Metal oxide film, metal oxide laminate, and method for producing metal oxide laminate

Abstract

Provided is an amorphous metal oxide film represented by the compositional formula SiaAlbOcTd (in the formula, Si represents a silicon atom, Al represents an aluminum atom, O represents an oxygen atom, and T represents one or more atoms other than Si, Al, and O, a, b, c, and d represent a weight ratio, a + b + c + d = 100, a is 3-45, b is 5-50, c is 35-60, and d represents a weight ratio, b is 5-50, and c is 5-60. And d is 0.05 to 10 inclusive, and the thickness of the metal oxide film is 0.1 [mu] m to 30 [mu] m inclusive. This metal oxide film makes it possible to obtain a metal oxide laminate having excellent adhesion, heat dissipation, insulating properties, and high voltage resistance.

Description

Technical Field

[0001] The present invention relates to a metal oxide film, a metal oxide laminate, and a method for manufacturing a metal oxide laminate. Background Art

[0002] In the past, in order to release heat generated by electronic components such as semiconductor chips or antennas to the outside of the system, a metallic heat dissipation member was used. Among these heat dissipation members, there is a heat dissipation circuit board provided with an insulating layer to prevent energization. However, due to the recent increase in power, typified by electric vehicles, the heat dissipation members are increasingly used at high temperatures. Therefore, alumina or the like having excellent heat resistance, strength, and insulation is used in the insulating material.

[0003] Patent Document 1 proposes a substrate (CBC substrate: Ceramic Bonding Cupper) formed by directly bonding and laminating a zirconia toughened alumina plate (ZTA) as an insulating layer and a foil-shaped copper plate.

[0004] Non-Patent Document 1 proposes a method for forming an insulating film of alumina on a silicon wafer. Non-Patent Document 2 describes that an aluminosilicate film having higher insulation than alumina is obtained by doping silicon into alumina.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 1996-195450

[0008] Non-Patent Documents

[0009] Non-Patent Document 1: Journal of the Society of Material Science, Japan 2013 Vol.62, No.11, pp 663~667

[0010] Non-Patent Document 2: Electrical Engineering C 2007, Vol. 127, No. 11, pp1822~1825 Summary of the Invention

[0011] (I) Technical Problems to be Solved

[0012] However, since the substrate described in Patent Document 1 is made by a hot pressing method, it is impossible to make a thin film, and the insulating layer needs to be made 150 μm or more, resulting in a problem of insufficient heat dissipation. Further, since the thermal expansion coefficients of the metal material and the ceramic are significantly different, there is a problem that the ceramic cannot completely absorb the internal stress due to temperature changes, and cracks appear in the ceramic or the ceramic peels off. In addition, from the perspective of withstand voltage, the alumina film obtained by the method described in Non-Patent Document 1 still has room for improvement. When forming the aluminosilicate film described in Non-Patent Document 2 on a substrate with a high coefficient of thermal expansion, there is a problem that the ceramic cannot completely absorb the internal stress due to temperature changes, and cracks appear in the ceramic or peeling occurs.

[0013] The present invention has been completed in view of the above circumstances, and an object thereof is to provide a metal oxide film capable of obtaining a metal oxide laminate excellent in adhesion, heat dissipation, insulation, and high withstand voltage. Further, an object thereof is to provide a metal oxide laminate of the metal oxide film and a method for manufacturing the metal oxide laminate.

[0014] (II) Technical Solution

[0015] That is, the present invention relates to a metal oxide film, which is an amorphous metal oxide film, and the metal oxide film is represented by the compositional formula: SiaAlbOcTd. In the formula, Si represents a silicon atom, Al represents an aluminum atom, O represents an oxygen atom, and T represents one or more atoms other than Si, Al, and O. a, b, c, and d represent weight ratios, a + b + c + d = 100, a is 3 or more and 45 or less, b is 5 or more and 50 or less, c is 35 or more and 60 or less, and d is 0.05 or more and 10 or less. The thickness of the metal oxide film is 0.1 μm or more and 30 μm or less.

