JP2008041921A - Piezoelectric thin film element and its manufacturing method, as well as ink jet head and ink jet-type recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric thin film element capable of easily raising a reliability and a durability, and to provide a method of manufacturing the piezoelectric thin film element. <P>SOLUTION: A piezoelectric thin film element 20 is equipped with: a substrate 11; a first electrode layer 13 provided on the substrate 11, a piezoelectric substance layer provided on the first electrode layer 13, and a second electrode layer 19 provided on the piezoelectric substance layer. For constituting the piezoelectric thin film element; the thin film layer has a primary piezoelectric substance layer 14 consisting of oxide of a perovskite version crystal structure which uses lead as a constituent element, and a secondary piezoelectric substance layer 18 consisting of electric insulation oxide which is provided on the primary piezoelectric substance layer 14 and buries a hole 17 in the primary piezoelectric substance layer 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric thin film element having an electromechanical conversion function and a manufacturing method thereof, an ink jet head using the piezoelectric thin film element, and an ink jet recording apparatus including the ink jet head as a printing unit.

  A piezoelectric thin film element used in a piezoelectric thin film actuator or the like is an element that generates electrostriction when an electric field is applied, and generally has a structure in which a piezoelectric layer is sandwiched between two electrodes in the thickness direction. A laminate is provided. The piezoelectric layer in this piezoelectric thin film element is formed of a piezoelectric material that converts mechanical energy into electrical energy or converts electrical energy into mechanical energy.

Typical examples of the piezoelectric material include lead zirconate titanate (Pb (Zr, Ti) O ₃ (hereinafter abbreviated as “PZT”), which is an oxide having a perovskite crystal structure, and magnesium, Among the PZT, tetragonal PZT has a large piezoelectricity in the (001) axis direction (C axis direction) and rhombohedral PZT has a large (111) axis direction. However, many piezoelectric materials are composed of polycrystals, which are aggregates of crystal grains, and the crystal axes of individual crystal grains are oriented in different directions. Spontaneous polarization is also randomly arranged.

  In order to obtain a large electromechanical conversion capability, the piezoelectric layer in the piezoelectric thin film element is manufactured so that the vector is parallel to the electric field when the sum of the vectors of the spontaneous polarization in each crystal particle is taken. Thereby, for example, in a piezoelectric thin film actuator having a structure in which a vibration plate is provided on the above laminate, when a voltage is applied between both electrodes, a mechanical displacement proportional to the magnitude of the voltage can be obtained.

  17 and 18 are cross-sectional views schematically showing the basic structure of an example of the piezoelectric thin film element. 17 has a structure in which an adhesion layer 42, a lower electrode layer 43, a piezoelectric layer 44, and an upper electrode layer 47 are laminated on a substrate 41 in this order. Each of the adhesion layer 42, the lower electrode layer 43, and the upper electrode 47 is formed by a sputtering method or the like, and the piezoelectric layer is formed by a sputtering method, a CVD method, a sol-gel method, or the like.

When the foreign substance 46 is mixed in forming the piezoelectric layer 44, a by-product layer having a composition different from that of the piezoelectric layer 44 is easily formed at the interface between the foreign substance 46 and the piezoelectric layer 44. In particular, when a piezoelectric layer having a perovskite crystal structure containing lead (Pb) is formed, Pb is excessive by about 5 to 15 mol% over the stoichiometric composition in order to improve crystallinity and enhance piezoelectric performance. Therefore, the by-product layer 45 made of lead oxide such as lead monoxide (PbO) or lead dioxide (PbO ₂ ) is easily formed at the interface between the foreign matter 46 and the piezoelectric layer 44 described above.

On the other hand, the piezoelectric thin film element 58 shown in FIG. 18 also has a structure in which an adhesion layer 52, a lower electrode layer 53, a piezoelectric layer 54, and an upper electrode layer 57 are laminated in this order on a substrate 51. 17 is different from the piezoelectric thin film element 48 shown in FIG. 17 in that the foreign matter 46 shown in FIG. 17 is lost between the formation of the piezoelectric layer 54 and the formation of the upper electrode layer 57. Hole) 56 is present. Foreign matters are easily lost because of poor adhesion to the piezoelectric layer 54. A by-product layer 55 made of lead oxide such as PbO or PbO ₂ is present at the interface between the piezoelectric layer 54 and the upper electrode 57 in the foreign-matter missing portion (hole) 56.

  For example, in an inkjet head using a piezoelectric thin film actuator, it is necessary to apply a voltage of several tens of volts to a piezoelectric layer having a thickness of several μm. Therefore, the piezoelectric layer is required to have a withstand voltage of several hundreds kV / cm or more. Is done. In such a piezoelectric thin film element that requires a high withstand voltage, the foreign substance 46 is mixed into the piezoelectric layer 44 as in the piezoelectric thin film element 48 shown in FIG. 17, and the by-product layer 45 is formed around the foreign substance 46. When formed, a leak current is likely to be generated through the foreign matter 46 and the by-product layer 45 when a voltage is applied, and reliability is lowered. Further, when the foreign material missing portion (hole) 56 is generated in the piezoelectric layer 54 as in the piezoelectric thin film element 58 shown in FIG. 18, the thickness of the piezoelectric film layer 54 below the foreign matter missing portion (hole) 56. Therefore, when a voltage is applied, electric field concentration occurs below the foreign matter missing portion (hole) 56, and dielectric breakdown is likely to occur, resulting in a decrease in reliability.

In order to improve the reliability of the piezoelectric thin film element, for example, in the piezoelectric element of the invention described in (Patent Document 1), the thin portion generated in the piezoelectric layer (piezoelectric film) Is filled with polyimide resin. In addition, in the piezoelectric element of the invention described in (Patent Document 2), the crystal grain boundary exposed region of the piezoelectric layer (piezoelectric film) has the same elemental configuration as the piezoelectric film but a different crystal. A low dielectric constant material having a property (amorphous or pyrochlore structure) is formed.
JP 2000-351212 A Japanese Patent No. 3666163

  In each piezoelectric element described in (Patent Documents 1 and 2), since an electrically insulating material having no piezoelectric performance is formed in the piezoelectric layer, the piezoelectric layer is not applied when a voltage is applied to the piezoelectric layer. Although it is deformed, the above-mentioned electrically insulating material is not deformed, and a large internal stress is generated in the boundary region between the piezoelectric layer and the above-mentioned electrically insulating material layer. For this reason, if a piezoelectric element is repeatedly deformed by applying a voltage periodically or aperiodically over a long period of time, micro-cracks or the like are likely to occur in the piezoelectric element, and leakage current is generated when micro-cracks occur. As a result, durability is reduced.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a piezoelectric thin film element that easily improves reliability and durability.

  In order to achieve the above object, in the present invention, a substrate, a first electrode layer provided on the substrate, a piezoelectric layer provided on the first electrode layer, and a piezoelectric layer are provided. In forming a piezoelectric thin film element including the second electrode layer, the piezoelectric layer has two layers, that is, a first piezoelectric layer made of an oxide having a perovskite crystal structure having lead as a constituent element; And a second piezoelectric layer made of an electrically insulating oxide that is provided on the first piezoelectric layer and fills pores in the first piezoelectric layer.

  In the piezoelectric thin film element of the present invention, since the holes generated in the first piezoelectric layer are filled with the second piezoelectric layer, the formation of leak paths and the occurrence of electric field concentration are suppressed when a voltage is applied. The Also, when a voltage is applied, both the first piezoelectric layer and the second piezoelectric layer are deformed, so that a large internal stress is unlikely to occur, and therefore microcracks are unlikely to occur. For these reasons, the piezoelectric thin film element of the present invention can easily improve its reliability and durability. By producing a piezoelectric thin film actuator using the piezoelectric thin film element of the present invention, an ink jet head and an ink jet recording apparatus that can easily improve reliability and durability can be obtained.

  A piezoelectric thin film element according to a first aspect of the present invention includes a substrate, a first electrode layer provided on the substrate, a piezoelectric layer provided on the first electrode layer, and a first electrode provided on the piezoelectric layer. A piezoelectric thin film element comprising: a first piezoelectric layer made of an oxide having a perovskite crystal structure having lead as a constituent element; and a first piezoelectric layer on the first piezoelectric layer. And a second piezoelectric layer made of an electrically insulating oxide that fills voids in the first piezoelectric layer.

  In this piezoelectric thin film element, since the holes generated in the first piezoelectric layer are filled with the second piezoelectric layer, the formation of a leak path and the occurrence of electric field concentration are suppressed when a voltage is applied. Also, when a voltage is applied, both the first piezoelectric layer and the second piezoelectric layer are deformed, so that a large internal stress is unlikely to occur, and therefore microcracks are unlikely to occur. For these reasons, the piezoelectric thin film element can easily improve its reliability and durability. By producing a piezoelectric thin film actuator using this piezoelectric thin film element, an ink jet head and an ink jet recording apparatus that can easily improve reliability and durability can be obtained.

  The piezoelectric thin film element of the second invention is characterized in that there is no by-product layer around the above-mentioned holes. In this piezoelectric thin film element, there is no by-product layer around the above holes, so that it is difficult to form a leak path when a voltage is applied. As a result, the piezoelectric thin film element can easily improve its reliability and durability.

  The piezoelectric thin film element according to a third aspect is characterized in that the first piezoelectric layer is a polycrystalline body preferentially oriented in the (111) plane or the (001) plane. In this piezoelectric thin film element, since the first piezoelectric layer is formed of the above-described polycrystalline body, excellent piezoelectric characteristics can be realized.

  The piezoelectric thin film element according to a fourth aspect is characterized in that the maximum thickness of the first piezoelectric layer is not less than 1 μm and not more than 10 μm. In this piezoelectric thin film element, since the maximum thickness of the first piezoelectric layer is selected as described above, the technical effect of the present invention can be easily obtained.

  According to a fifth aspect of the present invention, there is provided a piezoelectric thin film element manufacturing method comprising: a substrate; a first electrode layer provided on the substrate; a piezoelectric layer provided on the first electrode layer; and a piezoelectric layer provided on the piezoelectric layer. A method of manufacturing a piezoelectric thin film element including a second electrode layer, wherein the first piezoelectric layer made of an oxide having a perovskite crystal structure having lead as a constituent element is interposed through the first electrode layer. The substrate formed on one side is washed to remove foreign matters mixed in the first piezoelectric layer in the process of forming the first piezoelectric layer and by-product layers formed on the first piezoelectric layer. Foreign matter removing step to be removed, and second piezoelectric layer made of an electrically insulating oxide so as to fill voids in the first piezoelectric layer on the first piezoelectric layer that has undergone the foreign matter removing step And a second piezoelectric layer forming step for forming the substrate.

