JP6112401B2 - Electromechanical conversion element manufacturing method and electromechanical conversion element manufacturing apparatus - Google Patents

Description

The present invention relates to a manufacturing method and equipment of the electromechanical transducer.

  In recent years, ink jet recording apparatuses used as image recording apparatuses or image forming apparatuses such as printers, facsimiles, and copying apparatuses have been widely used. In this ink jet recording apparatus, a droplet discharge head is used as means for discharging a recording material such as ink. FIG. 1 is a cross-sectional view showing an example of a droplet discharge head. In FIG. 1, a droplet discharge head 10 includes a nozzle 11 that discharges ink droplets, and a pressure chamber 12 that communicates with the nozzle 11 (also referred to as an ink flow path, a pressurized liquid chamber, a pressure chamber, a discharge chamber, and a liquid chamber). ). Further, an electromechanical conversion element (piezoelectric element) 16 having an electromechanical conversion film 13, an upper electrode 14, and a lower electrode 15 that pressurizes ink in the pressurizing chamber 12 is provided. In addition, instead of the electromechanical conversion element 16, an electrothermal conversion element such as a heater, or one using a diaphragm forming a wall surface of the pressurizing chamber 12 and an electrode facing the diaphragm is known. Ink droplets are ejected from the nozzle 11 by pressurizing the ink in the pressurizing chamber 12 by the electromechanical transducer 16.

  There are two types of droplet discharge heads using the electromechanical transducer 16: one using a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of the piezoelectric element, and one using a flexural vibration mode piezoelectric actuator. Has been put to practical use. For example, a piezoelectric material layer using a flexural vibration mode is formed by a film forming technique over the entire surface of the diaphragm. A known piezoelectric element layer is formed by cutting the piezoelectric material layer into a shape corresponding to the pressure generating chamber by lithography and forming the piezoelectric material independently of each pressure generating chamber. For example, the piezoelectric element used in the actuator of the flexural vibration mode includes a lower electrode that is a common electrode, an electromechanical conversion film formed of, for example, a PZT film on the lower electrode, and an individual electrode formed on the PZT film. What is comprised with the upper electrode which is an electrode is known.

  Further, in Patent Documents 1 and 2, an interlayer insulating film is formed on the upper electrode to insulate the lower electrode from the upper electrode, and the upper electrode is connected to the upper electrode through a contact hole opened in the interlayer insulating film. A structure in which wirings to be electrically connected are provided is disclosed.

  As the lower electrode, a metal electrode mainly based on Pt is often used. However, in this case, there is a concern that the fatigue characteristics of PZT are reduced. Generally, characteristic deterioration due to Pb diffusion contained in PZT is considered, and it is said that fatigue characteristics are improved by using an oxide electrode (see Patent Document 3).

  Here, FIG. 2A shows a schematic diagram of the polarization state of the piezoelectric crystal used in the droplet discharge head before voltage application, and FIG. 2B shows a schematic diagram of the polarization state after voltage application is repeated. Each is shown. In the figure, the arrows indicate the directions of domain polarization separated by straight lines.

  As shown in FIG. 2 (a), the piezoelectric crystal is in a state of random polarization immediately before voltage application (before polarization treatment), but polarization treatment is performed by repeating voltage application, and FIG. ) As a group of domains with the same polarization direction.

  For this reason, attempts have been made to align the direction of polarization before voltage application, and efforts have been made to stabilize the amount of displacement with respect to a predetermined drive voltage referred to as an aging process or a poling (polarization process) process. (See Patent Documents 4 and 5). Specifically, a technique is applied in which a high voltage exceeding the drive pulse voltage is applied to the piezoelectric element. Further, a device has been devised in which a voltage is applied between the electrode and the charge supply means to generate a corona discharge, thereby supplying a charge and generating an electric field in the piezoelectric body (see Patent Document 6).

  For example, when processing is performed by applying a drive pulse voltage as described in Patent Documents 4 and 5, for example, processing can be performed at a wafer level using a probe card or the like. However, depending on the number and arrangement of terminal electrodes arranged, there is a problem that the production of the probe card is expensive. Further, when the number of terminal electrodes that can be processed by one probe card is small, there is a problem that it takes a considerable time to process at the wafer level.

  Further, in Patent Document 6 described above, the poling process is performed using the corona wire after the piezoelectric film is formed. However, due to the heat history in the subsequent process such as the interlayer film formation and the lead-out wiring formation after the poling process, etc. May depolarize. Specifically, for example, by giving a thermal history exceeding 300 [° C.] after processing, the state before processing is restored. In other words, the amount of displacement with respect to the predetermined drive voltage may not be stable when the droplet discharge head is used despite the polling process.

  FIG. 3 is a hysteresis curve showing the relationship between the electric field strength of the piezoelectric body and the polarization amount before the polarization treatment, after the polarization treatment, and after giving a thermal history exceeding 300 [° C.]. As shown in the hysteresis curve of FIG. 3, when an electric field is applied to the ferroelectric substance from the outside, polarization rapidly proceeds and saturates. Thereafter, the magnitude of the polarization does not become zero even if the electric field strength is reduced and the electric field is zero. This zero state is the remanent polarization Pr. However, if a thermal history exceeding 300 [° C.] is applied after the polarization treatment, it is depolarized and returns to the state before the polarization treatment.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromechanical conversion element capable of reliably performing a polarization process of an electromechanical conversion film and preventing depolarization after the polarization process. it is to provide a manufacturing method and manufacturing equipment of.

  In order to achieve the above object, the invention of claim 1 includes a step of forming a first drive electrode on a substrate or a base film, an electromechanical conversion film on the first drive electrode, and the electromechanical conversion film. Forming a second driving electrode located above; forming a first insulating protective film on the second driving electrode; and wiring electrically connected to the second driving electrode Forming on the first insulating protective film, forming a second insulating protective film which is a film formed on the wiring and which exposes a terminal electrode connected to the wiring, and the terminal By using a conductive member having a contact portion corresponding to the electrode, bringing the contact portion of the conductive member into contact with the terminal electrode, and injecting a charge generated by corona discharge or glow discharge into the conductive member, Polarizing the electromechanical conversion film A step, is characterized in that it has a.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to perform the polarization process of an electromechanical conversion film reliably, the depolarization after a polarization process can be prevented.

FIG. 3 is a schematic sectional view of a droplet discharge head. (A), (b) is a schematic diagram of the polarization state of the piezoelectric crystal before and after voltage application. The hysteresis curve which shows the relationship between the electric field strength of a piezoelectric material, and the amount of polarization before a polarization process, after a polarization process, and after giving the thermal history over 300 [degreeC]. Sectional drawing of the electromechanical transducer which concerns on one Embodiment of this invention. It is explanatory drawing of a structure of the same electromechanical conversion element, (a) is sectional drawing, (b) is a top view. It is explanatory drawing at the time of performing a polarization process using a conductor plate, (a) is sectional drawing, (b) is a top view. Explanatory drawing of a polarization process. It is a graph explaining a polarizability, (a) is a hysteresis loop about what has not performed polarization processing, and (b) is a hysteresis loop about what performed polarization processing. On a silicon substrate was deposited a titanium oxide film and a platinum film, a graph showing a SrRuO ₃ film X-ray diffraction measurement results of the samples was deposited. The graph which compares the electromechanical conversion element each produced by Example 1 and the comparative example 1. FIG. Sectional drawing which shows an example of a structure of a droplet discharge head. FIG. 3 is a perspective view illustrating an example of a configuration of a droplet discharge device according to the present embodiment. The side view of the mechanism part of the droplet discharge device.

Hereinafter, modes for carrying out the invention will be described with reference to the drawings, but the present invention is not limited to these examples.
In the present embodiment, an example of a method for manufacturing an electromechanical transducer of the present invention and an electromechanical transducer obtained thereby will be described.

First, a configuration example of the electromechanical transducer according to this embodiment will be described.
FIG. 4 is a cross-sectional view schematically showing the electromechanical transducer according to this embodiment. As shown in FIG. 4, the electromechanical transducer (piezoelectric element) 30 includes a first drive electrode 33, an electromechanical transducer film 34, and a second drive on a substrate 31 and a film formation diaphragm (base film) 32. The electrode 35 is laminated.

