Film formation method, member manufacturing method, and plasma processing apparatus comprising member

Abstract

The present disclosure relates to a method for forming a film on a metal member, the method including the following steps.　A first step for forming linear recesses at prescribed intervals on the surface of the metal member, a second step for forming an anodic oxide film on the surface of the metal member on which the recesses are formed, a third step for heat-treating the metal member on which the anodic oxide film is formed to form cracks in the anodic oxide film, and a fourth step for sealing the metal member on which the anodic oxide film is formed to fill the cracks with a hydrate.　Furthermore, the present disclosure also includes a method for manufacturing a member manufactured using the aforementioned film formation method, and a plasma processing device comprising the member.

Description

Film formation method, method for manufacturing a member, and plasma processing apparatus including the member

[0001] The present invention relates to a film formation method, a method for manufacturing a member, and a plasma processing apparatus including the member.

[0002] In microfabrication centered on semiconductor devices, foreign substances at the submicron level may affect each manufacturing process. For example, when foreign substances adhere to a wafer on which a semiconductor device is formed, electrical circuit abnormalities may occur due to the adhered foreign substances. As a result, this has an adverse effect on the manufacturing yield of semiconductor devices.

[0003] In plasma processing apparatuses used for manufacturing semiconductor devices and the like, foreign substances are generated due to various factors. For example, in a vacuum transfer container that constitutes a plasma processing apparatus, when minute particles or the like peel off from the wall surface of the apparatus and fall during the transfer of a wafer, they become foreign substances on the wafer. Plasma processing apparatuses are composed of various materials, but aluminum-based materials are often used because they are easy to process and lightweight. And, anodic oxidation treatment is often performed on aluminum-based materials for the purpose of suppressing corrosion of the material processing surface and the like.

[0004] When anodic oxidation treatment is performed on aluminum, the surface may form a porous shape and cracks called microcracks may be formed, and there is concern that these may be factors in the generation of foreign substances.

[0005] Patent Document 1 addresses the problem of suppressing the generation of fine particles from a component by applying an oxalic acid-based anodizing treatment to the component constituting the semiconductor processing apparatus, and discloses the following invention for a vacuum processing apparatus: "A vacuum processing apparatus comprising a plurality of vacuum processing chambers for vacuum processing wafers, a vacuum transport container equipped with a vacuum transport means for loading and unloading wafers into and out of each vacuum processing chamber, a load lock chamber that can be switched between an atmospheric atmosphere and a vacuum atmosphere for loading and unloading wafers into and out of each vacuum processing chamber, a cassette mounting means capable of mounting a plurality of cassettes capable of storing wafers, and an atmospheric transport means configured to allow wafers to be removed from any cassette on the cassette mounting means, wherein wafers in any cassette are loaded into each vacuum processing chamber via the atmospheric transport means, the switchable load lock chamber, and the vacuum transport means, and processed wafers that have been vacuum processed in each vacuum processing chamber are unloaded, wherein the inner surface of the component constituting the vacuum transport container 6 is subjected to an oxalic acid-based anodizing treatment."

[0006] Furthermore, Patent Document 2 aims to provide a method for forming an anodized aluminum film and an aluminum component that can suppress initial particles generated from an aluminum component on which an anodized film is formed on the surface. The following is disclosed as an invention of a plasma processing container internal component and a plasma processing container internal component manufactured thereby: "A method for manufacturing a plasma processing container internal component, which is disposed in a plasma processing container on which a workpiece is subjected to plasma processing, comprises an anodized film forming step (S3) of forming an anodized film on the surface of an aluminum substrate, a sealing step (S4) of sealing pores formed in the anodized film, and a heat treatment step (S5) of heating the anodized film after performing the sealing step."

[0007] Japanese Patent Publication No. 2010-50405 Japanese Patent Publication No. 2004-292887

[0008] However, even with the oxalic acid-based anodic oxidation treatment described in Patent Document 1, the suppression of foreign matter generation was insufficient, and even with the heat treatment technique described in Patent Document 2, the heat generated during the operation of the device caused the coating to be stretched due to the difference in the coefficient of linear expansion between the coating and the substrate, leaving room for new cracks to occur. Furthermore, there was a risk that foreign matter would be generated by these newly formed cracks. Therefore, the present invention aims to provide an anodic oxidation technique that suppresses the generation of foreign matter by preventing the occurrence of new cracks in the coating during the operation of the device.

[0009] To solve the above problems, one representative method of forming a coating or manufacturing a member according to the present invention comprises: a first step of forming linear recesses at predetermined intervals on the surface of a metal member; a second step of forming an anodic oxide film on the surface of the metal member having the recesses; a third step of heat-treating the metal member on which the anodic oxide film has been formed to form cracks in the anodic oxide film; and a fourth step of sealing the metal member on which the anodic oxide film has been formed to fill the cracks with a hydrate.

