Coated base material and method for producing coated base material

Abstract

Provided is a novel coated substrate which can be applied to various fields and from which high functionality can be expected. The coated substrate is a coated substrate (1) in which a substrate (5) is coated with a film (3). The thickness of the film (3) is 60 nm or greater and 10 µm or less, measurement of the film (3) shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 70 atm% or greater, the film (3) is amorphous, and the relative density of the film (3) is 90% or greater.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a coated substrate and a method for producing a coated substrate.BACKGROUND ART

[0002] Patent Literatures 1 to 4 disclose coated substrates having metal oxide films. In Patent Literatures 1 to 4, a wet film-formation method is employed. Meanwhile, in some cases, a dry film-formation method (dry process) has been employed so as to perform thickness control in accordance with complex substrate shapes.

[0003] In consideration of performance of coated substates in the case where they are applied to various fields, conventional coated substrates are not necessarily satisfactory, and development of a novel coated substrate has been desired.CITATION LISTPATENT LITERATURES

[0004] Patent Literature 1: JP2011-32521A Patent Literature 2: JP2009-147192A Patent Literature 3: JP2015-93821A Patent Literature 4: JPH9-202606A SUMMARY OF INVENTIONTECHNICAL PROBLEM

[0005] The present disclosure was made in view of the above-described circumstances, and an object is to provide a novel coated substrate which is applicable to various fields and from which high functionality can be expected. The present disclosure can be realized as the following modes.SOLUTION TO PROBLEM

[0006] [1] A coated substrate in which a substrate is coated with a film, in which the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 70 atm% or greater, the film is amorphous, the relative density of the film is 90% or greater, and the film has a layered structure as a cross-sectional form. [2] The coated substrate recited in [1], wherein a portion of the substrate where the film is formed is electrically conductive. [3] The coated substrate recited in [1] or [2], wherein each layer of the layered structure has a thickness of 20 nm or greater and 500 nm or less. [4] The coated substrate recited in [1] or [2], wherein the metal element is at least one or more types of metals selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), Mn (manganese), and Mg (magnesium). [5] The coated substrate recited in [1] or [2], wherein the film contains a compound having at least one type of structure selected from C-H, C=O, and C-O bonds. [6] The coated substrate recited in [1] or [2], wherein, in the film, the percentage of a halogen element is 0.1 atm% or greater. [7] A method for producing a coated substrate by using a bath liquid containing an organic solvent, wherein the water content of the bath liquid is less than 5 mass% and the bath liquid contains at least one or more types of metal elements and at least one or more types of halogen elements, the method comprises a forming step of forming a film layer containing the metal element on the substrate on a negative electrode side by applying a voltage in a state in which the substrate is immersed in the bath liquid, and a drying step of drying the film layer, and a set including the forming step and the drying step is repeated at least two times or more, thereby forming a film having a layered structure. [8] A coated substrate in which a substrate is coated with a film, wherein the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 70 atm% or greater, the film is amorphous, and the relative density of the film is 90% or greater. ADVANTAGEOUS EFFECT OF INVENTION

[0007] According to the present disclosure, there is provided a novel coated substrate which can be applied to various fields and can be mass produced.

[0008] In addition, in the coated substrate of the present disclosure, internal cracking of the film is suppressed, and adhesion between the film and the substrate is high.BRIEF DESCRIPTION OF DRAWINGS

[0009] [FIG. 1] Schematic view showing a cross section of one example of a coated substrate according to a first embodiment. [FIG. 2] Schematic view of a film formation apparatus. [FIG. 3] Schematic view showing a cross section of one example of a coated substrate according to a second embodiment. DESCRIPTION OF EMBODIMENTS

[0010] The present disclosure will now be described in detail. Notably, in the present specification, in a description in which "-" is used for a numerical range, the numerical range contains its upper and lower limit values, unless otherwise specifically noted. For example, a description of "10 - 20" should be read to contain both "10" (lower limit value) and "20" (upper limit value). Namely, "10 - 20" has the same meaning as "10 or greater and 20 or less." Also, in the present specification, the upper and lower limit values of various numerical ranges may be combined freely.1. Coated substrate 1

[0011] A coated substrate 1 includes a substrate 5 coated with a film 3. The thickness of the film 3 is 40 nm or greater and 10 µm or less.

[0012] Measurement of the film 3 shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 70 atm% or greater. The film 3 is amorphous. The relative density of the film 3 is 90% or greater. The film 3 may have a layered structure as a cross-sectional form in some cases. Namely, the film 3 has a layered structure in a first embodiment (see FIG. 1), and does not have the layered structure in a second embodiment (see FIG. 3).(1) Substrate 5

[0013] No particular limitation is imposed on the substrate 5. In order to enhance adhesion of the film 3 to the substrate 5, at least a portion (region) of the substrate 5, which portion is to be coated with the film 3, is preferably formed of a material which is electrically conductive and can function as a negative electrode 7 (cathode). In the case where the portion of the substrate 5, which portion is to be coated with the film 3, is electrically conductive and functions as the negative electrode 7 (cathode), the film 3 can be easily formed on that portion by voltage application.

