JP5405800B2 - Corrosion-resistant treatment method for aluminum or aluminum alloy - Google Patents

Description

  The present invention relates to a corrosion resistance treatment method for aluminum or an aluminum alloy.

  Conventionally, as a method of performing corrosion resistance treatment on aluminum or an aluminum alloy, for example, Patent Document 1 proposes a technique in which an oxide film having a thickness of 5 to 20 nm is formed on the surface of aluminum or an aluminum alloy, and then barrier type anodizing treatment is performed. It had been. Patent Document 1 describes that this technique can improve the gas releasing properties of aluminum or an aluminum alloy.

JP 2006-322040 A

  However, in the method described in Patent Document 1, many impurities are still contained in the oxide film formed on the surface of aluminum or aluminum alloy. For example, in the semiconductor manufacturing field, a chamber made of aluminum or an aluminum alloy may be used as a chamber covering a semiconductor manufacturing apparatus. Usually, the surface of the chamber is subjected to a corrosion resistance treatment for forming an oxide film in order to improve the corrosion resistance. However, if the surface of the anodized aluminum or aluminum alloy contains a certain amount or more of specific impurities, the oxide film formed by the anodizing treatment may be defective or rough. As a result, impurities are released during the manufacture of the semiconductor, which may affect the quality of the manufactured semiconductor. For this reason, it is desired that the amount of the specific impurity contained in the surface of the aluminum or aluminum alloy to be anodized be less than a certain amount.

  The present invention has been devised in view of the above-described problems, and an object of the present invention is to provide a corrosion-resistant treatment method that imparts corrosion resistance by forming an oxide film with fewer impurities than conventional on the surface of aluminum or an aluminum alloy.

  As a result of intensive studies in view of the above problems, the present inventors have performed a barrier type anodizing treatment after performing one or both of a chemical polishing treatment and a degreasing treatment on the surface of aluminum or an aluminum alloy in performing a corrosion resistance treatment. As a result, it was found that an oxide film having fewer impurities than the conventional one can be formed on the surface of aluminum or aluminum alloy, and the present invention has been completed.

That is, the gist of the present invention is a method of corrosion-resistant treatment of the surface of aluminum or aluminum alloy, a degreasing step of performing alkaline degreasing treatment of the surface of the aluminum or aluminum alloy, and chemical polishing treatment from the surface of the aluminum or aluminum alloy. , 50 nm or more, as chemical polishing engineering to remove the surface layer portion of 100μm or less, and after a chemical polishing step, sequentially performs as anodized Engineering performing barrier type anodic oxide treatment on the surface of the aluminum or aluminum alloy, and the Immediately before the anodic oxidation step, the present invention resides in a corrosion-resistant treatment method characterized in that the thickness of the oxide film on the surface of the aluminum or aluminum alloy is 0.2 nm or less.

At this time, in the chemical polishing step, the chemical polishing treatment is preferably performed with an acidic solution having a concentration of 60% by mass or more .
Moreover, it is preferable that the processing temperature of the said chemical polishing process is 5 degreeC or more and 70 degrees C or less (Claim 3) .

Furthermore, the aluminum or aluminum alloy semiconductor fabrication chamber, which is preferably formed as a flat panel display manufacturing chamber or solar cell production chamber (claim 4).

  According to the corrosion-resistant treatment method of the present invention, it is possible to impart corrosion resistance by forming an oxide film with fewer impurities than before on the surface of aluminum or an aluminum alloy.

  Hereinafter, the present invention will be described in detail with reference to embodiments, examples, etc., but the present invention is not limited to the following embodiments, examples, etc., and can be arbitrarily set within the scope of the present invention. Can be changed and implemented.

  FIG. 1 is a flowchart schematically showing an outline of a method of corrosion-resistant treatment of the surface of aluminum or an aluminum alloy as one embodiment of the present invention. As shown in FIG. 1, in the corrosion resistance treatment method for the surface of aluminum or aluminum alloy according to this embodiment, a degreasing process, a chemical polishing process, a cleaning process, and an anodizing process are performed.

