JP5117042B2 - Coating agent for complex oxide film formation - Google Patents

Description

The present invention is a composite oxide film forming coating agent for forming a titanium-containing perovskite composite oxide film, and relates to the production how the titanium-containing perovskite composite oxide film using such a coating agent.

A composite oxide having a perovskite-type crystal structure represented by the general formula ABO ₃ , among which a perovskite-type titanium-containing composite oxide has excellent electrical properties such as dielectric properties, piezoelectricity, and pyroelectricity. It is used as a material for various electronic components. For example, perovskite-type titanium-containing composite oxides use various dielectrics such as multilayer ceramic capacitors, dielectric filters, dielectric antennas, dielectric resonators, and dielectric duplexers by utilizing their high dielectric properties. It is used as a dielectric material for capacitors, phase shifters, etc. Perovskite-type titanium-containing composite oxides are used as piezoelectric materials for laminated piezoelectric actuators and the like by utilizing their piezoelectricity. Further, perovskite-type titanium-containing composite oxides have been tried to be applied to various fields.

The titanium-containing composite oxide represented by the general formula ATiO ₃ (A site represents at least one or two or more metal elements selected from Ca, Sr, Ba, or Pb) is a perovskite type. It has a crystal structure of In this case, it is known that various electric characteristics are exhibited depending on the difference in the solid solution ratio (composition ratio) of atoms at the A site.

For example, barium titanate (BaTiO ₃ ) exhibits a high dielectric constant while having a large temperature dependency. Therefore, a part of the A site is replaced with a metal element called a shifter such as Ca, Sr, Ba, or Pb. The perovskite-type titanium-containing composite oxide thus obtained can shift the Curie point to the low temperature side or shift the second phase transition point to the high temperature side. Furthermore, in a ceramic capacitor using such a perovskite-type titanium-containing composite oxide, the dielectric constant near room temperature can be increased, and the temperature dependence of capacitance can be broadened.

  Such a titanium-containing composite oxide can be produced, for example, by adding a compound containing a metal element such as Ca, Sr, Ba, and Pb to a powder of barium titanate and baking it. However, since such a manufacturing method is a thick film process, only a titanium-containing composite oxide film having a film thickness of 1 μm or more can be obtained practically. The capacitance of the capacitor is proportional to the electrode area and the dielectric constant of the dielectric layer, and inversely proportional to the distance between the electrodes. Therefore, in order to reduce the size and increase the capacity of the capacitor, it is necessary to increase the relative dielectric constant and reduce the film thickness of the above-described titanium-containing composite oxide film.

As a method for forming a titanium-containing composite oxide film, there are an MOCVD method, a sputtering method, an ion beam method, and the like. However, in any of the film forming methods, it is difficult to strictly control the composition ratio of atoms at the A site when the perovskite type titanium-containing composite oxide film represented by ATiO ₃ described above is manufactured.

  Therefore, methods for forming a titanium-containing composite oxide film on a substrate by a wet thin film forming method such as a coating method or a dip method have been proposed (see, for example, Patent Documents 1 to 3 and Non-Patent Documents 1 and 2). .) Such a wet thin film forming method does not require complicated and large-scale equipment, and has an advantage that the ratio of the metal composition in the composite oxide film can be easily controlled.

  By the way, in the method described in Non-Patent Document 1, titanium alkoxide is used. However, titanium alkoxides are difficult to handle because they are unstable in water. That is, the alkoxide of titanium is easily hydrolyzed by water, and may be deposited as titanium oxide before forming the composite oxide film. That is, the state of the aqueous solution is not maintained. In this case, even if the coating agent is prepared by precisely controlling the ratio of the metal composition, it is difficult to form a complex oxide film having a uniform composition on the substrate coated with the coating agent. Further, when such a coating agent is used, it is difficult to uniformly form a complex oxide film on the substrate. Furthermore, when preparing a coating agent, since it is necessary to select the compound which does not raise | generate a hydrolysis, it becomes difficult to add various metal elements by such restrictions.

On the other hand, in the method described in Patent Document 1, temperature and pH are controlled in order to dissolve the barium compound without decomposing titanium alkoxide. However, since the temperature is as high as 50 to 110 ° C., it is difficult to handle and it is difficult to control the film thickness because stable film formation cannot be performed. Furthermore, KOH is used to control the pH (pH 13 or higher). However, since it is impossible to completely remove KOH from the film after film formation by washing with water or the like, KOH remaining without being removed will adversely affect the electrical characteristics. On the other hand, in the method described in Patent Document 2, methanol is used as a solvent. However, water is difficult to handle because it should not contain water. On the other hand, in the method described in Patent Document 3, a method for producing a titanium-containing composite oxide using a water-soluble titanium compound is disclosed. However, since only water is used as the solvent, in this case, it is difficult to coat the substrate with a large surface tension. On the other hand, the method described in Non-Patent Document 2 is difficult to handle because it is performed in a glow box.
Japanese Patent Laid-Open No. 5-124817 JP 2005-39282 A JP 2001-322815 A Materials Chemistry and Physics, Vol.69, 2001, 166-171 Thin Solid Films, Vol.353, 1999, 144-148

The present invention has been proposed in view of such conventional circumstances, a composite oxide film-forming coating agent capable of uniformly forming a perovskite-type titanium-containing composite oxide film on a substrate , and , and an object thereof is to provide a manufacturing how the titanium-containing perovskite composite oxide film using such a coating agent.

