Method for producing anodized coating, alumite component, and plasma processing device

Abstract

Provided is an anodized coating with which it is possible to suppress the occurrence of foreign matter after evacuation and which has corrosion resistance. A base material made of an aluminum alloy is prepared. A porous coating is formed on the base material. A hydrate layer is formed on the uppermost layer of the porous coating. A heating treatment is performed on the hydrate layer and the porous coating. The heating treatment is performed at a temperature of 120°C + a°C or higher and for a duration of 40 / (2^(a / 10)) minutes or greater (where 0 ≤ a < 30). Cracks are formed in the hydrate layer due to the heating treatment.

Description

Anodic oxide film manufacturing method, anodized aluminum parts, and plasma processing apparatus

[0001] The present invention relates to a method for producing an anodic oxide film, an anodized aluminum part, and a plasma processing apparatus.

[0002] Aluminum parts are often used in plasma processing equipment used in semiconductor manufacturing for their strength, light weight, and prevention of heavy metal contamination. Aluminum parts are also sometimes used in equipment that uses corrosive gases such as chlorine, such as plasma dry etching equipment.

[0003] Aluminum parts used in plasma processing chambers require corrosion resistance in particular. Aluminum parts used in vacuum transfer chambers also require corrosion resistance because they are exposed to corrosive gases flowing in from the plasma processing chamber and adhering to the substrate being processed. One method for improving the corrosion resistance of aluminum parts is to manufacture anodized parts by forming an anodized film on the surface of a substrate made of an aluminum alloy. However, there is a need to quickly reduce the amount of foreign matter from the anodized parts when they are installed in equipment.

[0004] For example, Patent Document 1 discloses a technology in which, after a sealing treatment step, an anodized film is subjected to a heat treatment to modify the material inside the pores and prevent the material inside the pores from scattering due to plasma.

[0005] Japanese Patent Application Laid-Open No. 2004-292887

[0006] When performing fine processing on semiconductor substrates using a plasma processing apparatus, if minute foreign particles adhere to the semiconductor substrate, the foreign particles can cause defects. Therefore, it is important to prevent foreign particles from adhering to the semiconductor substrate while the semiconductor substrate is being transported within the plasma processing apparatus.

[0007] After installing a plasma processing apparatus or replacing parts of the plasma processing apparatus, it is important to quickly reduce the amount of foreign matter so that the plasma processing apparatus can be used for production as soon as possible. However, when anodized aluminum parts are used in the plasma processing apparatus, there is a problem in that a large amount of foreign matter is generated from the anodized aluminum parts at the beginning of evacuation.

[0008] For example, in a vacuum transfer chamber, which is not a plasma processing chamber and is not subject to ion incidence, no attempt has been made to suppress foreign matter by heat treatment. Furthermore, excessive heating of a sealed anodized coating can cause cracks to form between the substrate and the anodized coating. Therefore, it has been considered desirable to perform heat treatment at a temperature of 90°C or higher and less than 120°C.

[0009] Anodized films with cracks tend to have poor corrosion resistance and contain a large amount of foreign matter. Even if the anodized film is heat-treated, the generation of foreign matter at the start of use may not be suppressed.

[0010] The main object of the present invention is to provide an anodic oxide coating that can suppress the generation of foreign matter after evacuation and has corrosion resistance even if exposed to the atmosphere for a certain period of time before evacuation, and also to provide a plasma processing apparatus that uses an anodized aluminum part having such an anodic oxide coating.

[0011] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0012] One embodiment of the method for producing an anodic oxide film includes the steps of: (a) preparing a substrate made of an aluminum alloy; (b) forming a porous coating on the substrate; (c) forming a hydrate layer on top of the porous coating; and (d) heat-treating the hydrate layer and the porous coating. The heat-treating is performed at a temperature of 120°C + a°C or higher for a time of 40 / (2(a / 10)) minutes or longer (where 0≦a<30), and cracks are formed in the hydrate layer by the heat-treating.

[0013] An anodized aluminum component according to one embodiment includes a substrate made of an aluminum alloy, a porous coating formed on the substrate, and a hydrate layer formed on the top surface of the porous coating. Cracks are formed in the hydrate layer, and the deepest ends of the cracks do not reach the substrate.

[0014] According to one embodiment, it is possible to provide an anodized aluminum component having a corrosion-resistant anodic oxide coating that can suppress the generation of foreign matter after evacuation even if the component is exposed to the atmosphere for a certain period of time before evacuation. Also, it is possible to provide a plasma processing apparatus that uses an anodized aluminum component having such an anodized oxide coating.

[0015] FIG. 1 is a schematic diagram showing a plasma processing apparatus in embodiment 1. FIG. 2 is a flow diagram and a perspective view showing a method for manufacturing an anodic oxide film in embodiment 1. FIG. 3 is a cross-sectional view showing anodized aluminum parts in embodiment 1 and comparative examples 1 to 3, and a table showing characteristics of the anodized aluminum parts. FIG. 4 is data obtained in an experiment by the inventors of the present application. FIG. 5 is an SEM image obtained in an experiment by the inventors of the present application. FIG. 6 is a flow diagram showing a method for determining heating conditions for an anodic oxide film in embodiment 1. FIG. 7 is data obtained in an experiment by the inventors of the present application. FIG. 8 is an SEM image obtained in an experiment by the inventors of the present application. FIG. 9 is a flow diagram showing the timing for applying a heat treatment to an anodic oxide film in modification 1. FIG. 10 is a flow diagram showing the timing for applying a heat treatment to an anodic oxide film in modification 2. FIG. 11 is a flow diagram showing the timing for applying a heat treatment to an anodic oxide film in modification 3. FIG. 12 is a flow diagram showing the timing for applying a heat treatment to an anodic oxide film in modification 4. FIG. 10 is a schematic diagram showing a plasma processing apparatus according to a fourth modified example.

[0016] Hereinafter, embodiments will be described in detail with reference to the drawings. In all drawings for explaining the embodiments, components having the same functions are designated by the same reference numerals, and repeated explanations thereof will be omitted. In the following embodiments, explanations of the same or similar parts will not be repeated unless particularly necessary.

[0017] First Embodiment <Plasma Processing Apparatus> Hereinafter, each structure included in a plasma processing apparatus 100 according to a first embodiment will be described with reference to FIG.

[0018] 1, the plasma processing apparatus 100 mainly includes an Equipment Front End Module (EFEM) 101, a load lock chamber 102, gate valves 103 to 106, a connection part 107, a vacuum transfer chamber 108, a vacuum robot 109, a connection part 110, and a plasma processing chamber 111. A container 112 for the load lock chamber, a container 113 for the vacuum transfer chamber, and a container 114 for the plasma processing chamber are mainly made of an aluminum alloy.

[0019] When plasma processing apparatus 100 is installed or when parts used in plasma processing apparatus 100 are replaced, plasma processing apparatus 100 is wholly or partially exposed to the atmosphere. After that, moisture and the like adsorbed on the internal parts of load lock chamber 102, vacuum transfer chamber 108, and plasma processing chamber 111 are exhausted by exhaust units 115, 116, and 117, respectively.

[0020] If the plasma processing apparatus 100 passes performance tests such as foreign matter suppression and etching rate, product processing (substrate processing) is performed. During product processing, the substrate to be processed is set in the EFEM 101 and transported to the load lock chamber 102 by the EFEM 101. A gate valve 103 isolates the load lock chamber 102 from the atmosphere. A gate valve 104 isolates the load lock chamber 102 from the vacuum transfer chamber 108. An exhaust unit 115 evacuates the inside of the load lock chamber 102, creating a vacuum inside the load lock chamber 102.

