JP5416436B2 - Aluminum alloy member excellent in crack resistance and corrosion resistance, method for confirming crack resistance and corrosion resistance of porous anodic oxide film, and conditions for forming porous anodic oxide film excellent in crack resistance and corrosion resistance Setting method - Google Patents

Description

  The present invention is an aluminum alloy member suitably used as a material for a vacuum chamber of a semiconductor or liquid crystal manufacturing facility such as a dry etching apparatus, a CVD apparatus, an ion implantation apparatus, or a sputtering apparatus, or a component provided in the vacuum chamber. A method for confirming the crack resistance and corrosion resistance of the porous anodic oxide film formed on the surface of the aluminum alloy member, and the conditions for forming the porous anodic oxide film having excellent crack resistance and corrosion resistance. It relates to the setting method.

  Using an aluminum alloy as a base material, an anodic oxidation film such as a porous anodic oxide film is formed on the surface of the aluminum alloy base to give corrosion resistance (high temperature gas corrosion resistance), wear resistance, etc. to the aluminum alloy base material. Processing has been widely adopted.

  For example, various parts such as a vacuum chamber used in a plasma processing apparatus of a semiconductor manufacturing facility and electrodes provided in the vacuum chamber are usually formed using an aluminum alloy. However, if the aluminum alloy is used as it is, the corrosion resistance and wear resistance cannot be maintained. Therefore, the surface of the substrate formed of the aluminum alloy is subjected to anodizing treatment to form a porous anode. By forming an anodic oxide film such as an oxide film, corrosion resistance and wear resistance were maintained.

  The reason for forming the anodic oxide film on the surface of the aluminum alloy substrate is that, in the vacuum chamber, the object to be processed such as a silicon wafer is heated to a high temperature from room temperature to 200 ° C. or higher in the pre-processing step or manufacturing step of semiconductor manufacturing. Since predetermined processing is performed with various types of corrosive gas and plasma in the environment, various parts such as the inner surface of the vacuum chamber and electrodes provided in the vacuum chamber are also exposed to the above atmosphere. This is because the solid aluminum alloy cannot maintain the corrosion resistance and wear resistance.

  In recent years, various proposals regarding such aluminum alloy members having an anodic oxide film formed on the surface have been made. From the viewpoint of reducing contamination of the workpiece, that is, reducing Fe, Cr, and Cu, Mg and Si are added to high-purity aluminum as a base material to be anodized to contain impurities. The aluminum alloy base material which limited the quantity as much as possible is proposed as patent documents 1-7. In these aluminum alloy members described in Patent Documents 1 to 7, an effect can be expected for reducing the contamination of the object to be processed, but sufficient durability cannot always be obtained.

  On the other hand, as a base material capable of forming an anodized film with excellent durability on the surface, aluminum alloy with addition of Mn, Cu and Fe in addition to Mg and Si in high purity aluminum Patent Documents 8 and 9 propose that the base material is an aluminum alloy base material that can be expected to be effective in reducing the contamination of the workpiece and can form a film having excellent durability.

  However, since the aluminum alloy members described in Patent Documents 8 and 9 contain Cu and Fe as contamination sources, a sufficient effect cannot be expected for reducing the contamination of the object to be processed. There are problems such as insufficient film durability under the use gas environment, and slow growth rate of the anodic oxide film and poor productivity.

  The present applicant has proposed, as Patent Document 10, an aluminum alloy for anodizing treatment that solves these problems. The aluminum alloy for anodizing treatment described in Patent Document 10 has Mg: 0.1 to 2.0 mass%, Si: 0.1 to 2.0 mass%, and Mn: 0.1 to 2. mass as alloy components. The aluminum alloy contains 0% by mass, the contents of Fe, Cr, and Cu are each regulated to 0.03% by mass or less, and the balance is Al and inevitable impurities.

  However, if the alloy components (Mg, Si, Mn) of the aluminum alloy base material are set to the above-described component ranges, the crack resistance and corrosion resistance of the anodized film formed on the surface are not necessarily good. It was not possible.

  In addition, means for easily confirming that the anodized film formed on the surface of the aluminum alloy substrate has good crack resistance and corrosion resistance, an anodized film on the surface of the substrate made of aluminum alloy At present, there is no excellent prior art relating to means for easily setting the formation conditions.

