JP2013171962A - Method for manufacturing piezoelectric element, method for manufacturing liquid injection head, and method for manufacturing liquid injection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element manufactured using a lead-free or low-lead piezoelectric material, a liquid injection head, and a liquid injection apparatus.SOLUTION: A method for manufacturing a piezoelectric element includes: a step S1 of forming a coating film 31 of a first precursor solution containing Bi, Ba, Fe, and Ti on an electrode 20 and then defatting the coating film 31 to form a first amorphous layer 32; a step S2 of forming a coating film 33 of a second precursor solution containing Bi, Ba, Fe, and Ti on the first amorphous layer 32 and then defatting the coating film 33 to form a second amorphous layer 34; a step S3 of firing the amorphous layers 32, 34 to form a buffer layer 35; and a step S4 of forming a layer containing Bi, Ba, Fe, and Ti on the buffer layer 35 to form a piezoelectric layer 30 having a perovskite oxide. The molar concentration of Bi in the second precursor solution is larger than the molar concentration of an element excluding Ti from B-site elements, and the molar concentration of Bi in the first precursor solution is smaller than the molar concentration of an element excluding Ti from B-site elements.

Description

  The present invention relates to a piezoelectric element manufacturing method, a liquid ejecting head manufacturing method, and a liquid ejecting apparatus manufacturing method.

Piezoelectric materials characterized by charging when crystals are distorted and generating distortion when placed in an electric field are widely used for actuators and sensors used in inkjet printers and the like. Currently, PZT (lead zirconate titanate, Pb (Zr _x , Ti _1-x ) O ₃ ) is used as a typical piezoelectric material. However, since PZT contains a lot of lead (Pb), research and development of lead-free piezoelectric materials that do not contain lead are widely performed from the viewpoint of environmental load.

For example, it is known that the BiFeO ₃ —BaTiO ₃ material disclosed in Patent Document 1 has good characteristics as a lead-free thin film piezoelectric material.

JP 2009-252789 A

However, when a piezoelectric element was fabricated using a BiFeO ₃ —BaTiO ₃ based piezoelectric material, it was found that cracks were likely to occur in the piezoelectric thin film compared to PZT, and it was difficult to put it to practical use at present. It has also been found that when the amount of Bi used is made larger than the stoichiometric ratio of BiFeO ₃ —BaTiO ₃ for the purpose of reducing the occurrence of cracks, the dielectric breakdown voltage of the piezoelectric element decreases. Such a problem exists not only in the liquid ejecting head but also in a piezoelectric element such as a piezoelectric actuator or a sensor.

  In view of the above, one of the objects of the present invention is to improve the performance of a piezoelectric element, a liquid ejecting head, and a liquid ejecting apparatus using a lead-free or low-lead piezoelectric material.

To achieve one of the above objects, the present invention is a method of manufacturing a piezoelectric element having a piezoelectric layer and an electrode,
A coating film of a first precursor solution containing at least Bi (bismuth), Ba (barium), Fe (iron) and Ti (titanium) is formed on the electrode, and the coating film is degreased to form a first amorphous layer. Forming, and
Forming a coating film of a second precursor solution containing at least Bi, Ba, Fe and Ti on the first amorphous layer, and degreasing the coating film to form a second amorphous layer;
Firing the first amorphous layer and the second amorphous layer to form a buffer layer;
Forming a layer containing at least Bi, Ba, Fe and Ti on the buffer layer to form the piezoelectric layer having a perovskite oxide, and
The molar concentration of Bi in the second precursor solution is larger than the molar concentration of an element obtained by removing Ti from a B-site element containing at least Fe and Ti to be the perovskite oxide,
The Bi concentration of the first precursor solution has an aspect that is smaller than the molar concentration of an element obtained by removing Ti from a B site element containing at least Fe and Ti that becomes the perovskite oxide.

According to another aspect of the invention, there is provided an aspect of a method for manufacturing a liquid jet head including the method for manufacturing the piezoelectric element.
Furthermore, the invention includes an aspect of a method of manufacturing a liquid ejecting apparatus including the method of manufacturing the liquid ejecting head.

  In the second precursor solution for forming the second amorphous layer on the first amorphous layer, the molar concentration of Bi is larger than the molar concentration of the element obtained by removing Ti from the B site element. On the other hand, in the first precursor solution for forming the first amorphous layer on the electrode, the molar concentration of Bi is made smaller than the molar concentration of the element obtained by removing Ti from the B site element. The piezoelectric element in which the buffer layer is formed under such conditions is a piezoelectric element formed by making the molar concentration of Bi larger than the molar concentration of the element obtained by removing Ti from the B site element in all the coating films of the precursor solution. It was found that the dielectric breakdown voltage was higher than that of the sample, and it had good voltage resistance.

Here, degreasing the coating film of the precursor solution includes degreasing after drying the coating film.
The piezoelectric layer may contain an additive metal other than Bi, Ba, Fe and Ti such as Mn (manganese) for the purpose of improving characteristics such as suppressing leakage current, and has a perovskite structure when the piezoelectric layer is formed. Impurities may be contained as much as possible.
The layer formed on the buffer layer includes a coating film of a second precursor solution, a coating film of a precursor solution different from the second precursor solution, a second amorphous layer, and an amorphous layer different from the second amorphous layer , Etc. are included. Therefore, in the step of forming the piezoelectric layer, the piezoelectric layer may be formed by forming a coating film of the second precursor solution on the buffer layer and degreasing and baking the coating film. Further, in the step of forming the piezoelectric layer, a coating film of a third precursor solution containing at least Bi, Ba, Fe and Ti is formed on the buffer layer, and the coating film is degreased and fired to form the piezoelectric layer. A body layer may be formed.

  From the viewpoint of obtaining a piezoelectric element having good withstand voltage, the first precursor solution contains Bi with respect to the molar concentration of the element obtained by removing Ti from the B site element containing at least Fe and Ti to be the perovskite oxide. The density ratio may be 0.70 to 0.85.

  When Mn is contained in at least one of the first precursor solution and the second precursor solution, an effect of increasing the insulation of the piezoelectric layer (improving leakage characteristics) can be obtained.

FIG. 6 is a cross-sectional view schematically illustrating the manufacturing process of the piezoelectric element 3. 4 is a flowchart schematically illustrating a manufacturing process of the piezoelectric element 3. FIG. 2 is an exploded perspective view for convenience illustrating the outline of the configuration of the recording head 1. FIGS. 3A to 3C are cross-sectional views for illustrating a manufacturing process of the recording head 1. FIGS. 3A to 3C are cross-sectional views for illustrating a manufacturing process of the recording head 1. 2 is a diagram illustrating an outline of a configuration of a recording apparatus 200. FIG. (A) is a figure which shows the molar concentration ratio of the metal of a precursor solution, (b) is a figure which shows the conditions of each layer of each example. (A) is a graph showing the measurement results of the IV characteristics of Examples 1 and 2 and Comparative Example 2, and (b) is a graph showing the measurement results of the IV characteristics of Examples 5 and 6. (A) is a graph showing the measurement results of the IV characteristics of Examples 3 and 4 and Comparative Example 2, and (b) is a graph showing the measurement results of the IV characteristics of Examples 7 and 8. (A)-(e) is a graph which shows the measurement result of the hysteresis characteristic of Examples 1-4 and the comparative example 2. FIG. (A)-(d) is a graph which shows the measurement result of the hysteresis characteristic of Examples 5-8. 3 is an image showing the surface of the piezoelectric thin film of Example 1. The image which shows the piezoelectric thin film surface of the comparative example 1. The image which shows the piezoelectric thin film surface of the comparative example 2.

