Corrosion resistant member

Abstract

To provide a corrosion resistant member excellent in corrosion resistance to corrosive gas and capable of preventing a metal element from desorbing.SOLUTION: A corrosion resistant member 1 includes a base material 10 and a corrosion resistant film 20 on the base material 10. In the corrosion resistant member 1, the corrosion resistant film 20 includes a magnesium fluoride layer 21 containing magnesium fluoride and an aluminum fluoride layer 22 containing aluminum fluoride; the magnesium fluoride layer 21 has larger than 0 and 1 or less of the layer thickness ratio Lb / La of the thickness Lb of the aluminum fluoride layer 22 to that La of the magnesium fluoride layer 21; and the thickness Lb of the aluminum fluoride layer 22 is 1 nm or more and less than 200 nm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to corrosion-resistant members. [Background technology]

[0002] In semiconductor manufacturing processes, highly corrosive gases such as chlorine gas and fluorine gas are sometimes used, so corrosion resistance is required for components constituting semiconductor manufacturing equipment, such as chambers, piping, gas storage devices, valves, susceptors, and showerheads.

[0003] Patent Document 1 discloses a showerhead or other component used in a semiconductor manufacturing process. This component has an aluminum surface coated with a corrosion-resistant coating made of at least one of aluminum fluoride and magnesium fluoride. Patent Document 2 discloses a vacuum chamber component having a corrosion-resistant coating formed on the surface of a substrate. Specifically, the surface side of the corrosion-resistant coating is a layer mainly composed of aluminum oxide or a layer mainly composed of aluminum oxide and aluminum fluoride, and the substrate side of the corrosion-resistant coating is a layer mainly composed of magnesium fluoride or a layer mainly composed of magnesium fluoride and aluminum oxide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-533368 [Patent Document 2] Japanese Patent Application Publication No. 11-61410 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the components disclosed in Patent Documents 1 and 2 have the problem of causing metal contamination of wafers in semiconductor manufacturing processes. In semiconductor manufacturing processes, cleaning with water is sometimes performed for maintenance purposes, etc. In particular, when components come into contact with water, aluminum or magnesium may be released from the components in the form of particles, etc., which may cause metal contamination. Such metal contamination reduces the yield of semiconductor manufacturing in the semiconductor manufacturing process, and therefore there is a demand for its reduction.

[0006] Therefore, an object of the present disclosure is to provide a corrosion-resistant member that has excellent corrosion resistance against corrosive gases and is less likely to release metal elements. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the present disclosure is as follows [1] to [5]. [1] A corrosion-resistant member comprising a substrate and a corrosion-resistant coating on the substrate, the corrosion-resistant coating has a magnesium fluoride layer containing magnesium fluoride and an aluminum fluoride layer containing aluminum fluoride, the magnesium fluoride layer being disposed closer to the substrate than the aluminum fluoride layer; A corrosion-resistant member, wherein a layer thickness ratio Lb / La of a thickness Lb of the aluminum fluoride layer to a thickness La of the magnesium fluoride layer is greater than 0 and not greater than 1, and the thickness Lb of the aluminum fluoride layer is 1 nm or greater and less than 200 nm. [2] The corrosion-resistant member according to [1], wherein the magnesium fluoride includes magnesium fluoride. [3] The corrosion-resistant member according to [1] or [2], wherein the aluminum fluoride includes aluminum fluoride. [4] The corrosion-resistant member according to any one of [1] to [3], wherein the magnesium fluoride layer has a thickness La of 10 nm or more and 20,000 nm or less. [5] The corrosion-resistant member according to any one of [1] to [4], wherein the thickness of the corrosion-resistant coating is 11 nm or more and less than 20,200 nm. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a corrosion-resistant member that has excellent corrosion resistance against corrosive gases and is less likely to lose metal elements. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a configuration of a corrosion-resistant member according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure will be described below. Note that this embodiment shows an example of the present disclosure, and the present disclosure is not limited to this embodiment. Furthermore, various modifications or improvements can be made to this embodiment, and such modifications or improvements may also be included in the present disclosure.

