JP2015067475A - Oxide dielectric, method of producing the dielectric, precursor for oxide dielectric, solid electronic device and method of producing the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide dielectric having excellent characteristics, a solid electronic device provided with the oxide dielectric, e.g. a high-frequency filter, a patch antennas, a capacitor, a semiconductor device or a micro-electromechanical system.SOLUTION: An oxide layer 30 composed of an oxide dielectric contains an oxide which has a crystalline phase of a pyrochlore crystal structure and comprises bismuth(Bi), niobium(Nb) and optionally unavoidable impurities, and, with the atomic number of bismuth(Bi) as 1, the atomic number of niobium(Nb) is 1.3 or more and 1.7 or less.

Description

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

Conventionally, oxide layers composed of various compositions having functionality have been developed. In addition, 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. In addition, BiNbO ₄ has been developed as an oxide layer that does not contain Pb and can be fired at a relatively low temperature as a dielectric material used in a 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). Further, the patent literature also discloses an oxide layer composed of bismuth (Bi) and niobium (Nb) having a relative dielectric constant of 60 or more (maximum 180) at 1 KHz. Patent Documents 1 and 2).

International Publication No. WO2013 / 066940 International Publication No. WO2013 / 069471

Effect of phase transition on the microwave selective properties of BiNbO4, Eung So Kim Kim, Wong Choi, Journal of the Europe 26

  However, even if an oxide composed of bismuth (Bi) and niobium (Nb) having a relatively high dielectric constant is obtained, in order to enhance the performance of a solid-state electronic device such as a capacitor, a semiconductor device, or a microelectromechanical system. Therefore, a relative dielectric constant exceeding the conventionally disclosed numerical value is required. In addition, it can be said that this is an important technical problem that should be realized in improving electrical characteristics (for example, including dielectric loss (tan δ)). Various solid-state electronic devices are steadily being reduced in size and weight, and in particular, the reduction in size and weight of capacitors or capacitors (hereinafter collectively referred to as “capacitors”) is strongly demanded by the industry. .

  In order to realize the reduction in size and weight of the capacitor, it is necessary to achieve a high dielectric constant at the same time as making the dielectric film thinner. However, it is extremely difficult to realize a thin dielectric film and a high dielectric constant while ensuring the reliability of the capacitor or the dielectric film.

  In addition, in a composite device including at least two of a high-frequency filter, a patch antenna, a semiconductor device, a microelectromechanical system, or an RCL, which is an example of another solid-state electronic device, while being reduced in size and weight, For example, improvement in frequency characteristics is required.

  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 a solid electronic device, which is not preferable from the viewpoint of industriality or mass productivity. In addition, there is a problem in the prior art that it is relatively difficult to increase the area.

  The inventions filed by the present inventors so far propose several solutions for the above-mentioned technical problems in the prior art, but the realization of a high-performance and highly reliable solid-state electronic device is still halfway. .

  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”). Alternatively, the manufacturing process of such a solid-state electronic device can be simplified and energy can be saved. As a result, the present invention greatly contributes to the provision of an oxide dielectric excellent in industriality or mass productivity and a solid-state electronic device including the oxide dielectric.

  The inventors of the present application have conducted intensive research and analysis on selection of an oxide that can appropriately function as a dielectric in a solid-state electronic device from among a large number of oxides and a manufacturing method thereof. As a result of detailed analysis and examination by the inventors and many trials and errors, oxides composed of bismuth (Bi) and niobium (Nb) having a high relative dielectric constant are characterized by their characteristic composition ratio. It has been clarified that it is possible to exhibit very high performance by forming the oxide so as to be within the range of the above. Furthermore, the inventors are able to manufacture a dielectric with higher accuracy and higher performance by actively utilizing this characteristic range of the composition ratio in a part of the manufacturing process of the oxide dielectric. I found out.

  Further, the 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 dielectric. In addition, the inventors have also found that the oxide layer can be patterned by an inexpensive and simple method using a “embossing” processing method called “nanoimprint”. As a result, the inventors have realized the formation of the oxide dielectric, and consequently the formation of the oxide dielectric by a process that is greatly simplified or energy-saving compared to the conventional technology and easy to increase in area as well as realizing a high-performance oxide. It has been found that it is possible to manufacture a solid-state electronic device provided with the oxide dielectric. The present invention has been created based on the above viewpoints.

  One oxide dielectric of the present invention may include an oxide (inevitable impurities) of bismuth (Bi) and niobium (Nb) having a crystal phase of a pyrochlore-type crystal structure. The same.) Further, in this oxide dielectric, when the number of atoms of bismuth (Bi) is 1, the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less.

By providing a crystal phase having a pyrochlore type crystal structure, this oxide dielectric can have a very high relative dielectric constant (typically 220 or more) as compared with the prior art. According to detailed analysis by the inventors, the relative dielectric constant produced by the crystal phase of the pyrochlore type crystal structure is much higher than that of the conventional crystal structure (for example, the known β-BiNbO ₄ crystal structure). It became clear. Based on this knowledge, as described above, when the number of atoms of bismuth (Bi) is 1 in an oxide composed of bismuth (Bi) and niobium (Nb) (hereinafter also referred to as “BNO oxide”). A specific composition ratio in which the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less is selected. With this characteristic composition ratio, the crystal phase of the pyrochlore crystal structure is expressed with higher accuracy. Therefore, it is worthy of special mention that this oxide dielectric can positively develop a crystal phase of a pyrochlore crystal structure. Further, the oxide dielectric not only realizes a very high dielectric constant but also can exhibit excellent electrical characteristics (for example, dielectric loss (tan δ)). Therefore, the electrical characteristics of various solid-state electronic devices can be improved by using the above-described oxide dielectric.

  Further, in the method for producing one oxide dielectric according to the present invention, when the precursor containing bismuth (Bi) and the number of atoms of bismuth (Bi) are 1, the number of atoms of niobium (Nb) is A precursor starting from a precursor solution having a precursor containing niobium (Nb) of 1.3 to 1.7 as a solute is 520 ° C. or higher and 620 ° C. or lower in an oxygen-containing atmosphere. By heating at a temperature, when the number of atoms of the bismuth (Bi) and the niobium (Nb) is 1 and the number of atoms of the bismuth (Bi) is 1, the number of atoms of the niobium (Nb) is 1 And a step of forming an oxide dielectric (which may include inevitable impurities) including a crystal phase of a pyrochlore crystal structure that is 3 or more and 1.7 or less.

