JP2016165816A - Electromechanical conversion member, method of manufacturing the same, droplet discharge head, ink cartridge, and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromechanical conversion member with high durability and reliability by suppressing peeling of a lower electrode.SOLUTION: In an electromechanical conversion member which comprises: a diaphragm 15 forming one surface of a liquid chamber 13; and a piezoelectric element 16 having a lower electrode 161, a piezoelectric substance 162 and an upper electrode 163 formed in this order on the diaphragm 15, the lower electrodes 161 being a common electrode of the piezoelectric element 16 by being continuously provided across the direction in which the liquid chambers 13 are arranged side by side, a recess 15a is formed in the depth direction of the diaphragm 15 at a position other than a liquid chamber formation region 13a of the diaphragm 15, and the lower electrode 161 includes an anchor part 161a having the shape entering the recess 15a.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an electromechanical conversion member, a method for manufacturing an electromechanical conversion member, a droplet discharge head, an ink cartridge, and an image forming apparatus.

  In general, printers, facsimiles, copiers, plotters, or image forming apparatuses that combine a plurality of these functions include, for example, an ink jet recording apparatus that includes a droplet discharge head that discharges droplets of ink or the like.

  The droplet discharge head is also referred to as a nozzle that discharges liquid droplets of ink or the like, and a liquid chamber (pressure chamber, pressure chamber, pressure chamber, discharge chamber, or the like) that communicates with the nozzle and stores liquid. )) And an electromechanical transducer such as a piezoelectric element are known. In this droplet discharge head, when a voltage is applied to the piezoelectric element, the piezoelectric element vibrates so as to deform a diaphragm that forms part of the wall of the liquid chamber, and the liquid in the liquid chamber is deformed by the deformation of the diaphragm. Is pressurized, and droplets can be discharged from the nozzle.

  The droplet recording head of the ink jet recording apparatus uses a piezoelectric actuator as an electromechanical conversion member in a longitudinal vibration mode that extends and contracts in the axial direction of the piezoelectric element, and uses a piezoelectric actuator in a flexural vibration mode. Two types have been put into practical use.

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

  A piezoelectric element used for a piezoelectric actuator in a flexural vibration mode includes, for example, a lower electrode (lower electrode layer) that is a common electrode formed on a diaphragm and a piezoelectric body (piezoelectric layer) formed on the lower electrode. ) And an upper electrode (upper electrode layer) which is an individual electrode formed on the piezoelectric body. Further, an interlayer insulating film is formed on the upper electrode to insulate the lower electrode from the upper electrode, and a wiring electrically connected to the upper electrode through a contact hole opened in the interlayer insulating film. It has a provided structure.

However, during the manufacturing process of the piezoelectric actuator as described above, the lower electrode (for example, a laminated structure of Pt and TiO ₂ ) has a very good adhesion to the underlying diaphragm (for example, a silicon oxide film). In addition, in post-processing after etching in the lower electrode patterning process in the middle of manufacturing (for example, a resist removing process), film peeling or film floating (hereinafter also simply referred to as peeling) occurs at the pattern edge of the lower electrode, particularly at the corner. Will occur.

  When the lower electrode is peeled off, a short circuit or the like due to the lower electrode adhering to an unintended portion on the piezoelectric actuator substrate occurs, and the reliability of the product is lowered. In addition, the yield of the actuator substrate is reduced.

  As a technique relating to the lower electrode and the diaphragm, Patent Document 1 includes a laminated electrode provided on a diaphragm outside the region corresponding to the pressure generation chamber, which is configured by a layer different from the lower electrode and the upper electrode, and Breakage of the diaphragm by providing a stress relaxation layer made of a material having a linear expansion coefficient larger than that of the diaphragm and smaller than that of the multilayer electrode at least in a region corresponding to the end of the multilayer electrode between the multilayer electrode and the diaphragm. A liquid ejecting head that prevents the above is disclosed. Further, Patent Document 2 discloses a liquid ejecting head in which a stress relaxation layer is provided at a location where mechanical stress of the diaphragm along the periphery of the liquid chamber is concentrated.

  However, in the above prior art, in order to sufficiently exert the effect of the stress relaxation layer, the chip size cannot be reduced because it extends to the outside of the peripheral portion, and there is a problem in terms of cost reduction and yield improvement. there were. In addition, the number of processes has been increased by forming a stress relaxation layer.

  In addition, it is known that the lower electrode and the diaphragm are laminated via an adhesion layer provided on the lower electrode. Generally, the thin film lamination interface has a different linear expansion coefficient of each material, so Depending on the temperature at the time of film formation and the subsequent process temperature, the balance of stress was lost, and film peeling and film floating occurred at the thin film interface.

  As described above, there remains room for studying the suppression of peeling of the lower electrode due to restrictions on the pattern shape, area, and film thickness of the film.

  Therefore, an object of the present invention is to provide an electromechanical conversion member having high durability and reliability by suppressing peeling of the lower electrode.

  In order to achieve such an object, an electromechanical conversion member according to the present invention includes a diaphragm that forms one surface of a liquid chamber, and an electromechanical conversion in which a lower electrode, a piezoelectric body, and an upper electrode are formed in this order on the diaphragm. An electromechanical conversion member that serves as a common electrode of the electromechanical conversion element by being continuously provided in a direction in which the liquid chambers are arranged in parallel. A concave portion is formed in the depth direction of the diaphragm at a position other than the formation region of the liquid chamber, and the lower electrode has a shape that enters the concave portion.

  ADVANTAGE OF THE INVENTION According to this invention, peeling of a lower electrode can be suppressed and an electromechanical conversion member with high durability and reliability can be provided.

FIG. 3 is a cross-sectional view of the liquid chamber in the arrangement direction showing a schematic configuration of a droplet discharge unit that is a basic component of the droplet discharge head. It is sectional drawing of the direction orthogonal to the arrangement direction of a liquid chamber which shows schematic structure of a droplet discharge part. It is a perspective view which shows schematic structure of a droplet discharge part. It is a figure which shows the example of the XRD pattern figure of a SRO film | membrane (111). It is a flowchart which shows an example of the manufacturing process of a droplet discharge part. It is explanatory drawing which shows a mode that peeling liquid attacks the corner part of a lower electrode. It is an example of a sectional view showing a schematic structure of an actuator substrate concerning this embodiment. It is sectional drawing of the arrangement direction of a liquid chamber which shows schematic structure of the droplet discharge part provided with the actuator board | substrate which concerns on this embodiment. It is explanatory drawing (1) of the manufacturing process of a droplet discharge part. It is explanatory drawing (2) of the manufacturing process of a droplet discharge part. It is explanatory drawing (3) of the manufacturing process of a droplet discharge part. 1 is a top view of a piezoelectric element according to Example 1. FIG. 6 is a top view of a piezoelectric element according to Example 2. FIG. 6 is a top view of a piezoelectric element according to Example 3. FIG. 6 is a top view of a piezoelectric element according to Example 4. FIG. 6 is a top view of a piezoelectric element according to Example 5. FIG. FIG. 6 is a perspective view illustrating a configuration example of an ink cartridge including a droplet discharge head. It is a perspective view showing an example of composition of an ink jet recording device provided with a droplet discharge head. FIG. 4 is a side view illustrating a configuration example of a mechanism unit of an ink jet recording apparatus including a droplet discharge head.

