JP2006114562A - Piezoelectric film, piezoelectric element, piezoelectric actuator, piezoelectric pump, ink jet recording head, ink jet printer, surface acoustic wave element, thin film piezoelectric resonator, frequency filter, oscillator, electronic circuit, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric film having good piezoelectric characteristics.
A piezoelectric film according to the present invention comprises:
A perovskite-type piezoelectric film,
Preferentially oriented to pseudo cubic (100),
It has a monoclinic structure (region indicated by M in the figure)
The polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction.
[Selection] Figure 5

Description

  The present invention relates to a piezoelectric film, a piezoelectric element, a piezoelectric actuator, a piezoelectric pump, an ink jet recording head, an ink jet printer, a surface acoustic wave element, a thin film piezoelectric resonator, a frequency filter, an oscillator, an electronic circuit, and an electronic device.

Inkjet printers are known as printers that enable high image quality and high-speed printing. The ink jet printer includes an ink jet recording head having a cavity whose internal volume changes, and performs printing by ejecting ink droplets from the nozzle while scanning the head. As a head actuator in an ink jet recording head for such an ink jet printer, a piezoelectric element using a piezoelectric film represented by PZT (Pb (Zr, Ti) O ₃ ) has been conventionally used (for example, JP, 2001-223404, A).

In addition, in other devices having a piezoelectric film, since improvement of the characteristics is desired, provision of a piezoelectric film having good piezoelectric characteristics is desired.
JP 2001-223404 A

  An object of the present invention is to provide a piezoelectric film having good piezoelectric characteristics. Another object of the present invention is to provide a piezoelectric element using the piezoelectric film, a piezoelectric actuator using the piezoelectric element, a piezoelectric pump, an ink jet recording head, an ink jet printer, a surface acoustic wave element, a thin film piezoelectric resonator, To provide a frequency filter, an oscillator, an electronic circuit, and an electronic device.

The piezoelectric film according to the present invention is
A perovskite-type piezoelectric film,
Preferentially oriented to pseudo cubic (100),
Has a monoclinic structure,
The polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction.

  In the present invention, “pseudocubic” refers to a state in which the crystal structure is regarded as cubic.

  In the present invention, “preferential orientation” means that when 100% of crystals are in the desired (100) orientation, most crystals (for example, 90% or more) are oriented in the desired (100) orientation, and the rest And the case where the crystal has another orientation (for example, (111) orientation).

  This piezoelectric film has a monoclinic structure in which the polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction. As a result, the piezoelectric film has good piezoelectric characteristics.

In the piezoelectric film according to the present invention,
An angle δ formed by the polarization axis direction and the pseudo cubic <111> direction may be in the range of 0.0 ° <δ ≦ 10.0 °.

In the piezoelectric film according to the present invention,
Pb (Zr _1-x Ti _x ) O ₃
x can be in the range of 0.43 ≦ x ≦ 0.53.

  The piezoelectric element according to the present invention can have the above-described piezoelectric film.

The piezoelectric element according to the present invention is
A piezoelectric element having a perovskite-type piezoelectric film,
A substrate,
A lower electrode formed above the substrate;
A piezoelectric film formed above the lower electrode;
An upper electrode formed above the piezoelectric film,
The piezoelectric film is preferentially oriented to pseudo cubic (100),
In the state where an electric field in the pseudo cubic <100> direction is generated in the piezoelectric film,
The piezoelectric film has a monoclinic structure, and the polarization axis direction of the piezoelectric film is between a pseudo cubic <111> direction and a pseudo cubic <100> direction.

  In the present invention, other specific objects (hereinafter referred to as “B”) formed above a specific object (hereinafter referred to as “A”) are defined as B directly formed on A and A , B formed via the other on A. Further, in the present invention, forming B above A includes a case where B is formed directly on A and a case where B is formed on A via another on A.

  According to this piezoelectric element, the piezoelectric film has a monoclinic structure in which the polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction. As a result, the piezoelectric film has good piezoelectric characteristics. Therefore, the piezoelectric element has high performance. In particular, since the insulation property of the piezoelectric film is good, the repeated durability of the piezoelectric element is dramatically improved.

In the piezoelectric element according to the present invention,
An angle δ formed by the polarization axis direction of the piezoelectric film and the pseudo cubic <111> direction may be in the range of 0.0 ° <δ ≦ 10.0 °.

In the piezoelectric element according to the present invention,
The piezoelectric film is made of Pb (Zr _1-x Ti _x ) O ₃ ,
x can be in the range of 0.43 ≦ x ≦ 0.53.

  The piezoelectric actuator according to the present invention can have the above-described piezoelectric element.

  The piezoelectric pump according to the present invention can have the above-described piezoelectric element.

  The ink jet recording head according to the present invention can have the above-described piezoelectric element.

  The ink jet printer according to the present invention can have the ink jet recording head described above.

  The surface acoustic wave device according to the present invention can have the above-described piezoelectric device.

  The thin film piezoelectric resonator according to the present invention can have the above-described piezoelectric element.

  The frequency filter according to the present invention can include at least one of the above-described surface acoustic wave device and the above-described thin film piezoelectric resonator.

  The oscillator according to the present invention can include at least one of the above-described surface acoustic wave device and the above-described thin film piezoelectric resonator.

  The electronic circuit according to the present invention can include at least one of the above-described frequency filter and the above-described oscillator.

  The electronic device according to the present invention can include at least one of the above-described piezoelectric pump and the above-described electronic circuit.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

1. 1. First embodiment 1-1. Piezoelectric Film and Piezoelectric Element FIG. 1 is a cross-sectional view showing a piezoelectric element 1 according to a first embodiment to which the present invention is applied. The piezoelectric element 1 includes a substrate 2, an elastic film 3 formed on the substrate 2, a lower electrode 4 formed on the elastic film 3, and a piezoelectric film 5 formed on the lower electrode 4. And an upper electrode 6 formed on the piezoelectric film 5. For example, an electric field of 100 kV / cm to 400 kV / cm is applied between the lower electrode 4 and the upper electrode 6, so that piezoelectric deformation can be caused in the piezoelectric film 5.

  As the substrate 2, for example, a silicon substrate can be used. In the present embodiment, the substrate 2 is a (110) -oriented single crystal silicon substrate. As the substrate 2, a (100) -oriented single crystal silicon substrate or a (111) -oriented single crystal silicon substrate can also be used. Further, as the substrate 2, a substrate in which an amorphous silicon oxide film such as a thermal oxide film or a natural oxide film is formed on the surface of a silicon substrate can be used. The substrate 2 is processed to form ink cavities 521 in the ink jet recording head 50 as described later (see FIG. 9).

  As will be described later, the elastic film 3 functions as an elastic film 55 in the ink jet recording head 50. The thickness of the elastic film 3 is, for example, about 1 μm. When a plurality of piezoelectric elements 1 are formed in an ink jet recording head 50 described later, each piezoelectric element 1 can share the substrate 2 and the elastic film 3.

  The lower electrode 4 is one electrode for applying a voltage to the piezoelectric film 5. For example, the lower electrode 4 can be formed in the same planar shape as the piezoelectric film 5. When a plurality of piezoelectric elements 1 are formed in an ink jet recording head 50 described later, the lower electrode 4 is formed in the same planar shape as the common elastic film 3 so as to function as a common electrode for each piezoelectric element 1. Can also be done. The film thickness of the lower electrode 4 is, for example, about 50 nm to 200 nm.

The piezoelectric film 5 has a perovskite structure. In the present embodiment, a case where the piezoelectric film 5 is made of perovskite Pb (Zr _1-x Ti _x ) O ₃ (hereinafter also referred to as “PZT”) will be described. The piezoelectric film 5 is preferentially oriented to pseudo cubic (100). The piezoelectric film 5 has a monoclinic structure, and the polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction. In other words, the piezoelectric film 5 has a monoclinic structure in which the polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction.

