JP2011238708A - Liquid ejection head manufacturing method, liquid ejection device, and piezoelectric element manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid ejection head manufacturing method, a liquid ejection device, and a piezoelectric element manufacturing method, with which an environmental load is reduced and occurrence of a leak current is suppressed.SOLUTION: A first electrode 60 is formed. An application liquid 71 is applied onto the first electrode 60, the application liquid 71 including an organic metallic compound, which forms a complex oxide containing bismuth, ferrum, manganese, potassium, and titanium through baking, and polyvinylpyrrolidone. A piezoelectric layer 72 made of a complex oxide having a perovskite-type structure is formed by baking the application liquid 71. A second electrode is formed on the piezoelectric layer 72.

Description

  The present invention relates to a method for manufacturing a piezoelectric element in which a piezoelectric layer and electrodes are provided on both sides thereof, a method for manufacturing a liquid ejecting head having a piezoelectric element, and a liquid ejecting apparatus.

  As a piezoelectric element used in a liquid ejecting head, there is a piezoelectric material that exhibits an electromechanical conversion function, for example, a piezoelectric layer made of a crystallized dielectric material and sandwiched between two electrodes. Such a piezoelectric element is mounted on the liquid ejecting head as an actuator device in a flexural vibration mode, for example. As a typical example of a liquid ejecting head, for example, a part of a pressure generation chamber communicating with a nozzle opening for ejecting ink droplets is configured by a vibration plate, and the vibration plate is deformed by a piezoelectric element so that the ink in the pressure generation chamber is There is an ink jet recording head that pressurizes and ejects ink droplets from nozzle openings.

  A piezoelectric material used as a piezoelectric layer (piezoelectric ceramics) constituting such a piezoelectric element is required to have high piezoelectric characteristics, and a typical example is lead zirconate titanate (PZT) (Patent Document 1). reference).

However, from the viewpoint of environmental problems, there is a demand for a piezoelectric material with a reduced lead content. The piezoelectric material not containing lead, for example, chemical composition _{x [(Bi a K 1-} a) TiO 3] - (1-x) [BiFeO 3] ( where, 0.3 ≦ x ≦ 0.8, A piezoelectric ceramic represented by 0.4 <a <0.6) is disclosed (see Patent Document 2).

JP 2001-223404 A JP 2008-069051 A

  The piezoelectric ceramic described in Patent Document 2 is a so-called bulk material with a large film thickness. If this material is made into a thin film, insulation is low and leakage current is generated, so that it is difficult to use for piezoelectric elements. There is a problem.

  Such a problem exists not only in the ink jet recording head, but of course in other liquid ejecting heads that eject droplets other than ink, and also in piezoelectric elements used in other than liquid ejecting heads. Exist as well.

  SUMMARY An advantage of some aspects of the invention is that it provides a method for manufacturing a liquid ejecting head, a liquid ejecting apparatus, and a method for manufacturing a piezoelectric element that reduce an environmental load and suppress the generation of a leak current.

According to an aspect of the present invention for solving the above-described problem, a liquid ejecting head including a pressure generating chamber communicating with a nozzle opening for ejecting liquid, and a piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode is manufactured. A method of forming a first electrode; an organometallic compound that forms a composite oxide containing bismuth, iron, manganese, potassium, and titanium by firing above the first electrode; and polyvinylpyrrolidone; A step of applying a coating solution containing a material, a step of baking the coating solution to form a piezoelectric layer made of a composite oxide having a perovskite structure, and a step of forming the second electrode above the piezoelectric layer. And a liquid ejecting head manufacturing method comprising:
In this aspect, a liquid ejecting head that has high insulation and suppresses the occurrence of leakage current is manufactured by forming a piezoelectric layer made of a composite oxide having a perovskite structure containing bismuth, iron, manganese, potassium, and titanium. can do. Moreover, since the lead content can be suppressed, the burden on the environment can be reduced. Furthermore, in the piezoelectric layer forming step, by adding polyvinylpyrrolidone to the coating solution, a piezoelectric layer with improved surface morphology can be formed, and the generation of leakage current can be further suppressed. .

  The piezoelectric layer is formed by, for example, a sol-gel method or a MOD method. According to this, a piezoelectric layer with improved surface morphology can be easily formed.

  The polyvinyl pyrrolidone preferably has a viscosity average molecular weight of 40,000 or less. According to this, it is possible to reliably form a piezoelectric layer with improved surface morphology, and to reliably suppress the occurrence of leakage current.