[0014] A surface portion of the substrate 5 may be formed of a material which is electrically conductive and can function as the negative electrode 7. The entire substrate 5 may be formed of a material which can function as the negative electrode 7. Examples of preferred materials which can serve as the negative electrode 7 include an iron-based alloy and carbon. Examples of preferred iron-based alloys include one or more types of alloys selected from Fe-Ni-Cr alloy (austenitic stainless steel), Fe-Cr alloy (ferritic stainless steel), Fe-Ni alloy (permalloy), Fe-Si alloy (silicon iron), Fe-Si-Al alloy (Sendust), Fe-Ni-Mo (supermalloy), Fe-Co alloy (permendur), Fe-Ni-Co alloy (Kovar), and Fe-C-B alloy (amorphous).(2) Film 3(2.1) Thickness

[0015] From the viewpoint of enabling the film 3 to exhibit a function corresponding to the material of the film 3, the thickness of the film 3 is 40 nm or greater, preferably 100 nm or greater, more preferably 200 nm or greater. Meanwhile, from the viewpoints of enabling the film 3 to endure stresses generated therein and securing adhesion to the substrate 5, the thickness of the film 3 is 10 µm or less, preferably 1000 nm or less, more preferably 800 nm or less. From these viewpoints, the thickness of the film 3 is 40 nm or greater and 10 µm or less, preferably 100 nm or greater and 1000 nm or less, more preferably 200 nm or greater and 800 nm or less. Notably, in the case where the thickness of the film 3 is not uniform, the film 3 satisfies the requirement regarding the thickness when the thickness of at least a portion of the film 3 falls within the above-described range. The thickness of the film 3 can be obtained through observation under an FIB-SEM.(2.2) Percentage of C (carbon) element

[0016] From the viewpoints of suppressing growth of crystal grains in the film 3 and stabilizing the properties of the film 3, the percentage of C (carbon) element determined through measurement by x-ray photoelectron spectroscopy (XPS method) is 0.1 atm% or greater, preferably 0.5 atm% or greater, more preferably 1 atm% or greater. Meanwhile, from the viewpoint of enabling the film 3 to sufficiently function as an inorganic film, the percentage of C (carbon) element is less than 20 atm%, preferably 15 atm% or less, more preferably 10 atm% or less. From these viewpoints, the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, preferably 0.5 atm% or greater and 15 atm% or less, more preferably 1 atm% or greater and 10 atm% or less. Notably, in the case where the composition of the film 3 is not uniform, the film 3 satisfies the requirement regarding the percentage of C (carbon) element when the composition of at least a portion of the film 3 falls within the above-described range.

[0017] The composition analysis by the x-ray photoelectron spectroscopy can be performed by using an x-ray photoelectron spectrometer. The measurement can be performed by scanning a cross section under the following measurement conditions: K-alpha rays of aluminum being used as an x-ray source, the beam diameter being set to 100 µm, and the x-ray incident angle in relation to a surface to be analyzed being set to 45°.(2.3) Sum of the percentage of the metal element and the percentage of O (oxygen) element

[0018] From the viewpoint of enabling the film 3 to sufficiently function as an inorganic film, the sum of the percentage of the metal element and the percentage of O (oxygen) element of the film 3 determined through measurement by the x-ray photoelectron spectroscopy (XPS method) is 80 atm% or greater, preferably 85 atm% or greater, more preferably 90 atm% or greater. Notably, the upper limit of the sum of the percentage of the metal element and the percentage of O (oxygen) element is a value obtained by subtracting the percentage (atm%) of C (carbon) element from 100 atm%. In the case where the composition of the film 3 is not uniform, the film 3 satisfies the requirement regarding the sum of the percentage of the metal element and the percentage of O (oxygen) element when the composition of at least a portion of the film 3 falls within the above-described range.(2.4) Amorphous

[0019] The film 3 is amorphous. The fact that the film 3 is amorphous can be confirmed by using a TEM image. Since the film 3 is amorphous, it is expected that coming off of crystal grains does not occur, and peculiar functions, such as smoothing of the outermost surface by unform film growth, are exhibited.(2.5) Relative density of film 3

[0020] From the viewpoint of enabling the film 3 to sufficiently exhibit the function of the film 3, the relative density of the film 3 is 90% or greater, preferably 95% or greater, more preferably 98% or greater. The relative density of the film 3 may be 100%.

[0021] The relative density of the film 3 is obtained by the following method. A TEM image of a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction is obtained. The area of pores in a field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension) is measured. The relative density (%) is obtained in accordance with the following expression (1). The average of the relative densities of 10 fields of view is the relative density of the film 3. Notably, in the case where the thickness of the film 3 is smaller than the vertical size of 300 nm, measurement is performed in fields of view determined in accordance with the thickness of the film 3. Relative density % = S 1 − S 2 / S 1 × 100 (In the expression, S1 is the area (nm 2< ) of the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension), and S2 is the total area (nm 2< ) of pores in the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension))(2.6) Layered structure

[0022] The film 3 may have a layered structure as a cross-sectional form in some cases. In the case of this embodiment, the layered structure of the film 3 can be confirmed through observation of a cross section of the film 3 under the FIB-SEM (dual-beam scanning electron microscope), the cross section being obtained by cutting the film 3 in the film thickness direction.

[0023] Since the film 3 has a layered structure, internal cracking of the film 3 and peeling off of the film 3 from the substrate 5 can be prevented.(2.7) Thickness of each layer in layered structure

[0024] No particular limitation is imposed on the thickness of each layer in the layered structure.