The present invention provides the following means.
(1) A film is formed by applying to a substrate, and this is fired to obtain a general formula ATiO ₃ (A site is at least one or two or more metals selected from Ca, Sr, Ba or Pb) A composite oxide film-forming coating agent that forms a perovskite-type titanium-containing composite oxide film represented by the following formula: a titanium compound that coordinates a β-diketone and a β-diketone A coating agent for forming a complex oxide film comprising a solution containing a compound containing a metal element at the A site and a surfactant .
(2) β-diketone is 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 2,2,6-trimethyl-3,5 -Coating agent for complex oxide film formation of the preceding clause (1) which is either heptanedione or 3,5-heptanedione.
(3) The coating agent for forming a complex oxide film according to (1) or (2), further comprising at least one selected from ammonia, amine, amino alcohol, hydroxycarboxylic acid, alcohol, and carboxylic acid .
( 4 ) Perovskite-type titanium-containing composite oxide film represented by the general formula ATiO ₃ (A site represents at least one metal element selected from Ca, Sr, Ba, or Pb). A perovskite-type titanium-containing composite comprising a coating step of applying the coating agent according to any one of (1) to ( 3 ) on a substrate and a baking step of baking the substrate. Manufacturing method of oxide thin film.
( 5 ) The method for producing a perovskite-type titanium-containing composite oxide thin film according to ( 4 ), wherein the firing temperature is 300 ° C or higher and 1500 ° C or lower.
( 6 ) The method for producing a perovskite-type titanium-containing composite oxide thin film according to ( 4 ) or ( 5 ) above, wherein the firing time is from 1 minute to 24 hours.
( 7 ) The method for producing a composite oxide thin film according to ( 4 ), wherein firing is performed at a firing temperature of 600 ° C. or more and 1500 ° C. or less after firing is performed at a firing temperature of 300 ° C. or more and less than 600 ° C.
( 8 ) The perovskite-type titanium-containing composite oxide according to any one of ( 4 ) to ( 7 ) above, which includes a drying step of drying the coating agent applied on the substrate between the coating step and the baking step. Manufacturing method of physical film.
( 9 ) The method for producing a perovskite-type titanium-containing composite oxide film according to ( 8 ), wherein the drying temperature is 100 ° C. or higher and lower than 300 ° C.
( 10 ) The method for producing a perovskite titanium-containing composite oxide film according to ( 8 ) or ( 9 ), wherein the drying time is from 1 minute to 3 hours.
( 11 ) The perovskite type according to any one of ( 4 ) to ( 10 ), wherein the composition ratio of the metal element at the A site to Ti contained in the titanium-containing composite oxide film is 0.98 to 1.02. A method for producing a titanium-containing composite oxide film.

  As described above, according to the present invention, it is possible to obtain a coating agent for forming a complex oxide film that has good storage stability, can be applied in the air, is easy to handle, and can be applied at room temperature. Therefore, a perovskite-type titanium-containing composite oxide film can be uniformly formed on the substrate using such a composite oxide film-forming coating agent.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for convenience, and the dimensional ratios of the respective components are the same as the actual ones. Not exclusively.

A coating agent for forming a composite oxide film to which the present invention is applied is formed by coating on a substrate, and is baked to obtain a general formula ATiO ₃ (A site is in Ca, Sr, Ba or Pb). Represents a perovskite-type titanium-containing composite oxide film represented by the following formula: a titanium compound that coordinates a β-diketone; It consists of a solution with a compound containing a metal element.

  Among these, for β-diketones, for example, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 2,2,6-trimethyl- Examples include 3,5-heptanedione and 3,5-heptanedione.

  The solvent for dissolving the titanium compound that coordinates β-diketone is not particularly limited, and examples thereof include 1-butanol, t-butanol, and acetylacetone.

  The composite oxide film-forming coating agent of the present invention improves the solubility of the compound added to the solution, the wettability with the substrate, the film formability, the adhesion, the denseness of the film after drying or baking, and the like. Therefore, it is further effective to add a compound such as ammonia, amine, amino alcohol, alcohol, carboxylic acid, or hydroxycarboxylic acid to the solution.

Specifically, examples of the amine include monoamines such as monomethylamine, monoethylamine, dimethylamine, diethylamine, trimethylamine, and triethylamine, and ethylenediamine.
Examples of amino alcohols include monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-methyldiethanolamine, and N-propylethanolamine.
Examples of the alcohol include alcohols such as methanol, ethanol and propyl alcohol, and glycols such as ethylene glycol, diethylene glycol and propylene glycol.
Examples of the carboxylic acid include monocarboxylic acids such as formic acid, acetic acid, and propionic acid, and dicarboxylic acids such as malonic acid and succinic acid.
Examples of the hydroxycarboxylic acid include hydroxymonocarboxylic acid and hydroxydicarboxylic acid.

