JPH06306678A - Production of composite body composed of substrate and dielectric - Google Patents

Abstract

PURPOSE:To form a composite body having a dielectric coating film excellent in heat resistance and corrosion resistance on a conductive substrate by depositing the hydroxide or the like of a metal on the surface of the substrate by electrolysis by using the substrate as a cathode and after that, applying current by using the substrate as an anode to oxidize the hydroxide and the substrate. CONSTITUTION:The composite body composed of the substrate and a electrodeposited material is formed by applying current by using the substrate made of valve metal such as stainless steel or Ni, Cu, particularly Ti, Zr, Ta, Nb as the cathode, platinum as the anode and a mixed aq. solution of Ba(NO3)2 with TiCl3 as an electrolyte to form the film like electrodeposited material composed of the hydrate of Ti and the hydroxide of Ba and Ti on the surface of the cathode substrate. The composite dielectric coating film composed of the oxide of the substrate metal, TiO2 and BaO and excellent in corrosion resistance and large in dielectric constant is formed on the substrate by applying current by using the composite material as the anode and the platinum made cathode in an ammonium adipate aq. solution to electrolytic oxidize the substrate of the anode composite body and the hydroxide or the like on the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a composite body composed of a substrate and a dielectric, which is applied to small capacitors, high density memories and the like. The present invention also relates to a method for forming an anticorrosion coating.

[0002]

2. Description of the Related Art In the field of electronic equipment, various electronic parts are required to be small, lightweight, high performance, high frequency, etc. in order to realize small size, light weight, high performance and power saving. There is a strong demand. Therefore, miniaturization, large capacity, high frequency, chip, on-board, etc. are required for capacitors, which are one of the electronic components, and high density is required for the memory, which is also one of the electronic components. Has been done.

A capacitor has a structure in which a dielectric is sandwiched between electrodes. Here, the dielectric constant, which is the physical property of the dielectric, is ε, the thickness of the dielectric is d (cm), and the surface area of the electrode. To S
(Cm ² ), the capacitance C of the capacitor (μF)
Is given by C = 8.855 × 10 ^-8 × ε × S / d (1) From this equation, to increase the capacitance, increase the relative permittivity or the electrode area, or reduce the thickness of the dielectric. I know it's good. At present, there are a ceramic capacitor as a capacitor using a material having a high dielectric constant, a film capacitor or an electrolytic capacitor having an expanded electrode area per unit area, and an electrolytic capacitor having a thin film. By the way, since the electrolytic capacitor uses the oxide film of the substrate as a dielectric, the permittivity is uniquely determined by the substrate type (the relative permittivity is about 10 for an aluminum electrolytic capacitor and about 3 for a tantalum electrolytic capacitor).
0). Therefore, in order to further reduce the size and increase the capacity, a technique for forming various types of dielectric thin films regardless of the substrate type is required.

A DRAM which is a semiconductor memory device
(Writable memory that requires a memory holding operation) is a device including an ultrathin dielectric film formed on a silicon wafer as a part. The most basic structure of this kind of portion is a silicon wafer on which silicon dioxide is formed by thermal oxidation or the like. At present, a silicon wafer that is etched to increase the surface area and has a larger surface area is used for general-purpose products. Recently, research has been conducted to form a material film having a larger relative dielectric constant instead of silicon dioxide (having a relative dielectric constant of about 4) in order to further increase the density. Therefore, in order to further increase the density, it is necessary to have a technique for forming various types of dielectric thin films regardless of the substrate type.

On the other hand, in the field of anticorrosion coating, it is necessary to have characteristics such as oxidation resistance, corrosion resistance and heat resistance. However, in the case of metal, a plating film or a natural oxide film is used as an anticorrosion film, and other film types are not well known. Therefore, if it is possible to form an anticorrosion film having various properties superior to those of a plated film or a natural oxide film, it is considered that the range of application of these materials will be further expanded. In order to satisfy various characteristics, a technique for forming a dense and defect-free coating of oxide having good heat resistance is required regardless of the substrate type.

