JP2011142287A - Liquid-jet head, liquid-jet device, and piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a liquid-jet head having a piezoelectric element which is free from lead and has excellent piezoelectric properties. <P>SOLUTION: The liquid-jet head is equipped with: a pressure generation chamber in communication with a nozzle opening; and a piezoelectric element including a first electrode, a piezoelectric layer formed on the first electrode and containing iron manganese acid bismuth lanthanum, and a second electrode formed on the piezoelectric layer. In the piezoelectric layer, the crystal is preferentially oriented to the (111) face. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus each including a piezoelectric element having a piezoelectric layer and an electrode for applying a voltage to the piezoelectric layer by causing a pressure change in a pressure generating chamber communicating with the nozzle opening. The present invention relates to a piezoelectric element used.

  As a piezoelectric element used in a liquid ejecting head, there is a piezoelectric material that exhibits an electromechanical conversion function, for example, a piezoelectric layer made of a crystallized dielectric material and sandwiched between two electrodes. Such a piezoelectric element is mounted on the liquid ejecting head as an actuator device in a flexural vibration mode, for example. As a typical example of a liquid ejecting head, for example, a part of a pressure generation chamber communicating with a nozzle opening for ejecting ink droplets is configured by a vibration plate, and the vibration plate is deformed by a piezoelectric element so that the ink in the pressure generation chamber is There is an ink jet recording head that pressurizes and ejects ink droplets from nozzle openings. In the piezoelectric element mounted on such an ink jet recording head, for example, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric material layer is formed into a pressure generating chamber by a lithography method. There is one in which piezoelectric elements are formed so as to be separated into corresponding shapes and independent for each pressure generating chamber.

  As a piezoelectric material used for such a piezoelectric element, lead zirconate titanate (PZT) is cited (see Patent Document 1).

JP 2001-223404 A

However, since the lead zirconate titanate described above contains lead, a piezoelectric material made of a ferroelectric that does not contain lead is required from the viewpoint of environmental problems. As a piezoelectric material not containing lead, for example, there is BiFeO ₃ having a perovskite structure represented by ABO ₃ , but there is a problem that a BiFeO ₃ based piezoelectric material has low insulation and may generate a leakage current. Further, in general used lead zirconate titanate, various improvements have been made in order to improve the characteristics. Regarding the behavior of the BiFeO ₃ based piezoelectric material, Currently not confirmed. Such a problem is not limited to a liquid jet head typified by an ink jet recording head, and similarly exists in a piezoelectric element such as an actuator device mounted in another device.

  SUMMARY An advantage of some aspects of the invention is that it provides a liquid ejecting head, a liquid ejecting apparatus, and a piezoelectric element having a piezoelectric element that does not contain lead.

  An aspect of the present invention that solves the above problems includes a pressure generation chamber that communicates with a nozzle opening, a first electrode, a piezoelectric layer that is formed on the first electrode and includes bismuth lanthanum ferromanganate, and the piezoelectric layer. A piezoelectric element including the second electrode formed on the piezoelectric layer, wherein the piezoelectric layer has a crystal preferentially oriented in a (111) plane. According to this, it is a piezoelectric layer made of bismuth lanthanum iron manganate that does not contain lead, and a liquid jet head having excellent displacement characteristics.

  The first electrode includes a platinum layer including platinum and an STO layer formed on the platinum layer and including strontium titanate (STO), and the piezoelectric layer is formed on the STO layer. Is preferred. According to this, a piezoelectric layer in which crystals are preferentially oriented in the (111) plane can be easily obtained.

  The first electrode preferably includes a platinum layer containing platinum and an SRO layer formed on the platinum layer and containing strontium ruthenate, and the piezoelectric layer is preferably formed on the SRO layer. . According to this, a piezoelectric layer in which crystals are preferentially oriented in the (111) plane can be easily obtained.