  Hereinafter, the configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

(Configuration of electromechanical conversion member / droplet discharge head)
FIG. 1 is a cross-sectional view in the arrangement direction of liquid chambers showing a schematic configuration of a liquid droplet discharge portion which is a basic component of the liquid droplet discharge head, and only a portion corresponding to one liquid chamber is shown for convenience. FIG. 2 is a cross-sectional view in a direction perpendicular to the arrangement direction of the liquid chambers, showing a schematic configuration of the droplet discharge section. FIG. 3 is a perspective view showing a schematic configuration of the droplet discharge unit.

  As shown in FIG. 1, the droplet discharge unit 10 is a liquid in which a nozzle substrate 12 having a nozzle 11 for discharging a droplet of a liquid such as ink and a liquid chamber 13 that communicates with the nozzle 11 and contains a liquid are formed. And a chamber substrate 14 (hereinafter simply referred to as “substrate”). In the substrate 14, a partition wall portion of the liquid chamber 13 communicating with the nozzle 11, a fluid resistance portion 32, an ink introduction path 33 to the liquid chamber 13, and the like are formed. A vibration plate 15 serving as one wall surface of the liquid chamber 13 is formed on the substrate 14, and a piezoelectric element 16 including a lower electrode 161, a piezoelectric body (PZT) 162, and an upper electrode 163 is provided on the vibration plate 15. . A first insulating protective film 17, a second insulating protective film 18, a third insulating protective film 19, and a subframe 20 (second substrate) as a first protective film are provided so as to cover the piezoelectric element 16. Is provided.

  The piezoelectric element 16 includes a lower electrode 161 serving as a common electrode on the diaphragm 15 side, a piezoelectric body 162 made of PZT or the like as an electromechanical conversion film, and an individual electrode on the opposite side of the piezoelectric body 162 from the diaphragm 15 side. The upper electrode 163 is laminated. The lower electrode 161 is connected to a wiring 21 through a contact hole 17a formed in the first insulating protective film 17, and is connected to a pad electrode for a common electrode as a terminal electrode for external connection through the wiring 21. Has been. The upper electrode 163 is connected to the wiring 22 by a contact hole 18a formed in the second insulating protective film 18, and a pad electrode for an individual electrode as a terminal electrode for external connection through the wiring 22 23.

  The subframe 20 includes a common electrode wiring 21 electrically connected to the lower electrode 161 and the upper electrode 163, and a wiring space 22a for the individual electrodes including the wiring 22 for the individual electrodes, and the drive IC 24. Space. Further, it has a groove portion that becomes an ink flow path 35 from the common liquid chamber to the liquid chamber 13. The ink flow path 35 communicates with an ink introduction path 33 formed in the substrate 14 via an ink supply port 34.

  In the droplet discharge section 10 configured as described above, a predetermined electrode is provided between the lower electrode 161 and the upper electrode 163 of the piezoelectric element 16 via the common electrode pad electrode and wiring 21 and the individual electrode pad electrode 23 and wiring 22, respectively. A driving voltage having a frequency and an amplitude of 2 is applied. The piezoelectric element 16 to which the driving voltage is applied vibrates so as to deform the vibration plate 15 between the substrate 14 and the piezoelectric element 16, and the liquid in the liquid chamber 13 is pressurized by the deformation of the vibration plate 15. Thus, the droplets can be ejected from the nozzle 11.

  Next, the materials and methods of each part and member, which are constituent elements constituting the droplet discharge head, will be described more specifically.

〔substrate〕
As the substrate 14, it is preferable to use a silicon single crystal substrate, and it is preferable to have a thickness in the range of 100 [μm] to 600 [μm]. There are three types of plane orientations: (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry. In this configuration example, A single crystal substrate having a (100) plane orientation was mainly used. Further, when the liquid chamber (pressure chamber) 13 as shown in FIG. 1 is manufactured, the silicon single crystal substrate is processed using etching. As an etching method in this case, 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, 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. I know you can. As this configuration example, it is possible to use a single crystal substrate having a (110) plane orientation. However, in this case, SiO ₂ which is a mask material is also etched, so it is preferable to use this point in consideration.

(Diaphragm)
As shown in FIG. 1, upon receiving the force generated by the piezoelectric element 16 as an electromechanical transducer, the underlying diaphragm 15 is deformed, and liquid droplets such as ink in the liquid chamber (pressure chamber) 13 are discharged. Discharge. Therefore, it is preferable that the diaphragm 15 has a predetermined strength. Examples of the material include those made of Si, SiO ₂ , Si ₃ N _{4 and the} like by, for example, a CVD (Chemical Vapor Deposition) method. Further, it is preferable to select a material close to the linear expansion coefficient of the common electrode (lower electrode) 161 and the piezoelectric body 162 as shown in FIG. In particular, as the piezoelectric body 162, PZT is generally used as a material in many cases. Therefore, the material of the diaphragm 15 is in the range of 5 × 10 ⁻⁶ (1 / K) to 10 × 10 ⁻⁶ (1 / K), which is close to the linear expansion coefficient 8 × 10 ⁻⁶ (1 / K) of PZT. A material having a linear expansion coefficient of is preferable. Furthermore, a material having a linear expansion coefficient in the range of 7 × 10 ⁻⁶ (1 / K) to 9 × 10 ⁻⁶ (1 / K) 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. These materials can be produced by a spin coater using, for example, a sputtering method or a sol-gel method. The film thickness is preferably in the range of 0.1 [μm] to 10 [μm], and more preferably in the range of 0.5 [μm] to 3 [μm]. If it is smaller than this range, it becomes difficult to process the liquid chamber (pressure chamber) 13 as shown in FIG. On the other hand, if it is larger than the above range, the diaphragm 15 is not easily deformed, and ejection of droplets such as ink droplets becomes unstable.

[Lower electrode (common electrode)]
The lower electrode (common electrode) 161 is preferably made of metal or metal and oxide. Here, both materials are devised so as to suppress peeling and the like by putting an adhesion layer between the diaphragm 15 and the metal film constituting the lower electrode 161. Details of the metal electrode film and the oxide electrode film including the adhesion layer are described below.

[Adhesion layer]
The adhesion layer is formed as follows, for example. After Ti is formed by sputtering, the formed titanium film is thermally oxidized using an RTA (Rapid Thermal Annealing) apparatus to form a titanium oxide film. The conditions for thermal oxidation are, for example, a temperature in the range of 650 [° C.] to 800 [° C.], a treatment time in the range of 1 [min] to 30 [min], and an O ₂ atmosphere. 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 oxide film is 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 having a high temperature rising rate is advantageous in order to form better crystals. Moreover, as materials other than Ti, materials such as Ta, Ir, and Ru can be used. The thickness of the adhesion layer is preferably in the range of 10 [nm] to 50 [nm], and more preferably in the range of 15 [nm] to 30 [nm]. If it is less than this range, there is concern about adhesion. Also, if the value exceeds this range, the surface roughness of the lower electrode will increase and the adhesion to the piezoelectric film will decrease, adversely affecting the crystallinity of the piezoelectric film, and sufficient displacement for ink ejection will not be obtained. Trouble occurs.