JP-A-10-88271 JP 2004-99972 A Japanese Patent Laid-Open No. 2002-241992 JP 2002-256488 A JP 2003-119539 A JP 2003-119540 A JP 2003-171727 A Japanese Patent Laid-Open No. 11-43734 Japanese Patent Laid-Open No. 2001-220737 JP 2008-45161

  The present invention has been made as a solution to the above-described conventional problems, and provides an aluminum alloy member excellent in crack resistance and corrosion resistance of a porous anodic oxide film formed on the surface of a base material made of an aluminum alloy. This is a problem. In addition, the present invention provides a method for confirming crack resistance and corrosion resistance of a porous anodic oxide film that can easily confirm that the porous anodic oxide film has good crack resistance and corrosion resistance. It is to be an issue. Furthermore, the present invention provides a method for setting conditions for forming a porous anodic oxide film excellent in crack resistance and corrosion resistance, which can easily form a porous anodic oxide film excellent in crack resistance and corrosion resistance. Is an issue.

  Also, the back surface of the object to be processed is Fe, Cr, Cu, etc. from the lower electrode, susceptor, electrostatic chuck or the like on which the object to be processed such as a silicon wafer in a semiconductor manufacturing apparatus or a glass substrate in a CVD apparatus is placed. It is also a secondary object to provide an aluminum alloy member that can be reduced by contamination.

  Invention of Claim 1 contains Mg: 0.4-1.5 mass%, Si: 0.4-1.5 mass%, Mn: 0.4-1.5 mass%, Fe, Cr , Aluminum in which a porous anodic oxide film having a film thickness of 30 μm or more is formed on the surface of a base material made of an aluminum alloy in which the Cu content is regulated to 0.03% by mass or less and the balance is Al and inevitable impurities. An alloy member, wherein the relationship between the porosity and the true density of the porous anodic oxide film satisfies the condition “the porosity of the film ≧ 61-7 × the true density of the film”. And an aluminum alloy member having excellent corrosion resistance.

  The invention according to claim 2 is an aluminum alloy member excellent in crack resistance and corrosion resistance according to claim 1, wherein the barrier thickness between pores of the porous anodic oxide film is 25 nm or less. is there.

  Invention of Claim 3 contains Mg: 0.4-1.5 mass%, Si: 0.4-1.5 mass%, Mn: 0.4-1.5 mass%, Fe, Cr A porous anodic oxide film having a film thickness of 30 μm or more was formed on the surface of a base material made of an aluminum alloy in which the Cu content was regulated to 0.03% by mass or less and the balance was Al and inevitable impurities. A method for confirming crack resistance and corrosion resistance of an aluminum alloy member at a use temperature T ° C. of 300 ° C. or more of the porous anodic oxide film, wherein the porosity and the true density of the porous anodic oxide film are related to each other. Satisfying the condition of “porosity of the film ≧ (201−0.35 × T) − (71−0.16T) × true density of the film”, the crack resistance of the porous anodic oxide film and Confirm that the corrosion resistance is good It is crack resistance and corrosion resistance of the confirmation method of the porous type anodic oxide film according to claim.

  Invention of Claim 4 contains Mg: 0.4-1.5 mass%, Si: 0.4-1.5 mass%, Mn: 0.4-1.5 mass%, Fe, Cr A porous anodic oxide film having a film thickness of 30 μm or more is formed on the surface of a base material made of an aluminum alloy whose Cu content is regulated to 0.03% by mass or less and the balance is Al and inevitable impurities. For forming a porous anodic oxide film excellent in crack resistance and corrosion resistance at a use temperature T ° C. at 300 ° C. or higher, wherein the porosity of the porous anodic oxide film is set. And the true density satisfy the condition that “the porosity of the film ≧ (201−0.35 × T) − (71−0.16T) × the true density of the film”. The anti-cracking feature is characterized by setting the formation conditions of It is an excellent forming condition setting method of the porous type anodic oxide film on the sex and corrosion resistance.

  According to the aluminum alloy member of claim 1 of the present invention, the porous anodic oxide film formed on the surface of the base material made of an aluminum alloy can be excellent in crack resistance and corrosion resistance.

  According to the aluminum alloy member according to claim 2 of the present invention, from the lower electrode, the susceptor, the electrostatic chuck, or the like on which an object to be processed such as a silicon wafer in a semiconductor manufacturing apparatus or a glass substrate in a CVD apparatus is placed. Contamination of the back surface of the workpiece with Fe, Cr, Cu, or the like can be reduced by adjusting the thickness of the barrier between pores in the porous anodic oxide film.

  According to the method for confirming crack resistance and corrosion resistance of a porous anodic oxide film according to claim 3 of the present invention, from the relationship between the porosity and the true density of the porous anodic oxide film, the resistance of the porous anodic oxide film is confirmed. It can be easily confirmed that the cracking property and the corrosion resistance are good.

  According to the method for setting conditions for forming a porous anodic oxide film excellent in crack resistance and corrosion resistance according to claim 4 of the present invention, when the porous anodic oxide film is formed on the surface of a substrate made of an aluminum alloy, The relationship between the porosity and the true density of the porous anodic oxide film satisfies the condition “the porosity of the film ≧ (201−0.35 × T) − (71−0.16T) × the true density of the film”. Thus, by setting various conditions for forming the porous anodic oxide film, it is possible to easily form a porous anodic oxide film having excellent crack resistance and corrosion resistance. It is also possible to easily determine whether or not the formation conditions can be set.

