JP2019182681A - Oxide dielectric and manufacturing method thereof, and solid electronic device and manufacturing method thereof - Google Patents

Abstract

To provide an oxide dielectric capable of achieving sufficiently low dielectric loss in addition to high dielectric constant, and a solid electronic device equipped with the oxide dielectric (such as a capacitor, a semiconductor device, or a micro-electromechanical system).SOLUTION: One embodiment of the manufacturing method of an oxide dielectric includes: a precursor layer formation step of forming a precursor solution layer from a precursor solution comprising a precursor involving bismuth (Bi), a precursor involving niobium (Nb), and a precursor involving nickel (Ni) as solutes by application method; and an oxide dielectric layer formation step for forming an oxide dielectric layer 30 containing an oxide (which may include inevitable impurities) comprising bismuth (Bi), niobium (Nb), and nickel (Ni) and having a crystal phase of a pyrochlore crystal structure by a heating treatment of heating the precursor solution layer in an oxygen-containing atmosphere.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an oxide dielectric and a manufacturing method thereof, and a solid-state electronic device and a manufacturing method thereof.

Conventionally, oxide layers composed of various compositions having functionality have been developed. Further, as an example of a solid-state electronic device including the oxide layer, a device including a ferroelectric thin film that can be expected to operate at high speed has been developed. Further, BiNbO ₄ has been developed as an oxide layer that does not contain lead (Pb) and can be baked at a relatively low temperature as a dielectric material used in the solid-state electronic device. As for this BiNbO ₄ , the dielectric properties of BiNbO ₄ formed by the solid phase growth method have been reported (Non-patent Document 1). Furthermore, from bismuth (Bi), nickel (Ni), and niobium (Nb) formed through a high temperature treatment of 900 ° C. or higher (in some cases, 1000 ° C. or higher) and a very long (half day or longer) process time. The oxide which becomes is disclosed (nonpatent literatures 2 and 3).

  In addition, the patent document discloses an oxide layer made of bismuth (Bi) and niobium (Nb) having a relative dielectric constant of 60 or more at 1 kHz (Patent Document 1). ~ 3). Further, the relative permittivity variation with respect to the change in the environmental temperature in which the oxide composed of bismuth (Bi) and niobium (Nb) is present is small, in other words, the resistance to the change in the environmental temperature is greatly enhanced. The oxide is disclosed (Patent Document 4).

International Publication No. WO2013 / 066940 International Publication No. WO2013 / 069471 Japanese Patent Laying-Open No. 2015-67475 International Publication No. WO2016 / 013416

Effect of phase transition on the microwave dielectric properties of BiNbO4, Eung Soo Kim, Woong Choi, Journal of the European Ceramic Society 26 (2006) 1761-1766 Structures, phase transformations, and dielectric properties of (1-x) Bi2Zn2 / 3Nb4 / 3O7-xBi1.5NiNb1.5O7pychlore ceramics prepared by aqueous by sol-gel method, YX Jin, et al, Journalof Alloys and Compounds 622 (2015) 200 -205 The local crystal chemistry and dielectric properties of the cubicpyrochlore phase in the Bi2O3-M2 + O-Nb2O5 (M2 + = Ni2 + and Mg2 +) systems, Binh Nguyen et al, Journal of Solid State Chemistry 180 (2007) 549-557

  In the industry, in order to realize high performance of solid-state electronic devices including capacitors or capacitors (hereinafter collectively referred to as “capacitors”), semiconductor devices, or microelectromechanical systems, only a high relative dielectric constant is required. However, there is a need for oxide dielectrics and oxide dielectric layers that have low dielectric loss (dielectric loss tangent: tan δ) electrical properties.

  In addition to the above-mentioned problems, if high-temperature treatment is required for the production of the above-mentioned oxide and / or long-time treatment is required, it is possible to realize high-performance oxide. However, since it is a product that is easily unacceptable in the industry, lowering the processing temperature and shortening the processing time of the oxide are technical problems that cannot be avoided in the industry.

  In addition to the above-mentioned problems, a thick film that has not been fully realized in the manufacturing process for manufacturing an oxide dielectric having high performance in terms of relative permittivity and / or dielectric loss can be realized with high accuracy. If it is possible, it is possible to manufacture an oxide dielectric that is simpler and less costly and that is more reliable in terms of electrical characteristics. More specifically, it is a fundamental technology for using oxide dielectrics with advanced electrical characteristics in the industry to accurately suppress or prevent the phenomenon of film cracking, which tends to occur with increasing film thickness. It becomes.

  Note that it is one of the important technical issues to realize a thick oxide dielectric layer in a high-frequency filter, a patch antenna, or an RCL, which are other examples of solid-state electronic devices. In addition, oxidation also occurs in solid-state electronic devices as composite devices including at least two types selected from the group of capacitors, high-frequency filters, patch antennas, semiconductor devices, microelectromechanical systems (MEMS, NEMS), and RCLs. The realization of thicker dielectric layers is one of the important technical issues.

  In addition, in the prior art, a process that requires a relatively long time and / or expensive equipment such as a vacuum process or a process using a photolithography method is generally used, so that the use efficiency of raw materials and manufacturing energy is very poor. Become. When the manufacturing method as described above is adopted, many processes and a long time are required to manufacture the solid-state electronic device, which is not preferable from the viewpoint of industrial property or mass productivity. In addition, there is a problem in the prior art that it is relatively difficult to increase the area.

  The present invention solves at least one of the above-described problems, thereby improving the performance of a solid-state electronic device using an oxide as a dielectric or an insulator (hereinafter collectively referred to as “dielectric”). An object of the present invention is to realize simplification and energy saving of the manufacturing process of the solid-state electronic device. As a result, the present invention greatly contributes to the provision of an oxide dielectric excellent in industrial and mass productivity and a solid-state electronic device including the oxide dielectric.

  The present inventors have so far aimed at improving or improving various characteristics of oxides (hereinafter also referred to as “BNO oxides”) composed of bismuth (Bi) and niobium (Nb) having a relatively high relative dielectric constant. Have been intensively studied and analyzed. In addition, the present inventors from a new viewpoint, not only BNO oxide but also bismuth (Bi), niobium (Nb), and titanium (which realizes improvement in electrical characteristics (particularly very low dielectric loss)). An oxide composed of Ti) (hereinafter also referred to as “BNTO oxide”) was also created.

  However, the present inventors have not only improved the performance of oxides having the respective compositions described above, but also improved performance, specifically, relatively high relative dielectric constant and improved electrical characteristics (particularly low). Exploring oxides of another composition that achieve dielectric loss and stability of the dielectric loss to ambient temperature, lowering the temperature and shortening to a point where the oxide of the other composition is considered acceptable by the industry We have also worked hard to make it easier.

  In addition, with respect to oxides created by the coating method created so far, there has been a possibility that it has not been possible to sufficiently realize the phenomenon that the formed film breaks with a high degree of accuracy. . For example, when the film thickness is increased by using a spin coating method or a bar coating method, the film thickness can be increased by a single application and heat treatment only by increasing the dissolved mass in the solution to be applied. Even if this is the case, it has become clear from the investigation and analysis by the present inventors that the film is likely to “crack”.

  Thus, as a result of detailed examination and analysis, and many trials and errors, the present inventors have found that three elements (bismuth (Bi), nickel (Ni), and That oxides containing niobium (Nb) can achieve both a high dielectric constant and higher performance electrical properties (specifically, low dielectric loss and stability of the dielectric loss to ambient temperature). I found it. In addition, by adopting a certain manufacturing method, it is possible to realize a low temperature and a short time to an extent that can be considered acceptable in the industry, and is composed of bismuth (Bi), nickel (Ni), and niobium (Nb). The present inventors have found a method for producing an oxide (hereinafter also referred to as “BiNiNbO oxide” or simply “BNNO oxide”).

  Further, in the above-described research process, the present inventors have substantially affected the physical properties of the finally formed BiNiNbO oxide (BNNO oxide), and the film is formed by a single application and heat treatment. The present inventors have found an additive that realizes a thick film in which cracking is prevented or suppressed with high accuracy. As a result, the present inventors have also found that it is possible to produce a thick oxide layer with high accuracy, since cracking hardly occurs by a single application and heat treatment. In other words, it is possible to produce a thick oxide layer with high accuracy without causing cracking without repeating a cycle of coating and heat treatment many times. Note that these thick oxide layers can also achieve high dielectric constants and / or low dielectric loss values, similar to BNNO oxides that are not thickened.

  Further, the present inventors have found that an inexpensive and simple manufacturing process can be realized by adopting a method that does not require a high vacuum state in the manufacturing method of the oxide (oxide dielectric). . Among such manufacturing processes, a typical one is a “printing” processing method also called a screen printing method or “nanoimprint”. In addition to the fact that the present inventors can pattern an oxide layer made of the oxide dielectric (BNNO oxide in the present invention) by the above-described methods that are inexpensive and simple. I found it. As a result, the inventors of the present invention provided the oxide dielectric, and thus the oxide dielectric, by a process that is greatly simplified or energy-saving as compared with the prior art, and also easy to increase the area. The knowledge that a solid-state electronic device can be manufactured was obtained. The present invention has been created based on the above viewpoints.