The bismuth lanthanum iron manganate is preferably a composite oxide represented by the following general formula. According to this, since the composite oxide represented by the following general formula (1) can obtain the characteristics as a ferroelectric, the liquid does not contain lead and has a piezoelectric element that can easily control the amount of strain. It can be an ejection head. Therefore, a liquid ejecting head having a piezoelectric element that can easily control the droplet size to be ejected can be obtained.
_{(Bi 1-x, La x} ) (Fe 1-y, Mn y) O 3 (1)
(0.10 ≦ x ≦ 0.20, 0.01 ≦ y ≦ 0.09)

  In the general formula (1), 0.17 ≦ x ≦ 0.20 is preferable, 0.19 ≦ x ≦ 0.20 is more preferable, and 0.01 ≦ y ≦ 0. .05 is preferred. According to this, it can be set as a piezoelectric element with a larger distortion amount.

  According to another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head. In this aspect, since the liquid jet head having the piezoelectric element that does not contain lead, has excellent displacement characteristics, has high insulating properties, and can suppress the occurrence of leakage current, the liquid ejection head is not adversely affected and the dielectric breakdown does not occur. Thus, the liquid ejecting apparatus is excellent in reliability.

  The piezoelectric element of the present invention includes a piezoelectric layer containing bismuth lanthanum ferromanganate and an electrode formed on the piezoelectric layer, and the piezoelectric layer is preferentially oriented in the (111) plane. It is characterized by that. According to this, it is possible to provide a piezoelectric element that does not contain lead and has excellent piezoelectric characteristics.

  According to another aspect of the invention, there is provided a method of manufacturing the liquid jet head according to the aspect, wherein a step of forming an STO precursor film serving as a precursor of the STO layer on the platinum layer, and the STO precursor film. A step of forming a piezoelectric precursor film to be a precursor of the piezoelectric layer, and firing the STO precursor film and the piezoelectric precursor film simultaneously to form the STO layer and the piezoelectric layer; And a liquid ejecting head manufacturing method comprising the steps of: According to this, it is possible to manufacture a laminate of the STO layer and the piezoelectric layer relatively easily.

FIG. 2 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. 2 is a cross-sectional view and a main part enlarged cross-sectional view of a recording head according to Embodiment 1. It is a figure showing the PV curve of the sample 1. FIG. It is a figure showing the PV curve of the sample 2. FIG. 5 is a diagram illustrating a PV curve of Sample 3. FIG. 5 is a diagram illustrating a PV curve of Sample 4. FIG. 6 is a diagram illustrating a PV curve of Sample 5. FIG. 10 is a diagram illustrating a PV curve of Sample 6. FIG. It is a figure showing the PV curve of the sample 7. FIG. 5 is a diagram illustrating a PV curve of Sample 8. FIG. It is a figure showing the PV curve of the sample 9. FIG. 4 is a diagram illustrating a PV curve of Sample 10. FIG. 5 is a diagram illustrating a PV curve of Sample 11. FIG. 5 is a diagram illustrating a PV curve of Sample 12. FIG. It is a figure showing the PV curve of the sample 13. FIG. 5 is a diagram illustrating a PV curve of Sample 14. FIG. 5 is a diagram illustrating a PV curve of Sample 15. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. It is a figure which shows the X-ray-diffraction pattern of an Example and a comparative example. It is a reciprocal lattice mapping figure of an Example. 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 manufactured by a manufacturing method according to Embodiment 1 of the present invention, and FIG. 2 is a plan view of FIG. 3 is a cross-sectional view taken along the line AA ′ in FIG. 2 (FIG. 3A) and an enlarged view of the main part (FIG. 3B).

  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 reservoir part 31 of a protective substrate, which will be described later, and constitutes a part of a reservoir that becomes a common ink chamber of 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, and the insulator film 55 made of zirconium oxide or the like is formed on the elastic film 50. Has been.

  Further, on the insulator film 55, a first electrode 60, a thin piezoelectric layer 70 having a thickness of 2 μm or less, preferably 0.3 to 1.5 μm, and a second electrode 80 are stacked. Thus, the piezoelectric element 300 is configured. 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 insulator film 55, and the first electrode 60 function as a vibration plate. However, the present invention is not limited to this. Alternatively, only the first electrode 60 may function as a diaphragm. Further, the piezoelectric element 300 itself may substantially serve as a diaphragm.

  In the present embodiment, as shown in FIG. 3B, the first electrode 60 is formed on the titanium oxide layer 61 containing titanium oxide and the titanium oxide layer 61 in this order from the insulator film 55 side. A platinum layer 62 containing platinum and an STO layer 63 formed on the platinum layer 62 and containing Nb-doped strontium titanate (Nb-STO) are stacked. Of the first electrode 60, the platinum layer 62 is a layer mainly responsible for conductivity, and the other titanium oxide layers 61 and STO layers 63 may have low conductivity.

