JP6964511B2 - Piezoelectric laminate, manufacturing method of piezoelectric laminate and piezoelectric element - Google Patents

Description

The present invention relates to a piezoelectric laminate, a method for manufacturing a piezoelectric laminate, and a piezoelectric element.

Piezoelectric bodies are widely used in functional electronic components such as sensors and actuators. As the material of the piezoelectric body, lead-based materials, in particular, ferroelectric PZT system represented by a composition formula _{Pb (Zr 1-x Ti x} ) O 3 has been widely used. The PZT-based piezoelectric material contains about 60 to 70 wt% of lead, which is not preferable from the viewpoint of pollution prevention. Currently, various lead-free piezoelectric materials are being studied, among which alkaline niobium oxides having a perovskite structure (sodium niobate, sodium niobate _{) represented by the composition formula (K 1-x} Na _x ) NbO _{3 are being studied.} Hereinafter, there is also KNN (see, for example, Patent Documents 1 and 2). KNN exhibits relatively good piezoelectric properties and is expected to be a promising candidate for lead-free piezoelectric materials. Further, in recent years, there has been a strong demand for a piezoelectric material having a higher piezoelectric constant.

JP-A-2007-184513 Japanese Unexamined Patent Publication No. 2008-159807

An object of the present invention is to provide a piezoelectric laminate formed of an alkali niobium oxide, which comprises a piezoelectric film having a higher piezoelectric constant, and related techniques thereof.

According to one aspect of the invention
A substrate and a piezoelectric film formed on the substrate are provided.
The piezoelectric film is a piezoelectric laminate which is a single crystal epitaxial film composed of an alkali niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x ) NbO _{3 (0 <x <1) and its relations.} Technology is provided.

According to the present invention, it is possible to provide a piezoelectric laminate formed of an alkali niobium oxide and having a piezoelectric film having a higher piezoelectric constant, and related techniques thereof.

It is a figure which shows an example of the cross-sectional structure of the piezoelectric laminated body which concerns on one Embodiment of this invention. It is a figure which shows the schematic structure of the piezoelectric device which concerns on one Embodiment of this invention. (A) is a diagram showing a modified example of the cross-sectional structure of the buffer layer included in the piezoelectric laminate according to the embodiment of the present invention, and (b) is a diagram provided by the piezoelectric laminate according to the embodiment of the present invention. It is a figure which shows the other modification of the cross-sectional structure of a buffer layer. It is a figure which shows the schematic structure of the piezoelectric device which concerns on other embodiment of this invention.

<One Embodiment of the present invention>
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(1) Configuration of piezoelectric laminate As shown in FIG. 1, the laminate (laminated substrate) 10 having the piezoelectric film according to the present embodiment (hereinafter, also referred to as piezoelectric laminate 10) is on the substrate 1 and the substrate 1. The buffer layer 7 formed in the buffer layer 7, the lower electrode film (first electrode film) 2 formed on the buffer layer 7, the piezoelectric film (piezoelectric thin film) 3 formed on the lower electrode film 2, and piezoelectric film. An upper electrode film (second electrode film) 4 formed on the film 3 is provided.

As the substrate 1, a substrate made of single crystal silicon (Si) can be preferably used. Further, as the substrate 1, a substrate made of single crystal strontium titanate (SrTIO ₃ ), single crystal magnesium oxide (MgO), and single crystal fluorite (calcium fluoride, CaF ₂ ) can also be used. Further, as the substrate 1, an SOI (Silicon On Insulator) substrate having a silicon layer made of single crystal Si can also be used. _{Further, as the substrate 1, a single crystal Si substrate on which a surface oxide film (SiO 2} film) such as a thermal oxide film or a CVD (Chemical Vapor Deposition) oxide film is formed, that is, a Si substrate having a surface oxide film is used. You can also. The substrate 1 has a thickness of, for example, 300 to 1000 μm.

For the buffer layer 7, for example _{, zirconia stabilized with an oxide (Y 2} O ₃ ) of yttrium (Y) (composition formula (ZrO ₂ ) _1-x (Y ₂ O ₃ ) _x , abbreviation: YSZ) is used. Can be formed by The composition of the buffer layer 7 is preferably such that the crystal structure of the buffer layer 7 is cubic (cubic structure, cubic phase). For example, it is preferable that the coefficient x in the above composition formula has a size within the range of 0.065 ≦ x ≦ 0.155. The buffer layer 7 has a thickness of, for example, 5 to 300 nm, preferably 10 to 200 nm.

By forming the buffer layer 7 directly on the substrate 1, the buffer layer 7 grows epitaxially and becomes a single crystal epitaxial film. By providing the buffer layer 7 on the substrate 1, the difference in lattice constant between the substrate 1 (single crystal Si) and the KNN film 3 can be alleviated. As a result, as will be described later, the lower electrode film 2 and the KNN film 3 can be made into a single crystal epitaxial film.

