Film-forming auxiliary agent, film-forming coating liquid, laminate, and film-forming method

Abstract

To provide a film-forming auxiliary capable of forming silica-containing alumina having good mechanical strength and excellent in adhesion and wear resistance even after a heat resistance test by a chemical vapor deposition method.SOLUTION: A film-forming auxiliary agent for a chemical vapor phase growth method, which is used for forming a silica-containing alumina film by the chemical vapor phase growth method and which is ammonium salts showing a pH of 4.5 to 10.0 at 25 °C in an aqueous solution of the 1M.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film-forming auxiliary, a film-forming coating liquid, a laminate, and a film-forming method. [Background technology]

[0002] Silica-containing alumina, which is a mixture of alumina and silica, is used in various industries due to its excellent heat resistance, corrosion resistance, and wear resistance, and is also used in high-temperature parts such as aircraft engines and gas turbines.

[0003] Furthermore, ceramics are primarily formed using methods such as extrusion, injection molding, pressure molding, and slip casting, all of which are made from a mixture of ceramic powder, a binder made of organic matter such as resin, and water. Ceramics made using these methods require a firing process after molding, and volume shrinkage occurs during this process, resulting in a lack of dimensional stability. As a result, a new method has emerged in which a protective ceramic film is formed on the surface of a material such as metal that has been pre-formed to the desired shape, resulting in parts with high dimensional stability.

[0004] For example, the aerosol deposition method is a technique for producing a film by spraying fine powder of ceramics or metals in a solid state onto a substrate. While this method can produce a dense film without heating the substrate, etching of the substrate can occur depending on the incident angle of the powder, making it difficult to coat three-dimensional structures (Non-Patent Document 1).

[0005] Plasma spraying is a method of producing a coating by applying heat to a raw material powder, wire, or rod-shaped solid to melt it, and then spraying the liquid onto a substrate (Non-Patent Document 2). This method has a coating formation speed of approximately 104 μm / min, which is significantly faster than chemical vapor deposition (hereinafter referred to as "CVD") or plating, but adhesion in spraying is achieved by mechanical force, and the substrate surface is often roughened to increase the surface area.

[0006] The above-mentioned CVD is a technique in which a gas containing the components that will become the raw materials for the thin film is sent to the surface of a substrate, and a film is formed through a chemical reaction. Heat, plasma, etc. are used to promote the chemical reaction. In recent years, mist CVD (hereinafter also referred to as "mCVD"), which is a type of CVD that allows for film formation at low temperatures in the atmosphere without the need for reduced pressure equipment, has been studied (Patent Document 1). Mist CVD is a technique in which a solution containing the raw materials is turned into a mist using ultrasound or other methods, and then sent onto the surface of a substrate to form a film. The mist containing the raw materials is about several microns in size and has high three-dimensional tracking ability. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2018-140352 [Non-patent literature]

[0008] [Non-Patent Document 1] Jun Akedo and Masakatsu Kiyohara, "Room Temperature Ceramic Coating (AD Method) and Its Potential for 3D Printing Applications," Journal of Smart Processing, Vol. 3, No. 3, May 2014, pp. 158-166 [Non-patent document 2] Mitsumasa Sasaki, "Surface Modification Using Ceramics by Plasma Spraying", Surface Technology, Vol. 51, No. 2, 2000, pp. 167-174 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in mist CVD, gases can get mixed into the silica-containing alumina film during deposition. These gases are gradually released during use in high-temperature environments, creating pores in the film. These pores can damage the film and reduce its mechanical strength. As a result, the heat resistance and abrasion resistance expected of silica-containing alumina cannot be achieved, and there is a risk of corrosion of the substrate from the damaged areas of the film.

[0010] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a film-forming auxiliary agent that can form, by a chemical vapor deposition method, silica-containing alumina that has good mechanical strength and excellent adhesion and abrasion resistance even after a heat resistance test.

[0011] Another object of the present invention is to provide a film-forming coating fluid containing the above-mentioned film-forming aid, a laminate having a silica-containing alumina film formed from the film-forming coating fluid, and a film-forming method by chemical vapor deposition using the coating fluid. [Means for solving the problem]

[0012] The present invention relates to [1] a film-forming auxiliary for chemical vapor deposition, which is an ammonium salt that exhibits a pH of 4.5 to 10.0 in a 1 M aqueous solution at 25°C and is used for forming a silica-containing alumina film by chemical vapor deposition.

[0013] The present invention also relates to [2] a film-forming coating liquid that preferably contains the film-forming auxiliary of [1] above and a solvent.

[0014] The present invention also relates to the film-forming coating fluid [2] above, which preferably contains [3] a silicon-containing compound and an aluminum-containing compound.