  In the composite oxide film-forming coating agent of the present invention, for example, a surfactant such as a non-ionic surfactant or an anionic surfactant may be added to the solution. It may be added to the solution.

The metal element at the A site may be any element that forms a composite oxide with titanium contained in the titanium compound described above, and examples thereof include alkaline earth metals such as Ca, Sr, and Ba, and Pb. . Moreover, as a compound containing the metal element of these A sites, what is necessary is just what melt | dissolves in the solvent mentioned above, For example, the metal element compound of the said A site which coordinates (beta) -diketone can be mentioned. Among these, for β-diketones, for example, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 2,2,6-trimethyl- Examples include 3,5-heptanedione and 3,5-heptanedione. Furthermore, specific examples of the compound containing the metal element at the A site include, for example, calcium chloride, calcium nitrate, calcium acetate, strontium chloride, strontium nitrate, barium hydroxide, barium chloride, barium nitrate, barium acetate, lead nitrate. And lead acetate. Among them, in particular, a hydroxide capable of removing a counter ion of a metal by at least one of evaporation, sublimation, and thermal decomposition at a firing temperature or lower in a firing step described later and under atmospheric pressure or reduced pressure. Hydroxycarboxylates are preferably used, and examples thereof include barium hydroxide, barium acetate, barium formate, calcium acetate, calcium hydroxide, calcium citrate, strontium acetate, strontium hydroxide, and lead acetate. In addition, these compounds may be used individually by 1 type, or may mix and use 2 or more types by arbitrary ratios. In the present invention, by using one or more of these compounds, for example, a metal oxide film such as BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , BaSrTiO ₃ , BaSrCaTiO ₃ , SrCaTiO ₃ , and PbTiO ₃ can be obtained. it can.

  The solution further includes at least one or two selected from W, Nb, Ta, Sn, Si, Bi, Al, B, Co, Zn, Mg, Ni, Mn, Fe, and rare earth elements. You may add the compound containing the above element. In this case, it is preferable that these elements are contained in less than 5 mol% in the complex oxide after reaction. In the present invention, electrical characteristics can be improved by adding such a metal element.

  A method for producing a composite oxide film to which the present invention is applied includes a coating step of coating the above-described coating agent of the present invention on a substrate, a drying step of drying the coating agent coated on the substrate, and a substrate after drying. The perovskite-type titanium-containing composite oxide film described above can be formed through the firing step of firing.

  Specifically, the base material is not particularly limited as long as it can withstand the firing temperature and atmosphere described above. Specific examples of the base material include glass, aluminum oxide, silicon, nickel, titanium, and platinum. Among them, in particular, when firing at a high temperature of 600 ° C. or higher in an air atmosphere, it is preferable to use aluminum oxide, platinum, or the like excellent in heat resistance. Furthermore, the material of the substrate can be appropriately selected according to the application, and for example, a conductor, a semiconductor, an insulator, or the like can be used. Further, the base may be, for example, a composite body in which a metal and an insulator are bonded together.

  Examples of the base material suitable for the use of the capacitor include metals such as gold, silver, copper, nickel, platinum, palladium, and aluminum, alloys containing them, and conductors such as carbon. By forming a complex oxide film on a substrate made of these materials, the substrate can be used as it is as an electrode of a capacitor.

  There is no restriction | limiting in particular about the shape of a base | substrate, For example, a plate-shaped thing, a foil-like thing, and the thing whose surface is not smooth can be mentioned. In addition, as the shape of the substrate suitable for the use of the capacitor, since the ratio of the composite oxide film to the substrate increases and it becomes advantageous as the surface area per unit mass of the substrate becomes smaller and lighter, the foil shape is advantageous. A foil having a thickness of 1 to 300 μm, more preferably 3 to 100 μm, and still more preferably 5 to 30 μm can be used.

  In the case of using a foil as the substrate, it is preferable to perform etching in advance by chemical etching, electrolytic etching, or the like to form irregularities on the surface. Thereby, the surface area of the substrate can be increased. Similarly, in order to increase the ratio of the composite oxide film to the substrate, a fine particle sintered body having an average particle diameter of 0.1 to 20 μm, more preferably 1 to 10 μm can be used as the substrate. In this embodiment, a case where a substrate is used as a base and a complex oxide film is formed on the substrate will be described as an example.

  There is no restriction | limiting in particular in the film thickness of complex oxide film, What is necessary is just to control a film thickness according to a use. As the film thickness of the composite oxide film suitable for capacitor applications, the capacitor capacity increases as the composite oxide film thickness decreases, and the capacitor leakage current decreases as the composite oxide film thickness increases. Therefore, the film thickness may be set according to the desired capacity and leakage current.

  In the coating step, the coating agent prepared by controlling the ratio of the metal composition in the solution described above is coated on the substrate by spin coating. As described above, since the coating agent of the present invention has good wettability with respect to the substrate, it can be uniformly formed on the substrate. Moreover, when applying a coating agent by such a spin coat method, the thickness of the coating film can be easily adjusted by controlling the rotation speed of the substrate, the viscosity of the coating agent, and the like.