The buffer layer 7 can be formed by using a method such as a PLD (Pulsed Laser Deposition) method or a sputtering method. Among these methods, it is preferable to form the buffer layer 7 by the PLD method, whereby an amorphous silicon oxide layer (SiO ₂ layer) is formed at the interface between the substrate 1 and the buffer layer 7. It can be suppressed. As a result, the disorder of the crystallinity of the buffer layer 7 can be suppressed, and the buffer layer 7 can be easily epitaxially grown on the substrate 1.

In order to enhance the adhesion between the substrate 1 and the buffer layer 7, for example, adhesion containing titanium (Ti), tantalum (Ta), titanium oxide (TIO ₂ ), nickel (Ni) or the like as main components is achieved. Layer 6 may be provided. The adhesion layer 6 can be formed by using a method such as a sputtering method or a vapor deposition method. The adhesion layer 6 has a thickness of, for example, 1 to 200 nm. When the close contact layer 6 is provided, it is preferable to perform a cleaning treatment using a buffered hydrofluoric acid (BHF) solution on the substrate 1.

The lower electrode film 2 can be formed by using, for example, platinum (Pt). By directly forming the lower electrode film 2 on the buffer layer 7, the lower electrode film 2 grows epitaxially and becomes a single crystal epitaxial film (hereinafter, this is also referred to as a Pt film). The crystals constituting the Pt film are preferably oriented in the (111) plane orientation with respect to the surface of the substrate 1. That is, it is preferable that the surface of the Pt film (the surface serving as the base of the piezoelectric film 3) is composed of the Pt (111) surface. The Pt film can be formed by using a method such as a sputtering method or a vapor deposition method. In addition to Pt, the lower electrode film 2 includes various metals such as gold (Au), ruthenium (Ru), and iridium (Ir), alloys containing these as main components, strontium ruthenate (SrRuO ₃ ), and lanthanum nickelate (LaNiO). It is also possible to form a film using a metal oxide such as _3). For example, when the lower electrode film 2 is formed using _{SrRuO 3 , the SrRuO 3} film is preferably oriented in the (100) plane orientation with respect to the surface of the substrate 1. That is, it is preferable that the surface of the _{SrRuO 3 film is composed of SrRuO 3} (100) planes. The lower electrode film 2 has a thickness of, for example, 100 to 400 nm.

The piezoelectric film 3 contains, for example, potassium (K), sodium (Na), and niobium (Nb), and is an alkaline niobium oxide represented by _{the composition formula (K 1-x} Na _x ) NbO _{3, that is, potassium niobate.} A film can be formed by using sodium (KNN). The coefficient x [= Na / (K + Na)] in the above composition formula has a magnitude within the range of 0 <x <1, preferably 0.4 ≦ x ≦ 0.7. By forming the piezoelectric film 3 directly on the lower electrode film 2, the piezoelectric film 3 grows epitaxially on the lower electrode film 2, and is a single crystal epitaxial film of KNN (hereinafter referred to as KNN film 3 or single crystal KNN). Also referred to as film 3). When the buffer layer 7 is not provided as in the conventional piezoelectric laminate, the KNN film that grows on the lower electrode film 2 becomes a polycrystalline film. The crystal structure of KNN is a perovskite structure. The KNN film 3 has a thickness of, for example, 0.5 to 5 μm.

The crystals constituting the KNN film 3 are preferably oriented in the (001) plane orientation with respect to the surface of the substrate 1. That is, it is preferable that the surface of the KNN film 3 (the surface serving as the base of the upper electrode film 4) is composed of the KNN (001) surface. By directly forming the KNN film 3 on the Pt film (lower electrode film 2) oriented in the (111) plane direction with respect to the surface of the substrate 1, the crystals constituting the KNN film 3 are formed on the surface of the substrate 1. It becomes easy to orient the film in the (001) plane direction.

The KNN film 3 can be formed by using a method such as a sputtering method, a PLD method, or a sol-gel method. The composition ratio of the KNN film 3 can be adjusted, for example, by controlling the composition of the target material used during sputtering film formation. The target material can be produced, for example, _{by mixing K 2} CO ₃ powder, Na ₂ CO ₃ powder, Nb ₂ O ₅ powder and the like and firing them. In this case, the composition of the target material can be controlled by adjusting the mixing ratio of _{K 2} CO ₃ powder, Na ₂ CO ₃ powder, Nb ₂ O _{5 powder and the like.} As the atmosphere gas at the time of sputtering the KNN film 3, for example, a mixed gas (Ar + O ₂ mixed gas) of an _{argon (Ar) gas and an oxygen (O 2) gas is used.}

The KNN film 3 contains elements other than K, Na, and Nb such as copper (Cu), manganese (Mn), lithium (Li), tantalum (Ta), and antimony (Sb) within a range of 5 at% or less. You may.