[0025] From the viewpoint of increasing the strength of the film 3, the thickness of each layer is preferably 20 nm or greater and 500 nm or less, more preferably 40 nm or greater and 300 nm or less, further preferably 60 nm or greater and 200 nm or less. The thickness of each layer can be obtained through observation of a cross section of the film 3 under the FIB-SEM (dual-beam scanning electron microscope), the cross section being obtained by cutting the film 3 in the film thickness direction.(2.8) Metal element

[0026] No particular limitation is imposed on the metal element. From the viewpoint of facilitating formation of the film 3 having an increased strength by the production method described later and serving as a high quality protective layer, the metal element is preferably at least one or more metal elements selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), Mn (manganese), and Mg (magnesium).(2.9) Compound having at least one type of structure selected from C-H bond, C=O bond, and C-O bond

[0027] The film 3 preferably contains a compound having at least one type of structure selected from C-H, C=O, and C-O bonds. Since the compound having at least one type of structure selected from C-H, C=O, and C-O bonds volatiles at a lower temperature as compared with element C (carbon) and induces shrinkage of the film 3, presumably, the density of the film 3 increases.

[0028] In addition, the compound having at least one type of structure selected from C-H, C=O, and C-O bonds remains in the film 3, whereby, presumably, the flexibility of the film 3 is maintained, and adhesion of the film 3 to the substate 5 is also enhanced.(2.10) Halogen element

[0029] The percentage of the halogen element as determined through measurement of the film 3 by x-ray photoelectron spectroscopy is preferably 0.1 atm% or greater, more preferably 0.3 atm% or greater, further preferably 0.5 atm% or greater. The upper limit value of the percentage of the halogen element is 3 atm% or less.

[0030] Since a small amount of halogen element is contained in the film 3, conceivably, the oxide film present on the surface of the substrate 5 is removed by the action of the halogen element, and the film 3 comes into direct contact with the substrate 5. As a result, the adhesion between the substrate 5 and the film 3 is secured. From the viewpoints of enabling quick progress of an organic electrochemical reaction and enabling the film 3 to function as a high-quality protection layer for the substrate 5, the halogen element is preferably at least one or more halogen elements selected from the group consisting of I (iodine), Cl (chlorine), and Br (bromine).2. Method for producing coated substrate 1

[0031] No particular limitation is imposed on a method for producing the coated substrate 1 of the present disclosure.

[0032] A preferred production method will now be described below. The preferred production method is a method for producing the coated substrate 1 by using a bath liquid 2 containing an organic solvent. The water content of the bath liquid 2 is less than 5 mass% and the bath liquid 2 contains at least one or more types of metal elements and at least one or more types of halogen elements. The present production method includes a forming step of forming a metal-element-containing film layer on the substrate 5 on the negative electrode 7 side (on the cathode side), by applying a voltage in a state in which the substrate 5 is immersed in the bath liquid. In addition, the present production method includes a drying step of drying the film layer. In the present production method, the film 3 having a layered structure is formed by repeating at least two times or more a set including the forming step and the drying step.

[0033] Notably, in the product method of the present disclosure, since electrodeposition is taken place on the negative electrode 7 side, oxidation of the substrate 5 can be suppressed as compared with the case where electrodeposition is taken place on the positive electrode 6 side (anode side).(1) Bath liquid 2

[0034] The bath liquid 2 contains an organic solvent.(1.1) Water content

[0035] From the viewpoints of guaranteeing the homogeneity of the film 3 and suppressing oxidation of the substrate 5, the water content of the bath liquid 2 is rendered less than 5 mass%. The water content is preferably less than 3 mass%, more preferably less than 0.1 mass%. The water content may be 0 mass%. The water content of the bath liquid 2 can be obtained by GC-MS analysis.(1.2) Metal element

[0036] The bath liquid 2 contains at least one or more types of metal elements. No particular limitation is imposed on the metal elements. From the viewpoint of causing the film 3 to function as a high quality protection film for the substrate 5, the metal element is preferably at least one or more metal elements selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), and Mn (manganese). In the production method of the present disclosure, an oxide film depending on the metal element(s) in the bath liquid 2 is formed as the film 3.

[0037] The metal element(s) contained in the bath liquid 2 may be supplied as a result of elution of the positive electrode 6 (anode). In the case where the metal element(s) elutes from the positive electrode 6 into the bath liquid 2, control of film formation speed becomes easy, and continuous and stable formation of films on a plurality of substrates 5 becomes possible. In the case where the metal element(s) is supplied to the bath liquid 2 as a result of elution of the positive electrode 6, at least one or more types of electrodes selected from an electrode of Al, an electrode of Ti, and an electrode of Mo are preferably used as the positive electrode 6.

[0038] The metal element(s) in the bath liquid 2 may be supplied from a metal alkoxide and / or an inorganic metal compound. In the case where the metal element(s) is supplied as a result of dissolution of a metal alkoxide and / or an inorganic metal compound, it is possible to cope with an element which is difficult to supply by eluting the positive electrode 6 (anode). Also, in this case, it becomes possible to perform film formation in which composition ratios are controlled by combining a plurality of metal elements.

[0039] Examples of the metal alkoxide include an aluminum alkoxide, a titanium alkoxide, and a molybdenum alkoxide.

[0040] Examples of the aluminum alkoxide include an aluminum trialkoxide. Examples of the aluminum trialkoxide include aluminum tripropoxides (e.g., aluminum triisopropoxide and aluminum tri-n-propoxide), aluminum triethoxide, aluminum tributoxides (e.g., aluminum tri-sec-butoxide and aluminum tri-n-butoxide).

