JP2001233604A - Application solution for forming thin oxide film, method for producing the same and method for producing thin oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an application solution, excellent in film-forming properties, moisture resistance and stability for a long time, giving a coating film capable of being baked at a low temperature after film formation and capable of forming a thin oxide film having good film properties. SOLUTION: In preparing an application solution containing a metal oxide or its precursor by hydrolyzing a metal alkoxide, the metal alkoxide is hydrolyzed in an organic solvent containing an alkoxyalcohol with water in 0.1-10 molar ratio to the metal alkoxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid for forming an oxide thin film used for forming an oxide thin film such as a dielectric thin film, a conductive thin film, a piezoelectric thin film, and a semiconductor thin film by a liquid phase method. The present invention also relates to a method for producing the coating liquid and a method for forming an oxide thin film using the coating liquid.

[0002]

2. Description of the Related Art In order to form a metal oxide thin film on the surface of a substrate by a liquid phase method, a metal alkoxide is generally used as a starting material, which is hydrolyzed to contain a metal oxide or a precursor thereof. After preparing the coating solution, the coating solution is applied to the surface of the substrate and dried, and then the coating film is heated at an appropriate temperature to crystallize the metal oxide. In this case, the coating solution prepared by hydrolyzing the metal alkoxide is usually a completely non-aqueous solution, and is very sensitive to moisture including atmospheric humidity. Therefore, during the period from the preparation of the coating solution to the film formation, the coating solution is hydrolyzed under the influence of moisture in the atmosphere,
The coating liquid becomes inhomogeneous, making it impossible to form a uniform film, or during storage of the coating liquid, the coating liquid becomes inhomogeneous under the influence of moisture in the atmosphere.

Therefore, as one of the methods for improving the film forming property, moisture resistance and long-term stability of a coating solution, a method of stabilizing the coating solution by adding various organic ligands to the coating solution. Has been proposed. For example, β-diketone is effective for forming an alumina thin film using aluminum-s-butoxide as a starting material (Academic Journal of the Ceramic Society of Japan,
97 , 396 (1989)). In forming a titania thin film using titanium isopropoxide as a starting material, 1,3-butanediol (Toshio Koshiba, doctoral dissertation, Toyohashi University of Technology,
March 1993), diethanolamine (Journal of Materials Science (Journal of Materials)
Materials Science), 23 , 22
59 (1988)) or β-diketone (Academic Journal of the Ceramic Society of Japan, 97 , 183 (1989)) is reported to be effective. It has been reported that the use of diethylene glycol is effective in forming a zirconia thin film using zirconium-n-butoxide as a starting material (Ceramic Industry Association, 95 , 942 (19)
87)). Journals report that the use of β-diketones and alkanolamines is also effective in the synthesis of complex oxides such as PbTiO ₃ and Pb (Zr, Ti) O _3.
Of American Ceramic Society (Jo
urnal of American Ceramic
s Society), 74 , 1407 (1991) and Journal of Materials Science, 25 ,
3960 (1990). Also,

As another method for stabilizing a coating solution in order to improve the film forming property, moisture resistance and long-term stability of the coating solution, for example, a Physics of Tin Film is available. , 5 , p
87 (1969), Academic Press (Acade)
mic Press) includes chloride, sulfate, nitrate,
A method for producing an oxide thin film using hydrolysis of various inorganic salts such as ammonium salts and an aqua complex has been reported. Japanese Patent Application Laid-Open No. 9-12354 discloses a method of forming a Ba _1-x Sr _x Ti _y O ₃ thin film by mixing barium carboxylate, strontium carboxylate and titanium alkoxide in a mixed solvent of a carboxylic acid and an ester. A method for preparing a coating solution is disclosed. Further, Japanese Patent Application Laid-Open
No. 87329 discloses that a metal alkoxide is subjected to a treatment such as carboxylation, β-diketonation, or chelation.
There is disclosed a technique for obtaining a coating liquid for forming a Ti-based composite oxide thin film having excellent stability.

[0005]

According to the method for stabilizing a coating solution by adding an organic ligand as described above,
Although a homogeneous coating solution can be easily prepared, many organic substances remain in the obtained coating film. As a result, it is necessary to heat-treat the coating film at a high temperature of about 500 ° C. to remove the residue. Further, since many organic substances remain in the coating film, heat treatment of the coating film greatly reduces the weight of the film. In other words, many pores are generated in the film due to the removal of the organic matter from the coating film, which is likely to be a defect. On the other hand, extra energy is required to improve the microstructure of the film.

[0006] Further, the coating liquid for forming an oxide thin film disclosed in Japanese Patent Application Laid-Open Nos. 9-12354 and 10-87329 also has many organic substances in the coating film when a film is formed using the same. It remains and has the same problems as when an organic ligand is used.

[0007] As described above, the method using a metal salt is basically a thermal decomposition method, and causes many problems in the film quality after the heat treatment.

The present invention has been made in view of the above circumstances, and has excellent film-forming properties, moisture resistance and long-term stability, and can fire a coating film at a low temperature after film formation. Providing a coating liquid capable of forming an oxide thin film having good film quality, and providing a method for producing a coating liquid for producing such a coating liquid for forming an oxide thin film; and It is another object of the present invention to provide a method for producing an oxide thin film for forming an oxide thin film on the surface of a substrate using a coating solution.

[0009]

The invention according to claim 1 is
In the coating liquid for forming an oxide thin film containing a metal oxide and / or a precursor thereof, 0.01% by weight to 10% by weight, preferably in a solvent containing one or more alkoxy alcohols as a main component, preferably 0.1% by weight to 5% by weight
Of water.

