Coating solution for film formation, metal oxide film, planarization film, and method for forming metal oxide films by chemical vapor deposition.

Abstract

To provide a coating liquid for film formation that can form a metal oxide film with excellent flatness even on uneven surfaces and reliable heat resistance by chemical vapor deposition. [Solution] A coating solution for forming metal oxide films by chemical vapor deposition, wherein the coating solution is a one-component coating solution containing a β-diketone complex, an inorganic metal salt, and a solvent, or a multi-component coating solution comprising coating solution A containing a β-diketone complex and a solvent, and coating solution B containing an inorganic metal salt and a solvent, wherein the β-diketone complex and the inorganic metal salt are composed of metal atoms of period 3 to 6 and group 2 to 14.

Description

Technical Field

[0006] ,

[0001] The present invention relates to a coating liquid for film formation, a metal oxide film, a planarization film, and a method for forming a metal oxide film by chemical vapor deposition.

Background Art

[0002] The planarization film is used for electronic components such as liquid crystal panels, image sensors, and semiconductor chips for the purpose of improving optical uniformity and electrode printability, and those made of resin or metal oxide are known.

[0003] Regarding the planarization film made of metal oxide, film formation by sputtering or plasma CVD method in semiconductor chip manufacturing is known. However, in these film formation methods, since the material is irradiated from one direction to form a film uniformly, the planarization rate is low, and there is also a problem that film formation does not occur on the side surfaces of the uneven portions.

[0004] As other film formation methods, thermal CVD method and mist CVD method, which are chemical vapor deposition methods, are known. These film formation methods have the advantage that film formation is possible on the side surfaces of the uneven portions because film formation proceeds in the gas phase. However, as described in Patent Document 1, it is also known that uniform film formation on the uneven portions is difficult in the thermal CVD method and the mist CVD method, and it has been difficult to increase the planarization rate.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In view of the above problems, the present invention aims to provide a coating liquid for film formation that can form a metal oxide film with excellent flatness even on uneven surfaces and reliable heat resistance by chemical vapor deposition.

[0008] Furthermore, the present invention aims to provide the above-mentioned film-forming coating liquid, a metal oxide film, a planarization film, and a method for forming a metal oxide film by chemical vapor deposition. [Means for solving the problem]

[0009] The present invention relates to a film-forming coating solution used for forming metal oxide films by chemical vapor deposition, wherein the film-forming coating solution is a one-component film-forming coating solution containing a β-diketone complex, an inorganic metal salt, and a solvent, or a multi-component film-forming coating solution comprising a film-forming coating solution A containing a β-diketone complex and a solvent, and a film-forming coating solution B containing an inorganic metal salt and a solvent, wherein the β-diketone complex and the inorganic metal salt are composed of metal atoms of period 3 to 6 and group 2 to 14.

[0010] Furthermore, the present invention relates to the film-forming coating liquid described in [1] above, in which, in the one-component film-forming coating liquid, the molar ratio of the metal atoms of the β-diketone complex to the metal atoms of the inorganic metal salt is preferably 0.01 to 20.

[0011] Furthermore, the present invention relates to the film-forming coating liquid described in [1] or [2] above, which is used for planarizing a substrate.

[0012] Furthermore, the present invention relates to a metal oxide film formed from a film-forming coating liquid described in any of [1] to [3] above, and having a thickness of 30 μm or less.

[0013] Furthermore, the present invention relates to [5] a planarization film made of the metal oxide film described in [4] above.

[0014] Furthermore, the present invention relates to a method for forming a metal oxide film by chemical vapor deposition, comprising: [6] a misting step of atomizing the one-component film-forming coating solution described in any of [1] to [3] above; and a step of supplying the obtained mist to a heated substrate surface and allowing it to react on the substrate.

[0015] Furthermore, the present invention relates to a method for forming a metal oxide film by chemical vapor deposition, comprising: [7] a two-tank misting step of separately misting the film-forming coating liquid A and the film-forming coating liquid B in any of [1] to [3] above; and a step of supplying each mist to a heated substrate surface and allowing it to react on the substrate.

