JP6268985B2 - ELECTRO-MACHINE CONVERSION ELEMENT AND MANUFACTURING METHOD THEREOF, AND LIQUID DISCHARGE HEAD HAVING ELECTRO-MECHANICAL CONVERSION ELEMENT, AND LIQUID DISCHARGE EJECTION DEVICE HAVING LIQUID DISCHARGE HEAD - Google Patents

Description

  The present invention relates to an electromechanical transducer, a method for manufacturing the same, a droplet ejection head having an electromechanical transducer, and a droplet ejection apparatus having a droplet ejection head.

As for an ink jet recording apparatus and a droplet discharge head used as an image recording apparatus or an image forming apparatus such as a printer, a facsimile machine, and a copying apparatus, the configuration shown in FIG.
FIG. 1 is a schematic diagram illustrating a configuration example of a droplet discharge head.

  The droplet discharge head includes a nozzle 102 for discharging ink droplets, a nozzle plate 103 on which the nozzle 102 is formed, and a pressure chamber 101 (an ink flow path, a pressurized liquid chamber, a pressure chamber, a discharge chamber, And a discharge driving unit that pressurizes the ink (liquid) in the pressurizing chamber 101. The pressurizing chamber 101 is divided by a nozzle plate 103 on the lower surface, a pressurizing chamber substrate 104 (Si substrate) on the side surface, and a base 105 on the upper surface. Examples of the ejection driving means include an electromechanical conversion element 109 such as a piezoelectric element, an electrothermal conversion element such as a heater, or a means that includes a diaphragm that forms a wall surface of an ink flow path and an electrode facing the diaphragm. Ink droplets are ejected from the nozzles 102 by pressurizing the ink in the pressurizing chamber 101 with the energy generated by the energy generating means or the like. Two types of ink jet recording heads have been put into practical use: those using a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of the piezoelectric element, and those using a flexural vibration mode piezoelectric actuator.

  Various devices using a flexural vibration mode actuator are known. For example, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric material layer is cut into a shape corresponding to the pressure generating chamber by lithography to be independent of each pressure generating chamber. An electromechanical conversion element is formed.

The electromechanical conversion element used for the flexural vibration mode actuator includes, for example, a lower electrode 106 that is a common electrode, and a PZT film (piezoelectric layer; electromechanical conversion film 107) formed on the lower electrode 106. , And an upper electrode 108 which is an individual electrode formed on the PZT film. Further, an interlayer insulating film is formed on the upper electrode 108 to insulate the lower electrode 106 and the upper electrode 108 and are electrically connected to the upper electrode 108 through a contact hole opened in the interlayer insulating film. In this structure, the wiring to be provided is provided (see Patent Documents 1 and 2).
However, most of the examples using a metal electrode based on Pt as the lower electrode 106 are concerned, and there is a concern about the guarantee of the fatigue characteristics of PZT. Generally, characteristic degradation due to Pb diffusion contained in PZT is considered, and it is known that fatigue characteristics are improved by using an oxide electrode (see Patent Document 3).

  FIG. 2 is a diagram for explaining the polarization state of the PZT film before and after the polarization treatment. As shown in FIG. 2, the piezoelectric crystal whose polarization direction 21 was in a random state immediately before voltage application (FIG. 2 (a) before polarization processing) It becomes an aggregate of domains 20 in which the directions of polarization are aligned (after polarization processing in FIG. 2B). 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 called an aging process or a poling (polarization process) process. (See Patent Documents 4 to 8). Specifically, a technique is applied in which a high voltage exceeding the drive pulse voltage is applied to the piezoelectric element.

  By the way, when applying and processing a drive pulse voltage as described in Patent Documents 4, 5, 7, and 8, for example, a specific application method has not been specified. In this case, if it is assumed that processing is performed at the wafer level using a probe card or the like, the production of the probe card or the like is expensive depending on the number or arrangement of terminal electrodes arranged. In addition, when the number of terminal electrodes that can be processed by one probe card is small, it takes a considerable time to process at the wafer level.

Further, in the method described in Patent Document 6, a device is applied to generate an electric field in the piezoelectric body by supplying a charge by applying a voltage between the electrode and the charge supply means to generate a corona discharge. It has been broken.
However, in the case of processing using the corona wire described in Patent Document 6, the processing is performed after the piezoelectric film is formed, and the heat history in the subsequent steps (interlayer film formation and lead wiring formation), etc. There is concern about depolarization due to the effects of Specifically, FIG. 3 is a graph showing a PE hysteresis loop before and after the polarization process. As described above, when a heat history exceeding 300 ° C. is given after the processing, the state before the processing is returned as shown in FIG.

  The present invention has been made in view of the above problems in the prior art, and an object of the present invention is to provide an electromechanical transducer that exhibits a desired polarization state, excellent electrical characteristics, and excellent durability.

An electromechanical transducer according to the present invention for solving the above problems includes a substrate, a first electrode that is a common electrode formed on the substrate, and an electromechanical transducer formed on the first electrode. A film, a second electrode that is an individual electrode formed on the electromechanical conversion film, a first insulating protective film provided on the first electrode and the second electrode, and having a contact hole; A third electrode formed to be electrically connected to the first electrode through the contact hole, and a fourth electrode formed to be electrically connected to the second electrode via the contact hole. An electrode, a common electrode pad formed on the third electrode, a plurality of individual electrode pads formed on the fourth electrode and arranged in a predetermined row, the third electrode and the third electrode A common electrode pad and a front electrode provided on the fourth electrode; A second insulating protective film has an opening portion is formed at a portion corresponding to each of the plurality of individual electrodes pad, a fifth electrode formed so as to surround the neighborhood of each of the individual electrode pads, The fifth electrode is formed on the first insulating protective film and is electrically connected to the first electrode through the contact hole.

  ADVANTAGE OF THE INVENTION According to this invention, the electromechanical conversion element which exhibits a desired polarization state, is excellent in an electrical property, and is excellent in durability can be provided.

It is the schematic which shows the structural example of a droplet discharge head. It is a figure for demonstrating the polarization state of the PZT film | membrane before and behind a polarization process. It is a graph which shows the PE hysteresis loop before and behind a polarization process. It is the schematic which shows the structure of a part of electromechanical conversion element which concerns on this invention. (A) It is sectional drawing 1 in the conventional electromechanical transducer. (B) It is sectional drawing 2 in the conventional electromechanical transducer. (C) It is a top view in the conventional electromechanical transducer. It is a figure for demonstrating the discharge by a corona electrode. It is a figure for demonstrating the movement of the electric charge from an individual electrode and a common electrode. (A) It is sectional drawing in one Embodiment of the electromechanical transducer based on this invention. (B) It is an upper side figure in one embodiment of the electromechanical conversion element concerning the present invention. It is a figure for demonstrating the arrangement | positioning relationship of the opening part of a 2nd insulating protective film. It is a top view in other embodiments of an electromechanical conversion element concerning the present invention. (A) It is sectional drawing in other embodiment of the electromechanical conversion element which concerns on this invention. (B) It is a top view in other embodiment of the electromechanical transducer which concerns on this invention. It is the schematic in an example of a polarization processing apparatus. It is a figure for demonstrating the structure in an example of a polarization processing apparatus. (A) It is sectional drawing which shows an example in the A-A 'line | wire of FIG. (B) It is sectional drawing which shows another example in the A-A 'line | wire of FIG. (A) It is a graph which shows the PE hysteresis loop before polarization processing. (B) It is a graph which shows the PE hysteresis loop after polarization processing. It is a graph which shows a typical PE hysteresis loop. It is the schematic which shows the other structural example of a droplet discharge head. It is a schematic perspective view which shows the structure of the droplet discharge apparatus which concerns on this invention. It is a schematic sectional drawing which shows the structure of the droplet discharge apparatus which concerns on this invention. It is a figure which shows the example of the XRD pattern of the SRO film | membrane (111) of the electromechanical conversion element which concerns on this invention.

