JP2007088445A - Piezoelectric, piezoelectric element, liquid ejection head, liquid ejector and process for producing piezoelectric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric exhibiting excellent orientation and piezoelectric characteristics through control of crystallinity, and ensuring high adhesion between a piezoelectric film and an electrode and high durability through suppression of peeling of film in which piezoelectric characteristics do not deteriorate even if temperature of operational environment varies, and to provide a piezoelectric element, a liquid ejection head and a liquid ejector employing it. <P>SOLUTION: The piezoelectric has a laminate structure of a specific ABO<SB>3</SB>perovskite oxide wherein the laminate structure has a layer of first crystal phase, a layer of second crystal phase different from the first crystal phase, and a boundary layer provided between the layers of first and second crystal phases wherein a specific crystal phase exists between the first and second crystal phases, and the boundary layer has a crystal phase varying gradually in the thickness direction of the layer. The laminate structure has a single crystal structure or a uniaxial orientation crystal structure as a whole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric body, a piezoelectric body element, a liquid ejection head, and a method for manufacturing these used in a liquid ejection apparatus. More specifically, the present invention relates to a large-area, high-density piezoelectric element, a liquid discharge head, and a manufacturing method thereof.

  In an ink jet printer, higher resolution, higher speed printing, and longer head are required. Therefore, it is required to realize a multi-nozzle head structure with a miniaturized head. In order to reduce the size of the liquid discharge head, it is necessary to reduce the size of the piezoelectric element for discharging the liquid. Further, in order to reduce the size of the piezoelectric element, the driving capability is reduced even if the size is reduced. A piezoelectric body having a high piezoelectric constant is required. For this reason, in the case of a piezoelectric body using a piezoelectric film, a film having excellent crystallinity, that is, a film in which the crystallinity of highly oriented crystals is controlled is required as the piezoelectric film. In order to make the piezoelectric film highly oriented crystal, the layer directly under the piezoelectric film has higher crystallinity, and the piezoelectric film and the layer immediately below it have a good lattice matching. It is preferable.

  In addition, the piezoelectric film and the layer immediately below the film tend to peel off due to stress applied to the interface due to the thinning of the piezoelectric film, and have good adhesion to the piezoelectric film to suppress this film peeling. There is also a request.

Conventionally, a piezoelectric film used for a piezoelectric element has a PZT obtained by forming a green sheet by molding a PbO, ZrO ₂ and TiO ₂ powder paste into a sheet and then sintering the sheet. A piezoelectric material is used (Patent Document 1).

  However, it is difficult to form the PZT-based oxide film described in Patent Document 1 described above to a thickness of 10 μm or less, for example. Further, since the green sheet is sintered at a temperature of 1000 ° C. or higher, there is a problem that the piezoelectric film shrinks to about 70% during heating. For this reason, since it is difficult to align the piezoelectric film and the structure such as the ink chamber with a dimensional accuracy of the order of several microns, a satisfactory small piezoelectric element has not been obtained.

  In addition, as the thickness of the ceramic piezoelectric film formed by sintering the green sheet becomes thinner, the influence of crystal grain boundaries cannot be ignored, and good piezoelectric characteristics cannot be obtained. As a result, there is a problem that even if a piezoelectric film having a thickness of 10 μm or less is produced by sintering the green sheet, the piezoelectric film cannot obtain sufficient piezoelectric characteristics for discharging the recording liquid.

  In addition to the above methods, methods for producing a piezoelectric film include sputtering, CVD, MBE, and sol-gel methods. When an oxide is formed using these methods, a thin film having a thickness of 10 μm or less can be obtained. However, since the piezoelectric film produced by these methods has a high density, there is a problem that the in-plane stress of the film becomes very high, and the adhesion with the lower electrode under the film becomes poor. As a piezoelectric element of an ink jet head, in order to withstand the stress generated by repeated driving, it is necessary to have high adhesion between the piezoelectric film and the lower electrode below it. The piezoelectric film produced by the above method cannot be used as an inkjet piezoelectric element.

Also, the piezoelectric body depends on the material, but if the piezoelectric characteristics fluctuate depending on the temperature, it is necessary to keep the operating environment temperature constant, and it is applicable to piezoelectric elements that have low temperature dependence and excellent piezoelectric characteristics. A piezoelectric body has not yet been found.
Japanese Patent Laid-Open No. 62-213399

  An object of the present invention is to provide a piezoelectric body having high durability with high crystallinity controlled, excellent orientation, excellent adhesion with an electrode, suppressed film peeling, and high durability. It is in. It is another object of the present invention to provide a piezoelectric element, a liquid discharge head, and a liquid discharge apparatus using the same.

  It is another object of the present invention to obtain a piezoelectric body whose piezoelectric characteristics do not deteriorate even when the temperature of the operating environment changes, and to provide a piezoelectric element, a liquid ejection head, and a liquid ejection apparatus using the piezoelectric body.

  Furthermore, an object of the present invention is to obtain a method of manufacturing a piezoelectric body using a microfabrication technique generally used in a semiconductor process, and to have a discharge port formed at a high density using this method. An object of the present invention is to provide a liquid discharge head having a high level.