[0010] Furthermore, in order to solve the above problems, one of the representative plasma processing apparatuses of the present invention includes a member equipped with an anodic oxide film, wherein linear recesses are formed at predetermined intervals on the surface of the base material of the member. The anodic oxide film is formed on the upper surface of the base material, and cracks are formed in the anodic oxide film above the linear recesses, and hydrates are filled into the cracks.

[0011] According to the present invention, it is possible to provide an anodizing technology that suppresses the generation of foreign matter by preventing the occurrence of new cracks in the coating during the operation of the device. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments for carrying out the invention.

[0012] Figure 1 is a schematic diagram of a plasma processing apparatus. Figure 2 is a graph showing the relationship between the thickness of the anodic oxide film and the heating temperature. Figure 3 is a flowchart of the film formation method. Figure 4 is an external view when a linear notch is formed as a recess in the base material. Figure 5 is a cross-sectional view of a member on which an anodic oxide film has been formed. Figure 6 is a cross-sectional view showing cracks that occurred after heat treatment. Figure 7 is an enlarged view of section A in Figure 6. Figure 8 is an enlarged view of a cross-section near the anodic oxide film after sealing treatment. Figure 9 is a graph showing the relationship between the thickness of the anodic oxide film and the crack spacing.

[0013] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited by these embodiments. In the drawings, identical parts are denoted by the same reference numeral. When there are multiple components having the same or similar function, different subscripts may be used for the same reference numeral. Furthermore, if it is not necessary to distinguish between these multiple components, the subscript may be omitted. Also, terms such as "first," "second," and "third" may be used in this disclosure to describe various elements or components, but these elements or components should not be limited by these terms. These terms are used solely to distinguish one element or component from another. Therefore, the first element or component used in this disclosure may also be called the second element or component without departing from the teaching of the concept of the present invention. The position, size, shape, and range of each component shown in the drawings may not represent the actual position, size, shape, and range in order to facilitate understanding of the invention. For this reason, the present invention is not necessarily limited to the position, size, shape, and range disclosed in the drawings.

[0014] In this disclosure, "surface" may refer not only to the surface of the plate-like member, but also to the interface of a layer contained within the plate-like member that is substantially parallel to the surface of the plate-like member. Furthermore, "upper surface" and "lower surface" refer to the surface shown above or below in the drawing when the plate-like member or a layer contained within the plate-like member is illustrated.

[0015] Furthermore, "upward" refers to the vertically upward direction when a plate-like member or layer is placed horizontally. In addition, "upward" and its opposite, "downward," may be referred to as the "positive Z-axis direction" and the "negative Z-axis direction," respectively, while the horizontal direction may be referred to as the "X-axis direction" and the "Y-axis direction."

[0016] Furthermore, the term "layer" does not necessarily refer to a state in which the materials constituting the layer are uniformly arranged. It may also refer to a pattern with gaps or a collection of island-like regions.

[0017] (Meaning of terms) "Saturated crack temperature" refers to the temperature at which the number of cracks generated stops increasing as the heating temperature rises. The number of cracks generated at the saturated crack temperature is sometimes called the "saturated crack number." "Saturated crack temperature (50%)" refers to the temperature at which the number of cracks generated reaches 50% of the saturated crack number. The number of cracks generated at the saturated crack temperature is sometimes called the "saturated crack number (50%)."

[0018] First, with reference to Figure 1, an overview of the configuration of the plasma processing apparatus according to the present disclosure will be described.

[0019] (Embodiment 1) <Plasma Processing Equipment> The structures included in the plasma processing equipment 100 in Embodiment 1 will be described below with reference to Figure 1.

[0020] As shown in Figure 1, the plasma processing apparatus 100 mainly comprises an EFEM (Equipment Front End Module) 101, a load lock chamber 102, gate valves 103-106, connecting components 107, a vacuum transport chamber 108, a vacuum robot 109, connecting components 110, and a plasma processing chamber 111. The container 112 for the load lock chamber, the container 113 for the vacuum transport chamber, and the container 114 for the plasma processing chamber are mainly made of aluminum alloy.

[0021] When the plasma processing apparatus 100 is installed, or when parts used in the plasma processing apparatus 100 are replaced, the plasma processing apparatus 100 is exposed to the atmosphere, either entirely or partially. Subsequently, moisture adsorbed on the internal components of the load lock chamber 102, vacuum transport chamber 108, and plasma processing chamber 111 are exhausted by exhaust units 115, 116, and 117.