  Further, the structure of the electromechanical conversion element including the insulating protective film and the lead-out wiring will be described with reference to FIG. 5A is a cross-sectional view, FIG. 5B is a top view, and FIG. 5B is a perspective view of a part of the second insulating protective film so that the configuration of the piezoelectric element can be seen. It is described. FIGS. 6A and 6B are explanatory diagrams of a configuration in which electric charges generated by corona discharge or glow discharge are injected into the electromechanical transducer using a conductor plate, where FIG. 6A is a cross-sectional view and FIG. 6B is a top view. 5 and 6, the same members as those in FIG. 4 are denoted by the same reference numerals.

  In the electromechanical conversion element shown in FIG. 5, the first drive electrode 33, the electromechanical conversion film 34, and the second drive electrode 35 are provided on the substrate 31 and the film formation diaphragm 32 as in the case of FIG. 4. Are stacked. The electromechanical conversion film 34 and the second drive electrode 35 are individualized by etching after the second drive electrode is formed. The second drive electrode functions as an individual electrode, and the first drive electrode 33 functions as a common electrode for the individualized electromechanical conversion film 34 and the second drive electrode 35.

  On the first drive electrode 33 and the second drive electrode 35, a first insulating protective film 41 having a contact hole 45 is provided as shown in FIG. 5B. The contact hole 45 is provided so that the first drive electrode 33 and the second drive electrode 35 can be electrically connected to a first wiring 42 and a second wiring 43 described later. . Then, a first wiring 42 and a second wiring 43 are provided on the first insulating protective film 41, and through the contact hole 45 provided in the first insulating protective film 41 as described above. Thus, each is electrically connected to the first drive electrode 33 and the second drive electrode 35.

  Further, the common electrode and the individual electrode are protected by using the first drive electrode 33 and the first wiring 42 conducting to the common electrode as the common electrode, and the second driving electrode 35 and the second wiring 43 conducting to the individual electrode as the individual electrodes. A second insulating protective film 44 is formed. The second insulating protective film 44 is formed on the first wiring 42 and the second wiring 43 (and further on the first insulating protective film 41). The second insulating protective film 44 is provided with a plurality of openings 48 and 49 to expose the common electrode pad 46 as the first terminal electrode and the individual electrode pad 47 as the second terminal electrode. ing.

  Among the plurality of pads, those prepared for the common electrode, that is, those connected to the common electrode are the common electrode pads 46, and those prepared for the individual electrodes, ie, those connected to the individual electrodes are individually The electrode pad 47 is used. As described above, these pads can be exposed to the outside by providing openings 48 and 49 in the second insulating protective film 44, for example.

  The electromechanical transducer having the above-described configuration can be manufactured by performing the following steps.

  A step of forming the first drive electrode 33 on the substrate 31 or the base film (deposition diaphragm) 32. Here, the first drive electrode 33 may include an adhesion layer as described later.

  Forming an electromechanical conversion film on the first drive electrode 33;

  Forming a second drive electrode 35 on the electromechanical conversion film 34;

  A step of individualizing the electromechanical conversion film 34 and the second drive electrode 35 by etching; By performing this process, the second drive electrode 35 is used as an individual electrode, and the first drive electrode 33 functions as a common electrode for the individualized electromechanical conversion film 34 and the second drive electrode 35. become.

  Forming a first insulating protective film 41 on the first drive electrode 33 and the second drive electrode 35;

  At this time, the first insulating protective film 41 is contacted to electrically connect the first driving electrode 33 and the second driving electrode 35 to a first wiring 42 and a second wiring 43 which will be described later. Holes 45 can be formed.

  Forming a first wire and a second wire 43 electrically connected to the first drive electrode 33 and the second drive electrode 35 on the first insulating protective film 41, respectively;

  A step of forming a second insulating protective film 44 having a plurality of pads 46 and 47 for connecting to the first wiring 42 or the second wiring 43 on the first wiring 42 and the second wiring 43. .

  Here, the first wiring 42 and the second wiring 43 can be manufactured as separate processes in the above steps, but are preferably formed in the same process from the viewpoint of productivity.

  Further, the plurality of pads 46 and 47 can be exposed to the outside by providing openings in the second insulating protective film 44.

And in the manufacturing method of the electromechanical transducer 30 according to the present embodiment, as shown in FIG. 6A, the conductor plate 20 described later as a conductive member is connected to the individual electrode pad 47 from the opening 49, Corona discharge or glow discharge is performed on that part. This discharge generates a charge amount of 1.0 × 10 ⁻⁸ [C] or more, and performs a polarization process by injecting the generated charge through the pad.

  In the step of performing the polarization treatment, a charge amount greater than the predetermined amount is generated by corona discharge or glow discharge, and the generated charge is injected into the electromechanical conversion film 34 through the plurality of individual electrode pads 47. Is. At this time, it is preferable that the charge generated by corona discharge or glow discharge is positively charged.

  For example, as shown in FIG. 7, when corona discharge is performed using a corona wire 52 as a discharge electrode, positive ions are generated by ionizing molecules in the atmosphere. This cation flows into the electromechanical conversion element 30 from the contact portion 20a of the conductor plate 20 via the individual electrode pad 47 of the electromechanical conversion element 30 installed on the stage 53, and accumulates positive charge. Then, polarization processing of the electromechanical conversion film 34 is performed. A grid electrode as a discharge control electrode may be disposed between the corona wire 52 and the conductor plate 20, and a voltage for discharge control may be applied to the grid electrode.

Here, considering the charge amount Q required for the polarization treatment, it is preferable that a charge amount of 1.0 × 10 ⁻⁸ [C] or more is accumulated (generated), and 4.0 × 10 ⁻⁸ [C]. More preferably, the above charge amount is accumulated (generated). If the amount of charge is less than the above value, the polarization process may not be performed sufficiently, and sufficient characteristics cannot be obtained with respect to displacement degradation after continuous driving as an electromechanical conversion film 34, for example, a PZT piezoelectric actuator. This is because there are cases.

  In the step of performing the polarization treatment, the produced electromechanical transducer (piezoelectric element) 30 is subjected to corona discharge or glow discharge using the conductor plate 20, and the generated charges are passed through the pads 46 and 47. By injecting, polarization treatment is performed.

  Here, the state of polarization processing can be determined from the PE hysteresis loop.

  FIG. 8A shows the hysteresis loop measured for the sample not subjected to the polarization processing described in FIG. 2, and FIG. 8B shows the hysteresis loop measured for the polarization treatment.

  As shown in FIGS. 8A and 8B, a hysteresis loop is measured with an electric field strength of ± 150 [kV / cm]. The initial polarization at 0 [kV / cm] is Pini, and the polarization at 0 [kV / cm] when the voltage is returned to 0 [kV / cm] after applying a voltage of +150 [kV / cm] is Pr.

At this time, the difference between Pr and Pini, that is, the value of Pr−Pini is defined as the polarizability, and whether the polarization state is good or bad can be determined from this polarizability. Here, as shown in FIG. 8B, the polarizability Pr-Pini is preferably 10 [μC / cm ² ] or less, and more preferably 5 [μC / cm ² ] or less. preferable. This is because, when the value is less than this value, sufficient characteristics may not be obtained with respect to displacement degradation after continuous driving as a piezoelectric actuator of the electromechanical conversion film 34, for example, PZT.

That is, the electromechanical transducer 30 obtained by the manufacturing method described above measures a hysteresis loop by applying an electric field strength of ± 150 [kV / cm]. The polarization at 0 [kV / cm] at the start of measurement is Pini, and the polarization at 0 [kV / cm] when the voltage is returned to 0 [kV / cm] after applying a voltage of +150 [kV / cm] is Pr. To do. In this case, the difference between Pr and Pini is preferably 10 [μC / cm ² ] or less, and more preferably 5 [μC / cm ² ] or less.

  Further, in the electromechanical conversion element 30 obtained by the manufacturing method described above, the relative dielectric constant of the electromechanical conversion film 34 is preferably 600 or more and 2000 or less.

  Below, the material and construction method which comprise the electromechanical conversion element of this embodiment are demonstrated concretely.

(substrate)
The material of the substrate 31 is not particularly limited, but a silicon single crystal substrate is preferably used. The thickness is preferably 100 to 600 [μm].

  There are three types of plane orientation of the silicon single crystal substrate, (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry. In this configuration, a silicon single crystal substrate having a (100) plane orientation can be preferably used. In the electromechanical transducer 30 in the present embodiment, a single crystal substrate having a (110) plane orientation can also be preferably used.

  When the pressure chamber shown in FIG. 1 is manufactured on the substrate 31, the silicon single crystal substrate is generally processed by using etching. In this case, anisotropic etching is used as an etching method. It is common.