  Embodiments of the present invention will be described below. Of course, the embodiments described below are merely illustrative of the present invention.

(1) Overview of manufacturing method of piezoelectric element, liquid ejecting head, and liquid ejecting apparatus:
First, with reference to FIGS. 1-6, the example of this manufacturing method is demonstrated. A recording head (liquid ejecting head) 1 illustrated in FIGS. 3 and 5C includes a piezoelectric element 3 having a piezoelectric layer (piezoelectric ceramics) 30 and electrodes (20, 40), and a piezoelectric element 3 communicated with a nozzle opening 71. A pressure generation chamber 12 in which a pressure change is generated by the element 3 is provided. Accordingly, the method for manufacturing the liquid ejecting head includes a step of forming a piezoelectric element and a step of forming a pressure generation chamber. The pressure generating chamber 12 is formed on the silicon substrate 15 of the flow path forming substrate 10. The nozzle opening 71 is formed in the nozzle plate 70. A lower electrode (first electrode) 20, a piezoelectric layer 30, and an upper electrode (second electrode) 40 are sequentially laminated on the elastic film (vibrating plate) 16 of the flow path forming substrate 10 to form the pressure generating chamber 12. A nozzle plate 70 is fixed to the silicon substrate 15.
In addition, the positional relationship demonstrated in this specification is only the illustration for demonstrating invention, and does not limit invention. Accordingly, the present invention also includes the second electrode disposed at a position other than the top of the first electrode, for example, below, left, right, and the like.

  The manufacturing method illustrated in FIG. 1 includes a first amorphous layer forming step S1, a second amorphous layer forming step S2, a buffer layer forming step S3, and a piezoelectric layer forming step S4. The first amorphous layer forming step S1 includes a first precursor coating step S11 and a first coating film degreasing step S12. The second amorphous layer forming step S2 includes a second precursor coating step S21 and a second coating film degreasing step S22. The piezoelectric layer forming step S4 includes a second precursor coating step S41, a second coating film degreasing step S42, and a second degreasing film baking step S43.

In the first precursor application step S11, a first precursor solution containing at least Bi, Ba, Fe, and Ti is applied in a film shape to the surface of the electrode (20). Here, in the first precursor solution, the molar concentration of Bi is made smaller than the molar concentration of an element (for example, Fe) obtained by removing Ti from a B site element containing at least Fe and Ti to be a perovskite oxide. . In the first precursor solution, the ratio of the molar concentration of Bi to the molar concentration of the element obtained by removing Ti from the B site element is R1 _{Bi / (B-Ti)} (0 <R1 _{Bi / (B-Ti)} <1) To do. In the first coating film degreasing step S12, the first coating film 31 on the electrode (20) is degreased to form the first amorphous layer 32. For example, when the first coating film 31 is heated at a degreasing temperature lower than the crystallization temperature of the perovskite oxide, the first coating film 31 is degreased to have a first oxide having an amorphous oxide containing at least Bi, Ba, Fe, and Ti. An amorphous layer 32 is formed. Degreasing includes drying. Of course, the first coating film 31 may be heated at the degreasing temperature after the drying process after the first coating film 31 is heated at the drying temperature, with the drying temperature <the degreasing temperature <the crystallization temperature. Further, after the first coating film is heated below the crystallization temperature to form an amorphous oxide, the first precursor solution is coated on the oxide, and the formed coating film is degreased to form an amorphous oxide. A stacked first amorphous layer 32 may be formed.

In the second precursor application step S <b> 21, a second precursor solution containing at least Bi, Ba, Fe, and Ti is applied in a film shape to the surface of the first amorphous layer 32. Here, in the second precursor solution, the molar concentration of Bi is larger than the molar concentration of an element (for example, Fe) obtained by removing Ti from a B-site element containing at least Fe and Ti to be a perovskite oxide. . When the ratio of the molar concentration of Bi to the molar concentration of the element obtained by removing Ti from the B site element in the second precursor solution is R2 _{Bi / (B-Ti)} (R2 _{Bi / (B-Ti)} > 1), R2 _{Bi / (B-Ti)} > R1 _{Bi / (B-Ti)} . In the second coating film degreasing step S22, the second coating film 33 on the first amorphous layer 32 is degreased to form the second amorphous layer. For example, when the second coating film 33 is heated at a degreasing temperature lower than the crystallization temperature of the perovskite oxide, the second coating film 33 is degreased to include a second oxide having an amorphous oxide containing at least Bi, Ba, Fe, and Ti. An amorphous layer 34 is formed. Of course, after the second coating film 33 is heated at the drying temperature, the second coating film 33 may be heated at the degreasing temperature after the drying process. Further, after the second coating film is heated below the crystallization temperature to form an amorphous oxide, the second precursor solution is applied onto the oxide, and the formed coating film is degreased to form an amorphous oxide. A stacked second amorphous layer 34 may be formed.

  In the buffer layer forming step S3, the first amorphous layer 32 and the second amorphous layer 34 are baked to form a buffer layer 35 having a perovskite oxide containing at least Bi, Ba, Fe, and Ti.

  In the piezoelectric layer forming step S4, a layer containing at least Bi, Ba, Fe and Ti is formed on the buffer layer 35 to form the piezoelectric layer 30 having a perovskite oxide. In the second precursor application step S41 shown in FIG. 1, the second precursor solution is applied to the surface of the buffer layer 35 in a film form. In the second coating film degreasing step S42, the second coating film 33 on the buffer layer 35 is degreased by heating, for example, at a degreasing temperature to form the second amorphous layer 34. After forming the amorphous oxide by heating the second coating film below the crystallization temperature, the second precursor solution was applied on the oxide, and the formed coating film was degreased to stack the amorphous oxide. The second amorphous layer 34 may be formed. In the second degreasing film firing step S43, the second amorphous layer 34 on the buffer layer 35 is fired to form the piezoelectric layer 30 having a perovskite oxide containing at least Bi, Ba, Fe, and Ti. After the second amorphous layer is crystallized, the second precursor solution is applied to the surface of the formed layer having the perovskite oxide, the formed coating film is degreased, and the coating and coating are performed as necessary. Degreasing may be repeated, and the formed degreasing film may be fired to form a piezoelectric layer in which layers having a perovskite oxide are stacked.