The piezoelectric film 5 having a monoclinic structure and preferentially oriented to pseudo cubic (100) can be obtained by adjusting film forming conditions such as temperature, epitaxial stress from the lower electrode 4 and the like. Thus, the piezoelectric film 5 has a perovskite type monoclinic structure and is preferentially oriented to pseudo cubic (100). Therefore, the piezoelectric film 5 has a high piezoelectric constant (d ₃₁ ). The specific reason is as follows.

The monoclinic structure, which is one of the perovskite structures based on pseudo-cubic crystals, has a larger compliance (s _kj ) for shear mode deformation than the other structures. Piezoelectric constant (d _ij ) is determined by compliance (s _kj ) and piezo piezoelectric constant (e _ik )
d _ij = e _ik · s _kj
Given in. Regarding the piezoelectric constant (e _ik ), there is not much difference between the tetragonal structure, the monoclinic structure, and the rhombohedral structure. With respect to compliance (s _kj ), the _monoclinic structure is significantly greater than other structures. Accordingly, it is considered that the piezoelectric film 5 having a monoclinic structure has a high piezoelectric constant (d ₃₁ ).

  Furthermore, a monoclinic structure in which the polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction is considered to be a stable structure as compared to the rhombohedral structure. The reason for this is as follows.

FIG. 2 is a graph showing the results obtained by first-principles electronic state simulation of the total energy per unit cell of PbTiO ₃ with respect to the degree of deformation in the shear mode. The calculation was performed based on the density functional method in the range of local density approximation. The one-electron wavefunction was solved by the pseudopotential method. The vertical axis of the graph is shown as a relative value with the energy when the degree of deformation in the share mode is 0% as a reference (0.0 Harttree). One Harttree is 27.2 eV.

  FIG. 3 is a diagram schematically showing a lattice model used for the simulation. The unit cell of the reference structure was set to a = b = c = 397.06 pm and α = β = γ = 90 °. In the simulation, first, the internal atoms of the reference structure were relaxed and polarized in the pseudo-cubic <111> direction (the direction of the arrow P shown in FIG. 3) (the state of the rhombohedral structure). Then, in the plane orthogonal to the pseudo cubic <111> direction, the lattice was distorted in the pseudo cubic <001> direction (the direction of arrow S shown in FIG. 3) (shear mode deformation). The internal atoms were relaxed for each deformation of the shear mode. FIG. 4 is a diagram schematically showing changes in the polarization axis direction of the crystal. As the degree of deformation of the shear mode increases, the polarization axis direction P of the crystal moves from the pseudo cubic <111> direction to the pseudo cubic <100> direction as shown in FIG. 4 (arrow a shown in FIG. 4). . As shown in FIG. 2, as the degree of deformation of the share mode increases from zero, the total energy of the system decreases. The lower the total energy of the system, the more stable the system. Therefore, a monoclinic structure in which the polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction is expected to be more stable than the rhombohedral structure. Note that the degree of deformation of the share mode in which the total energy of the system is the minimum value is about 9%. At this time, the angle δ formed by the polarization axis direction P and the <111> direction is about 5.7 °.

The angle δ formed between the polarization axis direction P of the piezoelectric film 5 and the pseudo cubic <111> direction is:
0.0 ° <δ ≦ 10.0 °
It is preferable that it is the range of these. This is because when δ is larger than 10.0 °, the compliance is lowered and the piezoelectricity is lowered.

For the sake of convenience, a simulation for PbTiO ₃ was performed, but the result is predicted to be the same for PZT. This is because the PZT in the composition region showing the monoclinic structure can be set to a = b = c = 400 pm and α = β = γ = 90 °, which satisfies the same conditions as in the current simulation. .

  Further, the result of the above-described simulation does not change even in an actual applied electric field (for example, 100 kV / cm to 400 kV / cm).

As described above, the piezoelectric film 5 can be made of Pb (Zr _1-x Ti _x ) O ₃ [PZT]. FIG. 5 is an example of a phase diagram of PZT. In FIG. 5, R represents a region having a rhombohedral structure, M represents a region having a monoclinic structure, T represents a region having a tetragonal structure, and C represents a region having a cubic structure. _{X in} Pb (Zr _1-x Ti _x ) O ₃ has a certain range. The lower limit of x is the value of x (hereinafter also referred to as “x _MPB1 ”) at the phase boundary (hereinafter also referred to as “MPB ₁ ”) between the rhombohedral structure and the monoclinic structure of the piezoelectric film 5. . The value x of MPB ₁ (x _MPB1 ) is a value indicating the composition ratio of Ti when the rhombohedral structure and the monoclinic structure undergo phase transition. The upper limit of x is the value of x (hereinafter also referred to as “x _MPB2 ”) at the phase boundary between the monoclinic structure and the tetragonal structure of the piezoelectric film 5 (hereinafter also referred to as “MPB ₂ ”). . The value of x in MPB ₂ (x _MPB2 ) is a value indicating the composition ratio of Ti when the monoclinic structure and the tetragonal structure undergo phase transition. That is, x is
x _MPB1 ≤ x ≤ x _MPB2
It becomes the range. When x is within this range, the piezoelectric film 5 has a monoclinic structure. In the example shown in FIG.
0.43 ≦ x ≦ 0.53
It is. When x is larger than 0.53, the system has a tetragonal structure, and when x is smaller than 0.43, the system has a rhombohedral. In these cases, the compliance of the system is lowered. The phase diagram shown in FIG. 5 is an example, and may vary depending on factors such as in-film stress and lattice defects.

  If x is in the above-mentioned range, the piezoelectric film 5 can be easily controlled to have a monoclinic structure, and high piezoelectric characteristics can be expressed.

  The film thickness of the piezoelectric film 5 is, for example, about 300 nm to 1500 nm. With respect to the upper limit of the thickness, the thickness can be increased within a range that maintains the denseness and crystal orientation as a thin film, and can be allowed to be about 10 μm.

  The upper electrode 6 is the other electrode for applying a voltage to the piezoelectric film 5. The thickness of the upper electrode 6 is, for example, about 50 to 200 nm.

  In the present embodiment, at least one of the ICP method, the XPS method, and the SIMS method can be used to determine the composition. An XRD (X-Ray Diffraction) method can be used to determine the crystal orientation. For the determination of the crystal structure, at least one of an XRD method and a Raman scattering method can be used.

1-2. Next, a method for manufacturing the piezoelectric film 5 and the piezoelectric element 1 according to this embodiment will be described.

(1) First, a substrate 2 made of a silicon substrate having a (110) surface is prepared. Next, as shown in FIG. 6, an elastic film 3 is formed on the substrate 2. As will be described later, the elastic film 3 is a material having a sufficient etching selectivity with the substrate 2 so that the elastic film 3 functions as an etching stopper layer when the substrate 2 is etched to form a cavity. It is preferable to form by. When silicon is used as the substrate 2, examples of such a material include SiO _{2 and} ZrO ₂ . The elastic film 3 can be formed by, for example, a CVD method, a sputtering method, or a vapor deposition method.