[0041] Examples of the titanium alkoxide include a titanium trialkoxide, a titanium tetraalkoxide, and a titanium tetraalkoxide is preferred. Examples of the titanium tetraalkoxide include titanium tetrapropoxides (e.g., titanium tetraisopropoxide and titanium tetra-n-propoxide), titanium tetramethoxide, titanium tetraethoxide, titanium tetrabutoxides (e.g., titanium tetraisobutoxide and titanium tetra-n-butoxide), titanium tetrapentoxides, titanium tetrahexoxides, and titanium tetra (2-ethylhexoxide).

[0042] Examples of the inorganic metal compound include aluminum chloride, aluminum bromide, aluminum iodide, and titanium iodide.

[0043] In the case where the metal element(s) in the bath liquid 2 is supplied from a metal alkoxide and / or an inorganic metal compound, no particular limitation is imposed on the metal element concentration of the bath liquid 2. In this case, from the viewpoint of forming a satisfactory film 3, the metal element concentration of the bath liquid 2 is preferably 1 ppm or greater and 100 ppm or less, more preferably 3 ppm or greater and 10 ppm or less, further preferably 4 ppm or greater and 6 ppm or less. Notably, "ppm" means "parts per million" and "mg / L." Notably, in the case where the bath liquid 2 contains a plurality of metal elements, the above-described metal element concentration means the total concentration with respect to the plurality of metal elements. The metal element concentration of the bath liquid 2 can be measured by ICP-MS analysis.(1.3) Halogen element

[0044] The bath liquid 2 contains at least one or more types of halogen elements. Since the bath liquid 2 contains a halogen element(s), film formation is performed at a practical speed, and the film 3 is likely to become homogeneous. No particular limitation is imposed on the halogen element. From the viewpoints of enabling prompt progress of organic electrochemical reactions and causing the film 3 to function as a high quality protection film for the substrate 5, the halogen element(s) is preferably at least one or more halogen elements selected from the group consisting of Cl (chlorine), Br (bromine), and I (iodine).

[0045] No particular limitation is imposed on the halogen element concentration of the bath liquid 2. From the viewpoints of moderately reducing reaction speed, being advantageous for control of the homogeneity and thickness of the film 3, and preventing separation of the film 3, the halogen element concentration of the bath liquid 2 is preferably 1 ppm or greater and 20000 ppm or less, more preferably 5 ppm or greater and 2000 ppm or less, further preferably 10 ppm or greater and 100 ppm or less. Notably, "ppm" means "parts per million" and "mg / L." The halogen element concentration of the bath liquid 2 can be obtained from the amount of a halogen element(s) added at the time of making-up of the electrolytic bath or by ICP-MS analysis of the bath liquid.(1.4) Organic solvent

[0046] Since an organic solvent is used as the solvent of the bath liquid 2, generation of gas and oxidation of the substrate 5 itself during film formation are suppressed. From the viewpoint of satisfactory formation of the film 3, the solvent preferably contains at least one or more types of solvents selected from the group consisting of ketones and nitriles. In the case where the solvent contains a ketone and / or a nitrile, it is supposed that a condensation reaction occurs on the electrode surface (cathode surface) and electrodeposition becomes possible. Also, in the case where the solvent contains a ketone, conceivably, ketoenol tautomerism occurs in the presence of halogen, and the reactivity of the bath liquid 2 is enhanced.(1.4.1) Ketone

[0047] No particular limitation is imposed on the ketone so long as the ketone is an organic solvent having a carbonyl group (-C(=O)-) other than ester bond.

[0048] Examples of the ketone include acetone, methyl ethyl ketone (MEK), 1-hexanone, 2-hexanone, 4-heptanone, 2-heptanone (methyl amyl ketone), 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, diisobutyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, phenylacetone, acetophenone, methyl naphthyl ketone, cyclohexanone (CHN), and methylcyclohexanone. Among these, acetone and methyl ethyl ketone are preferred, because the film 3 is formed particularly satisfactorily.(1.4.2) Nitrile

[0049] Nitrile is an organic solvent which contains a nitrile group (-CN) in its structure. Examples of the nitrile include acetonitrile, propionitrile, valeronitrile, and butyronitrile. Among these, acetonitrile is preferred, because the film 3 is formed particularly satisfactorily.(2) Substrate 5

[0050] As to the "substrate 5," the description in the column entitled "(1) Substrate 5" in the above-described section entitled "1. Coated substrate 1" is applied as it is.(3) Forming step of forming a film layer (voltage application)

[0051] In the present disclosure, by applying a voltage to the substrate 5 immersed in the bath liquid, a film layer is formed on the substrate 5 on the negative electrode side. Specifically, the positive electrode 6 and the negative electrode 7 (the substrate 5) are immersed in the bath liquid 2, and a potential gradient is generated between the two electrodes.

[0052] Any of known electrically conductive substrates may be used as the positive electrode 6. In the case where the metal element(s) in the bath liquid 2 is supplied as a result of elution of the positive electrode 6, at least one or more types of electrodes selected from an electrode of Al, an electrode of Ti, and an electrode of Mo are preferably used as the positive electrode 6. No particular limitation is imposed on the shape, thickness, size, etc. of the positive electrode 6. The positive electrode 6 may be, for example, foil like, plate like, foam like, nonwoven fabric like, mesh like, felt like, or expanded metal like.

[0053] The positive electrode 6 and the negative electrode 7 are preferably disposed to face each other.

[0054] The positive electrode 6 and the negative electrode 7 are connected to a DC power supply, which can generate a potential gradient between the positive electrode 6 and the negative electrode 7.