  FIG. 2 illustrates a manufacturing method in which a third amorphous layer 37 different from the second amorphous layer 34 is formed on the buffer layer 35. The piezoelectric layer forming step S4 of the manufacturing method includes a third precursor coating step S44, a third coating film degreasing step S45, and a third degreasing film baking step S46. In the third precursor application step S44, a third precursor solution containing at least Bi, Ba, Fe, and Ti is applied to the surface of the buffer layer 35 in a film shape. In the third coating film degreasing step S45, the third coating film 36 on the buffer layer 35 is degreased by heating at, for example, a degreasing temperature to form the third amorphous layer 37. After forming the amorphous oxide by heating the third coating film below the crystallization temperature, the third precursor solution was applied on the oxide, and the formed coating film was degreased to stack the amorphous oxide. A third amorphous layer 37 may be formed. In the third degreasing film firing step S46, the third amorphous layer 37 on the buffer layer 35 is fired to form the piezoelectric layer 30 having a perovskite oxide containing at least Bi, Ba, Fe, and Ti. In addition, after crystallizing the third amorphous layer, the third precursor solution is applied to the surface of the formed layer having the perovskite oxide, the formed coating film is degreased, and the coating and coating are performed as necessary. Degreasing may be repeated, and the formed degreasing film may be fired to form a piezoelectric layer in which layers having a perovskite oxide are stacked. Further, one or more kinds of amorphous layers different from the above-described amorphous layers (32, 34, 37) may be formed to form the piezoelectric layer.

  The perovskite oxide obtained in the piezoelectric layer forming step S4 illustrated in FIGS. 1 and 2 contains at least Bi, Ba, Fe and Ti, and has a small molar ratio with Bi, Ba, Fe and Ti as main components. Another metal (eg, Mn) may be included. Here, the main component is one or more target components whose total molar ratio is larger than the molar ratio of the other contained components. The piezoelectric layer 30 may contain a substance (for example, a metal oxide) other than the perovskite oxide having a perovskite oxide as a main component.

After the formation of the piezoelectric layer, there is a second electrode forming step of forming the second electrode (40) on the surface of the piezoelectric layer 30 as illustrated in FIG. 4B.
As a constituent metal of the electrodes (20, 40), one or more of Pt (platinum), Au (gold), Ir (iridium), Ti, and the like can be used. The constituent metal may be in the state of a compound such as an oxide, in an uncombined state, in an alloy state, or in a single metal state. Metals may be included. The oxide includes a conductive oxide such as LaNiO _y (lanthanum nickelate). Although the thickness of an electrode (20, 40) is not specifically limited, For example, it can be set as about 10-500 nm.

  In the precursor solution including the first precursor solution, the second precursor solution, and the third precursor solution, another metal (for example, 0.1%) having Bi, Ba, Fe, and Ti as main components and having a small molar ratio is used. About 10% to 10% Mn). As the metal salt contained in the precursor solution, an organic acid salt such as 2-ethylhexanoate or acetate can be used. The precursor solution includes a solution in which the metal salt is dissolved in a solvent, a sol in which the metal salt is dispersed in a dispersion medium, and the like. As the solvent and the dispersion medium, those containing an organic solvent such as octane, xylene, or a combination thereof can be used. The precursor solution can be applied by a liquid phase method such as a spin coating method, a dip coating method, or an ink jet method. The thickness of the formed coating film (31, 33, 36) is not particularly limited, but can be, for example, about 0.1 μm.

  Various devices can be used for the heating described above. When an infrared lamp annealing device that can use the RTA (Rapid Thermal Annealing) method is used for heating at a temperature higher than the crystallization temperature, the buffer layer 35 and the piezoelectric layer are used. 30 can be formed satisfactorily.

  The crystallization temperature of the piezoelectric layer 30 having a perovskite oxide containing at least Bi, Ba, Fe, and Ti is, for example, higher than 550 ° C. and lower than 900 ° C.

The metal contained in the precursor of the piezoelectric layer such as the precursor solution is disposed at a site corresponding to the atomic radius in the perovskite structure. The resulting perovskite oxide contains at least Bi and Ba at the A site and at least Fe and Ti at the B site. Such a perovskite oxide includes a lead-free perovskite oxide having a composition represented by the following general formula.
(Bi, Ba) (Fe, Ti) O _z (1)
(Bi, Ba, MA) (Fe, Ti) O _z (2)
(Bi, Ba) (Fe, Ti, MB) O _z (3)
(Bi, Ba, MA) (Fe, Ti, MB) O _z (4)
Here, MA is one or more metal elements excluding Bi, Ba and Pb, and MB is one or more metal elements excluding Fe, Ti and Pb. As for z, 3 is a standard (stoichiometric ratio), but may deviate from 3 within a range where a perovskite structure can be taken. The ratio of the A site element to the B site element is 1: 1 (the stoichiometric ratio), but may be deviated from 1: 1 within a range where a perovskite structure can be taken. In the precursor used in this production method, the ratio of the A site element and the B site element is shifted from 1: 1 in at least one of the first precursor solution and the second precursor solution.

The molar ratio of Bi to the total molar number of Bi, Ba (, MA) can be, for example, about 40 to 99.9%. Note that the elements in parentheses do not have to be added. The molar ratio of Ba to the total molar number of Bi, Ba (, MA) can be, for example, about 0.1 to 50%. The molar ratio of MA to the total molar number of Bi, Ba (, MA) can be, for example, about 0.1 to 33%.
The molar ratio of Fe to the total molar number of Fe, Ti (, MB) can be, for example, about 50 to 99.9%. The molar ratio of Ti to the total molar number of Fe, Ti (, MB) can be, for example, about 0.1 to 50%. The ratio of the number of moles of MB to the total number of moles of Fe, Ti (, MB) can be, for example, about 0.1 to 33%.

  MB elements that can be added to the precursor include Mn and the like. The molar ratio of Mn in the B site constituent metal can be, for example, about 0.1 to 10%, with the total molar ratio of the B site constituent metal being 100%. When Mn is added, an effect of increasing the insulating property of the piezoelectric layer (improving leakage characteristics) is expected, but a piezoelectric element having piezoelectric performance can be formed without Mn.

In the second precursor solution, the ratio of the molar concentration of Bi to the molar concentration of element Fe (, MB) obtained by removing Ti from the B site element including Fe, Ti (, MB) in the second precursor solution R2 _{Bi / (B -Ti) is set} to R2 _{Bi / (B-Ti)} > 1. For example, assuming a BiFeO _z —BaTiO _z eutectic as the perovskite oxide, the ratio R 2 _{Bi / (B—Ti)} is the molar concentration ratio of Bi to the molar concentration of Fe. Further, Bi (Fe, Mn) As perovskite oxide if O _z assume -BaTiO _z eutectic ratio R2 _{Bi / (B-Ti)} is, Fe, the molar concentration ratio of Bi to the molar concentration sum of Mn It is. Focusing on the second coating film 33, the ratio R2 _{Bi / (B-Ti)} is substantially the ratio of the number of moles of Bi to the number of moles of the element Fe (, MB) obtained by removing Ti from the B site element. .
R2 _{Bi / (B-Ti)} > 1, that is, the Bi concentration is made larger than the molar concentration of the element Fe (, MB) obtained by removing Ti from the B site element, thereby reducing cracks in the piezoelectric layer. be able to.

