JP2001220637A - Aluminum alloy for anodic oxidation treatment, aluminum alloy member having anodically oxidized film and plasma treating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy for anodic oxidation treatment excellent in heat cracking resistance and corrosion resistance in a high temperature corrosive environment or moreover capable of realizing the excellent reduction of contamination and to provide an aluminum alloy member having an anodically oxidized film or the like. SOLUTION: This aluminum alloy for anodic oxidation treatment contains, by weight, 0.1 to 2.0% Si, 0.1 to 3.5% Mg, 0.02 to 4.0% Cu, and the balance Al with impurity elements. Among the impurity elements, preferably, the content of Fe is controlled to <=0.1%, Cr to<=0.04% and Mn to <=0.04%, and furthermore, the total of the impurity elements other than Fe, Cr and Mn is preferably controlled to <=0.1%. Moreover, the aluminum alloy member in this invention is the one obtained by depositing an anodically oxidized film on the surface of a base material composed of the above alloy. This invention is suitably utilized for various members used in a high temperature corrosive environment, particularly, in high temperature corrosive gas and plasma environments.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy suitable for anodizing and an aluminum alloy member having an anodized film formed on a surface of a substrate formed of the aluminum alloy. Suitable for various applications requiring heat cracking resistance and corrosion resistance under high-temperature corrosive environment, for example, vacuum chambers used in plasma processing equipment such as semiconductor and liquid crystal manufacturing equipment, and materials suitable for components provided inside the chambers Used.

[0002]

2. Description of the Related Art An anodizing treatment for forming an anodized film on the surface of an aluminum alloy substrate to impart corrosion resistance, abrasion resistance and the like to the substrate has been frequently performed. . For example, various components such as a vacuum chamber used in a plasma processing apparatus of a semiconductor manufacturing facility and electrodes installed therein are mainly formed of an aluminum alloy, but the corrosion resistance and abrasion resistance of a pure aluminum alloy as it is. In general, the base material formed of an aluminum alloy is subjected to an anodic oxidation treatment, so that an anodic oxide film is formed on the surface thereof. The reason is that, inside the vacuum chamber, various kinds of corrosive gas, plasma or various kinds of materials are processed in a pretreatment process or a manufacturing process of a semiconductor in a high temperature environment from room temperature to 200 ° C. or more in an object to be processed such as a silicon wafer. Since predetermined processing is performed by the active species obtained by the plasma, various components such as the inner surface of the vacuum chamber and the plasma electrode installed inside the vacuum chamber are also exposed to the atmosphere, and a pure aluminum alloy is used. This is because corrosion resistance and wear resistance cannot be maintained as it is.

[0003] As the aluminum alloy, Al is mainly used.
-Mg-based alloy (JISA5000-based), Al-Mg-Si
Alloys (JISA6000 series) are used, but in recent years, in order to cope with miniaturization of device design rules and high density of plasma, further high corrosion resistance of members,
It has been required to reduce the pollution of the object to be treated.

In order to satisfy these requirements, high-purity aluminum (Al:
99.9 wt% or more) or as described in JP-A-10-88271, Si and Mg are added to high-purity aluminum, and the total amount of other impurities is 0.1%.
% Has been proposed.

[0005]

However, the members obtained by anodizing the substrate made of these aluminum alloys can reduce the contamination caused by the anodic oxide film itself to some extent, but in any case, from the room temperature. In a corrosive gas at a high temperature of 200 ° C or higher and in a plasma environment, the expansion difference due to the difference in the coefficient of thermal expansion between the base aluminum alloy and the anodic oxide film cannot be reduced, and the anodic oxide film cracks. Corrosion then progresses along the cracks. As a result, not only the life of the member is shortened, but also particles are generated, which causes contamination of an object to be processed in the plasma processing.

The present invention has been made in view of the above problems, and an aluminum alloy for anodic oxidation treatment capable of achieving excellent heat cracking resistance and corrosion resistance in a high-temperature corrosive environment, or capable of realizing further excellent low pollution. It is an object of the present invention to provide an aluminum alloy member having an anodized film.