  An electromechanical conversion element according to the present invention includes a substrate, a first electrode that is a common electrode formed on the substrate, an electromechanical conversion film formed on the first electrode, and the electromechanical conversion A second electrode which is an individual electrode formed on the film, a first insulating protective film provided on the first electrode and the second electrode, and having a contact hole; and the first electrode, A third electrode formed so as to be conductive through the contact hole; a fourth electrode formed so as to be conductive through the second electrode; and the third electrode. A second insulating protective film having a common electrode pad formed on the electrode; and a plurality of individual electrode pads formed on the fourth electrode and arranged in a predetermined row; and the individual electrode A fifth pad formed so as to surround each of the pads for use. And a pole, said fifth electrode is formed on said first insulating protective film, characterized in that it conductive with the first electrode through the contact hole.

As described in the background art, since there is a problem of depolarization due to the influence of the thermal history or the like, it is preferable that the process using the corona electrode is performed after the process of giving the thermal history. . In the present invention, for example, the thermal history process exceeding 300 ° C. is performed.
Further, in the present invention, the polarization process is performed by injecting charges generated by corona discharge or glow discharge through the electrode pad portion so that batch processing can be performed at the wafer level. By doing in this way, the electromechanical conversion element which can suppress the displacement amount change by repeating voltage application can be provided. Furthermore, it is preferable because the ink ejection characteristics can be maintained satisfactorily, stable ink ejection characteristics can be obtained, and the electromechanical conversion elements can be arranged with high density.
Here, when performing polarization processing by charge injection such as corona discharge, problems such as variations in in-column characteristics due to excessive progress of polarization processing and dielectric breakdown between upper and lower electrodes due to injection of excess charge may occur. Newly understood.
For this reason, the present inventors have completed the present invention by developing a head configuration capable of injecting a uniform charge amount into the individual electrode pad portion of the drive channel.

Next, the electromechanical transducer according to the present invention will be described in more detail.
Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

FIG. 4 shows the configuration of an electromechanical transducer (hereinafter sometimes referred to as a piezoelectric element).
FIG. 4 is a schematic diagram showing a partial configuration of the electromechanical transducer according to the present invention.
5A is a sectional view 1 of a conventional electromechanical transducer, FIG. 5B is a sectional view of a conventional electromechanical transducer, and FIG. 5C is a conventional electrical machine. It is a top view in a conversion element. Here, in FIG. 5C, the second insulating protective film 409 is not shown for explanation.
As shown in FIG. 4, a substrate 401, a film formation diaphragm 402 as a base film, a first electrode 403, an electromechanical conversion film 404, and a second electrode 405 are stacked in this order. Further, FIG. 5 shows an element structure including an interlayer film and lead wiring.

  The first insulating protective film 406 has a contact hole, and the first electrode 403 and the third electrode 407 are electrically connected to each other and the second electrode 405 and the fourth electrode 408 are electrically connected. Yes. At this time, a second insulating protective film 409 for protecting the common electrode and the individual electrode is formed using the first and third electrodes as a common electrode and the second and fourth electrodes as individual electrodes. In addition, a part of the second insulating protective film 409 is opened, a part of the individual electrode is configured as an individual electrode pad, and a part of the common electrode is configured as a common electrode pad. A common electrode pad 412 is prepared for the common electrode, and an individual electrode pad 411 is prepared for the individual electrode.

Next, the piezoelectric element manufactured so far is subjected to corona discharge or glow discharge, and the generated charge is injected through the pad portion to perform polarization processing.
FIG. 6 is a diagram for explaining discharge by the corona electrode. As shown in FIG. 6, when corona discharge is performed using a corona electrode 71 (corona wire), positive ions are generated by ionizing molecules in the atmosphere, and positive ions flow through the pad portion of the piezoelectric element. Thus, electric charges are accumulated in the piezoelectric element.

  FIG. 7 is a diagram for explaining the movement of charges from the individual electrode and the common electrode. As shown in FIG. 7, the generated cations are considered to flow into both the individual electrode pad 411 and the common electrode pad 412. Here, the material flowing into the common electrode pad 412 flows to the ground (GND) through the film-forming diaphragm 402 and the substrate 401 below the first electrode 403, and is charged by the charges charged in the individual electrodes. It is considered that a potential difference is generated and the polarization process is performed.

  Here, when a plurality of piezoelectric elements are arranged in a predetermined column as shown in FIG. 5, when performing polarization processing by charge injection such as corona discharge, characteristic variation in the column due to excessive progress of polarization processing or excess charge It has been found that problems such as dielectric breakdown occur between the upper and lower electrodes due to the injection of.

Therefore, in order to prevent the electric charge from concentrating on the individual electrode pad 411, as shown in FIG. 8, an electrode (fifth electrode 410) is formed so as to surround each of the individual electrode pads 411. For such a charge, a device was devised so that it could escape to the electrode surrounding the individual electrode pad 411.
FIG. 8A is a cross-sectional view of one embodiment of the electromechanical transducer according to the present invention, and FIG. 8B is a top view of one embodiment of the electromechanical transducer according to the present invention. . Here, in FIG. 8B, the second insulating protective film 409 is not shown for explanation.

  The fifth electrode 410 is formed over the first insulating protective film 406 and is electrically connected to the first electrode 403 through a contact hole. A second insulating protective film 409 is formed on the fifth electrode 410, and as shown in FIGS. 8 and 9, it is opened so as to surround the vicinity of the individual electrode pad 411. Here, FIG. 9 is a diagram for explaining the arrangement relationship of the openings of the second insulating protective film. Further, as shown in FIG. 9, the fifth electrode 410 preferably surrounds the vicinity of the individual electrode pad 411 except for a part of the individual electrode pad 411. Further, the second insulating protective film 409 on the fifth electrode 410 is preferably opened so as to surround the vicinity of the individual electrode pad 411 except for a part of the individual electrode pad 411.

  That is, for example, as shown in FIG. 9, it is preferable that the fifth electrode 410 surrounds the vicinity of the individual electrode pad 411 except for one of the four sides around the individual electrode pad 411. As used herein, one side refers to a side on the side from which the fourth electrode 408 is drawn out in the individual electrode pad 411 as shown in FIG.

  FIG. 10 is a top view of another embodiment of the electromechanical transducer according to the present invention. In FIG. 10, the second insulating protective film 409 is not shown for the sake of explanation. As shown in FIG. 10, the fifth electrode 410 may have a pattern shape that is electrically connected to the third electrode 407.

Further, as shown in FIG. 11, the fifth electrode 410 is electrically connected to the sixth electrode 413 formed independently on the substrate 401 or the base film separately from the first electrode 403 through the contact hole. There is no problem with the pattern shape.
Here, FIG. 11 is a cross-sectional view of still another embodiment of the electromechanical transducer according to the present invention, and FIG. 11B is still another embodiment of the electromechanical transducer according to the present invention. It is a top view in the form of. Here, in FIG. 11B, illustration of the second insulating protective film 409 is omitted for explanation.
As a result of the corona polarization treatment, excess charges flow through the fifth electrode 410 to the GND through the film formation diaphragm 402 and the substrate 401 below the sixth electrode 413, so that the pattern shapes as shown in FIGS. It has been confirmed that similar effects are obtained.

