KR20090020496A - Anodized aluminum alloy material having both durability and low polluting property - Google Patents

Abstract

Anodized aluminium alloy having durability and the low polluting property is provided to secure plasma-resistance by controlling the content of Fe. Anodized aluminium alloy having durability and the low polluting property includes Mg of 0.1~2.0wt%, Si of 0.1~2.0wt%, Mn of 0.1~2.0wt%, Fe, Cr, Cu, Al and inevitable impurities. The content of Fe, Cr and Cu are restricted with 0.03% below. The surface of the alloy is coated with an anodized film. A different part is formed according to the thickness of the anodized film.

Description

ANODIZED ALUMINUM ALLOY MATERIAL HAVING BOTH DURABILITY AND LOW POLLUTING PROPERTY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy, and in particular, used in a member of a vacuum chamber of a semiconductor or liquid crystal manufacturing apparatus such as a CVD apparatus, a PVD apparatus, an ion implantation apparatus, a sputtering apparatus, a dry etching apparatus, or a member provided therein. Anodized aluminum alloy.

A corrosive gas containing a halogen element as a reactive gas, an etching gas, or a cleaning gas is introduced into a vacuum chamber of a semiconductor or liquid crystal manufacturing apparatus such as a CVD apparatus, a PVD apparatus, an ion implantation apparatus, a sputtering apparatus, or a dry etching apparatus. For this reason, corrosion resistance to corrosive gas (hereinafter referred to as gas corrosion) is demanded. In addition, since many halogen-based plasmas are generated in the vacuum chamber, resistance to plasma (hereinafter referred to as plasma resistance) is also important (Japanese Patent Application Laid-Open No. 2003-34894, Japanese Patent). See Application Publication No. 2004-225113, et al. In recent years, aluminum or an aluminum alloy has been adopted as a member of such a vacuum chamber because of its light weight and excellent thermal conductivity.

However, since aluminum and aluminum alloys do not have sufficient gas corrosion resistance and plasma resistance, various surface modification techniques for improving these characteristics have been proposed. However, these characteristics are still insufficient, and further improvement is expected.

In order to improve the plasma resistance, it is effective to form a high hardness anodized film on the surface of aluminum or an aluminum alloy. This is because the high hardness anodized film is resistant to abrasion of the member due to the physical energy of the plasma, so that the plasma resistance can be improved (see Japanese Patent Application Laid-Open No. 2004-225113, etc.).

However, by simply forming a high hardness anodized film on the surface of aluminum or an aluminum alloy, even if plasma resistance can be improved, cracks are likely to occur in the high hardness anodized film. In addition, once a crack is generated and penetrates the anodized film, a corrosive gas penetrates through the penetrated crack (hereinafter referred to as a through crack), and the aluminum or aluminum alloy as a base material is corroded. Occurs.

Therefore, an anodized film not only having high hardness but also having durability (crack resistance and corrosion resistance) is expected.

In addition, when the content of Fe in the aluminum alloy is reduced from the viewpoint of suppressing the contamination of Fe to the object to be treated such as a semiconductor wafer or a glass substrate for liquid crystal, an anodized film having a low content of Fe can be surely formed. However, such anodization film becomes harder, further deteriorating crack resistance and gas corrosion resistance. Therefore, in such a field, it is expected to improve the durability (crack resistance and gas corrosion resistance) while ensuring low pollution.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2003-34894

[Patent Document 2] Japanese Patent Application Laid-Open No. 2004-225113

The present invention has been made in view of the above circumstances, and an object thereof is to provide anodized aluminum alloy having durability and low pollution even at high hardness.

In order to achieve the said objective, invention of Claim 1 of this invention is Mg: 0.1-2.0% (meaning "mass%", the same below), Si: 0.1-2.0%, Mn: 0.1-as an alloy component. An anode comprising 2.0% of aluminum alloy containing 2.0% of each of Fe, Cr and Cu, each of which is regulated to 0.03% or less, the remainder being Al and inevitable impurities, and an anodized film formed on the surface of the aluminum alloy. It is an oxidation-treated aluminum alloy, It has a site | part which differs in hardness in the thickness direction of the said anodizing film, The difference between the site | part which has maximum hardness and the site | part which is minimum is Vickers hardness, It is characterized by the above-mentioned. As a result, even in high hardness, anodized aluminum alloy having both durability and low pollution can be realized.

