JP4068742B2 - Method for producing anodized film-coated member for semiconductor production equipment having excellent heat cracking resistance and corrosion resistance - Google Patents

Description

【００３５】
Ｎｏ．１〜７は本発明に係る陽極酸化皮膜被覆部材であり、いずれも耐熱割れ性及び耐ガス腐食性に優れている。一方、Ｎｏ．８〜１１は、本発明で規定する表面粗さが大き過ぎるか、小さ過ぎる場合の比較例であり、いずれも耐熱割れ性及び耐ガス腐食性に劣ることが分かる。
【００３６】
実施例２
陽極酸化処理後の表面において、本発明で規定する表面粗さを測定したこと以外は、実施例１と同様にして表２に示す各種試験片を作製し、耐熱割れ性と耐ガス腐食性を評価した。結果は表２に併記する。
【００３７】
【表２】

【００３８】
Ｎｏ．１〜４は本発明に係る陽極酸化皮膜被覆部材であり、いずれも耐熱割れ性及び耐ガス腐食性に優れている。一方、Ｎｏ．５〜８は、本発明で規定する表面粗さが大き過ぎるか、小さ過ぎる場合の比較例であり、いずれも耐熱割れ性及び耐ガス腐食性に劣ることが分かる。
【００３９】
尚、Ｎｏ．９は、図４で示した様に、本発明範囲外の平滑な表面を有する基材に陽極酸化皮膜を形成した後、ブラスト処理で表面を粗くしたものであり、この場合も、耐熱割れ性及び耐ガス腐食性に劣ることが分かる。
【００４０】
実施例３
６０００系のＡｌ合金からなる基材表面に、ショットブラストまたは表面研磨を施すことにより、表３に示す図１〜図４の内部構造を有する陽極酸化皮膜を形成した。得られた試験片に実施例１と同じ試験を行い、耐熱割れ性と耐ガス腐食性を評価した。結果は表３に示す。
【００４１】
【表３】