[0022] Once the plasma processing apparatus 100 passes performance tests such as foreign matter suppression or 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's machinery. The gate valve 103 isolates the load lock chamber 102 from the atmosphere. The gate valve 104 isolates the load lock chamber 102 from the vacuum transport chamber 108. The exhaust unit 115 exhausts the inside of the load lock chamber 102 and creates a vacuum inside the load lock chamber 102.

[0023] The exhaust unit 116 evacuates the inside of the vacuum transport chamber 108, creating a vacuum inside the vacuum transport chamber 108. The purge gas supply unit 118 supplies dry purge gas to the inside of the vacuum transport chamber 108 at a constant flow rate. Alternatively, the supply of dry purge gas maintains a constant pressure inside the vacuum transport chamber 108. The dry purge gas can be, for example, argon, dry nitrogen, or dry air.

[0024] The reduced-pressure gas inside the vacuum transport chamber 108 is continuously or intermittently replaced by a dry purge gas. After the gate valve 104 is opened, the vacuum robot 109 transports the substrate 119 to be processed from the load lock chamber 102 to the plasma processing chamber 111. In some cases, the substrate 119 is transported without supplying purge gas to the inside of the vacuum transport chamber 108.

[0025] The plasma processing chamber 111 includes a container 114 for the plasma processing chamber, a process gas supply unit 120, a processing 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 aluminum alloy.

[0026] The interior of the plasma processing chamber 111 is controlled by a temperature control heater 122 to maintain a temperature between 70°C and 100°C in order to stabilize processing performance and prevent the removal of deposits adhering to the inner walls. The process gas supply unit 120 supplies process gas to the interior of the plasma processing chamber 111.

[0027] The process gas includes a reactive process gas and an inert gas such as argon or nitrogen. The reactive process gas includes one or all of the following: chlorine molecules, hydrogen chloride, boron trichloride, hydrogen bromide, molecules containing chlorine atoms that decompose and become corrosive, or molecules containing bromine atoms. By closing the gate valve 106 of the connecting component 110 before at least the reactive process gas is supplied into the plasma processing chamber 111, it is possible to prevent the reactive process gas from flowing from the plasma processing chamber 111 into the vacuum transfer chamber 108.

[0028] Inside the plasma processing chamber 111, plasma 126 is generated by process gas and electromagnetic waves supplied from the processing power supply unit 121. The substrate 125 to be processed is processed by the plasma 126.

[0029] The upper replacement part 123 is mainly installed above the substrate 125 to be processed and is exposed to the plasma 126. The surface of the upper replacement part 123 exposed to the plasma 126 is coated with a highly plasma-resistant thermal spray coating, while the other surfaces are anodized to provide corrosion resistance (anodic oxidation treatment area 127).

[0030] In Figure 1, the parts of the plasma processing chamber 111, load lock chamber 102, and vacuum transport chamber 108 that have undergone anodizing treatment are indicated by dashed lines as anodizing treatment regions 127, 128, 129, 133, and 134.

[0031] The lower replacement part 124 is mainly located below the substrate 125 being processed. The lower replacement part 124 has lower plasma resistance compared to the upper replacement part 123. However, since the lower replacement part 124 is exposed to reactive process gases or particulate matter from the decomposition of reactive process gases, corrosion resistance is required for the lower replacement part 124. For this reason, the lower replacement part 124 is partially or entirely anodized (anodic oxidation treatment area 128).

[0032] Furthermore, the inner surface of the container 114 for the plasma processing chamber is anodized (anodic oxidation treatment area 129) because corrosion resistance is required. In addition, a base 130 for mounting the substrate and a plate-shaped aluminum part 131 for pressure adjustment are provided at the bottom of the plasma processing chamber 111. The base 130 and the plate-shaped aluminum part 131 are also anodized.

[0033] The substrate 125 processed in the plasma processing chamber 111 is transported from the plasma processing chamber 111 through the vacuum transport chamber 108 to the load lock chamber 102. During this process, corrosive gases also enter the interior of the vacuum transport chamber 108 and the load lock chamber 102. The air or corrosive gases that enter the interior of the vacuum transport chamber 108 are gradually replaced by a purge gas. To suppress corrosion inside the load lock chamber 102 and the vacuum transport chamber 108, the inner surface of the container 112 for the load lock chamber, the wafer holder 132, the connecting parts 107, the inner surface of the container 113 for the vacuum transport chamber, the surface of the vacuum robot 109, and the gate valves 103, 104, 105, and 106 are subjected to anodizing treatment (anodic oxidation treatment area 133).

[0034] The concentration of corrosive gases diffusing from the plasma processing chamber 111 is higher inside the connecting component 110, which is located between the plasma processing chamber 111 and the vacuum transport chamber 108, than inside the vacuum transport chamber 108. Therefore, in order to suppress corrosion inside the connecting component 110, the connecting component 110 is also subjected to anodizing treatment (anodic oxidation treatment area 134).

