JP5205930B2 - Method for producing metal oxide film - Google Patents

Description

  The present invention relates to a method for producing a metal oxide film, which can obtain a metal oxide film whose crystallinity and crystal structure are changed stepwise or continuously by a simple method.

  Conventionally, it has been known that metal oxide films exhibit various excellent physical properties. Taking advantage of these properties, metal oxide films have been used in a wide range of fields such as transparent conductive films, optical thin films, and fuel cell electrolytes. As a method for producing such a metal oxide film, for example, a sol-gel method, a sputtering method, a CVD method, a PVD method, a printing method, a laser ablation method and the like are known (for example, Patent Documents 1 and 2).

  On the other hand, a spray pyrolysis method has been proposed as another method for obtaining such a metal oxide film. The spray pyrolysis method is a method in which a metal oxide film is obtained by spraying a solution containing a metal source constituting the metal oxide film onto a high temperature substrate, and a substrate heated to about 500 ° C. is usually used. Since it is used, the solvent instantly evaporates and the metal source undergoes a thermal decomposition reaction, so that the metal oxide film can be obtained in a short and simplified process.

As a study of such spray pyrolysis method, for example, in Patent Document 3, a raw material solution is prepared by adding hydrogen peroxide or aluminum acetylacetonate to a solution containing a TiO ₂ precursor, and the temperature is as high as about 500 ° C. A method is disclosed in which a TiO ₂ precursor is thermally decomposed into TiO ₂ by intermittently spraying the raw material solution onto a held substrate to obtain a porous TiO ₂ thin film on the substrate. Further, for example, Patent Document 4 is a method for obtaining a porous TiO ₂ thin film by a pyrolysis spray method as in Patent Document 3, but by adding a solution in which a soluble titanium compound is added to a raw material solution, TiO ₂ is obtained. ₍₂₎ The adhesion between the thin film and the substrate was improved.

  As described above, although the spray pyrolysis method is a method capable of obtaining a metal oxide film in a short time and a simplified process, the crystallinity and crystal structure of the obtained metal oxide film are different from the metal of the material. In some cases, depending on the type of source, a metal oxide film having a desired crystal state cannot be obtained. Further, for example, in an optical thin film or an insulating / conductive film interface in the field of semiconductors or electronics, it is preferable that the crystallinity of the surface of the metal oxide film on the substrate side is high, and the surface opposite to the surface of the substrate side The crystallinity of is preferably low. Thus, a metal oxide film whose crystal state is changed stepwise or continuously in the stacking direction or the like is desired, but such a metal oxide film has not been known so far.

JP 2002-348665 A JP-A-4-361239 JP 2002-145615 A JP 2003-176130 A

  The present invention has been made in view of the above circumstances, and a metal oxide capable of obtaining a metal oxide film in which the crystallinity and crystal structure of the crystal structure are changed stepwise or continuously by a simple method. The main object is to provide a method for producing a film.

  The present inventor has found that when an acid is added to a metal oxide film forming solution, a metal oxide film obtained using a metal oxide film forming solution to which no acid is added is compared with a metal oxide film obtained by previous studies. Thus, it has been found that a metal oxide film having a changed crystal state can be obtained. Specifically, it has been clarified that it is possible to adjust the film quality, such as increasing the crystallinity of the metal oxide film, lowering the crystallinity to make it amorphous, or changing the crystal structure. ing. Although the detailed principle of this phenomenon is not always clear, the state of the solvent surrounding the metal ion is changed by adding an acid, and as a result, the metal oxide film formed by thermal decomposition of the metal source This is thought to be because the crystal state of the crystal changes.

  The present invention has been made based on this finding, and by changing the concentration of the acid contained in the metal oxide film forming solution over time, the crystallinity and the crystalline state of the crystal structure are changed stepwise or The present inventors have found that a continuously changed metal oxide film can be formed and have completed the present invention.

  That is, in the present invention, a solution for forming a metal oxide film in which a metal salt or an organometallic compound is dissolved as a metal source and the acid concentration for changing the crystal state of the metal oxide film is different is used. Forming a metal oxide film whose crystal state is changed stepwise or continuously on the base material by contacting the base material heated to a temperature equal to or higher than the metal oxide film formation temperature while changing A method for producing a metal oxide film is provided.

  According to the present invention, by bringing a metal oxide film forming solution into contact with a substrate heated to a temperature equal to or higher than the metal oxide film forming temperature while changing the acid concentration, A metal oxide film whose state changes stepwise or continuously can be obtained by a simple method.

In the above-mentioned invention, the acid, HF, _HCl, HBr, it is preferred that the _{HNO 2, HNO 3, H 2} SO 4 or _H 3 PO _4. This is because the crystal state of the metal oxide film can be effectively changed.

  In the said invention, it is preferable that the said solution for metal oxide film formation contains a doping metal source further. This is because a functional oxide film can be obtained by using a doping metal source.

  In the above invention, the metal element constituting the metal source is Mg, Al, Si, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ag, In, Sn, Ce, Sm. Pb, La, Hf, Sc, Gd, Ca, Cr, Ga, Sr, Nb, Mo, Pd, Sb, Te, Ba, W, or Ta are preferable. This is because metal oxide films useful for various applications can be obtained.

  In the present invention, there is an effect that a metal oxide film whose crystallinity and crystal state of crystal structure are changed stepwise or continuously can be obtained by a simple method.

  Hereinafter, the manufacturing method of the metal oxide film of this invention is demonstrated in detail.

  The method for producing a metal oxide film of the present invention comprises a solution for forming a metal oxide film in which a metal salt or an organometallic compound is dissolved as a metal source and the concentration of the acid for changing the crystal state of the metal oxide film is different The metal oxide whose crystal state is changed stepwise or continuously on the base material by contacting with the base material heated to a temperature equal to or higher than the metal oxide film formation temperature while changing the acid concentration. A film is formed.

  In the present invention, “crystalline state” means crystallinity and crystal structure. From the viewpoint of crystallinity of the metal oxide film, in the present invention, by changing the acid concentration, the crystallinity of the obtained metal oxide film can be increased or decreased stepwise or continuously. can do. On the other hand, from the viewpoint of the crystal structure of the metal oxide film, in the present invention, by changing the acid concentration, it is possible to obtain a metal oxide film whose crystal structure is changed stepwise or continuously. .