[0016] In addition, the present invention relates to a metal oxide laminate formed by directly laminating the metal oxide film on a sheet-like metal material having a thickness of 0.2 mm or more and 20 mm or less.

[0017] In addition, as a preferred form of the metal oxide laminate of the present invention, the metal material may be copper or a copper alloy, or aluminum or an aluminum alloy.

[0018] In addition, the present invention relates to a method for manufacturing a metal oxide laminate, which includes the following steps: a step of atomizing or dropletizing a coating liquid containing a silicon compound and a salt or complex of aluminum using a carrier gas to obtain a mist or droplets; and a step of reacting the mist or droplets on a metal material in a temperature atmosphere of 150 °C or more and 450 °C or less to obtain a metal oxide film.

[0019] (III) Advantageous Effects

[0020] Since the metal oxide film of the present invention is an extremely thin film of 0.1 μm or more and 30 μm or less and is a metal oxide film with high insulation, a metal oxide laminate capable of achieving both high heat dissipation and insulation can be obtained. Further, since the metal oxide film is amorphous and contains aluminum and silicon in an appropriate ratio, a metal oxide laminate having excellent adhesion, heat dissipation, insulation, and high voltage resistance and not generating cracks even after a thermal cycle test can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a film forming apparatus for a metal oxide film according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] <Metal Oxide Film>

[0023] The metal oxide film of the present invention is amorphous and is represented by the compositional formula: SiaAlbOcTd, where Si represents a silicon atom, Al represents an aluminum atom, O represents an oxygen atom, and T represents one or more atoms other than Si, Al, and O. a, b, c, and d represent weight ratios, a + b + c + d = 100, a is 3 or more and 45 or less, b is 5 or more and 50 or less, c is 35 or more and 60 or less, and d is 0.05 or more and 10 or less. The thickness of the metal oxide film is 0.1 μm or more and 30 μm or less.

[0024] From the perspective of high voltage resistance, in the above compositional formula, a is preferably 5 or more, more preferably 10 or more. And from the perspective of adhesion, a is preferably 40 or less, more preferably 33 or less. From the perspective of adhesion, b is preferably 8 or more, more preferably 10 or more. And from the perspective of high voltage resistance, b is preferably 40 or less, more preferably 37 or less. From the perspective of high voltage resistance, c is preferably 40 or more, more preferably 44 or more, and preferably 55 or less, more preferably 52 or less. From the perspective of preventing the metal oxide film from hardening and the metal oxide film layer from being easily broken when heated or strained, d is preferably 0.1 or more, more preferably 0.2 or more. And from the perspective of improving insulation, d is preferably 8 or less, more preferably 5 or less. That is, a is preferably 5 or more and 40 or less, b is preferably 8 or more and 40 or less, c is preferably 40 or more and 55 or less, and d is preferably 0.1 or more and 8 or less. More preferably, a is 10 or more and 33 or less, b is 10 or more and 37 or less, c is 44 or more and 52 or less, and d is 0.2 or more and 5 or less. In addition, the above composition ratio can be obtained by Dynamic Secondary Ion Mass Spectrometry (Dynamic SIMS).

[0025] In the above compositional formula, from the viewpoints of preventing the hardening of the metal oxide film, improving the adhesion and flexibility during thermal cycling tests, and preventing cracks, d preferably contains carbon atoms.

[0026] The thickness of the metal oxide film is 0.1 μm or more and 30 μm or less, preferably 0.8 μm or more and 20 μm or less. If the thickness is 0.1 μm or more and 30 μm or less, the insulation property, high voltage resistance property, and heat dissipation property are good, and even when heated to 100 °C or higher, cracks are not likely to occur in the metal oxide film. In addition, by making the metal oxide film amorphous, flexibility is imparted to the metal oxide film, so the adhesion at high temperature is excellent and cracks are not likely to occur during thermal cycling tests.

