JP2013080801A - Liquid jet head, liquid jet apparatus and piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jet head, a liquid jet apparatus and a piezoelectric element that implement a small environmental load and a large strain.SOLUTION: A liquid jet head 1 for discharging a liquid from a nozzle opening 21 includes a piezoelectric element 300 comprising a piezoelectric layer 70 and electrodes 60, 80 disposed on the piezoelectric layer 70. The piezoelectric layer 70 comprises a composite oxide containing bismuth, iron, barium and titanium and having a perovskite structure, and satisfies (Z-Z)/(Z-Z) of 0.08 to 0.45, where Zis a displacement under a driving voltage applied to the piezoelectric layer 70, Zis a displacement with the applied voltage later brought to 0 V, and Zis a minimum displacement under a further later applied voltage opposite in polarity to the driving voltage.

Description

  The present invention relates to a liquid ejecting head, a liquid ejecting apparatus, and a piezoelectric element that include a piezoelectric element having a piezoelectric layer made of a piezoelectric material and an electrode and eject liquid droplets from nozzle openings.

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

A piezoelectric material used as a piezoelectric layer constituting such a piezoelectric element is required to have high piezoelectric characteristics, and a typical example of the piezoelectric material is lead zirconate titanate (PZT) (see Patent Document 1). ). However, from the viewpoint of environmental problems, there is a demand for a piezoelectric material with reduced lead or lead content. As a piezoelectric material not containing lead, for example, there is a BiFeO ₃ -based piezoelectric material containing Bi and Fe (see, for example, Patent Document 2).

JP 2001-223404 A JP 2007-287745 A

  However, the piezoelectric layer made of a composite oxide with a reduced content of non-lead or lead does not have a sufficient amount of strain compared to lead zirconate titanate (PZT). It has been. Such a problem exists not only in the ink jet recording head, but of course in other liquid ejecting heads that eject droplets other than ink, and also in piezoelectric elements used in other than liquid ejecting heads. Exist as well.

  In view of such circumstances, it is an object of the present invention to provide a liquid ejecting head, a liquid ejecting apparatus, and a piezoelectric element that have a small environmental load and a large amount of distortion.

An aspect of the present invention that solves the above problem is a liquid ejecting head that discharges liquid from a nozzle opening, and includes a piezoelectric element that includes a piezoelectric layer and an electrode provided on the piezoelectric layer, and the piezoelectric body The layer is made of a complex oxide having a perovskite structure containing bismuth, iron, barium, and titanium. The displacement amount when the driving voltage is applied to the piezoelectric layer is Z _max , and the displacement when the applied voltage is 0 V thereafter. the amount of _{Z 0,} further followed upon application of a voltage of the drive voltage and reverse polarity, the minimum value of the displacement amount is taken as _{Z min, (Z 0 -Z min} ) / (Z max -Z 0) The liquid ejecting head is characterized in that the ratio is 0.08 or more and 0.45 or less.
In such an embodiment, a piezoelectric layer in which (Z ₀ −Z _min ) / (Z _max −Z ₀ ) satisfies 0.08 or more and 0.45 or less can be used to significantly increase the amount of strain, that is, the amount of displacement. A liquid ejecting head having elements is obtained. In addition, since the content of non-lead or lead can be suppressed, the burden on the environment can be reduced.

According to another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head.
In this aspect, since the piezoelectric element having a reduced environmental load and an improved displacement is provided, a liquid ejecting apparatus having excellent piezoelectric characteristics can be realized.

Another aspect of the present invention is a piezoelectric element including a piezoelectric layer and an electrode provided on the piezoelectric layer, wherein the piezoelectric layer includes bismuth, iron, barium, and titanium and has a perovskite structure. It is made of a complex oxide, and the displacement amount when a driving voltage is applied to the piezoelectric layer is Z _max , the displacement amount when the applied voltage is subsequently 0 V is Z ₀ , and then the voltage having the opposite polarity to the driving voltage (Z ₀ −Z _min ) / (Z _max −Z ₀ ) is 0.08 or more and 0.45 or less, where Z _min is the minimum value of displacement when applying It is in the piezoelectric element.
In such an embodiment, a piezoelectric layer in which (Z ₀ −Z _min ) / (Z _max −Z ₀ ) satisfies 0.08 or more and 0.45 or less can be used to significantly increase the amount of strain, that is, the amount of displacement. A liquid ejecting head having elements is obtained. In addition, since the content of non-lead or lead can be suppressed, the burden on the environment can be reduced.