[0055] For generation of a potential gradient between the positive electrode 6 and the negative electrode 7, in a state in which the positive electrode 6 and the negative electrode 7 are immersed in the bath liquid 2, a voltage (for example, constant voltage) is applied to the positive electrode 6 and the negative electrode 7 by the power supply connected to the positive electrode 6 and the negative electrode 7.

[0056] From the viewpoint of performing film formation at a practical speed, in the case where a constant voltage is applied, the potential gradient generated between the two electrodes is preferably 10 V or higher and 1000 V or lower, more preferably 20 V or higher and 500 V or lower, further preferably 60 V or higher and 200 V or lower.

[0057] No particular limitation is imposed on an application time during which the volage is applied. The application time is, for example, preferably 10 seconds or longer and 300 seconds or shorter, more preferably 30 seconds or longer and 240 seconds or shorter, further preferably 60 seconds or longer and 180 seconds or shorter.

[0058] Notably, the voltage is not required to be a constant voltage and the magnitude of the voltage may be changed.(4) Drying step of drying the film 3

[0059] No particular limitation is imposed on drying temperature. From the viewpoint of suppressing shrinkage of the entire film 3 after layer formation, by promoting shrinkage of a single layer (each film layer), thereby increasing the resistance of the film 3 to stresses, the drying temperature is preferably 0°C or higher and 1000°C or lower, more preferably 10°C or higher and 500°C or lower, further preferably 80°C or higher and 300°C or lower. No particular limitation is imposed on drying time. From the viewpoint of promoting a dehydration reaction, the drying time is preferably, for example, 1 minute or longer and 3 hours or shorter, more preferably 5 minutes or longer and 2 hours or shorter, further preferably 10 minutes or longer and 1 hour or shorter.(5) Repetition of the set of the forming step and the drying step

[0060] In the case of the first embodiment having a layered structure, the film 3 having a layered structure is formed by repeating at least two times or more the set including the forming step and the drying step. Notably, in the case of the second embodiment having no layered structure, the set including the forming step and the drying step may be performed one time.3. Action and effects of the coated substrate 1 of the present embodiment

[0061] According to the present embodiment, there is provided the novel coated substrate 1 which is applicable to various fields and from which high functionality can be expected.

[0062] According to the present embodiment, it is possible to provide a coated substrate in which internal cracking of the film 3 is suppressed, and adhesion of the film 3 to the substrate 5 is high.

[0063] The coated substrate 1 of the present embodiment can be mass-produced by using a simple process.

[0064] The coated substrate 1 of the present embodiment can be formed without use of an expensive material or by using only a small amount of an expensive material. Therefore, the coated substrate 1 is advantageous in terms of cost.

[0065] Notably, presumably, the film formation mechanism in the present embodiment is as follows. It is presumed that an oxide film formation process occurs. In the oxide film formation process, a condensation reaction occurs at the negative electrode, while the metal element in the solvent is taken in, subsequently, dew condensation occurs on the surface of the substrate 5 due to heat of vaporization at the time of drying, and then hydrolysis occurs, whereby an oxide film is formed. However, this film formation mechanism is a mere conjecture, and the present disclosure is not bounded by this film formation mechanism.EXAMPLES

[0066] The present disclosure will be described further specifically by means of examples.

[0067] Notably, in the following description, measurement conditions of XPS (x-ray photoelectron spectroscopy) are as follows.[Measurement conditions]

[0068] X-ray beam diameter: 100 µmΦ Signal reception angle: 45.0° Path energy: 140 eV Measurement was performed after Ar etching for 30 seconds (etching rate: 10 nm / min corresponding to SiO 2 ). 1. Production of coated substrates

[0069] Experimental examples 1-1, 1-2, 3-1, 3-2, 5-1, and 5-2 are examples. Experimental examples 2-1, 2-2, 4-1, 4-2, 6-1, and 6-2 are examples. (1) Experimental example 1-1

[0070] The film formation apparatus 11 shown in FIG. 2 was used. An aluminum wire was used as the positive electrode 6. A stainless steel plate was used as the negative electrode 7. The negative electrode 7 is a substrate 5 on which a film 3 is to be formed. Acetone was used as the solvent of the bath liquid 2. Iodine (halogen) was dissolved in the bath liquid 2 at a concentration of 600 ppm.

[0071] A set including a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for one minute in a state in which the positive electrode 6 and the negative electrode 7 were immersed in the bath liquid 2 and a drying step of drying the film layer at 100°C for 10 minutes was repeated two times.

[0072] Oservation of a cross section of the negative electrode 7 under an FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure including two layers was formed on the surface of the substrate 5, each film layer (single layer) had a thickness of 100 nm, and the total thickness was 200 nm. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was aluminum oxide.

[0073] The percentage of carbon in the film 3 was 5.8 atm%, and the sum of the percentage of aluminum and the percentage of oxygen was 93.9 atm%.

[0074] The percentage of iodine in this film 3 was 0.1 atm%.

[0075] Since no diffraction pattern was observed by the TEM electron diffraction method performed for a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0076] The relative density of the film 3 determined by the following method was 100%.

