Laminated substrate having piezoelectric film, method for manufacturing laminated substrate, and piezoelectric element

Abstract

The invention provides a laminated substrate having a piezoelectric film, a method for manufacturing the laminated substrate, and a piezoelectric element. [Problem] In a laminated substrate having a piezoelectric film, deterioration in orientation of the piezoelectric film is suppressed, and adhesion between the substrate and the piezoelectric film is improved. [Solution] A piezoelectric film comprising an alkali metal niobium oxide containing potassium, sodium, niobium, and oxygen, said piezoelectric film being obtained by forming a film on the substrate. When SIMS analysis is performed on a region within the entire range from the surface of the substrate on which the piezoelectric film is formed to a depth of 1 [mu] m from the surface of the substrate on which the piezoelectric film is formed to the opposite side of the surface of the substrate on which the piezoelectric film is formed, the concentration of potassium is 5E15 cm <-3 > or less, the concentration of sodium is 5E15 cm <-3 > or less, and the orientation rate of crystals constituting the piezoelectric film in the (001) plane orientation is 96% or more.

Description

Technical Field

[0001] The present application relates to a laminated substrate having a piezoelectric film, a method for manufacturing the laminated substrate, and a piezoelectric element. Background Art

[0002] Piezoelectric bodies are widely used in functional electronic components such as sensors and actuators. As materials for piezoelectric bodies, lead-based materials, particularly PZT-based ferroelectrics represented by the compositional formula Pb(Zr 1-x Ti x )O3, are widely used. Since PZT-based piezoelectric bodies contain lead, they are not preferred from the aspect of anti-pollution. Therefore, as a lead-free piezoelectric material, a piezoelectric material (KNN) containing potassium, sodium, niobium, and oxygen has been proposed, and a laminated substrate has been proposed, which has: a substrate, a lower electrode film formed on the substrate, and a piezoelectric film formed on the lower electrode film using KNN (for example, refer to Patent Documents 1 and 2).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-184513

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2008-159807 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] An object of the present application is to suppress a decrease in the orientation of a piezoelectric film and improve the adhesion between a substrate and the piezoelectric film in a laminated substrate having the piezoelectric film.

[0009] Means for Solving the Problems

[0010] According to one aspect of the present application, there is provided a laminated substrate or a piezoelectric element, which includes a substrate and a piezoelectric film formed on the substrate, and the piezoelectric film is composed of an alkali metal niobium oxide containing potassium, sodium, niobium, and oxygen.

[0011] When performing SIMS analysis on the entire region from the surface of the substrate on which the piezoelectric film is formed to a depth of 1 μm in the direction opposite to the surface of the substrate on which the piezoelectric film is formed among the substrates, the concentration of potassium is 5E15 cm -3 or less, and the concentration of sodium is 5E15 cm -3 or less.

[0012] The orientation ratio in the (001) plane direction of the crystal constituting the piezoelectric film is 96% or more.

[0013] According to other aspects of the present application, there is provided a method for manufacturing a laminated substrate, comprising:

[0014] a step of preparing a substrate; and

[0015] a step of forming a piezoelectric film on the substrate by sputtering, the piezoelectric film being composed of an alkali metal niobium oxide containing potassium, sodium, niobium, and oxygen,

[0016] In the step of forming the piezoelectric film, the film formation temperature is set to 400°C or higher and lower than 500°C, the oxygen partial pressure is set to 0.0025 Pa or higher and less than 0.01 Pa, and the atmosphere pressure is set to 0.03 Pa or higher and less than 0.1 Pa.

[0017] Effects of the Invention

[0018] According to the present application, in a laminated substrate having a piezoelectric film, it is possible to suppress a decrease in the orientation of the piezoelectric film and improve the adhesion between the substrate and the piezoelectric film. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a diagram showing an example of a cross-sectional structure of a piezoelectric laminate according to one aspect of the present application.

[0020] Figure 2 is a diagram showing an example of the structure of a simple piezoelectric element according to one aspect of the present application.

[0021] Figure 3 is a diagram showing an example of a schematic configuration of a piezoelectric element according to one aspect of the present application.

[0022] Figure 4 is a diagram showing an example of a schematic configuration of a piezoelectric device module according to one aspect of the present application.

[0023] Description of Reference Numerals

[0024] 1 Substrate

[0025] 2 Lower electrode film

[0026] 3 Piezoelectric film

[0027] 4 Upper electrode film

[0028] 6 Lower adhesion layer

[0029] 7 Upper adhesion layer

[0030] 8 Insulating film

[0031] 9a, 9b Metal wiring

[0032] 10 Laminate

[0033] 20 Piezoelectric element

[0034] 30 Piezoelectric device module Detailed implementation mode

[0035] <One mode of the present application>

[0036] Hereinafter, one mode of the present application will be described with reference to the accompanying drawings.

[0037] (1) Structure of the laminated substrate

[0038] As Figure 1 shown, the laminated substrate (laminated body) 10 having a piezoelectric film (hereinafter also referred to as the laminated body 10) according to this mode includes: a substrate 1, a lower electrode film 2 formed by film formation on the substrate 1, a piezoelectric film (piezoelectric thin film) 3 formed by film formation on the lower electrode film 2, and an upper electrode film 4 formed by film formation on the piezoelectric film 3. It should be noted that the film obtained by "film formation" in the present application is a film directly deposited on the substrate 1 and does not include a film pasted (bonded) on the substrate 1.

[0039] As the substrate 1, for example, a semiconductor substrate can be used. Specifically, as the substrate 1, a single crystal silicon (Si) substrate 1a formed with a surface oxide film (SiO2 film) 1b such as a thermal oxide film or a CVD (Chemical Vapor Deposition) oxide film, that is, a Si substrate having a surface oxide film, can be suitably used. In addition, as the substrate 1, a Si substrate 1a having an insulating film formed of an insulating material other than SiO2 instead of the surface oxide film 1b can also be used. In addition, as the substrate 1, a Si substrate 1a having a Si(100) plane or a Si(111) plane exposed on the surface, that is, a Si substrate without a surface oxide film 1b or an insulating film, can also be used. In addition, an SOI (Silicon On Insulator) substrate or a quartz glass (SiO2) substrate can also be used as the substrate 1. The thickness of the single crystal Si substrate 1a can be set to, for example, 300 μm or more and 1000 μm or less, and the thickness of the surface oxide film 1b can be set to, for example, 1 nm or more and 4000 nm or less.

[0040] The lower electrode film 2 can be formed using, for example, platinum (Pt). The lower electrode film 2 is a polycrystalline film. Hereinafter, the polycrystalline film formed by film deposition using Pt will also be referred to as a Pt film. Preferably, the (111) plane of the Pt film is parallel to the main plane of the substrate 1 (including the case where the (111) plane is inclined at an angle within ±5° with respect to the main plane of the substrate 1), that is, preferably, the Pt film is oriented in the (111) plane orientation. The Pt film being oriented in the (111) plane orientation means that in the X-ray diffraction pattern obtained by X-ray diffraction (XRD) measured on the surface of the piezoelectric film 3, no peaks other than the peaks derived from the (111) plane are observed. Thus, the main plane of the lower electrode film 2 (the plane serving as the base of the piezoelectric film 3) is preferably composed of the Pt (111) plane. The lower electrode film 2 can be formed by methods such as sputtering and evaporation. As the material of the lower electrode film 2, in addition to Pt, various metals such as gold (Au), ruthenium (Ru), or iridium (Ir), alloys having them as the main component, and metal oxides such as strontium ruthenate (SrRuO3, abbreviated as: SRO) or lanthanum nickelate (LaNiO3, abbreviated as: LNO) can be used to form it. It should be noted that when forming the lower electrode film 2 using a metal oxide, the crystal constituting the lower electrode film 2 preferably has a preferential orientation in the (001) plane orientation with respect to the surface of the substrate 1. The lower electrode film 2 can be formed as a single-layer film using the above various metals, alloys having the above various metals as the main component, or metal oxides. The lower electrode film 2 can be a laminate of a Pt film and a film having SRO as the main component provided on the Pt film, a laminate of a Pt film and a film having LNO as the main component provided on the Pt film, etc. The thickness of the lower electrode film 2 (when the lower electrode film 2 is a laminate, it is the total thickness of each layer) can be set, for example, to be 100 nm or more and 400 nm or less.

[0041] Between the substrate 1 and the lower electrode film 2, an adhesion layer 6 may be provided to improve their adhesion. The adhesion layer 6 may be, for example, a layer containing zinc (Zn) and oxygen (O) as main components (hereinafter also referred to as "ZnO layer"). The ZnO layer can be formed using, for example, zinc oxide. The composition ratio of Zn to O constituting the ZnO layer preferably satisfies the relationship of Zn:O = 1:1, but is not limited thereto and may have a slight deviation. The ZnO layer is a polycrystalline layer. The (0001) plane of the ZnO layer is preferably parallel to the main plane of the substrate 1 (including the case where the (0001) plane is inclined at an angle within ±5° with respect to the main plane of the substrate 1), that is, the ZnO layer is preferably oriented in the (0001) plane orientation. The ZnO layer being oriented in the (0001) plane orientation means that in the X-ray diffraction pattern obtained by XRD measured on the surface of the piezoelectric film 3, the intensity of the peak derived from the (0002) plane is high. Thus, the main plane of the ZnO layer (the plane that becomes the base of the lower electrode film 2) is preferably composed of the ZnO (0001) plane. The ZnO layer can be formed by methods such as sputtering method and evaporation method. The thickness of the ZnO layer can be set, for example, to be 1 nm or more and 200 nm or less, preferably 10 nm or more and 50 nm or less. As the adhesion layer 6, for example, a layer containing titanium (Ti), tantalum (Ta), titanium oxide (TiO2), nickel (Ni), ruthenium oxide (RuO2), iridium oxide (IrO2), etc. as main components can be provided. Such an adhesion layer 6 can also be formed by methods such as sputtering method and evaporation method, and the thickness of the adhesion layer 6 can be set, for example, to be 1 nm or more and 200 nm or less, preferably 10 nm or more and 50 nm or less. In this specification, the adhesion layer 6 provided between the substrate 1 and the lower electrode film 2 is sometimes also referred to as the lower adhesion layer 6.