  In this manufacturing method, the foreign matter mixed in the first piezoelectric layer during the formation of the first piezoelectric layer and the by-product formed in the first piezoelectric layer are removed, and then the second piezoelectric layer is removed. Since the body layer is formed, the obtained piezoelectric thin film element suppresses the formation of a leak path and the occurrence of electric field concentration when a voltage is applied. Also, when a voltage is applied, both the first piezoelectric layer and the second piezoelectric layer are deformed, so that a large internal stress is unlikely to occur, and therefore microcracks are unlikely to occur. For these reasons, according to this manufacturing method, it is easy to obtain a piezoelectric thin film element having high reliability and durability.

  An ink jet head according to a sixth aspect of the present invention is a piezoelectric thin film element in which a piezoelectric layer is formed on a first electrode layer, and a second electrode layer is formed on the piezoelectric layer. A diaphragm layer provided on the electrode layer side surface of either the electrode layer or the second electrode layer, and a pressure chamber that is bonded to the surface of the diaphragm layer opposite to the piezoelectric thin film element side and accommodates ink An ink jet head that discharges ink in the pressure chamber by displacing the diaphragm layer in the layer thickness direction by the piezoelectric effect of the piezoelectric thin film element, wherein the piezoelectric layer includes lead as a constituent element A first piezoelectric layer made of an oxide having a perovskite crystal structure, and a first piezoelectric layer made of an electrically insulating oxide that is provided on the first piezoelectric layer and fills voids in the first piezoelectric layer. And two piezoelectric layers.

  The piezoelectric thin film element in this ink jet head is equivalent to the piezoelectric thin film element of the first invention described above with the substrate removed, and the piezoelectric thin film element is also reliable as in the piezoelectric thin film element of the first invention described above. It is easy to improve performance and durability. Therefore, also in this inkjet head, it is easy to improve the reliability and durability performance.

  An ink jet recording apparatus according to a seventh aspect of the present invention includes an ink jet head and relative moving means for moving the ink jet head relative to the recording medium, and the ink jet head is moved relative to the recording medium by the relative moving means. In some cases, an ink jet recording apparatus that performs recording by discharging ink from the ink jet head onto a recording medium, wherein the ink jet head is the ink jet head of the sixth invention.

  In this ink jet recording apparatus, since the ink jet head is the ink jet head according to the sixth aspect of the invention, the reliability and durability can be easily improved.

  Hereinafter, embodiments of the piezoelectric thin film element, the method for manufacturing the piezoelectric thin film element, the ink jet head, and the ink jet recording apparatus of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing an example of the piezoelectric thin film element of the present invention. In the figure, 11 is a substrate, 12 is an adhesion layer, 13 is a first electrode layer, 14 is a first piezoelectric layer, 17 is a hole, 18 is a second piezoelectric layer, and 19 is a second electrode layer. , 20 are piezoelectric thin film elements. The adhesion layer 12, the first electrode layer 13, the first piezoelectric layer 14, the second piezoelectric layer 18, and the second electrode layer 19 are laminated on the substrate 11 in this order, and the piezoelectric thin film element 20. Is configured.

  As the substrate 11, for example, a silicon wafer, a magnesium oxide (MgO) single crystal substrate, a glass substrate, a metal substrate, a ceramic substrate, or the like can be used.

  The adhesion layer 12 is an optional component, and is disposed as necessary in order to improve the adhesion between the substrate 11 and the first electrode layer 13. The adhesion layer 12 is formed of a metal such as titanium (Ti), tantalum (Ta), iron (Fe), cobalt (Co), nickel (Ni), and chromium (Cr), or a compound of the metal. The thickness is appropriately selected within a range of approximately 0.005 to 1 μm. For example, when a silicon wafer is used as the substrate and the first electrode layer is formed of platinum (Pt), an adhesion layer 12 made of titanium (Ti) is provided, so that the substrate 11 and the first electrode layer 12 are separated. Adhesion can be improved.

  The first electrode layer 13 is for applying a voltage to the piezoelectric layer (the first piezoelectric layer 14 and the second piezoelectric layer 18) together with the second electrode layer 19, and has a desired conductivity. Formed by material. When the piezoelectric thin film element 20 is used for a piezoelectric thin film actuator of an ink jet head, the substrate 11 is finally removed, so that the first electrode layer 13 is made of platinum so as not to be damaged when the substrate 11 is removed. It is preferably formed of a corrosion-resistant metal such as (Pt), iridium (Ir), palladium (Pd), or ruthenium (Ru). The thickness of the 1st electrode layer 13 is suitably selected according to the material.

  The first piezoelectric layer 14 includes an oxide having a perovskite crystal structure containing lead as an element, for example, PZT having a rhombohedral or tetragonal perovskite crystal structure, lanthanum (La), One containing an additive such as strontium (Sr), niobium (Nb), aluminum (Al), lead magnesium niobate (PMN), lead zinc niobate (PZN), lead titanate doped with lanthanum ( PLT) or the like.

  For example, when the first piezoelectric layer 14 is formed by PZT, the atomic ratio Zr / Ti between zinc (Zn) atoms and titanium (Ti) atoms in the first piezoelectric layer 14 is 30/70 to 70. By setting it within the range of about / 30, the crystal structure can be a rhombohedral or tetragonal perovskite crystal structure. In PZT, when Zr / Ti is approximately 53/47, a morphotropic phase boundary (boundary between a tetragonal crystal and a rhombohedral crystal) is obtained.

  The above-mentioned oxides are not limited to PZT and are usually polycrystalline. In the case where the first piezoelectric layer 14 is formed of the above oxide polycrystal, if the crystal grains are evenly oriented, the polarization axis is easily oriented in the voltage application direction, so that the piezoelectric performance is improved. Piezoelectric performance is suppressed by the influence of internal stress generated when forming one piezoelectric layer 14 and stress due to the difference in linear expansion coefficient from the substrate generated for forming in a high temperature environment.

  Therefore, in practice, the first piezoelectric layer 14 is preferably formed of a polycrystalline body preferentially oriented in the (111) plane or the (001) plane. At this time, the orientation ratio α (111) to the (111) plane or the orientation ratio α (001) to the (001) plane is preferably 70% or more. This is more preferable because the influence of each stress can be ignored. The orientation rate α (111) is defined by α (111) = I (111) / ΣI (hkl), and the orientation rate α (001) is defined by α (001) = I (001) / ΣI (hkl). Is done. ΣI (hkl) in these formulas represents the total sum of diffraction peak intensities from each crystal plane when 2θ is 10 to 70 ° in X-ray diffraction using Cu-Kα rays. The orientation rate in the polycrystalline body is controlled by appropriately selecting the polycrystalline film forming method, film forming conditions, properties of the underlayer, and the like.

  The thickness of the first piezoelectric layer 14 is appropriately selected according to the composition, the use of the piezoelectric thin film element 20, and the like. When the piezoelectric thin film element 20 is used as a piezoelectric thin film actuator of an inkjet head, it is preferable to select the maximum thickness of the first piezoelectric layer 14 within a range of approximately 1 to 10 μm. If the maximum thickness of the first piezoelectric layer 14 is outside this range, it is difficult to improve the reliability and durability of the piezoelectric thin film element 20 even if the second piezoelectric layer 18 is provided.

  The foreign matter mixed in the first piezoelectric layer 14 during the formation process is removed before the second piezoelectric layer 18 is formed. As the foreign matter is removed, holes 17 are formed in the first piezoelectric layer 14. It is also preferable to remove by-products generated in the process of forming the first piezoelectric layer 14 before forming the second piezoelectric layer 18. A method for removing foreign substances and by-products will be described in Embodiment 3 to be described later.

The second piezoelectric layer 18 fills the holes 17 generated in the first piezoelectric layer 14 in accordance with the removal of the foreign matter from the first piezoelectric layer 14, and is an electrically insulating oxide. The piezoelectric material is made of. For example, the oxide described in the description of the first piezoelectric layer 14 can be used as the piezoelectric material, but the composition thereof is different from that of the first piezoelectric layer 14. The relative dielectric constant of the second piezoelectric layer 18 is preferably 1/3 or more and 1 or less of the relative dielectric constant of the first piezoelectric layer 14, and the piezoelectric constant d _{31 of the} second piezoelectric layer 18. Is preferably 1/50 or more and 1 or less of the first piezoelectric layer 14. The piezoelectric constant d ₃₁ of the second piezoelectric layer 18 is more preferably ½ or more that of the first piezoelectric layer 14. By selecting the piezoelectric constant d ₃₁ in the second piezoelectric layer 18 in this way, the voltage between the first piezoelectric layer 14 and the second piezoelectric layer 18 when a voltage is applied to the piezoelectric thin film element 20. It becomes easy to suppress the generation of internal stress at the interface.

  Further, regarding the piezoelectric material constituting the second piezoelectric layer 18, the piezoelectric material is preferably a polycrystalline body preferentially oriented in the (111) plane or the (001) plane. At this time, the orientation ratio α (111) or α (001) is preferably 70% or more, more preferably 90% or more, as in the first piezoelectric layer 14.

  The second electrode layer 19 is for applying a voltage to the piezoelectric layers (the first piezoelectric layer 14 and the second piezoelectric layer 18) together with the first electrode layer 13, and has a desired conductivity. Formed by material. The thickness of the second electrode layer 19 is appropriately selected within a range of approximately 0.1 to 0.4 μm depending on the material.

  In the piezoelectric thin film element 20 having such a structure, since the holes 17 generated in the first piezoelectric layer 14 are filled with the second piezoelectric layer 18, a leak path is formed when a voltage is applied. Generation of electric field concentration is suppressed. Further, when a voltage is applied, both the first piezoelectric layer 14 and the second piezoelectric layer 18 are deformed, so that a large internal stress is unlikely to occur, and therefore microcracks are unlikely to occur. For these reasons, the piezoelectric thin film element 20 can easily improve its reliability and durability.