FIG. 3 is an exploded perspective view illustrating a schematic configuration of the recording head according to the first embodiment. FIG. 3 is a plan view of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view of the recording head according to the first embodiment. The figure which shows the relationship between the displacement amount of a piezoelectric material, and a voltage. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. The figure which shows the SV curve of Example 1. FIG. The figure which shows the SV curve of Example 2. FIG. The figure which shows the SV curve of Example 3. FIG. The figure which shows the SV curve of Example 4. FIG. The figure which shows the SV curve of Example 5. FIG. The figure which shows the SV curve of Example 6. FIG. The figure which shows the SV curve of Example 7. FIG. The figure which shows the SV curve of Example 8. FIG. The figure which shows the SV curve of the comparative example 1. The figure which shows the SV curve of the comparative example 2. FIG. The figure which shows the SV curve of the comparative example 3. The figure which shows the SV curve of the comparative example 4. FIG. The figure which shows the relationship between Dmin- / Dm + and Dm +. 1 is a diagram illustrating a schematic configuration of a recording apparatus according to an embodiment of the present invention.

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

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

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

  On the other hand, the elastic film 50 is formed on the side opposite to the opening surface of the flow path forming substrate 10 as described above. On the elastic film 50, for example, titanium oxide having a thickness of about 30 to 50 nm or the like. An adhesion layer 56 for improving adhesion between the first electrode 60 such as the elastic film 50 and the like is provided. Note that an insulator film made of zirconium oxide or the like may be provided on the elastic film 50 as necessary.

  Further, on the adhesion layer 56, a first electrode 60, a piezoelectric layer 70 which is a thin film having a thickness of 3 μm or less, preferably 0.3 to 1.5 μm, and a second electrode 80 are laminated. Thus, a piezoelectric element 300 is configured as pressure generating means for causing a pressure change in the pressure generating chamber 12. Here, the piezoelectric element 300 refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In the present embodiment, the first electrode 60 is a common electrode of the piezoelectric element 300, and the second electrode 80 is an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. Also, here, the piezoelectric element 300 and the diaphragm that is displaced by driving the piezoelectric element 300 are collectively referred to as an actuator device. In the above-described example, the elastic film 50, the adhesion layer 56, the first electrode 60, and the insulator film provided as necessary function as a vibration plate. However, the present invention is not limited to this. 50 and the adhesion layer 56 may not be provided. Further, the piezoelectric element 300 itself may substantially serve as a diaphragm.

In this embodiment, the piezoelectric material constituting the piezoelectric layer 70 is a complex oxide having a perovskite structure including bismuth (Bi), iron (Fe), barium (Ba), and titanium (Ti). In the A site of the perovskite structure, that is, the ABO ₃ type structure, oxygen is 12-coordinated, and the B site is 6-coordinated of oxygen to form an octahedron. Bi and Ba are located at the A site, and Fe and Ti are located at the B site.

  Such a composite oxide containing Bi, Fe, Ba and Ti and having a perovskite structure is a composite oxide having a perovskite structure of a mixed crystal of bismuth ferrate and barium titanate, or bismuth ferrate and barium titanate. Is expressed as a solid solution in which the solid solution is uniformly dissolved. In the X-ray diffraction pattern, bismuth ferrate and barium titanate are not detected alone.

Here, bismuth ferrate and barium titanate are known piezoelectric materials each having a perovskite structure, and those having various compositions are known. For example, as bismuth ferrate and barium titanate, in addition to BiFeO ₃ and BaTiO ₃ , some elements are missing or excessive, or some elements are replaced with other elements. In the present invention, when expressed as bismuth ferrate or barium titanate, as long as the basic characteristics are not changed, those that deviate from the stoichiometric composition due to deficiency or excess, or some of the elements are replaced with other elements. Shall also be included in the ranges of bismuth ferrate and barium titanate.

The composition of the piezoelectric layer 70 made of a complex oxide having such a perovskite structure is represented, for example, as a mixed crystal represented by the following general formula (1). Moreover, this formula (1) can also be represented by the following general formula (1 ′). Here, the description of the general formula (1) and the general formula (1 ′) is a composition notation based on stoichiometry, and as described above, as long as a perovskite structure can be taken, it is inevitable due to lattice mismatch, oxygen deficiency, etc. Of course, a partial substitution of elements is allowed as well as a slight compositional deviation. For example, if the stoichiometric ratio is 1, the range of 0.85 to 1.20 is allowed.
(1-x) [BiFeO ₃ ] -x [BaTiO ₃ ] (1)
(0 <x <0.40)
(Bi _1-x Ba _x ) (Fe _1-x Ti _x ) O ₃ (1 ′)
(0 <x <0.40)

  Further, the complex oxide constituting the piezoelectric layer 70 may contain elements other than Bi, Fe, Ba, and Ti. Examples of the other element include at least one selected from the group consisting of Mn and Co. Of course, even a complex oxide containing other elements needs to have a perovskite structure.