[0007]

According to the present invention, the aluminum alloy for anodizing treatment has a chemical composition of 0.1% to 2.0% by weight of Si, 0.1% by weight of Mg and 0% by weight of Mg. .1
-3.5%, Cu: 0.02-4.0%, the balance containing Al as an essential component, and other impurity elements.

According to the present invention, a predetermined amount of Si and M
g, precipitates (Mg ₂ Si) are precipitated by aging, and Cu is concentrated around the Mg ₂ Si. By performing anodizing treatment in this state, the cells 3 in the anodized film are formed. Voids are formed at the point of interest that are sufficient to reduce the difference in the coefficient of thermal expansion. For this reason, the occurrence of cracks in the anodic oxide film is suppressed and prevented in a high temperature environment, the original corrosion resistance of the anodic oxide film is exhibited, and the heat crack resistance and the corrosion resistance are excellent. Further, since corrosion caused by cracks caused by a difference in thermal expansion is prevented, contamination caused by corrosion products can be suppressed and prevented.

According to the present invention, among the impurity elements, Fe: 0.1% or less, Cr:
0.04% or less, Mn: 0.04% or less is preferable, and further, as described in claim 3, Fe, C
It is preferable to keep the total sum of impurity elements other than r and Mn to 0.1% or less. As a result, the amount of impurity elements in the anodic oxide film can be reduced, contamination due to the film itself can be suppressed, and excellent low contamination can be realized.

[0010] Further, the aluminum alloy member of the present invention comprises:
As described in claim 4, an anodic oxide film is formed on the surface of the base material made of the aluminum alloy described in claim 1, 2 or 3.

According to the present invention, the difference in thermal expansion between the base material and the anodic oxide film is reduced, the occurrence of cracks in the anodic oxide film in a high temperature environment is suppressed and prevented, and the original corrosion resistance of the anodic oxide film is exhibited. As a result, the resistance to heat cracking and corrosion resistance is excellent, and furthermore, the corrosion caused by cracking is prevented, so that low pollution can be realized.

According to a fifth aspect of the present invention, there is provided a plasma processing apparatus for performing a predetermined process on an object to be processed by using plasma or active species obtained by forming a plasma in a vacuum chamber. Wherein at least one of the vacuum chamber and components provided therein is formed of an aluminum alloy member having an anodized film formed on a surface of the aluminum alloy base material according to claim 2 or 3. It was done.

According to this plasma processing apparatus, at least one of the vacuum chamber and the components provided therein, that is, the vacuum chamber, or at least one of the components provided in the vacuum chamber, or both of them are required. Item 2 or 3, which is constituted by an aluminum alloy member having an anodic oxide film formed on the surface of the base material made of the aluminum alloy described in Item 2 or 3, so that the member can be used in an atmosphere such as a high-temperature corrosive gas or plasma in a vacuum chamber. It has excellent heat cracking resistance and corrosion resistance, and can also reduce contamination due to impurity elements caused by the anodic oxide film itself. The production yield is improved.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION
Under the above high-temperature corrosive environment, in order to realize an aluminum alloy member having an anodic oxide film that has good heat cracking resistance and corrosion resistance and can realize low pollution.
As a result of intensive research, they have found that there is a correlation between the additive element component in the aluminum alloy forming the base material and the corrosion resistance of the anodic oxide film, and found that Si is an additive element component that forms the high corrosion resistant anodic oxide film. , Mg, and Cu. That is, in a member having an anodized film formed on an aluminum alloy to which only Si or Mg is added or a high-purity aluminum material such as JIS Al000 as a base material, the anodized film is formed in a high temperature corrosive gas environment from room temperature to 200 ° C. or more. Cracks occur due to heat, and the base material is corroded by the corrosive gas entering the cracks.
The inherent corrosion resistance of the anodic oxide film could not be exhibited, and particles due to corrosion products were generated. However, S
i, by adding an appropriate amount of Cu other than Mg, the anodic oxide film does not crack, so that the corrosive gas does not come into contact with the base material, it is possible to express excellent corrosion resistance at high temperatures, It has been found that the generation of particles can be suppressed by pulling.

