Surface-treated aluminum material, member for semiconductor manufacturing device, and electrostatic chuck

Abstract

A surface-treated aluminum material (1) comprises a base material (2) that comprises aluminum or an aluminum alloy, and an insulating film (3) that is formed on the base material. The insulating film (3) has a first layer (31) that comprises an aluminum oxide and that covers the base material (2), and a second layer (32) that covers the first layer (31). The dielectric breakdown strength of the insulating film (3) after being heated at a temperature of 200°C for one hour is not less than 35 V / μm.

Description

Surface-treated aluminum materials, components for semiconductor manufacturing equipment, and electrostatic chucks

[0001] This invention relates to surface-treated aluminum material, components for semiconductor manufacturing equipment, and electrostatic chucks.

[0002] Aluminum materials, consisting of aluminum or aluminum alloys, are used in a wide variety of applications. These aluminum materials may have an anodic oxide coating applied to their surface to achieve various objectives, such as improved corrosion resistance, scratch resistance, and aesthetic appeal. Because the functions that can be imparted to aluminum materials by the anodic oxide coating are diverse, the application fields of aluminum materials with anodic oxide coatings are expanding rapidly.

[0003] For example, since anodized coatings are dielectrics, a dielectric coating can be formed on the surface of an aluminum material by performing anodizing treatment. Thus, an aluminum material with a dielectric coating on its surface can be used, for example, as an electrostatic chuck as shown in Non-Patent Document 1.

[0004] Junichi Takeuchi, Ryo Yamazaki, Kazumi Tani, and Yasuo Takahashi, "Improvement of Ceramic Coatings with Electrostatic Adsorption Capability Using Reduced-Pressure Plasma Spraying," Journal of the High Temperature Society of Japan, 2010, Vol. 36, No. 6, pp. 288-294.

[0005] Aluminum materials with an anodized coating on their surface are prone to cracking in the anodized coating when the temperature rises. When cracks occur in the anodized coating, electrolysis concentrates at the tip of the crack, making dielectric breakdown more likely. Therefore, when using aluminum materials with an anodized coating on their surface as electrostatic chucks, there was a limit to how high the maximum operating temperature, that is, the maximum temperature expected in the environment in which the electrostatic chuck is used, could be increased.

[0006] This invention was made in view of the above background, and aims to provide a surface-treated aluminum material, a component for semiconductor manufacturing equipment, and an electrostatic chuck that can easily increase the maximum operating temperature while maintaining high electrical insulation properties.

[0007] One aspect of the present invention is a surface-treated aluminum material having a base material made of aluminum or an aluminum alloy and an insulating film formed on the base material, wherein the insulating film is made of aluminum oxide and has a first layer covering the base material and a second layer covering the first layer, and the dielectric breakdown strength of the insulating film after heating at a temperature of 200°C for 4 hours is 35 V / μm or more.

[0008] Another aspect of the present invention is a component for semiconductor manufacturing equipment made of the surface-treated aluminum material of the above aspect.

[0009] Yet another aspect of the present invention is an electrostatic chuck made of the surface-treated aluminum material of the above aspect.

[0010] The surface-treated aluminum material (hereinafter referred to as "aluminum material") comprises a first layer made of aluminum oxide and a second layer covering the first layer, and has an insulating film formed on the base material. Furthermore, the dielectric breakdown strength of the insulating film after being heated at a temperature of 200°C for 4 hours is 35 V / μm or more. The aluminum material having such characteristics can suppress the occurrence of cracks in the first layer even when its temperature rises. Therefore, the surface-treated aluminum material can suppress the occurrence of dielectric breakdown even when its temperature rises.

[0011] The semiconductor manufacturing equipment component and the electrostatic chuck are made of surface-treated aluminum material according to the above-described embodiment. As mentioned above, the aluminum material is less prone to cracking of the insulating film even when its temperature rises. Therefore, the semiconductor manufacturing equipment component and the electrostatic chuck can be easily operated at a higher maximum temperature.

[0012] As described above, according to the above embodiment, it is possible to provide a surface-treated aluminum material, a component for semiconductor manufacturing equipment, and an electrostatic chuck that can easily increase the maximum operating temperature while maintaining high electrical insulation properties.

[0013] Figure 1 is a cross-sectional view of the surface-treated aluminum material in the embodiment. Figure 2 is a cross-sectional view of the base material on which the first layer has been formed during the manufacturing process of the surface-treated aluminum material in the embodiment.