The upper electrode film 4 can be formed by using, for example, various metals such as Pt, Au, aluminum (Al), and Cu, or alloys thereof. The upper electrode film 4 can be formed by using a method such as a sputtering method, a vapor deposition method, a plating method, or a metal paste method. The upper electrode film 4 does not have a great influence on the crystal structure of the KNN film 3 like the lower electrode film 2. Therefore, the material, crystal structure, and film forming method of the upper electrode film 4 are not particularly limited. In addition, in order to enhance the adhesion between the KNN film 3 and the upper electrode film 4, for example, _{an adhesion layer containing Ti, Ta, TiO 2} , Ni or the like as a main component may be provided. The upper electrode film 4 has a thickness of, for example, 100 to 5000 nm. When the adhesion layer is provided, the adhesion layer has a thickness of, for example, 1 to 200 nm.

(2) Configuration of Piezoelectric Device FIG. 2 shows a schematic configuration diagram of a device 30 having a piezoelectric film (hereinafter, also referred to as a piezoelectric device 30) according to the present embodiment. The piezoelectric device 30 includes an element 20 (element 20 having a piezoelectric film, hereinafter also referred to as a piezoelectric element 20) obtained by molding the above-mentioned piezoelectric laminate 10 into a predetermined shape, and a voltage application connected to the piezoelectric element 20. At least a unit 11a or a voltage detection unit 11b is provided. The voltage application unit 11a is a means for applying a voltage between the lower electrode film 2 and the upper electrode film 4, and the voltage detection unit 11b is between the lower electrode film 2 and the upper electrode film 4. It is a means for detecting the generated voltage. Known means can be used as the voltage application unit 11a and the voltage detection unit 11b.

By connecting the voltage application unit 11a between the lower electrode film 2 and the upper electrode film 4 of the piezoelectric element 20, the piezoelectric device 30 can function as an actuator. The KNN film 3 can be deformed by applying a voltage between the lower electrode film 2 and the upper electrode film 4 by the voltage applying portion 11a. By this deformation operation, various members connected to the piezoelectric device 30 can be operated. In this case, applications of the piezoelectric device 30 include, for example, a head for an inkjet printer, a MEMS mirror for a scanner, a vibrator for an ultrasonic generator, and the like.

By connecting the voltage detection unit 11b between the lower electrode film 2 and the upper electrode film 4 of the piezoelectric element 20, the piezoelectric device 30 can function as a sensor. When the KNN film 3 is deformed due to some change in physical quantity, a voltage is generated between the lower electrode film 2 and the upper electrode film 4 due to the deformation. By detecting this voltage by the voltage detection unit 11b, the magnitude of the physical quantity applied to the KNN film 3 can be measured. In this case, applications of the piezoelectric device 30 include, for example, an angular velocity sensor, an ultrasonic sensor, a pressure sensor, an acceleration sensor, and the like.

(3) Method for Manufacturing Piezoelectric Laminates, Piezoelectric Elements, and Piezoelectric Devices Next, the method for manufacturing the above-mentioned piezoelectric laminate 10 will be described. First, the buffer layer 7 is formed on any of the main surfaces of the substrate 1 by using, for example, the PLD method. The following conditions are exemplified as processing conditions for forming the buffer layer 7. Then, the lower electrode film 2 is formed on the buffer layer 7 by using, for example, an RF magnetron sputtering method. A substrate 1 in which the buffer layer 7 and the lower electrode film 2 are provided in advance on any of the main surfaces may be prepared. Subsequently, a KNN film 3 is formed on the lower electrode film 2 by using, for example, an RF magnetron sputtering method. The following conditions are exemplified as the treatment conditions for forming the KNN film 3. Then, the upper electrode film 4 is formed on the KNN film 3 by using, for example, an RF magnetron sputtering method. As a result, the piezoelectric laminate 10 is obtained. Then, the piezoelectric element 20 is obtained by molding the piezoelectric laminate 10 into a predetermined shape by etching or the like, and the piezoelectric device 30 is obtained by connecting the voltage application unit 11a or the voltage detection unit 11b to the piezoelectric element 20. Be done.

(Example of processing conditions when forming a buffer layer)
Introduced gas: O ₂ gas O ₂ gas Atmospheric pressure: 7.3 × 10 ^-2 Pa
Laser frequency: 7Hz
Substrate temperature when forming the above-mentioned layer other than the LSCO layer: 800 ° C.
Substrate temperature when forming the LSCO layer: 550 ° C

(Example of processing conditions for lower electrode film and upper electrode film formation)
Substrate temperature: 300 ° C
Discharge power: 1200W
Introduced gas: Ar gas Ar gas Atmospheric pressure: 0.3Pa
Film formation time: 5 minutes

(Example of processing conditions for KNN film formation)
Substrate temperature: 600 ° C
Discharge power: 2200W
Introduced gas: Ar + O ₂ mixed gas Ar + O ₂ mixed gas Atmospheric pressure: 0.3 Pa
Partial pressure of Ar gas to O _{2 gas (Ar / O 2} partial pressure ratio): 25/1
Film formation speed: 1 μm / hr

When the adhesion layer 6 between the substrate 1 and the buffer layer 7 and the adhesion layer between the KNN film 3 and the upper electrode film 4 are provided, the processing conditions for forming the adhesion layer are the above-mentioned lower electrode film and the upper portion. The conditions can be the same as the processing conditions at the time of forming the electrode film.