(2) Next, as shown in FIG. 7, the lower electrode 4 is formed on the elastic film 3. The lower electrode 4 can be formed by, for example, a sputtering method or a vacuum deposition method. The lower electrode 4 is made of, for example, Pt (platinum). Pt is preferentially oriented to (111) relatively easily. Therefore, for example, Pt can be easily oriented and grown on the elastic film 3 by employing a relatively simple method such as sputtering. The material of the lower electrode 4 is not limited to Pt. For example, Ir (iridium), IrO _x (iridium oxide), SrRuO ₃ , Nb—SrTiO ₃ , La—SrTiO ₃ , Nb— (La, Sr) ) _CoO 3, LaNiO _3, or the like can be used PbBaO _3. Here, Nb—SrTiO ₃ is obtained by doping SrTiO ₃ with Nb, La-SrTiO ₃ is obtained by doping SrTiO ₃ with La, and Nb— (La, Sr) CoO ₃ is represented by (La, Sr). CoO ₃ is doped with Nb. By using an electrode having a perovskite structure such as SrRuO ₃ (hereinafter also referred to as “perovskite electrode”) as the lower electrode 4, a piezoelectric film formed on the lower electrode 4 in the manufacturing process. 5 can be preferentially oriented to pseudo cubic (100) more easily. In particular, the formation of the perovskite electrode can be performed while accelerating ions made of inert atoms and irradiating the formation surface of the perovskite electrode from a direction inclined by, for example, 45 degrees with respect to the thickness direction. As a result, inert atoms are taken into the perovskite electrode, and the lattice constant of the perovskite electrode is reduced from its original value. It is considered that the epitaxial stress due to this influences the piezoelectric film 5 formed on the lower electrode 4, and the piezoelectric film 5 is easily transferred to the monoclinic structure. As the inert atom, for example, at least one of Ar, Kr, and Xe can be used. Further, ions can be accelerated by a voltage of about 100 kV, for example.

  (3) Next, as shown in FIG. 8, a piezoelectric film 5 is formed on the lower electrode 4. First, the first and second raw material solutions are formed using the first and second raw material solutions containing at least one of Pb, Zr, and Ti so that the piezoelectric film 5 has a desired composition ratio. Are mixed in the desired ratio. This mixed solution (precursor solution) is disposed on the lower electrode 4 by a coating method such as a spin coating method or a droplet discharge method. Next, by performing a heat treatment such as firing, the oxide contained in the precursor solution is crystallized to obtain the piezoelectric film 5.

  More specifically, first, a series of steps of the precursor solution coating step, the drying heat treatment step, and the degreasing heat treatment step is performed a desired number of times. Next, the piezoelectric film 5 is formed by performing crystallization annealing.

  For the raw material solution, which is a material for forming the precursor solution, organic metals each containing a constituent metal of PZT are mixed so that each metal has a desired molar ratio, and these are mixed using an organic solvent such as alcohol. It is prepared by dissolving or dispersing. An organic metal such as a metal alkoxide or an organic acid salt can be used as the organic metal containing the constituent metals of PZT. Specifically, examples of the carboxylate or acetylacetonate complex containing the constituent metal of PZT include the following.

  Examples of the organic metal containing lead (Pb) include lead acetate. Examples of the organic metal containing zirconium (Zr) include zirconium butoxide. Examples of the organic metal containing titanium (Ti) include titanium isopropoxide. Note that the organic metal including the constituent metal of PZT is not limited to these.

Examples of the first raw material solution include a solution in which a condensation polymer for forming a PbZrO ₃ perovskite crystal composed of Pb and Zr among PZT constituent metal elements is dissolved in a solvent such as n-butanol in an anhydrous state. .

As the second raw material solution, among the constituent metal elements of PZT, a polycondensation product for forming a PbTiO ₃ perovskite crystal containing Pb and Ti, a solution prepared by dissolving in an anhydrous state in a solvent such as n- butanol are exemplified .

  Various additives such as a stabilizer can be added to the raw material solution as necessary. Furthermore, when hydrolysis / polycondensation is caused in the raw material solution, an acid or a base can be added as a catalyst together with an appropriate amount of water to the raw material solution.

  In the precursor solution coating step, the mixed solution is coated by a coating method such as spin coating. First, the mixed solution is dropped on the lower electrode 4. Spin is performed for the purpose of spreading the dropped solution over the entire surface of the lower electrode 4. The rotation speed of the spin is, for example, about 500 rpm in the initial stage, and then the rotation speed can be increased to about 2000 rpm so that coating unevenness does not occur. In this way, the application can be completed.

  In the drying heat treatment step, a heat plate (drying treatment) is performed at a temperature, for example, about 10 ° C. higher than the boiling point of the solvent used in the precursor solution, using a hot plate or the like in an air atmosphere. A drying heat treatment process is performed at 150 to 180 degreeC, for example.

  In the degreasing heat treatment step, heat treatment is performed at about 350 ° C. to 400 ° C. using a hot plate in an air atmosphere in order to decompose / remove the organometallic ligand used in the precursor solution.

  In the crystallization annealing, that is, the firing step for crystallization, heat treatment is performed in an oxygen atmosphere at, for example, about 600 ° C. This heat treatment can be performed by, for example, rapid thermal annealing (RTA).

  The film thickness of the piezoelectric film 5 after sintering can be about 300 to 1500 nm. In the example described above, the example in which the piezoelectric film 5 is formed by the liquid phase method has been described. However, the piezoelectric film 5 is formed by using a vapor phase method such as a sputtering method, a molecular beam epitaxy method, or a laser ablation method. It can also be formed.

  (7) Next, as shown in FIG. 1, the upper electrode 6 is formed on the piezoelectric film 5. The upper electrode 6 can be formed by, for example, sputtering or vacuum deposition. The upper electrode 6 is made of, for example, Pt (platinum). The material of the upper electrode 6 is not limited to Pt, and for example, a material that can be used as the material of the lower electrode 4 described above can be used.

  (8) Next, post-annealing can be performed in an oxygen atmosphere by RTA or the like, if necessary. Thereby, a favorable interface between the upper electrode 6 and the piezoelectric film 5 can be formed, and the crystallinity of the piezoelectric film 5 can be improved.

  Through the above steps, the piezoelectric film 5 and the piezoelectric element 1 according to this embodiment can be manufactured.

1-3. Action / Effect According to the piezoelectric element 1 in the present embodiment, the piezoelectric film 5 has a monoclinic structure in which the polarization axis direction is between the pseudo cubic <111> direction and the pseudo cubic <100> direction. . Thereby, the piezoelectric film 5 has good piezoelectric characteristics. Therefore, the piezoelectric element 1 has high performance.

The piezoelectric constant (d ₃₁ ) of the piezoelectric film 5 according to this embodiment can be, for example, about 200 pC / N in absolute value. For example, when the applied voltage is 100 kV / cm, the leakage current of the piezoelectric element 1 according to the present embodiment can be less than 10 ⁻⁵ A / cm ² . The repeated durability of the piezoelectric element 1 according to the present embodiment can be guaranteed 1 × 10 ⁹ times when the applied voltage is 300 kV / cm.

The method of measuring piezoelectric constant (d ₃₁₎ may be carried out as follows. First, the displacement amount S1 of the piezoelectric film 5 when a voltage is applied in an actual ink jet recording head 50 (see FIG. 9) is measured using a laser displacement meter. By comparing this value S1 with the displacement S2 obtained by the piezoelectric displacement simulation by the finite element method, the actual piezoelectric constant (d ₃₁ ) of the piezoelectric film 5 and the piezoelectric body assumed by the finite element method are used. The difference from the piezoelectric constant (d ′ ₃₁ ) of the film 5 can be obtained. As a result, the piezoelectric constant (d ₃₁ ) of the piezoelectric film 5 can be measured. The physical quantities required for the simulation of piezoelectric displacement by the finite element method are the Young's modulus of each film, the film stress, and the assumed piezoelectric constant (d ′ ₃₁ ) of the piezoelectric film 5. In the present embodiment, S1 is about 400 nm. In the simulation, for example, the Young's modulus of the piezoelectric film 5 was set to 65 GPa, and the in-plane compressive stress was set to 110 MPa.

2. Second embodiment 2-1. Inkjet Recording Head Next, an embodiment of an inkjet recording head having the piezoelectric element 1 according to the first embodiment will be described. FIG. 9 is a side sectional view showing a schematic configuration of the ink jet recording head according to the present embodiment, and FIG. 10 is an exploded perspective view of the ink jet recording head. In addition, FIG. 10 is shown upside down from the state normally used.

