JP2001350253A - Frame for pellicle made of aluminum and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frame for a pellicle less liable to fade and capable of accurately transferring a pattern circuit. SOLUTION: In a step S1, a frame material for a pellicle made of aluminum is anodically oxidized in an electrolytic solution of an organic acid having a functional group using at least carbon and oxygen as constitutional elements. In a step S2, the frame material anodically oxidized in the step S1 is dyed with a black organic dye.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum pellicle frame used in a pattern circuit printing step by irradiating a light beam when manufacturing an LSI or a liquid crystal, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Aluminum (pure aluminum or aluminum alloy) is used as a pellicle frame because it is lightweight and easy to process, and is given corrosion resistance by anodic oxidation treatment, dyeing treatment, etc., and can accurately blacken the surface. Have been.

In manufacturing such a pellicle frame, first, a frame material processed to a predetermined size is anodized in a sulfuric acid aqueous solution, and then the anodized frame material is blackened with an organic dye. Dyeing has been performed. The anodic oxidation treatment imparts corrosion resistance and abrasion resistance to the frame material, and blackening and dyeing facilitates inspection of foreign substances, and further prevents scattering of irradiation light and prints the pattern circuit with high accuracy. It is planned.

[0004]

By the way, the irradiation light source used in the lithography process such as at the time of manufacturing an LSI or a liquid crystal is a high-energy ray having few disturbance factors, for example, i-line (wavelength 365 nm), g-line ( High energy ultraviolet rays having a wavelength of 435 nm are used.

[0005] In recent years, pattern circuits have become finer due to an increase in the degree of integration of LSIs. In order to print a dense pattern circuit, it is considered to use far ultraviolet rays having high resolution and high energy, for example, excimer laser light (wavelength 248 nm, wavelength 193 nm, etc.) as a light source.

However, when such high-energy ultraviolet rays are used, since the sulfuric acid anodic oxidation film is a transparent film, the organic dye is decomposed by the irradiation ultraviolet rays,
There is a disadvantage in that black is easily discolored, and in the lithography process, irradiation light is reflected at a discolored portion and disturbs the transfer pattern circuit.

For this reason, a method has been proposed in which a metal is deposited in the pores of an oxide film by secondary electrolytic treatment (Japanese Patent Application Laid-Open No. 9-236908). However, in the secondary electrolytic treatment, it is difficult to control the liquid such as the pH and the liquid temperature, the equipment cost is high, and the waste liquid is also required. Also,
It is conceivable to provide a black organic dye layer after the secondary electrolytic treatment, but the manufacturing process of the pellicle frame becomes complicated.

An object of the present invention is to provide a pellicle frame capable of transferring a pattern circuit with high precision with little fading and a method of manufacturing the same.

[0009]

Means for Solving the Problems The inventors of the present invention have studied to solve the above-mentioned drawbacks, and as a result, have found that a black organic organic anodic oxide film having a functional group containing carbon and oxygen as constituent elements is formed on the anodic oxide film. When a dye layer is provided, there is no need to particularly increase the thickness of the film, and even when irradiated with high-energy ultraviolet rays, there is little fading of the black organic dye, and it can withstand long-term use when used as a pellicle frame. I discovered that.

That is, according to the present invention, an anodic oxide film containing carbon and / or a carbon compound dispersed therein is formed on the surface of an aluminum pellicle frame material, and a black dye layer is formed on the anodic oxide film. This is a pellicle frame made of aluminum. By providing the pellicle frame with an anodized film containing carbon or a carbon compound or both dispersedly, because the film is black in color, it absorbs the energy of the irradiation light and is further provided on the film. It has the effect of preventing fading of the black organic dye.

Further, since the black organic dye layer is provided on the film, it is not necessary to blacken only the film. For example, in order to blacken only the film, the thickness of the film is increased and the black density is increased. As a result, large cracks are likely to occur in the film, and if cracks are likely to occur, it is necessary to take measures against cracks, but in the present invention, there is no need for such crack measures, the thickness of the anodic oxide film 5
It is possible to achieve prevention of fading of the black organic dye with a film having a thickness as thin as 15 μm. The thickness of the anodic oxide film is preferably 7 to 12 μm.