According to another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head manufactured by the method for manufacturing a liquid ejecting head.
In this aspect, it is possible to realize a liquid jet head that suppresses the occurrence of leak current. Moreover, since the lead content can be suppressed, the burden on the environment can be reduced.

According to another aspect of the present invention, there is provided a step of forming a first electrode, and an organometallic compound that forms a composite oxide containing bismuth, iron, manganese, potassium, and titanium by firing above the first electrode. , A step of applying a coating solution containing polyvinylpyrrolidone, a step of baking the coating solution to form a piezoelectric layer made of a composite oxide having a perovskite structure, and a second layer above the piezoelectric layer. And a step of forming an electrode. A method of manufacturing a piezoelectric element comprising:
According to this aspect, it is possible to manufacture a piezoelectric element that suppresses the occurrence of leakage current. Moreover, since the lead content can be suppressed, the burden on the environment can be reduced.

FIG. 3 is an exploded perspective view illustrating a schematic configuration of the recording head according to the first embodiment. FIG. 3 is a plan view of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. The figure showing the X-ray-diffraction pattern of Examples 2-3 and the comparative example 1. FIG. 4 is a SEM observation photograph of the piezoelectric layer of Example 2. 4 is a SEM observation photograph of the piezoelectric layer of Comparative Example 1. 4 is a SEM observation photograph of the piezoelectric layer of Comparative Example 2. 10 is a SEM observation photograph of the piezoelectric layer of Comparative Example 3. The figure which shows the relationship between the applied voltage of Examples 2-3 and the comparative example 1, and current density. 1 is a diagram illustrating a schematic configuration of a recording apparatus according to an embodiment of the present invention.

(Embodiment 1)
FIG. 1 is an exploded perspective view showing a schematic configuration of an ink jet recording head which is an example of a liquid ejecting head according to Embodiment 1 of the invention, FIG. 2 is a plan view of FIG. 1, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. As shown in FIGS. 1 to 3, the flow path forming substrate 10 of the present embodiment is made of a silicon single crystal substrate, and an elastic film 50 made of silicon dioxide is formed on one surface thereof.

  A plurality of pressure generating chambers 12 are arranged in parallel in the width direction of the flow path forming substrate 10. In addition, a communication portion 13 is formed in a region outside the longitudinal direction of the pressure generation chamber 12 of the flow path forming substrate 10, and the communication portion 13 and each pressure generation chamber 12 are provided for each pressure generation chamber 12. Communication is made via a supply path 14 and a communication path 15. The communication part 13 communicates with a manifold part 31 of a protective substrate, which will be described later, and constitutes a part of a manifold that becomes a common ink chamber for each pressure generating chamber 12. The ink supply path 14 is formed with a narrower width than the pressure generation chamber 12, and maintains a constant flow path resistance of ink flowing into the pressure generation chamber 12 from the communication portion 13. In this embodiment, the ink supply path 14 is formed by narrowing the width of the flow path from one side. However, the ink supply path may be formed by narrowing the width of the flow path from both sides. Further, the ink supply path may be formed by narrowing from the thickness direction instead of narrowing the width of the flow path. In the present embodiment, the flow path forming substrate 10 is provided with a liquid flow path including the pressure generation chamber 12, the communication portion 13, the ink supply path 14, and the communication path 15.

  Further, on the opening surface side of the flow path forming substrate 10, a nozzle plate 20 having a nozzle opening 21 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14 is provided with an adhesive. Or a heat-welded film or the like. The nozzle plate 20 is made of, for example, glass ceramics, a silicon single crystal substrate, stainless steel, or the like.

  On the other hand, an elastic film 50 made of silicon dioxide is formed on the side opposite to the opening surface of the flow path forming substrate 10, and an insulator film 55 made of zirconium oxide is formed on the elastic film 50. ing. On the insulator film 55, an adhesion layer 56 made of titanium oxide or the like and for improving the adhesion between the insulator film 55 and the first electrode 60 is provided.

  Furthermore, on the adhesion layer 56, a first electrode 60, a piezoelectric layer 70 that is provided above the first electrode 60 and has a thickness of 2 μm or less, preferably 0.3 to 1 μm, and a piezoelectric layer The second electrode 80 provided above the 70 is laminated to form the piezoelectric element 300. Here, the term “above” includes not only directly above but also a state in which other members are interposed therebetween. Here, the piezoelectric element 300 refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In the present embodiment, the first electrode 60 is a common electrode of the piezoelectric element 300, and the second electrode 80 is an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. Here, the piezoelectric element 300 provided so as to be displaceable is referred to as an actuator device. In the above-described example, the elastic film 50, the insulator film 55, the adhesion layer 56, the first electrode 60, and the insulator film provided as necessary function as a diaphragm, but of course not limited thereto. For example, the elastic film 50 and the adhesion layer 56 may not be provided. Further, the piezoelectric element 300 itself may substantially serve as a diaphragm.