[0035] <Crack formation due to heating> Next, we will explain the crack formation mechanism for a component in which an anodic oxide film is formed on a base material made of aluminum alloy. When a component with an anodic oxide film is placed under high temperatures, tensile stress is generated due to the difference in thermal expansion between the base material aluminum alloy and the anodic oxide film. Generally, the coefficient of linear expansion of aluminum alloy is greater than the coefficient of expansion of the anodic oxide film, so tensile stress is generated in the anodic oxide film at high temperatures. Then, in the anodic oxide film, cracks are formed starting from areas where stress is concentrated, such as surface irregularities or abnormal areas, and which cannot withstand the tensile stress.

[0036] Here, abnormal areas are mainly caused by precipitates (intermetallic compounds) formed by the additive elements in the aluminum alloy. These abnormal areas are countless parts with different physical properties that exist inside and on the surface of the anodized film. Since precipitates are intermetallic compounds containing iron (Fe) or magnesium (Mg), it is believed that abnormal areas with different physical properties arise due to differences in film growth rates, either because the precipitates are less easily anodized than the aluminum alloy, or because they are more easily anodized than the aluminum alloy.

[0037] Near the abnormal area, there may be cavities containing a large amount of water or water vapor. When a crack crosses such a cavity, it is thought that the cavity opens into a vacuum, causing water vapor or gas to erupt from the crack and foreign matter to scatter.

[0038] Figure 2 shows the crack formation process. Figure 2 shows the crack formation process when a component made of aluminum alloy A5083, which has been anodized using an oxalic acid-based solution to form a film on its surface, is subjected to heat treatment. The y-axis represents the heating temperature, and the x-axis represents the thickness of the anodized film. Note that the component in Figure 2 has not undergone sealing treatment. For anodized film thicknesses of 17 μm, 25 μm, 26 μm, and 27 μm, the temperature at which crack formation began is indicated by a ●, the temperature at which the number of cracks reached the "saturation crack number" is indicated by a ■, and the temperature at which the number of cracks reached 50% of the "saturation crack number" is indicated by a ▲. As shown in the graph of Figure 2, the thicker the film, the lower the heating temperature at which crack formation occurs, and 50% of the saturation crack number occurs approximately midway between the temperature at which crack formation begins and the temperature at which the number of cracks saturates. The relationship between the heating temperature T (°C) at which the saturation crack number is reached and the thickness t (μm) of the anodized film is given by the following equation (1): T (°C) ≥ -4.502 × thickness t (μm) + 284.42 ... (1) The relationship between the heating temperature T (°C) at which the saturation crack number reaches 50% and the thickness t (μm) of the anodized film is given by the following equation (2): T (°C) ≥ -4.9801 × thickness t (μm) + 385.78 ... (2) The relationship between the heating temperature T (°C) at which cracks begin to occur and the thickness t (μm) of the anodized film is given by the following equation (3): T (°C) ≥ -8.0135 × thickness t (μm) + 551.00 ... (3)

[0039] The inventors of the present invention conceived the idea that, since crack formation in an anodic oxide film is temperature-dependent and there is a saturation point for crack formation, in order to prevent the generation of foreign matter due to newly formed cracks, the formation of new cracks in the anodic oxide film in advance by heat treatment can be suppressed during subsequent plasma treatment. Furthermore, they conceived that by sealing the pre-formed cracks, hydrates can be filled into the cracks, thereby effectively suppressing the generation of foreign matter.

[0040] Furthermore, recognizing that cracks in anodized coatings are caused by irregularities on the surface of the anodized coating, we discovered that crack formation can be controlled by controlling the arrangement of these irregularities on the anodized coating surface. We then created recesses in the aluminum alloy base material of the component, thereby systematically forming irregularities on the surface of the anodized coating. This resulted in a component that does not develop new cracks or generate foreign matter even after plasma treatment. These findings will be explained in detail below.

[0041] <Relationship between the recesses of the base material and the irregularities of the anodized coating> When an anodized coating is formed on a base material (sometimes called a substrate) made of aluminum alloy with irregularities on its surface, the anodized coating can also form irregularities that reflect the irregularities on the base material. This is thought to be because compressive strain occurs in the anodized coating formed on the irregularities of the base material, and this compressive strain remains on the surface of the final anodized coating, causing the coating to form and resulting in the appearance of irregularities on the surface of the anodized coating.

[0042] Next, with reference to Figures 3 to 7, the film formation method, the method for manufacturing a component, and the plasma processing apparatus equipped with the component according to this disclosure will be described. Figure 3 is a flowchart of the film formation method according to this disclosure. These will be described in order below.