(Embodiment 2)
FIG. 2 is a sectional view schematically showing another example of the piezoelectric thin film element of the present invention. In the figure, 61 is a substrate, 62 is an adhesion layer, 63 is a first electrode layer, 64 is a first piezoelectric layer, 67 is a hole, 70 is a second piezoelectric layer, and 71 is a second electrode layer. , 72 are piezoelectric thin film elements. The adhesion layer 12, the first electrode layer 63, and the first piezoelectric layer 64 are laminated in this order on the substrate 61, and the voids 67 generated in the first piezoelectric layer 64 are filled with the voids 67. The second piezoelectric layer 70 is formed only in the hole 67, and the second electrode layer 71 is formed so as to cover the first piezoelectric layer 64 and the second piezoelectric layer 70, and the piezoelectric thin film element 72 is constituted.

  The difference from the piezoelectric thin film element 20 (see FIG. 1) described in the first embodiment is that the second piezoelectric layer 70 is formed only in the holes 67. Other configurations of the piezoelectric thin film element 72 are the same as those of the piezoelectric thin film element 20 including the composition of each layer.

  Also in the piezoelectric thin film element 72 having such a structure, the holes 67 generated in the first piezoelectric layer 64 are filled with the second piezoelectric layer 70 as in the piezoelectric thin film element 20 described in the first embodiment. Therefore, when a voltage is applied, the formation of a leak path and the occurrence of electric field concentration are suppressed. Further, when a voltage is applied, both the first piezoelectric layer 64 and the second piezoelectric layer 70 are deformed, so that a large internal stress is unlikely to occur, and therefore microcracks are unlikely to occur. For these reasons, the piezoelectric thin film element 72 can easily improve its reliability and durability.

(Embodiment 3)
The piezoelectric thin film element of the present invention can be manufactured, for example, by the method for manufacturing a piezoelectric thin film element of the present invention including a foreign matter removing step and a second piezoelectric layer forming step. Hereinafter, taking the case of manufacturing the piezoelectric thin film element 20 (see FIG. 1) described in the first embodiment as an example, an example of the manufacturing method of the present invention will be described in detail for each process.

(Foreign substance removal process)
In the foreign matter removing step, the first piezoelectric layer made of an oxide having a perovskite-type crystal structure containing lead as a constituent element is washed through the first electrode layer to clean the first piezoelectric layer. In the process of forming the body layer, the foreign matter mixed in the first piezoelectric layer and the by-product layer formed on the first piezoelectric layer are removed.

  FIG. 3A is a cross-sectional view schematically showing an example of each of foreign matters mixed in the first piezoelectric layer and by-product layers generated in the first piezoelectric layer. Among the constituent elements shown in the figure, those common to the constituent elements shown in FIG. 1 are denoted by the same reference numerals as those used in FIG. 1 and description thereof is omitted. As shown in FIG. 3A, the first piezoelectric layer 14 is formed on the substrate 11 via the first electrode layer 13, and between the first electrode layer 13 and the substrate 11. Has an adhesion layer 12 interposed. Foreign matter 15 is mixed in the first piezoelectric layer 14, and a by-product layer 16 made of, for example, lead oxide is formed around the foreign matter 15.

  Note that each of the adhesion layer 12, the first electrode layer 13, and the first piezoelectric layer 14 has, for example, a sputtering method, a vacuum evaporation method, a laser beam evaporation method, an ion plating method, Physical vapor deposition method (PVD method) such as molecular beam epitaxy (MBE) method, chemical vapor deposition method (CVD method) such as metal organic chemical vapor deposition method (MOCVD method) and plasma CVD method, or metal It is formed by a chemical solution deposition method (CSD method) such as an organic compound deposition method (MOD method) or a sol-gel method.

  In the foreign matter removing step, the foreign matter 15 and the by-product layer 16 are removed by a specific cleaning process. For example, after the ultrasonic cleaning in water or an organic solvent, the operation of cleaning with a liquid (solvent) in which the by-product layer 16 is dissolved is repeated once or a plurality of times, whereby the foreign matter 15 and the by-product layer 16 are removed. Remove. The cleaning of the by-product layer 16 using a solvent may be performed by combining cleaning with dilute sulfuric acid and cleaning with hydrogen peroxide solution in this order, for example.

  FIG. 3B is a cross-sectional view schematically showing the first piezoelectric layer from which foreign substances and by-product layers are removed. Among the constituent elements shown in the figure, those common to the constituent elements shown in FIG. 1 are denoted by the same reference numerals as those used in FIG. 1 and description thereof is omitted. As shown in FIG. 3B, the first piezoelectric layer 14 from which the foreign matter 15 and the by-product layer 16 (see FIG. 3A) have been removed by the above-described cleaning has the foreign matter 15 and the by-product. Holes 17 are formed where the layer 16 was.

(Second piezoelectric layer forming step)
In the second piezoelectric layer forming step, a first piezoelectric layer made of an electrically insulating oxide is formed on the first piezoelectric layer that has been subjected to the foreign matter removing step so as to fill holes in the first piezoelectric layer. 2 piezoelectric layers are formed.

  FIG. 3C is a cross-sectional view schematically showing an example of the second piezoelectric layer. Among the constituent elements shown in the figure, those common to the constituent elements shown in FIG. 1 are denoted by the same reference numerals as those used in FIG. 1 and description thereof is omitted. As shown in FIG. 3C, the second piezoelectric layer 18 is formed on the first piezoelectric layer 14 so as to fill the holes 17 and covers the first piezoelectric layer 14. ing. The second piezoelectric layer 18 can be formed by a method similar to the method of forming the first piezoelectric layer 14.

  In the target piezoelectric thin film element 20, after the second piezoelectric layer 18 is formed as described above, the second electrode layer 19 is formed on the second piezoelectric layer 18 as shown in FIG. Is obtained. The second electrode layer 19 can be formed by a method similar to the method for forming the first electrode layer 13.

(Embodiment 4)
As in the piezoelectric thin film element 72 described in the second embodiment, the piezoelectric thin film element in which the second piezoelectric layer is formed only in the hole so as to fill the hole formed in the first piezoelectric layer. Is obtained by the manufacturing method of the present invention, the second piezoelectric layer forming step described in the third embodiment is divided into, for example, three sub-steps. Hereinafter, taking the case of manufacturing the piezoelectric thin film element 72 described in the second embodiment as an example, another example of the manufacturing method of the present invention will be described in detail for each process.

(Washing process)
The cleaning process is performed in the same manner as the cleaning process described in the third embodiment. As shown in FIG. 4A, the first piezoelectric layer 64 to be cleaned is formed on the substrate 61 via the first electrode layer 63, and the first electrode layer 63 and the substrate 61 are formed. An adhesion layer 62 is interposed therebetween. Foreign matter 65 is mixed in the first piezoelectric layer 64, and a by-product layer 66 made of, for example, lead oxide is formed around the foreign matter 65.

  As shown in FIG. 4B, after the cleaning process is performed, the foreign matter 65 and the by-product layer 66 (see FIG. 4A) are removed from the first piezoelectric layer 64, and the foreign matter 65 and Holes 67 are formed at locations where the by-product layer 66 was present.

  Each of the adhesion layer 62, the first electrode layer 63, and the first piezoelectric layer 64 is the adhesion layer 12, the first electrode layer 13, or the first piezoelectric layer described in the third embodiment. 14 is formed. Among the constituent elements shown in FIG. 4A or FIG. 4B, the same constituent elements as those shown in FIG. 2 are denoted by the same reference numerals as those used in FIG. Omitted. The same applies to components shown in FIGS. 4C to 4F described later.

(Second piezoelectric layer forming step)
In the second piezoelectric layer forming step, the following first to third sub-steps are performed in this order to fill the holes formed in the first piezoelectric layer so as to fill the second piezoelectric layer only in the holes. A body layer is formed.

  In the first sub-process, as shown in FIG. 4C, the piezoelectric layer 68 that fills the holes 67 is formed in the same manner as the second piezoelectric layer forming process described in the third embodiment. It is formed on the entire top surface of the piezoelectric layer 64. As will be described later, the piezoelectric layer 68 is patterned to form the second piezoelectric layer. The piezoelectric layer 68 is formed in the same manner as the second piezoelectric layer 18 described in the third embodiment.

  In the second sub-process, a resist layer 69 is formed on the piezoelectric layer 68 as shown in FIG. The resist layer 69 is formed, for example, by spin coating so that the upper surface thereof is a flat surface.

  In the third sub-step, as shown in FIG. 4E, the resist layer 69 and the piezoelectric layer 68 are etched back, leaving the piezoelectric layer 68 only in the holes 67. This piezoelectric layer becomes the second piezoelectric layer 70. In etching back the resist layer 69 and the piezoelectric layer 68, it is most preferable that these etching rates are the same, so that the etching rates are matched as much as possible or completely match. The material of the resist layer 69 is selected according to the material of the piezoelectric layer 68, and the etching gas and etching conditions for the etch back are selected.

  In the target piezoelectric thin film element 72, after the second piezoelectric layer 70 is formed as described above, the second electrode layer 71 is formed on the second piezoelectric layer 70 as shown in FIG. Is obtained. The second electrode layer 71 can be formed by a method similar to the method for forming the first electrode layer 63.

(Embodiment 5)
The inkjet head of the present invention includes a piezoelectric thin film element in which a piezoelectric layer is formed on a first electrode layer and a second electrode layer is formed on the piezoelectric layer, and a first electrode in the piezoelectric thin film element A diaphragm layer provided on the surface of one of the layers and the second electrode layer, and a pressure chamber that is bonded to a surface of the diaphragm layer opposite to the piezoelectric thin film element side and accommodates ink And a pressure chamber member having a pressure chamber member, and the diaphragm layer is displaced in the layer thickness direction by the piezoelectric effect of the piezoelectric thin film element to discharge ink in the pressure chamber. And said piezoelectric thin film element has the structure remove | excluding the board | substrate from the piezoelectric thin film element of this invention.