[0011] 1, the corrosion-resistant member according to this embodiment is a corrosion-resistant member 1 including a substrate 10 and a corrosion-resistant coating 20 on the substrate 10, wherein the corrosion-resistant coating 20 has a magnesium fluoride layer 21 containing magnesium fluoride and an aluminum fluoride layer 22 containing aluminum fluoride, the magnesium fluoride layer 21 being disposed closer to the substrate 10 than the aluminum fluoride layer 22, the layer thickness ratio Lb / La of the thickness Lb of the aluminum fluoride layer 22 to the thickness La of the magnesium fluoride layer 21 being greater than 0 and less than 1, and the thickness Lb of the aluminum fluoride layer 22 being 1 nm or greater and less than 200 nm. FIG. 1 is a schematic diagram showing a cross section of the corrosion-resistant member 1 cut along a plane perpendicular to the surface of the substrate 10.

[0012] The corrosion-resistant member 1 according to this embodiment has the above-described configuration, and is capable of resisting corrosion against corrosive gases and reducing metal contamination. The reason for this can be considered as follows, for example.

[0013] The corrosion-resistant member 1 according to this embodiment includes the corrosion-resistant coating 20, and therefore has excellent corrosion resistance against highly corrosive gases, plasma, and the like. In the corrosion-resistant coating 20, the aluminum fluoride layer 22 has low reactivity to corrosive gases and is therefore less likely to undergo compositional changes. This improves the chemical stability of the corrosion-resistant member 1. Furthermore, in the corrosion-resistant coating 20, the magnesium fluoride layer 21 relieves internal stress in the aluminum fluoride layer 22 due to heating, ensuring adhesion to the substrate 10. This improves the physical stability of the corrosion-resistant member 1. In other words, the corrosion-resistant coating 20 including both the aluminum fluoride layer 22 and the magnesium fluoride layer 21 is believed to enhance the corrosion resistance of the corrosion-resistant member 1 according to this embodiment in a corrosive gas environment.

[0014] The corrosion-resistant coating 20 according to this embodiment, which includes the magnesium fluoride layer 21 and the aluminum fluoride layer 22, also contributes to reducing metal contamination caused by the corrosion-resistant member. For example, when the corrosion-resistant member comes into contact with water, metals contained in the corrosion-resistant member may be released. Metal contamination caused by the corrosion-resistant member refers to contamination of the environment surrounding the corrosion-resistant member by metals released from the corrosion-resistant member. For example, in a semiconductor manufacturing process, when a semiconductor manufacturing device using corrosion-resistant members as components is washed with water or the like for maintenance or the like, metal elements contained in the corrosion-resistant member of the semiconductor manufacturing device may be released in the form of particles or the like. The released metal elements may remain on the surface of the semiconductor manufacturing device and may even adhere to wafers or the like during semiconductor manufacturing, causing metal contamination.

[0015] In the corrosion-resistant member 1 according to this embodiment, the thickness Lb of the aluminum fluoride layer 22 is equal to or smaller than the thickness La of the magnesium fluoride layer 21. Therefore, it is believed that the magnesium fluoride layer 21 can sufficiently relieve the internal stress of the aluminum fluoride layer 22 that occurs during the production of the corrosion-resistant member 1, thereby reducing microcracks that occur in the aluminum fluoride layer 22. This reduces defects on the outermost surface of the corrosion-resistant coating 20, thereby reducing the surface area of ​​the outermost surface of the corrosion-resistant coating 20, which is presumably why aluminum becomes less likely to be released from the corrosion-resistant member 1.

