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

Abstract

The present invention provides 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. [Solution] The surface-treated aluminum material 1 comprises 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.

Description

[Technical Field]

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

[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. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 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. [Overview of the project] [Problems that the invention aims to solve]

[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. [Means for solving the problem]

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

[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. [Effects of the Invention]

[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 heating 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. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a cross-sectional view of the surface-treated aluminum material in the embodiment. [Figure 2] 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. [Modes for carrying out the invention]

[0014] (Aluminum material) The base material of the aluminum material is composed of aluminum or an aluminum alloy. The shape of the base material is not particularly limited and can take various shapes according to the use of the aluminum material. For example, the base material may be an extended material such as a rolled plate or an extruded material, or it may be a cast material or a forged material. Further, the base material may be subjected to machining to form a desired shape. When the shape of the base material is plate-like, the thickness of the base material is not particularly limited. More specifically, the base material may be, for example, a cold-rolled plate having a thickness of about 1 mm, or a hot-rolled plate having a thickness of about 50 mm.

[0015] Also, the material of the base material can be appropriately selected from the group consisting of aluminum and aluminum alloys according to the use of the aluminum material. More specifically, as the aluminum constituting the base material, for example, 1000 series aluminum can be used. Also, as the aluminum alloy 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. Further, the base material may be a clad material in which two or more layers having different chemical compositions are laminated.

[0016] An insulating film including a first layer laminated on the base material and a second layer laminated on the first layer is provided on the base material. 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. Such an insulating film has excellent heat resistance and is unlikely to crack when the temperature rises. Therefore, even when the temperature of the surface-treated aluminum material rises, the occurrence of dielectric breakdown can be suppressed, and the maximum use temperature can be easily increased.

[0017] From the perspective 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 250°C for 4 hours is 35 V / μm or more. Note that the dielectric breakdown strength of the insulating film in the surface-treated aluminum material is a value measured by a method compliant 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 perspective of the dielectric breakdown strength, the upper limit of the thickness of the insulating film is not particularly limited, but the upper limit in manufacturing the insulating film is, for example, 200 μm. From the perspective of further enhancing 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 forming the preferred range of the thickness of the insulating film, the above-described upper and lower limits of the thickness of the insulating film can be arbitrarily combined. The preferred range of the thickness of the insulating film may be, for example, 10 μm or more and 200 μm or less, 10 μm or more and 150 μm or less, 15 μm or more and 100 μm or less, 15 μm or more and 60 μm or less, or 20 μm or more and 60 μm or less.

[0020] The first layer is composed of aluminum oxide. The first layer may have pores. That is, the first layer may be a porous anodic oxide film. Also, the first layer may be a barrier-type anodic oxide film having no pores. From the perspective of more easily increasing 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 metallic 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] When a porosity test is performed according to the method specified in JIS H8683-2:2013, the mass loss per unit area of ​​the aluminum material is 0.3 g / dm². 2 The following is preferable: Since the first layer of the aluminum material is sufficiently covered by the second layer, the reliability of the insulating film can be further enhanced.

[0025] The specific method for the porosity test is as follows: First, prepare 1 L of test solution by dissolving 35 mL of phosphoric acid and 20 g of chromic anhydride in water. Next, take a test piece containing the insulating film from the aluminum material and measure the area of ​​the insulating film on the test piece. After removing any dirt from the surface of the test piece, measure its mass. Then, immerse the test piece in the test solution maintained at a temperature of 38°C ± 1°C for 15 minutes ± 5 seconds.

[0026] After the test specimen has been immersed in the test solution, it is washed with running water, and then with deionized water or distilled water. After the washed specimen is thoroughly dried, its mass is measured.

[0027] The area A (unit: dm²) of the insulating coating of the test specimen obtained from the above is... 2 Using the mass m1 (unit: g) of the test specimen before immersion in the test solution and the mass m2 (unit: g) of the test specimen after immersion in the test solution, the mass loss per unit area δ is calculated based on the following formula (1). A (Unit: g / dm 2 It is possible to calculate ). δ A =(m1-m2) / A ···(1)

[0028] 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.

[0029] (Manufacturing method for aluminum materials) The surface-treated aluminum material is, for example, The first layer is formed on the base material by applying an anodizing treatment to the base material. Subsequently, the base material and the first layer are heated at a temperature of 150°C to 500°C. The result is obtained by forming the second layer on the first layer thereafter.

[0030] 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.

[0031] 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. 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The current density of the DC current in the anodizing process is, for example, 1 mA / cm². 2 More than 100mA / cm 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.

[0036] 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.

[0037] In the above manufacturing method, after anodizing, the base material and the first layer are heated at a temperature of 150°C to 500°C. By heating the first layer at a temperature within the specified range before forming the second layer on top of the first layer, the internal stress 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 heat resistance of the insulating film can be improved. As a result, the occurrence of cracks in the insulating film when heated can be suppressed, and dielectric breakdown can be suppressed even when the temperature of the aluminum material rises.

[0038] If the heating temperature of the first layer is less than 150°C, the relaxation of internal stress in the first layer tends to be insufficient. In this case, cracks may occur in the insulating film when the temperature of the aluminum material rises, making dielectric breakdown more likely. 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, even more preferably 230°C or higher, and particularly preferably 250°C or higher, this problem can be easily avoided and the heat resistance of the insulating film can be easily improved.

[0039] On the other hand, if the heating temperature of the first layer exceeds 500°C, the first layer may not be able to keep up with the thermal expansion of the base material, and cracks may occur in the first layer while it 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, even 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.