  Here, the STO layer 63 acts as an orientation control layer for controlling orientation, and acts so that the crystals of the piezoelectric layer 70 are preferentially oriented to (111). The thickness of the STO layer 63 is preferably 5 to 10 nm, for example. If it is thinner than 5 nm, the effect of controlling the orientation is not remarkable. In this embodiment, Nb-doped strontium titanate (Nb-STO) is used as the STO layer 63, but strontium titanate doped with other elements such as La may be used.

The piezoelectric layer 70 is a piezoelectric material containing bismuth lanthanum iron manganate, that is, an ABO ₃ type composite oxide containing bismuth (Bi), lanthanum (La), iron (Fe), and manganese (Mn). . Note that the ABO ₃ type structure, that is, the A site of the perovskite structure has 12 coordinated oxygen, and the B site has 6 coordinated oxygen to form an octahedron. Bi and La are located at the A site, and Fe and Mn are located at the B site.

  Here, the piezoelectric layer 70 of the present embodiment is a film in which crystals are preferentially oriented in the (111) plane. Although the piezoelectric layer 70 itself made of a piezoelectric material containing bismuth lanthanum iron manganate is novel, in this embodiment, it is confirmed for the first time that the crystal is a film preferentially oriented in the (111) plane, In addition, since the crystal is preferentially oriented in the (111) plane, the piezoelectric characteristics are superior to those of a film having a random orientation. When the piezoelectric element is used as a piezoelectric actuator, a large amount of strain is generated. It can also be obtained.

  In the present invention, “the crystals are preferentially oriented in the (111) plane” means that all the crystals are oriented in the (111) plane and that most crystals (for example, 90% or more) are (111). In the case of being oriented in a plane.

  As will be described in detail later, the piezoelectric element according to the present embodiment uses a titanium film as a base of a platinum film made of platinum which is a precursor of the platinum layer 62, and Nb-doped titanium as an orientation control layer for controlling orientation on the platinum film. An STO layer 63 containing strontium acid (Nb-STO) is formed, and a piezoelectric precursor film containing bismuth, lanthanum, iron and manganese is baked on the STO layer 63 in an inert gas atmosphere. The piezoelectric layer 70 is fired and crystallized at the same time. By manufacturing in this way, the piezoelectric layer 70 can be a film in which crystals are preferentially oriented in the (111) plane.

  Here, whether or not the crystal of the piezoelectric layer is preferentially oriented to (111) is determined by the orientation control layer, the firing conditions, and the like. When the orientation control layer is not provided on the platinum film, bismuth, lanthanum, When a piezoelectric precursor film containing iron and manganese is fired and crystallized, the crystals are not preferentially oriented in the (111) plane, and the orientation state tends to be random. On the other hand, when the STO layer 63 is used as the orientation control layer, the firing condition may not be an inert atmosphere, and the firing may be performed in an air atmosphere or an oxygen atmosphere.

The piezoelectric layer 70 containing bismuth (Bi), lanthanum (La), iron (Fe), and manganese (Mn) preferably has a composition ratio represented by the following general formula (1). By setting the composition ratio represented by the following general formula (1), the piezoelectric layer 70 can be made a ferroelectric substance. As described above, if the piezoelectric layer is the piezoelectric layer 70, the amount of strain can be easily controlled. For example, when a piezoelectric element is used in a liquid ejecting head or the like, the size of the ink droplets to be discharged can be easily set. Can be controlled. The ABO ₃ type composite oxide containing Bi, La, Fe, and Mn exhibited different characteristics such as a ferroelectric, an antiferroelectric, and a paraelectric depending on the composition ratio. Results of creating piezoelectric elements (samples 1 to 18) with different composition ratios of the following general formula (1), applying a 25 V or 30 V triangular wave, and determining the relationship of P (polarization amount) −V (voltage) Are shown in FIGS. 4 to 18 and the composition is shown in Table 1. Samples 16 to 18 were too leaky to be measured and could not be used as piezoelectric materials. As shown in FIGS. 4 to 14, in samples 1 to 11 in the ranges of 0.10 ≦ x ≦ 0.20 and 0.01 ≦ y ≦ 0.09, the hysteresis loop shape characteristic of the ferroelectric has Observed. Therefore, in the samples 1 to 11, since the distortion amount linearly changes with respect to the applied voltage, the distortion amount can be easily controlled. On the other hand, samples 12 to 14 outside the range of 0.10 ≦ x ≦ 0.20 and 0.01 ≦ y ≦ 0.09 in the following general formula (1) are antiferroelectric as shown in FIGS. Since the double hysteresis having two hysteresis loop shapes in the positive electric field direction and the negative electric field direction characteristic of the body was observed, it is an antiferroelectric material, and the sample 15 is a paraelectric material as shown in FIG. In addition, as described above, samples 16 to 18 were too leaky to be used as a piezoelectric material, and none of samples 12 to 18 was a ferroelectric material.
_{(Bi 1-x, La x} ) (Fe 1-y, Mn y) O 3 (1)
(0.10 ≦ x ≦ 0.20, 0.01 ≦ y ≦ 0.09)