  One oxide dielectric manufacturing method of the present invention comprises a precursor solution containing a precursor containing bismuth (Bi), a precursor containing niobium (Nb), and a precursor containing nickel (Ni) as a solute. Bismuth (Bi) having a crystal phase of a pyrochlore type crystal structure by a precursor layer forming step of forming a precursor solution layer by a coating method, and heat treatment for heating the precursor solution layer in an oxygen-containing atmosphere; An oxide dielectric layer forming step of forming an oxide dielectric layer containing an oxide (which may include inevitable impurities) made of niobium (Nb) and nickel (Ni) is included.

  According to this manufacturing method, a BNNO oxide (oxide dielectric) capable of realizing a sufficiently low dielectric loss in addition to a high relative dielectric constant can be manufactured. Moreover, the precursor layer formation process which forms the precursor solution layer which consists of the above-mentioned precursor solution by the apply | coating method is performed. From another viewpoint, according to this manufacturing method, for example, a precursor layer forming step is performed in which the precursor layer is formed without going through powder formation of the precursor solution layer. Therefore, a BNNO oxide (oxide dielectric) can be manufactured by a treatment at a relatively low temperature (for example, less than 850 ° C.) and sufficiently shorter (for example, 2 hours or less) than conventional.

  In addition, one oxide dielectric of the present invention includes an oxide (which may include inevitable impurities) made of bismuth (Bi), niobium (Nb), and nickel (Ni) having a pyrochlore crystal structure. Including. In addition, in this oxide derivative, when the number of atoms of the niobium (Nb) is 1, the number of atoms of the bismuth (Bi) is 1.2 or more and 1.9 or less, and the nickel (Ni) Is 0.25 or more and 0.75 or less.

  This oxide derivative is an oxide dielectric that achieves a high dielectric constant and has improved electrical characteristics (particularly, low dielectric loss and stability of the dielectric loss with respect to ambient temperature).

  Another oxide dielectric according to the present invention is an oxide composed of bismuth (Bi), niobium (Nb), and nickel (Ni) having a crystal phase of a pyrochlore crystal structure (may contain inevitable impurities). including. In addition, in this oxide derivative, when the number of atoms of the niobium (Nb) is 1, the number of atoms of the bismuth (Bi) is 0.8 or more and less than 1.2, and the nickel (Ni) The number of atoms is 0.25 or more and 0.75 or less, and the relative dielectric constant at 25 ° C. is more than 135.

  This oxide derivative is an oxide dielectric that achieves a high dielectric constant and has improved electrical characteristics (particularly, low dielectric loss and stability of the dielectric loss with respect to ambient temperature).

  Another oxide dielectric according to the present invention is an oxide composed of bismuth (Bi), niobium (Nb), and nickel (Ni) having a crystal phase of a pyrochlore crystal structure (may contain inevitable impurities). including. In addition, in this oxide derivative, when the number of atoms of the niobium (Nb) is 1, the number of atoms of the bismuth (Bi) is 0.5 or more and less than 0.7, and the nickel (Ni) Is 0.05 or more and less than 0.25.

  According to this oxide derivative, even if the bismuth (Bi) content is very small, a certain degree of high specific permittivity and low dielectric loss can be realized at the same time. In addition, it is worthy of special note that by reducing the content of bismuth (Bi) having a small amount of crustal reserve, an advantage that stable production can be expected in the long term is obtained.

  Also, one oxide dielectric precursor solution of the present invention is a precursor solution containing a precursor containing bismuth (Bi), a precursor containing niobium (Nb), and a precursor containing nickel (Ni) as a solute. Containing.

  This oxide dielectric precursor solution can be used in a precursor layer forming step of forming a precursor solution layer made of the oxide dielectric precursor solution by a coating method. As a result, by adopting the oxide dielectric precursor solution, for example, a precursor layer formation can be formed without going through pulverization of the precursor solution layer. In terms of electrical characteristics, it can be used as a raw material for oxide dielectric layers with higher reliability.

  By the way, in the above oxide dielectric manufacturing method, an oxide layer is formed by a relatively simple process (for example, an ink jet method, a screen printing method, an intaglio / letter printing method, or a nanoimprint method) without using a photolithography method. Can be done. This eliminates the need for relatively long and / or expensive equipment such as a process using a vacuum process. As a result, the manufacturing method of each above-mentioned oxide layer is excellent in industrial property or mass productivity.

  In a specific example, in the invention of the manufacturing method described above, the state in which the precursor layer is heated at 80 ° C. to 250 ° C. in an oxygen-containing atmosphere before forming the oxide dielectric layer. Forming the precursor embossing structure by embossing in a process eliminates the need for relatively long and / or expensive equipment such as a process using a vacuum process. From the viewpoint of making it, this is a preferred embodiment that can be adopted.

  In the present application, the “coating method” means a CSD (Chemical Solution Deposition) method represented by a spin coating method, a dip coating method, a bar coating method, a screen printing method, and a LSMCD (Liquid Source Misted Chemical Deposition) method. Means.

  Further, in the present application, “in an oxygen-containing atmosphere” means that the atmosphere is in an atmosphere containing oxygen, and includes a normal air (atmosphere) environment. Further, the “layer” in the present application is a concept including not only a layer but also a film. Conversely, the “film” in the present application is a concept including not only a film but also a layer.

  According to one oxide dielectric manufacturing method of the present invention, a BNNO oxide (oxide dielectric) capable of realizing a sufficiently low dielectric loss in addition to a high dielectric constant can be manufactured.

  In addition, one oxide dielectric of the present invention is an oxide dielectric that realizes a high dielectric constant and improved electrical characteristics (particularly, low dielectric loss and stability of the dielectric loss with respect to ambient temperature). is there.

  In addition, one oxide dielectric precursor solution of the present invention is simple and low-cost in a precursor layer forming step of forming a precursor solution layer comprising the oxide dielectric precursor solution by a coating method. Also, in terms of electrical characteristics, it can be utilized as a raw material for an oxide dielectric layer with higher reliability.

It is a figure which shows the whole structure of the thin film capacitor which is an example of the solid-state electronic device in 1st Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in 1st Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in 1st Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in 1st Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in 1st Embodiment. The relative permittivity and dielectric loss of the thin film capacitor when the number of atoms of bismuth (Bi) is changed when the number of atoms of (a) niobium (Nb) in the oxide of the first embodiment is 1. Correlation with (dielectric loss tangent: tan δ), (b) relative dielectric constant and dielectric loss of thin film capacitor when the number of atoms of nickel (Ni) is changed when the number of atoms of niobium (Nb) is 1. It is a graph which shows the correlation with (dielectric loss tangent: tan-delta). It is a graph which shows the result of having measured the temperature dependence of the dielectric loss (dielectric loss tangent: tan-delta) in an example of the oxide dielectric layer of this embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the modification of 1st Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the modification of 1st Embodiment. It is a figure which shows the whole structure of the thin film capacitor which is an example of the solid-state electronic device in the modification of 1st Embodiment. It is a figure which shows the whole structure of the multilayer capacitor which is an example of the solid-state electronic device in 2nd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the multilayer capacitor which is an example of the solid-state electronic device in 2nd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the multilayer capacitor which is an example of the solid-state electronic device in 2nd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the multilayer capacitor which is an example of the solid-state electronic device in 2nd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the multilayer capacitor which is an example of the solid-state electronic device in 2nd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the multilayer capacitor which is an example of the solid-state electronic device in 2nd Embodiment. It is a figure which shows the whole structure of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a figure which shows the whole structure of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment of this. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is an observation photograph (plan view) with an optical microscope after the processing of an oxide dielectric layer obtained by embossing a precursor layer in a third embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor which is an example of the solid-state electronic device in 3rd Embodiment. It is a figure which shows the whole structure of the thin-film transistor of other embodiment.

  A solid-state electronic device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this description, common parts are denoted by common reference symbols throughout the drawings unless otherwise specified. In the drawings, elements of the present embodiment are not necessarily described with each other kept to scale. Further, some symbols may be omitted to make each drawing easier to see.

<First Embodiment>
1. 1 is a diagram showing an overall configuration of a thin film capacitor 100a that is an example of a solid-state electronic device in the present embodiment. As shown in FIG. 1, a thin film capacitor 100 a is formed on a substrate 10 from the substrate 10 side, a lower electrode layer 20, an oxide dielectric layer (hereinafter also referred to as “oxide layer” for short). 30 and the upper electrode layer 40.

The substrate 10 is, for example, a high heat resistant glass, a SiO ₂ / Si substrate, an alumina (Al ₂ O ₃ ) substrate, an STO (SrTiO) substrate, or an STO (SrTiO) via a SiO ₂ layer and a Ti layer on the surface of the Si substrate. Insulating substrate in which layers are formed, an insulating substrate in which a SiO ₂ layer and a TiO _X layer are laminated in this order on the surface of a Si substrate, and a semiconductor substrate (for example, a Si substrate, a SiC substrate, a Ge substrate, a resin substrate, etc. ) Can be used. In addition, the example of the base material of this embodiment includes a resinous base material (for example, a known flexible substrate) in addition to the above-described various substrates.

  As a material of the lower electrode layer 20 and the upper electrode layer 40, a metal material such as a refractory metal such as platinum, gold, silver, copper, aluminum, molybdenum, palladium, ruthenium, iridium, tungsten, or an alloy thereof is used. .