[0021] The exhaust unit 116 exhausts the inside of the vacuum transfer chamber 108 to create a vacuum inside the vacuum transfer chamber 108. The purge gas supply unit 118 supplies a dry purge gas at a constant flow rate into the inside of the vacuum transfer chamber 108. Alternatively, the supply of the dry purge gas maintains a constant pressure inside the vacuum transfer chamber 108. The dry purge gas is, for example, argon, dry nitrogen, or dry air.

[0022] The gas under reduced pressure present inside the vacuum transfer chamber 108 is steadily or intermittently replaced with dry purge gas. After the gate valve 104 is opened, the vacuum robot 109 transfers the substrate 119 to be processed from the load lock chamber 102 to the plasma processing chamber 111. Note that the substrate 119 may be transferred without supplying purge gas into the vacuum transfer chamber 108.

[0023] The plasma processing chamber 111 has a plasma processing chamber vessel 114, a process gas supply unit 120, a process power supply unit 121, a temperature control heater 122, an upper replacement part 123, and a lower replacement part 124. The upper replacement part 123 and the lower replacement part 124 are mainly made of an aluminum alloy.

[0024] The temperature inside the plasma processing chamber 111 is adjusted to 70° C. or higher and 100° C. or lower by a temperature control heater 122 in order to stabilize processing performance and prevent material adhering to the inner wall from peeling off. A process gas supply unit 120 supplies a process gas into the plasma processing chamber 111.

[0025] The process gas includes a reactive process gas and an inert gas such as argon or nitrogen. The reactive process gas includes any or all of chlorine molecules, hydrogen chloride, boron trichloride, hydrogen bromide, molecules containing chlorine atoms that decompose to become corrosive, and molecules containing bromine atoms. Before at least the reactive process gas is supplied into the plasma processing chamber 111, the gate valve 106 of the connection part 110 is closed to prevent the reactive process gas from flowing from the plasma processing chamber 111 into the vacuum transfer chamber 108.

[0026] Inside the plasma processing chamber 111, a plasma 126 is generated by the process gas and electromagnetic waves supplied from the processing power supply unit 121. A substrate 125 to be processed is processed by the plasma 126.

[0027] The upper replacement part 123 is mainly installed above the substrate 125 to be processed and is exposed to the plasma 126. A thermal spray coating with high plasma resistance is formed on the surface of the upper replacement part 123 that is exposed to the plasma 126, and the other surfaces are anodized to provide corrosion resistance (anodized area 127).

[0028] In FIG. 1, the parts of the plasma processing chamber 111, the load lock chamber 102, and the vacuum transfer chamber 108 that are anodized are indicated by dashed lines as anodized areas 127, 128, 129, 133, and 134.

[0029] The lower replacement part 124 is mainly installed below the substrate 125 to be processed. The lower replacement part 124 has lower plasma resistance than the upper replacement part 123. However, since the lower replacement part 124 is exposed to reactive process gases or particle species generated by decomposition of the reactive process gases, the lower replacement part 124 needs to be corrosion resistant. For this reason, the lower replacement part 124 is partially or entirely anodized (anodized area 128).

[0030] Furthermore, the inner surface of the plasma processing chamber vessel 114 is anodized to provide corrosion resistance (anodized area 129). A base 130 for supporting a substrate and a plate-shaped aluminum part 131 for adjusting pressure are provided at the bottom of the plasma processing chamber 111. The base 130 and the plate-shaped aluminum part 131 are also anodized.

[0031] The substrate 125 to be processed, which has been processed in the plasma processing chamber 111, is transferred from the plasma processing chamber 111 through the vacuum transfer chamber 108 to the load lock chamber 102. During this transfer, corrosive gas also enters the interior of the vacuum transfer chamber 108 and the interior of the load lock chamber 102. The air or corrosive gas that has entered the interior of the vacuum transfer chamber 108 is gradually replaced by a purge gas. To prevent corrosion inside the load lock chamber 102 and the interior of the vacuum transfer chamber 108, the inner surface of the load lock chamber vessel 112, the wafer receiver 132, the connecting parts 107, the inner surface of the vacuum transfer chamber vessel 113, the surface of the vacuum robot 109, and the gate valves 103, 104, 105, and 106 are anodized (anodized area 133).

[0032] The concentration of corrosive gas diffusing from the plasma processing chamber 111 is higher inside the connection part 110 located between the plasma processing chamber 111 and the vacuum transfer chamber 108 than inside the vacuum transfer chamber 108. Therefore, in order to suppress corrosion inside the connection part 110, the connection part 110 is also anodized (anodized area 134).

[0033] <Method for Manufacturing Anodized Film> Manufacturing steps S201 to S204 included in the method for manufacturing an anodized film in embodiment 1 will be described below with reference to Fig. 2. Steps S201 to S204 are an example of the above-mentioned alumite treatment, and an anodized film (anodized aluminum coating) is manufactured by steps S201 to S204.

[0034] In the first embodiment, it is assumed that a user of the plasma processing apparatus 100 performs steps S201 to S204.

[0035] In the pretreatment step S201, first, a processed aluminum alloy substrate 205 is prepared. Next, crystallized materials on the surface of the substrate 205 are dissolved using an alkali or acid.

[0036] In the anodization step S202, an oxalic acid electrolyte is used to form a porous coating 206 on the substrate 205. The porous coating 206 has a plurality of pores 207, and the inner surface of each pore 207 is an inner surface 208 made of alumina.

[0037] In the sealing treatment step S203, the porous coating 206 is treated in water vapor at a pressure of 1 atmosphere or more and at 100°C or more. During this treatment, the alumina inner surface 208 becomes hydrated 209, increasing its volume, and the inside of the pores 207 is sealed with the hydrate 209. Continuing the sealing treatment step S203 further increases the amount of hydrate 209, and a hydrate layer 211 is formed on the top layer of the sealed porous coating 210. The anodic oxide coating 212 includes the hydrate layer 211 and the porous coating 210.

[0038] In the heat treatment step S204, the hydrate layer 211 and the porous coating 210 are subjected to heat treatment. This heat treatment is performed at a temperature of 120°C + a°C or higher for a time of 40 / (2 to the power of (a / 10)) minutes or longer (where 0≦a<30). This heat treatment also forms cracks 213 in the hydrate layer 211. The hydrate layer 211 with the cracks 213 formed therein becomes a hydrate layer 214 with at least the outermost surface altered. The anodic oxide coating 215 includes the altered hydrate layer 214 and the porous coating 210.

[0039] The deepest end of the crack 213 does not reach the substrate 205. In other words, the crack 213 is formed from the surface of the hydrate layer 214 to a depth that remains inside the hydrate layer 214, and even if the crack 213 is formed to the deepest position, it is formed from the surface of the hydrate layer 214 to a depth that remains inside the porous coating 210.

[0040] The thickness of the hydrate layer 211 (altered hydrate layer 214) is 0.2 μm or more and 1 μm or less. The thickness of the anodic oxide coating 215 including the hydrate layer 211 (altered hydrate layer 214) and the porous coating 210 is 20 μm or more and 30 μm or less.

[0041] Between the sealing treatment step S203 and the heat treatment step S204, the anodized film may be transported or stored during production, or the surface of the hydrate layer 211 may be washed with a cleaning solution containing water.

[0042] The anodized aluminum part having the thus formed anodic oxide film 215 and the substrate 205 can be applied to the anodized aluminum treatment areas 127, 128, 129, 133, and 134 in the plasma treatment apparatus 100 shown in FIG.