[0014] (Aluminum Material) The base material of the aluminum material is made of aluminum or an aluminum alloy. The shape of the base material is not particularly limited and can take various shapes depending on the application of the aluminum material. For example, the base material may be a wrought material such as a rolled plate or an extruded material, or it may be a cast material or a forged material. The base material may also be machined to form a desired shape. When the shape of the base material is a plate, the thickness of the base material is not particularly limited. More specifically, the base material may be a cold-rolled plate with a thickness of about 1 mm, or a hot-rolled plate with a thickness of about 50 mm.

[0015] Furthermore, the material of the base material can be appropriately selected from the group consisting of aluminum and aluminum alloys, depending on the application of the aluminum material. More specifically, for example, 1000 series aluminum can be used as the aluminum constituting the base material. For example, 2000 series aluminum alloy, 3000 series aluminum alloy, 4000 series aluminum alloy, 5000 series aluminum alloy, 6000 series aluminum alloy, 7000 series aluminum alloy, and 8000 series aluminum alloy can be used as the aluminum alloy constituting the base material. In addition, the base material may be a clad material in which two or more layers having different chemical compositions are laminated together.

[0016] An insulating film is provided on the base material, comprising a first layer laminated on the base material and a second layer laminated on the first layer. After heating at 200°C for 4 hours, the dielectric breakdown strength of the insulating film is 35 V / μm or more. An insulating film having such characteristics has excellent heat resistance and is less prone to cracking when the temperature rises. Therefore, the surface-treated aluminum material can suppress dielectric breakdown even when its temperature rises, and its maximum operating temperature can be easily increased.

[0017] From the viewpoint of increasing the maximum operating temperature of the surface-treated aluminum material, it is preferable that the dielectric breakdown strength of the insulating film after heating at a temperature of 250°C for 4 hours is 35 V / μm or higher. The dielectric breakdown strength of the insulating film in the surface-treated aluminum material is a value measured by a method in accordance with JIS H8687-2:2013.

[0018] The thickness of the insulating film is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. In this case, the dielectric breakdown voltage of the aluminum material can be further improved. From the viewpoint of dielectric breakdown strength, there is no particular upper limit to the thickness of the insulating film, but the manufacturing upper limit for the thickness of the insulating film is, for example, 200 μm. From the viewpoint of further increasing the productivity of the aluminum material, the thickness of the insulating film is preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 60 μm or less.

[0019] In determining the preferred range of the insulating film thickness, the upper and lower limits of the insulating film thickness described above can be arbitrarily combined. The preferred range of the insulating film thickness may be, for example, 10 μm to 200 μm, 10 μm to 150 μm, 15 μm to 100 μm, 15 μm to 60 μm, or 20 μm to 60 μm.

[0020] The first layer is composed of aluminum oxide. The first layer may have pores. That is, the first layer may be a porous type anodic oxide film. Alternatively, the first layer may be a barrier type anodic oxide film that does not have pores. From the viewpoint of making it easier to increase the thickness of the anodic oxide film, it is preferable that the first layer has pores.

[0021] The material constituting the second layer is not particularly limited as long as it is an electrical insulator. For example, the second layer may be an electrical insulating coating. The second layer may also be composed of hydrated aluminum oxide. Furthermore, the second layer may be composed of hydrated aluminum oxide and oxides and / or hydroxides of metal elements other than aluminum. Examples of metal elements included in the second layer include Ni (nickel), Cr (chromium), Zr (zirconium), Si (silicon), Ti (titanium), Au (gold), Ag (silver), Co (cobalt), Mo (molybdenum), Mn (manganese), Nb (niobium), Ta (tantalum), W (tungsten), Zn (zinc), Fe (iron), Ir (iridium), and Sc (scandium). In other words, the second layer may contain a hydrated aluminum oxide and an oxide and / or hydroxide of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc.

[0022] The second layer preferably contains aluminum hydrate oxide. Because aluminum hydrate oxide has high chemical stability, it is less likely to deteriorate during use of the aluminum material. Furthermore, aluminum hydrate oxide also has excellent electrical insulation properties. Therefore, by providing a second layer containing aluminum hydrate oxide on the first layer, the electrical insulation properties of the insulating film can be maintained for a longer period of time.