[0027] <Metal Oxide Laminate>

[0028] The metal oxide laminate of the present invention is formed by directly laminating the metal oxide film on a sheet-like metal material having a thickness of 0.2 mm or more and 20 mm or less. In addition, the direct lamination in the present invention means that there is no layer of 100 nm or more between the metal oxide film and the metal material.

[0029] From the viewpoint of heat dissipation, the metal material is preferably a material having a high thermal conductivity. Among them, the material is more preferably copper or a copper alloy, or aluminum or an aluminum alloy. Further, when the metal material contains copper atoms or aluminum atoms, at the interface with the metal oxide film, aluminum atoms or silicon atoms in the metal oxide film are directly bonded or bonded via oxygen atoms to aluminum atoms or copper atoms in the metal material, whereby the metal material and the metal oxide film can have high adhesion and higher thermal cycling resistance can be obtained.

[0030] The copper or copper alloy, or aluminum or aluminum alloy can be a known metal or alloy. As the copper or copper alloy, for example, a compound having a compositional formula of CuxMyTz can be cited, where Cu represents copper atoms, M represents chromium, beryllium, molybdenum, nitrogen, or phosphorus atoms, T represents one or more atoms other than Cu and M; x, y, and z represent weight ratios, preferably x + y + z = 100, x is preferably 60 or more and 100 or less, y is preferably 0 or more and 40 or less, and z is preferably 0 or more and 5 or less. Here, it is preferred that there are more copper atoms in the metal material, and when high adhesion is required, x is more preferably 80 or more and 100 or less.

[0031] In addition, examples of the aluminum or aluminum alloy include compounds with the compositional formula AlxMyTz, where Al represents aluminum atoms, M represents copper and magnesium atoms, and T represents one or more atoms other than Al and M; x, y, and z represent weight ratios, x + y + z = 100, x is preferably 80 or more and 100 or less, y is preferably 0 or more and 20 or less, and z is preferably 0 or more and 3 or less. Here, it is preferred that there are more aluminum atoms in the metal material, and when high adhesion is required, x is more preferably 90 or more and 100 or less.

[0032] The compounds represented by the above compositional formulas have high thermal conductivity and are more suitable as heat dissipation components.

[0033] The metal material is in the form of a sheet with a thickness of 0.2 mm or more and 20 mm or less, preferably 0.5 mm or more and 20 mm or less. When the thickness of the metal material is less than 0.2 mm, the heat dissipation performance is insufficient, and if it is greater than 20 mm, it will cause inconvenience in the installation process when used as a heat dissipation circuit board.

[0034] <Manufacturing method of metal oxide laminate>

[0035] In the metal oxide laminate, the method for forming the metal oxide film is not particularly limited. For example, physical vapor deposition methods such as vacuum evaporation, ion plating, and sputtering can be preferably cited; chemical vapor deposition methods such as plasma CVD, atomic layer deposition (ALD), metal organic compound CVD, and aerosol CVD; coating methods such as spraying, inkjet, spin coating, and dip coating in which a coating liquid reacts on the metal material. Among them, due to excellent film formation speed and film thickness uniformity of the film formation, chemical vapor deposition methods and coating methods are preferred.

[0036] In the chemical vapor deposition method and the coating method, by heating and reacting a coating liquid containing an aluminum salt or complex and a silicon compound on the metal material in a temperature atmosphere of 150 °C or more and 450 °C or less, a metal oxide film is formed. Thus, the metal atoms in the metal material are directly bonded to the aluminum atoms or silicon atoms in the metal oxide film or bonded via an oxygen bond, so the adhesion on the surface is increased, and thus it is preferred. If the film formation temperature exceeds 450 °C, the thermal load on the metal material is large, the dimensional stability of the obtained laminate becomes poor, and the difference in thermal expansion coefficients between the metal material and the metal oxide film is large. Therefore, when returning to room temperature after film formation, cracks may sometimes appear in the metal oxide film or warping may occur. In addition, when using a substrate with a particularly high thermal expansion coefficient such as copper or a copper alloy, or aluminum or an aluminum alloy in the metal material, in order to prevent warping caused by the difference in thermal expansion coefficients between the metal material and the metal oxide, the film formation temperature is preferably 370 °C or less, more preferably 350 °C or less.