[0043] <S301, S302> First, in S301, a base material of a member constituting the plasma processing apparatus is prepared and shaped into a predetermined shape. At this time of shaping, uneven portions on a predetermined line may be formed on the surface of the base material, or the uneven portions on the surface of the base material may be separately formed after shaping the base material as S302. FIG. 4 shows an external view when a linear notch is formed as a concave portion in the base material 401. In this case, the pitch P between the concave portions is the distance between the centers 402 of the concave portions. Note that the method of determining the pitch P will be described later. Also, in the example of FIG. 4, a notch is illustrated as the shape of the concave portion, but the cross-sectional shape of the concave portion 403 is not limited to a notch and may be a shape having a curvature as shown in FIGS. 5 and later. Further, in FIG. 4, the concave portion 403 composed of two parallel straight lines is shown, but the concave portion 403 may be formed in a lattice shape on the surface of the base material. Furthermore, instead of the concave portion 403, a convex portion may be formed.

[0044] <S303> Next, the base material 401 with uneven portions formed thereon is subjected to a degreasing and cleaning process (S303). Specifically, crystals on the surface of the base material 401 are washed away with an alkali or an acid or the like. However, this degreasing and cleaning process is not an essential process.

[0045] <S304> Next, the base material 401 after the degreasing and cleaning treatment S303 is subjected to anodizing treatment (S304). Specifically, the anodizing treatment is performed using an oxalic acid-based electrolyte to form an anodic oxide film on the base material 401. Figure 5 is a cross-sectional view of a member in which an anodic oxide film 502 as a porous film has been formed on the surface of a base material 401 having a recess 403 after anodizing treatment. When anodizing treatment is performed on aluminum alloy A5083 as the base material 401 using an oxalic acid-based electrolyte, an anodic oxide film with a film thickness t of 7 μm < t < 50 μm can be formed. The film thickness t of the anodic oxide film 502 is preferably 10 μm < t < 30 μm. As shown in Figure 5, when an anodic oxide film 502 is formed on an aluminum alloy base material 401 in which recesses 403 are formed, grooves 503 are also formed in the anodic oxide film above the recesses 403 formed on the aluminum alloy base material 401. In this case, it is desirable that the spacing P of the grooves 503 formed on the surface of the anodic oxide film 502 satisfies the following equation (4): P (mm) ≤ 0.1394 × film thickness t (μm) - 0.0618 ... (4) Furthermore, it is more preferable that the spacing P satisfies the following equation (5): P (mm) ≤ 0.0248 × film thickness t (μm) + 0.8218 ... (5) The basis for these equations will be explained in Figure 9, which will be described later. Also, since the positions of the recesses 403 in the base material 401 and the grooves 503 formed in the anodic oxide film 502 are aligned, the spacing of the grooves 503 is the same as the spacing between the multiple recesses 403 in the base material 401.

[0046] <S305> Next, when the member on which the anodic oxide film 502 is formed is subjected to heat treatment (S305), cracks occur in the depressions formed on the surface of the anodic oxide film. This is thought to be because, as described above, compressive strain is accumulated in the anodic oxide film formed on the irregularities of the base material, so when tensile stress occurs due to the difference in thermal expansion between the base material 401 and the anodic oxide film 502, cracks are more easily formed there compared to other parts. In other words, this shows that the irregularities formed on the base material can be used as a guide for crack formation. Figure 6 shows the cracks 603 that occurred after heat treatment (S305), and Figure 7 is an enlarged view of part A in Figure 6. As shown in Figure 6, the cracks 603 that occur due to heat treatment (S305) occur above the depressions 403 of the base material 401 and do not occur anywhere else. This is achieved by determining the spacing P of the recesses 403 formed on the surface of the anodic oxide film 502 according to the heating temperature, using the above-mentioned equations (1) and (2). This ensures that there are more recesses than the number of cracks generated by heating, i.e., crack guides are provided, so that no more cracks are generated than the number of recesses. As a result, cracks will not reach the anodic oxide film above adjacent recesses 403. Note that "above the recess 403" refers to the area approximately vertically above the region in the base material 401 where the recesses 403 are formed. The width of the formed cracks themselves is approximately 0.96 μm when the heating temperature T = 145°C (heating width ΔT = 140°C from room temperature), and approximately 1.2 μm when the heating temperature T = 175°C (ΔT = 150°C). Here, the depth d of the groove formed in the anodic oxide film 502 is permissible up to about the same as the film thickness t of the anodic oxide film 502, that is, up to 30 μm. If the spacing P of the recesses is 240 μm or more, the groove may be the same as the film thickness t of the anodic oxide film. It is desirable that the depth d be 2.9 μm or more. Furthermore, if the groove 503 is formed in a V-shape, the radius of curvature of the bottom of the V-shape should be as small as possible, with a maximum of 2.5 μm when the film thickness t = 30 μm. By making the shape of the bottom acute in this way, it is possible to facilitate the occurrence of cracks.