【００４２】
Ｎｏ．１，２は本発明に係る陽極酸化皮膜被覆部材であり、いずれも耐熱割れ性及び耐ガス腐食性に優れている。一方、Ｎｏ．３〜５は、陽極酸化皮膜においてセル結合部が均一に分散していない比較例であり、いずれも耐熱割れ性及び耐ガス腐食性に劣ることが分かる。
【００４３】
【発明の効果】
本発明は以上の様に構成されているので、耐熱割れ性に優れ、しかも耐食性が良好な半導体製造装置用陽極酸化皮膜被覆部材が提供できることとなった。
【図面の簡単な説明】
【図１】従来の陽極酸化皮膜の構造を示す概略説明図である。
【図２】従来の陽極酸化皮膜の構造を示す概略説明図である。
【図３】本発明に係る陽極酸化皮膜の構造を示す概略説明図である。
【図４】比較例の陽極酸化皮膜の構造を示す概略説明図である。
【符号の説明】
１ 基材
２ 皮膜
３ セル[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to an anodized film-coated member for a semiconductor manufacturing apparatus excellent in heat cracking resistance and corrosion resistance, and more specifically, is an aluminum alloy member suitable as a chamber of a semiconductor manufacturing apparatus or a chamber internal material, and has a large temperature change. The present invention relates to an anodized film-coated member for a semiconductor manufacturing apparatus that exhibits excellent heat cracking resistance even when used in an environment and has good corrosion resistance.
[0002]
[Prior art]
For example, aluminum alloys are mainly used in vacuum chambers for semiconductor manufacturing equipment, but the interior of the chamber is exposed to various types of corrosive gases and plasmas in an environment of room temperature to 200 ° C. or higher in pretreatment processes and manufacturing processes. Therefore, it is difficult to maintain corrosion resistance and wear resistance with a solid aluminum alloy. Therefore, a process of forming an anodized film inside the chamber is generally performed for the purpose of improving the corrosion resistance and wear resistance of the aluminum alloy. As described above, it is usually employed to form an anodic oxide film on the surface of an aluminum alloy by performing anodizing treatment for the purpose of improving the corrosion resistance and wear resistance of aluminum or an aluminum alloy (hereinafter simply referred to as an aluminum alloy). In the past, various methods have been proposed.
[0003]
For example, in JP-A-9-217197, when the surface roughness Ra of the aluminum alloy surface obtained by machining is 0.1 μm or more, alumina grows in various directions during the anodizing treatment. From the viewpoint that the stress increases and defects (cracks) occur in the anodized film, which significantly deteriorates the corrosion resistance, the surface flatness is averaged by performing mechanical polishing on the substrate surface. A technique for reducing the stress during film growth and improving the corrosion resistance by reducing the thickness Ra to 0.1 μm or less (preferably 0.01 μm or less) is disclosed.
[0004]
However, even if an anodic oxide coating member obtained by this method is used for a chamber member, the coating cracks or peels off due to a significant temperature change during use, and corrosive substances enter the coating. It has been pointed out that the base material is corroded by doing so.
[0005]
As mentioned above, conventional anodic oxide films do not necessarily assume a high-temperature corrosive environment and a thermal cycle at room temperature. When used under conditions with large temperature changes, there is a difference in the coefficient of thermal expansion between the substrate and the film. The film was cracked or peeled off, and the base material was corroded by the entry of corrosive substances. That is, there is actually no anodic oxide film with excellent heat cracking resistance.
[0006]
[Problems to be solved by the invention]
The present invention has been made paying attention to the above circumstances, and an object of the present invention is to provide an anodized film-coated member for a semiconductor manufacturing apparatus that has excellent heat cracking resistance and good corrosion resistance.
[0007]
[Means for Solving the Problems]
The anodic oxide coating member for a semiconductor manufacturing apparatus excellent in heat cracking resistance and corrosion resistance according to the present invention that solves the above problems is an anodic oxide coating member having an anodic oxide coating on an Al or Al alloy substrate. By forming an anodized film on an Al or Al alloy substrate having a surface roughness of 0.1 to 5 μm measured by the following methods (i) and (ii), a plurality of cells are bonded in the anodized film. The gist of the present invention is that the cell coupling portions are uniformly dispersed.
[0008]
(i) Measure the surface roughness at three or more locations on a line segment of 25 μm length arbitrarily selected on the surface of the substrate, and remove the maximum and minimum values from the measured values. The measurement value A is the measured value of the surface roughness of at least the place (in the case of two or more places, the average value).
(ii) This operation is repeated three times or more, and the average of the measured value A is defined as the surface roughness.
[0009]
As for the surface of the anodic oxide film, the surface roughness measured by the methods (i) and (ii) is 0.1 to 5 μm when the substrate is used.
[0011]
Also, in the process of growth of the anodic oxide film, both adjacent cells merge to reach the base material, or if an anodic oxide film is formed in which a single cell is divided in the middle to reach the base material, heat cracking resistance and corrosion resistance It is possible to obtain an anodic oxide coating member for a semiconductor manufacturing apparatus that is excellent in performance.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
As a result of various investigations to prevent cracks occurring in the conventional anodized film-coated member, the present inventors have found that the phenomenon of cracks in the film occurs as shown in FIG. It has been concluded that the cause is that the part where the direction is concentrated in one place and the stress becomes very high is present in the film 2.
[0013]
Further, as in the above prior art (Japanese Patent Laid-Open No. 9-217197), for an anodized film having an average surface roughness Ra of 0.1 μm or less, the cell 3 is attached to the substrate as shown in FIG. Although the stress between the cell 3 and the cell 3 ′ is very small, when used in an environment such as a vacuum chamber member that is subjected to a high temperature (200 ° C. or higher) and a room temperature thermal cycle, etc. The difference in thermal expansion coefficient between the substrate 1 and the film 2 cannot be absorbed, and the film is broken between the cell 3 and the cell 3 ′, which is the weakest part of the film, and the corrosion resistance is impaired. I found out.
[0014]
Therefore, the present inventors have avoided cell stress locally in the film, which is one of the causes of film cracking, and absorbs the difference in thermal expansion coefficient between the substrate and the film, so If the part (part where a plurality of cells are combined in the cell growth process in the anodizing process) is uniformly provided in the film, the cells, which are weak parts in the film, are reinforced, and heat cracking and corrosion resistance ( In particular, the inventors have found that a film excellent in gas corrosion resistance) can be formed, and have arrived at the present invention.
[0015]
That is, the anodic oxide coating member according to the present invention uniformly disperses the cell bonding portion in the anodic oxide film without uniformly concentrating the stress in the anodic oxide film. In addition, the corrosion resistance is drastically improved.
[0016]
The film as described above can be formed by setting the surface of the base material before the anodizing treatment to a surface roughness of 0.1 to 5 μm as measured by the following methods (i) and (ii).
[0017]
(i) Measure the surface roughness at three or more locations on a line segment of 25 μm length arbitrarily selected on the surface of the substrate, and remove the maximum and minimum values from the measured values. The measurement value A is the measured value of the surface roughness of at least the place (in the case of two or more places, the average value).
(ii) This operation is repeated three times or more, and the average of the measured value A is defined as the surface roughness.
[0018]
Incidentally, when the conventional product as shown in FIG. 1 is measured by the method defined in the present invention, even if the Ra value measured by the JIS standard (B0601) is large (in Japanese Patent Application Laid-Open No. 9-217197, Ra 0.1 A value of 0.1 μm or less (smooth surface value) can be obtained. The reason why the value increases in Ra defined by JIS is that the roughness having a large width such as a machined eye is averaged by measuring a section having a length of several mm. The surface roughness defined in the present invention is based on a measurement method in which an average roughness is measured in a section having a length of 25 μm and averaged except for a maximum value and a minimum value, and is expressed by the Ra value. It defines not a macro surface shape but a micro surface shape. In other words, in the present invention, it is very effective to control a microscopic surface shape, not a macroscopic surface shape represented by Ra, in order to form a film having excellent heat cracking resistance. It was made based on the knowledge.
[0019]
When the surface roughness specified in the present invention is less than 0.1 μm, the surface becomes close to a smooth state, and the cell grows straight and the heat cracking resistance deteriorates. Yes, 0.2 μm or more is desirable. On the other hand, when the surface roughness specified in the present invention exceeds 5 μm, the substrate is excessively exposed, many defects are generated in the anodized film, and the heat cracking resistance and corrosion resistance are deteriorated, so that it is 5 μm or less. 3 μm or less is desirable.