Examples of the material having a high dielectric constant include a complex oxide film having a perovskite structure such as barium titanate and an oxide such as titanium dioxide. Conventionally, as a method of forming such a film on various substrates, there are a sputtering method and a sol-gel method.

A method of forming a film of barium titanate or strontium titanate by sputtering has been studied for a long time, and a film having good film thickness uniformity is obtained on a smooth substrate. However, as the number of components increases, it becomes more difficult to control the composition ratio, and it becomes more difficult to synthesize a thin film having a desired composition. Therefore, it has not yet been put to practical use.

The sol-gel method includes a method using a metal alkoxide and a method using fine particles, and a film forming method includes a dip coating method and an electrophoresis method. The dip coating is a method in which the substrate is gently dropped into the solution, held for several seconds, and then gently pulled up to deposit the solute on the substrate. The electrophoretic method is a method in which fine particles are uniformly dispersed in a solvent, and the substrate is used as a cathode electrode to conduct electricity, so that charged fine particles are accumulated on the substrate.

The method using a metal alkoxide utilizes hydrolysis or polycondensation reaction of a metal alkoxide, and uses a metal alkoxide of Ba, Ti or Sr and dip-coats a barium titanate or strontium titanate film. Has been successfully synthesized. However, this film was not suitable for practical use because it was too thick as several μm and had electrical defects and large power loss and leakage current.

[0010] In addition, we previously mentioned Japanese Patent Application No. 4-72288.
, Stainless steel, Fe, Ni, Cu,
One of the Al metals is used as a cathode electrode,
It is proposed that a composite of a substrate and an oxide be obtained by applying an electric current in a solution containing a metal ion forming a target dielectric to obtain an electrodeposit and heat-treating it. However, when various capacitor characteristics were measured for this composite, the leakage current, which is one of the characteristics, was 75 μA / cm ²
From 1 mA / cm ² to 50 μA / cm ²
It was desired to reduce it to the following. Further, as the anticorrosion film, no significant difference was observed with the natural oxide film.

As described above, according to the conventional method, it was not possible to obtain a composite of a substrate and an oxide with few defects and satisfying the electrical characteristics.

[0012]

SUMMARY OF THE INVENTION Miniaturization of capacitors,
In order to realize large capacity, chips, on-board, and high-density memory, it is necessary to use a thin film of a high dielectric constant material for the dielectric, and the anticorrosion film has good heat resistance. It is conceivable to use a dense, defect-free oxide film. For that purpose, a technique for forming various kinds of oxide films on various substrates is required.

However, a film formed by a conventional electrophoretic method or a cathodic reaction as in Japanese Patent Application No. 4-72288 has a poor denseness and does not satisfy the electrical characteristics, or has a film defect. It has not been put to practical use because the substrate is oxidized from some parts.

An object of the present invention is to establish a manufacturing method for forming an oxide film which has good heat resistance, is dense, and has no electrical defects on a substrate made of a conductive material.

[0015]

In order to solve the above-mentioned problems, we have made a hydrate or a hydroxide containing a conductive material as a substrate and a metal species or fine particles different from the substrate on the substrate at the cathode. Alternatively, the inventors have invented a new manufacturing method for obtaining a complex consisting of a substrate and a complex oxide by electrodepositing a hydrous material and then oxidizing the electrodeposit and the substrate at the anode.

Specifically, a conductive material is used as a substrate, and the substrate is used as a cathode electrode by electrolyzing in a solution containing metal species or fine particles which are components of a desired dielectric material to form a solution on the substrate. After the metal hydrate or hydroxide of the metal species or fine particles in the film is electrodeposited in the form of a film, this substrate and the electrodeposit are used as the anode electrode, and the electrodeposit is dehydrated by applying electricity in the solution. By oxidizing the substrate and simultaneously oxidizing it, a composite oxide composed of the oxide of the electrodeposit and the oxide of the substrate is obtained, and as a result, a composite of the substrate and the composite oxide is obtained. Note that heat treatment may be performed in the middle or in the final step.

