JP2008004269A - Coating composition for forming high dielectric thin film and method for producing the same - Google Patents

Abstract

A high dielectric material capable of forming a dielectric thin film having no cracks, small film shrinkage, and excellent dielectric characteristics in the formation of a high dielectric thin film made of a perovskite type dielectric material by the MOD method. A coating composition for forming a thin film and an efficient production method thereof are provided.
A step of preparing an organic acid salt solution (A) having a predetermined concentration of an alkaline earth metal element using a specific mixed solution, selected from the group consisting of titanium, tin and zirconium using a specific organic solvent. A step of preparing an alkoxide liquid (B) having a predetermined concentration of at least one element, a step of synthesizing a composite organic acid salt liquid (C) using the organic acid salt liquid (A) and the alkoxide liquid (B), and a composite The method includes a step of concentrating the organic acid salt solution (C) to a predetermined concentration and then diluting to adjust to a predetermined concentration.
[Selection figure] None

Description

  The present invention relates to a coating composition for forming a high dielectric thin film and a method for producing the same. More specifically, the present invention relates to a coating composition comprising a perovskite type dielectric material obtained by an organic acid salt pyrolysis method (hereinafter sometimes referred to as a MOD method). The present invention relates to a coating liquid capable of forming a dielectric thin film that is free from cracks, has a small film shrinkage, and has excellent dielectric characteristics in forming a dielectric thin film, and an efficient manufacturing method thereof. As a result, it is used as a coating liquid when forming a thin film having a high dielectric constant that is effective for capacitor materials for various applications in electronic devices such as thin film capacitors and capacitive insulating films of semiconductor integrated circuit devices, DRAM capacitor materials, etc. Thus, a coating composition for forming a high dielectric thin film is obtained.

In recent years, with the miniaturization of capacitor elements and the high integration of semiconductor integrated circuits, capacitor insulating films used for capacitor insulating films of thin film capacitors and semiconductor integrated circuit devices, capacitor materials of DRAMs, etc. have a high dielectric constant. Substances are sought. As such a material having a high dielectric constant, a composite oxide having a perovskite crystal structure is known. For example, barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ), calcium titanate (CaTiO ₃ ), barium strontium titanate ((Ba, Sr) TiO ₃ ), or the like, or the composite oxide as a main component Further, perovskite type composite oxides in which magnesium is substituted at the Ba site and tin and zirconium are substituted at the Ti site are attracting attention.

  Further, as a method for forming a thin film of a substance having such a high dielectric constant, a sputtering method, a sol-gel method, a MOD method, a CVD method or the like is performed. However, both the sputtering method and the CVD method have a complicated apparatus and have a drawback that the film formation speed is slow, and the area on which the film can be formed is small, so that a film with a large area can be obtained. There is a problem that it is not possible. On the other hand, in the sol-gel method or the MOD method, a relatively simple process of applying a liquid material containing a compound that forms a perovskite-type composite oxide by thermal decomposition on a substrate and baking the substrate is large in an inexpensive facility. There is an advantage that a thin film having an area can be obtained, and this is a promising method that is industrially excellent in mass productivity.

Conventionally, for example, the following (a) to (c) have been proposed for coating compositions for forming a high dielectric thin film used in the sol-gel method or the MOD method.
(A) Barium and titanium metal soap is used (for example, refer to Patent Document 1).
(B) A barium carboxylate salt such as barium acetate and a raw material of titanium isopropoxide are dissolved in an organic solvent containing ethylene glycol monomethyl ether and hydrolyzed to obtain a composition for forming a barium titanate thin film (for example, , See Patent Document 2).
(C) Barium strontium carboxylate, strontium carboxylate, and titanium isopropoxide are dissolved in an organic solvent as an ester to form a composition for forming a barium strontium titanate thin film (see, for example, Patent Document 3). .

  However, these proposals have many technical problems and practical problems. For example, in (i), barium and strontium carbonates are not produced during pyrolysis of metal soap during firing, but the weight change due to volatilization of organic components is large, so cracks occur in the formed thin film, There arises a problem that the shrinkage of the resin becomes large. In (b), since a carboxylate is used as a raw material, a high temperature exceeding 800 ° C. is required for crystallization during firing. As a result, deterioration of insulation is unavoidable, and since leakage current is large, it has not been put into practical use. The cause of this deterioration is considered to be that micro cracks or voids are generated in the thin film due to rapid shrinkage of the film due to high-temperature firing or reaction with the base electrode. In (c), by using an ester as the solvent, the change in weight due to the volatilization of the organic component is small, and cracking and film shrinkage are unlikely to occur. However, expensive barium carboxylate and strontium carboxylate must be used, when a metal film is used for the base electrode, the wettability is poor and it is difficult to obtain a uniform coating film, and the solvent is only an ester. When it is, there existed problems, such as that the preservability by external air will deteriorate.

  As described above, in the coating liquid used for forming a high dielectric thin film made of a perovskite-type dielectric material, problems such as liquid storage stability, generation of cracks in the formed film, and film shrinkage must be cleared. However, it was difficult to satisfy all of these requirements and achieve high dielectric properties.