According to a second aspect of the present invention, in the coating solution of the first aspect, the metal oxide is a group consisting of a transition metal oxide, cerium oxide (ceria), and a chemical formula of ABO ₃ (A: Ba, Sr, and Pb). One or more elements selected from the group consisting of: B: one or more elements selected from the group consisting of Ti, Zr, Ge and Sn, or
A: a complex represented by one or more elements selected from the group consisting of Li, Na and K; B: one or more elements selected from the group consisting of V, Nb and Ta) Oxide and its solid solution and chemical formula C ₂
D ₂ O ₇ (C: one or more elements selected from the group consisting of Ba, Sr and Pb; D: Nb and / or
Or one or more oxides selected from the group consisting of a composite oxide represented by Ta) and a solid solution thereof.

According to a third aspect of the present invention, one or more metal alkoxides are used as a starting material and hydrolyzed, or one or more metal alkoxides and one or more metal alkoxides are used as starting materials. In a method for producing a coating solution for preparing a coating solution for forming an oxide thin film containing a metal oxide and / or a precursor thereof by hydrolyzing a mixture with a salt or a reaction product thereof, one or more kinds of Hydrolyzing a metal alkoxide with water in an amount of 0.1 to 10, preferably 3 to 10 in a molar ratio to the metal alkoxide or a molar ratio to the metal alkoxide and the metal salt in an organic solvent containing an alkoxy alcohol. It is characterized by.

According to a fourth aspect of the present invention, at least a metal alkoxide is used as a starting material, which is hydrolyzed to a chemical formula ABO ₃ (A: Ba or Sr; B: Ti, Zr, G
a complex oxide represented by one or more elements selected from the group consisting of e and Sn), a solid solution thereof, or a chemical formula C ₂ D ₂ O ₇ (C: Ba or Sr;
D: A method for producing a coating solution for preparing an oxide thin film containing a complex oxide represented by Nb and / or Ta) or a solid solution thereof, wherein Ba or Sr is used.
Hydroxide hydrate and an alkoxide of element B or D are mixed and stirred in an organic solvent containing one or more alkoxy alcohols to form a mixture of 0.01% by weight to 10% by weight.
The present invention is characterized in that a coating liquid for forming an oxide thin film containing water of 0.1% by weight, preferably 0.1% by weight to 5% by weight is obtained.

According to a fifth aspect of the present invention, a mixture of a metal alkoxide and a metal salt or a reaction product thereof is hydrolyzed to give a chemical formula of ABO ₃ (A: Ba or Sr; B: Ti,
A complex oxide represented by one or more elements selected from the group consisting of Zr, Ge and Sn) or a solid solution thereof or a chemical formula C ₂ D ₂ O ₇ (C: Ba or Sr; D: Nb and / or Or a coating solution for preparing an oxide thin film-forming coating solution containing a complex oxide represented by Ta) or a solid solution thereof, comprising an alkoxide or salt of Ba or Sr and a hydroxide hydrate and an element B or After mixing with an alkoxide or a salt of D in an organic solvent containing one or more alkoxy alcohols and stirring or heating and stirring, 0.1 mol to 10 mol of water is added to the metal alkoxide. Add,
0.01% by weight to 10% by weight, preferably 0.1% by weight
It is characterized in that a coating liquid for forming an oxide thin film containing up to 5% by weight of water is obtained.

According to a sixth aspect of the present invention, a film is formed by using the coating solution according to the first or second aspect or the coating solution obtained by the manufacturing method according to the third aspect. Thereafter, a heat treatment is performed on the coating film to produce an oxide thin film.

The coating liquid according to the first aspect of the present invention is stabilized without being affected by moisture in the atmosphere by containing an appropriate amount of water in a solvent containing an alkoxy alcohol as a main component. I do. Further, the presence of water is effective for removing residual organic matter after film formation. When the content of water in the solvent exceeds 10% by weight, the stability of the coating solution is reduced.
On the other hand, if the content of water in the solvent is less than 0.01% by weight, it will be affected by moisture in the atmosphere, and the effect of removing residual organic substances will also be reduced. The coating liquid can be stabilized without containing an organic ligand or the like. In addition, even if an organic component such as an organic ligand coexists in this coating liquid, removal of organic matter after film formation is easily performed by the effect of water. Therefore, when a film is formed using this coating liquid, a large amount of organic substances does not remain in the coating film. 0.1% by weight of water in the solvent
When the content is ５5% by weight, the effect of removing organic substances after film formation is further enhanced.

The coating solution of the invention according to claim 2 is used for forming a thin film of a transition metal oxide, cerium oxide or composite oxide.

According to the manufacturing method of the third aspect of the present invention,
The metal alkoxide is used in a molar ratio of 0.1-1.
Hydrolysis by an amount of water which is 0, or a mixture of a metal alkoxide and a metal salt or a reaction product thereof is hydrolyzed by an amount of water having a molar ratio thereof of 0.1 to 10; A coating solution containing an appropriate amount of water in a solvent containing an alkoxy alcohol as a main component is prepared, and the coating solution is stabilized without being affected by atmospheric moisture. If the molar ratio of water to the metal alkoxide or the molar ratio of water to the metal alkoxide and the metal salt exceeds 10, the coating solution will gel or form a precipitate, and the stability of the coating solution will decrease. on the other hand,
If the molar ratio of water to metal alkoxide or the molar ratio of water to metal alkoxide and metal salt is less than 0.1, water is consumed for hydrolysis of metal alkoxide or hydrolysis of metal alkoxide and metal salt, which is desirable. A coating solution having a water content cannot be obtained, and the coating solution is affected by atmospheric moisture. Then, the obtained coating liquid can be stabilized without containing an organic ligand or the like. Further, even if an organic component such as an organic ligand coexists in the obtained coating liquid, removal of organic matter after film formation is easily performed by the effect of water. Therefore, when a film is formed using this coating liquid, a large amount of organic substances does not remain in the coating film. When the hydrolysis is carried out with an amount of water in which the molar ratio to the metal alkoxide or the molar ratio to the metal alkoxide and the metal salt is 3 to 10, a more appropriate coating solution is prepared, and the coating solution is an organic material after film formation. Removal effect is more enhanced.