[0077] Specifically, the relative density of the film 3 was determined as follows. A TEM image was obtained from a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction. The area of pores was measured in a field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension). The relative density (%) was obtained in accordance with the following expression (1). The average of the relative densities of 10 fields of view is the relative density of the film 3. Notably, in the case where the thickness of the film 3 is smaller than the vertical size of 300 nm, measurement is performed in fields of view determined in accordance with the thickness of the film 3. Relative density % = S 1 − S 2 / S 1 × 100 (In the expression, S1 is the area (nm 2< ) of the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension), and S2 is the total area (nm 2< ) of pores in the field of view of 300 nm (vertical dimension) × 1000 nm (horizontal dimension))(2) Experimental example 1-2

[0078] The film formation apparatus 11 shown in FIG. 2 was used. A magnesium wire was used as the positive electrode 6. A stainless steel plate was used as the negative electrode 7. The negative electrode 7 is a substrate 5 on which a film 3 is to be formed. Acetone was used as the solvent of the bath liquid 2. Iodine (halogen) was dissolved in the bath liquid 2 at a concentration of 600 ppm.

[0079] A set including a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for one minute in a state in which the positive electrode 6 and the negative electrode 7 were immersed in the bath liquid 2 and a drying step of drying the film layer at 100°C for 10 minutes was repeated two times.

[0080] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure including two layers was formed on the surface of the substrate 5, each film layer (single layer) had a thickness of 100 nm, and the total thickness was 200 nm. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was magnesium oxide.

[0081] The percentage of carbon in the film 3 was 7.6 atm%, and the sum of the percentage of magnesium and the percentage of oxygen was 91.6 atm%.

[0082] The percentage of iodine in this film 3 was 0.1 atm%.

[0083] Since no diffraction pattern was observed by the TEM electron diffraction method performed for a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0084] The relative density of the film 3 determined by the above-described method was 100%.(3) Experimental example 2-1

[0085] The film formation apparatus 11 shown in FIG. 2 was used. An aluminum wire was used as the positive electrode 6. A stainless steel plate was used as the negative electrode 7. The negative electrode 7 is a substrate 5 on which a film 3 is to be formed. Acetone was used as the solvent of the bath liquid 2. Iodine (halogen) was dissolved in the bath liquid 2 at a concentration of 600 ppm.

[0086] A set including a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for two minutes in a state in which the positive electrode 6 and the negative electrode 7 were immersed in the bath liquid 2 and a drying step of drying the film layer at 80°C for 10 minutes was performed one time.

[0087] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a mono-layer (single layer) structure having a thickness of 200 nm was formed on the surface of the substrate 5. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was aluminum oxide.

[0088] The percentage of carbon in the film 3 was 6 atm%, and the sum of the percentage of aluminum and the percentage of oxygen was 90 atm%.

[0089] The percentage of iodine in this film 3 was 0.1 atm%.

[0090] Since no diffraction pattern was observed by the TEM electron diffraction method performed for a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0091] The relative density of the film 3 determined by the above-described method was 100%.(4) Experimental example 2-2

[0092] The film formation apparatus 11 shown in FIG. 2 was used. A magnesium wire was used as the positive electrode 6. A stainless steel plate was used as the negative electrode 7. The negative electrode 7 is a substrate 5 on which a film 3 is to be formed. Acetone was used as the solvent of the bath liquid 2. Iodine (halogen) was dissolved in the bath liquid 2 at a concentration of 600 ppm.

[0093] A set including a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for two minutes in a state in which the positive electrode 6 and the negative electrode 7 were immersed in the bath liquid 2 and a drying step of drying the film layer at 80°C for 10 minutes was performed one time.

[0094] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure including two layers was formed on the surface of the substrate 5, each film layer (single layer) had a thickness of 100 nm, and the total thickness was 200 nm. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was magnesium oxide.

[0095] The percentage of carbon in the film 3 was 9.9 atm%, and the sum of the percentage of magnesium and the percentage of oxygen was 89.7 atm%.

[0096] The percentage of iodine in this film 3 was 0.1 atm%.

[0097] Since no diffraction pattern was observed by the TEM electron diffraction method performed for a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0098] The relative density of the film 3 determined by the above-described method was 100%.(5) Experimental example 3-1

[0099] An experiment was performed in the same manner as in Experimental example 1 except that a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for one minute and a drying step of drying the film layer at 80°C for 10 minutes were repeated five times.

[0100] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure including five layers was formed on the surface of the substrate 5, each film layer (single layer) had a thickness of 100 nm, and the total thickness was 500 nm. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was aluminum oxide.

[0101] The percentage of carbon in the film 3 was 6 atm%, and the sum of the percentage of aluminum and the percentage of oxygen was 90 atm%.

[0102] The percentage of iodine in this film 3 was 0.1 atm%.

[0103] Since no diffraction pattern was observed by the TEM electron diffraction method performed for a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0104] The relative density of the film 3 determined by the above-described method was 100%.(6) Experimental example 3-2

[0105] An experiment was performed in the same manner as in Experimental example 1-2 except that a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for one minute and a drying step of drying the film layer at 80°C for 10 minutes were repeated five times.

[0106] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure including five layers was formed on the surface of the substrate 5, each film layer (single layer) had a thickness of 100 nm, and the total thickness was 500 nm. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was magnesium oxide.

[0107] The percentage of carbon in the film 3 was 8.9 atm%, and the sum of the percentage of magnesium and the percentage of oxygen was 90 atm%.

[0108] The percentage of iodine in this film 3 was 0.1 atm%.

[0109] Since no diffraction pattern was observed by the TEM electron diffraction method performed for a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0110] The relative density of the film 3 determined by the above-described method was 100%.(7) Experimental example 4-1

[0111] An experiment was performed in the same manner as in Experimental example 2 except that a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for five minutes and a drying step of drying the film layer at 80°C for 10 minutes were performed one time.