[0016] In the corrosion-resistant member 1 according to this embodiment, the aluminum fluoride layer 22 is laminated on the magnesium fluoride layer 21, so that the magnesium fluoride layer 21 is unlikely to be exposed on the surface. Therefore, it is presumed that magnesium is unlikely to be released from the corrosion-resistant member 1.

[0017] As described above, metal elements are less likely to be desorbed from the corrosion-resistant member 1 according to this embodiment. Therefore, for example, when the corrosion-resistant member 1 is used as a component of semiconductor manufacturing equipment, metal desorption from the corrosion-resistant member 1 caused by cleaning of the semiconductor manufacturing equipment is suppressed. This makes it less likely for metal elements to remain in the semiconductor manufacturing equipment, which is thought to reduce metal contamination of wafers and the like in the semiconductor manufacturing process.

[0018] As such, the corrosion-resistant member according to this embodiment is suitable for components that require corrosion resistance and that require reduced metal contamination, and is suitable, for example, as a component of semiconductor manufacturing equipment (particularly, a film-forming apparatus using chemical vapor deposition). Specific examples include susceptors and shower heads in film-forming apparatus that form thin films on wafers. Use of the corrosion-resistant member according to this embodiment as a component of semiconductor manufacturing equipment suppresses the generation of particles and the like in the semiconductor manufacturing process, thereby reducing metal contamination of wafers and the like. This allows semiconductors to be manufactured with a high yield.

[0019] The corrosion-resistant member according to this embodiment will be described in further detail below.

[0020] (base material) The material constituting the substrate in the corrosion-resistant member according to this embodiment is not particularly limited, and examples thereof include metals. The type of metal is not particularly limited, and may be a simple metal (containing unavoidable impurities) or an alloy. An example of a simple metal is aluminum (Al), and an example of an alloy is an aluminum alloy. The type of aluminum alloy is not particularly limited, and examples include A6061 alloy and A5052 alloy, which are aluminum alloys specified in the JIS standard. When aluminum or an aluminum alloy is used as the substrate, workability and mechanical strength can be improved.

[0021] (corrosion-resistant coating) The corrosion-resistant coating of the corrosion-resistant member according to this embodiment includes a magnesium fluoride layer containing magnesium fluoride and an aluminum fluoride layer containing aluminum fluoride. That is, the corrosion-resistant coating is a laminate of multiple layers, and the multiple layers include a magnesium fluoride layer containing magnesium fluoride and an aluminum fluoride layer containing aluminum fluoride. The magnesium fluoride layer is disposed closer to the substrate than the aluminum fluoride layer. For example, as shown in FIG. 1, a structure may be adopted in which a magnesium fluoride layer 21 is laminated on a substrate 10, and an aluminum fluoride layer 22 is further laminated on the magnesium fluoride layer 21.

[0022] The laminate may constitute the entire corrosion-resistant coating, or may constitute a part of it. That is, the laminate may cover the entire surface of the substrate, or may cover a part of the surface of the substrate. In the corrosion-resistant coating, the multiple layers of the laminate may have only two layers, a magnesium fluoride layer and an aluminum fluoride layer, or may have other layers. Furthermore, the multiple layers of the laminate may have a magnesium fluoride layer and an aluminum fluoride layer formed continuously, or another layer may be formed between the magnesium fluoride layer and the aluminum fluoride layer.

[0023] The magnesium fluoride layer in the corrosion-resistant coating according to this embodiment contains magnesium fluoride, but the type of magnesium fluoride is not particularly limited. The magnesium fluoride layer may be partially or entirely made of magnesium fluoride. The type of magnesium fluoride contained in the magnesium fluoride layer may be one type alone or multiple types. The magnesium fluoride may be, for example, magnesium fluoride (MgF2), or magnesium oxyfluoride (Mg x F y O z The type of magnesium fluoride can be identified by analysis using energy dispersive X-ray analysis (EDS) or X-ray diffraction (XRD).