  When there are a plurality of individual electrode pads 411 as shown in FIG. 8B or the like, it is preferable that the vicinity of all the individual electrode pads 411 is surrounded by the fifth electrode 410. If the vicinity of all of the individual electrode pads 411 is not surrounded by the fifth electrode 410, the variation in characteristics within the column due to excessive progress of the polarization treatment, or the dielectric breakdown between the upper and lower electrodes due to the injection of excess charge, etc. A bug may occur.

The width of the fifth electrode 410 is preferably 20 μm or more and 100 μm or less.
Further, as shown in FIG. 9, an opening 414 a that is an area where the second insulating protective film 409 on the fifth electrode 410 is opened, and an area that surrounds the vicinity of the individual electrode pad 411. The positional relationship with the opening 414b is important. The distances d ₁ , d ₂ , and d ₅ between the opening 414a on the fifth electrode 410 and the opening 414b that is an area opened so as to surround the vicinity of the individual electrode pad 411 are 5 μm or more and 50 μm or less. It is preferable that the thickness is 6 μm or more and 20 μm or less. If the distance is shorter than this range, charge concentration occurs in the fifth electrode 410, so that charges are not easily accumulated in the individual electrode pad 411, and polarization does not progress. If the distance is longer than this range, the charge is almost accumulated in the individual electrode pad 411, so that the function of the fifth electrode 410 to accumulate excess charge cannot be sufficiently performed. Note that d ₁ , d ₂ , and d ₅ may be the same value or different values.

Further, as shown in FIG. 9, the opening widths w ₁ and w _{2 of} the region (414a, white background portion) where the second insulating protective film 409 is opened on the fifth electrode 410 are important and are 10 μm or more. It is preferable that the opening has a width of 20 μm or more. If the value is less than this value, most of the charge is accumulated in the individual electrode pad 411, so that the function of the fifth electrode 410 to accumulate excess charge cannot be sufficiently performed. _Further, it is preferable that w 1, _{w 2} is 80μm or less. Note that w ₁ and w ₂ may be the same value or different values.

Further, the distance (d ₃ , d ₄ , d ₆ ) between the electrode portion formed so as to surround the vicinity of the individual electrode pad 411 in the fifth electrode 410 and the individual electrode pad 411 is 3 μm or more and 50 μm. The following is preferable. If the distance is shorter than this range, charge concentration occurs in the fifth electrode 410, so that charges are not easily accumulated in the individual electrode pad 411, and polarization does not progress. If the distance is longer than this range, the charge is almost accumulated in the individual electrode pad 411, so that the function of the fifth electrode 410 to accumulate excess charge cannot be sufficiently performed. Note that d ₃ , d ₄ , and d ₆ may be the same value or different values.

Polarization processing was performed on the piezoelectric elements manufactured so far using the polarization processing apparatus shown in FIGS.
12 shows an external view of the polarization processing apparatus, and FIG. 13 is an explanatory diagram of wiring in the polarization processing apparatus of FIG. 14A is a cross-sectional view showing an example taken along the line AA ′ in FIG. 12, and FIG. 14B is a cross-sectional view showing another example taken along the line AA ′ in FIG.

  The polarization processing apparatus shown in FIG. 12 includes a corona electrode 71 and a grid electrode 73. The corona electrode 71 and the grid electrode 73 are connected to a corona electrode power source 72 and a grid electrode power source 74, respectively. At this time, as shown in FIG. 13, the other terminal not connected to the electrodes of the corona electrode power source 72 and the grid electrode power source 74 can be connected to the sample stage 75 where the sample is placed, for example. it can. Further, when the ground wire 76 is connected to the sample stage 75 as will be described later, it can be connected to the ground wire 76.

The configuration of the corona electrode 71 is not particularly limited. For example, the corona electrode 71 can have a wire shape as shown in the figure, and can be formed of various conductive materials.
The grid electrode 73 is disposed between the corona electrode 71 and the sample stage 75. The configuration of the grid electrode 73 is not particularly limited. For example, when the mesh process is performed and a high voltage is applied to the corona electrode 71, the sample stage that efficiently lowers ions, charges, and the like generated by corona discharge. It is preferable to be configured to pour down to 75.

  A heating mechanism is added to the sample stage 75 so that the electromechanical conversion element can be heated. The specific means of the heating mechanism for heating the electromechanical conversion element is not particularly limited, and can be configured to heat using various heaters, lamps, or the like. In addition, the heating mechanism can be installed in the sample stage 75 or can be installed so as to heat from outside the sample stage. In particular, in order to avoid interference with an electrode or the like, it is preferably installed in the sample stage 75.

A configuration example when a heating mechanism is installed in the sample stage 75 will be described with reference to FIG. In addition, as above-mentioned, it is not limited to the following structures.
As shown in FIG. 14A, the sample stage 75 includes a sample holding groove 751 formed in accordance with the sample shape and a heating mechanism 753 including a heating wire in the sample holding portion 752. It can be. In addition, as will be described later, a ground wire 76 may be provided on the sample stage 75. The above configuration is preferable because the sample is particularly easily heated by the heating mechanism 753 uniformly. In particular, from the viewpoint of heating the sample uniformly, the sample holder 752 is preferably made of a metal, and for example, stainless steel or Inconel (registered trademark) can be more preferably used. In particular, INCONEL (registered trademark) can be particularly preferably used from the viewpoint of heating the sample uniformly.

  As another configuration example, as illustrated in FIG. 14B, the sample stage 75 may be divided into a sample holding unit 752 and a heating mechanism holding unit 754. In this case, a sample holding groove 751 can be formed in the sample holding portion 752. Further, the heating mechanism holding portion 754 can have a heating mechanism 753 made of a heating wire or the like. In this case, the sample holding part 752 is preferably made of a metal in order to improve heat transfer, for example, stainless steel or Inconel (registered trademark) can be more preferably used, and heating is particularly uniform. Inconel [INCONEL] (registered trademark) can be particularly preferably used. In the configuration shown in FIG. 14B, the sample holding unit 752 and the heating mechanism holding unit 754 can be simply stacked, or both can be fixed with an adhesive or a fixture. You can also.

  14A and 14B illustrate an example in which the sample holding groove 751 is provided. However, the groove is not provided, and the sample holding portion 752 may be provided at any place. You may comprise so that a sample may be installed.

  The maximum heating temperature of the heating mechanism is not particularly limited, and may be configured to be heated to a predetermined temperature according to the Curie temperature of the electromechanical conversion film of the electromechanical conversion element manufactured as described later. It ’s fine. In particular, it is preferably configured to be able to heat up to a maximum of 350 ° C. so as to be compatible with various electromechanical conversion elements.

  Moreover, it is preferable that the sample stage 75 on which the sample is placed is grounded so that electric charges can easily flow with respect to the sample arranged on the sample stage. That is, the ground wire 76 is preferably connected to the sample stage 75.