The piezoelectric layer 70 is formed by a method described in detail later, and is composed of a complex oxide having a perovskite structure having a general formula of ABO ₃ , and this complex oxide includes bismuth, iron, manganese, potassium, and It contains titanium. The composite oxide according to the present embodiment includes, for example, a perovskite structure including bismuth ferrate manganate (for example, Bi (Fe, Mn) O ₃ ) and potassium bismuth titanate (for example, (Bi, K) TiO ₃ ). It consists of complex oxide which has. Note that oxygen is 12-coordinated to the A site of the perovskite structure, and oxygen is 6-coordinated to the B site to form an octahedron. Bismuth (Bi) and potassium (K) are located at the A site, and iron (Fe), manganese (Mn), and titanium (Ti) are located at the B site. That is, the composite oxide having a perovskite structure containing bismuth ferrate manganate and potassium bismuth titanate can be said to be a solid solution in which bismuth ferrate manganate and potassium bismuth titanate are uniformly dissolved. In addition, as for the ratio of bismuth ferrate manganate (BFM) and bismuth potassium titanate (BKT), it is preferable that BFM / BKT (molar ratio) is 0.42 or more and 1.5 or less.

  As described above, when the complex oxide constituting the piezoelectric layer 70 is a complex oxide having a perovskite structure including bismuth, iron, manganese, potassium, and titanium, the insulating property is increased and the leakage current is suppressed. Can do. Furthermore, the piezoelectric layer 70 of the present embodiment will be described in detail later, but in the piezoelectric layer forming step, it is formed by adding polyvinyl pyrrolidone to the coating solution to form it without adding it. Thus, the surface morphology is improved. The surface morphology of the piezoelectric layer 70 is improved, in other words, the piezoelectric layer 70 is made of a dense film, so that the generation of leakage current can be further suppressed. Moreover, generation | occurrence | production of the crack at the time of the voltage application of a piezoelectric material layer can be suppressed, and it can be excellent in durability.

  Such a piezoelectric layer 70 can have a relative dielectric constant at 25 ° C. of 300 or more, further 500 or more. Therefore, the piezoelectric characteristics (distortion amount) are good.

  Each second electrode 80 that is an individual electrode of the piezoelectric element 300 is drawn from the vicinity of the end on the ink supply path 14 side and extended to the insulator film 55, for example, gold (Au). The lead electrode 90 which consists of etc. is connected.

  On the flow path forming substrate 10 on which such a piezoelectric element 300 is formed, that is, on the first electrode 60, the insulator film 55, and the lead electrode 90, a manifold portion 31 constituting at least a part of the manifold 100 is provided. The protective substrate 30 is bonded via an adhesive 35. In this embodiment, the manifold portion 31 penetrates the protective substrate 30 in the thickness direction and is formed across the width direction of the pressure generating chamber 12. As described above, the communication portion 13 of the flow path forming substrate 10. The manifold 100 is configured as a common ink chamber for the pressure generation chambers 12. Alternatively, the communication portion 13 of the flow path forming substrate 10 may be divided into a plurality of pressure generation chambers 12 and only the manifold portion 31 may be used as a manifold. Further, for example, only the pressure generation chamber 12 is provided in the flow path forming substrate 10, and the manifold 100 is attached to a member (for example, the elastic film 50, the insulator film 55, etc.) interposed between the flow path forming substrate 10 and the protective substrate 30. An ink supply path 14 that communicates with each pressure generating chamber 12 may be provided.

  A piezoelectric element holding portion 32 having a space that does not hinder the movement of the piezoelectric element 300 is provided in a region of the protective substrate 30 that faces the piezoelectric element 300. The piezoelectric element holding part 32 only needs to have a space that does not hinder the movement of the piezoelectric element 300, and the space may be sealed or unsealed.

  As such a protective substrate 30, it is preferable to use substantially the same material as the coefficient of thermal expansion of the flow path forming substrate 10, for example, glass, ceramic material, etc. In this embodiment, the same material as the flow path forming substrate 10 is used. The silicon single crystal substrate was used.