[0015] The present invention also relates to [4] the film-forming coating fluid according to the above [3], wherein the molar ratio of aluminum atoms of the aluminum-containing compound to silicon atoms of the silicon-containing compound (moles Al / moles Si) is preferably 0.01 to 20.0, and the molar ratio of the ammonium salt to the total of the silicon atoms and the aluminum atoms (moles ammonium salt / (moles Al+moles Si)) is preferably 0.1 to 80.0.

[0016] The present invention also relates to [5] the film-forming coating fluid according to the above [3] or [4], wherein the silicon-containing compound is preferably an alkoxysilane having 4 to 20 carbon atoms.

[0017] The present invention also relates to [6] a laminate having a silica-containing alumina film formed on the surface of a substrate from any one of the film-forming coating solutions [2] to [5] above, the film having a thickness of 10 μm or less.

[0018] The present invention also relates to [7] the laminate according to the above item [6], wherein the silica-containing alumina film preferably has a composition formula SiaAlbOcTd (wherein Si is a silicon atom, Al is an aluminum atom, O is an oxygen atom, and T is an atom or atoms other than Si, Al, and O; a, b, c, and d are weight ratios, where a+b+c+d=100, a is 1 or more and 45 or less, b is 3 or more and 55 or less, c is 35 or more and 70 or less, and d is 0 or more and 40 or less).

[0019] The present invention also relates to [8] a method for forming a silica-containing alumina film by chemical vapor deposition, which includes a two-tank mist-forming step of separately misting the film-forming coating solution according to [2] above and a metal source solution containing a silicon-containing compound and an aluminum-containing compound, and a step of supplying each mist to a heated substrate surface and causing a reaction on the substrate.

[0020] The present invention also relates to the method for forming a silica-containing alumina film by chemical vapor deposition according to the above item [8], wherein the molar ratio of the ammonium salt to the sum of silicon atoms of the silicon-containing compound and aluminum atoms of the aluminum-containing compound (moles of the ammonium salt / (moles of Al+moles of Si)) is preferably 0.1 to 80.0.

[0021] The present invention also relates to

[10] a method for forming a silica-containing alumina film by chemical vapor deposition, comprising: a step of misting the film-forming coating liquid according to any one of [3] to [5] above; and a step of supplying the mist obtained to a heated substrate surface and causing a reaction on the substrate. [Effects of the Invention]

[0022] It is presumed that the film-forming aid of the present invention prevents gas from being mixed into the film during film formation of silica-containing alumina, and therefore the silica-containing alumina film formed from the film-forming coating liquid containing the film-forming aid has good mechanical strength and is excellent in adhesion and abrasion resistance even after heat resistance testing. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram of a film-forming apparatus for a silica-containing alumina film in a method for producing a silica-containing alumina film according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram of a film-forming apparatus for a silica-containing alumina film in a method for producing a silica-containing alumina film according to one embodiment of the present invention. [Figure 3] 1 is a schematic diagram of a mist generator in a film forming apparatus for forming a silica-containing alumina film in a method for producing a silica-containing alumina film according to one embodiment of the present invention. [Figure 4] 1 is a schematic diagram of a mixing tank in a film forming apparatus for a silica-containing alumina film in a method for producing a silica-containing alumina film according to one embodiment of the present invention. [Figure 5] 1 is a schematic diagram of a film forming section in a film forming apparatus for forming a silica-containing alumina film in a method for producing a silica-containing alumina film according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, a film-forming auxiliary, a film-forming coating liquid, a laminate, and a film-forming method according to one embodiment of the present invention will be described with reference to drawings as necessary.

[0025] <Film-forming aid> The film-forming aid used in the present invention is an ammonium salt that exhibits a pH of 4.5 to 10.0 in a 1 M aqueous solution at 25°C, and is used for forming a silica-containing alumina film by chemical vapor deposition. Examples of counter anions of the ammonium salt include carboxylate ions, perchlorate ions, hydroxide ions, sulfonate ions, sulfate ions, nitrate ions, phosphate ions, halide ions, carbonate ions, bicarbonate ions, borate ions, and silicate ions. From the viewpoint of storage stability of the coating solution, the film-forming aid is preferably an ammonium salt that exhibits a pH of 5.5 to 8.5 in a 1 M aqueous solution at 25°C. Furthermore, since the aid is less likely to remain in the film, the counter anion is preferably derived from an acid that volatilizes at room temperature and normal pressure (25°C, 1013 hPa), such as carboxylate ions, nitrate ions, phosphate ions, halide ions, carbonate ions, and bicarbonate ions. Furthermore, ammonium salts of inorganic compounds are preferred to prevent the residue of carbon derived from organic substances. Examples of the ammonium salt include ammonium carbonate, ammonium chloride, and ammonium hydrogen carbonate. Among these, ammonium carbonate is preferred from the viewpoint of the heat resistance and abrasion resistance of the resulting film.

