Piezoelectric laminate, method for manufacturing piezoelectric laminate, sputtering target material, and method for manufacturing sputtering target material

Abstract

To provide a piezoelectric laminate having a large-diameter piezoelectric film in which the composition of K, Na, and Nb satisfies a predetermined relationship over the entire inner area of the main surface except for the peripheral portion.SOLUTION: A piezoelectric laminate includes substrate having a main surface with a diameter of 3 inches or more, and a piezoelectric film formed on the substrate and formed of an alkaline niobium oxide containing K, Na, Nb, and O, and the composition of K, Na, and Nb in the piezoelectric film satisfies the relationship of 0.94≤(K+Na) / Nb≤1.03 over the entire inner area of the main surface of the piezoelectric film except for the peripheral portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a piezoelectric laminate, a method for manufacturing a piezoelectric laminate, a sputtering target material, and a method for manufacturing a sputtering target material. [Background technology]

[0002] Piezoelectric materials are widely used in functional electronic components such as sensors, actuators, etc. Piezoelectric materials containing potassium (K), sodium (Na), niobium (Nb), and oxygen (O) have been proposed, and a laminate (hereinafter referred to as a piezoelectric laminate) having a piezoelectric film (KNN film) formed by sputtering using such a piezoelectric material has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-076730 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses that the composition of the KNN film can be adjusted by adjusting the composition of the target material. However, the technique described in Patent Document 1 is not suitable for mass-produced targets, such as those with a surface area of ​​44.2 cm2 exposed to plasma (sputtering surface). 2 When a KNN film is deposited on a large substrate with a diameter of 3 inches or more by sputtering using the above target material, even if the composition ((K+Na) / Nb) of the target material is adjusted so that the composition ((K+Na) / Nb) of the KNN film falls within the specified range, there may be portions on the main surface of the KNN film where the composition does not satisfy the specified range. This is a new problem that was first identified through the intensive research of the inventors and others.

[0005] The present disclosure aims to provide a piezoelectric laminate having a piezoelectric film in which the compositions of K, Na, and Nb satisfy a predetermined relationship over the entire inner area of ​​the main surface except for the peripheral edge, and related techniques. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a substrate having a main surface with a diameter of 3 inches or more; a piezoelectric film formed on the substrate and made of an alkali niobium oxide containing K, Na, Nb, and O; The present invention provides a piezoelectric laminate in which the compositions of K, Na, and Nb in the piezoelectric film satisfy the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire inner area of ​​the main surface of the piezoelectric film except for the peripheral edge portion, and a manufacturing technique for the same.

[0007] According to another aspect of the present disclosure, A sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O, When depositing a piezoelectric film using the sputtering method, the surface area exposed to plasma is 44.2 cm 2 and the thickness is 3mm or more, There is provided a sputtering target material in which the Vickers hardness of the surface exposed to the plasma is 150 or more over the entire inner area of ​​the surface exposed to the plasma excluding the peripheral edge.

[0008] According to yet another aspect of the present disclosure, It is made of a sintered body containing an oxide containing K, Na, Nb, and O, and the area of ​​the surface exposed to plasma is 44.2 cm 2 A method for manufacturing a target material having a thickness of 3 mm or more, (a) a step of mixing a powder consisting of a K compound, a powder consisting of a Na compound, and a powder consisting of a Nb compound in a predetermined ratio, or a step of mixing a powder consisting of a compound containing K and Nb with a powder consisting of a compound containing Na and Nb in a predetermined ratio to obtain a mixture; (b) applying a predetermined pressure to the mixture while heating the mixture to form a mold having a main surface area of ​​44.2 cm 2 and a step of obtaining a sintered body having a thickness of 3 mm or more. In (b), the pressure is increased by 1 kgf / cm per minute until the specified pressure is reached. 2 The method for producing a sputtering target material includes gradually increasing the pressure at the following rate, and maintaining the temperature in the plane that will become the main surface of the sintered body at 900 to 1200°C for 12 hours or more. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to obtain a piezoelectric laminate having a large-diameter piezoelectric film in which the compositions of K, Na, and Nb satisfy a predetermined relationship over the entire inner area of ​​the main surface except for the peripheral edge portion. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of a cross-sectional structure of a piezoelectric laminate according to an embodiment of the present disclosure. [Figure 2] 10A and 10B are diagrams illustrating modified examples of the cross-sectional structure of the piezoelectric laminate according to an embodiment of the present disclosure. [Figure 3] FIG. 10 is a diagram showing a cutting line of a piezoelectric film when measuring the composition of the piezoelectric film. [Figure 4] 1 is a diagram illustrating an example of a schematic configuration of a piezoelectric device module according to an aspect of the present disclosure. [Figure 5] 1 is a diagram showing an example of a schematic configuration of a sputtering target material according to one embodiment of the present disclosure. [Figure 6] FIG. 2 is a plan view of the sputtered surface showing the measurement points of Vickers hardness. [Figure 7] FIG. 1 is a diagram showing a schematic diagram of a hot press device used when producing a sputtering target material. [Figure 8] FIG. 1A is a diagram showing an example of a hot press treatment sequence according to one embodiment of the present disclosure, and FIGS. 1B and 1C are diagrams showing modified examples of the hot press treatment sequence according to one embodiment of the present disclosure. [Figure 9] 10A and 10B are diagrams illustrating modified examples of the cross-sectional structure of the piezoelectric device module according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Knowledge gained by the inventors> The target material used in mass production, specifically, the surface exposed to plasma (hereinafter also referred to as the "sputtering surface") has an area of ​​44.2 cm 2 As described above, when a large-diameter KNN film is deposited by sputtering on a large-diameter substrate with a diameter of 3 inches or more using a large target material with a thickness of 3 mm or more, there are inevitably portions in the KNN film where the K, Na, and Nb compositions do not satisfy the specified relationship, for example, portions where the value of (K + Na) / Nb is outside the specified range. In other words, a KNN film with a uniform in-plane distribution of composition cannot be obtained. This is a new problem discovered by the inventors. Note that K, Na, and Nb in (K + Na) / Nb represent the number of K atoms, Na atoms, and Nb atoms, respectively, contained per unit volume of the KNN film.

[0012] The inventors have conducted extensive research into the above-mentioned problem. As a result, they have found that the area of ​​the sputtering surface is 44.2 cm 2 We have found that when using large targets with thicknesses of 3 mm or more, microcracks occur on the sputtering surface (target material) during pre-sputtering and sputter deposition. This causes areas in the KNN film deposited on the substrate where the K, Na, and Nb compositions do not satisfy the required relationships. When cracks occur on the sputtering surface, abnormal discharges occur at the cracked areas during pre-sputtering and sputter deposition. In the areas where abnormal discharges occur, the temperature rises locally, becoming higher than in other areas, which promotes the local volatilization of K and Na. As a result, areas in the sputtered KNN film where the K, Na, and Nb compositions do not satisfy the required relationships appear.

[0013] The inventors conducted extensive research into the causes of cracks occurring in target materials. As a result, they discovered that there are areas on the sputtering surface where the bonds between particles are weak, and that in target materials of a certain size or larger, cracks occur because the area cannot withstand the stress applied to those areas during pre-sputtering or sputter deposition. The inventors also discovered that, while a decrease in the hardness of the target material is observed in the areas where the bonds between particles are weak, cracks do not occur in areas where the Vickers hardness is above a certain value. In order to prevent cracks from occurring during pre-sputtering or sputter deposition, the area of ​​the sputtering surface must be 44.2 cm2 or less. 2 The minimum practical power density for the target material is estimated to be 2.7 W / cm. 2 It was found that when a power of 10 ...

[0014] The inventors have conducted extensive research into a method for preventing weak interparticle bonding on the sputtering surface of a target material, i.e., for achieving a Vickers hardness of a predetermined value or higher across the entire sputtering surface. KNN target material can be produced by, for example, filling a jig with a mixture of raw material powders, such as a powder of a K compound, a powder of a Na compound, and a powder of a Nb compound, in a predetermined ratio, and then hot pressing the mixture. The jig is made of a material such as graphite, and has a main surface area of ​​44.2 cm. 2 As described above, it is configured to be possible to form a sintered body with a thickness of 3 mm or more. In the course of their research, the inventors discovered that when producing a target material, "uneven filling when filling the raw material powder into the jig" and "uneven sintering temperature (firing temperature) in the surface direction of the main surface of the sintered body (uneven sintering temperature)" are factors that cause low Vickers hardness and weak interparticle bonding in some areas. However, even if attempts are made to prevent uneven filling of the raw material powder and uneven sintering temperature when producing a target material, it is difficult to completely eliminate these unevenness. In particular, when the area of ​​the sputtering surface is 44.2 cm 2 When producing the above target material, it is practically very difficult to completely eliminate unevenness in the filling of the raw material powder and unevenness in the sintering temperature.

[0015] The inventors conducted extensive research into other factors that prevent the appearance of weak interparticle bonds on the sputtering surface of the target material. As a result, they discovered that the sintering time (firing time) of the raw material powder is important. That is, they discovered that by gradually increasing the applied pressure at a predetermined rate until a predetermined pressure is reached during hot pressing, and by using a sintering time that is much longer than conventional sintering times, it is possible to prevent the appearance of weak interparticle bonds across the entire sputtering surface, even if there are "uneven packing of raw material powder" or "uneven sintering temperature."

[0016] The present disclosure has been made based on the above-mentioned findings and problems that the inventors have obtained.

[0017] <One aspect of the present disclosure> Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings.

[0018] (1) Structure of the piezoelectric laminate 1, a laminate 10 having a piezoelectric film according to this embodiment (hereinafter also referred to as piezoelectric laminate 10) includes a substrate 1, a lower electrode film 2 provided on the substrate 1, a piezoelectric film (piezoelectric thin film) 3 provided on the lower electrode film 2, and an upper electrode film 4 provided on the piezoelectric film 3. In this embodiment, an example will be described in which one laminate structure (a structure formed by laminating at least the lower electrode film 2, the piezoelectric film 3, and the upper electrode film 4) is provided on one substrate 1.

[0019] The substrate 1 has a main surface with a diameter of 3 inches or more. The substrate 1 has a circular outer shape in a plan view. However, the outer shape of the substrate 1 is not limited to a circle. In this case, the substrate 1 preferably has a main surface with an inscribed circle having a diameter of 3 inches or more. A suitable substrate 1 is a single-crystal silicon (Si) substrate 1a on which a surface oxide film (SiO2 film) 1b, such as a thermal oxide film or a CVD (Chemical Vapor Deposition) oxide film, is formed, i.e., a Si substrate having a surface oxide film. Alternatively, as shown in FIG. 2, a Si substrate 1a having an insulating film 1d formed on its surface from an insulating material other than SiO2 may also be used. Alternatively, a Si substrate 1a with an exposed Si(100) or Si(111) surface, i.e., a Si substrate without a surface oxide film 1b or insulating film 1d, may also be used. Alternatively, a metal substrate made of a metal material such as an SOI (Silicon On Insulator) substrate, a quartz glass (SiO2) substrate, a gallium arsenide (GaAs) substrate, a sapphire (Al2O3) substrate, or stainless steel (SUS) can be used as the substrate 1. The thickness of the single crystal Si substrate 1a can be, for example, 300 to 1000 μm, and the thickness of the surface oxide film 1b can be, for example, 1 to 4000 nm.

[0020] In this specification, when a numerical range such as "300 to 1000 μm" is expressed, it means that the lower limit and upper limit are included in the range. For example, "300 to 1000 μm" means "300 μm or more and 1000 μm or less." The same applies to other numerical ranges.