In the production method according to the fourth aspect of the invention, the hydroxide hydrate of Ba or Sr is octahydrate, and the metal alkoxide is hydrolyzed using the crystallization water. According to this production method, 0.01% by weight to 10% by weight in a solvent containing an alkoxy alcohol as a main component,
Preferably, a coating liquid containing 0.1 to 5% by weight of water is obtained, and the coating liquid is stabilized without being affected by atmospheric moisture. Then, the obtained coating liquid can be stabilized without containing an organic ligand or the like. Further, even if an organic component such as an organic ligand coexists in the obtained coating liquid, removal of organic matter after film formation is easily performed by the effect of water. Therefore, when a film is formed using this coating liquid, a large amount of organic substances does not remain in the coating film.

In the method of the invention according to claim 5, the hydroxide hydrate of Ba or Sr is octahydrate, and the metal alkoxide and metal salt are hydrolyzed using the crystallization water. . According to this production method, 0.01% by weight or less in a solvent containing an alkoxy alcohol as a main component.
A coating liquid containing 10% by weight, preferably 0.1% to 5% by weight of water is obtained, and the coating liquid is stabilized without being affected by atmospheric moisture. Then, the obtained coating liquid can be stabilized without containing an organic ligand or the like. Further, even if an organic component such as an organic ligand coexists in the obtained coating liquid, removal of organic matter after film formation is easily performed by the effect of water. Therefore, when a film is formed using this coating liquid, a large amount of organic substances does not remain in the coating film.

According to the manufacturing method of the invention according to claim 6,
Since the film is formed using a stable coating solution, an oxide thin film having good film quality can be obtained. Further, since a large amount of organic matter does not remain in the coating film when the film is formed, there is no need to heat-treat the coating film at a high temperature to remove the residue from the coating film. Can be fired at a low temperature, and an oxide thin film having a good microstructure can be obtained.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

The coating liquid for forming an oxide thin film according to the present invention contains a metal oxide or a precursor thereof, or a metal oxide and a precursor thereof, and contains one or more alkoxy alcohols as main components. 0.01% by weight to 10% by weight, preferably 0.1% by weight to 5% by weight in the solvent
Contains water. As described above, since the coating liquid contains an appropriate amount of water, the coating liquid is not affected by atmospheric moisture, and the coating liquid is stabilized. When the content of water in the solvent exceeds 10% by weight, the stability of the coating solution is reduced. On the other hand, when the content of water in the solvent is less than 0.01% by weight, the solvent is affected by atmospheric moisture.
And, even if this coating solution does not contain an organic ligand or the like for stabilizing the coating solution, stability is ensured for a long period of time. Further, even if an organic component such as an organic ligand coexists in this coating liquid, removal of organic matter after film formation is easy due to the effect of water.

The oxide thin film to which the present invention can be applied is not particularly limited as long as a coating solution of a metal oxide or a precursor thereof can be obtained from a metal alkoxide or a metal salt as a starting material. Well, there is no particular limitation. For example, as the metal oxide, a transition metal oxide, for example, an oxide of a Group 4A element or a Group 5A element, cerium oxide, a composite oxide represented by the chemical formula ABO ₃ or a solid solution thereof, and a chemical formula C ₂ D ₂ O ₇ Or a solid solution thereof. In each of the above chemical formulas, A is Ba, Sr or Pb, or a combination of a plurality of these elements, and B is T
i, Zr, Ge or Sn, or a combination of a plurality of these elements. Alternatively, A is
Li, Na, or K, or a combination of a plurality of these elements, and B is V, Nb, or Ta, or a combination of a plurality of these elements. C is Ba, Sr or Pb, or a combination of a plurality of these elements, and D is Nb or Ta, or a combination of Nb and Ta. In order to improve the characteristics of these composite oxides, for example, transition metals such as La, Bi, Mn, etc.
It is also possible to add a generally known trace addition component. Then, using this coating solution, a dielectric thin film,
Various oxide thin films such as a conductor thin film, a piezoelectric thin film, and a semiconductor thin film are formed.

This coating solution is prepared by hydrolyzing one or more metal alkoxides as a starting material, or one or two or more metal alkoxides and one or more metal salts. Or a mixture thereof or a reaction product thereof by hydrolysis. In this case, in an organic solvent containing one or more alkoxy alcohols, an amount of water having a molar ratio to the metal alkoxide or a molar ratio to the metal alkoxide and the metal salt of 0.1 to 10, preferably 3 to 10, is used. To perform hydrolysis. In this way, by performing hydrolysis with a larger amount of water than in the prior art, a coating liquid containing an appropriate amount of water in a solvent containing an alkoxy alcohol as a main component is prepared. When the molar ratio of water to the metal alkoxide or the metal alkoxide and the metal salt exceeds 10, the coating solution gels or precipitates are generated, and the stability of the coating solution is reduced. On the other hand, when the molar ratio of water to the metal alkoxide or the metal alkoxide and the metal salt is less than 0.1, water is consumed for hydrolysis of the metal alkoxide or the metal alkoxide and the metal salt, and a coating solution having a desired water content is obtained. No longer available. Further, in this production method, no organic ligand is added for the purpose of stabilizing the coating solution.