  According to the present invention, by bringing a metal oxide film forming solution into contact with a substrate heated to a temperature equal to or higher than the metal oxide film forming temperature while changing the acid concentration, A metal oxide film whose state changes stepwise or continuously can be obtained by a simple method.

  An advantage of changing the crystallinity of the obtained metal oxide film is, for example, that the adhesion between the substrate and the metal oxide film can be improved. For example, when a metal oxide film with high crystallinity is directly formed on a substrate, the adhesion at the interface between the substrate and the metal oxide film may be inferior. On the other hand, the adhesiveness in an interface can be improved by making the crystallinity of the base-material side surface of a metal oxide film low. On the other hand, by increasing the crystallinity of the surface of the metal oxide film opposite to the substrate side, for example, when the metal oxide film is used as a catalyst, the reactivity can be improved. . Thus, by changing the crystallinity and the like of the metal oxide film stepwise or continuously in the stacking direction, a metal oxide film having excellent adhesion and reactivity can be obtained.

  In addition, for example, in a laminate provided with a base material such as titanium oxide having photocatalytic performance, the base material side surface of the metal oxide film is made amorphous, and the opposite side surface is made anatase crystal, It is possible to sufficiently exhibit the photocatalytic activity on the outer side (surface opposite to the substrate side surface) while minimizing damage to the substrate due to photocatalytic activity.

  As an advantage of changing the crystal structure of the obtained metal oxide film, for example, generation of grain boundaries at the interface between the base material and the metal oxide film can be suppressed. Specifically, when considering a transparent conductive film (metal oxide film) provided on titanium oxide (base material) of a dye-sensitized solar cell, a cubic ITO film is formed on titanium oxide having anatase type crystals. If the layer is provided, lattice matching is not good, grain boundaries are generated at the interface, and the electron conductivity is not only inferior, but also the adhesion is insufficient. On the other hand, if the ITO at the interface with titanium oxide is hexagonal ITO, lattice matching is better than that of cubic ITO, and it is possible to reduce the grain boundaries generated at the interface, and the electron conductivity and adhesion Can be improved. On the other hand, columnar cubic ITO is formed on the surface opposite to the substrate side surface of the metal oxide film, so the electron conductivity in the stacking direction is excellent, and electrons are smoothly transferred to the current collecting electrode. Can improve battery performance.

  Next, the manufacturing method of the metal oxide film of this invention is demonstrated using drawing. FIG. 1 is an explanatory view showing an example of a method for producing a metal oxide film of the present invention. In the method for producing a metal oxide film shown in FIG. 1, first, a metal oxide film forming solution A containing zirconium tetraacetylacetonate, zirconium tetraacetylacetonate and nitric acid are contained, and the concentration of nitric acid is 0.00. A metal oxide film forming solution B having 001 mol / l and a metal oxide film forming solution C containing zirconium tetraacetylacetonate and nitric acid and having a nitric acid concentration of 0.01 mol / l are prepared ( (Abbreviated as solutions A to C, respectively). Next, the metal oxide film is formed on the substrate 1 by sequentially spraying the solutions A to C on the substrate 1 heated to a temperature equal to or higher than the metal oxide film formation temperature by using the spray device 2. Is the method. By using this method, a metal oxide film whose crystal state is changed stepwise in the stacking direction can be obtained.

  Moreover, FIG. 2 is explanatory drawing which shows the other example of the manufacturing method of the metal oxide film of this invention. In the method for producing a metal oxide film shown in FIG. 2, first, a solution A containing zirconium tetraacetylacetonate and an acid D (for example, nitric acid) that changes the crystal state of the metal oxide film are prepared. Next, the substrate 1 heated to a temperature equal to or higher than the metal oxide film formation temperature is sprayed with the solution A at first, and then the flow rate of the acid D with respect to the solution A is gradually increased. In this method, a metal oxide film is formed on the substrate 1 by spraying. By using this method, a metal oxide film whose crystal state continuously changes in the stacking direction can be obtained.

  In the present invention, the “metal oxide film formation temperature” refers to a temperature at which a metal element contained in a metal source can combine with oxygen and form a metal oxide film on a substrate. It varies greatly depending on the type of metal source such as salt and organometallic compound and the composition of the metal oxide film forming solution such as solvent. In the present invention, such “metal oxide film formation temperature” can be measured by the following method. That is, the lowest base material on which a metal oxide film can be formed by preparing a solution for forming a metal oxide film that actually contains a desired metal source and changing the heating temperature of the base material to make contact Measure the heating temperature. This minimum substrate heating temperature can be set as the “metal oxide film forming temperature” in the present invention. At this time, whether or not the metal oxide film is formed is usually judged from the result obtained from an X-ray diffraction apparatus (Rigaku, RINT-1500). In the case of an amorphous film having no crystallinity, photoelectron spectroscopy is performed. It shall judge from the result obtained from the analyzer (the product made by VG Scientific, ESCALAB 200i-XL).

As described above, the metal oxide film formation temperature varies depending on the type of the metal source used, but is usually in the range of 200 to 600 ° C. In the present invention, the heating temperature of the substrate is not particularly limited as long as the temperature is higher than the metal oxide film formation temperature. For example, the metal oxide film formation temperature + 300 ° C. It is preferable that the film formation temperature + 200 ° C. or lower, particularly the metal oxide film formation temperature + 100 ° C. or lower. The heating temperature of the substrate is usually in the range of 300 to 600 ° C.
Hereafter, the manufacturing method of the metal oxide film of this invention is demonstrated in detail for every structure.

1. Metal Oxide Film Forming Solution First, the metal oxide film forming solution used in the present invention will be described. In the present invention, a metal oxide film-forming solution in which a metal salt or an organometallic compound is dissolved as a metal source and the concentration of acid for changing the crystal state of the metal oxide film is different is used.