  Here, when an antiferroelectric material, which is a substance in which spontaneous polarization is arranged in a staggered manner, that is, a material that exhibits an electric field induced phase transition is used as a piezoelectric layer, it exhibits an electric field induced phase transition at a certain applied voltage or more and a large distortion Therefore, it is possible to obtain a large strain exceeding that of the ferroelectric material, but it is not driven below a certain voltage, and the amount of strain does not change linearly with respect to the voltage. The electric field induced phase transition is a phase transition caused by an electric field, and means a phase transition from an antiferroelectric phase to a ferroelectric phase or a phase transition from a ferroelectric phase to an antiferroelectric phase. The ferroelectric phase is a state where the polarization axes are aligned in the same direction, and the anti-ferroelectric phase is a state where the polarization axes are aligned alternately. For example, the phase transition from the antiferroelectric phase to the ferroelectric phase is caused by the fact that the polarization axes arranged in a staggered manner in the antiferroelectric phase rotate 180 degrees, so that the polarization axes become the same direction and become a ferroelectric phase. A strain generated by expansion or expansion / contraction of the lattice due to the electric field induced phase transition is a phase transition strain generated by the electric field induced phase transition. Those that exhibit such an electric field induced phase transition are antiferroelectrics, in other words, in the absence of an electric field, the polarization axes are staggered, and those that rotate in the same direction due to rotation of the polarization axis by the electric field are opposite. It is a ferroelectric material. Such an antiferroelectric material has a double hysteresis having two hysteresis loop shapes in a positive electric field direction and a negative electric field direction in a PV curve indicating a relationship between the polarization amount P and the voltage V of the antiferroelectric material. Become. A region where the amount of polarization changes abruptly is a portion where the phase transition from the ferroelectric phase to the antiferroelectric phase, or the phase transition from the ferroelectric phase to the antiferroelectric phase.

  On the other hand, in the ferroelectric material, the PV curve does not become double hysteresis unlike the antiferroelectric material, and the strain amount changes linearly with respect to the applied voltage by aligning the polarization direction in one direction. Therefore, since it is easy to control the amount of distortion, it is easy to control the size of droplets to be ejected, and a single piezoelectric element generates both small amplitude vibrations that generate fine vibrations and large amplitude vibrations that generate large excluded volumes. be able to.

  When the piezoelectric layer 70 is measured by powder X-ray diffraction, in the diffraction pattern, a diffraction peak attributed to a phase exhibiting ferroelectricity (ferroelectric phase) and a phase exhibiting antiferroelectricity (antiferroelectric) It is preferred that the diffraction peaks attributed to the (dielectric phase) are observed simultaneously. Thus, a diffraction peak attributed to a phase exhibiting ferroelectricity and a diffraction peak attributed to a phase exhibiting antiferroelectricity are simultaneously observed, that is, a composition phase of an antiferroelectric phase and a ferroelectric phase. When the piezoelectric layer 70 is the boundary (MPB), a piezoelectric element with a large amount of strain can be obtained. In the general formula (1), the piezoelectric layer 70 preferably satisfies 0.17 ≦ x ≦ 0.20, and more preferably 0.19 ≦ x ≦ 0.20. In this range, as shown in Examples described later, when powder X-ray diffraction measurement is performed, a diffraction peak attributed to a phase exhibiting ferroelectricity (ferroelectric phase) and a phase exhibiting antiferroelectricity (antiferroelectric) A diffraction peak attributed to (dielectric phase) is simultaneously observed, indicating an antiferroelectric phase and a ferroelectric phase simultaneously. Therefore, M. of antiferroelectric phase and ferroelectric phase. P. B. Therefore, a piezoelectric element with a large amount of strain can be obtained.