In the invention described in claim 2, in the invention described in claim 1, the Vickers hardness of the portion having the minimum hardness is 365 or more. Thereby, plasma resistance improves.

As described above, the present invention contains Mg: 0.1 to 2.0% (the meaning of " mass% ", below) as the alloy component, Si: 0.1 to 2.0%, Mn: 0.1 to 2.0%, and Fe, Cr and Each content of Cu is regulated to 0.03% or less, respectively, and remainder is an anodizing aluminum alloy provided with the aluminum alloy which consists of Al and an unavoidable impurity, and the anodizing film formed on the surface of this aluminum alloy, The said anodizing film Since the difference in the thickness direction between the portion having the highest hardness and the portion having the smallest hardness is 5 or more in Vickers hardness, it is possible to provide anodized aluminum alloy having durability and low pollution even at high hardness.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail, illustrating embodiment.

(Configuration of Anodized Aluminum Alloy Having Durability and Low Pollution Pertaining to the Present Invention)

The anodized aluminum alloy having durability and low pollution according to the present invention is Mg: 0.1 to 2.0% (the meaning of "mass%", hereinafter the same), Si: 0.1 to 2.0%, Mn: 0.1 to An anode comprising 2.0% of aluminum alloy containing 2.0% of each of Fe, Cr and Cu, each of which is regulated to 0.03% or less, the remainder being Al and inevitable impurities, and an anodized film formed on the surface of the aluminum alloy. It is an oxidation-treated aluminum alloy, It has a site | part which differs in hardness in the thickness direction of the said anodic oxide film, The difference between the site | part which has maximum hardness and the site | part which is minimum is Vickers hardness, It is characterized by the above-mentioned. As a result, it is possible to provide an anodized aluminum alloy having durability and low pollution even at high hardness.

The reason for reaching the above configuration will be described in detail below.

The present inventors first suppressed the contents of Fe, Cr, and Cu in the aluminum alloy so as not to contaminate the object to be treated such as a semiconductor. In particular, the anodic oxide film produced by suppressing the Fe content is hardened, and the property that plasma resistance can be secured is actively utilized. However, even if a crack occurs in the anodized film, the crack extends to the aluminum alloy itself. We politely examined whether we could prevent it. As a result, the conditions for forming the anodic oxide film were studied, and the cracks were made of aluminum by having a site having a different hardness in the thickness direction of the anodic oxide film, and having a difference in the hardness of the site having the largest hardness and the minimum site being 5 or more in Vickers hardness. We found that the alloy itself could not be extended. As a result, the intrusion of gas into the aluminum alloy itself is also suppressed, and the total durability is ensured. The detailed mechanism of why the above problem can be solved by such a configuration has not been elucidated yet. However, as one mechanism, it is thought that the extension of the crack is absorbed or suppressed at the site of small hardness, and as a result, the crack does not extend to the aluminum alloy itself.

The present invention is described in detail below.

[Component in Aluminum Alloy]

Mg, Si, and Mn present in the aluminum alloy are combined with Mg ₂ Si and Al-Mn-Si compound or Al-Mn compound, but the detailed mechanism is not clear, but it is inferred to strengthen the anodized film.

Mg: 0.1 to 2.0%

Mg is an element necessary for forming the Mg ₂ Si compound, less than 0.1% since the Mg ₂ Si compound is not substantially formed, the desired effect can not be obtained increase in the durability of the anode oxide film. On the other hand, when it is more than 2.0%, the Mg ₂ Si compound is coarsened and rather inhibits the formation of a normal anodized film. Therefore, the minimum of content of Mg is 0.1%, and the upper limit is 2.0%. Preferably it is 0.8%.

Si: 0.1% to 2.0%

Si is an element necessary for forming Mg ₂ Si compound together with Mg, and since these compounds are hardly formed at less than 0.1%, the desired durability improvement effect of the anodized film cannot be obtained. On the other hand, when it is more than 2.0%, the Mg ₂ Si compound is coarsened and rather inhibits the formation of a normal anodized film. Therefore, the minimum of content of Mg is 0.1%, and the upper limit is 2.0%. Preferably it is 1.2%.