The present _{invention, (Pb 1-x M x} ) xm (Zr y Ti 1-y) O 3 ( one that wherein, M is La, Ca, Ba, Sr, Bi, selected from Sb, and W 1 Piezoelectric material having a laminated structure of ABO ₃ perovskite type oxides shown in (4), wherein the laminated structure is selected from tetragonal, rhombohedral, pseudocubic or monoclinic A layered first crystal phase having a formed crystal phase;
A layered second crystal phase selected from tetragonal, rhombohedral, pseudocubic, or monoclinic and having a crystal phase different from the crystal phase of the first crystal phase; and the first The crystal phase has a boundary layer that gradually changes in the thickness direction of the layer between the crystal phase and the second crystal phase, and has a single crystal structure or a uniaxially oriented crystal structure as a whole laminated structure The present invention relates to a piezoelectric body characterized by:

  The present invention also relates to a piezoelectric element in which a pair of electrodes is provided on the piezoelectric body, a liquid discharge head using the piezoelectric element, and a liquid discharge apparatus using the liquid discharge head.

  In addition, the present invention relates to a method for manufacturing the piezoelectric body, wherein each crystal phase is formed by sputtering.

  The piezoelectric body of the present invention has excellent orientation and excellent piezoelectric properties with controlled crystallinity, high adhesion to the electrode, suppression of film peeling, and durability even with a thin film. High, it is possible to suppress deterioration of the piezoelectric characteristics even if the temperature of the operating environment changes. Further, it can be used for a piezoelectric element having a high degree of adhesion and a liquid discharge head to exhibit excellent piezoelectric characteristics.

  The piezoelectric body manufacturing method of the present invention can manufacture a highly reliable piezoelectric body by utilizing a microfabrication technique generally used in a semiconductor process. A discharge head can be manufactured.

The piezoelectric body of the present embodiment has a laminated structure including a single crystal structure or a uniaxial orientation (single orientation) crystal structure of a perovskite oxide described by a general formula ABO ₃ . The piezoelectric body has a layered structure including a plurality of different crystal phases, which is a layered crystal phase including a crystal phase selected from tetragonal, rhombohedral, pseudocubic, orthorhombic and monoclinic. The crystal phase, either the in _{(Pb 1-x M x)} xm (Zr y Ti 1-y) O 3 ( wherein, M is La, Ca, Ba, Sr, Bi, Sb, is selected from W 1 A perovskite-type oxide crystal phase represented by: a first crystal phase and a second crystal phase different from the first crystal phase. A first crystal phase and the second crystal phase is not limited to the perovskite oxide ABO ₃ which is composed of elemental composition of the same elements different, different elemental composition, the perovskite oxide elemental composition ABO ₃ met May be. Further, not only those having two layers having different first crystal phase and second crystal phase in the laminated structure, but also third, fourth,... Crystal phases and three or more different crystal phases are interposed therebetween. It may be combined with a boundary layer. Furthermore, a crystal phase (boundary layer) in which the crystal structure gradually changes in the thickness direction of the layer is provided between the different crystal phases. These first crystal phase, boundary layer, and second crystal phase may be periodically laminated. Each crystal phase is, for example, epitaxially grown and constitutes a multilayer structure, and exhibits a single crystal structure or a uniaxially oriented crystal structure as the entire multilayer structure.

In order for the multilayer structure having a plurality of different crystal phases to exhibit a single crystal or a uniaxially oriented crystal structure as a whole, the crystal phase of the perovskite oxide ABO ₃ constituting each layer of the multilayer structure must be <100> oriented. Is preferred. When the tetragonal, rhombohedral, pseudocubic, orthorhombic, and monoclinic crystals constituting each layer of the laminated structure are oriented to <100>, the entire laminated structure can have a single crystal or uniaxially oriented structure. Conceivable. In the perovskite oxide of this embodiment, the tetragonal system, rhombohedral system, pseudocubic system, orthorhombic system, and monoclinic system have lattice constants close to each other, and these crystal phases have crystal axes. It exists in a state in which the direction is oriented in the film thickness direction, and has a single crystal structure or a uniaxially oriented crystal structure.

  As a piezoelectric body having such a laminated structure, for example, as shown in FIG. 1, a first crystal phase 21 and a second crystal phase 22 having a certain crystal structure, and a boundary layer 211 provided therebetween. 221 may be mentioned. Specifically, as the boundary layer, the following is provided between the tetragonal first crystal phase 21 having a single crystal structure and the rhombohedral second crystal phase 22 having a single crystal structure. It has such a crystal structure. The boundary layer 211 has a crystal structure that gradually changes from tetragonal to rhombohedral toward the crystal phase 22 from the crystal phase 21 side. The boundary layer 221 has a crystal structure that gradually changes from rhombohedral to tetragonal crystals from the crystal phase 22 side toward the crystal phase 21.

  Here, the gradual change in the crystal structure of the boundary layer includes a case where the crystal structures of the crystal phase 21 and the crystal phase 22 are mixed. The mixed phase is formed by combining two or more crystal phases into a single crystal or a uniaxial crystal structure. Unlike the case where multiple crystal phases are included in a polycrystalline state with different crystal axis directions and there are grain boundaries, there are multiple crystal phases in a single perovskite oxide particle. Thus, it is preferable to form a crystal integrally.