JP-A-1-308801 (first page) Japanese Patent Laid-Open No. 1-100024 (first page) JP-A-8-337421 (first page, second page)

  In view of the above-mentioned problems of the prior art, the object of the present invention is to form a high dielectric thin film made of a perovskite-type dielectric material by the MOD method. Another object of the present invention is to provide a coating composition for forming a high dielectric thin film capable of forming a dielectric thin film and an efficient production method thereof.

In order to achieve the above object, the present inventors have conducted extensive research on a coating composition for forming a high dielectric thin film used for forming a high dielectric thin film made of a perovskite dielectric material and a method for producing the same. As a result, an organic solvent containing a complex organic acid salt (hereinafter referred to as a composite) containing an alkaline earth metal element and at least one selected from titanium, tin, or zirconium and forming the perovskite complex oxide by thermal decomposition. An organic acid salt solution)) as a coating composition for forming a high dielectric thin film, and when producing a composite alkoxide solution, an alkaline earth metal element used as a metal source, titanium, Raw material forms such as tin or zirconium, selection of types such as organic solvents that dissolve these and stabilize the generated metal alkoxide, and complex organic acid salt solution Synthesis conditions are found to be important.
The metal alkoxide is represented by the general formula: M (OR 3) _n (wherein R represents a linear or branched alkyl group, M represents a metal element, and n is 2 or 4) For example, the chemical formula of titanium alkoxide is Ti (OR 3) ₄ .

  That is, a raw material in an appropriate form is dissolved in an organic solvent such as ether, alcohol, ester, and carboxylic acid, and an organic acid salt solution having a predetermined concentration containing an alkaline earth metal element organic acid salt and titanium, tin, or zirconium. After separately preparing an alkoxide liquid having a predetermined concentration containing at least one selected metal alkoxide, these metal alkoxide liquids are mixed to synthesize a composite organic acid salt liquid for forming a perovskite-type dielectric material. The concentration of the organic acid salt solution is once concentrated to a predetermined concentration and then readjusted to the predetermined concentration, so that the solubility of the coating solution, coating properties, storage stability, etc. can be satisfied. In the formation of thin films, high dielectrics that can form dielectric thin films with no cracks, small film shrinkage, and excellent dielectric properties It found that thin film-forming coating composition is prepared efficiently and stably, and completed the present invention.

That is, according to the first invention of the present invention, there is provided a method for producing a coating composition for forming a high dielectric thin film, comprising the following steps (1) to (4).
(1) At least one metal of an alkaline earth metal element selected from the group consisting of barium, strontium, magnesium and calcium, an alkoxide or a carboxylate thereof, an ether solvent and / or an alcohol solvent, a carboxylic acid or After being added to a mixed solution comprising an ester solvent containing the same, heat treatment is performed at a temperature of 80 to 110 ° C. in a nitrogen or inert gas atmosphere, and the metal element concentration is 0.2 to 0.8 mol / L. Preparing an organic acid salt solution (A),
(2) An alkoxide or carboxylate of at least one element selected from the group consisting of titanium, tin and zirconium is added to an ester solvent, and the metal element concentration is 0.2 to 0.8 mol / L. A step of preparing an alkoxide liquid (B),
(3) The organic acid salt solution (A) and the alkoxide solution (B) are mixed in such a proportion that the total amount of metal elements contained in the former and the total amount of metal elements contained in the latter are equal in molar ratio. A step of synthesizing a complex organic acid salt solution (C) by mixing at a temperature of 80 to 130 ° C. in a nitrogen or inert gas atmosphere after mixing,
(4) The obtained complex organic acid salt solution (C) is heat-treated at a temperature of 80 to 125 ° C. in a nitrogen or inert gas atmosphere, thereby promoting the complex alkoxidation reaction, while the metal element concentration is increased. Step of diluting the metal element concentration to 0.2 to 0.4 mol / L by adding an alcohol solvent and an ester solvent after concentrating to 1.0 to 1.6 mol / L ,

  According to the second invention of the present invention, in the first invention, in the step (1), the blending ratio of the ether solvent and / or alcohol solvent and the carboxylic acid or the ester solvent containing it is used. Provides a method for producing a coating composition for forming a high dielectric thin film, wherein the volume ratio is from 2: 3 to 3: 2.

  According to a third invention of the present invention, in the first invention, in the step (1), the ether solvent is methyl cellosolve or ethyl cellosolve, and the alcohol solvent is 1-propanol, 2- And at least one selected from the group consisting of propanol, 1-butanol, 2-butanol and methanol, and the carboxylic acid is selected from the group consisting of 2-ethylhexanoic acid, 3-ethylhexanoic acid, and 3-methylpentanoic acid. And the ester-based solvent is at least one selected from the group consisting of ethyl acetate, n-butyl acetate, isobutyl acetate, and isopentyl acetate. A method for producing a coating composition is provided.

  According to the fourth invention of the present invention, in the third invention, the ether solvent is methyl cellosolve, the alcohol solvent is 2-propanol or 1-butanol, and the carboxylic acid is 2- There is provided a method for producing a coating composition for forming a high dielectric thin film, which is ethylhexanoic acid and the ester solvent is n-butyl acetate or isopentyl acetate.