  As shown in FIG. 9, the ink jet recording head (hereinafter also referred to as “head”) 50 includes a head main body 57 and a piezoelectric portion 54 provided on the head main body 57. 9 corresponds to the elastic film 3, the lower electrode 4, the piezoelectric film 5, and the upper electrode 6 in the piezoelectric element 1 shown in FIG. In the ink jet recording head according to the present embodiment, the piezoelectric element 1 can function as a piezoelectric actuator. A piezoelectric actuator is an element having a function of moving a certain substance.

  Further, the elastic film 3 in the piezoelectric element 1 shown in FIG. 1 corresponds to the elastic film 55 in FIG. The substrate 2 (see FIG. 1) constitutes a main part of the head main body 57.

  That is, the head 50 includes a nozzle plate 51, an ink chamber substrate 52, an elastic film 55, and a piezoelectric part (vibration source) 54 bonded to the elastic film 55, as shown in FIG. 56 is housed. The head 50 constitutes an on-demand piezo jet head.

  The nozzle plate 51 is composed of, for example, a stainless steel rolling plate or the like, and has a large number of nozzles 511 for ejecting ink droplets formed in a line. The pitch between these nozzles 511 is appropriately set according to the printing accuracy.

  An ink chamber substrate 52 is fixed (fixed) to the nozzle plate 51. The ink chamber substrate 52 is formed by the substrate 2 (see FIG. 1). The ink chamber substrate 52 has a plurality of cavities (ink cavities) 521, a reservoir 523, and a supply port 524 formed by a nozzle plate 51, side walls (partition walls) 522, and an elastic film 55. . The reservoir 523 temporarily stores ink supplied from the ink cartridge 631 (see FIG. 13). Ink is supplied from the reservoir 523 to each cavity 521 through the supply port 524.

  As shown in FIGS. 9 and 10, the cavity 521 is disposed corresponding to each nozzle 511. The cavities 521 each have a variable volume due to the vibration of the elastic film 55. The cavity 521 is configured to eject ink by this volume change.

  As a base material for obtaining the ink chamber substrate 52, that is, the substrate 2 (see FIG. 1), a (110) -oriented silicon single crystal substrate is used. Since this (110) -oriented silicon single crystal substrate is suitable for anisotropic etching, the ink chamber substrate 52 can be formed easily and reliably. Such a silicon single crystal substrate is used such that the formation surface of the elastic film 3 shown in FIG. 1, that is, the formation surface of the elastic film 55 is the (110) surface.

  An elastic film 55 is disposed on the side of the ink chamber substrate 52 opposite to the nozzle plate 51. Further, a plurality of piezoelectric portions 54 are provided on the side of the elastic film 55 opposite to the ink chamber substrate 52. The elastic film 55 is formed by the elastic film 3 in the piezoelectric element 1 shown in FIG. 1 as described above. As shown in FIG. 10, a communication hole 531 is formed at a predetermined position of the elastic film 55 so as to penetrate in the thickness direction of the elastic film 55. Ink is supplied from the ink cartridge 631 to the reservoir 523 through the communication hole 531.

  Each piezoelectric portion 54 is electrically connected to a piezoelectric element driving circuit described later, and is configured to operate (vibrate, deform) based on a signal from the piezoelectric element driving circuit. That is, each piezoelectric part 54 functions as a vibration source (head actuator). The elastic film 55 vibrates (deflection) due to vibration (deflection) of the piezoelectric portion 54 and functions to instantaneously increase the internal pressure of the cavity 521.

  The base 56 is made of, for example, various resin materials, various metal materials, or the like. As shown in FIG. 10, the ink chamber substrate 52 is fixed and supported on the base body 56.

2-2. Operation of Inkjet Recording Head Next, the operation of the inkjet recording head 50 in this embodiment will be described. In the head 50 according to the present embodiment, a predetermined ejection signal is not input via the piezoelectric element driving circuit, that is, no voltage is applied between the lower electrode 4 and the upper electrode 6 of the piezoelectric portion 54. Then, as shown in FIG. 11, the piezoelectric film 5 is not deformed. For this reason, the elastic film 55 is not deformed and the volume of the cavity 521 is not changed. Accordingly, no ink droplet is ejected from the nozzle 511.

  On the other hand, in a state where a predetermined ejection signal is input via the piezoelectric element driving circuit, that is, in a state where a voltage is applied between the lower electrode 4 and the upper electrode 6 of the piezoelectric portion 54, as shown in FIG. In the piezoelectric film 5, the bending deformation occurs in the minor axis direction (the direction of the arrow s shown in FIG. 12). As a result, the elastic film 55 bends and the volume of the cavity 521 changes. At this time, the pressure in the cavity 521 increases instantaneously, and the ink droplet 58 is ejected from the nozzle 511.

  That is, when a voltage is applied, the crystal lattice of the piezoelectric film 5 is stretched in the direction perpendicular to the plane direction (the direction of the arrow d shown in FIG. 12), but is simultaneously compressed in the plane direction. In this state, the tensile stress f is in-plane for the piezoelectric film 5. Therefore, the elastic film 55 is deflected and bent by the tensile stress f. The greater the displacement amount (absolute value) of the piezoelectric film 5 in the minor axis direction of the cavity 521, the greater the deflection amount of the elastic film 55, making it possible to eject ink droplets more efficiently. .

  When the ejection of one ink is completed, the piezoelectric element driving circuit stops applying the voltage between the lower electrode 4 and the upper electrode 6. Thereby, the piezoelectric part 54 returns to the original shape shown in FIG. 11, and the volume of the cavity 521 increases. At this time, pressure (pressure in the positive direction) from the ink cartridge 631 toward the nozzle 511 acts on the ink. For this reason, air is prevented from entering the cavity 521 from the nozzle 511, and an amount of ink corresponding to the ink ejection amount is supplied from the ink cartridge 631 to the cavity 521 through the reservoir 523.

  In this way, arbitrary (desired) characters and figures are printed by sequentially inputting ejection signals via the piezoelectric element driving circuit to the piezoelectric unit 54 at the position where ink droplets are to be ejected. be able to.

2-3. Method for Manufacturing Inkjet Recording Head Next, an example of a method for manufacturing the inkjet recording head 50 in the present embodiment will be described.

  First, a base material to be an ink chamber substrate 52, that is, a substrate 2 made of a (110) oriented silicon single crystal substrate is prepared. Next, as shown in FIGS. 1 and 6 to 8, the elastic film 3, the lower electrode 4, the piezoelectric film 5, and the upper electrode 6 are sequentially formed on the substrate 2. The elastic film 3 formed here becomes the elastic film 55 as described above.

  Next, as shown in FIGS. 11 and 12, the upper electrode 6, the piezoelectric film 5, and the lower electrode 4 are patterned to correspond to the individual cavities 521, and as shown in FIG. 9, the cavities 521 are patterned. The number of piezoelectric portions 54 corresponding to the number of is formed.

  Next, the base material (substrate 2) to be the ink chamber substrate 52 is patterned, and concave portions to be the cavities 521 are respectively provided at positions corresponding to the piezoelectric portions 54, and concave portions to be the reservoir 523 and the supply port 524 at predetermined positions. Form.

  In the present embodiment, since a (110) -oriented silicon substrate is used as the base material (substrate 2), wet etching (anisotropic etching) using a high-concentration alkaline aqueous solution is suitably employed. In wet etching with a high-concentration alkaline aqueous solution, the elastic film 3 can function as an etching stopper as described above. Therefore, the ink chamber substrate 52 can be formed more easily.

  In this manner, the ink chamber substrate 52 is formed by removing the base material (substrate 2) by etching until the elastic film 55 is exposed in the thickness direction. At this time, a portion left without being etched becomes the side wall 522. The exposed elastic film 55 is in a state where it can function as an elastic film.