[0037] Particularly when a coating solution is subjected to a heating reaction on a metal material, it is most preferable to: carry out a step of transporting fog or droplets obtained by atomizing or nebulizing the coating solution onto the metal material by using a carrier gas such as nitrogen, and subject the fog or droplets to a heating reaction on the metal material set at a temperature of 150°C or higher and 450°C or lower, thereby forming a film (abbreviated as mCVD). This method is a type of chemical vapor deposition method. Thus, by forming fine droplets from a coating solution containing a salt or complex of aluminum and a silicon compound and reacting them, a metal oxide with a thin film thickness, amorphous, and in which Si and Al are uniformly dispersed can be obtained. In addition, with this method, since the reactivity of the salt or complex of aluminum and the silicon compound in the coating solution increases due to atomization or nebulization, a metal oxide can be obtained at a temperature of 150°C or higher and 450°C or lower, and thus film formation can be carried out without deteriorating the metal material. Further, by using the mCVD method to carry out film formation in a temperature range of 150°C or higher and 450°C or lower, the carbon atom content of the metal oxide can be controlled within the range of 0.1 to 5% by weight. As mCVD and its apparatus, for example, refer to Japanese Patent Laid-Open No. 2018-140352, Japanese Patent Laid-Open No. 2018-172793, etc.

[0038] The coating solution preferably contains: a combination of 0.2% by weight or more and 20% by weight or less of an aluminum complex or salt and 0.2% by weight or more and 20% by weight or less of a silicon compound; or a compound containing silicon and aluminum elements in one molecule in an amount of 0.2% by weight or more and 20% by weight or less. If the aluminum complex or salt and the silicon compound are less than 0.2% by weight, the film formation time becomes long, and if they are more than 20% by weight, the carbon content increases, which causes a decrease in insulation. In addition, as the silicon compound, any compound that can be atomized or nebulized may be used, and examples include silane, siloxane, silazane, polysilazane, alkoxysilane, etc.

[0039] In the above mCVD, as the oxygen source, oxidizing agents such as ozone, oxygen, and hydrogen peroxide can be used, and ozone is more preferable. In addition, in order to prevent ignition of the atomized coating solution, water, alcohol, etc. can also be used as the oxygen source. Here, the oxygen source refers to a source for supplying oxygen atoms for forming a metal oxide from an aluminum complex or salt and a silicon compound.

[0040] Thus, by forming fine fog or droplets from a coating solution containing an aluminum complex or salt and a silicon compound and reacting them on a metal material, it is also possible to fill the surface irregularities of the metal material.

[0041] By directly laminating the metal material on one surface of the metal oxide film and providing a conductive metal layer on the other surface of the metal oxide film, the metal oxide laminate can be used as a heat dissipation circuit board. In addition, such a heat dissipation circuit board can be used as a heat dissipation member.

[0042] Example

[0043] Hereinafter, the present invention will be described by way of examples and the like, but the present invention is not limited thereto.