  According to the fifth aspect of the present invention, in the first aspect, in the step (2), the ester solvent is selected from the group consisting of ethyl acetate, n-butyl acetate, isobutyl acetate and isopentyl acetate. There is provided a method for producing a coating composition for forming a high dielectric thin film, which is at least one kind.

  According to a sixth aspect of the present invention, there is provided the coating composition for forming a high dielectric thin film according to the first aspect, wherein the heating time is 2 to 10 hours in the step (3). A manufacturing method is provided.

  According to a seventh aspect of the present invention, in the first aspect, in the step (4), the ester solvent is n-butyl acetate or isobutyl acetate, and the alcohol solvent is 2-propanol. And / or 1-butanol. A method for producing a coating composition for forming a high dielectric thin film is provided.

  Moreover, according to the 8th invention of this invention, the coating composition for high dielectric material thin film formation obtained by the manufacturing method of the invention in any one of the 1st-7th is provided.

  The coating composition for forming a high dielectric thin film according to the present invention and the method for producing the same are as follows. In the formation of a high dielectric thin film made of a perovskite type dielectric material by the MOD method, there is no occurrence of cracks, the film shrinkage is small, and the dielectric properties Since the coating composition for forming a high dielectric thin film capable of forming an excellent dielectric thin film can be efficiently and stably produced, its industrial value is extremely large.

Hereinafter, the coating composition for forming a high dielectric thin film of the present invention and the production method thereof will be described in detail.
The manufacturing method of the coating composition for high dielectric thin film formation of this invention is characterized by including the process of following (1)-(4).
(1) At least one metal of an alkaline earth metal element selected from the group consisting of barium, strontium, magnesium and calcium, an alkoxide or a carboxylate thereof, an ether solvent and / or an alcohol solvent, a carboxylic acid or After being added to a mixed solution comprising an ester solvent containing the same, heat treatment is performed at a temperature of 80 to 110 ° C. in a nitrogen or inert gas atmosphere, and the metal element concentration is 0.2 to 0.8 mol / L. Preparing an organic acid salt solution (A),
(2) An alkoxide or carboxylate of at least one element selected from the group consisting of titanium, tin and zirconium is added to an ester solvent, and the metal element concentration is 0.2 to 0.8 mol / L. A step of preparing an alkoxide liquid (B),
(3) The organic acid salt solution (A) and the alkoxide solution (B) are mixed in such a proportion that the total amount of metal elements contained in the former and the total amount of metal elements contained in the latter are equal in molar ratio. A step of synthesizing a complex organic acid salt solution (C) by mixing at a temperature of 80 to 130 ° C. in a nitrogen or inert gas atmosphere after mixing,
(4) The obtained complex organic acid salt solution (C) is heat-treated at a temperature of 80 to 125 ° C. in a nitrogen or inert gas atmosphere, thereby promoting the complex alkoxidation reaction, while the metal element concentration is increased. Step of diluting the metal element concentration to 0.2 to 0.4 mol / L by adding an alcohol solvent and an ester solvent after concentrating to 1.0 to 1.6 mol / L ,

  In the production method of the present invention, it is important to carry out according to the procedure of the above steps. If this procedure is different, the stability of the resulting coating solution may be inferior, or the constituent metals may volatilize during firing during film formation, causing the film composition to deviate from the liquid composition.

  The step (1) of the production method of the present invention comprises at least one alkali earth metal element metal selected from the group consisting of barium, strontium, magnesium and calcium, an alkoxide or carboxylate thereof, an ether solvent ( Hereinafter, it may be abbreviated as ether) and / or an alcohol solvent (hereinafter sometimes abbreviated as alcohol) and a carboxylic acid or an ester solvent containing it (hereinafter abbreviated as ester). )), And then heat-treated in a nitrogen or inert gas atmosphere at a temperature of 80 to 110 ° C. to form an organic acid salt solution having a metal element concentration of 0.2 to 0.8 mol / L. This is a process for preparing (A).

In the step (1), by selecting the raw material form, the organic solvent, and the blending ratio thereof, the solubility and storage stability of the metal in the organic acid salt solution (A), and the coating for forming a high dielectric thin film The effect of satisfying the coating properties of the composition and the volatility or decomposability that causes film defects can be obtained.
For example, the stability of the liquid is improved by adding an ester and an ether. In particular, the ester has the effect of improving the coating properties by being added to the liquid.

  Here, when a metal is used as a raw material for alkaline earth metal elements such as barium, strontium, magnesium and calcium, and is dissolved in 2-propanol or methyl cellosolve, the carboxylic acid or ester having high solubility and low water miscibility If an appropriate amount of is mixed, a part of it will undergo substitution reaction with the alkyl group of the metal alkoxide to prepare a stable organic acid salt solution.

  Further, the carboxylate is not particularly limited, but a lower carboxylate such as barium acetate, calcium acetate, calcium ethylhexanoate is preferable. When these are used as raw materials, many of them are difficult to dissolve in lower alcohols, so they are dissolved in carboxylic acid or ester and carboxylic acid and then diluted with alcohol.