  FIG. 5 is a perspective view schematically showing an example of the ink jet head of the present invention, and FIG. 6 is a partial cross-sectional perspective view schematically showing a configuration of a main part of the ink jet head shown in FIG. . 5 and 6, A is a pressure chamber member. The pressure chamber member A is formed with a pressure chamber opening 101 (see FIG. 6) penetrating in the thickness direction (vertical direction). Has been. B is a piezoelectric thin film actuator portion (hereinafter simply referred to as “actuator portion”) disposed so as to cover the upper end opening of the pressure chamber opening 101, and C is a lower end opening of the pressure chamber opening 101. The ink flow path member is arranged so as to cover the ink. The pressure chamber opening 101 of the pressure chamber member A is closed to the pressure chamber 102 by being closed by the actuator portion B and the ink flow path member C positioned above and below the opening 101, respectively.

  The actuator part B has a first electrode layer 103 (individual electrode) positioned substantially immediately above each pressure chamber 102, and the pressure chamber 102 and the first electrode layer 103 can be seen from FIG. Many are arranged in a staggered pattern.

  The ink flow path member C includes a common liquid chamber 105 shared by the pressure chambers 102 arranged in the ink supply direction, a supply port 106 for supplying ink in the common liquid chamber 105 to the pressure chamber 102, and a pressure chamber. And an ink flow path 107 for ejecting the ink in 102.

  D is a nozzle plate, and a nozzle hole 108 communicating with the ink flow path 107 is formed in the nozzle plate D. E is an IC chip, and a voltage is supplied from the IC chip to each of the first electrode layers 103 via bonding wires BW.

  Next, the configuration of the actuator part B will be described with reference to FIG. FIG. 7 is a cross-sectional view in a direction orthogonal to the ink supply direction shown in FIG. In the figure, a pressure chamber member A having four pressure chambers 102 arranged in the orthogonal direction is drawn for reference. As described above, the actuator portion B includes the first electrode layer 103 positioned substantially immediately above each pressure chamber 102 and the first electrode layer 103 provided on each first electrode layer 103 (lower side in the figure). The piezoelectric layer 104, the second piezoelectric layer 110 provided on the first piezoelectric layer 104 (on the lower side), and the second piezoelectric layer 110 provided on the lower side (on the same side). A second electrode layer 112 (common electrode) that is common to all the second piezoelectric layers 110, and provided on the second electrode layer 112 (on the same side) as the first piezoelectric body. A vibration plate layer 111 that vibrates by being displaced in the layer thickness direction by the piezoelectric effect of the layer 104 and the second piezoelectric layer 110, and is provided on the vibration plate layer 111 (on the lower side), and partitions each pressure chamber 102. An intermediate layer 113 (vertical wall) located above the partition wall 102a, and the first electrode layer 103. The first piezoelectric layer 104, the second piezoelectric layer 110 and the second electrode layer 112 may constitute the piezoelectric thin-film element which they are stacked in this order. The diaphragm layer 111 is provided on the surface of the piezoelectric thin film element on the second electrode layer 112 side.

  Note that reference numeral 114 in FIG. 7 indicates an adhesive that bonds the pressure chamber member A and the actuator portion B, and each of the intermediate layers 113 is partially bonded at the time of bonding using the adhesive 114. Even when the adhesive 114 protrudes to the outside of the partition wall 102a, the adhesive layer 114 does not adhere to the vibration plate layer 111 so that the vibration plate layer 111 causes the desired displacement and vibration. It has the role of increasing the distance between the upper surface and the lower surface of the diaphragm layer 111. As described above, it is preferable to join the pressure chamber member A to the surface of the vibration plate layer 111 of the actuator portion B opposite to the second electrode layer 112 through the intermediate layer 113, but The pressure chamber member A may be directly joined to the surface opposite to the electrode layer 112.

  The constituent materials of the first electrode layer 103, the first piezoelectric layer 104, the second piezoelectric layer 110, and the second electrode layer 112 are the same as those of the first electrode layer 13 described in the first embodiment. These are the same as the first piezoelectric layer 14, the second piezoelectric layer 18 and the second electrode layer 19 (some of the constituent elements have different contents).

  Next, a manufacturing method of an ink jet head excluding the IC chip E of FIG. 5, that is, an ink jet head comprising the pressure chamber member A, the actuator part B, the ink flow path member C and the nozzle plate D shown in FIG. 6 or FIG. 8 to 12 will be described.

  As shown in FIG. 8A, an adhesion layer 121, a first electrode layer 103, a first piezoelectric layer 104, a second piezoelectric layer 110, a second electrode layer 112, and a diaphragm are formed on a substrate 120. The layer 111 and the intermediate layer 113 are sequentially deposited by sputtering. The substrate 120 corresponds to the substrate 11 described in the first embodiment, and the adhesion layer 121 corresponds to the adhesion layer 12. The adhesion layer 121 is formed between the substrate 120 and the first electrode layer 103 as necessary in order to improve adhesion between the substrate 120 and the first electrode layer 103. The adhesion layer 121 is removed in the same manner as the substrate 120 as described later. For example, chromium (Cr) is used as the material of the diaphragm layer 111, and titanium (Ti) is used as the material of the intermediate layer 113, for example. Note that after the first piezoelectric layer 104 is formed, cleaning for removing foreign substances and by-product layers such as a lead oxide layer is performed, and then the second piezoelectric layer 110 is formed.

  The method for forming and cleaning the adhesion layer 121, the first electrode layer 103, the first piezoelectric layer 104, the second piezoelectric layer 110, and the second electrode layer 112 are the same as those in Example 1 of the present invention. It is the same.

  The diaphragm layer 111 is obtained, for example, by performing sputtering for 6 hours at a high frequency power of 200 W in a 1 Pa argon gas atmosphere using a chromium (Cr) target at a room temperature. The thickness of the diaphragm layer 111 is 3 μm, for example. The material of the diaphragm layer 111 is not limited to chromium (Cr), but a metal (such as silicon) such as nickel (Ni), aluminum (Al), tantalum (Ta), tungsten (W), and silicon (Si). And oxides or nitrides of these metals, such as silicon dioxide, aluminum oxide, zirconium oxide, silicon nitride, and the like. Moreover, the thickness of the diaphragm layer 111 can be appropriately selected within a range of approximately 2 to 5 μm.

  The intermediate layer 113 is obtained, for example, by sputtering using a titanium (Ti) target at a film formation temperature of room temperature and in a 1 Pa argon gas atmosphere at a high frequency power of 200 W for 5 hours. The thickness of the intermediate layer 113 is, for example, 5 μm. The material of the intermediate layer 113 is not limited to titanium (Ti), but may be any conductive metal such as chromium (Cr). Further, the thickness of the intermediate layer 113 can be appropriately selected within a range of approximately 3 to 10 μm.

  Separately from the formation of these layers, a pressure chamber member A is formed as shown in FIG. The pressure chamber member A is formed using a substrate having a size larger than the substrate 120, for example, a 4-inch silicon wafer 130 (see FIG. 13). Specifically, the silicon wafer 130 (for pressure chamber member) is patterned to form a plurality of pressure chamber openings 101. As can be seen from FIG. 8B, this patterning is performed with four pressure chamber openings 101 as one set, and the thickness (thickness in the horizontal direction) of the partition wall 102b dividing each set is as follows. It is set to about twice the thickness of the partition wall 102a that partitions the pressure chamber opening 101 in each set.

  Thereafter, the substrate 120 on which the above-described layers are formed and the above-described pressure chamber member A are bonded using an adhesive. As shown in FIG. 8C, the adhesive layer used at this time is formed on the upper surface of each partition wall 102a, 102b in the pressure chamber member A by, for example, an electrodeposition method. In forming the adhesive layer 114 by the electrodeposition method, first, a base electrode made of a nickel (Ni) thin film of several hundreds of angstroms (several tens of nanometers) thin enough to transmit light on the upper surfaces of the partition walls 102a and 102b. A film (not shown) is formed by sputtering. Next, an adhesive layer 114 is formed by electrodeposition on the nickel (Ni) thin film. As the electrodeposition liquid at this time, for example, a solution obtained by adding 0 to 50 parts by weight of pure water to an acrylic resin aqueous dispersion and stirring and mixing it well is used. The reason why the thickness of the nickel (Ni) thin film is set so thin that light is transmitted is to make it easy to visually recognize that the adhesive resin is completely attached to the pressure member A. The electrodeposition conditions are, for example, a liquid temperature of about 25 ° C., a DC voltage of 30 V, an energization time of 60 seconds, and the thickness of the adhesive layer 114 is set to, for example, about 3 to 10 μm.

  Thereafter, as shown in FIG. 9A, the substrate 120 on which the above-described layers are formed and the pressure chamber member A are bonded using an adhesive layer 114. This adhesion is performed using the intermediate layer 113 formed on the substrate 120 as a substrate-side adhesion surface. Further, since the silicon wafer 130 is larger than the substrate 120 (for film formation), for example, when the size of the substrate 120 is 18 mm and the silicon wafer 130 is a 4-inch wafer, as shown in FIG. In the figure, 14 substrates 120 can be attached to one pressure chamber member A (silicon wafer 130). As shown in FIG. 9A, this pasting is performed in a state where the centers of the respective substrates 120 are aligned so as to be positioned at the center of one partition wall 102b in the pressure chamber member A. After the pasting, the pressure chamber member A is pressed and brought into close contact with the substrate 120 side, and both are bonded with high liquid tightness. Further, the temperature of the bonded substrate 120 and pressure chamber member A is gradually raised in a heating furnace, and the adhesive layer 114 is completely cured. Subsequently, plasma treatment is performed to remove the protruding portion of the adhesive 114.

  In FIG. 9A, the substrate 120 on which each layer is formed and the pressure chamber member A are bonded, but the above-described layers are formed on the silicon wafer 130 at a stage where the pressure chamber opening 101 is not formed. It may be adhered to the substrate 120.

  Next, as shown in FIG. 9B, the intermediate layer 113 is etched using the partition walls 102a and 102b of the pressure chamber member A as a mask, so that the intermediate layer 113 has a predetermined shape, that is, each partition wall 102a. , 102b are patterned into a shape (vertical wall) continuous.