[0024] The aluminum fluoride layer in the corrosion-resistant coating according to this embodiment contains aluminum fluoride, but the type of aluminum fluoride is not particularly limited. The aluminum fluoride layer may be partially or entirely aluminum fluoride. The type of aluminum fluoride contained in the aluminum fluoride layer may be one type alone or multiple types. The aluminum fluoride may be, for example, aluminum fluoride (AlF3), or aluminum oxyfluoride (Al x F y O zThe type of aluminum fluoride can be identified by analysis such as energy dispersive X-ray analysis or X-ray diffraction.

[0025] In the corrosion-resistant member according to this embodiment, the layer thickness ratio Lb / La of the aluminum fluoride layer thickness Lb to the magnesium fluoride layer thickness La is greater than 0 and less than 1. That is, the aluminum fluoride layer thickness Lb is equal to or less than the magnesium fluoride layer thickness La. Within this range, the magnesium fluoride layer relieves the internal stress of the aluminum fluoride layer, making it easier to suppress the occurrence of microcracks. As a result, the desorption of aluminum from the aluminum fluoride layer Lb can be suppressed. Furthermore, the layer thickness ratio Lb / La may be 0.8 or less, 0.5 or less, 0.3 or less, or 0.25 or less. Within this range, the occurrence of microcracks can be further suppressed, thereby further suppressing the desorption of aluminum from the aluminum fluoride layer Lb. The magnesium fluoride layer thickness La and the aluminum fluoride layer thickness Lb can be measured by observing the cross section of the corrosion-resistant member that appears when the corrosion-resistant member is cut along a plane perpendicular to the surface of the substrate. Specifically, it can be measured by the method described in the Examples below.

[0026] The thickness La of the magnesium fluoride layer is not particularly limited, but the lower limit of the thickness La of the magnesium fluoride layer may be 10 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more. If the thickness La of the magnesium fluoride layer is 10 nm or more, the internal stress of the aluminum fluoride layer can be sufficiently alleviated. Therefore, the adhesion between the aluminum fluoride layer and the substrate can be ensured. Furthermore, the upper limit of the thickness La of the magnesium fluoride layer may be 20,000 nm or less, 10,000 nm or less, 5,000 nm or less, or 550 nm or less. If the thickness La of the magnesium fluoride layer is 20,000 nm or less, the magnesium fluoride layer is less likely to crack even when subjected to thermal history. That is, the thickness La of the magnesium fluoride layer may be 10 nm or more and 20,000 nm or less, 30 nm or more and 10,000 nm or less, 40 nm or more and 5,000 nm or less, or 50 nm or more and 550 nm or less.

[0027] In the corrosion-resistant member according to this embodiment, the thickness Lb of the aluminum fluoride layer is 1 nm or more and less than 200 nm. If the thickness Lb of the aluminum fluoride layer is 1 nm or more, the corrosion resistance of the corrosion-resistant coating can be ensured. If the thickness Lb of the aluminum fluoride layer is less than 200 nm, the occurrence of microcracks during the production of the corrosion-resistant member can be suppressed. Therefore, the detachment of aluminum from the aluminum fluoride layer Lb can be suppressed.

[0028] The lower limit of the thickness Lb of the aluminum fluoride layer may be 3 nm or more, 5 nm or more, or 10 nm or more. The upper limit of the thickness Lb of the aluminum fluoride layer may be 150 nm or less, 110 nm or less, or 65 nm or less. That is, the thickness Lb of the aluminum fluoride layer may be 3 nm or more and 150 nm or less, 5 nm or more and 110 nm or less, or 10 nm or more and 65 nm or less. Within these ranges, the effect of suppressing aluminum detachment is further improved while ensuring the corrosion resistance of the corrosion-resistant coating.