Further, in the second precursor solution, the ratio R2 _{A / B} of the molar concentration of the A site element containing Bi, Ba (, MA) to the molar concentration of the B site element containing Fe, Ti (, MB) is R2 _{A / B} > 1 may be set. Further, when the perovskite oxide is represented by the general formula BiMO _z -BaTiO _z (M is one or more metal elements excluding Bi, Ba, Ti, and Pb and contains at least Fe), the mole of the element M The ratio R2 _{Bi / M} of _Bi molar concentration to concentration may be set to R2 _{Bi / M} > 1.
As described above, cracks in the piezoelectric layer can be reduced.

On the other hand, in the first precursor solution, the ratio R1 _{Bi / (B-Ti} ) of the molar concentration of Bi to the molar concentration of the element Fe (, MB) obtained by removing Ti from the B site element containing Fe, Ti (, MB). ₎ 0 <R1 _{Bi / (B-Ti)} <1. Focusing on the first coating film 31, the ratio R1 _{Bi / (B-Ti)} is substantially the ratio of the number of moles of Bi to the number of moles of the element Fe (, MB) obtained by removing Ti from the B site element. .
R1 _{Bi / (B-Ti)} <1, that is, by making the molar concentration of Bi smaller than the molar concentration of the element Fe (, MB) obtained by removing Ti from the B site element, the dielectric breakdown voltage of the piezoelectric element is increased. In addition, the voltage resistance can be improved. If the amount of Bi used over the entire piezoelectric layer exceeds the stoichiometric ratio of the perovskite oxide, it is presumed that crystals of the perovskite oxide grow large, while leak currents are likely to occur between large crystals. . The dielectric breakdown voltage of the piezoelectric element is increased by inserting the Bi amorphous first amorphous layer under the Bi excessive second amorphous layer because the crystallized layer formed from the first amorphous layer has a large intercrystalline structure. This is presumed to serve to block the leakage current.

In the first precursor solution, the ratio R1 _{A / B} of the molar concentration of the A site element including Bi, Ba (, MA) to the molar concentration of the B site element including Fe, Ti (, MB) is 0 <R1. _{A / B} <1 may be set. Further, when the perovskite oxide is represented by the general formula BiMO _z -BaTiO _z (M is one or more metal elements excluding Bi, Ba, Ti, and Pb and contains at least Fe), the mole of the element M The ratio R1 _{Bi / M} of the molar concentration of Bi to the concentration may be 0 <R1 _{Bi / M} <1.
As described above, the dielectric breakdown voltage of the piezoelectric element can be increased and the voltage resistance can be improved.

The ratio R1 _{Bi / (B-Ti)} is preferably 0.70 or more and 0.85 or less from the viewpoint of obtaining a piezoelectric element with good voltage resistance.

In the third precursor solution, the ratio R3 _{Bi / (B-Ti)} of the molar concentration of Bi to the molar concentration of the element Fe (, MB) obtained by removing Ti from the B site element containing Fe, Ti (, MB ₎ is Although not particularly limited, for example, it can be about 0.9 to R2 _{Bi / (B-Ti)} .

The Bi molar ratio R1 _Bi (0 <R1 _Bi <1) in the metal of the first precursor solution is higher than the Bi molar ratio R2 _Bi (0 <R2 _Bi <1) in the metal of the second precursor solution. small. Here, the Bi molar ratio in the metal of the precursor solution is represented by the ratio of the molar concentration of Bi to the total molar concentration of Bi, Ba (, MA), Fe, Ti (, MB) contained in the precursor solution. The
The Bi molar ratio R1 _{Bi / A} (0 <R1 _{Bi / A} <1) in the A site element of the first precursor solution is equal to the Bi molar ratio R2 _{Bi / A in} the A site element of the second precursor solution. It is smaller than (0 <R2 _{Bi / A} <1). Here, the Bi molar ratio in the A-site element of the precursor solution is represented by the ratio of the molar concentration of Bi to the total molar concentration of Bi and Ba (, MA) contained in the precursor solution.

  Although the number of layers of the 1st coating film 31 of a 1st precursor solution is not specifically limited, For example, it can be set as about 1-3 layers. The thickness of the first amorphous layer 32 can be set to about 0.1 to 0.3 μm, for example. The number of layers of the second coating film 33 of the second precursor solution is not particularly limited, but can be, for example, about 1 to 3 layers. The thickness of the second amorphous layer 34 can be set to about 0.1 to 0.3 μm, for example. The ratio of the number of layers and the thickness of the buffer layer 35 to the entire piezoelectric layer 30 can be, for example, about 0.05 to 0.5.

  As illustrated in FIG. 13 as a dark field 100-fold image of the surface of the piezoelectric thin film of Comparative Example 1, large cracks are formed on the surface of the piezoelectric layer formed with the amount of Bi used as a stoichiometric ratio over the entire piezoelectric layer. It can be seen. As illustrated in FIG. 14 as a dark field 100 times image of the surface of the piezoelectric thin film of Comparative Example 2, the surface of the piezoelectric layer formed with the amount of Bi used exceeding the stoichiometric ratio over the entire piezoelectric layer is No cracks of a size that can be confirmed with a dark field of 100 times are observed. As illustrated in FIG. 12 as a dark field 100-fold image on the surface of the piezoelectric thin film of Example 1, the piezoelectric layer formed by placing the Bi amorphous first amorphous layer under the Bi excessive second amorphous layer. No cracks of a size that can be confirmed with a dark field of 100 times are observed on the surface.

On the other hand, as illustrated in FIGS. 8A and 8B and FIGS. 9A and 9B, the I (current density) -V (applied voltage) curves of Examples 1 to 8 and Comparative Example 2 are illustrated. A piezoelectric element formed by inserting a Bi-deficient first amorphous layer under a Bi-excessed second amorphous layer has a sharper leakage than a piezoelectric element formed without a Bi-deficient first amorphous layer. The voltage at which current is generated increases. Therefore, this manufacturing method can increase the dielectric breakdown voltage of the piezoelectric element and improve the voltage resistance while reducing cracks that are likely to occur in the piezoelectric layer of BiFeO ₃ —BaTiO ₃ -based material. By reducing cracks in the piezoelectric layer and increasing the dielectric breakdown voltage of the piezoelectric element, the performance of the piezoelectric element using a lead-free or low-lead piezoelectric material can be improved.

(2) Example of manufacturing method of piezoelectric element and liquid jet head:
FIG. 3 is an exploded perspective view in which an ink jet recording head 1 which is an example of a liquid ejecting head is disassembled for convenience. 4 and 5 are cross-sectional views for illustrating the method of manufacturing the recording head, and are vertical cross-sectional views along the longitudinal direction D2 of the pressure generating chamber 12. FIG. The layers constituting the recording head 1 may be bonded and laminated, or may be integrally formed by modifying the surface of a material that is not separated.