[Metal electrode film]
Conventionally, platinum having high heat resistance and low reactivity has been used as the metal material of the metal electrode film, but it may not be said that it has sufficient barrier properties against lead. -Platinum group elements, such as rhodium, and these alloy films are also mentioned. Further, when platinum is used, it is preferable that the above-mentioned adhesion layer is laminated first because adhesion to the base (particularly SiO ₂ ) is poor. As a manufacturing method, vacuum film formation such as sputtering or vacuum deposition is generally used. The film thickness is preferably in the range of 80 [nm] to 200 [nm], and more preferably in the range of 100 [nm] to 150 [nm]. When the thickness is smaller than this range, a sufficient current cannot be supplied as the lower electrode 161, and a problem occurs when ejecting a droplet. Further, when the thickness is larger than this range, the cost increases when an expensive material of a platinum group element is used. In the case of using platinum as a material, the surface roughness increases when the film thickness is increased, which affects the surface roughness and crystal orientation of the oxide electrode film and PZT produced thereon. This causes a problem that sufficient displacement for ink ejection cannot be obtained.

[Oxide electrode film]
As a material for the oxide electrode film, it is preferable to use SrRuO ₃ (sometimes simply referred to as SRO). Otherwise, Sr _x (A) _(1-x) Ru _y (B) _(1-y) , A = Ba, Ca, B = Co, Ni, x, y = 0 to 0.5 Also mentioned are other materials. The film forming method is produced by sputtering. The film quality of the SrRuO ₃ thin film varies depending on the sputtering conditions. In particular, in order to place the SrRuO ₃ film in the (111) orientation in accordance with the Pt (111) of the first electrode, in particular, the crystal orientation is important. Is preferably formed by heating the substrate at 500 [° C.] or higher.

  For example, with respect to the SRO film formation conditions described in Japanese Patent No. 3784401, when thermal acidification is performed at a crystallization temperature (650 [° C.]) by RTA treatment after film formation at room temperature, the SRO film is sufficiently crystallized. Although a sufficient value is obtained as the specific resistance as an electrode, (110) is likely to be preferentially oriented as the crystal orientation of the film, and (110) orientation is also easy for PZT formed thereon. Become.

  Regarding SRO crystallinity produced on Pt (111), since the lattice constants of Pt and SRO are close to each other, in the normal θ-2θ measurement, the 2θ positions of SRO (111) and Pt (111) are overlapped, so that discrimination is possible. 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 direction by about 35 ° and judging from the peak intensity where 2θ is about 32 °.

  FIG. 4 shows an example of a measurement result when 2θ = 32 ° is fixed and Psi is shaken. At Psi = 0 °, almost no diffraction intensity is observed at SRO (110), and diffraction intensity is observed at around Psi = 35 °. It can be confirmed that it is oriented. In addition, regarding the SRO produced by the above-described room temperature film formation + RTA process, the diffraction intensity of SRO (110) is observed when Psi = 0 °.

  In addition, when the amount of displacement after being driven was estimated to be deteriorated compared to the initial displacement when continuously operating as a piezoelectric actuator, the orientation of PZT has a great influence. (110) Insufficient displacement suppression is insufficient. 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 after that and displacement deterioration after continuous driving. . The surface roughness is preferably 4 to 15 [nm], and more preferably 6 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 the crystallinity and the surface roughness as described above, the film formation temperature is 500 to 700 [° C.], preferably 520 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.

  Furthermore, the film thickness of the SRO film is preferably 40 to 150 [nm], and more preferably 50 to 80 [m]. If the thickness is smaller than this range, sufficient characteristics may not be obtained for initial displacement and displacement deterioration after continuous driving, and a function as a stop etching layer for suppressing overetching of PZT is also obtained. It becomes difficult. If this range is exceeded, the dielectric breakdown voltage of the PZT deposited thereafter is very poor and leaks easily.

The specific resistance is preferably 5 × 10 ⁻³ [Ω · cm] or less, and more preferably 1 × 10 ⁻³ [Ω · cm] or less. If it is larger than this range, a sufficient current cannot be supplied, and a problem occurs when ink is ejected.

[Piezoelectric body (electromechanical conversion film)]
As a material of the piezoelectric body 162, PZT was mainly used. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and titanic acid (PbTiO ₃ ), and the characteristics differ depending on the ratio. In general, the composition exhibiting excellent piezoelectric characteristics has a ratio of PbZrO ₃ and PbTiO ₃ of 53:47. When expressed by a chemical formula, Pb (Zr0.53, Ti0.47) O ₃ , general PZT (53/47) It is indicated. 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 A = Pb, Ba, Sr, B = Ti, Zr, Sn, Ni, Zn, Mg, and a composite oxide mainly composed of Nb. Specifically, (Pb1-x, Ba) (Zr, Ti) O ₃ , (Pb1-x, Sr) (Zr, Ti) O ₃ , which partially replaces Pb of the A site with Ba or Sr. This is the case. Such substitution is possible with a divalent element, and the effect thereof has an effect of reducing characteristic deterioration due to evaporation of lead during heat treatment.

  As a method for manufacturing the piezoelectric body 162, 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 (also called lithoetching) or the like. When PZT is produced by the sol-gel method, a PZT precursor solution can be produced by using lead acetate, zirconium alkoxide, and titanium alkoxide compounds 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 the film of the piezoelectric body 162 (PZT film) is obtained on the entire surface of the substrate 14, 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 the transformation from the coating film to the crystallized film involves volume shrinkage, it is necessary to adjust the precursor concentration so that a film thickness of 100 nm or less can be obtained in one step in order to obtain a crack-free film. Become.

  The film thickness of the piezoelectric body 162 is preferably in the range of 0.5 [μm] to 5 [μm], and more preferably in the range of 1 [μm] to 2 [μm]. If it is smaller than this range, it will not be possible to generate sufficient deformation (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.

  The relative permittivity of the piezoelectric body 162 is preferably in the range of 600 to 2000, and more preferably in the range of 1200 to 1600. At this time, when it is smaller than this range, sufficient deformation (displacement) characteristics cannot be obtained, and when it is larger than this range, polarization processing is not performed sufficiently, and sufficient characteristics cannot be obtained for displacement deterioration after continuous driving. A malfunction occurs.

[Upper electrode (individual electrode)]
Unlike the lower electrode material layer, the upper electrode (individual electrode) 163 is not subjected to a high-temperature process such as that for forming the film of the piezoelectric body 162 and the lattice constant matching with the film of the piezoelectric body 162 is not performed later. Since it is not necessary, the material selection width is wider than that of the lower electrode 161. For the upper electrode 163, a platinum film, a metal electrode such as iridium or gold can be used. A laminated film of an oxide electrode layer and a metal electrode can also be used.

  The upper electrode 163 is preferably made of metal or oxide and metal. Details of the oxide electrode film and the metal electrode film are described below.

[Oxide electrode film]
Examples of the material for the oxide electrode film include the same materials as those described for the oxide electrode film used in the lower electrode (common electrode) 161 described above. The oxide electrode film can be produced by a film forming method such as sputtering. The thickness of the oxide electrode film is preferably in the range of 20 [nm] to 80 [nm], and more preferably in the range of 40 [nm] to 60 [nm]. If the thickness is less than this range, sufficient characteristics cannot be obtained for the deterioration characteristics of initial deformation (displacement) and deformation (displacement). On the other hand, if it exceeds this range, the withstand voltage of the PZT film formed thereafter deteriorates and leaks easily.

