JP6051713B2 - Method for manufacturing electromechanical transducer - Google Patents

Description

The present invention relates to a process for the production of electrical mechanical conversion element.

  Devices such as a vibration sensor, a piezoelectric speaker, and various driving devices include an electromechanical conversion element in which electromechanical conversion films are stacked. In a driving device, for example, a liquid discharge head of an ink jet recording apparatus includes a nozzle that discharges ink droplets, a liquid chamber that communicates with the nozzle, and an electromechanical conversion element such as a piezoelectric element. By applying pressure, ink droplets are ejected from the nozzles.

  In recent years, various technical proposals relating to an electromechanical transducer in which a first electrode, an electromechanical transducer film, and a second electrode are laminated have been made for the purpose of obtaining more efficient vibration and deformation displacement. For example, Patent Document 1 discloses an electromechanical conversion element in which strontium ruthenate is used as a first electrode and an electromechanical conversion film is formed in a desired pattern on the first electrode.

  However, in the electromechanical conversion element described in Patent Document 1, it is difficult to pattern the electromechanical conversion film on the first electrode, the pattern shape is not stable, and the film thickness is not uniform. For this reason, the electromechanical conversion characteristics of the electromechanical conversion element are insufficient.

  Then, an object of this invention is to provide the electromechanical conversion element excellent in an electromechanical conversion characteristic.

A first electrode having a metal layer formed on the ground and a conductive oxide layer formed on a part of the metal layer;
An electromechanical conversion film formed on the conductive oxide layer;
A second electrode formed on at least a part of the electromechanical conversion film, and a method for producing an electromechanical conversion element having at least a laminated structure,
Laminating a metal layer and a conductive oxide layer on the ground;
Applying a resist composition on the conductive oxide layer to form a resist film;
Exposing and developing the resist film and patterning;
Using the patterned resist film as a mask, the height of the region of the first electrode not covered with the resist film from the base and the base of the interface between the metal layer and the conductive oxide layer A step of dry etching so that the difference between the height and the height is 5 nm or less;
Surface modifying the region to be hydrophobic;
Applying a sol-gel solution containing a precursor of the electromechanical conversion film to an unsurface-modified region on the first electrode by an inkjet method;
And a step of heat-treating the applied the sol-gel solution, the method of manufacturing an electro-mechanical conversion element is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the electromechanical conversion element excellent in an electromechanical conversion characteristic can be provided.

FIG. 1 is a schematic diagram showing an example of the structure of the droplet discharge head of this embodiment. FIG. 2 is a schematic view for explaining the method for manufacturing the electromechanical transducer according to this embodiment. FIG. 3 is an enlarged schematic view for explaining the relationship between h1 and h2 in FIG. FIG. 4 is a schematic view for explaining the effect of the method for manufacturing the electromechanical transducer according to this embodiment. FIG. 5 is an example of a PE hysteresis curve of the electromechanical transducer according to this embodiment. FIG. 6 is a schematic view for explaining the ink jet recording apparatus of the present embodiment. FIG. 7 is another schematic diagram for explaining the ink jet recording apparatus of the present embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment and each example, components such as members and components having the same function or shape are given the same reference numerals as much as possible to avoid duplicate explanation. In addition, the content described in embodiment is only one form, and the scope of the present invention is not limited to this.

  In this embodiment, the “image forming apparatus” of the liquid discharge recording method forms an image by landing droplets on a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. The “image formation” means not only that an image having a meaning such as a character or a figure is imparted to the medium, but also an image having no meaning such as a pattern is imparted to the medium ( It also simply means that a droplet is landed on a medium).

  Furthermore, in the present embodiment, the “droplet” is not limited to what is referred to as ink, but includes what is referred to as recording liquid, fixing processing liquid, resin, liquid, and the like, and image formation can be performed. It is used as a generic term for all liquid droplets that can be made into fine droplets. The term “recording medium” does not limit the material to paper, but also includes OHP sheets, cloth, etc., and means that the droplets adhere to it, and can be used as a recording medium, recording paper, recording paper, etc. It is used as a general term for anything from what is called thin paper to thick paper, postcard, envelope, or simply paper. Further, the image is not limited to a two-dimensional image, and includes a three-dimensional image.

  The present embodiment includes a droplet discharge head including an electromechanical conversion element and an image forming apparatus including the droplet discharge head as targets. The above-described image forming apparatus is generally called an ink jet recording apparatus. Note that specific configuration examples of the droplet discharge head and the image forming apparatus will be described in detail in an embodiment described later.