Mn: 0.1% to 2.0%

Mn is an essential element for forming the Al-Mn-Si compound or Al-Mn compound, and since these compounds are hardly formed at less than 0.1%, the desired durability improvement effect of the anodized film cannot be obtained. On the other hand, at more than 2.0%, the compound coarsens and rather inhibits the formation of a normal anodized film. Therefore, the minimum of content of Mn is 0.1%, and the upper limit is 2.0%. Preferably it is 1.6%.

Fe, Cr and Cu: 0.03% or less, respectively

Since the electricity used in the anodic oxidation treatment is used to generate oxygen by ionization of aluminum and electrolysis of water, the proportion of electricity used to generate oxygen decreases as the ratio of electricity used to generate oxygen decreases. The efficiency of formation is lowered, which slows down the deposition rate. In addition, when Fe, Cr, and Cu exist in an aluminum alloy, these elements become a starting point of oxygen generation, the ratio of electricity used for oxygen generation becomes large, and film-forming speed becomes slow. Moreover, when content of Fe, Cr, and Cu exceeds 0.03%, respectively, it will be discharge | released in gas from a base material and an anodizing film, and will pollute a to-be-processed object, such as a semiconductor. Therefore, each content of Fe, Cr, and Cu is 0.03% or less, respectively, Preferably it regulates to 0.01% or less, respectively.

ㆍ Residual Al and Unavoidable Impurities

The remainder is substantially Al alone, but inevitable small amounts of impurity elements such as Ni, Zn, B, Ca, Na, and K other than Fe, Cr, and Cu are allowed. However, in order to further realize low pollution, it is preferable to regulate the total of impurity elements (inevitable impurities) other than Fe, Cr, and Cu to 0.1% or less.

In addition, when the crystal grains of the aluminum alloy are large, the crystal form appears on the anodized film and the color tone becomes uneven. Therefore, Ti may be contained to prevent this. If the content of Ti is too small, the effect of controlling the crystal grains cannot be obtained. If the content of Ti is too large, it causes contamination. Therefore, when Ti is contained, the lower limit thereof is 0.01% and 0.015%. It is preferable to set it as 0.03% and 0.025%.

[Method for producing aluminum alloy]

Next, the manufacturing method of an aluminum alloy is demonstrated.

First, the aluminum alloy ingot adjusted within the said component range is manufactured by selecting suitably the usual melt casting methods, such as a continuous casting method and a semicontinuous casting method (DC casting method), for example. Subsequently, the aluminum alloy ingot is subjected to homogenization heat treatment (also called "cracking treatment"). This homogenization temperature (also called "homogenization temperature" or "cracking temperature") is obtained by cracking at a temperature of 500 ° C. or higher to obtain an anodized film having excellent durability, and furthermore, durability by cracking at a temperature exceeding 550 ° C. This superior anodic oxide film can be obtained. However, when the homogenization treatment is performed at a temperature exceeding 600 ° C., burning or the like may occur, which may cause problems such as surface properties. Therefore, the homogenization treatment temperature is preferably in the range of 500 ° C. or higher (or more than 550 ° C.) or 600 ° C. or lower. It is not yet known how such a cracking temperature is related to the formation of a highly durable anodizing film, but as mentioned above, the formation of Al-Mn-Si compound or Al-Mn compound is involved. I think.

After the aluminum alloy ingot subjected to the homogenization treatment is subjected to solution treatment, quenching, and artificial aging treatment (hereinafter, simply referred to as "aging treatment") of the aluminum alloy obtained by appropriate plastic working such as rolling, forging, and extrusion, By machining into a suitable shape, a substrate of an aluminum alloy is produced. Alternatively, the aluminum alloy base material may be produced by forming the aluminum alloy into a predetermined shape and then performing solution treatment, quenching, and aging treatment. As the solution treatment, quenching, and aging treatment, for example, solution treatment 515 to 550 ° C., water quenching, and aging treatment 170 ° C. × 8 h and 155 ° C. to 165 ° C. × 18 h, which are normal T6 treatments, can be performed.