  With such a configuration, strain from a biased direction can be evenly dispersed and absorbed, and therefore peeling due to strain can be suppressed even with a micron-order film thickness at which peeling is likely to occur. In other words, a piezoelectric body having high adhesion between the piezoelectric film and the electrode, suppressing film peeling and having high durability can be obtained, and stress applied to each layer of the crystal phase can be further relaxed, thereby improving the durability of the piezoelectric body. Further improvement can be achieved.

  In addition, when a defect such as a fine crack is generated in a specific phase, there is a possibility that the crack may spread in a piezoelectric body having a single crystal phase structure. However, since the Young's modulus for each layer differs depending on the laminated structure, the cracks generated from the layer having a large Young's modulus are prevented from progressing to the layer having the next large Young's modulus beyond the layer having the small Young's modulus. For this reason, it is difficult for cracks to spread, and a piezoelectric body having high durability as a whole can be obtained.

  Further, in such a laminated structure, when it is formed by epitaxial growth, a crystal phase having a different composition disperses and absorbs stress applied to the film itself in the phase change accompanying cooling from the film forming temperature to room temperature in the film forming process. To do. Furthermore, a specific crystal phase absorbs strain for each specific temperature region, and as a whole, it has good piezoelectric characteristics in a wide temperature region.

Further, as the laminated structure of the piezoelectric body of the present embodiment, it is preferable that at least two of the crystal phase layers have different thicknesses. For example, as shown in FIG. 2, the piezoelectric body has a crystal phase 31 with a film thickness T ₁ , a crystal phase 32 with a film thickness T ₂ , and a crystal phase 33 with a film thickness T ₃ , and the film thicknesses T ₁ , T ₂ , T ₃ may have different thicknesses. Between each crystal phase, there are boundary layers 311, 321, 331 in which the crystal structure gradually changes. The film thicknesses T ₁ , T ₂ , and T ₃ here indicate the distances from the center of the boundary layer to the center of the next boundary layer. As the piezoelectric body having such a laminated structure, it is preferable that the film thickness of the crystal phase layer most suitable for the conditions for using the piezoelectric body is sufficiently thick. It can be relaxed in the crystalline phase layer. In the piezoelectric body having a different thickness depending on each crystal phase, the ratio of the thickness of each crystal phase can be distributed according to the use conditions, and the piezoelectric body can be made according to the use environment. The boundary layer preferably changes gradually, but may be a mixed phase of crystal phases in contact with the boundary layer.

Perovskite oxide ABO ₃ used for the piezoelectric body of the present embodiment is represented by _{(Pb 1-x M x)} xm (Zr y Ti 1-y) O 3. In the formula, M represents any one element selected from La, Ca, Ba, Sr, Bi, Sb, and W. In the above formula, it is preferable to satisfy 0.45 ≦ y <1. Further, 0 ≦ x ≦ 0.10 and 0 ≦ xm ≦ 1.3 are preferably satisfied. Satisfying such an element composition facilitates the formation of a boundary layer to be described later.

The film thickness of each layer forming the laminated structure in the piezoelectric body of the present embodiment is preferably 1 nm or more and 1000 nm or less. If the thickness of each layer is 1 nm or more, sufficient piezoelectric characteristics can be obtained in the piezoelectric body, and if it is 1000 nm or less, peeling due to in-plane stress in the laminated structure can be suppressed.
[Piezoelectric element]
The piezoelectric element of the present embodiment is not particularly limited as long as it has the piezoelectric body of the present embodiment and a pair of electrodes provided in contact with the piezoelectric body. As an example of the piezoelectric element of this embodiment, as shown in FIG. 3, a piezoelectric element having a laminated structure in which a base body 41, a diaphragm 42, a buffer layer 43, a lower electrode 44, a piezoelectric body 45, and an upper electrode 46 are sequentially laminated. The body element 51 can be mentioned.

The material of the substrate in the piezoelectric element of the present embodiment is preferably a material having good crystallinity, such as Si, and specifically, SOI or the like in which a SiO ₂ film is formed on Si. Examples of the thickness of the substrate include 100 to 1000 μm.

The diaphragm is preferably provided to transmit the displacement of the piezoelectric body, has high lattice matching with the substrate, and has a sufficiently high Young's modulus to function as a diaphragm. When the material of the substrate is silicon oxide, the material of the diaphragm is preferably, for example, stabilized zirconia. When SOI is used as the substrate, an SiO ₂ layer on the Si single crystal layer may be used as the diaphragm. Examples of the thickness of the vibrating body include 2 to 10 μm.

The buffer layer is provided to play a role of matching the lattice matching between the crystal lattice constant of the substrate and the crystal lattice constant of the piezoelectric body, and may be omitted if the lattice matching between the substrate and the piezoelectric body is good. it can. The buffer layer may have several layers to achieve its function. The material of the buffer layer is preferably a material having high crystal lattice matching even with respect to the diaphragm directly below. When the material of the substrate is silicon, for example, stabilized zirconia YSZ (Y ₂ O ₃ —ZrO _2). ), CeO _{2 and the} like.

The lower electrode may be provided immediately above the buffer layer 43 or may be provided between the diaphragm 42 and the buffer layer 43. Further, when the buffer layer is not provided, the lower electrode may have the function of the buffer layer. In this case, the lower electrode is provided via the adhesion layer in order to improve the adhesion with the diaphragm. May be. As the material of the lower electrode, platinum group metals and these oxide-based conductive materials are preferable. Specific examples of the material for the lower electrode include platinum group metals such as Ru, Rh, Pd, Os, Ir, and Pt, and oxide-based conductive materials such as SrRuO ₃ , BaPbO ₃ , and RuO ₃ . Examples of the material for the adhesion layer include metals such as Ti, Cr, and Ir, and examples of these oxides include TiO ₂ and IrO ₂ .