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. Accordingly, a structure having an inclination of about 54 [°] can be produced in the plane orientation (100), whereas a deep groove can be dug in the plane orientation (110), so that the arrangement density can be maintained while maintaining rigidity. Can be high. For this reason, when producing a pressure chamber etc. using anisotropic etching, it is also possible to use a silicon single crystal substrate having a (110) plane orientation. However, in this case, SiO ₂ which is a mask material may be etched, so that it is desirable to use this in consideration.

(Undercoat (diaphragm))
As shown in FIG. 1, under the force generated by the electromechanical conversion film 13, the base film (vibration plate) 17 is deformed and displaced, and ink droplets in the pressure chamber 12 are ejected. Therefore, it is preferable that the base film 17 has a predetermined strength.

The material constituting the base film 17 may be any material that can be deformed and displaced to discharge the ink droplets in the pressure chamber 12 and can be arbitrarily selected according to required durability. SiO ₂ and Si 3 N 4 can be used. When these materials are used, they can be manufactured by a CVD method.

Further, it is preferable to select a material close to the linear expansion coefficient of the first drive electrode (lower electrode) 15 and the electromechanical conversion film 13 as the base film (vibration plate) 17. In particular, as the electromechanical conversion film 13, since PZT is generally used as a material, a film having a linear expansion coefficient close to 8 × 10 ⁻⁶ (1 / K) of PZT is preferable. Specifically, the material preferably has a linear expansion coefficient in the range of 5 × 10 ⁻⁶ (1 / K) to 10 × 10 ⁻⁶ (1 / K), and more preferably 7 × 10 ^−6. A material having a linear expansion coefficient in the range of (1 / K) to 9 × 10 ⁻⁶ (1 / K) is more preferable.

  In this case, specific materials 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 manufactured by a spin coater using a sputtering method or a sol-gel method.

  The film thickness is not particularly limited, but 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 may be difficult to process the pressure chamber 12 as shown in FIG. 1, and if it is larger than this range, the underlying film 17 will not be easily deformed and displaced, and ink droplet ejection may become unstable. It is.

(First drive electrode)
For example, the first drive electrode 15 shown in FIG. 1 is not particularly limited, but is preferably made of a metal or a metal and an oxide. Specifically, the first drive electrode 15 can be composed of a metal electrode film, for example. Moreover, it can also be comprised from a metal electrode film and an oxide electrode film.

  Even when the first drive electrode 15 is made of any material, it is preferable to devise an adhesive layer between the diaphragm 17 and the metal film so as to suppress peeling and the like. Details of the metal electrode film and oxide electrode film including the adhesion layer are described below.

The adhesion layer can be obtained, for example, by forming a metal film and then oxidizing it (thermal oxidation) by an RTA method using an RTA (rapid thermal annealing) device to form an oxide film. Conditions for the oxidation (thermal oxidation) are not particularly limited, and can be selected depending on the material of the metal film to be used. For example, it can be formed by thermally oxidizing a metal film at 650 to 800 [° C.] for 1 to 30 minutes in an O ₂ atmosphere.

  The metal film can be formed by sputtering, for example. As a material for the metal film, materials such as Ti, Ta, Ir, and Ru can be preferably used, and among these, Ti can be preferably used.

  The metal oxide film may be formed by reactive sputtering, but a thermal oxidation method at a high temperature of the metal film is desirable. This is because, when manufacturing by reactive sputtering, for example, a substrate such as a silicon substrate needs to be heated together at a high temperature, so that a special sputtering chamber configuration is required, which is not preferable in terms of cost. In addition, the crystallinity of the metal oxide film is improved by the oxidation by the RTA apparatus than by the oxidation by a general furnace. This is explained by taking a titanium film as an example. According to oxidation by a normal heating furnace, a titanium film that is easily oxidized forms a number of crystal structures at a low temperature, so that it is necessary to break it once. On the other hand, in the oxidation by the RTA method having a high temperature rising rate, it is not necessary to go through such a process, and it becomes possible to form a good crystal.

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

  Conventionally, platinum having high heat resistance and low reactivity can be used as the metal material of the metal electrode film. In addition, since platinum may not have sufficient barrier properties with respect to lead, platinum group elements such as iridium and platinum-rhodium, and alloys thereof can also be used.

In addition, when platinum is used as the metal material of the metal electrode film, it is preferable that the adhesion layer is laminated first because adhesion to the base (particularly SiO ₂ ) is poor.

  The method for producing the metal electrode film is not particularly limited, but vacuum film formation such as sputtering or vacuum deposition can be used.

  The thickness of the metal electrode film may be selected according to the required performance, and is not limited, but is preferably 80 [nm] to 200 [nm], for example, 100 [nm] to 150 [Nm] is more preferable. When the thickness is smaller than the above range, it may not be possible to supply a sufficient current as the common electrode, and a problem may occur when ink is ejected. In addition, when the thickness is larger than the above range, particularly when an expensive material of a platinum group element is used as the metal material of the metal electrode film, there is a problem in terms of cost. In particular, when platinum is used as the metal material, the surface roughness increases when the film thickness is increased. Then, when a defect occurs that affects the surface roughness and crystal orientation of the film (for example, an oxide electrode film or an electromechanical conversion film) to be formed thereon and sufficient displacement cannot be obtained for ink ejection. There is.

As a material for the oxide electrode film, it is preferable to use strontium ruthenate (SrRuO ₃ , hereinafter also simply referred to as “SRO”). The material obtained by replacing a part of strontium ruthenate, specifically, SrxA1-xRuyB1-yO ₃ (wherein, A is Ba, Ca, B is Co, Ni, x, y = 0~0.5) The material represented by can also be preferably used.

  The oxide electrode film can be formed by sputtering, for example. Although the sputtering conditions are not limited, the film quality of the oxide film changes depending on the sputtering conditions, and can be selected according to the required crystal orientation.

  For example, the electromechanical conversion film 34 to be described later is preferably oriented in the (111) plane orientation as its crystallinity in order to suppress deterioration of displacement characteristics when continuously operated. In order to obtain such an electromechanical conversion film 34, it is preferable that the oxide electrode film disposed in the lower layer is also oriented in the (111) plane direction. For this reason, the oxide electrode film is preferably preferentially oriented in the (111) plane orientation.

  Then, in order to obtain a film preferentially oriented in the (111) plane orientation with respect to the oxide electrode film, it is preferable to heat the substrate to 500 [° C.] or higher, and form the oxide electrode film thereon by sputtering.

  Moreover, when providing a metal electrode film in the lower layer of an oxide electrode film, it is preferable that this metal electrode film consists of a platinum film. Moreover, it is preferable that it is oriented in the (111) plane orientation as the plane orientation. This is because it is easy to obtain an oxide electrode film formed thereon that is preferentially oriented in the (111) plane orientation.

  For example, Patent Document 7 states that the SRO film is formed by depositing SRO at room temperature and then thermally oxidizing it at the crystallization temperature by RTA treatment. In this case, the SRO film is sufficiently crystallized and a sufficient value is obtained as a specific resistance as an electrode. However, as the crystal orientation of the film, (110) is likely to be preferentially oriented. When a PZT film is formed, this PZT film is also easily (110) oriented. For this reason, when forming the SRO film in the present embodiment, it is preferable to form the film under the above film forming conditions.

Here, for example, when a platinum film oriented in the (111) plane direction is used as a metal electrode film, and an SrRuO ₃ film as an oxide electrode film is formed thereon, the crystallinity of the oxide electrode is measured by X-ray diffraction measurement. The method of evaluation will be described.

Since Pt and SrRuO ₃ have close lattice constants, in the θ-2θ measurement in the normal X-ray diffraction measurement, the 2θ positions of the (111) plane of the SRO film and the (111) plane of Pt overlap and are difficult to discriminate. However, when Pt is tilted to Psi = 35 [°] due to the extinction law, the diffraction lines cancel each other at a position where 2θ is about 32 [°], and the diffraction intensity of Pt cannot be seen. Therefore, it is possible to confirm whether the SRO is preferentially oriented in the (111) plane orientation by inclining the Psi direction by about 35 [°] and judging from the peak intensity where 2θ is about 32 [°].

In FIG. 9, after forming a titanium oxide film as an adhesion layer on a silicon substrate, a platinum film oriented in the (111) plane orientation is formed, and the substrate is heated to, for example, 550 [° C.]. The X-ray diffraction measurement result of the sample on which the SrRuO ₃ film is formed by sputtering is shown.