  Further, the alkoxide is not particularly limited, and examples thereof include methoxide, ethoxide, isopropoxide, butoxide and the like, but it is particularly preferable to use isopropoxide or butoxide because of an appropriate reaction rate. . When these are used as raw materials, higher alcohols, carboxylic acids, esters, or mixed solvents thereof can be suitably used. In addition, since lower alcohol contains water | moisture content and becomes unstable, it is not preferable.

  In the step (1), the blending ratio of the ether and / or alcohol, the carboxylic acid and the ester in the mixed solution is not particularly limited, and the volume ratio is 2: 3 to 3: 2. It is preferable. That is, if the blending ratio is outside this range, dissolution is insufficient and undissolved substances are likely to be generated, which is not preferable because precipitation occurs and the liquid becomes unstable. As a result, the stability of the liquid is increased, and even if it is not immediately mixed with the alkoxide liquid (B) to synthesize the perovskite type dielectric material, it can be obtained in a sealed container without any change for 3 months. . However, when no carboxylic acid is added, for example, a mixed solvent of alcohol and ester, the solubility of the metal is low and the storage stability of the liquid is poor.

On the other hand, when an organic solvent such as ether, alcohol, carboxylic acid or ester is used alone or in any combination other than the conditions of the present invention, the above effects cannot be obtained.
For example, when metals are used as raw materials for alkaline earth metal elements such as barium, strontium, magnesium, calcium, etc., they are easily dissolved in alcohol or ether, but the resulting alkoxide solution lacks stability against water and is therefore exposed to the open air. There is a problem that it cannot be stored and storage stability is poor. In general, by adding an equimolar amount of diketone acetylacetone, ethyl acetoacetate and the like to the metal alkoxide, the stability of the liquid is improved. However, the metal film which is the base electrode of the dielectric thin film There is a problem that the wettability of the film is poor, and cracks are generated during film baking, resulting in a decrease in film density.

  In addition, when a lower carboxylate is used as a raw material, as described above, many of them are difficult to dissolve in a lower alcohol, so that they are generally dissolved using an ester or a carboxylic acid. However, when only an ester is used, particles are precipitated during storage because of the low solubility of the carboxylate. Furthermore, there is a problem that the wettability with the metal film as the base electrode of the dielectric thin film is poor and a uniform film cannot be obtained. On the other hand, carboxylic acid is a useful organic solvent that stabilizes storage stability because it has high solubility and low water miscibility, but it is difficult to volatilize and remove by heating. Therefore, when a large amount of carboxylic acid is used, an organic component remains during film formation. The same applies to a mixed solution of an ester and a carboxylic acid.

  In addition, the ether, alcohol, carboxylic acid or ester used in the step (1) is not particularly limited, but the solubility of the raw material, the stability of the organic acid salt solution, the coatability during film formation, If the volatilization or decomposability at the time of film heat treatment is not good, the dielectric properties of the film will deteriorate, so it can be selected to optimize them.

  As the ether used in the step (1), methyl cellosolve or ethyl cellosolve having a boiling point of 200 ° C. or less is preferable, and methyl cellosolve is more preferable.

  The alcohol used in the step (1) is preferably at least one selected from the group consisting of 1-propanol, 2-propanol, 1-butanol, 2-butanol and methanol, more preferably 2-propanol and 1-butanol. preferable. That is, the boiling point of the alcohol used is preferably from 80 to 160 ° C, more preferably from 80 to 130 ° C. That is, by mixing those having a boiling point of 160 ° C. or less, volatilization or decomposability at the time of heat treatment of the formed film is improved, and a film with less shrinkage and cracks can be obtained. However, when an alcohol solvent having a boiling point of less than 80 ° C. is used, when the metal alkoxide solution is mixed and heated to synthesize a composite organic acid salt solution, the concentration of the solution fluctuates and the synthesis becomes unstable.

  The carboxylic acid used in the step (1) has a boiling point of 200 ° C. or lower, and is excellent in handleability, solubility and stability, from 2-ethylhexanoic acid, 3-ethylhexanoic acid, and 3-methylpentanoic acid. At least one ethylhexanoic acid selected from the group consisting of the above is preferred, and 2-ethylhexanoic acid is more preferred.

  The ester used in the step (1) is preferably at least one selected from the group consisting of ethyl acetate, n-butyl acetate, isobutyl acetate, and isopentyl acetate having a boiling point of 200 ° C. or less. More preferred is isopentyl acetate.

  The heating and melting conditions used in the step (1) are performed at a temperature of 80 to 100 ° C. That is, when the heating temperature is less than 80 ° C., the formation of the organic acid salt is insufficient. On the other hand, when heating temperature exceeds 100 degreeC, volatilization of the organic solvent will become active. Moreover, it does not specifically limit as heating time, 2 to 10 hours are preferable, and the time for the production | generation of organic acid salt is fully chosen is selected.