The mechanism by which Mg, Si, and Cu present in the base material exert an effect on the corrosion resistance of the anodic oxide film is currently being investigated, but Mg ₂ S deposited in the base material is being investigated.
It has been ascertained that by performing anodizing treatment in a state where Cu is concentrated around i, sufficient voids are formed at the triple point of the cells in the coating to reduce the difference in the coefficient of thermal expansion. Furthermore, it is speculated that the elements of Mg, Si, and Cu may have an effect on each cell formed during the anodic oxidation treatment so as to develop resistance to thermal cracking.

Further, as a result of intensive studies on the content of elements contained in the aluminum alloy, it was found that the chemical composition was wt.
0.1-2.0%, Mg: 0.1-3.5% and C
It has been found that desired heat cracking resistance and corrosion resistance can be imparted by forming an anodized film on an aluminum alloy containing u: 0.02 to 4.0% as an essential component as a base material. Therefore, the impurity element Fe,
Other elements such as Cr and Mn do not deteriorate the corrosion resistance even if the content is reduced in order to reduce the contamination caused by the film itself.

The present invention has been made based on the above findings. First, the reasons for limiting the components of the aluminum alloy of the present invention will be described. The unit of the component is wt%.

Si: 0.1 to 2.0% Mg: 0.1 to 3.5% Si and Mg are elements necessary for precipitating a Mg ₂ Si precipitate by aging. Less than 1%, Mg:
If the amount is less than 0.1%, the precipitate Mg ₂ Si is scarcely formed, so that it is not possible to form a void at the triple point of the cell to reduce the thermal expansion. On the other hand, Si: more than 2.0%, M
g: If it exceeds 3.5%, coarse crystals such as Mg ₂ Si,
Al _m Mg _n (Al ₃ Mg _2, Al ₁₂ Mg ₁₇ ) and coarse Si
A precipitated phase is formed, which remains in the anodic oxide film and becomes a defect, and deteriorates corrosion resistance.

Cu: 0.02 to 4.0% Cu is anodized in a state of being concentrated around Mg ₂ Si to reduce the difference in the coefficient of thermal expansion at the triple point of the cell in the anodic oxide film. It has the effect of forming a void sufficient to perform If the content is less than 0.02%, the effect is too small. On the other hand, if the content exceeds 4.0%, the growth of the film is greatly inhibited, and the treatment takes a long time. Further, the film dissolves in the electrolytic solution during the long-term treatment, and the film properties become non-uniform. Therefore, the lower limit of Cu is set to 0.02%, preferably 0.1%, and the upper limit is set to 4.0%, preferably 0.15%.

The aluminum alloy of the present invention has the above Si, M
g, Cu and the balance Al are essential components and are formed by other impurities.
If a heavy metal such as r or Mn occupies the position of a substitutional impurity in an object to be processed such as a wafer, the characteristics of a semiconductor device (device) such as an increase in junction leak current are caused.
e, Cr, and Mn are preferably kept to 0.1% or less, 0.04% or less, and 0.04% or less, respectively. As a result, the amount of contamination from the anodic oxide film itself can be suppressed, the characteristic failure of the semiconductor device can be suppressed, and the manufacturing yield can be improved.

In addition to the above Fe, Cr and Mn, Ni, Z
Since the presence of impurity elements such as n, Ti, B, Ca, Na, and K may affect the contamination of the object to be treated, the total of these impurity elements is 0.1% or less from the viewpoint of reducing pollution. It is preferable to stop at.

The aluminum alloy member of the present invention is obtained by forming an anodized film on the surface of a substrate made of the aluminum alloy. The base material is obtained by subjecting an ingot of the aluminum alloy to rolling, forging, solution treatment of an aluminum alloy material obtained by appropriate plastic working such as extrusion, aging treatment, and then machining into an appropriate shape. After the aluminum alloy material is formed into a predetermined shape, a solution treatment and an aging treatment may be performed. The conditions of the solution treatment and the aging treatment are, for example, a normal T6 treatment: solution treatment 515 to 550 ° C., water cooling, aging treatment 170 ° C. × 8 hr, 155 to 165 ° C. × 1
8 hours can be performed. By performing anodic oxidation treatment on such a substrate, an anodic oxide film excellent in heat crack resistance and corrosion resistance is formed on the surface of the substrate.