(4) Effects obtained by the present embodiment According to the present embodiment, one or more of the following effects can be obtained.

(A) By using the KNN film 3 as a single crystal epitaxial film, the piezoelectric characteristics can be improved as compared with the polycrystalline KNN film. For example, the absolute value of the piezoelectric constant of the KNN film 3 (for example, | d ₃₁ |) can be made much higher than that of the polycrystalline KNN film. As a result, when the piezoelectric device 30 functions as an actuator, the piezoelectric device 30 having a single crystal KNN film 3 (the piezoelectric device 30 according to the present embodiment) and the piezoelectric device having a polycrystalline KNN film are used, respectively. When the same voltage is applied, the amount of deformation of the single crystal KNN film 3 is larger than the amount of deformation of the polycrystalline KNN film. That is, when the single crystal KNN film 3 and the polycrystalline KNN film are deformed by the same amount, the voltage applied to the single crystal KNN film 3 can be smaller than the voltage applied to the polycrystalline KNN film. As a result, the power consumption can be reduced as compared with the piezoelectric device having a polycrystalline KNN film.

(B) The single crystal KNN film 3 does not have a plurality of crystal particles and grain boundaries unlike the polycrystalline KNN film. Therefore, when the piezoelectric device 30 according to the present embodiment functions as a sensor, the attenuation of waves such as sound waves and elastic waves propagating in the KNN film 3 is less than that of the piezoelectric device having a polycrystalline KNN film. As a result, the piezoelectric device 30 according to the present embodiment has higher sensor characteristics (for example, measurement responsiveness) than the conventional piezoelectric device having a polycrystalline KNN film.

(C) Since the single crystal KNN film 3 does not have a plurality of crystal particles and grain boundaries unlike the polycrystalline KNN film, the piezoelectric laminate 10 having the single crystal KNN film 3 has a predetermined shape. It is not affected by the grain boundaries when it is molded into. Therefore, it becomes easier to process the KNN film 3 with higher accuracy than the polycrystalline KNN film.

(D) Since the piezoelectric film is a KNN film 3, that is, a lead-free film formed of an alkali niobium oxide, it is also preferable from the viewpoint of pollution prevention.

(5) Modification Example This embodiment is not limited to the above-described embodiment, and can be modified as follows, for example.

(Modification example 1)
For example, in the buffer layer 7, in addition to the above-mentioned YSZ, _{zirconia stabilized with an oxide of Sc (Sc 2} O ₃ ) (composition formula (ZrO ₂ ) _1-x (Sc ₂ O ₃ ) _x , abbreviation: ScSZ ) May be used. In this modification, the crystal structure of the buffer layer 7 can be a cubic phase by setting the coefficient x in the composition formula to, for example, a size within the range of 0.085 ≦ x ≦ 0.095. ScSZ has a composition range in which the crystal structure is in the cubic phase (range of the coefficient x in the above composition formula) is narrower than that of YSZ, but has better oxygen ion conductivity than YSZ. Therefore, when the buffer layer 7 is directly formed on the substrate 1 using ScSZ, oxygen (O) can be desorbed from the interface between the substrate 1 (Si) and the buffer layer 7 (ScSZ), and the substrate can be desorbed. It is possible to suppress the formation _{of an amorphous SiO 2} layer at the interface between 1 and the buffer layer 7. As a result, the disorder of the crystallinity of the buffer layer 7 can be suppressed, and the buffer layer 7 can be stably epitaxially grown in the plane of the substrate 1. Further, by forming the buffer layer 7 using ScSZ, it is possible to suppress the formation _{of the SiO 2} layer described above even when the buffer layer 7 is formed by the sputtering method instead of the PLD method. The sputtering method is preferable to the PLD method in terms of large diameter and mass productivity. Also in this modification, the lower electrode film 2 and the KNN film 3 can be epitaxially grown, and the same effect as that of the above-described embodiment can be obtained.

(Modification 2)
For example, the buffer layer 7 is made from yttrium (Y), scandium (Sc), itterbium (Yb), erbium (Er), dysprosium (Dy), gadolinium (Gd) and europium (Eu) in addition to the above-mentioned YSZ and ScSZ. It may be formed using zirconia stabilized with an oxide of one or more rare earth elements selected from the group. That is, the buffer layer 7 is, for example, an oxide (Ln) of a lanthanoid (Ln) represented by _{the composition formula (ZrO 2} ) _1-x (Ln ₂ O ₃ ) _{x (for example, 0.07 ≦ x ≦ 0.11).} It can be formed by using zirconia stabilized in ₂ O _3). Lanthanoid is a general term for Y, Sc, Yb, Er, Dy, Gd and Eu. Further, for example, the buffer layer 7 may be formed by using _{γ-alumina (γ-Al 2} O _3). Also in this modification, the lower electrode film 2 and the KNN film 3 can be epitaxially grown, and the same effect as that of the above-described embodiment can be obtained.