[0040] In determining the preferred range for 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 to 450°C, 200°C to 400°C, 230°C to 350°C, or 250°C to 300°C.

[0041] In heating the first layer, heating may be terminated immediately after the temperature of the first layer reaches the desired temperature, or the temperature may be maintained for a certain period of time after reaching the desired temperature. From the viewpoint of sufficiently relaxing the internal stress of the first layer and more reliably obtaining an aluminum material that is less prone to dielectric breakdown even at high temperatures, it is preferable that the heating time from the start to the end of heating of the first layer is 1 minute or more.

[0042] Furthermore, it is preferable that the heating temperature of the first layer be above 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 suppressed more reliably. As a result, dielectric breakdown can be suppressed, and the high insulation performance can be maintained for a longer period of time.

[0043] 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.

[0044] 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.

[0045] 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 sealing agent. As the sealing agent, for example, a substance capable of reacting 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.

[0046] 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.

[0047] From the viewpoint of more easily obtaining aluminum materials with excellent corrosion resistance and heat resistance, it is preferable that the sealant be hot water at a temperature of 80°C or higher. When using hot water as the sealant, 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. [Examples]

[0048] 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.

[0049] 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.

[0050] 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.

[0051] (Test materials A1~A11) To prepare 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 base material 2. This base material 2 is subjected to a pretreatment for anodizing. Specifically, as a pretreatment, base material 2 is first subjected to alkaline etching by immersing it in a 5 mass% sodium hydroxide aqueous solution at a temperature of 55°C. After that, base material 2 is subjected to desmatt treatment by immersing it in 30 mass% nitric acid.

[0052] 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.

[0053] 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.

[0054] 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 performing a sealing degree test according to the method specified in JIS H8683-2:2013 is approximately 0.01 g / dm². 2 This is the result.

[0055] (Test materials B1-B6) Test specimens B1 to B6 are for comparison with test specimens A1 to A11. The preparation method for 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 preparation method for test specimen B6 is also the same as that for test specimens A1 to A11, except that the heating temperature and heating time for the first layer are changed as shown in Table 1.

[0056] (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".

[0057] (Test material B7) Test specimen B7 is a test specimen used for comparison with test specimen A12. The method for preparing test specimen B7 is the same as that for test specimen A12, except that the second layer is formed without heating after the first layer is formed.

[0058] Table 1 shows the results of the dielectric strength tests for test materials A1-A12 and B1-B7 after heating. The specific test method is as follows.

[0059] 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. After heating, the test material is subjected to a dielectric strength test five times using a method compliant with JIS H8687-2:2013. The dielectric strength can be calculated by dividing the average dielectric breakdown voltage obtained from these five dielectric strength tests by the thickness of the insulating film 3.

[0060] 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.

[0061] [Table 1]

[0062] As shown in Table 1, test materials A1 to A11 are manufactured by heating the first layer on the 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 insulating films 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.

[0063] 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 35V / μm or higher. From a comparison with 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 35V / μm or higher. Thus, like test materials A1 to A11, test material A12 can easily have its maximum operating temperature increased while maintaining high electrical insulation properties.

[0064] In contrast, test materials B1-B5 and 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-A12.

[0065] 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.

[0066] Based on the above examples, the aspects of the surface-treated aluminum material, the member for semiconductor manufacturing equipment, and the electrostatic chuck have been described. However, the specific aspects of the surface-treated aluminum material, the member for semiconductor manufacturing equipment, and the electrostatic chuck according to the present invention are not limited to the aspects of the examples, and the configuration can be appropriately changed within the scope that does not impair the gist of the present invention.

[0067] For example, the surface-treated aluminum material can adopt the aspects according to the following [1] to [6].

[0068] (1) 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 an aluminum oxide, and has a first layer covering the base material, and a second layer covering the first layer, and the surface-treated aluminum material has an insulation breakdown strength of 35 V / μm or more of the insulating film after being heated at a temperature of 200°C for 4 hours. (2) The surface-treated aluminum material according to (1), wherein the insulation breakdown strength of the insulating film after being heated at a temperature of 250°C for 4 hours is 35 V / μm or more.

[0069] (3) The surface-treated aluminum material according to (1) or (2), wherein the thickness of the insulating film is 10 μm or more. (4) When a sealing degree test is performed by the method specified in JIS H8683-2:2013, the mass reduction amount per unit area is 0.3 g / dm 2 or less. The surface-treated aluminum material according to any one of (1) to (3).

[0070] (5) The surface-treated aluminum material according to any one of (1) to (4), wherein the second layer contains a hydrated oxide of aluminum. [6] The surface-treated aluminum material according to [5], wherein the second layer further comprises an oxide and / or hydroxide of one or more metallic 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.

[0071] Furthermore, the semiconductor manufacturing equipment component may take the form described in [7] below. A component for semiconductor manufacturing equipment made of a surface-treated aluminum material as described in any one of [7], [1], to [6].

[0072] Furthermore, the electrostatic chuck may take the form described in [8] below. An electrostatic chuck made of surface-treated aluminum material as described in any one of [8], [1], to [6]. [Explanation of Symbols]

[0073] 1. Surface-treated aluminum material 2 Base material 3. Insulating coating 31 First layer 32 Second layer

Claims

1. 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, The insulating film consists of an aluminum oxide and comprises a first layer covering the base material, It has a second layer covering the preceding first layer, A surface-treated aluminum material in which 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 a porosity 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, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc.

7. A component for semiconductor manufacturing equipment, comprising 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.

Images