  Next, as shown in FIG. 10A, the substrate 120 and the adhesion layer 121 are removed by etching. Subsequently, as shown in FIG. 10B, the first electrode layer 103 located on the pressure chamber member A is etched by photolithography to be individualized for each pressure chamber 102. Then, as shown in FIG. 11A, the first piezoelectric layer 104 and the second piezoelectric layer 110 are etched by a photolithography technique to be individualized in the same shape as the first electrode layer 103. To do. The first electrode layer 103, the first piezoelectric layer 104, and the second piezoelectric layer 110 after the etching are positioned above each of the pressure chambers 102, and the first electrode layer 103, the first piezoelectric layer The center in the width direction of the piezoelectric layer 104 and the second piezoelectric layer 110 is formed to coincide with the center in the width direction of the corresponding pressure chamber 102 with high accuracy.

  After individualizing the first electrode layer 103, the first piezoelectric layer 104, and the second piezoelectric layer 110 for each pressure chamber 102 in this way, as shown in FIG. By cutting at each partition wall 102b, four sets of the pressure chamber member A having four pressure chambers 102 and the actuator portion B fixed to the upper surface thereof can be obtained.

  Subsequently, as shown in FIG. 12A, the common liquid chamber 105, the supply port 106, and the ink flow path 107 are formed in the ink flow path member C, and the nozzle hole 108 is formed in the nozzle plate D. Next, as shown in FIG. 12B, the ink flow path member C and the nozzle plate D are bonded using an adhesive 109.

  Thereafter, as shown in FIG. 12C, an adhesive (not shown) is transferred to the lower end surface of the pressure chamber member A or the upper end surface of the ink channel member C, and the pressure chamber member A and the ink channel member C are transferred. Both are bonded with the above adhesive while adjusting the alignment. As a result, the inkjet head 150 having the pressure chamber member A, the actuator portion B, the ink flow path member C, and the nozzle plate D is completed as shown in FIG.

  A portion corresponding to each pressure chamber 102 in the diaphragm layer 111 by applying a predetermined voltage between the first electrode layer 103 and the second electrode layer 112 in the inkjet head 150 obtained as described above. When the amount of displacement in the layer thickness direction was measured, the variation σ of the amount of displacement was 1.8%. Further, even when a 20 V AC voltage having a frequency of 20 kHz was continuously applied for 10 days, no ink ejection failure occurred, and no deterioration in ejection performance was observed.

  On the other hand, an ink jet head that differs from the above ink jet head 150 only in that the second piezoelectric layer 110 is not provided, and the first electrode layer 103 and the second electrode layer 112 in this ink jet head are formed. When a predetermined voltage was applied between them and the displacement amount in the layer thickness direction of the portion corresponding to each pressure chamber 102 in the diaphragm layer 111 was measured, the variation σ of the displacement amount was 2.2%. Further, when a 20 V AC voltage having a frequency of 20 kHz was continuously applied for 10 days, an ink ejection failure occurred in a portion corresponding to about 70% of the pressure chambers 102 out of the total pressure chambers 102. This is considered to be due to the low durability performance of the actuator part B (piezoelectric thin film element) because it is not ink clogging or the like.

  From these, it can be seen that the inkjet head 150 of the present embodiment is excellent in durability performance.

(Embodiment 6)
FIG. 14 is a cross-sectional view schematically showing the main part of another example of the inkjet head of the present invention. The inkjet head 420 shown in the figure does not use the substrate separately for the piezoelectric thin film element and the pressure chamber member as in the inkjet head 150 (see FIG. 12D) described in the fifth embodiment. The piezoelectric thin film element and the pressure chamber member are used as one substrate.

  Specifically, on the pressure chamber substrate 401 in which the pressure chamber 402 is formed by etching, a diaphragm layer 403, an adhesion layer 404, a first electrode layer 406 (common electrode), a first piezoelectric layer 407, The second piezoelectric layer 408 and the second electrode layer 409 (individual electrode) are laminated in this order. The first electrode layer 406, the first piezoelectric layer 407, the second piezoelectric layer 408, and the second electrode layer 409 constitute a piezoelectric thin film element in which these are sequentially laminated. Further, the diaphragm layer 403 is provided on the surface of the piezoelectric thin film element on the first electrode layer 406 side via the adhesion layer 404. The adhesion layer 404 enhances the adhesion between the diaphragm layer 403 and the first electrode layer 406 and may not be the same as the adhesion layer 121 in the fifth embodiment.

  The constituent materials of the adhesive layer 404, the first electrode layer 406, the first piezoelectric layer 407, the second piezoelectric layer 408, and the second electrode layer 409 are the same as those described in Embodiment Mode 5. This is the same as the layer 121, the first electrode layer 103, the first piezoelectric layer 104, the second piezoelectric layer 110, or the second electrode layer 112, respectively. The structures of the first piezoelectric layer 407 and the second piezoelectric layer 408 are the same as the structures of the first piezoelectric layer 104 or the second piezoelectric layer 110, respectively. After the formation of the first piezoelectric layer 407, cleaning for removing foreign substances and by-product layers such as a lead oxide layer is performed to form the second piezoelectric layer 408.

  For example, a 4-inch silicon wafer having a thickness of 200 μm, a glass substrate, a metal substrate, or a ceramic substrate is used as the pressure chamber substrate 401.

  The thickness of the diaphragm layer 403 is appropriately selected within a range of approximately 0.5 to 10 μm. For example, the diaphragm layer 403 can be formed of a silicon dioxide layer having a film thickness of 2.8 μm. Note that the material of the diaphragm layer 403 is not limited to silicon dioxide, and may be the material described in the fifth embodiment (a simple substance such as nickel or chromium or an oxide or nitride thereof). .

  Next, a method for manufacturing the inkjet head 420 will be described with reference to FIG.

  In manufacturing the ink-jet head 420, first, as shown in FIG. 15A, the vibration chamber layer 403, the adhesion layer 404, and the first electrode layer 406 are formed on the pressure chamber substrate 401 in which the pressure chamber 402 is not formed. The first piezoelectric layer 407, the second piezoelectric layer 408, and the second electrode layer 409 are sequentially formed by a sputtering method.

The diaphragm layer 403 is formed, for example, in a mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas (gas volume ratio Ar: O ₂ = 5: 25) at an atmospheric pressure of 0.4 Pa. It is obtained by bringing the temperature to room temperature and sputtering a silicon dioxide sintered compact target with high frequency power of 300 W for 8 hours. Note that the method of forming the diaphragm layer 403 is not limited to the sputtering method, and may be a thermal CVD method, a plasma CVD method, a sol-gel method, or the like. Furthermore, the diaphragm layer 403 may be formed by thermally oxidizing the pressure chamber substrate 401.

  The adhesion layer 404, the first electrode layer 406, the first piezoelectric layer 407, the second piezoelectric layer 408, and the second electrode layer 409 formed on the vibration plate layer 403, respectively, and the first The cleaning method performed after the formation of the first piezoelectric layer 407 is the adhesion layer 12, the first electrode layer 13, the first piezoelectric layer 14, the second piezoelectric layer 18, and the like described in Embodiment 1. This is the same as the film formation method of the second electrode layer 19 and the cleaning method performed after the film formation of the first piezoelectric layer 14.

  After the formation of the second electrode layer 409, a resist is applied onto the second electrode layer 409 by spin coating, and exposure and development are performed in accordance with the position where the pressure chamber 402 is to be formed to obtain a resist pattern. . Using this resist pattern also as an etching mask, the second electrode layer 409, the second piezoelectric layer 408, and the first piezoelectric layer 407 are etched and individualized. This etching is performed by dry etching using, for example, a mixed gas of argon gas and an organic gas containing a fluorine element as an etching gas.

  Subsequently, as shown in FIG. 15B, a pressure chamber 402 is formed on the pressure chamber substrate 401. The pressure chamber 402 is formed by anisotropic dry etching using, for example, sulfur hexafluoride gas, an organic gas containing a fluorine element, or a mixed gas thereof as an etching gas. A resist pattern is formed on the surface of the pressure chamber substrate 401 opposite to the surface on which each of the films is formed so as to cover a portion that becomes the side wall 413, and this resist pattern is used as an etching mask to perform anisotropy. The pressure chamber 402 is formed by dry etching.

  After that, the nozzle plate 412 (see FIG. 14) in which the nozzle holes 410 are formed in advance is bonded to the surface of the pressure chamber substrate 401 opposite to the surface on which the respective films are formed by using an adhesive. The head 420 (see FIG. 14) is completed. The nozzle hole 410 is formed at a predetermined position of the nozzle plate 412 by lithography, laser processing, electric discharge processing, or the like. Then, when the nozzle plate 412 is joined to the pressure chamber substrate 401, alignment is performed so that each nozzle hole 410 is disposed corresponding to the pressure chamber 402.

  A predetermined voltage is applied between the first electrode layer 406 and the second electrode layer 409 in the inkjet head 420 obtained as described above, and the portions corresponding to the pressure chambers 402 in the diaphragm layer 403 are applied. When the displacement amount in the layer thickness direction was measured, the variation σ of the displacement amount was 1.8%. Further, even when a 20 V AC voltage having a frequency of 20 kHz was continuously applied for 10 days, no ink ejection failure occurred, and no deterioration in ejection performance was observed.

  On the other hand, an ink jet head that differs from the above ink jet head 420 only in that the second piezoelectric layer 408 is not provided, and the first electrode layer 406 and the second electrode layer 409 in the ink jet head are manufactured. When a predetermined voltage was applied between them and the displacement amount in the layer thickness direction of the portion corresponding to each pressure chamber 402 in the diaphragm layer 403 was measured, the variation σ of the displacement amount was 2.4%. In addition, when a 20 V AC voltage having a frequency of 20 kHz was continuously applied for 10 days, ink ejection failure occurred in the portion corresponding to about 65% of the pressure chambers 402 out of the total pressure chambers 402. This is considered to be due to the low durability performance of the actuator section (piezoelectric thin film element) because it is not clogged with ink or the like.

  From these facts, it can be seen that the inkjet head 420 of the present embodiment is excellent in durability as in the inkjet head 150 of the fifth embodiment described above (see FIG. 12D). .

(Embodiment 7)
An ink jet recording apparatus of the present invention includes the above-described ink jet head of the present invention and relative moving means for moving the ink jet head relative to a recording medium, and the ink jet head is made relative to the recording medium by the relative moving means. When moving, recording is performed by discharging ink from the inkjet head onto a recording medium.