[0047] <S306> Next, a sealing treatment (S306) is performed on the member in which the crack 603 is formed. The sealing treatment can be the same as the sealing treatment performed after the anodizing treatment of ordinary aluminum alloys, and can be performed by pressurized steam sealing (temperature 110°C to 140°C). Figure 8 is an enlarged view of the cross section near the anodized film after the sealing treatment. Hydrate 801 is deposited on the surface of the anodized film 502 and inside the crack 603, filling the inside of the crack 603 and covering the surface of the anodized film 502 to form a hydrate film. The hydrate is first pushed out from the porous pores of the anodized film by the sealing treatment. On the walls on both sides of the crack, hydrate from the porous pores of the cells of the anodized film flows into the crack, filling the crack 603. Furthermore, on the upper surface of the anodic oxide film, hydrates are extruded from the pores of the cells and formed to cover the surface of the anodic oxide film. The thickness h of the hydrate packing layer is 0.03 μm < h < 1 μm in the crack 603, and this fills the crack 603 in a strip-like manner. Here, due to its physical properties, the hydrates function as a buffer within the crack 603, and as long as no new cracks occur in the anodic oxide film 502, the generation of foreign matter caused by cracks can be suppressed.

[0048] <Interval of concavities and convexities formed on the base material> Next, the interval of the concavities and convexities formed on the base material 401 will be described. As described above, the concavities and convexities formed on the base material 401 function as a guide for crack generation. On the other hand, as shown in FIG. 2, it has been found that the cracks generated in the anodic oxide film 502 saturate at a certain temperature. Here, the graph in FIG. 9 shows the relationship between the crack interval P (mm) and the film thickness t (μm) of the anodic oxide film when the number of cracks reaches the "saturated crack number" and when the number of cracks reaches 50% of the "saturated crack number". In the graph of FIG. 9, for the cases where the film thickness of the anodic oxide film is 17 μm, 25 μm, 26 μm, and 27 μm, the crack interval when the number of cracks reaches the "saturated crack number" is indicated by ● marks, and the crack interval when the number of cracks reaches 50% of the "saturated crack number" is indicated by ◆ marks. From the data of this graph, if 50% of the "saturated crack number" is used as a reference, when the film thickness t (μm) of the anodic oxide film is considered, if the interval P (mm) of the concavities and convexities formed on the base material is set to satisfy the following formula (1), then under the condition of 300°C or lower, since all cracks occur above the concave portions of the base material in the heating process after anodization, no new cracks will occur during the plasma treatment process. P (mm) ≤ 0.1394 × film thickness t (μm) - 0.0618 ··· (4) Furthermore, assuming conditions of 350°C or higher, if the "saturated crack number" is used as a reference, when the film thickness t (μm) of the anodic oxide film is considered, if the interval P (mm) of the concavities and convexities formed on the base material is set to satisfy the following formula (3), then new cracks will not occur at locations other than the concave and convex portions of the base material. P (mm) ≤ 0.0248 × film thickness t (μm) + 0.8218 ··· (5)

[0049] In other words, in this disclosure, the spacing of cracks that may occur in the future is assumed based on the relationship between the thickness t (μm) of the anodic oxide film and the heating temperature T (°C). Cracks that may occur at the temperature to which the member will be exposed in the future are assumed to occur by creating irregularities on the base material in advance, thereby causing cracks to occur at the locations where the irregularities are created. Then, in the subsequent sealing treatment, hydrate is filled into the cracks to suppress the generation of foreign matter from the cracks. As a result, even if the member is exposed to plasma and the temperature rises, no new cracks will occur, thus suppressing the generation of foreign matter. Furthermore, since the cracks formed in the irregularities of the base material are limited to occurring above the irregularities, it is possible to suppress the random occurrence of cracks in various locations, and in this respect as well, it is possible to effectively suppress the generation of foreign matter.

[0050] <Examples> Examples of this embodiment will be described below. (Processing conditions) Base material: A5083 Anodized coating: Oxalic acid coating Heating process: 450°C Sealing process: Pressurized steam sealing (110-140°C) Under the above processing conditions, samples were prepared as Example 1 with an anodized coating thickness t = 25 μm, as Example 2 with an anodized coating thickness t = 10 μm, and as Example 3 with an anodized coating thickness t = 30 μm. When the prepared samples were tested in a Prisma environment, as shown in Table 1, no unexpected cracks or foreign matter were observed in any of the examples.

[0051] In the above explanation, the anodic oxide film was described using an oxalic acid-based film, but the anodic oxide film of this disclosure is not limited to oxalic acid-based films and may also be a sulfuric acid film. This is because both sulfuric acid films and oxalic acid films have the same elongation rate of 0.0025, and therefore, even with a sulfuric acid film, the crack formation situation is the same as in the case of an oxalic acid-based film.