[0020]
In order to obtain the surface roughness defined in the present invention, an appropriate method may be selected depending on the type of Al alloy, the type of member, the usage environment, and the like. For example, physical methods such as shot blasting, mechanical polishing, and rolling, The substrate surface may be treated based on a chemical method such as etching.
[0021]
The anodized film-coated member according to the present invention is first roughened on the surface of an Al alloy substrate to a surface roughness specified by the present invention to 0.1 to 5 μm [see FIG. If an oxide film is formed, as shown in FIG. 3B, it is possible to obtain a film in which cell coupling portions are dispersed inside the film. In the cell growth process, the anodic oxide film is a cell in which both adjacent cells are united to reach the base material, or a single cell is divided on the way to the base material. The surface of the anodized film is almost the same as the shape of the substrate surface before the anodizing treatment. However, as shown in FIG. 3C, the surface may be polished and smoothed. In addition, it is indispensable to control the surface roughness defined in the present invention only on the surface of the substrate before the anodizing treatment. For example, as shown in FIG. 4, a substrate having a surface roughness of less than 0.1 μm is used. Even when anodized and the surface of the anodized film is formed to a surface roughness of 0.1 to 5 μm as defined in the present invention, thermal cracking occurs.
[0022]
If the thickness of the anodic oxide film is too thin, the effect of improving the corrosion resistance is not sufficiently exhibited. Therefore, the thickness is suitably 0.1 μm or more, preferably 0.5 μm or more, and more preferably 1 μm or more. Further, if the anodized film is too thick, the film is easily peeled off, so that it is suitably 200 μm or less, preferably 70 μm or less, and more preferably 50 μm or less.
[0023]
The chamber internal member to which the present invention is preferably used is not only a structural material of a vacuum chamber made of Al or Al alloy, but also a gas diffusion plate (GDP), a clamper, a shower head, a susceptor disposed in the vacuum chamber, All of the members such as a clamp ring and an electrostatic chuck that are made of Al or an Al alloy are applicable.
[0024]
The present invention does not limit the Al alloy used as the base material. For example, the chamber material is excellent in terms of mechanical strength, thermal conductivity, electrical conductivity, and corrosion resistance. A system alloy is desirable. 1000 series alloy is pure aluminum series, but in the case of 5000 series alloy, it should contain at least Si: 0.5% by weight or less and Mg: 0.5-6.0% by weight as alloy components. Preferably, in the case of a 6000 series alloy, it is preferable to contain at least Si: 0.2 to 1.2% by weight and Mg: 0.4 to 1.5% by weight as alloy components. In the case of an in-chamber member, a 2000 series alloy or a 7000 series alloy can be used in addition to the 5000 series alloy or 6000 series alloy. In addition, by containing Mg, Si, Cu, Fe, etc. as the alloy component of the Al alloy, it is effective in improving the crack resistance of the anodized film against high frequency and high temperature (thermal cycle) and reducing the internal stress of the oxide film. I know it will work. In particular, Mg and Si, which are constituent elements of a 6000 series alloy, are effective, and the effect may be affected by the final heat treatment conditions of the material.
[0025]
In the present invention, the electrolysis voltage at the time of anodizing may be constant, but the final voltage may be set higher than the initial voltage to make the substrate-side pore diameter larger than the surface-side pore diameter. Recommended. The reason is that the pore diameter on the surface side is preferably as small as possible in order to obtain excellent plasma resistance, while the internal structure on the substrate side of the porous layer has a pore diameter and cell from the viewpoint of improving gas corrosion resistance. This is because a structure having a large diameter is desirable. Specifically, the initial voltage for anodic oxidation is preferably 50 V or less, and more preferably 30 V or less. On the other hand, the final voltage of the anodic oxidation treatment is desirably set higher than the initial voltage. Specifically, it is preferably 30 V or higher, more preferably 50 V or higher, and even more preferably 70 V or higher.
[0026]
In setting the final voltage in the anodizing process higher than the initial voltage, there are a method of changing the anodizing voltage continuously throughout the whole process and a method of changing it stepwise. In other words, the anodic oxidation voltage may be changed continuously and / or discontinuously in any section of the whole process, or any other section including the changed part in any section of the whole process. The voltage may be kept constant. In this way, the anodizing voltage when forming the anodized film is changed in an arbitrary section of the entire process, and the layers having different internal structures are combined or laminated, so that the anodized film and the gas or Stress and volume changes caused by plasma contact can be alleviated, and as a result, cracking and peeling of the film, which is the starting point of corrosion and damage, can be suppressed to improve gas corrosion resistance and plasma resistance. We can expect to show.
[0027]
In the present invention, when an anodized film is formed on an Al alloy substrate, electrolysis is performed with a solution containing one or more elements selected from the group consisting of C, S, N, P, F, and B. For example, it is desirable to perform electrolysis using an aqueous solution containing at least one selected from the group consisting of oxalic acid, phosphoric acid, boric acid or a compound thereof, phthalic acid or a compound thereof.
[0028]
Furthermore, it is recommended to first perform a porous type anodizing treatment and then perform a non-porous type anodizing treatment. The porous type anodizing treatment means a normal anodizing treatment for forming anodized film cells in terms of aluminum surface treatment in JIS H 0201, and any one of sulfuric acid, phosphoric acid, oxalic acid and chromic acid as an electrolytic solution. Or using these mixed solutions may be anodized at an electrolytic voltage of 5 to 200V. The non-porous type anodizing treatment refers to anodizing treatment for growing a barrier layer without forming pores. Specifically, boric acid solution, phosphoric acid solution, phthalic acid solution, adipic acid solution Examples include a method of anodizing at an electrolytic voltage of 60 to 500 V using any one of a solution, a carbonic acid solution, a citric acid solution, a tartaric acid solution, a sodium chromate solution, or a mixed solution thereof. it can.
[0029]
As the Al alloy base material, the average particle size of the crystallized product and the precipitate is 10 μm or less, or the crystallized product and the precipitate are parallel to the member surface having the largest area in the member surface. By using the Al alloy material adjusted so as to be arranged, the corrosion resistance of the substrate itself can be expected in addition to the corrosion resistance of the anodized film. Moreover, it is preferable that the average particle diameter of a crystallized substance and a precipitate is 10 micrometers or less, and the arrangement direction of a crystallized substance and a precipitate is parallel to the member surface which has the largest area. The volume fraction of the crystallized product and the precipitate is recommended to be 2% or less.
[0030]
Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are not of a nature that limits the present invention, and any design changes may be made in accordance with the gist of the present invention. It is included in the range.
[0031]
【Example】
Example 1
By subjecting the surface of a base material made of a 5000-series or 6000-series Al alloy to shot blasting, the surface roughness shown in Table 1 is obtained, and anodization treatment is performed using various electrolytic solutions listed in Table 1. A piece was made. The obtained test pieces were subjected to the following tests to evaluate the heat cracking resistance and gas corrosion resistance.
[0032]
[Heat cracking test]
After heating at 450 ° C. for 1 hour, the heat cycle exposed to the atmosphere for 24 hours was repeated three times, and the crack length in an arbitrary region of 10 cm ² was measured and evaluated as follows.
◎: No cracking ○: Crack length less than 80 mm Δ: Crack length of 80 mm or more and less than 160 mm ×: Crack length of 160 mm or more
[Gas corrosion resistance test]
After heating at 400 ° C. for 4 hours, two sets of thermal cycles exposed to the atmosphere for 24 hours were repeated, and the area ratio at which corrosion occurred was measured and evaluated as follows.
◎: No corrosion occurrence ○: Corrosion occurrence area ratio less than 10% Δ: Corrosion occurrence area ratio 10% or more and less than 20% ×: Corrosion occurrence area ratio 20% or more The results are shown in Table 1.
[0034]
[Table 1]