The term "valve metal" used in this specification has the same meaning as that generally used in the field of electrolytic capacitors and the like. When oxidized,
A general term for metals that form a dense oxide film with good insulating properties and cause a phenomenon (valve action) in which the film and the electrolyte pass electrons only in one direction and hardly in the opposite direction. (For example, "Revised Electrical Term Dictionary" edited by the Electrical Term Dictionary Editing Committee, published by Corona Publishing Co., Ltd., "Aluminum Dry Electrolytic Capacitor" by Isaya Nagata, Nihon Condenser Industry Co., Ltd., 1983, etc.). ). The present invention will be described in detail below.

The substrate used in the present invention needs to be a conductive material because it is used as an electrode. For example,
Various metals including stainless steel, Fe, Ni, Cu, etc., conductive oxides such as ITO, or TCNQ
Is a conductive polymer. Among them, Al, Ta,
Valve metals such as Ti, Zr and Hf can be mentioned as preferable examples. When a composite body was prepared by the manufacturing method according to the present invention using such a valve metal, the leakage current of the composite body was a small value of 50 μA / cm ² or less.
Further, it is also preferable to use a silicon wafer as the substrate, and when a composite body was prepared using the same, the leakage current of the composite body was a very small value of 5 μA / cm ² . It is considered that this is because the dielectric strength of the oxide film of the valve metal and the oxide film of the silicon wafer generated by the anode reaction is very large.

The aqueous solution used for the cathode reaction contains a metal species or fine particles other than the substrate, and the metal species and fine particles here are constituent elements of the target dielectric. Cathode reactions are roughly divided into three types depending on the type of the starting material. Specific examples of each are described below.

For example, when a barium titanate film is formed using a soluble metal salt, an aqueous solution containing barium ions and titanium ions is used. The aqueous solution contains a soluble Ba salt such as BaCl ₂ or Ba (NO _3). ) ₂ , B
_{a (CH 3 COO) 2,} Ba (OH) 2 · 8H 2 O and the like,
And soluble Ti salts such as TiCl ₃ , TiCl ₄
And the like are dissolved in water. In particular, Ba (N
When O ₃ ) ₂ and TiCl ₃ were used, the solution was easy to handle and had good characteristics. The composition ratio of the film can be controlled by the solution concentration and the applied potential, and the film thickness depends on the solution concentration and the voltage application time. Since this reaction utilizes the electrolytic reaction at the cathode, the voltage is -10V although the preparation conditions differ depending on the substrate type and the solution type.
VS Ag / AgCl or more and 0 V VS Ag / AgCl or less, and the electrolysis time is preferably within 1 hour. Further, in the case of a solution using a nitrate, precipitation occurs at a high temperature and the liquid composition shifts.

When an organic metal salt such as a metal alkoxide is used, for example, in order to form a titanium dioxide film, a solution containing titanium ethoxide as a solvent and hydrochloric acid as a catalyst is used. The composition ratio can be controlled by the solution concentration ratio. Further, since the film thickness depends on the amount of electric charge during energization, the voltage application time is preferably 10 minutes or less in order to obtain a thin film.

Further, using fine particles, for example, Pb (Zr,
Ti) O ₃ film, Pb (Zr, Ti)
O ₃ fine particles are obtained by a coprecipitation method, and a solution in which these fine particles are uniformly dispersed in an aqueous solvent is used. The composition ratio of the film can be controlled by controlling the composition ratio of the fine particles. Further, since the film thickness depends on the amount of electric charge when energized, the voltage is 20 V / cm ² or less and the voltage application time is 1 to obtain a thin film.
0 minutes or less is desirable.

The film-like electrodeposit obtained by the above cathode reaction is a hydrate, hydroxide or hydrate of metal species or fine particles in the solution used.