[Metal electrode film]
Examples of the material for the metal electrode film include the same materials as those described for the metal electrode film used in the lower electrode (common electrode) 161 described above. The thickness of the metal electrode film is preferably in the range of 30 [nm] to 200 [nm], and more preferably in the range of 50 [nm] to 120 [nm]. When the thickness is smaller than this range, a sufficient current cannot be supplied as the upper electrode (individual electrode) 163, and a problem occurs when ejecting a droplet. On the other hand, when the thickness is larger than the above range, the cost increases when an expensive material of a platinum group element is used. In addition, when platinum is used as the material, the surface roughness increases when the film thickness is increased, and process defects such as film peeling are likely to occur when wiring is formed through an insulating protective film. .

[First insulating protective film]
The material of the first insulating protective film 17 needs to be a dense inorganic material because it is necessary to select a material that prevents moisture in the atmosphere from being transmitted through while preventing damage to the piezoelectric element due to the film formation / etching process. There is. Further, when an organic material is used for the first insulating protective film 17, it is not suitable because it is necessary to increase the film thickness in order to obtain sufficient protection performance. When the first insulating protective film 17 is a thick film, the vibration of the diaphragm 15 is remarkably hindered, resulting in a droplet discharge head having a low discharge performance. In order to obtain high protection performance with a thin film, it is preferable to use an oxide, nitride, or carbide film. However, the electrode material, the piezoelectric material, and the diaphragm material serving as the base of the first insulating protective film 17 have adhesiveness. It is necessary to select a high material. In addition, it is necessary to select a film forming method that does not damage the piezoelectric element 16 as a method for forming the first insulating protective film 17. That is, a plasma CVD method in which a reactive gas is turned into plasma and deposited on a substrate, or a sputtering method in which a film is formed by causing a plasma to collide with a target material and flying away is not preferable. Examples of a preferable film formation method for the first insulating protective film 17 include an evaporation method and an ALD (Atomic Layer Deposition) method, but an ALD method with a wide range of materials that can be used is preferable. Preferred _{materials, Al 2 O 3, ZrO 2} , Y2O 3, Ta 2 O 3, an oxide film used in the ceramic material, such as TiO ₂ can be cited as examples. In particular, by using the ALD method, a thin film having a very high film density can be produced and damage in the process can be suppressed.

  The film thickness of the first insulating protective film 17 needs to be thin enough to ensure the protection performance of the piezoelectric element 16, and at the same time, it is made as thin as possible so as not to inhibit the deformation (displacement) of the diaphragm 15. There is a need. The thickness of the first insulating protective film 17 is preferably in the range of 20 [nm] to 100 [nm]. When the thickness is greater than 100 [nm], the deformation (displacement) amount of the vibration plate 15 is reduced, so that a droplet discharge head with low discharge efficiency is obtained. On the other hand, when the thickness is smaller than 20 [nm], the function of the piezoelectric element 16 as a protective layer is insufficient, so that the performance of the piezoelectric element 16 is deteriorated as described above.

[Second insulating protective film]
As the second insulating protective film 18, any oxide, nitride, carbide, or composite compound thereof can be used, and SiO ₂ generally used in semiconductor devices can also be used. Arbitrary methods can be used for forming the second insulating protective film 18, and examples thereof include a CVD method, a sputtering method, and an ALD method. It is preferable to use a CVD method capable of forming an isotropic film in consideration of the step coverage of the pattern forming portion such as the electrode forming portion. The film thickness of the second insulating protective film 18 needs to be a film thickness that does not cause dielectric breakdown by a voltage applied between the common electrode (lower electrode) 161 and the wiring 22 of the individual electrode. That is, it is necessary to set the electric field strength applied to the second insulating protective film 18 within a range that does not cause dielectric breakdown. Furthermore, in consideration of the surface property of the base of the second insulating protective film 18, pinholes, etc., the thickness of the second insulating protective film 18 needs to be 200 [nm] or more, more preferably 500 [nm] or more. It is.

[Wiring, pad electrode]
The material of the wirings 21 and 22 and the pad electrode is preferably a metal electrode material made of Ag alloy, Cu, Al, Au, Pt, or Ir. As a method for manufacturing these electrodes, a sputtering method or a spin coating method is used, and then a desired pattern is obtained by photolithography etching or the like. The film thickness is preferably in the range of 0.1 [μm] to 20 [μm], and more preferably in the range of 0.2 [μm] to 10 [μm]. If it is smaller than this range, the resistance becomes large, and a sufficient current cannot flow through the electrodes, making the head ejection unstable. On the other hand, if it is larger than this range, the process time becomes longer. Further, the contact resistance in the contact hole portion (for example, 10 [μm] × 10 [μm]) connected to the lower electrode 161 and the upper electrode 163 is 10 [Ω] or less with respect to the lower electrode 161 that is a common electrode. The upper electrode 163 that is an individual electrode is preferably 1 [Ω] or less. More preferably, it is 5 [Ω] or less for the lower electrode 161 and 0.5 [Ω] or less for the upper electrode 163. If it exceeds this range, it will not be possible to supply a sufficient current, and problems will occur when discharging droplets.

[Third insulating protective film]
The function as the third insulating protective film 19 is a passivation layer having a function as a protective layer of the common electrode wiring 21 and the individual electrode wiring 22. As shown in FIG. 2, the upper electrode 163 and the lower electrode 161 are covered except for the lead portion of the upper electrode 163 and the lead portion of the lower electrode 161 (contact hole 18a). Thereby, an inexpensive Al or an alloy material containing Al as a main component can be used as the electrode material. As a result, a low-cost and highly reliable droplet discharge head (inkjet head) can be obtained. As the material of the third insulating protective film 19, any inorganic material or organic material can be used, but it is necessary to use a material with low moisture permeability. Examples of the inorganic material include oxides, nitrides, and carbides, and examples of the organic material include polyimide, acrylic resin, and urethane resin. However, an organic material is not suitable for patterning because it needs to be a thick film. Therefore, it is preferable to use an inorganic material that can exhibit a wiring protection function with a thin film. In particular, it is preferable to use Si ₃ N ₄ on the Al wiring because it is a proven technology for semiconductor devices. The film thickness is preferably 200 [nm] or more, and more preferably 500 [nm] or more. When the film thickness is thin, a sufficient passivation function cannot be exhibited, so that disconnection due to corrosion of the wiring material occurs, and the reliability of the ink jet is lowered.

Further, a structure having openings on the piezoelectric element 16 and the surrounding diaphragm 15 is preferable. This is the same reason that the region corresponding to the liquid chamber 13 of the first insulating protective film 17 is thinned. As a result, a highly efficient and highly reliable droplet discharge head (inkjet head) can be obtained. Since the piezoelectric element 16 is protected by the first and second insulating protective films 17 and 18, a photolithography method and dry etching can be used to form the opening of the third insulating protective film 19. Note that the area of the pad electrode is preferably 50 × 50 [μm ² ] or more, and more preferably 100 × 300 [μm ² ] or more.

(Droplet ejection head manufacturing process)
Next, an example of a manufacturing method of the droplet discharge head 1 as a premise will be described. FIG. 5 is a flowchart for explaining an example of the manufacturing process of the droplet discharge head 1.

  First, the diaphragm 15 is formed on the substrate 14 (step S1). As the substrate 14, for example, a silicon wafer having a thickness of 625 [μm] is used. A vibration plate 15 is formed on the substrate 14 in a desired configuration such as a thermal oxide film, a silicon oxide film formed by, for example, a CVD method, a silicon nitride film, or a polysilicon film.