According to this method for manufacturing an oxide dielectric, it is possible to manufacture an oxide dielectric having a crystal phase of a pyrochlore crystal structure that can exhibit a very high relative dielectric constant (typically 220 or more). it can. As described above, according to the detailed analysis by the inventors, the relative dielectric constant generated by the crystal phase of the pyrochlore type crystal structure is significantly higher than that of the conventional crystal structure (for example, the known β-BiNbO ₄ crystal structure). It became clear to show a high value. Based on this knowledge, as described above, when the precursor containing bismuth (Bi) and the number of atoms of bismuth (Bi) are set to 1, the number of atoms of niobium (Nb) is 1.3 or more and 1.7. A precursor starting from a precursor solution having the following niobium (Nb) -containing precursor as a solute is selected. By adopting a precursor having such a composition ratio, when the number of atoms of bismuth (Bi) is 1 in an oxide composed of bismuth (Bi) and niobium (Nb), the accuracy is increased. An oxide dielectric having a specific composition ratio in which the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less is manufactured. And, by this characteristic composition ratio, the crystal phase of the pyrochlore type crystal structure is expressed with higher accuracy. Therefore, it is worthy of special mention that according to this oxide dielectric manufacturing method, it is possible to positively develop a crystal phase of a pyrochlore crystal structure. In addition, according to this method of manufacturing an oxide dielectric, an oxide dielectric that not only achieves a very high dielectric constant but also exhibits excellent electrical characteristics (for example, dielectric loss (tan δ)) is manufactured. can do. Therefore, by using the above-described oxide dielectric manufacturing method, it is possible to improve electrical characteristics of various solid-state electronic devices including the oxide dielectric.

  Further, in this oxide dielectric manufacturing method, an oxide layer is formed by a relatively simple process that does not use a photolithography method (for example, an inkjet method, a screen printing method, an intaglio / letter printing method, or a nanoimprint method). obtain. 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 this oxide layer is excellent in industrial property or mass productivity.

  Further, one oxide dielectric precursor of the present invention is an oxide precursor composed of bismuth (Bi) and niobium (Nb) having a pyrochlore crystal structure, and the bismuth ( When the precursor containing Bi) and the number of atoms of bismuth (Bi) are set to 1, the niobium (Nb) having the above-mentioned number of niobium (Nb) of 1.3 to 1.7. A precursor containing it is mixed as a solute.

  According to this oxide dielectric precursor, when the number of atoms of bismuth (Bi) is 1 in an oxide composed of bismuth (Bi) and niobium (Nb), the niobium (Nb) ) Is produced with an oxide dielectric having a specific composition ratio of 1.3 to 1.7. And, by this characteristic composition ratio, the crystal phase of the pyrochlore type crystal structure is expressed with higher accuracy. Therefore, this oxide dielectric precursor is a precursor that positively develops a crystal phase of a pyrochlore crystal structure in the oxide dielectric. In addition, the oxide dielectric formed from the precursor of the oxide dielectric not only realizes a very high dielectric constant but also can exhibit excellent electrical characteristics (for example, dielectric loss (tan δ)). Therefore, by using the above-described oxide dielectric precursor, it is possible to improve the electrical characteristics of various solid-state electronic devices including the oxide dielectric formed from the precursor.

  In the present application, “in an oxygen-containing atmosphere” means in an oxygen atmosphere or in the air. In the present application, the value of tan δ is treated as a numerical value representative of dielectric loss.

  Further, in each of the above-mentioned inventions, at present, the mechanism or the reason why the crystal phase of the pyrochlore type crystal structure can be expressed in the BNO oxide has not been clarified. However, it has been confirmed that this interesting heterogeneity provides electrical properties that have never been obtained.

  Moreover, in each of the above-described inventions, the above-described oxide further has an amorphous phase of an oxide composed of bismuth (Bi) and niobium (Nb) as compared with the case of only an aggregate of fine crystal grains. This is a preferred embodiment from the viewpoint of preventing the deterioration or variation in electrical characteristics due to the formation of unnecessary grain boundaries with high accuracy.

  According to one oxide dielectric of the present invention, it has an extremely high relative dielectric constant (typically 220 or more) as compared with the conventional one and has excellent electrical characteristics (for example, dielectric loss (tan δ)). Therefore, it is possible to improve the electrical characteristics of various solid-state electronic devices.

  In addition, according to the manufacturing method of one oxide dielectric of the present invention, it has an extremely high relative dielectric constant (typically 220 or more) as compared with the conventional one, and has excellent electrical characteristics (for example, dielectric). An oxide dielectric that can also exhibit loss (tan δ)) can be manufactured. Moreover, this oxide dielectric manufacturing method is excellent in industrial property or mass productivity.

  Furthermore, one oxide dielectric precursor of the present invention is a precursor in which the crystal phase of the pyrochlore crystal structure is expressed with higher accuracy in the oxide dielectric. Therefore, by using this oxide dielectric precursor, not only a very high dielectric constant but also an excellent dielectric property (for example, dielectric loss (tan δ)) can be exhibited. Can be formed.

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 1st Embodiment of this invention. It is the observation result by the cross-sectional TEM (Transmission Electron Microscopy) photograph and electron beam diffraction image of the thin film capacitor in the 1st Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 1st Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 1st Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 1st Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 1st Embodiment of this invention. In the first embodiment of the present invention, a precursor solution is prepared so that the number of atoms of niobium (Nb) is 1.5 when the number of atoms of bismuth (Bi) is 1, and at 550 ° C. It is a graph which shows the dielectric constant and dielectric loss (tan-delta) of this oxide layer when an oxide layer is formed by heating. In the first embodiment of the present invention, a precursor solution was prepared so that the number of atoms of niobium (Nb) was 1.5 when the number of atoms of bismuth (Bi) was 1, and at 600 ° C. 7 is a graph corresponding to FIG. 6 when an oxide layer is formed by heating. In the first embodiment of the present invention, when the number of atoms of bismuth (Bi) is 1, the precursor solution is prepared so that the number of atoms of niobium (Nb) is 1.5, and 550 ° C. It is a measurement result of the X-ray diffraction (XRD) which shows the crystal structure of this oxide layer when it heats at 600 degreeC and an oxide layer is formed. When the number of atoms of bismuth (Bi) is 1, the precursor solution is prepared so that the number of atoms of niobium (Nb) is 1, and the oxide layer is formed by heating at 550 ° C. or 600 ° C. It is a measurement result of the X-ray diffraction (XRD) which shows the crystal structure of this oxide layer in the case of. 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 2nd Embodiment of this invention. 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 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 3rd Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 4th Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 4th Embodiment of this invention. It is a cross-sectional schematic diagram which shows one process of the manufacturing method of the thin film capacitor in the 4th Embodiment of this invention. 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 4th Embodiment of this invention.