[About an anode oxide film]

Next, anodization film formed on the surface of the aluminum alloy base material will be described. As the method for forming the anodic oxide film, conditions such as electrolysis, that is, composition, concentration, and electrolysis conditions (voltage, current density, current-voltage waveform, temperature), and the like may be appropriately selected. As for the anodizing solution, it is necessary to perform electrolysis with 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 carry out using an aqueous solution containing at least one selected from nitric acid or the compound, phthalic acid or the compound. The film thickness of the anodic oxide film is not particularly limited, but is preferably about 0.1 to 200 μm, preferably about 0.5 to 70 μm, and more preferably about 1 to 50 μm.

As described above, since the difference in hardness in the thickness direction of the anodic oxide film is different, and the difference between the largest and smallest parts in the film is Vickers hardness of 5 or more, the film is cracked even at high hardness. Propagation is suppressed and it is excellent in crack resistance. As described above, since crack resistance is suppressed, intrusion of gas into the aluminum alloy itself is also suppressed as a result, and durability is assured as a whole. On the other hand, when the difference between the largest and smallest hardness sites is less than 5 as Vickers hardness, it exhibits substantially the same behavior as the case where the hardness is uniform (similarly) in the thickness direction of the anodized film. Radio wave is hard to be suppressed and crack resistance is inferior. Therefore, gas corrosion is also inferior.

In the present invention, the number of parts having different hardness in the thickness direction of the anodized film is required to be 2 or more, but the number of the parts is not particularly limited as long as it is 2 or more. In addition, in the thickness direction of the anodized film, the hardness may be changed intermittently or may be changed continuously (tiltwise).

Further, from the viewpoint of suppressing the propagation of cracks generated in the anodized film, it is thought that the Vickers hardness of the site having the smallest hardness should be as small as possible, but considering the resistance to wear caused by the physical energy of the plasma, It is preferable that it is 365 or more in Vickers hardness.

An aluminum alloy (hereinafter referred to as an anodized aluminum alloy) to which such anodization film has been applied is suitable for various applications used in a high temperature corrosive atmosphere. In particular, it is suitable as a component such as a vacuum chamber used in a plasma processing apparatus attached to a semiconductor manufacturing facility that is exposed to a corrosive gas and a plasma under a high temperature environment and requires low pollution to an object to be processed, and an electrode provided therein. Do.

In order to change the hardness of the anodizing film in the thickness direction of the anodizing film, a method of intermittently or continuously changing the temperature of the anodic oxidation solution during the anodic oxidation treatment, or stopping the anodic oxidation treatment midway, May be taken out from the anodic oxidation treatment liquid, and a method of restarting the anodic oxidation treatment with another anodic oxidation treatment liquid having a different liquid composition and / or temperature may be employed. Can change the hardness. In addition, the lower the temperature of the anodic oxidation treatment liquid, the chemical dissolution of the anodic oxide film during the anodic oxidation treatment is suppressed and harder.

In addition, as mentioned above, when contamination with to-be-processed objects, such as a semiconductor, is considered and the content of Fe in an aluminum alloy is suppressed to 0.03% or less, for example, content of Fe in an anodized film is suppressed to 500 ppm or less. do. Moreover, when content of Fe in an aluminum alloy is suppressed to 0.01% or less, content of Fe in an anodized film can be suppressed to 150 ppm or less.

As described above, the anodized aluminum alloy can satisfy durability (crack resistance and corrosion resistance) and low pollution even at high hardness.

EXAMPLE

EMBODIMENT OF THE INVENTION Hereinafter, this invention is described in detail based on an Example. However, the following Examples do not limit the present invention, and all modifications are made within the technical scope of the present invention without departing from the scope of the preceding and the later.