[0021] The lower electrode film 2 can be formed using, for example, platinum (Pt). The lower electrode film 2 is a polycrystalline film. Hereinafter, a polycrystalline film formed using Pt will also be referred to as a Pt film. It is preferable that the (111) plane of the Pt film is parallel to the main surface of the substrate 1 (including the case where the (111) plane is inclined at an angle of ±5° or less with respect to the main surface of the substrate 1), i.e., the Pt film is oriented in the (111) plane. The Pt film being oriented in the (111) plane means that no peaks other than those attributable to the (111) plane are observed in the X-ray diffraction pattern obtained by X-ray diffraction (XRD) measured on the surface of the KNN film 3. Thus, it is preferable that the main surface of the lower electrode film 2 (the surface underlying the piezoelectric film 3) is composed of the Pt (111) plane. The lower electrode film 2 can be formed using a sputtering method, a vapor deposition method, or the like. The lower electrode film 2 may be formed using various metals other than Pt, such as gold (Au), ruthenium (Ru), or iridium (Ir), alloys containing these as main components, or metal oxides such as strontium ruthenate (SrRuO3, abbreviated as SRO) or lanthanum nickelate (LaNiO3, abbreviated as LNO). The lower electrode film 2 may be a single layer film formed using the above-mentioned metals or metal oxides. The lower electrode film 2 may be a laminate of a Pt film and a film mainly composed of SRO provided on the Pt film, or a laminate of a Pt film and a film mainly composed of LNO provided on the Pt film. In order to improve adhesion between the substrate 1 and the lower electrode film 2, an adhesion layer 6 containing, for example, titanium (Ti), tantalum (Ta), titanium oxide (TiO2), nickel (Ni), ruthenium oxide (RuO2), iridium oxide (IrO2), zinc oxide (ZnO), or the like as a main component may be provided between the substrate 1 and the lower electrode film 2. The adhesion layer 6 can be formed using techniques such as sputtering and vapor deposition. The thickness of the lower electrode film 2 (the total thickness of each layer when the lower electrode film 2 is a laminate) can be, for example, 100 to 400 nm, and the thickness of the adhesion layer 6 can be, for example, 1 to 200 nm.

[0022] The piezoelectric film 3 is, for example, a film formed from an alkali niobate oxide containing potassium (K), sodium (Na), niobium (Nb), and oxygen (O). That is, the piezoelectric film 3 is a film mainly composed of an alkali niobate oxide containing K, Na, Nb, and O. The piezoelectric film 3 can be formed using an alkali niobate 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 within the range of 0 < x < 1, preferably 0.4 ≤ x ≤ 0.8. The piezoelectric film 3 becomes a polycrystalline film of KNN (hereinafter also referred to as the KNN film 3). Also, the crystal structure of KNN is a perovskite structure. That is, the KNN film 3 has a perovskite structure. Further, it is preferable that more than half of the crystals constituting the KNN film 3 have a columnar structure. In this specification, the crystal system of KNN is regarded as a tetragonal system. The KNN film 3 can be formed using a sputtering method.

[0023] The crystals constituting the KNN film 3 are preferably preferentially oriented in the (001) plane direction 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 1d, etc., it is the Si substrate 1a). That is, the main surface of the KNN film 3 (the surface serving as the base for the upper electrode film 4) is preferably 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.

[0024] As used herein, the crystals constituting the KNN film 3 being oriented in the (001) plane direction means that the (001) plane of the crystals constituting the KNN film 3 is parallel or approximately parallel to the main surface of the substrate 1. Furthermore, the crystals constituting the KNN film 3 being preferentially oriented in the (001) plane direction means that many of the crystals have their (001) planes parallel or approximately parallel to the main surface of the substrate 1. For example, it is preferable that 80% or more of the crystals constituting the KNN film 3 are oriented in the (001) plane direction relative to the main surface of the substrate 1. That is, the orientation rate of the crystals constituting the KNN film 3 in the (001) plane direction is, for example, preferably 80% or more, and more preferably 90% or more. The term "orientation rate" as used herein refers to a value calculated by the following equation (1) based on the peak intensity of the X-ray diffraction pattern (2θ / θ) obtained by XRD measurement of the KNN film 3.

[0025] (Number 1) Orientation rate (%) = {(001) peak intensity / ((001) peak intensity + (110) peak intensity)} × 100

[0026] The "(001) peak intensity" in the above equation (1) refers to the intensity of a diffraction peak due to crystals oriented in the (001) plane direction (i.e., crystals whose (001) plane is parallel to the main surface of the substrate 1) among the crystals constituting the KNN film 3 in the X-ray diffraction pattern obtained by performing XRD measurement on the KNN film 3, and is the intensity of a peak appearing within a 2θ range of 20° to 23°. When multiple peaks appear within a 2θ range of 20° to 23°, the intensity of the highest peak is used. The "(110) peak intensity" in the above equation (1) refers to the intensity of a diffraction peak due to crystals oriented in the (110) plane direction (i.e., crystals whose (110) plane is parallel to the main surface of the substrate 1) among the crystals constituting the KNN film 3 in the X-ray diffraction pattern obtained by performing XRD measurement on the KNN film 3, and is the intensity of a peak appearing within a 2θ range of 30° to 33°. When multiple peaks appear within the 2θ range of 30° to 33°, the intensity is that of the highest peak.

[0027] The KNN film 3 has a major surface (upper surface) with a diameter of 3 inches or more, i.e., a large-diameter major surface. The K, Na, and Nb compositions of the KNN film 3 satisfy the relationship of 0.94≦(K+Na) / Nb≦1.03, preferably 0.96≦(K+Na) / Nb≦1.00, throughout the entire inner area of ​​the major surface of the KNN film 3, excluding the peripheral edge. Here, K, Na, and Nb in the formula (K+Na) / Nb represent the numbers of K atoms, Na atoms, and Nb atoms contained per unit volume of the KNN film 3, respectively. Thus, the distribution of the K, Na, and Nb compositions of the KNN film 3 is uniform (in-plane uniform) throughout the entire inner area of ​​the major surface of the KNN film 3, excluding the peripheral edge.

[0028] Here, "the compositions of K, Na, and Nb in the KNN film 3 satisfy the relationship of 0.94≦(K+Na) / Nb≦1.03 throughout the entire inner area of ​​the main surface of the KNN film 3 excluding the peripheral edge portion" means that, as shown in FIG. 3, the KNN film 3 is cut into a grid at intervals of 1 cm in a region 3b on the main surface of the KNN film 3 that is inside the peripheral region 3a 5 mm from the edge (region 3b excluding the peripheral region 3a 5 mm from the edge), and among the obtained samples, the region 3b is cut into a grid at intervals of 1 cm. 2 When the compositions of the above samples (32 samples in the case of the KNN film 3 having a main surface with a diameter of 3 inches) were measured, all samples satisfied the relationship 0.94≦(K+Na) / Nb≦1.03. In FIG. 3, the cutting line of the KNN film 3 is indicated by a dotted line. Note that the "planar area" here refers to the area of ​​the main surface of the KNN film 3 when viewed from above in the vertical direction. In addition, in this specification, "the entire inner area of ​​the main surface of the KNN film 3 excluding the peripheral portion" is also referred to as "the entire main surface of the KNN film 3."

[0029] The K and Na compositions in the KNN film 3 can be measured by atomic absorption spectrometry (AAS) or the like, and the Nb composition can be measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) or the like. Specifically, first, each sample obtained by cutting the KNN film 3 is thermally decomposed with sulfuric acid, nitric acid, hydrofluoric acid, and hydrochloric acid, and then heated and dissolved in dilute hydrogen peroxide and dilute hydrofluoric acid to a constant volume. This solution is subjected to AAS and ICP-AES to determine the K, Na, and Nb contents in the sample and convert them into atomic ratios. This allows the K, Na, and Nb compositions in the KNN film 3 to be obtained. AAS can be performed using, for example, a Z-2300 manufactured by Hitachi High-Technologies Corporation, and ICP-AES can be performed using, for example, a PS3520VDDII manufactured by Hitachi High-Tech Science Corporation. It is also possible to measure the compositions of K, Na, and Nb in the KNN film 3 using only energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence spectroscopy (XRF), and ICP-AES. However, in this case, the analytical sensitivity of K and Na is low, making it difficult to accurately measure the compositions in the KNN film 3, and the composition of the KNN film 3 cannot be accurately evaluated. As described above, by measuring the compositions of K, Na, and Nb in the KNN film 3 using both AAS and ICP-AES, it becomes possible to accurately evaluate the composition of the KNN film 3.

[0030] When the composition of K, Na, and Nb in the KNN film 3 satisfies 0.94≦(K+Na) / Nb≦1.03, the dielectric strength of the KNN film 3 can be increased to, for example, 300 kV / cm or more, preferably 500 kV / cm or more. Note that the term "dielectric strength" as used herein refers to the dielectric strength at which a current density of 100 μA / cm is applied when a predetermined electric field is applied in the thickness direction of the KNN film 3. 2 This is the electric field value that is equal to or greater than this.

[0031] By ensuring that the K, Na, and Nb compositions satisfy the above relationship across the entire main surface of the KNN film 3, the dielectric strength voltage of the KNN film 3 can be made uniform (in-plane uniform) across the entire main surface of the KNN film 3. That is, the dielectric strength voltage of the KNN film 3 can be made, for example, 300 kV / cm or higher, preferably 500 kV / cm or higher across the entire main surface. This prevents variations in dielectric strength voltage from occurring among multiple piezoelectric elements 20 (piezoelectric device modules 30) (described below) obtained from a single piezoelectric laminate 10. As a result, the yield and reliability of the piezoelectric elements 20 (piezoelectric device modules 30) can be improved.

[0032] The thickness of the KNN film 3 is, for example, 0.5 μm or more, and preferably 0.5 to 5 μm, across the entire main surface of the KNN film 3. This reliably prevents variations in dielectric strength voltage from occurring among a plurality of piezoelectric elements 20 (piezoelectric device modules 30) (described later) obtained from one piezoelectric laminate 10.

[0033] The alkali niobium oxide constituting the KNN film 3 may be selected from the group consisting of lithium (Li), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), bismuth (Bi), antimony (Sb), vanadium (V), indium (In), Ta, molybdenum (Mo), tungsten (W), chromium (Cr), Ti, zirconium (Zr), hafnium (Hf), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and sulphur dioxide (Sv). The alkali niobium oxide may further contain at least one element (dopant) selected from the group consisting of 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 niobium oxide may be, for example, 5 at % or less (when multiple elements are contained, the total concentration is 5 at % or less).

[0034] The upper electrode film 4 is mainly composed of various metals such as Pt, Au, Al, and Cu, or alloys thereof. The upper electrode film 4 can be formed by a method such as sputtering, vapor deposition, plating, or metal paste deposition. Unlike the lower electrode film 2, the upper electrode film 4 does not significantly affect the crystal structure of the KNN film 3. Therefore, the material, crystal structure, and film formation method of the upper electrode film 4 are not particularly limited. Note that an adhesion layer mainly composed of, for example, Ti, Ta, TiO2, Ni, RuO2, or IrO2 may be provided between the KNN film 3 and the upper electrode film 4 to improve adhesion therebetween. The thickness of the upper electrode film 4 can be, for example, 100 to 5000 nm, and if an adhesion layer is provided, the thickness of the adhesion layer can be, for example, 1 to 200 nm.

[0035] (2) Piezoelectric device module configuration FIG. 4 shows a schematic diagram of a device module 30 having a KNN film 3 (hereinafter also referred to as a piezoelectric device module 30). By shaping the above-described piezoelectric laminate 10 into a predetermined shape, an element (device) 20 (element 20 having a KNN film 3, hereinafter also referred to as a piezoelectric element 20) as shown in FIG. 4 is obtained. The piezoelectric device module 30 includes at least the piezoelectric element 20 and a voltage application means 11a or a voltage detection means 11b connected to the piezoelectric element 20. The voltage application means 11a is a means for applying a voltage between the lower electrode film 2 and the upper electrode film 4, and the voltage detection means 11b is a means for detecting a voltage generated between the lower electrode film 2 and the upper electrode film 4. Various known means can be used as the voltage application means 11a and the voltage detection means 11b.