  The ink jet recording apparatus has many advantages such as low noise, high-speed printing, and the use of plain paper, which is an inexpensive recording medium with a high degree of ink freedom. Therefore, it is widely used as an image recording apparatus or an image forming apparatus such as a multi-function machine having a plurality of image forming functions such as a printer, a facsimile, a copying apparatus, and a plotter.

  A droplet discharge device used in an inkjet recording apparatus includes a nozzle that discharges ink droplets, a liquid chamber (also referred to as a discharge chamber, a pressure chamber, a pressure chamber, an ink flow path, and the like) that communicates with the nozzle, a liquid Pressure generating means for discharging the ink in the chamber.

  In this embodiment, the pressure generating means is a piezo type that discharges ink droplets by deforming a diaphragm that forms the wall surface of the liquid chamber using an electromechanical transducer such as a piezoelectric element. In the present embodiment, the piezoelectric pressure generating means includes a lateral vibration (bend mode) type utilizing deformation in the d31 direction.

(Droplet ejection head)
An embodiment in which the electromechanical conversion element of this embodiment is applied to a droplet discharge head will be described.

  FIG. 1 is a schematic diagram showing an example of the structure of the droplet discharge head of this embodiment.

  As shown in FIG. 1A, the liquid droplet ejection head 10 in this embodiment includes a nozzle plate 12 in which nozzle holes 11 for ejecting liquid droplets (for example, ink droplets) are formed, and a liquid in which the nozzle holes 11 communicate with each other. A chamber 21 (also referred to as an ink flow path, a pressurized liquid chamber, a pressurized chamber, a discharge chamber, a pressure chamber, etc.), an electromechanical transducer 40 that pressurizes a droplet in the pressurized chamber, and a wall surface of the ink flow path And a diaphragm 30 that forms

  In the present embodiment, the electromechanical transducer 40 includes a first electrode 44 formed of a metal layer 42 and a conductive metal layer 43 formed on a part of the metal layer 42, and the conductive metal layer. And an electromechanical conversion film 45 formed on the electrode 43 and a second electrode 46 formed on at least a part of the electromechanical conversion film 45. The liquid chamber 21 is formed by the nozzle plate 12, the liquid chamber substrate 20, and the vibration plate 30.

  The electromechanical conversion element 40 is disposed on the side facing the nozzle plate 12, and deforms and displaces the vibration plate 30 that forms the wall surface of the liquid chamber 21, thereby discharging the liquid droplets in the liquid chamber 21 from the nozzle holes 11. This is a piezo-type electromechanical transducer. The electromechanical transducer 40 is deformed and displaced when a voltage is applied between the first electrode 44 and the second electrode 46.

Further, in order to improve the first electrode 44 the adhesion between the vibrating plate 30, on the vibrating plate 30 is, for _{example, Ti, TiO 2, TiN,} Ta, Ta 2 O 5, Ta 3 N 5 , etc. The adhesion layer 41 may be provided.

  In the present embodiment, the height h1 of the region of the first electrode 44 that is not covered with the electromechanical conversion film 45 from the base, and the base of the interface between the metal layer and the conductive oxide layer. The difference from the height h2 is preferably within 5 nm.

  FIG. 1B and FIG. 1C are diagrams for explaining the relationship between h1 and h2 in more detail in the droplet discharge head of this embodiment. In the example of FIG. 1B, the height h <b> 1 from the adhesion layer 41 in the region that is not covered with the electromechanical conversion film 45 in the first electrode 44 is the difference between the metal layer 42 and the conductive oxide layer 43. It is larger than the height h2 from the adhesion layer 41 at the interface. In this case, h1-h2 is configured to be within 5 nm. On the other hand, in the example of FIG. 1C, the height h <b> 2 from the adhesion layer 41 at the interface between the metal layer 42 and the conductive oxide layer 43 is covered with the electromechanical conversion film 45 in the first electrode 44. It is larger than the height h1 from the adhesion layer 41 in the unexposed region. In this case, h2-h1 is configured to be within 5 nm. That is, in the present embodiment, the absolute value of the difference between h1 and h2 is configured to be within 5 nm. By setting the absolute value of the difference between h1 and h2 within 5 nm, the contact angle contrast between the hydrophobic region and the hydrophilic region with respect to pure water can be sufficiently increased in the substrate surface modification described later.