[0043] <Effect of Heat Treatment Step S204 on Foreign Matter> Below, the mechanism by which foreign matter is generated before heat treatment and the mechanism by which foreign matter is suppressed by heat treatment will be described using Comparative Examples 1 to 3. FIG. 3 shows anodized aluminum parts in Comparative Examples 1 to 3 and in Embodiment 1. Each anodized aluminum part has a base material made of an aluminum alloy and an anodized coating formed on the base material. Note that in the descriptions of Comparative Example 2, Embodiment 1, and Comparative Example 3, descriptions of parts that overlap with the structure of Comparative Example 1 will be omitted.

[0044] <<Anodized Aluminum Part of Comparative Example 1>> As shown in Fig. 3 , the anodic oxide coating 300 includes a hydrate layer 301 and a sealed porous coating 302. An abnormal portion 305 is present in the porous coating 302. The anodic oxide coating 300 is formed on a substrate 303. Crystallized matter 304 is present in the substrate 303.

[0045] In the case of the anodized aluminum part of Comparative Example 1, after the sealing treatment step S203, the heating treatment step S204 is not performed, but a cleaning step is performed, and a drying step is performed at 90° C. or less. Note that the anodized aluminum part of Comparative Example 1 also includes parts that were stored for several days or more after the drying step.

[0046] The anodized aluminum part of Comparative Example 1 was attached to a plasma processing apparatus, and the inside of the plasma processing apparatus was evacuated to a vacuum. A substrate for foreign matter inspection was transported into the plasma processing apparatus every three hours for two days, and the substrate for foreign matter inspection was held under the anodized aluminum part of Comparative Example 1 for a set period of time. The substrate for foreign matter inspection was then removed, and foreign matter inspection was performed. The size of the foreign matter detected was 25 nm or larger.

[0047] Fig. 4 shows the relationship between the number of foreign matters obtained from the anodized aluminum parts of Comparative Example 1 and Comparative Example 2 and the change over time. Fig. 5 shows SEM images (secondary electron images) of the surfaces of the anodized aluminum parts of Comparative Example 1 and Comparative Example 2, and also shows the results of calculating the total length of cracks. In Figs. 4 and 5, no heat treatment is performed in Comparative Example 1, but heat treatment is performed in Comparative Example 2.

[0048] As shown in Figure 4, in the case of the anodized aluminum part of Comparative Example 1, after evacuation, the number of foreign matter particles was initially large, but then gradually decreased over the next 42 hours. The presence or absence of cracks cannot be determined by visual inspection of the anodized aluminum part. Since the width of the cracks is at most about 50 nm, it is difficult to identify them even in SEM images. However, as shown in Figure 5, a certain threshold was set to extract the cracks.

[0049] 5 shows the state of the cracks "before evacuation evaluation" and the state of the cracks "after evacuation evaluation" 42 hours after evacuation. Each SEM image in FIG. 5 was acquired in an SEM observation range of approximately 110 μm horizontally and 77 μm vertically. The total length of the cracks in the foreign matter in Comparative Example 1 was 112 μm before evacuation, but increased to 531 μm after evacuation.

[0050] <<Anodized Aluminum Part of Comparative Example 2>> In the case of the anodized aluminum part of Comparative Example 2, the sealing treatment step S203 is followed by the heat treatment step S204. The heat treatment in Comparative Example 2 is performed at a temperature of less than 120°C, which is different from the temperature in Embodiment 1. As shown in Figure 3, in Comparative Example 2, a crack 306 is formed in the hydrate layer 301. The deep end of the crack 306 does not reach the substrate 303.

[0051] As shown in Figure 4, the anodized aluminum part of Comparative Example 2 was heat-treated in dry nitrogen at atmospheric pressure at 100°C for 2 hours. The anodized aluminum part of Comparative Example 2 was then cooled to room temperature and immediately evacuated and evaluated. Therefore, the anodized aluminum part of Comparative Example 2 was not exposed to a humid environment at room temperature. After evacuation, the number of foreign particles in the anodized aluminum part of Comparative Example 2 was smaller than that of Comparative Example 1, and remained almost unchanged over 42 hours. As shown in Figure 5, the total length of the cracks in the foreign particles in Comparative Example 2 was already 592 µm before evacuation.

[0052] Thus, the results of Comparative Examples 1 and 2 show that even if cracks exist in the anodized film, if the progression of the cracks is stopped beforehand, foreign matter will not be generated. Note that it is believed that foreign matter particles are generated the moment the cracks begin to progress in a vacuum.

[0053] Therefore, it may be considered appropriate to use an anodized film that has many cracks from the beginning, but in the past, there was concern that an anodized film with many cracks would have a trade-off between poor corrosion resistance and poor insulation properties the more cracks there are.

[0054] However, through detailed observations by the present inventors, it was found that, as shown in Comparative Example 2, if cracks 306 are present in the hydrate layer 301, which is an extremely thin surface layer of the anodic oxide coating 300, foreign matter can be suppressed, and there is no need for cracks in the porous coating 302. This has revealed that the trade-off between suppressing foreign matter and deterioration of corrosion resistance and insulation properties can be resolved.

[0055] The reason why cracks occur in the hydrate layer in a vacuum and foreign matter is generated is presumed to be as follows.

[0056] In Comparative Example 1, the material of the hydrate layer 301 and the material of the hydrate in the pores of the porous coating 302 are called boehmite or pseudo-boehmite. According to a weight loss evaluation by the inventors, these hydrates contain more water than boehmite. When such an anodized coating 300 is used in a vacuum, dehydration occurs from the hydrate, causing the hydrate layer 301 and the porous coating 302 to shrink. Because the hydrate layer 301 has a higher hydrate content than the porous coating 302 (see FIG. 2 ), the hydrate layer 301 experiences greater shrinkage.

[0057] If the temperature of the location where the anodized aluminum component is attached is high and the substrate 303 is heated, tensile stress will be generated due to the difference in thermal expansion between the substrate 303 and the anodic oxide coating 300. In other words, the linear expansion coefficient of the substrate 303 is generally greater than the contraction of the porous coating 302, so tensile stress will be generated in the anodic oxide coating 300. In this state, cracks will form starting from parts that cannot withstand the tensile stress among parts where stress is concentrated, such as irregularities and abnormal parts 305 on the surface of the anodic oxide coating 300.

[0058] The porous coating 302 is made of alumina and has a relatively high strength, while the hydrate layer 301 has a relatively low strength. Therefore, under non-excessive temperature conditions, cracks 306 are formed only in the hydrate layer 301.

[0059] The occurrence of the abnormal portions 305 is mainly due to precipitates (intermetallic compounds) that inevitably occur due to the additive elements of the aluminum alloy. Therefore, countless abnormal portions 305 exist inside and on the surface of the porous coating 302. The precipitates are intermetallic compounds containing iron (Fe) or magnesium (Mg). Therefore, the precipitates are more difficult to anodize than the aluminum alloy, or the precipitates are more easily anodized than the aluminum alloy, which often causes a difference in the film growth rate, resulting in the occurrence of the abnormal portions 305.

[0060] There may be a cavity containing a large amount of water or water vapor that was not filled during sealing near the abnormal portion 305. If a crack crosses the cavity and the cavity opens into a vacuum, water vapor or gas will likely erupt from the crack, scattering foreign matter.