(Modification example 3)
Further, as illustrated in FIG. 3A, when a Si substrate in which the surface crystals are oriented in the (100) plane orientation is used as the substrate 1, the buffer layer 7 is formed by the above-mentioned Ln oxide (Ln ₂ O). _A layer made of zirconia stabilized in 3) (hereinafter, also referred to as LnSZ layer) 7a, a layer 7b made of _{cerium oxide (CeO 2 ), and a layer 7c made of lanthanum strontium cobaltite (LaSrCoO 3} , abbreviated as LSCO). It may be formed by laminating in this order from the side of the substrate 1. It is preferable that the crystals constituting the LnSZ layer 7a, the CeO ₂ layer 7b, and the LSCO layer 7c are respectively oriented in the (100) plane orientation with respect to the surface of the substrate 1. When the buffer layer 7 is formed by laminating a plurality of layers in this way, it is preferable that the total thickness of the plurality of layers is within the range described in the above-described embodiment. When the LnSZ layer 7a is the YSZ layer in this modification, the composition of the LSCO layer 7c is preferably _{La 0.5} Sr _0.5 CoO _3. Further, as an example of the thickness of each layer in this case, the YSZ layer: 20 to 25 _{nm, the CeO 2} layer: 30 nm, and the LSCO layer: 50 nm can be mentioned. Also in this modification, the lower electrode film 2 and the KNN film 3 can be epitaxially grown, and the same effects as those in the above-described embodiment and modification can be obtained.

(Modification example 4)
Further, as illustrated in FIG. 3B, when a Si substrate in which the surface crystals are oriented in the (111) plane direction is used as the substrate 1, the buffer layer 7 is composed of layers 7d and Pt _{made of CeO 2.} The layer 7f composed of the layer 7e and the LaNiO ₃ may be formed by laminating in this order from the side of the substrate 1. The _{crystals constituting the CeO 2} layer 7d and the Pt layer 7e are preferably oriented in the (111) plane direction with respect to the surface of the substrate 1, and the crystals constituting the _{LaNiO 3 layer 7f are the surfaces of the substrate 1.} It is preferable that it is oriented in the (100) plane direction. That is, in this modification, _{it is preferable that the LaNiO 3} layer 7f also functions as an orientation conversion layer. As for the thickness of the buffer layer 7 in this modification, it is preferable that the total thickness of the buffer layers 7 is within the range described in the above-described embodiment as in the case of modification 3. Also in this modification, the lower electrode film 2 and the KNN film 3 can be epitaxially grown, and the same effects as those in the above-described embodiment and modification can be obtained.

(Modification 5)
Further, for example, in the above-mentioned modified examples 3 and 4, the CeO ₂ layers 7b and 7d are formed by using a samarium (Sm) -doped ceria oxide, that is, a samarium-doped ceria (chemical formula: SmCeO _x , abbreviated as SDC). The layer may be formed by using a Gd-doped ceria oxide, that is, a gadolinium-doped toceria (chemical formula: GdCeO _{x, abbreviated as GDC).} In this modification, the doping amount of Sm or Gd can be, for example, a concentration of 10 mol%. An example of the composition of SDC is Sm _0.1 Ce _0.9 O _1.95 , and an example of the composition of GDC is Gd _0.1 Ce _0.9 O _1.95 . SDC and GDC have good oxygen ion conductivity like ScSZ. _{Therefore, since the buffer layer 7 has the SDC layer or the GDC layer, the amorphous SiO 2} layer is formed at the interface between the SDC layer or the GDC layer and the layer adjacent to the SDC layer or the layer adjacent to the SDC layer or the GDC layer as in the first modification. It can be suppressed from being formed. Also in this modification, the lower electrode film 2 and the KNN film 3 can be epitaxially grown, and the same effects as those in the above-described embodiment and modification can be obtained.

<Other embodiments>
The embodiments of the present invention have been specifically described above. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist thereof.

For example, the above-mentioned piezoelectric device 30 may function as a filter device such as a surface acoustic wave (SAW) filter. FIG. 4 shows a schematic configuration diagram of the piezoelectric device 30A capable of functioning as a SAW device. As shown in FIG. 4, the piezoelectric device 30A includes a piezoelectric element 20A obtained by molding a piezoelectric laminate 10A into a predetermined shape, and a voltage applying unit 11a and a voltage detecting unit 11b connected to the piezoelectric element 20A. At least I have it.

The piezoelectric laminate 10A is formed on the substrate 1, the buffer layer 7 formed on the substrate 1, the single crystal KNN film (piezoelectric film) 3 formed on the buffer layer 7, and the KNN film 3. The electrode film 4 is provided. An adhesion layer 6 is provided between the substrate 1 and the buffer layer 7 in order to improve the adhesion thereof.

The piezoelectric element 20A has a pattern electrode obtained by molding the upper electrode film 4 into a predetermined pattern. The piezoelectric element 20A includes a pair of positive and negative pattern electrodes 4p ₁ on the input side (voltage application), and a pair of positive and negative pattern electrodes 4p ₂ on the output side (voltage detection), the. The pattern electrodes 4p ₁ and 4p ₂ are formed as comb-shaped electrodes (IDTs) having, for example, a base and a plurality of electrode fingers extending from the base and arranged at equal intervals. ing.