  Specifically, the metal compound concentration in the coating agent is preferably adjusted so as to be 1 to 20% by mass in terms of complex oxide. If this concentration is less than 1% by mass, the film thickness per spin coating is too thin, and the number of spin coatings increases to obtain a predetermined film thickness. On the other hand, when this concentration exceeds 20% by mass, it becomes difficult to form a dense coating film.

  In the present invention, the coating agent is preferably degassed in order to reduce defects during drying and firing described later. In order to improve wettability with the substrate, it is preferable to wash the substrate surface, and etching or the like for improving wettability may be performed on the substrate surface.

  In the drying step, it is preferable to dry the substrate coated with the above-described coating agent in a temperature range of 100 ° C. or more and less than 300 ° C. for 1 minute to 3 hours, and in a temperature range of 120 to 200 ° C. for 5 minutes to 2 hours. More preferably, it is made. Thereby, the solvent contained in the coating agent apply | coated on the board | substrate can be distilled off. For example, a method such as reduced pressure drying, hot air drying, or freeze drying can be used for drying. Moreover, the atmosphere in particular at the time of drying is not restrict | limited, It can carry out in air | atmosphere or under pressure reduction.

  A uniform coating film (a precursor of the composite oxide film) can be formed on the substrate through such a drying step. In addition, although a solvent can be distilled off in a short time, so that drying temperature is high, it becomes easy to produce a defect. Moreover, although it is preferable to completely distill off the solvent in the drying step, there is no problem even if it remains because the solvent can be distilled off in the subsequent baking step.

  In the firing step, the substrate on which the above-described coating film has been formed is preferably fired in the temperature range of 300 to 1500 ° C. for 1 minute to 24 hours. Moreover, the atmosphere in particular at the time of baking is not restrict | limited, It can carry out in air | atmosphere or under pressure reduction.

  This baking process is performed in order to make the coating film which is the precursor of the composite oxide film into a composite oxide film and further improve the crystallinity thereof. In addition, by this baking step, impurities such as by-products generated when the precursor is made into a composite oxide and solvent remaining without being distilled off in the drying step are evaporated, sublimated and / or thermally decomposed. It can be removed as a gas or by burning.

  In addition, the composite oxide film can have higher crystallinity when fired in the absence of impurities such as carbon. Therefore, in this case, it is preferable to perform two-stage firing in which impurities are completely removed at a relatively low firing temperature and then fired again at a firing temperature higher than that. Specifically, the substrate on which the above-described coating film is formed is baked in a temperature range of 300 ° C. or higher and lower than 600 ° C. for 1 minute to 2 hours, and then in a temperature range of 600 ° C. or higher and 1500 ° C. or lower for 1 minute to 24 hours. Baking is preferable.

  Through such a baking process, a perovskite-type titanium-containing composite oxide film with improved crystallinity can be formed on the substrate.

  As described above, in the method for producing a composite oxide film to which the present invention is applied, a composite oxide film formed of a solution of the titanium compound coordinated with the β-diketone described above and a compound containing a metal element at the A site is formed. By using the coating agent, a perovskite-type titanium-containing composite oxide film can be uniformly formed on the substrate. In addition, the coating agent for forming a complex oxide film of the present invention has good storage stability, can be applied in the air, is easy to handle, and can be applied at room temperature.

Furthermore, the manufacturing method of the present invention does not require complicated and large-scale equipment, and the ratio of the metal composition in the composite oxide film can be easily controlled. Specifically, in the present invention, the content of the A-site metal element contained in the titanium-containing composite oxide film formed on the substrate surface is controlled by controlling the content ratio of the A-site metal element contained in the solution. The ratio can be easily controlled. For example, it is known that perovskite-type titanium-containing composite oxides represented by the general formula ATiO ₃ exhibit various electrical characteristics depending on the composition ratio of atoms at the A site. When the production method of the present invention is used, the composition ratio of the A site atoms contained in the solution is almost the same as the composition ratio of the A site contained in the titanium-containing composite oxide film formed on the substrate surface. When preparing the above-described solution, the content ratio of the A site atoms contained in the titanium-containing composite oxide film formed on the substrate surface is controlled by controlling the content ratio of the A site contained in the solution. It can be easily controlled.

  The crystal structure of the perovskite-type titanium-containing composite oxide can be known by X-ray diffraction measurement, and the A-site atom ratio (solid solution ratio) in the perovskite-type titanium-containing composite oxide is determined by X-ray diffraction. It can be obtained from the peak position in the figure.

  In the present invention, the composition ratio of the metal element at the A site to Ti contained in the obtained titanium-containing composite oxide film is preferably 0.98 to 1.02, more preferably 0.995 to 1. 0.015, more preferably 0.99 to 1.01. In order to improve the electrical characteristics of the perovskite-type titanium-containing composite oxide film, there is no problem even if another compound is added and used.

  Further, in the manufacturing method of the present invention, the film thickness can be easily controlled, and the above manufacturing process can be repeated to increase the film thickness of the composite oxide film. Further, in the production method of the present invention, in addition to the method in which the coating agent is applied by one spin coating, the film thickness is reduced per spin coating, and a plurality of spin coatings are performed until the coating film reaches a predetermined film thickness. A dense coating film having no defects can be formed by repeating the drying, drying and firing. Further, the composite oxide film can be made to have a predetermined film thickness by reducing the film thickness per spin coating, drying and baking, and repeating this several times. Also in this case, a dense complex oxide film free from defects can be formed.