  Next, the nozzle plate 51 on which the plurality of nozzles 511 are formed is aligned so that each nozzle 511 corresponds to a concave portion that becomes each cavity 521, and bonded in that state. Thereby, a plurality of cavities 521, a reservoir 523, and a plurality of supply ports 524 are formed. For the joining of the nozzle plate 51, for example, an adhesive method using an adhesive or a fusion method may be used. Next, the ink chamber substrate 52 is attached to the base 56.

  The ink jet recording head 50 according to this embodiment can be manufactured through the above steps.

2-4. Action / Effect According to the ink jet recording head 50 according to the present embodiment, as described above, the piezoelectric constant (d ₃₁ ) of the piezoelectric film 5 of the piezoelectric portion 54 is high, and the deformation is larger than the applied voltage. It is what constitutes. That is, the piezoelectric portion 54 has good piezoelectric characteristics. Thereby, the amount of deflection of the elastic film 55 is increased, and ink droplets can be ejected more efficiently. Here, “efficient” means that the same amount of ink droplets can be ejected with a smaller voltage. That is, the driver circuit can be simplified and the power consumption can be reduced at the same time, so that the pitch of the nozzles 511 can be formed at a higher density. Therefore, high-density printing and high-speed printing are possible. Furthermore, since the length of the long axis of the cavity 521 can be shortened, the entire head can be reduced in size.

3. Third Embodiment 3-1. Inkjet Printer Next, an embodiment of an inkjet printer having the inkjet recording head 50 according to the second embodiment will be described. FIG. 13 is a schematic configuration diagram illustrating an inkjet printer 600 according to the present embodiment. The ink jet printer 600 can function as a printer that can print on paper or the like. In the following description, the upper side in FIG. 13 is referred to as “upper part” and the lower side is referred to as “lower part”.

  The ink jet printer 600 has an apparatus main body 620, a tray 621 for installing the recording paper P in the upper rear, a discharge port 622 for discharging the recording paper P in the lower front, and an operation panel 670 on the upper surface. Have.

  Inside the apparatus main body 620, there are mainly a printing apparatus 640 having a reciprocating head unit 630, a paper feeding apparatus 650 for feeding the recording paper P one by one to the printing apparatus 640, the printing apparatus 640 and the paper feeding apparatus 650. And a control unit 660 for controlling.

  The printing apparatus 640 includes a head unit 630, a carriage motor 641 serving as a driving source for the head unit 630, and a reciprocating mechanism 642 that receives the rotation of the carriage motor 641 to reciprocate the head unit 630.

  The head unit 630 includes an ink jet recording head 50 having a large number of the nozzles 511 described above, an ink cartridge 631 that supplies ink to the ink jet recording head 50, and the ink jet recording head 50 and the ink cartridge 631. And a carriage 632 mounted thereon.

  The reciprocating mechanism 642 includes a carriage guide shaft 643 whose both ends are supported by a frame (not shown), and a timing belt 644 extending in parallel with the carriage guide shaft 643. The carriage 632 is supported by the carriage guide shaft 643 so as to reciprocate and is fixed to a part of the timing belt 644. When the timing belt 644 travels forward and backward through a pulley by the operation of the carriage motor 641, the head unit 630 reciprocates while being guided by the carriage guide shaft 643. During this reciprocation, ink is appropriately discharged from the ink jet recording head 50 and printing on the recording paper P is performed.

  The sheet feeding device 650 includes a sheet feeding motor 651 serving as a driving source thereof, and a sheet feeding roller 652 that rotates by the operation of the sheet feeding motor 651. The paper feed roller 652 includes a driven roller 652 a and a drive roller 652 b that are opposed to each other across the feeding path (recording paper P) of the recording paper P, and the driving roller 652 b is connected to the paper feeding motor 651. Has been.

3-2. Action / Effect According to the ink jet printer 600 according to the present embodiment, as described above, since the ink jet recording head 50 having high performance and high nozzle density is provided, high density printing and high speed printing are possible. .

  The ink jet printer 600 of the present invention can also be used as a droplet discharge device used industrially. In that case, as the ink to be ejected (liquid material), various functional materials can be used by adjusting them to an appropriate viscosity with a solvent or a dispersion medium.

4). Fourth embodiment 4-1. Next, an embodiment of a piezoelectric pump having the piezoelectric element 1 according to the first embodiment will be described with reference to the drawings. 14 and 15 are schematic cross-sectional views of the piezoelectric pump 20 according to the present embodiment. In the piezoelectric pump 20 according to the present embodiment, the piezoelectric element can function as a piezoelectric actuator. 14 and 15 includes the lower electrode 4, the piezoelectric film 5, and the upper electrode 6 in the piezoelectric element 1 illustrated in FIG. 1, and the elasticity of the piezoelectric element 1 illustrated in FIG. 1. The membrane 3 is the diaphragm 24 in FIGS. 14 and 15. The substrate 2 (see FIG. 1) serves as a base 21 that constitutes a main part of the piezoelectric pump 20. The piezoelectric pump 20 includes a base 21, a piezoelectric unit 22, a pump chamber 23, a diaphragm 24, a suction side check valve 26a, a discharge side check valve 26b, a suction port 28a, and a discharge port 28b. Including.

4-2. Next, the operation of the above-described piezoelectric pump will be described. First, when a voltage is supplied to the piezoelectric portion 22, the voltage is applied in the film thickness direction of the piezoelectric film 5 (see FIG. 1). And as shown in FIG. 14, the piezoelectric part 22 bends in the direction (direction of arrow a shown in FIG. 14) where the pump chamber 23 spreads. Further, the diaphragm 24 together with the piezoelectric portion 22 bends in the direction in which the pump chamber 23 expands. For this reason, the pressure in the pump chamber 23 changes, and the fluid flows from the suction port 28a into the pump chamber 23 by the action of the check valves 26a and 26b (in the direction of arrow b shown in FIG. 14).

  Next, when the supply of voltage to the piezoelectric portion 22 is stopped, the application of voltage in the film thickness direction of the piezoelectric film 5 (see FIG. 1) is stopped. And as shown in FIG. 15, the piezoelectric part 22 bends in the direction (direction of arrow a shown in FIG. 15) where the pump chamber 23 narrows. Further, the diaphragm 24 together with the piezoelectric portion 22 bends in the direction in which the pump chamber 23 narrows. For this reason, the pressure in the pump chamber 23 changes, and the fluid is discharged from the discharge port 28b to the outside by the action of the check valves 26a and 26b (in the direction of arrow b shown in FIG. 15).

  The piezoelectric pump 20 can be used as a water cooling module for electronic equipment, for example, a personal computer, preferably a notebook personal computer. The water cooling module uses the above-described piezoelectric pump 20 for driving the coolant, and has a structure including the piezoelectric pump 20 and a circulating water channel.

4-3. Action / Effect According to the piezoelectric pump 20 according to the present embodiment, as described above, the piezoelectric film 5 of the piezoelectric portion 22 has good piezoelectric characteristics, so that fluid can be sucked and discharged efficiently. it can. Therefore, the piezoelectric pump 20 according to this embodiment can have a large discharge pressure and discharge amount. In addition, the piezoelectric pump 20 can be operated at high speed. Furthermore, the overall size of the piezoelectric pump 20 can be reduced.

5. Fifth embodiment 5-1. Surface Acoustic Wave Element Next, an example of a surface acoustic wave element according to a fifth embodiment to which the present invention is applied will be described with reference to the drawings. As shown in FIG. 16, the surface acoustic wave element 30 as an example of the present embodiment includes a substrate 11, an elastic film 12, a conductive layer 13, a piezoelectric film 14, a protective layer 15, an electrode 16, including. The substrate 11, the elastic film 12, the conductive layer 13, the piezoelectric film 14, and the protective layer 15 constitute a base 18.