[0042] The piezoelectric film 3 is a film formed of, for example, an alkali metal niobium oxide containing potassium (K), sodium (Na), niobium (Nb), and oxygen (O). That is, the piezoelectric film 3 is a film having an alkali metal niobium oxide containing K, Na, Nb, and O as main components. The piezoelectric film 3 can be formed using the alkali metal niobium oxide represented by the composition formula (K 1-x Na x )NbO3, that is, potassium sodium niobate (KNN). The coefficient x [=Na / (K + Na)] in the above composition formula can be set to 0 < x < 1, preferably in the range of 0.4 ≤ x ≤ 0.8. The piezoelectric film 3 becomes a polycrystalline film of KNN (hereinafter also referred to as KNN film 3). In addition, the crystal structure of KNN exhibits a perovskite structure. That is, the KNN film 3 has a perovskite structure. In addition, it is preferable that more than half of the crystals in the crystal group constituting the KNN film 3 have a columnar structure. It should be noted that in this specification, the crystal system of KNN is regarded as a tetragonal crystal system. The KNN film 3 can be formed by sputtering method. The thickness of the KNN film 3 can be set, for example, to be 0.5 μm or more and 5 μm or less, preferably 1 μm or more and 3 μm or less.

[0043] The crystals constituting the KNN film 3 are preferentially oriented in the (001) plane orientation with respect to the main surface of the substrate 1 (when the substrate 1 is, for example, a Si substrate 1a having a surface oxide film 1b or an insulating film, etc., with respect to the Si substrate 1a). That is, the main surface of the KNN film 3 (the surface that becomes the base of the upper electrode film 4) is mainly composed of the KNN (001) plane. For example, by directly forming the KNN film 3 on a Pt film (lower electrode film 2) whose main surface is mainly composed of the Pt (111) plane, a KNN film 3 whose main surface is mainly composed of the KNN (001) plane can be obtained. It should be noted that in this specification, the crystals constituting the KNN film 3 being oriented in the (001) plane orientation means that the (001) plane of the crystals constituting the KNN film 3 is parallel or substantially parallel to the main surface of the substrate 1. In addition, the crystals constituting the KNN film 3 being preferentially oriented in the (001) plane orientation means that there are many crystals whose (001) plane is parallel or substantially parallel to the main surface of the substrate 1.

[0044] In addition, the alkali metal niobium oxide constituting the KNN film 3 may further contain at least one element (dopant) selected from the group consisting of lithium (Li), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), bismuth (Bi), antimony (Sb), vanadium (V), indium (In), tantalum (Ta), molybdenum (Mo), tungsten (W), chromium (Cr), Ti, zirconium (Zr), hafnium (Hf), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), copper (Cu), zinc (Zn), silver (Ag), manganese (Mn), iron (Fe), cobalt (Co), Ni, aluminum (Al), Si, germanium (Ge), tin (Sn), and gallium (Ga). The concentration of these elements in the alkali metal niobium oxide can be set, for example, to 5 at% or less (when multiple of the above elements are contained, the total concentration is 5 at% or less).

[0045] The upper electrode film 4 has various metals such as Pt, Au, Al, Cu or their alloys as the main components. The upper electrode film 4 can be formed by methods such as sputtering, evaporation coating, plating, and metal paste method. The upper electrode film 4 does not significantly affect the crystal structure of the KNN film 3 as the lower electrode film 2 does. Therefore, the material, crystal structure, and film formation method of the upper electrode film 4 are not particularly limited. It should be noted that between the KNN film 3 and the upper electrode film 4, in order to improve their adhesion, for example, an adhesion layer 7 with RuO2, IrO2, Ti, Ta, TiO2, Ni, etc. as the main components can be provided. The thickness of the upper electrode film 4 can be set to, for example, 50 nm or more and 5000 nm or less, preferably 50 nm or more and 300 nm or less. In the case where the adhesion layer 7 is provided, the thickness of the adhesion layer 7 can be set to, for example, 1 nm or more and 200 nm or less, preferably 5 nm or more and 50 nm or less. In this specification, the adhesion layer 7 provided between the KNN film 3 and the upper electrode film 4 is sometimes referred to as the upper adhesion layer 7.

[0046] As described later, in this embodiment, during the production of the laminate 10, the KNN film 3 is formed under the conditions of low temperature, high oxygen partial pressure, and low atmosphere pressure. Thus, the laminate 10 in this embodiment has both feature 1 and feature 2 described later. In addition, the laminate 10 in this embodiment may further have feature 3 described later. Hereinafter, various features that the laminate 10 in this embodiment may have will be described.

[0047] (Feature 1)

[0048] When the KNN film 3 is formed, alkali metals (potassium atoms, sodium atoms) sometimes diffuse to the substrate 1 through the lower electrode film 2 (and the lower adhesion layer 6). If the alkali metals diffuse to the substrate 1, the adhesion between the substrate 1 and the lower electrode film 2 (the lower adhesion layer 6 when the lower adhesion layer 6 is present) sometimes decreases. As a result, when driving the piezoelectric element 20 (piezoelectric device module 30) described later obtained by processing the laminate 10, if excessive external force is repeatedly applied to the periphery (components) of the lower electrode film 2 due to repeated significant deformation of the KNN film 3, etc., the lower electrode film 2 and then the KNN film 3 sometimes peel off from the substrate 1.

[0049] Regarding this problem, in this embodiment, during the production of the laminate 10, the KNN film 3 is formed at a low temperature. Thus, the diffusion of alkali metals to the substrate 1 is successfully suppressed. Specifically, the laminate 10 in this embodiment has the following feature (feature 1): when analyzing the surface layer region of the substrate 1 by secondary ion mass spectrometry (SIMS), the potassium concentration (K concentration) is 5E15 cm -3Hereinafter, the concentration of sodium (Na concentration) is 5E15 cm -3 Hereinafter.

[0050] As a result of intensive research by the present inventors, the following new insights were first discovered: By forming the KNN film 3 at a low temperature in this way, it is possible to suppress the diffusion of alkali metals into the substrate 1, and a laminate 10 with low K concentration and Na concentration in the surface layer region of the substrate 1 can be obtained.

[0051] It should be noted that the "surface layer region of the substrate 1" in this specification refers to the entire region from the upper surface of the substrate 1 (when the substrate 1 has the surface oxide film 1b, it is from the upper surface of the surface oxide film 1b) toward the thickness direction of the substrate 1 (toward the lower surface of the substrate 1) to a depth of 1 μm. In addition, the "upper surface of the substrate 1" refers to the surface on which the lower electrode film 2 etc. is formed among the two main surfaces of the substrate 1, and the "lower surface of the substrate 1" refers to the surface on the opposite side of the upper surface of the substrate 1 among the two main surfaces of the substrate 1.

[0052] By making the K concentration and Na concentration in the surface layer region of the substrate 1 be 5E15 cm -3 Hereinafter, the adhesion between the substrate 1 and the lower electrode film 2 (or the lower adhesion layer 6) can be improved. Thereby, when driving the piezoelectric element 20 (piezoelectric device module 30) described later, even if an excessive external force is repeatedly applied to the periphery of the lower electrode film 2, it is possible to prevent the lower electrode film 2 and further the KNN film 3 from peeling off from the substrate 1. As a result, the reliability of the piezoelectric element 20 (piezoelectric device module 30) can be improved.

[0053] The lower the K concentration and Na concentration in the surface layer region of the substrate 1, the more the adhesion between the substrate 1 and the lower electrode film 2 (or the lower adhesion layer 6) can be further improved. The K concentration and Na concentration in the surface layer region of the substrate 1 are preferably 3E14 cm -3 Hereinafter, thereby, the above-mentioned adhesion can be further improved. In addition, the K concentration in the surface layer region of the substrate 1 is more preferably 1E14 cm -3 Hereinafter, thereby the above-mentioned adhesion can be further improved.

[0054] The lower limit values of the K concentration and Na concentration in the surface layer region of the substrate 1 are not particularly limited. It should be noted that the current detection limit of the K concentration based on SIMS analysis is about 1E14 cm -3 around, and the detection limit of the Na concentration is about 3E14 cm -3 around.

[0055] (Feature 2)

[0056] If a KNN film 3 is formed at a low temperature, diffusion of an alkali metal into the substrate 1 can be suppressed, but the (001) orientation ratio of the KNN film 3 sometimes decreases.

[0057] In view of this problem, in this method, during the production of the laminate 10, the KNN film 3 is formed under conditions of low temperature, high oxygen partial pressure, and low atmosphere pressure. That is, not only is the film formation condition of the KNN film 3 set to a low temperature, but also to a high oxygen partial pressure and a low atmosphere pressure. Thereby, even when film formation is performed at a low temperature, a KNN film 3 with a high (001) orientation ratio (high crystal orientation) is successfully obtained. This is a new insight first discovered as a result of in-depth research by the present inventors.

[0058] Specifically, in addition to having the feature 1, the laminate 10 further has a feature (feature 2) that the (001) orientation ratio of the KNN film 3 is, for example, 96% or more, preferably 98% or more.

[0059] It should be noted that the (001) orientation ratio of the KNN film 3 refers to the orientation ratio in the (001) plane orientation of the crystals constituting the KNN film 3. “The (001) orientation ratio of the KNN film 3 is 96% or more” means that, among the crystals constituting the KNN film 3, for example, 96% or more of the crystals are oriented in the (001) plane orientation with respect to the main surface of the substrate 1. It should be noted that the “orientation ratio” in this specification refers to a value calculated using the following formula (1) based on the peak intensity of the X-ray diffraction pattern (2θ / θ) obtained by performing XRD measurement on the KNN film 3.