  In the production method of the present invention, in addition to the coating method such as the spin coating method described above, a wet film formation method such as a dip method in which the substrate is directly immersed in the solution constituting the coating agent of the present invention is used. Also good.

  As described above, according to the production method of the present invention, the composite of the present invention in which the perovskite-type titanium-containing complex oxide film having a high relative dielectric constant is formed on the surface of the substrate can be obtained. In the present invention, such a composite can be suitably used as the dielectric material or piezoelectric material of the present invention. Furthermore, in the present invention, the capacitor of the present invention can be configured by sandwiching this dielectric material between a pair of electrodes, and the piezoelectric element of the present invention can be configured by sandwiching this piezoelectric material between a pair of electrodes.

  Specifically, the dielectric material including the composite according to the present invention can be used as it is as a component of the capacitor dielectric and one electrode as long as the substrate is a conductive material. For the other electrode of the capacitor (the counter electrode of the one electrode), for example, a metal such as gold, silver, copper, nickel, platinum, palladium, or aluminum, an alloy containing them, or a conductor such as carbon Can be used. These electrodes may be electrically connected to the external leads of the capacitor.

  Examples of the electrode forming method include a method of forming a conductor on the composite oxide film by using a wet method such as electrolytic plating, electroless plating, or applying a metal paste, a sputtering method, a vapor deposition method, or the like. . Alternatively, the electrode may be formed by using a conductive polymer, manganese dioxide, carbon paste, silver paste, nickel paste or the like alone or in admixture of two or more at any ratio.

  Moreover, the capacitance can be increased by stacking the capacitors thus formed in parallel. For example, a conductor is formed on the composite oxide film of the composite of the present invention, and the composite oxide film of the present invention and the conductor are sequentially laminated on this conductor as a base, and finally, By connecting an external electrode to the conductor, a capacitor electrically connected in parallel can be obtained (see, for example, FIG. 1). Further, as a method of manufacturing the capacitor thus laminated, for example, a composite oxide film is applied on a nickel foil by a spin coating method and dried, and then the obtained dielectric layer is sputtered with nickel. The internal electrode is formed by By repeating this process, a laminated body in which the dielectric layer and the internal electrode are sequentially laminated is formed. A multilayer capacitor can be obtained by cutting the multilayer body into a desired size and connecting external electrodes to the side surfaces of the capacitor obtained by firing (see, for example, FIG. 1).

  In the composite of the present invention, as described above, the thickness of the composite oxide film is thin and uniform. Furthermore, this complex oxide film has a high relative dielectric constant. Therefore, the capacitor of the present invention using such a composite (dielectric material) can be further reduced in size and capacity. Furthermore, the electronic device of the present invention provided with such a capacitor can be further reduced in size and weight.

  On the other hand, the piezoelectric material including the composite of the present invention can be used as it is as a component of the piezoelectric body of the piezoelectric element and one electrode. And in the piezoelectric element of this invention using such a composite_body | complex (piezoelectric material), further size reduction and the improvement of an electrical property are possible. Furthermore, the electronic device of the present invention provided with such a piezoelectric element can be further reduced in size and weight.

  In particular, in the present invention, the composite oxide film containing a perovskite compound is excellent in electrical characteristics such as dielectric properties, piezoelectricity, pyroelectricity, etc., for example, various capacitors such as multilayer ceramic capacitors, dielectrics, etc. It can be suitably used for electronic parts such as a body filter, a dielectric antenna, a dielectric resonator, a dielectric duplexer, a phase shifter, a piezoelectric element, and a laminated piezoelectric actuator.

FIG. 1 is a cross-sectional view showing a multilayer ceramic capacitor 1 as an example of a capacitor which is an electronic component of the present invention.
As shown in FIG. 1, the multilayer ceramic capacitor 1 includes a multilayer body 5 in which a dielectric layer 2 and internal electrodes 3 and 4 are sequentially stacked, and an external electrode 6 attached to a side surface of the multilayer body 5. 7. One end of each of the internal electrodes 3, 4 is exposed on the side surface of the laminate 5, and each one end is connected to the external electrodes 6, 7.

  In this multilayer ceramic capacitor 1, a perovskite-type titanium-containing composite oxide film was produced as a dielectric layer 2 on the surface of a Ti foil forming one of the internal electrodes 3 and 4 by using the production method of the present invention. Is. The external electrodes 6 and 7 are made of, for example, a sintered body made of Ag, Cu, Ni or the like and plated with Ni.

  In this multilayer ceramic capacitor 1, a perovskite titanium-containing composite oxide having a high dielectric constant is used for the dielectric layer 2. In the multilayer ceramic capacitor 1, the thickness of the dielectric layer 2 can be reduced while maintaining a high dielectric constant. Therefore, the multilayer ceramic capacitor 1 can be further reduced in size and capacity.