  FIG. 16 is a perspective view schematically showing an example of a main part of the ink jet recording apparatus of the present invention. An ink jet recording apparatus 27 shown in the figure includes an ink jet head 28 similar to that described in the fifth or sixth embodiment. In the ink jet head 28, a pressure chamber (such as the pressure chamber 102 in the fifth embodiment or the like) is provided. Ink in the pressure chamber is recorded on recording paper or the like from nozzle holes (nozzle hole 108 in the fifth embodiment or nozzle hole 410 in the sixth embodiment) provided to communicate with the pressure chamber 402 in the sixth embodiment. The recording is performed by discharging to the medium 29.

  The inkjet head 28 is mounted on a carriage 31 provided on a carriage shaft 30 extending in the main scanning direction X, and reciprocates in the main scanning direction X as the carriage 31 reciprocates along the carriage shaft 30. It is configured to move. The carriage 31 constitutes a relative movement unit that relatively moves the inkjet head 28 and the recording medium 29 in the main scanning direction X.

  The ink jet recording apparatus 27 includes a plurality of rollers 32 that move the recording medium 29 in the sub scanning direction Y substantially perpendicular to the main scanning direction X (width direction) of the ink jet head 28. The plurality of rollers 32 constitute a relative moving unit that relatively moves the inkjet head 28 and the recording medium 29 in the sub-scanning direction Y. When the inkjet head 28 is moved in the main scanning direction X by the carriage 31, ink is ejected from the nozzle holes of the inkjet head 28 onto the recording medium 29. The medium 29 is moved by a predetermined amount to perform the next one-scan recording. Note that the reference sign “Z” in FIG. 16 indicates the vertical direction.

  The ink jet recording apparatus 27 configured as described above includes the ink jet head 28 similar to the ink jet head described in the fifth embodiment or the sixth embodiment, and thus has good printing performance and durability performance. ing.

(Example 1)
An example of the piezoelectric thin film element 20 (see FIG. 1) described in the first embodiment will be described in detail with appropriate reference numerals used in FIG.

  The adhesion layer 12, the first electrode layer 13, and the first piezoelectric layer 14 are sequentially formed on a 4-inch silicon wafer (substrate 11) by a sputtering method and washed to thereby remove the foreign matter 15 and the byproduct layer 16. Then, the second piezoelectric layer 18 is formed on the first piezoelectric layer 14 by sputtering, and then diced to a predetermined size, and then the second electrode layer 19 is formed by sputtering. Thus, a predetermined number of piezoelectric thin film elements 20 were obtained.

  First, while heating a silicon wafer (substrate 11) to 400 ° C. in an argon (Ar) gas atmosphere of 1 Pa, a titanium (Ti) target is sputtered with a high frequency power of 100 W for 1 minute to form a silicon wafer (substrate 11). An adhesion layer 12 made of titanium and having a thickness of 0.02 μm was formed.

  Next, while heating the silicon wafer (substrate 11) to 400 ° C. in an argon (Ar) gas atmosphere of 1 Pa, a platinum (Pt) target is sputtered for 12 minutes at a high frequency power of 200 W, and platinum is deposited on the adhesion layer 12. A first electrode layer 13 having a thickness of 0.22 μm was formed. The first electrode layer 13 (platinum layer) is a polycrystalline body preferentially oriented in the (111) plane.

Next, while heating the silicon wafer (substrate 11) to 580 ° C. in a mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas (gas volume ratio Ar: O ₂ = 16: 4), zirconium A PZT sintered compact target having an atomic ratio of (Zr) to titanium (Ti) of Zr / Ti = 52/48 is sputtered with a high frequency power of 250 W for 1 hour, and is made of PZT on the first electrode layer 13. A first piezoelectric layer 14 having a thickness of 1.6 μm was formed. At this time, the pressure of the mixed gas atmosphere during film formation was set to 0.3 Pa.

  By removing the silicon wafer (substrate 11) on which the first piezoelectric layer 14 is formed, cleaning with diluted sulfuric acid after ultrasonic cleaning, and then cleaning with hydrogen peroxide solution three times, The foreign matter mixed in the first piezoelectric layer 14 and the by-product layer made of lead oxide formed on the first piezoelectric layer 14 were removed.

Then, a second piezoelectric layer 18 made of PZT and having a thickness of 1.0 μm was formed on the first piezoelectric layer 14 from which the foreign matters and by-product layers were removed by sputtering. As a sputtering target at this time, a PZT sintered body having an atomic ratio of zirconium (Zr) to titanium (Ti) of Zr / Ti = 58/42 was used. While heating the silicon wafer (substrate 11) to 620 ° C. in a mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas (gas volume ratio Ar: O ₂ = 16: 4), the above sputtering target Was sputtered with a high frequency power of 220 W for 1 hour. The pressure of the mixed gas atmosphere at the time of film formation was 0.3 Pa.

  Thereafter, the silicon wafer (substrate 11) is diced to obtain a total of 50 intermediate products having a size in plan view of 15 mm × 2 mm, and platinum is formed on the second piezoelectric layer 18 in each of these intermediate products. A second electrode layer 19 having a thickness of 0.2 μm was formed by sputtering to obtain a total of 50 piezoelectric thin film elements 20. In forming the second electrode layer 19, a platinum (Pt) target is sputtered at a high frequency power of 200 W for 10 minutes while keeping the temperature of the silicon wafer (substrate 11) at room temperature in an argon (Ar) gas atmosphere of 1 Pa. did.

  The crystal structure and crystal orientation in each of the first piezoelectric layer 14 and the second piezoelectric layer 18 in each piezoelectric thin film element 20 thus obtained were examined by X-ray diffraction. The crystal structure and crystal orientation of the first piezoelectric layer 14 were measured before the second piezoelectric layer 18 was formed. As a result, both the first piezoelectric layer 14 and the second piezoelectric layer 18 had a rhombohedral perovskite crystal structure and preferentially oriented in the (111) plane. The orientation rate α (111) was 99% in any layer.

Further, the piezoelectric constant d ₃₁ was measured for each piezoelectric thin film element 20 (see, for example, JP-A-2002-225285 for the method of measuring the piezoelectric constant d ₃₁ ). As a result, the piezoelectric constant d ₃₁ of each piezoelectric thin film element 20 was 165 pC / N on average, and the variation σ was 3.5%. Further, when the relative dielectric constant ε _r was measured, the relative dielectric constant ε _r was 830.

Separately, the silicon wafer (substrate 11) is diced in a state before the second piezoelectric layer 18 is formed, and a sample having a size in plan view of 15 mm × 2 mm is cut out. A second electrode layer made of platinum having a thickness of 0.2 μm was formed on the piezoelectric layer 14 by sputtering, and the piezoelectric constant d ₃₁ of the first piezoelectric layer 14 was measured. As a result, the piezoelectric constant d ₃₁ of the first piezoelectric layer 14 averaged 172 pC / N, and the variation σ was 3.9%. Further, when the relative dielectric constant ε _r was measured, the relative dielectric constant ε _r was 870.

From the above results, when the piezoelectric constant d ₃₁ and the relative dielectric constant ε _r of the second piezoelectric layer 18 are calculated, the piezoelectric constant d ₃₁ and the relative dielectric constant ε _r of the second piezoelectric layer 18 are each 155 pC / N, 780.

  Next, when a DC voltage of 150 V was applied to the 50 piezoelectric thin film elements 20 for 5 minutes, no increase in leakage current was observed in all of the piezoelectric thin film elements 20, and no element breakdown occurred.

Furthermore, 30 piezoelectric thin film elements 20 having the same shape as the above-described piezoelectric thin film element 20 were produced again, and a 50 V, 200 Hz AC voltage having a sin waveform was continuously applied for 1000 hours to examine the durability performance. As a result, the piezoelectric constant d ₃₁ did not decrease in all 30 piezoelectric thin film elements 20.

(Comparative Example 1)
The comparative example is a piezoelectric thin film element having the same layer structure as the conventional piezoelectric thin film element 48 shown in FIG. 17, and each layer was formed under the above-described conditions. In contrast to the first embodiment, there is no step of removing the foreign substance existing in the piezoelectric layer and the by-product layer made of lead oxide by washing and the step of forming the second piezoelectric layer.

  The thickness of the piezoelectric layer was 2.6 μm and preferentially oriented to (111). The orientation rate α (111) was 99%.

After forming the piezoelectric layer, the silicon wafer was diced to obtain a total of 50 intermediate products having a size in plan view of 15 mm × 2 mm. A piezoelectric thin film element was obtained by forming a second electrode layer made of platinum having a thickness of 0.2 μm on the piezoelectric layer in each intermediate product by sputtering, and the piezoelectric constant d ₃₁ was measured for these piezoelectric thin film elements. It was. As a result, the piezoelectric constant d ₃₁ of the piezoelectric thin film element produced in this comparative example was 177 pC / N on average, and the variation σ was 3.3%. Further, when the relative dielectric constant ε _r was measured, the relative dielectric constant ε _r was 835.

  Next, when a DC voltage of 150 V was applied to the 50 piezoelectric thin film elements for 5 minutes, an increase in leakage current was observed in 23 samples, and 16 of them were damaged.

Furthermore, 30 piezoelectric thin film elements having the same shape as the above-described piezoelectric thin film element were produced again, and a 50 V, 200 Hz AC voltage having a sin waveform was continuously applied for 1000 hours to examine the durability performance. As a result, the piezoelectric constant d ₃₁ was lowered in all 30 piezoelectric thin film elements.

(Comparative Example 2)
The comparative example is a piezoelectric thin film element having the same layer structure as the conventional piezoelectric thin film element 58 shown in FIG. 18, and each layer was formed under the above-described conditions. Compared to the first embodiment, there is no second piezoelectric layer forming step after the step of removing the foreign substance existing in the piezoelectric layer and the by-product layer made of lead oxide by washing.

  The thickness of the piezoelectric layer was 2.6 μm and preferentially oriented to (111). The orientation rate α (111) was 99%.

After forming the piezoelectric layer, the silicon wafer was diced to obtain a total of 50 intermediate products having a size in plan view of 15 mm × 2 mm. A piezoelectric thin film element was obtained by forming a second electrode layer made of platinum having a thickness of 0.2 μm on the piezoelectric layer in each intermediate product by sputtering, and the piezoelectric constant d ₃₁ was measured for these piezoelectric thin film elements. It was. As a result, the piezoelectric constant d ₃₁ of the piezoelectric thin film element produced in this comparative example was 175 pC / N on average, and the variation σ was 3.5%. Further, when the relative dielectric constant ε _r was measured, the relative dielectric constant ε _r was 830.