[0060] Orientation ratio (%) = {(001) peak intensity / ((001) peak intensity + (110) peak intensity)} × 100…(1)

[0061] The “(001) peak intensity” in the above formula (1) refers to the intensity of the diffraction peak caused by the crystals oriented in the (001) plane orientation among the crystals constituting the KNN film 3 (that is, the crystals whose (001) plane is parallel to the main surface of the substrate 1) in the X-ray diffraction pattern obtained by performing XRD measurement on the KNN film 3, and it is the intensity of the peak that appears in the range of 2θ of 20° to 23°. When multiple peaks appear in the range of 2θ of 20° to 23°, it is the intensity of the highest peak. In addition, the “(110) peak intensity” in the above formula (1) refers to the intensity of the diffraction peak caused by the crystals oriented in the (110) plane orientation among the crystals constituting the KNN film 3 (that is, the crystals whose (110) plane is parallel to the main surface of the substrate 1) in the X-ray diffraction pattern obtained by performing XRD measurement on the KNN film 3, and it is the intensity of the peak that appears in the range of 2θ of 30° to 33°. It should be noted that when multiple peaks appear in the range of 2θ of 30° to 33°, it is the intensity of the highest peak.

[0062] It should be noted that in order to exhibit this characteristic, the KNN film 3 must have a perovskite structure. This is because when the KNN film 3 does not have a perovskite structure, in the X-ray diffraction pattern obtained by XRD measurement, no peak can be observed at least in the range of 2θ from 20° to 23°. As a result, the (001) orientation ratio cannot be calculated.

[0063] (Characteristic 3)

[0064] In this method, during the production process of the laminate 10, the KNN film 3 is formed under the conditions of low temperature, high oxygen partial pressure, and low atmosphere pressure. Thus, even when the film is formed at a low temperature, a KNN film 3 with a high (001) orientation ratio is successfully obtained. As a result, a KNN film 3 with a high piezoelectric constant can also be obtained.

[0065] Specifically, on the basis of having the above-mentioned Characteristic 1 and Characteristic 2, the laminate 10 may further have a piezoelectric constant e of the KNN film 3 31 whose absolute value is, for example, 7 C / m 2 and preferably 10 C / m or more 2 or more of the above characteristics (Characteristic 3).

[0066] (2) Configuration of the piezoelectric element and the piezoelectric device module

[0067] Figure 2 FIG. shows a schematic configuration diagram of the element (device) 20 (the element 20 having the KNN film 3, hereinafter also referred to as the piezoelectric element 20) obtained by shaping the above-mentioned laminate 10 into a specified shape by using etching or the like. It should be noted that in this specification, Figure 2 the piezoelectric element 20 shown is also referred to as the simple piezoelectric element 20a.

[0068] In addition, the piezoelectric element 20 may have a film structure, a cantilever structure, etc. As an example of such a piezoelectric element 20, Figure 3 FIG. shows a schematic configuration diagram of the film-type MEMS piezoelectric element 20b obtained by further shaping the simple piezoelectric element 20a. The piezoelectric element 20b is obtained by performing Deep-RIE or wet etching on the simple piezoelectric element 20a and removing a part of the substrate 1 from the back side of the substrate 1 (the side opposite to the side where the lower electrode film 2 etc. are formed among the two main surfaces of the substrate 1). In addition, the piezoelectric element 20b further includes an insulating film 8 and metal wirings 9a, 9b.

[0069] The metal wiring 9a is arranged in a manner that it is connected (in contact) with the lower electrode film 2 and not connected (not in contact) with the upper electrode film 4. Additionally, the metal wiring 9b is arranged in a manner that it is connected with the upper electrode film 4 and not connected with the lower electrode film 2. The metal wirings 9a and 9b can be formed using various metals such as Au, Al, Ti, Cr, etc., or alloys with these various metals as the main components. The metal wirings 9a and 9b can be single-layer films or laminated bodies with multiple layers laminated. The metal wirings 9a and 9b can be formed by methods such as sputtering, evaporation coating, plating, or the metal paste method.

[0070] The insulating film 8 is arranged to insulate the metal wiring 9b from the lower electrode film 2. The insulating film 8 is arranged, for example, to cover a part of the side surface of the KNN film 3 from the upper electrode film 4 to the substrate 1. The insulating film 8 can be formed using oxides such as silicon oxide (SiO2), aluminum oxide (Al2O3), tantalum oxide (Ta2O5), etc. The insulating film 8 can be a single-layer film or a laminated body with multiple layers laminated. The insulating film 8 can be formed by methods such as CVD or sputtering.

[0071] Figure 4 Fig. shows a schematic configuration diagram of the device module 30 having the KNN film 3 (hereinafter also referred to as the piezoelectric device module 30) according to this embodiment. The piezoelectric device module 30 at least includes Figure 3 the piezoelectric element 20b shown, and a voltage application unit 11a or a voltage detection unit 11b connected to the piezoelectric element 20b. It should be noted that the piezoelectric device module 30 can include Figure 2 the simple piezoelectric element 20a shown in place of Figure 3 the piezoelectric element 20b shown.

[0072] The voltage application unit 11a is a means for applying a voltage between the lower electrode film 2 and the upper electrode film 4 (between the electrodes), and the voltage detection unit 11b is a means for detecting the voltage generated between the lower electrode film 2 and the upper electrode film 4 (between the electrodes). As the voltage application unit 11a and the voltage detection unit 11b, various known means can be used.

[0073] 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 module 30 can function as an actuator. By applying a voltage between the lower electrode film 2 and the upper electrode film 4 using the voltage application unit 11a, the KNN film 3 can be deformed. Through this deformation action, various components connected to the piezoelectric device module 30 can be made to work. In this case, as the uses of the piezoelectric device module 30, examples include nozzles for inkjet printers, MEMS mirrors for scanners, and oscillators for ultrasonic generating devices, etc.

[0074] 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 module 30 can function as a sensor. If the KNN film 3 deforms with the change of a certain physical quantity, a voltage is generated between the lower electrode film 2 and the upper electrode film 4 due to this deformation. By detecting this voltage using the voltage detection unit 11b, the magnitude of the physical quantity applied to the KNN film 3 can be measured. In this case, examples of the uses of the piezoelectric device module 30 include an angular velocity sensor, an ultrasonic sensor, a pressure sensor, an acceleration sensor, etc.

[0075] (3) Manufacturing methods of piezoelectric laminates, piezoelectric elements, and piezoelectric device modules

[0076] The manufacturing methods of the above laminate 10, piezoelectric element 20, and piezoelectric device module 30 will be described.

[0077] (Preparation of substrate)

[0078] First, as the substrate 1, a Si substrate having a surface oxide film 1b is prepared.

[0079] (Film formation of lower adhesion layer and lower electrode film)

[0080] On the surface oxide film 1b of the substrate 1, a lower adhesion layer 6 (e.g., ZnO layer) and a lower electrode film 2 (e.g., Pt film) are sequentially formed by, for example, sputtering. It should be noted that a substrate 1 on which the lower adhesion layer 6 and the lower electrode film 2 are pre-formed on either main surface can be prepared.

[0081] Regarding the conditions for forming the ZnO layer as the lower adhesion layer 6, the following conditions can be exemplified. The film formation time of the lower adhesion layer 6 is appropriately adjusted according to the thickness of the target lower adhesion layer 6.

[0082] Target: ZnO sintered body

[0083] Temperature (substrate temperature): 200 °C or higher and 700 °C or lower, preferably 300 °C or higher and 700 °C or lower, more preferably 500 °C or higher and 700 °C or lower

[0084] Discharge power density: 2 W / cm 2 or higher and 6 W / cm 2 or lower, preferably 3 W / cm 2 or higher and 5 W / cm 2 or lower

[0085] Atmosphere: Atmosphere of a mixed gas of argon (Ar) gas and oxygen (O2) gas (hereinafter also referred to as "Ar / O2 mixed gas atmosphere")

[0086] Partial pressure ratio of Ar gas to O2 gas (Ar gas partial pressure / O2 gas partial pressure): 5 / 1 to 30 / 1, preferably 7 / 1 to 20 / 1, more preferably 10 / 1 to 15 / 1

[0087] Atmospheric pressure: 0.1 Pa or more and 0.5 Pa or less, preferably 0.2 Pa or more and 0.4 Pa or less

[0088] Thickness: 1 nm or more and 200 nm or less, preferably 10 nm or more and 50 nm or less

[0089] The expression of the numerical range such as "5 / 1 to 30 / 1" in this specification means that the lower limit value and the upper limit value are included in this range. The same applies to other numerical ranges. In addition, the "substrate temperature" in this specification refers to the surface temperature of the substrate when forming each film (each layer).

[0090] It should be noted that regarding the conditions for forming the Ti layer or the like as the lower adhesion layer 6, the following conditions can be exemplified.

[0091] Target: Ti plate, etc.

[0092] Temperature (substrate temperature): 100 °C or more and 500 °C or less, preferably 200 °C or more and 400 °C or less

[0093] Atmosphere: Ar gas atmosphere

[0094] Atmospheric pressure: 0.1 Pa or more and 0.5 Pa or less, preferably 0.2 Pa or more and 0.4 Pa or less

[0095] Other conditions can be set to the same conditions as those for setting the ZnO layer.

[0096] Regarding the conditions for forming the Pt film as the lower electrode film 2, the following conditions can be exemplified. The film formation time of the lower electrode film 2 is appropriately adjusted according to the thickness of the target lower electrode film 2.