Further, the present invention provides a first step of anodizing a pellicle frame material made of aluminum in an organic acid electrolytic solution having a functional group containing carbon and oxygen as at least constituent elements; And a second step of dyeing the pellicle frame material with a black organic dye.
By performing anodic oxidation treatment in an organic acid electrolyte having a functional group containing carbon and oxygen as at least constituent elements, a black colored anodic oxide film containing carbon and / or a carbon compound dispersed therein can be formed, and further black. By dyeing with a system organic dye, a pellicle frame that can be used for a long time with little fading can be manufactured in a simple process.

Further, when an inorganic acid is contained in the electrolytic solution to be anodized, pores are easily formed in the film, the number and the depth of the pores are increased as compared with the case of using only the organic acid, and the area of the dye adhered is increased. Blackened easily. Before dyeing,
By dipping the anodized frame material in an aqueous acid solution, the amount of positive charge of the frame material is increased, and the throwing power of the negatively charged black organic dye is improved.

When a functional group containing at least carbon and oxygen as a constituent element is a carboxyl group (structural formula: -COOH), a stable aqueous solution can be obtained, and a good black anodic oxide film can be formed.

When the aqueous solution of an inorganic acid and an acid is an aqueous acid solution containing nitric acid or sulfuric acid or a mixed acid thereof as a main component, blackening in a dyeing step after anodic oxidation is further improved with a stable aqueous acid solution.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pellicle frame according to the present invention will be described. The composition of aluminum as the pellicle frame material is not particularly limited, but 5000 type, 6000 type, and 7000 type alloys are suitable because workability, corrosion resistance, and strength are required.

FIG. 2 is a perspective view of a pellicle frame having a typical shape. As shown in FIG. 2, the pellicle frame 11 has a rectangular shape, and a corner 11A is formed in a round shape.

FIGS. 3A and 3B show the use of the pellicle frame. FIG. 3A is a sectional view of the pellicle frame with the pellicle frame attached to a photoresist mask, and FIG. 3B is a sectional view of the pellicle frame. . As shown in FIG. 3A, a circuit wiring diagram (circuit pattern) 13 such as an IC or LSI is formed on a surface of a photoresist mask 12 made of hard glass. The photoresist mask 12 is mounted on a transfer device (stepper) (not shown), the circuit wiring diagram 13 is exposed, and a circuit pattern is transferred to a semiconductor substrate (not shown). In this case, if dust adheres to the circuit wiring diagram 13, the transferred wiring diagram becomes unclear. To prevent this, the pellicle frame 11, which is an optical device component, is attached to the photoresist mask 12. Be worn. A translucent pellicle film 14 is adhered to the pellicle frame 11.
It is attached to the photoresist mask 12 so as to cover the entire original drawing of the circuit wiring diagram 13. The same pellicle frame 11 as described above may be provided on the opposite side 17 of the photoresist mask 12 on the circuit wiring diagram 13 side for use. The size of the pellicle frame 11 corresponds to the size of the photoresist mask 12.

FIG. 3 shows one end surface of the pellicle frame 11 on one side.
As shown in (B), a patch 16 on which a patch protective film 15 is stretched is applied in advance, and when the pellicle frame 11 is attached to the photoresist mask 12, the adhesive protection is performed. Membrane 1
5 is peeled off and the surface on which the adhesive 16 is applied is brought into close contact with the photoresist mask 12. Thus, the pellicle frame 1
When 1 is adhered to the photoresist mask 12, the dust is blocked by the pellicle film 14 and does not adhere to the circuit wiring diagram 13. Also, even if dust adheres to the pellicle film 14, the dust is defocused by the light from the external light source passing through the lens and is not imaged, so that the image formed on the semiconductor substrate surface is the circuit wiring as shown in the original drawing. The figure is transcribed.

An anodized film is formed on the pellicle frame. If carbon or a carbon compound or both are dispersed in the anodic oxide film, the film is colored black, so that a pellicle frame having a black organic dye layer provided on this film is used. With such a frame, even when the pellicle frame is irradiated with high-energy ultraviolet rays in the lithography process, as shown in FIG. 1, the irradiation light beam 1 passes through the thin black organic dye layer 2 and passes therethrough. The energy of the irradiation light 3 is attenuated by the anodic oxide film 4 in which carbon or a carbon compound or both are dispersed provided on the surface of the aluminum base 6 of the pellicle frame material, and the black light adheres to the inner wall surface of the pore 5 and the film surface. The organic dye layer 2 is less likely to be decomposed and is less likely to fade. As the organic dye, for example, SANODAL DEEP BLACK MLW manufactured by Sando Co., Ltd. is suitable.