  Since such a lower electrode 44 affects the orientation crystal orientation of the piezoelectric body provided thereon, the preferential orientation crystal orientation of the substrate surface is any one of (010), (101), (110), and (111). It is preferable that When the preferentially oriented crystal orientation of the substrate surface of the lower electrode is (010), (101), (110), (111), the piezoelectric body 45 to be laminated has the preferentially oriented crystal orientation of (100), (001), respectively. , (010), (101), (110), (111). In addition, when the preferred orientation crystal orientation is (001) or (111), the preferred orientation crystal orientation of the substrate surface of the lower electrode is (001) or (111). .

  In such a metal thin film or oxide conductive material thin film constituting the lower electrode, the crystal orientation rate is preferably 70% or more. The crystal orientation ratio is a ratio in the peak intensity of the film measured by XRD (X-ray diffraction) θ-2θ measurement. When the crystal orientation ratio of the metal electrode thin film is 70% or more, the lower electrode has good electrical characteristics, and the piezoelectric body 45 provided thereon has excellent crystallinity. It is more preferable that the crystal orientation rate of the metal thin film or the oxide conductive material thin film of the lower electrode is 85% or more. Further, the film thickness of the lower electrode is preferably 100 nm to 1000 nm, and the film thickness of the adhesion layer is preferably 5 nm to 300 nm, more preferably 10 to 70 nm.

  The piezoelectric body used in the piezoelectric element of this embodiment is the piezoelectric body of this embodiment. The film thickness of the piezoelectric body is preferably 100 nm or more and 10 μm or less, more preferably 500 nm or more and 8 μm or less. If the thickness of the piezoelectric body is 100 nm or more, the piezoelectric element is durable against stress generated by repeated driving when the piezoelectric element is used for a liquid discharge head, and if it is 10 μm or less, the occurrence of film peeling is suppressed. can do.

  The upper electrode 46 is provided immediately above the piezoelectric body 45 and charges the piezoelectric body together with the lower electrode. An adhesion layer made of the same material as the adhesion layer provided between the lower electrode and the diaphragm may be provided between the upper electrode and the piezoelectric body. The material of the upper electrode 46 can be the same as that of the lower electrode.

Specific examples of the piezoelectric element according to this embodiment include the following layer structures. This layer structure is displayed as an upper electrode 46 // piezoelectric body 45 // lower electrode 44 // vibrating plate 42, and indicates a different laminated structure.
Example 1: Pt / Ti // PbZrTiO ₃ // Pt / Ti // YSZ (Y ₂ O ₃ -ZrO ₂ ) / Si
Example 2: Au // PbZrTiO ₃ // Pt / Ti // YSZ (Y ₂ O ₃ -ZrO ₂ ) / Si
Example 3: Pt / Ti // PbZrTiO ₃ / PbTiO ₃ // Pt / Ti // YSZ (Y ₂ O ₃ -ZrO ₂ ) / Si
Example 4: Au / Cr // PbZrTiO ₃ / PbTiO ₃ // Pt / Ti // YSZ (Y ₂ O ₃ -ZrO ₂ ) / Si
Example 5: Au / Cr // PbZrTiO ₃ // Pt / Ti // SiO ₂ / Si
Example 6: Au // PbZrTiO ₃ / PbTiO ₃ // Pt / Ti // YSZ (Y ₂ O ₃ -ZrO ₂ ) / Si
Example 7: Pt / Ti // PbZrTiO ₃ // Pt / Ti // SiO ₂ / Si
Example 8: Au // PbZrTiO ₃ // Pt / Ti // SiO ₂ / Si
Example 9: Pt / Ti // PbZrTiO ₃ / PbTiO ₃ // Pt / Ti // SiO ₂ / Si
Example 10: Au // PbZrTiO ₃ / PbTiO ₃ // Pt / Ti // SiO ₂ / Si
Example 11: Pt // PbZrTiO ₃ // Pt / Ti // SiO ₂ / Si
Example 12: Au // PbZrTiO ₃ / PbTiO ₃ // Ir / Ti // SiO ₂ / Si
Example 13: Ir // PbZrTiO ₃ // Ir / Ti // SiO ₂ / Si
Example 14: Ir // PbZrTiO ₃ // Pt / Ti // SiO ₂ / Si
Example 15: Ir // PbZrTiO ₃ // Ir / Ti // SiO ₂ / Si
Example 16: Ir // PbZrTiO ₃ // Pt / Ti // SiO ₂ / Si
[Liquid discharge head]
The liquid ejection head of this embodiment includes an ejection port, an individual liquid chamber communicating with the ejection port, the piezoelectric element of the present embodiment provided corresponding to the individual liquid chamber, the individual liquid chamber, and the piezoelectric element. If it has a diaphragm provided between, it will not be restrict | limited in particular. As an example of the liquid discharge head of this embodiment, the ink jet head shown in FIG. 3 can be cited. Such an ink jet head is provided with a base 41 and a pressure chamber 61 which is a plurality of individual liquid chambers provided in parallel with the base. Each pressure chamber is provided with a liquid discharge port (discharge port) 53 and a piezoelectric element 51, and a diaphragm 42 is provided between the pressure chamber and the piezoelectric element. In this ink jet head, the discharge ports 53 are formed at a predetermined interval in the nozzle plate 52 provided on the lower side of the base body 41, but can also be provided on the side surface side.