[0023] Furthermore, the second layer containing hydrated aluminum oxide is formed, for example, by hydrating the aluminum oxide contained in the first layer after the first layer has been formed by anodizing the base material. When aluminum oxide is hydrated, the hydrated oxide grows from the surface of the aluminum oxide, making it difficult for defects to form between the aluminum oxide and the hydrated oxide. Therefore, by forming a second layer containing hydrated aluminum oxide on the first layer, the formation of defects at the interface between the first and second layers can be suppressed, and the reliability of the insulating film can be further improved.

[0024] It is preferable that the first layer and the second layer have no cracks. Thus, by forming an insulating film without cracks on the base material, the reliability of the surface-treated aluminum material can be further enhanced.

[0025] When the porosity test is carried out by the method specified in JIS H8683-2:2013, the mass reduction amount per unit area of the aluminum material is preferably 0.3 g / dm ,

[0029] , ２ , Ａ , １ , Ａ , ２ ,

[0028] , １ , ２ ,

[0027] , , ２ ,

[0026] , , or less. Since the first layer of such an aluminum material is sufficiently covered by the second layer, the reliability of the insulating film can be further enhanced.

[0026] The specific method of the porosity test is as follows. First, dissolve 35 mL of phosphoric acid and 20 g of anhydrous chromic acid in water to prepare 1 L of a test solution. Next, collect a test piece including the insulating film from the aluminum material and measure the area of the insulating film in the test piece. After removing the dirt on the surface of this test piece, measure the mass of the test piece. Then, immerse the test piece in the test solution maintained at a temperature of 38 °C ± [1] °C for 15 minutes ± 5 seconds.

[0027] After the immersion of the test piece in the test solution is completed, wash the test piece with running water and further wash it with deionized water or distilled water. After the washed test piece is sufficiently dried, measure the mass of the test piece.

[0028] Using the area A (unit: dm ２ ) of the insulating film of the test piece, the mass m １ (unit: g) of the test piece before immersion in the test solution, and the mass m ２ (unit: g) of the test piece after immersion in the test solution obtained as above, the mass reduction amount δ Ａ (unit: g / dm ２ ) per unit area can be calculated based on the following formula (1). δ Ａ = (m １ - m ２ ) / A ・・・(1)

[0029] As mentioned above, the aluminum material can easily increase its maximum operating temperature while maintaining high electrical insulation properties. Therefore, the aluminum material is suitable as a component for semiconductor manufacturing equipment, and in particular as an electrostatic chuck for attracting objects by electrostatic force.

[0030] (Method for manufacturing aluminum material) The surface-treated aluminum material is obtained, for example, by forming the first layer on the base material by anodic oxidation treatment of the base material, then heating the base material and the first layer at a temperature of 150°C to 500°C, and then forming the second layer on the first layer.

[0031] In the method for manufacturing the surface-treated aluminum material, after applying anodizing treatment to the base material, the first layer formed by the anodizing treatment is heated to a temperature within the specified range. By heating the first layer in this way before forming the second layer on top of the first layer, the internal stress generated during the formation of the first layer can be relieved. Then, by forming the second layer after the internal stress of the first layer has been relieved, the occurrence of cracks and dielectric breakdown can be suppressed even when the temperature of the aluminum material rises. The method for manufacturing the aluminum material will be described in more detail below.

[0032] In producing the surface-treated aluminum material, first, a base material made of aluminum or an aluminum alloy is prepared. The method for manufacturing the base material is not particularly limited, and known methods can be used. For example, the base material may be produced by a method that appropriately combines casting, rolling, and heat treatment. As for the casting method of the base material, either DC casting or continuous casting may be used. Furthermore, the base material may be formed into a desired shape by machining a cast material, forged material, or wrought material.

[0033] Furthermore, in the above manufacturing method, pretreatments such as degreasing, etching, desmatting, polishing, and grinding may be performed on the base material before anodizing, as necessary.

[0034] In the above manufacturing method, the first layer is formed on the base material by subjecting the base material prepared in this manner to an anodic oxidation treatment. In the anodic oxidation treatment, the first layer can be formed on the surface of the base material by DC electrolysis, that is, by passing a DC current between the base material and the counter electrode while the base material and the counter electrode are immersed in an electrolyte solution.