The magnitude of the voltage applied to the corona electrode and grid electrode and the distance between the sample and each electrode are not particularly limited, and these are adjusted so that sufficient polarization treatment can be performed, and the strength of the corona discharge can be adjusted. You can turn it on.
Further, the amount of charge Q required for performing the polarization treatment is not particularly limited, but a positively charged charge is 1.0 × 10 ⁻⁸ C or more in the electromechanical transducer due to corona discharge or glow discharge. Is preferably accumulated, and more preferably, a charge amount of 4.0 × 10 ⁻⁸ C or more is accumulated. By accumulating the charge amount in such a range in the electromechanical conversion element, the polarization process can be performed so as to have a desired polarizability more reliably.

Here, the state of the polarization process is determined from the PE hysteresis loop. FIG. 15A is a graph showing a PE hysteresis loop before polarization processing, and FIG. 15B is a graph showing a PE hysteresis loop after polarization processing.
As shown in FIG. 15, the hysteresis loop was measured by applying an electric field strength of ± 150 kV / cm, and the polarization at the time of initial 0 kV / cm was 0 kV / cm when the polarization was returned to 0 kV / cm after applying the voltage of Pini, +150 kV / cm. When the time polarization is Pr, the value of Pr-Pini is defined as the polarizability, and the quality of the polarization state is judged from this polarizability. Here it is preferred that the polarizability Pr-Pini has become 10 [mu] C / cm ² or less, further preferably has a 5 [mu] C / cm ² or less. If this value is not reached, sufficient characteristics may not be obtained for displacement degradation after continuous driving as a PZT piezoelectric actuator.

  In order to obtain the desired polarizability Pr-Pini, it can be achieved by adjusting the corona, the grid electrode voltage, the sample stage and the corona, the distance between the grid electrodes, and the like as shown in FIGS. However, in order to obtain a desired polarizability, it is necessary to generate a high electric field for the electromechanical conversion film.

However, when the current between the individual electrodes as shown in FIG. 5 and the current between the common electrode and the individual electrodes were measured, it was found that the polarization treatment would not proceed if the amount of leakage current was large. Considering the polarization processing mechanism in the corona discharge, the charge that should be accumulated in the piezoelectric element via the pad portion is piezoelectric when a leak path occurs between individual electrodes or between individual and common electrodes. No charge is accumulated in the device. For this reason, the polarization process does not proceed. The amount of leakage current between individual electrodes or between individual and common electrodes is preferably 1.0 × 10 ⁻⁸ A or less when a voltage of 50 V is applied, more preferably 8. 0 × 10 ⁻¹⁰ A or less.
In the case of a leak amount higher than this, the polarization process does not proceed, so that sufficient characteristics cannot be obtained with respect to displacement deterioration after continuous driving as a PZT piezoelectric actuator.

Below, the material and construction method of each structure of the electromechanical conversion element of this invention are demonstrated concretely.
(Substrate 401)
As the substrate 401, a silicon single crystal substrate is preferably used, and usually has a thickness of 100 to 600 μm. There are three types of plane orientations, (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry. A single crystal substrate having a plane orientation of 100) was mainly used. In addition, when a pressure chamber as shown in FIG. 1 is manufactured, a silicon single crystal substrate is processed using etching. In this case, anisotropic etching is generally used as an etching method. Is.

Anisotropic etching utilizes the property that the etching rate differs with respect to the plane orientation of the crystal structure. For example, in anisotropic etching immersed in an alkaline solution such as KOH, the (111) plane has an etching rate of about 1/400 compared to the (100) plane. Accordingly, a structure having an inclination of about 54 ° can be produced in the plane orientation (100), whereas a deep groove can be formed in the plane orientation (110). For this reason, it has been found that in the plane orientation (110), the arrangement density can be increased while maintaining rigidity, and a single crystal substrate having the (110) plane orientation can be used as this configuration. is there. However, in this case, SiO ₂ which is a mask material is also etched, so this area is also used with attention.

(Film-forming diaphragm 402)
As shown in FIG. 1, upon receiving the force generated by the electromechanical conversion film, the base (film formation diaphragm 402) is deformed and displaced, and ink droplets in the pressure chamber are ejected. Therefore, it is preferable that the base has a predetermined strength.
Examples of the material for the film formation diaphragm 402 include Si, SiO ₂ , and Si ₃ N ₄ produced by the CVD method. Furthermore, it is preferable to select a material close to the linear expansion coefficient of the first electrode 403 and the electromechanical conversion film 404. In particular, as an electromechanical conversion film, since PZT is generally used as a material, a linear expansion coefficient close to 8 × 10 ⁻⁶ (1 / K) is 5 × 10 ⁻⁶ to 10 × 10. A material having a linear expansion coefficient of ⁻⁶ is preferable, and a material having a linear expansion coefficient of 7 × 10 ^{−6 to} 9 × 10 ⁻⁶ is more preferable.

  Specific examples of the material include aluminum oxide, zirconium oxide, iridium oxide, ruthenium oxide, tantalum oxide, hafnium oxide, osmium oxide, rhenium oxide, rhodium oxide, palladium oxide, and compounds thereof. It can be produced with a spin coater using the Sol-gel method. The film thickness is preferably from 0.1 to 10 μm, more preferably from 0.5 to 3 μm. If it is smaller than this range, the processing of the pressure chamber as shown in FIG. 1 becomes difficult, and if it is larger than this range, the base becomes difficult to be deformed and displaced, and ink droplet ejection becomes unstable.

(First electrode 403, sixth electrode 413)
The first electrode 403 and the sixth electrode 413 preferably include a metal or metal electrode film and an oxide electrode film. Here, both are devised so as to suppress peeling and the like by putting an adhesion layer between the diaphragm and the metal or metal electrode film.
Details of the metal electrode film and oxide electrode film including the adhesion layer are described below.

-Adhesion layer After sputter deposition of Ti, using a rapid thermal annealing (RTA) apparatus, the titanium film is thermally oxidized in an O ₂ atmosphere at 650 to 800 ° C. for 1 to 30 minutes to convert the titanium film into a titanium oxide film. To do. 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 TiO ₂ 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. As materials other than Ti, materials such as Ta, Ir, and Ru are also preferable.

  The film thickness of the adhesion layer is preferably 10 nm to 50 nm, and more preferably 15 nm to 30 nm. If it is less than this range, there is a concern about adhesion. On the other hand, exceeding this range affects the crystal quality of the electrode film produced on the adhesion layer.

・ Metal electrode film Conventionally, platinum with high heat resistance and low reactivity has been used as the material for the metal electrode film, but it may not be said that it has sufficient barrier properties against lead. And platinum group elements such as platinum-rhodium and alloy films thereof. In addition, when platinum is used, the adhesion layer is preferably laminated first because of poor adhesion to the base (particularly SiO ₂ ).
As a manufacturing method, vacuum film formation such as sputtering or vacuum deposition is generally used. As a film thickness, 80-200 nm is preferable and 100-150 nm is preferable. If the thickness is smaller than this range, a sufficient current cannot be supplied as a common electrode, and a problem occurs when ink is ejected. When the thickness is larger than this range, the cost increases when an expensive material of a platinum group element is used. When the thickness is larger than the above range, when the material is platinum, the surface roughness increases as the film thickness increases, and the surface roughness or crystal of the oxide electrode film or PZT formed thereon is increased. There is a problem that the orientation is affected and a sufficient displacement for ink ejection cannot be obtained.