The flow path forming substrate 10 can be formed from a silicon single crystal substrate or the like. The elastic film 16 can be formed integrally with the silicon substrate 15 by, for example, thermally oxidizing one surface of the relatively thick and rigid silicon substrate 15 having a film thickness of about 500 to 800 μm in a diffusion furnace at about 1100 ° C. It can be made of silicon dioxide (SiO ₂ ) or the like. The thickness of the elastic film 16 is not particularly limited as long as it exhibits elasticity, but can be, for example, about 0.5 to 2 μm.

Next, as shown in FIG. 4A, a lower electrode (first electrode) 20 is formed on the elastic film 16 by sputtering or the like. In the example shown in FIG. 4B, patterning is performed after the lower electrode 20 is formed. Although the thickness of the lower electrode 20 is not specifically limited, For example, it can be set as about 50-500 nm. As the adhesion layer or the diffusion prevention layer, a layer such as a titanium oxide (TiO _x ), a titanium nitride aluminum (TiAlN) film, an Ir film, an iridium oxide (IrO) film, a zirconium oxide (ZrO ₂ ) film or the like is used as the elastic film 16. After forming the upper electrode, the lower electrode 20 may be formed on the layer.

Next, as shown in FIG. 1, the first precursor solution containing at least Bi, Ba, Fe, and Ti described above is applied to the surface of the lower electrode 20 (first precursor application step S11). The molar concentration ratio of the metal in the precursor solution can be determined according to the composition of the perovskite oxide to be formed, but the amount of Bi used is less than the stoichiometric ratio.
Next, the first coating film 31 is heated at a degreasing temperature lower than the crystallization temperature to form a thin first amorphous layer 32 (first coating film degreasing step S12). Preferably, for example, it is heated to about 140 to 190 ° C. and dried (drying step), and then degreased by heating to about 300 to 500 ° C. (degreasing step).

Next, the above-described second precursor solution containing at least Bi, Ba, Fe and Ti is applied to the surface of the first amorphous layer 32 (second precursor application step S21). The molar concentration ratio of the metal in the precursor solution can be determined according to the composition of the perovskite oxide to be formed, but the amount of Bi used is larger than the stoichiometric ratio.
Next, the second coating film 33 is heated at a degreasing temperature lower than the crystallization temperature to form a thin second amorphous layer 34 (second coating film degreasing step S22). Preferably, for example, it is heated to about 140 to 190 ° C. and dried (drying step), and then degreased by heating to about 300 to 500 ° C. (degreasing step).

  Next, the first amorphous layer 32 and the second amorphous layer 34 are heated at a temperature equal to or higher than the crystallization temperature to form a thin buffer layer 35 containing a perovskite oxide (buffer layer forming step S3). For example, crystallization is performed by heating to about 550 to 850 ° C. (firing step).

  In the case of the manufacturing method shown in FIG. 1, the above-mentioned second precursor solution is applied to the surface of the buffer layer 35 (second precursor application step S41). Next, the second coating film 33 on the buffer layer 35 is heated below the crystallization temperature to form a thin second amorphous layer 34 (second coating film degreasing step S42). Preferably, drying is performed by heating at a drying temperature, and degreasing is performed by heating at a degreasing temperature. Thereafter, the second amorphous layer 34 on the buffer layer 35 is fired at a firing temperature equal to or higher than the crystallization temperature to form a thin film piezoelectric layer 30 containing a perovskite oxide (second degreasing film firing step S43). Due to the firing, diffusion is seen in Bi of the piezoelectric layer.

  In the case of the manufacturing method shown in FIG. 2, the above-described third precursor solution is applied to the surface of the buffer layer 35 (third precursor application step S44). Next, the third coating film 36 on the buffer layer 35 is heated below the crystallization temperature to form a thin third amorphous layer 37 (third coating film degreasing step S45). Preferably, drying is performed by heating at a drying temperature, and degreasing is performed by heating at a degreasing temperature. Thereafter, the third amorphous layer 37 on the buffer layer 35 is fired at the firing temperature to form the piezoelectric layer 30 (third degreasing film firing step S46). Due to the firing, diffusion is seen in Bi of the piezoelectric layer.

In addition, in order to thicken the piezoelectric layer 30, the combination of the coating process, the drying process, the degreasing process, and the baking process may be performed a plurality of times. In order to reduce the firing process, the firing process may be performed after the combination of the coating process, the drying process, and the degreasing process is performed a plurality of times. Further, a combination of these steps may be performed a plurality of times.
The thickness of the formed piezoelectric layer 30 is not particularly limited as long as it exhibits an electromechanical conversion effect, and can be, for example, about 0.2 to 2 μm. Preferably, the thickness of the piezoelectric layer 30 is suppressed to such an extent that cracks do not occur in the manufacturing process, and the piezoelectric layer 30 is made thick enough to exhibit sufficient displacement characteristics.

  As a heating apparatus for performing the above-described drying process and degreasing process, a hot plate, an infrared lamp annealing apparatus for heating by irradiation with an infrared lamp, or the like can be used. An infrared lamp annealing device or the like can be used as a heating device for performing the firing step. Preferably, the temperature rising rate may be made relatively fast by using an RTA (Rapid Thermal Annealing) method or the like.

After the piezoelectric layer 30 is formed, as shown in FIG. 4B, the upper electrode 40 is formed on the piezoelectric layer 30 by sputtering or the like. Although the thickness of the upper electrode 40 is not specifically limited, For example, it can be set as about 50-150 nm. In the example shown in FIG. 4C, after the upper electrode 40 is formed, the piezoelectric layer 30 and the upper electrode 40 are patterned in regions facing the pressure generation chambers 12 to form the piezoelectric element 3. .
In general, one of the electrodes of the piezoelectric element 3 is used as a common electrode, and the other electrode and the piezoelectric layer 30 are patterned for each pressure generating chamber 12 to configure the piezoelectric element 3. The piezoelectric element 3 shown in FIGS. 3 and 5 uses the lower electrode 20 as a common electrode and the upper electrode 40 as an individual electrode.

  Thus, the piezoelectric element 3 having the piezoelectric layer 30 and the electrodes (20, 40) is formed, and the piezoelectric actuator 2 including the piezoelectric element 3 and the elastic film 16 is formed.

  Next, as shown in FIG. 4C, lead electrodes 45 are formed. For example, after forming a gold layer over the entire surface of the flow path forming substrate 10, the lead electrode 45 is provided by patterning for each piezoelectric element 3 through a mask pattern made of a resist or the like. Connected to each upper electrode 40 shown in FIG. 3 is a lead electrode 45 extending on the elastic film 16 from the vicinity of the end on the ink supply path 14 side.

  The lower electrode 20, the upper electrode 40, and the lead electrode 45 can be formed by a sputtering method such as a DC (direct current) magnetron sputtering method. The thickness of each layer can be adjusted by changing the voltage applied to the sputtering apparatus and the sputtering processing time.