  Next, the piezoelectric element 16 is formed on the vibration plate 15. Specifically, in the piezoelectric element 16, a lower electrode that is a common electrode is formed (step S2), a PZT film that is a piezoelectric body 162 is formed (step S3), and an upper electrode 163 that is an individual electrode is formed (step S4). ) In this order.

  Specifically, in the formation of the lower electrode in step S2, a titanium film (film thickness 30 [nm]) is first formed as an adhesion film with a sputtering apparatus, and then the temperature is set to 750 [° C.] using RTA. And thermally oxidized.

Subsequently, a platinum film (film thickness 100 [nm]) was formed as a metal film. A titanium oxide film is formed on the platinum film. A titanium film is formed on the platinum film by sputtering. Subsequently, the titanium film is thermally oxidized in an O ₂ atmosphere at 650 to 750 [° C.] for 1 to 5 minutes using RTA to form a titanium oxide film. The thickness of the titanium film is preferably 30 to 70 angstroms.

  In step S3, a PZT film is formed to a desired thickness by a sol-gel method.

Specifically, the upper electrode in step S4 is formed by sputtering a SrRuO ₃ film (film thickness 20 [nm]) as an oxide film and a Pt film (film thickness 100 [nm]) as a metal film, respectively. A film was formed.

  Thereafter, a photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. was formed by spin coating, and a resist pattern was formed by ordinary photolithography. Thereafter, the PZT film and the upper electrode were individualized by etching using an ICP (Inductively Coupled Plasma) etching apparatus (manufactured by Samco Co., Ltd.) to produce a pattern (step S5). Thereby, the upper electrode 163 functions as an individual electrode.

  Next, in the same manner, a resist pattern is formed by photolithography, and a lower electrode pattern is formed by etching (step S6). The lower electrode 161 is not individualized like the PZT film and the upper electrode, and is patterned so as to function as a common electrode for the plurality of piezoelectric bodies 162 and the upper electrode 163.

Next, an Al ₂ O ₃ film was formed as the first insulating protective film 17 by the ALD method (step S7). The first insulating protective film 17 functions as a barrier layer that protects the piezoelectric element 16 from process damage such as hydrogen. By using Al ₂ O _{3 formed} by the ALD method as the first insulating protective film 17 (barrier layer), a good barrier layer with low moisture permeability can be obtained.

  The thickness of the first insulating protective film 17 functioning as a barrier layer is preferably in the range of 30 [nm] to 80 [nm]. Accordingly, the function of the piezoelectric element 16 as an actuator can be maintained while the first insulating protective film 17 has a sufficient barrier property as a barrier layer.

  The taper angle, which is the angle formed between the surface of the substrate 14 and the side wall of the first insulating protective film 17 (barrier layer), is preferably smaller than the taper angle formed between the surface of the substrate 14 and the side wall surface of the piezoelectric element 16. . Thereby, the concentration of stress at the end of the piezoelectric element 16 is alleviated, the life can be extended, and the reliability is improved.

Next, a SiO ₂ interlayer film was formed as the second insulating protective film 18 (step S8). In this way, by using SiO ₂ that is an interlayer film, the first insulating protective film 17 (barrier layer) is further added to the portion covering the side wall surface of the piezoelectric element 16 without adding a new process. 2 protective films can be formed. Therefore, it is possible to prevent a decrease in production efficiency and an increase in manufacturing cost. Further, in the subsequent photolithography / etching step, the side wall surface of the piezoelectric element 16 in the first insulating protective film 17 (barrier layer) is etched by etching the side wall surface of the piezoelectric element 16 masked with a resist. The SiO ₂ interlayer film is left in the portion covering the film. Thereby, over-etching of the first insulating protective film 17 (barrier layer) can be prevented more reliably.

The thickness of the SiO ₂ interlayer film is preferably in the range of 10 nm to 500 nm. If it is thinner than 10 [nm], sufficient etching resistance cannot be secured. On the other hand, if the thickness is larger than 500 [nm], the piezoelectric element 16 is difficult to deform, and the function as an actuator may not be maintained.

  Thereafter, a contact hole 18a was formed by etching (step S9). And in order to form wiring, Al was formed into a film by sputtering (step S10). Further, the Al film formed in Step S8 was etched and patterned (Step S11).

  Thereafter, a SiN passivation layer is formed as the third insulating protective film 19 and an etching process is performed (steps S12 and S13).

  Finally, a through hole that becomes the ink supply port 34 was formed in the diaphragm by etching (step S14).

  The composite laminated substrate including the substrate 14, the vibration plate 15, the piezoelectric element 16, and various electrodes formed in this manner is an electromechanical conversion member called an actuator substrate 30 (first substrate). The diaphragm 15 and the piezoelectric element 16 excluding the substrate 14 may be called electromechanical conversion members. The numerical values such as the material and film thickness of each layer of the electromechanical conversion member described so far are only examples, and the present invention is not limited thereto.

(Diaphragm, lower electrode)
Hereinafter, the electromechanical conversion member according to the present embodiment, which is characterized by the diaphragm and the lower electrode, will be described.

  As described above, in the resist stripping process, there is a problem that the yield is lowered due to the peeling of the lower electrode. The peeling of the corners of the lower electrode seems to be caused by the fact that the stripping solution is directly discharged to the corners where the stress is concentrated. Peeling becomes apparent on the lower electrode (common electrode) having a large area.

  On the other hand, as shown in FIG. 6, the structure which makes the corner part of the lower electrode 161 as a common electrode round shape is considered. With this configuration, in the resist stripping process using the stripping solution, the stripping solution attacks the corners of the lower electrode 161 only from the direction along the round shape. It becomes difficult for the liquid to enter between the lower surface of the lower electrode 161 and the diaphragm 15. For this reason, the lower electrode 161 can be made difficult to peel off from the diaphragm 15, and as a result, the actuator substrate 30 having high reliability can be obtained.

  However, according to the study by the inventors of the present application, it has been found that by making the corner of the lower electrode 161 round, it is not possible to eliminate the occurrence of peeling, and there is room for further improvement.

  Therefore, the electromechanical conversion member (actuator substrate 30) according to the present embodiment includes a vibration plate (vibration plate 15) that forms one surface of the liquid chamber (liquid chamber 13), and a lower electrode (lower electrode 161) on the vibration plate. ), A piezoelectric body (piezoelectric body 162), and an electromechanical transducer (piezoelectric element 16) in which an upper electrode (upper electrode 163) is formed in this order, and the lower electrode is arranged in a direction in which liquid chambers are arranged in parallel. In the electromechanical conversion member that is continuously provided over the electromechanical conversion element and is provided as a common electrode, in the depth direction of the vibration plate at a position other than the liquid chamber formation region (liquid chamber formation region 13a) of the vibration plate A concave portion (concave portion 15a) is formed in the lower electrode, and a shape (anchor portion 161a) in which the lower electrode enters the concave portion (FIG. 7 and the like). In addition, the code | symbol in embodiment and the example of application are shown in a parenthesis.

  FIG. 7 is a sectional view of the liquid chamber of the 2-bit actuator substrate 30 in the arrangement direction. After the diaphragm 15 is formed, the actuator substrate 30 forms the lower electrode 161, the piezoelectric body 162, and the upper electrode 163 in order, and then forms the desired pattern in the upper electrode 163 and the piezoelectric body 162 in order by the lithoetch method. To do. Next, a desired pattern is formed on the lower electrode 161 by a lithoetch method.