[0036] By connecting the voltage application means 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 by the voltage application means 11a, the KNN film 3 can be deformed. This deformation can actuate various members connected to the piezoelectric device module 30. In this case, examples of applications of the piezoelectric device module 30 include a head for an inkjet printer, a MEMS mirror for a scanner, and a vibrator for an ultrasonic generator.

[0037] By connecting the voltage detection means 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. When the KNN film 3 deforms in response to a change in some 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 with the voltage detection means 11b, it is possible to measure the magnitude of the physical quantity applied to the KNN film 3. In this case, the piezoelectric device module 30 can be used, for example, as an angular velocity sensor, an ultrasonic sensor, a pressure sensor, an acceleration sensor, etc.

[0038] The piezoelectric device module 30 (piezoelectric element 20) is fabricated from a piezoelectric laminate 10 having a KNN film 3 in which the composition of K, Na, and Nb satisfies the relationship 0.94≦(K+Na) / Nb≦1.03 across the entire main surface. This prevents variations in dielectric strength voltage from occurring among multiple piezoelectric device modules 30 (piezoelectric elements 20) obtained from a single piezoelectric laminate 10. In other words, multiple piezoelectric device modules 30 with uniform dielectric strength voltages can be obtained from a single piezoelectric laminate 10. In this way, uniform dielectric strength voltages among multiple piezoelectric device modules 30 can improve the yield and reliability of the piezoelectric device modules 30.

[0039] (3) Methods for manufacturing piezoelectric laminates, piezoelectric elements, and piezoelectric device modules A method for manufacturing the above-mentioned piezoelectric stack 10, piezoelectric element 20, and piezoelectric device module 30 will now be described.

[0040] (Deposition of adhesion layer and bottom electrode film) First, a large-diameter substrate 1 having a main surface with a diameter of 3 inches or more is prepared, and an adhesion layer 6 (e.g., a Ti layer) and a lower electrode film 2 (e.g., a Pt film) are formed in this order on one of the main surfaces of the substrate 1 by, for example, sputtering. Alternatively, a substrate 1 may be prepared on which the adhesion layer 6 and the lower electrode film 2 have already been formed on one of the main surfaces.

[0041] The conditions for providing the adhesive layer 6 are exemplified as follows. Temperature (substrate temperature): 100 to 500°C, preferably 200 to 400°C Discharge power density: 12.3~18.5W / cm 2 , preferably 13.5 to 17.3 W / cm 2 Atmosphere: Argon (Ar) gas atmosphere Atmospheric pressure: 0.1 to 0.5 Pa, preferably 0.2 to 0.4 Pa Time: 30 seconds to 3 minutes, preferably 45 seconds to 2 minutes

[0042] The conditions for forming the lower electrode film 2 are exemplified as follows. Temperature (substrate temperature): 100 to 500°C, preferably 200 to 400°C Discharge power density: 12.3~18.5W / cm 2 , preferably 13.5 to 17.3 W / cm 2 Atmosphere: Ar gas atmosphere Atmospheric pressure: 0.1 to 0.5 Pa, preferably 0.2 to 0.4 Pa Time: 3 to 10 minutes, preferably 4 to 8 minutes, more preferably 5 to 6 minutes

[0043] (KNN film production) After the formation of the adhesion layer 6 and the lower electrode film 2 is completed, the KNN film 3 is subsequently formed on the lower electrode film 2 by a sputtering method such as RF magnetron sputtering. A large target material 100 is used here, which is formed from a KNN sintered compact and has a minimum Vickers hardness of 150 on the sputtering surface 101. This target material 100, described below, has a high Vickers hardness across the entire sputtering surface 101. The composition of the KNN film 3 can be adjusted, for example, by controlling the composition of the target material 100. Specifically, the target material 100 is used, whose composition is controlled to satisfy the relationship R1 > R2, where R1 is the average value of (K + Na) / Nb on the sputtering surface 101 and R2 is the average value of (K + Na) / Nb on the main surface of the KNN film 3 to be formed. Details of the target material 100 will be described later.

[0044] The following conditions are exemplified as conditions for forming the KNN film 3. The film formation time can be set appropriately depending on the thickness of the KNN film 3. Discharge power density: 2.7~4.1W / cm 2 , preferably 2.8 to 3.8 W / cm 2 Atmosphere: an atmosphere containing at least oxygen (O2) gas, preferably a mixed gas atmosphere of Ar gas and O2 gas Atmospheric pressure: 0.2 to 0.5 Pa, preferably 0.2 to 0.4 Pa Ratio of Ar gas partial pressure to O2 gas (Ar gas partial pressure / O2 gas partial pressure): 30 / 1 to 20 / 1 Temperature (substrate temperature): 500 to 700°C, preferably 550 to 650°C Film forming speed: 0.5~4μm / hr

[0045] As will be described later, since the Vickers hardness of the sputtering surface 101 of the target material 100 is high over the entire surface, it is possible to prevent cracks from occurring in the sputtering surface 101 during pre-sputtering and sputtering film formation. 2 Even when sputtering is performed at a high discharge power density such as 2000 to 3000 W / 12-inch diameter circular hole), i.e., when sputtering is performed at a high rate, cracks can be prevented from occurring on the sputtering surface 101. This prevents abnormal discharge from occurring over the entire sputtering surface during pre-sputtering or sputtering, thereby preventing localized volatilization of K and Na on the sputtering surface 101. By using the target material 100 described below for sputtering the KNN film 3, it is possible to obtain a KNN film 3 whose K, Na, and Nb compositions satisfy the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire main surface, even when a large-diameter KNN film 3 is formed on a large-diameter substrate 1 (on a large-diameter bottom electrode film 2 formed on the large-diameter substrate 1). Although some alkali from the target material 100 (sputtering surface 101) scatters during pre-sputtering and sputtering film formation, since the target material 100 satisfies the relationship R1>R2 described above, a KNN film 3 can be obtained in which the composition of K, Na, and Nb satisfies the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire main surface.

[0046] (Deposition of upper electrode film) After the deposition of the KNN film 3 is completed, the upper electrode film 4 is deposited on the KNN film 3 by, for example, sputtering. The conditions for depositing the upper electrode film 4 can be the same as those for depositing the above-mentioned lower electrode film 2. This results in a piezoelectric stack 10 as shown in FIG.

[0047] (Fabrication of piezoelectric elements and piezoelectric device modules) The obtained piezoelectric laminate 10 is then shaped into a predetermined shape by etching or the like (microfabrication is performed to a predetermined pattern). This results in a piezoelectric element 20 as shown in Fig. 4, and a piezoelectric device module 30 is obtained by connecting a voltage application means 11a or a voltage detection means 11b to the piezoelectric element 20. Examples of etching methods that can be used include dry etching such as reactive ion etching, and wet etching using a predetermined etching solution.

[0048] When shaping the piezoelectric stack 10 by dry etching, a photoresist pattern serving as an etching mask for dry etching is formed on the piezoelectric stack 10 (e.g., the upper electrode film 4) by a photolithography process or the like. A noble metal film (metal mask) such as a Cr film, Ni film, Pt film, or Ti film may be formed as the etching mask by a sputtering method. Then, dry etching is performed on the piezoelectric stack 10 (the upper electrode film 4, the KNN film 3, etc.) using a gas containing a halogen element as the etching gas. Examples of halogen elements include chlorine (Cl) and fluorine (F). Examples of gases that can be used that contain a halogen element include BCl3 gas, SiCl4 gas, Cl2 gas, CF4 gas, and C4F8 gas.

[0049] When the piezoelectric laminate 10 is shaped by wet etching, a silicon oxide (SiO x ) film, etc. Then, the piezoelectric stack 10 is immersed in an etching solution containing an alkaline aqueous solution of a chelating agent but not containing hydrofluoric acid, for example, to perform wet etching on the piezoelectric stack 10 (upper electrode film 4, KNN film 3, etc.). Note that as the etching solution containing an alkaline aqueous solution of a chelating agent but not containing hydrofluoric acid, an etching solution that is a mixture of ethylenediaminetetraacetic acid as a chelating agent, ammonia water, and hydrogen peroxide water can be used.

[0050] (4) Target material composition The structure of the sputtering target material 100 used in sputtering the KNN film 3 will be described in detail below with reference to Fig. 5. The target material 100 is fixed to a backing plate, for example, with an adhesive such as In, and then mounted in a sputtering device so that the sputtering surface 101 is irradiated with plasma. As described above, the "sputtering surface" refers to the surface of the target material 100 that is exposed to plasma during sputtering (the surface that ions collide with during sputtering).

[0051] Fig. 5 is a schematic diagram showing an example of a target material 100 according to this embodiment. In Fig. 5, the target material 100 is shown with the sputtering surface 101 facing upward.

[0052] The target material 100 is formed from a sintered body containing oxides containing K, Na, Nb, and O, i.e., a KNN sintered body. The crystal grains that mainly constitute the KNN sintered body have a perovskite structure. In addition to the oxides containing K, Na, Nb, and O, the KNN sintered body may also contain carbonates, oxalates, and the like derived from the raw materials described below.

[0053] The composition of K, Na, and Nb in the target material 100 ((K + Na) / Nb) satisfies the relationship 0.95≦(K + Na) / Nb≦1.2, preferably 1≦(K + Na) / Nb≦1.1. Here, K, Na, and Nb in the formula (K + Na) / Nb represent the number of K atoms, Na atoms, and Nb atoms, respectively, contained per unit volume of the KNN sintered compact. Thus, the composition of the target material 100 must be slightly K-rich and Na-rich compared to the composition of the KNN film 3 to be deposited. For example, the composition of the target material 100 must be adjusted to satisfy the relationship R1>R2, where R1 is the average value of (K + Na) / Nb within the sputtering surface 101, and R2 is the average value of (K + Na) / Nb within the main surface of the KNN film 3 to be deposited. This is because, in sputter deposition performed with the substrate 1 heated to a high temperature, alkali scattering during the sputtering process causes the (K + Na) / Nb value of the KNN film 3 to deviate slightly from the (K + Na) / Nb value of the target material 100. The amount of this deviation depends on the sputter deposition conditions (substrate temperature, discharge power density, deposition rate, equipment configuration, etc.). By making the composition of the target material 100 slightly richer in K and Na than the composition of the KNN film 3, it is possible to obtain a KNN film 3 in which the K, Na, and Nb compositions satisfy the above relationship across the entire main surface. The composition ((K + Na) / Nb) of the target material 100 can be measured (calculated) by a known method.

[0054] The target material 100 may further contain, as a dopant, at least one element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga. The concentration of the above elements in the target material 100 can be, for example, 5 at % or less (when multiple elements are contained, the total concentration is 5 at % or less).

[0055] The target material 100 has a circular outer shape. That is, the target material 100 has a sputtering surface 101 that is circular in plan view. The outer shape of the target material 100 (the planar shape of the sputtering surface 101) can be various shapes such as an ellipse, a rectangle, or a polygon, in addition to a circle. The area of ​​the sputtering surface 101 is 44.2 cm 2 That is all. For example, the sputtering surface 101 has an area larger than that of a 3-inch substrate 1. Note that the "area of ​​the sputtering surface 101" here means the area of ​​the sputtering surface 101 when viewed from above in the vertical direction. The target material 100 has a thickness of 3 mm or more. Note that the upper limit of the thickness of the target material 100 is not particularly limited, but can be, for example, 20 mm or less.