[0052] Although the present invention has been specifically described above based on the above embodiments, the present invention is not limited to the above embodiments and can be modified in various ways without departing from its spirit.

[0053] For example, the configuration of the plasma processing apparatus is not limited to the configuration described herein, but is applicable to a variety of plasma processing apparatuses.

[0054] Furthermore, the heat treatment process can be carried out directly or indirectly by methods such as using a bake oven, attaching electric heaters to the parts, using hot air, heating lamps, or electromagnetic waves.

[0055] The present disclosure includes the following aspects: (Aspect 1) A method for forming a film on a metal member, comprising: a first step of forming linear recesses at predetermined intervals on the surface of the metal member; a second step of forming an anodic oxide film on the surface of the metal member on which the recesses are formed; a third step of heat-treating the metal member on which the anodic oxide film is formed to form cracks in the anodic oxide film; and a fourth step of sealing the metal member on which the anodic oxide film is formed to fill the cracks with a hydrate.

[0056] (Aspect 2) The method for forming a film according to the method for forming a film according to the method for forming a film according to the method for forming a film, characterized in that the crack is formed in the anodic oxide film above the recess provided on the metal member.

[0057] (Aspect 3) A method for forming a film according to aspect 1 or 2, characterized in that the crack formed in the anodic oxide film above a recess provided on the metal member does not reach the anodic oxide film above an adjacent recess.

[0058] (Aspect 4) A method for forming a coating according to any one of aspects 1 to 3, characterized in that the recesses provided at predetermined intervals on the surface of the metal member are provided in a grid pattern.

[0059] (Aspect 5) A method for forming a film according to any one of aspects 1 to 4, wherein the metal member is an aluminum alloy, and when the thickness of the anodic oxide film is t (μm), the distance P (mm) between the centers of the recesses formed on the surface of the metal member satisfies the following formula (4), and the temperature T (°C) of the heat treatment satisfies the following formula (2). P (mm) ≤ 0.1394 × film thickness t (μm) - 0.0618 ... (4) T (°C) ≥ -4.9801 × film thickness t (μm) + 385.78 ... (2)

[0060] (Aspect 6) A method for manufacturing a member to be placed inside a plasma processing apparatus, comprising: a first step of forming linear recesses at predetermined intervals on the surface of a base material of the member; a second step of forming an anodic oxide film on the surface of the base material on which the recesses are formed; a third step of heat-treating the member on which the anodic oxide film is formed to form cracks in the anodic oxide film; and a fourth step of sealing the member on which the anodic oxide film is formed to fill the cracks with a hydrate.

[0061] (Aspect 7) A method for manufacturing a member according to aspect 6, characterized in that the crack is formed in the anodic oxide film above a recess provided in the metal member.

[0062] (Aspect 8) A method for manufacturing a member according to aspect 6 or 7, characterized in that the crack formed in the anodic oxide film above a recess provided on the metal member does not reach the anodic oxide film above an adjacent recess.

[0063] (Aspect 9) A method for manufacturing a member according to any one of aspects 6 to 8, characterized in that the recesses provided at predetermined intervals on the surface of the metal member are arranged in a grid pattern.

[0064] (Aspect 10) A method for manufacturing a member according to any one of aspects 6 to 9, wherein the metal member is an aluminum alloy, and when the thickness of the anodic oxide film is t (μm), the distance P (mm) between the centers of the recesses provided on the surface of the metal member satisfies the following formula (4), and the temperature T (°C) of the heat treatment satisfies the following formula (2). P (mm) ≤ 0.1394 × thickness t (μm) - 0.0618 ... (4) T (°C) ≥ -4.9801 × thickness t (μm) + 385.78 ... (2)

[0065] (Aspect 11) A plasma processing apparatus for processing wafers using plasma, wherein the plasma processing apparatus comprises a member having an anodic oxide film, the member having linear recesses formed at predetermined intervals on the surface of the base material of the member, an anodic oxide film formed on the upper surface of the base material, the anodic oxide film having cracks formed above the linear recesses, and the cracks being filled with hydrate.

[0066] (Aspect 12) A plasma processing apparatus according to the present invention of 11, characterized in that the crack formed in the anodic oxide film above a recess provided on the metal member does not reach the anodic oxide film above an adjacent recess.

[0067] (Aspect 13) A plasma processing apparatus according to aspect 11 or 12, characterized in that the recesses provided at predetermined intervals on the surface of the base material of the member are arranged in a grid pattern.