  As an example, the piezoelectric element 51 is provided corresponding to each pressure chamber 61. Each piezoelectric element 51 includes, for example, a laminated body in which a buffer layer 43, a lower electrode 44, a piezoelectric body 45 that is a piezoelectric thin film, and an upper electrode 46 are sequentially laminated.

  In the liquid discharge head of this embodiment, the liquid in the individual liquid chamber is discharged from the discharge port by the volume change in the individual liquid chamber caused by the vibration plate to which the displacement of the piezoelectric body is transmitted.

  The liquid discharge head of this embodiment can be applied to a liquid discharge portion of an apparatus that discharges various liquids in addition to an inkjet head.

In the liquid discharge head according to the present embodiment, the piezoelectric element in which the orientation of the crystal orientation is aligned is used on the base plate, such as the diaphragm, the buffer layer constituting the piezoelectric element, the lower electrode, the piezoelectric body, and the upper electrode. There is little variation in the performance of each piezoelectric element. For this reason, a device with high adhesion can be obtained, and piezoelectric characteristics and mechanical characteristics sufficient for miniaturization can be obtained. In addition, by using a highly oriented crystal piezoelectric body, the durability of the piezoelectric element is improved, and the liquid discharge head is excellent in durability.
[Liquid ejection device]
The liquid discharge apparatus according to the present embodiment includes the liquid discharge head according to the present embodiment.

  As an example of the liquid discharge apparatus of this embodiment, an ink jet recording apparatus can be cited. As shown in FIG. 4, the ink jet recording apparatus includes an automatic feeding unit 97 that automatically feeds recording paper as a recording medium into the apparatus main body 96. Furthermore, a transport unit 99 that guides the recording paper fed from the automatic feeding unit 97 to a predetermined recording position and guides the recording paper from the recording position to the discharge port 98, a recording unit 91 that performs recording on the recording paper transported to the recording position, And a recovery unit 90 that performs recovery processing on the recording unit 91. The recording unit 91 is provided with a carriage 92 that houses the liquid ejection head of this embodiment and is reciprocated on the rail.

  In such an ink jet recording apparatus, the carriage 92 is moved on the rail by an electrical signal sent from a computer, and the piezoelectric body is displaced when a driving voltage is applied to the electrodes sandwiching the piezoelectric body. Printing is performed by pressurizing each piezoelectric chamber through the vibration plate by the displacement of the piezoelectric body and discharging ink from the discharge port.

  In the liquid ejection apparatus of this embodiment, droplets can be ejected uniformly at a high speed, and the apparatus can be miniaturized.

Although the above example has been illustrated as a printer, the liquid ejection apparatus according to the present embodiment can be used as an industrial liquid ejection apparatus in addition to an inkjet recording apparatus such as a facsimile, a multifunction peripheral, and a copying machine.
[Piezoelectric manufacturing method]
The method of manufacturing the piezoelectric body according to this embodiment is the above-described method for manufacturing a piezoelectric body, the step of providing a target in which a plurality of piezoelectric materials are arranged in different regions, and the step of performing sputtering by changing the region of the target to be sputtered And have. For example, as a method of manufacturing the piezoelectric body shown in FIG. 1, a base body to be a base body of a piezoelectric body, a piezoelectric material constituting a crystal phase, and a piezoelectric material having an elemental composition of the perovskite oxide ABO ₃ are arranged. A chamber provided so as to face the target is used. After the chamber is evacuated to high vacuum, a glow discharge is generated by applying a voltage between the substrate and the target, and the introduced argon gas or the like is ionized. Further, the ions are accelerated by a high electric field to strike the target, and a crystal phase is grown on the substrate by a recoil element from the target. In particular, in order to manufacture a piezoelectric body by periodically laminating different crystal phases, as shown in FIG. 5, two types of crystal phases are formed in different regions obtained by dividing the target region as shown in FIG. A piezoelectric material, composition 1, and composition 2 are used. The opening of the shutter is made to face the corresponding piezoelectric material region of the target. Only the region of the corresponding piezoelectric material is sputtered through the opening for a predetermined time to form a recoil element on the substrate. Thereafter, the shutter is gradually moved so that the opening faces a piezoelectric material region of another composition that forms the next crystal phase, and sputtering is performed. By repeating this, it is possible to obtain a piezoelectric body having a laminated structure in which different compositions, that is, two different crystal phases and a boundary layer therebetween are sequentially laminated. Further, in the case of a piezoelectric body having a laminated structure in which three kinds of crystal phases and a boundary layer are laminated, as shown in FIG. 6, three kinds of piezoelectric materials constituting different crystal phases, compositions 1 to 3, The target area is arranged in different areas of the three divided areas. A piezoelectric body having a laminated structure in which a crystal phase of composition 1 to 3 and a boundary layer thereof are laminated by performing sputtering while sequentially opening the shutter opening to the corresponding piezoelectric material region in order. Obtainable.