[0061] The width of the crack 501 in the hydrate layer shown in Figure 5 is about 50 nm, but the size of the foreign matter detected is 25 nm to 50 nm. In other words, the width of the crack 501 is wide enough for the foreign matter to pass through. Although large foreign matter of 50 nm or larger is also present, it is possible that large foreign matter may be scattered from near the surface of the anodic oxide coating 300 due to the influence of the ejected gas.

[0062] In the anodized aluminum part of Comparative Example 2, there were numerous cracks 501 in the hydrate layer before evacuation, and as soon as evacuation began, gas was released from abnormal portions 305 that were connected to the vacuum by the cracks. After evacuation, no new cracks were generated, preventing foreign matter from scattering.

[0063] As described above, it is believed that the anodized aluminum part of Comparative Example 1 generated foreign matter when used in a vacuum, while the anodized aluminum part of Comparative Example 2 was able to suppress the generation of foreign matter.

[0064] <<Anodized Aluminum Part of First Embodiment>> In the case of the anodized aluminum part of the first embodiment, the sealing treatment step S203 is followed by the heat treatment step S204. This heat treatment is performed at a temperature of 120°C + a°C or higher for a time of 40 / (2 to the power of (a / 10)) minutes or longer (where 0≦a<30). Hereinafter, for ease of explanation, the heat treatment of the first embodiment may be referred to as "heat treatment at 120°C or higher." Note that this heat treatment temperature is for cases where excessive heating conditions are not met, and excessive heating conditions will be explained later.

[0065] 3, in the first embodiment, under these heating conditions, an altered hydrate layer 307 is formed in the uppermost layer of the porous coating 302. Furthermore, a crack 308 is formed in the hydrate layer 307. The deepest end of the crack 308 does not reach the substrate 303.

[0066] The difference between the heating conditions of Comparative Example 2 and those of Embodiment 1 will be described below with reference to FIG.

[0067] 6 shows the number of foreign particles generated inside the plasma processing apparatus 100 to which anodized aluminum parts were attached after heating under various conditions. The various conditions were heating times ranging from 20 minutes to 6 hours, and conditions in which the atmosphere was normal air or dry nitrogen in a clean room.

[0068] The horizontal axis of Figure 6 represents the temperature to which the anodized aluminum part was heated before being attached to the plasma processing apparatus 100. The vertical axis of Figure 6 represents the number of foreign particles normalized with the number of foreign particles without heat treatment as the reference 601. After the anodized aluminum part was attached to the plasma processing apparatus 100, the number of foreign particles was inspected every three hours for two days, and the median number of foreign particles over the two days was taken as the number of foreign particles for that part. A low number of foreign particles over the two days is very important for the productivity of the plasma processing apparatus 100.

[0069] The "without air exposure" in Fig. 6 indicates the number of foreign particles when the anodized aluminum part was heat-treated, cooled to room temperature, and immediately evacuated to a vacuum. The "with air exposure" in Fig. 6 indicates the number of foreign particles when the anodized aluminum part was heat-treated, left exposed to an air containing normal humidity for one to two weeks, attached to the plasma processing apparatus 100, and immediately evacuated to a vacuum.

[0070] When the anodized aluminum part was heat-treated at 100°C without air exposure, the number of foreign particles was less than that of standard 601, as shown in particle number 602, confirming the effect of reducing foreign particles. However, when the anodized aluminum part was heat-treated at 100°C or 110°C with air exposure, the number of foreign particles was similar to that of standard 601, as shown in particles 603 and 604, and the effect of reducing foreign particles was weakened.

[0071] On the other hand, in the case of "heat treatment at 120°C or higher" corresponding to the anodized aluminum part of embodiment 1, the number of foreign particles is less than the standard 601, as shown in foreign particle count group 605, and the foreign particle suppression effect is maintained. Specifically, heat treatment was performed in a normal clean room environment at 120°C for 1 hour, at 140°C for 1 hour, or at 130°C for 20 minutes, or in a dry nitrogen environment at 120°C for 2 hours or at 120°C for 1 hour. The atmospheric exposure time was also set to 2 weeks.

[0072] Thus, according to the first embodiment, even if the anodized aluminum component is exposed to the atmosphere for a certain period of time before evacuation, the generation of foreign matter after evacuation can be suppressed, and a corrosion-resistant anodized oxide film can be provided. Furthermore, a plasma processing apparatus 100 using an anodized aluminum component having such an anodized oxide film can be provided.

[0073] In the anodized aluminum part of Comparative Example 2, which was heat-treated at 110°C or less, the foreign matter suppression effect was lost due to exposure to the atmosphere. One possible cause is that the cracks may have closed again due to moisture absorption. The inventors of the present application have confirmed that the weight of the anodized aluminum part that was heat-treated at a temperature of 100°C returns to its original weight after cooling.

[0074] For example, there is knowledge about the stress of sulfate anodized aluminum coatings. It has been reported that tensile stress increases in sealed sulfate anodized aluminum coatings in low-humidity environments, and compressive stress increases in high-humidity environments. For this reason, it is thought that cracks close during exposure to the atmosphere and then reappear during use.

[0075] The reason why the anodized aluminum part of embodiment 1 has a foreign matter suppression effect even when exposed to the atmosphere is thought to be that the hydrate layer 301 is altered by heating at 120°C or higher, and the altered hydrate layer 307 prevents the crack 308 from closing even after exposure to the atmosphere.

[0076] Furthermore, from the changes in the TG (thermogravimetry) curves and DTA (differential thermal analysis) curves of the three types of pseudo-boehmite from about 130°C to 450°C, as well as from X-ray diffraction and infrared spectra, it is known that pseudo-boehmite thermally decomposes to γ-alumina through a dehydration reaction during temperature changes within the above temperature range. The heating rate during DTA measurement is generally about 1°C to 5°C per minute.

[0077] The heating temperature in the first embodiment is lower than 130°C. However, even if the heating temperature is 120°C, it is not inconsistent if thermal decomposition proceeds as long as the heating time is one hour or longer. That is, the "heat treatment at 120°C or higher" in the first embodiment causes the hydrate layer 214 in FIG. 2 or the hydrate layer 307 in FIG. 3 to be thermally denatured to γ-alumina.

[0078] It has also been reported that amorphous alumina (γ-alumina) remained unchanged for six months in saturated water vapor at room temperature (25° C.) This report provides evidence for the phenomenon discovered by the present inventors that the foreign matter suppression effect is maintained even after exposure to the atmosphere.

[0079] By maintaining the foreign matter suppression performance in this way, the timing of application of the heat treatment can be freely set. For example, the "heat treatment at 120°C or higher" of the first embodiment can be performed not only by the user of the plasma processing apparatus 100 but also by a parts manufacturer or a cleaning manufacturer. Furthermore, the "heat treatment at 120°C or higher" of the first embodiment can be performed after the plasma processing apparatus 100 arrives, before the date of installation of the apparatus.

[0080] It is also known that hydration progresses in a relatively short period of time when immersed in water. Therefore, when cleaning with a cleaning solution containing water after the "heat treatment at 120°C or higher" of embodiment 1, it is desirable to keep the time of wetting with water short. Furthermore, it is more desirable to clean with a cleaning solution containing water before the "heat treatment at 120°C or higher" of embodiment 1.

[0081] In the first embodiment, the evaluation was performed for up to two weeks of exposure to the atmosphere. However, considering the above-mentioned properties of γ-alumina at room temperature, it is expected that the properties of the altered hydrate layer 214 in Fig. 2 or the altered hydrate layer 307 in Fig. 3 will be maintained even after six months of exposure to the atmosphere.