  When the piezoelectric layer 70 contains Mn or Co, it is estimated that Mn and Co are located at the B site, and that Mn and Co are complex oxides having a structure in which part of Fe existing at the B site is substituted. The For example, in the case of containing Mn to Co, the composite oxide constituting the piezoelectric layer 70 has a structure in which part of Fe in a solid solution in which bismuth ferrate and barium titanate are uniformly dissolved, is substituted with Mn to Co. Alternatively, it is expressed as a composite oxide having a perovskite structure of mixed crystals of bismuth ferrate manganate to bismuth ferrate cobaltate and barium titanate, and the basic characteristics are mixed crystals of bismuth ferrate and barium titanate. Although it is the same as the complex oxide having a perovskite structure, the leakage characteristics are improved. In the X-ray diffraction pattern, bismuth ferrate, barium titanate, bismuth ferrate manganate, and bismuth ferrate cobaltate are not detected alone.

The piezoelectric layer 70 made of a complex oxide having a perovskite structure including Mn and Co in addition to Bi, Fe, Ba, and Ti is a mixed crystal represented by the following general formula (2), for example. Moreover, this formula (2) can also be represented by the following general formula (2 ′). In General Formula (2) and General Formula (2 ′), M is Mn to Co. Here, the description of the general formula (2) and the general formula (2 ′) is a composition notation based on stoichiometry, and as described above, as long as a perovskite structure can be taken, it is unavoidable due to lattice mismatch, oxygen deficiency, etc. Such a composition deviation is allowed. For example, if the stoichiometry is 1, one in the range of 0.85 to 1.20 is allowed.
(1-x) [Bi (Fe _{1- y My} ) O ₃ ] -x [BaTiO ₃ ] (2)
(0 <x <0.40, 0.01 <y <0.10)
_{(Bi 1-x Ba x)} ((Fe 1-y M y) 1-x Ti x) O 3 (2 ')
(0 <x <0.40, 0.01 <y <0.10)

In the present invention, the piezoelectric layer 70 has the displacement amount Z _max when the driving voltage is applied to the piezoelectric layer 70, the displacement amount when the applied voltage is 0 V, and then the driving amount Z ₀ . When the minimum value of the displacement is Z _min when a voltage having a reverse polarity to the voltage is applied, (Z ₀ −Z _min ) / (Z _max −Z ₀ ) is 0.08 or more and 0.45 or less. is there.

Specifically, when a drive voltage ( _a positive voltage V _a in FIG. 4) is applied to the piezoelectric body, the displacement amount temporarily decreases as shown in FIG. 4, which is an example showing the relationship between the displacement amount and the voltage. After that, it increases again and reaches Z _max . Thereafter, when the applied voltage is set to 0 V, the displacement amount becomes Z ₀ (the origin is Z ₀ in FIG. 4). Thereafter, when a voltage having a polarity opposite to that of the drive voltage ( _a negative voltage −V _a in FIG. 4) is further applied, the displacement amount once decreases and then increases again. The minimum displacement amount at this time is expressed as Z _Let it be _min . In the present invention, these Z _max , Z ₀ and Z _min are such that (Z ₀ −Z _min ) / (Z _max −Z ₀ ) satisfies 0.08 or more and 0.45 or less. In this specification, “Z _max −Z ₀ ” is also referred to as “Dm +”, and “Z ₀ −Z _min ” is also referred to as “Dmin−”.

Here, as described in Patent Document 2 and the like, a composite oxide containing Bi, Ba, Fe, and Ti is known as a piezoelectric material. In this embodiment, it is made of such a composite oxide containing Bi, Ba, Fe and Ti, and (Z ₀ −Z _min ) / (Z _max −Z ₀ ) is 0.08 or more and 0.45 or less. By using the piezoelectric layer 70, as shown in Examples and Comparative Examples described later, (Z ₀ −Z _min ) / (Z _max −Z ₀ ) is outside the range of 0.08 or more and 0.45 or less. As compared with the above, the amount of displacement can be remarkably improved. Therefore, an ink jet recording head having excellent piezoelectric characteristics is obtained.