In the piezoelectric device 30A, is connected with a voltage application unit 11a between the pattern electrode 4p _1, connect the voltage detection unit 11b between the pattern electrodes 4p _2. By applying a voltage between the pattern electrode 4p ₁ by the voltage application section 11a, SAW is excited on the surface of the KNN layer 3. For example, by adjusting the pitch between adjacent electrode fingers of the pattern electrode 4p _1, it is possible to adjust the frequency of the SAW that excited. For example, the frequency of the SAW is increased as described above of the pitch of the pattern electrodes 4p ₁ is shortened, the frequency of the SAW as pitch described above is longer decreases. Is excited by the voltage application unit 11a, among the SAW having reached the pattern electrode 4p ₂ propagates the KNN film 3, a predetermined determined according to the pitch or the like between adjacent electrode fingers of the pattern electrode 4p ₂ frequency (frequency components) A voltage is generated between the pattern electrodes 4p _{2 by the SAW having.} By detecting this voltage by the voltage detection unit 11b, it is possible to extract the SAW having a predetermined frequency from the excited SAWs. The term "predetermined frequency" here may include not only a predetermined frequency but also a predetermined frequency band in which the center frequency is a predetermined frequency. The same effect as that of the above-described embodiment can be obtained by this modification as well.

Further, for example, in the above-described embodiment, when the piezoelectric laminate is molded into a piezoelectric element, as long as the piezoelectric device manufactured by using the piezoelectric laminate (piezoelectric element) can be applied to a desired application such as an actuator or a sensor. , The substrate may be removed from the piezoelectric laminate.

<Preferable Aspect of the Present Invention>
Hereinafter, preferred embodiments of the present invention will be added.

(Appendix 1)
According to one aspect of the invention
A substrate and a piezoelectric film formed on the substrate are provided.
As the piezoelectric film, a piezoelectric laminate which is a single crystal epitaxial film composed of an alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x ) NbO _{3 (0 <x <1) is provided.} NS.

(Appendix 2)
The laminated body of Appendix 1, preferably
Between the substrate and the piezoelectric film (on the substrate), lanthanoids (one or more rare earth elements selected from the group consisting of yttrium, scandium, yttrium, erbium, displosium, gadolinium and europium) An oxide-stabilized zirconia buffer layer, a γ-alumina buffer layer, a lanthanoid oxide-stabilized zirconia layer, a cerium oxide layer, and a lanthanstrontium cobaltite layer. Is a buffer layer in which is laminated in this order from the substrate side, or a buffer layer in which a layer made of cerium oxide, a layer made of platinum, and a layer made of lanthanate nickate are laminated in this order from the side of the substrate. Either is provided.

(Appendix 3)
The laminated body of Appendix 2, preferably
An electrode film is provided between the buffer layer and the piezoelectric film.

(Appendix 4)
It is a laminate of Appendix 2 or 3, preferably
An electrode film is provided on the piezoelectric film.

(Appendix 5)
It is a laminated body according to any one of Supplementary note 1 to 4, and is preferable.
The substrate is a substrate made of any one of single crystal silicon, strontium titanate, single crystal magnesium oxide, or single crystal fluorite, or an SOI substrate having a silicon layer made of single crystal silicon.

(Appendix 6)
It is a laminated body according to any one of Appendix 3-5, and is preferable.
The electrode film is a single crystal film.

(Appendix 7)
According to yet another aspect of the invention.
A step of forming a single crystal piezoelectric film by epitaxially growing an alkali niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _{x ) NbO 3 (0 <x <1) on a substrate.} A method for producing a piezoelectric laminate having a structure is provided.

(Appendix 8)
The method of Appendix 7, preferably
On the substrate, a buffer layer made of zirconia stabilized with an oxide of lanthanoid, a buffer layer made of γ-alumina, a layer made of zirconia stabilized with an oxide of lanthanoid, a layer made of cerium oxide, and lanthanum. A buffer layer in which a layer made of strontium cobaltite is laminated in this order from the side of the substrate, or a layer made of cerium oxide, a layer made of platinum, and a layer made of lanthanum nickate are formed in this order from the side of the substrate. Further comprising the step of forming any of the laminated buffer layers,
In the step of forming the piezoelectric film, the piezoelectric film is formed on the buffer layer.

(Appendix 9)
The method of Appendix 8, preferably
Further having a step of forming an electrode film on the buffer layer,
In the step of forming the piezoelectric film, the piezoelectric film is formed on the electrode film.

(Appendix 10)
The method of Appendix 8 or 9, preferably
It further has a step of forming an electrode film on the piezoelectric film.