[0016] Furthermore, the present invention relates to a method for forming a metal oxide film by chemical vapor deposition as described in [7] above, wherein mist of the film-forming coating liquid A and the film-forming coating liquid B is supplied to the heated substrate surface such that the molar ratio of the metal atoms of the β-diketone complex to the metal atoms of the inorganic metal salt contained in each is 0.01 to 20. [Effects of the Invention]

[0017] The coating solution for film formation of the present invention is presumed to have the effect of counteracting the ability to follow the uneven surface of the substrate, which is a factor in the reduction of flatness when forming a metal oxide film by chemical vapor deposition. Therefore, the metal oxide film formed from this coating solution exhibits excellent flatness even on uneven surfaces and has reliable heat resistance. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram of a metal oxide film deposition apparatus in a method for manufacturing a metal oxide film according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of a metal oxide film deposition apparatus in a method for manufacturing a metal oxide film according to one embodiment of the present invention. [Figure 3] Schematic diagram of an atomizer in a film forming apparatus for a metal oxide film in a method for producing a metal oxide film according to an embodiment of the present invention. [Figure 4] Schematic diagram of a mixing tank in a film forming apparatus for a metal oxide film in a method for producing a metal oxide film according to an embodiment of the present invention. [Figure 5] Schematic diagram of a film forming section in a film forming apparatus for a metal oxide film in a method for producing a metal oxide film according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0019] Hereinafter, a coating liquid for film formation, a metal oxide film, a planarizing film, and a method for forming a metal oxide film by chemical vapor deposition according to an embodiment of the present invention will be described with reference to the drawings as necessary.

[0020] <Coating Liquid for Film Formation> The coating liquid for film formation of the present invention is a one-component type coating liquid for film formation containing a β-diketone complex, an inorganic metal salt, and a solvent, or a multi-component type coating liquid for film formation having a coating liquid A for film formation containing a β-diketone complex and a solvent and a coating liquid B for film formation containing an inorganic metal salt and a solvent, which is used for forming a metal oxide film by chemical vapor deposition.

[0021] <β-Diketone Complex> It is considered that the multimer formed by reacting the β-diketone complex with the inorganic metal salt in the liquid phase or the gas phase contributes to the planarization of the substrate. In the liquid, the inorganic metal salt acts as a Lewis acid, and due to the hydrolysis of the β-diketone complex, the ligand β-diketone is replaced by a hydroxy group. As a result, the formation of metal-oxygen-metal bonds is promoted, and it is considered that a multimer is formed. Monomers tend to be more reactive than multimers and are deposited on the uneven surface of the substrate by reacting in the gas phase to form a film that follows the uneven surface. On the other hand, some multimers cannot react completely in the gas phase and are deposited in the concave portions of the substrate, and the concave portions are preferentially formed into a film by reacting on the substrate, which is considered to improve the flatness.

[0022] β-diketone complexes are composed of metal atoms from periods 3-6 and groups 2-14. From the viewpoint of ease of polymer formation, it is preferable that the melting points of the metal atoms (elements) constituting the β-diketone complex are 100°C or higher. Examples of the above metals include Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Cd, In, Ba, Hf, Ir, Pb, and Sn. From the same viewpoint, it is more preferable that the melting points of the metal atoms constituting the β-diketone complex are 500°C or higher. Examples of metals with a melting point of 500°C or higher include Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Ba, Hf, and Ir. A lower melting point of a metal atom tends to result in fewer electrons involved in bonding and a weaker bonding force, so a higher metal melting point is considered preferable from the viewpoint of polymer formation. The melting point of a metal can be determined by the capillary method, which is a commonly used method for measuring melting points. Here, the values ​​of the melting points of metals defined in this specification are those listed in "New Series of Chemistry: Basic Inorganic Chemistry" by Masami Ichikuni (1998).