  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. FIG. 1 is a diagram showing an overall configuration of a thin film capacitor 100 that is an example of a solid-state electronic device according to the present embodiment. As shown in FIG. 1, a thin film capacitor 100 is formed on a substrate 10 from the substrate 10 side, a lower electrode layer 20 and an oxide dielectric layer (hereinafter also referred to as “oxide layer” for short. The same applies hereinafter). 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, an STO (SrTiO) layer on the surface of the Si substrate via an SiO ₂ layer and a Ti layer. Various insulating base materials can be used including a semiconductor substrate (eg, Si substrate, SiC substrate, Ge substrate, etc.).

  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. .

  In the present embodiment, the oxide dielectric layer (oxide layer 30) is a precursor starting from a precursor solution containing a precursor containing bismuth (Bi) and a precursor containing niobium (Nb) as a solute. The body is formed by heating in an oxygen-containing atmosphere (hereinafter, the production method according to this step is also referred to as “solution method”). As the solute in the precursor solution in this embodiment, when the number of atoms of bismuth (Bi) in the precursor containing bismuth (Bi) is 1, the number of niobium (Nb) atoms is 1.3. The number of atoms of bismuth (Bi) and the number of atoms of niobium (Nb) are adjusted so as to be 1.7 or less (typically 1.5).

  By employing a precursor layer (simply referred to as “precursor layer”) that uses the above precursor solution as a starting material, an oxide layer 30 composed of bismuth (Bi) and niobium (Nb) is obtained. More specifically, the oxide layer 30 of this embodiment includes an oxide composed of bismuth (Bi) and niobium (Nb) having a crystal phase (including a microcrystalline phase) having a pyrochlore crystal structure. . In the oxide layer 30, when the number of atoms of bismuth (Bi) is 1, the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less.

FIG. 2 is an observation of a BNO oxide layer (oxide layer 30) by a cross-sectional TEM (Transmission Electron Microscopy) photograph and an electron diffraction image. Using the electron beam diffraction image of the BNO oxide layer, the Miller index and interatomic distance were determined, and structural analysis was performed by fitting with a known crystal structure model. (Bi _1.5 Zn _0.5 ) (Zn _0.5 Nb _1.5 ) O ₇ , β-BiNbO ₄ , and Bi ₃ NbO ₇ were used as known crystal structure models. As a result, as shown in FIG. 2, the crystal phase of the pyrochlore type crystal structure in the oxide layer 30 of this embodiment is (Bi _1.5 Zn _0.5 ) (Zn _0.5 Nb _1.5 ) O _7. It was found to be a type structure, or substantially the same or approximate to a (Bi _1.5 Zn _0.5 ) (Zn _0.5 Nb _1.5 ) O ₇ type structure.

  In addition, although the pyrochlore type crystal structure known so far was a structure that can be taken as a result of the inclusion of “zinc”, in this embodiment, a result different from the known aspect was obtained. At present, it is not clear why such a pyrochlore crystal structure is developed in a composition containing no zinc. However, as described later, by having a crystal phase of a pyrochlore crystal structure, as a dielectric layer of a thin layer capacitor or an insulating layer of other various solid-state electronic devices (for example, semiconductor devices or microelectromechanical systems) Has been found to lead to good dielectric properties (especially high dielectric constant).

  In addition, as shown in FIG. 2, the oxide layer 30 of the present embodiment also has an amorphous phase of an oxide composed of bismuth (Bi) and niobium (Nb). Thus, the presence of the crystalline phase and the amorphous phase is a preferable embodiment from the viewpoint of preventing the deterioration or variation in electrical characteristics due to the formation of unnecessary grain boundaries with high accuracy.

  Note that the present embodiment is not limited to this structure. Further, in order to simplify the drawing, description of patterning of the extraction electrode layer from each electrode layer is omitted.

2. Method for Manufacturing Thin Film Capacitor 100 Next, a method for manufacturing the thin film capacitor 100 will be described. In addition, the display of the temperature in this application represents the preset temperature of a heater. 3 to 6 are cross-sectional schematic views showing one process of the method of manufacturing the thin film capacitor 100, respectively. As shown in FIG. 3, 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. 3 is a diagram showing a process for forming the lower electrode layer 20. In the present embodiment, an example in which the lower electrode layer 20 of the thin film capacitor 100 is formed of platinum (Pt) will be described. As the lower electrode layer 20, a layer made of platinum (Pt) is formed on the substrate 10 by a known sputtering method.

(2) Formation of Oxide Layer as Insulating 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 baking, and (b) main baking. 4 to 6 are diagrams showing a process of forming the oxide layer 30. FIG. In the present embodiment, an example in which the oxide layer 30 in the manufacturing process of the thin film capacitor 100 is formed of an oxide composed of bismuth (Bi) and niobium (Nb) having a crystal phase of a pyrochlore crystal structure will be described. To do.

(A) Formation of Precursor Layer and Pre-Baking As shown in FIG. 4, a precursor containing bismuth (Bi) and a precursor containing niobium (Nb) are formed on the lower electrode layer 20 by a known spin coating method. As a starting material, a precursor layer 30a is formed using a precursor solution (hereinafter referred to as a precursor solution, which is the same as the precursor solution). Here, examples of the precursor containing bismuth (Bi) for the oxide layer 30 include bismuth 2-ethylhexanoate, bismuth octylate, bismuth chloride, bismuth nitrate, or various bismuth alkoxides (for example, bismuth isopropoxy). Bismuth butoxide, bismuth ethoxide, bismuth methoxide). Further, examples of the precursor containing niobium (Nb) for the oxide layer 30 in the present embodiment are niobium 2-ethylhexanoate, niobium octylate, niobium chloride, niobium nitrate, or various niobium alkoxides (for example, Niobium isopropoxide, niobium butoxide, niobium ethoxide, niobium methoxyethoxide) may be employed. The solvent of the precursor solution is at least one alcohol solvent selected from the group consisting of ethanol, propanol, butanol, 2-methoxyethanol, 2-ethoxyethanol, and 2-butoxyethanol, or acetic acid, propionic acid, and octylic acid. Preferably, the solvent is at least one carboxylic acid selected from the group consisting of: Therefore, in the solvent of the precursor solution, a mixed solvent of the above-described two or more alcohol solvents or a mixed solvent of the above-described two or more carboxylic acids is an embodiment that can be employed.