  As the substrate 11, for example, a (100) single crystal silicon substrate can be used. The elastic film 12 can be made of the elastic film 3 in the piezoelectric element 1 shown in FIG. The conductive layer 13 can be composed of the lower electrode 4 in the piezoelectric element 1 shown in FIG. The piezoelectric film 14 can be composed of the piezoelectric film 5 in the piezoelectric element 1 shown in FIG. The protective layer 15 can be made of, for example, an oxide or a nitride. As the electrode 16, for example, a thin film such as aluminum can be used. The electrode 16 is an inter-digital type electrode (Inter-Digital Transducer: hereinafter referred to as “IDT electrode”). When viewed from the top, the electrode 16 has a shape such as interdigital electrodes 141, 142, 151, 152, and 153 shown in FIGS.

5-2. Action / Effect According to the surface acoustic wave device 30 according to the present embodiment, the piezoelectric film 14 formed of the piezoelectric film 5 in the piezoelectric element 1 shown in FIG. The wave element 30 itself has high performance.

6). Sixth Embodiment 6-1. Frequency Filter Next, an example of a frequency filter according to a sixth embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 17 is a diagram schematically illustrating a frequency filter that is an example of the present embodiment.

  As shown in FIG. 17, the frequency filter has a base 140. As the substrate 140, the substrate 18 of the surface acoustic wave device 30 shown in FIG. 16 can be used.

  IDT electrodes 141 and 142 are formed on the upper surface of the substrate 140. Further, sound absorbing portions 143 and 144 are formed on the upper surface of the base 140 so as to sandwich the IDT electrodes 141 and 142. The sound absorbing parts 143 and 144 absorb surface acoustic waves that propagate on the surface of the base 140. A high frequency signal source 145 is connected to the IDT electrode 141 formed on the base 140, and a signal line is connected to the IDT electrode 142.

6-2. Operation of Frequency Filter Next, the operation of the above frequency filter will be described. In the above configuration, when a high frequency signal is output from the high frequency signal source 145, the high frequency signal is applied to the IDT electrode 141, thereby generating a surface acoustic wave on the upper surface of the substrate 140. The surface acoustic wave propagated from the IDT electrode 141 to the sound absorbing portion 143 side is absorbed by the sound absorbing portion 143. Of the surface acoustic waves propagated to the IDT electrode 142 side, the specific surface acoustic wave is determined according to the pitch of the IDT electrode 142 or the like. A surface acoustic wave having a frequency or a frequency in a specific band is converted into an electric signal and taken out to terminals 146a and 146b through signal lines. Note that most of the frequency components other than the specific frequency or the frequency in the specific band pass through the IDT electrode 142 and are absorbed by the sound absorbing unit 144. In this way, it is possible to obtain (filter) only a surface acoustic wave having a specific frequency or a specific band of the electric signal supplied to the IDT electrode 141 included in the frequency filter of the present embodiment.

7). Seventh Embodiment 7-1. Oscillator Next, an example of an oscillator according to a seventh embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 18 is a diagram schematically illustrating an oscillator which is an example of the present embodiment.

  As shown in FIG. 18, the oscillator has a base 150. As the base 150, the base 18 of the surface acoustic wave device 30 shown in FIG. 16 can be used as in the frequency filter described above.

  An IDT electrode 151 is formed on the upper surface of the substrate 150, and IDT electrodes 152 and 153 are formed so as to sandwich the IDT electrode 151. A high frequency signal source 154 is connected to one comb-like electrode 151a constituting the IDT electrode 151, and a signal line is connected to the other comb-like electrode 151b. The IDT electrode 151 corresponds to an electric signal applying electrode, and the IDT electrodes 152 and 153 are used for resonance to resonate a specific frequency component of a surface acoustic wave generated by the IDT electrode 151 or a frequency component of a specific band. It corresponds to an electrode.

7-2. Next, the operation of the above-described oscillator will be described. In the above configuration, when a high-frequency signal is output from the high-frequency signal source 154, this high-frequency signal is applied to one comb-like electrode 151a of the IDT electrode 151, and thereby propagates to the IDT electrode 152 side on the upper surface of the base 150. The surface acoustic wave that propagates to the IDT electrode 153 side is generated. Among these surface acoustic waves, the surface acoustic wave having a specific frequency component is reflected by the IDT electrode 152 and the IDT electrode 153, and a standing wave is generated between the IDT electrode 152 and the IDT electrode 153. The surface acoustic wave having the specific frequency component is repeatedly reflected by the IDT electrodes 152 and 153, whereby the specific frequency component or the frequency component in the specific band resonates and the amplitude increases. A part of the surface acoustic wave of the specific frequency component or the frequency component of the specific band is extracted from the other comb-shaped electrode 151b of the IDT electrode 151, and corresponds to the resonance frequency of the IDT electrode 152 and the IDT electrode 153. An electric signal having a frequency (or a frequency having a certain band) can be taken out to the terminals 155a and 155b.

7-3. Voltage Control SAW Oscillator FIGS. 19 and 20 are diagrams schematically showing an example in which the above-described oscillator is applied to a VCSO (Voltage Controlled SAW Oscillator), and FIG. 19 is a side perspective view. FIG. 20 is a top perspective view.

  The VCSO is configured to be mounted inside a metal (Al or stainless steel) housing 60. On the substrate 61, an IC (Integrated Circuit) 62 and an oscillator 63 are mounted. In this case, the IC 62 is an oscillation circuit that controls the frequency applied to the oscillator 63 in accordance with a voltage value input from an external circuit (not shown).

  In the oscillator 63, IDT electrodes 65a to 65c are formed on a base 64, and the configuration thereof is substantially the same as that of the oscillator shown in FIG. As the base 64, the base 18 of the surface acoustic wave device 30 shown in FIG. 16 can be used, similarly to the oscillator shown in FIG. 18 described above.

  A wiring 66 for electrically connecting the IC 62 and the oscillator 63 is patterned on the substrate 61. The IC 62 and the wiring 66 are connected by a wire line 67 such as a gold wire, for example, and the oscillator 63 and the wiring 66 are connected by a wire line 68 such as a gold wire. As a result, the IC 62 and the oscillator 63 are electrically connected via the wiring 66.

  The VCSO can also be formed by integrating the IC 62 and the oscillator 63 on the same substrate. FIG. 21 shows a schematic diagram of a VCSO in which an IC 62 and an oscillator 63 are integrated on the same substrate 61. In FIG. 21, the oscillator 63 has a structure in which the formation of the conductive layer 13 is omitted in the surface acoustic wave device 30 shown in FIG.

  As shown in FIG. 21, the VCSO is formed by sharing the substrate 61 in the IC 62 and the oscillator 63. As the substrate 61, for example, the substrate 11 of the surface acoustic wave device 30 shown in FIG. 16 can be used. Although not shown, the IC 62 and the electrode 65a of the oscillator 63 are electrically connected. As the electrode 65a, for example, the electrode 16 of the surface acoustic wave element 30 shown in FIG. 16 can be used. As a transistor constituting the IC 62, a TFT (Thin Film Transistor) can be adopted.

  19 to 21 is used as, for example, a VCO (Voltage Controlled Oscillator) of the PLL circuit shown in FIG. Here, the PLL circuit will be briefly described.

  FIG. 22 is a block diagram showing a basic configuration of the PLL circuit. The PLL circuit includes a phase comparator 71, a low-pass filter 72, an amplifier 73, and a VCO 74. The phase comparator 71 compares the phase (or frequency) of the signal input from the input terminal 70 with the phase (or frequency) of the signal output from the VCO 74, and an error whose value is set according to the difference. A voltage signal is output. The low pass filter 72 passes only the low frequency component at the position of the error voltage signal output from the phase comparator 71. The amplifier 73 amplifies the signal output from the low-pass filter 72. The VCO 74 is an oscillation circuit in which the frequency that oscillates according to the input voltage value changes continuously within a certain range.