[0026] When silicon-containing compounds and aluminum-containing compounds react to form silica-containing alumina by chemical vapor deposition, it is believed that the reaction occurs via a hydroxide intermediate. The ammonium salt used as a film-forming additive is completely ionized in the coating solution to produce ammonium ions. These ammonium ions act as a catalyst, promoting the decomposition of alkoxide groups and ligands released from the silicon-containing and aluminum-containing compounds. This prevents gases derived from the alkoxide groups and ligands from remaining in the film, improving the mechanical strength of the film. Furthermore, the film-forming additive abstracts protons from hydroxides, the reaction intermediates of silica-containing alumina, improving nucleophilicity and promoting the addition reaction of highly electrophilic metal-containing compounds to the central metal. This is also expected to promote the formation of silicon-oxygen-aluminum bonds.

[0027] <Film-forming coating liquid> The film-forming coating fluid of the present invention is preferably in the form of a coating fluid (A) containing the film-forming aid and a solvent, or a coating fluid (B) containing the film-forming aid, a silicon-containing compound, an aluminum-containing compound, and a solvent. The coating fluid (A) is suitable for a chemical vapor deposition film-forming method in which the coating fluid and a metal source solution containing a silicon-containing compound and an aluminum-containing compound are separately misted and the respective mist is supplied to form a silica-containing alumina film. The coating fluid (B) is also suitable for a chemical vapor deposition film-forming method in which the coating fluid is misted and supplied to form a silica-containing alumina film. The mist-forming method used in the present invention includes atomization and dropletization, and refers to breaking down a liquid into fine particles and dispersing them in a gas.

[0028] <Solvent> The solvent may be any solvent capable of dissolving the film-forming aid, silicon-containing compound, and aluminum-containing compound. However, from the viewpoint of mist generation efficiency, a solvent having a boiling point of 40°C to 150°C and a viscosity at 25°C of 1.3 mPa·sec or less is preferred, a solvent having a viscosity of 0.1 mPa·sec to 1.0 mPa·sec or less is more preferred, and a solvent having a viscosity of 0.5 mPa·sec to 1.0 mPa·sec or less is even more preferred. Examples of the solvent include polar solvents such as lower alcohols (e.g., methanol), nitrile-based solvents (e.g., acetonitrile), and water, as well as nonpolar solvents (e.g., toluene). Two or more of these solvents may be mixed. Among these solvents, polar solvents are preferred, and lower alcohols and water are more preferred because they act as an oxidation source to fully achieve the effects of the present invention. Furthermore, the inclusion of water is preferred because of its ease of handling and the ability to prevent the mist-formed coating liquid from igniting. Here, the oxidation source is a source of oxygen atoms for converting the metal salt or complex described below into silica-containing alumina.

[0029] <Silicon-containing compounds> The silicon-containing compound used in the present invention may be any compound that can be misted when prepared as a coating liquid, and examples thereof include silane, siloxane, silazane, polysilazane, and alkoxysilane. In view of reactivity during film formation and the heat resistance and abrasion resistance of the resulting silica-containing alumina film, it is preferable to use an alkoxysilane. Furthermore, from the viewpoint of reactivity during film formation, an alkoxysilane having 4 to 20 carbon atoms is desirable.

[0030] <Aluminum-containing compounds> The aluminum-containing compound used in the present invention may be any compound that can be turned into a mist when prepared as a coating liquid, and examples thereof include alkoxide compounds, β-diketone complexes, organic acid salt compounds, inorganic salt compounds, etc. Furthermore, from the viewpoint of reactivity during film formation, alkoxide compounds or β-diketone complexes are preferred.

[0031] In the film-forming coating liquid, the film-forming auxiliary is generally contained in an amount of preferably 0.05% by weight or more and 20% by weight or less, and more preferably 0.5% by weight or more and 20% by weight or less.

[0032] In the coating liquid (A) and the metal source solution, or the coating liquid (B), the molar ratio of the film-forming aid to the total of silicon atoms and aluminum atoms (moles of the ammonium salt / (moles of Al+moles of Si)) is preferably 0.1 to 80, more preferably 1 to 70, from the viewpoint of the mechanical strength and heat resistance of the silica-containing alumina film, and even more preferably 5 to 60 from the viewpoint of the surface roughness of the silica-containing alumina film, and even more preferably 10 to 50 from the viewpoint of the heat resistance of the silica-containing alumina film.