[0023] <Inorganic metal salts> Inorganic metal salts are composed of metal atoms from periods 3 to 6 and groups 2 to 14. From the viewpoint of ease of polymer formation, it is preferable that the electronegativity of the metal atoms constituting the inorganic metal salt is 1.95 or less. Examples of the above metals include Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Cd, In, Ba, Hf, Pb, Ga, etc. From the same viewpoint, it is more preferable that the electronegativity of the metal atoms constituting the inorganic metal salt is 1.80 or less. Examples of metals with an electronegativity of 1.80 or less include Mg, Al, Sc, Ti, V, Cr, Mn, Zn, Sr, Y, Zr, Cd, In, Ba, Hf, etc. When an inorganic metal salt ionizes and exists as a metal cation in the liquid or gas phase, the metal cation coordinates with a β-diketone partially liberated from the β-diketone complex to form a complex. However, if the electronegativity of the metal is high, the formed complex is stabilized, and problems such as the formation of new polymers are inhibited may occur. Therefore, it is considered preferable for the metal constituting the inorganic metal salt to have low electronegativity. Hereinafter, in this specification, "electronegativity" refers to the electronegativity proposed in Emsley John's "The Elements" (1998), and its specific numerical value is defined as the electronegativity value described in the aforementioned book.

[0024] Furthermore, examples of anions that constitute the inorganic metal salt include fluoride ions, chloride ions, bromide ions, iodide ions, nitrate ions, sulfate ions, and phosphate ions. Among these, nitrate ions, sulfate ions, and phosphate ions, which are oxoacid ions, are preferred because if an oxygen atom is contained in the structure, it also acts as an oxygen source and enhances the effect of promoting the reaction.

[0025] In the coating solution for film formation, the total concentration of the β-diketone complex and the inorganic metal salt (also called the "metal source" concentration) is preferably 30% by weight or less from the viewpoint of ease of atomization, and more preferably 0.1% by weight or more from the viewpoint of film formation rate. Furthermore, from the viewpoint of planarization, it is more preferably 1% by weight or more. In addition, the molar ratio of the metal atoms of the β-diketone complex to the metal atoms of the inorganic metal salt is preferably 0.005 to 30, and more preferably 0.01 to 20, from the viewpoint of promoting polymer formation which is involved in the step reduction rate.

[0026] When the coating solution is a one-component coating solution, it is suitable for a chemical vapor deposition (CVD) method in which a metal oxide film is formed by supplying a mist obtained by atomizing the coating solution. Furthermore, when the coating solution is a multi-component coating solution, it is suitable for a chemical vapor deposition (CVD) method in which a metal oxide film is formed by atomizing coating solution A and coating solution B separately and supplying the respective mists. In this invention, atomization includes processes such as detonation and droplet formation, and refers to the process of atomizing a liquid into fine particles and dispersing them in a gas.

[0027] <Solvent> Any solvent that can dissolve the β-diketone complex and / or inorganic metal salt may be used. However, from the viewpoint of mist generation efficiency, a solvent with a boiling point of 40°C to 150°C and a viscosity of 1.3 mPa·sec or less at 25°C is preferred, a solvent with a viscosity of 0.1 mPa·sec to 1.0 mPa·sec is more preferred, and a solvent with a viscosity of 0.5 mPa·sec to 1.0 mPa·sec is even more preferred. Examples of solvents include polar solvents such as lower alcohols like methanol, nitrile solvents such as acetonitrile, and water, as well as nonpolar solvents such as aromatic solvents like toluene. Two or more of these solvents may be used in mixture form. Among these solvents, polar solvents are preferred, and lower alcohols and water are more preferred in that they act as oxygen sources, allowing the effects of the present invention to be fully obtained. Furthermore, it is preferable to include water in order to make it easier to handle and to prevent ignition of the misted coating solution. Here, the oxygen source is a source of oxygen atoms for converting the β-diketone complex and / or inorganic metal salt into a metal oxide.

[0028] <Metal oxide film> The metal oxide film of the present invention is formed from a coating solution for film formation and has a thickness of 30 μm or less. From the viewpoint of flatness, the metal oxide film is preferably 0.2 μm or more in thickness, and from the viewpoint of cost, it is preferably 20 μm or less in thickness.