[0097] Target: Pt plate

[0098] Temperature (substrate temperature): 200 °C or more and 600 °C or less, preferably 300 °C or more and 500 °C or less

[0099] Discharge power density: 1 W / cm 2 or more and 5 W / cm 2 or less, preferably 2 W / cm 2 or more and 4 W / cm 2 or less

[0100] Atmosphere: Ar gas atmosphere

[0101] Atmospheric pressure: 0.1 Pa or more and 0.5 Pa or less, preferably 0.2 Pa or more and 0.4 Pa or less

[0102] Thickness: 100 nm or more and 400 nm or less

[0103] (Film formation of KNN film)

[0104] After the film formation of the lower sealing layer 6 and the lower electrode film 2 is completed, then, a KNN film 3 is formed on the lower electrode film 2 by a sputtering method such as RF magnetron sputtering. The composition of the KNN film 3 can be adjusted by, for example, controlling the composition of the target used during the sputtering film formation. The target can be produced by mixing and calcining powders such as K2CO3 powder, Na2CO3 powder, and Nb2O5 powder. The composition of the target can be controlled by adjusting the mixing ratio of powders such as K2CO3 powder, Na2CO3 powder, and Nb2O5 powder. When forming a KNN film 3 containing the above elements such as Cu and Mn, it is only necessary to use a target in which Cu powder (or CuO powder), Mn powder (or MnO powder), etc. are further mixed at a specified ratio based on the above-mentioned respective powders.

[0105] In this method, the film formation conditions of the KNN film 3 are set to be low temperature, the oxygen partial pressure is increased, and further, the atmospheric pressure is decreased. Specifically, as the conditions for forming the KNN film 3, the following conditions can be exemplified. The film formation time of the KNN film 3 is appropriately adjusted according to the thickness of the target KNN film 3.

[0106] Temperature (substrate temperature): 400 °C or more and less than 500 °C, more preferably 400 °C or more and 450 °C or less

[0107] Atmosphere: Ar / O2 mixed gas atmosphere

[0108] Oxygen partial pressure in the atmosphere (O2 gas partial pressure): 0.0025 Pa or more and less than 0.01 Pa, preferably 0.003 Pa or more and less than 0.01 Pa

[0109] Atmospheric pressure (chamber pressure): 0.03 Pa or more and less than 0.1 Pa, preferably 0.03 Pa or more and 0.08 Pa or less

[0110] Discharge power density: 2.7 W / cm 2 and 4.1 W / cm 2 or less, preferably 2.8 W / cm 2 or more and 3.8 W / cm 2 or less

[0111] Film formation speed: 0.5 μm / hr or more and 4 μm / hr or less, preferably 0.5 μm / hr or more and 2 μm / hr or less

[0112] Thickness: 0.5 μm or more and 5 μm or less, preferably 1 μm or more and 3 μm or less

[0113] By forming the KNN film 3 under the above conditions, especially by setting the film formation temperature, oxygen partial pressure, and atmosphere pressure within the above specified conditions, a laminate 10 can be obtained in which the K concentration and Na concentration in the surface layer region of the substrate 1 are 5E15 cm -3 or less, and the (001) orientation ratio of the KNN film 3 is 96% or more. That is, a laminate 10 having both the above-mentioned feature 1 and feature 2 can be obtained.

[0114] Especially by setting the film formation temperature of the KNN film 3 within the above specified conditions, the diffusion of alkali metals into the substrate 1 can be suppressed. As a result, the K concentration and Na concentration in the surface layer region of the substrate 1 can be 5E15 cm -3 or less. That is, a laminate 10 having the above-mentioned feature 1 can be obtained.

[0115] When the film formation temperature of the KNN film 3 is 500 °C or higher, it is sometimes impossible to suppress the diffusion of alkali metals into the substrate 1.

[0116] By making the film formation temperature of the KNN film 3 lower than 500 °C, the diffusion of alkali metals can be suppressed, and the K concentration and Na concentration in the surface layer region of the substrate 1 can be reduced respectively. As a result, the K concentration and Na concentration in the surface layer region of the substrate 1 can be 5E15 cm -3 or less. In addition, by making the film formation temperature of the KNN film 3, for example, 450 °C or lower, the diffusion of alkali metals can be reliably suppressed, and the K concentration and Na concentration in the surface layer region of the substrate 1 can be further reduced respectively. For example, the K concentration and Na concentration in the surface layer region of the substrate 1 can be 3E14 cm -3 or less, and the K concentration in the surface layer region of the substrate 1 can be further reduced to 1E14 cm -3 or less.

[0117] When the film formation temperature of the KNN film 3 is lower than 400 °C, the effect of suppressing the diffusion of alkali metals into the substrate 1 reaches its limit, but the (001) orientation ratio of the KNN film 3 sometimes decreases. As a result, even if the oxygen partial pressure and atmosphere pressure during the film formation of the KNN film 3 are set within the specified conditions, it is sometimes impossible to make the (001) orientation ratio of the KNN film 3 96% or more.

[0118] By making the film formation temperature of the KNN film 3 400 °C or higher, the diffusion of alkali metals into the substrate 1 can be suppressed, and a KNN film 3 with a (001) orientation ratio of 96% or more can be reliably obtained. That is, a laminate 10 having both the above-mentioned feature 1 and feature 2 can be obtained.

[0119] In addition, when the oxygen partial pressure during the formation of the KNN film 3 is less than 0.0025 Pa, sometimes the (001) orientation ratio of the KNN film 3 cannot be sufficiently increased. Therefore, when the film formation temperature of the KNN film 3 is 400 °C or higher and lower than 500 °C, if the oxygen partial pressure is less than 0.0025 Pa, sometimes the (001) orientation ratio of the KNN film 3 cannot be 96% or higher. As a result, sometimes the absolute value of the piezoelectric constant e 31 is 7 C / m 2 or more.

[0120] By setting the oxygen partial pressure to 0.0025 Pa or higher, the (001) orientation ratio of the KNN film 3 can be sufficiently increased. Even when the film formation temperature of the KNN film 3 is 400 °C or higher and lower than 500 °C, the (001) orientation ratio of the KNN film 3 can be 96% or higher. That is, the laminate 10 having both the above-described feature 1 and feature 2 can be obtained. In addition, by setting the oxygen partial pressure to 0.0025 Pa or higher, even when the film formation temperature of the KNN film 3 is 400 °C or higher and lower than 500 °C, the absolute value of the piezoelectric constant e of the KNN film 3 31 is 7 C / m 2 or more. That is, the laminate 10 having all of the above-described features 1 to 3 can be obtained. By setting the oxygen partial pressure to 0.003 Pa or higher, the (001) orientation ratio of the KNN film 3 can be further increased, and the (001) orientation ratio of the KNN film 3 can be 98% or higher or the absolute value of the piezoelectric constant e of the KNN film 3 31 is 10 C / m 2 or more.

[0121] In the case where the oxygen partial pressure is 0.01 Pa or higher, the sputtering energy required for the crystallization of the KNN film 3 is taken away due to the ionization of oxygen. Therefore, when the film formation temperature is 400 °C or higher and lower than 500 °C, if the oxygen partial pressure is 0.01 Pa or higher, sometimes the (001) orientation ratio of the KNN film 3 cannot be 96% or higher. As a result, sometimes the absolute value of the piezoelectric constant e 31 is 7 C / m 2 or more.

[0122] By making the oxygen partial pressure less than 0.01 Pa, it is possible to suppress the decrease in the (001) orientation ratio of the KNN film 3. Even when the film formation temperature of the KNN film 3 is 400 °C or higher and lower than 500 °C, the (001) orientation ratio of the KNN film 3 can be 96% or higher. That is, the laminate 10 having both the above-mentioned feature 1 and feature 2 can be obtained. In addition, by making the oxygen partial pressure less than 0.01 Pa, even when the film formation temperature of the KNN film 3 is 400 °C or higher and lower than 500 °C, the piezoelectric constant e 31 has an absolute value of 7 C / m 2 or more.

[0123] In addition, when the atmospheric pressure during the film formation of the KNN film 3 is 0.1 Pa or higher, it may not be possible to sufficiently increase the (001) orientation ratio of the KNN film 3. Therefore, when the film formation temperature of the KNN film 3 is 400 °C or higher and lower than 500 °C, if the atmospheric pressure is 0.1 Pa or higher, the (001) orientation ratio of the KNN film 3 may not be 96% or higher. As a result, the piezoelectric constant e 31 may not have an absolute value of 7 C / m 2 or more.

[0124] By making the atmospheric pressure less than 0.1 Pa, it is possible to sufficiently increase the (001) orientation ratio of the KNN film 3, and the (001) orientation ratio of the KNN film 3 can be 96% or higher. That is, the laminate 10 having both the above-mentioned feature 1 and feature 2 can be obtained. In addition, by making the atmospheric pressure less than 0.1 Pa, the piezoelectric constant e of the KNN film 3 can also be 31 has an absolute value of 7 C / m 2 or more. In addition, by making the atmospheric pressure 0.08 Pa or less, it is possible to further increase the (001) orientation ratio of the KNN film 3, and the (001) orientation ratio of the KNN film 3 can be 98% or higher or the piezoelectric constant e of the KNN film 3 31 has an absolute value of 10 C / m 2 or more.

[0125] In addition, when the atmospheric pressure is less than 0.03 Pa, it may not be possible to sufficiently increase the (001) orientation ratio of the KNN film 3. Therefore, when the film formation temperature of the KNN film 3 is 400 °C or higher and lower than 500 °C, if the atmospheric pressure is less than 0.03 Pa, the (001) orientation ratio of the KNN film 3 may not be 96% or higher. As a result, the piezoelectric constant e 31 may not have an absolute value of 7 C / m 2 or more.

[0126] By setting the atmosphere pressure to 0.03 Pa or more, the (001) orientation ratio of the KNN film 3 can be sufficiently increased. Even when the film formation temperature of the KNN film 3 is 400 °C or more and less than 500 °C, the (001) orientation ratio of the KNN film 3 can be 96% or more. That is, the laminate 10 having both the above-mentioned feature 1 and feature 2 can be obtained. In addition, by setting the atmosphere pressure to 0.03 Pa or more, the piezoelectric constant e of the KNN film 3 can also be 31 with an absolute value of 7 C / m 2 or more.

[0127] By forming the KNN film 3 by setting all of the film formation temperature, oxygen partial pressure, and atmosphere pressure within the above-mentioned specified conditions in this way, the laminate 10 having both the above-mentioned feature 1 and feature 2 can be obtained for the first time, and further, the laminate 10 having all of the above-mentioned feature 1, feature 2, and feature 3 can be obtained. If at least any one of the conditions of the film formation temperature, oxygen partial pressure, and atmosphere pressure is outside the above-mentioned conditions, the laminate having both the above-mentioned feature 1 and feature 2 may not be obtained.