[0044] <Manufacturing Example>

[0045] <Preparation of Coating Liquid>

[0046] <Example 1>

[0047] <Formation of Metal Oxide Film>

[0048] Use Figure 1The film-forming apparatus (mCVD apparatus) shown below forms a metal oxide film on a metal material by the following method. Using an O-ring and a caulking agent, a polyethylene film is fixed at a position 1 cm from the bottom of a glass cylinder (diameter: 13 cm, height: 15 cm). A Teflon (registered trademark)-made lid is provided at the upper part of the cylinder, and two holes are opened in the lid. A glass pipe for supplying nitrogen and a glass pipe with a branch for transporting mist are inserted. The glass pipe with a branch for transporting mist is set at a position 1 to 2 cm from the metal material on the heating plate, and an ozone generation device is connected to the branch using a Teflon pipe so as to be able to introduce ozone-oxygen. The cylinder is immersed in a water bath, and an ultrasonic oscillator (ultrasonic atomization unit HMC-2401; manufactured by Honda Electronics Co., Ltd.) is provided directly below the polypropylene. The heating plate is placed in a box filled with nitrogen, and film formation is started after the oxygen concentration becomes 1% or less. The above coating solution is added to the cylinder, the ultrasonic oscillator is started, and ultrasonic waves are transmitted to the coating solution through the water in the water bath and the polypropylene, atomizing a part of the coating solution. The atomized coating solution is transported onto the metal material (30 mm × 30 mm) using nitrogen. The metal material is heated using the heating plate. After confirming that the atomized coating solution has reached the metal material, ozone is supplied to cause a chemical reaction to form a metal oxide layer, obtaining a laminate. In addition, the film thickness of the metal oxide layer is adjusted by the film formation time (the time when the atomized coating solution is sprayed onto the metal material), and is measured by the following method. The nitrogen flow rate is set to 11 L / minute, the ozone concentration in ozone-oxygen is set to 5000 ppm, the ozone-oxygen flow rate is set to 1 L / minute, the vibration frequency of the ultrasonic oscillator is set to 2.4 MHz, the voltage is set to 24 V, and the current is set to 0.6 A. In addition, the conditions such as the metal material, coating solution, and heating plate temperature used are shown in Table 1.

[0049] <Measurement of the film thickness of the metal oxide film>

[0050] Regarding the measurement of the film thickness of the metal oxide film, a metal oxide film is formed on a silicon wafer instead of the above metal material, and measurement is performed using a surface profiler (Dektak XT-S: manufactured by Bruker Japan K.K.).

[0051] <Measurement of the composition of the metal oxide film>

[0052] By dynamic secondary ion mass spectrometry (PHI ADEPT: manufactured by ULVAC-PHI, INCORPORATED.), the weight per unit volume of aluminum atoms, silicon atoms, oxygen atoms, and carbon atoms and their ratios are calculated. The conditions of dynamic secondary ion mass spectrometry are shown below. Primary ion species: Cs+, primary acceleration voltage: 5.0 kV, detection area: 45×45 μm. As a sample, a sample with a 1-μm metal oxide film formed on a copper substrate is prepared. The center of the sample is measured in the depth direction, and the depth of the point where silicon is detected is defined as 1 μm. The weight ratios of the four atoms are calculated based on the secondary ion intensities, relative sensitivity coefficients, and atomic weights of aluminum atoms, silicon atoms, oxygen atoms, and carbon atoms respectively. Since the difference between the total value of the weights of the four atoms per unit volume and the specific gravity of the metal oxide film is less than 1%, it is considered that the metal oxide film is mainly composed of the four atoms, and the weight ratio per unit volume of the four atoms is calculated as the composition ratio.

[0053] Using the laminate obtained above, the following evaluations are carried out.

[0054] <Confirmation of Amorphousness>

[0055] An X-ray diffractometer (SmartLab: manufactured by Rigaku Corporation) is used to confirm the amorphousness of the metal oxide film. As samples, a silicon wafer and a sample with a 1-μm metal oxide film formed on the silicon wafer are prepared, and measurements are carried out under the following conditions. Compared with the silicon wafer, the case where no new diffraction peak appears is regarded as amorphous, and the case where a new diffraction peak appears is regarded as crystalline.

[0056] Tube voltage: 45 kV

[0057] Tube current: 200 mA

[0058] X-ray wavelength: Cu-Kα ray (1.5418 Å)

[0059] Detector: D / teX Ultra 250

[0060] Measurement range: 2θ = ω scan

[0061] Scan axis: 2θ / θ

[0062] Long side limit slit width: 2.0 mm

[0063] Scan mode: continuous (CONTINUOUS)