  FIG. 9 shows data when 2θ = 32 [°] is fixed and Psi is changed. When Psi = 0 [°], almost no diffraction intensity is observed in the diffraction line on the (110) plane of SRO, and the diffraction intensity is observed in the vicinity of Psi = 35 [°]. ) It can be confirmed that the preferred orientation is in the plane orientation. In addition, from this result, it was confirmed that SRO was preferentially oriented in the (111) plane direction for those produced under the present film forming conditions.

  Further, when the SRO film prepared by performing the RTA process after forming the SRO film described above at room temperature was evaluated in the same manner, the diffraction intensity of SRO (110) was found when Psi = 0 [°]. It was seen.

  When it was estimated how much the displacement after driving was deteriorated compared to the initial displacement when continuously operating as a piezoelectric actuator, the orientation of the electromechanical conversion film (for example, PZT) greatly affected. , (110) may be insufficient in suppressing displacement deterioration. For this reason, as described above, the oxide electrode film is preferably oriented in the (111) plane orientation.

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

The surface roughness of the SrRuO ₃ film affects the film formation temperature, and when the substrate is heated from room temperature to 300 [° C.], the surface roughness is very small and becomes 2 [nm] or less. In this case, the surface roughness is very small and flat, but the crystallinity of the SrRuO ₃ film may not be sufficient. Thus, when the crystallinity of the SrRuO ₃ film is not sufficient, sufficient characteristics can be obtained with respect to the initial displacement as the piezoelectric actuator of the electromechanical conversion film (for example, PZT film) to be formed thereafter and the deterioration of the displacement after continuous driving. Disappear.

Thus, considering the film formation conditions, the surface roughness obtained without deteriorating the crystallinity of the SrRuO ₃ film is considered to be within the above range. Therefore, the above range is preferable.

When it deviates from the above range, the crystallinity of the SrRuO ₃ film may be deteriorated, and the withstand voltage of the electromechanical conversion film to be formed thereafter is deteriorated and may be liable to leak.

In order to obtain the SrRuO ₃ film having the crystallinity and the surface roughness as described above, the film formation condition (temperature) is 500 [° C.] to 700 [° C.], preferably 520 [° C.] to 600 It is preferable to heat the substrate in the range of [° C.] and form a film by sputtering.

  The composition ratio of Sr and Ru after film formation is not particularly limited and is selected depending on required conductivity, etc., but Sr / Ru is preferably 0.82 or more and 1.22 or less. . This is because if it is out of the above range, the specific resistance increases, and sufficient conductivity as an electrode may not be obtained.

  Furthermore, the thickness of the SRO film as the oxide electrode is preferably 40 [nm] or more and 150 [nm] or less, and more preferably 50 [nm] or more and 80 [nm] or less. If the thickness is less than the above range, sufficient characteristics may not be obtained for initial displacement and displacement deterioration after continuous driving. Moreover, it becomes difficult to obtain a function as a stop etching layer for suppressing over-etching of the electromechanical conversion film. Further, if the film thickness exceeds the above-mentioned film thickness range, the dielectric strength voltage of the PZT formed thereafter is deteriorated and it may be likely to leak.

The specific resistance of the oxide electrode is preferably 5 × 10 ⁻³ [Ω · cm] or less, and more preferably 1 × 10 ⁻³ [Ω · cm] or less. If it exceeds this range, sufficient contact resistance cannot be obtained at the interface with the first wiring, and sufficient current cannot be supplied as a common electrode, which may cause problems when ink is ejected. It is.

(Electromechanical conversion membrane)
The electromechanical conversion film 34 can be used as long as it has a piezoelectric property, and is not particularly limited. For example, PZT that is widely used can be preferably used. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTiO ₃ ), and the characteristics differ depending on the ratio. However, the ratio is not limited, and the required piezoelectric performance, etc. Can be selected accordingly. Among them, the ratio (molar ratio) of PbZrO ₃ and PbTiO ₃ is 53:47, and when expressed by the chemical formula, it is also indicated as PZT (PZT (53/47)) represented by Pb (Zr0.53, Ti0.47) O _3. ) Can be preferably used because it exhibits particularly excellent piezoelectric characteristics.

  Barium titanate can also be used as a material other than PZT. In this case, it is possible to prepare a barium titanate precursor solution by using barium alkoxide and a titanium alkoxide compound as starting materials and dissolving them in a common solvent.

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

Further, a composite oxide in which Pb at the A site is partially substituted with Ba or Sr, such as (Pb1-x, Bax) (Zr, Ti) O ₃ , (Pb1-x, Srx) (Zr, Ti) O ₃ Can also be used. A divalent element can be used as an element used for substitution. When a heat treatment is performed when an electromechanical conversion film is formed by substituting a part of Pb with a divalent element, lead can be used. There is an effect of reducing characteristic deterioration due to evaporation.

  A method for producing the electromechanical conversion film 34 is not particularly limited, but for example, it can be produced by a spin coater using a sputtering method or a sol-gel method. Then, after film formation, patterning can be performed by photolithography etching or the like to obtain a desired pattern.

A case where the electromechanical conversion film 34 made of PZT is manufactured by a sol-gel method will be described as an example.
PZT precursor solution is prepared by using lead acetate, zirconium alkoxide, and titanium alkoxide compound as starting materials, using methoxyethanol as a common solvent, and dissolving the above starting materials in a common solution so as to have a predetermined ratio to obtain a uniform solution. To do. Since the metal alkoxide compound is easily hydrolyzed by moisture in the atmosphere, an appropriate amount of a stabilizer such as acetylacetone, acetic acid or diethanolamine can be added to the precursor solution as a stabilizer. In addition, since the lead component may evaporate during heat treatment in the film forming process, it can be added in a larger amount than the stoichiometric ratio.

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

  In the case of a barium titanate film, for example, a barium titanate precursor solution is prepared by using barium alkoxide and a titanium alkoxide compound as starting materials and dissolving them in a common solvent. And using this, for example, it is possible to form a film by the sol-gel method in the same procedure as in the case of PZT.

  The film thickness of the electromechanical conversion film 34 is not limited and may be selected according to the required piezoelectric characteristics, but is preferably 0.5 [μm] or more and 5 [μm] or less, More preferably, it is 1 [μm] or more and 2 [μm] or less. This is because if the thickness is smaller than the above range, sufficient displacement may not be generated when used as a piezoelectric actuator. On the other hand, if the thickness is larger than the above range, a number of layers are deposited in the manufacturing process, so that the number of processes increases and the process time becomes longer.

  The relative dielectric constant of the electromechanical conversion film 34 is preferably 600 or more and 2000 or less, and more preferably 1200 or more and 1600 or less. If the relative permittivity is smaller than the range, sufficient displacement characteristics may not be obtained when used as a piezoelectric actuator. Further, when the relative permittivity is larger than the range, there may be a problem in that the polarization process is not sufficiently performed and sufficient characteristics cannot be obtained for the displacement degradation after continuous driving.

(Second drive electrode)
Although it does not specifically limit as the 2nd drive electrode 35, It is preferable that it consists of a metal or an oxide, and a metal. Specifically, the second drive electrode 35 can be composed of, for example, a metal electrode film. Moreover, it can also comprise from a metal electrode film and an oxide electrode film.

Details of the oxide electrode film and the metal electrode film are described below.
The material or the like of the oxide electrode film is the same as that described for the oxide electrode film of the first drive electrode. The thickness of the oxide electrode film is preferably 20 [nm] or more and 80 [nm] or less, and more preferably 40 [nm] or more and 60 [nm] or less. If the thickness is less than this range, sufficient characteristics may not be obtained for the initial displacement and displacement deterioration characteristics. If this range is exceeded, the dielectric strength of the electromechanical conversion film will be very poor and leakage will occur. It is because it may become easy to do.

  The material of the metal electrode film is the same as that described for the metal electrode film of the first drive electrode. The film thickness of the metal electrode film is preferably 30 [nm] to 200 [nm], and more preferably 50 [nm] to 120 [nm]. This is because if the thickness is smaller than this range, a sufficient current cannot be supplied as an individual electrode, and a problem may occur when ink is ejected. When the thickness is larger than this range, there is a problem in that the cost increases when an expensive platinum group element material is used as the material of the metal electrode film. Further, in the case of using platinum as a material, the surface roughness increases as the film thickness increases, and when the second wiring is formed through the first insulating protective film, film peeling, etc. This is because there is a case where the above-mentioned trouble is likely to occur.