[0082] In addition, in the first embodiment, the air exposure was carried out in a clean room without the anodized aluminum parts being sealed. The vinyl bags used to pack ordinary parts allow water vapor to gradually pass through, causing the water vapor partial pressure inside the vinyl bag to increase. Therefore, even when the anodized aluminum parts are stored sealed in vinyl bags, the same results as when they are exposed to the air can be obtained. Also, storing the anodized aluminum parts inside vinyl bags, or transporting them in vinyl bags, can prevent the adhesion of foreign matter.

[0083] The minimum heating conditions required in the first embodiment will be described below with reference to Fig. 7. Fig. 7 is a graph showing the relationship between the weight change of the anodized aluminum part due to dehydration and the heating time when the anodized aluminum part of the first embodiment is heated under atmospheric pressure.

[0084] As shown in Figure 7, when the heating temperature is 120°C, dehydration is completed in 40 minutes, and the weight is equivalent to that after 1 hour. When the heating temperature is 140°C, the same amount of water can be dehydrated in 10 minutes as when the heating temperature is 120°C.

[0085] In the thermal decomposition reaction of the surface of the hydrate layer, the reverse reaction of water molecules adhering can be ignored. In a high temperature environment of 120°C or higher and normal humidity, the reaction is considered to be a first-order chemical reaction in which water molecules leave the pseudo-boehmite, and the reaction rate increases exponentially with increasing temperature.

[0086] Considering the dehydration speed in Figure 7, in order to cause the thermal decomposition of the hydrate layer of an anodized aluminum part to be equivalent to 40 minutes at 120°C, the treatment should be performed for 20 minutes at 130°C and 10 minutes at 140°C, i.e., for 120°C + a°C, for a period of 40 ÷ (2 to the power of (a / 10)) minutes or more. In fact, it has been confirmed that even with a 20-minute heat treatment at 130°C, the foreign matter suppression effect is resistant to exposure to the atmosphere (see the number of foreign matters 606 in Figure 6). Furthermore, it goes without saying that even if there are temperature changes during the heat treatment, it is sufficient as long as the heat treatment is performed with the same intensity throughout the entire heat treatment process.

[0087] Furthermore, the material of the hydrate layer is pseudo-boehmite in all cases, regardless of the type of electrolyte (sulfuric acid, oxalic acid, etc.) used during anodization or the thickness of the anodized coating. Therefore, the minimum heating condition required is the temperature of the thermal decomposition reaction of pseudo-boehmite, and is independent of the specifications of the anodized coating. Furthermore, since the cracked hydrate layer is located in the outermost layer and is thin (approximately 1 μm), the dehydration time is also independent of the thickness of the anodized coating.

[0088] <<Method of Determining Heating Conditions>> As described above, the deep end of the crack does not reach the base material in the anodized aluminum component of embodiment 1. Below, steps S801 to S805 included in the method of determining heating conditions for achieving this will be described with reference to FIG.

[0089] 8, first, in step S801, a plurality of test pieces are prepared from a substrate made of an aluminum alloy. Since the state of crystallized matter varies depending on the substrate, the substrate of the test pieces is the same as the substrate of the anodized aluminum parts used in the plasma processing apparatus 100.

[0090] Next, in step S802, a plurality of test pieces are subjected to an anodizing treatment. That is, the plurality of test pieces are sequentially subjected to the pretreatment step S201, the anodizing step S202, and the sealing treatment step S203 shown in FIG. 2. As a result, an anodized coating including a hydrate layer and a porous coating is formed on the substrate.

[0091] Next, in step S803, the test pieces are subjected to separate heat treatments under various heating conditions in which the temperature is changed over a fixed time period, and at least four or more temperature conditions are set.

[0092] Next, in step S804, the admittance of the test piece is measured. Next, in step S805, although the admittance varies depending on the temperature, heating conditions are determined under which the admittance falls within an allowable range.

[0093] These heating conditions can be derived from the change curve of admittance showing the heating temperature dependency in Fig. 9A. An admittance within the allowable range is a value lower than the value exceeding the inflection point of the change curve in Fig. 9A. In other words, a heat treatment temperature within the allowable range is a temperature lower than the temperature exceeding the inflection point of the change curve in Fig. 9A.

[0094] 9A and 9B, we will explain how corrosion resistance can be evaluated by measuring admittance. Fig. 9A shows the relationship between the heating temperature of the test piece and the admittance after heating. Fig. 9B shows the relationship between the heating temperature of the test piece and the weight loss due to immersion in dilute hydrochloric acid after heating.

[0095] The admittance was measured in accordance with the JIS standard. The admittance was measured by measuring the ease with which a 1 kHz alternating current passed between the surface of the anodized film (the surface of the hydrate layer) and the substrate. The weight loss due to immersion in dilute hydrochloric acid was determined from the weight difference before and after immersing the test piece in dilute hydrochloric acid of a certain concentration for a certain period of time. In this evaluation, if there is a defect in the anodized film that leads to the substrate, the substrate dissolves, resulting in a weight loss of the substrate, and the corrosion resistance can be evaluated.

[0096] As shown in Figure 9A, the admittance increases slightly from 150°C. As shown in Figure 9B, the weight loss due to hydrochloric acid immersion worsens slightly at 150°C. From these results, temperatures below 150°C are within the allowable range. In this way, the corrosion resistance of the anodized film can be ensured by determining the heating conditions using a method that uses admittance measurements.

[0097] Fig. 10A is a cross-sectional SEM image of the anodized coating of a test piece heated in dry nitrogen at 150°C for 2 hours. Note that numerous cracks 1002 have formed in the hydrate layer 1001 within a range of several millimeters surrounding the cross-sectional SEM image of Fig. 10A, but no cracks have formed in the sealed porous coating 1003.

[0098] It is also possible to determine the temperature within the allowable range at which cracks do not reach the substrate by changing the heat treatment temperature multiple times, taking multiple cross-sectional SEM photographs for each temperature, and examining the depth of the cracks from the multiple cross-sectional SEM photographs. However, the method of determining the heating conditions so that the admittance falls within the allowable range allows for a more precise determination of the temperature within the allowable range than the method using multiple cross-sectional SEM photographs.

[0099] <<Anodized Aluminum Part of Comparative Example 3>> In the case of the anodized aluminum part of Comparative Example 3, the heat treatment step S204 is performed after the sealing treatment step S203. This heat treatment is performed at an excessive temperature of 200° C. for 2 hours.

[0100] As shown in Figure 3, in Comparative Example 3, these heating conditions resulted in the formation of cracks 309 in the hydrate layer 307 and the porous coating 302. The deep ends of the cracks 309 reached the substrate 303. When the heating conditions were at an excessively high temperature, the cracks 309 deteriorated the corrosion resistance. As shown in Figures 9A and 9B, when the heating temperature was 200°C, the admittance was very large, and the weight loss due to immersion in dilute hydrochloric acid was also large, indicating that the corrosion resistance was deteriorated.

[0101] 10B is a cross-sectional SEM image of the anodized coating of a test piece heated in dry nitrogen at 200° C. for 2 hours. Cracks 1006 were observed extending from the surface 1004 of the porous coating to the substrate 1005. When the cracks 1006 cross the porous coating 1007, they may be visible optically.

[0102] <<Regarding the Specification Range of the Anodized Film>> The thickness of the anodized film in the first embodiment may be 10 μm or more and 50 μm or less. The thicker the anodized film, the more likely it is that the corrosion resistance will be improved because the influence of abnormal parts present inside the anodized film can be reduced. The size of the crystallized particles and intermetallic compound particles present inside the substrate is affected by the amount of additive elements in the aluminum alloy that constitutes the substrate and the manufacturing process of the substrate.