[0064] Scan speed: 20° / minute

[0065] <Evaluation of Adhesion>

[0066] The airtightness is evaluated by checking for cracks or peeling between the metal material and the metal oxide after the thermal cycle test. Specifically, using a TSA-103ES-W thermal cycle tester manufactured by ESPEC CORP., a 30 mm × 30 mm laminate is subjected to 200 thermal cycle tests with one cycle consisting of 35 minutes at -40°C and 35 minutes at 200°C. An optical microscope is used to observe the laminate at a magnification of 50 times. The presence of peeling or cracks is evaluated as ×. Then, the magnification of the optical microscope is increased to 150 times for observation. The presence of peeling is evaluated as △, and the absence of peeling is evaluated as 〇. Further, a scanning microscope (IT-200, manufactured by JEOL Ltd.) is used to observe at a magnification of 1000 times, and the absence of cracks is evaluated as ◎.

[0067] <Evaluation of insulation property>

[0068] Using silver paste (DOTITE FA-451a; manufactured by FUJIKURA KASEI CO., LTD.), a circular main electrode with a diameter of 10 mm as the conductive metal layer is formed on the metal oxide film of the 30 mm × 30 mm laminate. Using an insulation resistance meter (SM-7120 high resistance meter, manufactured by HIOKI E.E. CORPORATION), a DC voltage of 10 V is applied between the metal material and the main electrode, and the current is measured to determine the volume resistivity. A volume resistivity of 2000 GΩ·cm or more is evaluated as ◎, a volume resistivity of 1000 GΩ·cm or more and less than 2000 GΩ·cm is evaluated as 〇, and a volume resistivity less than 1000 GΩ·cm is evaluated as ×.

[0069] <Evaluation of high voltage resistance>

[0070] Using silver paste (DOTITE FA-451a; manufactured by FUJIKURA KASEI CO., LTD.), a circular main electrode with a diameter of 10 mm as the conductive metal layer is formed on the metal oxide film of the 30 mm × 30 mm laminate. Using an insulation resistance meter (SM-7120 high resistance meter, manufactured by HIOKI E.E. CORPORATION), a DC voltage is applied between the metal material and the main electrode at a voltage increase rate of 10 V / s, and the current is measured. The evaluation is based on the voltage (dielectric breakdown voltage (V)) when a current of 2 mA or more flows through. A value of 500 V or more is considered qualified.

[0071] <Evaluation of heat dissipation (thermal conductivity)>

[0072] In a dry glove box purged with nitrogen from a high-pressure cylinder, 10 undeliquesced ammonium acetate particles with a particle size of 1 mm or less (melting point: 112 °C, manufactured by FUJIFILM Wako Pure Chemical Corporation) were placed on the metal oxide film of a 30 mm × 30 mm laminate with the metal material facing down, and the laminate was placed on a hot plate at 120 ± 3 °C. Using a CCD camera, the melting of ammonium acetate was magnified and photographed, and the time T1 from when it was placed on the hot plate until ammonium acetate completely turned into a liquid was measured. When T1 was 120 seconds or less, it was evaluated as 〇; when T1 exceeded 120 seconds and was 150 seconds or less, it was evaluated as △; when T1 exceeded 150 seconds, it was evaluated as ×.

[0073] <Warpage evaluation>

[0074] For a sample with a thickness of 0.5 mm, a length of 60 mm, and a width of 5 mm, the short side of the sample was used as the fixed end, the opposite short side was used as the free end, and the measuring table was fixed to the fixed end. Then, a feeler gauge was used to measure the distance between the free end and the measuring table.

[0075] The warpage of the substrate (the ratio of warpage to the sample length) was calculated by the following formula.

[0076] Warpage = V / 60 × 100 (%)

[0077] When the warpage was less than 2%, it was evaluated as good "〇"; when the warpage was 2% or more and 5% or less, it was evaluated as qualified "△"; when the warpage was greater than 5%, it was evaluated as unqualified "×". For example, when V was 4 mm as described above, warpage = 4 / 60 × 100 (= 6.7)%.

[0078] <Examples 2 - 24, Comparative Examples 2 - 5>

[0079] Except for changing the formation conditions of the metal oxide film in Example 1 to the conditions shown in Tables 1 - 6, laminates were produced by the same operations as in Example 1, and the above evaluations were performed. The results are shown in Tables 1 - 6.