It is a graph which shows the relationship between the porosity of the film | membrane obtained by the evaluation test of the Example, and the number of corrosion generation cycles. It is a graph which shows the relationship between the porosity of the membrane | film | coat obtained by the evaluation test at the time of 400 degreeC heating of the Example, 350 degreeC heating, and 300 degreeC heating, and a true density.

  The present inventors have further improved the aluminum alloy member in which an anodized film is formed on the surface of a base material made of a conventional aluminum alloy because it is not always sufficient from the viewpoint of crack resistance and corrosion resistance. In order to find an aluminum alloy member having crack resistance and corrosion resistance, intensive studies were conducted.

  As a result, a porous anodic oxide film having a film thickness of 30 μm or more, which is excellent from the viewpoint of plasma resistance, is selected as the anodic oxide film formed on the surface of the base material made of an aluminum alloy. By making the relationship between the porosity and true density of the porous anodized film satisfy the condition of “porosity of the film ≧ 61-7 × true density of the film”, it is excellent in crack resistance and corrosion resistance. It was confirmed that an aluminum alloy member can be obtained. In the present specification, as indicated by the inequality, the porous anodic oxide film may be simply described as a film.

  First, the present inventors can obtain only an anodized film having a film thickness of about 1 μm by the barrier type anodizing treatment, and cannot make an aluminum alloy member excellent in crack resistance and corrosion resistance. An aluminum alloy member in which a porous anodic oxide film capable of forming a thick film was formed on the surface of a base material made of an aluminum alloy was to be studied.

  Cracks generated in a porous anodic oxide film are generated under the condition of “force applied to the film> power that the film can withstand”. The force applied to the porous anodic oxide film is caused by the difference in linear expansion between the aluminum alloy substrate and the porous anodic oxide film due to heating, and the force applied to the porous anodic oxide film is large in the porosity of the porous anodic oxide film. It becomes smaller. On the other hand, the force that the film withstands increases as the true density of the porous anodic oxide film increases. Therefore, crack resistance and corrosion resistance can be improved by forming a porous anodic oxide film having a high porosity and true density on the surface of the aluminum alloy substrate.

  As a result of further experimental investigations from the above viewpoint, a porous anodic oxide film having a film thickness of 30 μm or more, which is excellent in terms of plasma resistance, was selected, and after selecting this, the porous anodic oxide film was selected. By making the relationship between the porosity and the true density satisfy the condition of “porosity of the film ≧ 61−7 × true density of the film”, an aluminum alloy member having the porous anodic oxide film formed on the surface It was confirmed that the aluminum alloy member was excellent in crack resistance and corrosion resistance.

  Next, a method for calculating the porosity and true density of the porous anodic oxide film will be described. The porosity of the porous anodized film is obtained by determining the volume of the void by SEM (scanning electron microscope) observation or TEM (transmission electron microscope) observation of the film surface or cross section, and as a percentage (%) as a ratio to the apparent film volume. calculate. On the other hand, the true density of the porous anodic oxide film can be calculated from the apparent film density and the porosity, and is obtained from the formula “true density = appearance density / ((100−porosity) / 100)”. Can do.

The coating apparent density is determined by the formula “weight of anodized aluminum alloy = aluminum alloy volume × aluminum alloy density + film apparent volume × film apparent density”, and the area of the aluminum alloy measured. And “aluminum alloy volume” calculated from the plate thickness, “aluminum alloy density = aluminum alloy weight / aluminum alloy volume” separately obtained, and “appearance volume” calculated from the area and film thickness of the porous anodized film Can be obtained.

  In addition, the present inventors have further conducted intensive studies in order to give such an effect that the aluminum alloy member excellent in crack resistance and corrosion resistance is further excellent in low contamination. As a result, by setting the barrier thickness between the pores of the porous anodic oxide film to 25 nm or less, a lower electrode or a susceptor on which an object to be processed such as a silicon wafer in a semiconductor manufacturing apparatus or a glass substrate in a CVD apparatus is placed. It has also been found that contamination of the back surface of the object to be processed by Fe, Cr, Cu or the like from an electrostatic chuck or the like can be reduced.

In addition, the barrier thickness between pores defined in the present invention is the average value of the barrier thickness between pores existing in 1 μm ² when the surface of the anodized film is observed with a scanning electron microscope (SEM). Indicates. Specifically, when observing the surface of the anodized film with an SEM (scanning electron microscope), the shortest distance between the adjacent pores (the minimum thickness of the solid portion) is measured for 10 or more adjacent pores. When the pores were connected to each other, the barrier thickness between the pores was set to 0, and the measured average value was obtained to obtain the barrier thickness between the pores. In the present invention, the barrier thickness between the pores is required to be 25 nm or less.