[0056] The Vickers hardness of sputtering surface 101 (hereinafter also simply referred to as "Vickers hardness") is 150 or more, preferably 200 or more, over the entire inner area excluding the peripheral edge of sputtering surface 101. In other words, the minimum value of Vickers hardness within sputtering surface 101 is 150 or more, preferably 200 or more.

[0057] Here, "the Vickers hardness of sputtering surface 101 is 150 or more over the entire inner area of ​​sputtering surface 101 excluding the peripheral edge portion" means that, as shown in FIG. 6, hardness measurements were made at 1 cm intervals in a grid pattern on area 101b (area inside the area 5 mm from the edge) of sputtering surface 101 excluding area 101a 5 mm from the edge (peripheral edge portion), and all points (the outer shape of sputtering surface 101 is circular and the area of ​​sputtering surface 101 is 44.2 cm) 2 This means that the Vickers hardness is 150 or more (37 points if the hardness is 100 or more). In FIG. 6, the measurement points of the Vickers hardness are indicated by ● marks. In this specification, "the entire inner area excluding the periphery of the sputtering surface 101" is also referred to as "the entire sputtering surface."

[0058] The Vickers hardness was measured by making an indentation on the test surface (sputtered surface 101) using a micro Vickers hardness tester HM-114 manufactured by Mitutoyo Corporation in accordance with JIS R 1610 under the following test conditions: Specifically, the Vickers hardness was calculated from the test force when a depression (indentation) was made on the test surface using a Vickers indenter (a pyramidal indenter with a square base and an angle of 136 degrees between two opposing surfaces) and the surface area of ​​the indentation calculated from the diagonal length of the indentation. (Test conditions) Atmosphere: Atmospheric Temperature, humidity: 25℃ 52% Test force: 1.0 kgf Load application acceleration: 10μm / s Holding time: 15sec Number of measurement points: 37 points

[0059] As described above, by having a Vickers hardness of 150 or more over the entire sputtering surface, cracks can be suppressed from occurring on the sputtering surface 101 during pre-sputtering and sputtering deposition. This makes it possible to avoid abnormal discharge over the entire sputtering surface during sputtering deposition. Therefore, it is possible to avoid the appearance of areas with locally elevated temperatures on the sputtering surface 101 during sputtering deposition, and to avoid local volatilization of K and Na on the sputtering surface 101. As a result, a large-diameter KNN film 3 can be obtained in which the compositions of K, Na, and Nb satisfy the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire main surface.

[0060] The inventors have found that if the Vickers hardness is 150 or more over the entire sputtering surface, the area of ​​the sputtering surface 101 is 44.2 cm 2As described above, even with a large target material 100 having a thickness of 3 mm or more, there are no weak interparticle bonds across the entire sputtering surface, and it has been confirmed that cracks and abnormal discharges during pre-sputtering and sputtering deposition can be avoided, and compositional deviations of K, Na, and Nb in the sputtered KNN film 3 (hereinafter also referred to as "compositional deviations of the KNN film 3") can be sufficiently suppressed. Furthermore, if the Vickers hardness is 200 or higher across the entire sputtering surface, the above-mentioned cracks and abnormal discharges can be reliably avoided, and compositional deviations of the KNN film 3 can be reliably suppressed.

[0061] Furthermore, by suppressing the occurrence of cracks, the K, Na, and Nb compositions of each of the multiple KNN films 3 repeatedly formed using one target material 100 satisfy the relationship 0.94≦(K+Na) / Nb≦1.03 across the entire main surface of the KNN film 3. In other words, run-to-run variations in the composition of the KNN film 3 can be suppressed during the fabrication of the piezoelectric stack 10. As a result, the composition of the KNN film 3 can be made uniform among the multiple piezoelectric stacks 10, further improving the yield and reliability of the piezoelectric elements 20 and piezoelectric device modules 30.

[0062] If the Vickers hardness is not 150 or more over the entire sputtering surface, that is, if there are areas (places) on the sputtering surface 101 where the Vickers hardness is less than 150, cracks will occur during pre-sputtering or sputtering deposition, starting from the areas where the Vickers hardness is less than 150, and abnormal discharge will occur at the cracked areas during sputtering deposition. As a result, areas that do not satisfy the above relationship may appear within the main surface of the sputtered KNN film 3.

[0063] There is no particular upper limit to the Vickers hardness. However, to further increase the Vickers hardness, a longer sintering time (longer heating time) is required in the hot press process described below. Therefore, from the viewpoints of ensuring productivity and suppressing cost increases, the Vickers hardness can be set to, for example, 650 or less. That is, the Vickers hardness can be set to, for example, a range of 150 or more and 650 or less, preferably a range of 200 or more and 650 or less.

[0064] The relative density of the target material 100 is 60% or more, preferably 70% or more, and more preferably 80% or more over the entire sputtering surface. The relative density (%) here is a value calculated by (measured density / KNN theoretical density) × 100. The KNN theoretical density is 4.51 g / cm. 3 This makes it possible to reliably prevent the occurrence of abnormal discharge over the entire sputtering surface when the KNN film 3 is formed by sputtering.

[0065] Furthermore, it is preferable that the target material 100 has high resistance. For example, it is preferable that the volume resistivity of the target material 100 is 1000 kΩcm or more, and more preferably 1000 kΩcm or more over the entire sputtering surface. This makes it possible to obtain a KNN film 3 with good insulating properties. The upper limit of the volume resistivity is not particularly limited, but can be, for example, 100 MΩcm or less.

[0066] (5) Target material manufacturing method A method for manufacturing a target material 100 having a Vickers hardness of 150 or more over the entire sputtering surface will be described in detail below.

[0067] In the sequence for producing the target material 100 in this embodiment, A process (mixing process) of mixing a powder made of a K compound, a powder made of a Na compound, and a powder made of a Nb compound in a predetermined ratio to obtain a mixture; The mixture is heated while applying a predetermined pressure to the mixture, and the area of ​​the main surface is 44.2 cm 2A process (hot pressing) for obtaining a sintered body having a thickness of 3 mm or more. In the hot press process, the pressure is increased by 1 kgf / cm per minute until the specified pressure is reached. 2 The pressure is gradually increased at the following rate, and the temperature within the plane that will become the main surface of the sintered body to be obtained is maintained at 900 to 1200°C for 12 hours or more.

[0068] In addition, after the mixing process and before the hot pressing process, A process of heating the mixture at a predetermined temperature to calcinate it (calcination process); A process of pulverizing the mixture after the calcination (pulverization process); In this case, the hot pressing treatment is carried out on the mixture that has been pulverized after the preliminary firing.

[0069] After the hot pressing process, the sintered body may be further subjected to a process of heating at a predetermined temperature (heat treatment).

[0070] (Mixing treatment) A powder made of a K compound, a powder made of a Na compound, and a powder made of a Nb compound are mixed in a predetermined ratio to obtain a mixture.

[0071] Specifically, first, a powder consisting of a K compound, a powder consisting of a Na compound, and a powder consisting of a Nb compound are prepared. Note that the term "powder consisting of a K compound" here refers to a powder whose main component is a K compound, and may be composed solely of a K compound powder or may contain powders of other compounds in addition to the powder of the K compound that is the main component. Similarly, the term "powder consisting of a Na compound" refers to a powder whose main component is a Na compound, and may be composed solely of a Na compound powder or may contain powders of other compounds in addition to the powder of the Na compound that is the main component. The term "powder consisting of a Nb compound" refers to a powder whose main component is a Nb compound, and may be composed solely of a Nb compound powder or may contain powders of other compounds in addition to the powder of the Nb compound that is the main component.

[0072] The K compound is at least one selected from the group consisting of K oxides, K composite oxides, and K compounds that become oxides upon heating (e.g., carbonates, oxalates). For example, potassium carbonate (K2CO3) powder can be used as the powder of a K compound.

[0073] The Na compound is at least one selected from the group consisting of Na oxides, Na composite oxides, and Na compounds that become oxides upon heating (e.g., carbonates, oxalates). As the powder consisting of a Na compound, for example, sodium carbonate (Na2CO3) powder can be used.

[0074] The Nb compound is at least one selected from the group consisting of Nb oxide, Nb composite oxide, and Nb compound that becomes an oxide by heating. As the powder consisting of the Nb compound, for example, niobium oxide (Nb2O5) powder can be used.

[0075] Furthermore, when preparing a target material 100 containing a predetermined dopant, at least one of a powder of a compound of at least one element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga, and a powder of at least one element selected from the group consisting of the above elements, is prepared. The powder of the compound of each element is at least one selected from the group consisting of an oxide powder of each element, a composite oxide powder of each element, and a powder of a compound of each element (e.g., carbonate, oxalate) that becomes an oxide upon heating.

[0076] Then, the mixing ratio of each powder is adjusted so that the target material 100 has a predetermined composition, and each powder (raw material powder) is weighed. The weighing may be performed in the air, but is preferably performed in an inert gas atmosphere such as Ar gas or nitrogen (N2) gas in order to avoid deviations in the composition ratio of the target material 100. Furthermore, in order to reliably avoid deviations in the composition ratio of the target material 100, it is preferable to weigh each powder after sufficiently drying (dehydrating).

[0077] Next, the powders are mixed (wet mixed) using a mixer such as a ball mill, a bead mill, etc. The mixing conditions are exemplified by the following conditions. Solvent: organic solvent such as ethanol or water Mixing time: 5 to 30 hours, preferably 10 to 26 hours Mixed atmosphere: Air

[0078] By performing the mixing under the above conditions, it is possible to prevent the powder from agglomerating, and it becomes easier to make the composition of the target material 100 uniform across the entire sputtering surface and across the entire thickness direction.

[0079] (Pre-calcination and crushing) After the mixing process is completed, the mixture obtained by the mixing process is heated at a predetermined temperature and calcined (calcination process).

[0080] The conditions for carrying out the calcination are exemplified as follows. Heating temperature: 650 to 1100°C, preferably 700 to 900°C, more preferably 700°C or higher and lower than 800°C Heating time: 1 to 50 hours, preferably 5 to 40 hours, more preferably 10 to 35 hours

[0081] After the pre-baking treatment is completed, the pre-baked mixture is mixed while being pulverized using a ball mill or the like (pulverization treatment).

[0082] The conditions for pulverization are exemplified as follows. Grinding (mixing) time: 3 to 10 hours, preferably 5 to 9 hours Other conditions can be the same as those in the above-mentioned mixing process.

[0083] By carrying out the pre-baking and pulverization under the above conditions, the composition of the target material 100 can be made more uniform over the entire sputtering surface.

[0084] (Filling process) After the pre-firing and pulverization processes are completed, the mixture (raw material powder) obtained by pulverization and mixing after pre-firing is filled (contained) in a predetermined jig 208 (see FIG. 7). At this time, the raw material powder is filled into the jig 208 so as to minimize uneven filling of the raw material powder. The jig 208 is made of a material such as graphite, and has a main surface area of ​​44.2 cm. 2 As described above, the jig 208 is configured to be able to form a sintered body (molded body) having a thickness of 3 mm or more. The jig 208 is configured so that it can be placed in a processing chamber 201 provided in a hot press device 200 described below, and so that it will not be damaged by pressure applied by a pressing means 217. Note that the "area of ​​the main surface" here means the area of ​​the main surface of the sintered body when viewed from above in the vertical direction.

[0085] (hot press processing) After the filling process is completed, a hot press process (hot press sintering) is performed using, for example, a hot press device 200 shown in Fig. 7. That is, a predetermined pressure is applied to the mixture 210 filled in the jig 208 to compress it, while the mixture 210 in the jig 208 is heated at a predetermined temperature to obtain a sintered body.