-Oxide electrode film About an oxide electrode film, it has a big influence on the crystal growth as a seed layer with respect to the electromechanical conversion film produced on it. For example, when PZT is used as the electromechanical conversion film, the crystal orientation state of PZT varies greatly depending on the type of oxide electrode film. As a specific example, when aiming at PZT (111) orientation, SrRuO ₃ material or the like is preferable, and when aiming at PZT (100) orientation, LaNiO ₃ material or the like is preferred. Further, PZT (100) and PZT (111) can be arbitrarily adjusted for the thermally oxidized TiOx seed depending on the film thickness range. However, the oxide electrode film is not limited to these materials. Regardless of whether PZT (111) or PZT (100) is preferentially oriented, it is possible to maintain a stable state as shown in FIG. In terms of time, it is advantageous in the process tact to perform PZT (111) preferential orientation.

Here, in order to preferentially orient PZT (111), a SrRuO ₃ material is selected and its detailed manufacturing method will be described. For SrRuO ₃ , besides Sr _x (A) _(1-x) Ru _y (B) _(1-y) , A = Ba, Ca, B = Co, Ni, x, y = 0 to 0 Also mentioned are materials as described in .5. The film forming method is produced by sputtering. Although the film quality of the SrRuO ₃ thin film changes depending on the sputtering conditions, in particular, the crystal orientation is emphasized, and in order to align the SrRuO ₃ film also with the (111) orientation following the Pt (111) of the first electrode, It is preferable to form a film by heating the substrate at 500 ° C. or higher.
For example, regarding the SRO film formation conditions described in Japanese Patent No. 3784401, the film is formed at room temperature, and then thermally oxidized at the crystallization temperature (650 ° C.) by the RTA treatment. In this case, the SRO film is sufficiently crystallized, and a sufficient value is obtained as the specific resistance as an electrode. However, as the crystal orientation of the film, (110) tends to be preferentially oriented, and the film is formed thereon. The (110) orientation of the deposited PZT is also facilitated.

  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 tilting the Psi direction by about 35 ° and judging from the peak intensity where 2θ is about 32 °.

  FIG. 20 shows data 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 °. From this, it was confirmed that SRO was (111) oriented for those fabricated under the present film forming conditions. 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 °.

  As will be described in detail later, when the amount of displacement after driving was deteriorated compared to the initial displacement when continuously operating as a piezoelectric actuator, the orientation of PZT has a great influence. 110) is insufficient in suppressing displacement deterioration. Further, when the surface roughness of the SRO film is observed, it affects the film formation temperature, and the surface roughness is very small from room temperature to 300 ° C. and becomes 2 nm or less. As for the roughness, surface roughness (average roughness) measured by an AFM (Atomic Force Microscope) 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 nm to 15 nm, and more preferably 6 nm to 10 nm. If this range is exceeded, the dielectric breakdown voltage of the PZT deposited thereafter is very poor and leaks easily. Therefore, in order to obtain the crystallinity and surface roughness as described above, the film formation temperature is in the range of 500 ° C. to 700 ° C., preferably 520 ° C. to 600 ° C.

  Regarding the composition ratio of Sr and Ru after film formation, Sr / Ru is preferably 0.82 or more and 1.22 or less. If it is out of this range, the specific resistance increases, and sufficient conductivity as an electrode cannot be obtained.

  Furthermore, the film thickness of the SRO film is preferably 40 nm to 150 nm, and more preferably 50 nm to 80 nm. If the thickness is smaller than this range, sufficient characteristics cannot be obtained for initial displacement and displacement deterioration after continuous driving, and it is difficult to obtain a function as a stop etching layer for suppressing overetching of PZT. 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 this range is exceeded, sufficient contact resistance cannot be obtained at the interface with the fifth electrode 410 as a common electrode, and sufficient current cannot be supplied as the common electrode, causing problems when ink is ejected. To do.

(Electromechanical conversion film 404)
As a material of the electromechanical conversion film 404, PZT was mainly used. PZT is a solid solution of lead zirconate (PbTiO 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. In terms of chemical formula, Pb (Zr _0.53 , Ti _0.47 ) O ₃ , generally PZT (53 / 47). Examples of composite oxides other than PZT include barium titanate. In this case, it is also possible to prepare a barium titanate precursor solution by dissolving barium alkoxide and a titanium alkoxide compound in a common solvent. is there.

These materials are described by the general formula ABO ₃ and correspond to composite oxides containing A = Pb, Ba, Sr B = Ti, Zr, Sn, Ni, Zn, Mg, and Nb as main components. Specific descriptions thereof include (Pb _1-x , Ba _x ) (Zr, Ti) O ₃ , (Pb _1-x , Sr _x ) (Zr, Ti) O ₃ , and the like, which are Pb of the A site. Is partially replaced with Ba or Sr. Such substitution is possible with a divalent element, and the effect thereof has an effect of reducing characteristic deterioration due to evaporation of lead during heat treatment.

As a manufacturing method, it can be manufactured by a spin coater using a sputtering method or a Sol-gel method. In that case, since patterning is required, a desired pattern is obtained by photolithography etching or the like.
When PZT is produced by the Sol-gel method, 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 a PZT film is obtained on the entire surface of the base substrate, it is obtained by forming a coating film by a solution coating method such as spin coating and performing heat treatments such as solvent drying, thermal decomposition, and crystallization. Since 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.

The film thickness of the electromechanical conversion film is preferably 0.5 to 5 μm, more preferably 1 μm to 2 μm. If the thickness is smaller than this range, sufficient displacement cannot be generated. If the thickness is larger than this range, many thin layers are stacked, so that the number of steps increases and the process time becomes longer.
The insulation resistance of the electromechanical conversion film is preferably 5.0 × 10 ¹⁰ Ω or more.

  The relative dielectric constant is preferably 600 or more and 2000 or less, and more preferably 1200 or more and 1600 or less. At this time, when the value is less than this value, sufficient displacement characteristics cannot be obtained, and when the value is larger than this value, the polarization process is not performed sufficiently, and sufficient characteristics cannot be obtained for displacement deterioration after continuous driving. A malfunction occurs.

(Second electrode 409)
The second electrode 409 is preferably made of a metal or an oxide and a metal.
Details of the oxide electrode film and the metal electrode film are described below.

-Oxide electrode film About the material of an oxide electrode film, the same thing as what was described by the oxide electrode film used by the 1st electrode 403 can be used, As a film thickness of SRO film | membrane, 20 nm-80 nm Is preferable, and 40 to 60 nm is more preferable. If the thickness is less than this range, sufficient characteristics cannot be obtained for the initial displacement and displacement deterioration characteristics. If this range is exceeded, the dielectric breakdown voltage of the PZT deposited thereafter is very poor and leaks easily.

-Metal electrode film The material of the metal electrode film can be the same as that described for the metal electrode film used in the first electrode 403, and the film thickness is preferably 30-200 nm, preferably 50-120 nm. Further preferred. When the thickness is smaller than this range, a sufficient current cannot be supplied as the individual electrode, and a problem occurs when ink is ejected. If it is thicker than this range, the cost increases when using an expensive platinum group element material, or the surface roughness increases when the film thickness is increased when platinum is used as the material. When the sixth electrode 413 is manufactured via the insulating protective film, process defects such as film peeling are likely to occur.

(First insulating protective film 406)
As a material for the first insulating protective film 406, it is necessary to select a material that prevents damage to the piezoelectric element due to the film formation / etching process and is difficult to transmit moisture in the atmosphere. It is preferable to do. An organic material is not preferable because the film thickness needs to be increased in order to obtain sufficient protection performance. If the first insulating protective film 406 is a thick film, the vibration displacement of the diaphragm is significantly inhibited, resulting in an inkjet head with low ejection performance.