  FIG. 1 describes an example in which the electromechanical conversion element of this embodiment is applied to a droplet discharge head, but the present invention is not limited in this respect. The electromechanical transducer of this embodiment may be used in applications such as a micropump, an ultrasonic motor, an acceleration sensor, a projector biaxial scanner, an infusion pump, and the like.

(Electromechanical conversion membrane)
In this embodiment, PZT is mainly used as the material of the electromechanical conversion film 45. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTiO ₃ ). For example, the ratio of PbZrO ₃ and PbTiO ₃ is 54:47, and the chemical formula indicates Pb (Zr _0.54 , Ti _0.47 ) O ₃ , PZT generally indicated as PZT (54/47), etc. Can be used. The characteristics of PZT vary depending on the ratio of PbZrO ₃ and PbTiO ₃ .

When PZT is used as the electromechanical conversion film, lead acetate, a zirconium alkoxide compound, and a titanium alkoxide compound are used as starting materials, and dissolved in methoxyethanol as a common solvent to prepare a PZT precursor solution. The mixing amount of the lead acetate, zirconium alkoxide compound, and titanium alkoxide compound can be appropriately selected by those skilled in the art depending on the desired composition of PZT (ratio of PbZrO ₃ and PbTiO ₃ ).

  Note that the metal alkoxide compound is easily decomposed by moisture in the atmosphere. Therefore, stabilizers such as acetylacetone, acetic acid and diethanolamine may be added to the PZT precursor solution as stabilizers.

Examples of composite oxides other than PZT include barium titanate. In this case, it is also possible to prepare a barium titanate precursor solution by dissolving barium alkoxide and a titanium alkoxide compound in a common solvent. is there. These materials are described by the general formula ABO ₃ 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 expressed as (Pb _1-x , Ba) (Zr, Ti) O ₃ , (Pb _1-x , Sr) (Zr, Ti) O ₃ , which is the same as Pb of the A site. This is a case where the part Ba or Sr is substituted. 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.

  A method for forming (depositing) the electromechanical conversion film 45 will be described later.

[First electrode]
In the present embodiment, the first electrode may have a structure in which a metal layer and a conductive metal layer formed on a part of the metal layer are stacked.

  The metal used in the metal layer is not particularly limited as long as a SAM (Self Assembled Monolayer) film can be formed by reaction with alkanethiol described later. For example, ruthenium (Ru), rhodium (Rh), palladium (Pd ), Osmium (Os), iridium (Ir), platinum (Pt), platinum group metals, gold (Au), silver (Ag), copper (Cu), and alloy materials containing these metals Can be used.

The conductive metal layer is, for example, described by the chemical formula ABO ₃ , a composite oxide mainly composed of A = Sr, Ba, Ca, La, B = Ru, Co, Ni, SrRuO ₃ or CaRuO _3. In addition to (Sr _1-x Ca _x ) O ₃ which is a solid solution thereof, LaNiO ₃ and SrCoO ₃ , and further, (La, Sr) (Ni _1-y Co _y ) O ₃ (y = 1 is also acceptable). Other oxide materials include IrO ₂ and RuO ₂ .

[Second electrode]
Further, as the material of the second electrode, a material such as a metal having high heat resistance similar to that of the first electrode can be used. The second electrode can be manufactured by a method such as a sputtering method or a vacuum film formation method such as vacuum deposition.

[Diaphragm]
Since the first electrode is electrically connected as a common electrode for inputting a signal to the electromechanical transducer, the diaphragm under the first electrode can be an insulator or a conductor subjected to insulation treatment.

  As a specific material of the diaphragm, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a film in which these films are stacked having a thickness of about several microns can be used. In addition, a ceramic film such as an aluminum oxide film or a zirconia film in consideration of a difference in thermal expansion can also be used.

  As a method for forming the diaphragm, for example, the silicon-based insulating film can be obtained by CVD or thermal oxidation treatment of the silicon-based film. The metal oxide film can be formed by a sputtering method or the like.

(Method for manufacturing electromechanical transducer)
A method for manufacturing the electromechanical transducer according to this embodiment will be described with reference to the drawings.