  The oxide dielectric layer (oxide layer 30) of this embodiment is a precursor solution layer (hereinafter referred to as “precursor”) that uses a precursor solution (also referred to as “first oxide dielectric precursor solution”) as a starting material. The body layer ”is also formed by heating in an oxygen-containing atmosphere (hereinafter, the production method according to this step is also referred to as“ solution method ”).

  Examples of the solute of the precursor solution of the present embodiment are a precursor containing bismuth (Bi), a precursor containing niobium (Nb), and a precursor containing nickel (Ni).

  By adopting a precursor layer starting from the first oxide dielectric precursor solution described above, BiNiNbO oxide composed of bismuth (Bi), niobium (Nb) and nickel (Ni) (in short, , An oxide dielectric layer (oxide layer 30) containing “BNNO oxide” (however, inevitable impurities may be included; the same shall apply hereinafter).

  In addition, this embodiment is not limited to the structure shown in FIG. Further, in order to simplify the drawing, description of patterning of the extraction electrode layer from each electrode layer is omitted.

2. Manufacturing Method of Thin Film Capacitor 100a Next, a manufacturing method of the thin film capacitor 100a will be described. In addition, the display of the temperature in this application represents the preset temperature of a heater. 2 to 5 are cross-sectional schematic views showing one process of the method of manufacturing the thin film capacitor 100a. As shown in FIG. 2, first, the lower electrode layer 20 is formed on the substrate 10. Next, the oxide layer 30 is formed on the lower electrode layer 20, and then the upper electrode layer 40 is formed on the oxide layer 30.

(1) Formation of Lower Electrode Layer FIG. 2 is a diagram showing a process of forming the lower electrode layer 20. In the present embodiment, an example in which the lower electrode layer 20 of the thin film capacitor 100a is formed of platinum (Pt) will be described. As the lower electrode layer 20, a layer (for example, 200 nm thick) made of platinum (Pt) is formed on the substrate 10 by a known sputtering method.

(2) Formation of Oxide Layer as Insulating Layer or Dielectric Layer Next, the oxide layer 30 is formed on the lower electrode layer 20. The oxide layer 30 is formed in the order of (A) formation of a precursor layer and preliminary firing, and (B) main firing. 3 and 4 are diagrams showing a process of forming the oxide layer 30. FIG. In this embodiment, the oxide layer 30 in the manufacturing process of the thin film capacitor 100a is formed of an oxide composed of bismuth (Bi), niobium (Nb), and nickel (Ni) having a crystal phase of a pyrochlore crystal structure. An example will be described.

(A) Formation of precursor layer (precursor layer forming step) and preliminary firing As shown in FIG. 3, in the precursor layer forming step of the present embodiment, a precursor solution layer (precursor) is formed on the lower electrode layer 20. Layer) 30a is formed. Specifically, a precursor containing bismuth (Bi) (also referred to as precursor A) and a precursor containing niobium (Nb) (also referred to as precursor B) on the lower electrode layer 20 by a known spin coating method. And a precursor solution containing nickel (Ni) -containing precursor (also referred to as precursor C) as a solute, sorbitan fatty acid ester, sorbitan fatty acid ester polyoxyethylene ether, polyvinyl polymer, and ethylene polymer A precursor layer 30a is formed using a precursor solution obtained by mixing at least one additive selected from the group as a starting material.

  Here, examples of the precursor A for the oxide layer 30 include bismuth octylate, bismuth chloride, bismuth nitrate, or various bismuth alkoxides (for example, bismuth isopropoxide) in addition to the above-described bismuth 2-ethylhexanoate. Bismuth butoxide, bismuth ethoxide, bismuth methoxyethoxide) and the like. Examples of the precursor B in this embodiment include niobium 2-ethylhexanoate, niobium octylate, niobium chloride, niobium nitrate, or various niobium alkoxides (for example, niobium isopropoxide) in addition to the niobium ethoxide described above. , Niobium butoxide, niobium methoxyethoxide) may be employed. In addition to the above-described nickel acetylacetonate dihydrate, nickel acetate, nickel nitrate, nickel chloride, or various nickel alkoxides can be adopted as an example of the precursor C in the present embodiment.

  Moreover, the solvent of the precursor solution of this embodiment is at least one alcohol solvent selected from the group of ethanol, propanol, butanol, 2-methoxyethanol, 2-ethoxyethanol, and 2-butoxyethanol, or acetic acid, The solvent is at least one carboxylic acid selected from the group of propionic acid, octylic acid, and 2-ethylhexanoic acid, or at least one ketone selected from the group of acetone and acetyl asenton. preferable. Therefore, in the solvent of the precursor solution, a mixed solvent of the above two or more alcohol solvents, a mixed solvent of the above two or more carboxylic acids, a mixed solvent of the above two or more ketones, and the above An alcohol solvent, a solvent of the above carboxylic acid, and a mixed solvent of two or more selected from the group of the above solvents of ketones are also an embodiment that can be adopted.

In addition, the precursor solution of this embodiment mixes the 1st solution shown in the following (1), the 2nd solution shown in the following (2), and the 3rd solution shown in the following (3). Is manufactured by.
(1) A first solution obtained by diluting bismuth 2-ethylhexanoate with 1-butanol, or a first solution obtained by diluting bismuth 2-ethylhexanoate with 2 ethylhexanoic acid, or bismuth 2-ethylhexanoate with 1-butanol A solution obtained by diluting bismuth 2-ethylhexanoate with 2 ethylhexanoic acid and a second solution obtained by diluting niobium ethoxide with 1-butanol, or niobium ethoxide A second solution diluted with 2 ethylhexanoic acid, or (3) a solution obtained by diluting nickel acetylacetonate dihydrate with 1-butanol and a third solution or nickel acetylacetonate dihydrate with 2 ethylhexane Third solution diluted with acid or nickel acetylacetonate dihydrate diluted with 1-butanol and nickel acetyl The third solution was mixed with a solution prepared by diluting Setonato dihydrate in 2-ethylhexanoic acid, the

Moreover, in this embodiment, it is a precursor so that the number of atoms of niobium (Nb), the number of atoms of bismuth (Bi), and the number of atoms of nickel (Ni) become the ratios shown in the following (a1) to (c1). A body solution was prepared.
(A1) When the number of atoms of niobium (Nb) is 1, the number of atoms of bismuth (Bi) is 1.2 or more and 1.9 or less, and the number of atoms of nickel (Ni) is 0.25 or more and 0 .75 or less (b1) When the number of atoms of niobium (Nb) is 1, the number of atoms of bismuth (Bi) is 0.8 or more and less than 1.2, and the number of atoms of nickel (Ni) is 0.25. 0.75 or less (c1) When the number of atoms of niobium (Nb) is 1, the number of atoms of bismuth (Bi) is 0.5 or more and less than 0.7, and the number of atoms of nickel (Ni) is 0.05 or more and less than 0.25

  Note that the precursor solution (first oxide dielectric precursor solution) of the present embodiment can contain other substances as long as the effects of the present embodiment can be obtained.

  Thereafter, as pre-baking, pre-baking is performed in a temperature range of 80 ° C. or higher and 450 ° C. or lower for a predetermined time in an oxygen-containing atmosphere. In addition, it can also employ | adopt performing prebaking in multiple times in the above-mentioned temperature range. In the pre-firing, the solvent (typically, the main solvent) in the precursor layer 30a is sufficiently evaporated, and in order to develop characteristics that enable future plastic deformation (before thermal decomposition) Thus, it is considered that the organic chain remains). Forming such a gel state makes it easier to form a film by an embossing method or a screen printing method, which is one method of a film forming process described later. Further, preliminary baking may be further performed after the film formation by the embossing method or the screen printing method. In order to realize the above-mentioned viewpoint with higher accuracy, the pre-baking temperature is preferably 80 ° C. or higher and 450 ° C. or lower. Moreover, the desired thickness of the oxide layer 30 can be obtained by repeating the formation and preliminary baking of the precursor layer 30a by the above-described spin coating method a plurality of times.

(B) Main firing (oxide dielectric layer forming step)
Thereafter, in the oxide dielectric layer forming step of the present embodiment, the oxide layer is formed by a heat treatment in which the precursor solution layer (precursor layer) 30a formed on the lower electrode layer 20 is heated in an oxygen-containing atmosphere. (Oxide dielectric layer, oxide layer 30) is formed. Specifically, as a heating process for the main firing, the precursor layer 30a is placed in an oxygen atmosphere (for example, but not limited to 100% by volume) for a predetermined short time (for example, 20 minutes), A heating step is performed in which heating is performed at a temperature (first temperature) in a range of 600 ° C. to 800 ° C. (typically, 750 ° C. or less). As a result, as shown in FIG. 4, an oxide dielectric layer (oxide layer 30) (eg, 100 nm thick) made of bismuth (Bi), niobium (Nb), and nickel (Ni) is formed on the electrode layer. It is formed.

  It should be noted that the BNNO oxide (oxide dielectric) of this embodiment can be formed by heat treatment at a low temperature of 800 ° C. or lower. For example, when heat treatment at 900 ° C. or higher is required to form an oxide layer from a solid phase or liquid phase starting material, many electrode materials (eg, silver) provided in an electronic device can withstand the heating temperature. Therefore, the material that can be used is limited (for example, to tungsten or the like). In addition, such a high temperature treatment may cause a problem that it is not suitable for low temperature co-fired ceramics (LTCC), which is a type of so-called electronic ceramics.