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

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

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

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

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

  A drive circuit 120 for driving the piezoelectric elements 300 arranged in parallel is fixed on the protective substrate 30. For example, a circuit board or a semiconductor integrated circuit (IC) can be used as the drive circuit 120. The drive circuit 120 and the lead electrode 90 are electrically connected via a connection wiring 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 reservoir portion 31 is sealed by the sealing film 41. The fixing plate 42 is formed of a relatively hard material. Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 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 reservoir 100 to the nozzle opening 21 is filled with ink, and then driven. In accordance with a recording signal from the circuit 120, a voltage is applied between each of the first electrode 60 and the second electrode 80 corresponding to the pressure generating chamber 12, and the elastic film 50, the insulator film 55, the first electrode 60, and the piezoelectric film are applied. By flexing and deforming the body layer 70, the pressure in each pressure generating chamber 12 increases and ink droplets are ejected from the nozzle openings 21.

  Next, an example of a method for manufacturing the ink jet recording head of this embodiment will be described with reference to FIGS. 19 to 23 are cross-sectional views in the longitudinal direction of the pressure generating chamber.

First, as shown in FIG. 19A, a silicon dioxide film made of silicon dioxide (SiO ₂ ) 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. 19B, an insulator film 55 made of zirconium oxide or the like is formed on the elastic film 50 (silicon dioxide film) by a reactive sputtering method, thermal oxidation, or the like.

  Next, as shown in FIG. 20A, a titanium film 56 made of titanium is provided on the insulator film 55 by a DC sputtering method, an ion sputtering method, or the like. Next, a platinum film 57 made of platinum is formed on the entire surface of the titanium film 56 by DC sputtering or the like, and then patterned.

  Next, the STO layer 63 is formed on the platinum film 57. A method for forming the STO layer 63 is not particularly limited, and examples thereof include a sputtering method, a laser ablation method, an MOCVD method, a MOD method, and a sol-gel method. In this embodiment, the STO layer 63 is formed by a sol-gel method. That is, an Nb-STO sol-gel solution was applied, dried and degreased to obtain an STO precursor film 58.

  Next, the piezoelectric layer 70 is laminated on the STO precursor film 58. The method for manufacturing the piezoelectric layer 70 is not particularly limited. For example, a solution obtained by dissolving and dispersing an organometallic compound in a solvent is applied and dried, and further fired at a high temperature to obtain the piezoelectric layer 70 made of a metal oxide. The piezoelectric layer 70 can be formed using a MOD (Metal-Organic Decomposition) method. The manufacturing method of the piezoelectric layer 70 is not limited to the MOD method, and for example, a sol-gel method, a laser ablation method, a sputtering method, a pulse laser deposition method (PLD method), a CVD method, an aerosol A liquid phase method or a solid phase method such as a deposition method may be used.

  As a specific example of the formation procedure of the piezoelectric layer 70, first, as shown in FIG. 20B, an organometallic compound, specifically, bismuth, lanthanum, iron, manganese, is formed on the STO precursor film 58. A sol or MOD solution (precursor solution) containing a metal-containing organometallic compound in a ratio of a target composition ratio is applied by using a spin coating method or the like to form a piezoelectric precursor film 71 (application) Process).

  The precursor solution to be applied is prepared by mixing organometallic compounds containing bismuth, lanthanum, iron and manganese so that each metal has a desired molar ratio, and dissolving or dispersing the mixture using an organic solvent such as alcohol. It has been made. As the organometallic compound containing bismuth, lanthanum, iron, and manganese, for example, metal alkoxides, organic acid salts, β-diketone complexes, and the like can be used. Examples of the organometallic compound containing bismuth include bismuth 2-ethylhexanoate. Examples of the organometallic compound containing lanthanum include lanthanum 2-ethylhexanoate. Examples of the organometallic compound containing iron include iron 2-ethylhexanoate. Examples of the organometallic compound containing manganese include manganese 2-ethylhexanoate.