FIG. 2 is a plan view showing a mobile phone as an example of the electronic apparatus of the present invention.
The capacitor 1 shown in FIG. 1 is used by being mounted on a circuit board 11 of a mobile phone 10 as shown in FIG. 2, for example. Therefore, the mobile phone 10 can be further reduced in size and weight.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

Example 1
In Example 1, first, 18.5 g of a titanium compound 1-butanol solution coordinated with 3,5-heptanedione (Narsem titanium manufactured by Nippon Chemical Industry Co., Ltd., titanium content: 8.9% by mass) was added to 18.5 g of bis (acetylacetate). (Nato) 12.7 g of barium dihydrate (Nasemubarium manufactured by Nippon Kagaku Sangyo Co., Ltd.) and 28.0 g of lactic acid (manufactured by Wako Pure Chemical Industries, Ltd.) were dissolved. Furthermore, 10.8 butanol (made by Wako Pure Chemical Industries, Ltd.) 40.8 was added, and the coating agent for complex oxide film formation of Example 1 was prepared.

  Next, the coating agent of Example 1 was applied on a glass substrate, an alumina substrate, a silicon substrate, a nickel substrate, a titanium substrate, and a platinum substrate by spin coating, and then dried at 150 ° C. for 1 hour. The operation from spin coating to drying was repeated three times. And when the obtained board | substrate was observed visually, the uniform coating film was formed in the surface of all the board | substrates. Next, among the substrates on which the coating film was formed, the platinum substrate was baked at 500 ° C. for 1 hour in the air atmosphere, and then further baked at 900 ° C. for 1 hour.

  Then, when the obtained sample of Example 1 was identified by X-ray diffraction, it was found that barium titanate having a tetragonal perovskite structure was formed on the surface of the platinum substrate. The layer thickness of this barium titanate was found to be 0.18 μm when a cross-section processed sample with an FIB apparatus was observed with a TEM.

The crystallite size was measured as follows. As a result, the crystallite size was 63 nm.
Equipment ;: X-ray diffractometer (Rigaku Electric rotor flex)
Measurement angle: 2θ; 21 ° to 94 °
Measurement step: 0.02 °
Analysis method: Rietveld analysis (Rietan)

Next, a nickel film having a diameter of 2 mm and a thickness of 0.2 μm was formed by electron beam evaporation on the surface of the platinum substrate on which the composite oxide film was formed, thereby producing a capacitor. The nickel film was used as one electrode and the platinum substrate was used as the other electrode, and the capacitance of the capacitor was measured under the following conditions.
Apparatus: LCR meter (NF circuit design block ZM2353 type)
Measurement frequency: 120Hz
Amplitude: 1V
Measurement temperature: 25 ° C
As a result, the capacitance of the capacitor of Example 1 was 30 μF / cm ² .
Furthermore, the leakage current of the capacitor of Example 1 was 4 × 10 ⁻⁵ A.

(Example 2)
In Example 2, first, titanium compound 1-butanol solution coordinated with 3,5-heptanedione (Narsem titanium manufactured by Nippon Kagaku Sangyo Co., Ltd., titanium content: 8.9% by mass) was added to 18.5 g, and bis (acetylacetate). Natto 12.7 g of barium dihydrate (Nasemubarium manufactured by Nippon Kagaku Sangyo Co., Ltd.) and 14.0 g of 2-aminoethanol (manufactured by Wako Pure Chemical Industries, Ltd.) were dissolved. Further, 54.8 g of 1-butanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added to prepare a composite oxide film-forming coating agent of Example 2.

  Next, the coating agent of Example 2 was applied on a glass substrate, an alumina substrate, a silicon substrate, a nickel substrate, a titanium substrate, and a platinum substrate by spin coating, and then dried at 150 ° C. for 1 hour. The operation from spin coating to drying was repeated three times. And when the obtained board | substrate was observed visually, the uniform coating film was formed in the surface of all the board | substrates. Next, among the substrates on which the coating film was formed, the platinum substrate was baked at 500 ° C. for 1 hour in the air atmosphere, and then further baked at 900 ° C. for 1 hour.

  Then, when the obtained sample of Example 2 was identified by X-ray diffraction, it was found that barium titanate having a tetragonal perovskite structure was formed on the surface of the platinum substrate. The layer thickness of the barium titanate was found to be 0.17 μm when a cross-section processed sample with an FIB apparatus was observed with a TEM. The crystallite size was 65 nm.

And the capacitor was produced similarly to Example 1, and the characteristic of the capacitor was measured. As a result, the capacitance of the capacitor of Example 2 was 34 μF / cm ² , and the leakage current was 2 × 10 ⁻⁵ A.

(Example 3)
In Example 3, first, 18.5 g of titanium compound 1-butanol solution coordinated with 3,5-heptanedione (Narsem titanium manufactured by Nippon Chemical Industry Co., Ltd., titanium content 8.9 mass%) was added to 18.5 g of bis (acetylacetate). Nato) 12.4 g of barium dihydrate (Nasemubarium manufactured by Nippon Chemical Industry Co., Ltd.), 0.3 g of bis (acetylacetonato) calcium dihydrate (Nasemu calcium manufactured by Nippon Chemical Industry Co., Ltd.), 14.0 g of 2-aminoethanol (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved. Further, 55.6 g of 1-butanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added to prepare a composite oxide film-forming coating agent of Example 3.