[0029] The method for measuring the thickness La of the magnesium fluoride layer and the thickness Lb of the aluminum fluoride layer of the corrosion-resistant coating is not particularly limited, but examples include methods using a transmission electron microscope (TEM), a scanning transmission electron microscope (STEM), a scanning electron microscope (SEM), etc. For example, the corrosion-resistant member is cut along a plane perpendicular to the surface of the substrate to expose the cross section, and then a scanning electron microscope image of the cross section is obtained using a scanning electron microscope. The thickness La of the magnesium fluoride layer and the thickness Lb of the aluminum fluoride layer can be determined by measuring the lengths of the portions corresponding to magnesium fluoride and aluminum fluoride in the obtained scanning electron microscope image. The magnification of the electron microscope observation is not particularly limited, but can be, for example, 30,000 times.

[0030] The crystallinity of magnesium fluoride in the magnesium fluoride layer and the crystallinity of aluminum fluoride in the aluminum fluoride layer are not particularly limited. That is, the crystal grains of the magnesium fluoride layer and the aluminum fluoride layer may contain a plurality of crystallites or an amorphous phase.

[0031] The thickness of the corrosion-resistant coating according to this embodiment is not particularly limited, but may be 11 nm or more, 33 nm or more, 45 nm or more, or 60 nm or more. A thickness of 11 nm or more ensures corrosion resistance. Furthermore, the thickness of the corrosion-resistant coating may be less than 20,200 nm, 10,150 nm or less, 5,110 nm or less, or 615 nm or less. A thickness of less than 20,200 nm makes the corrosion-resistant coating less likely to crack even when subjected to thermal history. That is, the thickness of the corrosion-resistant coating may be 11 nm or more but less than 20,200 nm, 33 nm or more but 10,000 nm or less, 45 nm or more but 5,110 nm or less, or 60 nm or more but 615 nm or less.

[0032] The method for measuring the thickness of the corrosion-resistant coating is not particularly limited, but examples thereof include methods using a transmission electron microscope, a scanning transmission electron microscope, a scanning electron microscope, or the like.

[0033] (Method for manufacturing corrosion-resistant members) The method for producing the corrosion-resistant member according to this embodiment is not particularly limited, but an example thereof includes a method in which a magnesium fluoride layer is formed on the surface of a substrate by a method such as vapor deposition, and then an aluminum fluoride layer is further formed by a method such as vapor deposition.

[0034] The method for forming the magnesium fluoride layer and the aluminum fluoride layer is not particularly limited, but examples thereof include physical vapor deposition (PVD) such as vacuum deposition and sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), a sol-gel method, a thermal spraying method, and an electrophoretic deposition method. Among these, physical vapor deposition, chemical vapor deposition, and atomic layer deposition are preferred from the viewpoint of controlling the thickness La of the magnesium fluoride layer and the thickness Lb of the aluminum fluoride layer. [Example]

[0035] The present invention will be described in more detail below with reference to examples and comparative examples.

[0036] Example 1 The substrate used was an aluminum alloy A5052 containing 2.55 mass % of magnesium, cut into a plate shape measuring 50 mm in length, 30 mm in width, and 3 mm in thickness.

[0037] The substrate was pretreated as follows: First, 70 g of Esclean AL-13 (manufactured by Sasaki Chemical Co., Ltd.) was dissolved in 1 L of water to prepare a degreasing solution at a temperature of 50°C. The substrate was immersed in this degreasing solution for 10 minutes to degrease it, and then washed with pure water.

[0038] Next, the degreased substrate was subjected to smut removal to prevent a decrease in adhesion to the corrosion-resistant coating. First, 500 g of Esclean AL-5000 (manufactured by Sasaki Chemical Co., Ltd.) was heated to 70°C to prepare an etching solution. The degreased substrate was immersed in this etching solution for 1 minute to perform etching, and then washed with pure water. Next, 200 g of Smut Clean (manufactured by Raiki Co., Ltd.) containing nitric acid was dissolved in 400 g of water and the temperature was raised to 25°C to prepare a smut removal solution. The etched substrate was immersed in this smut removal solution for 30 seconds to perform smut removal, and then washed with pure water. The substrate from which smut removal had been performed was then vacuum dried to complete the pretreatment.