[0033] In the coating liquid (B) or the metal source solution, the molar ratio of aluminum atoms of the aluminum-containing compound to silicon atoms of the silicon-containing compound (moles Al / moles Si) is preferably 0.01 to 20, more preferably 0.1 to 10 from the viewpoint of the mechanical strength of the silica-containing alumina film, and even more preferably 0.2 to 5 from the viewpoint of the adhesion of the silica-containing alumina film.

[0034] <Laminate> The laminate of the present invention has a silica-containing alumina film formed on the surface of a substrate from the film-forming coating liquid and having a thickness of 10 μm or less. The laminate is preferably formed by directly laminating the silica-containing alumina film onto a sheet-like substrate having a thickness of 0.2 mm to 20 mm, or onto a substrate processed into a specific shape using a mold. The term "direct lamination" as used herein means that there is no layer of 100 nm or more between the silica-containing alumina film and the substrate.

[0035] Examples of the material for the substrate include metal materials such as aluminum, stainless steel, zinc, and silicon, as well as graphite and glass. The shape of the substrate is not particularly limited and may be a plate or block, but plate-shaped substrates such as an aluminum plate, a glass plate, a silicon wafer, and a graphite sheet are preferred.

[0036] The silica-containing alumina film preferably has a composition formula: SiaAlbOcTd (wherein Si is a silicon atom, Al is an aluminum atom, O is an oxygen atom, and T is one or more atoms other than Si, Al, and O; a, b, c, and d are weight ratios, where a+b+c+d=100, a is 1 or more and 45 or less, b is 3 or more and 55 or less, c is 35 or more and 70 or less, and d is 0 or more and 40 or less). From the viewpoint of mechanical strength, the silica-containing alumina film more preferably has a value of a is 3 or more and 40 or less, b is 3 or more and 40 or less, c is 45 or more and 63 or less, and d is 0 or more and 30 or less. The above composition ratios can be determined by dynamic SIMS.

[0037] In the composition formula, T is an optional component and may not be included, or may contain a carbon atom from the viewpoint of preventing the silica-containing alumina film from hardening and suppressing cracks.

[0038] <Method for forming silica-containing alumina film by chemical vapor deposition> The method for forming the silica-containing alumina film may be any chemical vapor deposition method, and mCVD is preferred from the viewpoint of excellent film formation speed and film formation uniformity.

[0039] Examples of mCVD include a method for forming a silica-containing alumina film by chemical vapor deposition, which includes a two-tank mist-forming step in which the above-mentioned film-forming coating solution (A) and a metal source solution containing a silicon-containing compound and an aluminum-containing compound are separately misted, and a step in which each mist is supplied to a heated substrate surface and reacted on the substrate; and a method for forming a silica-containing alumina film by chemical vapor deposition, which includes a mist-forming step in which the above-mentioned film-forming coating solution (B) is misted, and a step in which the obtained mist is supplied to a heated substrate surface and reacted on the substrate.

[0040] 1 shows a schematic diagram of a film-forming apparatus (1) in a method for forming a silica-containing alumina film, which has a two-tank mist-forming process in which the above-mentioned film-forming coating solution (A) and a metal source solution containing a silicon-containing compound and an aluminum-containing compound are separately misted. The film-forming apparatus (1) is composed of two mist-forming devices, a mixing tank, and a film-forming machine (film-forming section) connected by piping.

[0041] 2 shows a schematic diagram of a film-forming apparatus (2) in a method for forming a silica-containing alumina film, which includes a mist-forming step of misting the film-forming coating solution (B). The film-forming apparatus (2) is composed of one mist-forming device and a film-forming machine (film-forming section) connected by piping.

[0042] Figure 3 shows a schematic diagram of the mist generator in a silica-containing alumina film deposition system. The mist generator consists of a container for containing raw materials and an ultrasonic generator equipped with an ultrasonic vibrator. The container is a glass cylinder with a Teflon (registered trademark) lid and a bottom made of polyethylene or tetrafluoroethylene-hexafluoropropylene copolymer film. Two glass pipes are installed to pass through the lid. The first pipe is installed to deliver carrier gas (nitrogen) for transporting the mist into the container, and the second pipe is installed to deliver the mist generated in the container and carrier gas to the deposition machine. The container is placed in an ultrasonic generator together with water, and ultrasonic waves generated by the ultrasonic vibrator are transmitted to the raw materials via the water and the polyethylene film, etc., to turn the raw materials into mist.