In order to obtain high protection performance with a thin film, it is preferable to use an oxide, a nitride, or a carbonized film. However, the electrode material, the piezoelectric material, and the diaphragm material that form the base of the first insulating protective film 406 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. 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 preferable film forming methods include vapor deposition and ALD (Atomic Layer Deposition), but ALD is preferable because of the wide choice of materials that can be used. As a preferable material of the first insulating protective film 406, an oxide film used for a ceramic material such as Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , and TiO ₂ can be given as an example. 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 406 needs to be a thin film enough to ensure the protection performance of the piezoelectric element, and at the same time, it needs to be as thin as possible so as not to disturb the displacement of the diaphragm. A preferable thickness of the first insulating protective film 406 is in the range of 20 nm to 100 nm. If it is thicker than 100 nm, the displacement of the diaphragm is reduced, and the ink jet head has a low ejection efficiency. On the other hand, when the thickness is less than 20 nm, the function of the piezoelectric element as a protective layer is insufficient, so that the performance of the piezoelectric element is deteriorated as described above.

A configuration in which the first insulating protective film 406 has two layers is also conceivable. In this case, in order to increase the thickness of the second insulating protective film, a configuration in which the second insulating protective film is opened in the vicinity of the second electrode portion so as not to significantly disturb the vibration displacement of the diaphragm can be cited. . At this time, as the second insulating protective film, any oxide, nitride, carbide, or a composite compound thereof can be used, but SiO ₂ generally used in semiconductor devices can be used. Arbitrary methods can be used for the film formation, and a CVD method and a sputtering method can be exemplified, and 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 thickness of the second insulating protective film needs to be a thickness that does not cause dielectric breakdown by the voltage applied to the lower electrode and the individual electrode wiring. That is, it is necessary to set the electric field strength applied to the insulating protective film within a range not causing dielectric breakdown. Furthermore, considering the surface properties of the base of the insulating protective film, pinholes, etc., the film thickness needs to be 200 nm or more, and more preferably 500 nm or more.

(Third electrode 407, fourth electrode 408, fifth electrode 410)
The material of the third electrode 407, the fourth electrode 408, and the fifth electrode 410 is preferably a metal electrode material made of Ag alloy, Cu, Al, Au, Pt, or Ir. As a manufacturing method, 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 from 0.1 to 20 μm, more preferably from 0.2 to 10 μm. If the thickness is smaller than this range, the resistance increases and a sufficient current cannot be supplied to the electrode, and the head discharge becomes unstable. If the thickness 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) as the common electrode and the individual electrode is preferably 10Ω or less for the common electrode, 1Ω or less for the individual electrode, and more preferably 5Ω or less for the common electrode. The individual electrode is 0.5Ω or less. If this range is exceeded, it will not be possible to supply a sufficient current, and problems will occur when ink is ejected.

(Second insulating protective film 409)
The function as the second insulating protective film 409 is a passivation layer having a function of a protective layer for individual electrode wiring and common electrode wiring. As shown in FIG. 5, the individual electrode and the common electrode are covered except for the portions of the individual electrode lead portion (on the individual electrode pad 411) and the common electrode lead portion (on the common electrode pad 412). This makes it possible to use inexpensive Al or an alloy material mainly composed of Al 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 409, 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, 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 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 small, 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 a thin film portion (not shown) on the piezoelectric element and the surrounding diaphragm is preferable. For example, in FIG. 8A, the second insulating protective film 409 is on the electromechanical conversion film 404 (second electrode 405) and at a position excluding the region where the fourth electrode 408 is disposed. It is preferable that it is formed thinner than other portions. This is the same reason that the individual liquid chamber region of the first insulating protective film 406 is thinned. This makes it possible to obtain a highly efficient and highly reliable ink jet head.

For the formation of the opening, photolithography and dry etching can be used because the piezoelectric element is protected by the insulating film. Further, the area of the pad portion is preferably 50 × 50 μm ² or more, and more preferably 100 × 300 μm ² or more. When the value is less than this value, sufficient polarization processing cannot be performed, and there is a problem that sufficient characteristics cannot be obtained with respect to displacement deterioration after continuous driving.

  Next, an ink jet head (droplet discharge head) and an ink jet recording apparatus (droplet discharge apparatus) according to the present invention will be described.

  FIG. 1 shows a configuration example of a one-nozzle droplet discharge head. FIG. 1 shows a droplet discharge head that includes a nozzle 102 that discharges droplets, a pressurizing chamber 101 that communicates with the nozzle 102, and a discharge driving unit that pressurizes the liquid in the pressurizing chamber 101. The discharge driving means includes a diaphragm (base 105) that constitutes a part of the wall of the pressurizing chamber 101, and the electromechanical conversion element according to the present invention is disposed on the diaphragm.

  FIG. 17 shows a configuration in which a plurality of these are arranged (another configuration example of the droplet discharge head). According to the present invention, the electromechanical conversion element in the figure can be formed by a simple manufacturing process (and having performance equivalent to that of bulk ceramics), and etching removal from the back surface for forming a pressure chamber and nozzle holes can be formed. A droplet discharge head can be formed by joining the nozzle plates. In the figure, descriptions of liquid supply means, flow paths, and fluid resistance are omitted.

  Next, an example of a droplet discharge device equipped with the droplet discharge head according to the present invention will be described with reference to FIGS. 18 is a perspective explanatory view of a droplet discharge device according to the present invention, and FIG. 19 is a side view of a mechanism portion of the droplet discharge device according to the present invention.

  This ink jet recording apparatus includes a carriage movable in the main scanning direction inside the recording apparatus main body 81, a recording head composed of an ink jet head embodying the present invention mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. A sheet feeding cassette (or a sheet feeding tray) 84 on which a large number of sheets 83 can be stacked from the front side is detachably attached to the lower part of the apparatus main body 81. The manual feed tray 85 for manually feeding the paper 83 can be opened, the paper 83 fed from the paper feed cassette 84 or the manual feed tray 85 is taken in, and the printing mechanism 82 After recording a required image, the image is discharged to a paper discharge tray 86 mounted on the rear side.

  The printing mechanism 82 holds a carriage 93 slidably in the main scanning direction by a main guide rod 91 and a sub guide rod 92 which are guide members horizontally mounted on left and right side plates (not shown). (Y), cyan (C), magenta (M), black (Bk) A head 94 comprising an ink jet head according to the present invention for ejecting ink droplets of each color has a plurality of ink ejection openings (nozzles) as 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 95 for supplying ink of each color to the head 94 is replaceably mounted on the carriage 93.

  The ink cartridge 95 has an air port that communicates with the atmosphere upward, a supply port that supplies ink to the inkjet head below, and a porous body filled with ink inside, and the capillary force of the porous body. Thus, the ink supplied to the inkjet head is maintained at a slight negative pressure. Further, although the heads 94 of the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets of the respective colors may be used.

  Here, the carriage 93 is slidably fitted to the main guide rod 91 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 92 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 93 in the main scanning direction, a timing belt 100 is stretched between a driving pulley 98 and a driven pulley 99 that are rotationally driven by a main scanning motor 97, and the timing belt 100 is moved to the carriage 93. The carriage 93 is driven to reciprocate by forward and reverse rotation of the main scanning motor 97.