  The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The vicinity of the end portion of the lead electrode 90 drawn from each piezoelectric element 300 is provided so as to be exposed in the through hole 33.

  A drive circuit 120 for driving the piezoelectric elements 300 arranged in parallel is fixed on the protective substrate 30. For example, a circuit board or a semiconductor integrated circuit (IC) can be used as the drive circuit 120. The drive circuit 120 and the lead electrode 90 are electrically connected via a connection wiring 121 made of a conductive wire such as a bonding wire.

  In addition, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility, and one surface of the manifold portion 31 is sealed by the sealing film 41. The fixing plate 42 is formed of a relatively hard material. Since the area of the fixing plate 42 facing the manifold 100 is an opening 43 that is completely removed in the thickness direction, one surface of the manifold 100 is sealed only with a flexible sealing film 41. Has been.

  In such an ink jet recording head I of this embodiment, ink is taken in from an ink introduction port connected to an external ink supply means (not shown), and the interior from the manifold 100 to the nozzle opening 21 is filled with ink, and then driven. In accordance with a recording signal from the circuit 120, a voltage is applied between each of the first electrode 60 and the second electrode 80 corresponding to the pressure generating chamber 12, and the elastic film 50, the insulator film 55, the adhesion layer 56, the first electrode By bending and deforming the electrode 60 and the piezoelectric layer 70, the pressure in each pressure generating chamber 12 is increased and ink droplets are ejected from the nozzle openings 21.

  Next, an example of a method for manufacturing the ink jet recording head of the present embodiment will be described with reference to FIGS. 4 to 8 are cross-sectional views in the longitudinal direction of the pressure generating chamber.

First, as shown in FIG. 4A, a silicon dioxide film made of silicon dioxide (SiO ₂ ) or the like constituting the elastic film 50 is formed by thermal oxidation or the like on the surface of a flow path forming substrate wafer 110 that is a silicon wafer. To do. Next, as shown in FIG. 4B, an insulator film 55 made of zirconium oxide is formed on the elastic film 50.

  Next, as shown in FIG. 5A, the adhesion layer 56 made of titanium oxide is formed on the insulator film 55, and the first electrode 60 is formed on the adhesion layer 56. Specifically, after the adhesion layer 56 made of titanium oxide or the like is formed on the insulator film 55, the first electrode 60 made of platinum, iridium, iridium oxide, or a laminated structure thereof is formed on the adhesion layer 56. Form. The adhesion layer 56 and the first electrode 60 can be formed by, for example, a sputtering method or a vapor deposition method.

  Next, the piezoelectric layer 70 is stacked on the first electrode 60. The piezoelectric layer 70 can be formed using a chemical solution method such as a MOD (Metal-Organic Decomposition) method or a sol-gel method. Specifically, a coating liquid containing an organometallic compound capable of forming a composite oxide containing bismuth, iron, manganese, potassium, and titanium by firing, and polyvinylpyrrolidone is applied and dried, and further fired at a high temperature. Thus, the piezoelectric layer 70 made of a complex oxide can be formed.

  As a specific example of the procedure for forming the piezoelectric layer 70, first, as shown in FIG. 5B, a coating solution such as a sol or a MOD solution (precursor solution) is spin-coated on the first electrode 60. The piezoelectric precursor film 71 is formed by application using a method (application process). Specifically, the coating solution is obtained by dissolving and dispersing, in a solvent, an organometallic compound capable of forming a composite oxide containing bismuth, iron, manganese, potassium, and titanium by firing, and polyvinylpyrrolidone. . Here, “an organometallic compound capable of forming a composite oxide containing bismuth, iron, manganese, potassium, and titanium by firing” includes one or more metals of bismuth, iron, manganese, potassium, and titanium. Refers to a mixture of organometallic compounds. The coating solution is a mixture of such organometallic compounds so that each metal of bismuth (Bi), iron (Fe), manganese (Mn), potassium (K), titanium (Ti) has a desired molar ratio, The mixture is dissolved or dispersed using an organic solvent such as alcohol, and polyvinylpyrrolidone is added thereto.

  Thus, by blending polyvinyl pyrrolidone in the coating solution, as shown in Examples described later, the piezoelectric layer 70 having improved surface morphology compared to a piezoelectric layer formed without blending polyvinyl pyrrolidone. Can be formed. Thereby, leakage current can be suppressed. Moreover, generation | occurrence | production of the crack at the time of the voltage application of a piezoelectric material layer can be suppressed, and it can be excellent in durability.