First, an aluminum alloy ingot having a component composition of {Examples (Samples No. 1, 2, 4, 5) and Comparative Examples (Samples No3, 6 to 14) described in Table 1 was solvent (size: width 220 mm). After the length 250 mm × thickness 100 mm and the cooling rate: 15 to 10 ° C./s, the ingot is cut and faced (size: width 220 mm × length 150 mm × thickness 60 mm). Cracking treatment (540 ° C. × 4 h) was performed. After the cracking treatment, the 60 mm thick substrate was rolled into a 6 mm thick sheet by hot rolling, after solution treatment (510 to 520 占 폚 for 30 minutes), water quenched, and the aging treatment (160 to 180 占 폚 x 8). h) was carried out to obtain the provided alloy plate. The test piece of 25 mm x 35 mm (rolling direction) x thickness 3mm was cut out from this alloy plate, and the surface was surface-treated with the surface roughness of Ra 1.6.

Table 1

Next, the test specimens were washed with water then immersed two minutes in -10% aqueous solution of NaOH 60 ℃, also after cleaning the surface by the process of washing with water after 2 minutes, immersed in 30 ℃ -20% HNO ₃ aqueous solution, Anodization treatment was performed in order of the first layer (the aluminum alloy base material side) and the second layer (the layer further formed on the first layer). The conditions for the anodic oxidation treatment are as described in Table 1 above, and the treatment liquid for both the first layer and the second layer is 25 g / L (where "L" means liter) oxalic acid, It fixed at 60V and made the thickness of the anodic oxide film formed into 15 micrometers. The other conditions for the anodic oxidation treatment of the first layer and the second layer were the temperature of the treatment liquid, and the temperature at the time of formation of the first layer was higher than the temperature at the time of formation of the second layer.

For the anodized aluminum alloy sample piece produced as described above (hereinafter simply referred to as a sample piece), the measurement of the content of Fe, Cr and Cu in the anodized film, the measurement of the hardness of the anodized film, and the The durability test was done.

[Measurement of Contents of Fe, Cr, and Cu in the Anodic Oxide Film]

In order to evaluate the contamination resistance of the sample pieces, the anodized film was dissolved in 100 mL of 7% hydrochloric acid (wherein "mL" means milliliters) so that the aluminum alloy base material is not exposed, and the weight change of hydrochloric acid before and after dissolution. The amount of dissolved W (g) of the anodic oxide film was calculated from the above. Subsequently, ICP analysis of the hydrochloric acid solution was performed to determine the respective concentrations of Fe, Cr, and Cu in hydrochloric acid, and to calculate the respective weights of Fe, Cr, and Cu dissolved in 100 mL hydrochloric acid, WFe, WCr, and WCu (g). The concentrations of Fe, Cr, and Cu in the anodic oxide film were determined from / W, WCr / W, and WCu / W. The contamination resistance was evaluated according to the following criteria with the concentrations of Fe, Cr, and CU in the anodic oxide film (the evaluation results are shown in Table 1 above).

ㆍ Pollution resistance evaluation standard

(Double-circle): All elements are 300 ppm or less, (circle): At least 1 element is more than 300 ppm and 500 ppm or less, other elements are 300 ppm or less, x: At least 1 element is more than 500 ppm

ㆍ Pollution resistance evaluation result

As shown in Table 1, in Comparative Examples (Samples No. 12 to 14), the content of any one element of the anodized film was more than 500 ppm, but Examples (Samples No. 1, 2, 4, 5) And Comparative Examples (Samples No. 3, 6 to 11) were satisfactory results of 500 ppm or less for all the elements. In addition, in Examples (Samples No. 1 and 2) and Comparative Examples (Samples No. 3, 6 to 11), as shown in Table 1, the content of all elements in the anodized film was 300 ppm or less, which is a very good result. It was.

[Measurement of hardness of anode oxide film]

The specimen piece was embedded in resin in the cross-sectional direction (so that the anode oxide film cross section and the aluminum alloy substrate cross section became the polishing surface), and after polishing, the hardness was measured by the method of JIS Z 2244 (1998) on the anode oxide film cross section. did.