  Further, from the viewpoint of leakage current and dielectric loss accompanying the decrease in film thickness, the thickness of the oxide layer 30 is preferably 30 nm or more. If the thickness of the oxide layer 30 is less than 30 nm, it is not preferable to apply it to a solid-state electronic device due to an increase in leakage current and dielectric loss accompanying a decrease in the thickness.

(3) Formation of Upper Electrode Layer Next, the upper electrode layer 40 is formed on the oxide layer 30. FIG. 5 is a diagram illustrating a process of forming the upper electrode layer 40. In the present embodiment, an example in which the upper electrode layer 40 of the thin film capacitor 100a is formed of platinum (Pt) will be described. In the upper electrode layer 40, similarly to the lower electrode layer 20, a layer (for example, 150 nm thick) made of platinum (Pt) is formed on the oxide layer 30 by a known sputtering method. By forming the upper electrode layer 40, the thin film capacitor 100a shown in FIG. 1 is manufactured.

  As described above, if the oxide layer manufacturing method of the present embodiment is employed, the precursor solution may be heated in an oxygen-containing atmosphere without using a vacuum process, and therefore has a large area compared to the conventional sputtering method. It becomes easy to make it easier, and it becomes possible to remarkably improve industrial property or mass productivity.

<Various characteristic evaluation of the thin film capacitor 100a>
By the way, in the thin film capacitor 100a of this embodiment, the oxide layer 30 obtained by heat treatment at least at 800 ° C. or lower (more preferably at 700 ° C. or lower) is an oxide composed of a crystal phase having a pyrochlore crystal structure. It became clear that it included. Note that the oxide layer 30 of the present embodiment may include a microcrystalline phase.

  The inventors have obtained an analysis result that the oxide layer 30 of this embodiment made of bismuth (Bi), niobium (Nb), and nickel (Ni) has a pyrochlore crystal structure. Since the oxide layer 30 has a crystal phase having a pyrochlore crystal structure, the dielectric layer of the thin film capacitor, the dielectric layer of the multilayer capacitor, or other various solid-state electronic devices (for example, semiconductor devices or microelectromechanical systems) Can lead to good dielectric properties (especially very low dielectric loss) as an insulating layer.

  As an example of a dielectric having a pyrochlore crystal structure known so far, an oxide composed of bismuth (Bi), niobium (Nb), and zinc (Zn) is known. Have obtained an analysis result that the oxide layer 30 of this embodiment made of bismuth (Bi), niobium (Nb), and nickel (Ni) has a pyrochlore crystal structure. Since the oxide layer 30 has a crystal phase having a pyrochlore crystal structure, the dielectric layer of the thin film capacitor, the dielectric layer of the multilayer capacitor, or other various solid-state electronic devices (for example, semiconductor devices or microelectromechanical systems) Can lead to good dielectric properties (especially low dielectric loss and stability of the dielectric loss against ambient temperature) as an insulating layer.

  Below, the experimental result which has confirmed that the thin film capacitor 100a of this embodiment has a favorable electrical property is demonstrated.

<Measurement results of dielectric loss (dielectric loss tangent: tan δ) and relative dielectric constant>
FIG. 6 shows that after the main baking and the subsequent post-annealing treatment (for example, 600 ° C. or higher and 800 ° C. or lower (typically 750 ° C. or lower) for about 20 minutes), It is a graph which shows correlation with the relative dielectric constant and the value of dielectric loss (dielectric loss tangent: tan-delta) about five samples which changed the ratio of bismuth (Bi): niobium (Nb): nickel (Ni). 6A shows the relative permittivity and dielectric loss (dielectric loss tangent) of the thin film capacitor 100a when the number of atoms of bismuth (Bi) is changed when the number of atoms of niobium (Nb) is 1. FIG. : Tan δ). FIG. 6B shows the relative dielectric constant and dielectric loss (dielectric loss tangent) of the thin film capacitor 100a when the number of nickel (Ni) atoms is varied, assuming that the number of niobium (Nb) atoms is one. : Tan δ). In both FIG. 6A and FIG. 6B, the black square indicates the value of dielectric loss (dielectric loss tangent: tan δ), and the square with only the outline indicates dielectric loss (dielectric loss tangent: tan δ). The value of is shown.

  The relative dielectric constant was measured by applying a voltage of 0.1 V and an AC voltage of 1 kHz between the lower electrode layer and the upper electrode layer. For this measurement, a 1260-SYS type broadband dielectric constant measurement system manufactured by Toyo Corporation was used. The dielectric loss (dielectric loss tangent: tan δ) was measured by applying a voltage of 0.1 V and an alternating voltage of 1 kHz between the lower electrode layer and the upper electrode layer at room temperature (about 25 ° C.). For this measurement, a 1260-SYS type broadband dielectric constant measurement system manufactured by Toyo Corporation was used.

From the results shown in FIGS. 6A and 6B, the present inventors have an oxide layer (oxide dielectric layer) included in the numerical range shown in the following (a2). The thin film capacitor 100a has a sufficiently low dielectric loss (typically tan δ = 0.003 or less, more narrowly) in addition to a high relative dielectric constant (typically 125 or more, more narrowly 130 or more). Was found to be less than 0.003). More specifically, within the numerical range shown in (a2) below, the thin film capacitor 100a has a significant technical advantage compared to, for example, Non-Patent Document 1 or 2 described above. I can confirm that.
(A2) When the number of atoms of niobium (Nb) is 1, the number of atoms of bismuth (Bi) is 1.2 or more and 1.9 or less, and the number of atoms of nickel (Ni) is 0.25 or more and 0.75. Less than

Furthermore, as a result of repeated analysis and examination by the inventors, the thin film capacitor 100a is sufficiently provided with an oxide layer (oxide dielectric layer) included in the numerical range shown in the following (b2). It was also found that a thin film capacitor having a low dielectric loss and excellent electrical characteristics can be realized.
(B2) When the number of atoms of niobium (Nb) is 1, the number of atoms of bismuth (Bi) is 0.8 or more and less than 1.2, and the number of atoms of nickel (Ni) is 0.25 or more and 0.75 or less. And the relative dielectric constant at 25 ° C. exceeds 135.

  In addition, regarding the numerical range of (b2) described above, as shown in FIG. 6 (a) in particular, the presence of BNNO oxide capable of realizing a relative dielectric constant exceeding 135 was confirmed even within this numerical range. It is based on what was done.

Further, as a result of analysis by the present inventors from a viewpoint different from the above, the thin film capacitor 100a includes an oxide dielectric layer included in the numerical range shown in the following (c2), whereby bismuth (Bi). It has been found that even if the content of is extremely small, a certain degree of high relative dielectric constant and low dielectric loss can be realized simultaneously. In addition, it is worthy of special note that by reducing the content of bismuth (Bi) having a small amount of crustal reserve, an advantage that stable production can be expected in the long term can be obtained.
(C2) When the number of niobium (Nb) atoms is 1, the number of bismuth (Bi) atoms is 0.5 or more and less than 0.7, and the number of nickel (Ni) atoms is 0.05 or more and 0. Less than 25

  By the way, all the results shown in FIGS. 6A and 6B are obtained at a relatively low temperature (typically 800 ° C. or lower) and short by adopting the solution method of this embodiment. It is worthy of special mention that it is obtained from an oxide dielectric layer obtained by heat treatment for a time (typically less than 1 hour). In the present embodiment, even if the main firing time and the post-annealing time are added together, the heating time is as short as about 40 minutes. Therefore, even if the result is not included in the numerical ranges shown in the above (a) to (c), the oxide dielectric layer that can be formed by a short heat treatment is, for example, the above-mentioned non-patent document. It is clear that it has a significant technical advantage compared to 1 or 2.

<Measurement result of temperature dependence of dielectric loss (dielectric loss tangent: tan δ)>
FIG. 7 shows dielectric loss (dielectric loss tangent: tan δ) in a BNNO oxide of Bi _1.65 Nb _0.75 Ni _1.5 O ₇ , which is an example of the oxide layer (oxide dielectric layer) of this embodiment. It is a graph which shows the result of having measured the temperature dependence of (). The “temperature” on the horizontal axis means the temperature of the measurement environment (atmosphere). The temperature substantially matches the temperature of the sample to be measured.

  As shown in FIG. 7, the value of the dielectric loss tangent is a low value of less than 0.001 (0.0005 or less) when the temperature of the measurement environment (and hence the temperature of the BNNO oxide) is in the temperature range from room temperature to over 100 ° C. It became clear that it was almost constant. Moreover, it turned out that such a tendency is seen also in the BNNO oxide of this embodiment which has another composition ratio. Therefore, it can be said that the BNNO oxide of this embodiment can realize excellent electrical characteristics (particularly, low dielectric loss) in a wide temperature range.

  As described above, the oxide (oxide layer 30) made of bismuth (Bi), niobium (Nb), and nickel (Ni) according to the present embodiment has a low dielectric loss value while maintaining a high relative dielectric constant. It can be realized. Therefore, it is particularly preferable to apply to various solid-state electronic devices (for example, a capacitor, a semiconductor device, or a microelectromechanical system, or a composite device including at least two of a high-frequency filter, a patch antenna, and an RCL). confirmed.