Moreover, in this embodiment, the precursor solution which makes each precursor the solute which the number of atoms of bismuth (Bi) and the number of atoms of niobium (Nb) shown in the following (1) and (2) are adjusted is a solute Is the starting material.
(1) Precursor containing bismuth (Bi) described above (2) When the number of bismuth (Bi) in the precursor of (1) is 1, the number of niobium (Nb) is 1.3 or more. Precursor containing niobium (Nb) which is 1.7 or less

  After that, as preliminary baking, preliminary baking is performed in a temperature range of 80 ° C. to 250 ° C. for a predetermined time in an oxygen atmosphere or in the air (collectively, also referred to as “oxygen-containing atmosphere”). In the pre-baking, the solvent in the precursor layer 30a is sufficiently evaporated, and in order to develop characteristics that enable future plastic deformation (preferably in a gel state (before thermal decomposition, the organic chain remains). Is considered). In order to realize the above-mentioned viewpoint with higher accuracy, the pre-baking temperature is preferably 80 ° C. or higher and 250 ° 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 baking Thereafter, as the main baking, the precursor layer 30a is subjected to a temperature in a range of 520 ° C. or more and 620 ° C. or less for a predetermined time in an oxygen atmosphere (for example, 100% by volume, but not limited thereto). Heat at (first temperature). As a result, as shown in FIG. 5, an oxide layer 30 made of bismuth (Bi) and niobium (Nb) is formed on the electrode layer. The atomic composition ratio of bismuth (Bi) and niobium (Nb) in the oxide layer 30 is such that niobium (Nb) is 1.3 or more and 1.7 or less when (Bi) is 1.

  Here, in the present embodiment, the main firing temperature (first temperature) is set to 520 ° C. or more and 620 ° C. or less. However, the upper limit value is an upper limit value at which an effect of the present embodiment, which will be described later, has been confirmed at the present time, and is not a technical limit value that exhibits the effect.

However, according to the research and analysis of the present inventors, for example, when the number of atoms of bismuth (Bi) is 1, the precursor solution is prepared so that the number of atoms of niobium (Nb) is 1. In some cases, as the temperature for heating the precursor layer increases from 550 ° C. to 600 ° C., the crystal phase of the pyrochlore crystal structure is not observed, while the crystal structure of β-BiNbO ₄ is likely to be developed. It was discovered. However, when the precursor layer 30a of the present embodiment is used, the β-BiNbO ₄ crystal structure is hardly expressed even when heated at 600 ° C. or higher, in other words, having a pyrochlore crystal structure. A very interesting result was obtained that the crystal phase remained highly accurate. Therefore, it was confirmed that the precursor layer 30a of the present embodiment can maintain the crystal phase of the pyrochlore crystal structure even at a high temperature of 600 ° C. or higher.

  Note that the thickness range 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. 6 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 100 is formed of platinum (Pt) will be described. Similar to the lower electrode layer 20, the upper electrode layer 40 is formed of a layer made of platinum (Pt) on the oxide layer 30 by a known sputtering method. By forming the upper electrode layer 40, the thin film capacitor 100 shown in FIG. 1 is manufactured.

  In the present embodiment, the precursor layer is formed by heating a precursor layer starting from a precursor solution containing a precursor containing bismuth (Bi) and a precursor containing niobium (Nb) in an oxygen-containing atmosphere. An oxide layer made of bismuth (Bi) and niobium (Nb) is formed. In addition, particularly good electrical characteristics can be obtained when the heating temperature for forming the oxide layer is 520 ° C. or higher. Even when the heating temperature exceeds 600 ° C. (for example, 620 ° C. or less), good electrical characteristics may be obtained. In particular, as the ratio of niobium (Nb) to bismuth (Bi) increases, the crystal phase of the pyrochlore crystal structure tends to remain with high accuracy even when the heating temperature becomes higher.

In addition, if the oxide layer manufacturing method of this embodiment is employed, the oxide layer precursor solution may be heated in an oxygen-containing atmosphere without using a vacuum process. Thus, the area can be easily increased, and the industrial property or mass productivity can be remarkably improved.
3. Electrical characteristics of thin film capacitor 100

(1) Relative permittivity and dielectric loss (tan δ)
FIG. 7 is a graph showing the relative dielectric constant and dielectric loss (tan δ) of the oxide layer 30 formed by heating at 550 ° C. in the present embodiment. FIG. 8 is a graph corresponding to FIG. 7 of the oxide layer 30 formed by heating at 600 ° C. in the present embodiment.

  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 (tan δ) 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 at room temperature. For this measurement, a 1260-SYS type broadband dielectric constant measurement system manufactured by Toyo Corporation was used.

  More specifically, FIG. 7 shows that the precursor solution was prepared such that the number of atoms of niobium (Nb) was 1.5 when the number of atoms of bismuth (Bi) was 1, and at 550 ° C. When the oxide layer 30 is formed by heating, the relative dielectric constant and the dielectric loss (tan δ) of the oxide layer 30 at a frequency of 1 Hz to 1 MHz are shown. Further, FIG. 8 shows that when the number of atoms of bismuth (Bi) is 1, a precursor solution is prepared so that the number of atoms of niobium (Nb) is 1.5, and is heated at 600 ° C. to oxidize. When the physical layer 30 is formed, the relative dielectric constant and dielectric loss (tan δ) of the oxide layer 30 at a frequency of 1 Hz to 1 MHz are shown. In both FIGS. 7 and 8, in order to confirm reproducibility, three similar samples were prepared, and the relative dielectric constant and dielectric loss (tan δ) were examined.

  As shown in FIGS. 7 and 8, it was confirmed that the relative dielectric constant was 220 or more at any frequency from 1 Hz to 1 MHz. In particular, when the oxide layer 30 is formed by heating at 600 ° C., the ratio is higher than the relative dielectric constant of the oxide layer 30 formed by heating at 550 ° C. at any of the aforementioned frequencies. The point where the dielectric constant (about 250 or more) was obtained is worthy of special mention. On the other hand, with respect to the dielectric loss (tan δ), although there is some variation in the dielectric loss (tan δ) of the oxide layer 30 formed by heating at 600 ° C., good results can be obtained without depending on the heating temperature. It was. The reason why the value of the dielectric loss (tan δ) suddenly increases in the high frequency range (20 KHz or higher) is considered to be because the parasitic inductance is dominant due to the structure of the thin film capacitor 100. In other words, in the high frequency range (20 KHz or more), it is considered that the characteristics of the BNO oxide itself are not represented.