Examples of usable metal alkoxides or metal salts include alkali metal elements, alkaline earth metal elements and Group 3B elements from the second period to the sixth period of the periodic table, and the third period of the periodic table. Examples include metal alkoxides or metal salts such as Group 4B and Group 5B elements up to the sixth period, transition metal elements, lanthanoid elements, etc., but are not particularly limited. Organic salts such as acetates, oxalates, nitrates, chlorides and the like are used as metal salts. A composite alkoxide obtained by a reaction between two or more metal alkoxides of the element;
Alternatively, it may be a composite alkoxide obtained by reacting one or more metal alkoxides with one or more metal salts. Furthermore, these can be used in combination. A metal oxide obtained by a reaction product of a metal alkoxide and a metal salt,
Specifically, Pb (Zr _1-x Ti _x ) O ₃ (0 ≦ x ≦
1), a Pb (B1, B2) perovskite-type composite oxide of lead-based, such as _{O 3.} In this case, the metal salt used is most preferably lead acetate. Also, Pb (B
1, B2) O ₃ includes B1, Mg, Zn, N
Alkoxides or metal salts such as i, Mn, Fe, and Co are used, and preferably acetate is used. Also,
Mg is more preferably added as a metal and reacted with a solvent.

The number of carbon atoms of the alkoxyl group of the metal alkoxide is not particularly limited. However, the number of carbon atoms is preferably 1 to 4 depending on the concentration of the oxide contained, the ease of desorption of organic substances, and the availability.
Is preferred. Complex alkoxides obtained by reacting one or more metal alkoxides with one or more metal salts include organic acid salts such as chlorides, nitrates, sulfates, acetates and formates. And a compound obtained by reacting a metal salt such as oxalate with an alkoxide.

As the alkoxy alcohol used as a solvent, 2-methoxyethanol (ethylene glycol monomethyl ether), 2-ethoxyethanol (ethylene glycol monoethyl ether), 2-propoxyethanol (ethylene glycol monopropyl ether), Butoxyethanol (ethylene glycol monobutyl ether), 1-methoxy-2-propanol (1,2-propylene glycol monomethyl ether), 3-methoxypropanol (1,3-propylene glycol monomethyl ether), 3-ethoxypropanol (1,3 -Propylene glycol monoethyl ether), 3-propoxypropanol (1,3-propylene glycol monopropyl ether), 4-methoxybutanol (diethyl Glycol monomethyl ether), 4-ethoxy-butanol (diethylene glycol monoethyl ether), 4-propoxy-butanol (although diethylene glycol monopropyl ether) include, but are not particularly limited to these. These alkoxy alcohols are used alone or in combination of two or more. Preferably, 2-
Methoxyethanol, 2-ethoxyethanol or 1
-Methoxy-2-propanol is used as solvent.

Also, the chemical formula ABO ₃ or C ₂ D ₂ O ₇
The following method can also be used to prepare a coating solution for forming an oxide thin film containing the complex oxide represented by the formula (1) or a solid solution thereof. In the above formula, A and C are each Ba or Sr, and B is Ti, Z
r, Ge or Sn, or a combination of a plurality of these elements, and D is Nb or Ta, or a combination of Nb and Ta.

Hydroxide hydrate of Ba or Sr and element B
Alternatively, by using the alkoxide of D as a starting material and mixing and stirring them in an organic solvent containing an alkoxy alcohol, 0.01 to 10% by weight, preferably 0.1 to 5% by weight is mixed. A coating liquid for forming an oxide thin film containing water is prepared. Further, a hydroxide hydrate of Ba or Sr and an alkoxide or salt of element B or D are used as starting materials, or a hydroxide hydrate of Ba or Sr and an alkoxide or salt of Ba or Sr are combined with an element B Alternatively, by using the alkoxide of D as a starting material and mixing and stirring them in an organic solvent containing an alkoxy alcohol, the mixture can be prepared without adding water to a concentration of 0.0
A coating liquid for forming an oxide thin film containing 1 to 10% by weight, preferably 0.1 to 5% by weight of water is prepared. This method can be performed in combination with another complex alkoxide.

As described above, Ba or Sr is used as a starting material.
In the method using the hydroxide hydrate, Ba or Sr
Is an octahydrate, and the hydrolysis reaction of the metal alkoxide or metal salt proceeds using the water of crystallization. In this production method, a coating liquid containing 0.01% by weight to 10% by weight, preferably 0.1% by weight to 5% by weight of water in a solvent containing alkoxy alcohol as a main component is obtained. The type and amount of starting materials are selected.

When a coating solution is obtained by the above-described manufacturing method, the coating solution is applied on a substrate on which a film is to be formed, thereby forming a coating film on the surface of the substrate. As a coating method, a generally practiced method such as dip coating, spin coating, flow coating, and bar coating can be used. Then, the metal oxide is crystallized by performing a heat treatment on the coating film after the film formation. The heating temperature at this time varies depending on the compound, but is, for example, about 300 ° C. to 600 ° C. for a perovskite-type composite oxide. According to this manufacturing method, since a film is formed using a stable coating solution, an oxide thin film having good film quality can be obtained. Also,
Since it is not necessary to heat-treat the coating film at a high temperature to remove residual organic substances from the coating film, the coating film can be fired at a relatively low temperature, and the obtained oxide thin film has a good quality. It will have a fine structure.

[0032]

Next, a more specific embodiment of the present invention will be described.

Examples 1 to 14 Chemical formula M (OR)
_n (M: metal element; n: valency of M) of an alkoxy alcohol solution of a metal alkoxide in a 10% alkoxy alcohol diluent (H ₂ O /
n = 1). From the obtained hydrolyzate, R
The low boiling point component mainly composed of OH was distilled off under reduced pressure to obtain a transparent MOn _{/ 2} coating liquid mainly composed of alkoxy alcohol. Table 1 shows the starting materials, the type of solvent, the weight concentration in terms of oxide in the solution, the amount of water added (molar ratio of H ₂ O / M), and the oxide concentration and water content of the coating solution. . In the column of “Type of solvent” in Table 1 (the same applies to Table 3), ME is 2-methoxyethanol, EE is 2-methoxyethanol.
Ethoxyethanol and MP indicate 1-methoxy-2-propanol, respectively.