[0086] The hot press apparatus 200 shown in FIG. 7 includes a processing vessel 203 made of stainless steel or the like, and configured with a processing chamber 201 therein. The processing chamber 201 is provided with a pressing means 217 (e.g., a hydraulic press-type pressing means 217) configured to apply a predetermined pressure to a mixture 210 filled in a jig 208. The processing chamber 201 is also provided with a heater 207 that heats the mixture 210 in the jig 208 to a predetermined temperature. The heater 207 is disposed so as to concentrically surround the jig 208. The processing chamber 201 is also provided with a temperature sensor 209 that measures the temperature inside the processing chamber 201. Each component included in the hot press apparatus 200 is connected to a controller 280 configured as a computer, and procedures and conditions described below are controlled by a program executed on the controller 280.

[0087] An example of hot pressing performed using the above-described hot pressing device 200 will be described with reference to Fig. 8(a). In the hot pressing, the following four steps, that is, steps A to D, are performed.

[0088] [Step A] First, the jig 208 filled with the mixture 210 is placed in the processing chamber 201 and placed at a predetermined position on the pressing means 217. Then, the processing chamber 201 is filled with an inert gas atmosphere or a vacuum atmosphere, and the pressing means 217 starts to apply pressure to the mixture 210 in the jig 208. At this time, pressure is applied in a direction perpendicular to the pressing surface, as shown by the white arrow in FIG. 8(a).

[0089] In this step, the pressure applied to the mixture 210 is increased, for example, to 1 kgf / cm per minute until the pressure reaches the pressing pressure in step C described below. 2 Gradually increase the pressure at the following rate: 1 kgf / cm 2 ·Must be less than min.

[0090] [Step B] When the pressure applied to the mixture 210 reaches a predetermined pressing pressure, the application of the predetermined pressing pressure is maintained while starting to heat the mixture 210. In this step, the mixture 210 is heated until the temperature of the mixture 210 reaches the sintering temperature (firing temperature) in step C described below.

[0091] [Step C] When the temperature of the mixture 210 reaches the sintering temperature, a predetermined pressure is applied to the mixture 210 while the temperature in the plane that will become the main surface of the sintered body is kept at the predetermined sintering temperature for a predetermined time, thereby performing hot press sintering. Specifically, a pressure of 80 to 500 kgf / cm is applied to the mixture 210. 2 While applying this pressure, the temperature within the surface that will become the main surface of the sintered body is maintained at 900 to 1200°C over the entire surface, and this state is maintained for 12 hours or more, preferably 24 hours or more. This results in a desired KNN sintered body. At this time, the temperature of the heater 207 is controlled based on the temperature detected by the temperature sensor 209 so that the temperature within the surface that will become the main surface of the sintered body is uniform (uniform within the surface), that is, so that unevenness in the sintering temperature within the surface that will become the main surface of the sintered body is minimized. In this step, the surface that will become the upper surface when the jig 208 is placed on the pressing means 217 is the surface that will become the main surface of the sintered body, and the temperature of the heater 207 is controlled so that the temperature within this surface is 900 to 1200°C over the entire surface.

[0092] The conditions for this step are exemplified as follows: Sintering temperature: 900 to 1200°C, preferably 1000 to 1150°C Press pressure: 80-500kgf / cm 2 , preferably 100 to 400 kgf / cm 2 Sintering time: 12 hours or more, preferably 24 hours or more Atmosphere: inert gas atmosphere or vacuum atmosphere

[0093] [Step D] The temperature within the surface that will become the main surface of the sintered body is maintained at 900 to 1200°C over the entire surface, and this state is maintained for 12 hours or more, after which pressure is released and cooling (temperature reduction) is initiated for the mixture 210. Then, when the temperature of the obtained sintered body has decreased to a predetermined temperature, the jig 208 (sintered body) is carried out of the processing chamber.

[0094] By carrying out the hot pressing process by carrying out the above-mentioned steps A to D, it is possible to obtain a target material 100 having high Vickers hardness over the entire sputtering surface.

[0095] Specifically, in step A, the pressure is set to, for example, 1 kgf / cm 2 By gradually increasing the temperature at a rate of 1 / 2 min or less and setting the sintering time in step C to be much longer than conventional sintering times, that is, by maintaining the temperature of the main surface of the sintered body at 900 to 1200°C over the entire surface for 12 hours or more, it is possible to strengthen the bonds between particles contained in the sintered body. As a result, even if there are "uneven filling of raw material powder" or "uneven sintering temperature," it is possible to achieve a sintered body with an area of ​​44.2 cm2. 2 As described above, a large target material 100 can be obtained that is 3 mm or more thick and has a Vickers hardness of 150 or more over the entire sputtering surface.

[0096] The pressure increase rate in step A is 1 kgf / cm 2 If the hardness exceeds .times. ...

[0097] The lower the pressure increase rate, i.e., the slower the pressure increase in step A, the more reliably it becomes possible to avoid the appearance of a region in the sputtering surface 101 having a Vickers hardness of less than 150. Therefore, there is no particular restriction on the lower limit of the pressure increase rate. However, if the pressure increase rate is 0.2 kgf / cm 2 If the pressure increase rate is less than 0.2 kgf / cm, productivity may decrease and manufacturing costs may increase. From the viewpoint of ensuring productivity and suppressing cost increases, the pressure increase rate is set to, for example, 0.2 kgf / cm2 ·min or more.

[0098] Furthermore, if the sintering time in step C is less than 12 hours, even if the sintering temperature is set within the above range, a region having a Vickers hardness of less than 150 may appear on sputtered surface 101.

[0099] Since the longer the sintering time, the higher the Vickers hardness can be, the upper limit of the sintering time is not particularly limited. However, if the sintering time exceeds 100 hours, productivity may decrease and manufacturing costs may increase. From the viewpoint of ensuring productivity and suppressing cost increases, the sintering time may be, for example, 100 hours or less, preferably 72 hours or less.

[0100] Furthermore, in step C, if the sintering temperature is less than 900°C, sintering may be insufficient even if the sintering time is 12 hours or more, and regions with a Vickers hardness of less than 150 may appear on the sputtering surface 101. If the sintering temperature exceeds 1200°C, cracks or chips may occur in the sintered body. Furthermore, scattering of K and Na may cause compositional deviations in the target material, and as a result, in a KNN film formed using such a target material, the compositions of K, Na, and Nb may not satisfy the above-mentioned relationship across the entire main surface.

[0101] In addition, the pressure in step C is 80 kgf / cm 2 By setting the pressure to 80 kgf / cm or more, it is possible to reliably obtain a target material 100 having a Vickers hardness of 150 or more over the entire sputtering surface. 2 If the pressure is less than 500 kgf / cm, the compression will be insufficient, and a region having a Vickers hardness of less than 150 may appear in the sputtering surface 101. 2 By keeping the pressure at or below 500 kgf / cm, it is possible to avoid the occurrence of cracks and damage to the jig 208 during the production of the target material 100. 2If it exceeds this value, the sintered body may crack during the production of the target material 100, or the jig 208 may be damaged.

[0102] Furthermore, by carrying out the above steps A to D, it is possible to make the relative density of the target material 100 60% or more, preferably 70% or more, and more preferably 80% or more over the entire sputtering surface.

[0103] (Heat treatment) After the hot pressing process is completed, the sintered body is subjected to a predetermined heat treatment using a heat treatment device. The heat treatment is performed while controlling the temperature of the heater of the heat treatment device so that the temperature within the main surface of the sintered body becomes uniform (uniform within the surface).

[0104] The heat treatment conditions are exemplified as follows: Temperature: 600 to 1100°C, preferably 700 to 1000°C Atmosphere: Air or oxygen (O)-containing atmosphere Time: 1 to 40 hours, preferably 5 to 30 hours

[0105] In hot pressing, when sintering is performed in an inert gas atmosphere or vacuum atmosphere, the KNN sintered body, which is an oxide, may be reduced to some extent, resulting in oxygen deficiency in the sintered body. By performing heat treatment under the above conditions, oxygen can be replenished to replace the oxygen deficiency in the sintered body. As a result, a target material 100 with higher resistance can be obtained. For example, the volume resistivity of the target material 100 can be increased to 1000 kΩcm or more, preferably 1000 kΩcm or more across the entire sputtering surface.

[0106] (Finishing process) After the heat treatment is completed, the outer shape and thickness of the heat-treated sintered body are adjusted as necessary, and the surface is polished to improve the surface condition, thereby obtaining a target material 100 as shown in FIG.

[0107] (6) Effects According to the present disclosure, one or more of the following advantages can be obtained.

[0108] (a) In this embodiment, even if the KNN film 3 has a large diameter (diameter of 3 inches or more), the composition of K, Na, and Nb in the KNN film 3 satisfies the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire main surface. This allows, for example, the dielectric strength voltage of the KNN film 3 to be uniform over the entire main surface. As a result, it is possible to prevent variations in dielectric strength voltage from occurring among multiple piezoelectric elements 20 and piezoelectric device modules 30 obtained from a single piezoelectric laminate 10. This makes it possible to improve the yield and reliability of the piezoelectric elements 20 and piezoelectric device modules 30.

[0109] (b) When the composition of K, Na, and Nb in the KNN film 3 satisfies 0.94≦(K+Na) / Nb≦1.03, the dielectric strength voltage of the KNN film 3 can be, for example, 300 kV / cm or more, preferably 500 kV / cm or more.

[0110] (c) When the compositions of K, Na, and Nb in the KNN film 3 satisfy the above relationship over the entire main surface, the dielectric strength voltage of the KNN film 3 can be set to, for example, 300 kV / cm or more, preferably 500 kV / cm or more over the entire main surface.

[0111] (d) The area of ​​the sputtering surface 101 is 44.2 cm 2 By sputtering the KNN film 3 using the target material 100 having the above-mentioned thickness of 3 mm or more and a Vickers hardness of 150 or more over the entire sputtering surface, it is possible to obtain a large-diameter KNN film 3 in which the composition of K, Na, and Nb satisfies the above relationship over the entire main surface.

[0112] Here, as a method for evaluating the Vickers hardness of the sputtered surface, for example, a method can be considered in which the Vickers hardness is measured at a total of nine points: one point at the center of the sputtered surface, four points at 90° intervals at half the radius, and four points at 90° intervals at a predetermined distance inward from the outer periphery. However, with this evaluation method, since there are fewer evaluation points than in the present embodiment, it may not be possible to accurately evaluate the Vickers hardness over the entire sputtered surface. In particular, when the area of ​​the sputtered surface is 44.2 cm 2 In the case of a target material having the above thickness of 3 mm or more, even if a region having a Vickers hardness of less than 150 appears, that region may not be found.

[0113] In contrast, in the target material 100 according to this embodiment, the Vickers hardness was measured at 1 cm intervals in a grid pattern in the area excluding the peripheral portion, which is a region 5 mm from the edge of the sputtering surface 101. 2 The sputtered surface 101 has a Vickers hardness of 150 or more (37 points for the sputtered surface 101 having an area of ​​44.2 cm2). 2 By sputtering a KNN film 3 on a large-diameter substrate 1 using a target material 100 that is 3 mm or more thick and has a high Vickers hardness over the entire sputtering surface, a large-diameter KNN film 3 can be obtained in which the compositions of K, Na, and Nb satisfy the above-mentioned relationship over the entire main surface.

[0114] (e) In the above step A, the pressure is set to, for example, 1 kgf / cm 2 The temperature is gradually increased at a rate of 1 / min or less, and in step C, the temperature in the plane that will become the main surface of the sintered body is kept at 900 to 1200°C for 12 hours or more, thereby strengthening the interparticle bonds in the KNN sintered body. Therefore, even if there are "uneven filling of raw material powder" or "uneven sintering temperature," the area of ​​the sputtering surface 101 can be increased to 44.2 cm. 2 In addition, a target material 100 having a thickness of 3 mm or more and a Vickers hardness of 150 or more over the entire sputtering surface can be obtained.