In addition, the numerical value of the dielectric constant shown in FIG.7 and FIG.8 is a numerical value as the whole oxide layer. As will be described later, according to the analysis of the inventors of the present application, the oxide layer composed of bismuth (Bi) and niobium (Nb) has a crystal phase other than the crystal phase of the pyrochlore crystal structure (for example, β-BiNbO ₄ type). It has been found that the value of the relative dielectric constant of the oxide layer as a whole can be varied by having the crystal phase) and / or the amorphous phase. However, as shown in FIGS. 7 and 8, it can be said that the oxide layer 30 of this embodiment has many crystal phases of a pyrochlore crystal structure that is considered to produce a high dielectric constant. In other words, it was confirmed from FIGS. 7 and 8 that the crystal phase of the pyrochlore crystal structure can be maintained even by baking at a high temperature of 600 ° C.

  As a comparative example, a precursor solution is prepared so that the number of atoms of niobium (Nb) is 1.5 when the number of atoms of bismuth (Bi) is 1, and is heated at 500 ° C. to oxidize. As a result of investigating the relative dielectric constant and dielectric loss (tan δ) of the oxide layer 30 at a frequency of 1 Hz to 1 MHz when the physical layer is formed, both the relative dielectric constant and the dielectric loss have frequency dependency. It became clear that it was very big. In particular, it was confirmed that the relative dielectric constant was about 250 at 1 Hz, while the value at 1 MHz was reduced to about 60. Here, most of the oxide formed by heating at 500 ° C. is an amorphous phase, and this amorphous phase at 500 ° C. is considered to have a great influence on electrical characteristics. In other words, since the amorphous phase is dominant with respect to the electrical characteristics, it is considered that the frequency dependence has become very large. If the heating is performed at 520 ° C. or higher so that crystallization is promoted and the crystal phase of the pyrochlore crystal structure is formed with higher accuracy, the relative dielectric constant and dielectric loss (tan δ) of the oxide layer 30 is 550 ° C. It approaches the properties of the oxide formed by heating.

(2) Leakage current When the number of atoms of bismuth (Bi) is 1, a precursor solution is prepared so that the number of niobium (Nb) atoms is 1.5, and the oxide is heated at 550 ° C. When the layer 30 was formed, the leakage current value when 50 kV / cm was applied was examined. As a result, the leak current value was able to obtain characteristics that can be used as a capacitor. The leakage current was measured by applying the voltage described above between the lower electrode layer and the upper electrode layer. In addition, Agilent Technologies 4156C type was used for this measurement.

3. Crystal structure analysis by X-ray diffraction (XRD) method FIG. 9 shows a precursor solution prepared so that the number of atoms of niobium (Nb) is 1.5 when the number of atoms of bismuth (Bi) is 1. And X-ray diffraction (XRD) measurement results showing a crystal structure when the oxide layer 30 is formed by heating at 550 ° C. or 600 ° C. FIG. On the other hand, FIG. 10 shows that when the number of atoms of bismuth (Bi) is 1, a precursor solution is prepared so that the number of atoms of niobium (Nb) is 1, and heated at 550 ° C. or 600 ° C. It is a measurement result of X-ray diffraction (XRD) which shows a crystal structure when an oxide layer is formed. As a comparative example, in each drawing, a precursor solution was prepared such that the number of atoms of niobium (Nb) was 1.5 when the number of atoms of bismuth (Bi) was 1, and 500 ° C. Also shown is the measurement result of the oxide layer when heated at.

  As shown in FIGS. 9 and 10, when the precursor solution is prepared so that the number of atoms of niobium (Nb) is 1.5 when the number of atoms of bismuth (Bi) is 1, Compared to the case where the precursor solution was prepared so that the number of atoms of niobium (Nb) would be 1 when the number of atoms of (Bi) was 1, the half width at which 2θ was around 28 ° to 29 ° It turns out that it becomes small. The peak in the vicinity of 28 ° to 29 ° is a peak showing a pyrochlore crystal structure. Therefore, when the number of atoms of bismuth (Bi) is 1, the precursor solution is prepared so that the number of atoms of niobium (Nb) is 1.5, so that the crystal phase of the pyrochlore crystal structure grows. You can confirm that On the other hand, as shown in the comparative examples in each figure, when heated at 500 ° C., only a broad peak was observed when 2θ was around 28 ° to 29 °. Therefore, it is highly likely that the oxide layer heated at 500 ° C. has little or no crystal phase having a pyrochlore crystal structure.

  In addition, each analysis thru | or measurement mentioned above is oxide when a precursor solution is prepared so that the number of atoms of niobium (Nb) may be 1.5 when the number of atoms of bismuth (Bi) is 1. This is done for layer 30. However, the oxide formed when the precursor solution is prepared so that the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less when the number of atoms of bismuth (Bi) is 1. If it is the layer 30, a result substantially equivalent to each above-mentioned analysis result thru | or measurement result can be obtained.

  The finally formed oxide layer 30 includes an oxide (which may include inevitable impurities) made of bismuth (Bi) and niobium (Nb) having a crystal phase of a pyrochlore type crystal structure, and the bismuth. If the number of atoms of (Bi) is 1 and the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less, good electrical characteristics can be obtained.

  As described above, regarding the atomic composition ratio of bismuth (Bi) and niobium (Nb) in the oxide layer 30, when the number of atoms of bismuth (Bi) is 1, the number of niobium (Nb) atoms is 1. If it is 3 or more and 1.7 or less, the relative dielectric constant, dielectric loss (tan δ), and leakage current value are various solid-state electronic devices (for example, capacitors, semiconductor devices, or microelectromechanical systems, high-frequency filters, It was confirmed that application to a patch antenna or a composite device including at least two of RCLs is particularly preferable.

<Second Embodiment>
The thin film capacitor 200 of the present embodiment is the same as the thin film capacitor 100 of the first embodiment, except that the oxide layer 30 of the thin film capacitor 100 formed in the first embodiment is changed to an oxide layer 230. The same. Therefore, the description which overlaps with 1st Embodiment is abbreviate | omitted.

  FIG. 11 is a diagram showing an overall configuration of a thin film capacitor 200 which is an example of a solid-state electronic device in the present embodiment. The oxide layer 230 of the present embodiment is further formed by the oxygen layer 30 of the first embodiment after the oxide layer 30 is formed by the main baking process at the first temperature (520 ° C. or more and 620 ° C. or less) for about 20 minutes. It is formed by heating at a second temperature (typically 350 ° C. to 600 ° C.) equal to or lower than the first temperature in the contained atmosphere. In the present embodiment, the heating of the oxide layer at the second temperature is also referred to as “post-annealing treatment”.