<Modification of First Embodiment>
In this embodiment, instead of the precursor solution in the first embodiment, a precursor solution obtained by mixing the precursor solution in the first embodiment and a specific additive (“second oxidation”). This is the same as in the first embodiment except that a “dielectric precursor solution” is also adopted. For example, in the present embodiment, the substrate 10, the lower electrode layer 20, the upper electrode layer 40, and their materials are the same as the electrode layers and their materials employed in the first embodiment. Therefore, the description which overlaps with 1st Embodiment may be abbreviate | omitted.

  FIG. 10 is a diagram showing an overall configuration of a thin film capacitor 100b which is an example of a solid-state electronic device in the present modification. 8 and 9 are schematic cross-sectional views showing one process of the method for manufacturing the thin film capacitor 100b.

  Similar to the first embodiment, the lower electrode layer 20 is formed on the substrate 10. Then, after a precursor solution layer (hereinafter also referred to as “precursor layer”) 30b is formed by a coating method as shown in FIG. 8, the oxide dielectric layer of this variation is formed as shown in FIG. (Oxide layer 30x) is formed. The oxide layer 30x is a precursor layer 30b starting from a precursor solution (also referred to as a “second oxide dielectric precursor solution”) obtained by mixing a precursor solution and a specific additive. Is formed by a method (solution method) of heating in an oxygen-containing atmosphere.

  The example of the solute of the second oxide dielectric precursor solution of the present modification is the same as the example of the solute of the first embodiment. An additive is further added to the precursor solution of this modification. The additive of this modification is a surfactant and / or a polymer. More specifically, the additive is at least one selected from the group consisting of sorbitan fatty acid ester, polyoxyethylene ether of sorbitan fatty acid ester, polyvinyl polymer, and ethylene polymer.

  In addition, the specific example of the material which can employ | adopt as an additive of this modification which the 2nd oxide dielectric precursor solution of this embodiment contains is as follows. The additive is not limited to the following examples. Materials equivalent to the following examples can also be applied to this embodiment.

  First, representative examples of “Sorbitan fatty acid ester, polyoxyethylene ether of sorbitan fatty acid ester” in this modification are Polyoxyethylene Sorbitan Monostearate, Polyoxyethylene Sorbitan Trioleate (Polyoxyethylene Sorbitan Trioleate) ).

  Next, specific examples of the “polyvinyl polymer” of this modification are polyvinyl pyrrolidone, polyvinyl pyrrolidone, (polyvinyl pyrrolidone / vinyl acetate) copolymer, polyvinyl alcohol, polyvinyl phenol, polyacrylamide, polymethyl methacrylate, polyvinyl methyl ether, Polyvinyl formamide, polyvinyl acetamide, and copolymers containing these.

  In addition, specific examples of the “ethylene polymer” in this modification are polyethylene, polyethylene glycol, or a copolymer of polyethylene and / or polyethylene glycol and other comonomer of 50 mol% or less. In addition, about polyethylene, the polyethylene manufactured by any manufacturing method of a high pressure method and a medium-low pressure method can also be used.

  By the way, the precursor solution of the present modification (second oxide dielectric precursor solution) includes one type of the above-described example of sorbitan fatty acid ester and one type of the above-described polymer having a vinyl group. Inclusion of any of the additives can form the thicker precursor layer 30b (and hence the oxide layer 30x described later) in a state in which cracking is unlikely to occur by a single coating using a coating method. Therefore, this is a preferred embodiment.

  Further, the amount of the additive that can be contained in the second oxide dielectric precursor solution is not particularly limited as long as it is soluble. However, from the viewpoint of controlling the uniformity of the film thickness when the film is formed by the coating method, the additive is 1 to 30 in terms of mass ratio when the precursor solution is 100. It is more preferable that the additive is 2 or more and 20 or less.

  In addition, the precursor solution (second oxide dielectric precursor solution) of the present embodiment can contain other substances as long as the effects of the present embodiment can be obtained.

  By employing the same manufacturing method as that of the oxide layer 30 of the first embodiment using the precursor layer starting from the second oxide dielectric precursor solution described above, bismuth (Bi) and niobium are used. As a result, an oxide dielectric layer (oxide layer 30x) including a BNNO oxide composed of (Nb) and nickel (Ni) (however, inevitable impurities may be included; the same shall apply hereinafter) is obtained. Note that the oxide layer 30x has a notable characteristic that cracking hardly occurs even when the oxide layer 30x is relatively thick (for example, more than 100 nm, more narrowly, 150 nm or more, and more narrowly, 170 nm or more). Yes.

  Thereafter, the upper electrode layer 40 is formed on the oxide layer 30x. Also in this modification, the upper electrode layer 40 is formed of platinum (Pt) as in the first embodiment. By forming the upper electrode layer 40, the thin film capacitor 100b shown in FIG. 10 is manufactured.

<Evaluation on presence or absence of cracks in oxide layer>
The present inventors conducted the following experiment in order to evaluate the presence or absence of cracks in the finally produced oxide layer 30x.

  Specifically, first, when the oxide layer 30x is formed, a layer of the second oxide dielectric precursor solution is formed by a single coating using a coating method. Thereafter, main firing is performed. In this experimental example, a film having a thickness of more than 60 nm and 600 nm or less is formed after the main baking.

  On the other hand, as a comparative example, using the precursor solution of the first embodiment in which the additive shown in this modification is not mixed at all, a method similar to the method for manufacturing the oxide layer 30 is used to exceed 60 nm. An oxide layer having a thickness of 200 nm or less was produced.

  As a result, the oxide layer (oxide dielectric layer) of this modification has an oxide thickness of more than 100 nm and less than 600 nm (more narrowly, more than 150 nm and less than 600 nm, and more narrowly more than 200 nm and less than 400 nm). Even when the physical layer was formed, no cracks were visually recognized. On the other hand, in the comparative example, cracks were visually recognized with a higher probability than in the case of the oxide layer 30x when the thickness exceeded 100 nm.

  Although the detailed mechanism is still unknown, the present inventors have caused stress concentration in the oxide layer 30x after the main firing by the additives mentioned in the present modification in the second oxide dielectric precursor solution. It is analyzed that it is difficult to occur or the stress is relaxed.

  Further, for example, when it is difficult to cause cracking by one coating (suppression or prevention of cracking) and a thickness exceeding 260 nm is desired (easiness of thickening), examples of the sorbitan fatty acid ester described above And at least one selected from the group of examples of polyoxyethylene ethers of the above-mentioned sorbitan fatty acid esters, and at least one selected from the group of examples of the above-mentioned polyvinyl polymers and examples of the above-mentioned ethylene polymers Are preferably mixed as additives.

  In addition, as a result of investigations by the present inventors, one of examples of polyoxyethylene ethers of sorbitan fatty acid esters was employed as an additive, and one of examples of polymers having a vinyl group was employed as an additive. It was confirmed that cracking can be prevented or suppressed more accurately than in the case. On the other hand, when one type of polymer having a vinyl group is used as an additive, the film thickness is increased compared to the case where one type of polyoxyethylene ether of a sorbitan fatty acid ester is used as an additive. It was confirmed that it was easy to realize. Accordingly, both the polymer having a vinyl group and the polyoxyethylene ether of sorbitan fatty acid ester can exert both effects of suppressing or preventing cracking and increasing the film thickness. It can be said that ethylene ether mainly contributes to suppression or prevention of cracks, and a polymer having a vinyl group mainly contributes to facilitation of thickening.

  As described above, according to this modification, an oxide dielectric that realizes a thick film that can highly reliably suppress or prevent the phenomenon of film breakage, and a solid-state electronic device (for example, a capacitor) including the oxide dielectric , A semiconductor device, or a microelectromechanical system).

<Second Embodiment>
In the present embodiment, a multilayer capacitor 200 that is an example of a solid-state electronic device will be described. Note that at least a part of the multilayer capacitor 200 is formed by a screen printing method. Of the materials forming the multilayer capacitor 200 in the present embodiment, the oxide composed of bismuth (Bi), niobium (Nb), and nickel (Ni) is the oxide layer 30 or the first in the first embodiment. This is the same as the oxide layer 30x in the modification of the embodiment. Therefore, the description which overlaps with 1st Embodiment and its modification example may be abbreviate | omitted.

[Structure of multilayer capacitor 200]
FIG. 11 is a schematic cross-sectional view showing the structure of the multilayer capacitor 200 in the present embodiment. As shown in FIG. 11, the multilayer capacitor 200 of the present embodiment partially includes a structure in which a total of five electrode layers and a total of four dielectric layers are alternately stacked. Further, in a portion where the electrode layers and the dielectric layers are not alternately stacked, the lower electrode layer (for example, the first-stage electrode layer 220a) and the upper electrode layer (for example, the fifth-stage electrode layer) Each electrode layer is formed so as to be electrically connected to the electrode layer 220e). The material or composition of each electrode layer 220a, 220b, 220c, 220d, 220e, and the material or composition of each of the oxide layers 230a, 230b, 230c, 230d, which are dielectric layers, are described in the multilayer capacitor of this embodiment described later. It is disclosed in the description of 200 manufacturing methods. In this embodiment, the BNNO oxide of the first embodiment will be described as a representative. However, the following manufacturing method is applied to the BNNO oxide shown in the modification of the first embodiment, and the BNNO oxide is used. One skilled in the art can fully appreciate that oxides can replace the first embodiment BNNO oxide.