[0112] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a mono-layer (single layer) structure having a thickness of 500 nm was formed on the surface of the substrate 5. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was aluminum oxide.

[0113] The percentage of carbon in the film 3 was 6 atm%, and the sum of the percentage of aluminum and the percentage of oxygen was 90 atm%.

[0114] The percentage of iodine in this film 3 was 0.1 atm%.

[0115] Since no diffraction pattern was observed by the TEM electron diffraction method performed for a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0116] The relative density of the film 3 determined by the above-described method was 100%.(8) Experimental example 4-2

[0117] An experiment was performed in the same manner as in Experimental example 2-2 except that a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for five minutes and a drying step of drying the film layer at 80°C for 10 minutes were performed one time.

[0118] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a mono-layer (single layer) structure having a thickness of 500 nm was formed on the surface of the substrate 5. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was magnesium oxide.

[0119] The percentage of carbon in the film 3 was 8.9 atm%, and the sum of the percentage of magnesium and the percentage of oxygen was 90 atm%.

[0120] The percentage of iodine in this film 3 was 0.1 atm%.

[0121] Since no crystal grain was observed in a TEM image of a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0122] The relative density of the film 3 determined by the above-described method was 100%.(9) Experimental example 5-1

[0123] An experiment was performed in the same manner as in Experimental example 1 except that a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for one minute and a drying step of drying the film layer at 80°C for 10 minutes were repeated 20 times.

[0124] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure including 20 layers was formed on the surface of the substrate 5, each film layer (single layer) had a thickness of 100 nm, and the total thickness was 2000 nm. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was aluminum oxide.

[0125] The percentage of carbon in the film 3 was 6 atm%, and the sum of the percentage of aluminum and the percentage of oxygen was 90 atm%.

[0126] The percentage of iodine in this film 3 was 0.1 atm%.

[0127] Since no crystal grain was observed in a TEM image of a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0128] The relative density of the film 3 determined by the above-described method was 100%.(10) Experimental example 5-2

[0129] An experiment was performed in the same manner as in Experimental example 1-2 except that a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for one minute and a drying step of drying the film layer at 80°C for 10 minutes were repeated 20 times.

[0130] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a layered structure including 20 layers was formed on the surface of the substrate 5, each film layer (single layer) had a thickness of 100 nm, and the total thickness was 2000 nm. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was magnesium oxide.

[0131] The percentage of carbon in the film 3 was 8.9 atm%, and the sum of the percentage of magnesium and the percentage of oxygen was 90 atm%.

[0132] The percentage of iodine in this film 3 was 0.1 atm%.

[0133] Since no crystal grain was observed in a TEM image of a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0134] The relative density of the film 3 determined by the above-described method was 100%.(11) Experimental example 6-1

[0135] An experiment was performed in the same manner as in Experimental example 2 except that a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for 20 minutes and a drying step of drying the film layer at 80°C for 10 minutes were performed one time.

[0136] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a mono-layer (single layer) structure having a thickness of 2000 nm was formed on the surface of the substrate 5. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was aluminum oxide.

[0137] The percentage of carbon in the film 3 was 6 atm%, and the sum of the percentage of aluminum and the percentage of oxygen was 90 atm%.

[0138] The percentage of iodine in this film 3 was 0.1 atm%.

[0139] Since no diffraction pattern was observed by the TEM electron diffraction method performed for a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0140] The relative density of the film 3 determined by the above-described method was 100%.(12) Experimental example 6-2

[0141] An experiment was performed in the same manner as in Experimental example 2-2 except that a film layer forming step of applying a voltage of 80 V between the positive electrode 6 and the negative electrode 7 for 20 minutes and a drying step of drying the film layer at 80°C for 10 minutes were performed one time.

[0142] Oservation of a cross section of the negative electrode 7 under the FIB-SEM (focused ion beam scanning electron microscope) revealed that a film 3 having a mono-layer (single layer) structure having a thickness of 2000 nm was formed on the surface of the substrate 5. Analysis performed by XPS after Ar etching for 30 seconds revealed that the film 3 was magnesium oxide.

[0143] The percentage of carbon in the film 3 was 8.9 atm%, and the sum of the percentage of magnesium and the percentage of oxygen was 90 atm%.

[0144] The percentage of iodine in this film 3 was 0.1 atm%.

[0145] Since no crystal grain was observed in a TEM image of a cross section of the film 3 obtained by cutting the film 3 in the film-thickness direction, it was confirmed that the film 3 was amorphous.

[0146] The relative density of the film 3 determined by the above-described method was 100%.(13) Analysis of films 3 by XPS

[0147] The films 3 produced in Experimental examples 1-1, 1-2, 3-1, 3-2, 5-1, 5-2, 2-1, 2-2, 4-1, 4-2, 6-1, and 6-2 were analyzed by XPS. In each of the films 3, C=O and C-O bonds were detected.2. Evaluation(1) Evaluation method

[0148] For the coated substrate of each experimental example, surface observation by an optical microscope and cross-section observation by an FIB-SEM were performed. By these observations, presence / absence of a crack extending from the surface of the film 3 and reaching the substrate was investigated.

[0149] In addition, after drying the coated substrate of each experimental example in a vacuum (under reduced pressure) at room temperature, its surface was observed under the optical microscope, and its cross section was observed under the FIB-SEM. By these observations, presence / absence of a crack extending from the surface of the film 3 and reaching the substrate was investigated.