[0035] The electrolyte used in the anodic oxidation process may be an acidic electrolyte containing electrolytes such as sulfuric acid, oxalic acid, or phosphoric acid, or an alkaline electrolyte containing electrolytes such as sodium metaborate. Preferably, the electrolyte used in the anodic oxidation process contains an inorganic electrolyte consisting of inorganic cations such as metal ions or ammonium ions, and one or more anions selected from the group consisting of sulfate ions, phosphate ions, and borate ions. By performing the anodic oxidation process using an electrolyte containing an inorganic electrolyte, a first layer having the desired structure can be formed more easily.

[0036] The current density of the DC current in the anodizing process is, for example, 1 mA / cm². ２ 100mA / cm or more ２ The temperature can be set appropriately from the following range. Furthermore, the electrolyte temperature in the anodizing process can be set appropriately from, for example, a range of 0°C to 40°C.

[0037] The thickness of the first layer formed during the anodizing process is preferably 10 μm or more. By making the thickness of the first layer 10 μm or more, the thickness of the insulating film obtained after sealing can be sufficiently increased, and the dielectric breakdown voltage can be made higher.

[0038] In the manufacturing method, after an anodic oxidation treatment, the base material and the first layer are heated at a temperature of 150°C or higher and 500°C or lower. Thus, by heating the first layer at a temperature within the specific range before forming the second layer on the first layer, the internal stress of the first layer can be relaxed. And by forming the second layer after relaxing the internal stress of the first layer, the heat resistance of the insulating film can be enhanced. As a result, the generation of cracks in the insulating film when heated can be suppressed, and the occurrence of dielectric breakdown can be suppressed even when the temperature of the aluminum material rises.

[0039] From the viewpoint of more surely obtaining such an effect, in the manufacturing method, it is preferable that the first layer formed by anodic oxidation treatment and the structure of the first layer at the start of heating are substantially the same. In other words, after forming the first layer by anodic oxidation treatment, it is preferable to heat the first layer without performing a treatment for changing the structure of the first layer. From a similar viewpoint, it is more preferable to heat the first layer without performing other treatments after forming the first layer by anodic oxidation treatment. Treatments for changing the structure of the first layer include, for example, a treatment for forming cracks in the first layer, a treatment for changing the pore diameter of the pores in the first layer, a treatment for attaching a substance different from the substance constituting the first layer in the pores of the first layer, and the like.

[0040] When the heating temperature of the first layer is less than 150°C, the relaxation of the internal stress of the first layer tends to be insufficient. Therefore, in this case, when the temperature of the aluminum material rises, cracks may occur in the insulating film, and dielectric breakdown may easily occur. By setting the heating temperature of the first layer to 150°C or higher, preferably 180°C or higher, more preferably 200°C or higher, still more preferably 230°C or higher, and particularly preferably 250°C or higher, such a problem can be easily avoided, and the heat resistance of the insulating film can be easily improved.

[0041] On the other hand, when the heating temperature of the first layer exceeds 500°C, the first layer cannot follow the thermal expansion of the base material, and cracks may occur in the first layer while the first layer is being heated. By setting the heating temperature of the first layer to 500°C or lower, preferably 450°C or lower, more preferably 400°C or lower, still more preferably 350°C or lower, and particularly preferably 300°C or lower, the occurrence of cracks in the first layer during heating can be easily avoided, and a crack-free first layer can be easily formed.

[0042] In determining the preferred range of the heating temperature of the first layer, the upper and lower limits of the heating temperature of the first layer described above can be arbitrarily combined. For example, the heating temperature of the first layer may be 180°C or higher and 450°C or lower, 200°C or higher and 400°C or lower, 230°C or higher and 350°C or lower, or 250°C or higher and 300°C or lower.

[0043] In heating the first layer, the heating may be terminated immediately after the temperature of the first layer reaches the desired temperature, or after the desired temperature is reached, the temperature may be maintained for a certain period of time. From the viewpoint of more reliably obtaining an aluminum material with sufficiently relaxed internal stress in the first layer and less likely to cause dielectric breakdown even at high temperatures, the heating time from the start to the end of heating the first layer is preferably 1 minute or longer.

[0044] Further, the heating temperature of the first layer is preferably not lower than the maximum operating temperature of the surface-treated aluminum material. In this case, the occurrence of cracks in the surface-treated aluminum material during use can be more reliably suppressed. As a result, the occurrence of dielectric breakdown can be suppressed, and the high insulation property can be maintained for a longer period.