[1. Aluminum and aluminum alloy]
First, aluminum and aluminum alloy that are subject to corrosion resistance will be described.
In the aluminum alloy, the type of metal constituting the alloy in combination with aluminum is not particularly limited, but preferred examples of the metal include magnesium and zirconium. Among these, magnesium is particularly preferable because it can increase the strength of the aluminum alloy.
In addition, these metals may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  In the aluminum alloy, the aluminum content is usually 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 94% by mass or more. In addition, an upper limit is 100 mass%, and this represents pure aluminum. If the aluminum content is too small, the film quality of the barrier type anodized film may be deteriorated.

  Moreover, in aluminum and aluminum alloy, in addition to the metal which comprises an alloy with aluminum, you may contain another metal component as a crystal regulator. The type thereof is arbitrary as long as it has a sufficient effect on crystal control, and examples thereof include zirconium. These metal components may be used alone or in combination of two or more in any combination and ratio.

  The content of the metal component functioning as a crystal modifier is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, with respect to the total amount of aluminum or aluminum alloy. is there. This is to sufficiently develop the characteristics as a crystal modifier. However, the upper limit is usually 20% by mass or less, preferably 10% by mass or less, more preferably 6% by mass or less, and still more preferably 4.5% by mass or less. This is to maintain good material properties of aluminum or aluminum alloy.

Aluminum or an aluminum alloy is usually formed into a desired shape before performing the corrosion resistance treatment method. Although there is no restriction | limiting in the shape, It is preferable to shape | mold as a chamber for semiconductor manufacture, a chamber for flat panel display (FPD) manufacture, or a chamber for solar cell manufacture. In the present embodiment, an oxide film is formed on the surface of aluminum or an aluminum alloy with few defects and surface roughness and very little impurity emission. For this reason, it is because the corrosion-resistant treatment method of the present embodiment is suitable for use in articles made of aluminum or aluminum alloys that are used in applications where the presence and release of a very small amount of impurities are not preferable as in the semiconductor manufacturing process. At this time, specific shapes, dimensions, and the like may be arbitrarily set according to applications.
It should be noted that the corrosion-resistant treatment method of the present invention can be applied even to a shape suitable for a use other than the semiconductor manufacturing chamber, the flat panel display manufacturing chamber, and the solar cell manufacturing chamber.

  Usually, an oxide film is formed on the surface of aluminum or aluminum alloy. This oxide film is formed unintentionally with air or water, and is generally called a natural oxide film. However, since this natural oxide film is an extremely thin film, a thicker oxide film is usually formed by anodizing treatment and subjected to corrosion resistance treatment. At this time, when the corrosion resistance treatment method of this embodiment is performed, the emission of impurities from the formed oxide film is reduced. In the present embodiment, the following steps are performed.

[2. Degreasing process]
As shown in FIG. 1, normally, in this embodiment, a degreasing process is first performed. A degreasing process is a process of performing the degreasing process of the surface of aluminum or aluminum alloy.
When forming aluminum or an aluminum alloy, a lubricating oil is usually used. This lubricating oil remains on the surface of the aluminum or aluminum alloy. In addition, during transportation inside and outside the factory, the oil component may adhere to the surface of aluminum or an aluminum alloy for some reason. In the degreasing step, organic components such as lubricating oil and oil component adhering to the surface of aluminum or aluminum alloy are removed before an anodic oxidation step described later.

There is no restriction | limiting in the method of a degreasing process, If the said organic component can be removed, it is arbitrary.
For example, it is preferable to perform the degreasing process by an alkaline degreasing process. The alkali degreasing treatment is a method in which an alkaline solution is brought into contact with the surface of aluminum or an aluminum alloy to perform the degreasing treatment, and the treatment is usually performed by immersing aluminum or an aluminum alloy in a liquid of the alkaline solution.

There is no restriction | limiting in the kind of alkaline solution used in an alkaline degreasing process. Examples of the alkaline solution include a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and an ammonium hydroxide aqueous solution. At this time, the concentration of the alkaline solution is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, and usually 50% by mass or less, preferably 30% by mass or less. More preferably, it is 15 mass% or less. If the concentration of the alkaline solution is too low, the degreasing treatment may not be sufficient, and if the concentration is too high, the surface roughness of the aluminum or aluminum alloy may be serious.
In addition, in an alkaline solution, 1 type may be used for a solvent and a solute, respectively, and 2 or more types may be used together by arbitrary combinations and a ratio.

  Further, for example, degreasing treatment may be performed with an organic solvent such as acetone or alcohols. In the degreasing process using an organic solvent, the degreasing process is performed by bringing the organic solvent into contact with the surface of aluminum or an aluminum alloy. Usually, degreasing is performed by immersing aluminum or an aluminum alloy in an organic solvent solution.