The solution used for the anode reaction is a solution containing oxygen ions, such as an aqueous solution or an organic solvent solution. However, a solution that corrodes the substrate, such as a strong acid or strong alkaline solution, cannot be used. Further, the applied voltage in the anode reaction needs to be increased as the film thickness of the electrodeposit synthesized on the cathode increases. If the application time is short, electrical defects cannot be repaired, so it is necessary to apply a voltage for a long time, and at least 30 minutes or more is desirable.

The composite obtained after the anode reaction is a composite of the substrate and the composite oxide of the substrate and the electrodeposit. However, when the electrodeposit obtained by the cathode reaction covers the substrate without any defects, the substrate may not be oxidized.
The composite obtained in that case is a composite of the substrate and the oxide of the electrodeposit.

The components, compositions, etc. of the composite of the substrate and the composite oxide obtained by the production method of the present invention are not particularly limited, and various ones may be selected according to the desired characteristics such as dielectric constant. However, a preferable example is one in which the substrate is a valve metal and the complex oxide is a valve metal oxide and titanium dioxide, or a valve metal oxide and a perovskite type oxide.

The heat treatment may be performed during the cathodic and anodic reactions, or after the anodic reaction, or both.

[0028]

We consider that the drawback of the conventional method is that there is a problem in the method of dehydrating the electrodeposit formed by the cathode reaction.
Moreover, it was considered that the anodic reaction was the most suitable dehydration method.

The conventional electrophoresis method and Japanese Patent Application No. 4-722
Electrodeposits formed on the substrate by the cathode reaction as shown in No. 88 are often assumed to be hydroxides or hydrates or hydrates. This electrodeposit was dried in the air at room temperature, and the composite of the substrate and the film obtained after drying had large power loss and leakage current, and in extreme cases, cracking was not suitable for practical use. It is considered that this is due to dehydration and decomposition caused by drying, resulting in electrical defects and pores, and in extreme cases, cracking. Therefore, we thought that a drying method should be devised to prevent these defects. As a drying method, dehydration / drying in air, vacuum, or gas can be considered. But,
Although it is dehydrated in the air, vacuum or gas,
It is considered that rearrangement for repairing defects is unlikely to occur and is not suitable for practical use.

Therefore, we have considered that the anodic reaction is suitable as a dehydration method. This is because it was thought that the following reaction occurred near the anode. That is, the water contained in the electrodeposit is represented by the formula (2), and the hydroxyl group (OH ⁻ ) contained in the hydroxide (M ^{n +} (OH ⁻ ) _n ) constituting the electrodeposit is (3). The O ⁻ ions decomposed as shown in the formula are used to oxidize the metal species in the anode electrode substrate and the electrodeposit, while the H ⁺ ions diffuse into the solution and disappear from the electrodeposited film. Therefore, as a result, it is considered that dehydration and decomposition proceed at the anode, the metal species in the substrate and the electrodeposit are oxidized, and further rearrangement occurs due to electric energy to repair the defective portion. H ₂ O → O ^{2 −} + 2H ⁺ (2) OH ⁻ → O ² + H ⁺ (3) Repeatedly, however, if the anode reaction is used, water and hydroxyl groups contained in the electrodeposit are decomposed and The sludge is dehydrated and oxidized. At the same time, when an electric defect is present in the film, rearrangement due to electric energy occurs and the defective portion is preferentially repaired, so that a uniform and defect-free oxide film is formed on the substrate. In addition, when the coverage of the electrodeposit is poor and the conductive substrate is exposed due to cracks or the like, the oxide of the substrate is generated in the exposed portion due to the anode reaction. Or it will be completely covered by the oxide of the substrate.

Actually, when an Al substrate and an electrodeposit formed of a hydrate of titanium and a hydroxide of barium formed on the cathode were used as an anode electrode, a film with few defects was obtained by the above effect. . In addition, the resulting complex
When analyzed by R (infrared absorption) or Auger spectroscopy, it was found that the oxide film contained the oxide of the substrate depending on the conditions to be created. That is, the production method according to the present invention is not limited to simple dehydration and decomposition, but also because the element contained in the substrate diffuses into the electrodeposit, and the element contained in the electrodeposit diffuses into the substrate. It can be said that a complex oxide composed of the elements contained in the substrate and the electrodeposit was prepared.