In order to color the coating black, it is preferable that the thickness of the coating is 30 μm or more. However, if the coating is too thick, cracks occur after anodizing treatment. Is preferably kept to 15 μm or less. More preferably, it is 12 μm or less. By doing so, it is possible to provide a pellicle frame in which the oxide film has no cracks and there is no danger of generating dust, and there is no occurrence of circuit transfer failure due to dust in the lithography process, and accurate circuit transfer can be performed.

Next, a method of manufacturing the pellicle frame will be described. FIG. 4 shows a manufacturing procedure of the pellicle frame. First, the pellicle frame material is anodized in an organic acid electrolyte having a functional group containing carbon and oxygen as constituent elements (step S1). Next, the pellicle frame material that has been anodized is dyed with a black organic dye (step S2).

The anodic oxide film is formed by electrolysis using a metal as an anode in an electrolytic solution containing an electrolyte, and the generated oxygen oxidizes the metal to form an oxide film on the metal surface. When the metal is aluminum, the surface becomes aluminum oxide and gradually grows into a film while forming a large number of pores through which electric current passes. However, carbon or a carbon compound or both are dispersed in the film. It is thought that it is contained for the following reasons.

That is, when the electrolytic solution contains an organic acid having a functional group containing at least carbon and oxygen as constituent elements as an electrolyte, the functional group is decomposed into carbon and oxygen at the time of anodic oxidation treatment, and the surface of aluminum becomes aluminum oxide. In the process of growing as a film, decomposed carbon or a carbon compound such as a functional group or an organic acid is incorporated into the film.

[0025] Carbon and carbon compounds can be confirmed by analysis using both fluorescent X-ray analysis and infrared spectroscopy.

The conditions of the anodizing treatment are, for example, as follows. A functional group containing at least carbon and oxygen as a constituent element includes a carboxyl group and the like. As the organic acid having such a functional group, for example, maleic acid represented by the following structural formula is suitable.

[0027]

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Particularly, carbon and oxygen are at least constituent elements.
When the functional group is a carboxyl group,
With a small amount of acid, a black anodic oxide film can be formed.
A preferred example of the processing is as follows. Organic acid amount: 0.1 to 30 wt% aqueous solution, preferably 1 to
10 wt% aqueous solution Current: DC or AC or superimposed AC / DC Current density: 0.5 to 4 A / dm², Preferably 1-3A
/ Dm²  Voltage: ~ 120V, preferably 40 ~ 80V Liquid temperature: 5 ~ 40 ° C, preferably 15 ~ 25 ° C

The pellicle frame anodized by the above method is dyed with an organic dye. As described above, for example, Sanodal Deep Black MLW manufactured by Sando is suitable as the organic dye.

The conditions for dyeing the organic dye are as follows, for example. The amount of the above organic dye: 5 to 20 g / L, preferably 10 to 20 g / L
15 g / L liquid temperature: 50 to 60 ° C., preferably 55 to 6
0 ° C

It is preferable that pores formed in the anodic oxide film after the dyeing treatment are closed, and a sealing treatment is carried out in order to eliminate the possibility of accumulation of dust.

When the dyeing treatment is performed, a dye layer is formed on the film including the pore wall. In this case, the dye layer adhered to the pore wall has a higher areal density of the dye than the dye layer adhered to the film plane, and contributes to blackening. High degree. The thickness of this dye layer is 1 to
Considered several molecular layers.

As the inorganic acid to be added to the above-mentioned electrolyte containing an organic acid, for example, sulfuric acid, phosphoric acid or a mixed acid thereof is suitable. Addition amount of inorganic acid is 0.5 to 30 wt%
Is preferred. By adding the inorganic acid, pores are uniformly formed in the film. The dimensions of the pores in the film when this inorganic acid is added vary depending on the type of electrolyte, temperature, electrolysis conditions, etc., but the inner diameter is about 250 to 500 °, and the wall thickness between adjacent pores is 1000 ~ 200
The film thickness of the pore bottom is about 1000 ° and about 2000 °.