[0128] (Formation of the upper adhesion layer and the upper electrode film)

[0129] After the film formation of the KNN film 3 is completed, the upper adhesion layer 7 (for example, RuO2 layer) and the upper electrode film 4 (for example, Pt film) are sequentially formed on the KNN film 3 by, for example, sputtering.

[0130] Regarding the conditions for forming the RuO2 layer or the like as the upper adhesion layer 7, the following conditions can be exemplified. The film formation time of the upper adhesion layer 7 is appropriately adjusted according to the thickness of the target upper adhesion layer 7.

[0131] Target: Ru plate or the like

[0132] Temperature (substrate temperature): room temperature (25 °C) or more and less than 500 °C, preferably room temperature (25 °C) or more and 450 °C or less

[0133] Discharge power density: 0.3 W / cm 2 or more and 2 W / cm 2 or less, preferably 0.5 W / cm 2 or more and 1 W / cm 2 or less

[0134] Atmosphere: Ar / O2 mixed gas atmosphere

[0135] Partial pressure ratio of Ar gas to O2 gas (Ar gas partial pressure / O2 gas partial pressure): 3 / 5 to 1 / 1, preferably 3 / 4 to 1 / 1

[0136] Atmospheric pressure: 0.1 Pa or more and 1.0 Pa or less, preferably 0.2 Pa or more and 0.7 Pa or less

[0137] Thickness: 1 nm or more and 200 nm or less, preferably 5 nm or more and 50 nm or less

[0138] Regarding the conditions for forming the Pt film or the like as the upper electrode film 4 during film formation, the following conditions can be exemplified. The film formation time of the upper electrode film 4 is appropriately adjusted according to the thickness of the target upper electrode film 4.

[0139] Target: Pt plate or the like

[0140] Temperature (substrate temperature): room temperature (25 °C) or more and less than 500 °C, preferably room temperature (25 °C) or more and 450 °C or less

[0141] Discharge power density: 1 W / cm 2 or more and 5 W / cm 2 or less, preferably 2 W / cm 2 or more and 4 W / cm 2 or less

[0142] Atmosphere: Ar gas atmosphere

[0143] Atmospheric pressure: 0.1 Pa or more and 0.5 Pa or less, preferably 0.2 Pa or more and 0.4 Pa or less

[0144] Thickness: 50 nm or more and 5000 nm or less, preferably 50 nm or more and 300 nm or less

[0145] By forming the upper adhesion layer 7 and the upper electrode film 4 using the above conditions, especially by forming the upper adhesion layer 7 and the upper electrode film 4 with the film formation temperature within the above-specified range, it is possible to more reliably suppress the diffusion of alkali metals into the substrate 1. As a result, it is possible to more reliably obtain a laminate 10 in which the K concentration and the Na concentration in the surface layer region of the substrate 1 are each 5E15 cm -3 or less.

[0146] As described above, by sequentially forming the lower adhesion layer 6, the lower electrode film 2, the KNN film 3, the upper adhesion layer 7, and the upper electrode film 4, it is possible to obtain Figure 1 the laminate 10 as shown.

[0147] (Fabrication of piezoelectric element)

[0148] After fabricating Figure 1 the laminate 10 as shown, the laminate 10 is processed to fabricate a simple piezoelectric element 20a.

[0149] Specifically, first, the upper electrode film 4 (including the upper adhesion layer 7) and the KNN film 3 are separately patterned by dry etching using, for example, Ar gas or reactive gas. In the patterning process, the upper electrode film 4 (including the upper adhesion layer 7) and the KNN film 3 are each formed into a specified shape, and a part of the lower electrode film 2 is exposed. Additionally, in the patterning process, a photoresist can be used as an etching mask.

[0150] After manufacturing Figure 2 a simple piezoelectric element 20a as shown, the lower electrode film 2 and the lower adhesion layer 6 are separately patterned by dry etching using, for example, Ar gas or reactive gas, and the lower electrode film 2 and the lower adhesion layer 6 are each formed into a specified shape. In this patterning process, a photoresist can be used as an etching mask.

[0151] After the patterning of the lower electrode film 2 and the lower adhesion layer 6 is completed, an insulating film 8 and metal wirings 9a, 9b are provided. Specifically, first, a layer formed of an insulating material (i.e., the insulating film 8) is provided from the upper electrode film 4 to the substrate 1 by methods such as CVD method, sputtering method, etc. so as to cover the side surface of the KNN film 3. Then, the insulating film 8 is patterned by dry etching or wet etching using a reactive gas such as Ar gas or CF4 gas, and the insulating film 8 is formed into a specified shape.

[0152] After the insulating film 8 is provided, a layer formed of a metal-containing material (metal wiring layer) is provided by methods such as sputtering method, evaporation method, plating method, metal paste method, etc. And, the metal wiring layer is patterned by dry etching or wet etching using Ar gas or reactive gas to form metal wirings 9a, 9b. The metal wiring 9a is formed (patterned) so as to be connected to the lower electrode film 2 and not connected to the upper electrode film 4, and the metal wiring 9b is formed so as to be connected to the upper electrode film 4 and not connected to the lower electrode film 2.

[0153] It should be noted that the etching conditions in the patterning process for forming the insulating film 8 and the metal wirings 9a, 9b and the etching conditions of the substrate 1 when the piezoelectric laminate 10 is processed into the piezoelectric element 20 can be set to general etching conditions used in the semiconductor device manufacturing process as long as they do not deteriorate the insulation of the KNN film 3.

[0154] Additionally, a part of the substrate 1 is removed from the back side of the substrate 1 by Deep-RIE or wet etching. Thereby, Figure 3 a piezoelectric element 20b as shown can be obtained.

[0155] (Fabrication of Piezoelectric Device Module)

[0156] By connecting the voltage application unit 11a or the voltage detection unit 11b to the obtained piezoelectric element 20 (20b), a device module 30 having the KNN film 3 (hereinafter also referred to as a piezoelectric device module 30) can be obtained.

[0157] (4) Effects

[0158] According to this embodiment, one or more of the following effects can be obtained.

[0159] (a) In this embodiment, during the production of the laminate 10, the KNN film 3 is formed under the conditions that the film formation temperature is 400 °C or higher and lower than 500 °C, the oxygen partial pressure is 0.0025 Pa or higher and less than 0.01 Pa, and the atmosphere pressure is 0.03 Pa or higher and less than 0.1 Pa.

[0160] By setting the film formation temperature to 400 °C or higher and lower than 500 °C to form the KNN film 3, diffusion of alkali metals into the substrate 1 can be suppressed. As a result, the obtained laminate 10 can have the characteristics that "the K concentration and the Na concentration in the surface layer region of the substrate 1 are each 5E15 cm -3 or less" (Characteristic 1).

[0161] In addition, by setting the oxygen partial pressure and the atmosphere pressure within the above-specified conditions to form the KNN film 3, the KNN film 3 can be formed at a low temperature (400 °C or higher and lower than 500 °C) and a KNN film 3 with a high (001) orientation ratio can be obtained. As a result, the obtained laminate 10 can further have the characteristic that "the (001) orientation ratio of the KNN film 3 is 96% or higher" (Characteristic 2).

[0162] By forming the KNN film 3 by setting all of the film formation temperature, the oxygen partial pressure, and the atmosphere pressure within the above-specified conditions in this way, the obtained laminate 10 can have both of the above Characteristic 1 and Characteristic 2.

[0163] By making the laminate 10 have the above Characteristic 1, the adhesion between the substrate 1 and the lower electrode film 2 (lower adhesion layer 6) can be improved. As a result, when the piezoelectric element 20 (piezoelectric device module 30) is driven, even if an excessive external force is repeatedly applied to the periphery (components) of the lower electrode film 2 due to repeated significant deformation of the KNN film 3 or the like, peeling of the lower electrode film 2 and thus the KNN film 3 from the substrate 1 can be avoided. As a result, the reliability of the piezoelectric element 20 and thus the piezoelectric device module 30 can be improved.

[0164] In addition, by making the laminate 10 have both Characteristic 1 and Characteristic 2, a laminate 10 (piezoelectric element 20, piezoelectric device module 30) with high reliability and excellent piezoelectric characteristics can be obtained.

[0165] (b) By setting all of the film formation temperature, oxygen partial pressure, and atmosphere pressure within the ranges of the above-described specified conditions, the KNN film 3 is formed, so that the KNN film 3 can be formed at a low temperature and a KNN film 3 having a high piezoelectric constant can be obtained. As a result, in addition to having the above-described features 1 and 2, the laminate 10 may further have a feature (feature 3) that "the absolute value of the piezoelectric constant e 31 of the KNN film 3 is, for example, 7 C / m 2 or more". Thus, the KNN film 3 and further the laminate 10 can reliably have excellent piezoelectric characteristics.

[0166] It should be noted that a method of manufacturing a piezoelectric laminate by using adhesion (bonding) has also been proposed. That is, a method of manufacturing a piezoelectric laminate by sequentially forming a first electrode film, a KNN film, and a second electrode film on a first substrate, pasting a second substrate on the upper surface of the second electrode film, and then removing the first substrate has also been proposed. It can be considered that in a piezoelectric laminate manufactured by using the adhesion method, alkali metals do not diffuse into the second substrate. It should be noted that in a piezoelectric laminate manufactured by using this method, the second electrode film functions as a lower electrode film, and the first electrode film functions as an upper electrode film. However, a piezoelectric laminate manufactured by using this method of adhesion has a problem that the adhesion between the substrate (second substrate) and the lower electrode film (second electrode film) is very low. In addition, in the method using adhesion, the number of manufacturing steps of the piezoelectric laminate increases. Therefore, there are also concerns such as complication of the manufacturing process, reduction in productivity, and increase in cost. In contrast, in the present embodiment, the laminate 10 is manufactured without using the adhesion method. Furthermore, during the manufacturing process, diffusion of alkali metals into the substrate 1 is suppressed. As a result, the adhesion between the substrate 1 and the lower electrode film 2 (lower adhesion layer 6) is successfully improved. In addition, since the laminate 10 is manufactured without using the adhesion method, the laminate 10 (and further the piezoelectric element 20 and the piezoelectric device module 30) according to the present embodiment does not have traces originating from adhesion. That is, in the laminate 10 (and further the piezoelectric element 20 and the piezoelectric device module 30) according to the present embodiment, there are no traces originating from adhesion at the interface between the substrate 1 and the KNN film 3, at the interface between the substrate 1 and the lower electrode film 2 (lower adhesion layer 6 when there is a lower adhesion layer 6), or at the interface between the lower electrode film 2 and the KNN film 3. It should be noted that as the "traces originating from adhesion" mentioned here, the presence (distribution) of inclusions (e.g., adhesives) used for adhesion and the presence (distribution) of impurities not originating from the film formation process (e.g., impurities originating from adhesives) can be exemplified.