  12 to 16 are schematic cross-sectional views illustrating one process of the method for manufacturing the multilayer capacitor 200. 12, FIG. 13, FIG. 14, FIG. 15, and FIG. 16 show a part of the structure of the multilayer capacitor 200 shown in FIG. 11 for convenience of explanation. Moreover, the display of the temperature in this application represents the preset temperature of the heater.

(1) Formation of First Stage Electrode Layer 220a In this embodiment, as shown in FIG. 12, first, as in the first embodiment, lanthanum (La) is formed on the substrate 10 by screen printing. A precursor solution containing a precursor containing nickel and a precursor containing nickel (Ni) as a solute (hereinafter referred to as an electrode layer precursor solution. The electrode layer precursor layer 221a is used as a starting material. Then, it heats to 80 degreeC or more and 450 degrees C or less for about 20 minutes as preliminary baking. This pre-baking is performed in an oxygen-containing atmosphere.

  In addition, the pre-baked gel is preferable for sufficiently evaporating the solvent (typically, the main solvent) in the electrode layer precursor layer 221a and exhibiting characteristics that enable future plastic deformation. A state (presumed to be a state in which organic chains remain before thermal decomposition) can be formed. From the viewpoint of realizing the above-mentioned viewpoint with higher accuracy, the pre-baking temperature is preferably 80 ° C. or higher and 450 ° C. or lower. As a result, a first electrode layer precursor layer 221a having a layer thickness of about 2 μm to about 3 μm is formed. It should be noted that not only the first-stage electrode layer 220a but also screen printing of each layer to be described later, adjusting the screen printability (viscosity, etc.) by using a known material (ethylcellulose, etc.) is appropriately employed. obtain.

  Thereafter, as the main baking, the first-layer electrode layer precursor layer 221a is heated to 580 ° C. for about 15 minutes in an oxygen atmosphere, so that lanthanum ( First-stage electrode layer oxide layer made of La) and nickel (Ni) (however, inevitable impurities may be included. The same applies hereinafter. Also referred to simply as “first-stage electrode layer”) 220a is formed. An electrode oxide layer (including not only the first-stage electrode oxide layer but also other electrode oxide layers) made of lanthanum (La) and nickel (Ni) is also called an LNO layer. .

  An example of a precursor containing lanthanum (La) for the first-stage electrode layer 220a in the present embodiment is lanthanum acetate. As other examples, lanthanum nitrate, lanthanum chloride, or various lanthanum alkoxides (for example, lanthanum isopropoxide, lanthanum butoxide, lanthanum ethoxide, lanthanum methoxyethoxide) may be employed. An example of a precursor containing nickel (Ni) for the first-stage electrode layer 220a in the present embodiment is nickel acetate. As other examples, nickel nitrate, nickel chloride, or various nickel alkoxides (for example, nickel isopropoxide, nickel butoxide, nickel ethoxide, nickel methoxyethoxide) may be employed.

  In addition, in the present embodiment, the first-stage electrode layer 220a made of lanthanum (La) and nickel (Ni) is employed, but the first-stage electrode layer 220a is not limited to this composition. For example, a first-stage electrode layer (however, inevitable impurities may be included; the same applies hereinafter) made of antimony (Sb) and tin (Sn) can also be employed. In this case, examples of the precursor containing antimony (Sb) include antimony acetate, antimony nitrate, antimony chloride, or various antimony alkoxides (for example, antimony isopropoxide, antimony butoxide, antimony ethoxide, antimony methoxyethoxide). Can be employed. Examples of the precursor containing tin (Sn) include tin acetate, tin nitrate, tin chloride, or various tin alkoxides (eg, tin isopropoxide, tin butoxide, tin ethoxide, tin methoxyethoxide). obtain. Alternatively, an oxide composed of indium (In) and tin (Sn) (however, inevitable impurities may be included; the same applies hereinafter) can also be employed. In that case, examples of the precursor containing indium (In) include indium acetate, indium nitrate, indium chloride, or various indium alkoxides (for example, indium isopropoxide, indium butoxide, indium ethoxide, indium methoxyethoxide). Can be employed. Moreover, the example of the precursor containing tin (Sn) is the same as the above-mentioned example.

(2) Formation of first-stage dielectric layer (oxide layer) 230a Thereafter, as shown in FIG. 14, bismuth (Bi) is formed on the substrate 10 and the first-stage electrode layer 220a by screen printing. ), A precursor containing niobium (Nb), and a precursor solution layer formed from a precursor solution having a precursor containing nickel (Ni) as a solute, a patterned precursor layer is formed. To do. Then, it heats to 80 degreeC or more and 450 degrees C or less for about 20 minutes as preliminary baking. This pre-baking is performed in an oxygen-containing atmosphere.

  In addition, the pre-baking allows the solvent (typically, the main solvent) in the precursor layer to evaporate sufficiently, and at the same time favorably develops a gel state (thermal decomposition) to develop characteristics that enable plastic deformation. It is considered that the organic chain remains in the front). From the viewpoint of realizing the above-mentioned viewpoint with higher accuracy, the pre-baking temperature is preferably 80 ° C. or higher and 250 ° C. or lower. In this embodiment, in order to obtain a sufficient thickness (for example, about 2 μm to about 3 μm) of the oxide layer 230a that is a dielectric layer, the precursor layer is formed and pre-fired by the above-described screen printing method.

  Thereafter, as a heating step for the main firing, the precursor layer of the oxide layer 230a is heated at 750 ° C. in an oxygen atmosphere for a predetermined time (for example, about 20 minutes), as shown in FIG. A patterned oxide layer (oxide layer 230a) made of bismuth (Bi), niobium (Nb), and nickel (Ni) is formed on the substrate 10 and the first electrode layer 220a. Here, by performing the main baking under the above-described conditions, or by performing the main baking and the post-annealing treatment shown in the first embodiment, extremely low dielectric loss while maintaining a high relative dielectric constant. It is possible to manufacture the oxide layer 230a that can realize the above value.

(3) Formation of second and subsequent electrode layers and dielectric layer Thereafter, the manufacturing process of the electrode layer (first electrode layer 220a) and the oxide layer 230a which is the dielectric layer described so far , Electrode layers and dielectric layers patterned by a screen printing method are alternately stacked.

  Specifically, after the first-stage oxide layer 230a is patterned, the second-stage electrode layer patterned by the screen printing method on the oxide layer 230a and the first-stage electrode layer 220a. The precursor layer for forming is formed in the same manner as the first-layer electrode layer precursor layer 221a. Thereafter, as shown in FIG. 15, a patterned second-stage electrode layer 220b is formed.

  Further, as shown in FIG. 16, the second-stage dielectric layer patterned by screen printing on the second-stage electrode layer 220b and the first-stage dielectric layer 230a. A body layer 230b is formed.

  In this way, by laminating alternately patterned electrode layers and dielectric layers by screen printing, a multilayer capacitor 200 as shown in FIG. 11 is finally manufactured.

  As described above, the multilayer capacitor 200 of this embodiment is notable for the fact that each electrode layer and each dielectric layer (oxide layer) are each formed of a metal oxide. In addition, in this embodiment, since each electrode layer and each dielectric layer (oxide layer) are formed by heating various precursor solutions in an oxygen-containing atmosphere, compared with the conventional method. Therefore, the area can be easily increased, and the industrial property or mass productivity can be remarkably improved.

  It is to be understood by those skilled in the art that, by knowing the contents of the present application, the above-described electrode layer and dielectric layer (oxide layer) formation steps can be repeated in an alternating manner so as to be stacked upward. You can understand.

<Third Embodiment>
1. Overall Configuration of Thin Film Capacitor of this Embodiment In this embodiment, embossing is performed in the formation process of all layers of a thin film capacitor that is an example of a solid-state electronic device. The overall configuration of a thin film capacitor 300, which is an example of a solid-state electronic device in the present embodiment, is shown in FIG. In the present embodiment, the lower electrode layer, the oxide layer, and the upper electrode layer are the same as those in the first embodiment except that the embossing process is performed. Therefore, the description which overlaps with 1st Embodiment is abbreviate | omitted.

  As shown in FIG. 17, the thin film capacitor 300 of this embodiment is formed on the substrate 10 as in the first embodiment or its modification. The thin film capacitor 300 includes a lower electrode layer 320 from the substrate 10 side, and an oxide layer 330 made of an oxide of bismuth (Bi), niobium (Nb), and nickel (Ni) (provided that inevitable impurities are added). The same applies to the following), and an upper electrode layer 340.

2. Manufacturing Process of Thin Film Capacitor 300 Next, a manufacturing method of the thin film capacitor 300 will be described. FIGS. 18 to 23 and FIGS. 26 to 28 are cross-sectional schematic views showing one process of the method of manufacturing the thin film capacitor 300, respectively. In manufacturing the thin film capacitor 300, first, the lower electrode layer 320 that has been embossed is formed on the substrate 10. Next, an oxide layer 330 that has been embossed is formed on the lower electrode layer 320. Thereafter, an upper electrode layer 340 that is embossed on the oxide layer 330 is formed. Also in the manufacturing process of the thin film capacitor 300, the description which overlaps with 1st Embodiment or its modification is abbreviate | omitted.

(1) Formation of Lower Electrode Layer In this embodiment, an example in which the lower electrode layer 320 of the thin film capacitor 300 is formed of a conductive oxide layer made of lanthanum (La) and nickel (Ni) will be described. The lower electrode layer 320 is formed in the order of (A) formation of a precursor layer and preliminary baking, (B) stamping process, and (C) main baking process.