(First insulating protective film)
The first insulating protective film 41 preferably has a function of preventing damage to the piezoelectric element due to the film forming / etching process and preventing moisture in the air from permeating. Therefore, the material is preferably a dense inorganic material. In the case of organic materials, it is necessary to increase the film thickness in order to obtain sufficient protection performance. However, if the insulating film is made thick, the vibration displacement of the diaphragm is hindered and the liquid droplet ejection head has a low ejection performance. This is because there is a case of becoming.

In order to obtain high protection performance with a thin film, it is preferable to use an oxide, nitride, or carbide thin film, but it has high adhesion to electrode materials, electromechanical conversion film materials, and diaphragm materials that form the base of insulating films. It is preferable to select the material. Specifically, the first insulating protective film 41 is preferably made of at least one inorganic film selected from, for example, an alumina film, a silicon oxide film, a silicon nitride film, and a silicon oxynitride film. More _{specifically, Al 2 O 3, ZrO 2} , Y 2 O 3, Ta 2 O 3, an oxide film used in the ceramic material, such as TiO ₂ can be cited as examples. These films have good adhesion, hard films, and excellent wear resistance and cost performance.

  The film formation method of the first insulating protective film 41 is also preferably a film formation method with a low possibility of damaging the piezoelectric element. For example, a vapor deposition method, an ALD method, or the like can be preferably used. The ALD method with a wide range of options can be used more preferably. In particular, by using the ALD method, a thin film having a very high film density can be manufactured, and damage during the process can be suppressed.

  The plasma CVD method in which a reactive gas is turned into plasma and deposited on the substrate, and the sputtering method in which the film is formed by causing the plasma to collide with the target material and flying may cause damage to the piezoelectric element, compared with the vapor deposition method and the ALD method. It is not preferable because it is expensive.

  The film thickness of the first insulating protective film 41 may be a thin film having a sufficient thickness for protecting the piezoelectric element and may be as thin as possible so as not to disturb the displacement of the diaphragm. It is not limited. For example, the thickness of the first insulating protective film is preferably in the range of 20 [nm] to 100 [nm]. When the thickness is larger than 100 [nm], the displacement of the vibration plate is reduced, so that a droplet discharge head (inkjet head) with low discharge efficiency may be obtained. On the other hand, when the thickness is less than 20 [nm], the function as a protective layer of the piezoelectric element may not be sufficient, and the performance of the piezoelectric element may be deteriorated.

  Further, a configuration in which another layer is provided as the first insulating protective film 41 to form two layers is also conceivable. In this case, for example, the second insulating film may be thickened to open the second insulating film in the vicinity of the second drive electrode portion so as not to inhibit the vibration displacement of the diaphragm.

Arbitrary oxides, nitrides, carbides, or composite compounds thereof can be used for the second insulating protective film. For example, SiO ₂ that is generally used in semiconductor devices can be used.

  Arbitrary methods can be used as a method for forming the second insulating protective film, and examples thereof include a CVD method and a sputtering 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 is preferably selected so that the dielectric breakdown is not caused by the voltage applied between the common electrode and the individual electrode wiring. That is, it is preferable to set the electric field strength applied to the insulating film within a range not causing dielectric breakdown. Furthermore, in consideration of the surface property of the base of the second insulating film, pinholes, etc., the film thickness is preferably 200 [nm] or more, and more preferably 500 [nm] or more.

(First and second wiring)
The first wiring 42 and the second wiring 43 are electrically connected to the first driving electrode 33 and the second driving electrode 35, respectively, and are formed on the first insulating protective film 41. .

  The material of the first wiring 42 and the second wiring 43 is not particularly limited, and may be selected according to required performance. For example, Ag alloy, Cu, Al, Al alloy, It is preferably made of at least one metal selected from Au, Pt, and Ir. These metals can form a low-resistance and durable electrode on the substrate.

  As a method for manufacturing the first wiring 42 and the second wiring 43, for example, a method of manufacturing by using a sputtering method or a spin coating method and then obtaining a desired pattern by photolithography etching or the like can be preferably used.

  The film thicknesses of the first wiring 42 and the second wiring 43 are preferably 0.1 [μm] to 20 [μm], and more preferably 0.2 [μm] to 10 [μm]. If the film thickness is smaller than the above range, the resistance increases, and a sufficient current cannot flow through the electrode, and the droplet discharge head may become unstable when the droplet discharge head is used. On the other hand, if the film thickness is larger than the above range, the process time becomes long, which may cause a problem in productivity.

  Further, a portion of the first wiring 42 exposed from the opening (contact hole) 48 becomes a common electrode pad 46. In addition, a portion of the second wiring 43 exposed from the opening (contact hole) 49 becomes an individual electrode pad 47. The contact resistance of these pads 46 and 47 (10 [μm] × 10 [μm]) is preferably 10 [Ω] or less as the contact resistance of the common electrode pad 46, and the contact resistance of the individual electrode pad 47 Is preferably 1 [Ω] or less. Furthermore, the contact resistance of the common electrode pad 46 is more preferably 5 [Ω] or less, and the contact resistance of the individual electrode pad 47 is more preferably 0.5 [Ω] or less. This is because when the contact resistance at each of the pads 46 and 47 exceeds the above range, a sufficient current cannot be supplied, and in the case of a droplet discharge head, a problem occurs when discharging a droplet. It is because there is a case to do.

(Second insulating protective film)
The second insulating protective film 44 functions as a passivation layer having a function of a protective layer for individual electrode wiring and common electrode wiring.

  As shown in FIG. 5A, the individual electrode and the common electrode are covered except for the individual electrode lead portion and the common electrode lead portion (not shown). By providing the second insulating protective film 44 in this way, 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 ink jet head can be obtained.

  As a material of the second insulating protective film 44, any inorganic material or organic material can be used, but a material having low moisture permeability is preferably used.

  As the inorganic material, for example, an oxide, nitride, carbide, or the like can be used, and as the organic material, polyimide, an acrylic resin, a urethane resin, or the like can be used. However, in the case of an organic material, it is necessary to form a thick film, which is not suitable for patterning described later. Therefore, it is more preferable to use an inorganic material that can exhibit a wiring protection function with a thin film.

Therefore, the second insulating protective film 44 is preferably at least one inorganic film selected from an alumina film, a silicon oxide film, a silicon nitride film, and a silicon oxynitride film. In particular, the use of Si ₃ N ₄ as the second insulating protective film on the Al wiring is a technology that has a proven record in semiconductor devices. Therefore, it is preferable to adopt the same configuration also in this embodiment.

  The thickness of the second insulating protective film 44 is preferably 200 [nm] or more, and more preferably 500 [nm] or more. This is because, when the film thickness is small, a sufficient passivation function cannot be exhibited, and therefore disconnection due to corrosion of the wiring material may occur, which may reduce the reliability of the electromechanical conversion element.

  Further, a structure having openings on the piezoelectric element and the surrounding diaphragm is preferable. This is the same reason for providing the opening 49 in the vicinity of the individual electrode pad 47 on the first insulating protective film 41 described above. Thereby, it can be set as a highly efficient and highly reliable electromechanical conversion element. Further, for example, a highly efficient and highly reliable droplet discharge head or inkjet head using the electromechanical transducer 30 can be obtained.

  Since the piezoelectric elements are protected by the first insulating protective film 41 and the second insulating protective film 44, the openings 48 and 49 can be formed by photolithography and dry etching.

The second insulating protective film 44 is provided with a plurality of pads (a common electrode pad 46 and an individual electrode pad 47). The area of these pads is preferably 2500 [μm ² ] or more. Further, it is more preferably 30000 [μm ² ] or more. This is because when the value is less than this value, sufficient polarization processing cannot be performed, or sufficient characteristics may not be obtained for displacement deterioration after continuous driving.

  A method for forming the plurality of pads (the common electrode pad 46 and the individual electrode pad 47) is not particularly limited. For example, the pads can be formed by lithoetching (lithographic etching method).

(Conductor plate)
The conductor plate 20 has a function of injecting electric charges generated by corona discharge or glow discharge into the electromechanical transducer 30.

As shown in FIG. 6A, the conductor plate 20 is composed of a plate portion and a protrusion portion of the main body, and the protrusion portion of the conductor plate 20 is connected to the opening portion of the individual electrode pad 47, and the portion is connected to that portion. Perform corona discharge or glow discharge.

As shown in FIG. 6B, the area of the conductor plate 20 is preferably equal to the substrate 31 on which the electromechanical transducer 30 is present, and more preferably larger. This is because if the area of the conductor plate 20 is smaller than the area, charges generated by corona discharge, will be injected, such as the common electrode, because the strength of the electric field may be reduced.