  When the crystal state of the metal oxide film is changed stepwise, the metal oxide film forming solution to be used is usually two or more types, and preferably two or three types. In the present invention, at least one metal oxide film-forming solution containing a metal source and an acid may be used. Therefore, a metal oxide film forming solution containing no acid may be used in combination with a metal oxide film forming solution containing an acid.

On the other hand, when the crystal state of the metal oxide film is continuously changed, the metal oxide film forming solution used is usually one kind. In this case, by gradually adding an acid to the metal oxide film forming solution, a metal oxide film whose crystal state is continuously changed can be obtained.
Hereinafter, the metal source contained in the metal oxide film forming solution will be described first, and then the acid, solvent, and additive will be described.

(1) Metal source First, the metal source used in the present invention will be described. The metal source used in the present invention is usually a metal salt or an organometallic compound. In the present invention, two or more kinds of metal sources may be used in combination.

In the present invention, the metal source is preferably a metal source capable of forming a single film by itself. Here, the “metal source capable of forming a single film” refers to a metal source that provides a metal oxide film that satisfies a predetermined standard in the following test. That is, a metal oxide film forming solution (concentration: 0.1 mol / l) comprising one target metal source and a solvent (for example, ethanol, toluene, or acetylacetone is preferably used) is prepared. The oxide film forming solution was made into droplets having a particle size of about 0.5 to 20 μm using an ultrasonic neplyzer or the like, and heated within the range of the metal oxide film forming temperature to the metal oxide film forming temperature + 100 ° C. A metal oxide film is formed on the substrate by contacting with the material for 1 hour, and then the obtained metal oxide film is cooled to room temperature, and the region of the metal oxide film of about 1 cm ^{2 is} subjected to a pressure of 0. A test of wiping with a waste cloth at about 2 Pa is performed. As a result, a metal source that provides a metal oxide film having a strength that does not cause peeling is referred to as a “metal source capable of forming a single film” in the present invention. In addition, as a base material, what is used when forming a metal oxide film actually is used. In addition, when the obtained metal oxide film is a powder, the metal oxide film does not correspond to a metal source capable of forming a single film because it easily peels off when wiped with a waste cloth or the like.

  The metal element constituting the metal source is not particularly limited as long as it can form a metal oxide film. For example, Mg, Al, Si, Ti, V, Mn, Fe, Co, Ni Cu, Zn, Y, Zr, Ag, In, Sn, Ce, Sm, Pb, La, Hf, Sc, Gd, Ca, Cr, Ga, Sr, Nb, Mo, Pd, Sb, Te, Ba, W In particular, Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, In, Sn, Ce, and La are preferable.

  The metal salt is not particularly limited as long as it can form a metal oxide film. For example, chlorides, nitrates, sulfates, perchlorates, acetates containing the above metal elements, A phosphate, a bromate, etc. can be mentioned. Among these, in the present invention, it is preferable to use chloride, nitrate, and acetate. This is because these compounds are easily available as general-purpose products. Specific examples of the metal salt include magnesium chloride, aluminum nitrate, aluminum chloride, calcium chloride, scandium acetate, titanium tetrachloride, vanadium oxosulfate, ammonium chromate, chromium chloride, ammonium dichromate, and chromium acetate. , Chromium nitrate, chromium sulfate, manganese acetate, manganese nitrate, manganese sulfate, iron chloride (I), iron chloride (III), iron acetate (II), iron nitrate (III), iron sulfate (II), ammonium iron sulfate (III ), Cobalt chloride, cobalt nitrate, cobalt acetate, nickel chloride, nickel nitrate, nickel acetate, copper chloride, copper nitrate, zinc chloride, zinc acetate, zinc chloride, yttrium nitrate, yttrium chloride, zirconium chloride oxide, zirconium nitrate oxide, four Zirconium chloride, silver chloride, silver acetate, indium chloride, indetic acetate Um, tin chloride, tin acetate, tin sulfate, cerium chloride, cerium acetate, cerium nitrate, cerium oxalate, diammonium cerium nitrate, cerium sulfate, samarium chloride, samarium nitrate, lead chloride, lead acetate, lead nitrate, lead iodide , Lead phosphate, lead sulfate, lanthanum chloride, lanthanum acetate, lanthanum nitrate, gadolinium nitrate, strontium chloride, strontium acetate, strontium nitrate, niobium pentachloride, ammonium molybdate phosphate, molybdenum sulfide, palladium chloride, palladium acetate, palladium nitrate , Antimony pentachloride, antimony trichloride, antimony trifluoride, telluric acid, barium sulfite, barium chloride, barium chlorate, barium perchlorate, barium acetate, barium nitrate, tungstic acid, ammonium tungstate, tongue hexachloride Ten, tantalum pentachloride, hafnium chloride, mention may be made of sulfuric acid such as hafnium.

  The organometallic compound is not particularly limited as long as it can form a metal oxide film, and specific examples include acetylacetonate complexes. Examples of the acetylacetonate-based complex include aluminum acetylacetonate, iron (III) acetylacetonate, nickel (II) acetylacetonate dihydrate, copper (II) acetylacetonate, zinc acetylacetonate, zirconium Tetraacetylacetonate, zirconium monoacetylacetonate, tris (acetylacetonato) indium (III), chromium (III) acetylacetonate, cobalt acetylacetonate, cerium acetylacetonate, lanthanum acetylacetonate, titanium acetylacetonate, Examples thereof include calcium acetylacetonate, molybdenyl acetylacetonate, and palladium acetylacetonate.