  The metal element concentration of the organic acid salt solution (A) obtained in the step (1) is 0.2 to 0.8 mol / L. That is, when the metal element concentration is less than 0.2 mol / L, the productivity is low because the concentration is dilute. On the other hand, when the metal element concentration exceeds 0.8 mol / L, the solution becomes insufficient and the solution is not stable. There is.

  The step (2) of the production method of the present invention comprises adding an alkoxide or carboxylate of at least one element selected from the group consisting of titanium, tin and zirconium into an ester solvent, and then adding nitrogen or an inert gas. It is a step of preparing an alkoxide liquid (B) having a metal element concentration of 0.2 to 0.8 mol / L by heating and melting at a temperature of 20 to 60 ° C. in an atmosphere.

The alkoxide used in the step (2) is not particularly limited, and examples thereof include methoxide, ethoxide, isopropoxide, butoxide and the like. In particular, since the reaction rate is appropriate, isopropoxide or It is preferable to use butoxide.
In addition, the carboxylate used in the step (2) is not particularly limited, and acetate or ethylhexanoate can be used.

  As the organic solvent used in the step (2), an ester solvent, particularly an acetate ester is used. That is, when the mixed solution is added with alcohol, it may gradually become cloudy and precipitate.

  The ester is preferably at least one selected from the group consisting of ethyl acetate, n-butyl acetate, isobutyl acetate, and isopentyl acetate having a boiling point of 200 ° C. or less, and more preferably n-butyl acetate or isopentyl acetate.

  The heating and melting conditions used in the step (2) are performed at a temperature of 20 to 60 ° C. That is, when the heating temperature is less than 20 ° C., the formation of the metal alkoxide is insufficient. On the other hand, when heating temperature exceeds 60 degreeC, volatilization of the organic solvent will become active. Moreover, it does not specifically limit as heating time, 10 minutes-2 hours are preferable, and time for formation of metal alkoxide fully is chosen.

  The metal element concentration of the alkoxide liquid (B) obtained in the step (2) is 0.2 to 0.8 mol / L. That is, when the metal element concentration is less than 0.2 mol / L, the productivity decreases when the concentration is dilute. On the other hand, when the metal element concentration exceeds 0.8 mol / L, dissolution is insufficient and the liquid is not stable.

  In the step (3) of the production method of the present invention, the organic acid salt solution (A) and the alkoxide solution (B) are obtained by adding the total amount of metal elements contained in the former and the total amount of metal elements contained in the latter. This is a step of synthesizing the composite organic acid salt solution (C) by mixing at a blending ratio such that the molar ratios are equal and then heat-treating at a temperature of 80 to 130 ° C. in a nitrogen or inert gas atmosphere. Here, the organic acid salt liquid (A) and the metal alkoxide contained in the alkoxide liquid (B) react to synthesize a complex organic acid salt that forms the perovskite complex oxide by thermal decomposition.

  The heating condition used in the step (3) is a temperature of 80 to 130 ° C. That is, when the heating temperature is less than 80 ° C., the synthesis reaction is insufficient, the constituent elements exist alone, the difference in hydrolysis rate occurs, and the uniformity of the film composition is inferior. On the other hand, when the heating temperature exceeds 130 ° C., not only the volatilization of the organic solvent is activated, but also the metal alkoxide is volatilized at the same time, resulting in a composition shift. Moreover, it does not specifically limit as heating time, 2-10 hours are preferable and the time for which synthesis | combination is fully performed is selected.

  In the step (4) of the production method of the present invention, the obtained complex organic acid salt solution (C) is heat-treated at a temperature of 80 to 125 ° C. in an atmosphere of nitrogen or an inert gas. After concentrating the metal element concentration to 1.0 to 1.6 mol / L while promoting the chlorination reaction, an alcohol solvent and an ester solvent are further added to reduce the metal element concentration to 0.2. This is a step of diluting to ~ 0.4 mol / L. As a result, a coating composition for forming a high dielectric thin film that satisfies the coating properties and storage stability, does not generate cracks, has a small film shrinkage, and has excellent dielectric properties. Is obtained.

  Here, first, the complex organic acid salt solution (C) is heated in an inert gas atmosphere at 80 to 125 ° C. to volatilize a part of the solvent, and once the metal element concentration is 1.0 to 1.6 mol. A high concentration solution of / L is prepared. The organic solvent is volatilized by introducing the inert gas while heating. At this time, most of the volatile organic solvent is a low boiling point, particularly an alcohol or an ester. Thereby, the synthesis reaction is further promoted by increasing the concentration. However, since precipitation occurs when the concentration is too high, 1.6 mol / L is the upper limit. On the other hand, if it is less than 1.0 mol / L, the synthesis effect cannot be expected. As the heating temperature at this time, 80 to 125 ° C. at which the synthesis reaction proceeds is used. In addition, when temperature exceeds 125 degreeC, volatilization of metal alkoxy will occur.

Next, an ester and alcohol are added to the high concentration liquid as a diluent at room temperature and mixed to adjust the metal element concentration to 0.2 to 0.4 mol / L. Here, as a diluent, the main component is alcohol which does not easily break the structure of the synthesized liquid. However, since the ester is reduced by increasing the concentration, the coating properties are inferior as it is. Therefore, it is necessary to add ester.