  Under such a configuration, the PLL circuit operates so that the difference between the phase (or frequency) input from the input terminal 70 and the phase (or frequency) of the signal output from the VCO 74 is reduced. Is synchronized with the frequency of the signal input from the input terminal 70. When the frequency of the signal output from the VCO 74 is synchronized with the frequency of the signal input from the input terminal 70, the frequency thereafter matches the signal input from the input terminal 70 except for a certain phase difference, and the input signal changes. A signal that follows the signal is output.

8). Eighth Embodiment Next, an example of an electronic circuit and an electronic apparatus according to an eighth embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 23 is a block diagram illustrating an electrical configuration of an electronic device 300 that is an example of the present embodiment. The electronic device 300 is, for example, a mobile phone.

  The electronic device 300 includes an electronic circuit 310, a transmitter 80, a receiver 91, an input unit 94, a display unit 95, and an antenna unit 86. The electronic circuit 310 includes a transmission signal processing circuit 81, a transmission mixer 82, a transmission filter 83, a transmission power amplifier 84, a transmission / reception duplexer 85, a low noise amplifier 87, a reception filter 88, a reception mixer 89, a reception signal processing circuit 90, and a frequency. It has a synthesizer 92 and a control circuit 93.

  In the electronic circuit 310, the frequency filter shown in FIG. 17 can be used as the transmission filter 83 and the reception filter 88. The frequency to be filtered (frequency to be passed) is individually determined by the transmission filter 83 and the reception filter 88 according to the frequency required from the signal output from the transmission mixer 82 and the frequency required by the reception mixer 89. It is set. Further, as the VCO 74 of the PLL circuit (see FIG. 22) provided in the frequency synthesizer 92, the oscillator shown in FIG. 18 or the VCSO shown in FIGS. 19 to 21 can be used.

  The transmitter 80 is realized by, for example, a microphone that converts a sound wave signal into an electric signal. The transmission signal processing circuit 81 is a circuit that performs processing such as D / A conversion processing and modulation processing on the electrical signal output from the transmitter 80. The transmission mixer 82 mixes the signal output from the transmission signal processing circuit 81 using the signal output from the frequency synthesizer 92. The transmission filter 83 passes only a signal having a frequency that requires an intermediate frequency (hereinafter referred to as “IF”) and cuts a signal having an unnecessary frequency. A signal output from the transmission filter 83 is converted into an RF signal by a conversion circuit (not shown). The transmission power amplifier 84 amplifies the power of the RF signal output from the transmission filter 83 and outputs it to the transmission / reception duplexer 85.

  The transmitter / receiver demultiplexer 85 outputs the RF signal output from the transmission power amplifier 84 to the antenna unit 86 and transmits the RF signal from the antenna unit 86 in the form of a radio wave. The transmitter / receiver demultiplexer 85 demultiplexes the received signal received by the antenna unit 86 and outputs the demultiplexed signal to the low noise amplifier 87. The low noise amplifier 87 amplifies the received signal from the transmitter / receiver demultiplexer 85. The signal output from the low noise amplifier 87 is converted into IF by a conversion circuit (not shown).

  The reception filter 88 passes only a signal having a frequency necessary for IF converted by a conversion circuit (not shown), and cuts a signal having an unnecessary frequency. The reception mixer 89 uses the signal output from the frequency synthesizer 92 to mix the signal output from the reception filter 88. The reception signal processing circuit 90 is a circuit that performs processing such as A / D conversion processing and demodulation processing on the signal output from the reception mixer 89. The receiver 91 is realized by, for example, a small speaker that converts an electric signal into a sound wave.

  The frequency synthesizer 92 is a circuit that generates a signal to be supplied to the transmission mixer 82 and a signal to be supplied to the reception mixer 89. The frequency synthesizer 92 has a PLL circuit, and can divide a signal output from the PLL circuit to generate a new signal. The control circuit 93 controls the transmission signal processing circuit 81, the reception signal processing circuit 90, the frequency synthesizer 92, the input unit 94, and the display unit 95. For example, the display unit 95 displays the state of the device to the user of the mobile phone. The input unit 94 inputs an instruction from a user of a mobile phone, for example.

  In the above-described example, a mobile phone is used as the electronic device, and an electronic circuit provided in the mobile phone is used as the electronic circuit, and the present invention is not limited to the mobile phone. The present invention can be applied to a body communication device and an electronic circuit provided therein.

  Furthermore, the present invention can be applied not only to mobile communication devices but also to communication devices used in a stationary state such as tuners that receive BS and CS broadcasts, and electronic circuits provided therein. Furthermore, not only communication devices that use radio waves propagating in the air as communication carriers, but also electronic devices such as HUBs that use high-frequency signals propagating in coaxial cables or optical signals propagating in optical cables, and the electronics provided therein It can also be applied to circuits.

9. Ninth Embodiment Next, an example of a thin film piezoelectric resonator according to a ninth embodiment to which the present invention is applied will be described with reference to the drawings.

9-1. First Thin Film Piezoelectric Resonator FIG. 24 is a diagram schematically showing a first thin film piezoelectric resonator 700 which is an example of this embodiment. The first thin film piezoelectric resonator 700 is a diaphragm type thin film piezoelectric resonator.

  The first thin film piezoelectric resonator 700 includes a substrate 701, an elastic film 703, a lower electrode 704, a piezoelectric film 705, and an upper electrode 706. The substrate 701, the elastic film 703, the lower electrode 704, the piezoelectric film 705, and the upper electrode 706 in the thin film piezoelectric resonator 700 are respectively the substrate 2, the elastic film 3, the lower electrode 4, and the piezoelectric element in the piezoelectric element 1 shown in FIG. It corresponds to the body film 5 and the upper electrode 6. That is, the first thin film piezoelectric resonator 700 has the piezoelectric element 1 shown in FIG.

  A via hole 702 that penetrates the substrate 701 is formed in the substrate 701. A wiring 708 is provided on the upper electrode 706. The wiring 708 is electrically connected to an electrode 709 formed on the elastic film 703 via a pad 710.

9-2. Action / Effect According to the first thin film piezoelectric resonator 700 according to this embodiment, the piezoelectric film 705 has good piezoelectric characteristics, and thus has a high electromechanical coupling coefficient. Thereby, the thin film piezoelectric resonator 700 can be used in a high frequency region. Further, the thin film piezoelectric resonator 700 can be reduced in size (thinned) and can be operated satisfactorily.

9-3. Second Thin Film Piezoelectric Resonator FIG. 25 is a diagram schematically showing a second thin film piezoelectric resonator 800 which is an example of this embodiment. The second thin film piezoelectric resonator 800 is mainly different from the first thin film piezoelectric resonator 700 shown in FIG. 24 in that an air gap 802 is formed between the substrate 801 and the elastic film 803 without forming a via hole. In the point.

  The second thin film piezoelectric resonator 800 includes a substrate 801, an elastic film 803, a lower electrode 804, a piezoelectric film 805, and an upper electrode 806. The substrate 801, the elastic film 803, the lower electrode 804, the piezoelectric film 805, and the upper electrode 806 in the thin film piezoelectric resonator 800 are respectively the substrate 2, the elastic film 3, the lower electrode 4, and the piezoelectric body in the piezoelectric element 1 shown in FIG. It corresponds to the film 5 and the upper electrode 6. That is, the second thin film piezoelectric resonator 800 has the piezoelectric element 1 shown in FIG. The air gap 802 is a space formed between the substrate 801 and the elastic film 803.

9-4. Action / Effect According to the second thin film piezoelectric resonator 800 according to this embodiment, the piezoelectric film 805 has good piezoelectric characteristics, and thus has a high electromechanical coupling coefficient. Thereby, the thin film piezoelectric resonator 800 can be used in a high frequency region. Further, the thin film piezoelectric resonator 800 can be reduced in size (thinned) and can be operated satisfactorily.