  In the present invention, it is required to form a porous anodic oxide film having a barrier thickness between pores of 25 nm or less, but the lower limit of the barrier thickness between pores is not particularly defined. However, it is practically impossible to control the barrier thickness between pores to be less than 5 nm by controlling the electrolysis voltage and processing temperature described later, and it is preferable to set the lower limit to 5 nm.

  Hereinafter, when a porous anodic oxide film having a film thickness of 30 μm or more is formed on the surface of a base material made of an aluminum alloy, the relationship between the porosity and the true density of the porous anodic oxide film is “the porosity of the film”. The conditions for forming the porous anodic oxide film, such as the manufacturing conditions, for obtaining a porous anodic oxide film satisfying the condition “≧ 61−7 × true density of the film” will be described.

  In addition, conditions for forming a porous anodic oxide film with a barrier thickness between pores of 25 nm or less will be described.

As described above, the porosity of the porous anodic oxide film is preferably large, but the porosity of the film can be increased by increasing the diameter of the pores formed in the film or by increasing the number density of the pores. Can be bigger. On the other hand, the true density of the porous anodic oxide film is preferably large as described above, but it is considered that the true density of the film is difficult to exceed the alumina ceramic density of 4.0 g / cm ³ . It can be considered that the true density of the film is at most 3.6 g / cm ³ . The barrier thickness between pores is also related to the number density of pores and the pore diameter.

  Among the manufacturing conditions for forming a porous anodic oxide film on the surface of a substrate made of an aluminum alloy, the manufacturing conditions that affect the pore diameter, the pore number density, and the true density of the porous anodic oxide film are as follows: The “electrolytic voltage at the time”, “treatment temperature of the anodizing treatment”, and “composition of the anodizing treatment solution”, and “composition of the aluminum alloy substrate” also affect the formation conditions of the porous anodized film. The above four conditions are conditions for forming the porous anodic oxide film of the present invention.

  The electrolytic voltage during the anodizing treatment affects the pore diameter, the number density of the pores, and the true density, respectively. When this electrolysis voltage increases, the pore diameter and true density of the coating increase, but the pore number density decreases conversely. That is, when the electrolysis voltage is low, the pore diameter and true density of the coating are reduced, and conversely, when the electrolysis voltage is high, the pore number density is reduced. Further, the barrier thickness between the pores becomes thinner as the electrolytic voltage is reduced as a result of the balance between the number density of pores and the pore diameter.

  Considering this, although affected by the treatment temperature, the composition of the anodizing treatment solution, and the composition of the aluminum alloy base material, the relationship between the porosity and the true density is “the porosity of the coating ≧ 61−7 × the coating. The optimum voltage range for satisfying the condition of “true density of” is considered to be within a range of approximately 20 to 60V. Further, in order to make the barrier thickness between the pores 25 nm or less, the voltage needs to be 35 V or less. However, if the voltage is too small, the film forming speed becomes slow. Is considered to be in the range of approximately 20-35V.

  The treatment temperature of the anodizing treatment largely affects the pore diameter of the film. Since the pore diameter of the film increases as the treatment temperature increases, it is considered that the treatment is preferably performed at a temperature as high as possible in order to increase the porosity of the film and to reduce the barrier thickness between the pores. As a result of repeated experiments, it was confirmed that a desired porosity and barrier thickness between pores could not be obtained unless the treatment was performed at least at 30 ° C. or higher.

  However, if the treatment temperature exceeds 40 ° C., the amount of evaporation of the anodizing solution increases, making it difficult to manage production. In addition, the specific upper limit temperature cannot be specified here because it is affected by the electrolytic voltage during anodizing, the composition of the anodizing solution, and the composition of the aluminum alloy base material. The chemical dissolution of the inner film becomes large, and a film of 30 μm or more cannot be formed.

  From the above, although the electrolytic voltage during anodizing treatment, the composition of the anodizing treatment solution, and the composition of the aluminum alloy base material are also related, the treatment temperature of the anodizing treatment generally needs to be in the range of 30 to 40 ° C. There is.

  Oxidic acid, sulfuric acid, phosphoric acid, and chromic acid can be cited as anodizing liquids for forming a porous anodic oxide film, but chromium (Cr) remains in the film from the viewpoint of contamination. The chromic acid that becomes cannot be used. Further, when sulfuric acid is used, chemical dissolution of the film becomes too large, and it becomes difficult to form a film having a thickness of 30 μm or more in the above-described processing temperature range (30 to 40 ° C.). If it is to be formed forcibly, it must be formed at a low electrolysis voltage, and the desired true density cannot be obtained. In addition, when phosphoric acid is used, phosphoric acid is not an appropriate anodizing solution because the growth rate of the film is small even if the treatment temperature is high.