  In the thin film capacitor 200 including the above-described oxide layer 230, the oxide layer 230 and its underlying layer (that is, the lower electrode) are not changed without substantially changing the relative dielectric constant of the thin film capacitor 100 of the first embodiment. The effect of further improving the adhesion with the layer 20) and / or the upper electrode layer 40 is obtained.

  In addition, it is preferable that the 2nd temperature in a post-annealing process is a temperature below 1st temperature. This is because if the second temperature is higher than the first temperature, the second temperature is likely to affect the physical properties of the oxide layer 230. Therefore, it is preferable to select a temperature at which the second temperature does not dominate the physical properties of the oxide layer 230. On the other hand, the lower limit value of the second temperature in the post-annealing process is determined from the viewpoint of further improving the adhesion with the base layer (that is, the lower electrode layer 20) and / or the upper electrode layer 40 as described above.

<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 entire configuration of a thin film capacitor 300 which is an example of the 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. In addition, the description which overlaps with 1st Embodiment is abbreviate | omitted.

  As shown in FIG. 12, the thin film capacitor 300 of this embodiment is formed on the substrate 10. The thin film capacitor 300 includes a lower electrode layer 320, an oxide layer 330 made of an oxide dielectric, and an upper electrode layer 340 from the substrate 10 side.

2. Manufacturing Process of Thin Film Capacitor 300 Next, a manufacturing method of the thin film capacitor 300 will be described. 13 to 22 are cross-sectional schematic views showing one process of the method of manufacturing the thin film capacitor 300. 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 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. First, a lower electrode using a precursor solution for a lower electrode layer having a precursor containing lanthanum (La) and a precursor containing nickel (Ni) as a solute on a substrate 10 by a known spin coating method. A layer precursor layer 320a is formed.

  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. 13, in the state heated in the range of 80 ° C. or higher and 300 ° C. or lower, for the lower electrode layer Using the mold M1, embossing is performed at a pressure of 1 MPa or more and 20 MPa or less. 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 mounted from the lower part with a heater, The following is a method in which stamping is performed using a heated mold. In this case, it is more preferable in terms of workability to use a method in which the base is heated from below by a heater and 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 stamping process is a pressure in the range of 1 MPa or more and 20 MPa or less, the lower electrode layer precursor layer 320a is deformed following the surface shape of the mold, and a desired stamping structure is obtained. Can be formed with high accuracy. Moreover, the pressure applied when embossing is performed is set to a low pressure range of 1 MPa to 20 MPa. 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. 14, 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 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. Such processing is performed. As a result, since the frictional force between each precursor layer and the mold can be reduced, the stamping process can be performed on each precursor layer with higher accuracy. 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 the 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. 15, 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 serving as Dielectric Layer or Insulating Layer Next, an oxide layer 330 serving as 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) stamping step, and (c) main firing step. 16 to 19 are diagrams showing a process for forming the oxide layer 330.
(A) Formation of Precursor Layer and Pre-Firing As shown in FIG. 16, a precursor and niobium containing bismuth (Bi) are formed on the substrate 10 and the patterned lower electrode layer 320 as in the second embodiment. A precursor layer 330a is formed starting from a precursor solution having a precursor containing (Nb) as a solute. Thereafter, preliminary firing is performed in an oxygen-containing atmosphere while being heated to 80 ° C. or higher and 250 ° C. or lower. As in the first embodiment, when the number of atoms of bismuth (Bi) in the precursor containing bismuth (Bi) is 1 as the solute in the precursor solution in this embodiment, niobium ( The number of atoms of bismuth (Bi) and the number of atoms of niobium (Nb) are adjusted so that the number of Nb) atoms is 1.3 or more and 1.7 or less (typically 1.5).

(B) Embossing process In this embodiment, as shown in FIG. 17, 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 1 MPa or more and 20 MPa or less using the dielectric layer mold M2 while being heated to 80 ° C. or more and 300 ° C. or less. .

  Thereafter, the entire surface of the precursor layer 330a is etched. As a result, as shown in FIG. 18, the precursor layer 330a is completely removed from the region 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 firing Thereafter, as in the second embodiment, the precursor layer 330a is subjected to main firing. As a result, as shown in FIG. 19, an oxide layer 330 (however, it may contain unavoidable impurities; the same applies hereinafter) is formed on the lower electrode layer 320 as a dielectric layer. As the main firing, the precursor layer 330a is heated in an oxygen atmosphere for a predetermined time in a temperature range of 520 ° C. or more and 620 ° C. or less.

  By this main baking step, an oxide layer 330 made of bismuth (Bi) and niobium (Nb) is obtained. More specifically, as in the first embodiment, the oxide layer 330 of this embodiment includes bismuth (Bi) and niobium (Nb) having a crystal phase (including a microcrystalline phase) having a pyrochlore crystal structure. It contains an oxide consisting of In the oxide layer 30, when the number of atoms of bismuth (Bi) is 1, the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less.

  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 unnecessary regions can be removed more easily than etching after each precursor layer is finally fired.

(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. 20, in order to perform patterning of the precursor layer 340 a for the upper electrode layer that has been pre-baked, the precursor layer 340 a for the upper electrode layer is heated to 80 ° C. or more and 300 ° C. or less. Then, using the upper electrode layer mold M3, the upper electrode layer precursor layer 340a is embossed at a pressure of 1 MPa to 20 MPa. Then, as shown in FIG. 21, the upper electrode layer precursor layer 340a is completely removed from regions other than the region corresponding to the upper electrode layer 340 by etching the entire surface of the upper electrode layer precursor layer 340a.

  Then, as shown in FIG. 22, 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, so that the oxide layer 330 is 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.

  Also in this embodiment, a precursor layer starting from a precursor solution containing a precursor containing bismuth (Bi) and a precursor containing niobium (Nb) as a solute is heated in an oxygen-containing atmosphere. Thus, an oxide layer 330 made of bismuth (Bi) and niobium (Nb) is formed. In addition, when the heating temperature for forming the oxide layer is 520 ° C. or more and 620 ° C. or less, particularly good electrical characteristics can be obtained. In addition, if the oxide layer manufacturing method of this embodiment is employed, the oxide layer precursor solution may be heated in an oxygen-containing atmosphere without using a vacuum process. Thus, the area can be easily increased, and the industrial property or mass productivity can be remarkably improved.