[0029] <Planarization film> The planarization film of the present invention is made of a metal oxide film. Preferably, the planarization film is a laminate in which the planarization film is directly laminated on a sheet-like substrate having a thickness of 0.2 mm to 20 mm, or on a substrate processed into a certain shape using a mold. The above "direct lamination" means that there is no layer of 100 nm or more between the planarization film and the substrate. If the substrate has an uneven shape, preferably the maximum height (Sz) of the substrate surface in the uneven portion is 30 μm or less.

[0030] Examples of base material materials include metallic materials such as copper or copper alloys, aluminum or aluminum alloys, zinc, and silicon, as well as inorganic solid materials such as oxides, carbides, nitrides, and borides.

[0031] <Method for forming metal oxide films by chemical vapor deposition> Any method for depositing the metal oxide film is acceptable, and mist CVD is preferred from the viewpoint of excellent deposition rate and uniformity of the film.

[0032] Examples of mist CVD include a method for forming metal oxide films by chemical vapor deposition, comprising a misting step of atomizing a one-component film-forming coating solution and a step of supplying the obtained mist to a heated substrate surface and allowing it to react on the substrate; and a method for forming metal oxide films by chemical vapor deposition, comprising a multi-tank misting step of atomizing two separate multi-component film-forming coating solutions, A and B, and a step of supplying each mist to a heated substrate surface and allowing it to react on the substrate.

[0033] Figure 1 shows a schematic diagram of a film deposition apparatus (1) in a method for depositing metal oxide films, which includes a misting step for atomizing a one-component film-forming coating solution. The film deposition apparatus (1) consists of a single misting unit and a film deposition machine (film deposition section) connected by piping.

[0034] Figure 2 shows a schematic diagram of a film deposition apparatus (2) in a method for depositing metal oxide films, which has a multi-tank misting process in which a multi-liquid type film deposition coating solution having film deposition coating solution A and film deposition coating solution B is separately atomized. The film deposition apparatus (2) consists of multiple misters, mixing tanks, and film deposition machines (film deposition sections) connected by piping.

[0035] Figure 3 shows a schematic diagram of a misting apparatus in a metal oxide film deposition system. The misting apparatus consists of a container for the raw material and an ultrasonic generator equipped with an ultrasonic transducer. The container is a glass cylinder with a Teflon® lid and a bottom made of polyethylene or a film of tetrafluoroethylene-hexafluoropropylene copolymer. Two glass pipes are provided to pass through the lid. The first pipe is provided to send a carrier gas (nitrogen) for transporting the mist into the container, and the second pipe is provided to send the mist generated in the container and the carrier gas to the film deposition machine. The container is placed in the ultrasonic generator along with water, and ultrasonic waves generated by the ultrasonic transducer are transmitted to the raw material via the water and the film of polyethylene or the like, causing the raw material to be atomized.

[0036] Figure 4 shows a schematic diagram of a mixing tank in a metal oxide film deposition apparatus. The mixing tank is a glass container with a Teflon® lid. Three glass pipes are provided to pass through the lid. Of the four pipes, three are connected to three atomizers by piping, and one central pipe is connected to the film deposition section by piping. The mist generated in the atomizers is transported to the film deposition section via the mixing tank. This mixing tank is mainly used to mix the mist generated in separate atomizers.

[0037] Figure 5 shows a schematic diagram of the film deposition section in a metal oxide film deposition apparatus. The film deposition section consists of a metal jig and a hot plate connected to a misting unit or mixing tank. The jig is connected to the misting unit or mixing tank by a silicone tube and is provided to heat the mist and the substrate. As the heated mist passes over the substrate, a chemical reaction occurs on the substrate to form a silica-containing alumina film. In Figure 5, if a jig with a large internal space is used, film deposition is possible not only on plate-shaped substrates but also on three-dimensional substrates. The hot plate is provided to heat the jig.