[0034]

[Table 1]

The obtained coating solution was used at room temperature and a humidity of 45.
%, At a rotation speed of 2000 rpm for 20 seconds.
A film was formed on a substrate. Subsequently, after the coating film was dried at a temperature of 100 ° C., heat treatment was performed at various temperatures for 30 minutes. Thus, a crystalline MOn _{/ 2} film was obtained. Table 1 summarizes the thickness and crystallization temperature of the obtained oxide thin film.

Comparative Example 1 Ti, Zr, Nb, Ta, C
e, to a 2-butanol solution (concentration in terms of oxide = 2% by weight) of each of the alkoxides of V, W, and 5% 2-butanol diluted solution (H ₂ O / M = 1) of ion-exchange distilled water was added, and water was added. Decomposed. However, a white precipitate was formed in the solution, and a coating solution capable of forming a film could not be obtained.

Comparative Example 2 Ti, Zr, Nb, Ta, C
A film-forming test was performed using 2-butanol solutions of alkoxides e, V and W (concentration in terms of oxide = 2% by weight). However, at room temperature in Examples 1-14 above,
Under the condition of a humidity of 45%, white turbidity or powder was generated during film formation, and film formation was impossible. In order to obtain a film equivalent to the oxide thin films of Examples 1 to 14, it was necessary to form the film under the condition of a humidity of 15% or less.

Examples 15 to 22: Predetermined amounts of metal barium or barium diisopropoxide, metal strontium or strontium diisopropoxide and tetraisopropoxy so that the final oxide concentration is 5% by weight. After adding titanium to 2-methoxyethanol, the mixture was refluxed for 1 hour to synthesize a composite alkoxide.
The obtained composite alkoxide solution was hydrolyzed with a 10% alkoxy alcohol diluted solution of ion exchange distilled water. From the obtained hydrolyzate, a low-boiling component containing 2-propanol as a main component was distilled off under reduced pressure, and 2-methoxyethanol as a main component and an oxide concentration of 5% by weight (Ba _x Sr).
_1-x ) TiO ₃ coating solution was obtained. Ba ratio x, the amount of water added _((molar ratio _{Ba x Sr 1-x) TiO} 3),
Table 2 shows the amount of water in the coating solution.

[0039]

[Table 2]

The obtained coating solution was used at room temperature with a humidity of 45.
%, Pt under the condition of rotation speed of 2000 rpm for 20 seconds
A film was formed on the Si substrate on which the electrodes were formed. Subsequently, the coating solution was dried at a temperature of 100 ° C., and then dried at a temperature of 450 ° C. for 3 hours.
Heat treatment was performed for 0 minutes. Thereby, the crystalline (BaxS ₎
r _1-x) TiO ₃ film was obtained.

Further, film formation / drying and calcination at 350 ° C. for 15 minutes are performed until the film thickness becomes about 400 nm.
After repeating 0 times, the coating film was subjected to a heat treatment at a temperature of 600 ° C. to obtain a (Ba _x Sr _1-x ) TiO ₃ film. On the obtained (Ba _x Sr _1-x ) TiO ₃ film, an Al upper electrode having a diameter of 0.5 mm was formed by a vacuum deposition method, and the dielectric characteristics at 1 kHz were measured at room temperature using an LCR meter.
The results are summarized in Table 2.

Embodiments 23 and 24 Embodiment 18 described above.
A coating solution was prepared using the same composition as described above and using 2-ethoxyethanol or 1-methoxy-2-propanol as a solvent. The water content of the coating solution obtained using each solvent is
They were 0.97% by weight and 1.01% by weight, respectively.

Using the obtained coating solution, at room temperature and humidity of 45
%, Pt under the condition of rotation speed of 2000 rpm for 20 seconds
A film was formed on the Si substrate on which the electrodes were formed. Subsequently, after drying each coating solution at a temperature of 100 ° C.,
For 30 minutes. As a result, a crystalline (Ba _0.5 Sr _0.5 ) TiO ₃ film was obtained.

[Examples 25 to 30] Strontium hydroxide octahydrate or barium hydroxide 8 was added to a 2-methoxyethanol solution of tetraisopropoxytitanium prepared so that the final oxide concentration was 5% by weight. After the hydrate was added, the solution was vigorously stirred at room temperature for 24 hours to prepare a transparent (Ba _x Sr _1-x ) TiO ₃ coating solution. Ba
Table 2 summarizes the ratio x and the amount of water in the coating solution.

Under the same conditions as in Example 15 described above, (Ba
_x Sr _1-x) it was confirmed crystallization temperature of TiO _3.
As a result, irrespective of the Ba ratio, 3
It was found that crystallization to the perovskite phase was obtained by the heat treatment for 0 minutes. Further, at a heating temperature of 600 ° C., a film thickness of about 40
The evaluation of the dielectric properties at 0 nm was performed. The results are summarized in Table 2.

Comparative Example 3 A coating solution was prepared with the same composition as in Example 15 described above, but using 2-butanol as a solvent. However, a precipitate was formed in the solution by the addition of water, and a coating solution capable of forming a film was not obtained.

Comparative Example 4 An equimolar amount of metal barium and tetraisopropoxytitanate were dissolved in 2-butanol in the presence of Ti and an equimolar amount of aceracetone, and the concentration in terms of oxide was 5% by weight. A homogeneous solution containing the complex alkoxide was obtained. The amount of water in the solution is 0.008
%Met.

The obtained coating solution was used at room temperature and a humidity of 45.
%, Pt under the condition of rotation speed of 2000 rpm for 20 seconds
A film was formed on the Si substrate on which the electrodes were formed. Subsequently, after the coating film was dried at a temperature of 100 ° C.,
Heat treatment was performed for 0 minutes. BaTiO ₃ obtained by this
The film was amorphous, and required one hour of heat treatment at a temperature of 600 ° C. to crystallize BaTiO ₃ .