  Next, the coating agent of Example 3 was applied on a glass substrate, an alumina substrate, a silicon substrate, a nickel substrate, a titanium substrate, and a platinum substrate by spin coating, and then dried at 150 ° C. for 1 hour. The operation from spin coating to drying was repeated three times. And when the obtained board | substrate was observed visually, the uniform coating film was formed in the surface of all the board | substrates. Next, among the substrates on which the coating film was formed, the platinum substrate was baked at 500 ° C. for 1 hour in the air atmosphere, and then further baked at 900 ° C. for 1 hour.

  The obtained sample of Example 3 was identified by X-ray diffraction. As a result, barium titanate having a tetragonal perovskite structure in which barium and calcium were dissolved in 97: 3 (molar ratio) on the surface of the platinum substrate. It was found that calcium was generated. The layer thickness of this barium calcium titanate was found to be 0.18 μm when a cross-section processed sample with an FIB apparatus was observed with a TEM. The crystallite size was 50 nm.

And the capacitor was produced similarly to Example 1, and the characteristic of the capacitor was measured. As a result, the capacitance of the capacitor of Example 3 was 35 μF / cm ² , and the leakage current was 1 × 10 ⁻⁶ A.

Example 4
In Example 4, first, titanium compound 1-butanol solution coordinated with 3,5-heptanedione (Narsem titanium manufactured by Nippon Kagaku Sangyo Co., Ltd., titanium content 8.9 mass%) was added to 18.5 g, and bis (acetylacetate). Nato) 9.6 g of barium dihydrate (Nasemubarium manufactured by Nippon Kagaku Sangyo Co., Ltd.), 2.7 g of bis (acetylacetonato) strontium dihydrate (Nasemu Strontium manufactured by Nippon Kagaku Sangyo Co., Ltd.), 14.0 g of 2-aminoethanol (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved. Further, 55.2 g of 1-butanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added to prepare a composite oxide film-forming coating agent of Example 4.

  Next, the coating agent of Example 4 was applied on a glass substrate, an alumina substrate, a silicon substrate, a nickel substrate, a titanium substrate, and a platinum substrate by spin coating, and then dried at 150 ° C. for 1 hour. The operation from spin coating to drying was repeated three times. And when the obtained board | substrate was observed visually, the uniform coating film was formed in the surface of all the board | substrates. Next, among the substrates on which the coating film was formed, the platinum substrate was baked at 500 ° C. for 1 hour in the air atmosphere, and then further baked at 900 ° C. for 1 hour.

  The obtained sample of Example 4 was identified by X-ray diffraction. As a result, barium titanate having a tetragonal perovskite structure in which barium and strontium were dissolved in a molar ratio of 4: 1 on the surface of the platinum substrate. It was found that strontium was formed. The layer thickness of this barium strontium titanate was found to be 0.18 μm when a cross-section processed sample with an FIB apparatus was observed with a TEM. The crystallite size was 49 nm.

And the capacitor was produced similarly to Example 1, and the characteristic of the capacitor was measured. As a result, the capacitance of the capacitor of Example 4 was 192 μF / cm ² , and the leakage current was 9 × 10 ⁻⁹ A.

(Example 5)
In Example 5, a complex oxide was formed on the surface of the platinum substrate in the same manner as in Example 1 except that the platinum substrate coated with the coating agent of Example 1 was baked at 1000 ° C. for 1 hour in the air atmosphere. A film was formed.

  Then, when the obtained sample of Example 5 was identified by X-ray diffraction, it was found that barium titanate having a tetragonal perovskite structure was formed on the surface of the platinum substrate. The crystallite size of the generated barium titanate was 77 nm.

And the capacitor was produced similarly to Example 1, and the characteristic of the capacitor was measured. As a result, the capacitance of the capacitor of Example 5 was 31 μF / cm ² , and the leakage current was 4 × 10 ⁻⁵ A.

(Comparative Example 1)
In Comparative Example 1, first, titanium isopropoxide (manufactured by Wako Pure Chemical Industries, Ltd.) 11.7 g, barium isopropoxide 20% isopropanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) 33.8 g, and 3,5-heptane When 13.7 g of dione (manufactured by Wako Pure Chemical Industries, Ltd.) and 40.8 g of isopropyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.) were added to adjust the coating agent for forming the complex oxide film, the coating agent was prepared during the preparation. Became cloudy.

  Next, the coating agent of Comparative Example 1 was stirred as much as possible, and applied on a glass substrate, an alumina substrate, a silicon substrate, a nickel substrate, a titanium substrate, and a platinum substrate by a spin coating method. Dry for hours. The operation from spin coating to drying was repeated three times. And when the obtained board | substrate was observed visually, the particulate thing was observed on the surface in any board | substrate.

  Next, among the substrates on which the coating film was formed, the platinum substrate was baked at 500 ° C. for 1 hour in the air atmosphere, and then further baked at 900 ° C. for 1 hour. And when the sample of the obtained comparative example 1 was identified by X-ray diffraction, it turned out that the barium carbonate, titanium oxide, and barium titanate are producing | generating on the surface of a platinum substrate.