[0115] (f) By using a target material 100 having a Vickers hardness of 150 or more over the entire sputtering surface, it is possible to prevent cracks from occurring on the sputtering surface 101 even when the KNN film 3 is deposited by sputtering at a high rate. This extends the life of the target material 100 and reduces the frequency of maintenance of the sputtering device (deposition device). As a result, it is possible to reduce the manufacturing cost of the piezoelectric stack 10.

[0116] (7) Variations This aspect can be modified as follows. In the following description of the modifications, the same components as those in the above aspect are denoted by the same reference numerals, and the description thereof will be omitted. The above aspect and the following modifications can be combined in any way.

[0117] (Variation 1) The piezoelectric stack 10 does not necessarily have to include the lower electrode film 2. That is, the piezoelectric stack 10 may be configured to include a large-diameter substrate 1, a large-diameter KNN film 3 deposited on the substrate 1, and an upper electrode film 4 (electrode film) deposited on the KNN film 3.

[0118] FIG. 9 shows a schematic diagram of a piezoelectric device module 30 fabricated using the piezoelectric laminate 10 according to this modification. The piezoelectric device module 30 is configured to include at least a piezoelectric element 20 obtained by shaping the piezoelectric laminate 10 into a predetermined shape, and a voltage application unit 11a and a voltage detection unit 11b connected to the piezoelectric element 20. In this modification, the piezoelectric element 20 has pattern electrodes formed by shaping an electrode film into a predetermined pattern. For example, the piezoelectric element 20 has a pair of positive and negative pattern electrodes 4p1 on the input side and a pair of positive and negative pattern electrodes 4p2 on the output side. An example of the pattern electrodes 4p1 and 4p2 is an interdigital transducer (IDT).

[0119] By connecting the voltage application means 11a between the pattern electrodes 4p1 and the voltage detection means 11b between the pattern electrodes 4p2, the piezoelectric device module 30 can function as a filter device such as a surface acoustic wave (SAW) filter. By applying a voltage between the pattern electrodes 4p1 using the voltage application means 11a, a SAW can be excited in the KNN film 3. The frequency of the excited SAW can be adjusted, for example, by adjusting the pitch of the pattern electrode 4p1. For example, the shorter the pitch of the IDT serving as the pattern electrode 4p1, the higher the SAW frequency, and the longer the pitch, the lower the SAW frequency. Of the SAWs excited by the voltage application means 11a, propagating through the KNN film 3 and reaching the pattern electrode 4p2, a SAW with a predetermined frequency (frequency component) determined by the pitch of the IDT serving as the pattern electrode 4p2 generates a voltage between the pattern electrodes 4p2. By detecting this voltage with the voltage detection means 11b, it is possible to extract a SAW having a predetermined frequency from the excited SAWs. Note that the term "predetermined frequency" here can include not only a predetermined frequency but also a predetermined frequency band whose center frequency is a predetermined frequency.

[0120] In this modified example, a large target material 100 having a Vickers hardness of 150 or more over the entire sputtering surface is used to sputter the KNN film 3, thereby obtaining a large-diameter KNN film 3 whose composition of K, Na, and Nb satisfies the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire main surface.

[0121] (Variation 2) The piezoelectric stack 10 does not necessarily have to include the upper electrode film 4. That is, the piezoelectric stack 10 may be configured to include a large-diameter substrate 1, a lower electrode film 2 deposited on the substrate 1, and a large-diameter KNN film 3 deposited on the lower electrode film 2. In this modification, the KNN film 3 is deposited by sputtering using a large target material 100 having a Vickers hardness of 150 or more over the entire sputtering surface, thereby obtaining a large-diameter KNN film 3 in which the composition of K, Na, and Nb satisfies the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire main surface.

[0122] (Variation 3) In the above-described embodiment, the mixing process for producing the target material 100 is described as an example in which a powder made of a K compound (e.g., K2CO3 powder), a powder made of a Na compound (e.g., Na2CO3 powder), and a powder made of a Nb compound (e.g., Nb2O5 powder) are mixed in a predetermined ratio, but this is not limiting.

[0123] For example, in the mixing process, a powder of a compound containing K and Nb and a powder of a compound containing Na and Nb may be mixed in a predetermined ratio to obtain a mixture. Note that the term "powder of a compound containing K and Nb" as used herein refers to a powder whose main component is a compound of K and Nb. This may include powders consisting solely of a compound containing K and Nb, or may contain powders of other compounds in addition to the powder of the compound containing K and Nb as the main component. Similarly, the term "powder of a compound containing Na and Nb" refers to a powder whose main component is a compound containing Na and Nb. This may include powders consisting solely of a compound containing Na and Nb, or may contain powders of other compounds in addition to the powder of the compound containing Na and Nb as the main component.

[0124] The compound containing K and Nb is at least one selected from the group consisting of oxides (composite oxides) containing K and Nb, and compounds containing K and Nb that become oxides upon heating (e.g., carbonates, oxalates). For example, KNbO3 powder can be used as the powder of the compound containing K and Nb. KNbO3 powder can be obtained by, for example, mixing a K compound (e.g., K2CO3 powder) and a Nb compound (e.g., Nb2O5 powder), calcining the mixture, and then pulverizing and mixing the calcined mixture using a ball mill or the like.

[0125] The compound containing Na and Nb is at least one selected from the group consisting of oxides containing Na and Nb (composite oxides) and compounds containing Na and Nb that become oxides upon heating (e.g., carbonates, oxalates). For example, NaNbO3 powder can be used as the powder of the compound containing Na and Nb. NaNbO3 powder can be obtained by, for example, mixing a compound of Na (e.g., Na2CO3 powder) and a compound of Nb (e.g., Nb2O5 powder), calcining the mixture, and then pulverizing and mixing the calcined mixture using a ball mill or the like.

[0126] In this case, the composition of the target material 100 can be controlled by adjusting the mixing ratio of KNbO3 powder and NaNbO3 powder, the mixing ratio of K compounds and Nb compounds when producing KNbO3 powder, and the mixing ratio of Na compounds and Nb compounds when producing NaNbO3 powder.

[0127] In this modification, the calcination conditions for producing the KNbO3 powder and the NaNbO3 powder can be the same as the calcination conditions for the above-described embodiment, and the mixing conditions can be the same as the mixing conditions for the above-described embodiment.

[0128] In this modification, the same effect as in the above embodiment can be obtained by performing the hot pressing process. Specifically, in step A, the pressure is set to, for example, 1 kgf / cm 2In step C, the temperature in the plane that will become the main surface of the sintered body is kept at 900 to 1200°C for 12 hours or more. This allows the area of ​​the sputtering surface 101 to be increased to 44.2 cm2 even if there are "uneven filling of the raw material powder" or "uneven sintering temperature." 2 As described above, it is possible to obtain a large target material 100 having a thickness of 3 mm or more and a Vickers hardness of 150 or more over the entire sputtering surface. Furthermore, by sputtering the KNN film 3 using the target material 100 of this modification, it is possible to obtain a large-diameter KNN film 3 in which the composition of K, Na, and Nb satisfies the above relationship over the entire main surface.

[0129] (Variation 4) In the above embodiment, an example has been described in which step B is started after step A is completed. That is, an example has been described in which heating of the mixture 210 is started after the pressure in step A reaches the pressing pressure. However, the present disclosure is not limited to the above embodiment. For example, as shown in FIG. 8(b), the above-mentioned steps A and B may overlap in part. That is, step B (heating) may be started while step A is being performed (while the pressure is being increased). Furthermore, as shown in FIG. 8(c), the period of step A and the period of step B may be the same. Even in these cases, in step A, for example, 1 kgf / cm 2 By gradually increasing the pressure at a rate of 0.1 MPa or less and, in step C, maintaining the temperature within the plane that will become the main surface of the sintered compact at 900 to 1200°C for 12 hours or more, the same effects as those of the above-mentioned aspects and modifications can be obtained.

[0130] (Variation 5) In the above-described embodiments and modifications, examples have been described in which the powders are mixed by wet mixing in the mixing process or pulverization process, but this is not limiting. The mixing process may also be by dry mixing. That is, the powders may be mixed using a mixer such as an attritor.

[0131] (Variation 6) In the above embodiment, the example in which the pre-baking treatment, the crushing treatment, and the heat treatment are performed has been described, but the present invention is not limited to this. These treatments may be performed as needed. That is, when the area of ​​the sputtering surface 101 is 44.2 cm 2 As long as it is possible to obtain a large target material 100 having a thickness of 3 mm or more and a Vickers hardness of 150 or more over the entire sputtering surface, these treatments may not be carried out.

[0132] (Variation 7) For example, the heating in each of the pre-baking treatment and the heat treatment may be performed in multiple steps. 2 As a result, a large-sized target material 100 having a thickness of 3 mm or more and a Vickers hardness of 150 or more over the entire sputtering surface can be obtained.

[0133] (Variation 8) For example, an orientation control layer for controlling the orientation of the crystals constituting the KNN film 3 may be provided between the lower electrode film 2 and the KNN film 3, i.e., directly below the KNN film 3. If the lower electrode film 2 is not provided, an orientation control layer may be provided between the substrate 1 and the KNN film 3. The orientation control layer may be formed using a metal oxide such as SRO, LNO, or strontium titanate (SrTiO3, abbreviated as STO), which is different from the material constituting the lower electrode film 2. The crystals constituting the orientation control layer preferably have a (100) preferential orientation with respect to the main surface of the substrate 1. This ensures that the orientation rate of the KNN film 3 is, for example, 80% or more, preferably 90% or more. [Example]

[0134] The following describes experimental results that support the effects of the above-described embodiment.

[0135] After mixing, calcining, crushing, filling, hot pressing, and heat treatment were performed to obtain a sintered body, which was then subjected to a finishing process to reduce the area to 44.2 cm. 2Target materials (samples 1 to 15) each having a circular sputtering surface and a thickness of 5 mm were fabricated.

[0136] In Sample 1, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the value of (K+Na) / Nb was 0.95 in the mixing process. In addition, in step A of the above-mentioned hot pressing process, the pressing pressure was 80 kgf / cm 2 until it reaches 1kgf / cm 2 The pressure was gradually increased at a rate of 0.1 sq. min. In step C of the above-described embodiment of the hot pressing, the temperature within the main surface of the sintered compact was maintained at 900°C over the entire surface for 12 hours. That is, in step C, the sintering temperature was 900°C and the sintering time was 12 hours. The other conditions were set to the predetermined conditions within the ranges described in the above-described embodiment.

[0137] For Sample 2, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 1000°C and the sintering time was set to 12 hours. The manufacturing procedure and other manufacturing conditions were the same as for Sample 1.

[0138] For Sample 3, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.20 during the mixing process. In addition, in Step C, the sintering temperature was set to 1200°C and the sintering time was set to 12 hours. The manufacturing procedure and other manufacturing conditions were the same as for Sample 1.

[0139] In Sample 4, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the value of (K+Na) / Nb was 1.07 in the mixing process. The pressure increase rate in Step A was set to 0.5 kgf / cm 2 In step C, the sintering temperature was 950°C and the sintering time was 12 hours. The manufacturing procedure and other manufacturing conditions were the same as those for sample 1.

[0140] In Sample 5, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the value of (K+Na) / Nb was 1.07 in the mixing process. The pressure increase rate in Step A was set to 0.2 kgf / cm 2 In step C, the sintering temperature was 950°C and the sintering time was 12 hours. The manufacturing procedure and other manufacturing conditions were the same as those for sample 1.

[0141] For Sample 6, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 950°C and the sintering time was set to 24 hours. The manufacturing procedure and other manufacturing conditions were the same as those for Sample 1.

[0142] For Sample 7, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 950°C and the sintering time was set to 48 hours. The manufacturing procedure and other manufacturing conditions were the same as those for Sample 1.