In other words, for example, in the conventional method, the other metal ions could be mixed in the anodic oxide film of Al, which is one of the valve metals, only in the ppm order. For the first time, it is possible to mix other metals with% order. Such a composite can be used for applications different from capacitors, memories, and anticorrosion coatings, for example, EC materials and sensor materials.

According to the present invention, a composite having a dense film and excellent in electrical characteristics can be obtained. By using this composite, the capacitor can be miniaturized, the capacity can be increased, the on-board can be realized, and the memory can be improved. Enables densification. The film according to the present invention can also be used as a film for anticorrosion.

[0034]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 An Al foil having a thickness of 100 μm washed in dilute nitric acid for 10 minutes was used as a cathode electrode, and the projected area in the electrolytic solution was set to be 1 cm ² . Similarly, washed Pt was used as an anode electrode, and 0.15 mol / l of Ba (N
O _{3) 2} and 0.025 mol / l mixed aqueous solution of about 300ml of TiCl ₃ in an electrolyte solution, a constant potential -5.0 V V.
Voltage was applied for 10 seconds with S. Ag / AgCl. In addition,
The pH of the electrolytic solution at this time was 1.3. As a result, A
A white film-like electrodeposit was formed on the 1 substrate, and it was confirmed by Auger spectroscopy and IR that it was a hydrate of Ti and hydroxides of Ba and Ti. Next, the composite consisting of the Al substrate used as the cathode electrode and the electrodeposit was used as the anode electrode, and the cathode electrode was washed Pt,
10 in an aqueous solution of 100 g / l ammonium adipate
A voltage of 0V was applied for 1 hour. At this time, the temperature of the solution is 9
It was 0 ° C. As a result, the film thickness is 200n on the Al substrate.
m film was obtained. This was confirmed to be amorphous by X-ray analysis, and it was found from Auger spectroscopy results that this film was an oxide of Ba, Ti, and Al. The leakage current of this composite was ² μA / cm ² and the capacitance was 500 nF.

Example 2 In the same setting as in Example 1, a substrate prepared by depositing ITO, which is a conductive oxide, on silica glass by sputtering was used as an electrode on the cathode side. 0.3 mol / l
Of Sr (NO ₃ ) ₂ and 0.15 mol of Sr (CH ₃ C
Voltage was applied at a constant potential of −2V VS Ag / AgCl for 1 minute in a mixed aqueous solution of OO) ₂ and 0.1 mol / l of TiCl ₃ . The electrodeposits obtained at this time were hydroxides of Sr and Ti. After that, when a voltage of 200 V was applied for 2 hours in a boric acid aqueous solution using the substrate and the electrodeposit as an anode electrode, a SrTiO ₃ film of 300 nm was formed.
The leakage current of this film was 50 μA / cm ² .

Example 3 In the same setting as in Example 1, stainless steel (Fe-20Cr-5Al) was used for the cathode side electrode,
10 g of titanium ethoxide was dissolved in 300 cc of ethanol, and a voltage of 2.5 V / cm ² was applied for 1 minute with an electrolytic solution to which 1 g of hydrochloric acid and 2 cc of water were added. The electrodeposits obtained at this time were a hydrate of TiO ₂ and a hydrate of Ti. Then, using the substrate and the electrodeposit as the anode electrode,
After applying a voltage of 100 V in an aqueous solution of ammonium phosphate for 1 hour, heat treatment was performed at 500 ° C. for 1 hour, and further applying a voltage of 100 V in an aqueous solution of ammonium phosphate for 1 hour, TiO ₂ and Al ₂ O _{3 of} 200 nm were formed. A film consisting of The leakage current of this film is 50 μA /
It was cm ² .