[Examples 31 to 44] Anhydrous lead acetate was added to an alkoxy alcohol solution of Ti alkoxide and / or Zr alkoxide in an amount of 1.04 mol times the amount of (Zr + Ti), and the mixture was reacted at a temperature of 90 ° C. for 24 hours. A Pb-Zr-Ti composite alkoxide solution having a concentration in terms of a substance of 20% by weight was obtained. The obtained composite alkoxide solution was hydrolyzed with a 10% alkoxy alcohol diluted solution of ion exchange distilled water. From the obtained hydrolyzed solution, a low boiling point component containing ROH as a main component was distilled off under reduced pressure to obtain a PZT coating solution containing an alkoxy alcohol as a main component and an oxide concentration of 20% by weight. Kind of alkoxide as starting material and Z
Table 3 shows the r / Ti ratio (molar ratio), the type of solvent, the amount of water added (molar ratio to the (Zr + Ti) amount), and the amount of water in the solution.

[0050]

[Table 3]

Using the obtained coating solution, at room temperature and humidity 45
%, At a rotation speed of 3000 rpm for 20 seconds.
A film was formed on the Si substrate on which the electrodes were formed. Subsequently, the coating solution was dried at a temperature of 100 ° C., and then dried at a temperature of 350 ° C.
After calcining for 5 minutes and repeating this film formation / drying and calcining three times until the film thickness becomes about 300 nm, the coating film is heated at various temperatures for 1 hour (heating rate: 10 ° C./min). do it,
A PZT film was obtained. Table 3 shows the crystallization temperature of each PZT film into a perovskite single phase.

An Al upper electrode was formed on the PZT film obtained in Example 34 by a vacuum evaporation method, and the PE characteristics were evaluated by a Sawyer tower method. As a result, a hysteresis loop corresponding to the ferroelectric substance is obtained, and the formed PZ
It was confirmed that the T film was a ferroelectric. Further, it was confirmed that the PZT film obtained in Example 39 was an antiferroelectric substance, and the PZT films obtained in other examples were ferroelectric films.

Embodiments 45 and 46 Embodiment 34 described above.
Under the same conditions as above, only the reaction time between the alkoxide and lead acetate was changed to 10 hours and 48 hours, respectively.
A coating solution was prepared. The water content of each of the obtained PZT coating solutions was 0.72% and 0.80%, respectively. After film formation using each coating solution, the crystallization temperature of PZT was confirmed. As a result, it was confirmed that both Examples 45 and 46 were crystallized into a perovskite single phase by firing at the same temperature of 500 ° C. for 1 hour as in Example 34.

Example 47 Under the same conditions as in Example 34 described above, a coating liquid was prepared by adding 1 mol% of La to PZT. As a La raw material, lanthanum acetate anhydride was used. Lanthanum anhydride was produced by replacing a substantial amount of it with lead acetate. The water content in the obtained coating solution was 0.75%. After forming a film using the coating solution, the crystallization temperature of PZT-La was confirmed. As a result, it was confirmed that sintering at the same temperature of 500 ° C. for 1 hour as in Example 34 caused crystallization to a perovskite single phase.

[Comparative Example 5] Anhydrous lead acetate was added to a 2-methoxyethanol solution of tetraisopropoxytitanium and tetranormal butoxyzirconium prepared so that Zr / Ti = 52/48, and 1% of (Zr + Ti) was added. .0
After adding 4 mol times, the mixture was refluxed for 2 hours to obtain a Pb-Zr-Ti composite alkoxide solution having an oxide equivalent concentration of 20% by weight. (Zr +
Ti) and an equimolar amount of acetylacetone were added, and then a 10% alkoxy alcohol diluted solution (H
Hydrolysis with ₂ O / PZT = 1) gave a PZT coating solution having an oxide concentration of 10% by weight. The water content in the coating solution was 0.09%.

The obtained coating solution was used at room temperature with a humidity of 45.
%, At a rotation speed of 3000 rpm for 20 seconds.
A film was formed on the Si substrate on which the electrodes were formed. Subsequently, the coating solution was dried at a temperature of 100 ° C., and then dried at a temperature of 350 ° C.
The film was calcined for 5 minutes, and the film formation / drying and calcining were repeated five times until the film thickness became about 300 nm. In order to obtain a perovskite single-phase film, a heat treatment at a temperature of 700 ° C. for one hour was required by a high-speed heating treatment.

[Comparative Example 6] In a 2-ethoxyethanol solution of tetraisopropoxytitanium and tetranormal butoxyzirconium prepared so that Zr / Ti = 52/48, anhydrous lead acetate was added in an amount of 1% (Zr + Ti). .0
After adding 4 mol times, the mixture was refluxed for 24 hours to obtain a Pb-Zr-Ti composite alkoxide solution having an oxide equivalent concentration of 20% by weight. The water content in the reaction solution was 0.04%. Using the obtained reaction liquid as a coating liquid, film formation was attempted in the same manner as in Example 34. However, under the condition of 45% humidity, cracks occurred in the obtained film. In order to suppress the generation of cracks, it was necessary to dilute the coating solution to 5% or to form a film at a humidity of 20% or less.

Using a coating solution diluted to an oxide equivalent concentration of 5%, a film was formed on a Si substrate on which a Pt electrode had been formed at room temperature under a condition of 45% humidity and a rotation speed of 3000 rpm for 20 seconds. . Subsequently, after the coating film was dried at a temperature of 100 ° C., it was calcined at a temperature of 350 ° C. for 15 minutes, and the film formation / drying and calcining were repeated six times until the film thickness became about 300 nm. In order to obtain a perovskite single-phase film, a heat treatment at a temperature of 650 ° C. for one hour by a high-speed temperature raising treatment was required.