[0143] For Sample 8, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 850°C and the sintering time was set to 12 hours. The manufacturing procedure and other manufacturing conditions were the same as those for Sample 1.

[0144] For Sample 9, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 800°C and the sintering time was set to 12 hours. The manufacturing procedure and other manufacturing conditions were the same as those for Sample 1.

[0145] For Sample 10, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 1250°C and the sintering time was set to 12 hours. The manufacturing procedure and other manufacturing conditions were the same as those for Sample 1.

[0146] For Sample 11, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 1300°C and the sintering time was set to 12 hours. The manufacturing procedure and other manufacturing conditions were the same as those for Sample 1.

[0147] For Sample 12, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 950°C and the sintering time was set to 6 hours. The manufacturing procedure and other manufacturing conditions were the same as those for Sample 1.

[0148] For Sample 13, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the (K+Na) / Nb value was 1.07 during the mixing process. In addition, in Step C, the sintering temperature was set to 950°C and the sintering time was set to 3 hours. The manufacturing procedure and other manufacturing conditions were the same as those for Sample 1.

[0149] In Sample 14, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the value of (K+Na) / Nb was 1.07 in the mixing process. In addition, the pressure increase rate in Step A was set to 2 kgf / cm 2 In step C, the sintering temperature was 950°C and the sintering time was 12 hours. The manufacturing procedure and other manufacturing conditions were the same as those for sample 1.

[0150] In Sample 15, the mixing ratio of K2CO3 powder, Na2CO3 powder, and Nb2O5 powder was adjusted so that the value of (K+Na) / Nb was 1.07 in the mixing process. The pressure increase rate in Step A was set to 4 kgf / cm 2 In step C, the sintering temperature was 950°C and the sintering time was 12 hours. The manufacturing procedure and other manufacturing conditions were the same as those for sample 1.

[0151] <Evaluation> The target materials of Samples 1 to 15 were evaluated for cracking and Vickers hardness. In addition, the KNN film formed by sputtering using each sample was evaluated, and the occurrence of cracks in each sample after sputtering was evaluated.

[0152] (Crack evaluation) Each sample was visually evaluated for the presence or absence of cracks or chips. As a result, it was confirmed that chips had occurred in samples 10 and 11. No cracks or chips were found in any samples other than samples 10 and 11. This indicates that cracks and chips will occur in the sintered body if the temperature (sintering temperature) in step C exceeds 1200°C.

[0153] (Vickers hardness evaluation) For each sample except for samples 10 and 11, which had chipping, the Vickers hardness of the sputtered surface was measured. The Vickers hardness was measured in a grid pattern at 1 cm intervals in the area excluding a 5 mm area from the edge of the sputtered surface. 2 For Samples 1 to 9 and 12 to 15, each of which had a circular sputtered surface and a thickness of 3 mm, Vickers hardness was measured at 37 points. Vickers hardness was measured using a micro Vickers hardness tester HM-114 manufactured by Mitutoyo Corporation, in accordance with JIS R1610, by making an indentation on the test surface (sputtered surface) under the test conditions described in the above embodiment. The measurement results are shown in Table 1 below. In Table 1, "passing measurement points" refers to the number of measurement points where the Vickers hardness was 150 or more, and "failing measurement points" refers to the number of measurement points where the Vickers hardness was less than 150.

[0154] [Table 1]

[0155] As shown in Table 1, the pressure increase rate in step A is set to 1 kgf / cm 2 In Samples 1 to 7, in which the sintering temperature was kept at 900 to 1200°C for 12 hours or more in Step C, the area of ​​the sputtered surface was 44.2 cm 2 As described above, it was confirmed that even if the thickness is 3 mm or more, the Vickers hardness can be made to be 150 or more over the entire sputtered surface.

[0156] In contrast, Samples 8 and 9, in which the sintering temperature in Step C was less than 900°C, Samples 12 and 13, in which the sintering time was less than 12 hours, and Samples 14 and 15, in which the pressure increase rate in Step A was 1 kgf / cm 2 In Samples 14 and 15, where the hardness exceeded 1.5 min, it was confirmed that areas (locations) with a Vickers hardness of less than 150 appeared on the sputtered surface.

[0157] (Evaluation of KNN membrane) Using each sample except for Samples 10 and 11 in which cracks had occurred, a KNN film was formed by sputtering according to the following procedure.

[0158] A 4-inch diameter, 510 μm thick Si substrate with a (100) surface orientation and a 200 nm thick thermal oxide film (SiO2 film) formed on the surface was prepared as the substrate. Then, a 2 nm thick Ti layer was deposited as an adhesion layer on this substrate (on the thermal oxide film) by RF magnetron sputtering, and a 200 nm thick Pt film (oriented in the (111) plane with respect to the main surface of the substrate) was deposited as a lower electrode film. Using each of Samples 1 to 9 and 12 to 15 as the target material, a 2 μm thick KNN film with a 3-inch diameter was deposited on the lower electrode film by RF magnetron sputtering.

[0159] The conditions for forming the Ti layer were as follows: Temperature (substrate temperature): 300℃ Discharge power density: 14.8W / cm 2 (1200W / 4 inch diameter circular) Atmosphere: Ar gas atmosphere Ambient pressure: 0.3 Pa Film deposition speed: A 2.5 nm thick Ti layer is deposited in 30 seconds.

[0160] The conditions for forming the Pt film were as follows: Temperature (substrate temperature): 300℃ Discharge power density: 14.8W / cm 2 (1200W / 4 inch diameter circular) Atmosphere: Ar gas atmosphere Ambient pressure: 0.3 Pa Time: 5 minutes

[0161] The conditions for forming the KNN film were as follows: Discharge power density: 3.0W / cm 2 (2200W / 12 inch diameter circular) Atmosphere: Ar gas + O2 gas mixed gas atmosphere Ambient pressure: 0.3 Pa Ar / O2 partial pressure ratio: 25 / 1 Temperature (substrate temperature): 600℃ Film forming speed: 1μm / hr

[0162] Then, the composition analysis of K, Na, and Nb was performed on each of the obtained KNN films. Specifically, first, the area of ​​the main surface of the KNN film, excluding the peripheral area 5 mm from the edge, was cut into a grid at intervals of 1 cm to obtain a plurality of small pieces. Of the obtained small pieces, those with a planar area of ​​25 mm 2The above small pieces (in this example, 32 small pieces per KNN film) were each thermally decomposed with sulfuric acid, nitric acid, hydrofluoric acid, and hydrochloric acid, and then heated and dissolved in dilute hydrogen peroxide and dilute hydrofluoric acid to a constant volume. AAS was performed on this solution using a Z-2300 manufactured by Hitachi High-Technologies Corporation to measure the K and Na contents in the KNN film, and ICP-AES was performed using a PS3520VDDII manufactured by Hitachi High-Tech Science Corporation to measure the Nb content in the KNN film. The obtained K, Na, and Nb contents were then converted to atomic ratios, and the composition of K, Na, and Nb in the KNN film, i.e., the (K + Na) / Nb value, was calculated from these atomic ratios.

[0163] The results of the composition analysis of K, Na, and Nb in the KNN membrane are shown in Table 1. The "number of pass" in Table 1 refers to the number of small pieces whose K, Na, and Nb compositions in the KNN membrane satisfy the relationship 0.94≦(K+Na) / Nb≦1.03, and the "number of fail" refers to the number of small pieces whose K, Na, and Nb compositions in the KNN membrane do not satisfy the relationship 0.94≦(K+Na) / Nb≦1.03, i.e., the number of small pieces whose (K+Na) / Nb value is less than 0.94 ((K+Na) / Nb<0.94) and whose (K+Na) / Nb value is greater than 1.03 (1.03<(K+Na) / Nb). The numbers in parentheses in the "number of fail" column refer to the (K+Na) / Nb values ​​of the failed small pieces.

[0164] As shown in Table 1 above, in the large-diameter KNN films with a diameter of 3 inches formed using samples 1 to 7, which had a Vickers hardness of 150 or more across the entire sputtered surface, it was confirmed that the compositions of K, Na, and Nb in the KNN films all satisfied the relationship 0.94≦(K+Na) / Nb≦1.03 across the entire main surface.

[0165] In contrast, in the KNN films deposited using Samples 8, 9, and 12 to 15, in which regions with a Vickers hardness of less than 150 appeared on the sputtered surface, it was confirmed that there were portions on the main surface of the KNN film where the compositions of K, Na, and Nb did not satisfy the relationship of 0.94≦(K+Na) / Nb≦1.03. That is, it was confirmed that in the KNN films deposited using Samples 8, 9, and 12 to 15, there were portions on the main surface of the KNN film where the value of (K+Na) / Nb was less than 0.94 or where the value of (K+Na) / Nb was more than 1.03.

[0166] (Evaluation of crack occurrence in each sample after sputtering film formation) After the KNN film was formed by sputtering, Samples 1 to 9 and 12 to 15 were visually inspected for the presence or absence of cracks on the sputtered surface.

[0167] As a result, it was confirmed that in Samples 1 to 7, which had a Vickers hardness of 150 or more across the entire sputtered surface, no cracks occurred on the sputtered surface even after sputtering. In other words, it was confirmed that in Samples 1 to 7, there were no areas with weak interparticle bonds across the entire sputtered surface, and it was possible to avoid the occurrence of cracks and abnormal discharge during pre-sputtering and sputtering.

[0168] In contrast, in Samples 8, 9, and 12 to 15, in which regions with a Vickers hardness of less than 150 appeared on the sputtered surface, it was confirmed that cracks had occurred on the sputtered surface after the sputtering film was formed.

[0169] <Preferred aspects of the present disclosure> Preferred aspects of the present disclosure will be described below.

[0170] (Appendix 1) According to one aspect of the present disclosure, a substrate having a main surface with a diameter of 3 inches or more; a piezoelectric film formed on the substrate and made of an alkali niobium oxide containing K, Na, Nb, and O; A piezoelectric laminate is provided in which the compositions of K, Na, and Nb in the piezoelectric film satisfy the relationship of 0.94≦(K+Na) / Nb≦1.03, preferably 0.96≦(K+Na) / Nb≦1.00, over the entire inner area of ​​the main surface of the piezoelectric film except for the peripheral edge portion.

[0171] (Appendix 2) The piezoelectric laminate according to Supplementary Note 1, preferably The thickness of the piezoelectric film is 0.5 μm or more over the entire inner area of ​​the main surface of the piezoelectric film excluding the peripheral edge portion.

[0172] (Appendix 3) The piezoelectric laminate according to Supplementary Note 1 or 2, preferably The alkali oxide further contains, as a dopant, at least one element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga.

[0173] (Appendix 4) The piezoelectric laminate according to any one of Supplementary Notes 1 to 3, preferably The dielectric strength of the piezoelectric film is 300 kV / cm or more, preferably 500 kV / cm or more, over the entire inner area of ​​the main surface of the piezoelectric film excluding the peripheral edge portion. That is, when a predetermined electric field is applied in the thickness direction of the piezoelectric film, the current density of the piezoelectric film is 100 μA / cm 2 The electric field value at which this is achieved is 300 kV / cm or more, preferably 500 kV / cm or more, over the entire inner area of ​​the main surface of the piezoelectric film excluding the peripheral edge portion.

[0174] (Appendix 5) The laminate according to any one of Supplementary Notes 1 to 4, preferably A lower electrode film is formed between the substrate and the piezoelectric film.

[0175] (Appendix 6) The laminate according to any one of Supplementary Notes 1 to 5, preferably An upper electrode film is formed on the piezoelectric film.