  The material constituting the conductor plate 20 is preferably the same material as the common electrode pad 46 and the individual electrode pad 47 (the first wiring 42 and the second wiring 43). That is, the material constituting the conductor plate 20 is a metal electrode material selected from the same kind of Ag alloy, Cu, Al, Au, Pt, and Ir as the first wiring 42 and the second wiring 43. Is preferred.

  Further, on the lower surface of the conductor plate 20 in FIG. 6A, a plurality of protruding contact portions 20a corresponding to the positions and the number of pads 47 to be connected to the second wiring 43 are provided. ing. The height of these contact portions 20a is, for example, 1 [mm]. When the polarization process is performed, these contact portions 20a are connected to the pads 47 connected to the second wiring 43 and inject electric charges.

  According to the manufacturing method of the electromechanical conversion element 30 of the present embodiment described above, the polarization process can be performed on the piezoelectric elements at the wafer level. Further, when the electromechanical conversion element 30 obtained by this manufacturing method is a droplet discharge head, the electromechanical conversion element 30 exhibits a stable displacement with respect to a predetermined drive voltage, and maintains a good droplet discharge characteristic. In addition, it is possible to obtain stable droplet discharge characteristics.

  Specifically, as shown in FIG. 1, a nozzle 11 that discharges droplets, a pressurizing chamber 12 that communicates with the nozzle 11, and a discharge driving unit that pressurizes the liquid in the pressurizing chamber 12. A liquid droplet ejection head 10 is provided. In the droplet discharge head 10 according to the present embodiment, as a discharge drive unit, a part of the wall of the pressurizing chamber 12 is configured by a vibration plate, and the above-described electromechanical conversion element is disposed on the vibration plate. is there.

  According to this droplet discharge head 10, since the above-described electromechanical conversion element is used, a stable displacement amount with respect to a predetermined drive voltage can be exhibited, droplet discharge characteristics can be maintained well, and stable droplet discharge can be achieved. Characteristics can be obtained.

  In the present embodiment, the droplet discharge head composed of one nozzle has been described. However, the present invention is not limited to such a configuration, and a configuration including a plurality of droplet discharge heads as shown in FIG. it can. In FIG. 11, a plurality of droplet discharge heads of FIG. 1 are arranged in series, and the same members are denoted by the same reference numerals.

  Moreover, although description about a liquid supply means, a flow path, fluid resistance, etc. was abbreviate | omitted, the incidental equipment which can be provided in a droplet discharge head can be provided naturally.

[Example 1]
Hereinafter, a more specific manufacturing method of the electromechanical transducer will be described with reference to examples. However, the present invention is not limited to this embodiment.

  First, a thermal oxide film (film thickness: 1 [μm]) was formed on a 6-inch silicon wafer.

Next, a first drive electrode was formed. Specifically, first, as an adhesion film, a titanium film (film thickness: 30 [nm]) was formed by a sputtering apparatus, and then thermally oxidized at 750 [° C.] using RTA. Subsequently, a platinum film (film thickness 100 [nm]) was formed as a metal film, and an SrRuO ₃ film (film thickness 60 [nm]) was formed as an oxide film by sputtering. Film formation was performed at a substrate heating temperature of 550 [° C.] during the sputtering film formation.

  Next, an electromechanical conversion film was formed. Specifically, a solution having a molar ratio of Pb: Zr: Ti = 114: 53: 47 was prepared, and a film was formed by spin coating.

  For the synthesis of a specific precursor coating solution, lead acetate trihydrate, isopropoxide titanium, and normal propoxide zirconium were used as starting materials. Crystal water of lead acetate was dissolved in methoxyethanol and then dehydrated. The lead amount is excessive with respect to the stoichiometric composition. This is to prevent crystallinity deterioration due to so-called lead loss during heat treatment.

  Isopropoxide titanium and normal propoxide zirconium were dissolved in methoxyethanol, the alcohol exchange reaction and the esterification reaction were advanced, and the PZT precursor solution was synthesized by mixing with the methoxyethanol solution in which the lead acetate was dissolved. The PZT concentration in the synthesized PZT precursor solution was 0.5 [mol / L].

  Using the precursor solution, a film is formed on the substrate on which the first drive electrode is formed by spin coating, and after the film formation, drying is performed at 120 [° C.], and then thermal decomposition is further performed at 500 [° C.]. The operation was repeated several times to laminate an electromechanical conversion film.

  When the electromechanical conversion film was laminated by repeating the above procedure, a crystallization heat treatment (temperature 750 [° C.]) was performed by RTA (rapid heat treatment) after the third thermal decomposition treatment. After the thermal decomposition treatment of the third layer, the film thickness of the electromechanical conversion film (PZT) subjected to RTA treatment was 240 [nm].

  The above process was performed a total of 8 times (24 layers) to obtain an electromechanical conversion film having a PZT film thickness of about 2 [μm].

Next, an SrRuO ₃ film (film thickness 40 [nm]) was formed as an oxide film of the second drive electrode, and a Pt film (film thickness 125 [nm]) was formed as a metal film by sputtering.

  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 electromechanical conversion film and the second drive electrode were separated by etching using an ICP etching apparatus (manufactured by Samco), and a pattern as shown in FIG. 5 was produced. Thus, the second drive electrode functions as an individual electrode, and the first drive electrode functions as a common electrode for the individualized electromechanical conversion film and the second drive electrode.

Next, as the first insulating protective film, an Al ₂ O ₃ film having a thickness of 50 nm was formed by the ALD method.

As raw materials, trimethylaluminum (TMA) (manufactured by Sigma-Aldrich) was used as the Al source, and O ₃ generated by an ozone generator was used as the O source. Then, an Al source and an O source were alternately supplied onto the substrate and laminated to form a film.

  Thereafter, as shown in FIG. 5, a contact hole was formed by etching.

  Then, Al was sputtered as the first wiring and the second wiring, and was patterned by etching.

After that, Si ₃ N ₄ was deposited as a second insulating film to a thickness of 500 [nm] by plasma CVD to produce an electromechanical conversion element.

  At this time, 25 areas of 30 [mm] × 10 [mm] squares in a 6-inch wafer are arranged, and individual electrode pad areas (50 [μm] × 1000 [μm]) are provided, and 300 pads are prepared. did. Further, a common electrode pad area (50 [μm] × 1000 [μm]) and 30 pads were prepared.

  Thereafter, the conductor plate 20 having an area equivalent to that of the substrate and having contact portions corresponding to the number of pads of the individual electrodes and the positions of the pads of the individual electrodes is connected to all the individual electrode pads in the wafer, and subjected to corona charging treatment. Polarization treatment was performed.

  The corona charging treatment was performed using a tungsten wire of φ50 [μm]. The distance between the wire and the conductor plate 20 was set to 5 [mm], and a voltage of 6 [kV] was applied to the sample for 20 minutes.

[Comparative Example 1]
An electromechanical transducer was produced in the same manner as in Example 1 except that a voltage was applied to the sample without using the conductor plate 20 in the corona charging process. However, in Comparative Example 1, since the conductor plate 20 is not used, all the individual electrode pads in 25 areas of 30 [mm] × 10 [mm] in a 6-inch wafer are corona-charged with tungsten wires. There is a need to do. For this reason, the corona charging process must be performed for each column, and nine processes must be performed.

  FIG. 10 is a graph comparing the electromechanical transducers produced in Example 1 and Comparative Example 1, respectively. In the graph shown in FIG. 10, regarding the processing effect of the electromechanical transducer elements in the wafer produced by Example 1 and Comparative Example 1, respectively, the X axis is in the range of Pr-Pini, and the Y axis is the number of elements in that range. Compare as a percentage.

  In FIG. 10, it can be seen that Example 1 in which the treatment was performed using the conductor plate 20 had less variation throughout the wafer. Furthermore, in Example 1, the processing effect can be obtained in an extremely short time compared to Comparative Example 1 in which the conductor plate 20 is not used. That is, as described above, in the first embodiment, the polarization process by the corona charging process can be performed in 1/9 of the time compared with the first comparative example.

  Next, a configuration example of a droplet discharge apparatus including the droplet discharge head will be described. The form of the droplet discharge device is not particularly limited, but here, an ink jet recording device will be described as an example.

  An example of the ink jet recording apparatus will be described with reference to FIGS. 12 is a perspective explanatory view of the recording apparatus, and FIG. 13 is a side explanatory view of a mechanism portion of the recording apparatus.

