forming method is produced by sputtering. The film quality of the SrRuO3 thin film varies depending on the sputtering conditions. In particular, in order to place the SrRuO3 film in the (111) orientation following the Pt (111) of the first electrode with particular emphasis on the crystal orientation, the film forming temperature is set to 500 ° C. It is preferable to perform film formation by performing the above substrate heating.

  For example, SRO film formation conditions are described in Japanese Patent No. 3249696. The outline will be described below.

  After film formation at room temperature, thermal acidification was performed at the crystallization temperature (650 ° C.) by RTA treatment. In this case, the SRO film is sufficiently crystallized and a sufficient value is obtained as the specific resistance as an electrode. However, as the crystal orientation of the film, (110) is easily preferentially oriented, and the film is formed thereon. The PZT (lead zirconate titanate) film is also easily (110) oriented.

  Regarding SRO crystallinity produced on Pt (111), the lattice constants of Pt and SRO are close to each other. Therefore, in the usual θ-2θ measurement, the 2θ positions of SRO (111) and Pt (111) are overlapped. difficult. With respect to Pt, diffraction lines cancel each other at a position where 2θ tilted by Psi = 35 ° is about 32 ° due to the disappearance rule, and no diffraction intensity is observed. Therefore, it is possible to confirm whether the SRO is preferentially oriented to (111) by inclining the Psi (tilt angle) direction by about 35 ° and judging from the peak intensity where 2θ is about 32 °. FIG. 5 shows data when 2θ = 32 ° is fixed and Psi is shaken. When Psi = 0 °, almost no diffraction intensity is observed with SRO (110), but near Psi = 35 °, diffraction intensity is observed. I was able to confirm.

    Further, when the surface roughness of the SRO film is observed, the film formation temperature is affected, and the surface roughness is very small from room temperature to 300 ° C. and becomes 2 nm or less. As for the roughness, the surface roughness (average roughness) measured by AFM is used as an index. Although the surface roughness is very flat, the crystallinity is not sufficient, and sufficient characteristics cannot be obtained with respect to initial displacement as a piezoelectric actuator of PZT formed thereafter and displacement deterioration after continuous driving. . The surface roughness is preferably 4 nm to 15 nm, and more preferably 6 nm to 10 nm. If this range is exceeded, the dielectric breakdown voltage of the PZT deposited thereafter is very poor and leaks easily. Therefore, in order to obtain crystallinity and surface roughness as described above, the film formation is performed at a film formation temperature in the range of 500 ° C. to 700 ° C., preferably 520 ° C. to 600 ° C.

  Regarding the composition ratio of Sr and Ru 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.

  The third electrode 236 is formed under the same sputtering conditions as those of the second electrode 234 after the second adhesive layer 235 is formed. At this time, the total film thickness of the SRO film of the second electrode 234 and the third electrode 236 is preferably 40 nm to 150 nm, and more preferably 50 nm to 80 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 this range is exceeded, the dielectric breakdown voltage of the PZT deposited thereafter is very poor and leaks easily. The thicknesses of the second electrode 234 and the third electrode 236 are preferably substantially the same, and the difference between the thicknesses is preferably within ± 10 nm. If the thickness is out of this range, the optimum value of the film thickness of the second adhesion layer 235 is shifted, so that the quality of the electro-mechanical conversion film produced thereafter is affected and sufficient characteristics cannot be obtained.

The film thickness of the SRO film as the fourth electrode 244 is preferably 40 nm to 80 nm, and more preferably 50 nm to 60 nm. If it is thinner than this film thickness range, sufficient characteristics cannot be obtained for the initial displacement and displacement deterioration characteristics. If this range is exceeded, the dielectric breakdown voltage of the PZT deposited thereafter is very poor and leaks easily.
[Electro-mechanical conversion membrane]
PZT was mainly used as the electromechanical conversion film 243. PZT is a solid solution of lead zirconate (PbTiO3) and titanic acid (PbTiO3), and the characteristics differ depending on the ratio. In general, the composition showing excellent piezoelectric properties is a ratio of PbZrO3 and PbTiO3 of 53:47, and it is expressed as Pb (Zr0.53, Ti0.47) O3 and general PTZ (53/47) in chemical formula. . Examples of composite oxides other than PTZ 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.

  These materials are described by the general formula ABO3, and correspond to composite oxides containing A = Pb, Ba, Sr B = Ti, Zr, Sn, Ni, Zn, Mg, and Nb as main components. The specific description is (Pb1-x, Ba) (Zr, Ti) O3, (Pb1-x, Sr) (Zr, Ti) O3, which is obtained by partially replacing Pb at the A site with Ba or Sr. It is. 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 manufacturing method, it can be manufactured 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 obtained on the entire surface of the base substrate, it is obtained 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. Since 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.