(Appendix 11)
According to yet another aspect of the invention.
The substrate, the first electrode film formed on the substrate, and the film formed on the first electrode film and represented by the composition formula (K _1-x Na _x ) NbO ₃ (0 <x <1). A piezoelectric laminate comprising a piezoelectric film which is a single crystal epitaxial film made of an alkaliniobium oxide having a perovskite structure and a second electrode film formed on the piezoelectric film.
Provided is a piezoelectric element or piezoelectric device including at least one of a voltage detecting unit and a voltage applying unit connected between the first electrode film and the second electrode film.

(Appendix 12)
According to yet another aspect of the invention.
It is a single crystal epitaxial film composed of a substrate and an alkaliniobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x ) NbO _{3 (0 <x <1) formed on the substrate.} A piezoelectric laminate comprising a piezoelectric film and an electrode film (pattern electrode film) formed on the piezoelectric film, and a piezoelectric laminate.
A piezoelectric element or piezoelectric device including at least one of a voltage detecting unit and a voltage applying unit connected between the pattern electrodes is provided.

1 Substrate 3 Piezoelectric film 10 Piezoelectric laminate

Claims (10)

A substrate, a buffer layer formed on the substrate, a first electrode film formed on the buffer layer, and a piezoelectric film formed on the first electrode film are provided.
The buffer layer is a layer composed of zirconia stabilized with an oxide of one or more rare earth elements selected from the group consisting of scandium, itterbium, erbium, dysprosium, gadolinium, and europium. A layer made of oxide-stabilized zirconia, a layer made of cerium oxide, and a layer made of lanthanum strontium cobaltite are laminated in this order from the side of the substrate, or a layer made of cerium oxide and platinum. The layer and the layer made of lanthanum nickate are one of the layers in which the layers are laminated in this order from the side of the substrate.
The piezoelectric film is a piezoelectric laminate which is a single crystal epitaxial film made of an alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x ) NbO _{3 (0 <x <1).} A substrate, a buffer layer formed on the substrate, and a piezoelectric film formed on the buffer layer are provided.
The buffer layer has a composition formula (ZrO). ₂ ) _1-x (Y ₂ O ₃ ) _x A layer represented by the above formula in which the coefficient x in the composition formula is within the range of 0.065 ≦ x ≦ 0.155, or the composition formula (ZrO). ₂ ) _1-x (Y ₂ O ₃ ) _x A layer in which the coefficient x in the composition formula is within the range of 0.065 ≦ x ≦ 0.155, a layer made of cerium oxide, and a layer made of lanthanum strontium cobaltite are arranged in this order from the side of the substrate. It is one of the laminated layers,
The piezoelectric film has a composition formula (K). _1-x Na _x ) NbO ₃ A piezoelectric laminate which is a single crystal epitaxial film made of an alkali niobium oxide having a perovskite structure represented by (0 <x <1). A substrate, a buffer layer formed on the substrate, and a piezoelectric film formed on the buffer layer are provided.
The buffer layer is a layer composed of zirconia stabilized with an oxide of one or more rare earth elements selected from the group consisting of scandium, itterbium, erbium, dysprosium, gadolinium, and europium, or the rare earth element. One of the layers in which a layer made of zirconia stabilized with an elemental oxide, a layer made of cerium oxide, and a layer made of lanthanum strontium cobaltite are laminated in this order from the side of the substrate.
The piezoelectric film has a composition formula (K). _1-x Na _x ) NbO ₃ A piezoelectric laminate which is a single crystal epitaxial film made of an alkali niobium oxide having a perovskite structure represented by (0 <x <1). On a substrate, a buffer layer composed of zirconia stabilized with an oxide of one or more rare earth elements selected from the group consisting of scandium, itterbium, erbium, dysprosium, gadolinium, and europium, said A buffer layer in which a layer made of oxide-stabilized zirconia, a layer made of cerium oxide, and a layer made of lanthanum strontium cobaltite are laminated in this order from the side of the substrate, or a layer made of cerium oxide and platinum. A step of forming a buffer layer of any of the buffer layers in which a layer made of the material and a layer made of lanthanum nickelate are laminated in this order from the side of the substrate.
A step of forming a first electrode film on the buffer layer and
A single crystal piezoelectric film is produced by epitaxially growing an alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x ) NbO ₃ (0 <x <1) on the first electrode film. method of manufacturing a piezoelectric laminate comprising the steps of film. Composition formula (ZrO) on the substrate ₂ ) _1-x (Y ₂ O ₃ ) _x The buffer layer represented by, and the coefficient x in the composition formula is within the range of 0.065 ≦ x ≦ 0.155, or the composition formula (ZrO). ₂ ) _1-x (Y ₂ O ₃ ) _x A layer in which the coefficient x in the composition formula is within the range of 0.065 ≦ x ≦ 0.155, a layer made of cerium oxide, and a layer made of lanthanum strontium cobaltite are formed in this order from the side of the substrate. The step of forming one of the buffer layers of the laminated buffer layers and