  The ink jet recording apparatus includes a carriage 69 that can move in the main scanning direction inside the recording apparatus main body 61. Further, a recording head composed of an ink jet head mounted on the carriage 69, a printing mechanism unit 62 including an ink cartridge for supplying ink to the recording head, and the like are accommodated. In addition, a sheet feeding cassette (or a sheet feeding tray) 64 on which a large number of sheets 63 can be stacked from the front side can be removably mounted on the lower portion of the apparatus main body 61. The manual feed tray 65 for manually feeding paper can be opened. Then, the paper 63 fed from the paper feed cassette 64 or the manual feed tray 65 is taken in, and after a required image is recorded by the printing mechanism unit 62, the paper is discharged to a paper discharge tray 66 mounted on the rear side.

  The printing mechanism 62 holds a carriage 69 slidably in the main scanning direction by a main guide rod 67 and a sub guide rod 68 which are guide members horizontally mounted on left and right side plates (not shown). The carriage 69 includes a recording head 70 including an inkjet head that ejects ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The recording head 70 has a plurality of ink discharge ports (nozzles) arranged in a direction crossing the main scanning direction, and is mounted with the ink droplet discharge direction facing downward. In addition, each ink cartridge 71 for supplying ink of each color to the head 70 is replaceably mounted on the carriage 69.

  The ink cartridge 71 has an atmosphere port communicating with the atmosphere above, a supply port for supplying ink to the inkjet head below, and a porous body filled with ink inside. The ink supplied to the inkjet head is maintained at a slight negative pressure by the capillary force of the porous body. Further, although the recording heads 70 of the respective colors are used here as the recording heads, a single recording head having nozzles for ejecting ink droplets of the respective colors may be used.

  Here, the carriage 69 is slidably fitted to the main guide rod 67 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 68 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 69 in the main scanning direction, a timing belt 75 is stretched between a driving pulley 73 and a driven pulley 74 that are rotationally driven by a main scanning motor 72. This timing belt 75 is fixed to the carriage 69, and the carriage 69 is reciprocated by the forward / reverse rotation of the main scanning motor 72.

  On the other hand, in order to convey the sheet 63 set in the sheet feeding cassette 64 to the lower side of the head 70, the sheet 63 is guided from the sheet feeding roller 76 and the friction pad 77 for separating and feeding the sheet 63 from the sheet feeding cassette 64. A guide member 78 is provided. Further, a conveyance roller 79 that reverses and conveys the fed paper 63, a conveyance roller 80 that is pressed against the circumferential surface of the conveyance roller 79, and a leading end roller 81 that defines a feeding angle of the sheet 63 from the conveyance roller 79, Is provided. The transport roller 79 is rotationally driven by a sub-scanning motor 82 through a gear train.

  A printing receiving member 83 is provided as a paper guide member that guides the paper 63 fed from the transport roller 79 on the lower side of the recording head 70 corresponding to the range of movement of the carriage 69 in the main scanning direction. On the downstream side of the printing receiving member 83 in the sheet conveyance direction, a conveyance roller 84 and a spur 85 that are rotationally driven to send the sheet 63 in the sheet discharge direction are provided. Further, a discharge roller 86 and a spur 87 for sending the sheet 63 to the discharge tray 66, and guide members 88 and 89 for forming a discharge path are provided.

  At the time of recording, the recording head 70 is driven in accordance with the image signal while moving the carriage 69, thereby ejecting ink onto the stopped sheet 63 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 63 reaches the recording area, the recording operation is terminated and the paper 63 is discharged.

  Further, a recovery device 90 for recovering defective ejection of the head 70 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 69. The recovery device 90 includes a cap unit, a suction unit, and a cleaning unit. The carriage 69 is moved to the recovery device 90 side during printing standby and the head 70 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.

  When a discharge failure occurs, the discharge port (nozzle) of the head 70 is sealed with a capping unit, and bubbles and the like are sucked out from the discharge port through the tube with a suction unit. As a result, the ink, dust, etc. adhering to the ejection port surface are removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  As described above, the ink jet recording apparatus, which is the liquid droplet ejection apparatus of the present embodiment, is equipped with the above-described liquid droplet ejection head, so there is no ink droplet ejection failure due to vibration plate drive failure and stable ink droplet ejection. Characteristics are obtained and image quality is improved.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A step of forming a first drive electrode 33 on the substrate 31 or the base film 32; an electromechanical conversion film 34 on the first drive electrode 33; and a second drive electrode 35 positioned on the electromechanical conversion film 34 Forming a first insulating protective film 41 on the second drive electrode 35; and wiring 43 electrically connected to the second drive electrode 35 as a first insulating protective film 41, forming a second insulating protective film 44 that is a film formed on the wiring 43 and that exposes terminal electrodes such as the individual electrode pads 47 that are connected to the wiring 43 ; a conductive member such as conductive plate 20 having a contact portion 20 a that corresponds to the child electrode, by contacting the contact portion 20 a of the conductive member to the terminal electrodes, generated by corona discharge or glow discharge in the conductive members Electric By injecting comprises the steps of polarized electromechanical conversion film 34.
According to this, as above described, when performing the polarization treatment of the electromechanical conversion film 34, the contact portion 20 a of the conductive member, an opening portion formed in the second insulating protection film 44 Since the contact is made from 49 to the terminal electrode, the charge generated by the corona discharge or the glow discharge is surely injected, and the electromechanical conversion film 34 can be polarized. Further, since the polarization process is performed after the formation of the second insulating protective film 44 to which high temperature heat is applied, no heat is applied after the polarization process. Thereby, depolarization after the polarization process of the electromechanical conversion film 34 can be prevented. As described above, the polarization process of the electromechanical conversion film 34 can be reliably performed, and depolarization after the polarization process can be prevented.
Incidentally, when the conductive member has a plurality of contact portions 20 a may be polarized at once a plurality of electromechanical conversion film conductive to a plurality of terminal electrodes, thereby improving the manufacturing efficiency.
(Aspect B)
In the aspect A, the area of the conductive member is an area that is equal to or larger than the area of the substrate 31.
According to this, as described in the above embodiment, when the area of the conductive member is smaller than the area of the substrate 31, charges generated by corona discharge or glow discharge are applied to the electrodes other than the second drive electrode 35. it is implanted there is a want cormorant fear. In embodiments B, the area of the conductive member, because it is the area over the area of the substrate 31, as possible out to suppress the charge injection into the second drive electrodes 35 other than the electrodes.
(Aspect C)
In the aspect A or B, in the step of performing the polarization treatment, the charge generated by the corona discharge or the glow discharge is positively charged.
According to this, as described in the above embodiment, positive ions having positively charged charges can be easily generated by ionizing molecules in the atmosphere by corona discharge or glow discharge. The positive ions flow into the electromechanical conversion element 30 through the pad 47 connected to the wiring 43, so that positively charged charges can be easily accumulated in the electromechanical conversion element 30. Therefore, the polarization treatment of the electromechanical conversion film can be performed stably.
(Aspect D)
In any one of the above aspects A to C, in the step of performing the polarization treatment, a charge amount of 1.0 × 10 ⁻⁸ [C] or more is generated by corona discharge or glow discharge.
According to this, as described in the above embodiment, when the charge amount due to corona discharge or glow discharge is less than 1.0 × 10 ⁻⁸ [C], the polarization treatment may not be sufficiently performed. When the electromechanical conversion film 34 is used as a piezoelectric actuator such as PZT, sufficient characteristics may not be obtained with respect to displacement deterioration after continuous driving. In the present embodiment D, since the charge amount due to corona discharge or glow discharge is 1.0 × 10 ⁻⁸ [C] or more, the polarization treatment can be sufficiently performed, and the electromechanical conversion film 34 is formed into the piezoelectric layer. When used as an actuator, sufficient characteristics can be obtained with respect to displacement deterioration after continuous driving.
(Aspect E)
In any one of the above aspects A to D, the material of the conductive member is the same as the material of the terminal electrode.
According to this, as above described, it is possible to reduce the contact resistance between the contact portion 20 a and the terminal electrodes of the conductive member, it is possible to increase the efficiency of charge injection via the terminal electrode .
(Aspect F)
The electromechanical conversion element obtained by any one of the above aspects A to E, wherein the polarization of the electromechanical conversion film 34 is measured when the hysteresis loop is measured with an electric field strength of ± 150 [kV / cm]. When the polarization at 0 [kV / cm] is Pini and the voltage at 0 [kV / cm] when the voltage is returned to 0 [kV / cm] after applying a voltage of +150 [kV / cm] is Pr , The difference between Pr and Pini is 10 [μC / cm ² ] or less.
According to this, as described in the above embodiment, when the difference between Pr and Pini is larger than 10 [μC / cm ² ], when the electromechanical conversion film 34 is used as a piezoelectric actuator, displacement deterioration after continuous driving is achieved. This is because sufficient characteristics may not be obtained. In the aspect F, since the difference between Pr and Pini is 10 [μC / cm ² ] or less, when the electromechanical conversion film 34 is used as a piezoelectric actuator, sufficient characteristics can be obtained with respect to displacement deterioration after continuous driving.
(Aspect G)
In the aspect F, the relative dielectric constant of the electromechanical conversion film 34 is 600 or more and 2000 or less.
According to this, as described in the above embodiment, when the relative dielectric constant is smaller than 600, there are cases where sufficient displacement characteristics cannot be obtained when the electromechanical conversion film 34 is used as a piezoelectric actuator. Also, if the relative dielectric constant is greater than 2000, the polarization process may not be sufficiently performed, and there may be a problem that sufficient characteristics cannot be obtained for displacement degradation after continuous driving. In the aspect F, since the relative dielectric constant of the electromechanical conversion film 34 is 600 or more and 2000 or less, sufficient displacement characteristics can be obtained when the electromechanical conversion film 34 is used as a piezoelectric actuator. Further, the polarization process is sufficiently performed, and sufficient characteristics can be obtained with respect to displacement deterioration after continuous driving.
(Aspect H)
In the above aspect F or G, the area of the terminal electrode is 2500 [μm ² ] or more.
According to this, as described in the above-described embodiment, when the area of the terminal electrode is less than 2500 [μm ² ], sufficient polarization processing cannot be performed, or displacement deterioration after continuous driving is sufficient. Characteristics may not be obtained. In the aspect H, since the area of the terminal electrode is 2500 [μm ² ] or more, the polarization process is sufficiently performed, and sufficient characteristics can be obtained with respect to the displacement deterioration after continuous driving.
(Aspect I)
In the droplet discharge head 10 including a nozzle 11 that discharges a droplet, a pressurizing chamber 12 that communicates with the nozzle 11, and a discharge driving unit that pressurizes the liquid in the pressurizing chamber 12, the discharge driving unit includes: A part of the wall of the pressurizing chamber 12 is constituted by the diaphragm 17, and the electromechanical transducer of any one of the above aspects F to H is arranged on the diaphragm 17.
According to this, as described in the above embodiment, the liquid in the pressurizing chamber 12 can be boosted by the electromechanical conversion element that has been reliably subjected to the polarization process without depolarization. Discharge characteristics can be obtained.
(Aspect J)
A droplet discharge apparatus including the droplet discharge head according to aspect I. According to this, as described in the above embodiment, stable droplet discharge characteristics can be obtained.
(Aspect K)
Electromechanical conversion for performing polarization processing on an electromechanical conversion element having a structure in which a first drive electrode 33, an electromechanical conversion film 34, and a second drive electrode 35 are laminated on a substrate 31 or a base film 32. an apparatus for producing a device, corona discharge or a discharge electrode such as corona wire 52 for generating an electric charge by glow discharge, a stage 53 for placing the electromechanical transducer 3 0, an electromechanical transducer disposed on the stage 53 A conductive member having a contact portion 20a in contact with a terminal electrode such as the individual electrode pad 47 connected to the second drive electrode, and a conductor plate 20 into which charges generated by corona discharge or glow discharge are injected. A conductive member.
According to this, as described in the above embodiment, the polarization process of the electromechanical conversion film 34 can be reliably performed, and depolarization after the polarization process can be prevented.
(Aspect L)
In the above aspect K, the area of the conductive member is an area larger than the area of the substrate.
According to this, as above described, to suppress the charge injection into the second drive electrodes 35 other than the electrodes as possible.
(Aspect M)
In the above aspect K or L, the material of the conductive member is the same as the material of the terminal electrode.
According to this, as above described, it is possible to reduce the contact resistance between the contact portion 20 a and the terminal electrodes of the conductive member, it is possible to increase the efficiency of charge injection via the terminal electrode .