When the pellicle frame after the anodizing treatment is immersed in, for example, an aqueous solution of nitric acid or sulfuric acid or a mixed acid thereof, the + charge amount of the pellicle frame is increased, and
Improves the coverage of black organic dyes that are electrically charged. The amount of the acid is, for example, a 0.5 to 50 wt% aqueous solution, preferably a 5 to 40 wt% aqueous solution.

[0035]

(Example 1) AA7075A treated with T6
Cut a hollow extruded material of Luminium alloy, 148mm wide
Cutting and polishing a pellicle frame of 122 mm long x 2 mm thick
Prepared, anodized under the following conditions, immersed in an aqueous acid solution
Pellicle after treatment and dyeing with organic dye
A frame was made. Anodizing treatment conditions Electrolyte: aqueous solution containing 5% by weight of sulfosalicylic acid
Or an aqueous solution containing 5% by weight of malonic acid Liquid temperature: 15 ° C Current density: 3 A / dm²  Dyeing treatment with organic dye Organic dye: SANODAR DEEP
Rack MLW Concentration of organic dye: 10 g / L Liquid temperature: 60 ° C. Immersion time: 10 minutes

Example 1-1 contains sulfosalicylic acid, and Example 1-1 contains malonic acid.
Let it be 2. The structural formulas of sulfosalicylic acid and malonic acid are shown below.

[0037]

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[0038]

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Under the above conditions, the pellicle frame material was anodized to form oxide film thicknesses of 2, 10, 20, and 30 μm, respectively. The evaluation of the color tone of this frame was indicated using a lightness index L * based on the Hunter's color difference formula. The film was inspected for cracks by a 10-fold magnification method, and the percentage of occurrence of cracks was measured by visual inspection. The frame was analyzed for anodic oxidation by X-ray fluorescence analysis and infrared spectroscopy.
Carbon or carbon compounds were detected. Further, another frame subjected to the anodizing treatment was subjected to a dyeing treatment with an organic dye under the above conditions for 10 minutes to obtain a pellicle frame. This frame was subjected to an ultraviolet irradiation test under the following conditions to visually inspect fading resistance. Table 1 shows the results. UV irradiation test conditions Wavelength used: 235.7 nm UV output: 15 W Irradiation time: 100 hours

(Example 2) A solution in which 0.5 wt% of sulfuric acid was further added to the electrolytic solution under the conditions used in Example 1 was used, and the other conditions were the same as in Example 1. The measurement items and the conditions were the same. Table 1 shows the results.

The case containing sulfosalicylic acid and sulfuric acid is referred to as Example 2-1 and the case containing malonic acid and sulfuric acid is referred to as Example 2-2.

Comparative Example 1 An electrolytic solution containing 15% by weight of sulfuric acid was used in place of the electrolytic solution used in Example 1, and the other conditions were the same as in Example 1. Oxide film thicknesses of 2, 10, 20, and 30 μm were formed, and the measurement items and conditions were the same. Table 1 shows the results.
Shown in This comparative example is referred to as Comparative Example 1-1 in Table 1.

[0043]

[Table 1]

In Table 1, a circle in the column of fading resistance indicates that no fading was observed by visual inspection, and a cross indicates that fading was observed by visual inspection. In the column of crack occurrence ratio, 0/5 means that no cracks occurred in all five frames, and 1/5 means that cracks occurred in one frame.
5/5 indicates that cracks occurred in all the frames. The lower the lightness index L * value, the more the color is colored black.

The following can be seen from the results in Table 1. That is, it is found that the film containing carbon or carbon compound or both in the anodic oxide film is colored black, and the black organic dye can be provided with fading resistance to ultraviolet irradiation. It can be seen that as the film thickness increases, the black color becomes deeper and the film is already colored at 10 μm, and that the black organic dye can be given fading resistance to ultraviolet irradiation.

When anodizing is performed in an organic acid electrolyte having a functional group containing at least carbon and oxygen as constituent elements, the oxide film is colored black and is resistant to discoloration to a black organic dye upon irradiation with ultraviolet rays. It can be seen that the property can be imparted. Further, it can be seen that when the above-mentioned organic acid electrolyte is treated in an electrolyte containing sulfuric acid, the organic acid electrolyte has an effect of further coloring black.
Also, it can be seen that when the thickness of the oxide film is small, cracks hardly occur.