[0039] Next, a magnesium fluoride layer was formed on the pretreated substrate by vacuum deposition. The conditions for vacuum deposition of the magnesium fluoride layer were as follows: First, the pretreated substrate was placed in a vacuum chamber, and then the vacuum degree was set to 2×10 -4 The vacuum chamber was evacuated until the pressure reached 100 Pa. The pretreated substrate was then heated to 400°C. A magnesium fluoride sintered material was used as the deposition material, and an electron beam was irradiated onto this sintered material. The shutter was opened, and a magnesium fluoride layer was formed on the pretreated substrate. The input power of the electron beam was about 40 mA at an acceleration voltage of 5 kV, and the degree of vacuum during deposition was 5 x 10 -4 It was Pa.

[0040] Next, an aluminum fluoride layer was formed on the magnesium fluoride layer by vacuum deposition. The conditions for vacuum deposition of the aluminum fluoride layer were as follows: First, the substrate on which the magnesium fluoride layer was formed was placed in a vacuum chamber, and then the vacuum degree was set to 2×10 -4 The vacuum chamber was evacuated until the pressure reached 100 Pa. Then, the substrate on which the magnesium fluoride layer was formed was heated to 400°C. An aluminum fluoride sintered material was used as the deposition material, and an electron beam was irradiated onto this sintered material. The shutter was opened, and an aluminum fluoride layer was formed on the magnesium fluoride layer formed on the substrate. The input power of the electron beam at this time was about 40 mA at an acceleration voltage of 5 kV, and the degree of vacuum during deposition was 5 x 10 -4 It was Pa.

[0041] The corrosion-resistant member of Example 1 thus obtained was cut to expose a cross section of the corrosion-resistant member. This cross section was a plane perpendicular to the surface of the substrate on which the corrosion-resistant coating was formed. The cross section of the corrosion-resistant member was then processed using a cross-section polisher (IB-19530CP, manufactured by JEOL Ltd.).

[0042] Next, the cross section of the corrosion-resistant member was observed using a scanning electron microscope (JSM-IT800HL, manufactured by JEOL Ltd.), and the thicknesses of the magnesium fluoride layer and the aluminum fluoride layer were measured. The conditions for electron microscope observation were an acceleration voltage of 10 kV and a magnification of 30,000 times. The thicknesses of the magnesium fluoride layer and the aluminum fluoride layer were measured for five fields of view in the electron microscope image obtained by electron microscope observation. The average values ​​of the five fields of view for each of the magnesium fluoride layer and the aluminum fluoride layer were calculated and used as the magnesium fluoride layer thickness La and the aluminum fluoride layer thickness Lb of the corrosion-resistant coating of Example 1. Furthermore, the thickness of the corrosion-resistant coating and the layer thickness ratio Lb / La were calculated from the obtained magnesium fluoride layer thickness La and aluminum fluoride layer thickness Lb. These results are shown in Table 1.

[0043] [Table 1]

[0044] A metal extraction test was conducted on the corrosion-resistant member of Example 1 to evaluate the amounts of aluminum and magnesium (Mg) extracted from the corrosion-resistant member. The metal extraction test was conducted as follows: First, the corrosion-resistant member was immersed in 150 mL of ultrapure water (Milli-Q Advantage A10, manufactured by Merck) for 60 minutes and then dried by air blowing. Next, the dried corrosion-resistant member was immersed in 50 mL of nitric acid (TAMAPURE AA-10, manufactured by Tama Chemicals Co., Ltd.) diluted with ultrapure water to a concentration of 0.15 mass% for 5 minutes and then removed.