  At this time, after the vibration plate 15 is formed and before the lower electrode 161 (lower electrode layer) is formed, a region (liquid chamber formation) corresponding to the upper portion of the liquid chamber 13 serving as the driving unit of the piezoelectric element 16 in the vibration plate 15 A recess 15a, which is a depression in the depth direction of the diaphragm 15, is formed at a position excluding the region 13a). In the formation of the lower electrode 161, the layer of the lower electrode 161 enters the recess 15 a formed in the vibration plate 15. The portion of the lower electrode 161 that enters the recess 15a of the diaphragm 15 is referred to as an anchor portion 161a.

  The recesses 15a are formed, for example, along the corresponding positions of the corners (four corners) of the pattern of the lower electrode 161 (FIG. 12) and the corresponding positions of the peripheral edge of the pattern of the lower electrode 161 (FIG. 14). Is preferred. The shape of the recess 15a is not limited to the groove shape, and may be a quadrangle, a round shape, an ellipse, a slit shape, or the like.

  As described above, the corners and the peripheral edge of the pattern of the lower electrode 161 are liable to cause film peeling or film floating. However, by providing the concave portion 15a and the anchor portion 161a, the adhesion at the interface between the diaphragm 15 and the lower electrode 161 is achieved. Can be improved by the anchor effect, and film peeling and film floating of the lower electrode 161 can be prevented.

  Moreover, the recessed part 15a may be formed in the position which protrudes from the corner | angular part and peripheral part of the pattern of the lower electrode 161 (FIG. 13, FIG. 15). Moreover, the recessed part 15a may be provided in the inner side other than a peripheral part, if it is except the liquid chamber formation area 13a of the pattern of the lower electrode 161 (FIG. 16).

  Here, if the concave portion 15a and the anchor portion 16a are provided in the liquid chamber forming region 13a serving as the driving portion of the piezoelectric element 16, the characteristics of the piezoelectric element 16 cannot be fully utilized, and in the worst case, the structural local stress of the concave portion 15a. As a result, a crack is generated in the piezoelectric element 16, and there is a problem in reliability. For this reason, in the present embodiment, the concave portion 15a is provided in a region other than the liquid chamber forming region 13a serving as the driving portion of the piezoelectric element 16 to improve the adhesion between the lower electrode 161 and the diaphragm 15. It is.

  According to the electromechanical conversion member according to the present embodiment described above, the recess 15a is formed in the depth direction on the base of the lower electrode 161 in a region that is particularly easily peeled by the pattern of the lower electrode 161 and does not affect the liquid chamber 13. With the anchor effect, film peeling and film floating can be eliminated at the pattern corner and peripheral edge of the lower electrode 161 due to the anchor effect. Therefore, it is possible to improve the yield and obtain an electromechanical conversion member with high durability and reliability.

  In addition, since the actuator substrate 30 having excellent durability and reliability is applied to the droplet discharge head 1 including the electromechanical conversion member according to the present embodiment, the droplet is highly reliable and stable. A discharge head can be realized with high yield. Further, the present invention can be provided in a cartridge in which the droplet discharge head 1 is integrated or an ink jet recording apparatus in which the droplet discharge head 1 is mounted.

  Examples of the electromechanical conversion member according to the present invention and comparative examples will be described below.

<Example 1>
FIG. 8 is a cross-sectional view of the liquid droplet ejection unit 10 having the actuator substrate 30 according to the first embodiment in the liquid chamber short side length direction. FIGS. 9 to 11 are explanatory diagrams of the manufacturing process of the droplet discharge section 10.

  First, as shown in FIG. 9A, a silicon single crystal substrate (for example, plate thickness 400 [μm]) having a plane orientation (110) as a substrate 14 and a diaphragm 15 as a diaphragm constituting film, for example, LP A silicon oxide film, a polysilicon film, an amorphous silicon film, a silicon nitride film, or the like is formed by a CVD method so as to have a desired rigidity. At this time, the recess 15 a is formed in the depth direction of the diaphragm 15. Note that the diaphragm 15 may have a single-layer structure or a laminated structure as long as consistency with a subsequent process and a function as the diaphragm 15 are ensured.

  Next, as shown in FIG. 9B, a lower electrode 161 which is a common electrode made of Ti and Pt is formed by sputtering, for example, 30 [nm] and 100 [nm], respectively.

  At this time, the anchor electrode 161 a is formed by the layer of the lower electrode 161 entering the recess 15 a formed in the vibration plate 15. Note that the short side width of the recess 15 a is preferably set to a width equal to or less than ½ of the film thickness of the lower electrode 161 in consideration of the influence on the step in the subsequent process. As a result, the recess 15a is filled with the layer of the lower electrode 161, and no step is generated.

  Next, a PZT film having a thickness of 2 μm is formed as a piezoelectric body 162 on the lower electrode 161 by, for example, sputtering. Here, the film formation method of the piezoelectric body 162 is not limited to the sputtering method, and may be formed by, for example, an ion plating method, an air sol method, a sol gel method, an ink jet method, or the like. Further, an upper electrode 163 is formed on the piezoelectric body 162.

  Next, as shown in FIG. 9C, in order to form the piezoelectric element 16 at a position corresponding to the liquid chamber 13 to be formed later by the lithoetch method, the upper electrode 163 and the piezoelectric body 162 are separately patterned by the lithoetch method. . The etching at this time may be dry etching or wet etching. In the case of dry etching, etching may be performed with a chlorine-based gas or a fluorine-based gas as an ion milling method or reactive dry etching. Thereafter, the lower electrode 161 is similarly patterned by the lithoetch method (FIG. 10A).

Next, an opening for making contact with the subsequent upper electrode 163 is opened in the piezoelectric body 162 by a lithoetch method. Further, as shown in FIG. 10B, in order to ensure insulation between the lead-out wiring layer to the outside of the electrode and the upper electrode 163 and the lower electrode 161, a SiO ₂ film (second insulating protective film) is formed by plasma CVD. 18) is formed, for example, with a film thickness of 500 [um], and contact holes are formed for contacting the lead wiring with the upper electrode 163 and the lower electrode 161. Thereafter, in order to form the lead wiring and a layer (lead wiring layer 25) that becomes a part of the partition wall, for example, TiN / Al is formed into a film with a film thickness of 30 [nm] and 1 [um] by sputtering, A desired pattern is processed by a lithoetch method.

Next, as shown in FIG. 10C, an SiN film (third insulating protective film 19) is formed as a passivation film by plasma CVD, for example, with a film thickness of 1 [um]. Thereafter, the SiO ₂ film (second insulating protective film 18) and the SiN film (third insulating protective film 19) in the liquid chamber forming region 13a on the vibration plate 15 are removed by a lithoetch method.

  Further, the diaphragm constituting film at the location that becomes the common liquid chamber is removed by a litho-etching method. Next, the subframe 20 formed of, for example, a glass material in which the common droplet supply path, the droplet supply port, the protection space 20a, and the like are formed is joined to the actuator substrate 30 (FIG. 11A).

  The subframe 20 and the actuator substrate 30 may be joined by an adhesive or direct joining, but direct joining without using an adhesive is suitable.