  In addition, 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. As a result, both the electrode layer and the oxide layer can be easily patterned. As a result, the thin film capacitor 300 of this embodiment is extremely excellent in industrial property or mass productivity.

<Fourth Embodiment>
1. Overall Configuration of Thin Film Capacitor of this Embodiment Also in this embodiment, embossing is performed in the formation process of all layers of a thin film capacitor which is an example of a solid-state electronic device. The overall configuration of a thin film capacitor 400, which is an example of a solid-state electronic device in the present embodiment, is shown in FIG. In this embodiment, the lower electrode layer, the oxide layer, and the upper electrode layer are pre-fired after the precursor layers are stacked.

  In addition, all the precursor layers that have been subjected to preliminary firing are subjected to main firing after being embossed. In addition, about the structure of this Embodiment, the description which overlaps with the 1st thru | or 3rd embodiment is abbreviate | omitted. As shown in FIG. 26, the thin film capacitor 400 is formed on the substrate 10. The thin film capacitor 400 includes a lower electrode layer 420 from the substrate 10 side, an oxide layer 430 that is an insulating layer made of a dielectric, and an upper electrode layer 440.

2. Manufacturing Process of Thin Film Capacitor 400 Next, a manufacturing method of the thin film capacitor 400 will be described. FIG. 23 to FIG. 25 are cross-sectional schematic views showing one process of the method of manufacturing the thin film capacitor 400, respectively. In manufacturing the thin film capacitor 400, first, a lower electrode layer precursor layer 420a which is a precursor layer of the lower electrode layer 420, a precursor layer 430a which is a precursor layer of the oxide layer 430, and an upper portion are formed on the substrate 10. A stacked body of the upper electrode layer precursor layer 440a, which is a precursor layer of the electrode layer 440, is formed. Next, after the stamping process is performed on the laminated body, the firing is performed. Also in the manufacturing process of the thin film capacitor 400, the description overlapping with the first to third embodiments is omitted.

(1) Formation of Laminate of Precursor Layer As shown in FIG. 23, first, a precursor layer for a lower electrode layer 420a, which is a precursor layer for the lower electrode layer 420, and a precursor for an oxide layer 430 are formed on the substrate 10. A laminated body of a precursor layer 430a which is a layer and a precursor layer 440a for the upper electrode layer which is a precursor layer of the upper electrode layer 440 is formed. In the present embodiment, as in the third embodiment, the lower electrode layer 420 and the upper electrode layer 440 of the thin film capacitor 400 are formed of a conductive oxide layer made of lanthanum (La) and nickel (Ni), An example in which the oxide layer 430 serving as a dielectric layer is formed of an oxide layer made of bismuth (Bi) and niobium (Nb) will be described.

  First, a lower electrode using a precursor solution for a lower electrode layer having a precursor containing lanthanum (La) and a precursor containing nickel (Ni) as a solute on a substrate 10 by a known spin coating method. A layer precursor layer 420a is formed. Thereafter, as preliminary firing, the lower electrode layer precursor layer 420a is heated in a temperature range of 80 ° C. or higher and 250 ° C. or lower in an oxygen-containing atmosphere for a predetermined time. Moreover, the desired thickness of the lower electrode layer 420 can be obtained by repeating the formation and preliminary baking of the lower electrode layer precursor layer 420a by the spin coating method described above a plurality of times.

  Next, the precursor layer 430a is formed on the precursor layer 420a for the lower electrode layer that has been pre-fired. First, on the lower electrode layer precursor layer 420a, a precursor layer 430a is formed using a precursor solution containing a precursor containing bismuth (Bi) and a precursor containing niobium (Nb) as a solute. Thereafter, as preliminary firing, the precursor layer 430a 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.

  Next, a precursor containing lanthanum (La) and nickel (Ni) are contained on the precursor layer 430a that has been pre-fired by a known spin coating method in the same manner as the precursor layer 420a for the lower electrode layer. A precursor layer 440a for the upper electrode layer is formed using a precursor solution having the precursor as a solute as a starting material. Thereafter, preliminary firing is performed by heating the precursor layer 440a for the upper electrode layer in an oxygen-containing atmosphere in a temperature range of 80 ° C. to 250 ° C.

(2) Embossing Next, as shown in FIG. 24, in order to pattern the laminated body (420a, 430a, 440a) of each precursor layer, the state heated within the range of 80 degreeC or more and 300 degrees C or less Then, using the laminate mold M4, the stamping process is performed at a pressure of 1 MPa or more and 20 MPa or less.

  Thereafter, the entire stack of the precursor layers (420a, 430a, 440a) is etched. As a result, as shown in FIG. 25, the stacked body (420a, 430a, 440a) of each precursor layer is completely removed from regions other than the region corresponding to the lower electrode layer, the oxide layer, and the upper electrode layer ( Etching step for the entire surface of each precursor layer (420a, 430a, 440a).

(3) Main baking Next, main baking is performed with respect to the laminated body (420a, 430a, 440a) of each precursor layer. As a result, a lower electrode layer 420, an oxide layer 430, and an upper electrode layer 440 are formed on the substrate 10 as shown in FIG.

  Also in this embodiment, a precursor layer starting from a precursor solution containing a precursor containing bismuth (Bi) and a precursor containing niobium (Nb) as a solute is heated in an oxygen-containing atmosphere. Thus, an oxide layer 430 made of bismuth (Bi) and niobium (Nb) is formed. As in the first embodiment, when the number of atoms of bismuth (Bi) in the precursor containing bismuth (Bi) is 1 as the solute in the precursor solution in this embodiment, niobium ( The number of atoms of bismuth (Bi) and the number of atoms of niobium (Nb) are adjusted so that the number of Nb) atoms is 1.3 or more and 1.7 or less (typically 1.5).

  Through the above-described main baking step, an oxide layer 430 made of bismuth (Bi) and niobium (Nb) is obtained. More specifically, as in the first embodiment, the oxide layer 430 of this embodiment includes bismuth (Bi) and niobium (Nb) having a crystal phase (including a microcrystalline phase) having a pyrochlore crystal structure. It contains an oxide consisting of In the oxide layer 30, when the number of atoms of bismuth (Bi) is 1, the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less.

  Note that when the heating temperature for forming the oxide layer 430 is 520 ° C. or more and 620 ° C. or less, particularly good electrical characteristics can be obtained. In addition, if the oxide layer manufacturing method of this embodiment is employed, the oxide layer precursor solution may be heated in an oxygen-containing atmosphere without using a vacuum process. Thus, the area can be easily increased, and the industrial property or mass productivity can be remarkably improved.