  Each second electrode 80, which is an individual electrode of the piezoelectric element 300, is drawn from the vicinity of the end on the ink supply path 14 side and extends to the elastic film 50 or an insulator film provided as necessary. For example, a lead electrode 90 made of gold (Au) or the like is connected.

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

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

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

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

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

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

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

  Next, an example of a method for manufacturing the ink jet recording head of the present embodiment will be described with reference to FIGS. 5 to 9 are cross-sectional views in the longitudinal direction of the pressure generating chamber.

First, as shown in FIG. 5A, a silicon dioxide film made of silicon dioxide (SiO ₂ ) or the like constituting the elastic film 50 is formed by thermal oxidation or the like on the surface of a flow path forming substrate wafer 110 that is a silicon wafer. To do. Next, as shown in FIG. 5B, an adhesion layer 56 made of titanium oxide or the like is formed on the elastic film 50 (silicon dioxide film) by sputtering or thermal oxidation.

  Next, as shown in FIG. 6A, a first electrode 60 made of platinum, iridium, iridium oxide, or a laminated structure thereof is formed on the entire surface of the adhesion layer 56 by a sputtering method, a vapor deposition method, or the like. . Next, as shown in FIG. 6B, patterning is performed simultaneously on the first electrode 60 so that the side surfaces of the adhesion layer 56 and the first electrode 60 are inclined using a resist (not shown) having a predetermined shape as a mask.

  Next, after peeling off the resist, the piezoelectric layer 70 is laminated on the first electrode 60. The method for manufacturing the piezoelectric layer 70 is not particularly limited. For example, a MOD (Metal film) that obtains a piezoelectric layer (piezoelectric film) made of a metal oxide by coating and drying a solution containing a metal complex and firing at a high temperature. The piezoelectric layer 70 can be manufactured by using a chemical solution method such as an —Organic Decomposition ”method or a sol-gel method. In addition, the piezoelectric layer 70 can be manufactured by either a liquid phase method or a solid phase method such as a laser ablation method, a sputtering method, a pulse laser deposition method (PLD method), a CVD method, an aerosol deposition method, or the like.

  As a specific example of the formation procedure when the piezoelectric layer 70 is formed by the chemical solution method, first, as shown in FIG. 6C, a metal complex, specifically Bi, is formed on the first electrode 60. The piezoelectric precursor film 71 is formed by applying a piezoelectric film forming composition (precursor solution) made of a MOD solution or a sol containing a metal complex containing Fe, Ba and Ti using a spin coating method or the like. Form (application process).

  The precursor solution to be applied is obtained by mixing a metal complex capable of forming a composite oxide containing Bi, Fe, Ba and Ti by firing, and dissolving or dispersing the mixture in an organic solvent. When forming the piezoelectric layer 70 made of a complex oxide containing Mn and Co, a precursor solution containing a metal complex containing Mn and Co is further used. What is necessary is just to mix the mixing ratio of the metal complex which each contains Bi, Fe, Ba, and Ti, and the metal complex which has Mn and Co mixed as needed so that each metal may become a desired molar ratio. As a metal complex containing Bi, Fe, Ba, Ti, Mn, and Co, for example, an alkoxide, an organic acid salt, a β-diketone complex, or the like can be used. Examples of the metal complex containing Bi include bismuth octylate and bismuth acetate. Examples of the metal complex containing Fe include iron octylate, iron acetate, and tris (acetylacetonato) iron. Examples of the metal complex containing Ba include barium isopropoxide, barium octylate and barium acetylacetonate. Examples of the metal complex containing Ti include titanium isopropoxide, titanium octylate, titanium (di-i-propoxide) bis (acetylacetonate), and the like. Examples of the metal complex containing Mn include manganese octylate and manganese acetate. Examples of the organometallic compound containing Co include cobalt octylate and cobalt (III) acetylacetonate. Of course, a metal complex containing two or more of Bi, Fe, Ba, Ti, Mn and Co to be contained as required may be used. Examples of the solvent for the precursor solution include propanol, butanol, pentanol, hexanol, octanol, ethylene glycol, propylene glycol, octane, decane, cyclohexane, xylene, toluene, tetrahydrofuran, acetic acid, octylic acid, and the like.