The method of manufacturing the electromechanical transducer in the present embodiment is as follows:
Laminating a metal layer and a conductive oxide layer on the ground;
Applying a resist composition on the conductive oxide layer to form a resist film;
Exposing and developing the resist film and patterning,
Using the patterned resist film as a mask, the difference between the height of the region of the first electrode not covered with the resist film from the base and the height of the interface between the metal layer and the conductive oxide layer from the base A step of dry etching so that the thickness is within 5 nm,
A step of surface-modifying the region to be hydrophobic;
A step of applying a sol-gel solution containing a precursor of an electromechanical conversion film to an unsurface-modified region on the first electrode by an inkjet method;
Heat-treating the applied sol-gel solution;
including.

  FIG. 2 is a schematic view for explaining the method for manufacturing the electromechanical transducer according to this embodiment. As shown in FIG. 2A, a stacked structure of a metal layer 42 and a conductive oxide layer 43 is formed on the base 50 as the first electrode 44. In order to obtain good crystallinity, the metal layer 42 and the conductive oxide 43 layer can usually be formed by a method such as sputtering or vapor deposition while heating the base 50.

  Next, as shown in FIG. 2B, a photoresist 51 is applied on the conductive oxide layer 43. The photoresist 51 is exposed and developed using a known photolithography method, patterned, and the conductive oxide 43 layer is dry-etched using the patterned photoresist 51 as a mask, as shown in FIG. Thus, the first electrode 44 is patterned. At this time, the difference between the height h1 of the region of the first electrode 44 not covered with the photoresist 51 and the height h2 of the interface between the metal layer 42 and the conductive oxide layer 43 is within 5 nm. Then, dry etching is performed.

  FIG. 3 shows an enlarged schematic diagram for explaining the relationship between h1 and h2 in FIG. In dry etching of the conductive oxide 43, as shown in FIG. 3A, the height h1 of the region not covered with the photoresist 51 from the base 50 is such that the metal layer 42, the conductive oxide layer 43, Etching may be performed so as to be larger than the height h2 of the interface from the base 50 (see Example 1 in Table 1). Further, as shown in FIG. 3B, the height h2 of the interface between the metal layer 42 and the conductive oxide layer 43 from the base 50 is the height from the base 50 in the region not covered with the photoresist 51. The conductive oxide 43 may be dry-etched so as to be larger than h1 (see Example 3 in Table 1). However, in either embodiment of FIGS. 3A and 3B, the conductive oxide 43 is dry-etched so that the absolute value of the difference between h1 and h2 is within 5 nm.

  In the vicinity of the interface between the metal layer 42 and the conductive oxide layer 43, the metal elements in each other layer diffuse due to the thermal history of the base 50 when forming the first electrode 44. In this embodiment, in this state, the conductive oxide 43 layer is etched to the vicinity of the interface with the metal layer 42 using the patterned photoresist 51 as a mask. Therefore, as shown in FIG. 2C, the surface 50 of the base 50 includes a region A where the conductive oxide 43 is exposed and a region B where the metal layer 42 and the conductive oxide 43 are exposed. It is formed. When the amount of dry etching described above is small, the exposed ratio of the metal layer 42 in the region B becomes small, and it becomes difficult to form a SAM film described later. On the other hand, when the amount of dry etching described above is large, the exposed ratio of the metal layer 42 in the region B is increased, and SAM film formation described later is facilitated. However, the metal layer 42 has a higher selectivity in dry etching than the conductive oxide layer 43. Therefore, for example, when the second electrode is formed and patterned, the first electrode film in the region B may disappear due to excessive etching, and the element resistance may increase. In this case, it is possible to cope by increasing the film thickness of the metal layer 42 of the first electrode or changing the dry etching conditions during the process, but the manufacturing cost increases and the process is complicated. become.

  Thereafter, as shown in FIG. 2D, the photoresist 51 which is present on the conductive oxide layer 43 is removed.

  Next, the base 50 is dipped in a SAM material-containing solution made of alkanethiol or the like, and after a predetermined time, the base 50 is taken out, and the excess molecules are washed by substitution with a solvent and dried. Compared with the surface of the conductive oxide layer 43, the alkanethiol has a property of being easily attached to the surface of the metal layer 42. Therefore, the SAM film 52 can be formed only in the region B as shown in FIG. 2E by appropriately selecting the immersion time in the immersion treatment. Since the SAM material is a material containing an alkyl group, the surface of the region B where the SAM film 52 is formed is water repellent (hydrophobic). On the other hand, the surface (region A) of the conductive oxide layer 43 where the SAM film 52 is not formed becomes hydrophilic. Thereby, the contact angle difference with respect to pure water between the area | region A and the area | region B can be ensured large. By utilizing this surface energy contrast, it becomes possible to separately coat the precursor solution of the electromechanical conversion film described in detail below.