  Next, as illustrated in FIG. 5A, the protective substrate 50 on which the piezoelectric element holding portion 52 and the like are formed in advance is bonded onto the flow path forming substrate 10 with an adhesive, for example. As the protective substrate 50, for example, a silicon single crystal substrate, glass, a ceramic material, or the like can be used. Although the thickness of the protective substrate 50 is not specifically limited, For example, it can be about 300-500 micrometers. The reservoir portion 51 penetrating in the thickness direction of the protective substrate 50 and the communication portion 13 constitute a reservoir 9 serving as a common ink chamber (liquid chamber). The piezoelectric element holding portion 52 provided in the region facing the piezoelectric element 3 has a space that does not hinder the movement of the piezoelectric element 3. In the through hole 53 of the protective substrate 50, the vicinity of the end portion of the lead electrode 45 drawn from each piezoelectric element 3 is exposed.

Next, after the silicon substrate 15 is polished to a certain thickness, the silicon substrate 15 is further etched to a predetermined thickness (for example, about 60 to 80 μm) by wet etching with hydrofluoric acid. Next, as shown in FIG. 5B, a mask film 17 is newly formed on the silicon substrate 15 and patterned into a predetermined shape. Silicon nitride (SiN) or the like can be used for the mask film 17. Next, the silicon substrate 15 is anisotropically etched (wet etching) using an alkaline solution such as KOH. As a result, a plurality of liquid flow paths including the pressure generating chambers 12 defined by the plurality of partition walls 11 and the narrow ink supply paths 14, and a communication portion 13 that is a common liquid flow path connected to each ink supply path 14. And are formed. The liquid flow paths (12, 14) are arranged in the width direction D1, which is the short direction of the pressure generating chamber 12.
The pressure generation chamber 12 may be formed before the piezoelectric element 3 is formed.

  Next, unnecessary portions at the peripheral portions of the flow path forming substrate 10 and the protective substrate 50 are removed by cutting, for example, by dicing. Next, as shown in FIG. 5C, the nozzle plate 70 is bonded to the surface of the silicon substrate 15 opposite to the protective substrate 50. The nozzle plate 70 can be made of glass ceramics, silicon single crystal substrate, stainless steel, or the like, and is fixed to the opening surface side of the flow path forming substrate 10. For this fixation, an adhesive, a heat welding film, or the like can be used. The nozzle plate 70 is formed with nozzle openings 71 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14. Therefore, the pressure generation chamber 12 communicates with the nozzle opening 71 that discharges the liquid.

  Next, the compliance substrate 60 having the sealing film 61 and the fixing plate 62 is bonded onto the protective substrate 50 and divided into a predetermined chip size. The sealing film 61 is made of, for example, a material having low rigidity such as a polyphenylene sulfide (PPS) film having a thickness of about 4 to 8 μm, and the like, and seals one surface of the reservoir unit 51. The fixing plate 62 is made of a hard material such as a metal such as stainless steel (SUS) having a thickness of about 20 to 40 μm, for example, and an area facing the reservoir 9 is an opening 63.

A driving circuit 65 for driving the piezoelectric elements 3 arranged in parallel is fixed on the protective substrate 50. For the drive circuit 65, a circuit board, a semiconductor integrated circuit (IC), or the like can be used. The drive circuit 65 and the lead electrode 45 are electrically connected via the connection wiring 66. As the connection wiring 66, a conductive wire such as a bonding wire can be used.
Thus, the recording head 1 is manufactured.

The recording head 1 takes in ink from an ink introduction port connected to an external ink supply unit (not shown), and fills the interior from the reservoir 9 to the nozzle opening 71 with ink. When a voltage is applied between the lower electrode 20 and the upper electrode 40 for each pressure generation chamber 12 in accordance with a recording signal from the drive circuit 65, the deformation of the piezoelectric layer 30, the lower electrode 20, and the elastic film 16 causes deformation from the nozzle opening 71. Ink droplets are ejected.
The recording head may have a common lower electrode structure in which the lower electrode is a common electrode and the upper electrode is an individual electrode, or a common upper electrode structure in which the upper electrode is a common electrode and the lower electrode is an individual electrode. Alternatively, the lower electrode and the upper electrode may be a common electrode, and an individual electrode may be provided between the two electrodes.

(3) Liquid ejecting apparatus:
FIG. 6 shows an appearance of a recording apparatus (liquid ejecting apparatus) 200 having the recording head 1 described above. When the recording head 1 is incorporated in the recording head units 211 and 212, the recording apparatus 200 can be manufactured. In the recording apparatus 200 shown in FIG. 6, the recording head 1 is provided in each of the recording head units 211 and 212, and ink cartridges 221 and 222 as external ink supply means are detachably provided. A carriage 203 on which the recording head units 211 and 212 are mounted is provided so as to be able to reciprocate along a carriage shaft 205 attached to the apparatus main body 204. When the driving force of the driving motor 206 is transmitted to the carriage 203 via a plurality of gears and a timing belt 207 (not shown), the carriage 203 moves along the carriage shaft 205. A recording sheet 290 fed by a sheet feeding roller (not shown) is conveyed onto the platen 208 and printed by ink supplied from the ink cartridges 221 and 222 and ejected from the recording head 1.

(4) Example:
Hereinafter, although an example is shown, the present invention is not limited by the following examples.

[Preparation of lower electrode forming substrate]
A substrate having each layer of Pt (platinum) / TiO _x (titanium oxide) / SiO ₂ / Si was produced as follows.
First, a (100) -oriented single crystal silicon (Si) substrate was heated in a diffusion furnace to thermally oxidize the surface, and a silicon oxide (SiO ₂ ) film having a thickness of 1200 nm was formed on the Si substrate surface. Next, a titanium (Ti) film having a thickness of 40 nm was formed on the SiO ₂ film by RF (high frequency) magnetron sputtering and thermally oxidized to form a titanium oxide (TiO _x ) thin film. Furthermore, a 100 nm-thick platinum thin film (lower electrode 20) oriented in the (111) plane was formed on the titanium oxide film by RF magnetron sputtering.

[Precursor solution preparation]
2-ethylhexanoate is used as a precursor material of each metal element of Bi, Ba, Fe, Ti, and Mn, and “R”, “+15”, “+8”, “−15” with the composition shown in FIG. ”And“ −30 ”precursor solutions were prepared. “R” represents the molar concentration ratio of each metal in accordance with the stoichiometric ratio of (Bi, Ba) (Fe, Ti, Mn) O _z which is the target of the perovskite oxide, and Bi: Ba: Fe: Ti: Mn = 75: 25: 71.25: 25: 3.75. “+15” and “+8” represent the molar concentration ratio of each metal in which the molar concentration ratio of Bi is increased by + 15% and + 8% relative to “R”. “−15” and “−30” represent the molar concentration ratio of each metal in which the molar concentration ratio of Bi is 15% and 30% shorter than “R”.
N-octane was used as the solvent.