Next, the piezoelectric precursor film 71 is heated to a predetermined temperature (for example, 150 to 200 ° C.) and dried for a predetermined time (drying step). Next, the dried piezoelectric precursor film 71 is degreased by heating it to a predetermined temperature (for example, 350 to 450 ° C.) and holding it for a certain time (degreasing process). The degreasing referred to here is to release the organic component contained in the piezoelectric precursor film 71 as, for example, NO ₂ , CO ₂ , H ₂ O, or the like. The atmosphere of the drying step or the degreasing step is not limited, and may be in the air, in an oxygen atmosphere, or in an inert gas. In addition, you may perform an application | coating process, a drying process, and a degreasing process in multiple times.

  Next, as shown in FIG. 7A, the piezoelectric precursor film 71 is crystallized by heating to a predetermined temperature, for example, about 600 to 850 ° C., and holding it for a certain time, for example, 1 to 10 minutes. Then, a piezoelectric film 72 made of a composite oxide containing bismuth, iron, barium and titanium and having a perovskite structure is formed (firing step). Also in this firing step, the atmosphere is not limited, and may be in the air, in an oxygen atmosphere, or in an inert gas. Examples of the heating device used in the drying step, the degreasing step, and the firing step include an RTA (Rapid Thermal Annealing) device that heats by irradiation with an infrared lamp, a hot plate, and the like.

  Next, the above-described coating process, drying process, degreasing process, coating process, drying process, degreasing process, and firing process are repeated a plurality of times in accordance with a desired film thickness and the like, and the piezoelectric layer 70 composed of a plurality of piezoelectric films 72. As shown in FIG. 7B, a piezoelectric layer 70 having a predetermined thickness composed of a plurality of layers of piezoelectric films 72 is formed. For example, when the film thickness of the coating solution per one time is about 0.1 μm, for example, the entire film thickness of the piezoelectric layer 70 composed of the ten piezoelectric films 72 is about 1.1 μm. In the present embodiment, the piezoelectric film 72 is provided by being laminated, but only one layer may be provided.

  After the piezoelectric layer 70 is formed in this way, as shown in FIG. 8A, the second electrode 80 made of platinum or the like is formed on the piezoelectric layer 70 by a sputtering method or the like, and each pressure generating chamber 12 is formed. Then, the piezoelectric layer 70 and the second electrode 80 are simultaneously patterned in a region opposite to each other to form the piezoelectric element 300 including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. The patterning of the piezoelectric layer 70 and the second electrode 80 can be performed collectively by dry etching via a resist (not shown) formed in a predetermined shape. Then, you may anneal in the temperature range of 600-850 degreeC as needed, for example. Thereby, a good interface between the piezoelectric layer 70 and the first electrode 60 or the second electrode 80 can be formed, and the crystallinity of the piezoelectric layer 70 can be improved.

Thus, the composition of the precursor solution, the firing temperature, the crystallinity, the film thickness, the underlying layer of the piezoelectric layer 70 (the first electrode 60, the adhesion layer 56, the insulator film, the elastic film) when the piezoelectric layer 70 is manufactured. type of 50 and the flow path forming substrate 10), by adjusting the manufacturing conditions, the piezoelectric layer _{70 (Z 0 -Z min) /} (Z max -Z 0) is 0.08 to 0.45 Can be within range. For example, if the content of Ba and Ti in the precursor solution is increased, (Z ₀ −Z _min ) / (Z _max −Z ₀ ) tends to decrease, and if the firing temperature of the piezoelectric layer 70 is increased (Z ₀ −Z _min ) / (Z _max −Z ₀ ) tends to increase, and when the thickness of the piezoelectric layer 70 is reduced, (Z ₀ −Z _min ) / (Z _max −Z ₀ ) tends to decrease. When the crystallinity of the piezoelectric layer 70 is increased, (Z ₀ −Z _min ) / (Z _max −Z ₀ ) tends to increase, and when the base of the piezoelectric layer 70 is an oxide (Z ₀ − Z _min ) / (Z _max −Z ₀ ) tends to increase.

  Next, as shown in FIG. 8B, a lead electrode 90 made of, for example, gold (Au) or the like is formed over the entire surface of the flow path forming substrate wafer 110, and then a mask pattern made of, for example, a resist or the like. Patterning is performed for each piezoelectric element 300 via (not shown).

  Next, as shown in FIG. 8C, a protective substrate wafer 130 that is a silicon wafer and serves as a plurality of protective substrates 30 is placed on the piezoelectric element 300 side of the flow path forming substrate wafer 110 with an adhesive 35 interposed therebetween. After the bonding, the flow path forming substrate wafer 110 is thinned to a predetermined thickness.