  As an organometallic compound containing Bi, Fe, Mn, K, and Ti, for example, a metal alkoxide, an organic acid salt, a β-diketone complex, or the like can be used. Examples of the organometallic compound containing Bi include bismuth 2-ethylhexanoate. Examples of the organometallic compound containing Fe include iron 2-ethylhexanoate. Examples of the organometallic compound containing Mn include manganese 2-ethylhexanoate. Examples of the organometallic compound containing K include potassium 2-ethylhexanoate, potassium acetate, potassium acetylacetonate, and the like. Examples of the organometallic compound containing Ti include titanium isopropoxide, titanium 2-ethylhexanoate, titanium (di-i-propoxide) bis (acetylacetonate), and the like. Of course, an organometallic compound containing two or more of Bi, Fe, Mn, K, and Ti may be used.

Polyvinyl pyrrolidone is not particularly limited, but preferably has a viscosity average molecular weight of 40000 or less. Thereby, the surface morphology of the piezoelectric layer 70 to be formed can be improved more reliably. The amount of polyvinylpyrrolidone is not particularly limited, for example, the total amount 1mol of the metal of the organometallic compound in the coating solution, a monomolecular weight terms (specifically, [C 6 _{H 5 ON]} equivalent) The amount is preferably 0.2 mol or more, more preferably 0.25 mol or more, and particularly preferably 0.5 mol or more.

Next, the piezoelectric precursor film 71 is heated to a predetermined temperature (for example, 130 to 180 ° C.) and dried for a predetermined time (for example, 2 to 4 minutes) (drying process). Next, the dried piezoelectric precursor film 71 is degreased by heating to a predetermined temperature (for example, 350 to 450 ° C.) and holding for a certain time (for example, 4 to 6 minutes) (degreasing process). The degreasing referred to here is to release the organic component contained in the piezoelectric precursor film 71 as, for example, NO ₂ , CO ₂ , H ₂ O or the like. The atmosphere in the drying process or the degreasing process is not limited, and it may be in the air or in an inert gas.

  Next, as shown in FIG. 5C, the piezoelectric precursor film 71 is crystallized by heating to a predetermined temperature, for example, about 600 to 800 ° C., and holding it for a certain time (for example, 2 to 6 minutes). Then, the piezoelectric film 72 is formed (firing process). Also in this firing step, the atmosphere is not limited, and may be in the air or in an inert gas.

  Examples of the heating apparatus used in the drying process, the degreasing process, and the baking process include an RTA (Rapid Thermal Annealing) apparatus and a hot plate that are heated by irradiation with an infrared lamp.

  Next, as shown in FIG. 6A, for example, the first electrode 60 and the first layer of the piezoelectric film 72 are inclined on the piezoelectric film 72 using a resist (not shown) having a predetermined shape as a mask. Pattern simultaneously.

  Next, after peeling off the resist, the above-described coating process, drying process, degreasing process, coating process, drying process, degreasing process, and baking process are repeated a plurality of times according to the desired film thickness, etc. By forming the piezoelectric layer 70 made of the material, a piezoelectric layer 70 having a predetermined thickness composed of a plurality of layers of piezoelectric films 72 is formed as shown in FIG. 6B. For example, when the film thickness of the coating solution per one time is about 0.1 μm, for example, the entire film thickness of the piezoelectric layer 70 composed of the ten piezoelectric films 72 is about 1.1 μm. In the present embodiment, the piezoelectric film 72 is provided by being laminated, but only one layer may be provided. The piezoelectric layer 70 is made of a composite oxide having a perovskite structure containing bismuth, iron, manganese, potassium, and titanium, with the polyvinyl pyrrolidone contained in the coating solution disappearing, and has a good surface morphology. It becomes.

  After the piezoelectric layer 70 is formed in this way, as shown in FIG. 7A, a second electrode 80 made of platinum or the like is formed on the piezoelectric layer 70 by sputtering or the like, and each pressure generating chamber 12 is formed. Then, the piezoelectric layer 70 and the second electrode 80 are simultaneously patterned in a region opposite to each other to form the piezoelectric element 300 including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. The patterning of the piezoelectric layer 70 and the second electrode 80 can be performed collectively by dry etching via a resist (not shown) formed in a predetermined shape. Thereafter, post-annealing may be performed in a temperature range of 600 ° C. to 800 ° C. as necessary. Thereby, a good interface between the piezoelectric layer 70 and the first electrode 60 or the second electrode 80 can be formed, and the crystallinity of the piezoelectric layer 70 can be improved.