  Examples of organometallic compounds other than acetylacetonate complexes include magnesium diethoxide, calcium di (methoxyethoxide), calcium gluconate monohydrate, calcium citrate tetrahydrate, and calcium salicylate dihydrate. , Titanium lactate, tetraisopropyl titanate, tetranormal butyl titanate, tetra (2-ethylhexyl) titanate, butyl titanate dimer, titanium bis (ethylhexoxy) bis (2-ethyl-3-hydroxyhexoxide), diisopropoxy titanium bis (tri Ethanolaminate), dihydroxybis (ammonium lactate) titanium, diisopropoxytitanium bis (ethylacetoacetate), ammonium peroxocitrate tetrahydrate, dicyclopentadi Nyl iron (II), iron (II) lactate trihydrate, copper (II) dipivaloylmethanate, copper (II) ethyl acetoacetate, zinc lactate trihydrate, zinc salicylate trihydrate, stearic acid Zinc, strontium dipivaloylmethanate, yttrium dipivaloylmethanate, zirconium tetra-n-butoxide, zirconium (IV) ethoxide, zirconium normal propylate, zirconium normal butyrate, zirconium acetylacetonate bisethylacetoacetate, Zirconium acetate, zirconium monostearate, penta-n-butoxy niobium, pentaethoxy niobium, pentaisopropoxy niobium, indium (III) 2-ethylhexanoate, tetraethyl tin, dibutyl tin oxide (IV), tricyclohexyl tin (IV) Hydroxide, Li (methoxyethoxy) lanthanum, pentaisopropoxytantalum, pentaethoxytantalum, tantalum (V) ethoxide, lead (II) citrate trihydrate, lead cyclohexanebutyrate, gallium (III) trifluoromethanesulfonate, strontium dipivalo Ilmethanate and the like can be mentioned.

  In the present invention, the metal source is preferably a zirconium-containing metal source containing a zirconium element. This is because a zirconium oxide film whose crystal state is changed stepwise or continuously can be obtained. The zirconium-containing metal source is not particularly limited as long as it contains a zirconium element. As described above, a metal salt containing a zirconium element may be used, and an organic metal containing a zirconium element. A compound may be used, but among them, an organometallic compound containing a zirconium element is preferable. Particularly in the present invention, the zirconium-containing metal source is preferably zirconium acetylacetonate.

  The concentration of the metal source in the metal oxide film forming solution is not particularly limited, but for example, within the range of 0.001 to 1 mol / l, particularly within the range of 0.01 to 0.5 mol / l. Preferably there is. This is because if the concentration is within the above range, the metal oxide film can be formed in a relatively short time.

  In the present invention, it is also possible to add a doping metal source for the purpose of doping the metal oxide film. A functional oxide film can be obtained by using a doping metal source.

  The kind of the doping metal source is preferably selected as appropriate according to the kind of the target metal oxide film. For example, when obtaining a yttria-stabilized zirconia film (YSZ film) useful as an electrolyte of a solid oxide fuel cell, a metal source having a yttrium element is used as a doping metal source in addition to a metal source having a zirconium element. Specific examples of the metal source having an yttrium element include yttrium nitrate hexahydrate. That is, in the present invention, the metal source is preferably a combination of a zirconium-containing metal source containing a zirconium element and an yttrium-containing metal source containing an yttrium element. This is because it is possible to obtain a YSZ film whose crystal state is changed stepwise or continuously. In addition, about a zirconium containing metal, it is the same as that of said content. The yttrium-containing metal source is not particularly limited as long as it contains an yttrium element. As described above, it may be a metal salt containing an yttrium element, or an organic metal containing an yttrium element. A compound may be used, but among them, a metal salt containing an yttrium element is preferable. Particularly in the present invention, the yttrium-containing metal source is preferably yttrium nitrate. The ratio of the zirconium-containing metal source and the yttrium-containing metal source contained in the metal oxide film forming solution is not particularly limited as long as a desired YSZ can be obtained. In this case, the yttrium-containing metal source is preferably in the range of 3 to 30, more preferably in the range of 5 to 20, in terms of mole.

  In the present invention, the metal source is preferably a combination of an indium-containing metal source containing an indium element and a tin-containing metal source containing a tin element. This is because an ITO film whose crystal state is changed stepwise or continuously can be obtained. The indium-containing metal source is not particularly limited as long as it contains an indium element. As described above, the indium-containing metal source may be a metal salt containing an indium element, and contains an indium element. An organic metal compound may be used, but among them, a metal salt containing an indium element is preferable. Particularly in the present invention, the indium-containing metal source is preferably indium chloride. On the other hand, the tin-containing metal source is not particularly limited as long as it contains a tin element, and as described above, it may be a metal salt containing a tin element, and contains a tin element. An organic metal compound may be used, but among them, a metal salt containing a tin element is preferable. In particular, in the present invention, the tin-containing metal source is preferably tin chloride.

  The concentration of the doping metal source in the metal oxide film forming solution is not particularly limited. For example, the concentration is within the range of 0.001 to 0.5 mol / l, particularly 0.01 to 0.1 mol / l. It is preferable to be within the range.

(2) Acid Next, the acid used in the present invention will be described. The acid used in the present invention changes the crystal state of the resulting metal oxide film.

The type of the acid is not particularly limited as long as the crystal state of the metal oxide film can be changed. For example, HF, HCl, HBr, HNO ₂ , HNO ₃ , H ₂ SO ₄ and H ₃ PO _{4 and the} like. Among them, HCl and HNO ₃ are preferable. In the present invention, two or more kinds of acids may be used in combination.

  The concentration of the acid contained in the metal oxide film forming solution is, for example, 0.001 mol / l or more, particularly 0.01 to 1 mol / l, particularly 0.05 to 0.5 mol / l. Preferably there is. When the concentration is less than the above range, the crystal state of the metal oxide film may not change. When the concentration exceeds the above range, it reacts with a metal source or the like to obtain a desired metal oxide film. Because there is no possibility.

  In the present invention, it is preferable to add an acid immediately before applying the metal oxide film forming solution. It is because the side reaction of a metal source and an acid can be suppressed.

(3) Solvent Next, the solvent used in the present invention will be described. The solvent used in the present invention is not particularly limited as long as it can dissolve the above-described metal source and the like, for example, water; total carbon such as methanol, ethanol, isopropyl alcohol, propanol, butanol and the like. Lower alcohols having 5 or less; toluene; diketones such as acetylacetone, diacetyl, benzoylacetone; ketoesters such as ethyl acetoacetate, ethyl pyruvate, ethyl benzoylacetate, ethyl benzoylformate; and mixed solvents thereof Can do. Depending on the compatibility with the raw material (metal source), for example, the film formation rate may be faster when only methanol is used, or the film formation rate may be higher when acetylacetone is mixed. For this reason, water, methanol, ethanol, acetone, toluene, acetylacetone or a mixed solvent thereof is more preferable. Moreover, it is preferable to use at least one of the above diketones and the above ketoesters as all or part of the solvent. This is because the film forming property is improved.

(4) Additive The metal oxide film forming solution used in the present invention may contain additives such as ceramic fine particles and a surfactant.

  By using the ceramic fine particles, a metal oxide film is formed so as to surround the ceramic fine particles, so that a mixed film of different ceramics can be obtained and the volume of the metal oxide film can be increased. In addition, it is preferable that the content of the ceramic fine particles is appropriately selected according to the characteristics of the member to be used.

  Examples of the ceramic fine particles include ITO, aluminum oxide, zirconium oxide, silicon oxide, titanium oxide, tin oxide, cerium oxide, calcium oxide, manganese oxide, magnesium oxide, and barium titanate. Etc.

  The surfactant acts on the interface between the metal oxide film forming solution and the substrate surface. By using the surfactant, the contact area between the metal oxide film forming solution and the substrate surface can be improved, and a uniform metal oxide film can be obtained. Particularly, when the metal oxide film forming solution is contacted by spraying, the droplets of the metal oxide film forming solution can be sufficiently brought into contact with the substrate surface due to the effect of the surfactant. Used for. In addition, it is preferable to select and use the usage-amount of the said surfactant suitably according to the metal source etc. to be used.

  Examples of the surfactant include Surfinol 485, Surfinol SE, Surfinol SE-F, Surfinol 504, Surfinol GA, Surfinol 104A, Surfinol 104BC, Surfinol 104PPM, Surfinol 104E, Surfinol. Examples include Surfinol series such as Nord 104PA (all manufactured by Nissin Chemical Industry Co., Ltd.), NIKKOL AM301, NIKKOL AM313ON (all manufactured by Nikko Chemical Co., Ltd.), and the like.

2. Next, the substrate used in the present invention will be described. The base material used in the present invention holds the metal oxide film. The material of the base material is not particularly limited as long as it has sufficient heat resistance, and examples thereof include glass, SUS, metal plate, ceramic base material, heat resistant plastic, and the like. It is preferable to use glass, SUS, a metal plate, or a ceramic substrate. It is because it is excellent in versatility.

  The base material used in the present invention is, for example, one having a smooth surface, one having a fine structure, one having a hole, one having a groove, one porous, one porous It may be provided with a film. Of these, those having a smooth surface, those having a fine structure, those having grooves, those which are porous, and those having a porous film are preferably used.

3. Method for Changing Acid Concentration Next, a method for bringing the metal oxide film forming solution into contact with the heated substrate while changing the acid concentration will be described. In the present invention, the method for changing the acid concentration is not particularly limited as long as a metal oxide film having a changed crystal state can be obtained. For example, as shown in FIG. A method using a plurality of metal oxide film forming solutions whose concentration is changed stepwise, and a method using a metal oxide film forming solution whose acid concentration is continuously changed as shown in FIG. Etc.

  By the method using a plurality of metal oxide film forming solutions in which the acid concentration is changed stepwise, a metal oxide film whose crystal state is changed stepwise can be obtained. Here, for a specific example of this method, a metal oxide film forming solution A containing only a metal source (abbreviated as solution A) and a metal oxide film forming solution B containing a metal source and an acid (solution) And a metal oxide film forming solution C (abbreviated as solution C) having a higher acid concentration than that of the solution B.

  For example, using the apparatus shown in FIG. 1, a method of spraying solution A first, then spraying solution B, and finally spraying solution C, and first spraying solution C and then solution B And a method of spraying the solution A at the end.

  On the other hand, a metal oxide film whose crystal state is continuously changed can be obtained by a method using the metal oxide film forming solution in which the acid concentration is changed stepwise. Here, some specific examples of this method will be illustrated using the above-described solution A and the acid D that changes the crystal state of the metal oxide film.

  For example, the apparatus shown in FIG. 2 is used to spray the solution A first, then gradually increase the flow rate of the acid D with respect to the solution A and spray the mixed solution of the solution A and the acid D first. Examples of the method include spraying and then spraying while gradually increasing or decreasing the flow rate of the acid D with respect to the solution A.

4). Next, a contact method between the substrate and the metal oxide film forming solution in the present invention will be described. The contact method is not particularly limited as long as it is a method in which the above-described base material and the above-described metal oxide film forming solution are brought into contact with each other, but the metal oxide film-forming solution and the base material are brought into contact with each other. It is preferable that the method does not lower the temperature of the substrate. This is because if the temperature of the substrate is lowered, the film formation reaction does not occur and a desired metal oxide film may not be obtained. As a method for preventing the temperature of the base material from being lowered, for example, a method of bringing the metal oxide film forming solution into contact with the base material as droplets, and the like are preferable. If the diameter of the droplet is small, the solvent of the metal oxide film forming solution is instantly evaporated, and the decrease in the substrate temperature can be further suppressed. Further, since the droplet diameter is small, a uniform film can be obtained. This is because a thick metal oxide film can be obtained.

  The method for bringing the droplet of the metal oxide film forming solution having such a small diameter into contact with the substrate is not particularly limited. Specifically, the metal oxide film forming solution is sprayed. The method of making it contact with a base material by this, the method of passing a base material in the space which made the metal oxide film formation solution mist-like, etc. are mentioned.

  Examples of the method of bringing the metal oxide film forming solution into contact with the substrate by spraying include a spraying method using a spray device or the like. In the case of spraying using the above spray device or the like, the diameter of the droplets is preferably within a range of 0.1 to 1000 μm, and more preferably within a range of 0.5 to 300 μm. This is because if the droplet diameter is within the above range, the substrate temperature can be prevented from decreasing, and a uniform metal oxide film can be obtained.

  The spray gas of the spray device is not particularly limited as long as it does not inhibit the formation of the metal oxide film, and examples thereof include air, nitrogen, argon, helium, oxygen and the like. Active gases such as nitrogen, argon and helium are preferred. In addition, the injection amount of the injection gas is, for example, preferably in the range of 0.1 to 50 l / min, and more preferably in the range of 1 to 20 l / min. The spray device may be a fixed device, a movable device, a device that ejects the solution by rotation, a device that ejects only the solution by pressure, or the like. As such a spray device, a commonly used spray device can be used, for example, hand spray (spray gun No. 8012, manufactured by ASONE), ultrasonic nepriser (NE-U17, manufactured by OMRON), etc. Can be used.

  Moreover, in the method of allowing the substrate to pass through the space in which the metal oxide film forming solution is made into a mist, the diameter of the droplets is usually within the range of 0.1 to 300 μm, particularly within the range of 1 to 100 μm. It is preferable that This is because if the droplet diameter is within the above range, the substrate temperature can be prevented from decreasing, and a uniform metal oxide film can be obtained.

  Further, the heating method of the substrate is not particularly limited, and examples thereof include a heating method such as a hot plate, an oven, a firing furnace, an infrared lamp, a hot air blower, etc. A method in which the metal oxide film forming solution can be contacted while maintaining the temperature is preferable, and specifically, a hot plate or the like is preferably used.

  Next, the contact method between the substrate and the metal oxide film forming solution in the present invention will be specifically described with reference to the drawings. Examples of the method of bringing the metal oxide film forming solution into contact with the substrate by spraying the above-described method include, for example, a method of continuously moving and spraying the substrate with a roller, a method of spraying on a fixed substrate, The method etc. which spray on the flow path like a pipe are mentioned.

  As a method of continuously moving and spraying the substrate with the roller, for example, as shown in FIG. 3, the solution A and the acid D described above are prepared, and the substrate 1 is made of metal using the rollers 3 to 5. It is continuously moved while being heated to a temperature equal to or higher than the oxide film formation temperature, and only the solution A is first sprayed using the spray device 2, and then the flow rate of the acid D to the solution A is gradually increased and sprayed. Thus, a method of forming a metal oxide film can be used. By this method, it is possible to obtain a metal oxide film whose crystal state has changed in a direction (moving direction of the base material) orthogonal to the stacking direction of the metal oxide film.

  Moreover, the method of spraying on the fixed base material, for example, as shown in FIG. 1 or FIG. 2, heats the base material 1 to a temperature equal to or higher than the metal oxide film formation temperature using a hot plate or the like, Examples thereof include a method of forming a metal oxide film by spraying the metal oxide film forming solution using the spray device 2. By this method, a metal oxide film whose crystal state is changed in the stacking direction of the metal oxide film can be obtained.

  In addition, as a method of passing the base material through the space in which the above-described solution for forming a metal oxide film is made into a mist, for example, as shown in FIG. A method of forming a metal oxide film by heating to a temperature equal to or higher than a material film forming temperature, passing the solution A through a mist-like space, and then passing the solution B through a mist-like space. Can be mentioned. By this method, a metal oxide film whose crystal state has changed in the stacking direction of the metal oxide film can be obtained.

5. In addition, in the method for producing a metal oxide film of the present invention, the metal oxide film obtained by the above-described contact method or the like may be washed. The cleaning of the metal oxide film is performed to remove impurities present on the surface of the metal oxide film, for example, a method of cleaning using a solvent used in the metal oxide film forming solution. Etc. In the present invention, ultraviolet irradiation may be performed during or after the production of the metal oxide film. By irradiating with ultraviolet rays, for example, the crystallinity of the metal oxide film can be improved.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be specifically described with reference to examples.

[Reference Example 1]
In this reference example, a metal oxide film-forming solution A containing zirconium tetraacetylacetonate and a metal oxide film-forming solution B containing zirconium tetraacetylacetonate and nitric acid were respectively used for zirconium oxide. Films were prepared, and the crystal states (crystallinity and crystal structure) of the obtained zirconium oxide films were compared.

  First, a mixed solvent of ethanol 50 wt% and toluene 50 wt% was prepared as a solvent. In this mixed solvent, zirconium tetraacetylacetonate (manufactured by Kanto Chemical Co., Inc.) was dissolved to a concentration of 0.1 mol / l to obtain 100 ml of a metal oxide film forming solution A. On the other hand, for the formation of a metal oxide film, zirconium tetraacetylacetonate is dissolved in the above mixed solvent at 0.1 mol / l and nitric acid (1 mol / l aqueous solution, manufactured by Kanto Chemical Co., Ltd.) at 0.005 mol / l. Solution B was obtained.

  Next, a silicon wafer was prepared as a base material. This substrate was heated to 500 ° C. with a hot plate (manufactured by ASONE), and 100 ml of the metal oxide film forming solutions A and B were sprayed on the substrate with an ultrasonic nebulizer (manufactured by OMRON). Two types of metal oxide films were obtained on the substrate.

  When the obtained two types of metal oxide films were measured using an X-ray diffractometer (Rigaku, RINT-1500), the crystal structure of the zirconium oxide film formed by the metal oxide film forming solution A was It was confirmed that the crystal structure was mainly tetragonal, and the crystal structure of the zirconium oxide film formed by the metal oxide film forming solution B was mainly tetragonal and monoclinic (FIG. 5). reference). As a result, it was confirmed that by adding nitric acid, the crystal structure of the obtained metal oxide film changes from tetragonal to tetragonal and monoclinic.

[Example 1-1]
<Preparation of zirconium oxide film whose crystal state changed stepwise in the stacking direction>
First, a silicon wafer was prepared as a base material. Next, metal oxide forming solutions A and B used in Reference Example 1 described above were prepared. Next, this base material (silicon wafer) is heated to 500 ° C. with a hot plate (manufactured by ASONE), and the metal oxide film forming solution A is applied to this base material with an ultrasonic nebulizer (manufactured by OMRON). The metal oxide film was obtained by spraying 100 ml and subsequently spraying 100 ml of the metal oxide film forming solution B in the same manner.

  When the obtained metal oxide film was observed using a transmission electron microscope (H-9000UHR, manufactured by Hitachi High-Tech Science Systems Co., Ltd.), it was confirmed that the crystal state was changed in two steps in the stacking direction.

[Example 1-2]
<Preparation of zirconium oxide film whose crystal state continuously changed in the stacking direction>
First, a silicon wafer was prepared as a base material. Next, the metal oxide forming solution A used in Reference Example 1 described above was prepared. Next, this base material (silicon wafer) is heated to 500 ° C. with a hot plate (manufactured by ASONE), and the metal oxide film forming solution A is applied to this base material with an ultrasonic nebulizer (manufactured by OMRON). When spraying 300 ml, 0.01 ml of 0.1 mol / l nitric acid was added every 10 seconds to obtain a metal oxide film on the substrate.

  When the obtained metal oxide film was observed using a transmission electron microscope (H-9000UHR, manufactured by Hitachi High-Tech Science Systems Co., Ltd.), the crystal state continuously changed from the base material (there was no boundary). Was confirmed.

[Reference Example 2]
In this reference example, a metal oxide film-forming solution A containing zirconium tetraacetylacetonate and a metal oxide film-forming solution B containing zirconium tetraacetylacetonate and hydrochloric acid were respectively used for zirconium oxide. Films were prepared, and the crystal states (crystallinity and crystal structure) of the obtained zirconium oxide films were compared.

  First, a mixed solvent of ethanol 50 wt% and toluene 50 wt% was prepared as a solvent. In this mixed solvent, zirconium tetraacetylacetonate (manufactured by Kanto Chemical Co., Inc.) was dissolved to a concentration of 0.1 mol / l to obtain 100 ml of a metal oxide film forming solution A. On the other hand, in the above mixed solvent, zirconium tetraacetylacetonate is dissolved at 0.1 mol / l and hydrochloric acid (1 mol / l aqueous solution, manufactured by Kanto Chemical Co., Ltd.) is dissolved at 0.005 mol / l to form a metal oxide film. Solution B was obtained.

  Next, a silicon wafer was prepared as a base material. This substrate was heated to 500 ° C. with a hot plate (manufactured by ASONE), and 100 ml of the metal oxide film forming solutions A and B were sprayed on the substrate with an ultrasonic nebulizer (manufactured by OMRON). Two types of metal oxide films were obtained on the substrate.

  When the obtained two types of metal oxide films were measured using an X-ray diffractometer (Rigaku, RINT-1500), the crystal structure of the zirconium oxide film formed by the metal oxide film forming solution A was It was confirmed that the crystal structure was mainly tetragonal, and the crystal structure of the zirconium oxide film formed by the metal oxide film forming solution B was mainly tetragonal and monoclinic (FIG. 6). reference). As a result, it was confirmed that by adding hydrochloric acid, the crystal structure of the resulting metal oxide film changes from tetragonal to tetragonal and monoclinic.

[Example 2-1]
<Preparation of zirconium oxide film whose crystal state changed stepwise in the stacking direction>
A metal oxide film was obtained in the same manner as in Example 1-1 except that the metal oxide film forming solutions A and B used in Reference Example 2 were used. When the obtained metal oxide film was observed using a transmission electron microscope (H-9000UHR, manufactured by Hitachi High-Tech Science Systems Co., Ltd.), it was confirmed that the crystal state was changed in two steps in the stacking direction.

[Example 2-2]
<Preparation of zirconium oxide film whose crystal state continuously changed in the stacking direction>
A metal oxide film was obtained in the same manner as in Example 1-2 except that the metal oxide film forming solutions A and B used in Reference Example 2 were used. When the obtained metal oxide film was observed using a transmission electron microscope (H-9000UHR, manufactured by Hitachi High-Tech Science Systems Co., Ltd.), the crystal state continuously changed from the base material (there was no boundary). Was confirmed.

[Reference Example 3]
In this reference example, a metal oxide film forming solution A containing zirconium tetraacetylacetonate and yttrium nitrate and a metal oxide film forming solution B containing zirconium tetraacetylacetonate, yttrium nitrate and hydrochloric acid were used. The YSZ films were respectively prepared, and the crystal states (crystallinity and crystal structure) of the obtained YSZ films were compared.

  First, ethanol was prepared as a solvent. In this solvent, zirconium tetraacetylacetonate (manufactured by Kanto Chemical Co., Inc.) is dissolved at 0.1 mol / l and yttrium nitrate (manufactured by Kanto Chemical Co., Ltd.) is dissolved at 0.02 mol / l to form a 100 ml metal oxide film. Solution A was obtained. On the other hand, zirconium tetraacetylacetonate is dissolved in the above solvent to 0.1 mol / l, yttrium nitrate is 0.02 mol / l, and nitric acid (1 mol / l aqueous solution, manufactured by Kanto Chemical Co., Ltd.) is dissolved to 0.005 mol / l. Thus, a metal oxide film forming solution B was obtained.

  Next, a silicon wafer was prepared as a base material. This substrate was heated to 500 ° C. with a hot plate (manufactured by ASONE), and 100 ml of the metal oxide film forming solutions A and B were sprayed on the substrate with an ultrasonic nebulizer (manufactured by OMRON). Two types of metal oxide films were obtained on the substrate.

  When the obtained two types of metal oxide films were observed using SEM (manufactured by Hitachi, S-4500), the metal oxide film formed with the metal oxide film forming solution A had a thickness of 480 nm. The metal oxide film formed with the metal oxide film forming solution B had a thickness of 520 nm. Moreover, when the obtained two types of metal oxide films were measured using an X-ray diffractometer (Rigaku, RINT-1500), the YSZ film formed from the metal oxide film forming solution A was more It was confirmed that the YSZ film formed by the metal oxide film forming solution B has higher crystallinity (see FIG. 7). From the results, it was confirmed that the crystallinity of the obtained metal oxide film was improved by adding hydrochloric acid.

[Example 3-1]
<Preparation of YSZ film whose crystal state changed stepwise in the stacking direction>
A metal oxide film was obtained in the same manner as in Example 1-1 except that the metal oxide film forming solutions A and B used in Reference Example 3 were used. When the obtained metal oxide film was observed using a transmission electron microscope (H-9000UHR, manufactured by Hitachi High-Tech Science Systems Co., Ltd.), it was confirmed that the crystal state was changed in two steps in the stacking direction.

[Example 3-2]
<Preparation of YSZ film whose crystal state continuously changed in the stacking direction>
A metal oxide film was obtained in the same manner as in Example 1-2 except that the metal oxide film forming solutions A and B used in Reference Example 3 were used. When the obtained metal oxide film was observed using a transmission electron microscope (H-9000UHR, manufactured by Hitachi High-Tech Science Systems Co., Ltd.), the crystal state continuously changed from the base material (there was no boundary). Was confirmed.

[Reference Example 4]
In this reference example, an ITO film was formed using a metal oxide film forming solution A containing indium chloride and tin chloride and a metal oxide film forming solution B containing indium chloride, tin chloride and nitric acid, respectively. And the crystal states (crystallinity and crystal structure) of the obtained ITO films were compared.

  First, a mixed solvent of 50 wt% methanol and 50 wt% ethyl acetoacetate was prepared as a solvent. In this mixed solvent, indium (III) chloride tetrahydrate (manufactured by Kanto Chemical Co., Inc.) is 0.1 mol / l, and tin (II) chloride dihydrate (manufactured by Kanto Chemical Co., Ltd.) is 0.005 mol / l. Thus, 100 ml of a metal oxide film forming solution A was obtained. On the other hand, in the mixed solvent, indium chloride (III) tetrahydrate 0.1 mol / l, tin chloride (II) dihydrate 0.005 mol / l, nitric acid (1 mol / l aqueous solution, manufactured by Kanto Chemical Co., Inc.) ) Was dissolved to 0.01 mol / l to obtain a metal oxide film forming solution B.

  Next, a slide glass was prepared as a base material. This substrate was heated to 500 ° C. with a hot plate (manufactured by ASONE), and 100 ml of the metal oxide film forming solutions A and B were sprayed on the substrate with an ultrasonic nebulizer (manufactured by OMRON). Two types of metal oxide films were obtained on the substrate.

  Moreover, when two types of obtained metal oxide films were measured using the X-ray-diffraction apparatus (the Rigaku make, RINT-1500), the crystal structure of the ITO film | membrane formed with the solution A for metal oxide film formation Were confirmed to be mainly cubic crystals, and the crystal structure of the ITO film formed by the metal oxide film forming solution B was confirmed to be mainly hexagonal crystals and cubic crystals (see FIG. 8). ). From the results, it was confirmed that by adding nitric acid, the crystal structure of the obtained metal oxide film was changed from cubic to hexagonal and cubic.

[Example 4-1]
<Preparation of ITO film whose crystal state changed stepwise in the stacking direction>
A metal oxide film was obtained in the same manner as in Example 1-1 except that the metal oxide film forming solutions A and B used in Reference Example 4 were used. When the obtained metal oxide film was observed using a transmission electron microscope (H-9000UHR, manufactured by Hitachi High-Tech Science Systems Co., Ltd.), it was confirmed that the crystal state was changed in two steps in the stacking direction.

[Example 4-2]
<Preparation of ITO film whose crystal state continuously changed in the stacking direction>
A metal oxide film was obtained in the same manner as in Example 1-2 except that the metal oxide film forming solutions A and B used in Reference Example 4 were used. When the obtained metal oxide film was observed using a transmission electron microscope (H-9000UHR, manufactured by Hitachi High-Tech Science Systems Co., Ltd.), the crystal state continuously changed from the base material (no boundary). Was confirmed.

[Reference Example 5]
In this reference example, two types of metal oxide films (ITO films) were obtained in the same manner as in Reference Example 4 except that a porous titanium oxide base material was used instead of the slide glass as the base material. .
When the obtained two types of metal oxide films were observed using an SEM (manufactured by Hitachi, S-4500), the metal oxide film formed by the metal oxide film forming solution A had columnar crystals. As a result, the grain boundary was clearly confirmed at the interface, and the metal oxide film formed by the metal oxide film forming solution B was confirmed to have no grain boundary at the interface (see FIG. 9). From the results, it was confirmed that the crystal state of the metal oxide film was changed by adding nitric acid.

It is explanatory drawing which shows an example of the manufacturing method of the metal oxide film of this invention. It is explanatory drawing which shows the other example of the manufacturing method of the metal oxide film of this invention. It is explanatory drawing which shows the other example of the manufacturing method of the metal oxide film of this invention. It is explanatory drawing which shows the other example of the manufacturing method of the metal oxide film of this invention. 6 is a graph showing the results of X-ray diffraction measurement of Reference Example 1. 6 is a graph showing the results of X-ray diffraction measurement of Reference Example 2. 10 is a graph showing the results of X-ray diffraction measurement of Reference Example 3. 10 is a graph showing the results of X-ray diffraction measurement of Reference Example 4. 10 is a SEM photograph of the metal oxide film of Reference Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Spray apparatus 3, 4, 5 ... Roller

Claims (4)

A solution for forming a metal oxide film in which a metal salt or an organometallic compound is dissolved as a metal source and the concentration of the acid for changing the crystal state of the metal oxide film is different. In a method for producing a metal oxide film, a metal oxide film having a crystalline state changed stepwise or continuously on a base material by contacting the base material heated to a temperature equal to or higher than a physical film formation temperature. There,
The method of bringing the metal oxide film forming solution into contact with the base material is a method of bringing the metal oxide film forming solution into contact with the base material by spraying the metal oxide film forming solution, or the metal oxide film forming solution. A method for producing a metal oxide film, characterized in that the substrate is passed through a mist-like space . The method for producing a metal oxide film according to claim 1, wherein the acid is HF, HCl, HBr, HNO ₂ , HNO ₃ , H ₂ SO _4, or H ₃ PO ₄ .   The method for producing a metal oxide film according to claim 1, wherein the metal oxide film forming solution further contains a doping metal source.   Metal elements constituting the metal source are Mg, Al, Si, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ag, In, Sn, Ce, Sm, Pb, La, The claim according to any one of claims 1 to 3, wherein Hf, Sc, Gd, Ca, Cr, Ga, Sr, Nb, Mo, Pd, Sb, Te, Ba, W or Ta. The manufacturing method of the metal oxide film as described in 2.

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