  Next, as shown in FIG. 9A, a mask film 52 is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape.

  Then, as shown in FIG. 9B, the flow path forming substrate wafer 110 is anisotropically etched (wet etching) using an alkaline solution such as KOH through the mask film 52, thereby forming the piezoelectric element 300. Corresponding pressure generating chambers 12, communication portions 13, ink supply passages 14, communication passages 15 and the like are formed.

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

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

Example 1
First, a silicon oxide (SiO ₂ ) film having a thickness of 1070 nm was formed on the surface of a (110) single crystal silicon (Si) substrate by thermal oxidation. Next, a titanium film having a thickness of 20 nm was formed on the SiO ₂ film by RF magnetron sputtering, and a titanium oxide film having a thickness of 40 nm was formed by thermal oxidation at 700 ° C. Next, a platinum film (first electrode 60) having a thickness of 130 nm and oriented in the (111) plane was formed on the titanium oxide film by DC sputtering.

  Next, the piezoelectric layer 70 was formed on the first electrode 60 by spin coating. The method is as follows. First, a precursor solution was prepared by mixing n-octane solutions of bismuth octylate, iron octylate, manganese octylate, barium octylate and titanium octylate at a predetermined ratio. And this precursor solution was dripped on the said board | substrate with which the titanium oxide film and the platinum film were formed, the substrate was rotated at 2500 rpm, and the piezoelectric precursor film | membrane was formed (application | coating process). Next, it was dried at 180 ° C. for 2 minutes (drying step). Subsequently, degreasing was performed at 400 ° C. for 2 minutes (degreasing step). After repeating this coating step, drying step, and degreasing step twice, firing was performed in an oxygen atmosphere using an RTA (Rapid Thermal Annealing) apparatus at 650 ° C. for 5 minutes (firing step). Subsequently, the series of steps of the application process, the drying process, the degreasing process, and the firing process described so far were repeated four times, and the piezoelectric layer 70 was formed by a total of eight applications.

Thereafter, a platinum film (second electrode 80) having a thickness of 100 nm is formed as a second electrode 80 on the piezoelectric layer 70 by sputtering, and then baked at 650 ° C. for 5 minutes using an RTA apparatus in an oxygen atmosphere. Is performed, and the piezoelectric layer 70 is composed of a composite oxide having a perovskite structure having a composition ratio of 0.75 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.25BaTiO ₃ and having a piezoelectric layer 70 with a thickness of 740 nm. Element 300 was formed.

(Example 2)
The mixing ratio of bismuth octylate, iron octylate, manganese octylate, barium octylate and titanium octylate in the precursor solution was changed, and the firing temperature and the firing temperature after the second electrode 80 was manufactured ( The same operation as in Example 1 was performed except that the firing temperature was 800 ° C., and the composition ratio was 0.70 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.30BaTiO ₃ having a perovskite structure. A piezoelectric element 300 having a piezoelectric layer 70 made of a complex oxide and having a thickness of 650 nm was formed.

(Example 3)
The number of times of application of the precursor solution was changed to 10 times, and the same as in Example 1 except that the temperature of the firing step and the temperature of firing after firing the second electrode 80 (firing temperature) were 750 ° C. The piezoelectric material having a piezoelectric layer 70 having a thickness of 835 nm, which is made of a composite oxide having a perovskite structure with a composition ratio of 0.75 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.25BaTiO ₃ by performing the operation. Element 300 was formed.

Example 4
The same operation as in Example 3 was performed except that the temperature of the firing step and the firing temperature (baking temperature) after manufacturing the second electrode 80 were 800 ° C., and the composition ratio was 0.75 Bi (Fe _0. made of a complex oxide having a ₉₅ Mn _0.05) perovskite structure of _{O 3} -0.25BaTiO 3, to form a piezoelectric element 300 having a piezoelectric layer 70 having a thickness of 840 nm.

(Example 5)
Example 4 and Example 4 except that the temperature raising condition during firing was changed and the crystal orientation direction was changed from (110) preferential orientation (that is, 60% or more of the crystals were oriented to (110)) to no orientation. By performing the same operation, a piezoelectric layer 70 made of a composite oxide having a perovskite structure with a composition ratio of 0.75 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.25BaTiO ₃ and having a thickness of 820 nm is formed. A piezoelectric element 300 was formed.