[Example 48] Anhydrous lead acetate and pentaethoxyniobium were mixed in 2-ethoxyethanol for 9 hours.
The reaction was carried out at a temperature of 0 ° C. for 24 hours to obtain a Pb—Nb composite alkoxide solution. Further, metallic magnesium was added to the solution and reacted at 90 ° C. for 24 hours to obtain Pb-M
A g-Nb composite alkoxide solution was synthesized. At this time,
The composition of each element is Pb _1.04 (Mg _1/3 N
b _2/3 ) O ₃ and the concentration in terms of oxide was 15% by weight. The obtained composite alkoxide solution was diluted with a 10% alkoxy alcohol diluent (H ₂
O / (Mg + Nb) = 12). From the resulting hydrolyzed solution, a low boiling component containing ROH as a main component was distilled off under reduced pressure to obtain a PMN coating solution containing an alkoxy alcohol as a main component and an oxide concentration of 20% by weight. The water content in the obtained coating solution was 0.88%.

Using the obtained coating solution, at room temperature and a humidity of 45
%, At a rotation speed of 3000 rpm for 20 seconds.
A film was formed on the Si substrate on which the electrodes were formed. Subsequently, the coating film was dried at a temperature of 100 ° C., and then dried at a temperature of 350 ° C.
After calcination for 5 minutes, this film formation / drying and calcination are repeated 5 times until the film thickness becomes about 500 nm, and then heat-treated at 760 ° C. for 1 hour (heating rate: 10 ° C./min). Thus, a single-phase PMN film was obtained. An Al upper electrode was formed on the obtained PMN film by a vacuum evaporation method, and the dielectric characteristics at room temperature and 1 kHz were measured using an LCR meter. As a result, the relative dielectric constant was 1700, and tan δ was 0.01.

Comparative Example 7 Film formation was attempted using the Pb-Mg-Nb composite alkoxide solution obtained in Example 48 described above as a coating liquid (water content: 0.05%). %, Cracks occurred in the film.

Example 49 Each of the coating solutions obtained in Examples 34 and 48 was mixed at a ratio of 1: 9, and mixed with Pb (Mg _1/3 Nb _2/3 ) _0.9 Ti.
_A coating solution for forming a _0.1 O ₃ film was used. The water content in the obtained coating solution was 0.86%. After forming a film in the same manner as in Example 48, the film was heated at 690 ° C. for 1 hour to obtain a single-phase PMN-PT film. The dielectric properties of the obtained film were a relative dielectric constant of 2300 and a tan δ of 0.03.

[Comparative Example 8] The chemical composition was Pb _1.04 (M
g _1/3 Nb _2/3 ) _0.9 Ti _0.1 O _{3 A} predetermined amount of anhydrous lead acetate, pentaethoxy niobium, metallic magnesium and tetraisopropoxy titanium were added to 2
-The mixture was refluxed in ethoxyethanol for 2 hours to be reacted to obtain a Pb-Nb composite alkoxide solution. The obtained composite alkoxide solution is coated with a coating solution (water content: 0.05
%), But cracks occurred in the film under the condition of room temperature and humidity of 45%.

In order to obtain an oxide-concentrated concentration of 5% by weight,
-Using an application liquid diluted with ethoxyethanol, a film was formed under the same conditions as in Example 48 described above. Subsequently, the coating film is dried at a temperature of 100 ° C., and then dried at a temperature of 350 ° C. for 15 minutes.
After calcining for 20 minutes, the film formation / drying and calcining were repeated 12 times to obtain a PMN-PT film having a thickness of 500 nm.
In order to obtain a perovskite single-phase film, a heat treatment at a temperature of 820 ° C. for one hour was required.

Example 50 Final oxide concentration was 2% by weight
After adding strontium hydroxide octahydrate to a 2-methoxyethanol solution of tetraethoxy niobium prepared so as to obtain a solution of transparent Sr ₂
An Nb ₂ O ₇ coating solution was obtained. The amount of water in the coating solution is 1.8
8%.

The obtained coating solution was used at room temperature and a humidity of 45.
%, At a rotation speed of 3000 rpm for 20 seconds.
A film was formed on the Si substrate on which the electrodes were formed. Next, the coating film
Is dried at a temperature of 100 ° C. and at a temperature of 350 ° C. for 15 minutes
After calcination for 1 hour, heat treatment at 650 ° C. for 1 hour (heating
(Rate: 10 ° C./min). Thereby, Sr₂Nb₂O
₇Crystallization was confirmed.

After forming a film on the Si substrate on which the Pt electrode is formed, the coating film is dried at a temperature of 100 ° C.
After calcining at a temperature of 15 ° C. for 15 minutes, repeating the film formation / drying and calcining four times until the film thickness becomes about 200 nm,
Heat treatment at a temperature of 650 ° C. for 1 hour (heating rate: 10 ° C. /
) To obtain a sample for evaluating electrical characteristics. Al was applied to the Sr ₂ Nb ₂ O ₇ film of the obtained sample by a vacuum evaporation method.
Form an upper electrode and use an LCR meter at room temperature for 1 k
The dielectric properties at Hz were measured. As a result, the dielectric constant (ε _γ ) was 50 and the dielectric loss (tan δ) was 0.01.

Comparative Example 9 An equimolar amount of metal strontium and tetraethoxyniobium were dissolved in 2-butanol in the presence of Nb and an equimolar amount of acetylacetone to form an oxide to give 2% by weight of Sr _2. A homogeneous solution containing Nb ₂ O ₇ was obtained. The obtained composite alkoxide solution was diluted with 2-butanol (H ₂ O / Ti = 10% ion-exchange distilled water).
Hydrolysis was performed in 1) to obtain a Sr ₂ Nb ₂ O ₇ coating solution. The water content in the coating solution was 0.07%.