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

  Next, as shown in FIGS. 20C and 20D, by heating the piezoelectric precursor film 71 to a predetermined temperature, for example, about 600 to 700 ° C., and holding it for a certain time in an inert gas atmosphere. Crystallization is performed to form the piezoelectric film 72 (firing step). At this time, the STO precursor film 58 is also baked to form the STO layer 63. That is, the STO layer 63 is not crystallized alone, but is crystallized simultaneously with the piezoelectric film 72.

  In addition, as a heating apparatus used by a drying process, a degreasing process, and a baking process, the RTA (Rapid Thermal Annealing) apparatus, a hotplate, etc. which heat by irradiation of an infrared lamp are mentioned, for example.

  Next, as shown in FIG. 21A, the side surfaces of the first electrode 60 and the first layer of the piezoelectric film 72 are inclined on the piezoelectric film 72 using a resist (not shown) having a predetermined shape as a mask. Pattern simultaneously.

  Next, after peeling off the resist, the above-described coating process, drying process, degreasing process, coating process, drying process, degreasing process, and baking process are repeated a plurality of times according to the desired film thickness, etc. As shown in FIG. 21B, the 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.

  Note that when passing through the step of crystallizing the piezoelectric precursor film 71, depending on the firing conditions, the platinum film 57 made of platinum contains platinum, and depending on the degree of titanium diffusion, platinum also contains titanium and titanium oxide. Layer 62 is formed. In the present embodiment, a titanium oxide layer containing titanium oxide may be formed between the platinum layer 62 and the STO layer 63 due to the diffused titanium. This is the orientation state of the piezoelectric layer 70. It does not affect.

  Here, the inert gas atmosphere is a rare gas such as helium or argon, an inert gas such as nitrogen gas, or a mixed gas atmosphere thereof. It may be in a state where the inside of the heating apparatus is replaced with an inert gas or in a state where an inert gas is allowed to flow in the heating apparatus. In addition, the inert gas concentration may not be 100%, and it is an atmosphere in which titanium constituting the titanium film 56 formed on the flow path forming substrate 10 side of the platinum film 57 to be the first electrode 60 diffuses. Well, for example, the oxygen concentration is less than 20%.

  After the piezoelectric layer 70 is formed in this way, as shown in FIG. 22A, a second electrode 80 made of platinum or the like is formed on the piezoelectric layer 70 by sputtering or the like, and each pressure generating chamber 12 is formed. Then, the piezoelectric layer 70 and the second electrode 80 are simultaneously patterned in a region opposite to each other to form the piezoelectric element 300 including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. The patterning of the piezoelectric layer 70 and the second electrode 80 can be performed collectively by dry etching via a resist (not shown) formed in a predetermined shape. Thereafter, post-annealing may be performed in a temperature range of 600 ° C. to 700 ° C. as necessary. Thereby, a good interface between the piezoelectric layer 70 and the first electrode 60 or the second electrode 80 can be formed, and the crystallinity of the piezoelectric layer 70 can be improved.

  Next, as shown in FIG. 22B, a lead electrode 90 made of, for example, gold (Au) or the like is formed over the entire surface of the wafer 110 for flow path forming substrate, 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. 22 (c), a protective substrate wafer 130 that is a silicon wafer and serves as a plurality of protective substrates 30 is disposed on the piezoelectric element 300 side of the flow path forming substrate wafer 110 via an adhesive 35. After the bonding, the flow path forming substrate wafer 110 is thinned to a predetermined thickness.

  Next, as shown in FIG. 23A, 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. 23B, the flow path forming substrate wafer 110 is anisotropically etched (wet etching) using an alkaline solution such as KOH through the mask film 52, whereby the piezoelectric element 300 is formed. 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.

(Other manufacturing methods)
The piezoelectric layer in which crystals are preferentially oriented in the (111) plane is not limited to those manufactured by the above-described manufacturing method.

  Examples of the orientation control layer on the platinum film include an STO layer and a strontium ruthenate (SRO) layer. The piezoelectric precursor film containing bismuth, lanthanum, iron and manganese formed on the orientation control layer may be fired and crystallized in an inert gas atmosphere, or fired and crystallized in an air or oxygen atmosphere. It is sufficient that the piezoelectric layer has a crystal in which the crystal is preferentially oriented in the (111) plane.