  In addition, the degreasing treatment liquid such as the alkaline solution and the organic solvent described above may contain components other than those described above as long as the organic components attached to the surface of the aluminum or aluminum alloy can be removed. 1 type may be contained for such a component and 2 or more types may be contained by arbitrary combinations and a ratio.

  The treatment temperature of the degreasing treatment (that is, the temperature of the degreasing solution) is arbitrary as long as the degreasing treatment can be performed, but is usually 5 ° C. or higher, preferably 10 ° C. or higher, more preferably 15 ° C. or higher, and usually 100 ° C. The temperature is preferably 80 ° C. or lower, more preferably 60 ° C. or lower. If the temperature is too low, the degreasing treatment tends to take time. If the temperature is too high, the liquid composition changes and stable degreasing tends to be difficult.

  The processing time of the degreasing process is arbitrary. For example, when the degreasing treatment is performed by dipping in a degreasing solution, the time during which the aluminum or aluminum alloy is immersed is usually 5 seconds or more, preferably 10 seconds or more, more preferably 30 seconds or more, and usually 3 hours or less, preferably 2 hours or less, more preferably 1 hour or less. If the treatment time is too short, degreasing tends to be insufficient, and if it is too long, the productivity of the treatment may be reduced.

  Further, the degreasing treatment may be performed only once or may be performed twice or more. Furthermore, when performing a degreasing process twice or more, the processing method of each time may be the same, and may differ. For example, the conditions of the degreasing treatment may be changed each time, or the alkaline degreasing treatment and the degreasing treatment with an organic solvent may be performed in combination.

  Usually, in a degreasing process, after removing an organic component, the degreasing process liquid which remained on the surface of aluminum or aluminum alloy is removed. The removal of the degreasing solution is usually performed by washing with water. At this time, it is preferable that the purity of the water used for washing is higher.

  The organic component adhering to the surface of aluminum or aluminum alloy is removed by the degreasing treatment described above. Thereby, it can suppress that an organic component remains on the surface of aluminum or an aluminum alloy in a chemical polishing process, and a polishing nonuniformity generate | occur | produces at the time of chemical polishing. Furthermore, when alkaline degreasing is performed, usually, an oxide film such as a natural oxide film formed on the surfaces of aluminum and aluminum alloy is also removed. Thereby, the above-mentioned polishing unevenness can be prevented more reliably.

[3. Chemical polishing process]
As shown in FIG. 1, normally, after performing a degreasing process, before performing an anodic oxidation process, a chemical polishing process is performed. The chemical polishing step is a step of performing chemical polishing treatment on the surface of aluminum or aluminum alloy.
In the chemical polishing process, the fine irregularities on the surface are dissolved before the depressions to obtain a smooth glossy surface. At this time, if there are impurities on the surface of the aluminum or aluminum alloy, It is removed in the polishing process. That is, since a smooth aluminum or aluminum alloy surface with a specific amount of specific impurities or less can be obtained, an oxide film can be obtained in the subsequent anodic oxidation process with few defects and surface roughness and very little impurity emission.

  There is no restriction | limiting in the method of a chemical polishing process, As long as the surface of aluminum or aluminum alloy can be grind | polished by a chemical reaction, it is arbitrary. Usually, it is preferable to perform a chemical polishing treatment by bringing a chemical polishing solution into contact with the surface of aluminum or an aluminum alloy. The contact is usually performed by immersing aluminum or an aluminum alloy in a chemical polishing liquid.

At this time, it is preferable to use an acidic solution as the chemical polishing liquid and perform the chemical polishing treatment with the acidic solution. There is no restriction | limiting in the kind of acidic solution used in a chemical polishing process.
Examples of the solvent for the acidic solution include water and glycerin.
On the other hand, examples of the solute of the acidic solution include phosphoric acid, sulfuric acid, nitric acid, acetic acid, boric acid, chromic acid, and salts of these acids.
Under the present circumstances, the density | concentration of the solute in an acidic solution is 60 mass% or more normally, Preferably it is 70 mass% or more, More preferably, it is 75 mass% or more. If the concentration of the acidic solution is too low, chemical polishing may not be sufficient.
In addition, in an acidic solution, 1 type may be used for a solvent and a solute, respectively, and 2 or more types may be used together by arbitrary combinations and a ratio.