The obtained coating solution was used at room temperature and a humidity of 45.
%, Pt under the condition of rotation speed of 2000 rpm for 20 seconds
A film was formed on the Si substrate on which the electrodes were formed. Subsequently, the coating film was dried at a temperature of 100 ° C., calcined at a temperature of 350 ° C. for 15 minutes, and then heat-treated at a temperature of 650 ° C.
₂ Nb ₂ O ₇ was amorphous. When the heat treatment temperature is further increased, the intended Sr ₂ Nb ₂ O ₇ layer and other SrO—N
Heat treatment at a temperature of 800 ° C. for one hour was required to generate a b ₂ O ₅ -based impurity layer and obtain a Sr ₂ Nb ₂ O ₇ single-layer film.

As described above, according to the present invention, the coating solution is
The influence of moisture in the atmosphere is reduced, the film forming property is improved, and the number of times of forming the oxide thin film having a predetermined thickness can be reduced. Further, the crystallization temperature of the oxide thin film can be lowered as compared with the conventional method.

[0071]

According to the first aspect of the present invention, film forming properties,
Provided is a coating liquid which is excellent in moisture resistance and long-term stability, can bake a coating film at a low temperature after film formation, and can form an oxide thin film having good film quality.

According to the second aspect of the present invention, there is provided a coating liquid having the above-mentioned properties used for forming a thin film of a transition metal oxide, cerium oxide or a composite oxide.

According to the production method of each of the third to fifth aspects of the present invention, the coating film is excellent in film formability, moisture resistance and long-term stability, and the coated film can be fired at a low temperature after film formation. A coating liquid capable of forming an oxide thin film having good film quality can be obtained.

According to the manufacturing method of the invention according to claim 6,
By firing at a relatively low temperature, an oxide thin film having a good film structure and a good film quality can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01L 21/316 H01L 21/316 U F term (Reference) 4G042 DA02 DB10 DB11 DC01 DC03 DD02 DD10 DE09 DE14 4G047 CA07 CA08 CC02 CD02 CD07 CD08 4G048 AA04 AC02 AD02 AD08 4J038 AA011 HA156 HA161 HA166 JA16 JA17 KA06 NA17 NA19 PA19 PB09 5F058 BA07 BC03 BF46 BH01

Claims (6)

[Claims] 1. A coating liquid for forming an oxide thin film containing a metal oxide and / or a precursor thereof, wherein 0.01% by weight to 10% by weight is contained in a solvent containing one or more alkoxy alcohols as a main component. A coating liquid for forming an oxide thin film, comprising water by weight. 2. The metal oxide is a transition metal oxide, cerium oxide, ABO ₃ (A: one or more elements selected from the group consisting of Ba, Sr and Pb;
B: one or more elements selected from the group consisting of Ti, Zr, Ge and Sn, or A: Li,
One or two or more elements selected from the group consisting of Na and K; B: one or two or more elements selected from the group consisting of V, Nb and Ta) Solid solution and chemical formula C ₂ D ₂ O
₇ (C: one or more elements selected from the group consisting of Ba, Sr, and Pb; D: Nb and / or Ta) and a complex oxide represented by the group consisting of: The coating liquid for forming an oxide thin film according to claim 1, wherein the coating liquid is a kind or two or more kinds of oxides. 3. Hydrolysis of one or more metal alkoxides as a starting material, or a mixture of one or more metal alkoxides with one or more metal salts or a mixture thereof. A method for preparing a coating solution for forming an oxide thin film containing a metal oxide and / or a precursor thereof by hydrolyzing the reaction product of (1), wherein the organic solvent contains one or more alkoxy alcohols Wherein the metal alkoxide is hydrolyzed by an amount of water having a molar ratio to the metal alkoxide or a molar ratio to the metal alkoxide and the metal salt of from 0.1 to 10. 4. At least a metal alkoxide as a starting material, which is hydrolyzed to give a chemical formula ABO ₃ (A: Ba
Or Sr; B: a complex oxide represented by one or more elements selected from the group consisting of Ti, Zr, Ge and Sn), a solid solution thereof, or a chemical formula C ₂ D
₂ O ₇ (C: Ba or Sr; D: Nb and / or Ta) in a method for producing a coating solution for forming an oxide thin film containing a complex oxide or a solid solution thereof, comprising Ba or Sr Is mixed with an alkoxide of the element B or D in an organic solvent containing one or more alkoxy alcohols, and stirred to obtain a hydrate of 0.01%.
A method for producing a coating solution, characterized by obtaining a coating solution for forming an oxide thin film containing water in an amount of 10% by weight to 10% by weight. 5. A mixture of a metal alkoxide and a metal salt or a reaction product thereof is hydrolyzed to give a compound of the formula ABO
₃ (A: Ba or Sr; B: one or more elements selected from the group consisting of Ti, Zr, Ge and Sn) or a solid solution thereof, or a chemical formula C ₂ D ₂ O ₇ (C: Ba or Sr; D: Nb and / or Ta) A method for producing a coating solution for preparing an oxide thin film-forming coating solution containing a complex oxide or a solid solution thereof, wherein Ba or Sr alkoxide or Salt and hydroxide hydrate with an alkoxide or salt of element B or D,
After mixing and stirring or heating and stirring in an organic solvent containing one or more alkoxy alcohols, 0.1 mol to 10 mol of water is added to the metal alkoxide, and 0.01 wt% A method for producing a coating liquid, comprising obtaining a coating liquid for forming an oxide thin film containing water of 10 to 10% by weight. 6. A film is formed using the coating liquid according to claim 1 or 2 or the coating liquid obtained by the production method according to claim 3, and then the coating film is heated. A method for producing an oxide thin film, comprising: