JPH07232961A - Preparation of oxide thin film - Google Patents

Abstract

PURPOSE:To stably prepare a uniform oxide ferroelectric thin film or oxide dielectric thin film useful for a thin film capacitor, a piezoelectric body, and a pyroelectric body, etc., and excellent in stoichiometry. CONSTITUTION:In this preparing method of an oxide thin film expressed by the formula (BaxSr1-x)TiO3 (0<=x<=1), each of metallic alkoxide compds. expressed by the formula Ba(OR<3>)2, Ti(OR<4>)4 and Sr(OR<5>)2 (in the formula, R<3>, R<4> and R<5> are respectively an aliphat. hydrocarbon groups) is added and mixed simultaneously or in a arbitrary order to and with a solvent expressed by the formula R<1>OR<2>OH (in the formula, R<1> is the aliphat. hydrocarbon group, R<2> is a divalent aliphat. hydrocarbon group which may have an ether bond), and the result is subjected to heating reaction, and the obtained soln. of mixture is applied on a substrate to form the thin film, then heat treated. When R<1> is methyl group, the metallic alkoxide compd. of the formula Ba(OR<3>)2 is added, allowed to react, then other metallic alkoxide compd. is added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an oxide ferroelectric thin film or an oxide paraelectric thin film which can be used for a thin film capacitor, a piezoelectric body, a pyroelectric body and the like.

[0002]

2. Description of the Related Art Ferroelectric thin films are used in many fields of electronics due to many properties of ferroelectrics such as ferroelectricity, piezoelectricity, pyroelectricity and electro-optic effect, and in recent years, they have been used in DRAMs. The application to memory cells is drawing attention with the rapid development of integration. Among these, barium strontium titanate has a higher relative permittivity than strontium titanate, and it is possible to change the Curie temperature by the composition ratio of barium and strontium, so that it can be used as a paraelectric at the operating temperature of the device. It is a particularly promising material. Conventionally, as a method for manufacturing an oxide thin film, a method such as film formation by a dry process such as a sputtering method or a vacuum evaporation method, or film formation by a wet process such as a sol-gel method has been adopted.

However, in the case of film formation by a dry process, the apparatus used is very expensive, and the vapor pressure is different for each element, so that a thin film excellent in stoichiometry cannot be stably manufactured. However, there are drawbacks such as poor crystallinity, low productivity and high cost, which are far from practical use. On the other hand, when a film is formed by a wet process, for example, the sol-gel method using an organometallic compound, precise chemical composition control, molecular level uniformity,
There are advantages in terms of low process temperature, large area, and low equipment cost. However, in the conventional sol-gel method, since a lower alcohol such as methanol or ethanol is mainly used as a solvent, the solution of the organometallic compound is extremely unstable and easily absorbs water in the atmosphere to be hydrolyzed. Therefore, it is difficult to form a uniform thin film. Further, since the vapor pressure of these lower alcohols is high, it is difficult to form a thin film having a uniform thickness because the film after coating is dried quickly in spin coating or the like. In recent years, for example, J. Am. Ceram. So
c. , 71, (5), C-280 (1988), etc.
It has been shown to use ethylene glycol monomethyl ether in the preparation of a ferroelectric thin film of lead titanate or the like, which is represented by the general formula (Ba _x Sr _1-x ) TiO ₃ (0
When used as a solvent for synthesizing an oxide thin film represented by ≦ x ≦ 1), there is a problem that an organometallic compound of Ba and an organometallic compound of Ti selectively react with each other to cause precipitation. In addition, Advanced Ceramic M
materials, 3, (2), 183 (1988) and the like describe that barium acetate is dissolved in an aqueous acetic acid solution and mixed with titanium isopropoxide, but in this method, titanium isopropoxide and acetic acid are mixed. A reaction product is likely to form a precipitate. In addition, in order to achieve precise control and uniformity of composition, it is necessary to synthesize a complex alkoxide with a controlled metal atom ratio as a precursor, but since water is added to the raw material, the precursor solution Was unstable and it was difficult to control the chemical composition of the precursor.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. That is, an object of the present invention is to use an organometallic compound on a substrate to form a thin film capacitor, a piezoelectric body, a pyroelectric body, or the like, which is a uniform and highly stoichiometric oxide ferroelectric thin film or oxide. It is to provide a method for stably producing a paraelectric thin film.

[0005]

DISCLOSURE OF THE INVENTION As a result of investigations, the present inventors have found that the general formula (Ba _x Sr _1-x ) TiO ₃ (0 ≦ x ≦ 1)
In the method for producing an oxide thin film represented by
r, an organometallic compound each containing a Ti component are dissolved in a specific solvent, or they are dissolved in a specific solvent in a specific order, the resulting mixed solution is applied on a substrate to form a thin film, Then by pyrolysis followed by crystallization,
It was found that an oxide thin film having a uniform and excellent stoichiometry can be prepared.

The first aspect of the present invention is the general formula (Ba _x S
r _1-x ) TiO ₃ (0 <x ≦ 1), which relates to a method for producing an oxide thin film represented by the following general formula (IA)
R ^{1 ′} OR ² OH (IA) (wherein R ^{1 ′} represents an aliphatic hydrocarbon group having 2 or more carbon atoms, and R ² may have an ether bond). Represents a divalent aliphatic hydrocarbon group.) The following general formulas (II) and (III
) Or two metal alkoxide compounds represented by the general formulas (II) to (IV) as Ba (OR ³ ) ₂ (II) Ti (OR ⁴ ) ₄ (III) Sr. (OR ⁵ ) ₂ (IV) (In the formula, each of R ³ , R ⁴ and R ⁵ represents an aliphatic hydrocarbon group.) Either simultaneously or in any order, added and mixed, and then reacted by heating to obtain The method is characterized in that the obtained mixed solution is applied onto a substrate to form a thin film, and then heat treatment is performed.

The second aspect of the present invention is the general formula (Ba _x S
r _1-x ) TiO ₃ (0 <x <1), which relates to a method for producing an oxide thin film represented by the following general formula (IB)
CH ₃ OR ^{2 ′} OH (IB) (wherein R ^{2 ′} represents a divalent aliphatic hydrocarbon group) in a solvent represented by a barium alkoxide compound represented by the following general formula (II): After dissolution and heating reaction, Ba (OR ³ ) ₂ (II) (In the formula, R ³ represents an aliphatic hydrocarbon group.) Then, two kinds of compounds represented by the following general formulas (III) and (IV) are represented. A metal alkoxide compound is added and reacted to obtain Ti (OR ⁴ ) ₄ (III) Sr (OR ⁵ ) ₂ (IV) (in the formula, R ⁴ and R ⁵ each represent an aliphatic hydrocarbon group). It is characterized in that the obtained mixed solution is applied onto a substrate to form a thin film, and then heat treatment is performed.

A third aspect of the present invention relates to a method for producing an oxide thin film represented by SrTiO ₃ , which comprises the following general formula (I) R ¹ OR ² OH (I) (wherein R ¹ is Represents an aliphatic hydrocarbon group, and R ² represents a divalent aliphatic hydrocarbon group which may have an ether bond.) Two metal alkoxides represented by the following general formulas (III) and (IV) The compounds are added simultaneously or in any order and mixed, and then reacted by heating to produce Ti (OR ⁴ ) ₄ (III) Sr (OR ⁵ ) ₂ (IV) (wherein R ⁴ and R ⁵ are each a fat It represents a group hydrocarbon group.) The obtained mixed solution is applied onto a substrate to form a thin film, and then heat treated.

The present invention will be described in detail below. In the present invention, the metal alkoxide compound used is selected from those represented by the following general formulas (II), (III) and (IV). Ba (OR ³ ) ₂ (II) Ti (OR ⁴ ) ₄ (III) Sr (OR ⁵ ) ₂ (IV) (In the formula, R ³ , R ⁴ and R ⁵ each represent an aliphatic hydrocarbon group. ) As R ³ , R ⁴ and R ^{5 in the} general formulas (II), (III) and (IV), an alkyl group having 1 to 4 carbon atoms is preferable, and specific metal alkoxide compounds include barium dimethoxide. , Barium diethoxide,
Examples include barium dipropoxide, barium dibutoxide, strontium dimethoxide, strontium diethoxide, strontium dipropoxide, strontium dibutoxide, titanium tetramethoxide, titanium tetraethoxide, titanium tetrapropoxide, titanium tetrabutoxide and the like. However, the present invention is not limited to these.