[0035]
No. 1 to 7 are anodized film-coated members according to the present invention, and all are excellent in heat cracking resistance and gas corrosion resistance. On the other hand, no. 8 to 11 are comparative examples in which the surface roughness specified in the present invention is too large or too small, and it is understood that both are inferior in heat cracking resistance and gas corrosion resistance.
[0036]
Example 2
Except that the surface roughness defined in the present invention was measured on the surface after the anodizing treatment, various test pieces shown in Table 2 were prepared in the same manner as in Example 1, and the heat crack resistance and gas corrosion resistance were measured. evaluated. The results are also shown in Table 2.
[0037]
[Table 2]

[0038]
No. 1-4 are anodized film-coated members according to the present invention, and all are excellent in heat cracking resistance and gas corrosion resistance. On the other hand, no. Nos. 5 to 8 are comparative examples in which the surface roughness specified in the present invention is too large or too small, and it is understood that both are inferior in heat cracking resistance and gas corrosion resistance.
[0039]
No. As shown in FIG. 4, after forming an anodic oxide film on a base material having a smooth surface outside the scope of the present invention, the surface is roughened by blasting, and in this case as well, heat cracking resistance It can also be seen that the gas corrosion resistance is poor.
[0040]
Example 3
An anodic oxide film having the internal structure of FIGS. 1 to 4 shown in Table 3 was formed by performing shot blasting or surface polishing on the surface of a base material made of a 6000 series Al alloy. The obtained test piece was subjected to the same test as in Example 1 to evaluate heat cracking resistance and gas corrosion resistance. The results are shown in Table 3.
[0041]
[Table 3]