  Therefore, oxalic acid is optimal as an anodizing solution for forming a porous anodic oxide film. The concentration of oxalic acid as the anodizing solution may be generally 20 to 50 g / L, and there is no problem even if an additive such as sulfuric acid is added as long as the problem described in the previous stage does not occur.

  As described above, the composition of the aluminum alloy base material also affects the pore diameter, the pore number density, and the true density of the porous anodized film to be formed, but from the viewpoint of contamination, it contains Fe, Cr, and Cu. In the aluminum alloy base material whose amount is regulated to 0.03% by mass or less, as additive elements, Mg: 0.4 to 1.5% by mass, Si: 0.4 to 1.5% by mass, Porous type in which the relationship between the porosity of the film and the true density satisfies the condition “the porosity of the film ≧ 61−7 × the true density of the film” by containing Mn: 0.4 to 1.5% by mass. An anodized film can be formed on the surface of the aluminum alloy substrate.

  In addition, in pure aluminum (4N) whose Fe, Cr, and Cu contents are 0.03% by mass or less, any one of Mg, Si, and Mn deviates from the range of 0.4 to 1.5% by mass. When an alloy is used as a base material, a porous anodic oxide film satisfying the condition that the porosity of the film and the true density satisfy the condition “the porosity of the film ≧ 61-7 × the true density of the film” is the surface of the base material. Can not be formed.

  As described above, an aluminum alloy member having a porous anodic oxide film having a film thickness of 30 μm or more, wherein the relationship between the porosity and the true density of the porous anodic oxide film is expressed by “the porosity of the film ≧ By satisfying the condition of “61-7 × true density of coating”, an aluminum alloy member excellent in crack resistance and corrosion resistance can be obtained. Conversely, this “porosity of coating ≧ 61-7” By confirming that the condition “x true density of coating” is satisfied, it can be confirmed that the crack resistance and corrosion resistance of the porous anodic oxide coating are good. A detailed confirmation method will be described in the next embodiment.

  Further, the formation conditions of the porous anodic oxide film so that the relationship between the porosity and the true density of the porous anodic oxide film satisfies the condition of “porosity of the film ≧ 61-7 × true density of the film”, That is, by appropriately setting the four conditions of “electrolytic voltage during anodizing treatment”, “treatment temperature of anodizing treatment”, “composition of anodizing treatment liquid”, and “composition of aluminum alloy substrate”, A porous anodic oxide film excellent in cracking and corrosion resistance can be formed on the surface of an aluminum alloy substrate. A detailed method for setting the film formation conditions will also be described in the next embodiment.

  In this example, first, these evaluation tests were carried out in order to confirm the effects of the present invention on crack resistance and corrosion resistance. Aluminum alloy ingots having the respective component compositions shown in Table 1 (the unit of the numerical values shown in the column of each element shown in Table 1 is mass%) are melted (size: 220 mmW × 250 mmL × t100 mm, cooling rate: 15 to 10) The ingot was cut and chamfered (size: 220 mmW × 150 mmL × t60 mm), and then subjected to soaking (540 ° C. × 4 h). After soaking, the 60 mm thick material was rolled into a 6 mm thick plate by hot rolling, cut (size: 220 mmW × 400 mmL × t6 mm), and then subjected to a solution treatment (510-520 ° C. × 30 min). After the solution treatment, water quenching was performed, and an aging treatment (160 to 180 ° C. × 8 h) was performed to obtain a match metal plate.

A test piece of 25 mm × 35 mm (rolling direction) × t 3 mm was cut out from the game metal plate, and the surface thereof was chamfered to a surface roughness of Ra 1.6. Next, after immersing in a 60 ° C.-10% NaOH aqueous solution for 2 minutes and then washing with water, and further immersing in a 30 ° C.-20% HNO ₃ aqueous solution for 2 minutes and then washing with water to clean the surface, Table 1 shows Anodizing was performed under each condition to form a porous anodic oxide film on the surface of the test piece. The film thickness of the formed porous anodic oxide film was in the range of 45 ± 2 μm by adjusting the treatment time.

Each sample (aluminum alloy member) prepared as described above is allowed to stand for 4 hours in a 5% Cl ₂ —Ar gas atmosphere (400 ° C.), and then visually observed for the presence or absence of corrosion (details) In Japanese Patent Application Laid-Open No. 2003-34894 filed earlier by the present applicant), and repeated evaluation tests were conducted until occurrence of corrosion was observed. A sample in which the occurrence of corrosion was confirmed for the first time in 9 to 10 cycles or a sample that could not be confirmed in 10 cycles was judged to be appropriate, and these were regarded as acceptable. These acceptable samples were evaluated as aluminum alloy members excellent in crack resistance and corrosion resistance in the present invention. The evaluation test was performed up to 10 cycles, and when corrosion could not be confirmed even after 10 cycles, it was listed in Table 1 as “> 10”.