  Alkanethiol differs in reactivity and hydrophobicity (water repellency) depending on the molecular chain length, but a SAM material usually has 6 to 18 carbon atoms. The SAM material is prepared by diluting alkanethiol with a solvent such as alcohols in which the alkanethiol is dissolved and does not cause a chemical reaction. The concentration of alkanethiol is preferably about several millimoles / liter to several moles / liter.

Next, as shown in FIG. 2 (f), an electromechanical conversion film precursor solution (sol-gel solution) 54 is applied onto the hydrophilic region A that has not been surface-modified by the inkjet device 53. Due to the contrast of the surface energy described above, the application region of the precursor solution 54 is only the hydrophilic region A (FIG. 2G). Therefore, since wetting and spreading of the precursor solution 54 can be suppressed, the shape and film thickness of the electromechanical conversion film can be stabilized. By discharging the precursor solution 54 only to the region A of the hydrophilic surface, the amount of the precursor solution 54 to be applied can be reduced as compared with a conventional process such as a spin coating method, and the process can be simplified. Is possible.

  The viscosity, surface tension, and the like of the precursor solution 54 are adjusted according to the ink jet head used so that the precursor solution 54 can be applied by an ink jet method.

  After the precursor solution 54 is applied by the ink jet method, the electromechanical conversion film 45 is formed by heat-treating the precursor solution 54 as shown in FIG. The heat treatment referred to here is a step of drying the solvent component contained in the precursor solution 54, a step of thermally decomposing the dried precursor solution (film), and a crystal of the precursor solution (film) that has been pyrolyzed. And the step of making it. At this time, each process may be performed independently or may be performed continuously.

  It is preferable to apply the precursor solution so that the thickness of the electromechanical conversion film formed by one film formation is about 60 nm to 100 nm. Since the precursor solution has a high shrinkage rate, when the thickness of the electromechanical conversion film formed by one film formation exceeds 100 nm, the formed electromechanical conversion film may be cracked.

  Therefore, in order to obtain a desired film thickness of the electromechanical conversion film, it is necessary to perform application of the precursor solution and heat treatment one or more times. Subsequently, after washing with isopropyl alcohol as a repeated treatment, a SAM film is formed by the same immersion treatment. In the second and subsequent processes, the SAM film is not formed on the electromechanical conversion film, and the above-described photolithography process is unnecessary. Next, alignment is performed on the electromechanical conversion film pattern formed for the first time, and the precursor solution is applied again by the ink jet coating apparatus. Through the same heat treatment as that of the first time, an overcoated electromechanical conversion film is obtained. Thereafter, this process can be repeated a plurality of times until the desired film thickness is obtained.

  In the electromechanical conversion film forming method of the present embodiment, an electromechanical conversion film having a thickness of up to about 5 μm can be generally formed.

  As described above, the present embodiment includes the step of applying the precursor solution containing the precursor of the electromechanical conversion film by the inkjet method. Therefore, the amount of starting material required is small compared with a method of applying by a conventional spin coater, and the process can be simplified.

(First embodiment)
The present invention will now be described in more detail by describing embodiments.

First, a titanium oxide (TiO ₂ ) film having a thickness of 50 nm was formed on the silicon substrate surface as an adhesion layer. Pt and SRO (strontium ruthenate) were sequentially laminated on the TiO ₂ layer as the first electrode. At this time, the film thicknesses of Pt and SRO were 250 nm and 60 nm, respectively.

  The resist composition on the SRO so that the electromechanical transducer is formed every 120 μm in the horizontal direction (pattern width = space width = 60 μm) in a long pattern of 60 μm in the horizontal direction and 1250 μm in the depth direction in FIG. Was coated, exposed and developed. Next, the SRO film was etched by dry etching using the resist film as a mask. After the etching, the photoresist remaining on the pattern was peeled off.

  Table 1 shows the etching amount in each example and each comparative example.

The Pt element concentration in the region B of FIG. 2 in each Example and each Comparative Example was measured by XPS (X-ray photoelectron spectroscopy). The measurement results are also shown in Table 1.

  By etching, the surface of the region B in each Example and each Comparative Example was in a state where the Pt layer and the SRO layer were scattered in spots.