  The ester is not particularly limited, and n-butyl acetate or isobutyl acetate is preferable, and the alcohol is preferably 2-propanol and / or 1-butanol. As the blending ratio, alcohol: ester = 4: 1 to 2: 1 is preferable.

  The coating composition for forming a high dielectric thin film of the present invention is a coating composition for forming a high dielectric thin film obtained by the above-described manufacturing method, satisfies the coating properties and storage stability, and further generates cracks. Therefore, it is possible to form a dielectric thin film having a small film shrinkage and excellent dielectric characteristics. Various additives for improving the performance as a coating solution such as coating properties, storage stability, and crystallinity can be added to the coating composition for forming a high dielectric thin film. The additive is added in the step (4) or thereafter.

As a thin film forming method using the coating composition for forming a high dielectric thin film obtained by the production method of the present invention, for example, Si, Pt / Ti / SiO ₂ / Si, Pt / Ta / SiO ₂ / Si, Pt / SiO ₂ / Si, Ru / RuO ₂ / SiO ₂ / Si, RuO ₂ / Si, RuO ₂ / Ru / SiO ₂ / Si, Ir / IrO ₂ / Si, Pt / Ir / IrO ₂ / Si, Pt / IrO ₂ After the coating solution is dropped onto a substrate such as / Si, Pt / TiO ₂ / SiO ₂ / Si, it is applied by spin coating, dip coating or the like and dried. Next, temporary baking is performed at a temperature of 400 to 600 ° C. for about 10 minutes to 1 hour. Here, in order to obtain a desired film thickness, coating, drying, and pre-baking are repeated several times, followed by baking at a temperature of 700 to 900 ° C. for about 20 minutes to 2 hours to form a high dielectric thin film. .

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples. In addition, the analysis of the metal used by the Example and the comparative example, and the formation method and evaluation method of a thin film are as follows.
(1) Metal analysis: ICP emission analysis was performed.
(2) Thin film formation method and evaluation method: The coating solution was applied onto a titanium platinum substrate by spin coating, dried at 200 ° C., and then pre-baked in air or in an oxidizing atmosphere at 600 ° C. for 10 minutes. . Coating, drying, and pre-baking were repeated 6 times, followed by main baking at 800 ° C. for 1 hour in an oxygen gas stream to form a thin film made of a perovskite dielectric material. Thereafter, AFM observation of the film surface was performed to evaluate the occurrence of cracks and shrinkage. Further, a platinum upper electrode having a diameter of 0.3 mm was vapor-deposited on the thin film, and the relative dielectric constant and dielectric loss at an AC voltage of 1.0 V and a frequency of 1 MHz were measured in a room kept at 25 ° C.

(Example 1)
A barium titanate (BaTiO ₃ ) thin film was formed and evaluated.
First, as the process of (1), metal barium is added to 80 mL of a mixed solvent in which methyl cellosolve: 2-ethylhexanoic acid: n-butyl acetate = 2: 1: 1 is mixed at a volume ratio, and 80 ° C. in a nitrogen stream. And stirred for 2 hours to prepare a barium organic acid salt solution (A1) having a Ba concentration of 0.8 mol / L. In addition, as the step (2), titanium isopropoxide was added to 20 mL of n-butyl acetate, and the mixture was stirred and mixed at room temperature for 10 minutes to prepare a titanium alkoxide liquid (B1) having a Ti concentration of 0.8 mol / L.
Next, as the step (3), the titanium alkoxide liquid (B1) is dropped into the barium organic acid salt liquid (A1) so that the molar ratio of barium: titanium = 1: 1, and the nitrogen stream is at 110 ° C. The mixture was stirred and mixed for 2 hours to obtain a composite organic acid salt solution (C1) having a total concentration of 0.8 mol / L.

Next, as a step of (4), the complex organic acid salt solution (C1) is heated in a nitrogen stream at 125 ° C. for 1 hour to volatilize a part of the organic solvent, and a high concentration of metal element concentration of 1.2 mol / L. A liquid was obtained. Finally, a diluent obtained by adding 2-propanol and n-butyl acetate at a volume ratio of 2: 1 was added to the high-concentration solution, and the metal element concentration was adjusted to 0.4 mol / L to obtain a coating solution.
Thereafter, the thin film was formed according to the above-described thin film formation method and evaluation method, and the film surface was observed and the dielectric properties were evaluated. The results are shown in Tables 1 and 2.

(Example 2)
A barium titanate (BaTiO ₃ ) thin film was formed and evaluated.
In the step (3), the stirring and mixing temperature is 100 ° C., in the step (4), the heating temperature is 110 ° C., and the metal element concentration of the high concentration liquid is 1.0 mol / L. This was performed in the same manner as in Example 1 except that 2-propanol and n-butyl acetate were added to the high-concentration solution at a mixing ratio of 4: 1. Thereafter, the thin film was formed according to the above-described thin film formation method and evaluation method, and the film surface was observed and the dielectric properties were evaluated. The results are shown in Tables 1 and 2.