[0167] (5) Modification

[0168] This method can be modified as in the following modification examples. It should be noted that in the description of the following modification examples, the same reference numerals are given to the same components as in the above method, and their descriptions are omitted. In addition, the above method and the following modification examples can be combined arbitrarily.

[0169] (Modification Example 1)

[0170] As the substrate 1, for example, a semiconductor substrate that requires a reduced thermal history can also be used. Specifically, as the substrate 1, a semiconductor substrate (e.g., a Si substrate) having semiconductor elements formed on either main surface can also be used.

[0171] The semiconductor elements can, for example, have a CMOS (Complementary Metal Oxide Semiconductor) structure including a p-type MOSFET and an n-type MOSFET, which function complementarily. In addition, the substrate 1 can further have a protective film such as an oxide film or a nitride film for protecting the semiconductor elements, and it can be considered that the protective film is included in the semiconductor elements. It should be noted that various known methods can be used to form the semiconductor elements. In addition, methods such as a method of causing thermal diffusion of a dopant and a method of activating ions by ion implantation and annealing can be used to form the n-type region and the p-type region of the semiconductor elements.

[0172] In addition, when the substrate 1 has a surface oxide film 1b or an insulating film, in this modification example, the surface oxide film 1b or the insulating film is formed in a portion of the upper surface of the substrate 1 (the surface of the substrate 1 on which the semiconductor elements are formed) other than the formation site of the semiconductor elements.

[0173] In addition, in this modification example, the lower electrode film 2 is formed at a position on the upper surface of the substrate 1 different from the formation site of the semiconductor elements (when the substrate 1 has a surface oxide film 1b or an insulating film, etc., it is formed on the surface oxide film 1b or the insulating film). Therefore, the piezoelectric element 20 can be formed at a position on the upper surface of the substrate 1 different from the formation position of the semiconductor elements. In addition, the piezoelectric element 20 can also be formed on the semiconductor elements (on the protective film). In these cases, the surface layer region of the substrate 1 is a region within the entire range from the interface between the piezoelectric element 20 and the substrate 1 or the interface between the piezoelectric element 20 and the semiconductor elements (protective film) to a depth of 1 μm toward the back surface of the substrate 1.

[0174] In this modification example, during the fabrication of the laminate 10, the KNN film 3 is formed by setting all of the film formation temperature, oxygen partial pressure, and atmosphere pressure within the above-specified conditions. As a result, it is possible to suppress the diffusion of alkali metals into the substrate 1 and to increase the (001) orientation ratio of the KNN film. Consequently, the same effects as those of the above-described method can be obtained. That is, a laminate 10 having at least both Feature 1 and Feature 2 can be obtained.

[0175] It should be noted that the CMOS structure formed using the above method is not heat-resistant. For example, when the n-type region and the p-type region are heated, the dopant sometimes migrates, resulting in a change in the doping concentration. In this modification example, since the KNN film 3 is formed at a low temperature of 400°C or higher and lower than 500°C, it is possible to reduce the thermal history for the semiconductor element and to form a semiconductor element and a piezoelectric element on the same substrate 1. In addition, by reducing the thermal history for the semiconductor element, it is possible to suppress the shortening of the life and the deterioration of the performance of the semiconductor element.

[0176] In addition, in this modification example, it is preferable to set the film formation temperatures of the lower electrode film 2 and the lower adhesion layer 6 to be lower than 500°C, respectively. Specifically, the film formation temperature of the lower electrode film 2 is, for example, set to 200°C or higher and lower than 500°C, preferably 300°C or higher and 450°C or lower. When the ZnO layer is formed as the lower adhesion layer 6, the film formation temperature is, for example, set to 200°C or higher and lower than 500°C, preferably 300°C or higher and 450°C or lower, more preferably 400°C or higher and 450°C or lower. When the Ti layer or the like is formed as the lower adhesion layer 6, the film formation temperature is preferably set to 100°C or higher and lower than 500°C, preferably 200°C or higher and 400°C or lower. Thereby, it is possible to reliably reduce the thermal history for the semiconductor element and to reliably suppress the shortening of the life and the deterioration of the performance of the semiconductor element.

[0177] (Modification Example 2)

[0178] In the above Modification Example 1, an example in which the semiconductor element has a CMOS structure has been described. However, as long as the semiconductor element is an element having a heat-sensitive element structure, it is not limited to CMOS. Elements formed by using thermal diffusion or ion implantation of dopants in the formation of the n-type region or the p-type region are not heat-resistant. Therefore, when these methods are used to form a semiconductor element, that is, when the semiconductor element has either a region where a p-type or n-type dopant is thermally diffused or a region where the aforementioned dopant is ion-implanted, this method can also be suitably applied, and the same effects as those of the above-described method and modification example can be obtained.

[0179] (Modification Example 3)

[0180] As described above, since the KNN film 3 is formed at a low temperature of 400 °C or higher and lower than 500 °C, as the substrate 1, other substrates that require a reduced thermal history can also be used.

[0181] For example, as the substrate 1, a substrate formed with a CMUT (Capacitive Micro-machined Ultrasound Transducer) structure can also be used.

[0182] In addition, for example, as the substrate 1, either a heat-intolerant resin substrate or a glass substrate can be used.

[0183] As the resin substrate, for example, a substrate formed of polyimide, polytetrafluoroethylene (PTFE), polyethylene naphthalate, polypropylene, polystyrene, polycarbonate, polysulfone, polyarylate, polyamide, polyethylene terephthalate (PET), or an acrylic resin can be used. In addition, as the resin substrate, for example, a glass epoxy substrate, a paper phenol substrate, a paper epoxy substrate, a glass composite substrate, or a fluororesin substrate can also be used. In addition, as the resin substrate, a composite resin substrate containing, for example, silica particles, metal nanoparticles, inorganic oxide nanoparticles, inorganic nitride nanoparticles, or metal-based / inorganic-based nanofibers or microfibers in the above resin substrate can also be used. The thickness of the resin substrate can be set, for example, to 10 μm or more and 1000 μm or less.

[0184] Even when the above substrate is used as the substrate 1, in the process of manufacturing the laminate 10, by forming the KNN film 3 with the film formation temperature, oxygen partial pressure, and atmosphere pressure all within the above-specified conditions, it is possible to both suppress the diffusion of alkali metals into the substrate 1 and form a KNN film 3 with a high (001) orientation rate on the substrate 1 that requires a reduced thermal history and the heat-intolerant substrate 1. As a result, in this modified example, a laminate 10 having at least both Feature 1 and Feature 2 can also be obtained.

[0185] In addition, when using a substrate formed with a CMUT structure, a heat-sensitive resin substrate, or a glass substrate as the substrate 1, it is preferable to set the film formation temperatures of the lower electrode film 2 and the lower adhesion layer 6 to be lower than 500 °C, respectively. Specifically, the film formation temperature of the lower electrode film 2 is set, for example, to be 200 °C or higher and lower than 500 °C, preferably 300 °C or higher and 450 °C or lower. When forming a ZnO layer as the lower adhesion layer 6, the film formation temperature is set, for example, to be 200 °C or higher and lower than 500 °C, preferably 300 °C or higher and 450 °C or lower, more preferably 400 °C or higher and 450 °C or lower. When forming a Ti layer or the like as the lower adhesion layer 6, the film formation temperature is set, for example, to be 100 °C or higher and lower than 500 °C, preferably 200 °C or higher and 400 °C or lower. Thereby, the thermal history with respect to the substrate 1 can be reliably reduced.

[0186] In addition, as the substrate 1, a metal substrate can also be used. As the metal substrate, for example, a substrate containing platinum (Pt), gold (Au), iron (Fe), titanium (Ti), copper (Cu), molybdenum (Mo), nickel (Ni), aluminum (Al), tungsten (W), palladium (Pd) as the main component can be used. In addition, as the metal substrate, for example, a substrate formed of stainless steel (SUS), permalloy, or inconel can also be used. The thickness of the metal substrate can be set, for example, to be 10 μm or more and 1000 μm or less. In this case, during the production process of the laminate 10, by forming the KNN film 3 by setting all of the film formation temperature, oxygen partial pressure, and atmosphere pressure within the range of the above-specified conditions, a laminate 10 having at least both of the feature 1 and the feature 2 can also be obtained.

[0187] (Modification Example 4)

[0188] In the above-described manner and modification examples, an example in which the lower adhesion layer 6 and the lower electrode film 2 are provided has been described, but it is not limited thereto. The lower adhesion layer 6 and the lower electrode film 2 may not be provided. That is, the KNN film 3 can be directly formed on the substrate 1.

[0189] In this modification example, during the production process of the laminate 10, by forming the KNN film 3 by setting all of the film formation temperature, oxygen partial pressure, and atmosphere pressure within the range of the above-specified conditions, diffusion of alkali metals into the substrate 1 can be suppressed and the (001) orientation ratio of the KNN film can be increased. As a result, in this manner, the same effects as those of the above-described manner and modification examples can also be obtained. That is, a laminate 10 having at least both of the feature 1 and the feature 2 can be obtained.