[0068] (Aspect 14) A plasma processing apparatus according to any one of aspects 11 to 13, wherein the base material of the member is an aluminum alloy, and when the thickness of the anodic oxide film is t (μm), the distance P (mm) between the centers of the recesses provided on the surface of the metal member satisfies the following formula (4): P (mm) ≤ 0.1394 × film thickness t (μm) - 0.0618 ... (4)

[0069] 100: Plasma processing apparatus, 101: EFEM, 102: Load lock chamber 103, 104, 105, 106: Gate valve, 107: Connecting parts 108: Vacuum transfer chamber, 109: Vacuum robot, 110: Connecting parts 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 section, 118: Purge gas supply section, 119: Substrate to be processed 120: Process gas supply section, 121: Processing power supply section, 122: Temperature control heater 123: Upper replacement parts, 124: Lower replacement parts, 125: Substrate to be processed 126: Plasma, 127, 128, 129: Anodizing processing area 130: Base, 131: Plate-shaped aluminum part, 132: Wafer holder 133, 134: Anodized treatment area, 401: Base material, 402: Center, 403: Recess, 502: Anodized coating, 603: Crack

Claims

1. A method for forming a coating on a metal member, comprising: a first step of forming linear recesses at predetermined intervals on the surface of the metal member; a second step of forming an anodic oxide film on the surface of the metal member on which the recesses are formed; a third step of heat-treating the metal member on which the anodic oxide film is formed to form cracks in the anodic oxide film; and a fourth step of sealing the metal member on which the anodic oxide film is formed to fill the cracks with a hydrate.

2. A method for forming a film according to claim 1, characterized in that the crack is formed in the anodic oxide film above the recess provided on the metal member.

3. A method for forming a film according to claim 1, characterized in that the crack formed in the anodic oxide film above a recess provided on the metal member does not reach the anodic oxide film above an adjacent recess.

4. A method for forming a coating according to claim 1, characterized in that the recesses provided at predetermined intervals on the surface of the metal member are arranged in a grid pattern.

5. The method for forming a film according to claim 1, wherein the metal member is an aluminum alloy, and when the thickness of the anodic oxide film is t (μm), the distance P (mm) between the centers of the recesses formed on the surface of the metal member satisfies the following formula (4), and the temperature T (°C) of the heat treatment satisfies the following formula (2): P (mm) ≤ 0.1394 × film thickness t (μm) - 0.0618 ... (4) T (°C) ≥ -4.9801 × film thickness t (μm) + 385.78 ... (2) 6. A method for manufacturing a member to be placed inside a plasma processing apparatus, comprising: a first step of forming linear recesses at predetermined intervals on the surface of a base material of the member; a second step of forming an anodic oxide film on the surface of the base material on which the recesses are formed; a third step of heat-treating the member on which the anodic oxide film is formed to form cracks in the anodic oxide film; and a fourth step of sealing the member on which the anodic oxide film is formed to fill the cracks with a hydrate.

7. A method for manufacturing a member according to claim 6, characterized in that the crack is formed in the anodic oxide film above a recess provided in the member.

8. A method for manufacturing a member according to claim 6, characterized in that the crack is formed in the anodic oxide film formed above a recess provided in the member, and does not reach the anodic oxide film above an adjacent recess.

9. A method for manufacturing a member according to claim 6, characterized in that the recesses provided at predetermined intervals on the surface of the member are arranged in a grid pattern.

10. A method for manufacturing a member according to claim 6, wherein the member is an aluminum alloy, and when the thickness of the anodic oxide film is t (μm), the distance P (mm) between the centers of the recesses provided on the surface of the member satisfies the following formula (4), and the temperature T (°C) of the heat treatment satisfies the following formula (2): P (mm) ≤ 0.1394 × thickness t (μm) - 0.0618 ... (4) T (°C) ≥ -4.9801 × thickness t (μm) + 385.78 ... (2) 11. A plasma processing apparatus for processing wafers using plasma, wherein the plasma processing apparatus comprises a member having an anodic oxide film, the member having linear recesses formed at predetermined intervals on the surface of the base material of the member, the anodic oxide film formed on the upper surface of the base material, the anodic oxide film having cracks formed above the linear recesses, and the cracks being filled with hydrate.

12. A plasma processing apparatus according to claim 11, characterized in that the crack formed in the anodic oxide film above a recess provided on the member does not reach the anodic oxide film above an adjacent recess.

13. A plasma processing apparatus according to claim 11, characterized in that the recesses provided at predetermined intervals on the surface of the base material of the member are arranged in a grid pattern.

14. A plasma processing apparatus according to claim 11, wherein the base material of the member is an aluminum alloy, and when the thickness of the anodic oxide film is t (μm), the distance P (mm) between the centers of the recesses provided on the surface of the member satisfies the following formula (4): P (mm) ≤ 0.1394 × film thickness t (μm) - 0.0618 ... (4)

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