  Next, as shown in FIG. 7B, a lead electrode 90 made of, for example, gold (Au) or the like is formed over the entire surface of the flow path forming substrate wafer 110, and then a mask pattern made of, for example, a resist or the like. Patterning is performed for each piezoelectric element 300 via (not shown).

  Next, as shown in FIG. 7C, a protective substrate wafer 130 that is a silicon wafer and serves as a plurality of protective substrates 30 is placed on the piezoelectric element 300 side of the flow path forming substrate wafer 110 via an adhesive 35. After the bonding, the flow path forming substrate wafer 110 is thinned to a predetermined thickness.

  Next, as shown in FIG. 8A, a mask film 52 is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape.

  Then, as shown in FIG. 8B, the flow path forming substrate wafer 110 is anisotropically etched (wet etching) using an alkaline solution such as KOH through the mask film 52 to form the piezoelectric element 300. Corresponding pressure generating chambers 12, communication portions 13, ink supply passages 14, communication passages 15 and the like are formed.

  Thereafter, unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 110 and the protective substrate wafer 130 are removed by cutting, for example, by dicing. Then, after removing the mask film 52 on the surface opposite to the protective substrate wafer 130 of the flow path forming substrate wafer 110, the nozzle plate 20 having the nozzle openings 21 formed therein is bonded, and the protective substrate wafer 130 is also formed. The compliance substrate 40 is bonded to the substrate, and the flow path forming substrate wafer 110 or the like is divided into a single chip size flow path forming substrate 10 or the like as shown in FIG. To do.

In the present embodiment, a liquid jet head that has high insulating properties and suppresses generation of leakage current by forming a piezoelectric layer made of a composite oxide having a perovskite structure including bismuth, iron, manganese, potassium, and titanium. Can be manufactured. Moreover, since the lead content can be suppressed, the burden on the environment can be reduced. Furthermore, in the piezoelectric layer forming step, by adding polyvinylpyrrolidone to the coating solution, a piezoelectric layer with improved surface morphology can be formed, and the generation of leakage current can be further suppressed. . For example, the piezoelectric layer 70 has a leakage current of 5.0 × 10 ⁻¹ A / cm ² or less, preferably 2.5 × 10 ⁻⁴ A / cm ² or less when a voltage of 25 V is applied. Can do. Here, 25V is a typical driving voltage applied to the piezoelectric element of the ink jet recording head. Moreover, generation | occurrence | production of the crack at the time of the voltage application of a piezoelectric material layer can be suppressed, and it can be excellent in durability.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited to a following example.

Example 1
An elastic film made of silicon dioxide having a thickness of 1070 nm was formed on the surface of the silicon substrate oriented in (100) by thermal oxidation. Next, a titanium film with a thickness of 40 nm was formed on the silicon dioxide film by RF sputtering, and a titanium oxide film was formed by thermal oxidation. Next, a platinum film having a film thickness of 130 nm was formed on the titanium oxide film by DC sputtering to form a first electrode oriented in (111).

A piezoelectric layer was formed on the first electrode by spin coating. The method is as follows. First, Bi, K, Fe, Mn, Ti xylene, octane and butanol solutions are mixed at a predetermined ratio, and polyvinylpyrrolidone (K15; manufactured by Tokyo Chemical Industry Co., Ltd.) having a viscosity average molecular weight of 10,000 is added thereto. Then, a precursor solution was prepared. Specifically, a BF-BKT raw material solution adjusted to Bi: Fe: K: Ti = 4: 3: 1: 2 is prepared, and K is excessive by 4 mol% with respect to the BF-BKT raw material solution. Was added as follows. By adding Bi and Mn raw material solutions to the solution to which K was added, the amount of BiMnO ₃ added was adjusted to 3 mol%. By adding polyvinylpyrrolidone to this, a precursor solution in which polyvinylpyrrolidone was 0.2 mol in terms of single molecular weight was formed with respect to 1 mol of the total amount of metal of the organometallic compound.

  The precursor solution was dropped onto the substrate on which the first electrode was formed, and the substrate was rotated at 3000 rpm to form a piezoelectric precursor film (application process). Next, drying and degreasing were performed at 150 ° C. for 2 minutes and at 400 ° C. for 4 minutes (drying and degreasing process). After repeating this application | coating process, drying, and a degreasing process 3 times, it baked at 750 degreeC for 5 minute (s) by Rapid Thermal Annealing (RTA) (baking process). This coating process, drying and degreasing process was repeated 3 times, and then the process of performing a baking process in which baking was performed in a lump was repeated 3 times, and a total of 900 nm thick piezoelectric layers were formed by a total of 9 applications.