  The film thickness of the electromechanical conversion film 243 is preferably 0.5 to 5 μm, more preferably 1 μm to 2 μm. If it is smaller than this range, it will not be possible to generate a sufficient displacement, and if it is larger than this range, many layers will be laminated, resulting in an increase in the number of steps and a longer process time.

FIG. 6 shows XRD after a film of 1 μm is formed on the second electrode 234 by spin coating using a solution in which PZT is manufactured by the Sol-gel method. For example, when compared with the presence or absence of the second adhesion layer 235 when viewed with the configuration shown in FIG. 3, the quality of the crystal can be further improved when the second adhesion layer 235 is inserted. I understand that
[How to make]
Next, an example of a method for producing the electromechanical conversion element 500 will be described.
<Example 1>
First, a thermal oxide film (film thickness: 1 micron) is formed on a silicon wafer, and a titanium film (film thickness: 30 nm) is formed as a first adhesion layer 232 by a sputtering apparatus, and then RTA is used at 750 ° C. Thermal oxidation is performed, and subsequently a platinum film (thickness 150 nm) as the first electrode 233, a SrRuO film (thickness 30 nm) as the second electrode 234, a titanium film (thickness 10 nm) as the second adhesion layer 235, the first As the third electrode 236, a SrRuO film (thickness 30 nm) was formed by sputtering.

  The substrate was heated at 550 ° C. during the sputtering film formation. Next, the following two types of solutions were prepared as the electromechanical conversion film 243, and a laminated film as shown in FIG. 7 was produced.

PZT (1) (Pb: Zr: Ti = 110: 53: 47)
PZT (2) (Pb: Zr: Ti = 120: 53: 47)
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-liter. Using this solution, a film was formed by spin coating, and after film formation, drying at 120 ° C. → thermal decomposition at 500 ° C. was performed. As shown in FIG. 7, the PZT (1) solution was used for the first and second layers, and the PZT (2) solution was used for the third layer. After thermal decomposition treatment of the third layer, crystallization heat treatment (temperature: 750 ° C.) was performed by RTA (rapid heat treatment). At this time, the film thickness of PZT was 240 nm. This process was performed a total of 8 times (24 layers) to obtain a PZT film thickness of about 2 μm.

  Next, an SrRuO film (film thickness 40 nm) was formed as the fourth electrode 244 by sputtering, and a Pt film (film thickness 125 nm) was formed as the fifth electrode 245 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 1008, a parylene film (film thickness: 2 μm) was formed by CVD. Thereafter, a photoresist made by Tokyo Ohka Co., Ltd. (TSMR8800) is formed by spin coating, a resist pattern is formed by ordinary photolithography, and then RIE.
The pattern shown in FIG. 8 was produced using (made by Samco).

Finally, an Al film (film thickness 5 μm) was formed by sputtering as the fifth and sixth electrodes 245 and 1009. Thereafter, a photoresist made by Tokyo Ohka Co., Ltd. (TSMR8800) is formed by spin coating, a resist pattern is formed by ordinary photolithography, and then the RIE (manufactured by Samco) is used as shown in FIGS. Such a pattern was produced, and a droplet discharge head 1000 was produced. Reference numerals 1009 and 1010 denote sixth and seventh electrode terminals.
<Example 2>
A droplet discharge head 1000 as shown in FIGS. 8A and 8B was produced in the same manner as in Example 1 except that the SrRuO film (film thickness 70 nm) was used as the second electrode 234 and the third electrode 236. .
<Example 3>
A droplet discharge head 1000 as shown in FIGS. 8A and 8B was produced in the same manner as in Example 1 except that the SrRuO film (film thickness 25 nm) was used as the second electrode 234 and the third electrode 236. .
<Example 4>
A droplet discharge head 1000 as shown in FIG. 8 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 235.
<Example 5>
A droplet discharge head 1000 as shown in FIG. 8 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 1>
A droplet discharge head 1100 as shown in FIGS. 9A and 9B was produced in the same manner as in Example 1 except that the second adhesion layer 235 was not provided.
<Comparative example 2>
A droplet discharge head 1100 as shown in FIGS. 9A and 9B was produced in the same manner as in Example 1 except that the SrRuO film (film thickness 85 nm) was used as the second electrode 234 and the third electrode 236. .
<Comparative Example 3>
A droplet discharge head 1100 as shown in FIGS. 9A and 9B was produced in the same manner as in Example 1 except that a titanium film (thickness 30 nm) was used as the second adhesion layer 235.
<Comparative example 4>
A droplet discharge head 1100 as shown in FIGS. 9A and 9B was manufactured in the same manner as in Example 1 except that a titanium film (film thickness: 0.5 nm) was used as the second adhesion layer 235.
<Comparative Example 5>
A droplet discharge head 1100 as shown in FIGS. 9A and 9B was produced in the same manner as in Example 1 except that SrRuO films (thickness 15 nm) were used as the second electrode 234 and the third electrode 236. .
<Comparative Example 6>
After forming a titanium film (film thickness: 10 nm) as the second adhesion layer 235 and a titanium film (film thickness: 30 nm) as the first adhesion layer 232 using a sputtering apparatus, the RTA treatment is not performed continuously. A droplet discharge head 1000 as shown in FIG. 9 is formed in the same manner as in Example 1 except that a platinum film (thickness 150 nm) is used as the first electrode and a SrRuO film (thickness 60 nm) is formed as the second electrode 234 by sputtering. Produced.