(Example 3)
A barium titanate (BaTiO ₃ ) thin film was formed and evaluated.
In the step (4), the heating time is 2 hours, the metal element concentration of the high concentration liquid is 1.6 mol / L, and the volume ratio of 2-propanol: n-butyl acetate: The same procedure as in Example 1 was performed except that an organic solvent blended with isopentyl acetate = 2: 2: 1 was added. Thereafter, the thin film was formed according to the above-described thin film formation method and evaluation method, and the film surface was observed and the dielectric properties were evaluated. The results are shown in Tables 1 and 2.

Example 4
A barium calcium titanate ((Ba, Ca) TiO ₃ ) thin film was formed and evaluated.
First, as step (1), metal barium is added to 100 mL of a mixed solvent containing 1-butanol: 2-ethylhexanoic acid: n-butyl acetate = 2: 1: 1 in a volume ratio, and 100 in a nitrogen stream. A barium organic acid salt solution (A1) with a Ba concentration of 0.4 mol / L was prepared by stirring and mixing at 2 ° C. for 2 hours. Furthermore, the calcium alkoxide liquid (A2) was prepared by using commercially available calcium 2-ethylhexanoate having a Ca concentration of 0.4 mol / L. (A1) and (A2) were mixed at a volume ratio of 9: 1 to prepare a barium calcium organic acid salt solution (A12), and 50 mL thereof was collected. Further, as the step (2), after adding titanium isopropoxide to n-butyl acetate and stirring and mixing at room temperature in air for 10 minutes to prepare a titanium alkoxide liquid (B1) having a Ti concentration of 0.4 mol / L, 50 mL of this was collected.
Next, as the step (3), the titanium alkoxide solution (B1) is dropped into the barium calcium organic acid salt solution (A12) so that the molar ratio of barium + calcium: titanium = 1: 1, and in a nitrogen stream The mixture was stirred and mixed at 110 ° C. for 2 hours to obtain a complex organic acid salt solution (C2) having a metal element concentration of 0.4 mol / L.

Next, as a step of (4), the composite organic acid salt solution (C2) is heated in a nitrogen stream at 125 ° C. for 3 hours to volatilize a part of the organic solvent, and a high concentration of metal element concentration of 1.1 mol / L. A liquid was obtained. Finally, 2-propanol and n-butyl acetate were added to the high concentration solution at a volume ratio of 3: 1 to adjust the metal element concentration to 0.4 mol / L to obtain a coating solution.
Thereafter, the thin film was formed according to the above-described thin film formation method and evaluation method, and the film surface was observed and the dielectric properties were evaluated. The results are shown in Tables 1 and 2.

(Comparative Example 1)
A barium titanate (BaTiO ₃ ) thin film was formed and evaluated.
First, as the step (1), barium 2-ethylhexanoate is added to 2-ethylhexanoic acid and stirred and mixed in a nitrogen stream at room temperature for 2 hours to obtain a barium organic acid salt having a Ba concentration of 0.8 mol / L. After preparing the liquid (A3), 50 mL thereof was collected. Moreover, after adding titanium isopropoxide to n-butyl acetate and stirring and mixing at room temperature in the atmosphere for 10 minutes as a step (2), a titanium alkoxide liquid (B2) having a Ti concentration of 0.8 mol / L is prepared. 50 mL thereof was collected.
Next, as the step (3), the titanium alkoxide liquid (B2) is dropped into the barium organic acid salt liquid (A3) so that the molar ratio of barium: titanium = 1: 1 is obtained, and the mixture is heated at 80 ° C. in a nitrogen stream. By stirring and mixing for 2 hours, a composite organic acid salt solution (C3) having a metal element concentration of 0.8 mol / L was obtained and used as a coating solution.
Thereafter, the thin film was formed according to the above-described thin film formation method and evaluation method, and the film surface was observed and the dielectric properties were evaluated. The results are shown in Tables 1 and 2. The thin film forming method is different in that the pre-baking temperature is 500 ° C. and the number of repetitions of coating, drying, and pre-baking is three.

(Comparative Example 2)
A barium titanate (BaTiO ₃ ) thin film was formed and evaluated.
The same procedure as in Example 1 was performed except that the concentration of the complex organic acid salt solution (C1) was not performed in the step (4). A diluent obtained by adding 2-propanol and n-butyl acetate at a volume ratio of 2: 1 was added to the high-concentration solution, and the metal element concentration was adjusted to 0.4 mol / L to obtain a coating solution.
Thereafter, the thin film was formed according to the above-described thin film formation method and evaluation method, and the film surface was observed and the dielectric properties were evaluated. The results are shown in Tables 1 and 2.

(Comparative Example 3)
A barium titanate (BaTiO ₃ ) thin film was formed and evaluated.
In the step (4), the same procedure as in Example 1 was performed except that the heating time was 3 hours and that the metal element concentration of the high-concentration liquid was 1.9 mol / L. Thereafter, the thin film was formed according to the above-described thin film formation method and evaluation method, and the film surface was observed and the dielectric properties were evaluated. The results are shown in Tables 1 and 2. When the coating solution was observed, a slightly cloudy precipitate was observed.