The solvent used in the present invention is represented by the following general formula (I). R ¹ OR ² OH (I) (In the formula, R ¹ represents an aliphatic hydrocarbon group, and R ² represents a divalent aliphatic hydrocarbon group which may have an ether bond.) Of R ¹ As the aliphatic hydrocarbon group, an alkyl group having 1 to 4 carbon atoms is preferable, and as R ² , a divalent aliphatic hydrocarbon group which may have an ether bond is an alkylene group having 2 to 4 carbon atoms. , A divalent group having a total of 4 to 8 carbon atoms in which an alkylene group having 2 to 4 carbon atoms is bonded by an ether bond is preferable. Specifically, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether and other ethylene glycol monoalkyl ethers, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether. Diethylene glycol monoalkyl ethers such as ethers,
1,2-propylene glycol monoalkyl ethers such as 1,2-propylene glycol monomethyl ether, 1,3-propylene glycol monomethyl ether, 1,3-propylene glycol monoethyl ether, 1,3-propylene glycol monopropyl ether, etc. 1,3-Propylene glycol monoalkyl ethers and the like, but are not limited thereto. These may be used alone or in combination of two or more. Among these, examples of the solvent represented by the general formula (IB) include ethylene glycol monomethyl ether and 1,3-propylene glycol monomethyl ether.

In the present invention, the above general formulas (II) and (II
The metal alkoxide compounds represented by I) and (IV) are added to and dissolved in the solvent represented by the general formula (I) at the same time or in any order, and heated to react. In this case, when R ¹ in the general formula (I) represents a methyl group as the solvent, that is, when the solvent represented by the general formula (IB) is used, pay attention to the addition order of the metal alkoxide. There must be. That is, first, the barium alkoxide compound represented by the general formula (II) is added and dissolved, and the mixture is heated and reacted. As a result, the Ba ligand is replaced with the solvent. Then, the metal alkoxide compound containing Ti represented by the general formula (III) and the metal alkoxide compound containing Sr represented by the general formula (IV) are added to this solution. If the addition order is not as described above, precipitation occurs in the solution and it becomes impossible to obtain a homogeneous mixed solution. In the case of producing an oxide thin film represented by BaTiO ₃ , SrTiO _{3 is} prepared by using two kinds of metal alkoxide compounds represented by the general formulas (II) and (III).
In the case of producing the oxide thin film represented by, the two kinds of metal alkoxide compounds represented by the general formulas (III) and (IV) may be used. It is effective that the mixed solution obtained as described above is further treated by distillation or reflux to form a composite alkoxide as a precursor.

The mixed solution obtained by reacting the metal alkoxide compound as described above is coated on a substrate to form a thin film, and then heat treated. In this case, the mixed solution may be hydrolyzed and then applied on the substrate. As the substrate, any substrate can be used as long as it can be applied to the intended element, for example,
ITO / SiO ₂ glass, Pt / Ti / SiO ₂ / Si
Etc. can be used. As a method of applying this solution onto a substrate, a spin coating method, a dipping method, a spray method,
A screen printing method, an inkjet method, or the like can be used.

The coated substrate is heat-treated. That is, the substrate is heated at a heating rate of 0.1 to 500 ° C./sec, the coating layer is thermally decomposed in a temperature range of 100 ° C. to 500 ° C. where crystallization does not occur, and then 0.1 to 500 ° C./sec. The substrate is heated at a heating rate of 1 to crystallize the oxide thin film in the temperature range of 300 ° C to 1200 ° C. When the coating is repeated, the substrate is heated at a heating rate of 0.1 to 500 ° C./second after the coating, and the coating layer is thermally decomposed in a temperature range of 100 ° C. to 500 ° C. where crystallization does not occur. After repeating this coating and thermal decomposition a predetermined number of times, the oxide thin film is crystallized in the temperature range of 300 ° C to 1200 ° C. An oxide thin film is formed by this heat treatment.

The heat treatment temperature during film formation is 500 to 12
When the temperature is in the range of 00 ° C., the mixed solution obtained as described above is applied to the substrate in a state where water or a catalyst is not added (that is, in a state where it is not hydrolyzed) and heat treatment is performed. Is preferred. This is because it is more preferable to use it in a non-hydrolyzed state in terms of electrical characteristics, especially leakage current characteristics.

[0015]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Example 1 Ba (OC ₂ H ₅ ) ₂ was dissolved in ethylene glycol monomethyl ether dehydrated with molecular sieves to obtain a 0.6 M concentration solution. 1 with stirring this solution
Distill at 25 ° C for 2 hours, reflux for another 22 hours,
a (OC ₂ H ₄ OCH ₃ ) ₂ was obtained. To this solution, Sr (OC ₂ H ₅ ) ₂ and Ti (Oi-C ₃ H ₇ ) ₄ were added so that the molar ratio of Ba, Sr, and Ti was 0.5: 0.5: 1. A solution having a concentration of 0.6M was prepared. Next, this solution was distilled at 125 ° C. for 2 hours while stirring, and refluxed for another 22 hours to obtain a complex alkoxide: (Ba _0.5 Sr _0.5 ) Ti.
(OC ₂ H ₄ OCH ₃ ) ₆ was obtained. This alcohol substitution reaction was confirmed by ¹ H NMR spectrum. This solution was a uniform, light brown, transparent liquid without any precipitate. This solution was spin-coated on an ITO / SiO ₂ glass substrate and subsequently heated at a rate of 10 ° C./sec for 30
Hold at 0 ° C. for 2 minutes and 700 ° C. for 1 hour. (Ba _0.5 Sr _0.5 ) T composed of the obtained perovskite single phase
The surface of the iO ₃ thin film was optically smooth and transparent.

Comparative Example 1 Ba (OC ₂ H ₅ ) ₂ , Sr (OC ₂ H ₅ ) ₂ and Ti
_{(O-i-C 3 H} 7) 4 and Ba and Sr and the molar ratio of Ti is 0.5: 0.5: to be 1, ethylene glycol monomethyl ether which had been dehydrated by molecular sieve, and dissolved at the same time To give a solution having a concentration of 0.6 M, which was then distilled with stirring at 125 ° C. for 2 hours and further refluxed for 22 hours. When this solution was allowed to stand at room temperature for a while, a precipitate was formed and a uniform solution was not obtained. As a result of the analysis, a large amount of Ba and Ti was detected in the precipitate, and a large amount of Sr was detected in the solution rather than the composition ratio of the charge. From this analysis result, it was found that the precursor of excellent stoichiometry could not be synthesized by the method of this comparative example.

[0017] with a solution of 0.6M concentration by dissolving Example 2 Ti (O-i-C 3 H 7) 4 ethylene glycol monoethyl ether which had been dehydrated by molecular sieve, the solution, with stirring 1
Distilled at 35 ° C. for 2 hours. Ba, Sr and Ti in this solution
So that the molar ratio of Ba (O−) becomes 0.6: 0.4: 1.
i-C ₃ H ₇ ) ₂ and Sr (OC ₂ H ₅ ) ₂ are added to 0.6
A solution of M was obtained. This solution is then stirred at 135 ° C.
The mixture was distilled for 2 hours, and refluxed for another 22 hours to obtain a complex alkoxide: (Ba _0.6 Sr _0.4 ) Ti (OC ₂ H ₄ O
C ₂ H ₅ ) ₆ was obtained. This alcohol substitution reaction is ¹ H
Confirmed by NMR spectrum. This solution was a transparent liquid that was uniform and light brown with no precipitate. This solution was spin-coated on an ITO / SiO ₂ glass substrate, subsequently heated at a rate of 10 ° C./sec, and held at 300 ° C. for 2 minutes and 700 ° C. for 1 hour. Obtained film thickness 0.1 μm
The (Ba _0.6 Sr _0.4 ) TiO ₃ thin film was composed of a perovskite single phase, and its surface was optically smooth and transparent.

Comparative Example 2 Ba (OC ₂ H ₅ ) ₂ , Sr (OC ₂ H ₅ ) ₂ and Ti
The _{(O-i-C 3 H} 7) 4, the molar ratio of Ba and Sr and Ti 0.6: 0.4: to be 1, was dissolved at the same time ethylene glycol monomethyl ether which had been dehydrated by molecular sieve As a result, a solution having a concentration of 0.6 M was prepared, distilled with stirring at 125 ° C. for 2 hours, and further refluxed for 22 hours. When this solution was allowed to stand at room temperature for a while, a metal-colored precipitate was formed, and a uniform solution was not obtained. As a result of the analysis, a large amount of Ba and Ti was detected in the precipitate, and a large amount of Sr was detected in the solution rather than the composition ratio of the charge. From this analysis result, it was found that the precursor of excellent stoichiometry could not be synthesized by the method of this comparative example.

[0019] and Example 3 Ti (O-i-C 3 H 7) 4 was dissolved in ethylene glycol monoethyl ether which had been dehydrated by molecular sieve of 0.6M concentrated solutions. 1 with stirring this solution
Distilled at 35 ° C. for 2 hours. The molar ratio of Ba and Ti in the solution is 1: 1 so as to _{Ba (O-i-C 3} H 7) 2 was added to obtain a solution of 0.6M concentration. Next, this solution was distilled at 135 ° C. for 2 hours with stirring, and further refluxed for 18 hours to perform complex alkoxide: BaTi (OC ₂ H ₄ OC ₂
H ₅ ) ₆ was obtained. This alcohol substitution reaction is ¹ H NM
Confirmed by R spectrum. This solution was a transparent liquid that was uniform and light brown with no precipitate. Further, water was added to this solution so that the molar ratio with Ba was 1: 1 to obtain a uniform partial hydrolysis solution. This solution is Pt / Ti /
Spin coating on SiO ₂ / Si substrate followed by 10 ° C
Heating at a speed of s / sec, 350 ° C. for 2 minutes and 700
Hold at 30 ° C for 30 minutes. The obtained ferroelectric thin film BaTiO ₃ having a film thickness of 0.1 μm consists of a perovskite single phase,
The surface was optically smooth and transparent.

Comparative Example 3 Ba (OC ₂ H ₅ ) ₂ and Ti (Oi-C ₃ H ₇ ) ₄ were added to B
Simultaneously dissolve in ethylene glycol monomethyl ether dehydrated with molecular sieves so that the molar ratio of a to Ti is 1: 1 to obtain a solution of 0.6M concentration, and distill at 125 ° C. for 2 hours with stirring, Reflux for an additional 22 hours. When this solution was allowed to stand at room temperature for a while, a large amount of precipitate was formed, and a uniform solution was not obtained.

Example 4 Sr (OC ₂ H ₅ ) ₂ and Ti (Oi-C ₃ H ₇ ) ₄ were added to S
Simultaneously dissolved in ethylene glycol monomethyl ether dehydrated with molecular sieves so that the molar ratio of r and Ti is 1: 1 to obtain a 0.5 M concentration solution, which is distilled for 2 hours at 125 ° C. with stirring, The mixture was refluxed for another 22 hours, and the composite alkoxide: SrTi (OC ₂ H ₄ OC
H ₃ ) ₆ was obtained. This alcohol substitution reaction is ¹ H NM
Confirmed by R spectrum. This solution was a transparent liquid that was uniform and light brown with no precipitate. This solution is Si
The substrate was spin-coated, then heated at a rate of 10 ° C./sec and held at 300 ° C. for 2 minutes and 700 ° C. for 1 hour. The obtained SrTiO ₃ thin film having a thickness of 0.1 μm consisted of a perovskite single phase, and its surface was optically smooth and transparent.

Example 5 Composite alkoxide obtained in Example 4: SrTi
A solution containing (OC ₂ H ₄ OCH ₃ ) ₆ was spin-coated on an ITO / glass substrate, subsequently heated at a rate of 10 ° C./sec, and held at 300 ° C. for 2 minutes and 600 ° C. for 30 minutes. . Furthermore, when Pt was attached to this thin film and the leak current was measured, it was about 1 at an applied voltage of 2V.
It was × 10 ^-6 A / cm ² .

Example 6 Composite alkoxide obtained in Example 4 above: Sr
Water was added to a solution containing Ti (OC ₂ H ₄ OCH ₃ ) _{6 so} that the molar ratio with Ti was 1: 1 to obtain a uniform partially hydrolyzed solution. This solution was spin-coated on an ITO / glass substrate and subsequently heated at a rate of 10 ° C./sec for 3 times.
Hold at 00 ° C for 2 minutes and 600 ° C for 30 minutes. Further, Pt was attached on this thin film, and the leak current was measured. At an applied voltage of 2 V, about 1 × 10 ⁻⁵ A /
It was cm ² .

Example 7 Sr (OC ₂ H ₅ ) ₂ and Ti (Oi-C ₃ H ₇ ) ₄ were added to S
Simultaneously dissolve in ethylene glycol monoethyl ether dehydrated by molecular sieve so that the molar ratio of r and Ti is 1: 1 to obtain a solution of 0.6M concentration, and distill at 135 ° C for 2 hours with stirring. After refluxing for another 22 hours, the composite alkoxide: SrTi (OC ₂ H ₄ OC
₂ H ₅ ) ₆ was obtained. This alcohol substitution reaction is ¹ H N
Confirmed by MR spectrum. This solution was a transparent liquid that was uniform and light brown with no precipitate. This solution is I
Spin coating on TO / glass followed by heating at a rate of 10 ° C / sec for 2 minutes at 300 ° C and 3 at 600 ° C.
Hold for 0 minutes. Further, when Pt was attached to the obtained thin film and the leak current was measured, it was about 5 × 10 ⁻⁷ A / cm ² at an applied voltage of 2V.

Example 8 Composite alkoxide obtained in Example 7: SrTi
Water was added to the solution containing (OC ₂ H ₄ OC ₂ H ₅ ) _{6 so} that the molar ratio with Ti was 1: 1 to obtain a uniform partially hydrolyzed solution. This solution was spin-coated on an ITO / glass substrate and subsequently heated at a rate of 10 ° C./sec to give 30
Hold at 0 ° C for 2 minutes and 600 ° C for 30 minutes. Further, Pt was attached to this thin film, and the leak current was measured. As a result, at an applied voltage of 2 V, about 5 × 10 ⁻⁶ A / c
It was m ² .

[0026]

INDUSTRIAL APPLICABILITY The present invention uses a mixed solution prepared by adding a metal alkoxide compound containing Ba, Sr, and Ti components to the solvent represented by the general formula (I) as described above, and using a solvent When the compound represented by the general formula (IB) is used as the compound, a mixed solution prepared by adding the metal alkoxide compounds in a specific order is used, and thus the compound represented by the general formula (Ba _x Sr _{1 -x} ) TiO ₃ (0
The oxide thin film represented by ≦ x ≦ 1) is uniform and excellent in stoichiometry, and can be used as an oxide thin film that can be used for a thin film capacitor, a piezoelectric body, a pyroelectric body and the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/314 A 7352-4M 21/316 S 7352-4M

Claims (3)

[Claims] 1. A general formula (Ba _x Sr _1-x ) TiO ₃ (0
In the method for producing an oxide thin film represented by <x ≦ 1),
R ^{1 ′} OR ² OH (I-A) (in the formula, R ^{1 ′} represents an aliphatic hydrocarbon group having 2 or more carbon atoms, and R ² is an ether). Represents a divalent aliphatic hydrocarbon group which may have a bond.) The following general formulas (II) and (III
) Or two metal alkoxide compounds represented by the general formulas (II) to (IV) as Ba (OR ³ ) ₂ (II) Ti (OR ⁴ ) ₄ (III) Sr. (OR ⁵ ) ₂ (IV) (In the formula, each of R ³ , R ⁴ and R ⁵ represents an aliphatic hydrocarbon group.) Either simultaneously or in any order, added and mixed, and then reacted by heating to obtain A method for producing an oxide thin film, which comprises applying the obtained mixed solution onto a substrate to form a thin film, and then performing heat treatment. 2. The general formula (Ba _x Sr _1-x ) TiO ₃ (0
In the method for producing an oxide thin film represented by <x <1),
CH ₃ OR ^{2 ′} OH (I-B) (wherein R ^{2 ′} represents a divalent aliphatic hydrocarbon group) in a solvent represented by the following general formula (IB): A barium alkoxide compound represented by the formula (1) is dissolved and reacted by heating, and Ba (OR ³ ) ₂ (II) (in the formula, R ³ represents an aliphatic hydrocarbon group), and then the following general formulas (III) and ( IV) two kinds of metal alkoxide compounds are added and reacted, and Ti (OR ⁴ ) ₄ (III) Sr (OR ⁵ ) ₂ (IV) (in the formula, R ⁴ and R ⁵ are each an aliphatic group). It represents a hydrocarbon group.) A method for producing an oxide thin film, which comprises applying the obtained mixed solution onto a substrate to form a thin film, and then performing heat treatment. 3. A method of producing an oxide thin film represented by SrTiO ₃ , wherein R ¹ OR ² OH (I) (wherein R ¹ is an aliphatic hydrocarbon group) in a solvent represented by the following general formula (I): And R ² represents a divalent aliphatic hydrocarbon group which may have an ether bond.) Two kinds of metal alkoxide compounds represented by the following general formulas (III) and (IV) are simultaneously or optionally used. And mixed by heating in the following order: Ti (OR ⁴ ) ₄ (III) Sr (OR ⁵ ) ₂ (IV) (In the formula, R ⁴ and R ⁵ are each an aliphatic hydrocarbon group; The method for producing an oxide thin film is characterized in that the obtained mixed solution is applied onto a substrate to form a thin film, and then heat treatment is performed.