Thereafter, a platinum film having a film thickness of 100 nm is formed as a second electrode by a DC sputtering method on the piezoelectric layer, followed by firing at 750 ° C. for 5 minutes using RTA, whereby Bi (Fe _0.97 , Mn _0.03 ) O ₃ and (Bi _0.5 , K _0.5 ) TiO ₃ in a composite oxide having a perovskite structure, which is bismuth iron manganate / potassium bismuth titanate, ie Bi (Fe _0. A piezoelectric element having a piezoelectric layer of ₉₇ , Mn _0.03 ) O ₃ / (Bi _0.5 , K _0.5 ) TiO ₃ in a molar ratio of 1.50 was formed. In addition, as above-mentioned, the molar ratio of BF-BKT and BM is BF-BKT: BM = 100: 3.

(Example 2)
Example 2 is the same material and production method as Example 1 described above except that the precursor solution is 0.25 mol in terms of monomolecular weight of polyvinylpyrrolidone with respect to 1 mol of the total amount of metal of the organometallic compound. The piezoelectric element was formed.

(Example 3)
Example 3 is the same material and production method as Example 1 described above, except that the precursor solution is 0.50 mol in terms of monomolecular weight of polyvinylpyrrolidone with respect to 1 mol of the total amount of metal of the organometallic compound. The piezoelectric element was formed.

(Comparative Example 1)
A piezoelectric element of Comparative Example 1 was formed by the same material and manufacturing method as in Example 1 except that polyvinylpyrrolidone was not added to the precursor solution.

(Comparative Example 2)
Instead of polyvinylpyrrolidone, polyalkylene glycol (PAG) (Emulgen 709: manufactured by Kao Corporation) is used so that polyalkylene glycol becomes 0.25 mol in terms of single molecular weight with respect to 1 mol of the total amount of metal of the organometallic compound. Except for the above, the piezoelectric element of Comparative Example 2 was formed using the same material and manufacturing method as in Example 1 described above.

(Comparative Example 3)
Polyethylene glycol (PEG) (# 400: manufactured by Kanto Chemical Co., Inc.) was used instead of polyvinyl pyrrolidone, and polyethylene glycol was adjusted to 0.25 mol in terms of single molecular weight with respect to 1 mol of the total amount of metal of the organometallic compound. Except for the above, the piezoelectric element of Comparative Example 3 was formed using the same material and manufacturing method as in Example 1 described above.

(Test Example 1)
For the piezoelectric elements of Examples 2 to 3 and Comparative Example 1, a piezoelectric layer was used at room temperature by X-ray diffraction wide angle method (XRD) using “D8 DISCOVER” manufactured by Bruker AKS and using CuKα rays as an X-ray source. The X-ray diffraction pattern of was obtained. The result is shown in FIG.

  As shown in FIG. 9, the diffraction intensity peaks (2θ) due to the perovskite structure, specifically 23 °, 32 ° and 47 °, were detected. The other peaks are attributed to platinum (Pt) as an electrode, silicon (Si) as a substrate, and the like, and almost no diffraction intensity peaks derived from other crystal structures were detected. From this, it was confirmed that each of the piezoelectric layers of Examples 2 to 3 and Comparative Example 1 was a perovskite structure single layer.

In Examples 1 and 2 described above, a piezoelectric layer in which Bi (Fe _0.97 , Mn _0.03 ) O ₃ / (Bi _0.5 , K _0.5 ) TiO ₃ is 1.50 in molar ratio. In the same manner, a piezoelectric layer having an improved surface morphology can be formed even if the piezoelectric layer has a molar ratio other than this, and the generation of leakage current can be suppressed.

(Test Example 2)
In Example 2 and Comparative Examples 1 to 3, before forming the second electrode, the surface of the piezoelectric layer was observed with a scanning electron microscope (SEM) at a magnification of 5000 times. The results are shown in FIGS.

  The surface of the piezoelectric layer of Example 2 formed by adding polyvinylpyrrolidone (see FIG. 10) has a reduced pore and surface morphology compared to the surface of the piezoelectric layer of Comparative Example 1 (see FIG. 11). As a result, it was confirmed that a dense film was formed.