  The test results are shown in Table 1 and FIG. In Table 1, crack resistance and corrosion resistance are summarized and described as corrosion resistance. In addition, the porosity is obtained by measuring the volume of the void by SEM (Scanning Electron Microscope) observation or TEM (Transmission Electron Microscope) observation of the coating surface or cross section, and calculating it as a percentage (%) as a ratio to the apparent film volume. The density was obtained by substituting the void ratio and the apparent film density into the formula of “true density = film apparent density / ((100−void ratio) / 100)”. In FIG. Only data 1 to 17 are shown in the graph.

  According to Table 1, after appropriately adjusting the alloy composition of the base material made of an aluminum alloy, No. 1 satisfying the condition of “porosity of film ≧ 61-7 × true density of film”. In 5, 6, 7, 12, 13, 14, 15, and 16, the occurrence of corrosion was confirmed for the first time in 9 to 10 cycles, or could not be confirmed even in 10 cycles. These can be judged to be appropriate samples.

  On the other hand, although the alloy composition of the base material made of an aluminum alloy does not satisfy the conditions, No. 1 satisfying the condition of “the porosity of the film ≧ 61−7 × the true density of the film”. In 18, 19, and 20, the occurrence of corrosion was confirmed only after 5 or 6 cycles. These No. The reason why the occurrence of corrosion was confirmed in 18, 19 and 20 in 5 or 6 cycles is considered to be that the compound was coarsened to generate corrosives. In addition, the alloy composition of the base material made of an aluminum alloy is No. which does not satisfy both the conditions and the condition “the porosity of the film ≧ 61−7 × the true density of the film”. In 1, 2, 3, 4, 8, 9, 10, 11, 17, the occurrence of corrosion was confirmed between 2 and 4 cycles.

  From the results of the evaluation tests described above, the alloy composition of the base material made of an aluminum alloy was Mg: 0.4 to 1.5 mass%, Si: 0.4 to 1.5 mass%, and Mn: 0.4 to 1. 5 mass%, Fe, Cr and Cu contents are restricted to 0.03 mass% or less respectively, and the balance is Al and inevitable impurities, and the relationship between the porosity and the true density of the porous anodic oxide film However, it was confirmed that an aluminum alloy member excellent in crack resistance and corrosion resistance can be obtained by satisfying the condition of “porosity of film ≧ 61−7 × true density of film”. It was also confirmed that an aluminum alloy member having further excellent crack resistance and corrosion resistance can be obtained by appropriately adjusting the alloy composition of a base material made of an aluminum alloy.

  In addition, No. produced using the aluminum alloy base material with which content of Fe, Cr, and Cu was each controlled to 0.03 mass% or less. Samples 1, 2, 3, and 4 did not satisfy the condition of “porosity of film ≧ 61−7 × true density of film” because any of the contents of Mg, Si, and Mn was 0. The cause is considered to be not within the range of 4 to 1.5% by mass.

  This is presumably because the effect of Mg—Si—Mn is not sufficient, the pore diameter of the film is reduced, and as a result, the porosity is reduced. The porosity shown in Table 1 is as small as 16.2 to 19.8 with respect to the true density of 61-7 × film, and the treatment temperature is already as high as 35 ° C. Even if the treatment temperature is raised to 40 ° C. However, the porosity cannot be increased sufficiently. In addition, even if the electrolytic voltage during anodizing treatment, which has a trade-off relationship with the pore diameter, true density, and number density of pores, is adjusted, the condition “the porosity of the film ≧ 61−7 × the true density of the film” is satisfied. There is little chance of being able to do it. Therefore, no. It can be judged that the application of aluminum alloys having compositions of 1, 2, 3, 4 should be abandoned.

  Similarly, No. 1 manufactured using an aluminum alloy base material in which the contents of Fe, Cr, and Cu are regulated to 0.03% by mass or less, respectively. Samples of 8, 9, 10, and 11 also did not satisfy the condition of “porosity of film ≧ 61−7 × true density of film”.

  However, the contents of Mg, Si, and Mn all fall within the range of 0.4 to 1.5 mass%, and the composition of the aluminum alloy base material is No. 1 with the same composition. 12 and 13 satisfy the condition that “the porosity of the film ≧ 61−7 × the true density of the film”, the electrolytic voltage during the anodizing treatment, the treatment temperature of the anodizing treatment, and the anodizing solution It is considered that an aluminum alloy member excellent in crack resistance and corrosion resistance can be produced by adjusting the formation conditions of the porous anodic oxide film, such as the composition.