  The chemical polishing liquid such as the acidic solution described above may contain components other than those described above as long as the surface of aluminum or aluminum alloy can be polished. 1 type may be contained for such a component and 2 or more types may be contained by arbitrary combinations and a ratio.

  The treatment temperature of the chemical polishing treatment (temperature of the chemical polishing solution) is usually 5 ° C. or higher, preferably 50 ° C. or higher, more preferably 55 ° C. or higher, and usually 70 ° C. or lower, preferably 65 ° C. or lower. If the temperature is too low, chemical polishing tends to be difficult to proceed. If the temperature is too high, the reaction cannot be controlled and the surface tends to be rough.

  The treatment time for the chemical polishing treatment is arbitrary. For example, when chemical polishing treatment is performed by immersing in a chemical polishing solution, the time during which aluminum or an aluminum alloy is immersed is usually 10 seconds or longer, preferably 30 seconds or longer, more preferably 60 seconds or longer, Usually, it is 600 seconds or less, preferably 300 seconds or less, more preferably 180 seconds or less. If the treatment time is too short, chemical polishing tends to be insufficient, and if it is too long, the surface tends to become rough.

  Further, the chemical polishing treatment may be performed only once or may be performed twice or more. Furthermore, when the chemical polishing treatment is performed twice or more, the treatment method for each round may be the same or different. For example, the conditions of the chemical polishing treatment may be changed each time, or the chemical polishing liquid may be changed.

  A natural oxide film is usually formed before the chemical polishing step, and this natural oxide film is dissolved and removed together with the underlying aluminum or aluminum alloy surface layer by chemical polishing. Therefore, a thicker oxide film is formed on the surface of the aluminum or aluminum alloy before the chemical polishing step than after the chemical polishing step.

  The thickness of the surface layer portion removed by the chemical polishing treatment is usually 50 nm or more, preferably 500 nm or more, and is usually 100 μm or less, preferably 10 μm or less. If the surface layer portion to be removed is too thin, impurities may remain, and if it is too thick, aluminum or an aluminum alloy is wasted.

  Moreover, the surface shape of aluminum or an aluminum alloy is usually smoothed by the chemical polishing step.

[4. Cleaning process]
Since the degreasing treatment liquid used in the above-described degreasing process and the chemical polishing liquid used in the chemical polishing process cannot be completely removed by drying or the like, usually, cleaning that cleans aluminum or aluminum alloy prior to the anodizing process Perform the process.

  In the cleaning step, the aluminum or the aluminum alloy is cleaned with a cleaning liquid. At this time, usually, water is used as the cleaning liquid, and the chemical polishing liquid is removed by washing with water. However, the water used at this time is preferably high-purity water with a low impurity content. This is because impurities contained in water are prevented from adsorbing on the surface of aluminum or aluminum alloy.

  Even if chemical polishing liquid and dust adhere to the surface of aluminum or aluminum alloy, these are removed by the cleaning process. In the anodic oxidation process, if chemical polishing liquid and dust adhere to the surface of aluminum or aluminum alloy, these may infiltrate into the oxide film formed on the surface of aluminum or aluminum alloy and become impurities. However, the above-described cleaning can prevent such impurities from entering.

[5. Anodizing process]
As shown in FIG. 1, an anodic oxidation process is performed after a degreasing process, a chemical polishing process, and a washing process. The anodizing step is a step of performing barrier type anodizing treatment on the surface of the aluminum or aluminum alloy. By performing the barrier type anodizing step, an oxide film (specifically, a barrier type anodized film) is formed on the surface of aluminum or aluminum alloy. Since the oxide film of aluminum or aluminum alloy is very stable, the aluminum or aluminum alloy becomes passive and the corrosion resistance is improved.

  Usually, an oxide film containing impurities derived from a bare metal is often formed on the surface of aluminum or an aluminum alloy, but in this embodiment, the oxide film is chemically polished in advance by the above-described chemical polishing step, and then the barrier is formed. A new oxide film is formed by performing the mold anodizing treatment. For this reason, an oxide film with a low impurity content is newly formed, and in addition to improving the corrosion resistance, it is possible to achieve a reduction in impurities in the oxide film.