  In this embodiment, a glass material is applied as the subframe 20, but a silicon single crystal substrate or the like may be used. In the case of using a silicon single crystal substrate, a common liquid droplet is supplied from a film having resistance such as a silicon oxide film or a silicon nitride film so that the substrate is not etched by etching for forming the liquid chamber 13 of the actuator substrate 30 later. It is necessary to form on the road inner wall and the substrate surface.

  Next, as shown in FIG. 11A, in order to form the liquid chamber 13, the common liquid chamber, and the fluid resistance portion, the substrate 14 has a desired thickness t (for example, a thickness of 80 [μm]). Further, polishing is performed by a known technique. Etching may be used in addition to the polishing method. Next, the partition walls other than the liquid chamber 13, the common liquid chamber, and the fluid resistance portion are coated with a resist, and then anisotropic etching is performed with an alkali solution (KOH solution or TMHA solution). A resistance portion is formed.

  Next, as shown in FIG. 11B, the nozzle substrate 12 having the nozzles 11 opened is joined to the positions corresponding to the liquid chambers 13 to complete the droplet discharge section 10. In the manufacturing process of the droplet discharge unit 10, the processes after manufacturing the diaphragm 15 and the piezoelectric element 16 are not particularly limited, and may be manufactured by a known manufacturing process.

  FIG. 12 is a top view after patterning of the lower electrode 161 of the piezoelectric element 16 in the first embodiment. As shown in FIG. 12, a recess 15 a is provided at a position other than the liquid chamber forming region 13 a of the vibration plate 15 at a position corresponding to a corner (four corners) of the pattern of the lower electrode 161, and the lower electrode 161 is formed. By forming the anchor portion 161a that sometimes enters the concave portion 15a, the lower electrode 161 can increase the adhesion with the surface layer of the diaphragm 15 that is the base layer due to the effect as an anchor, and the film Peeling and film floating can be prevented.

<Example 2>
In the following description of the embodiment, the description of the same points as in the first embodiment will be omitted. In the second embodiment, as shown in FIG. 13, the recess 15 a is provided so as to protrude from the pattern at a position corresponding to the corner (four corners) of the pattern of the lower electrode 161.

  According to Example 2, the anchor effect can be ensured even when the positional relationship between the recess 15a and the end of the pattern of the lower electrode 161 is shifted, a stable anchor effect can be obtained, and film peeling or film floating can be achieved. On the other hand, a stable effect with a sufficient margin can be obtained.

<Example 3>
In Example 3, as shown in FIG. 14, the concave portions 15a are formed in a rectangular cubic shape and arranged along the peripheral edge portion of the lower electrode 161 pattern.

  According to the third embodiment, the concave portion 15a in which the anchor effect can be obtained is arranged all over the peripheral portion of the lower electrode 161 where film peeling or film floating is likely to occur. Film floating can be effectively prevented.

<Example 4>
In Example 4, as shown in FIG. 15, the recesses 15a are arranged along the peripheral edge of the lower electrode 161 pattern, and are provided so as to protrude from the peripheral edge of the pattern.

  According to the fourth embodiment, when the positional relationship between the recess 15a and the end of the pattern of the lower electrode 161 is deviated, the film peeling and film floating can be effectively prevented as compared with the case where it is arranged only at the corner. However, the anchor effect can be ensured.

<Example 5>
In the fifth embodiment, as shown in FIG. 16, the recesses 15a are arranged along the peripheral edge of the lower electrode 161 pattern, and are also provided at locations other than the liquid chamber forming region 13a on the inner side.

  According to the fifth embodiment, the anchor effect is obtained not only in the peripheral portion of the lower electrode 161 but also in a region other than the liquid chamber forming region 13a on the inner side. The effect of preventing film peeling and film floating can be obtained.

  According to the first to fifth embodiments, it can be confirmed that the adhesion between the lower electrode 161 and the diaphragm 15 can be increased to prevent film peeling and film floating compared to the conventional configuration in which the concave portion 15a and the anchor portion 161a are not formed. It was. In addition, according to Examples 2 to 5, it was confirmed that the anchor effect was further improved compared to Example 1, and the adhesion between the lower electrode 161 and the diaphragm 15 was increased to further prevent film peeling and film floating. did it.

(ink cartridge)
Next, an ink cartridge provided with the droplet discharge head 1 according to the present embodiment will be described.

  FIG. 17 is a perspective view illustrating a configuration example of an ink cartridge including the droplet discharge head 1. The ink cartridge 90 is obtained by integrating the above-described droplet discharge head 1 (inkjet head) having the nozzles 11 and the like, and an ink tank 91 that supplies ink to the droplet discharge head 1.

  When the droplet discharge head 1 and the ink tank 91 are integrated, the cost reduction and reliability improvement of the droplet discharge head 1 immediately lead to cost reduction and reliability improvement of the entire ink cartridge 90. Therefore, by reducing the cost, increasing reliability, and reducing manufacturing defects of the droplet discharge head 1, the yield and reliability of the ink cartridge 90 are improved, and the cost of the ink cartridge 90 integrated with the head is reduced. Can be planned.

(Image forming device)
Next, an ink jet recording apparatus which is an image forming apparatus provided with the droplet discharge head 1 according to the present embodiment will be described.

  FIG. 18 is a perspective view showing a configuration example of an ink jet recording apparatus equipped with a droplet discharge head, and FIG. 19 is a side view showing a configuration example of a mechanism section of the recording apparatus.

  The ink jet recording apparatus 100 houses a printing mechanism 103 and the like inside the apparatus main body, and may be a paper feed cassette (or a paper feed tray) on which a large number of recording sheets 130 can be stacked from the front side in the lower part of the apparatus main body. ) 104 is removably mounted. Further, it has a manual feed tray 105 that is opened to manually feed the recording paper 130. The recording paper 130 fed from the paper feed cassette 104 or the manual feed tray 105 is taken in, a required image is recorded by the printing mechanism unit 103, and then discharged to the paper discharge tray 106 mounted on the rear side.

  The printing mechanism 103 includes a carriage 101 that can move in the main scanning direction, a droplet discharge head mounted on the carriage 101, an ink cartridge 102 that supplies ink to the droplet discharge head, and the like. Further, the printing mechanism 103 holds the carriage 101 slidably in the main scanning direction with a main guide rod 107 and a sub guide rod 108 which are guide members horizontally mounted on left and right side plates (not shown). The carriage 101 includes a droplet discharge head that discharges yellow (Y), cyan (C), magenta (M), and black (Bk) ink droplets, and a plurality of ink discharge ports (nozzles) in the main scanning direction. They are arranged in the intersecting direction and mounted with the ink droplet ejection direction facing downward. In addition, each ink cartridge 102 for supplying ink of each color to the droplet discharge head is replaceably mounted on the carriage 101.

  The ink cartridge 102 is provided with an air opening communicating with the atmosphere above, and a supply opening for supplying ink to the droplet discharge head below. The ink cartridge 102 has a porous body filled with ink, and the ink supplied to the droplet discharge head is maintained at a slight negative pressure by the capillary force of the porous body. Further, although the droplet discharge heads of the respective colors are used as the droplet discharge heads, one droplet discharge head having nozzles for discharging the ink droplets of the respective colors may be used.