(A) Precursor layer formation and pre-baking step First, a lower part having a lanthanum (La) -containing precursor and nickel (Ni) -containing precursor as solutes on the substrate 10 by a known spin coating method. A lower electrode layer precursor layer 320a is formed using the electrode layer precursor solution as a starting material.

  Thereafter, as preliminary firing, the lower electrode layer precursor layer 320a is heated in a temperature range of 80 ° C. or higher and 250 ° C. or lower for a predetermined time in an oxygen-containing atmosphere. Moreover, the desired thickness of the lower electrode layer 320 can be obtained by repeating the formation and preliminary baking of the lower electrode layer precursor layer 320a by the spin coating method described above a plurality of times.

(B) Embossing Next, in order to perform patterning of the precursor layer 320a for the lower electrode layer, as shown in FIG. 18, in the state heated within the range of 80 ° C. or higher and 300 ° C. or lower, Using the mold M1, embossing is performed at a pressure of 0.1 MPa to 40 MPa. Examples of the heating method in the embossing process include a method of bringing the substrate into a predetermined temperature atmosphere by using a chamber, an oven, or the like, a method of heating the base on which the substrate is placed from below, or a temperature of 80 ° C. or more and 300 ° C. The following is a method of embossing using a heated mold. In this case, it is more preferable in terms of workability to use in combination the method of heating the base with a heater from the bottom and the method of using a mold heated in advance to 80 ° C. or more and 300 ° C. or less.

  The reason why the heating temperature of the mold is set to 80 ° C. or more and 300 ° C. or less is as follows. When the heating temperature during the embossing process is lower than 80 ° C., the plastic deformation ability of the lower electrode layer precursor layer 320a is reduced due to the lower temperature of the lower electrode layer precursor layer 320a. Therefore, the feasibility of molding at the time of molding the embossed structure, or the reliability or stability after molding becomes poor. Further, when the heating temperature during the stamping process exceeds 300 ° C., the decomposition (oxidative thermal decomposition) of the organic chain, which is the source of the plastic deformability, proceeds, so that the plastic deformability decreases. Furthermore, from the above viewpoint, it is a more preferable aspect that the precursor layer 320a for the lower electrode layer is heated within a range of 100 ° C. or more and 250 ° C. or less during the embossing process.

  Further, if the pressure in the die pressing process is a pressure in the range of 0.1 MPa to 40 MPa, the lower electrode layer precursor layer 320a is deformed following the surface shape of the die, and a desired die The push structure can be formed with high accuracy. In addition, the pressure applied when embossing is performed is set to a low pressure range of 0.1 MPa to 40 MPa (particularly, 20 MPa or less). As a result, it is difficult for the mold to be damaged when the stamping process is performed, and it is advantageous for increasing the area.

  Thereafter, the entire lower electrode layer precursor layer 320a is etched. As a result, as shown in FIG. 19, the lower electrode layer precursor layer 320a is completely removed from the region other than the region corresponding to the lower electrode layer (etching process for the entire surface of the lower electrode layer precursor layer 320a).

  Further, in the above-described embossing process, in advance, a mold release treatment for the surface of each precursor layer that will be brought into contact with the stamping surface and / or a mold release treatment for the die pressing surface of the mold is performed. It is preferable that an embossing process is performed on each precursor layer. By applying such treatment, the frictional force between each precursor layer and the mold can be reduced, so that each precursor layer can be embossed with higher accuracy. It becomes. Examples of the release agent that can be used for the release treatment include surfactants (for example, fluorine surfactants, silicon surfactants, nonionic surfactants, etc.), fluorine-containing diamond-like carbon, and the like. can do.

(C) Main baking Next, main baking is performed in air | atmosphere with respect to the precursor layer 320a for lower electrode layers. The heating temperature during the main baking is not less than 550 ° C. and not more than 650 ° C. As a result, as shown in FIG. 20, a lower electrode layer 320 (however, inevitable impurities may be included. The same applies hereinafter) made of lanthanum (La) and nickel (Ni) is formed on the substrate 10.

(2) Formation of Oxide Layer that Becomes Dielectric Layer Next, an oxide layer 330 that becomes a dielectric layer is formed on the lower electrode layer 320. The oxide layer 330 is formed in the order of (A) precursor layer formation and preliminary firing step, (B) embossing step, and (C) main firing step. 21 to 24 are views showing a process of forming the oxide layer 330. FIG.

(A) Formation and pre-baking of oxide precursor layer made of bismuth (Bi), niobium (Nb) and nickel (Ni) As shown in FIG. 21, on the substrate 10 and the patterned lower electrode layer 320, Similarly to the first embodiment or the modification thereof, a precursor layer 330a composed of the following precursor solution layers is formed.

  Specifically, the precursor solution for the dielectric layer of this embodiment includes a precursor containing bismuth (Bi), a precursor containing niobium (Nb), and a precursor containing nickel (Ni) as a solute. A precursor solution.

  Thereafter, in the present embodiment, preliminary firing is performed in an oxygen-containing atmosphere while being heated to 80 ° C. or higher and 250 ° C. or lower. According to the study by the present inventors, in this embodiment, the precursor layer 330a is heated within the range of 80 ° C. or higher and 250 ° C. or lower, so that the plastic deformation capability of the precursor layer 330a is increased. It was revealed that the solvent (typically, the main solvent) can be sufficiently removed.

(B) Embossing process In this embodiment, as shown in FIG. 22, an embossing process is performed with respect to the precursor layer 330a which performed only preliminary baking. Specifically, in order to perform patterning of the oxide layer, embossing is performed at a pressure of 0.1 MPa or more and 40 MPa or less using the dielectric layer mold M2 while being heated to 80 ° C. or more and 250 ° C. or less. Is done.

  Thereafter, the entire surface of the precursor layer 330a is etched. As a result, as shown in FIG. 23, the precursor layer 330a is completely removed from regions other than the region corresponding to the oxide layer 330 (etching process for the entire surface of the precursor layer 330a). In addition, although the etching process of the precursor layer 330a of this embodiment was performed using the wet etching technique which does not use a vacuum process, it does not prevent etching using what is called dry etching technique using plasma. .

(C) Main baking Thereafter, the precursor layer 330a is main-fired in the same manner as the oxide 30 of the first embodiment and its modification. And if necessary, the post-annealing process shown in the first embodiment is additionally performed. As a result, as shown in FIG. 24, an oxide layer (oxide dielectric layer) 330 to be a dielectric layer is formed on the lower electrode layer 320. As a heating step for the main firing, the precursor layer 330a is heated in an oxygen atmosphere for a predetermined time (for example, about 20 minutes) at 600 ° C. or higher and 800 ° C. or lower.

  Here, by performing the main baking under the above-described conditions, or by performing the main baking and the post-annealing treatment shown in the first embodiment, extremely low dielectric loss while maintaining a high relative dielectric constant. An oxide layer 330 that can achieve this value can be manufactured.

  Although the etching process for the entire surface of the precursor layer 330a can be performed after the main baking, as described above, the precursor layer is entirely etched between the embossing process and the main baking process. It is a more preferable aspect that the process is included. This is because the precursor layers in unnecessary regions can be removed more easily than etching after each precursor layer is subjected to main firing.

<Evaluation of shape of oxide dielectric layer in stamping>
Here, the present inventors investigated the moldability and dimensional accuracy of the oxide dielectric obtained by embossing the precursor layer 330a of the present embodiment in a heated state.

  FIG. 25 shows an optical microscope of an oxide layer (oxide dielectric layer) obtained by embossing the precursor layer 330a of the present embodiment after the processing (after the main firing at 750 ° C.). It is an observation photograph (plan view) by. “P” in FIG. 25 indicates an example of the widths of a plurality of types (15 μm width and 25 μm width) of the BNNO oxide layer formed by the embossing process.

  As a result, as shown in FIG. 25, it was confirmed that the oxide dielectric layer (BNNO oxide layer) subjected to the embossing process of this embodiment is excellent in formability and dimensional accuracy.

(3) Formation of upper electrode layer Thereafter, a precursor containing lanthanum (La) and a precursor containing nickel (Ni) are formed on the oxide layer 330 in the same manner as the lower electrode layer 320 by a known spin coating method. A precursor layer 340a for the upper electrode layer is formed using a precursor solution as a solute as a starting material. Thereafter, preliminary firing is performed by heating the precursor layer 340a for the upper electrode layer in an oxygen-containing atmosphere in a temperature range of 80 ° C. to 250 ° C.

  Subsequently, as shown in FIG. 26, in order to perform the patterning of the precursor layer 340a for the upper electrode layer that has been pre-baked, the precursor layer 340a for the upper electrode layer is heated to 80 ° C. or higher and 300 ° C. or lower. Using the upper electrode layer mold M3, the upper electrode layer precursor layer 340a is embossed at a pressure of 0.1 MPa to 40 MPa. Thereafter, the entire upper electrode layer precursor layer 340a is etched to completely remove the upper electrode layer precursor layer 340a from the region other than the region corresponding to the upper electrode layer 340, as shown in FIG.

  Then, as shown in FIG. 28, as the main firing, the upper electrode layer precursor layer 340a is heated to 520 ° C. to 600 ° C. for a predetermined time in an oxygen atmosphere, thereby being formed on the oxide layer 330. An upper electrode layer 340 made of lanthanum (La) and nickel (Ni) (however, it may contain inevitable impurities; the same applies hereinafter) is formed.