[0045] Next, the nitric acid solution after removing the corrosion-resistant components was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). A calibration curve was created using a mixed standard solution (XSTC-622, SPEX), and measurements were performed using an inductively coupled plasma mass spectrometer (7900 ICP-MS, Agilent Technologies) to calculate the concentrations of aluminum and magnesium in the nitric acid. The calculated concentrations of aluminum and magnesium were used as the amounts of aluminum and magnesium extracted from the corrosion-resistant components, respectively. These results are shown in Table 1.

[0046] In Table 1, the aluminum extractables were designated as "AA" if they were less than 500 ppt, "A" if they were between 500 ppt and 1000 ppt, "B" if they were between 1000 ppt and 1500 ppt, "C" if they were between 1500 ppt and 2000 ppt, and "D" if they were 2000 ppt or more. In Table 1, the extracted amount of magnesium was designated as "AA" if it was less than 100 ppt, "A" if it was 100 ppt or more but less than 200 ppt, "B" if it was 200 ppt or more but less than 500 ppt, "C" if it was 500 ppt or more but less than 1000 ppt, and "D" if it was 1000 ppt or more.

[0047] Next, a corrosion test was conducted on the corrosion-resistant member of Example 1 to evaluate the state of peeling of the corrosion-resistant coating. The corrosion test involved heat treatment in an inert gas atmosphere containing fluorine gas (F2). The corrosion test conditions were as follows: the fluorine gas concentration in the inert gas atmosphere was 1% by volume, the heat treatment temperature was 300°C, and the heat treatment time was 300 minutes.

[0048] After the corrosion test, the surface of the corrosion-resistant coating on the corrosion-resistant member was observed with a scanning electron microscope (JSM-IT800HL, manufactured by JEOL Ltd.) to evaluate the degree of peeling of the corrosion-resistant coating. The conditions for electron microscope observation were an accelerating voltage of 10 kV and a magnification of 100x. The results are shown in Table 1. In Table 1, if the area of ​​the peeled portion of the corrosion-resistant coating was less than 1% of the total area of ​​the corrosion-resistant coating, it was designated as "AA," if it was 1% or more but less than 10%, it was designated as "A," if it was 10% or more but less than 20%, it was designated as "B," if it was 20% or more but less than 50%, it was designated as "C," and if it was 50% or more, it was designated as "D."

[0049] (Examples 2 to 7 and Comparative Examples 1 and 4) Corrosion-resistant members of Examples 2 to 7 and Comparative Examples 1 and 4 were produced in the same manner as in Example 1, except that the thickness of the magnesium fluoride layer and the thickness of the aluminum fluoride layer were changed as shown in Table 1. The obtained corrosion-resistant members were each evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0050] (Comparative Example 2) A corrosion-resistant member of Comparative Example 2 was produced in the same manner as in Example 1, except that no magnesium fluoride layer was formed and the thickness of the aluminum fluoride layer was changed as shown in Table 1. The obtained corrosion-resistant member of Comparative Example 2 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0051] (Comparative Example 3) A corrosion-resistant member of Comparative Example 3 was produced in the same manner as in Example 1, except that no aluminum fluoride layer was formed and the thickness of the magnesium fluoride layer was changed as shown in Table 1. The obtained corrosion-resistant member of Comparative Example 3 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0052] As shown in Table 1, the corrosion-resistant members of Examples 1 to 7 had low amounts of extracted aluminum and extracted magnesium in the metal extraction test. This suggests that metal contamination due to the detachment of aluminum and magnesium from the surface of the corrosion-resistant member can be suppressed by appropriately controlling the thickness of the magnesium fluoride layer and aluminum fluoride layer. It was also found that there was almost no peeling of the corrosion-resistant coating after the corrosion test.