[0080] <Comparative Example 1>

[0081] Referring to the examples of Patent Document 1, a circuit board was obtained. Specifically, using a hot press, a metal material (30 mm × 30 mm) with a thickness of 1.5 mm made of copper and a metal oxide substrate (ceramic substrate 30 mm × 30 mm) with a thickness of 150 μm made of ZTA (zirconia toughened alumina) were heated and pressed to bond them. The obtained circuit board was evaluated as above. The results are shown in Table 6.

[0082] [Table 1]

[0083]

[0084] [Table 2]

[0085]

[0086] [Table 3]

[0087]

[0088] [Table 4]

[0089]

[0090] [Table 5]

[0091]

[0092] [Table 6]

[0093]

[0094] In Tables 1 to 6, polysilazane means (“TRESMILE ANN-120-20”, manufactured by SANWA KAGAKU CORP.);

[0095] Al(acac)3 means aluminum tris(acetylacetonate) (“Aluminum Chelate A”, manufactured by Kawaken Fine Chemicals Co., Ltd.);

[0096] TEOS means tetraethyl orthosilicate (manufactured by Tokyo Chemical Industry Co., Ltd.);

[0097] Bis(sec-butyl alcohol) triethyl orthosilicate aluminum salt is manufactured by Thermo Scientific.

[0098] Comparative Example 1 is a metal oxide laminate produced by using the usual hot pressing method as the manufacturing method of the metal oxide laminate. Since the film thickness of the metal oxide laminate obtained in Comparative Example 1 is large, its heat dissipation is low and it has crystallinity compared with the Examples. Therefore, after the thermal cycling test, the metal oxide film peels off from the metal.

[0099] Since the composition of the metal oxide film of the metal oxide laminate obtained in Comparative Example 2 is outside the scope of the claims of this application, its high voltage resistance is low.

[0100] Since the composition of the metal oxide film of the metal oxide laminate obtained in Comparative Example 3 is outside the scope of the claims of this application, its adhesion is low and cracks are generated.

[0101] Since the composition of the metal oxide film of the metal oxide laminate obtained in Comparative Example 4 falls outside the scope of the claims of the present application, peeling was confirmed in the film-formed sample. Therefore, the adhesion, withstand voltage property, and insulation property are low.

[0102] Since the film formation temperature and the composition of the metal oxide film of the metal oxide laminate obtained in Comparative Example 5 fall outside the scope of the claims of the present application, warping and cracking occurred in the film-formed sample.

Claims

1. A metal oxide film, which is an amorphous metal oxide film, wherein: The metal oxide film is represented by the composition formula: SiaAlbOcTd, In the formula, Si represents a silicon atom, Al represents an aluminum atom, O represents an oxygen atom, and T represents one or more atoms other than Si, Al and O, a, b, c and d represent weight ratios, a+b+c+d=100, a is 3 or more and 45 or less, b is 5 or more and 50 or less, c is 35 or more and 60 or less, and d is 0.05 or more and 10 or less, The metal oxide film has a thickness of 0.1 μm or more and 30 μm or less. 2 . A metal oxide laminate, wherein the metal oxide film according to claim 1 is directly laminated on a sheet-like metal material having a thickness of 0.2 mm to 20 mm.

3. The metal oxide laminate according to claim 2, wherein The metal material is copper or a copper alloy, or aluminum or an aluminum alloy.

4. A method for producing a metal oxide stack, which is the method for producing a metal oxide stack according to claim 2 or 3, comprising the following steps: A step of atomizing or dropletizing a coating liquid containing a salt or complex of a silicon compound and aluminum by transporting the coating liquid by a carrier gas to obtain mist or droplets; and A step of causing the mist or liquid droplets to react on a metal material in a temperature atmosphere of 150° C. to 450° C. inclusive, thereby obtaining a metal oxide film.

5. The method for producing a metal oxide stack according to claim 4, wherein: The temperature atmosphere is 370° C. or less.

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