  Here, immediately before the anodic oxidation step, the thickness of the oxide film on the surface of the aluminum or aluminum alloy after the surface layer portion is removed by the chemical polishing treatment is usually 0.2 nm or less, preferably 0.18 nm or less. Preferably, it is 0.15 nm or less, and all the oxide film may be removed by chemical polishing treatment. If the thickness of the oxide film is too thick, a heterogeneous layer may be formed in the anodic oxidation process, and desired characteristics may not be obtained.

  The barrier type anodizing treatment is performed by energizing aluminum or an aluminum alloy as an anode in the electrolyte solution.

As a solvent for the electrolyte solution, water may be used, but a mixed solvent of a non-aqueous solvent and water is preferably used. The water content in the mixed solvent is preferably 5% by weight or more and 50% by weight or less.
Examples of the non-aqueous solvent include a solvent having one or more alcoholic hydroxyl groups and / or one or more phenolic hydroxyl groups; an aprotic organic solvent, and the like. Among these, a solvent having an alcoholic hydroxyl group is preferable from the viewpoint of storage stability.

Examples of the solvent having an alcoholic hydroxyl group include monohydric alcohols such as methanol, ethanol, propanol, isopropanol, 1-butanol, 2-ethyl-1-hexanol, and cyclohexanol; ethylene glycol, propylene glycol, butane-1,4. -Dihydric alcohols such as diol, diethylene glycol, triethylene glycol and tetraethylene glycol; trihydric or higher polyhydric alcohols such as glycerin and pentaerythritol. Among them, those having two or more alcoholic hydroxyl groups in the molecule from the viewpoint of miscibility with water and vapor pressure are preferred, dihydric alcohols and trihydric alcohols are more preferred, and ethylene glycol, propylene glycol, and diethylene glycol are particularly preferred. preferable.
Examples of the solvent having a phenolic hydroxyl group include those having one hydroxyl group, alkylphenols such as unsubstituted phenol, o-cresols, m-cresols, p-cresols, and xylenols. Resorcinols are exemplified as those having two hydroxyl groups, and pyrogallols are exemplified as those having three hydroxyl groups.
These solvents having an alcoholic hydroxyl group and / or a phenolic hydroxyl group may further have other functional groups in the molecule as long as the effects of the present invention are not significantly impaired. For example, a solvent having an alkoxy group together with an alcoholic hydroxyl group such as methyl cellosolve and cellosolve can also be used.

On the other hand, as the aprotic organic solvent, either a polar solvent or a nonpolar solvent may be used.
Examples of the polar solvent include cyclic carboxylic acid esters such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; chain carboxylic acid esters such as methyl acetate, ethyl acetate, and methyl propionate; ethylene carbonate, propylene Cyclic carbonates such as carbonate, butylene carbonate, vinylene carbonate; chain carbonates such as dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate; N-methylformamide, N-ethylformamide, N, N-dimethylformamide, N, Amides such as N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone; acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-metho Nitriles such as Cipro propionitrile; trimethyl phosphate, and the like phosphoric ester such as triethyl phosphate.
Moreover, as a nonpolar solvent, hexane, toluene, silicon oil etc. are mentioned, for example.

Among these solvents, ethylene glycol, propylene glycol, and diethylene glycol are particularly preferable.
In addition, 1 type may be used for a solvent and it may use 2 or more types together by arbitrary combinations and a ratio.

  Examples of the solute of the electrolyte solution include carboxylic acid and carboxylate; boric acid and borate; phosphoric acid and phosphate, among which carboxylic acid and carboxylate are preferable. The oxide film formed by the barrier type anodic oxidation treatment tends to be incorporated into impurities with a very small amount of solute component, but impurities can be reduced by using carboxylic acid or carboxylate as the solute.

  Among the carboxylic acids, aliphatic carboxylic acids are preferable in view of high solubility and good dissolution stability, and aliphatic dicarboxylic acids having 3 to 10 carbon atoms are particularly preferable. Specific examples include malonic acid, maleic acid, fumaric acid, succinic acid, tartaric acid, itaconic acid, glutaric acid, dimethylmalonic acid, citraconic acid, citric acid, adipic acid, heptanoic acid, pimelic acid, suberic acid, and azelain. Examples thereof include acid, sebacic acid, etc. Among them, tartaric acid, citric acid, and adipic acid are particularly preferable for reasons such as solution stability, safety, and good buffer action.