[0103] The aluminum alloy used in the first embodiment is A5083 or A5052. Even with A6061 or A6082, which contain a large amount of crystallized material, corrosion resistance can be imparted by increasing the thickness of the anodized coating depending on the substrate. Furthermore, the heat resistance of sulfuric acid coatings is often lower than 120°C, while oxalic acid coatings tend to be more resistant to cracking due to heating (heat resistance).

[0104] The electrolyte used to form the porous coating may be a mixed acid or phosphoric acid. The porous coating formed using these electrolytes has a cell diameter equal to or larger than that of a porous coating formed using oxalic acid. Therefore, the heat resistance of a porous coating formed using a mixed acid or phosphoric acid is equivalent to that of a porous coating formed using oxalic acid. The cell diameter is the diameter of the cell surrounding each pore, and is approximately equal to the distance between adjacent pores in the porous coating.

[0105] Furthermore, if the sealing treatment is too short to form a hydrate layer, the pores in the porous coating are not sufficiently filled with the hydrate layer, resulting in poor corrosion resistance of the porous coating.On the other hand, if the sealing treatment is too long, hydration progresses on the inner surfaces of the pores, which are made of alumina, causing a decrease in the heat resistance of the sealed porous coating and an increase in the thickness of the hydrate layer.

[0106] Although a hydrate layer is required in the first embodiment, the thickness of the hydrate layer does not have to be within the range shown in the first embodiment. Even if the hydrate layer is thick, there is no problem as long as the heat resistance is higher than 120°C. Therefore, if the anodized coating after the sealing treatment step does not have heat resistance above 120°C, the results of the admittance evaluation of heat resistance can be fed back to the sealing conditions, and the sealing conditions can be weakened. Therefore, in this way, by measuring the admittance shown in the first embodiment, it is possible to determine the sealing conditions and heating conditions that provide corrosion resistance depending on the anodized coating.

[0107] The surface of the anodic oxide coating may be polished to remove fuzz (or powder) after sealing, as long as the hydrate layer remains. When a hydrate layer is formed on the top layer of a porous coating, either pressurized steam sealing or boiling water sealing may be used as the sealing treatment.

[0108] <<About Heating Conditions>> The heat treatment process requires evaporation of water, and heat treatment in an environment with extremely high water vapor pressure is not desirable. However, at 120°C, the method was effective in a normal humidity range, for example, at room temperature with a relative humidity of 50% or less. At 130°C, the saturated water vapor pressure increases by about 1.4 times, so it is expected that the method will be effective even at a relatively high humidity, such as a relative humidity of 70%.

[0109] The heating conditions must take into account the heat capacity of the part, and since it takes time to heat up, a time appropriate to the part is required. To alter the hydrate layer, the higher the temperature at which the anodized part is heat-treated, the shorter the heat treatment time can be. However, there is a risk that the part will not heat up in a short time, or that cracks will occur due to the difference in thermal expansion between the base material and the anodized film, resulting in a deterioration of corrosion resistance.

[0110] When measuring the admittance, evaluation was performed for different times (1 to 2 hours) and in different atmospheres with different water vapor partial pressures (dry nitrogen, normal humidity atmosphere), but similar graphs were obtained. In this way, it is possible to select the conditions that are most applicable.

[0111] <<Location of anodized aluminum components inside a plasma processing apparatus>> The inventors of the present application have clarified from the distribution of detected foreign matter that foreign matter generated from anodized aluminum components in a vacuum is scattered at a certain initial velocity (for example, 2 m / s). Therefore, foreign matter can adhere to a substrate being processed even in replaceable parts located below the substrate being processed, anodized aluminum components such as pressure adjustment plates that are not normally replaced, and anodized aluminum components used on the side walls of a vacuum transfer chamber.

[0112] The application of the heat treatment according to the first embodiment can provide a foreign matter suppression effect. The initial velocity of the foreign matter is caused by gases such as water vapor remaining in the abnormal portion of the porous coating when a crack occurs. As the gas is suddenly released into the vacuum, the foreign matter is given an initial velocity.

[0113] Unlike a vacuum transfer chamber, components installed in a vacuum processing chamber may require both corrosion resistance and insulation. Since admittance measurement is a method for measuring the ease with which AC current flows, the absence of deterioration in admittance means that both corrosion resistance and insulation can be maintained to a certain extent. Since minute foreign particles are carried from upstream to downstream by the gas flow, applying the anodized aluminum components of embodiment 1 to components located upstream of the purge gas can also achieve a foreign particle suppression effect.

[0114] The vacuum transfer chamber may be used without a purge gas flow. In such cases, foreign matter from the anodized aluminum components is likely to scatter with great force. Therefore, by applying the anodized aluminum components of the first embodiment to the vacuum transfer chamber, the effect of suppressing foreign matter can be obtained.

[0115] The risk of foreign matter from anodized aluminum parts varies depending on the base material material and the part temperature. Foreign matter can be effectively suppressed by using anodized aluminum parts that have been partially heat-treated only for parts that are hot or that generate a lot of foreign matter, and not using anodized aluminum parts that have been heat-treated for parts that use high-purity base materials that have a low risk of foreign matter.

[0116] In particular, in the case of conventional anodized aluminum parts, the temperature rises in connection parts, gate valves, and parts located inside the plasma processing chamber, which are temperature-controlled at 70° C. to 90° C., and dehydration proceeds faster than parts at room temperature. Therefore, there is a high risk of foreign matter from anodized aluminum parts that have not been treated with countermeasures, so by applying the anodized aluminum parts of embodiment 1, a foreign matter suppression effect can be obtained.

[0117] After the anodized aluminum part of the first embodiment was mounted in the plasma processing apparatus of the first embodiment, the amount of foreign matter generated gradually decreased after three hours. However, the amount of foreign matter increased when cracks began to form as the moisture was removed, and decreased when the cracks stopped growing.

[0118] Depending on the anodized coating, the amount of foreign matter may gradually increase and then gradually decrease, or the decrease in the amount of foreign matter may be slow. By applying the anodized aluminum part of embodiment 1, the cracks in the surface hydrate layer can be made to have moisture removed, which is effective in suppressing foreign matter in the early stages of evacuation. In other words, by applying the anodized aluminum part of embodiment 1, the plasma processing apparatus of embodiment 1 can reduce the amount of foreign matter generated in the early stages of evacuation.

[0119] 2 is performed by the user of the plasma processing apparatus 100, the execution of the heat treatment step S204 is not limited to the user of the plasma processing apparatus 100. Modifications 1 to 4 below will describe embodiments in which the user of the plasma processing apparatus 100 or another person performs the heat treatment step S204.

[0120] (Modification 1) Modification 1 of the first embodiment will be described below with reference to Fig. 11. In Fig. 11, a step corresponding to the heat treatment step S204 in Fig. 2 will be described as a heat treatment step S1104.

[0121] In the first modification, the parts supplier or cleaning manufacturer performs the heat treatment step S1104, and then delivers new anodized aluminum parts to the plasma processing apparatus manufacturer or plasma processing apparatus user.

[0122] 11 , in a conventional process, a parts supplier processes the substrate of an anodized aluminum part (step S1101), performs surface treatment on the surface of the anodized aluminum part (step S1102), and delivers the anodized aluminum part to a plasma processing equipment manufacturer. The plasma processing equipment manufacturer then installs the part in a plasma processing equipment (step S1103). Before installation in the plasma processing equipment, the plasma processing equipment manufacturer may also clean the anodized aluminum part.