  Further, the surface of the piezoelectric layer of Comparative Example 2 and Comparative Example 3 to which a polymer material other than polyvinylpyrrolidone was added (FIGS. 12 and 13 respectively) has a larger pore than that of Comparative Example 1, and the surface morphology is rough. It was confirmed that.

  From the above, it can be seen that the surface morphology is lowered when a polymer material other than polyvinylpyrrolidone is added to the coating liquid when forming the piezoelectric layer, but the surface morphology is improved by adding polyvinylpyrrolidone. It was.

(Test Example 3)
About each piezoelectric element of Examples 2-3 and the comparative example 1, the relationship between an applied voltage and a current density was measured at room temperature using "4140B" by a Hewlett-Packard company. The results are shown in FIG.

  As shown in FIG. 14, Examples 2 to 3 formed using a coating solution to which polyvinyl pyrrolidone was added had smaller leakage current than Comparative Example 1 and exhibited better insulation. From this, it was found that the leakage current was suppressed in the piezoelectric layer formed using the coating liquid to which polyvinylpyrrolidone was added.

  Further, Example 3 in which polyvinylpyrrolidone is 0.50 mol in terms of single molecular weight with respect to 1 mol of the total amount of metal of the organometallic compound has a smaller leakage current than Example 2, and has good insulation. Indicated.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above. For example, in the above-described embodiment, the silicon single crystal substrate is exemplified as the flow path forming substrate 10, but the present invention is not particularly limited thereto, and for example, a material such as an SOI substrate or glass may be used.

  In addition, the ink jet recording head of these embodiments constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 15 is a schematic view showing an example of the ink jet recording apparatus.

  In the ink jet recording apparatus II shown in FIG. 15, the recording head units 1A and 1B having the ink jet recording head I are detachably provided with cartridges 2A and 2B constituting the ink supply means, and the recording head units 1A and 1B. Is mounted on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.

  The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S that is a recording medium such as paper fed by a paper feed roller (not shown) is wound around the platen 8. It is designed to be transported.

  In the above-described embodiment, the ink jet recording head has been described as an example of the liquid ejecting head. However, the present invention is widely applied to all liquid ejecting heads, and the liquid ejecting ejects a liquid other than ink. Of course, it can also be applied to the head. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

  In addition, the present invention is not limited to a method of manufacturing a piezoelectric element mounted on a liquid jet head typified by an ink jet recording head, but includes an ultrasonic device such as an ultrasonic transmitter, an ultrasonic motor, a pressure sensor, and a pyroelectric sensor. The present invention can also be applied to a method for manufacturing a piezoelectric element mounted on another device such as the above. The present invention can also be applied to a method for manufacturing a ferroelectric element such as a ferroelectric memory.

  I ink jet recording head (liquid ejecting head), II ink jet recording apparatus (liquid ejecting apparatus), 10 flow path forming substrate, 12 pressure generating chamber, 13 communicating portion, 14 ink supply path, 20 nozzle plate, 21 nozzle opening, 30 protective substrate, 31 manifold portion, 32 piezoelectric element holding portion, 40 compliance substrate, 50 elastic film, 55 insulator film, 56 adhesion layer, 60 first electrode, 70 piezoelectric layer, 80 second electrode, 90 lead electrode, 100 manifold, 120 drive circuit, 300 piezoelectric element

Claims (5)

A method of manufacturing a liquid ejecting head comprising a pressure generating chamber communicating with a nozzle opening for ejecting liquid, and a piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode,
Forming a first electrode;
Applying a coating solution containing polyvinylpyrrolidone and an organometallic compound that forms a composite oxide containing bismuth, iron, manganese, potassium, and titanium by firing above the first electrode;
Baking the coating solution to form a piezoelectric layer made of a composite oxide having a perovskite structure;
And a step of forming the second electrode above the piezoelectric layer.   The method of manufacturing a liquid jet head according to claim 1, wherein the piezoelectric layer is formed by a sol-gel method or a MOD method.   The method of manufacturing a liquid jet head according to claim 1, wherein the polyvinyl pyrrolidone has a viscosity average molecular weight of 40,000 or less.   A liquid ejecting apparatus comprising the liquid ejecting head manufactured by the method of manufacturing a liquid ejecting head according to claim 1. Forming a first electrode;
Applying a coating solution containing polyvinylpyrrolidone and an organometallic compound that forms a composite oxide containing bismuth, iron, manganese, potassium, and titanium by firing above the first electrode;
Baking the coating solution to form a piezoelectric layer made of a composite oxide having a perovskite structure;
And a step of forming the second electrode above the piezoelectric layer.