The piezoelectric material of the _{(Pb 1-x M x)} xm (Zr y Ti 1-y) perovskite oxide ABO ₃ represented by O ₃ is used as a target, for example, sintering process, was prepared in a desired composition It can be obtained by a powder method.

  In addition, the manufacture of the boundary layer in which the crystal structure gradually changes in the layer thickness direction is performed by adjusting the moving speed of the shutter that opposes the opening to the region where the different piezoelectric material is disposed. A crystal phase in which the crystal phase gradually changes is produced by setting the shutter movement speed to an opening movement speed that allows film formation corresponding to a crystal phase that gradually changes in the thickness direction of the piezoelectric body. be able to.

In this way, by using the target having the elemental composition of the perovskite oxide ABO ₃ and performing epitaxial growth, a piezoelectric body having a single crystal structure or a uniaxially oriented structure as a whole in a laminated structure having different crystal phases is obtained. Can do.

[Method for Manufacturing Piezoelectric Element]
Examples of the method for manufacturing the piezoelectric element of the present embodiment include a method using a thin film deposition technique. In manufacturing the piezoelectric element having the above-described configuration, a method for manufacturing the diaphragm 42 may be a thin film manufacturing method such as sputtering, CVD, laser ablation, or MBE. In particular, in the sputtering method, an oxide thin film epitaxially grown on the base body 41 can be obtained by sufficiently heating the deposition substrate during heating.

  In addition, as a method for producing the lower electrode 44 and the upper electrode laminated on the substrate 41 in the manufacture of the piezoelectric element, sputtering, CVD, PLD, Sol-Gel, MBE, hydrothermal synthesis, etc. The thin film manufacturing technique can be used. By these methods, a film can be formed by orienting the electrode material in a specific direction.

  In order to form the piezoelectric body 45 on the lower electrode 44, a method of forming a piezoelectric body and growing a crystal by a method such as sputtering, CVD, Sol-Gel, MBE, or hydrothermal synthesis is used. Can do.

  In addition to the above method, the upper electrode 46 is formed on the piezoelectric body 45 by a method such as a vapor phase method such as an evaporation method, a coating method such as a screen printing method, or a liquid phase method such as a plating method. be able to.

  For the production of the buffer layer of the piezoelectric element, a method similar to the method for producing an electrode using a buffer material can be used.

[Method of manufacturing liquid discharge head]
As a manufacturing method of the liquid discharge head of this embodiment, a method using a thin film deposition technique can be mentioned. In order to manufacture the liquid discharge head of this embodiment, a method of providing the individual liquid chamber (pressure chamber) 61 in the base body 41 of the piezoelectric element having the above-described configuration, and providing a separate liquid chamber in another base body and the piezoelectric body It can be based on a method of joining the element.

  As the former method, a piezoelectric element is manufactured by the same method as described above, and a part of the base body 41 is removed at a constant pitch to form a plurality of concave portions to be individual liquid chambers. For example, wet etching using anisotropic etching, dry etching such as ICP, Liga process, Bosch process, sand mill, or the like can be used to form the recess. The planar shape of the individual liquid chamber can be appropriately selected from a rectangular shape, a circular shape, an elliptical shape, and the like. In the case of a side shooter, the shape of the individual liquid chamber can be a narrowed shape having a tapered portion toward the liquid discharge port. The liquid discharge head can be manufactured by joining the nozzle plate 52 having the discharge port 53 perforated corresponding to the concave portion, or joining the discharge plate 53 and the nozzle plate having the communication hole. The material of the nozzle plate may be the same as or different from the substrate to be bonded, such as SUS, Ni, etc., and the difference in thermal expansion coefficient from the substrate to be bonded is 1E-6 / ° C. to 1E−. A material that is 8 / ° C is preferred. Examples of a method for perforating the discharge port in the nozzle plate include methods such as etching, machining, and laser beam irradiation.

  As a method for bonding the base body 41 and the nozzle plate 52, a method using an organic adhesive may be used, but a method using metal bonding with an inorganic material is preferable. Examples of materials used for metal bonding include In, Au, Cu, Ni, Pb, Ti, and Cr. These metal materials can bond the base and the nozzle plate at a low temperature of 250 ° C. or less, and the difference in thermal expansion coefficient from the base is small. In addition, damage to the piezoelectric body can be suppressed.

Hereinafter, the liquid discharge head using the piezoelectric body and the piezoelectric element of the present embodiment will be specifically described. The technical scope of the piezoelectric body and piezoelectric element of the present embodiment and the liquid discharge head using the piezoelectric body is not limited to this.
[Example 1]
A liquid discharge head was produced by the following method.

First, using a sputtering apparatus (L-210-FH (manufactured by ANELVA)), a stabilized zirconia YSZ (Y ₂ O ₃ —ZrO ₂ ) film was formed on the opening of the Si substrate to produce a diaphragm. At this time, the Si substrate is heated to 800 ° C., Ar and O ₂ are used as the ionizing gas, the applied power between the Si substrate and the target is 60 W, and the pressure in the apparatus is 1.0 Pa. A diaphragm having an oriented film thickness of 200 nm was obtained.