  Next, when a direct current voltage of 150 V was applied to the 50 piezoelectric thin film elements for 5 minutes, an increase in leakage current was observed in 34 samples, and element breakdown occurred in 28 of them.

Furthermore, 30 piezoelectric thin film elements having the same shape as the above-described piezoelectric thin film element were produced again, and a 50 V, 200 Hz AC voltage having a sin waveform was continuously applied for 1000 hours to examine the durability performance. As a result, the piezoelectric constant d ₃₁ was lowered in all 30 piezoelectric thin film elements.

  From the results of Example 1, Comparative Example 1, and Comparative Example 2, the piezoelectric thin film element 20 of the present invention shown in Example 1 is superior in reliability and durability performance as compared with the conventional piezoelectric thin film element. I understand.

(Example 2)
In this embodiment, the second piezoelectric layer 18 is formed of lead titanate (PLT) doped with lanthanum (La), and the other layers are piezoelectric thin films manufactured under the same conditions as in the first embodiment. It is an element.

The second piezoelectric layer 18 uses a PLT sintered body target containing 30 mol% of lanthanum (La) and is in a mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas (gas volume ratio Ar). : O ₂ = 16: 4), while the silicon wafer (substrate 11) was heated to 580 ° C., the above sputtering target was sputtered at a high frequency power of 200 W for 1 hour. The pressure of the mixed gas atmosphere at the time of film formation is 0.3 Pa, and the thickness of the formed second piezoelectric layer 18 is 1.1 μm.

(Example 3)
In this embodiment, the second piezoelectric layer 18 is formed of PLZT, and the other layers are piezoelectric thin film elements manufactured under the same conditions as in the first embodiment.

The second piezoelectric layer 18 uses a PLZT sintered target containing 20 mol% of lanthanum (La) (the atomic ratio of zirconium (Zr) to titanium (Ti) is Zr / Ti = 58/42). In the mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas (gas volume ratio Ar: O ₂ = 25: 5), the above-mentioned sputtering is performed while heating the silicon wafer (substrate 11) to 630 ° C. The target was formed by sputtering at a high frequency power of 200 W for 1 hour. The pressure of the mixed gas atmosphere at the time of film formation is 0.4 Pa, and the thickness of the formed second piezoelectric layer 18 is 0.9 μm.

Example 4
In this embodiment, the second piezoelectric layer 18 is formed of PLZT, and the other layers are piezoelectric thin film elements manufactured under the same conditions as in the first embodiment.

The second piezoelectric layer 18 uses a PLZT sintered body target containing 10 mol% of lanthanum (La) (the atomic ratio of zirconium (Zr) to titanium (Ti) is Zr / Ti = 55/45). In the mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas (gas volume ratio Ar: O ₂ = 15: 5), the above-mentioned sputtering is performed while heating the silicon wafer (substrate 11) to 630 ° C. The target was formed by sputtering with a high frequency power of 210 W for 1 hour. The pressure of the mixed gas atmosphere at the time of film formation is 0.3 Pa, and the thickness of the formed second piezoelectric layer 18 is 1.2 μm.

(Example 5)
In this embodiment, the second piezoelectric layer 18 is formed of PZT having a specific composition, and the other layers are piezoelectric thin film elements manufactured under the same conditions as in the first embodiment.

The second piezoelectric layer 18 uses a PZT sintered body target in which the atomic ratio of zirconium (Zr) to titanium (Ti) is Zr / Ti = 45/55), and uses argon (Ar) gas and oxygen ( While the silicon wafer (substrate 11) is heated to 600 ° C. in a mixed gas atmosphere with O ₂ ) gas (gas volume ratio Ar: O ₂ = 20: 5), the sputtering target is heated at a high frequency power of 200 W for 1 hour. It was formed by sputtering. The pressure of the mixed gas atmosphere at the time of film formation is 0.3 Pa, and the thickness of the formed second piezoelectric layer 18 is 1.0 μm.

  About each piezoelectric thin film element of Examples 2-5 mentioned above, the presence or absence of the increase in a leak current when a 150-V alternating voltage was applied for 5 minutes, and the 50-V, 200-Hz alternating voltage which exhibits a sin waveform were continuously applied for 1000 hours. The durability performance (presence or absence of decrease in piezoelectric constant) was measured under the same conditions as in Example 1. The results are shown in Table 1. In Table 1, the measurement results in Example 1 are also shown.

As is clear from Table 1, by providing the second piezoelectric layer 18, it is possible to suppress the occurrence of leakage current in the piezoelectric thin film element and to improve the durability performance of the piezoelectric thin film element. The composition of the second piezoelectric layer 18 is such that the piezoelectric constant d ₃₁ of the second piezoelectric layer 18 is about 1/10 or more of the piezoelectric constant d ₃₁ of the first piezoelectric layer 14. By selecting this, the durability performance can be further enhanced.

(Example 6)
In this example, a predetermined number of piezoelectric thin film elements 20 were obtained using a 4-inch magnesium oxide single crystal substrate as the substrate 11 (hereinafter referred to as “MgO single crystal substrate 11”).

  First, while heating the MgO single crystal substrate 11 to 400 ° C. in an argon (Ar) gas atmosphere of 1 Pa, a titanium (Ti) target is sputtered at a high frequency power of 100 W for 1 minute to form titanium on the MgO single crystal substrate 11. An adhesion layer 12 having a thickness of 0.02 μm was formed.

  Next, while heating the MgO single crystal substrate 11 to 650 ° C. in an argon (Ar) gas atmosphere of 1 Pa, a platinum (Pt) target is sputtered for 12 minutes at a high frequency power of 180 W, and is made of platinum on the adhesion layer 12. A first electrode layer 13 having a thickness of 0.22 μm was formed. The first electrode layer 13 (platinum layer) is a polycrystalline body preferentially oriented in the (001) plane.

Next, while heating the MgO single crystal substrate 11 to 630 ° C. in a mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas (gas volume ratio Ar: O ₂ = 29: 1), zirconium ( A PZT sintered body target having an atomic ratio of Zr) to titanium (Ti) of Zr / Ti = 52/48 is sputtered with a high frequency power of 230 W for 1 hour to form a thickness of PZT on the first electrode layer 13. A first piezoelectric layer 14 having a thickness of 1.7 μm was formed. The pressure of the mixed gas atmosphere at the time of film formation was 0.3 Pa.

  The MgO single crystal substrate 11 on which the first piezoelectric layer 14 is formed is taken out, washed with dilute sulfuric acid after ultrasonic cleaning, and then washed with hydrogen peroxide solution three times to repeat the first operation. Foreign matters mixed in one piezoelectric layer 14 and a by-product layer made of lead oxide formed on the first piezoelectric layer 14 were removed.

Then, a second piezoelectric layer 18 made of PZT and having a thickness of 0.9 μm was formed by sputtering on the first piezoelectric layer 14 from which the foreign matter and by-product layers were removed. As a sputtering target at this time, a PZT sintered body having an atomic ratio of zirconium (Zr) to titanium (Ti) of Zr / Ti = 58/42 was used. While heating the MgO single crystal substrate 11 to 650 ° C. in a mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas (gas volume ratio Ar: O ₂ = 28.5: 1.5), the above The sputtering target was sputtered with a high frequency power of 210 W for 1 hour. The pressure of the mixed gas atmosphere at the time of film formation was 0.3 Pa.

  Thereafter, the MgO single crystal substrate 11 is diced to obtain a total of 50 intermediate products having a size in plan view of 15 mm × 2 mm, and each intermediate product is made of platinum on the second piezoelectric layer 18. A second electrode layer 19 having a thickness of 0.2 μm was formed by sputtering to obtain a total of 50 piezoelectric thin film elements 20. In forming the second electrode layer 19, a platinum (Pt) target is sputtered at a high frequency power of 200 W for 10 minutes while keeping the temperature of the silicon wafer (substrate 11) at room temperature in an argon (Ar) gas atmosphere of 1 Pa. did.

  The crystal structure and crystal orientation in each of the first piezoelectric layer 14 and the second piezoelectric layer 18 in each piezoelectric thin film element 20 thus obtained were examined by X-ray diffraction. The crystal structure and crystal orientation of the first piezoelectric layer 14 were measured before the second piezoelectric layer 18 was formed. As a result, both the first piezoelectric layer 14 and the second piezoelectric layer 18 had a tetragonal perovskite crystal structure and preferentially oriented in the (001) plane. The orientation ratio α (001) was 99.5% in any layer.

Further, the piezoelectric constant d ₃₁ of each piezoelectric thin film element 20 was measured. As a result, the piezoelectric constant d ₃₁ of each piezoelectric thin film element 20 was 145 pC / N on average, and the variation σ was 1.5%. Further, when the relative dielectric constant ε _r was measured, the relative dielectric constant ε _r was 330.

Separately, the silicon wafer (substrate 11) is diced in a state before the second piezoelectric layer 18 is formed, and a sample having a size in plan view of 15 mm × 2 mm is cut out. A second electrode layer made of platinum having a thickness of 0.2 μm was formed on the piezoelectric layer 14 by sputtering, and the piezoelectric constant d ₃₁ of the first piezoelectric layer 14 was measured. As a result, the piezoelectric constant d ₃₁ of the first piezoelectric layer 14 was an average of 152 pC / N, and the variation σ was 3.9%. Further, when the relative dielectric constant ε _r was measured, the relative dielectric constant ε _r was 370.

From the above results, when the piezoelectric constant d ₃₁ and the relative dielectric constant ε _r of the second piezoelectric layer 18 are calculated, the piezoelectric constant d ₃₁ and the relative dielectric constant ε _r of the second piezoelectric layer 18 are each 128 pC / N, 280.

  Next, when a DC voltage of 150 V was applied to the 50 piezoelectric thin film elements 20 for 5 minutes, no increase in leakage current was observed in all of the piezoelectric thin film elements 20, and no element breakdown occurred.

Furthermore, 30 piezoelectric thin film elements 20 having the same shape as the above-described piezoelectric thin film element 20 were produced again, and a 50 V, 200 Hz AC voltage having a sin waveform was continuously applied for 1000 hours to examine the durability performance. As a result, the piezoelectric constant d ₃₁ did not decrease in all 30 piezoelectric thin film elements 20.