  No. For Nos. 8 and 9, the treatment liquid temperatures are as low as 25 ° C. and 28 ° C., respectively, and the porosity shown in Table 1 is slightly lower than the true density of the 61-7 × film. There is a possibility that a desired porous anodic oxide film can be formed by increasing the temperature, and the formation conditions of the porous anodic oxide film may be adjusted and set in that direction.

  No. For No. 10, since the porosity shown in Table 1 is only 0.1-7 lower than the true density of the 61-7 × film, there is a particular problem with the temperature control capability in the processing equipment and the countermeasures against evaporation of the processing liquid. If there is not, it can respond by raising the temperature of the processing solution from 34 ° C. In addition, when there are equipment restrictions, the difference between the porosity and the true density of the 61-7 × film is slight. Therefore, by optimizing the electrolytic voltage during anodization, “the porosity of the film” There is a possibility that the condition “≧ 61−7 × the true density of the film” can be satisfied. Therefore, by setting the quantitative relationship with the pore diameter, true density, and pore number density of the film at an electrolytic voltage of around 50V, and optimizing the electrolytic voltage, the conditions for forming the porous anodic oxide film should be set. If there is a possibility, it is sufficient to start setting the conditions for forming the porous anodic oxide film.

  No. 1 in which the electrolytic voltage during anodizing was 55V. Regarding No. 11, although the pore diameter of the film was increased, the number density of the pores was decreased, and as a result, the porosity was decreased, and it is expected that a desired film can be formed by lowering the electrolytic voltage. No. with an electrolysis voltage of 50V. Since the porosity was somewhat small even at 10, it can be assumed that a desired film can be formed by lowering the electrolysis voltage below 50V. Actually, no. In No. 13, the desired film could be formed by setting the electrolytic voltage to 45V.

Moreover, when each sample (aluminum alloy member) was heated at 400 ° C. in a 5% Cl ₂ —Ar gas atmosphere, the stress (unit: MPa) applied to the porous anodic oxide film was measured using a thin film stress measuring device ( Measurement was performed by heating the porous anodic oxide film from room temperature to 400 ° C. using KLA Tencor, FLX-2320). The results are shown in Table 2.

  From the relationship between the stress applied to the porous anodic oxide film obtained in this test and the porosity, “the force applied to the porous anodic oxide film decreases as the porosity of the porous anodic oxide film increases”. I understand that.

  Thus, since the force applied to the porous anodic oxide film and the porosity are correlated, the conditional expression “the porosity of the film ≧ 61−7 × the true density of the film” is obtained from the results shown in Table 2. It can be replaced by the conditional expression “stress (MPa) applied to the film during heating at 14000/400 ° C. ≧ 61−7 × true density of film”. Naturally, in this test result shown in Table 2, the same test result as the previous test result shown in Table 1 could be obtained.

  Next, in the previous test heated to 400 ° C., No. 1-4, no. 8-11, no. With respect to No. 17, each sample (aluminum alloy member) was newly produced from the game metal plate, and a corrosion test at 350 ° C. heating was performed in the same manner as at 400 ° C. heating. Furthermore, No. which failed in this test. 1-4, no. 8, no. About 17 again, each sample (aluminum alloy member) was produced from the game metal plate, and the corrosion test at the time of 300 degreeC heating was implemented in the same way as the time of 400 degreeC heating. These test results are shown in Table 3 and FIG.

  FIG. 2 also shows test results when heated at 400 ° C. in addition to heating at 350 ° C. and 300 ° C. Considering all these test results together, at the test temperature T ° C., the relationship between the porosity of the porous anodic oxide film and the true density is “the porosity of the film ≧ (201−0.35 × T) − ( It was found that those satisfying the condition of “71−0.16T) × the true density of the film passed the test result. In Table 3, it was determined by substituting 350 ° C. and 300 ° C. into the formula “(201−0.35 × T) − (71−0.16T) × true density of film”. “-15 × true density” and “96-23 × true density” are displayed.

  That is, from the expression “porosity of the film ≧ (201−0.35 × T) − (71−0.16T) × true density of the film”, the crack resistance and resistance at the use temperature T ° C. above 300 ° C. Corrosivity can be confirmed, and formation conditions of crack resistance and corrosion resistance at a use temperature T ° C. at 300 ° C. or higher can be set.

  Subsequently, an evaluation of contamination of the back surface of the processing object from the lower electrode, susceptor, electrostatic chuck, or the like on which the processing object such as a silicon wafer in a semiconductor manufacturing apparatus or a glass substrate in a CVD apparatus is placed, that is, An evaluation test for low contamination was conducted.