The composition formula (K) is placed on the buffer layer. _1-x Na _x ) NbO ₃ A method for producing a piezoelectric laminate, comprising a step of forming a single crystal piezoelectric film by epitaxially growing an alkaline niobium oxide having a perovskite structure represented by (0 <x <1). On a substrate, a buffer layer composed of zirconia stabilized with an oxide of one or more rare earth elements selected from the group consisting of scandium, ytterbium, erbium, dysprosium, gadrinium, and europium, or the rare earths. A layer made of zirconia stabilized with an elemental oxide, a layer made of cerium oxide, and a layer made of lanthanstrontium cobaltite are laminated in this order from the side of the substrate to form a buffer layer of any one of the buffer layers. And the process to do
The composition formula (K) is placed on the buffer layer. _1-x Na _x ) NbO ₃ A method for producing a piezoelectric laminate, comprising a step of forming a single crystal piezoelectric film by epitaxially growing an alkaline niobium oxide having a perovskite structure represented by (0 <x <1). With the board
A buffer layer made of zirconia stabilized with an oxide of one or more rare earth elements selected from the group consisting of scandium, itterbium, erbium, dysprosium, gadolinium, and europium formed on the substrate. From the buffer layer in which a layer made of zirconia stabilized with an oxide of the rare earth element, a layer made of erbium oxide, and a layer made of lanthanum strontium cobaltite are laminated in this order from the side of the substrate, or from cerium oxide. One of the buffer layers in which a layer made of platinum, a layer made of platinum, and a layer made of lanthanum nickate are laminated in this order from the side of the substrate.
The first electrode film formed on the buffer layer and
It is a single crystal epitaxial film formed on the first electrode film and composed of an alkali niobium oxide having a perovskite structure represented _{by the composition formula (K 1-x} Na _x ) NbO _{3 (0 <x <1).} Piezoelectric membrane and
A piezoelectric laminate comprising a second electrode film formed on the piezoelectric film, and
A piezoelectric element including at least one of a voltage detection unit and a voltage application unit connected between the first electrode film and the second electrode film. With the board
Composition formula (ZrO) formed on the substrate ₂ ) _1-x (Y ₂ O ₃ ) _x The buffer layer represented by, and the coefficient x in the composition formula is within the range of 0.065 ≦ x ≦ 0.155, or the composition formula (ZrO). ₂ ) _1-x (Y ₂ O ₃ ) _x A layer in which the coefficient x in the composition formula is within the range of 0.065 ≦ x ≦ 0.155, a layer made of cerium oxide, and a layer made of lanthanum strontium cobaltite are arranged in this order from the side of the substrate. With any of the stacked buffer layers,
The first electrode film formed on the buffer layer and
A film is formed on the first electrode film, and the composition formula (K) _1-x Na _x ) NbO ₃ A piezoelectric film which is a single crystal epitaxial film made of an alkali niobium oxide having a perovskite structure represented by (0 <x <1), and a piezoelectric film.
A piezoelectric laminate comprising a second electrode film formed on the piezoelectric film, and
A piezoelectric element including at least one of a voltage detection unit and a voltage application unit connected between the first electrode film and the second electrode film. With the board
Composition formula (ZrO) formed on the substrate ₂ ) _1-x (Y ₂ O ₃ ) _x The buffer layer represented by, and the coefficient x in the composition formula is within the range of 0.065 ≦ x ≦ 0.155, or the composition formula (ZrO). ₂ ) _1-x (Y ₂ O ₃ ) _x A layer in which the coefficient x in the composition formula is within the range of 0.065 ≦ x ≦ 0.155, a layer made of cerium oxide, and a layer made of lanthanum strontium cobaltite are arranged in this order from the side of the substrate. With any of the stacked buffer layers,
A film is formed on the buffer layer, and the composition formula (K) _1-x Na _x ) NbO ₃ A piezoelectric film which is a single crystal epitaxial film made of an alkali niobium oxide having a perovskite structure represented by (0 <x <1), and a piezoelectric film.
A piezoelectric laminate comprising a pair of positive and negative input side pattern electrodes and a pair of positive and negative output side pattern electrodes formed on the piezoelectric film.
A voltage application unit connected between the input side pattern electrodes and
A piezoelectric element including a voltage detection unit connected between the output-side pattern electrodes. With the board
A buffer layer made of zirconia stabilized with an oxide of one or more rare earth elements selected from the group consisting of scandium, ytterbium, erbium, dysprosium, gadrinium, and europium formed on the substrate. Alternatively, one of a buffer layer in which a layer made of zirconia stabilized with an oxide of the rare earth element, a layer made of cerium oxide, and a layer made of lanthanstrontium cobaltite are laminated in this order from the side of the substrate.
A film is formed on the buffer layer, and the composition formula (K) _1-x Na _x ) NbO ₃ A piezoelectric film which is a single crystal epitaxial film made of an alkali niobium oxide having a perovskite structure represented by (0 <x <1), and a piezoelectric film.
A piezoelectric laminate comprising a pair of positive and negative input side pattern electrodes and a pair of positive and negative output side pattern electrodes formed on the piezoelectric film.
A voltage application unit connected between the input side pattern electrodes and
A piezoelectric element including a voltage detection unit connected between the output-side pattern electrodes.

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