The surface of the substrate was modified by the surface modification process described above. Note that dodecanethiol (CH ₃ (CH ₂ ) ₁₁ —SH) was used as the SAM film, and an ethanol diluted solution having a molar concentration of 0.1 mmol / l was used. Further, the immersion time of the substrate in the alkanethiol solution was 10 seconds, and after the immersion, ultrasonic cleaning was performed in an ethanol bath for about 5 minutes.

  Table 1 shows the contact angles of the regions A and B with respect to pure water in each example and each comparative example. In each Example, the contact angle of pure water in region B was 90 degrees or more, and sufficient hydrophobicity was obtained. In addition, a sufficient contact angle contrast between the region A and the region B could be secured.

  On the other hand, the substrate in each comparative example had a contact angle of pure water in region B of about 60 degrees, and sufficient hydrophobicity and contrast could not be obtained.

  The PZT precursor solution was applied to the patterned hydrophilic region using a known inkjet coating apparatus. As starting materials for the PZT precursor solution, lead acetate trihydrate, isopropoxide titanium and isopropoxide zirconium were used. Crystal water of lead acetate was dissolved in methoxyethanol (boiling point 124 ° C.) and then dehydrated. In addition, the usage-amount of the starting material was adjusted so that lead amount might be 15 mol% excess with respect to a stoichiometric composition. Thereby, the fall of crystallinity by lead omission during heat treatment can be prevented. Isopropoxide titanium and isopropoxide zirconium were dissolved in methoxyethanol, alcohol exchange reaction and esterification reaction were advanced, and mixed with the methoxyethanol solution in which the lead acetate was dissolved to obtain a PZT precursor solution. . Further, diethylene glycol monomethyl ether (boiling point 194.1 ° C.) and 1-nonanol (boiling point 213 ° C.) were added to the synthesized PZT precursor solution. Further, in this embodiment, the concentration of the PZT precursor solution was adjusted to 0.25 mol / liter so that the thickness of the PZT film obtained by one film formation was about 90 nm.

  FIG. 4 is a schematic view for explaining the effect of the method for manufacturing the electromechanical transducer according to this embodiment. More specifically, FIG. 4A shows the state of the substrate after application of the PZT precursor solution in the example, and FIG. 4B shows the state of the substrate after application of the PZT precursor solution in the comparative example. As shown in FIG. 4A, in the substrate of the example, the precursor solution spreads only in the region A where the precursor solution is hydrophilic. On the other hand, as shown in FIG. 4B, the precursor solution protruded from the region A on the substrate of the comparative example.

  The substrate coated with the PZT precursor solution was heated to 300 ° C. at a temperature rising rate of 30 ° C./min by solvent heating by heating the lower surface of the substrate with a hot plate. In addition, the SAM film in the region where the precursor solution was not applied disappeared by this heat treatment. Next, the organic substance was thermally decomposed (about 500 ° C.) to obtain a PZT film. In addition, the film thickness of the obtained PZT precursor coating film was 90 nm.

  As a subsequent treatment, after washing with isopropyl alcohol, a SAM film was formed by the same immersion treatment. At this time, the contact angle with respect to pure water of the SAM film formed on the substrate of the example was 100 degrees or more, and the contact angle with respect to pure water of the PZT precursor coating film was 25 degrees or less.

  Next, alignment is performed on the PZT film formed first, and the PZT precursor solution is applied again by the ink jet coating apparatus, and the PZT film is formed by the same heat treatment as the PZT film formed first. Obtained.

  This process was further repeated 4 times (total 6 times of application and heat treatment of PZT), and rapid heat treatment (RTA) was performed at a temperature of about 750 ° C. to obtain a PZT film. In the obtained PZT film, defects such as cracks did not occur.

  Furthermore, the same crystallization heat treatment as described above was performed by performing six SAM film treatments, selective application of a PZT precursor solution, solvent drying at about 300 ° C. and thermal decomposition at about 500 ° C. No defects such as cracks occurred in the PZT film. Further, six cycles of the SAM film treatment, selective application of the PZT precursor solution, solvent drying at about 300 ° C. and thermal decomposition at about 500 ° C. were performed, and the same crystallization heat treatment cycle was performed twice. The film thicknesses of the electromechanical conversion films obtained in the examples were all 2.4 μm, and the film thickness unevenness was small in the pattern.