ㆍ measurement result

As shown in Table 1, in Examples (Samples No. 1, 2, 4, 5) and Comparative Examples (Samples No. 3, 6 to 14), the hardness of the anodic oxide film of the second layer was the first. It became harder than the hardness of the anodized film of the layer. This is because the temperature of the processing liquid at the time of forming the anodic oxide film of the second layer is lower than the temperature of the processing liquid at the time of formation of the anodic oxide film of the first layer. The difference in hardness between the second layer of Example (Sample No, 2) and the anodized film of the first layer was 5 in Vickers hardness. This is based on the fact that the temperature of the processing liquid at the time of forming the anodic oxide film of the second layer is 5 ° C, and the temperature of the processing liquid at the time of formation of the anodic oxide film of the first layer is 8 ° C. In addition, the difference of the hardness of the 2nd layer of a comparative example (sample No. 3), and the anodized film of a 1st layer was 4 in Vickers hardness. This is based on the fact that the temperature of the processing liquid at the time of forming the anodic oxide film of the second layer is 5 ° C, and the temperature of the processing liquid at the time of formation of the anodic oxide film of the first layer is 7 ° C. The difference between the hardness of the anodic oxide film of the 2nd layer and 1st layer of Examples (sample No. 1, 4, 5) and comparative examples (sample No. 6-14) other than these was 10 in Vickers hardness. This is based on the fact that the temperature of the processing liquid at the time of forming the anodic oxide film of the second layer is 5 ° C, and the temperature of the processing liquid at the time of formation of the anodic oxide film of the first layer is 10 ° C. Thus, by controlling the temperature of the processing liquid at the time of formation of the anodized film, the hardness of the anodized film can be set arbitrarily. In addition, since the hardness of the anodized film is 365 or more in Vickers hardness, except for Comparative Example (Sample No. 12), as shown in Table 1, plasma resistance except for Comparative Example (Sample No. 12) It is possible to secure.

[Test of durability of anode oxide film]

The durability test consists of two stages: the crack resistance test and the gas corrosion test described below. First, a sample piece was first installed in a test container (atmosphere was in the air), heated to 450 ° C. for 1 hour, and then the sample piece was taken out of the test container and quenched by immersion in 27 ° C. water. (Crack resistance test). After this test, the sample pieces were placed in a 5% Cl ₂ -Ar gas atmosphere (400 ° C.) for 4 hours (this is 1 cycle), and then 1 cycle was further added, and a total of 2 cycles were performed (gas corrosion resistance test). . Then, the sample piece was taken out, the corrosion occurrence area ratio (corrosion area / sample piece area x 100) of the sample piece surface was computed, and it evaluated by the following reference | standard (evaluation result is shown in the said Table 1).

ㆍ durability evaluation criteria

(Double-circle): Corrosion generation area rate 0%, (circle): Corrosion generation area rate more than 0% 3% or less, x: Corrosion generation area rate more than 3%

ㆍ Duration evaluation result

As shown in Table 1 above, Comparative Examples (Samples No. 3, 6 to 11) were failed, but Examples (Samples No. 1, 2, 4, 5) and Comparative Examples (Samples No. 12 to 14) were It was a good result. In addition, the Example (sample No. 1) and the comparative example (sample No. 12-14) were very favorable results as shown in the said Table 1.

As described above, when the measurement results of the content of Fe, Cr, and Cu in the anodized film, the measurement results of the hardness of the anodized film, and the test results of the durability of the anodic oxide film are collectively judged, the overall standards can be satisfied. Only the examples (sample Nos. 1, 2, 4, and 5) are used. Examples (Samples No. 1, 2, 4, 5) satisfying the entire standard combine durability and low pollution even with high hardness.

Claims (2)

Mg: 0.1 to 2.0% (the meaning of "mass%", the same below), Si: 0.1 to 2.0%, Mn: 0.1 to 2.0% as an alloy component, and each content of Fe, Cr, and Cu is 0.03, respectively It is regulated to% or less, and remainder is an anodized aluminum alloy provided with the aluminum alloy which consists of Al and an unavoidable impurity, and the anodizing film formed on the surface of this aluminum alloy, and hardness differs in the thickness direction of the said anodizing film. An anodized aluminum alloy having durability and low pollution, wherein the difference between a portion having a maximum hardness and a portion having a minimum hardness is Vickers hardness of 5 or more. The anodized aluminum alloy according to claim 1, wherein the Vickers hardness of the portion having the minimum hardness is 365 or more.