  The droplet ejection heads produced in Examples 1 to 5 and Comparative Examples 1 to 6 were evaluated for electrical characteristics and electro-mechanical conversion ability (piezoelectric constant). A typical PE hysteresis curve is shown in FIG. The electro-mechanical conversion ability was calculated by measuring the amount of deformation by applying an electric field (150 kV / cm) with a laser Doppler vibrometer and fitting by simulation. After evaluating the initial characteristics, durability (characteristics immediately after applying the applied voltage 10 ^ 10 times) was evaluated. These detailed results are summarized in Table 1 of FIG.

  In Examples 1 to 5 and Comparative Examples 1 to 6, the initial characteristics and the results after the durability test were the same as those of a general ceramic sintered body (residual polarization Pr: 20 to 27 uC-cm2, The piezoelectric constant is -120 to -140 pm-V).

  On the other hand, Comparative Examples 1 to 6 are slightly inferior to the general ceramic sintered body in terms of initial characteristics. Further, in the characteristics after 1010 times (immediately after applying the applied voltage repeatedly 1010 times), it was confirmed that both the residual polarization and the piezoelectric constant were greatly deteriorated as compared with Examples 1-5.

That is, the droplet discharge head 1000 according to the first to fifth embodiments including the electro-mechanical conversion element 500 shown in FIG. 3 does not deteriorate in piezoelectric characteristics as the number of repeated electric field applications increases, and is reliable. It can be seen from the display 1 in FIG. That is, the reliability of the electromechanical conversion element 500 can be improved.
[Inkjet recording apparatus]
1 and 2 show an ink jet recording apparatus 80 which is a droplet discharge apparatus equipped with a recording head 94 having the electro-mechanical conversion element 500 shown in FIG.

  The ink jet recording apparatus 80 includes a printing mechanism unit 82 provided inside the apparatus main body 81. The printing mechanism section 82 includes a carriage 93 that can move in the main scanning direction, a recording head (printer head) 94 that is an ink jet head (droplet discharge head) mounted on the carriage 93, and ink to the recording head 94. An ink cartridge 95 to be supplied is included.

  A paper feed cassette (or a paper feed tray) 84 on which a large number of sheets 83 can be stacked from the front side is detachably attached to the lower portion of the apparatus main body 81. In addition, a manual feed tray 85 for manually feeding the paper 83 is attached to the front portion of the apparatus main body 81 so that the paper 83 can be turned over.

  The paper 83 fed from the paper feed cassette 84 or the manual feed tray 85 is taken into the apparatus main body 81, and after a required image is recorded by the printing mechanism unit 82, the paper 83 is discharged to the paper discharge tray 86 mounted on the rear side. It has come to be.

  The printing mechanism 82 is slidably held in the main scanning direction by the main guide rod 91 and the sub guide rod 92 which are guide members horizontally mounted on left and right side plates (not shown), and the main guide rod 91 and the sub guide rod 92. The carriage 93 is provided. A plurality of recording heads 94 that are ink jet heads that eject ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk) are mounted on the carriage 93. Has ink discharge ports (nozzles) arranged in a direction crossing the main scanning direction, and the ink droplet discharge direction is directed downward.

  In addition, ink cartridges 95 for supplying inks of the respective colors to the recording heads 94 are mounted on the carriage 93 in a replaceable manner.

  The ink cartridge 95 has an atmosphere port (not shown) communicating with the atmosphere at the upper side and a supply port (not shown) for supplying ink to the recording head 94 at the lower side, and the inside is filled with ink. A porous body is provided, and the ink supplied to the recording head 94 is maintained at a slight negative pressure by the capillary force of the porous body.