[0038] In the mist CVD described above, oxidizing agents such as ozone, oxygen, and hydrogen peroxide may be used as the oxygen source, but ozone is more preferred. Furthermore, to prevent ignition of the atomized coating solution, water, alcohol, etc., may be used as the oxygen source. Here, the oxygen source is a source of oxygen atoms necessary to convert the aluminum complex or salt and silicon compound into metal oxides.

[0039] As the carrier gas, an inert gas containing no more than 10,000 ppm (by volume) of oxygen is preferred in order to suppress oxidation of the substrate surface.

[0040] In mist CVD, it is preferable to form a metal oxide film by heating and reacting a mist of raw materials on a substrate in a temperature atmosphere of 200°C to 500°C, and it is even more preferable to form the film at 300°C to 450°C. [Examples]

[0041] The present invention will be described in more detail below with reference to examples and comparative examples.

[0042] <Examples 1-11, 14> <Preparation of coating solution for film formation> Examples 1-11 and 14 were single-tank systems, and a one-component film-forming coating solution was prepared using the raw materials and proportions listed in Tables 1-2.

[0043] <Formation of metal oxide film on substrate> A metal oxide film was formed on a substrate using the film deposition apparatus (mist CVD apparatus) shown in Figures 1, 3, and 5, by the following method. A polyethylene or tetrafluoroethylene-hexafluoroethylene copolymer film was fixed to the bottom of a glass cylinder (13 cm in diameter, 15 cm in height) with an O-ring and sealant at a position 1 cm from the bottom. The top of the cylinder was fitted with a Teflon® lid, and two holes were made in the lid to insert glass pipes for nitrogen gas supply and mist transport. The glass tube for mist transport with a branch pipe was placed 1-2 cm away from the metal material on the hot plate, and the branch pipe was connected to an ozone generator with a Teflon® tube to allow introduction of ozone-oxygen gas. The cylinder was immersed in a water bath, and an ultrasonic transducer (ultrasonic atomization unit HMC-2401; manufactured by Honda Electronics Co., Ltd.) was placed directly below the polyethylene or tetrafluoroethylene-hexafluoropropylene. The hot plate was placed inside a box filled with nitrogen, and film deposition was started only after the oxygen concentration had dropped to 1% or less. The above-mentioned one-component film-forming coating solution was placed in a cylinder, and an ultrasonic transducer was activated. Ultrasound was transmitted to the one-component film-forming coating solution via water in a tank and polyethylene or tetrafluoroethylene-hexafluoropropylene copolymer, causing a portion of the one-component film-forming coating solution to be atomized. The atomized one-component film-forming coating solution was transported onto the substrate (30 mm x 30 mm) using nitrogen gas. The substrate was heated to 360°C by the hot plate, and it was confirmed that the atomized one-component film-forming coating solution had reached the substrate. A chemical reaction was then carried out to form a metal oxide film, and a laminate was obtained. The thickness of the metal oxide film was adjusted by the film deposition time (the time the atomized one-component film-forming coating solution was sprayed onto the substrate) and measured by the following method. The nitrogen gas flow rate was set to 11 L / min, the ozone concentration in the ozone-oxygen gas to 5000 ppm, the ozone-oxygen gas flow rate to 1 L / min, the ultrasonic transducer frequency to 2.4 MHz, the voltage to 24 V, and the current to 0.6 A.

[0044] <Example 12> <Preparation of coating solution for film formation> Example 12 was a two-tank system in which film-forming coating solution A, containing a β-diketone complex and a solvent, and film-forming coating solution B, containing an inorganic metal salt and a solvent, were prepared using the raw materials and proportions listed in Table 2.