[0043] FIG. 4 shows a schematic diagram of a mixing tank in a silica-containing alumina film forming apparatus. The mixing tank is a glass container equipped with a Teflon (registered trademark) lid. Three glass pipes are provided to pass through the lid. Of the three pipes, two are connected to two mist generators, and the central pipe is connected to the film forming unit via a pipe. The mist generated in the mist generator is transported to the film forming unit via the mixing tank. This mixing tank is mainly used to mix the mists generated in the separate mist generators.

[0044] Figure 5 shows a schematic diagram of the film formation section of a silica-containing alumina film formation apparatus. The film formation section consists of a metal jig connected to the mist generator or mixing tank and a hot plate. The jig is connected to the mist generator or mixing tank with 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. Furthermore, if a jig with a large internal space is used in Figure 5, it is possible to form a film not only on plate-shaped substrates but also on substrates with three-dimensional shapes. The hot plate mentioned above is provided to heat the jig.

[0045] In the mCVD, an oxidizing agent such as ozone, oxygen, or hydrogen peroxide may be used as the oxygen source, with ozone being more preferred. Furthermore, to prevent the mist coating liquid from igniting, water, alcohol, or the like may be used as the oxygen source. Here, the oxygen source refers to a source of oxygen atoms for converting aluminum complexes or salts and silicon compounds into metal oxides.

[0046] The carrier gas is preferably an inert gas containing no more than 10,000 ppm (volume ratio) of oxygen in order to suppress oxidation of the substrate surface.

[0047] In mCVD, a silica-containing alumina film is preferably formed by thermally reacting a mist of raw material on a substrate in an atmosphere at a temperature of 200°C to 500°C, more preferably at 250°C to 450°C, and even more preferably at 300°C to 450°C. [Example]

[0048] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0049] <Measurement of pH of film-forming aid> The film-forming aids listed in Table 1-4 were dissolved in water to a concentration of 1 M, and the pH was measured at 25°C using a glass electrode hydrogen ion concentration indicator (D-54, manufactured by Horiba, Ltd.) The measurement was carried out three times, and the average value was calculated.

[0050] <Example 1-14> <Preparation of coating solution for film formation> A film-forming coating solution was prepared using the raw materials and blending amounts shown in Tables 1 and 2. <Formation of silica-containing alumina film on substrate> Using the film-forming apparatus (mist CVD apparatus) shown in Figures 2, 3, and 5, a silica-containing alumina film was formed on a substrate using the following method. A polyethylene or tetrafluoroethylene-hexafluoroethylene copolymer film was fixed 1 cm from the bottom of a glass cylinder (13 cm diameter, 15 cm height) using an O-ring and caulking. A Teflon® lid was attached to the top of the cylinder, and two holes were drilled in the lid into which glass pipes for nitrogen gas supply and mist transport were inserted. The glass tube for mist transport with a branch pipe was placed 1–2 cm from the metal material on the hot plate, and the branch pipe was connected to a silicone tube for nitrogen gas supply. The cylinder was immersed in a water bath, and an ultrasonic vibrator (ultrasonic atomization unit HMC-2401; Honda Electronics Co., Ltd.) was placed directly below the polyethylene or tetrafluoroethylene-hexafluoropropylene copolymer film. The hot plate was placed in a nitrogen-filled box, and film formation began once the oxygen concentration reached 1% or less. The above-mentioned coating solution was placed in a cylinder, and the ultrasonic transducer was activated. Ultrasonic waves were transmitted to the coating solution through the water in the tank and a polyethylene or tetrafluoroethylene-hexafluoroethylene copolymer film, atomizing a portion of the coating solution. The misted coating solution was then transported onto a substrate (30 mm x 30 mm) using nitrogen gas. The substrate was heated to 200°C, 250°C, or 360°C using a hot plate. Once the misted coating solution reached the substrate, a chemical reaction formed a silica-containing alumina film, yielding a laminate. The thickness of the silica-containing alumina film was adjusted by the film formation time (the time the misted coating solution was sprayed onto the substrate) and measured using the following method. The nitrogen gas flow rate was 11 L / min, the ultrasonic transducer frequency was 2.4 MHz, the voltage was 24 V, and the current was 0.6 A.