  By the way, the thin film capacitor 300 of this embodiment includes a lower electrode layer 320, an oxide layer 330 that is an insulating layer, and an upper electrode layer 340 on the substrate 10 from the substrate 10 side. In addition, each layer described above is embossed by embossing. As a result, a process using a relatively long time and / or expensive equipment such as a vacuum process, a process using a photolithography method, or an ultraviolet irradiation process becomes unnecessary. In addition, both the electrode layer and the oxide layer can be easily patterned. Therefore, the thin film capacitor 300 of this embodiment is extremely excellent in industrial property or mass productivity.

  As a modification of the present embodiment, on the substrate 10, a lower electrode layer precursor layer 320a that is a precursor layer of the lower electrode layer 320, a precursor layer 330a that is a precursor layer of the oxide layer 330, and It is also an aspect that can be adopted in which after the laminated body of the upper electrode layer precursor layer 340a, which is the precursor layer of the upper electrode layer 340, is formed, the laminated body is embossed. Thereafter, main firing is performed. If such a method is employed, in this embodiment, unlike the thin film capacitor 300, it is not possible to form individual stamping structures for each layer alone, but it is possible to reduce the number of stamping processes. Become.

<Other embodiment (1)>
Moreover, the oxide layer in each of the above-described embodiments is suitable for various solid-state electronic devices that control a large current with a low driving voltage, for example. The solid-state electronic device provided with the oxide layer in each of the above-described embodiments can be applied to many devices other than the above-described thin film capacitor. For example, various capacitors such as variable capacitance thin film capacitors, semiconductor devices such as metal oxide semiconductor junction field effect transistors (MOSFETs) and nonvolatile memories, or MEMS such as micro TAS (Total Analysis System), micro chemical chips, DNA chips, etc. The oxide layer in each of the above embodiments can be applied to a device of a microelectromechanical system typified by (microelectromechanical system) or NEMS (nanoelectromechanical system), a high-frequency filter, a patch antenna, or RCL. In addition, the solid-state electronic device as a composite device including at least two types selected from the group of capacitors, high-frequency filters, patch antennas, semiconductor devices, microelectromechanical systems, and RCLs is also oxidized in the above-described embodiments. A physical layer can also be applied.

  Hereinafter, a structure of a thin film transistor 400 which is an example of a solid-state electronic device will be described.

<Overall Configuration of Thin Film Transistor of this Embodiment>
FIG. 29 is a diagram illustrating an overall configuration of the thin film transistor 400. As shown in FIG. 29, in the thin film transistor 400 in this embodiment, a lower electrode layer (gate electrode) 320, an oxide layer (gate insulating layer) 330, a channel 444, a source electrode 458, The drain electrodes 456 are stacked in this order. Since the manufacturing method of the lower electrode layer (gate electrode) 320 and the oxide layer (gate insulating layer) 330 is the same as those manufacturing method of the third embodiment, the description thereof is omitted.

  Although the thin film transistor 400 employs a so-called bottom gate structure, the present embodiment is not limited to this structure. Further, as in the first embodiment, in order to simplify the drawing, description of patterning of the extraction electrode from each electrode is omitted.

  The channel 444 of this embodiment is made of a channel oxide containing indium (In), zinc (Zn), and zirconium (Zr). In the present embodiment, other known channel materials can also be used. A thin film transistor in which the thickness of the channel 444 is greater than or equal to 5 nm and less than or equal to 80 nm, and the thickness of the channel 444 is greater than or equal to 5 nm and less than or equal to 80 nm is highly accurate and covers the oxide layer (gate insulating layer). This is a preferred embodiment from the viewpoint of facilitating modulation.

  Further, the source electrode 458 and the drain electrode 456 of the present embodiment are made of ITO (Indium Tin Oxide).

  Further, in the thin film transistor 400 which is an example of a solid-state electronic device, an oxide layer made of bismuth (Bi), niobium (Nb), and nickel (Ni) is used as an insulating layer that plays a role other than the oxide layer (gate insulating layer) 330. Or an oxide composed of bismuth (Bi) and niobium (Nb) can also be used.

<Other embodiment (2)>
Moreover, in the aspect which gave the die-pressing process among the above-mentioned embodiments, the pressure at the time of the die-pressing process was set within the range of “0.1 MPa to 40 MPa” for the following reason. First, if the pressure is less than 0.1 MPa, the pressure may be too low to emboss each precursor layer. On the other hand, if the pressure is 40 MPa, the precursor layer can be sufficiently embossed, so that it is not necessary to apply more pressure. From the above viewpoint, it is more preferable that the embossing process is performed at a pressure within a range of 0.1 MPa to 20 MPa.

  As described above, the disclosure of each of the embodiments described above is described for explaining the embodiments, and is not described for limiting the present invention. In addition, modifications within the scope of the present invention including other combinations of the embodiments are also included in the scope of the claims.

10 Substrate 20, 320 Lower electrode layer 30, 30x, 230a, 230b, 230c, 230d, 330 Oxide layer (oxide dielectric layer)
30a, 330a Precursor layer 340a Upper electrode layer precursor layer 40, 340 Upper electrode layer 100a, 100b, 300 Thin film capacitor as an example of solid state electronic device 200 Multilayer capacitor 220a, 220b, 220c as an example of solid state electronic device 220d, 220e Electrode layer 221a Precursor layer for electrode layer 320a Precursor layer for lower electrode layer 400 Thin film transistor which is an example of solid state electronic device 444 Channel 456 Drain electrode 458 Source electrode M1 Lower electrode layer type M2 Dielectric layer type M3 Mold for upper electrode layer

Claims (12)

Precursor layer formation in which a precursor solution layer comprising a precursor solution containing bismuth (Bi), niobium (Nb), and nickel (Ni) is used as a solute. Process,
Oxide (inevitable impurities) composed of bismuth (Bi), niobium (Nb), and nickel (Ni) having a crystal phase of a pyrochlore crystal structure by heat treatment in which the precursor solution layer is heated in an oxygen-containing atmosphere. An oxide dielectric layer forming step of forming an oxide dielectric layer comprising:
A method for manufacturing an oxide dielectric. The precursor solution further contains at least one selected from the group of sorbitan fatty acid esters, polyoxyethylene ethers of sorbitan fatty acid esters, polyvinyl polymers, and ethylene polymers,
The method for producing an oxide dielectric according to claim 1. The precursor solution further comprises at least one selected from the group of sorbitan fatty acid esters and polyoxyethylene ethers of the sorbitan fatty acid esters, and at least one selected from the group of polyvinyl polymers and ethylene polymers. contains,
The method for producing an oxide dielectric according to claim 1. In the precursor layer forming step, when the precursor solution layer is formed by one application on or above the substrate,
The thickness of the oxide dielectric layer after the heat treatment in the oxide dielectric layer forming step is greater than 100 nm.
The method for producing an oxide dielectric according to claim 2 or claim 3. Before forming the oxide dielectric layer, the precursor solution layer is embossed in a state in which the precursor solution layer is heated at 80 ° C. to 250 ° C. in an oxygen-containing atmosphere. Structure is formed,
The manufacturing method of the oxide dielectric of any one of Claim 1 thru | or 4. A step of manufacturing a solid-state electronic device including the oxide dielectric layer formed by the method for manufacturing the oxide dielectric according to any one of claims 1 to 5.
Manufacturing method of solid-state electronic device. An oxide of bismuth (Bi), niobium (Nb) and nickel (Ni) having a crystal phase of a pyrochlore type crystal structure (which may include inevitable impurities);
When the number of atoms of the niobium (Nb) is 1, the number of atoms of the bismuth (Bi) is 1.2 or more and 1.9 or less, and the number of atoms of the nickel (Ni) is 0.25 or more and 0. .75 or less,
Oxide dielectric. An oxide of bismuth (Bi), niobium (Nb) and nickel (Ni) having a crystal phase of a pyrochlore type crystal structure (which may include inevitable impurities);
When the number of atoms of the niobium (Nb) is 1, the number of atoms of the bismuth (Bi) is 0.8 or more and less than 1.2, and the number of atoms of the nickel (Ni) is 0.25 or more and 0.00. 75 or less and the relative dielectric constant at 25 ° C. is higher than 135.
Oxide dielectric. An oxide of bismuth (Bi), niobium (Nb) and nickel (Ni) having a crystal phase of a pyrochlore type crystal structure (which may include inevitable impurities);
When the number of atoms of the niobium (Nb) is 1, the number of atoms of the bismuth (Bi) is 0.5 or more and less than 0.7, and the number of atoms of the nickel (Ni) is 0.05 or more and 0. .25,
Oxide dielectric. A precursor solution containing a precursor containing bismuth (Bi), a precursor containing niobium (Nb), and a precursor containing nickel (Ni) as a solute;
Oxide dielectric precursor solution. Sorbitan fatty acid ester, polyoxyethylene ether of sorbitan fatty acid ester, polyvinyl polymer, and at least one selected from the group of ethylene polymers, further containing,
The oxide dielectric precursor solution according to claim 10. And further comprising at least one selected from the group of sorbitan fatty acid esters and polyoxyethylene ethers of the sorbitan fatty acid esters, and at least one selected from the group of polyvinyl polymers and ethylene polymers,
The oxide dielectric precursor solution according to claim 10.