DESCRIPTION OF SYMBOLS 10 Droplet discharge head 11 Nozzle 12 Pressurization chamber 13 Electromechanical conversion film 14 Upper electrode 15 Lower electrode 16 Electromechanical conversion element 17 Base film (vibration plate)
DESCRIPTION OF SYMBOLS 20 Conductor plate 30 Electromechanical conversion element 31 Board | substrate 33 1st drive electrode 34 Electromechanical conversion film 35 2nd drive electrode 41 1st insulation protective film 42 1st wiring 43 2nd wiring 44 2nd insulation protection Film 45 Contact hole 46 Common electrode pad 47 Individual electrode pad 61 (Inkjet) recording device main body

Japanese Patent No. 3365485 Patent No. 4218309 Japanese Patent No. 3019845 JP 2004-202849 A JP 2010-034154 A JP 2006-203190 A Japanese Patent No. 3784401

Claims (11)

Forming a first drive electrode on a substrate or a base film;
Forming an electromechanical conversion film and a second drive electrode positioned on the electromechanical conversion film on the first drive electrode;
Forming a first insulating protective film on the second drive electrode;
Forming a wiring electrically connected to the second drive electrode on the first insulating protective film;
Forming a second insulating protective film that is a film formed on the wiring and exposes a terminal electrode connected to the wiring;
Using a conductive member having a contact portion corresponding to the terminal electrode, bringing the contact portion of the conductive member into contact with the terminal electrode, and injecting a charge generated by corona discharge or glow discharge into the conductive member. And a step of polarizing the electromechanical conversion film. A method for manufacturing an electromechanical conversion element. In the manufacturing method of the electromechanical transducer of claim 1,
The method of manufacturing an electromechanical conversion element, wherein an area of the conductive member is equal to or larger than an area of the substrate. In the manufacturing method of the electromechanical transducer of Claim 1 or 2,
In the step of performing the polarization treatment, the charge generated by corona discharge or glow discharge is positively charged. In the method for manufacturing an electromechanical transducer according to any one of claims 1 to 3,
In the step of performing the polarization treatment, a charge amount of 1.0 × 10 ⁻⁸ [C] or more is generated by corona discharge or glow discharge. In the method for manufacturing an electromechanical transducer according to any one of claims 1 to 4,
The method of manufacturing an electromechanical transducer element, wherein a material of the conductive member is the same as a material of the terminal electrode. Production method smell either electromechanical variable換素Ko of claims 1 to 5 Te,
When the hysteresis loop is measured by applying an electric field strength of ± 150 [kV / cm] as the polarization of the electromechanical conversion film, the polarization at 0 [kV / cm] at the start of measurement is Pini, and +150 [kV / cm] The difference between Pr and Pini is 10 [μC / cm ² ] or less when the polarization at 0 [kV / cm] when the voltage is returned to 0 [kV / cm] after the voltage application is taken as Pr. A method for manufacturing an electromechanical transducer element. In the manufacturing method of the electromechanical transducer of claim 6,
The method of manufacturing an electromechanical conversion element , wherein the electromechanical conversion film has a relative dielectric constant of 600 or more and 2000 or less. In the manufacturing method of the electromechanical transducer of Claim 6 or 7,
The method of manufacturing an electromechanical transducer, wherein the terminal electrode has an area of 2500 [μm ² ] or more. An apparatus for manufacturing an electromechanical conversion element that performs polarization processing on an electromechanical conversion element having a structure in which a first drive electrode, an electromechanical conversion film, and a second drive electrode are stacked on a substrate or a base film. There,
A discharge electrode for generating a charge by corona discharge or glow discharge;
A stage on which the electromechanical transducer is installed;
A conductive member having a contact portion that comes into contact with a terminal electrode connected to the second drive electrode of the electromechanical transducer disposed on the stage, and is a conductive member into which charges generated by corona discharge or glow discharge are injected. Members,
An apparatus for manufacturing an electromechanical transducer, comprising: In the electromechanical transducer element manufacturing apparatus according to claim 9 ,
2. The electromechanical transducer manufacturing apparatus according to claim 1, wherein an area of the conductive member is equal to or larger than an area of the substrate. In the electromechanical transducer manufacturing apparatus according to claim 9 or 10 ,
The electromechanical transducer manufacturing apparatus is characterized in that the material of the conductive member is the same as the material of the terminal electrode.

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