[0051] <Examples 15-26, Comparative Examples 1 and 2> <Preparation of coating solution for film formation> Examples 15-26 and Comparative Examples 1 and 2 were two-tank systems, and film-forming coating solutions were prepared using the raw materials and blending amounts shown in Tables 2-4, including a coating solution containing a film-forming aid and a solvent, and a metal source solution containing a silicon-containing compound, an aluminum-containing compound, and a solvent. <Formation of silica-containing alumina film on substrate> A silica-containing alumina film was formed on a substrate using the film-forming apparatus (mist CVD apparatus) shown in Figures 1 and 3-5, as follows. A polyethylene or tetrafluoroethylene-hexafluoroethylene copolymer film was fixed 1 cm from the bottom of a glass cylinder (13 cm diameter, 15 cm height) with an O-ring and caulking agent. A Teflon® lid was attached to the top of the cylinder, and two holes were drilled in the lid to insert glass pipes for nitrogen gas supply and mist transport. The glass tube with a branch pipe for mist transport was positioned 1–2 cm from the metal material on the hot plate, and the branch pipe was connected to a silicone tube for nitrogen gas supply. The cylinder was immersed in a water bath, and an ultrasonic vibrator (ultrasonic atomization unit HMC-2401; Honda Electronics Co., Ltd.) was placed directly below the polyethylene or tetrafluoroethylene-hexafluoropropylene copolymer film. The hot plate was placed in a nitrogen-filled box, and film formation began once the oxygen concentration reached 1% or less. The above-mentioned film-forming coating solution and metal source solution were placed separately in two cylinders, and the ultrasonic transducer was activated. Ultrasonic waves were transmitted to the film-forming coating solution and metal source solution via the water in the water tank and a polyethylene or tetrafluoroethylene-hexafluoroethylene copolymer film, atomizing a portion of the solution. The misted film-forming coating solution and metal source solution were then transported onto a substrate (30 mm x 30 mm) using nitrogen gas. The substrate was heated to 150°C, 300°C, or 360°C using a hot plate. Once the misted film-forming coating solution reached the substrate, a chemical reaction formed a silica-containing alumina film, yielding a laminate. The film thickness of the silica-containing alumina was adjusted by the film-forming time (the time the misted film-forming coating solution was sprayed onto the substrate) and measured using the following method. The flow rate of the nitrogen gas was 11 L / min, the frequency of the ultrasonic vibrator was 2.4 MHz, the voltage was 24 V, and the current was 0.6 A.

[0052] <Comparative Example 3> <Preparation of coating solution for film formation> A film-forming coating solution was prepared using the raw materials and blending amounts shown in Table 4. <Formation of silica-containing alumina film on substrate> A film-forming coating solution prepared with the composition shown in Table 4 was applied onto a substrate and then heated on a hot plate heated to 150° C. to obtain a silica-containing alumina film.

[0053] The samples obtained above were evaluated as follows, and the results are shown in Tables 1-4.

[0054] <Thickness measurement of silica-containing alumina film> The thickness of the silica-containing alumina film was measured by forming the silica-containing alumina film on a 30 x 30 mm silicon wafer as the substrate and measuring it with a surface profiler (DektakXT-S, manufactured by Bruker Japan Co., Ltd.). The shape of the surface of the obtained silica-containing alumina film laminate was measured from a position 3.5 mm from the edge to the edge, and the difference in height from the substrate surface was measured. The measurement was performed on a total of 10 spots on both ends, and the average value was taken as the film thickness.

[0055] <Measurement of the composition of silica-containing alumina film> The weights and ratios of aluminum, silicon, oxygen, and carbon atoms per unit volume were calculated using a dynamic SIMS (PHI ADEPT: manufactured by Ulvac-PHI). The dynamic SIMS conditions were as follows: primary ion species: Cs+, primary acceleration voltage: 5.0 kV, detection area: 45 × 45 μm. A copper substrate with a 1 μm silica-containing alumina film was used as the sample substrate. Measurements were taken from the center of the sample in the depth direction, and the depth at which copper was detected was defined as 1 μm. The weight ratios of the four atoms were calculated from the secondary ion intensities, relative sensitivity coefficients, and atomic weights of aluminum, silicon, oxygen, and carbon atoms. Since the total weight of the four elements per unit volume did not differ by more than 1% from the specific gravity of the silica-containing alumina film, the silica-containing alumina film was considered to be primarily composed of these four atoms, and the weight ratios of the four atoms per unit volume were calculated as the composition ratio.

[0056] <Mechanical strength evaluation> A 30 x 30 mm copper substrate was used as the substrate, and the resulting laminate with the silica-containing alumina film was wrapped around mandrels with diameters of 20 mm, 25 mm, and 32 mm based on a bending resistance test (cylindrical mandrel method) in accordance with JIS K5600-5-1:1999, and visually inspected for cracks in the silica-containing alumina film for evaluation. The evaluation criteria are shown below. "Evaluation A," "Evaluation B," and "Evaluation C" were considered acceptable, and "Evaluation D" was considered unacceptable. Rating A: No cracks were observed when a mandrel with a diameter of 20 mm was used. Rating B: No cracks were observed when a 25 mm diameter mandrel was used, but cracks occurred when a 20 mm diameter mandrel was used. Rating C: No cracks were observed when a 32 mm diameter mandrel was used, but cracks occurred when a 25 mm diameter mandrel was used. Rating D: Cracks occurred on the 32 mm diameter mandrel.