  A platinum film was formed by sputtering on the substrate including the obtained electromechanical conversion film, and a second electrode (upper electrode) was formed by photolithography and an etching process to obtain an electromechanical conversion element. Note that in the etching step when forming the second electrode, overetching of the first electrode did not occur in the region B.

  The obtained electromechanical conversion element was evaluated for electric characteristics and electromechanical conversion ability (piezoelectric constant).

  FIG. 5 shows an example of the PE hysteresis curve of the electromechanical transducer obtained in the first embodiment. Table 2 shows the measurement results of the electrical characteristics of the electromechanical transducer obtained in the first embodiment.

Moreover, the residual polarization of the electromechanical transducer of Example 1 was 19.3 μC / cm ² , and the coercive electric field was 34.5 kV / cm. Thereby, it turned out that the electromechanical conversion element obtained by 1st Embodiment has an electrical property equivalent to the conventional ceramic sintered compact.

  The electromechanical conversion ability of the electromechanical conversion element was calculated by measuring the amount of deformation by applying an electric field with a laser Doppler vibrometer and fitting it through simulation. The piezoelectric constant d31 of the electromechanical transducer obtained in the first embodiment was all 135 pm / V or more. This means that the obtained electromechanical transducer has a characteristic value that can be applied as a droplet discharge head.

  As an example, when the above-described steps up to the crystallization treatment were repeated 10 times without disposing the second electrode, a 5 μm PZT film was obtained, and this PZT film had defects such as cracks. It wasn't.

  As described above, in the electromechanical conversion element of the first embodiment, the difference between the height of the region not covered with the electromechanical conversion film and the height of the interface between the metal layer and the conductive oxide layer is 5 nm. Is within. Therefore, a sufficient contact angle contrast between the region A and the region B shown in FIG. 2 can be ensured, and the electromechanical conversion film can be formed on the first electrode with high accuracy. Therefore, more efficient vibration and deformation displacement can be obtained as compared with the electromechanical conversion element manufactured by the conventional spin method.

(Second Embodiment)
In the present embodiment, an embodiment in which the electromechanical conversion element of the above-described embodiment is applied to a droplet discharge head will be described.

  The configuration of the droplet discharge head to which the electromechanical transducer of the above-described embodiment is applied has been described with reference to FIG.

  As the droplet discharge head of this embodiment, a configuration in which a plurality of droplet discharge heads of FIG. 1 are arranged can be used.

  The droplet discharge head according to this embodiment is manufactured by manufacturing the electromechanical conversion element described in the above embodiments, and then etching the nozzle plate 12 having the nozzle holes 11 to form the liquid chamber 21 from the back surface. It can be created by joining. Therefore, a droplet discharge head having the same performance as a conventional droplet discharge head can be manufactured with a simple manufacturing process.

  Further, in FIG. 1 and the present embodiment, the case of applying to an inkjet head has been described as an example of use as a droplet discharge head, but the present embodiment is not limited to this. For example, it can be applied to uses such as a micro pump, an ultrasonic motor, an acceleration sensor, a two-axis scanner for a projector, and an infusion pump.

(Third embodiment)
In the third embodiment, an example of an ink jet recording apparatus equipped with the droplet discharge head of the second embodiment will be described with reference to FIGS. 6 and 7. 6 is a schematic diagram for explaining the ink jet recording apparatus of the present embodiment, and FIG. 7 is another schematic diagram for explaining the ink jet recording apparatus of the present embodiment.

  The ink jet recording apparatus according to the present embodiment includes a carriage 93 that is movable in the main scanning direction inside the recording apparatus main body 81, an ink jet recording head 94 that is an embodiment of the present invention mounted on the carriage 93, and an ink jet recording head. A printing mechanism unit 82 and the like configured by an ink cartridge 95 that supplies ink to 94 are accommodated. A sheet feeding cassette (or a sheet feeding tray) 84 on which a large number of sheets 83 can be stacked can be detachably mounted on the lower part of the recording apparatus main body 81. Further, the manual feed tray 85 for manually feeding 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 in, and after a required image is recorded by the printing mechanism unit 82, the paper is discharged to a paper discharge tray 86 mounted on the rear side.

  The printing mechanism 82 holds the carriage 93 slidably in the main scanning direction with a main guide rod 91 and a sub guide rod 92 which are guide members horizontally mounted on left and right side plates (not shown). An inkjet recording head 94 according to the present invention for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk) is provided on the carriage 93, and a plurality of ink ejection ports (nozzles). Are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward. Further, the carriage 93 is mounted with replaceable ink cartridges 95 for supplying ink of the respective colors to the ink jet recording head 94.