Moreover, as a salt of these acids, what is necessary is just a salt of these acids and a suitable cation. Although there is no restriction | limiting in particular as a cation, For example, an ammonium ion, a primary, a secondary, a tertiary, or a quaternary alkyl ammonium ion, an alkali metal ion, a phosphonium ion, a sulfonium ion etc. can be used. Of these, ammonium ion, primary, secondary, tertiary or quaternary alkylammonium ion is preferred in that it is less affected by residual metal ions on the surface. The alkyl group of the alkyl ammonium ion may be appropriately selected in consideration of solubility, but is usually an alkyl group having 1 to 4 carbon atoms.
In addition, 1 type may be used for a solute and it may use 2 or more types together by arbitrary combinations and a ratio.

  The concentration of the solute in the electrolyte solution is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more. This is because the oxide film is sufficiently formed by increasing the electrical conductivity. Moreover, an upper limit is 30 mass% or less normally, Preferably it is 15 mass% or less, More preferably, it is 10 mass% or less. This is to keep the performance of the oxide film high and to reduce the cost.

The pH of the electrolyte solution is usually 4 or more, preferably 5 or more, more preferably 6 or more, and usually 10 or less, preferably 9 or less, more preferably 8 or less. This is because it is preferable to make the pH close to neutral in order to prevent the oxide film formed by the barrier type anodizing treatment from being dissolved in the electrolyte solution. In addition, by keeping the pH within this range, it is possible to repair defects caused by the non-uniformity of aluminum or aluminum alloy and form a dense and smooth oxide film.
From the viewpoint of maintaining the pH of the electrolyte solution in such a neutral range, those having a buffering action as a solute are preferable. Specific examples include the solutes described above.

  Further, the electrolyte solution may contain other components as long as the effects of the present invention are not significantly impaired. In addition, 1 type may be sufficient as another component, and 2 or more types may be contained by arbitrary combinations and ratios.

  In the barrier type anodizing treatment, there is no limitation on the cathode which is a pair of aluminum or aluminum alloy which is an anode. Therefore, a cathode made of any conductive material that is insoluble in the electrolyte solution can be used. For example, platinum, aluminum or an alloy thereof, carbon, titanium or an alloy thereof can be used as the cathode.

  The energization method performed in the barrier type anodizing treatment is arbitrary as long as the effects of the present invention are not significantly impaired. Therefore, as the current waveform, for example, direct current; pulsed current in which the applied voltage is periodically interrupted; alternating current; modulation current such as AC / DC superimposition, incomplete rectification, and triangular wave can be used. Further, a PR method in which the polarity is inverted can also be used. Of these, a direct current is preferably used.

In addition, it is usually preferable to energize at a constant current and a constant voltage. That is, it is preferable to conduct the barrier type anodizing treatment by energizing with a constant current up to a predetermined voltage, and holding the voltage for a certain time after reaching the target voltage.
Instead of the DC power supply until reaching the target voltage, an AC with a constant peak current value may be used, and when the target voltage is reached, a method of switching to the DC voltage and holding it for a certain time may be used.

The current density during energization is usually 0.001 mA / cm ² or more, preferably 0.01 mA / cm ² or more, and usually 100 mA / cm ² or less, preferably 10 mA / cm ² or less. This is to obtain an oxide film with good surface flatness.

  The treatment temperature of the barrier type anodizing treatment (that is, the temperature of the electrolyte solution) is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually −20 ° C. or higher, preferably 5 ° C. or higher, more preferably 10 ° C. or higher. is there. It takes into account the production efficiency and energy efficiency during processing. Moreover, an upper limit is 150 degrees C or less normally, Preferably it is 100 degrees C or less, More preferably, it is 80 degrees C or less. This is because a uniform barrier type anodizing treatment is performed while maintaining the composition of the electrolyte solution.

  The treatment time of the barrier type anodizing treatment (that is, the time for energization) may be appropriately set according to conditions such as the thickness of the oxide film to be formed, but is usually 1 minute or more, preferably 5 minutes or more. It is preferably 15 minutes or longer, and usually 24 hours or shorter, preferably 12 hours or shorter, more preferably 6 hours or shorter. If the treatment time is too short, it tends to be difficult to form a good quality oxide film, and if it is too long, the productivity may deteriorate.