[0057] <Evaluation of adhesion after heat resistance test> A 30 x 30 mm silicon wafer was used as the substrate, and the resulting laminate with a silica-containing alumina film was subjected to a heat resistance test at 400°C for 24 hours, after which it was evaluated in accordance with the test method specified in JIS K5600-5-6:1999 (cross-cut method). After the heat resistance test, the laminate with a silica-containing alumina film was scored in a grid pattern using a special tool, and adhesion was evaluated using 25 mm wide transparent pressure-sensitive adhesive tape. The evaluation criteria are shown below. "Rating A," "Rating B," "Rating C," and "Rating D" were considered pass, and "Rating E" was considered fail. Rating A: The edges of the cut are completely smooth and there is no peeling on any of the grids. Grade B: The percentage of peeled lattices in the cross-cut area is less than 5%. Rating C: The percentage of peeled lattices in the cross-cut area is 5% or more but less than 10%. Grade D: The percentage of peeled lattices in the cross-cut area is 10% or more but less than 15%. Grade E: The percentage of peeled lattices in the cross-cut area is 15% or more but less than 20%.

[0058] <Evaluation of abrasion resistance after heat resistance test> A 30 x 30 mm silicon wafer was used as the substrate, and the resulting laminate with a silica-containing alumina film was subjected to a heat resistance test at 400°C for 24 hours. Following the pencil hardness test of JIS K5600-5-4:1999, a 9H to H pencil was used to scratch the surface of the silica-containing alumina film laminate, and the hardness of the pencil at which scratches began to form was determined. The evaluation criteria are shown below. "Evaluation A," "Evaluation B," "Evaluation C," and "Evaluation D" were considered acceptable, and "Evaluation E" was considered unacceptable. Rating A: Pencil hardness of 9H or higher. Rating B: Pencil hardness is 6H or more but less than 9H. Rating C: Pencil hardness is 4H or more but less than 6H. Rating D: Pencil hardness is 2H or more but less than 4H. Rating E: Pencil hardness is H or more but less than 2H.

[0059] <Evaluation of surface roughness (Ra) after heat resistance test> A 30 x 30 mm square Si wafer was used as the substrate, and the resulting laminate with a silica-containing alumina film was subjected to a heat resistance test at 400°C for 24 hours. After that, a measurement test was carried out using a surface profiler in accordance with JIS B0601 to determine the surface roughness (Ra) of the thin film-formed surface of the laminate with a silica-containing alumina film. Measurements were taken five times at equal intervals within a 1 cm square in the center of the thin film-formed surface, and the average was calculated. The evaluation criteria are shown below. "Evaluation A," "Evaluation B," "Evaluation C," and "Evaluation D" were considered pass, and "Evaluation E" was considered fail. Rating A: Surface roughness (Ra) is less than 0.3 nm. Rating B: Surface roughness (Ra) is 0.3 nm or more and less than 0.5 nm. Rating C: Surface roughness (Ra) is 0.5 nm or more and less than 1.0 nm. Rating D: Surface roughness (Ra) is 1.0 nm or more and less than 5.0 nm. Grade E: Surface roughness (Ra) is 5.0 nm or more and less than 10 nm.

[0060] [Table 1]

[0061] [Table 2]

[0062] [Table 3]

[0063] [Table 4]

[0064] In Table 1-4, Ammonium carbonate (Fujifilm Wako Pure Chemical Industries, Ltd.); Ammonium bicarbonate (Fujifilm Wako Pure Chemical Industries, Ltd.); Ammonium chloride (Fujifilm Wako Pure Chemical Industries, Ltd.); Hydrogen peroxide solution (Kishida Chemical Co., Ltd.); Concentrated hydrochloric acid (Kishida Chemical Co., Ltd.); Triethoxymethylsilane (Tokyo Chemical Industry Co., Ltd.); Triethoxysilane (Tokyo Chemical Industry Co., Ltd.); Tetraethoxysilane (Tokyo Chemical Industry Co., Ltd.); Tetraisopropoxysilane (Tokyo Chemical Industry Co., Ltd.); Tetrabutoxysilane (Tokyo Chemical Industry Co., Ltd.); Polysilazane (Tresmile ANN-120-20, Sanwa Chemical Co., Ltd.); Al(acac)3 is aluminum tris(acetylacetonate) ("Aluminum Chelate A", manufactured by Kawaken Fine Chemicals Co., Ltd.); Al(O-iPr)3 is aluminum isopropoxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Methanol is (manufactured by Kishida Chemical Co., Ltd.);

[0065] In Examples 1-26, the film was formed using the film-forming auxiliary, and the mechanical strength and heat resistance of the obtained silica-containing alumina film were satisfactory compared to Comparative Example 1, which did not contain this auxiliary.