(Example 6)
Example 5 except that the mixing ratio of bismuth octylate, iron octylate, manganese octylate, barium octylate and titanium octylate in the precursor solution was changed and the number of coatings of the precursor solution was changed to 12. And a piezoelectric layer 70 having a thickness of 950 nm and comprising a composite oxide having a perovskite structure with a composition ratio of 0.75 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.25BaTiO _3. A piezoelectric element 300 was formed.

(Example 7)
Similar to Example 1 except that titanium tetraisopropoxide is used in place of titanium octylate as a raw material for the precursor solution, and the temperature of the firing step and the firing temperature after producing the second electrode 80 are 800 ° C. The piezoelectric layer 70 having a thickness of 980 nm is formed from the composite oxide having a perovskite structure with a composition ratio of 0.75 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.25BaTiO _3. A piezoelectric element 300 was formed.

(Example 8)
Except for changing the number of times of application of the precursor solution to 12, the same operation as in Example 4 was performed, and the composition ratio was 0.75 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.25BaTiO ₃ . A piezoelectric element 300 having a piezoelectric layer 70 made of a complex oxide having a perovskite structure and having a thickness of 1300 nm was formed.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the amount of bismuth octylate in the precursor solution was increased, and the temperature of the firing step and the firing temperature after producing the second electrode 80 were 750 ° C. A piezoelectric layer 70 made of a composite oxide having a perovskite structure with a composition ratio of 0.75 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.25BaTiO ₃ -0.025Bi ₂ O ₃ and having a thickness of 600 nm is formed. A piezoelectric element 300 was formed.

(Comparative Example 2)
The mixing ratio of bismuth octylate, iron octylate, manganese octylate, barium octylate and titanium octylate in the precursor solution was changed, and the temperature of the firing step and the firing temperature after producing the second electrode 80 were changed. Except that the temperature was set to 750 ° C., the same operation as in Example 1 was performed to obtain a composite oxide having a perovskite structure having a composition ratio of 0.85 Bi (Fe _0.95 Mn _0.05 ) O ₃ -0.15BaTiO _3. Thus, the piezoelectric element 300 having the piezoelectric layer 70 having a thickness of 750 nm was formed.

(Comparative Example 3)
Except that the mixing ratio of bismuth octylate, iron octylate, manganese octylate, barium octylate and titanium octylate in the precursor solution was changed, the same operation as in Example 4 was performed, and the composition ratio was 0.60 Bi ( A piezoelectric element 300 having a piezoelectric layer 70 having a thickness of 970 nm made of a complex oxide having a perovskite structure of Fe _0.95 Mn _0.05 ) O ₃ −0.40BaTiO ₃ was formed.

(Comparative Example 4)
Changing the mixing ratio of bismuth octylate, iron octylate, manganese octylate, barium octylate and titanium octylate in the precursor solution, changing the number of coatings of the precursor solution to 12, and changing the crystal orientation direction to (110) Change from preferred orientation (ie, 60% or more of the crystals are oriented to (110)) to (111) preferred orientation (ie, 60% or more of the crystals are oriented to (111)), and The composition ratio is 0.80 Bi (Fe _0.95 Mn ₀ .0) by performing the same operation as in Example 1 except that the temperature of the firing step and the firing temperature after manufacturing the second electrode 80 are 700 ° C. ₀₅ ) A piezoelectric element 300 having a piezoelectric layer 70 made of a complex oxide having a perovskite structure of O ₃ −0.20BaTiO ₃ and having a thickness of 1000 nm was formed.

(Test Example 1)
For each of the piezoelectric elements of Examples 1 to 8 and Comparative Examples 1 to 4, an electrode pattern of φ = 500 μm was used at room temperature using a displacement measuring device (DBLI) manufactured by Axact, and a voltage of ± 30 V was applied at a frequency of 1 kHz. The relationship (SV curve) between S (electric field induced strain (displacement amount)) and V (voltage) was determined. The result of Examples 1-8 and Comparative Examples 1-4 is shown in FIGS. 10-21 in order. From this S-V curve, determine the _Z max, _{Z 0} and _{Z min, respectively,} to determine the relationship between the _{(Z 0 -Z min) / (} Z max -Z 0) and _Z max -Z _0. The results are shown in FIG. In FIG. 22 and Table 1, Z ₀ −Z _min is expressed as Dmin−, and Z _max −Z ₀ is expressed as Dm +.