  From Tables 1 and 2, in Examples 1 to 4, a step of preparing an organic acid salt solution (A) of an alkaline earth metal element using a specific mixed solution, titanium, tin and a specific organic solvent. A step of preparing an alkoxide liquid (B) of at least one element selected from the group consisting of zirconium, and a composite organic acid salt liquid (C) is synthesized using the organic acid salt liquid (A) and the alkoxide liquid (B). The process and the step of concentrating the complex organic acid salt solution (C) and then diluting to adjust the concentration of the metal element were sequentially performed according to the method of the present invention, so that the perovskite type dielectric material by the MOD method was used. In the formation of a high dielectric thin film, a coating composition for forming a high dielectric thin film capable of forming a dielectric thin film that is free from cracks, has a small film shrinkage, and has excellent dielectric properties can be efficiently obtained. You know .

  On the other hand, in Comparative Examples 1 to 3, the specific mixed solution was not used in the step (1), the concentration of the complex organic acid salt solution (C) was not performed in the step (4), In addition, the metal element concentration of the high-concentration liquid does not meet the conditions of the present invention due to any deviation from the predetermined concentration, so that a satisfactory dielectric constant is obtained with a low relative dielectric constant and a high dielectric loss. I understand that there is no.

  As is apparent from the above, the coating composition for forming a high dielectric thin film and the method for producing the same according to the present invention are coating compositions for forming a high dielectric thin film capable of forming a dielectric thin film having excellent dielectric properties. Since this is an efficient manufacturing method, it is used for capacitor insulating films used for thin film capacitors and capacitive insulating films of semiconductor integrated circuit devices, DRAM capacitor materials, and the like.

Claims (8)

The manufacturing method of the coating composition for high dielectric material thin film formation including the process of following (1)-(4).
(1) At least one metal of an alkaline earth metal element selected from the group consisting of barium, strontium, magnesium and calcium, an alkoxide or a carboxylate thereof, an ether solvent and / or an alcohol solvent, a carboxylic acid or After being added to a mixed solution comprising an ester solvent containing the same, heat treatment is performed at a temperature of 80 to 110 ° C. in a nitrogen or inert gas atmosphere, and the metal element concentration is 0.2 to 0.8 mol / L. Preparing an organic acid salt solution (A),
(2) An alkoxide or carboxylate of at least one element selected from the group consisting of titanium, tin and zirconium is added to an ester solvent, and the metal element concentration is 0.2 to 0.8 mol / L. A step of preparing an alkoxide liquid (B),
(3) The organic acid salt solution (A) and the alkoxide solution (B) are mixed in such a proportion that the total amount of metal elements contained in the former and the total amount of metal elements contained in the latter are equal in molar ratio. A step of synthesizing a complex organic acid salt solution (C) by mixing at a temperature of 80 to 130 ° C. in a nitrogen or inert gas atmosphere after mixing,
(4) The obtained complex organic acid salt solution (C) is heat-treated at a temperature of 80 to 125 ° C. in a nitrogen or inert gas atmosphere, thereby promoting the complex alkoxidation reaction, while the metal element concentration is increased. Step of diluting the metal element concentration to 0.2 to 0.4 mol / L by adding an alcohol solvent and an ester solvent after concentrating to 1.0 to 1.6 mol / L ,   In the step (1), the mixing ratio of the ether solvent and / or the alcohol solvent and the carboxylic acid or the ester solvent containing the solvent is 2: 3 to 3: 2 by volume. The manufacturing method of the coating composition for high dielectric material thin film formation of Claim 1.   In the step (1), the ether solvent is methyl cellosolve or ethyl cellosolve, and the alcohol solvent is at least one selected from the group consisting of 1-propanol, 2-propanol, 1-butanol, 2-butanol and methanol. The carboxylic acid is at least one selected from the group consisting of 2-ethylhexanoic acid, 3-ethylhexanoic acid, and 3-methylpentanoic acid, and the ester solvent is ethyl acetate, n-acetate The method for producing a coating composition for forming a high dielectric thin film according to claim 1, wherein the coating composition is at least one selected from the group consisting of butyl, isobutyl acetate, and isopentyl acetate.   The ether solvent is methyl cellosolve, the alcohol solvent is 2-propanol or 1-butanol, the carboxylic acid is 2-ethylhexanoic acid, and the ester solvent is n-butyl acetate or acetic acid. The method for producing a coating composition for forming a high dielectric thin film according to claim 3, wherein the coating composition is isopentyl.   2. The high dielectric material according to claim 1, wherein in the step (2), the ester solvent is at least one selected from the group consisting of ethyl acetate, n-butyl acetate, isobutyl acetate and isopentyl acetate. The manufacturing method of the coating composition for thin film formation.   2. The method for producing a coating composition for forming a high dielectric thin film according to claim 1, wherein in the step (3), the heating time is 2 to 10 hours.   In the step (4), the ester solvent is n-butyl acetate or isobutyl acetate, and the alcohol solvent is 2-propanol and / or 1-butanol. A method for producing a coating composition for forming a dielectric thin film.   A coating composition for forming a high dielectric thin film obtained by the production method according to claim 1.