  On the other hand, in order to convey the paper 83 set in the paper feed cassette 84 to the lower side of the head 94, the paper feed roller 101 and the friction pad 102 for separating and feeding the paper 83 from the paper feed cassette 84 and the paper 83 are guided. A guide member 103, a transport roller 104 that reverses and transports the fed paper 83, a transport roller 105 that is pressed against the peripheral surface of the transport roller 104, and a leading end that defines a feed angle of the paper 83 from the transport roller 104 A roller 106 is provided. The transport roller 104 is rotationally driven by a sub-scanning motor 107 through a gear train.

  A printing receiving member 109 is provided as a paper guide member that guides the paper 83 sent from the transport roller 104 below the recording head 94 in accordance with the movement range of the carriage 93 in the main scanning direction. A conveyance roller 111 and a spur 112 that are rotationally driven to send the paper 83 in the paper discharge direction are provided on the downstream side of the printing receiving member 109 in the paper conveyance direction, and the paper 83 is further delivered to the paper discharge tray 86. A roller 113 and a spur 114, and guide members 115 and 116 that form a paper discharge path are disposed.

  At the time of recording, the recording head 94 is driven according to the image signal while moving the carriage 93, thereby ejecting ink onto the stopped sheet 83 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 83 has reached the recording area, the recording operation is terminated and the paper 83 is discharged.

  Further, a recovery device 117 for recovering defective ejection of the head 94 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 93. The recovery device 117 includes a cap unit, a suction unit, and a cleaning unit. The carriage 93 is moved to the recovery device 117 side during printing standby and the head 94 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 94 is sealed with a capping unit, and bubbles and the like are sucked out from the discharge port with the suction unit through the tube. Is removed by the cleaning means to recover the ejection failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  In the droplet discharge device of the present invention, it is possible to suppress ink droplet discharge failure due to vibration plate drive failure and the like, and to improve stable ink droplet discharge characteristics and image quality.

  Examples of the present invention will be described below. In addition, this invention is not limited to the Example illustrated here.

<Example 1>
A thermal oxide film (film thickness: 1 μm) is formed on a 6-inch silicon wafer, and a titanium film (film thickness: 30 nm) is formed as an adhesion layer of the first electrode 403 by a sputtering apparatus at a film formation temperature of 350 ° C. Is thermally oxidized at 750 ° C. Subsequently, a platinum film (film thickness 100 nm) was formed as a metal electrode film by a sputtering apparatus at a film formation temperature of 550 ° C., and an SrRuO film (film thickness 50 nm) was formed as an oxide electrode film by sputtering. The substrate heating temperature during the SrRuO sputtering film formation was 450 ° C., and then a post-annealing process (550 ° C.) was performed using RTA. Next, a solution adjusted to Pb: Zr: Ti = 115: 53: 47 was prepared as an electromechanical conversion film 404, and a film was formed by spin coating.
Here, as a sputtering apparatus, a film was formed using a single chamber equipped with a plurality of targets.

  For the synthesis of a specific precursor coating solution, lead acetate trihydrate, isopropoxide titanium and isopropoxide zirconium were used as starting materials. Crystal water of lead acetate was dissolved in methoxyethanol and then dehydrated. The lead amount is excessive with respect to the stoichiometric composition. This is to prevent crystallinity deterioration due to so-called lead loss during heat treatment. Isopropoxide titanium and isopropoxide zirconium were dissolved in methoxyethanol, the alcohol exchange reaction and the esterification reaction were advanced, and the PZT precursor solution was synthesized by mixing with the methoxyethanol solution in which the lead acetate was dissolved. The PZT concentration was 0.5 mol / l. Using this solution, a film was formed by spin coating. After film formation, the film was dried at 120 ° C. and then thermally decomposed at 500 ° C. After thermal decomposition treatment of the third layer, crystallization heat treatment (temperature: 750 ° C.) was performed by RTA (rapid heat treatment). At this time, the film thickness of PZT was 240 nm. This process was performed a total of 8 times (24 layers) to obtain a PZT film thickness of about 2 μm.

Next, an SrRuO film (film thickness: 40 nm) was formed as the oxide electrode film of the second electrode 405, and a Pt film (film thickness: 125 nm) was formed as the metal electrode film by sputtering. Thereafter, a photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. was formed by spin coating, a resist pattern was formed by ordinary photolithography, and then a pattern was prepared using an ICP etching apparatus (manufactured by Samco). Next, as the first insulating protective film 406, an Al ₂ O ₃ film having a thickness of 50 nm was formed using an ALD method. At this time, the film formation was advanced by alternately laminating TMA (trimethylaluminum, Sigma-Aldrich) for Al as raw materials and O ₃ generated by an ozone generator for O. Thereafter, contact hole portions are formed by etching. After that, Al is sputter-deposited as the third electrode 407, the fourth electrode 408, and the fifth electrode 410, patterned by etching, and Si ₃ N ₄ is deposited as the second insulating protective film 409 by 500 nm by plasma CVD. Film formation was performed to produce an electromechanical transducer.
The structure shown in FIG. 8 was produced.

  Thereafter, polarization treatment was performed by corona charging treatment using the polarization treatment apparatus shown in FIG. For the corona charging treatment, a tungsten wire of φ50 μm is used. The polarization treatment conditions were a treatment temperature of 80 ° C., a corona voltage of 9 kV, a grid voltage of 2.5 kV, a treatment time of 30 s, a corona electrode-grid electrode distance of 4 mm, and a grid electrode-stage distance of 4 mm.

  The distance between the fifth electrode 410 and the individual electrode pad 411, the width of the fifth electrode 410, and the opening width of the fifth electrode 410 as shown in FIG. 9 were 25 μm, 25 μm, and 15 μm. A plurality of individual electrode pads 411 were prepared as shown in FIG. 8, and all of the individual electrode pads 411 were surrounded by the fifth electrode 410. In each individual electrode pad 411, the distance between the fifth electrode 410 and the individual electrode pad 411, the width of the fifth electrode 410, and the opening width of the fifth electrode 410 were all set to the above values.

<Example 2>
As for the distance between the fifth electrode 410 and the individual electrode pad 411, the width of the fifth electrode 410, and the opening width of the fifth electrode 410 as shown in FIG. 9, except that they were prepared at 15 μm, 20 μm and 10 μm. An electromechanical transducer was prepared in the same manner as in Example 1.

<Example 3>
As for the distance between the fifth electrode 410 and the individual electrode pad 411, the width of the fifth electrode 410, and the opening width of the fifth electrode 410 as shown in FIG. 9, except that they were prepared at 50 μm, 20 μm and 10 μm. An electromechanical transducer was prepared in the same manner as in Example 1.

<Example 4>
As for the distance between the fifth electrode 410 and the individual electrode pad 411, the width of the fifth electrode 410, and the opening width of the fifth electrode 410 as shown in FIG. 9, except that they were prepared at 5 μm, 20 μm and 10 μm. An electromechanical transducer was prepared in the same manner as in Example 1.

<Example 5>
An electromechanical transducer was produced in the same manner as in Example 1 except that the structure shown in FIG. 10 was produced.

<Example 6>
An electromechanical transducer was produced in the same manner as in Example 1 except that the structure shown in FIG. 11 was produced. Note that the sixth electrode 413 was manufactured in the same manner as the first electrode manufacturing method.