As a result, in Examples 1 to 8 where (Z ₀ −Z _min ) / (Z _max −Z ₀ ), that is, Dmin− / Dm + in FIG. 22 and Table 1 is 0.08 or more and 0.45 or less, Compared with Comparative Examples 1 to 4 in which Z ₀ −Z _min ) / (Z _max −Z ₀ ) is outside the range of 0.08 or more and 0.45 or less, Z _max −Z ₀ (that is, Dm +) is significantly higher. It was big. In addition, since it is preferable to drive the piezoelectric element 300 in a region that is displaced on the plus side in FIGS. 4, 10 to 21, etc., if Z _max −Z ₀ (that is, Dm +) that is a part of the displacement amount is large. It can be said that the displacement amount when used as the piezoelectric element 300 increases.

(Test Example 2)
For each of the piezoelectric elements of Examples 1 to 8 and Comparative Examples 1 to 4, “D8 Discover” manufactured by Bruker AXS was used, CuKα rays were used as the X-ray source, and the piezoelectric layer 70 was at room temperature (25 ° C.). The X-ray diffraction pattern of was obtained. As a result, in all of Examples 1 to 8 and Comparative Examples 1 to 4, a peak due to the perovskite structure and a peak derived from the substrate were observed. In all of Examples 1 to 8 and Comparative Examples 1 to 4, bismuth ferrate, barium titanate, and bismuth ferrate manganate were not detected alone. In Examples 1 to 4, 7, 8 and Comparative Examples 1 to 3, the (110) plane was preferentially oriented (that is, 60% or more of the crystals were oriented to (110)).

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

  Furthermore, in the above-described embodiment, the piezoelectric element 300 in which the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are sequentially stacked on the substrate (the flow path forming substrate 10) is illustrated, but the present invention is not particularly limited thereto. For example, the present invention can also be applied to a longitudinal vibration type piezoelectric element in which piezoelectric materials and electrode forming materials are alternately stacked to expand and contract in the axial direction.

  In addition, the ink jet recording head of these embodiments constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 23 is a schematic view showing an example of the ink jet recording apparatus.

  In the ink jet recording apparatus II shown in FIG. 23, the recording head units 1A and 1B having the ink jet recording head I are detachably provided with cartridges 2A and 2B constituting ink supply means, and the recording head units 1A and 1B. Is mounted on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.

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

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

  Further, the piezoelectric element according to the present invention is not limited to the piezoelectric element used in the liquid ejecting head, and can be used in other devices. Other devices include, for example, an ultrasonic device such as an ultrasonic transmitter, an ultrasonic motor, a temperature-electric converter, a pressure-electric converter, a ferroelectric transistor, a piezoelectric transformer, and a filter for blocking harmful rays such as infrared rays. And filters such as an optical filter using a photonic crystal effect by quantum dot formation, an optical filter using optical interference of a thin film, and the like. The present invention can also be applied to a piezoelectric element used as a sensor and a piezoelectric element used as a ferroelectric memory. Examples of the sensor using the piezoelectric element include an infrared sensor, an ultrasonic sensor, a thermal sensor, a pressure sensor, a pyroelectric sensor, and a gyro sensor (angular velocity sensor).

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

Claims (3)

A liquid ejecting head for discharging liquid from a nozzle opening,
A piezoelectric element comprising a piezoelectric layer and an electrode provided on the piezoelectric layer;
The piezoelectric layer is made of a complex oxide having a perovskite structure containing bismuth, iron, barium and titanium,
The displacement amount when the driving voltage is applied to the piezoelectric layer is Z _max , the displacement amount when the applied voltage is subsequently 0 V is Z ₀ , and then the voltage having the opposite polarity to the driving voltage is applied. A liquid ejecting head, wherein (Z ₀ −Z _min ) / (Z _max −Z ₀ ) is 0.08 or more and 0.45 or less, where Z _min is the minimum displacement amount.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1. A piezoelectric element comprising a piezoelectric layer and an electrode provided on the piezoelectric layer,
The piezoelectric layer is made of a complex oxide having a perovskite structure containing bismuth, iron, barium and titanium,
The displacement amount when the driving voltage is applied to the piezoelectric layer is Z _max , the displacement amount when the applied voltage is subsequently 0 V is Z ₀ , and then the voltage having the opposite polarity to the driving voltage is applied. A piezoelectric element, wherein (Z ₀ −Z _min ) / (Z _max −Z ₀ ) is 0.08 or more and 0.45 or less, where Z _min is the minimum displacement amount.

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