  Here, the method for forming the SRO layer is not particularly limited, and examples thereof include sputtering, laser ablation, MOCVD, sol-gel, and MOD.

  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 dioxide film was formed on the surface of a silicon substrate by thermal oxidation. Next, a 400-nm-thick zirconium oxide film was formed on the silicon dioxide film by RF sputtering. Next, a 20 nm-thick titanium film was formed on the zirconium oxide film by DC sputtering. Next, a platinum film having a thickness of 130 nm was formed on the titanium film by DC sputtering. Next, an Nb-STO sol-gel solution was spin-coated on a platinum film at 500 rpm, then 3000 rpm for 30 seconds, dried at 300 ° C. for 3 minutes, and degreased to form an STO precursor film.

  Next, a piezoelectric layer was formed on the STO precursor film by spin coating. The method is as follows. First, a precursor solution was prepared by mixing xylene and octane solutions of bismuth 2-ethylhexanoate, lanthanum 2-ethylhexanoate, iron 2-ethylhexanoate, manganese 2-ethylhexanoate at a predetermined ratio. Then, this precursor solution was dropped onto the substrate on which the platinum film was formed, and the piezoelectric precursor film was formed by first rotating the substrate at 500 rpm for 5 seconds and then at 1500 rpm for 30 seconds (application process). . Next, drying and degreasing were performed in the atmosphere at 350 ° C. for 3 minutes (drying and degreasing step). After repeating this coating process, drying, and degreasing process twice, baking was performed at 650 ° C. for 2 minutes using Rapid Thermal Annealing (RTA) in which the inside of the heating apparatus was flowed with nitrogen at a flow rate of 500 cc / min (baking process). This coating process, drying and degreasing process are repeated twice, and then the process of performing a baking process is performed three times. Thereafter, the inside of the heating apparatus is 650 ° C. with an RTA flowed with nitrogen at a flow rate of 500 cc / min. By baking for 5 minutes, a total of 450 nm-thick piezoelectric layer was formed by a total of 6 coatings. In the first firing step, the STO precursor film is also fired at the same time to form an STO layer.

After that, a platinum film having a film thickness of 100 nm is formed as a second electrode by a DC sputtering method on the piezoelectric layer, and then baked at 650 ° C. for 5 minutes with RTA flowed with nitrogen at a flow rate of 500 cc / min in the heating device. As a result, a piezoelectric element having an ABO ₃ type structure represented by the general formula (1) where x = 0.19 and y = 0.03 as a basic composition and a composite oxide containing titanium as a piezoelectric layer is obtained. Formed.

(Example 2)
A piezoelectric element was formed in the same manner as in Example 1 except that a (100) preferentially oriented strontium ruthenate (SRO) layer having a thickness of 50 nm was formed on the platinum film by sputtering instead of the STO layer. .

(Comparative Example 1)
The same operation as in Example 1 was performed except that the STO layer was not provided.

(Comparative Example 2)
Example 1 except that a titanium oxide film was formed on the zirconium oxide film instead of the titanium film, a platinum film was formed thereon, and a piezoelectric layer was formed without providing an STO layer on the platinum film. The same operation was performed.

(Test Example 1)
For the piezoelectric elements of Examples 1 and 2 and Comparative Examples 1 and 2, “D8 Discover” manufactured by Bruker AXS was used, CuKα ray was used as the X-ray source, and the powder X-ray diffraction pattern of the piezoelectric layer at room temperature Was obtained at φ = ψ = 0 °. The results of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in FIG. FIG. 25 shows a reciprocal lattice mapping diagram of the first embodiment.