[0045] <Formation of metal oxide film on substrate> A metal oxide film was formed on a substrate using the film deposition apparatus (mist CVD apparatus) shown in Figures 2, 3-5, by the following method. A film made of polyethylene or tetrafluoroethylene / hexafluoroethylene copolymer was fixed to a glass cylinder (13 cm in diameter, 15 cm in height) 1 cm from the bottom using an O-ring and sealant. The top of the cylinder was fitted with a Teflon® lid, and two holes were drilled in the lid to insert glass pipes for nitrogen gas supply and mist transport. The cylinder was immersed in a water bath, and an ultrasonic transducer (ultrasonic atomization unit HMC-2401; manufactured by Honda Electronics Co., Ltd.) was placed directly below the polyethylene or tetrafluoroethylene / hexafluoropropylene film. The hot plate was placed inside a box filled with nitrogen, and film deposition was started after the oxygen concentration fell to 1% or less. The above-mentioned film-forming coating liquids A and B were placed separately in two cylinders, and an ultrasonic transducer was activated. Ultrasound was transmitted to film-forming coating liquids A and B via water in a tank and polyethylene or tetrafluoroethylene-hexafluoropropylene copolymer, causing a portion of the liquid to be atomized. The atomized film-forming coating liquids A and B were transported onto a substrate (30 mm x 30 mm) using nitrogen gas. The substrate was heated to 360°C on a hot plate. After confirming that the atomized film-forming coating liquids A and B had reached the substrate, a chemical reaction was initiated to form a metal oxide film, and a laminate was obtained. The thickness of the metal oxide film was adjusted by the film formation time (the time the atomized film-forming coating liquids A and B were sprayed onto the substrate) and measured by the following method. The nitrogen gas flow rate was set to 11 L / min, the ultrasonic transducer frequency to 2.4 MHz, the voltage to 24 V, and the current to 0.6 A.

[0046] <Example 13> <Preparation of coating solution for film formation> Example 13 was a three-tank system in which a film-forming coating solution A containing a β-diketone complex and a solvent, a film-forming coating solution B containing an inorganic metal salt and a solvent, and an oxygen source solution were prepared using the raw materials and proportions listed in Table 2.

[0047] <Formation of metal oxide film on substrate> A metal oxide film was formed on a substrate using the film deposition apparatus (mist CVD apparatus) shown in Figures 2, 3-5, by the following method. A film made of polyethylene or tetrafluoroethylene / hexafluoroethylene copolymer was fixed to a glass cylinder (13 cm in diameter, 15 cm in height) 1 cm from the bottom using an O-ring and sealant. The top of the cylinder was fitted with a Teflon® lid, and two holes were drilled in the lid to insert glass pipes for nitrogen gas supply and mist transport. The cylinder was immersed in a water bath, and an ultrasonic transducer (ultrasonic atomization unit HMC-2401; manufactured by Honda Electronics Co., Ltd.) was placed directly below the polyethylene or tetrafluoroethylene / hexafluoropropylene film. The hot plate was placed inside a box filled with nitrogen, and film deposition was started after the oxygen concentration fell to 1% or less. The above-mentioned film-forming coating solution A, film-forming coating solution B, and oxygen source solution were placed separately in three cylinders, and an ultrasonic transducer was activated. Ultrasound was transmitted to film-forming coating solution A, film-forming coating solution B, and oxygen source solution via water in a tank and polyethylene or tetrafluoroethylene-hexafluoropropylene copolymer, causing a portion of the liquid to be atomized. The atomized film-forming coating solution was transported onto the substrate (30 mm x 30 mm) using nitrogen gas. The substrate was heated to 360°C on a hot plate, and it was confirmed that the atomized film-forming coating solution A, film-forming coating solution B, and oxygen source solution had reached the substrate. A chemical reaction was then carried out to form a metal oxide film, and a laminate was obtained. The thickness of the metal oxide film was adjusted by the film formation time (the time the atomized film-forming coating solution A, film-forming coating solution B, and oxygen source solution were sprayed onto the substrate) and measured by the following method. The nitrogen gas flow rate was set to 11 L / min, the ultrasonic transducer frequency to 2.4 MHz, the voltage to 24 V, and the current to 0.6 A.

[0048] <Comparative Example 1> <Preparation of coating solution for film formation> A coating solution for film formation was prepared using the raw materials and proportions listed in Table 3.

[0049] <Formation of metal oxide film on substrate> Metal oxide films were formed using the same method as in Examples 1-11 and 14.

[0050] <Measuring film thickness> For the measurement of film thickness, a metal oxide film was formed on a 3cm square silicon wafer in Examples 1-13 and Comparative Example 1, and on a 3cm square alumina substrate in Example 14. The film thickness was then measured using a surface shape analyzer (DektakXT-S: manufactured by Bruker Japan Co., Ltd.). The difference between a spot 3.5mm from the edge of the resulting laminate and the substrate was measured, and the average of the total of 10 spots at both ends was measured as the film thickness.

[0051] <Film formation speed> The film deposition rate was determined from the film thickness measured using the film thickness measurement method and the deposition time, as the film thickness (nm) that can be deposited per minute.

[0052] <Measurement of the composition of metal oxide films> The weight per unit volume and their ratios of metal atoms, oxygen atoms, and carbon atoms were calculated using Dynamic SIMS (PHI ADEPT: Ulvac·PHI). The Dynamic SIMS conditions were as follows: Primary ion species: Cs+, Primary acceleration voltage: 5.0kV, Detection area: 45×45μm. As a sample, a silicon wafer was used as the substrate, and a 1μm metal oxide film was formed on it. Measurements were taken in the depth direction from the center of the sample, and the depth of the point where silicon was detected was defined as 1μm. The weight ratios of atoms were calculated from the secondary ion intensity, relative sensitivity coefficient, and atomic weight of each of the metal atoms, oxygen atoms, and carbon atoms. Since there was no difference of more than 1% between the total atomic weight per unit volume and the specific gravity of the metal oxide film, it was assumed that the metal oxide film was mainly composed of the detected atoms, and the weight ratio per unit volume of the detected atoms was calculated as the composition ratio.

[0053] <Thermal resistance reliability> As the substrate described above, a 3cm square silicon wafer was used to form a metal oxide film, which was then subjected to a heat resistance test at 250°C for 1000 hours in an oven. After that, it was evaluated according to the test method specified in JIS K5600-5-6:1999 (cross-cut method). The laminate after the heat resistance test was cut in a grid pattern using a dedicated jig, and its adhesion was evaluated using a 25mm wide transparent pressure-sensitive adhesive tape. A good condition was defined as one where the cut edges were perfectly smooth and there was no peeling at any of the grid lines, while a poor condition with peeling was defined as a failure.

[0054] <Step reduction rate> As the substrate described above, the following textured substrate was prepared. Stripe-shaped textures were fabricated on a transparent glass substrate using a photocurable resist by a conventional method (stripe width: 50 μm). The surface texture (step) of this substrate was measured using a micro-shape measuring instrument (manufactured by Kosaka Laboratory Co., Ltd.; trademark; Surfcoder ET400), and the result was 1.0 μm. Next, the surface texture of a substrate on which a metal oxide film was prepared using the above method was measured using the same measuring instrument, and the step reduction rate was calculated. A rate of 30% or more was judged to be acceptable. The step reduction rate is calculated using the following formula. Step reduction rate (%) = {(Step height of the uneven substrate before metal oxide film formation (μm) - Step height of the uneven substrate after metal oxide film formation (μm)) / Step height of the uneven substrate before metal oxide film formation (μm)} × 100

[0055] [Table 1]

[0056] [Table 2]

[0057] [Table 3]

[0058] [Table 4]

[0059] In Table 1-3, Al(acac)3 is aluminum tris(acetylacetonate) ("Aluminum Chelate A," manufactured by Kawaken Fine Chemical Co., Ltd.); AlCl3 is aluminum chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.); Al(NO3)3·9H2O is aluminum nitrate notahydrate (manufactured by Sigma-Aldrich). Zr(acac)4 is tetrakis(2,4-pentanedionato)zirconium(IV) (manufactured by Tokyo Chemical Industry Co., Ltd.); ZrO(NO3)2·2H2O is zirconium oxynitrate (dihydrate) (manufactured by Kishida Chemical Co., Ltd.). Zn(acac)2 is zinc(II) acetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd.); ZnCl2 is zinc chloride (manufactured by Tokyo Chemical Industry Co., Ltd.); GaCl3 is gallium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.); Zr(DPM)4 represents tetrakiszirconium (2,2,6,6-tetramethyl-3,5-heptanedione), manufactured by Sigma-Aldrich.