  The barrier type anodizing treatment may be performed only once or may be performed twice or more. Further, when the barrier type anodizing treatment is performed twice or more, the treatment method of each time may be the same or different. For example, the conditions of the barrier type anodizing treatment may be changed each time, or the electrolyte solution may be changed.

[5. Other processes]
Although the corrosion-resistant treatment method of this embodiment is as described above, other steps may be performed in addition to the above-described degreasing step, chemical polishing step, cleaning step, and anodizing step. Further, the other steps may be performed before, during or after the above-described steps as long as the effects of the present invention are not significantly impaired.

An example of another process is an annealing process. In the annealing process, heat treatment of aluminum or aluminum alloy is performed for the purpose of removing moisture in the oxide film, and is usually performed after the anodic oxidation process.
The temperature of the heat treatment is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and usually 600 ° C. or lower, preferably 550 ° C. or lower, more preferably 500 ° C. or lower. In the heat treatment, the set temperature of the heating furnace is usually regarded as the heat treatment temperature.
The time for the heat treatment is usually 1 minute or longer, preferably 5 minutes or longer, more preferably 15 minutes or longer, and usually 180 minutes or shorter, preferably 120 minutes or shorter, more preferably 60 minutes or shorter.
Furthermore, nitrogen, oxygen, or a mixed gas thereof can be appropriately used as the atmosphere for the heat treatment. Among them, an atmosphere having an oxygen concentration of 20% by volume or more is preferable.

[6. Composition of the resulting oxide film]
By the above-described corrosion resistance treatment method, an oxide film is formed on the surface of aluminum or aluminum alloy, thereby improving the corrosion resistance of aluminum or aluminum alloy. Further, according to the corrosion resistance treatment method of the present embodiment, the oxide film has few impurities. Here, examples of the impurities include B and P.

  In addition, the low release of impurities can be evaluated by, for example, a temperature programmed desorption measurement device. That is, as a result of measuring with a temperature-programmed desorption measuring device, if there are few observed desorption gases, it can be evaluated that there are few impurities.

[7. advantage]
As described above, according to the corrosion resistance treatment method of the present embodiment, an oxide film having fewer impurities than the conventional one can be formed on the surface of aluminum or aluminum alloy. This oxide film functions as a corrosion-resistant film, and can impart corrosion resistance to aluminum or an aluminum alloy. The oxide film can also function as a protective film and an impurity blocking film.
Further, for example, in the conventional technique described in Patent Document 1, it is necessary to perform a treatment at a high temperature of 80 ° C. or higher in order to grow an oxide film prior to the anodic oxidation. Since the treatment can be performed at a low temperature, the operation is simple and the cost is advantageous.

[8. Application]
The corrosion resistance treatment method of the present embodiment can be widely used as a corrosion resistance treatment method for aluminum or aluminum alloy, but is particularly preferably used as a corrosion resistance treatment method for semiconductor manufacturing apparatuses, flat panel display manufacturing apparatuses, and solar cell manufacturing apparatuses. In particular, it is preferably used as a corrosion resistance method for aluminum or aluminum semiconductor manufacturing chambers. Among them, chemical vapor deposition (CVD), physical vapor deposition (PVD), vacuum deposition, sputter deposition, and microwave excitation. Vacuum thin film forming apparatus used for plasma CVD, etc .; dry etching apparatus used for plasma etching, reactive ion etching (RIE), microwave-excited plasma etching, etc .; It is suitable for use as.

[9. Others]
The present invention is not limited to the above-described embodiments and exemplifications, and can be implemented with arbitrary modifications without departing from the gist of the present invention.
For example, both the degreasing step and the chemical polishing step may be performed as described above, but only one of them may be performed. When both are performed, the chemical polishing step is usually performed after the degreasing step first as in the above embodiment, but conversely, the degreasing step may be performed after the chemical polishing step is performed first. .

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified without departing from the gist of the present invention.

[Example 1]
A sample using A5052 as a substrate as an aluminum alloy was naturally dried after removing organic substances on the surface with acetone.
Next, the sample was immersed for 1 minute in a solution in which a 15 wt% aqueous potassium hydroxide solution was heated to 50 ° C., and the surface was completely degreased (degreasing step).
The sample taken out from the potassium hydroxide aqueous solution was washed with pure water to remove the chemical solution on the surface.