  The ink cartridge 95 has an air port (not shown) communicating with the air at the upper side, a supply port (not shown) for supplying ink to the inkjet recording head 94 at the lower side, and a porous body (not shown) filled with ink inside. doing. The ink supplied to the inkjet recording head 94 is maintained at a slight negative pressure by the capillary force of the porous body. In addition, although the heads of the respective colors are used here as the ink jet recording head 94, a single head having nozzles for ejecting ink droplets of the respective colors may be used.

  The carriage 93 is slidably fitted to the main guide rod 91 on the downstream side in the paper conveyance direction, and is slidably mounted on the sub guide rod 92 on the upstream side in the paper conveyance direction. 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 the main scanning motor 97, so that the main scanning motor 97 is forward / reverse. The carriage 93 is reciprocated by the rotation. The timing belt 100 is fixed to the carriage 93.

  The ink jet recording apparatus according to the present embodiment also reverses the paper feed roller 101 that separates and feeds the paper 83 from the paper feed cassette 84, the friction pad 102, the guide member 103 that guides the paper 83, and the fed paper 83. A conveying roller 104 that conveys the sheet 83, a conveying roller 105 that is pressed against the peripheral surface of the conveying roller 104, and a leading end roller 106 that defines a feeding angle of the sheet 83 from the conveying roller 104 are provided. As a result, the paper 83 set in the paper feed cassette 84 is conveyed to the lower side of the inkjet recording head 94. The transport roller 104 is rotationally driven by a sub-scanning motor 107 through a gear train.

  The printing receiving member 109 which is a paper guide member guides the paper 83 sent out from the transport roller 104 corresponding to the movement range of the carriage 93 in the main scanning direction on the lower side of the recording head 94. On the downstream side of the printing receiving member 109 in the sheet conveyance direction, a conveyance roller 111 and a spur 112 that are rotationally driven to send out the sheet 83 in the sheet discharge direction are provided. Further, a discharge roller 113 and a spur 114 for sending the paper 83 to the discharge tray 86, and guide members 115 and 116 for forming a discharge path are provided.

  At the time of image recording, the recording head 94 is driven in accordance with the image signal while moving the carriage 93 to eject ink onto the stopped paper 83 to record one line, and after the paper 83 is conveyed by a predetermined amount Record the next line. Upon receiving a recording end signal or a signal that the trailing end of the paper 83 reaches the recording area, the recording operation is terminated and the paper 83 is discharged.

  A recovery device 117 for recovering defective ejection of the head 94 is provided 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 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 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 of the head 94 is sealed by the capping unit, and bubbles and the like are sucked out from the discharge port by the suction unit through the tube. Also, ink or dust adhering to the ejection port surface is removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged into 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 the ink jet recording apparatus according to the present embodiment, since the droplet discharge head of the second embodiment is mounted, there is no ink droplet discharge failure due to vibration plate drive failure, and stable ink droplet discharge characteristics are obtained. , Improve the image quality.

DESCRIPTION OF SYMBOLS 10 Droplet discharge head 11 Nozzle hole 12 Nozzle plate 20 Liquid chamber board | substrate 21 Liquid chamber 30 Vibrating plate 40 Electromechanical conversion element 41 Adhesion layer 42 Metal layer 43 Conductive oxide layer 44 1st electrode 44 Electromechanical conversion film 45 2nd Electrode

Japanese Patent No. 4590855

Claims (1)

A first electrode having a metal layer formed on the ground and a conductive oxide layer formed on a part of the metal layer;
An electromechanical conversion film formed on the conductive oxide layer;
A second electrode formed on at least a part of the electromechanical conversion film, and a method for producing an electromechanical conversion element having at least a laminated structure,
Laminating a metal layer and a conductive oxide layer on the ground;
Applying a resist composition on the conductive oxide layer to form a resist film;
Exposing and developing the resist film and patterning;
Using the patterned resist film as a mask, the height of the region of the first electrode not covered with the resist film from the base and the base of the interface between the metal layer and the conductive oxide layer A step of dry etching so that the difference between the height and the height is 5 nm or less;
Surface modifying the region to be hydrophobic;
Applying a sol-gel solution containing a precursor of the electromechanical conversion film to an unsurface-modified region on the first electrode by an inkjet method;
And a step of heat-treating the applied sol-gel solution.