The low contamination evaluation test is performed at 400 ° C., which simulates the usage environment of the lower electrode by placing a Si substrate on each test piece that has been anodized under the conditions shown in Table 1, respectively. Vacuum heat treatment was performed for 2 hours under reduced pressure of 1.5 × 10 ⁻³ Torr (2 Pa). Thereafter, the back surface of the Si substrate in contact with the test piece was analyzed using total reflection X-ray fluorescence analysis (TXRF). In addition, the sample used for this test was No. which passed the test shown in Table 1. Evaluation tests were conducted only on 5, 6, 7, 12, 13, 14, 15, and 16.

Since the low contamination required in an actual semiconductor manufacturing apparatus or the like differs depending on each process, use environment, etc., it is difficult to quantitatively set a reference value for low contamination. Therefore, in this evaluation test, the low-contamination evaluation is performed assuming the latest process with a wiring width of 45 nm, and Fe per unit area on the back surface of the Si substrate measured using total reflection X-ray fluorescence analysis (TXRF). When the number of atoms was 10 × 10 ¹⁰ atoms / cm ² or less, the anodized film of the test piece was judged to be excellent in low contamination.

As described above, the barrier thickness between pores is the average value of the barrier thickness between pores existing in 1 μm ² when the surface of the anodized film is observed with SEM (scanning electron microscope). Indicates. Specifically, when observing the surface of the anodized film with an SEM (scanning electron microscope), the shortest distance between the adjacent pores (the minimum thickness of the solid portion) is measured for 10 or more adjacent pores. When the pores were connected to each other, the barrier thickness between the pores was set to 0, and the measured average value was obtained to obtain the barrier thickness between the pores. The test results are shown in Table 4.

No. In 6, 12, and 16, the pore thickness between the pores was 23 nm, 21 nm, and 22 nm, respectively, which were 25 nm or less. Therefore, the number of Fe atoms per unit area on the back surface of the Si substrate was 10 × 10 ¹⁰ atoms / cm. ^{It was 2} or less and was excellent in low contamination.

On the other hand, No. 1 in which the barrier thickness between pores exceeds 25 nm. In 5, 7, 13, 14, and 15, the number of Fe atoms per unit area on the back surface of the Si substrate exceeds 10 × 10 ¹⁰ atoms / cm ² , and it cannot be said that the low contamination property is excellent.

Claims (4)

Mg: 0.4 to 1.5% by mass, Si: 0.4 to 1.5% by mass, Mn: 0.4 to 1.5% by mass, and Fe, Cr, Cu content is 0 respectively. An aluminum alloy member in which a porous anodic oxide film having a film thickness of 30 μm or more is formed on the surface of a base material made of an aluminum alloy that is regulated to 0.03 mass% or less and the balance is Al and inevitable impurities,
Excellent resistance to cracking and corrosion, characterized in that the relationship between the porosity and the true density of the porous anodic oxide film satisfies the condition “the porosity of the film ≧ 61-7 × the true density of the film” Aluminum alloy member.   The aluminum alloy member excellent in crack resistance and corrosion resistance according to claim 1, wherein a barrier thickness between pores of the porous anodic oxide film is 25 nm or less. Mg: 0.4 to 1.5% by mass, Si: 0.4 to 1.5% by mass, Mn: 0.4 to 1.5% by mass, and Fe, Cr, Cu content is 0 respectively. The porous type of an aluminum alloy member in which a porous anodic oxide film having a film thickness of 30 μm or more is formed on the surface of a base material made of an aluminum alloy, the balance of which is regulated to 0.03% by mass or less and the balance is Al and inevitable impurities. A method for confirming crack resistance and corrosion resistance at an operating temperature T ° C of 300 ° C or higher of an anodized film,
The relationship between the porosity and the true density of the porous anodic oxide film satisfies the condition “the porosity of the film ≧ (201−0.35 × T) − (71−0.16T) × the true density of the film”. Thus, it is confirmed that the crack resistance and corrosion resistance of the porous anodic oxide film are good. The method for confirming crack resistance and corrosion resistance of the porous anodic oxide film. Mg: 0.4 to 1.5% by mass, Si: 0.4 to 1.5% by mass, Mn: 0.4 to 1.5% by mass, and Fe, Cr, Cu content is 0 respectively. 0.03% by mass or less, and the conditions for forming a porous anodic oxide film having a film thickness of 30 μm or more are set on the surface of a base material made of an aluminum alloy with the balance being Al and inevitable impurities, 300 A method for setting conditions for forming a porous anodic oxide film excellent in crack resistance and corrosion resistance at a use temperature T ° C. at a temperature equal to or higher than C.
The relationship between the porosity and the true density of the porous anodic oxide film satisfies the condition “the porosity of the film ≧ (201−0.35 × T) − (71−0.16T) × the true density of the film”. As described above, a method for setting conditions for forming a porous anodic oxide film excellent in crack resistance and corrosion resistance, characterized in that the conditions for forming the porous anodic oxide film are set.

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