[0045] The reason why the aforementioned effects are obtained by setting the heating temperature of the first layer to a temperature above the maximum operating temperature of the surface-treated aluminum material is not entirely clear, but the following reasons can be considered, for example. Multiple strains exist in the first layer formed on the base material, and these strains are thought to be released when heated at a temperature corresponding to the state of each strain. Therefore, when the first layer is heated in the aluminum material manufacturing method, it is thought that the strains present in the first layer are released according to the heating temperature of the first layer, and the internal stress is relieved. Consequently, if the temperature of the surface-treated aluminum material obtained by the manufacturing method is below the heating temperature of the first layer, it is thought that there are no strains to be released in the first layer. For the reasons above, it is thought that the occurrence of cracks associated with the release of strains in the first layer can be suppressed by setting the heating temperature of the first layer to a temperature above the maximum operating temperature of the surface-treated aluminum material.

[0046] In the above manufacturing method, the first layer is heated, and then the second layer is formed on top of the first layer. The method for forming the second layer can be any method appropriate from known methods, depending on the material constituting the second layer. For example, if the second layer is an electrically insulating coating, the coating can be formed by applying the coating to the first layer and then drying the coating.

[0047] Furthermore, if the second layer contains a hydrated aluminum oxide, the second layer can be formed on the first layer by bringing the first layer into contact with a sealant. In this case, after forming a crack-free first layer on the base material, a crack-free second layer can be easily formed by bringing the first layer into contact with a sealant. As the sealant, for example, a substance that can react with aluminum oxide to form a hydrated oxide can be used, such as hot water or steam at a temperature of 80°C or higher, or an aqueous solution containing ions of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc. When sealing is performed using hot water or steam, a second layer consisting of a hydrated aluminum oxide can be formed on the first layer.

[0048] Furthermore, when an aqueous solution containing ions of the metal element is used as a sealing agent, a second layer containing hydrated aluminum oxide and oxides and / or hydroxides of the metal element can be formed on the first layer. The metal element may exist as a metal ion or as a complex ion in the aqueous solution. More specifically, aqueous solutions of metal salts containing the metal element, such as aqueous nickel acetate solution, aqueous cobalt acetate solution, aqueous nickel fluoride solution, aqueous chromate solution, and aqueous silicate solution, can be used as sealing agents.

[0049] From the viewpoint of more easily obtaining aluminum materials with excellent corrosion resistance and heat resistance, it is preferable that the sealing agent be hot water at a temperature of 80°C or higher. When using hot water as the sealing agent, it is even more preferable to form the second layer by contacting the first layer with hot water at 80°C or higher for 10 minutes or more but less than 120 minutes.

[0050] An example of the surface-treated aluminum material described above will be explained with reference to Figures 1 and 2. As shown in Figure 1, the surface-treated aluminum material 1 of this example has a base material 2 made of aluminum or an aluminum alloy and an insulating film 3 formed on the base material. The insulating film 3 is made of aluminum oxide and has a first layer 31 covering the base material 2 and a second layer 32 covering the first layer 31. The dielectric breakdown strength of the insulating film 3 after heating at a temperature of 200°C for 1 hour is 35 V / μm or more.

[0051] In producing the aluminum material 1 in this example, first, the base material 2 is subjected to anodizing treatment to form a first layer 31 on the base material 2, as shown in Figure 2. Then, the base material 2 and the first layer 31 are heated at a temperature of 150°C to 500°C to relieve the internal stress of the first layer 31. Finally, the aluminum material 1 is obtained by forming a second layer 32 on the heated first layer 31.

[0052] Table 1 shows specific examples of aluminum material 1 (test materials A1 to A12). The method for preparing these test materials is as follows, for example.

[0053] (Test materials A1 to A11) In preparing test materials A1 to A11, first, an aluminum plate with a thickness of 1 mm and having the chemical composition represented by alloy number A6016 is prepared as the base material 2. This base material 2 is subjected to a pretreatment for anodic oxidation. Specifically, as a pretreatment, the base material 2 is first subjected to an alkaline etching treatment by immersing it in a sodium hydroxide aqueous solution with a concentration of 5 mass% at a temperature of 55°C. After that, the base material 2 is subjected to a desmatt treatment by immersing it in nitric acid with a concentration of 30 mass%.