[0042]
No. 1 and 2 are anodized film-coated members according to the present invention, both of which are excellent in heat cracking resistance and gas corrosion resistance. On the other hand, no. Nos. 3 to 5 are comparative examples in which the cell bonding portions are not uniformly dispersed in the anodized film, and it is understood that all are inferior in heat cracking resistance and gas corrosion resistance.
[0043]
【The invention's effect】
Since the present invention is configured as described above, it is possible to provide an anodized film-coated member for a semiconductor manufacturing apparatus that has excellent heat cracking resistance and good corrosion resistance.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing the structure of a conventional anodic oxide film.
FIG. 2 is a schematic explanatory view showing the structure of a conventional anodic oxide film.
FIG. 3 is a schematic explanatory view showing the structure of an anodized film according to the present invention.
FIG. 4 is a schematic explanatory view showing the structure of a comparative anodized film.
[Explanation of symbols]
1 Base material 2 Coating 3 Cell

Claims (2)

A method for producing an anodized film-coated member having an anodized film on an Al or Al alloy substrate, wherein the surface roughness of the substrate is measured by the following methods (i) and (ii) An anodized film coating for a semiconductor manufacturing apparatus excellent in heat cracking resistance and corrosion resistance, comprising a step of performing a surface treatment so as to be 0.1 to 5 μm and a step of anodizing the base material Manufacturing method of member.
(i) Measure the surface roughness at 3 or more locations on a line segment of 25 μm length arbitrarily selected on the surface of the substrate, and remove the maximum and minimum values from the measured values. The measurement value A is the measured value of the surface roughness of at least the place (in the case of two or more places, the average value).
(ii) This operation is repeated three times or more, and the average of the measured value A is defined as the surface roughness. The method for producing an anodized film-coated member for a semiconductor production apparatus according to claim 1 , wherein a method of surface-treating the substrate is any one of shot blasting, mechanical polishing, rolling, and etching.

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