[Production of Piezoelectric Layer Forming Substrates of Examples and Comparative Examples]
FIG. 7 (b) shows Examples 1 to 7 in which any of the above-described “R”, “+15”, “+8”, “−15”, and “−30” is used as the precursor solution of each layer of the spin coating process. 8 and the layer structure of Comparative Examples 1 and 2 are shown. In FIG. 7 (b), the “layer” column indicates the layer number counted from the lower electrode side, and “degreasing” in the “treatment” column indicates that the drying step and the degreasing step were performed after the precursor solution was applied. “Baking” in the “treatment” column indicates that the drying process, the degreasing process, and the baking process were performed after the precursor solution was applied. In any coating process, the precursor solution was dropped onto the substrate, and the coating film was formed by a spin coating method in which the substrate was rotated and the maximum rotation speed of 3000 rpm was continued for 30 seconds. In each of the drying steps, the substrate was placed on a hot plate, heated to 180 ° C., and dried for 2 minutes. In the degreasing process, all were degreased by heating to 350 ° C. for 2 minutes. In the firing step, firing was performed for 5 minutes by heating to 800 ° C. at a temperature rising rate of 15 ° C./second in an oxygen atmosphere by an RTA (Rapid Thermal Annealing) apparatus.

For each of the examples and comparative examples, first, the first layer precursor solution is dropped onto the lower electrode of the lower electrode forming substrate to form a coating film (coating step), and then the first layer is passed through a drying step and a degreasing step. An amorphous layer of eyes was formed. Next, a second precursor solution was dropped onto the first amorphous layer to form a coating film, and a second amorphous layer was formed through a drying step and a degreasing step. Next, the third precursor solution was dropped onto the second amorphous layer to form a coating film, and a crystallization layer was formed through a drying step, a degreasing step, and a firing step. The crystallization layers of Examples 1 to 8 correspond to the buffer layer 35.
Hereinafter, by using the precursor solution shown in FIG. 7 (b), the combination of “coating step, drying step and degreasing step three times” and “firing step” is repeated three more times to obtain the number of layers in the spin coating process. A piezoelectric thin film (piezoelectric layer) having a thickness of 12 was formed on the lower electrode.

For example, in Example 1, the combination of “-30 first precursor solution coating step, drying step and degreasing step once” and “+15 second precursor solution coating step, drying step and degreasing step combination” After forming the buffer layer by performing “twice” and “firing process”, the combination of “+15 second precursor solution coating process, drying process and degreasing process three times” and “firing process” three times It is repeating. The ratio of the number of first amorphous layers to the entire piezoelectric thin film is 1/12 = 0.083, and the ratio of the number of second amorphous layers of the buffer layer to the entire piezoelectric thin film is 2/12 = 0.17.
In Example 3, “-30 combination of the first precursor solution coating step, drying step and degreasing step once” and “+15 second precursor solution coating step, combination of drying step and degreasing step twice” ”And“ baking step ”to form a buffer layer, and then the combination of“ the third combination of the R precursor solution, the drying step and the degreasing step 3 times ”and the“ baking step ”is repeated three times. Yes. The ratio of the number of first amorphous layers to the entire piezoelectric thin film is 1/12 = 0.083, and the ratio of the number of second amorphous layers of the buffer layer to the entire piezoelectric thin film is 2/12 = 0.17.
In Examples 5 and 7, the second precursor solution of Examples 1 and 3 is replaced from “+15” to “+8”.
Examples 2, 4, 6, and 8 replace the first precursor solution of Examples 1, 3, 5, and 7 from “−30” to “−15”.

In Comparative Example 1, the combination of “the combination of the R precursor solution coating process, the drying process, and the degreasing process 3 times” and the “baking process” is repeated 4 times. In Comparative Example 2, the combination of “+15 precursor solution coating process, drying process and degreasing process 3 times” and “baking process” is repeated 4 times.
The thickness of the obtained piezoelectric thin film was almost the same as 937 to 1030 nm.

[Evaluation of piezoelectric thin film]
The surface of each piezoelectric thin film sample was confirmed with a metal microscope. As an example of the results, FIG. 12 shows a dark field 100 × image of the piezoelectric thin film surface of Example 1, FIG. 13 shows a dark field 100 × image of the piezoelectric thin film surface of Comparative Example 1, and FIG. A dark field 100 × image is shown. As shown in FIG. 13, large cracks are observed on the surface of the piezoelectric thin film sample of Comparative Example 1 in which all layers are formed of “R”. As shown in FIG. 14, no crack of a size that can be confirmed with a dark field of 100 times is observed on the surface of the piezoelectric thin film sample of Comparative Example 2 in which all layers are formed with Bi + “+ 15”. As shown in FIG. 12, the dark field also appears on the surface of the piezoelectric thin film sample of Example 1 in which the first amorphous layer of “−30” Bi-deficient state is formed under the Bi-rich “+15” second amorphous layer. There is no crack of a size that can be confirmed at 100 times.
Therefore, it can be seen that the presence of the Bi-excess amorphous layer reduces cracks in the piezoelectric layer.

  When an X-ray diffraction chart was obtained for each piezoelectric thin film sample by the X-ray diffraction wide angle method (XRD), it was found that all were preferentially oriented in the (110) plane.

[Evaluation of piezoelectric element]
For each piezoelectric thin film sample, a platinum thin film (upper electrode 40) having a thickness of 100 nm was formed on the piezoelectric thin film of the piezoelectric layer forming substrate by sputtering, and then fired at 750 ° C. for 5 minutes in an oxygen atmosphere using an RTA apparatus. A piezoelectric element sample was formed. For each piezoelectric element, a voltage was applied between the platinum electrodes, and the IV characteristics, that is, the current density (A / cm ² ) relative to the applied voltage (V) was measured.

FIG. 8A shows the measurement results of the IV characteristics of Examples 1 and 2 and Comparative Example 2, and FIG. 8B shows the measurement results of the IV characteristics of Examples 5 and 6. FIG. 9A shows the measurement results of the IV characteristics of Examples 3 and 4 and Comparative Example 2, and FIG. 9B shows the measurement results of the IV characteristics of Examples 7 and 8. . Here, the horizontal axis is the applied voltage, the vertical axis is the common logarithm of the current density, “1.E-0i” (i is an integer of 1 to 7) is 10 ⁻ⁱ , “1.E + 0i” (i is 0 or 1) ) Indicates 10 ^{+ i} . As shown in FIG. 8A, the piezoelectric element sample of Comparative Example 2 in which all the layers are formed with Bi excess “+15” has a dielectric breakdown voltage of the piezoelectric layer, that is, a voltage causing a sudden leak current of +50 V. It was as low as about -35V. On the other hand, in the piezoelectric element samples of Examples 1 to 8 in which the buffer layer was formed by putting the Bi amorphous first amorphous layer under the Bi excessive second amorphous layer, the first precursor solution was “−30”. And “−15”, in both cases where the second precursor solution is “+15” and “+8”, the precursor solutions on the buffer layer are “+15”, “+8”, and “R”. In any case, the dielectric breakdown voltage was higher than that of the piezoelectric element sample of Comparative Example 2.

  As described above, when the buffer layer is formed by inserting the Bi amorphous first amorphous layer under the Bi excessive second amorphous layer, the dielectric breakdown voltage is reduced as compared with the piezoelectric element in which such a buffer layer is not formed. It was found that the voltage can be increased and the withstand voltage can be improved. As shown in the image of the piezoelectric thin film surface in FIG. 12, the effect of reducing cracks in the piezoelectric layer is also maintained.