  From these results, in the piezoelectric thin film element 20 of the present invention, even when each of the first piezoelectric layer and the second piezoelectric layer 18 is preferentially oriented in the (001) plane, the first piezoelectric body It can be seen that excellent reliability and durability performance can be obtained as in the case where each of the layer and the second piezoelectric layer 18 is preferentially oriented in the (111) plane.

(Example 7)
An example of the piezoelectric thin film element 72 (see FIG. 2) described in the second embodiment will be described in detail with appropriate reference numerals used in FIG. 2 or FIGS. 4 (a) to 4 (f).

  First, under the same conditions as in the first embodiment, an adhesion layer 62, a first electrode layer 63, and a first electrode are formed on a silicon wafer as a substrate 61 (hereinafter referred to as “silicon wafer (substrate 61)”). After the first piezoelectric layer 64 is laminated in this order, the first piezoelectric layer 64 is washed under the same conditions as in the first embodiment and mixed in the first piezoelectric layer 64. Foreign substances and a by-product layer made of lead oxide formed on the first piezoelectric layer 64 were removed. In addition, the thickness of the 1st piezoelectric material layer 64 in the location where the foreign material is not mixed is 2.5 micrometers.

  Next, under the same conditions as the molding of the second piezoelectric layer 18 in the first embodiment, the piezoelectric layer 68 (see FIG. 4C) that is the basis of the second piezoelectric layer 70 is changed to the first. Laminated on the piezoelectric layer 64.

  Next, a resist was applied on the piezoelectric layer 68 to form a resist layer 69 (see FIG. 4D) having a flat upper surface. The resist layer 69 and the piezoelectric layer 68 are etched back to fill the holes 67 of the first piezoelectric layer 64 so that only the holes 67 have the piezoelectric layer 68 (FIG. 4E, FIG. 4 (f)). At this time, the etching gas was selected so that the etching rate of the resist layer 69 and the etching rate of the piezoelectric layer 68 were substantially the same. The piezoelectric layer 68 left in the holes 67 is the second piezoelectric layer 70.

  Thereafter, the silicon wafer (substrate 61) is diced to obtain a total of 50 intermediate products having a size in plan view of 15 mm × 2 mm, and the first piezoelectric layer 64 and the second piezoelectric material in each of these intermediate products are obtained. A second electrode layer 71 was formed by sputtering under the same conditions as in Example 1 so as to cover the piezoelectric layer 70, and a total of 50 piezoelectric thin film elements 72 were obtained.

The piezoelectric constant d ₃₁ was measured for each piezoelectric thin film element 72 thus obtained. As a result, the piezoelectric constant d ₃₁ of each piezoelectric thin film element 72 was 172 pC / N on average, and the variation σ was 3.4%. Further, when the relative dielectric constant ε _r was measured, the relative dielectric constant ε _r was 870.

  Next, when a DC voltage of 150 V was applied to the 50 piezoelectric thin film elements 72 for 5 minutes, no increase in leakage current was observed in all the piezoelectric thin film elements 72, and no element breakdown occurred.

Further, 30 piezoelectric thin film elements 72 having the same shape as the above-described piezoelectric thin film element 72 were produced again, and a 50 V, 200 Hz AC voltage having a sin waveform was continuously applied for 1000 hours to examine durability performance. As a result, the piezoelectric constant d ₃₁ did not decrease in all 30 piezoelectric thin film elements 72.

  For these reasons, even when the second piezoelectric layer 70 is formed only in the holes 67 existing in the first piezoelectric layer 64, as in the first and sixth embodiments, It can be seen that a piezoelectric thin film element excellent in reliability and durability can be obtained.

  As described above, the piezoelectric thin film element of the present invention is suitable as a material for a piezoelectric thin film actuator in an inkjet head. Further, a thin film piezoelectric actuator in a head support mechanism in which a head for recording information on a hard disk device (used as a computer storage device or the like) or reading information from the hard disk device is provided on a substrate, That is, it is also suitable as a material for an actuator for displacing the head by deforming the substrate. Besides these, thin-film capacitors, charge storage capacitors for nonvolatile memory elements, various actuators, infrared sensors, ultrasonic sensors, pressure sensors, angular velocity sensors, acceleration sensors, flow sensors, shock sensors, piezoelectric transformers, piezoelectric ignition elements, piezoelectrics The present invention can also be applied to speakers, piezoelectric microphones, piezoelectric filters, piezoelectric pickups, tuning fork oscillators, delay lines, and the like.

Sectional drawing which shows roughly an example of the piezoelectric thin film element of this invention Sectional drawing which shows schematically the other example of the piezoelectric thin film element of this invention Process drawing which shows roughly an example of the manufacturing method of the piezoelectric thin film element of this invention Process drawing which shows the other example of the manufacturing method of the piezoelectric thin film element of this invention roughly The perspective view which shows an example of the inkjet head of this invention roughly FIG. 5 is a partial cross-sectional perspective view schematically showing the configuration of the main part of the inkjet head shown in FIG. Sectional drawing which shows schematically the structure of the actuator part in the inkjet head shown in FIG. FIG. 6 is a process diagram schematically showing a part of steps in an example of a method for manufacturing an ink jet head including the pressure chamber member, the actuator section, the ink flow path member, and the nozzle plate shown in FIG. Process diagram schematically showing another partial process in an example of a method of manufacturing an ink jet head including the pressure chamber member, the actuator section, the ink flow path member, and the nozzle plate shown in FIG. FIG. 6 is a process diagram schematically showing still another part of the process for producing an ink jet head including the pressure chamber member, the actuator section, the ink flow path member, and the nozzle plate shown in FIG. FIG. 6 is a process diagram schematically showing still another part of the process for producing an ink jet head including the pressure chamber member, the actuator section, the ink flow path member, and the nozzle plate shown in FIG. FIG. 6 is a process diagram schematically showing still another part of the process for producing an ink jet head including the pressure chamber member, the actuator section, the ink flow path member, and the nozzle plate shown in FIG. The top view which shows roughly an example of the board | substrate used for formation of the pressure chamber member shown in FIG. 6 or FIG. Sectional drawing which shows schematically the principal part in the other example of the inkjet head of this invention. Process drawing which shows roughly an example of the process at the time of manufacturing the inkjet head shown in FIG. 1 is a perspective view schematically showing an example of a main part of an ink jet recording apparatus of the present invention. Sectional drawing which shows roughly an example of the basic structure of a piezoelectric thin film element Sectional drawing which shows roughly an example of the basic structure of a piezoelectric thin film element

Explanation of symbols

11, 61, 120 Substrate 12, 62, 121, 404 Adhesion layer 13, 63, 407 First electrode layer 14, 64, 104 First piezoelectric layer 15, 65 Foreign matter 16, 66 By-product layer 17, 67 Hole 18, 70, 110, 408 Second piezoelectric layer 19, 71 Second electrode layer 20, 72 Piezoelectric thin film element 27 Inkjet recording device 28, 150, 420 Inkjet head 29 Recording medium 31 Carriage (relative movement means) )
32 rollers (relative movement means)
68 Piezoelectric layer 69 Resist 102, 402 Pressure chamber 103, 406 First electrode layer (individual electrode)
108,410 Nozzle hole 111,403 Diaphragm layer 112 Second electrode layer (common electrode)
401 Pressure chamber substrate 409 Second electrode layer (individual electrode)

Claims (7)

A substrate; a first electrode layer provided on the substrate; a piezoelectric layer provided on the first electrode layer; and a second electrode layer provided on the piezoelectric layer. A piezoelectric thin film element,
The piezoelectric layer is
A first piezoelectric layer made of an oxide having a perovskite crystal structure containing lead as a constituent element;
A second piezoelectric layer made of an electrically insulating oxide provided on the first piezoelectric layer and filling the voids in the first piezoelectric layer;
A piezoelectric thin film element comprising: 2. The piezoelectric thin film element according to claim 1, wherein there is no by-product layer around the pores. 3. The piezoelectric thin film element according to claim 1, wherein the first piezoelectric layer is a polycrystalline body preferentially oriented in a (111) plane or a (001) plane. 4. The piezoelectric thin film element according to claim 1, wherein the maximum thickness of the first piezoelectric layer is not less than 1 μm and not more than 10 μm. A substrate; a first electrode layer provided on the substrate; a piezoelectric layer provided on the first electrode layer; and a second electrode layer provided on the piezoelectric layer. A method for manufacturing a piezoelectric thin film element comprising:
A substrate in which a first piezoelectric layer made of an oxide having a perovskite crystal structure containing lead as a constituent element is formed on one side through the first electrode layer is washed, and the first piezoelectric layer A foreign matter removing step of removing foreign matter mixed in the first piezoelectric layer in the formation process and a by-product layer formed on the first piezoelectric layer;
A second piezoelectric layer made of an electrically insulating oxide is formed on the first piezoelectric layer that has been subjected to the foreign matter removing step so as to fill holes in the first piezoelectric layer. A piezoelectric layer forming step;
A method for manufacturing a piezoelectric thin film element, comprising: A piezoelectric thin film element in which a piezoelectric layer is formed on the first electrode layer, and a second electrode layer is formed on the piezoelectric layer, and the first electrode layer and the second electrode layer in the piezoelectric thin film element A diaphragm layer provided on one of the electrode layers, and a pressure chamber member having a pressure chamber that is bonded to a surface of the diaphragm layer opposite to the piezoelectric thin film element side and that stores ink. An inkjet head that discharges ink in the pressure chamber by displacing the diaphragm layer in the layer thickness direction by the piezoelectric effect of the piezoelectric thin film element,
The piezoelectric layer is
A first piezoelectric layer made of an oxide having a perovskite crystal structure containing lead as a constituent element;
A second piezoelectric layer made of an electrically insulating oxide provided on the first piezoelectric layer and filling the voids in the first piezoelectric layer;
An ink jet head comprising: An inkjet head; and a relative movement means for moving the inkjet head relative to the recording medium. When the inkjet head is moved relative to the recording medium by the relative movement means, An ink jet recording apparatus that performs recording by discharging ink to the recording medium,
An ink jet recording apparatus according to claim 6, wherein the ink jet head is an ink jet head according to claim 6.

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