[0190] In addition, in this modified example, since the KNN film 3 is formed at a low temperature of 400 °C or higher and lower than 500 °C, as the substrate 1, any of the substrates described in the above modified examples 1 to 3 can be used.

[0191] <Other methods>

[0192] As described above, the methods and modified examples of the present application have been specifically described. However, the present application is not limited to the above methods and modified examples, and various changes can be made without exceeding the gist thereof.

[0193] In addition, in the above method, the case where the lower adhesion layer 6 is provided between the substrate 1 and the lower electrode film 2 and the upper adhesion layer 7 is provided between the KNN film 3 and the upper electrode film 4 has been described, but it is not limited thereto. As long as the necessary adhesion can be ensured, the lower adhesion layer 6 and the upper adhesion layer 7 may not be provided.

[0194] Examples

[0195] Hereinafter, the experimental results for verifying the effects of the above method will be described.

[0196] (Sample 1)

[0197] As the substrate, a Si substrate with a (100) plane orientation on the surface, a thickness of 610 μm, a diameter of 6 inches, and a thermally oxidized film (SiO2 film) with a thickness of 500 nm formed on the surface was prepared. Then, a piezoelectric laminate (Sample 1) was fabricated by successively forming a ZnO layer (thickness: 25 nm) as the lower adhesion layer, a Pt film (thickness: 200 - 300 nm) as the lower electrode film, and a KNN film (thickness: 2 μm) as the piezoelectric film on this substrate (on the thermally oxidized film). In Sample 1, the lower adhesion layer, the lower electrode film, and the KNN film were all formed by RF magnetron sputtering.

[0198] The film formation conditions of the ZnO layer as the lower adhesion layer are as follows.

[0199] Target: ZnO sintered body

[0200] Substrate temperature: 500 °C

[0201] Discharge power density: 4 W / cm 2

[0202] Atmosphere: Ar / O2 mixed gas atmosphere

[0203] Atmosphere pressure (chamber pressure): 0.3 Pa

[0204] Ar gas partial pressure / O2 gas partial pressure: 10 / 1

[0205] Film formation time: 3 minutes (thickness 25 nm)

[0206] The film-forming conditions of the Pt film as the lower electrode film are as follows.

[0207] Target: Pt plate

[0208] Substrate temperature: 500 °C

[0209] Discharge power density: 2 W / cm 2

[0210] Atmosphere: Ar gas atmosphere

[0211] Atmospheric pressure (chamber pressure): 0.3 Pa

[0212] Film-forming time: 20 minutes (thickness 200 nm)

[0213] The conditions for forming the KNN film are as follows.

[0214] Target: KNN sintered body

[0215] Discharge power density: 3 W / cm 2

[0216] Atmosphere: Ar / O2 mixed gas atmosphere

[0217] Film-forming temperature: 490 °C

[0218] Oxygen partial pressure: 0.003 Pa

[0219] Atmospheric pressure (chamber pressure): 0.05 Pa

[0220] Film-forming time: 120 minutes (thickness 2000 nm (2 μm))

[0221] (Samples 2 - 13)

[0222] In Samples 2 - 13, the temperature, oxygen partial pressure, and atmospheric pressure during the formation of the KNN film are as recorded in Table 1. The other conditions are used for film formation under the same conditions as in Sample 1.

[0223] [Table 1]

[0224]

[0225] [Evaluation]

[0226] For Samples 1 - 13, the K concentration and Na concentration in the surface layer region of the substrate, the (001) orientation ratio of the KNN film, the piezoelectric constant e 31 and the adhesion between the substrate and the lower adhesion layer (lower electrode film) are evaluated.

[0227] (Measurement of K concentration and Na concentration)

[0228] The measurement of the K concentration and the Na concentration in the surface layer region of the substrate is carried out by SIMS analysis. It should be noted that, in order to improve the analysis accuracy, the SIMS analysis is carried out using various samples in a state where the KNN film is removed by etching. The measurement results of the K concentration and the Na concentration in the surface layer region of the substrate are shown in Table 2 below. It should be noted that in Table 2, the 1E14 cm of the K concentration -3 The following means that: the K concentration in the surface layer region of the substrate is below the detection limit which is the lower limit value based on the SIMS analysis, and the 3E14 cm of the Na concentration -3 The following means that: the Na concentration in the surface layer region of the substrate is below the detection limit which is the lower limit value based on the SIMS analysis.

[0229] (Evaluation of the (001) orientation ratio of the KNN film)

[0230] The (001) orientation ratio of the KNN film is calculated and evaluated by using the peak intensity of the X-ray diffraction pattern (2θ / θ) obtained by performing XRD measurement on the KNN film and using the above formula (1). The calculation results of the (001) orientation ratio are shown in Table 2 below. It should be noted that the "orientation ratio" in Table 2 refers to the (001) orientation ratio of the KNN film.

[0231] (Evaluation of the piezoelectric constant)

[0232] The piezoelectric constant e of the KNN film 31 is measured (evaluated) as follows. First, rectangular test pieces with a width of 2.5 mm × a length of 20 mm are made from each sample. One end in the length direction of each of the made test pieces is fixed as the fixed end, and the other end is used as the free end to make a simple piezoelectric element having a cantilever (cantilever beam) structure, and a voltage application means is connected to this piezoelectric element. And while applying a voltage to the KNN film of each test piece (piezoelectric element), the displacement amount of the free end of the test piece is measured by laser. Using the measured displacement amount, the piezoelectric constant e is calculated by using the following (mathematical formula 2) 31 . In the following (mathematical formula 2), s 11,s is the Young's modulus of the substrate (Si substrate) of each sample, h s is the thickness of the substrate of each sample, L is the beam length (14.5 mm), δ is the output displacement based on the measured displacement amount, and V is the voltage applied to the piezoelectric film. It should be noted that the frequency of the alternating electric field (alternating voltage) when measuring the piezoelectric constant e 31 is 350 Hz, and the maximum value of the voltage applied to the KNN film is 20 V. The unit of the piezoelectric constant e 31 is C / m 2 . The piezoelectric constant e 31The measurement results are shown in Table 2 below.

[0233] (Mathematical formula 2)

[0234]

[0235] (Evaluation of adhesion)

[0236] The adhesion between the substrate and the lower adhesion layer (lower electrode film) is evaluated by the following AC voltage application test. First, two rectangular test pieces with a width of 2.5 mm and a length of 20 mm are made from each sample. One end in the length direction of each of the fabricated test pieces is fixed as the fixed end, and the other end is used as the free end to make a simple piezoelectric element having a cantilever (cantilever beam) structure, and a voltage application means is connected to the piezoelectric element. And, for the KNN film of the test piece (piezoelectric element), an AC voltage is continuously applied to one of the two pieces for 100 hours, and an AC voltage is continuously applied to the other piece for 200 hours. It should be noted that the frequency of the AC voltage is 350 Hz, and the maximum value of the voltage applied to the KNN film is 30 V. After applying the voltage, a scanning electron microscope is used to confirm whether there is peeling of the lower adhesion layer (lower electrode film). The evaluation results are shown in Table 2 below. It should be noted that in Table 2, "○" means that no peeling of the lower electrode film (no peeling) was confirmed in the piezoelectric element to which the AC voltage was applied for 200 hours, "△" means that no peeling of the lower electrode film was confirmed in the piezoelectric element to which the AC voltage was applied for 100 hours, but peeling of the lower electrode film was confirmed in the piezoelectric element to which the AC voltage was applied for 200 hours, and "×" means that peeling of the lower electrode film was confirmed in the piezoelectric element to which the AC voltage was applied for 100 hours.

[0237] [Table 2]

[0238]

[0239] It can be confirmed from Table 2 that in Samples 1, 2, 3, 6, 8, 10, and 12 with a KNN film formed under the conditions that the film formation temperature is 400 °C or higher and lower than 500 °C, the oxygen partial pressure is 0.0025 Pa or higher and less than 0.01 Pa, and the atmosphere pressure is 0.03 Pa or higher and less than 0.1 Pa, the K concentration and Na concentration in the surface layer region of the substrate are 5E15 cm -3 as follows, and the (001) orientation ratio of the KNN film is 96% or higher. It can be seen from this that in Samples 1, 2, 3, 6, 8, 10, and 12, the diffusion of alkali metals into the substrate is suppressed. In addition, even when the KNN film is formed at a low temperature, the (001) orientation ratio of the KNN film can be sufficiently increased. Furthermore, it can also be confirmed that in Samples 1, 2, 3, 6, 8, 10, and 12, the piezoelectric constant e 31 is 7 C / m 2As described above, it can be confirmed that by forming a film of a KNN film sample under the conditions where the film formation temperature, oxygen partial pressure, and atmosphere pressure are all within the above-specified ranges, a laminate having both of the above characteristics 1 and 2 can be obtained, and further, a laminate having all of the above characteristics 1 to 3 can be obtained.

[0240] In addition, it can be confirmed that among the samples (laminates) having both of the above characteristics 1 and 2, in samples 2, 3, 6, 8, 10, and 12 where the film formation temperature is 400 °C or higher and 450 °C or lower, the K concentration and Na concentration in the surface layer region of the substrate are 3E14 cm -3 or less, and further, the K concentration in the surface layer region of the substrate is 1E14 cm -3 or less. That is, it can be known that when forming a KNN film under the conditions of 400 °C or higher and 450 °C or lower, the (001) orientation ratio of the KNN film can be prevented from decreasing, and the diffusion of alkali metals into the substrate can be more reliably suppressed, and the values can be reduced to below the detection limit of the lower limit values of the K concentration and Na concentration based on SIMS analysis. In addition, even when an AC voltage with a frequency of 350 Hz and a maximum voltage value of 30 V is applied to these samples for 200 hours, peeling of the lower electrode film is not confirmed. That is, it can be known that samples 2, 3, 6, 8, 10, and 12 have higher adhesion than sample 1.