In addition, for each piezoelectric element, FCE-1A manufactured by Toyo Technica Co., Ltd. is used, an electrode pattern of Φ = 500 μm is used, a triangular wave with a frequency of 1 kHz is applied in the room temperature atmosphere, and an applied voltage is applied every 5 V from 5 V to 30 V. The relationship between the amount of polarization P (μC / cm ² ) and the voltage (V) was determined.

  FIGS. 10A to 10E show the measurement results of the hysteresis characteristics of Examples 1 to 4 and Comparative Example 2. FIGS. 11A to 11D show the measurement results of the hysteresis characteristics of Examples 5 to 8. Show. As shown in FIGS. 10 and 11, the piezoelectric element samples of Examples 1 to 8 and Comparative Example 2 had substantially the same good hysteresis characteristics.

In the first precursor solution, when the ratio R1 _{Bi / (B-Ti)} of the Bi concentration to the molar concentration of the element excluding Ti from the B site element is 0.70 or more and 0.85 or less, good resistance Voltage property can be obtained.

(5) Application and others:
Various modifications can be considered for the present invention.
In the above-described embodiment, an individual piezoelectric body is provided for each pressure generation chamber. However, a common piezoelectric body may be provided for a plurality of pressure generation chambers, and an individual electrode may be provided for each pressure generation chamber.
In the above-described embodiment, a part of the reservoir is formed on the flow path forming substrate. However, the reservoir may be formed on a member different from the flow path forming substrate.
In the above-described embodiment, the upper side of the piezoelectric element is covered with the piezoelectric element holding unit, but the upper side of the piezoelectric element can be opened to the atmosphere.
In the embodiment described above, the pressure generating chamber is provided on the opposite side of the piezoelectric element with the diaphragm interposed therebetween, but it is also possible to provide the pressure generating chamber on the piezoelectric element side. For example, if a space surrounded by fixed plates and piezoelectric elements is formed, this space can be used as a pressure generating chamber.

  The liquid ejected from the fluid ejecting head may be any material that can be ejected from the liquid ejecting head, such as a solution in which a dye or the like is dissolved in a solvent, or a sol in which solid particles such as pigments or metal particles are dispersed in a dispersion medium. Is included. Such fluids include ink, liquid crystal, and the like. The liquid ejecting head can be mounted on an image recording apparatus such as a printer, a color filter manufacturing apparatus such as a liquid crystal display, an electrode manufacturing apparatus such as an organic EL display, a biochip manufacturing apparatus, and the like.

  The laminated ceramics produced by the production method described above can be suitably used to form ferroelectric thin films for ferroelectric devices, pyroelectric devices, piezoelectric devices, and optical filters. Ferroelectric devices include ferroelectric memory (FeRAM), ferroelectric transistors (FeFET), etc., and pyroelectric devices include temperature sensors, infrared detectors, temperature-electric converters, and the like. Examples of piezoelectric devices include fluid ejection devices, ultrasonic motors, acceleration sensors, and pressure-electric converters. Optical filters include blocking filters for harmful rays such as infrared rays, and photonic crystal effects due to quantum dot formation. And an optical filter using optical interference of a thin film.

As described above, according to the present invention, according to various aspects, it is possible to provide a technique for improving the performance of a piezoelectric element, a liquid ejecting head, and a liquid ejecting apparatus using a lead-free or low-lead piezoelectric material. it can.
In addition, the configurations disclosed in the embodiments and modifications described above are mutually replaced, the combinations are changed, the known technology, and the configurations disclosed in the embodiments and modifications described above are mutually connected. It is possible to implement a configuration in which replacement or combination is changed. The present invention includes these configurations and the like.

DESCRIPTION OF SYMBOLS 1 ... Recording head (liquid ejecting head), 2 ... Piezoelectric actuator, 3 ... Piezoelectric element, 10 ... Channel formation substrate, 12 ... Pressure generating chamber, 15 ... Silicon substrate, 16 ... Elastic film (vibration plate), 20 ... Bottom Electrode (first electrode), 30 ... piezoelectric layer, 31 ... first coating film, 32 ... first amorphous layer, 33 ... second coating film, 34 ... second amorphous layer, 35 ... buffer layer, 36 ... third Coating film: 37 ... third amorphous layer, 40 ... upper electrode (second electrode), 45 ... lead electrode, 50 ... protective substrate, 60 ... compliance substrate, 65 ... driving circuit, 70 ... nozzle plate, 71 ... nozzle opening, DESCRIPTION OF SYMBOLS 200 ... Recording apparatus (liquid ejecting apparatus), S1 ... 1st amorphous layer formation process, S2 ... 2nd amorphous layer formation process, S3 ... Buffer layer formation process, S4 ... Piezoelectric layer formation process, S11 ... 1st precursor Cloth process, S12 ... 1st coating film degreasing process, S21 ... 2nd precursor coating process, S22 ... 2nd coating film degreasing process, S41 ... 2nd precursor coating process, S42 ... 2nd coating film degreasing process, S43 ... 2nd degreasing film baking process, S44 ... 3rd precursor application | coating process, S45 ... 3rd coating film degreasing process, S46 ... 3rd degreasing film baking process.

Claims (5)

A method of manufacturing a piezoelectric element having a piezoelectric layer and an electrode,
Forming a first precursor solution coating film containing at least Bi, Ba, Fe and Ti on the electrode, and degreasing the coating film to form a first amorphous layer;
Forming a coating film of a second precursor solution containing at least Bi, Ba, Fe and Ti on the first amorphous layer, and degreasing the coating film to form a second amorphous layer;
Firing the first amorphous layer and the second amorphous layer to form a buffer layer;
Forming a layer containing at least Bi, Ba, Fe and Ti on the buffer layer to form the piezoelectric layer having a perovskite oxide, and
The molar concentration of Bi in the second precursor solution is larger than the molar concentration of an element obtained by removing Ti from a B-site element containing at least Fe and Ti to be the perovskite oxide,
The method for manufacturing a piezoelectric element, wherein a molar concentration of Bi in the first precursor solution is smaller than a molar concentration of an element obtained by removing Ti from a B-site element containing at least Fe and Ti to be the perovskite oxide.   In the first precursor solution, the ratio of the Bi concentration to the molar concentration of the element obtained by removing Ti from the B site element containing at least Fe and Ti to be the perovskite oxide is 0.70 to 0.85. The method for manufacturing a piezoelectric element according to claim 1.   The method for manufacturing a piezoelectric element according to claim 1 or 2, wherein Mn is contained in at least one of the first precursor solution and the second precursor solution.   A method for manufacturing a liquid jet head, comprising the step of forming a piezoelectric element by the method for manufacturing a piezoelectric element according to claim 1.   A method of manufacturing a liquid ejecting apparatus, comprising: forming a liquid ejecting head by the method of manufacturing a liquid ejecting head according to claim 4.