[0053] The corrosion-resistant members of Comparative Examples 1 and 4 exhibited a higher amount of extracted aluminum in the metal extraction test. The corrosion-resistant coatings of the corrosion-resistant members of Comparative Examples 1 and 4 all had a layer thickness ratio Lb / La greater than 1. This means that the thickness Lb of the aluminum fluoride layer was greater than the thickness La of the magnesium fluoride layer. Therefore, it is presumed that the stress in the aluminum fluoride layer during the production of the corrosion-resistant member could not be fully relieved, resulting in the occurrence of microcracks in the aluminum fluoride layer on the surface of the corrosion-resistant member. As a result, the surface area of ​​the aluminum fluoride layer increased, and the amount of aluminum desorbed from the surface of the corrosion-resistant member increased. Furthermore, the corrosion-resistant members of Comparative Examples 1 and 4 exhibited a higher amount of extracted magnesium in the metal extraction test compared to Examples 1 to 7. It is presumed that this is due to the microcracks that occurred in the aluminum fluoride layer reaching the magnesium fluoride layer.

[0054] The corrosion-resistant member of Comparative Example 2 had a large amount of extracted aluminum in the metal extraction test. The corrosion-resistant coating of the corrosion-resistant member of Comparative Example 2 did not have a magnesium fluoride layer. Therefore, it is presumed that the stress in the aluminum fluoride layer during the production of the corrosion-resistant member could not be alleviated, causing microcracks in the aluminum fluoride layer. As a result, the surface area of ​​the aluminum fluoride layer increased, and it is believed that the amount of aluminum desorbed from the surface of the corrosion-resistant member increased.

[0055] The corrosion-resistant member of Comparative Example 3 had a large amount of extracted magnesium in the metal extraction test. Because the corrosion-resistant coating of the corrosion-resistant member of Comparative Example 3 did not have an aluminum fluoride layer, the magnesium fluoride layer was exposed on the surface of the corrosion-resistant member. This is thought to have made it easier for magnesium to be desorbed from the surface of the corrosion-resistant member.

[0056] Furthermore, peeling of the corrosion-resistant coating after the corrosion test was confirmed in the corrosion-resistant members of Comparative Examples 2 and 3. From these results, it is considered that in order to obtain corrosion resistance in the corrosion test, the corrosion-resistant coating needs to have both a magnesium fluoride layer and an aluminum fluoride layer.

[0057] The results of Examples 1 to 7 and Comparative Examples 1 to 4 revealed that in order to obtain good results in the corrosion test and the metal extraction test, it is necessary for the corrosion-resistant coating to have both a magnesium fluoride layer and an aluminum fluoride layer, and for the layer thickness ratio Lb / La of the aluminum fluoride layer thickness Lb to the magnesium fluoride layer La to be greater than 0 and not greater than 1. [Explanation of symbols]

[0058] 1. Corrosion-resistant materials 10...Base material 20. Corrosion-resistant coating 21···Magnesium fluoride layer 22 Aluminum fluoride layer La··· magnesium fluoride layer thickness Lb: thickness of aluminum fluoride layer

Claims

1. A corrosion-resistant member comprising a substrate and a corrosion-resistant coating on the substrate, the corrosion-resistant coating has a magnesium fluoride layer containing magnesium fluoride and an aluminum fluoride layer containing aluminum fluoride, the magnesium fluoride layer being disposed closer to the substrate than the aluminum fluoride layer; a layer thickness ratio Lb / La of a thickness Lb of the aluminum fluoride layer to a thickness La of the magnesium fluoride layer is greater than 0 and less than 1, and the thickness Lb of the aluminum fluoride layer is 1 nm or more and less than 200 nm.

2. The corrosion-resistant member of claim 1 , wherein the magnesium fluoride comprises magnesium fluoride.

3. The corrosion-resistant member according to claim 1 or claim 2, wherein the aluminum fluoride comprises aluminum fluoride.

4. 3. The corrosion-resistant member according to claim 1, wherein the magnesium fluoride layer has a thickness La of 10 nm or more and 20,000 nm or less.

5. 3. The corrosion-resistant member according to claim 1, wherein the thickness of the corrosion-resistant coating is 11 nm or more and less than 20,200 nm.

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