  In the present embodiment, the main firing is performed after the stamping process is performed on the precursor layers of all the oxide layers that have been subjected to the preliminary firing. Therefore, it is possible to shorten the process when forming the embossing structure.

  As described above, it is confirmed that the oxide layer in each of the above-described embodiments has a high relative dielectric constant that is unprecedented as a BNO oxide because the crystal phase of the pyrochlore crystal structure is distributed. It was done. An oxide dielectric having a specific composition ratio in which the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less when the number of atoms of bismuth (Bi) is 1 is particularly high. It was also revealed that the dielectric constant was expressed. Further, when the precursor containing bismuth (Bi) and the number of atoms of the bismuth (Bi) is 1, the niobium (Nb) has an atomic number of 1.3 or more and 1.7 or less. It has been clarified that an oxide dielectric having higher accuracy and a higher dielectric constant can be obtained when a precursor starting from a precursor solution containing a precursor containing) as a solute is selected.

  In addition, the oxide layer in each of the above-described embodiments is manufactured by a solution method, thereby simplifying the manufacturing process. In addition, in the production of an oxide layer by a solution method, the heating temperature for forming the oxide layer (the temperature of the main firing) is set to 520 ° C. or more and 620 ° C. or less, so that the relative dielectric constant is high and the dielectric It is possible to obtain a BNO oxide layer having good electrical characteristics with low loss. In addition, the oxide layer manufacturing method in each of the above-described embodiments is a simple method in a relatively short time without requiring complicated and expensive equipment such as a vacuum apparatus. This greatly contributes to the provision of various solid-state electronic devices provided with a physical layer and such an oxide layer.

<Other embodiments>
By the way, in the oxide layer in the third or fourth embodiment, the post-annealing process is not performed, but the post-annealing process is adopted as a modification of the third or fourth embodiment. This is a preferable embodiment. For example, a post-annealing process can be performed after the embossing process is performed and the patterning is completed. By this post-annealing process, the same effects as those described in the second embodiment can be obtained.

Further, the oxide layer in each of the above embodiments is suitable for various solid-state electronic devices that control a large current with a low driving voltage. 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, capacitors such as multilayer thin film capacitors and variable capacitance thin film capacitors, semiconductor devices such as metal oxide semiconductor junction field effect transistors (MOSFETs) and nonvolatile memories, or micro TAS (Total Analysis System), micro chemical chips, DNA chips MEMS (microelectromechanical system) or NEMS (nanoelectromechanical)
The oxide layer in each of the above-described embodiments can also be applied to a device of a microelectromechanical system typified by a system) or a composite device including at least two of a high-frequency filter, a patch antenna, or an RCL.

  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 is set in the range of “1 MPa or more and 20 MPa or less” for the following reason. First, if the pressure is less than 1 MPa, the pressure may be too low to emboss each precursor layer. On the other hand, if the pressure is 20 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 2 MPa to 10 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 claims.

10 Substrate 20, 320, 420 Lower electrode layer 320a, 420a Precursor layer for lower electrode layer 30, 330, 430 Oxide layer (oxide dielectric layer)
30a, 330a, 430a Oxide layer precursor layer 40, 340, 440 Upper electrode layer 340a, 440a Upper electrode layer precursor layer 100, 200, 300, 400 Thin layer capacitor as an example of solid-state electronic device M1 Lower electrode Layer type M2 Dielectric layer type M3 Upper electrode layer type M4 Laminate type

Claims (12)

When an oxide of bismuth (Bi) and niobium (Nb) having a pyrochlore crystal structure (which may include unavoidable impurities) is included, and the number of atoms of the bismuth (Bi) is 1, The number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less,
Oxide dielectric. The oxide further has an amorphous phase of an oxide composed of bismuth (Bi) and niobium (Nb).
The oxide dielectric according to claim 1. When the oxide has a precursor containing the bismuth (Bi) and the number of atoms of the bismuth (Bi) is 1, the number of atoms of the niobium (Nb) is 1.3 or more and 1.7 or less. Formed by heating a precursor starting from a precursor solution having a precursor containing niobium (Nb) as a solute in an oxygen-containing atmosphere;
The oxide dielectric according to any one of claims 1 and 2. It comprises the oxide dielectric according to any one of claims 1 to 3.
Solid electronic device. The solid-state electronic device is one selected from the group of a high-frequency filter, a patch antenna, a capacitor, a semiconductor device, and a microelectromechanical system;
The solid state electronic device according to claim 4. When the precursor containing bismuth (Bi) and the number of atoms of the bismuth (Bi) are 1, the niobium (Nb) has an atomic number of 1.3 or more and 1.7 or less. By heating a precursor layer starting from a precursor solution containing a precursor containing solute at a first temperature of 520 ° C. or more and 620 ° C. or less in an oxygen-containing atmosphere,
When the oxide of bismuth (Bi) and niobium (Nb) having a pyrochlore crystal structure (including inevitable impurities) is included and the number of atoms of the bismuth (Bi) is 1. Forming a layer of an oxide dielectric in which the number of atoms of niobium (Nb) is 1.3 or more and 1.7 or less,
A method for manufacturing an oxide dielectric. The oxide further has an amorphous phase of an oxide composed of bismuth (Bi) and niobium (Nb).
The manufacturing method of the oxide dielectric of Claim 6. After the precursor layer is heated in the oxygen-containing atmosphere, it further includes an additional heating step of heating at a second temperature not higher than the first temperature.
A method for producing an oxide dielectric according to claim 6. Before forming the oxide dielectric layer, a stamping structure of the precursor layer is performed by performing a stamping process in a state where the precursor layer is heated at 80 ° C. to 300 ° C. in an oxygen-containing atmosphere. Forming,
The method for manufacturing an oxide dielectric according to claim 6. The embossing process is performed at a pressure within a range of 1 MPa to 20 MPa.
A method for manufacturing the oxide dielectric according to claim 9. A solid-state electronic device comprising the oxide dielectric according to any one of claims 6 to 10 is manufactured.
Manufacturing method of solid-state electronic device. A precursor of an oxide composed of bismuth (Bi) and niobium (Nb) having a crystal phase of a pyrochlore type crystal structure,
The niobium (Nb) wherein the number of atoms of the niobium (Nb) is 1.3 or more and 1.7 or less when the number of atoms of the precursor containing the bismuth (Bi) and the bismuth (Bi) is 1. ) And a precursor containing solute,
Precursor of oxide dielectric.