[0123] As shown in Example A of FIG. 11, the parts supplier performs a heat treatment step S1104 on the anodized aluminum parts before delivery.

[0124] 11, after the surface treatment step S1102, the parts supplier delivers the anodized aluminum parts to a cleaning manufacturer. The cleaning manufacturer cleans the anodized aluminum parts (step S1105) and performs a heat treatment step S1104 on the anodized aluminum parts. The cleaning manufacturer then delivers the anodized aluminum parts to a plasma processing equipment manufacturer. In the cleaning step S1105, the surface of the hydrate layer is cleaned with a cleaning solution containing water.

[0125] The same flow as in Examples A and B can also be applied when a replacement part for a plasma processing apparatus, rather than a new anodized aluminum part, is delivered from a parts supplier to a plasma processing apparatus user.

[0126] If the heat treatment step S1104 is performed in a location different from the location where step S1103 is performed, the anodized aluminum part is exposed to normal humidity for several days or more until step S1103 is performed. If the heat treatment temperature is lower than 120° C., the foreign matter suppression effect may be lost, but the heat treatment step S1104 can maintain the foreign matter suppression effect.

[0127] Therefore, the plasma processing apparatus manufacturer or the plasma processing apparatus user does not need to install equipment for performing the heat treatment step S1104, and can operate in the same manner as before.

[0128] New anodized aluminum parts include parts that are difficult to replace and parts that are easy to replace (replacement parts). Large parts that are difficult to replace include, for example, the vacuum robot 109, the container 112 for the load lock chamber, the container 113 for the vacuum transfer chamber, and the container 114 for the vacuum processing chamber (see FIG. 1). Replacement parts include, for example, the upper replacement part 123 or the lower replacement part 124 (see FIG. 1).

[0129] (Modification 2) Modification 2 of the first embodiment will be described below with reference to Fig. 12. In Fig. 12, a step corresponding to the heat treatment step S204 in Fig. 2 will be described as a heat treatment step S1202.

[0130] In some cases, a plasma processing apparatus manufacturer or a plasma processing apparatus user has equipment capable of performing a heat treatment process on anodized aluminum parts. In the second modification, a parts supplier delivers normal anodized aluminum parts to a plasma processing apparatus manufacturer and / or a plasma processing apparatus user (step S1201).

[0131] 12 , in an example of the second modification, a plasma processing apparatus manufacturer performs a heat treatment step S1202 on anodized aluminum parts delivered from a parts supplier. The plasma processing apparatus manufacturer prepares other parts for the plasma processing apparatus in advance (step S1203), and assembles the plasma processing apparatus by combining the anodized aluminum parts that have been subjected to the heat treatment step S1202 with the other parts (step S1204). The plasma processing apparatus manufacturer delivers the plasma processing apparatus to a plasma processing apparatus user, and installs the plasma processing apparatus at the plasma processing apparatus user site (step S1205).

[0132] After step S1205, the plasma processing apparatus manufacturer performs various inspections at the user site, including checking for foreign matter in the plasma processing apparatus (step S1207).

[0133] A cleaning step or a storage period may be performed before or after the heat treatment step S1202. When a cleaning step is performed after the heat treatment step S1202, whether or not the foreign matter suppression effect is completely lost depends on the cleaning conditions. Therefore, it is desirable to perform the cleaning step before the heat treatment step S1202. The cleaning step performed before the heat treatment step S1202 can be performed by a parts supplier, a cleaning manufacturer, or the like. In such a cleaning step, the surface of the hydrate layer is usually cleaned with a cleaning liquid containing water.

[0134] In another example of the second modification, a plasma processing apparatus manufacturer installs a plasma processing apparatus at a plasma processing apparatus user site as usual. The plasma processing apparatus user performs a heat treatment step S1202 on anodized aluminum parts delivered from a parts supplier. The plasma processing apparatus user replaces the anodized aluminum parts of the plasma processing apparatus with heat-treated anodized aluminum parts (step S1206) and checks the plasma processing apparatus for foreign matter (step S1207). The plasma processing apparatus user then performs product processing (substrate processing) (step S1208).

[0135] During maintenance of the plasma processing apparatus, the user of the plasma processing apparatus opens each processing chamber of the plasma processing apparatus to the atmosphere (step S1209). The user of the plasma processing apparatus performs a heat treatment step S1202 on replacement parts delivered in advance from a parts supplier and stores the parts.

[0136] The user of the plasma processing apparatus mounts the anodized aluminum component that has been subjected to the heat treatment step S1202 (step S1210), checks the plasma processing apparatus for foreign matter (step S1211), and then performs product processing (substrate processing) (step S1212).

[0137] Modification 2 is suitable for cases where the parts supplier does not have sufficient means to perform the heat treatment step S1202 and where the heat treatment step S1202 can be performed at the plasma processing equipment user site. Also, by performing the heat treatment step S1202 near the user's plasma processing equipment, it is easier to maintain the temperature of the anodized aluminum parts at room temperature during storage, and a stable foreign matter suppression effect can be obtained during the foreign matter check steps S1206 and S1209.

[0138] (Modification 3) Modification 3 of the first embodiment will be described below with reference to Fig. 13. In Fig. 13, a step corresponding to the heat treatment step S204 in Fig. 2 will be described as a heat treatment step S1307.

[0139] The third modification is suitable for replacing some parts of a plasma processing apparatus and cleaning or regenerating the replaced parts.

[0140] 13 , a user of the plasma processing apparatus performs product processing (substrate processing) (step 1301). Thereafter, during maintenance of the plasma processing apparatus, the user opens each processing chamber to the atmosphere (step S1302), removes the replacement part (step S1303), installs a new replacement part (step S1304), checks the anodized parts for foreign matter (step S1305), and performs product processing (substrate processing) (step 1306).

[0141] In step S1302, the plasma processing apparatus user removes the used replacement part and sends it to a cleaning manufacturer or a parts remanufacturing manufacturer. The cleaning manufacturer or parts remanufacturing manufacturer remanufactures the replacement part (step S1307) and / or cleans the replacement part (step S1308). Thereafter, the cleaning manufacturer or parts remanufacturing manufacturer performs a heat treatment step S1309 on the replacement part. In the cleaning step S1308, the surface of the hydrate layer is cleaned with a cleaning solution containing water.

[0142] In the third modification, by performing the heating treatment step S1309 at the cleaning manufacturer or parts remanufacturing manufacturer, even if hydration occurs on the surface of the anodic oxide coating (the surface of the hydrate layer) when a used anodized aluminum part is cleaned (step S1308), it is possible to provide a foreign matter suppression effect during the foreign matter check step S1305.

[0143] (Modification 4) Modification 4 of the first embodiment will be described below with reference to Figures 14 and 15. In Figure 14, a step corresponding to the heat treatment step S204 in Figure 2 will be described as a heat treatment step S1401.

[0144] The fourth modification relates to a plasma processing apparatus that can suppress foreign matter not only when an anodized aluminum part is first used, but also after the part is opened to the atmosphere during maintenance.

[0145] As shown in FIG. 14, the plasma processing apparatus user installs the plasma processing apparatus received from the plasma processing apparatus manufacturer (step S1403), checks for foreign matter on the anodized aluminum parts (step S1404), and performs product processing (substrate processing) (step S1405).

[0146] When each processing chamber is opened to the atmosphere during maintenance of the plasma processing apparatus (steps S1406 and S1409), if no foreign matter is detected in the foreign matter check (steps S1407 and S1410), product processing (substrate processing) is performed (steps S1408 and S1411), but foreign matter may be detected again. An example of maintenance of the plasma processing chamber 111 will be described below with reference to FIG. 15.