[0060] Table 4 shows the melting points and electronegativity of each metal in the above-mentioned β-diketone complexes and inorganic metal salts.

[0061] Since Examples 1-14 used β-diketone complexes and inorganic metal salts for film formation, the flatness of the resulting metal oxide films was satisfactory compared to Comparative Example 1, which did not contain inorganic metal salts in the coating solution.

[0062] In Examples 2-4, the molar ratio of metal atoms in the β-diketone complex to metal atoms in the inorganic metal salt contained in the film-forming coating solution used was 0.01 to 20, resulting in superior flatness of the metal oxide film compared to Examples 1 and 5.

[0063] In Example 3, the electronegativity of the metal atoms constituting the inorganic metal salt used was 1.80 or less. Therefore, compared to Example 9, where the electronegativity of the metal atoms constituting the inorganic metal salt was greater than 1.80, the resulting metal oxide film exhibited superior flatness.

[0064] In Example 6, the anion constituting the inorganic metal salt used was an oxoate ion, resulting in superior flatness of the resulting metal oxide film compared to Example 3, where the anion constituting the inorganic metal salt was a chloride ion.

[0065] In Examples 3 and 7, the metal atoms constituting the β-diketone complex used had melting points of 500°C or higher, resulting in superior flatness of the resulting metal oxide films.

[0066] Example 12 used a two-component film-forming coating solution. Film-forming coating solution A and film-forming coating solution B were atomized separately to form a metal oxide film. The flatness of the resulting metal oxide film was satisfactory.

[0067] Example 13 used a three-component film-forming coating solution. Film-forming coating solution A, film-forming coating solution B, and water (an oxygen source) were each atomized separately to form a metal oxide film. The flatness of the resulting metal oxide film was satisfactory.

Claims

1. This is a coating solution used for forming metal oxide films by chemical vapor deposition. The aforementioned film-forming coating solution is a one-component film-forming coating solution containing a β-diketone complex, an inorganic metal salt, and a solvent, or A multi-component film-forming coating solution comprising a film-forming coating solution A containing a β-diketone complex and a solvent, and a film-forming coating solution B containing an inorganic metal salt and a solvent, The β-diketone complex and the inorganic metal salt are film-forming coating solutions composed of metal atoms belonging to the 3rd to 6th period and groups 2 to 14.

2. The film-forming coating liquid according to claim 1, wherein the molar ratio of the metal atoms of the β-diketone complex to the metal atoms of the inorganic metal salt is 0.01 to 20.

3. A coating liquid for film formation according to claim 1 or 2, used for planarizing a substrate.

4. A metal oxide film formed from the film-forming coating liquid described in claim 1 or 2, having a thickness of 30 μm or less.

5. A planarized film comprising a metal oxide film as described in claim 4.

6. A misting step in which the one-component film-forming coating liquid is atomized, according to claim 1 or 2, A method for forming a metal oxide film by chemical vapor deposition, comprising the steps of supplying the obtained mist to a heated substrate surface and allowing it to react on the substrate.

7. A two-tank misting step in which the film-forming coating liquid A and the film-forming coating liquid B in the film-forming coating liquid according to claim 1 are each misted separately, A method for forming a metal oxide film by chemical vapor deposition, comprising the steps of supplying each mist to a heated substrate surface and allowing it to react on the substrate.

8. A method for forming a metal oxide film by chemical vapor deposition according to claim 7, wherein mist of the film-forming coating liquid A and the film-forming coating liquid B is supplied to the heated surface of the substrate such that the molar ratio of the metal atoms of the β-diketone complex to the metal atoms of the inorganic metal salt contained in each of the coating liquids is 0.01 to 20.

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