As shown in FIG. 24, the XRD pattern differs depending on the atmosphere of the RTA, the material of the base of the platinum film serving as the first electrode, or whether the platinum film is different, and Comparative Examples 1 and 2 are in a random orientation state. However, in Examples 1 and 2, it is presumed that the films are not oriented films preferentially oriented in the (100) plane, but oriented films preferentially oriented in the (111) plane. Since the peak oriented in the (111) plane overlaps with the peak of platinum in the vicinity of 2θ = 40 °, it is not clear that it is the (111) plane preferred orientation, but 2θ was measured while rotating in the ψ direction. Looking at the reciprocal lattice mapping, in the piezoelectric layer of Example 1, the peak of the (110) plane is observed around ψ = 30 °, and therefore the peak of the (111) plane exists at ψ = 0 °. Is determined to be reliable. In all of Examples 1 and 2 and Comparative Examples 1 and 2, diffraction peaks derived from ABO ₃ were observed, and the piezoelectric layers of Examples 1 and 2 and Comparative Examples 1 and 2 formed an ABO ₃ type structure. I understand that.

(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 basic composition of the piezoelectric layer has been described as an ABO ₃ type composite oxide containing only Bi, La, Fe and Mn as metal elements, but Bi, La, Fe and Mn are described. ABO ₃ type complex oxide may be used, and other metals may be added to adjust the characteristics.

  In the embodiment described above, a 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. 26 is a schematic view showing an example of the ink jet recording apparatus.

  In the ink jet recording apparatus II shown in FIG. 26, the recording head units 1A and 1B having the ink jet recording head I are detachably provided with cartridges 2A and 2B constituting the ink supply means, and the recording head units 1A and 1B. Is mounted on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.

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

  In the first embodiment described above, an ink jet recording head has been described as an example of a liquid ejecting head. However, the present invention is widely intended for all liquid ejecting heads, and is a liquid ejecting a liquid other than ink. Of course, the present invention can also be applied to an ejection 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.

  The present invention is not limited to a piezoelectric element mounted on a liquid jet head typified by an ink jet recording head, and is mounted on other devices such as an ultrasonic device such as an ultrasonic transmitter, an ultrasonic motor, and a pressure sensor. The present invention can also be applied to a piezoelectric element.

  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 Protection substrate, 31 Reservoir part, 32 Piezoelectric element holding part, 40 Compliance substrate, 56 Titanium film, 57 Platinum film, 60 First electrode, 61 Titanium oxide layer, 62 Platinum layer, 63 STO layer, 70 Piezoelectric layer, 80 Second electrode, 90 lead electrode, 100 reservoir, 120 drive circuit, 300 piezoelectric element.

Claims (11)

A pressure generating chamber communicating with the nozzle opening;
A piezoelectric element comprising: a first electrode; a piezoelectric layer formed on the first electrode and containing bismuth lanthanum iron manganate; and a second electrode formed on the piezoelectric layer;
In the liquid ejecting head, the piezoelectric layer has crystals preferentially oriented in a (111) plane.   The first electrode includes a platinum layer containing platinum and an STO layer formed on the platinum layer and containing strontium titanate, and the piezoelectric layer is formed on the STO layer. The liquid ejecting head according to claim 1.   The liquid ejecting head according to claim 2, wherein the STO layer is doped with Nb.   The first electrode includes a platinum layer containing platinum and an SRO layer formed on the platinum layer and containing strontium ruthenate, and the piezoelectric layer is formed on the SRO layer. The liquid ejecting head according to claim 1. The liquid jet head according to claim 1, wherein the bismuth lanthanum iron manganate is a complex oxide represented by the following general formula.
_{(Bi 1-x, La x} ) (Fe 1-y, Mn y) O 3 (1)
(0.10 ≦ x ≦ 0.20, 0.01 ≦ y ≦ 0.09)   The liquid ejecting head according to claim 5, wherein 0.17 ≦ x ≦ 0.20.   The liquid ejecting head according to claim 6, wherein 0.19 ≦ x ≦ 0.20.   The liquid ejecting head according to claim 5, wherein 0.01 ≦ y ≦ 0.05.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1. A piezoelectric layer containing bismuth lanthanum iron manganate;
An electrode formed on the piezoelectric layer,
The piezoelectric element is characterized in that the piezoelectric layer has crystals preferentially oriented in a (111) plane.   4. The method of manufacturing a liquid jet head according to claim 2, wherein a step of forming an STO precursor film serving as a precursor of the STO layer on the platinum layer, and the piezoelectric on the STO precursor film. Forming a piezoelectric precursor film to be a precursor of the body layer, and simultaneously firing the STO precursor film and the piezoelectric precursor film to form the STO layer and the piezoelectric layer. A method of manufacturing a liquid ejecting head.