9-5. Application Example The piezoelectric thin film resonator according to the present embodiment (for example, the first thin film piezoelectric resonator 700 and the second thin film piezoelectric resonator 800) can function as a resonator, a frequency filter, or an oscillator. For example, in the electronic circuit 310 shown in FIG. 23, as the transmission filter 83 and the reception filter 88, the piezoelectric thin film resonator according to the present embodiment functioning as a frequency filter can be used. In addition, as the oscillator included in the frequency synthesizer 92, the piezoelectric thin film resonator according to the present embodiment functioning as an oscillator can be used.

  Although the embodiments of the present invention have been described in detail as described above, those skilled in the art will readily understand that many variations are possible without substantially departing from the novel matters and effects of the present invention. . Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, the piezoelectric element according to the present invention is applicable not only to the above-described device but also to various devices. For example, the piezoelectric element according to the present invention can be used as a piezoelectric actuator for driving a lens in an optical zoom mechanism of a camera (including those mounted on a mobile phone or a PDA: Personal Digital Assistant).

1 is a cross-sectional view schematically showing a piezoelectric element according to a first embodiment. Graph showing relative degree of deformation of the shear mode, the total energy per unit cell of PbTiO _3, the results obtained by the first principle electronic state simulation. The figure which shows typically the lattice model used for simulation. The figure which shows typically the change of the polarization axis direction of a crystal | crystallization. An example of a phase diagram of PZT. Sectional drawing which shows typically the manufacturing process of the piezoelectric element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric element which concerns on 1st Embodiment. FIG. 5 is a schematic configuration diagram of an ink jet recording head according to a second embodiment. FIG. 6 is an exploded perspective view of an ink jet recording head according to a second embodiment. FIG. 4 is a diagram for explaining the operation of an ink jet recording head. FIG. 4 is a diagram for explaining the operation of an ink jet recording head. FIG. 9 is a schematic configuration diagram of an ink jet printer according to a third embodiment. The schematic sectional drawing of the piezoelectric pump which concerns on 4th Embodiment. The schematic sectional drawing of the piezoelectric pump which concerns on 4th Embodiment. FIG. 10 is a side sectional view showing a surface acoustic wave device according to a fifth embodiment. The perspective view which shows the frequency filter which concerns on 6th Embodiment. The perspective view which shows the oscillator which concerns on 7th Embodiment. Schematic which shows an example which applied the oscillator concerning 7th Embodiment to VCSO. Schematic which shows an example which applied the oscillator concerning 7th Embodiment to VCSO. Schematic which shows an example which applied the oscillator concerning 7th Embodiment to VCSO. The block diagram which shows the basic composition of a PLL circuit. The block diagram which shows the structure of the electronic circuit which concerns on 8th Embodiment. FIG. 10 is a side sectional view showing a thin film piezoelectric resonator according to a ninth embodiment. FIG. 10 is a side sectional view showing a thin film piezoelectric resonator according to a ninth embodiment.

Explanation of symbols

1 piezoelectric element, 2 substrate, 3 elastic film, 4 lower electrode, 5 piezoelectric film, 6 upper electrode, 11 substrate, 12 elastic film, 13 conductive layer, 14 piezoelectric film, 15 protective layer, 16 electrode, 18 substrate, 20 piezoelectric pump, 21 base, 22 piezoelectric section, 23 pump chamber, 24 vibration plate, 30 surface acoustic wave element, 50 ink jet recording head, 51 nozzle plate, 52 ink chamber substrate, 54 piezoelectric section, 55 elastic film, 56 base 57 head body, 58 ink droplets, 60 housing, 61 substrate, 63 oscillator, 64 substrate, 66 wiring, 67 wire lines, 70 input terminals, 71 phase comparator, 72 low-pass filter, 73 amplifier, 80 transmitter , 81 Transmission signal processing circuit, 82 Transmission mixer, 83 Transmission filter, 84 Transmission power amplifier, 85 Transmitter / receiver demultiplexer, 86 Antenna unit, 8 7 Low noise amplifier, 88 reception filter, 89 reception mixer, 90 reception signal processing circuit, 91 reception unit, 92 frequency synthesizer, 93 control circuit, 94 input unit, 95 display unit, 140 base, 141 electrode, 142 electrode, 143 sound absorption Part, 144 sound absorbing part, 145 high frequency signal source, 150 base, 151 electrode, 152 electrode, 153 electrode, 154 high frequency signal source, 300 electronic equipment, 310 electronic circuit, 511 nozzle, 521 cavity, 522 side wall, 523 reservoir, 524 Supply port, 531 communication hole, 600 inkjet printer, 620 apparatus main body, 621 tray, 622 discharge port, 630 head unit, 631 ink cartridge, 632 carriage, 640 printing device, 641 carriage motor, 642 reciprocating machine Structure, 643 carriage guide shaft, 644 timing belt, 650 sheet feeding device, 651 sheet feeding motor, 652 sheet feeding roller, 660 control unit, 670 operation panel, 700 first thin film piezoelectric resonator, 701 substrate, 702 via hole, 703 Elastic film, 704 Lower electrode, 705 Piezoelectric film, 706 Upper electrode, 708 Wiring, 709 electrode, 710 Pad, 800 Second thin film piezoelectric resonator, 801 Substrate, 802 Air gap, 803 Elastic film, 804 Lower electrode, 805 Piezoelectric film, 806 Upper electrode

Claims (17)

A perovskite-type piezoelectric film,
Preferentially oriented to pseudo cubic (100),
Has a monoclinic structure,
A piezoelectric film in which a polarization axis direction is between a pseudo cubic <111> direction and a pseudo cubic <100> direction. In claim 1,
An angle δ formed by the polarization axis direction and the pseudo cubic <111> direction is a piezoelectric film in a range of 0.0 ° <δ ≦ 10.0 °. In claim 1 or 2,
Pb (Zr _1-x Ti _x ) O ₃
x is a piezoelectric film having a range of 0.43 ≦ x ≦ 0.53.   A piezoelectric element having the piezoelectric film according to claim 1. A piezoelectric element having a perovskite-type piezoelectric film,
A substrate,
A lower electrode formed above the substrate;
A piezoelectric film formed above the lower electrode;
An upper electrode formed above the piezoelectric film,
The piezoelectric film is preferentially oriented to pseudo cubic (100),
In the state where an electric field in the pseudo cubic <100> direction is generated in the piezoelectric film,
The piezoelectric element has a monoclinic structure, and a polarization axis direction of the piezoelectric film is between a pseudo cubic <111> direction and a pseudo cubic <100> direction. In claim 5,
An angle δ formed by the polarization axis direction of the piezoelectric film and the pseudo cubic <111> direction is a range of 0.0 ° <δ ≦ 10.0 °. In claim 5 or 6,
The piezoelectric film is made of Pb (Zr _1-x Ti _x ) O ₃ ,
x is a piezoelectric element having a range of 0.43 ≦ x ≦ 0.53.   A piezoelectric actuator comprising the piezoelectric element according to claim 4.   A piezoelectric pump comprising the piezoelectric element according to claim 4.   An ink jet recording head comprising the piezoelectric element according to claim 4.   An ink jet printer comprising the ink jet recording head according to claim 10.   A surface acoustic wave element comprising the piezoelectric element according to claim 4.   A thin film piezoelectric resonator comprising the piezoelectric element according to claim 4.   A frequency filter comprising at least one of the surface acoustic wave device according to claim 12 and the thin film piezoelectric resonator according to claim 13.   An oscillator comprising at least one of the surface acoustic wave device according to claim 12 and the thin film piezoelectric resonator according to claim 13.   An electronic circuit comprising at least one of the frequency filter according to claim 14 and the oscillator according to claim 15.   An electronic apparatus comprising at least one of the piezoelectric pump according to claim 9 and the electronic circuit according to claim 16.

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