Subsequently, an acidic solution in which 85% by weight phosphoric acid, 97% by weight sulfuric acid and 70% by weight nitric acid were mixed at a volume ratio of 70: 25: 5 was heated to 65 ° C., and the sample was shaken for 3 minutes. While being immersed, chemical polishing was performed (chemical polishing step).
After chemical polishing, the sample taken out of the solution was washed with pure water at room temperature (cleaning step), and barrier type anodizing treatment was performed to form an anodized film on the sample surface (anodic oxidation step).
In the barrier type anodizing treatment, a constant current is applied up to 200 V at a current density of 1 mA / cm ² at 23 ° C. in a mixture of ethylene glycol / water / ammonium adipate at a weight ratio of 79: 20: 1. Then, a direct current was applied for 30 minutes at a constant voltage of 200V.

[Example 2]
Using the same sample as in Example 1, degreasing with acetone, drying, and complete degreasing with a potassium hydroxide solution were performed under the same conditions (degreasing step).
Next, the sample was immersed in 5 wt% nitric acid at 25 ° C. for 5 minutes to remove the alkali component adhering to the surface by acid neutralization.
After immersion, the sample was taken out and washed with pure water at room temperature (cleaning step), and then the barrier type anodizing treatment was performed in the same manner as in Example 1 to form an anodized film on the sample surface (anodic oxidation). Process).

[Comparative Example 1]
Using the same sample as in Example 1, degreasing with acetone and drying were performed under the same conditions.
Next, an acidic solution in which 85% phosphoric acid and 70% nitric acid were mixed at a volume ratio of 80: 5 was heated to 85 ° C., and the sample was immersed in this for 2 minutes.
After soaking, it was washed with pure water at 50 ° C., and then washed with pure water at room temperature.
Subsequently, the sample was heat-treated at 300 ° C. for 1 hour in an electric furnace in an air atmosphere.
After 1 hour, the electric furnace was returned to room temperature, and then the sample was taken out from the electric furnace and subjected to barrier type anodizing treatment in the same manner as in Example 1 to form an anodized film on the sample surface.

[Comparative Example 2]
Using the same sample as in Example 1, degreasing with acetone and drying were performed under the same conditions.
Subsequently, barrier type anodizing treatment was performed in the same manner as in Example 1 to form an anodized film on the sample surface.

[Evaluation]
About the sample obtained by each Example and the comparative example, the thermal desorption test was done with the thermal desorption measuring apparatus (model number AGS-7000; Anerva). The temperature was raised up to 300 ° C.
Moreover, about the sample, the film thickness of the oxide film formed on the sample surface just before the barrier type anodic oxidation treatment was measured. The film thickness was measured by the voltage jump method, with the film thickness of Example 2 set to 0 and the potential difference from the counter electrode being corrected.
These results are shown in Table 1 below.

  The present invention can be used in any field related to aluminum or an aluminum alloy, but is particularly suitable for use in a semiconductor manufacturing facility.

It is a flowchart which shows typically the outline | summary of the corrosion-resistant processing method of the surface of the aluminum or aluminum alloy as one Embodiment of this invention.

Claims (4)

A method of corrosion resistance treatment of the surface of aluminum or aluminum alloy,
A degreasing step for performing an alkaline degreasing treatment on the surface of the aluminum or aluminum alloy;
The chemical polishing treatment from the surface of the aluminum or aluminum alloy, 50 nm or more, as chemical polishing engineering to remove the surface layer portion of 100μm or less, and after a chemical polishing step, the barrier type anodic oxide treatment on the surface of the aluminum or aluminum alloy sequentially performed as anodic oxidation of Engineering to carry out,
And just before this anodizing process, the film thickness of the oxide film on the surface of the aluminum or aluminum alloy is 0.2 nm or less. The corrosion-resistant treatment method according to claim 1, wherein in the chemical polishing step, the chemical polishing treatment is performed with an acidic solution having a concentration of 60% by mass or more . The corrosion resistance treatment method according to claim 1 or 2, wherein a treatment temperature of the chemical polishing treatment is 5 ° C or higher and 70 ° C or lower . The said aluminum or aluminum alloy is shape | molded as a semiconductor manufacturing chamber, a flat panel display manufacturing chamber, or a solar cell manufacturing chamber, The corrosion-resistant processing method as described in any one of Claims 1-3 characterized by the above-mentioned.

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