As a method of forming the anodic oxide film, conditions such as electrolysis conditions, that is, the composition and concentration of the electrolytic solution, and electrolysis conditions (voltage, current density, current-voltage waveform) are appropriately selected. Just do it. For the anodizing solution,
It is necessary to perform electrolysis in a solution containing at least one element selected from C, S, N, P, and B. For example, oxalic acid, formic acid, sulfamic acid, phosphoric acid, phosphorous acid, boric acid It is effective to use an aqueous solution containing at least one selected from acetic acid, nitric acid or a compound thereof, and phthalic acid or a compound thereof. Although the thickness of the anodic oxide film is not particularly limited, it is about 0.1 to 200 μm, preferably 0.5 to 7 μm.
About 0 μm, more preferably about 1 to 50 μm is appropriate.

The aluminum alloy member is suitable for various uses used in a high-temperature corrosive atmosphere, but is particularly exposed to a corrosive gas, plasma, or an active species obtained by plasmatization in a high-temperature environment. On the other hand, it is suitably used as a vacuum chamber used in a plasma processing apparatus attached to a semiconductor manufacturing facility or the like in which an object to be processed is required to have low contamination, and as components such as electrodes provided inside the vacuum chamber.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not construed as being limited to such Examples.

[0026]

EXAMPLE An aluminum alloy having the composition shown in Table 1 below was melted, an ingot obtained by casting was cut, face-cut, and then subjected to soaking. After soaking, the 45 mm thick material was rolled into a 4 mm thick plate by hot rolling, subjected to a solution treatment, and then subjected to a normal T6 treatment to obtain a match metal plate. A 35 × 25 mm test piece was sampled from this alloy plate, the surface of the test piece was chamfered, and then anodized. Table 1 shows the processing solutions and the electrolytic voltages used for the anodizing treatment. The temperature of the treatment liquid was set to room temperature, and the treatment was performed until a predetermined film thickness was obtained.

In order to evaluate the heat cracking resistance and gas corrosion resistance of the sample manufactured as described above, the temperature was changed from room temperature to 250 ° C.
Thermal crack resistance test in which 5 heating / cooling cycles up to 100 ° C are performed.
Halogen gas corrosion resistance test for holding at hr was performed, and heat crack resistance and gas corrosion resistance of the anodic oxide film under a high-temperature heat cycle and a corrosive environment were evaluated according to the following criteria. Evaluation criteria for heat cracking resistance ：: no cracking ○: crack length less than 80 mm / 10 cm ² △: crack length 80 mm / 10 cm ² or more to 160 mm / 10 cm
Less than ² ×: Crack length 160 mm / 10 cm ² or more Gas corrosion resistance evaluation criteria ：: No corrosion occurred ○: Corrosion occurrence area ratio less than 10% △: Corrosion occurrence area ratio 10% or more, less than 20% ×: Corrosion occurrence area 20% or more

For Sample Nos. 16 to 23, the film formation rate was measured, and the anodic oxidizing property due to the difference in Cu content was evaluated based on the following criteria. · Anodizing treatment evaluation criteria ○: 20 μm / hr or more Δ: 8 μm / hr or more, less than 20 μm / hr ×: less than 8 μm / hr

The results of evaluation of the above-mentioned heat cracking resistance, gas corrosion resistance and anodic oxidation treatment properties are also shown in Table 1. Table 1
The sample No. 5 aluminum alloy is commercially available JISA60
Equivalent to 61 aluminum alloy. From Table 1, Si, M
For the samples (Nos. 1 to 10 and Nos. 18 to 22) in which the contents of g and Cu satisfy the conditions of the present invention, good heat cracking resistance, gas corrosion resistance and anodizing property are obtained. Was. On the other hand, No. 23 having a Cu content exceeding the range of the invention had good heat cracking resistance and gas corrosion resistance, but markedly deteriorated anodizing property.