[0241] In addition, it can be confirmed from Table 2 that in sample 4, the K concentration and Na concentration in the surface layer region of the substrate exceed 5E15 cm -3 respectively. From this, it can be known that when the film formation temperature of the KNN film is 500 °C (500 °C or higher), even if the oxygen partial pressure and atmosphere pressure during film formation of the KNN film are within the specified ranges, the diffusion of alkali metals into the substrate cannot be suppressed. That is, a laminate having both of the above characteristics 1 and 2 cannot be obtained.

[0242] In addition, it can be confirmed from Table 2 that in sample 5, the (001) orientation ratio of the KNN film is less than 96%. From this, it can be known that when the film formation temperature of the KNN film is 390 °C (lower than 400 °C), even if the oxygen partial pressure and atmosphere pressure during film formation of the KNN film are within the specified ranges, the (001) orientation ratio of the KNN film cannot be sufficiently increased. That is, a laminate having both of the above characteristics 1 and 2 cannot be obtained.

[0243] In addition, it can be confirmed from Table 2 that in samples 7 and 9, the (001) orientation ratio of the KNN film is less than 96%, and the piezoelectric constant e 31 is less than 7.0 C / m 2Therefore, it can be known that when the oxygen partial pressure during the formation of the KNN film is 0.01 Pa (0.01 Pa or higher), or when the oxygen partial pressure during the formation of the KNN film is 0.002 Pa (less than 0.0025 Pa), the (001) orientation ratio of the KNN film cannot be sufficiently increased. Thus, it can be known that if the film formation temperature of the KNN film is lower than 500 °C, the (001) orientation ratio of the KNN film is less than 96%. That is, it can be known that a laminate having both the above-mentioned Feature 1 and Feature 2 cannot be obtained. It can also be known that the (001) orientation ratio of the KNN film is less than 96%, and as a result, the piezoelectric constant e 31 is sometimes less than 7.0 C / m 2 .

[0244] In addition, it can be confirmed from Table 2 that in Samples 11 and 13, the (001) orientation ratio of the KNN film is less than 96%, and the piezoelectric constant e 31 is less than 7.0 C / m 2 . Therefore, it can be known that when the atmospheric pressure during the formation of the KNN film is 0.1 Pa (0.1 Pa or higher), or when the atmospheric pressure during the formation of the KNN film is 0.025 Pa (less than 0.03 Pa), the (001) orientation ratio of the KNN film cannot be sufficiently increased. Thus, it can be known that if the film formation temperature of the KNN film is lower than 500 °C, the (001) orientation ratio of the KNN film is less than 96%. That is, it can be known that a laminate having both the above-mentioned Feature 1 and Feature 2 cannot be obtained. It can also be known that the (001) orientation ratio of the KNN film is less than 96%, and as a result, the piezoelectric constant e 31 is sometimes less than 7.0 C / m 2 .

[0245] <Preferred Embodiment of the Present Application>

[0246] Hereinafter, the preferred embodiment of the present application is noted.

[0247] (Note 1)

[0248] According to one embodiment of the present application, there is provided a laminated substrate including a substrate and a piezoelectric film formed on the substrate, the piezoelectric film being composed of an alkali metal niobium oxide containing potassium, sodium, niobium, and oxygen,

[0249] when performing SIMS analysis on the entire region from the surface of the substrate on which the piezoelectric film is formed to a depth of 1 μm toward the surface of the substrate opposite to the surface on which the piezoelectric film is formed among the substrates, the concentration of potassium is 5E15 cm -3 or less, the concentration of sodium is 5E15 cm -3 or less,

[0250] and the orientation ratio in the (001) plane direction of the crystal constituting the piezoelectric film is 96% or more.

[0251] (Supplementary Note 2)

[0252] The laminated substrate according to Supplementary Note 1, wherein

[0253] The piezoelectric constant e of the aforementioned piezoelectric film 31 is 7 C / m 2 or more.

[0254] (Supplementary Note 3)

[0255] The laminated substrate according to Supplementary Note 1 or 2, wherein

[0256] The aforementioned substrate is any one of a semiconductor substrate, a resin substrate, a glass substrate, and a metal substrate.

[0257] (Supplementary Note 4)

[0258] The laminated substrate according to any one of Supplementary Notes 1 to 3, wherein

[0259] The aforementioned substrate is a silicon substrate,

[0260] and the aforementioned substrate is formed with semiconductor elements.

[0261] (Supplementary Note 5)

[0262] The laminated substrate according to Supplementary Note 4, wherein

[0263] The aforementioned substrate has a protective film for protecting the aforementioned semiconductor elements.

[0264] (Supplementary Note 6)

[0265] The laminated substrate according to Supplementary Note 4 or 5, wherein

[0266] The aforementioned semiconductor element has either a region doped with a p-type or n-type dopant (impurity) or a region ion-implanted with the aforementioned dopant.

[0267] (Supplementary Note 7)

[0268] The laminated substrate according to any one of Supplementary Notes 1 to 6, which includes a lower electrode film formed by film deposition between the aforementioned substrate and the aforementioned piezoelectric film.

[0269] (Supplementary Note 8)

[0270] According to another aspect of the present application, there is provided a method for manufacturing a laminated substrate, which includes:

[0271] a step of preparing a substrate; and

[0272] a step of forming a piezoelectric film by sputtering method on the aforementioned substrate, the piezoelectric film being composed of an alkali metal niobium oxide containing potassium, sodium, niobium, and oxygen

[0273] In the process of forming the piezoelectric film as described above, the film formation temperature is set to be 400 °C or higher and lower than 500 °C, the oxygen partial pressure is set to be 0.0025 Pa or higher and less than 0.01 Pa, and the atmosphere pressure is set to be 0.03 Pa or higher and less than 0.1 Pa.

[0274] (Supplementary Note 9)

[0275] According to another aspect of the present application, there is provided a piezoelectric element or a piezoelectric device module, comprising:

[0276] A substrate;

[0277] A lower electrode film formed by film formation on the above-mentioned substrate; and

[0278] A piezoelectric film formed by film formation on the above-mentioned substrate, the piezoelectric film being composed of an alkali metal niobium oxide containing potassium, sodium, niobium and oxygen,

[0279] When performing SIMS analysis on the entire area within a depth of 1 μm from the surface of the above-mentioned substrate on which the above-mentioned piezoelectric film is formed to the surface of the above-mentioned substrate on the opposite side of the above-mentioned surface on which the above-mentioned piezoelectric film is formed among the above-mentioned substrates, the concentration of potassium is 5E15 cm -3 or less, the concentration of sodium is 5E15 cm -3 or less,

[0280] The orientation rate in the (001) plane orientation of the crystal constituting the above-mentioned piezoelectric film is 96% or higher.

[0281] (Supplementary Note 10)

[0282] The piezoelectric element or piezoelectric device module according to Supplementary Note 9 includes an upper electrode film formed by film formation on the above-mentioned piezoelectric film.

[0283] (Supplementary Note 11)

[0284] The piezoelectric element or piezoelectric device module according to Supplementary Note 9 or 10 includes a lower electrode film formed by film formation between the above-mentioned substrate and the above-mentioned piezoelectric film.

[0285] (Supplementary Note 12)

[0286] The laminated substrate according to any one of Supplementary Notes 1 to 7 or the piezoelectric element or piezoelectric device module according to any one of Supplementary Notes 9 to 11, wherein,

[0287] There are no traces resulting from pasting at the interface between the aforementioned substrate and the aforementioned piezoelectric film, at the interface between the aforementioned substrate and the aforementioned lower electrode film (or the lower adhesion layer when the lower adhesion layer is included), or at the interface between the aforementioned lower electrode film and the aforementioned piezoelectric film. It should be noted that the traces resulting from pasting refer to inclusions used in pasting, the distribution of impurities not originating from film formation processes, etc.

Claims

1. A laminate substrate comprising a substrate and a piezoelectric film formed on the substrate, wherein the piezoelectric film is composed of an alkali metal niobium oxide containing potassium, sodium, niobium and oxygen, When SIMS analysis was performed on the entire region of the substrate from the surface of the substrate on which the piezoelectric film was formed toward the surface of the substrate opposite to the surface on which the piezoelectric film was formed to a depth of 1 μm, the potassium concentration was 5E15 cm -3 Below, the concentration of sodium is 5E15cm -3 the following, The orientation rate of the (001) plane of the crystal constituting the piezoelectric film is 96% or more.

2. The laminate substrate according to claim 1, wherein: The piezoelectric constant e of the piezoelectric film 31 7C / m 2 above.

3. The laminated substrate according to claim 1 or 2, wherein: The substrate is any one of a semiconductor substrate, a resin substrate, a glass substrate, and a metal substrate.

4. The laminated substrate according to claim 1 or 2, wherein: The substrate is a silicon substrate, The substrate has a semiconductor element formed thereon.

5. The laminated substrate according to claim 4, wherein: The substrate has a protective film formed thereon for protecting the semiconductor element.

6. A method for manufacturing a laminated substrate, comprising: a step of preparing a substrate; and a step of forming a piezoelectric film on the substrate by sputtering, wherein the piezoelectric film is composed of an alkali metal niobium oxide containing potassium, sodium, niobium and oxygen; In the step of forming the piezoelectric film, the film forming temperature is set to 400° C. or higher and lower than 500° C., the oxygen partial pressure is set to 0.0025 Pa or higher and lower than 0.01 Pa, and the atmosphere pressure is set to 0.03 Pa or higher and lower than 0.1 Pa.

7. A piezoelectric element comprising a substrate and a piezoelectric film formed on the substrate, wherein the piezoelectric film is composed of an alkali metal niobium oxide containing potassium, sodium, niobium and oxygen. When SIMS analysis was performed on the entire region of the substrate from the surface of the substrate on which the piezoelectric film was formed toward the surface of the substrate opposite to the surface on which the piezoelectric film was formed to a depth of 1 μm, the potassium concentration was 5E15 cm -3 Below, the concentration of sodium is 5E15cm -3 the following, The orientation rate of the crystals constituting the piezoelectric film in the (001) plane direction is 96% or more.

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