  Next, a lower electrode was produced by the same method as the method for producing the diaphragm. At this time, Pt is used as the target, the substrate temperature is 600 ° C., the ionizing gas Ar is used, the applied power between the diaphragm and the target is 100 W, and the pressure in the apparatus is 0.5 Pa. A 400 nm Pt film was obtained.

Then, using the said sputtering apparatus, what was shown in FIG. 5 which has arrange | positioned 2 types of perovskite oxides of the following target composition (1) (2) as a target in a different area | region was used. After the shutter opening was made to face one composition region of the target, fixed for a certain period of time and deposited on the substrate, the shutter was moved so that the opening faced the other composition region, and deposition was repeated. A piezoelectric body was obtained in which 20 crystal phases having different compositions were alternately laminated, and a boundary layer was laminated between the crystal phases. The substrate temperature was 650 ° C., ionizing gases Ar and O ₂ were used, the applied power between the electrode and the target was 100 W, and the pressure in the apparatus was 0.5 Pa. The sputtering time of the target composition (1) and (2) regions was 8 min, and the movement time (boundary layer formation time) from one region of the target of the shutter opening to the next region was 2 min. A piezoelectric body having a film thickness of 3000 nm composed of a tetragonal crystal, rhombohedral crystal, and a mixed phase boundary layer thereof was obtained as shown in FIG.

Target composition _{(1) (Pb 1-x} M x) xm (Zr y Ti 1-y) O ₃ wherein, x = 0, y = 0.45
_{(2) (Pb 1-x} M x) xm (Zr y Ti 1-y) O ₃ wherein, x = 0, y = 0.55
Then, the upper electrode was produced by the same method as the production method of the lower electrode.

Next, the Si substrate was subjected to ICP dry etching from the surface opposite to the surface on which the vibration plate 42 was provided to remove the central portion to form a recess. At this time, the temperature of the substrate was 20 ° C., the gases used were SF ₆ and C ₄ F ₈ , the dielectric of the high frequency coil was 1800 W in RF, and the pressure in the apparatus was 4.0 Pa. A Si nozzle plate provided with a liquid outlet 53 was bonded to a Si substrate having a recess by a Si-Si bonding method. A liquid discharge head having a length of 5000 μm and a width of 100 μm of the diaphragm of the piezoelectric element was produced.

With respect to the obtained piezoelectric element and liquid discharge head, the amount of displacement of the piezoelectric element at an applied voltage of 20 V and 10 kHz, the discharge amount of liquid droplets and the discharge speed of the liquid discharge head were measured.
[Example 2]
A liquid ejection head was produced by the same method as in Example 1 except that the target composition for producing the piezoelectric body was as follows, and the target shown in FIG. Target compositions (1) to (3) were respectively disposed as piezoelectric materials in the three target regions. The sputtering time for each composition region was 15 min, 13 min, and 11 min, respectively, and the moving time of the shutter opening was 4 min. A piezoelectric body was obtained in which 20 layers each of three layers of tetragonal crystals, rhombohedral crystals, and both of these crystal phases were mixed, and a boundary layer of the mixed phases was sequentially laminated. By changing the film formation time of each crystal phase, it was possible to form piezoelectric bodies having different film thicknesses of each crystal phase as shown in FIG.

During target composition _{(1) (Pb 1-x} M x) xm (Zr y Ti 1-y) O 3 Formula, M = La, x = 0.07 , y = 0.40, xm = 1.10
_{(2) (Pb 1-x} M x) xm (Zr y Ti 1-y) O ₃ wherein, M = Ca, x = 0.02 , y = 0.52, xm = 1.10
(3) (Pb _1-x M _x ) _xm (Zr _y Ti _1-y ) O ₃ where M = Ba, x = 0.03, y = 0.55, xm = 1.10
For the obtained piezoelectric element and liquid discharge head, the displacement amount, the droplet discharge amount, and the discharge speed were measured in the same manner as in Example 1.
[Example 3]
The following (1) to (6) were used as target compositions for producing a piezoelectric body, and targets each having a piezoelectric material arranged in six target areas were used. Otherwise, a liquid discharge head was produced by the same method as in Examples 1 and 2. The sputtering time for each composition region was 24 min, 24 min, 24 min, 30 min, 24 min, and 36 min, respectively. The moving time of the shutter opening was 6 min. A piezoelectric body in which 10 layers each of tetragonal, rhombohedral, tetragonal, pseudocubic, tetragonal, and monoclinic crystals and a boundary layer were sequentially laminated was obtained. The target divided region and the sputtering time were appropriately changed to form a piezoelectric body in which a plurality of crystal phases having a target film thickness were laminated.

Target composition _{(1) (Pb 1-x} M x) xm (Zr y Ti 1-y) O ₃ wherein, M = La, x = 0.07 , y = 0.40, xm = 1.15
(2) (Pb _1-x M _x ) _xm (Zr _y Ti _1-y ) O ₃ where M = Sr, x = 0.02, y = 0.52, xm = 1.15
(3) (Pb _1-x M _x ) _xm (Zr _y Ti _1-y ) O ₃ where M = Bi, x = 0.03, y = 0.40, xm = 1.15
_{(4) (Pb 1-x} M x) xm (Zr y Ti 1-y) O ₃ wherein, M = Sb, x = 0.02 , y = 0.52, xm = 1.15
_{(5) (Pb 1-x} M x) xm (Zr y Ti 1-y) O ₃ wherein, M = W, x = 0.02 , y = 0.40, xm = 1.15
(6) in _{(Pb 1-x M x)} xm (Zr y Ti 1-y) O 3 Formula, M = La, x = 0.03 , y = 0.52, xm = 1.15
Since the film formation time was set to 24 min, 30 min, and 36 min according to the above (2), (4), and (6) with a Zr amount of 0.52, a difference occurred in the stress applied to the film, and (2) is rhombohedral, (4) Pseudocubic, (6) is considered to have a monoclinic structure.