<Comparative Example 1>
An electromechanical transducer was prepared in the same manner as in Example 1 except that the structure shown in FIG.

<Reference Example 1>
As for the distance between the fifth electrode 410 and the individual electrode pad 411, the width of the fifth electrode 410, and the opening width of the fifth electrode 410 as shown in FIG. 9, except that they were prepared at 60 μm, 10 μm and 5 μm. An electromechanical transducer was prepared in the same manner as in Example 1.

<Reference Example 2>
The distance between the fifth electrode 410 and the individual electrode pad 411, the width of the fifth electrode 410, and the opening width of the fifth electrode 410 as shown in FIG. An electromechanical transducer was prepared in the same manner as in Example 1.

For the electromechanical transducers produced in Examples 1 to 6, Comparative Example 1 and Reference Examples 1 and 2, it was confirmed whether there was an appearance defect such as a discharge mark with respect to the Bits of all electrode pads after the polarization treatment process. . Furthermore, the electrical characteristics and electromechanical conversion ability (piezoelectric constant) were evaluated using the produced electromechanical conversion element. A typical PE hysteresis curve is shown in FIG. The electromechanical conversion capacity was calculated from the amount of deformation caused by an applied electric field (150 kV / cm) measured with a laser Doppler vibrometer and adjusted by simulation. After evaluating the initial characteristics, durability (characteristics immediately after applying the applied voltage 10 to ¹⁰ times) was evaluated. These detailed results are summarized in Table 1.

About Examples 1-6, it had the characteristic equivalent to a general ceramic sintered compact also about the initial characteristic and the result after a durability test (piezoelectric constant is -120--160 pm / V).
On the other hand, in Comparative Example 1 and Reference Example 1, discharge marks were generated after the polarization treatment, and the electrical characteristics and the like after that could not be evaluated. In Reference Example 2, it was confirmed that the polarizability was high and the piezoelectric constant was greatly deteriorated in the results after the durability test.
In Reference Examples 1 and 2, any of a plurality of configurations including a distance between the fifth electrode 410 and the individual electrode pad 411, a width of the fifth electrode 410, and an opening width of the fifth electrode 410 is within a preferable range. The effect of the present invention is not achieved because it is off. However, according to the present invention, any of a plurality of configurations of the distance between the fifth electrode 410 and the individual electrode pad 411, the width of the fifth electrode 410, and the opening width of the fifth electrode 410 is within a preferable range. This is not necessarily required, and the desired effect can be obtained by appropriately adjusting other configurations instead of these.

Next, using the electromechanical transducers manufactured in Examples 1 to 6, the droplet discharge head shown in FIG. 17 was prepared, and liquid discharge was evaluated. Using an ink whose viscosity was adjusted to 5 cp, the discharge state when an applied voltage of −10 to −30 V was applied with a simple Push waveform was confirmed, and it was confirmed that discharge was possible from any nozzle hole.
In addition, in the droplet discharge device equipped with the droplet discharge heads manufactured in Examples 1 to 6, there was no ink droplet discharge failure due to vibration plate drive failure, stable ink droplet discharge characteristics were obtained, and image quality was improved. .

(About FIG.1 and FIG.17)
101 Pressurizing chamber 102 Nozzle 103 Nozzle plate 104 Pressurizing chamber substrate (Si substrate)
105 Base 106 Lower electrode 107 Electromechanical conversion film 108 Upper electrode 109 Electromechanical conversion element (piezoelectric body)
(About Figure 2)
20 domain 21 direction of polarization (for FIGS. 4, 5, and 7-11)
401 Substrate 402 Deposition diaphragm 403 First electrode 404 Electromechanical conversion film 405 Second electrode 406 First insulating protective film 407 Third electrode 408 Fourth electrode 409 Second insulating protective film 410 Fifth Electrode 411 Individual electrode pad 412 Common electrode pad 413 Sixth electrode 414a Opening portion 414b on fifth electrode Opening portion on individual electrode pad

Japanese Patent No. 3365485 Japanese Patent No. 4218309 Japanese Patent No. 3019845 JP 2004-202849 A JP 2010-34154 A JP 2006-203190 A

Claims (9)

A substrate,
A first electrode that is a common electrode formed on the substrate;
An electromechanical conversion film formed on the first electrode;
A second electrode that is an individual electrode formed on the electromechanical conversion film;
A first insulating protective film provided on the first electrode and the second electrode and having a contact hole;
A third electrode formed to be electrically connected to the first electrode through the contact hole;
A fourth electrode formed to be electrically connected to the second electrode through the contact hole;
A common electrode pad formed on the third electrode;
A plurality of individual electrode pads formed on the fourth electrode and arranged in a predetermined row;
A second insulating protective film provided on the third electrode and the fourth electrode, wherein openings are formed in portions corresponding to the common electrode pad and the plurality of individual electrode pads, respectively. When,
A fifth electrode formed so as to surround each of the individual electrode pads; and
The electromechanical conversion element, wherein the fifth electrode is formed on the first insulating protective film and is electrically connected to the first electrode through the contact hole. A substrate,
A first electrode that is a common electrode formed on the substrate;
An electromechanical conversion film formed on the first electrode;
A second electrode that is an individual electrode formed on the electromechanical conversion film;
A first insulating protective film provided on the first electrode and the second electrode and having a contact hole;
A third electrode formed to be electrically connected to the first electrode through the contact hole;
A fourth electrode formed to be electrically connected to the second electrode through the contact hole;
A common electrode pad formed on the third electrode;
A plurality of individual electrode pads formed on the fourth electrode and arranged in a predetermined row;
A second insulating protective film provided on the third electrode and the fourth electrode, wherein openings are formed in portions corresponding to the common electrode pad and the plurality of individual electrode pads, respectively. When,
A fifth electrode formed so as to surround each of the individual electrode pads;
A sixth electrode that conducts through the fifth electrode and the contact hole;
The fifth electrode is formed on the first insulating protective film;
The sixth electrode is formed on the substrate independently of the first electrode, and is an electromechanical transducer. The electromechanical transducer according to claim 1, wherein the fifth electrode is electrically connected to the third electrode. The second insulating protective film is formed on the fifth electrode;
The electromechanical transducer according to any one of claims 1 to 3 , wherein the second insulating protective film is opened so as to surround the vicinity of each of the individual electrode pads. Electromechanical transducer according to any one of claims 1 to 4, wherein the fifth electrode is characterized in that surround the near pad for individual electrodes except for respective portions of the individual electrode pads. 2. The second insulating protective film on the fifth electrode is opened so as to surround the vicinity of the individual electrode pad except for a part of the individual electrode pad. The electromechanical transducer according to any one of 5 to 5 . By corona discharge or glow discharge, the positively charged charge is generated so that the charge amount becomes 1.0 × 10 -8 or ^C, wherein the electro-mechanical conversion element according to any one of claims 1 to 6 of the A method of manufacturing an electromechanical transducer, comprising a polarization step of performing polarization treatment of the electromechanical transducer film via one electrode and the second electrode. In a droplet discharge head comprising a nozzle that discharges a droplet, a pressure chamber that communicates with the nozzle, and a discharge driving means that pressurizes the liquid in the pressure chamber.
The discharge driving means has a diaphragm constituting a part of the wall of the pressurizing chamber,
A liquid droplet ejection head, wherein the electromechanical transducer according to any one of claims 1 to 6 is disposed on the diaphragm. A droplet discharge apparatus comprising the droplet discharge head according to claim 8 .