[0037]

INDUSTRIAL APPLICABILITY The present invention is a completely new production method in which a conductive material is used as a substrate, a cathode is used to form a composite of the substrate and an electrodeposit, and the anode is dehydrated and oxidized. According to the present invention, a dense film having various dielectric constants is formed on a substrate, and a composite having excellent electrical characteristics can be obtained. By using this composite, it is possible to reduce the size of the capacitor, increase the capacity of the capacitor, make it on-board, and increase the density of the memory, and the film produced by the present invention is also effective as an anticorrosion film.

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[Procedure amendment]

[Submission date] July 22, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

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[Correction method] Change

[Correction content]

A DRAM which is a semiconductor memory device
(Writable memory that requires a memory holding operation) is a device including an ultrathin dielectric film formed on a silicon wafer as a part. The most basic structure of this main part is a silicon wafer on which silicon dioxide is formed by thermal oxidation or the like. At present, a silicon wafer that is etched to increase the surface area and has a larger surface area is used for general-purpose products. Recently, research has been conducted to form a material film having a larger relative dielectric constant instead of silicon dioxide (having a relative dielectric constant of about 4) in order to further increase the density. Therefore, in order to further increase the density, it is necessary to have a technique for forming various types of dielectric thin films regardless of the substrate type.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Examples of materials having a high relative dielectric constant include complex oxides having a perovskite structure such as barium titanate and oxides such as titanium dioxide. Conventionally, as a method of forming such a film on various substrates, there are a sputtering method and a sol-gel method.

[Procedure 3]

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[Correction method] Change

[Correction content]

The method using a metal alkoxide utilizes hydrolysis or polycondensation reaction of a metal alkoxide, and uses a metal alkoxide of Ba, Ti or Sr and dip-coats a barium titanate or strontium titanate film. Has been successfully synthesized. However, this film was not suitable for practical use because it was too thick as several μm and had electrical defects and large power loss and leakage current.
The method using fine particles is the coprecipitation method or metal alkoxide
The obtained fine particles are formed into a film by an electrophoresis method.
The film thickness of TiO _{2 obtained} by this method is too thick, such as several tens of μm.
It was not suitable for practical use because it had some electrical defects.

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Incidentally, the term "valve metal" used in the present specification generally means electrolytic capacitor.
Is of the same meaning as that used in the support areas such, when the anodized metal in an electrolytic bath, a dense insulating good oxide film formed, this film and the electrolyte solution is an electronic It is a general term for metals that cause a phenomenon (valve action) that passes through in only one direction and hardly in the opposite direction (for example, "Revised Electrical Glossary").
Electric Term Dictionary Editing Committee, published by Corona Publishing Co., Ltd.
"Aluminum dry electrolytic capacitor" by Isaya Nagata
Issued by Japan Electric Storage Industry Co., Ltd. See 1983. ). The present invention will be described in detail below.

[Procedure Amendment 5]

[Document name to be amended] Statement

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[Correction method] Change

[Correction content]

For example, when a barium titanate film is formed using a soluble metal salt, an aqueous solution containing barium ions and titanium ions is used. The aqueous solution contains a soluble Ba salt such as BaCl ₂ or Ba (NO _3). ) ₂ , B
_{a (CH 3 COO) 2,} Ba (OH) 2 · 8H 2 O and the like,
And soluble Ti salts, eg TiCl ₃ , TiC
It can be obtained by dissolving l ₄ , Ti (SO ₄ ) _{2 and the} like in water. In particular, when Ba (NO ₃ ) ₂ or TiCl ₃ was used, the solution was easy to handle and had good characteristics. The composition ratio of the film can be controlled by the solution concentration and the applied potential, and the film thickness depends on the solution concentration and the voltage application time. Since this reaction utilizes the electrolytic reaction at the cathode, although the preparation conditions differ depending on the substrate type and solution type,
Voltage is -10V VS Ag / AgCl or more 0V
VS Ag / AgCl or less, and the electrolysis time is preferably within 1 hour. Further, in the case of a solution using a nitrate, precipitation occurs at a high temperature and the liquid composition shifts.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

When an organic metal salt such as a metal alkoxide is used, for example, in order to form a titanium dioxide film, a solution containing titanium ethoxide as a solvent and hydrochloric acid as a catalyst is used. The composition ratio can be controlled by the solution concentration ratio. Further, since the film thickness depends on the amount of charge when energized, to obtain a thin film, the voltage application time is preferably 10 minutes or less.