  With respect to the obtained piezoelectric element and liquid discharge head, the displacement amount, the droplet discharge amount, and the discharge speed were measured in the same manner as in Examples 1 and 2.

[Comparative Example 1]
The target composition for producing the piezoelectric body is (Pb _1-x M _x ) (Z _ry Ti _1-y ) O ₃ formula, where x = 0, y = 0.50 sintered body, and the heating temperature of the substrate is 600 ° C. Except for this, a liquid discharge head was manufactured in the same manner as in Example 1. A polycrystalline piezoelectric body in which tetragonal crystals and rhombohedral crystals were mixed was obtained.

  For the obtained piezoelectric element and liquid discharge head, the displacement amount, the droplet discharge amount, and the discharge speed were measured in the same manner as in Example 1.

  From the results, the displacement amount of the piezoelectric element of Example 1 was 0.40 nm. The displacement amount of Example 2 was 0.55 nm. The displacement amount of Example 3 was 0.54 nm. On the other hand, the displacement amount of the piezoelectric element consisting only of the tetragonal layer of Comparative Example 1 was 0.35 nm.

  When a voltage of 20 V was applied to the liquid discharge head of Example 1 (10 kHz), the discharge amount was 17 pl and the discharge speed was 14 m / sec. When a voltage of 20 V was applied (10 kHz) to the liquid discharge head of Example 2, the discharge amount was 19 pl and the discharge speed was 16 m / sec. When a voltage of 20 V was applied to the liquid discharge head of Example 3 (10 kHz), the discharge amount was 19 pl and the discharge speed was 15 m / sec. On the other hand, the discharge amount and discharge speed of the liquid discharge head of Comparative Example 1 were 16 pl and 13 m / sec, respectively, and the discharge amount and discharge speed were lower than in the example.

Further, when durability tests of these liquid discharge heads were performed, the liquid discharge heads of the examples of the present embodiment had no discharge failure nozzles even after exceeding 10 ⁹ times, whereas in the comparative examples, 10 ⁶ to 10 Separation occurred after ⁷ times, and a non-ejection nozzle part was generated. It can be seen that by applying the piezoelectric body of the present embodiment, a piezoelectric element having high durability and hardly causing peeling can be obtained.

It is a schematic diagram which shows the laminated structure of one embodiment of the piezoelectric material of this invention. It is a schematic diagram which shows the laminated structure of one embodiment of the piezoelectric material of this invention. It is a perspective view showing one embodiment of the liquid discharge head of the present invention. It is a perspective view which shows one embodiment of the liquid discharge apparatus of this invention. It is a schematic diagram which shows the relationship between the target and shutter of a sputtering device used for the manufacturing method of the piezoelectric material of this invention. It is a schematic diagram which shows the relationship between the target and shutter of a sputtering device used for the manufacturing method of the piezoelectric material of this invention.

Explanation of symbols

41 Base 42 Diaphragm 43 Buffer Layer 44 Lower Electrode 45 Piezoelectric 46 Upper Electrode 51 Piezoelectric Element 52 Nozzle Plate 53 Discharge Port 61 Pressure Chamber (Individual Liquid Chamber)
81 Inkjet recording device (liquid ejection device)

Claims (6)

In _{(Pb 1-x M x)} xm (Zr y Ti 1-y) O 3 ( wherein, M is La, Ca, Ba, Sr, Bi, Sb, and one kind of element selected from W A piezoelectric body having a laminated structure of perovskite oxide ABO ₃ represented by:
The laminated structure is
A layered first crystal phase having a crystal phase selected from any of tetragonal, rhombohedral, pseudocubic or monoclinic;
A layered second crystal phase selected from tetragonal, rhombohedral, pseudocubic or monoclinic and having a crystal phase different from the crystal phase of the first crystal phase;
A boundary layer between the first crystal phase and the second crystal phase, wherein the crystal phase gradually changes in the thickness direction of the layer;
A piezoelectric body characterized by having a single crystal structure or a uniaxially oriented crystal structure as a whole laminated structure.   2. The piezoelectric body according to claim 1, wherein 0.45 ≦ y <1 is satisfied in the formula.   A piezoelectric element comprising the piezoelectric body according to claim 1 and a pair of electrodes provided in contact with the piezoelectric body.   A liquid discharge head having an individual liquid chamber communicating with the discharge port and a piezoelectric element provided corresponding to the individual liquid chamber, and discharging the liquid in the individual liquid chamber from the discharge port; A liquid discharge head comprising the piezoelectric element according to claim 3 as the piezoelectric element.   A liquid discharge apparatus comprising the liquid discharge head according to claim 4. A method of manufacturing a piezoelectric body according to claim 1 or 2,
Providing a target in which a plurality of piezoelectric materials are arranged in different regions;
And a step of performing sputtering by changing a region of a target to be sputtered.

Images