[0147] 15 shows the state of the plasma processing chamber 111 opened to the atmosphere during maintenance. As shown in FIG. 15, before opening the plasma processing chamber 111 to the atmosphere, the vacuum transfer chamber 108 is separated from the atmosphere by the gate valve 105 of the vacuum transfer chamber 108, thereby maintaining a vacuum inside the vacuum transfer chamber 108. If the plasma processing chamber 111 is opened to the atmosphere in this state (step S1406), the connecting part 110, the plasma processing chamber container 114, the base 130, the plate-shaped aluminum part 131, and the like are exposed to the atmosphere. However, it is difficult to replace the anodized aluminum parts used in these components.

[0148] Therefore, at the plasma processing apparatus manufacturer, these anodized aluminum parts are subjected to a heat treatment step S1401 before assembling the plasma processing apparatus (step S1402). As a result, even if the anodized aluminum parts are exposed to the atmosphere during maintenance or modification of the plasma processing apparatus, the cracks in the anodic oxide film remain altered, so the generation of foreign matter is suppressed during the foreign matter check step S1407.

[0149] Similarly, when the vacuum transfer chamber 108 is opened to the atmosphere during maintenance of the vacuum transfer chamber 108 (step S1409), the container 113 for the vacuum transfer chamber, the vacuum robot 109, and the like are exposed to the atmosphere. However, it is difficult to replace the anodized aluminum parts used in these components.

[0150] Even for such anodized aluminum parts, the plasma processing apparatus manufacturer performs the heat treatment step S1401 before assembling the plasma processing apparatus (step S1402), thereby suppressing the generation of foreign matter in the foreign matter check step S1410.

[0151] Unlike the above configuration, if there is an insulating structure between components that need to be protected from heating, it may be possible to heat the plasma processing apparatus on the spot by installing a heater in the plasma processing apparatus or by installing a temporary heater when starting up the plasma processing apparatus. In this case, the "heating process at 120°C or higher" may be performed after assembling the plasma processing apparatus. However, since foreign matter will be generated if the temperature remains high, it is necessary to lower the temperature to a normal temperature after the heating process until the substrate to be processed is processed. This prevents the generation of foreign matter after maintenance, even when the apparatus is opened to the atmosphere during the next maintenance.

[0152] The present invention has been specifically described above based on the above embodiment, but the present invention is not limited to the above embodiment and can be modified in various ways without departing from the spirit of the present invention.

[0153] For example, the configuration of the plasma processing apparatus is not limited to the configuration described in this specification, and many components such as O-ring seals installed between components to maintain a vacuum and exhaust valves are omitted.

[0154] The heat treatment step can be carried out directly or indirectly by using a baking oven, attaching an electric heater to the part, or using hot air, a heat lamp, or electromagnetic waves.

[0155] Furthermore, those who can perform the heat treatment process are not limited to plasma processing apparatus users, plasma processing apparatus manufacturers, parts suppliers, cleaning manufacturers, or regeneration manufacturers.

[0156] 100 Plasma processing apparatus 101 EFEM 102 Load lock chamber 103, 104, 105, 106 Gate valve 107 Connection part 108 Vacuum transfer chamber 109 Vacuum robot 110 Connection part 111 Plasma processing chamber 112 Container for load lock chamber 113 Container for vacuum transfer chamber 114 Container for plasma processing chamber 115, 116, 117 Exhaust part 118 Purge gas supply part 119 Substrate to be processed 120 Process gas supply part 121 Processing power supply part 122 Temperature control heater 123 Upper replacement part 124 Lower replacement part 125 Substrate to be processed 126 Plasma 127, 128, 129 Anodized aluminum treatment area 130 Base 131 Plate-shaped aluminum part 132 Wafer holder 133, 134 Anodized area 205 Substrate 206 Porous coating 207 Hole 208 Alumina inner surface 209 Hydrate 210 Sealed porous coating 211 Hydrate layer 212 Anodized coating 213 Crack 214 Altered hydrate layer 215 Anodized coating 300 Anodized coating 301 Hydrate layer 302 Sealed porous coating 303 Substrate 304 Crystallized substance 305 Abnormal part 306 Crack 307 Altered hydrate layer 308, 309 Crack 501 Crack 601 Criterion 602, 603, 604, 606 Number of foreign particles 605 Group of foreign particle counts 1001 Hydrate layer 1002 Crack 1003 Sealed porous coating 1004 Surface of porous coating 1005 Substrate 1006 Crack 1007 Sealed porous coating

Claims

1. (a) A step of preparing a substrate made of an aluminum alloy, (b) a step of forming a porous film on the substrate, (c) a step of forming a hydrate layer on the outermost layer of the porous film, (d) a step of performing a heat treatment on the hydrate layer and the porous film, comprising: The heat treatment is performed at a temperature of 120 °C + a °C or higher and a time of 40 / (2 ^ (a / 10)) minutes or longer (where 0 ≤ a < 30), and cracks are formed in the hydrate layer by the heat treatment. A method for manufacturing an anodic oxide film.

2. In the method for manufacturing an anodic oxide film according to claim 1, the deep end of the crack does not reach the substrate. A method for manufacturing an anodic oxide film.

3. In the method for manufacturing an anodic oxide film according to claim 1, the temperature of the heat treatment is set to a temperature lower than the temperature exceeding the inflection point of the change curve showing the heating temperature dependence of the admittance between the surface of the hydrate layer and the substrate in the change curve. A method for manufacturing an anodic oxide film.

4. In the method for manufacturing an anodic oxide film according to claim 1, the hydrate layer is modified to γ-alumina. A method for manufacturing an anodic oxide film.

5. In the method for manufacturing an anodic oxide film according to claim 1, the thickness of the hydrate layer is 0.2 μm or more and 1 μm or less. A method for manufacturing an anodic oxide film.

6. In the method for manufacturing an anodic oxide film according to claim 1, in the step (b), an oxalic acid electrolyte is used. A method for manufacturing an anodic oxide film.

7. In the method for manufacturing an anodic oxide film according to claim 1, further comprising: (e) a step of washing the surface of the hydrate layer with a cleaning liquid containing water between the step (c) and the step (d). A method for manufacturing an anodic oxide film.

8. In the method for manufacturing an anodic oxide film according to claim 1, further comprising: (f) a step of washing the surface of the hydrate layer with a cleaning liquid containing water after the step (d). A method for manufacturing an anodic oxide film.

9. In the method for manufacturing an anodic oxide film according to claim 1, the steps (a), (b), (c) and (d) are performed on the components of the plasma processing chamber and the components of the vacuum transfer chamber provided in the plasma processing apparatus. A method for manufacturing an anodic oxide film.

10. An anodized part comprising a substrate made of an aluminum alloy, a porous film formed on the substrate, and a hydrate layer formed on the uppermost layer of the porous film, wherein cracks are formed in the hydrate layer and the deep ends of the cracks do not reach the substrate.

11. The anodized part according to claim 10, wherein the hydrate layer is modified to γ-alumina.

12. The anodized part according to claim 10, wherein the thickness of the hydrate layer is 0.2 μm or more and 1 μm or less.

13. A plasma processing apparatus comprising the anodized part according to claim 10, the plasma processing apparatus comprising a plasma processing chamber and a vacuum transfer chamber, wherein the anodized part is used for parts in the plasma processing chamber and parts in the vacuum transfer chamber.

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