[0176] (Appendix 7) According to another aspect of the present disclosure, A step of preparing a sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O; providing a substrate having a major surface with a diameter of 3 inches or more; and forming, on the substrate using the sputtering target material, a piezoelectric film formed from an alkali niobium oxide containing K, Na, Nb, and O, wherein the compositions of K, Na, and Nb satisfy the relationship of 0.94≦(K+Na) / Nb≦1.03 over the entire inner area of ​​the main surface excluding the peripheral edge portion. A method for manufacturing a piezoelectric stack is provided.

[0177] (Appendix 8) According to yet another aspect of the present disclosure, providing a substrate having a major surface with a diameter of 3 inches or more; preparing a sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O, the sputtering target material having a minimum Vickers hardness of 150 or more on a surface (sputtering surface) exposed to plasma when forming a piezoelectric film by a sputtering method; The discharge power density applied to the sputtering target material is 2.7 to 4.1 W / cm 2 and forming the piezoelectric film made of alkali niobium oxide containing K, Na, Nb, and O under conditions of a temperature of 500 to 700°C, an atmosphere containing at least oxygen gas, a pressure of 0.1 Pa or more and 0.8 Pa or less, and a film formation rate of 0.5 μm / hr or more. A method for manufacturing a piezoelectric stack is provided.

[0178] (Appendix 9) According to yet another aspect of the present disclosure, The method includes a step of depositing a piezoelectric film made of an alkali niobium oxide containing K, Na, Nb, and O on a substrate by a sputtering method using a sputtering target material made of a sintered body containing an oxide containing K, Na, Nb, and O; In the step of forming the piezoelectric film, The sputtering target material is R1 is the average value of (K+Na) / Nb, which represents the composition of K, Na, and Nb within the surface exposed to plasma when depositing the piezoelectric film; When the average value of (K+Na) / Nb representing the composition of K, Na, and Nb in the main surface of the piezoelectric film formed on the substrate is R2, A method for manufacturing a piezoelectric laminate is provided that uses a sputtering target material that satisfies the relationship R1>R2.

[0179] (Appendix 10) According to yet another aspect of the present disclosure, A sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O, Temperature: 500 to 700°C, discharge power density: 2.7 to 4.1 W / cm 2 When used as a target material for depositing a piezoelectric film on a substrate having a main surface with a diameter of 3 inches or more by a sputtering method under the conditions of an atmosphere containing at least oxygen gas, an atmospheric pressure of 0.2 to 0.5 Pa, an argon gas partial pressure / oxygen gas partial pressure = 30 / 1 to 20 / 1, and a deposition rate of 0.5 to 2 μm / hr, On the substrate, the piezoelectric film is formed from an alkali niobium oxide containing K, Na, Nb, and O, and the compositions of K, Na, and Nb satisfy the relationship of 0.94≦(K+Na) / Nb≦1.03 over the entire inner area of ​​the main surface except for the peripheral portion. A sputtering target material is provided.

[0180] (Appendix 11) According to yet another aspect of the present disclosure, A sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O, When depositing a piezoelectric film using the sputtering method, the surface area exposed to plasma is 44.2 cm 2 and the thickness is 3mm or more, There is provided a sputtering target material in which the Vickers hardness of the surface exposed to the plasma is 150 or more, preferably 200 or more, over the entire inner area of ​​the surface exposed to the plasma excluding the peripheral edge.

[0181] (Appendix 12) According to yet another aspect of the present disclosure, A sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O, Temperature: 500 to 700°C, discharge power density: 2.7 to 4.1 W / cm 2 When used as a sputtering target material for depositing a piezoelectric film on a substrate having a main surface with a diameter of 3 inches or more by a sputtering method under the conditions of an atmosphere containing at least oxygen gas, an atmospheric pressure of 0.2 to 0.5 Pa, an argon gas partial pressure / oxygen gas partial pressure = 30 / 1 to 20 / 1, and a deposition rate of 0.5 to 2 μm / hr, The sputtering target material is provided such that, in any of the plurality of piezoelectric films formed using one sputtering target material, the composition of K, Na, and Nb in the piezoelectric film satisfies the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire inner area of ​​the main surface of the piezoelectric film except for the peripheral edge portion.

[0182] (Appendix 13) The sputtering target material according to any one of Supplementary Notes 10 to 12, preferably The dopant further contains at least one element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga.

[0183] (Appendix 14) The sputtering target material according to any one of Supplementary Notes 10 to 13, preferably The relative density is 60% or more over the entire surface exposed to plasma when forming the piezoelectric film. Note that the relative density (%) here is the ratio of (measured density) to KNN theoretical density (4.51 g / cm3). 3 )) × 100.

[0184] (Appendix 15) The target material according to any one of Supplementary Notes 10 to 14, preferably The volume resistivity is 1000 kΩcm or more over the entire surface that is exposed to plasma when the piezoelectric film is formed.

[0185] (Appendix 16) According to yet another aspect of the present disclosure, It is made of a sintered body containing an oxide containing K, Na, Nb, and O, and the area of ​​the surface exposed to plasma is 44.2 cm 2 A method for manufacturing a target material having a thickness of 3 mm or more, (a) a step of mixing a powder consisting of a K compound, a powder consisting of a Na compound, and a powder consisting of a Nb compound in a predetermined ratio, or a step of mixing a powder consisting of a compound containing K and Nb with a powder consisting of a compound containing Na and Nb in a predetermined ratio to obtain a mixture; (b) applying a predetermined pressure to the mixture while heating the mixture to form a mold having a main surface area of ​​44.2 cm 2 and a step of obtaining a sintered body having a thickness of 3 mm or more. In (b), the pressure is increased by 1 kgf / cm per minute until the specified pressure is reached. 2 The method for producing a sputtering target material includes gradually increasing the pressure at the following rate, and maintaining the temperature in the plane that will become the main surface of the sintered body at 900 to 1200°C for 12 hours or more.

[0186] (Appendix 17) The method according to claim 16, preferably After performing (a) and before performing (b), (c) heating the mixture at a predetermined temperature to calcinate it; (d) pulverizing the mixture after calcination; In (b), the mixture pulverized in (d) is heated while being subjected to a predetermined pressure to obtain the sintered body.

[0187] (Appendix 18) The method according to claim 16 or 17, preferably comprising: After (b), (e) A step of heating the sintered body at a predetermined temperature is further carried out. [Explanation of symbols]

[0188] 1 board 3 Piezoelectric film (KNN film) 10 Piezoelectric laminate 100 target material 101 Sputter surface

Claims

1. a substrate having a main surface with a diameter of 3 inches or more; a piezoelectric film formed on the substrate and made of an alkali niobium oxide containing K, Na, Nb, and O; A piezoelectric laminate in which the compositions of K, Na, and Nb in the piezoelectric film satisfy the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire inner area of ​​the main surface of the piezoelectric film excluding a peripheral portion that is a region 5 mm from the edge.

2. A piezoelectric laminate as described in claim 1, wherein the piezoelectric film is cut in a grid pattern at 1 cm intervals over the entire inner area of ​​the main surface of the piezoelectric film excluding the peripheral edge portion to create a plurality of small pieces, and all of the small pieces created have a planar area of ​​25 mm 2 or more and are used as samples.When the compositions of K, Na, and Nb in the piezoelectric film for each of the plurality of samples are measured, the compositions of K, Na, and Nb in the piezoelectric film for all of the samples satisfy the relationship 0.94≦(K+Na) / Nb≦1.

03.

3. A piezoelectric laminate as described in claim 1, wherein the composition of K, Na and Nb in the piezoelectric film satisfies the relationship 0.96≦(K+Na) / Nb≦1.00 throughout the entire inner area of ​​the main surface of the piezoelectric film excluding the peripheral portion.

4. 2. The piezoelectric stack according to claim 1, wherein the alkali niobium oxide further contains, as a dopant, at least one element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga.

5. preparing a sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O, wherein the composition of K, Na, and Nb satisfies the relationship of 0.95≦(K+Na) / Nb≦1.2 over the entire inner area of ​​the surface exposed to plasma, excluding a peripheral edge portion that is a region 5 mm from the edge, and the Vickers hardness of the surface exposed to plasma is 150 or more over the entire inner area of ​​the surface exposed to plasma, excluding the peripheral edge portion; providing a substrate having a major surface with a diameter of 3 inches or more; and forming, on the substrate using the sputtering target material, a piezoelectric film formed from an alkali niobium oxide containing K, Na, Nb, and O, wherein the K, Na, and Nb compositions satisfy the relationship 0.94≦(K+Na) / Nb≦1.03 over the entire inner area of ​​the main surface excluding a peripheral edge portion that is a region 5 mm from the edge. A method for manufacturing a piezoelectric laminate.

6. A sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O, the compositions of K, Na, and Nb satisfy the relationship 0.95≦(K+Na) / Nb≦1.2 throughout the entire inner area excluding a peripheral portion, which is a region 5 mm from the edge of the surface exposed to plasma; the Vickers hardness of the surface exposed to the plasma is 150 or more over the entire inner area of ​​the surface exposed to the plasma excluding the peripheral edge portion; Temperature: 500 to 700°C, discharge power density: 2.7 to 4.1 W / cm ２ When used as a target material in forming a piezoelectric film on a substrate having a main surface with a diameter of 3 inches or more by a sputtering method under the conditions of an atmosphere of a mixed gas of argon gas and oxygen gas, an atmospheric pressure of 0.2 to 0.5 Pa, an argon gas partial pressure / oxygen gas partial pressure = 30 / 1 to 20 / 1, and a film formation rate of 0.5 to 2 μm / hr, On the substrate, the piezoelectric film is formed from an alkali niobium oxide containing K, Na, Nb, and O, and the compositions of K, Na, and Nb satisfy the relationship of 0.94≦(K+Na) / Nb≦1.03 over the entire inner area of ​​the main surface excluding a peripheral portion that is a region 5 mm from the edge. Sputtering target material.

7. A sputtering target material formed from a sintered body containing an oxide containing K, Na, Nb, and O, When forming a piezoelectric film by sputtering, the surface area exposed to plasma is 44.2 cm ２ or more, and the thickness is 3 mm or more, the compositions of K, Na, and Nb satisfy the relationship 0.95≦(K+Na) / Nb≦1.2 throughout the entire inner area of ​​the surface exposed to the plasma, excluding a peripheral portion that is a region 5 mm from the edge, A sputtering target material in which the Vickers hardness of the surface exposed to the plasma is 150 or more over the entire inner area of ​​the surface exposed to the plasma excluding the peripheral edge portion.

8. 8. The sputtering target material according to claim 6 or 7, further containing, as a dopant, at least one element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga.

9. It is made of a sintered body containing an oxide containing K, Na, Nb, and O, and the area of ​​the surface exposed to plasma is 44.2 cm ２ A method for manufacturing a target material having the above and a thickness of 3 mm or more, (a) a step of mixing a powder consisting of a K compound, a powder consisting of a Na compound, and a powder consisting of a Nb compound in a predetermined ratio, or mixing a powder consisting of a compound containing K and Nb with a powder consisting of a compound containing Na and Nb in a predetermined ratio so that the composition of K, Na, and Nb satisfies the relationship 0.95≦(K+Na) / Nb≦1.2, to obtain a mixture; (b) Heating the mixture while applying a predetermined pressure to the mixture to form a mold having a main surface area of ​​44.2 cm ２ and obtaining a sintered body having a thickness of 3 mm or more and a Vickers hardness of 150 or more over the entire inner area of ​​the surface exposed to the plasma except for a peripheral portion that is a region 5 mm from the edge of the surface exposed to the plasma, In (b), the pressure is increased by 1 kgf / cm per minute until the predetermined pressure is reached. ２ A method for producing a sputtering target material, comprising gradually increasing the pressure at the following rate, and maintaining the temperature of the surface that will become the main surface of the sintered body at 900 to 1200°C for 12 hours or more.

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