[0054] After pre-treating the base material 2 as described above, the base material 2 is subjected to DC electrolysis as an anodizing treatment to form a first layer 31 on the surface of the base material 2. The electrolyte used in the anodizing treatment is a 15% by mass aqueous sulfuric acid solution, and the temperature of the electrolyte is 5°C. The first layer 31 formed in this way is a so-called porous type anodized film and has a large number of pores 311 as shown in Figure 2.

[0055] After anodizing, the base material 2 is heated in a heating furnace to relieve the internal stress of the first layer 31. The set temperature of the heating furnace is the value shown in the "Heating Temperature" column of Table 1, and the time the base material 2 stays in the furnace, that is, the time from the start of heating to the end of heating, is the value shown in the "Heating Time" column of Table 1.

[0056] Subsequently, the base material 2 with the first layer 31 is immersed in hot water at 100°C for 60 minutes as a sealing agent to form a second layer 32 made of hydrated aluminum oxide on the first layer 31, and the pores 311 of the first layer 31 are sealed by the second layer 32. Through this process, test materials A1 to A11 shown in Table 1 can be obtained. The thickness of the insulating film 3 in test materials A1 to A11 is as shown in Table 1. When sealing the pores 311 of the first layer 31 under these conditions, the mass loss per unit area of ​​the aluminum material 1 when a sealing degree test is performed according to the method specified in JIS H8683-2:2013 is approximately 0.01 g / dm². 2 This is the result. Furthermore, the first layer 31 and the second layer 32 in test materials A1 to A11 do not have cracks.

[0057] (Test specimens B1 to B6) Test specimens B1 to B6 are test specimens for comparison with test specimens A1 to A11. The method for preparing test specimens B1 to B5 is the same as that for test specimens A1 to A11, except that the second layer is formed without heating after the first layer is formed. The method for preparing test specimen B6 is the same as that for test specimens A1 to A11, except that the heating temperature and heating time of the first layer are changed as shown in Table 1.

[0058] (Test material A12) The method for preparing test material A12 is the same as that for test material A3, except that an aqueous solution containing nickel ions is used as the sealing agent instead of boiling water, and the contact time between the sealing agent and the first layer is changed to 30 minutes. Specifically, the sealing agent used to prepare test material A12 is an aqueous solution of "Topseal (registered trademark) H-298" manufactured by Okuno Pharmaceutical Co., Ltd., diluted with water to a concentration of 40 mL / L. "Topseal H-298" is an aqueous solution mainly composed of nickel acetate. In Table 1, "Topseal H-298" is written as "H-298". The first layer 31 and the second layer 32 in test material A12 do not have cracks.

[0059] (Test material B7) Test material B7 is a test material for comparison with test material A12. The method for preparing test material B7 is the same as that for test material A12, except that the second layer is formed without heating after the first layer is formed.

[0060] Table 1 shows the results of the dielectric strength tests for test materials A1 to A12 and test materials B1 to B7 after heating. The specific test method is as follows.

[0061] First, each test material is heated using a heating furnace. The heating furnace temperature is set to the value shown in the "Heat Treatment Temperature" column of Table 1, and the time spent in the heating furnace is set to the value shown in the "Time Spent" column of the same table. The withstand voltage test is performed five times on each test material after heating using a method compliant with JIS H8687-2:2013. The dielectric breakdown strength can be calculated by dividing the average value of the dielectric breakdown voltage obtained from these five withstand voltage tests by the thickness of the insulating film 3.

[0062] The average dielectric breakdown voltage and dielectric breakdown strength for each test material are shown in the "Average Voltage" and "Dielectric Breakdown Strength" columns of Table 1, respectively. The minimum dielectric breakdown voltage for each test material is shown in the "Minimum Voltage" column of Table 1, and the minimum dielectric breakdown voltage is shown in the "Maximum Voltage" column of the same table.

[0063]

[0064] As shown in Table 1, test materials A1 to A11 are manufactured by heating a first layer on a base material at a temperature within the specified range, and then forming a second layer. Therefore, after heating these test materials at 200°C for 4 hours, the dielectric breakdown strength of the insulating film is 35 V / μm or higher. Test materials equipped with such an insulating film can suppress the occurrence of dielectric breakdown even when their temperature rises. Thus, these test materials can easily increase their maximum operating temperature while maintaining high electrical insulation properties.