  Here, the carriage 101 is slidably fitted on the main guide rod 107 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 108 on the front side (upstream side in the paper conveyance direction). ing. In order to move and scan the carriage 101 in the main scanning direction, a timing belt 112 is stretched between a driving pulley 110 and a driven pulley 111 that are rotationally driven by a main scanning motor 109, and the timing belt 112 is attached to the carriage 101. It is fixed to. As a result, the carriage 101 is driven to reciprocate by forward / reverse rotation of the main scanning motor 109.

  On the other hand, in order to convey the recording paper 130 set in the paper feeding cassette 104 to the lower side of the droplet discharge head, a paper feeding roller 113 and a friction pad 114 for separating and feeding the recording paper 130 from the paper feeding cassette 104, and recording And a guide member 115 for guiding the paper 130. Further, a conveyance roller 116 that reverses and conveys the fed recording paper 130, a conveyance roller 117 that is pressed against the peripheral surface of the conveyance roller 116, and a leading roller that defines the feeding angle of the recording paper 130 from the conveyance roller 116. 118. The transport roller 116 is rotationally driven through a gear train by a sub-scanning motor.

  In addition, a printing receiving member 119 that is a paper guide member is provided to guide the recording paper 130 fed from the transport roller 116 corresponding to the range of movement of the carriage 101 in the main scanning direction on the lower side of the droplet discharge head. Yes. On the downstream side of the printing receiving member 119 in the paper conveyance direction, a conveyance roller 120 and a spur 121 that are rotationally driven to send the recording paper 130 in the paper discharge direction are provided. Further, a discharge roller 123 and a spur 124 for feeding the recording paper 130 to the discharge tray 106, and guide members 125 and 126 for forming a discharge path are provided.

  At the time of recording with the ink jet recording apparatus 100, the droplet discharge head is driven in accordance with the image signal while moving the carriage 101, whereby ink is discharged onto the stopped recording paper 130 to record one line. Thereafter, the recording paper 130 is conveyed by a predetermined amount, and then the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the recording paper 130 reaches the recording area, the recording operation is terminated and the recording paper 130 is discharged.

  Further, a recovery device 127 for recovering the ejection failure of the droplet ejection head is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 101. The recovery device 127 includes a cap unit, a suction unit, and a cleaning unit. During printing standby, the carriage 101 is moved to the recovery device 127 side, and the droplet ejection head is capped by the capping unit to keep the ejection port portion in a wet state, thereby preventing 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 droplet discharge head 1 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. In this way, ink or dust adhering to the ejection port surface is removed by the cleaning means, and the ejection failure is recovered. The sucked ink is discharged to a waste ink reservoir installed at the lower part of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir. As described above, since the inkjet recording apparatus 100 of the present embodiment includes the recovery device 127, the ejection failure of the droplet ejection head is recovered, stable ink droplet ejection characteristics are obtained, and the image quality is improved. be able to.

  In this embodiment, the case where a droplet discharge head is used in the inkjet recording apparatus 100 has been described. However, the droplet discharge head 1 is applied to a device that discharges droplets other than ink, for example, a liquid resist for patterning. May be.

  As described above, since the ink jet recording apparatus (image forming apparatus) 100 according to the present embodiment includes the liquid discharge head according to the present invention as a recording head, stable ink droplet discharge characteristics can be obtained, and high-quality images can be stably displayed. Can be formed.

  In the ink jet recording apparatus, an image is formed by adhering ink droplets to a sheet by a droplet discharge head while conveying a medium. The medium here is also referred to as “paper”, but the material is not limited, and a recording medium, a recording medium, a transfer material, a recording paper, and the like are also used synonymously. The image forming apparatus means an apparatus for forming an image by ejecting liquid droplets on a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, or ceramic. The image formation is not only giving an image having a meaning such as a character or a figure to the medium but also giving an image having no meaning such as a pattern to the medium (simply ejecting a droplet). Also means. The ink is not limited to so-called ink, and is not particularly limited as long as it becomes a droplet when ejected. For example, the ink is a generic term for liquids including DNA samples, resists, pattern materials, and the like. Used as

  Further, the image forming apparatus includes both a serial type image forming apparatus and a line type image forming apparatus, unless otherwise limited.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, the present invention can be applied to a micropump including a piezoelectric actuator, a microactuator, and other optical devices.

DESCRIPTION OF SYMBOLS 1 Droplet discharge head 10 Droplet discharge part 11 Nozzle 12 Nozzle substrate 13 Liquid chamber 13a Liquid chamber formation area 14 Liquid chamber substrate 15 Diaphragm 15a Recess 16 Piezoelectric element 161 Lower electrode 161a Anchor part 162 Piezoelectric body 163 Upper electrode 17 1st Insulating protective film 17a Contact hole 18 Second insulating protective film 18a Contact hole 19 Third insulating protective film 20 Subframe 20a Protective spaces 21, 22 Wiring 23 Pad electrode 24 Driving IC
25 Lead-out wiring layer 30 Actuator substrate 32 Fluid resistance portion 33 Ink introduction path 34 Ink supply port 35 Ink flow path 90 Ink cartridge 100 Inkjet recording apparatus

JP 2006-239966 A JP 2006-231790 A

Claims (9)

A diaphragm forming one surface of the liquid chamber;
An electromechanical transducer having a lower electrode, a piezoelectric body, and an upper electrode formed in this order on the diaphragm;
In the electromechanical conversion member that is a common electrode of the electromechanical conversion element by continuously providing the lower electrode over the direction in which the liquid chambers are arranged in parallel,
An electromechanical conversion member characterized in that a recess is formed in a depth direction of the diaphragm at a position other than the liquid chamber formation region of the diaphragm, and the lower electrode has a shape that enters the recess. .   The electromechanical conversion member according to claim 1, wherein the concave portion is formed at a corresponding position of a corner portion of the pattern of the lower electrode.   The electromechanical conversion member according to claim 1, wherein the concave portion is formed along a corresponding position of a peripheral edge portion of the pattern of the lower electrode.   The electromechanical conversion member according to claim 2, wherein the recess is formed at a position protruding from a peripheral edge of the pattern of the lower electrode.   The said recessed part is formed in positions other than the said peripheral part of the pattern of the said lower electrode, and the formation area of the said liquid chambers other than the said peripheral part. Electromechanical conversion member. A diaphragm forming one surface of the liquid chamber;
An electromechanical transducer having a lower electrode, a piezoelectric body, and an upper electrode formed in this order on the diaphragm;
In the method of manufacturing an electromechanical conversion member, the lower electrode is continuously provided in a direction in which the liquid chambers are arranged side by side, and becomes a common electrode of the electromechanical conversion element.
Forming a recess in the depth direction of the diaphragm at a position other than the formation region of the liquid chamber of the diaphragm;
Forming a film of the lower electrode into the shape of the recessed portion, and a method for producing an electromechanical conversion member. A liquid chamber communicating with a nozzle for discharging droplets;
A substrate for forming the liquid chamber so that the liquid in the liquid chamber can be pressurized;
An electromechanical conversion member provided on the substrate;
In a droplet discharge head having
A droplet discharge head using the electromechanical conversion member according to claim 1 as the electromechanical conversion member. A droplet discharge head;
In an ink cartridge integrated with an ink tank for supplying ink to the droplet discharge head,
An ink cartridge using the droplet discharge head according to claim 7 as the droplet discharge head. In an image forming apparatus that forms an image by discharging droplets from a droplet discharge head,
An image forming apparatus using the droplet discharge head according to claim 7 as the droplet discharge head.