[0066] In Example 25, the molar ratio of aluminum atoms of the aluminum-containing compound to silicon atoms of the silicon-containing compound contained in the film-forming coating fluid used was 0.1 to 10, and therefore the heat resistance of the silica-containing alumina film was superior to that of Example 22. Furthermore, in Example 25, the molar ratio of the film-forming auxiliary to the total of silicon atoms and aluminum atoms in the film-forming coating fluid was 1 to 70, and therefore the surface roughness of the silica-containing alumina film was lower than that of Example 24.

[0067] In Examples 15-26, the film forming method included multiple mist supplying steps, and therefore the surface roughness of the obtained silica-containing alumina films was lower than that of Examples 1-14.

[0068] In Examples 13-26, the film formation temperature was 250° C. or higher, and the mechanical strength and adhesiveness of the obtained silica-containing alumina films were higher than those in Examples 1-12.

[0069] In Comparative Example 1, film formation was performed without using a film-forming aid, and therefore the mechanical strength and heat resistance of the resulting silica-containing alumina film were lower than those of Example 1-26, which used a film-forming aid. In Comparative Example 2, hydrogen peroxide solution was used as the film-forming aid, and therefore the mechanical strength and heat resistance of the resulting silica-containing alumina film were lower than those of Example 1-26, which used the film-forming aid of the present invention. In Comparative Example 3, concentrated hydrochloric acid was used as the film-forming aid and the sol-gel method was used as the film-forming method, and therefore the mechanical strength of the resulting silica-containing alumina film was lower and the surface roughness was higher than those of Example 1-26.

Claims

1. A film-forming auxiliary for chemical vapor deposition, which is an ammonium salt that exhibits a pH of 4.5 to 10.0 in a 1M aqueous solution at 25°C, and is used for forming a silica-containing alumina film by chemical vapor deposition.

2. A film-forming coating liquid comprising the film-forming aid according to claim 1 and a solvent.

3. The film-forming coating liquid according to claim 2 , comprising a silicon-containing compound and an aluminum-containing compound.

4. the molar ratio of aluminum atoms of the aluminum-containing compound to silicon atoms of the silicon-containing compound (moles Al / moles Si) is 0.01 to 20.0; 4. The film-forming coating fluid according to claim 3, wherein a molar ratio of the ammonium salt to the total of the silicon atoms and the aluminum atoms (moles of the ammonium salt / (moles of Al+moles of Si)) is 0.1 to 80.

0.

5. 5. The film-forming coating solution according to claim 3, wherein the silicon-containing compound is an alkoxysilane having 4 to 20 carbon atoms.

6. A laminate having a silica-containing alumina film formed on a surface of a substrate from the film-forming coating liquid according to any one of claims 2 to 4 and having a thickness of 10 µm or less.

7. 7. The laminate according to claim 6, wherein the silica-containing alumina film has a composition formula SiaAlbOcTd (wherein Si is a silicon atom, Al is an aluminum atom, O is an oxygen atom, and T is an atom or atoms other than Si, Al, and O; a, b, c, and d are weight ratios, where a+b+c+d=100, a is 1 or more and 45 or less, b is 3 or more and 55 or less, c is 35 or more and 70 or less, and d is 0 or more and 40 or less).

8. a two-tank mist-forming step of separately misting the film-forming coating solution according to claim 2 and a metal source solution containing a silicon-containing compound and an aluminum-containing compound; A method for forming a silica-containing alumina film by chemical vapor deposition, comprising the steps of supplying each mist to a heated substrate surface and causing a reaction on the substrate.

9. 9. The method for forming a silica-containing alumina film by chemical vapor deposition according to claim 8, wherein the molar ratio of the ammonium salt to the sum of silicon atoms of the silicon-containing compound and aluminum atoms of the aluminum-containing compound (moles of the ammonium salt / (moles of Al+moles of Si)) is 0.1 to 80.

0.

10. a mist-forming step of forming the film-forming coating liquid according to claim 3 or 4 into a mist; The method for forming a silica-containing alumina film by chemical vapor deposition includes a step of supplying the obtained mist to a heated substrate surface and causing a reaction on the substrate.

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