[Procedure Amendment 7]

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[Correction method] Change

[Correction content]

Therefore, we have considered that the anodic reaction is suitable as a dehydration method. This is because it was thought that the following reaction occurred near the anode. That is, the water contained in the electrodeposit is represented by the formula (2), and the hydroxyl group (OH ⁻ ) contained in the hydroxide (M ^{n +} (OH ⁻ ) _n ) constituting the electrodeposit is (3). The O ²⁻ ion decomposed as shown in the formula is used to oxidize the metal species in the anode electrode substrate and the electrodeposit, while the H ⁺ ion diffuses into the solution and disappears from the electrodeposited film. Therefore, as a result, it is considered that dehydration and decomposition proceed at the anode, the metal species in the substrate and the electrodeposit are oxidized, and further rearrangement occurs due to electric energy to repair the defective portion. H ₂ O → O ^{2 −} + 2H ⁺ (2) OH ⁻ → O ² + H ⁺ (3) Repeatedly, however, if the anode reaction is used, water and hydroxyl groups contained in the electrodeposit are decomposed and The sludge is dehydrated and oxidized. At the same time, when an electric defect is present in the film, rearrangement due to electric energy occurs and the defective portion is preferentially repaired, so that a uniform and defect-free oxide film is formed on the substrate. In addition, when the coverage of the electrodeposit is poor and the conductive substrate is exposed due to cracks or the like, the oxide of the substrate is generated in the exposed portion due to the anode reaction. Or it will be completely covered by the oxide of the substrate.

[Procedure Amendment 8]

[Document name to be amended] Statement

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[Correction method] Change

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[0034]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 An Al foil having a thickness of 100 μm washed in dilute nitric acid for 10 minutes was used as a cathode electrode, and the projected area in the electrolytic solution was set to be 1 cm ² . Similarly, washed Pt was used as an anode electrode, and 0.15 mol / l of Ba (N
O _{3) 2} and 0.025 mol / l mixed aqueous solution of about 300ml of TiCl ₃ in an electrolyte solution, a constant potential -5.0 V V.
Voltage was applied for 10 seconds with S. Ag / AgCl. In addition,
The pH of the electrolytic solution at this time was 1.3. As a result, A
A white film-like electrodeposit was formed on the 1 substrate, and it was confirmed by Auger spectroscopy and IR that it was a hydrate of Ti and hydroxides of Ba and Ti. Next, the composite consisting of the Al substrate used as the cathode electrode and the electrodeposit was used as the anode electrode, and the cathode electrode was washed Pt,
10 in an aqueous solution of 100 g / l ammonium adipate
A voltage of 0V was applied for 1 hour. At this time, the temperature of the solution is 9
It was 0 ° C. As a result, the film thickness is 200n on the Al substrate.
m film was obtained. This was confirmed to be amorphous by X-ray diffraction , and from the result of Auger spectroscopy, it was found that this film was an oxide of Ba, Ti, and Al. The leakage current of this composite was ² μA / cm ² and the capacitance was 500 nF.

Claims (2)

[Claims] 1. A conductive material is used as a substrate, the substrate is used as a cathode electrode, and electrolysis is performed in an aqueous solution containing at least one metal species or fine particles different from that of the substrate, whereby the metal species in the solution or After electrodepositing the hydrates or hydroxides or hydrates of the microparticles, the substrate and the electrodeposits described above are used as the anode electrode to conduct electricity in the solution to dehydrate and oxidize the electrodeposits, and at the same time to remove the substrate. A method for producing a composite comprising a substrate, an electrodeposit and a composite oxide of the substrate by oxidation. 2. The composite according to claim 1, wherein the substrate is a valve metal and the complex oxide is a valve metal oxide and titanium dioxide, or a valve metal oxide and a perovskite type oxide. Manufacturing method for obtaining.