(Comparative Example 2)
In Comparative Example 2, first, titanium isopropoxide (manufactured by Wako Pure Chemical Industries, Ltd.) 11.7 g, barium isopropoxide 20% isopropanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) 33.8 g, and 3,5-heptane 13.7 g of dione (manufactured by Wako Pure Chemical Industries, Ltd.) and 40.8 g of isopropyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.) were added. When prepared in a dehumidified glow box, a transparent coating agent for forming a complex oxide film was obtained.

  Next, the coating agent of Comparative Example 2 was applied on a glass substrate, an alumina substrate, a silicon substrate, a nickel substrate, a titanium substrate, and a platinum substrate, respectively, by spin coating, and then dried at 150 ° C. for 1 hour. The operation from spin coating to drying was repeated three times. And when the obtained board | substrate was observed visually, the uniform coating film was formed in the surface of all the board | substrates.

  Next, among the substrates on which the coating film was formed, the platinum substrate was baked at 500 ° C. for 1 hour in the air, and then further baked at 900 ° C. for 1 hour. It was.

(Comparative Example 3)
In Comparative Example 3, first, titanium compound 1 in which 28.0 g of lactic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 3,5-heptanedione were coordinated to 40.8 g of 1-butanol (manufactured by Wako Pure Chemical Industries, Ltd.) -18.5g of butanol solution (Nippon Kagaku Sangyo Co., Ltd. Nursem titanium, titanium content 8.9 mass%) was melt | dissolved. Furthermore, when 12.7 g of bis (acetylacetonato) barium dihydrate (Nasemubarium manufactured by Nippon Kagaku Sangyo Co., Ltd.) was added to prepare a composite oxide film-forming coating agent of Comparative Example 3, bis ( Acetylacetonato) barium dihydrate did not dissolve completely.

  Next, among the substrates on which the coating film was formed, the platinum substrate was baked at 500 ° C. for 1 hour in the air atmosphere, and then further baked at 900 ° C. for 1 hour. And when the sample of the obtained comparative example 3 was identified by X-ray diffraction, it turned out that the barium carbonate, titanium oxide, and barium titanate are producing | generating on the surface of a platinum substrate.

FIG. 1 is a cross-sectional view showing a multilayer ceramic capacitor which is an example of an electronic component of the present invention. FIG. 2 is a plan view showing a mobile phone as an example of the electronic apparatus of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 2 ... Dielectric layer 3, 4 ... Internal electrode 5 ... Laminate 6, 7 ... External electrode 10 ... Mobile telephone 11 ... Circuit board

Claims (11)

A film is formed by applying to a substrate, and this is baked to give a general formula ATiO ₃ (A site represents at least one or two or more metal elements selected from Ca, Sr, Ba or Pb) .) Is a composite oxide film-forming coating agent for forming a perovskite-type titanium-containing composite oxide film, wherein a titanium compound that coordinates β-diketone and an A site that coordinates β-diketone A coating agent for forming a complex oxide film comprising a solution containing a compound containing a metal element and a surfactant .   β-diketone is 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 2,2,6-trimethyl-3,5-heptanedione The coating agent for forming a complex oxide film according to claim 1, which is any one of 3,5-heptanedione.   Furthermore, the coating agent for complex oxide film formation of Claim 1 or 2 containing at least 1 or more types chosen from ammonia, an amine, amino alcohol, hydroxycarboxylic acid, alcohol, and carboxylic acid. Method for producing perovskite type titanium-containing composite oxide film represented by general formula ATiO ₃ (A site represents at least one or two or more metal elements selected from Ca, Sr, Ba or Pb) A method for producing a perovskite-type titanium-containing composite oxide thin film comprising a coating step of coating the substrate with the coating agent according to any one of claims 1 to 3 and a firing step of firing the substrate. . The method for producing a perovskite-type titanium-containing composite oxide thin film according to claim 4 , wherein the firing temperature is 300 ° C or higher and 1500 ° C or lower. The method for producing a perovskite-type titanium-containing composite oxide thin film according to claim 4 or 5 , wherein the firing time is from 1 minute to 24 hours. 5. The method for producing a composite oxide thin film according to claim 4 , wherein firing is performed at a firing temperature of 600 ° C. or more and 1500 ° C. or less after firing is performed at a firing temperature of 300 ° C. or more and less than 600 ° C. 6. The method for producing a perovskite-type titanium-containing composite oxide film according to any one of claims 4 to 7 , further comprising a drying step of drying the coating agent applied on the substrate between the coating step and the baking step. The method for producing a perovskite-type titanium-containing composite oxide film according to claim 8 , wherein the drying temperature is 100 ° C or higher and lower than 300 ° C. The method for producing a perovskite-type titanium-containing composite oxide film according to claim 8 or 9 , wherein the drying time is from 1 minute to 3 hours. The perovskite titanium-containing composite oxide film according to any one of claims 4 to 10 , wherein the composition ratio of the metal element at the A site to Ti contained in the titanium-containing composite oxide film is 0.98 to 1.02. Manufacturing method.

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