[0065] Test material A12 was prepared using the same method as test materials A2 to A4, except for the difference in the sealing agent. Furthermore, the dielectric breakdown strength of the insulating film of test material A12 after heating at 250°C for 4 hours is 35 V / μm or higher. From a comparison of test material A3 and test material A4, when the heat treatment temperature is changed from 250°C to 200°C, the average voltage and dielectric breakdown strength increase slightly. Therefore, it is estimated that when test material A12 is heated at 200°C for 4 hours, the dielectric breakdown strength of the insulating film after heating will be 35 V / μm or higher. Accordingly, like test materials A1 to A11, test material A12 can easily have its maximum operating temperature increased while maintaining high electrical insulation properties.

[0066] In contrast, test materials B1 to B5 and test material B7 are manufactured by forming the second layer without heating the first layer on the base material. Therefore, these test materials are prone to cracking when the temperature rises. As a result of the cracking, dielectric breakdown becomes more likely, and the dielectric breakdown strength is lower compared to test materials A1 to A12.

[0067] Furthermore, because the heating temperature of the first layer of test material B6 is too low, cracks are likely to occur when the temperature of test material B6 rises. As a result of the occurrence of cracks, dielectric breakdown becomes more likely, and the dielectric breakdown strength is lower compared to test materials A1 to A12.

[0068] Although the embodiments of the surface-treated aluminum material, semiconductor manufacturing equipment component, and electrostatic chuck have been described above based on the examples, the specific embodiments of the surface-treated aluminum material, semiconductor manufacturing equipment component, and electrostatic chuck according to the present invention are not limited to those of the examples, and the configuration can be appropriately modified without impairing the spirit of the present invention.

[0069] For example, the surface-treated aluminum material may take the following forms [1] to [6].

[0070] [1] A surface-treated aluminum material comprising a base material made of aluminum or an aluminum alloy, and an insulating film formed on the base material, wherein the insulating film is made of aluminum oxide and comprises a first layer covering the base material and a second layer covering the first layer, and the dielectric breakdown strength of the insulating film after heating at a temperature of 200°C for 4 hours is 35 V / μm or more. [2] The surface-treated aluminum material according to [1], wherein the dielectric breakdown strength of the insulating film after heating at a temperature of 250°C for 4 hours is 35 V / μm or more.

[0071] [3] The surface-treated aluminum material according to [1] or [2], wherein the thickness of the insulating film is 10 μm or more. [4] The mass loss per unit area when a porosity test is performed according to the method specified in JIS H8683-2:2013 is 0.3 g / dm 2 The surface-treated aluminum material described in any one of the following [1] to [3].

[0072] [5] The surface-treated aluminum material according to any one of [1] to [4], wherein the second layer comprises a hydrated aluminum oxide. [6] The surface-treated aluminum material according to [5], wherein the second layer further comprises an oxide and / or hydroxide of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc.

[0073] Furthermore, the semiconductor manufacturing apparatus component may take the form described in [7] below: A semiconductor manufacturing apparatus component made of a surface-treated aluminum material as described in any one of [7] [1] to [6].

[0074] Furthermore, the electrostatic chuck may take the form described in [8] below: an electrostatic chuck made of a surface-treated aluminum material as described in any one of [8] [1] to [6].

Claims

1. A surface-treated aluminum material comprising a base material made of aluminum or an aluminum alloy, and an insulating film formed on the base material, wherein the insulating film is made of aluminum oxide and comprises a first layer covering the base material and a second layer covering the first layer, and the dielectric breakdown strength of the insulating film after heating at a temperature of 200°C for 4 hours is 35 V / μm or more.

2. The surface-treated aluminum material according to claim 1, wherein the dielectric breakdown strength of the insulating film after heating at a temperature of 250°C for 4 hours is 35 V / μm or more.

3. The surface-treated aluminum material according to claim 1, wherein the thickness of the insulating film is 10 μm or more.

4. When the degree of sealing test is performed according to the method specified in JIS H8683-2:2013, the mass loss per unit area is 0.3 g / dm². 2 The surface-treated aluminum material according to claim 1, which is as follows:

5. The surface-treated aluminum material according to claim 1, wherein the second layer contains a hydrated oxide of aluminum.

6. The surface-treated aluminum material according to claim 5, wherein the second layer further comprises an oxide and / or hydroxide of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc.

7. A component for semiconductor manufacturing equipment made of a surface-treated aluminum material according to any one of claims 1 to 6.

8. An electrostatic chuck made of a surface-treated aluminum material according to any one of claims 1 to 6.

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