[0030]

[Table 1]

Next, the contamination of the aluminum alloys of Sample Nos. 1 to 7 in substrate processing was examined by a plasma processing apparatus. The vacuum chamber for the plasma processing apparatus is a processing chamber having a depth of φ270 mm × 100 mm from a material obtained by rolling an ingot to produce a thick plate of an aluminum alloy and subjecting it to a solution treatment and an aging treatment (T6). A substrate for a vacuum chamber having the following characteristics was produced by machining, and a 20 μm anodic oxide film was formed on the surface of the substrate under the same processing conditions as in Table 1. An upper lid made of SiO ₂ glass was hermetically assembled on the opening of the vacuum chamber, and an antenna for high-frequency generation was installed directly above the upper lid. A substrate (silicon wafer) having a diameter of 150 mm was set on an electrode plate provided inside the vacuum chamber. The electrode plate is made of the same material as the substrate for the vacuum chamber, and has a 20 μm anodic oxide film formed under the same conditions. The vacuum chamber was provided with an exhaust pipe and a gas supply pipe communicating with the inside of the vacuum chamber.

In the plasma test, a plasma is generated under the following conditions, and after exposing the substrate to a corrosive gas and plasma for 2 hours, the total amount of Fe, Cr, and Mn on the substrate is measured. The degree of contamination was evaluated. Test conditions Gas used: Chlorine gas Gas pressure: 10 mTorr Gas flow rate: 100 sccm RF power: ICP 100 W RF generation time: 2 hr (test time) Substrate contamination evaluation criteria Sample No. 5 aluminum alloy (equivalent to 6061 commercially available material) ), The total amount of Fe, Cr, and Mn of the substrate plasma-treated by the vacuum chamber (reference chamber) is 100%
◎: less than 50% of the reference chamber ○: 50% to less than 80% of the reference chamber △: 80% to 95% of the reference chamber

The results are shown in Table 1 above. From Table 1, among the aluminum alloys of Sample Nos. 1 to 7, Fe,
No. in which Cr and Mn are not more than a predetermined amount specified in the present invention.
In Nos. 1 to 4, low contamination of the substrate is realized. However, No. 4 has a slightly larger amount of other impurities, such as 0.15%, so that the degree of contamination is slightly larger than that of the others. On the other hand, F
e, Cr, Mn, N
o. 5 to 7 have good heat cracking resistance and gas corrosion resistance, but are inferior to low contamination of the substrate as compared with Nos. 1 to 4.

[0034]

According to the aluminum alloy and the aluminum alloy member of the present invention, an anodic oxide film excellent in heat cracking resistance and gas corrosion resistance can be obtained, and, in addition, it has low pollution and high temperature. It can be suitably used in a corrosive gas or plasma environment. Further, according to the plasma processing apparatus of the present invention, excellent low pollution can be realized in the plasma processing, and the production yield of the object to be processed can be improved.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H05H 1/46 H01L 21/302 B (72) Inventor Atsushi Hisamoto 1-chome Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture No.5-5 Kobe Steel Ltd. Kobe Research Institute F-term (reference) 5F004 AA16 BB29 BB30 5F045 BB14 EB03 EC05 EM09

Claims (5)

[Claims] 1. The chemical composition is wt%, and Si: 0.1-2.
0%, Mg: 0.1 to 3.5%, Cu: 0.02 to 4.
Anodizing aluminum alloy containing 0%, balance Al as an essential component, and other impurity elements. 2. The method according to claim 1, wherein Fe: 0.1% or less among the impurity elements.
Cr: 0.04% or less, Mn: 0.04% or less,
The aluminum alloy for anodizing treatment according to claim 1. 3. The anodized aluminum alloy according to claim 2, wherein the total amount of impurity elements other than Fe, Cr, and Mn is 0.1% or less. 4. An aluminum alloy member having an anodized film, wherein an anodized film is formed on a surface of the substrate made of the aluminum alloy according to claim 1. 5. A plasma processing apparatus for performing a predetermined process on an object to be processed by plasma or an active species obtained by converting the plasma into a plasma in a vacuum chamber, wherein the vacuum chamber and components provided therein are provided. A plasma processing apparatus comprising an aluminum alloy member having an anodized film, wherein the plasma processing device comprises an aluminum alloy member having an anodized film formed on a surface of at least one of the aluminum alloys according to claim 2 or 3. .