  Here, the recording head 94 of each color is used as the recording head, but a single head having nozzles for ejecting ink droplets of each color may be used.

  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 fixed to the carriage 93. ing. Then, 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 recording 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 are guided. The guide member 103 to be transported, the transport roller 104 that reverses and transports the fed paper 83, the transport roller 105 that is pressed against the peripheral surface of the transport roller 104, and the feed angle of the paper 83 from the transport roller 104 are defined. A tip roller 106 is provided on the apparatus main body 81.

  The transport roller 104 is rotationally driven by a sub-scanning motor 107 via a gear train (not shown).

  A printing receiving member 109 is provided as a paper guide member that guides the paper 83 sent from the transport roller 104 below the recording 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.

  At the time of recording, the recording head 94 is driven according to the image signal while moving the carriage 93, thereby ejecting ink onto the stopped sheet 83 to record one line. Record the line. 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 recording 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. The carriage 93 is moved to the recovery device 117 side during printing standby, and the recording head 94 is capped by the capping unit, 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 recording head 94 is sealed by the capping unit, and bubbles and the like are sucked out together with the ink from the discharge port by the suction unit through the tube. Etc. 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.

  Since the ink jet recording apparatus 80 includes the recording head 94 using the electro-mechanical conversion element 500, the piezoelectric characteristics do not deteriorate as the number of times of repeated electric field application increases. By use, there is no ink droplet ejection failure due to vibration plate drive failure, stable ink droplet ejection characteristics are obtained, and image quality is improved.

  The printer head 94, which is an ink jet head (droplet discharge head) equipped with the electro-mechanical conversion element 500, and the ink jet recording apparatus 80, which is a droplet discharge device, maintain good ink discharge characteristics over a long period of time. Therefore, stable ink discharge characteristics can be obtained even when ink is continuously discharged.

  In the above embodiment, the film formation vibration plate 231 is formed on the substrate 230, but the film formation vibration plate 231 is not necessarily formed.

  The present invention is not limited to the above-described embodiments, and design changes and additions are permitted without departing from the scope of the claimed invention.

80 Inkjet recording device (droplet discharge device)
94 Recording Head (Droplet Discharge Head)
230 Substrate (base: diaphragm)
231 Film formation diaphragm (underlayer)
232 First adhesion layer 233 First electrode 234 Second electrode 235 Second adhesion layer 236 Third electrode 243 Electro-mechanical conversion film 244 Fourth electrode 245 Fifth electrode 300 Lower electrode 400 Upper electrode 500 Electro-mechanical transducer

JP 2009-54934 A

Claims (9)

A substrate or a base film, a lower electrode formed on the substrate or the base film via a first adhesion layer, an electromechanical conversion film formed on the lower electrode, and the electromechanical conversion film An electro-mechanical conversion element comprising an upper electrode formed on
The lower electrode is formed on the first adhesion layer and is made of a first electrode made of a metal film, a second electrode made of an oxide formed on the first electrode, and the second electrode. A second adhesion layer formed on the electrode, and a third electrode formed on the second adhesion layer,
The upper electrode includes a fourth electrode made of an oxide formed on the electro-mechanical conversion film, and a fifth electrode made of a metal formed on the fourth electrode. An electromechanical conversion element.   2. The electromechanical transducer according to claim 1, wherein the second electrode and the third electrode are made of strontium ruthenate.   The electro-mechanical transducer according to claim 1 or 2, wherein the total thickness of the second electrode and the third electrode is 40 nm or more and 150 nm or less.   The electro-mechanical conversion according to any one of claims 1 to 3, wherein the second adhesion layer is a titanium film and has a film thickness of 1 nm or more and 20 nm or less. element.   5. The electromechanical conversion element according to claim 1, wherein the first adhesion layer has a thickness of 10 nm or more and 50 nm or less.   6. The first adhesion layer according to claim 1, wherein the first adhesion layer is formed by forming a titanium film on the insulating film, and thereafter, rapidly heating and thermally oxidizing the titanium film. The electromechanical conversion element according to any one of the above.   7. The electromechanical transducer according to claim 1, wherein the first electrode is made of platinum and has a film thickness of 80 nm or more and 200 nm or less. In a droplet discharge head comprising a nozzle that discharges a droplet, a pressure chamber that communicates with the nozzle, and a discharge driving means that pressurizes the liquid in the pressure chamber.
The discharge driving means comprises a part of a wall of the pressurizing chamber as a diaphragm, and the electromechanical conversion element according to any one of claims 1 to 7 is provided on the diaphragm. A droplet discharge head characterized by being a thing.   A droplet discharge apparatus comprising the droplet discharge head according to claim 8.