[0150] In addition, after heat-treating the coated substrate of each experimental example at 500°C in the atmosphere, its surface was observed under the optical microscope, and its cross section was observed under the FIB-SEM. By these observations, presence / absence of a crack extending from the surface of the film 3 and reaching the substrate was investigated.(2) Evaluation results

[0151] The evaluation results are shown in Table 1.

[0152] In Experimental examples 1-1, 1-2, 3-1, 3-2, 5-1, and 5-2, no crack was formed even after the film formation, after the reduced-pressure drying, or after the heat treatment.

[0153] In Experimental examples 2-1, 2-2, 4-1, and 4-2, no crack was formed after the film formation. In Experimental examples 2-1, 2-2, 4-1, and 4-2, a crack was found after the reduced-pressure drying or after the heat treatment.

[0154] In Experimental examples 6-1 and 6-2, a crack was found after the film formation, after the reduced-pressure drying, or after the heat treatment. Table 1Experimental exampleFilm thickness (nm)Thickness of single layer (nm)Number of layersPresence / absence of crack after film formationPresence / absence of crack after reduced-pressure dryingPresence / absence of crack after 500°C heat treatment1-12001002AbsentAbsentAbsent1-22001002AbsentAbsentAbsent2-12002001AbsentPresentPresent2-22002001AbsentPresentPresent3-15001005AbsentAbsentAbsent3-25001005AbsentAbsentAbsent4-15005001AbsentPresentPresent4-25005001AbsentPresentPresent5-1200010020AbsentAbsentAbsent5-2200010020AbsentAbsentAbsent6-1200020001PresentPresentPresent6-2200020001PresentPresentPresent 3. Effect of Examples

[0155] According to the present examples, novel coated substrates 1 which are applicable to various fields and from which high functionality can be expected are provided.

[0156] The present invention is not limited to the embodiments described in detail above and various modifications and changes are possible within the range shown in the claims of the present invention.(Additional note)

[0157] The following inventions are contained in the present specification. [1] A coated substrate in which a substrate is coated with a film, wherein the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 70 atm% or greater, the film is amorphous, the relative density of the film is 90% or greater, and the film has a layered structure as a cross-sectional form. [2] The coated substrate recited in [1], wherein a portion of the substrate where the film is formed is electrically conductive. [3] The coated substrate recited in [1] or [2], wherein each layer of the layered structure has a thickness of 20 nm or greater and 500 nm or less. [4] The coated substrate recited in [1] to [3], wherein the metal element is at least one or more types of metals selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), Mn (manganese), and Mg (magnesium). [5] The coated substrate recited in [1] to [4], wherein the film contains a compound having at least one type of structure selected from C-H, C=O, and C-O bonds. [6] The coated substrate recited in [1] to [5], wherein, in the film, the percentage of a halogen element is 0.1 atm% or greater. [7] A method for producing a coated substrate by using a bath liquid containing an organic solvent, wherein the water content of the bath liquid is less than 5 mass% and the bath liquid contains at least one or more types of metal elements and at least one or more types of halogen elements, the method comprises a forming step of forming a film layer containing the metal element on the substrate on a negative electrode side by applying a voltage in a state in which the substrate is immersed in the bath liquid, and a drying step of drying the film layer, and a set including the forming step and the drying step is repeated at least two times or more. thereby forming a film having a layered structure. [8] A coated substrate in which a substrate is coated with a film, wherein the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 70 atm% or greater, the film is amorphous, and the relative density of the film is 90% or greater. REFERENCE SIGNS LIST

[0158] 1: coated substrate 2: bath liquid 3: film 5: substrate 6: positive electrode 7: negative electrode 11: film formation apparatus

Claims

1. A coated substrate in which a substrate is coated with a film, wherein the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 70 atm% or greater, the film is amorphous, the relative density of the film is 90% or greater, and the film has a layered structure as a cross-sectional form.

2. The coated substrate according to claim 1, wherein a portion of the substrate where the film is formed is electrically conductive.

3. The coated substrate according to claim 1 or 2, wherein each layer of the layered structure has a thickness of 20 nm or greater and 500 nm or less.

4. The coated substrate according to claim 1 or 2, wherein the metal element is at least one or more types of metals selected from the group consisting of Al (aluminum), Ti (titanium), Zr (zirconium), Mo (molybdenum), W (tungsten), V (vanadium), Fe (iron), Cr (chromium), Co (cobalt), Mn (manganese), and Mg (magnesium).

5. The coated substrate according to claim 1 or 2, wherein the film contains a compound having at least one type of structure selected from C-H, C=O, and C-O bonds.

6. The coated substrate according to claim 1 or 2, wherein, in the film, the percentage of a halogen element is 0.1 atm% or greater.

7. A method for producing a coated substrate by using a bath liquid containing an organic solvent, wherein the water content of the bath liquid is less than 5 mass% and the bath liquid contains at least one or more types of metal elements and at least one or more types of halogen elements, the method comprises a forming step of forming a film layer containing the metal element on the substrate on a negative electrode side by applying a voltage in a state in which the substrate is immersed in the bath liquid, and a drying step of drying the film layer, and a set including the forming step and the drying step is repeated at least two times or more, thereby forming a film having a layered structure.

8. A coated substrate in which a substrate is coated with a film, wherein the thickness of the film is 60 nm or greater and 10 µm or less, measurement of the film shows that the percentage of C (carbon) element is 0.1 atm% or greater and less than 20 atm%, and the sum of the percentage of a metal element and the percentage of O (oxygen) element is 70 atm% or greater, the film is amorphous, and the relative density of the film is 90% or greater.

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