From Comparative Example 1-1, it can be seen that the anodic oxide film formed by the sulfuric acid electrolytic solution is transparent, and the black organic dye fades upon irradiation with ultraviolet rays.

(Example 3) Anodizing treatment conditions Electrolyte solution: sulfosalicylic acid 5 wt%, malonic acid 5 wt%
%, 5% by weight of sulfosalicylic acid + 0.5% by weight of sulfuric acid, 5% by weight of sulfophthalic acid having a carboxyl group and a sulfone group + 0.5% by weight of sulfuric acid, or 5% by weight of malonic acid having a functional group of a carboxyl group + 0.5% of sulfuric acid %

Anodizing film treatment was performed under the conditions of the above electrolytic solution and the temperature and current density of Example 1 to form a film having a thickness of 10 μm, and the film was immersed in an acid aqueous solution having various acid contents under the following conditions. Next, a pellicle frame was dyed with an organic dye under the same conditions as in Example 1 and sealed with hot water. With respect to this frame, the color tone before and after the ultraviolet irradiation was measured. The ultraviolet irradiation conditions are the same as in the first embodiment. The evaluation of the color tone was indicated using a lightness index L * according to the Hunter's color difference formula. Table 2 shows the results. Immersion treatment conditions in acid aqueous solution Acid aqueous solution: nitric acid concentration 0.1, 10, 20, 30, 40 w
Aqueous solution containing t% Liquid temperature: 25 ° C Immersion time: 1 minute

In Example 3-1 where treatment with sulfosalicylic acid was carried out without immersion in an aqueous acid solution, and in Example 3-2 where treatment was carried out with malonic acid and without immersion in an aqueous acid solution, sulfosalicylic acid and sulfuric acid were contained. Example 3-3 is a case where the cell is treated with an electrolytic solution and is not immersed in an acid aqueous solution. Similarly, the case of containing malonic acid and sulfuric acid and having a nitric acid concentration of 10 in Example 3-5, the case of containing sulfophthalic acid and sulfuric acid and having a nitric acid concentration of 20 in Example 3-6, and containing nitric acid containing sulfophthalic acid and sulfuric acid. Concentration 30
The case of Example 3-7 is referred to as Example 3-7, and the case of containing sulfophthalic acid and sulfuric acid and having a nitric acid concentration of 40 is referred to as Example 3-8. The structural formula of sulfophthalic acid is shown below.

[0051]

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(Example 4) After anodizing under the same conditions as in Example 3, immersion in an aqueous acid solution having various acid contents under the following conditions, and then dyeing with an organic dye under the same conditions as in Example 1 To give a pellicle frame. With respect to this frame, the color tone before and after the ultraviolet irradiation was measured. The ultraviolet irradiation conditions are the same as in the first embodiment. Table 2 shows the results. Immersion treatment conditions in acid aqueous solution Acid aqueous solution: sulfuric acid concentration 0.1, 10, 20, 30, 40 w
Aqueous solution containing t% Liquid temperature: 25 ° C Immersion time: 1 minute

In this embodiment, all contain 5 wt% of sulfophthalic acid and 0.5 wt% of sulfuric acid as electrolytes. Example 4-1 when the acid aqueous solution to be immersed after anodic oxidation was 0.1 in sulfuric acid concentration, and Example 4- in the case of 10% sulfuric acid concentration
2. The case of sulfuric acid concentration of 20 was used in Example 4-3, sulfuric acid concentration of 30.
Example 4-4 in the case of (1) and Example 4 in the case of sulfuric acid concentration of 40
-5.

[0054]

[Table 2]

The following can be seen from the results in Table 2. That is, the lightness index L * 1 after dyeing of the pellicle frame containing no acid in the organic acid anodizing electrolyte (Example 3-1 and Example 3-2) is 28.0, The lightness index L * after dyeing of the pellicle frame containing an acid in the organic acid anodizing electrolyte (Example 3-3) is as low as 27.1. It can be seen that the toner has good surrounding properties and can be darkened.

The lightness index L * 1 after dyeing of the pellicle frame material (Example 3-3) which was not immersed in the aqueous acid solution after the organic acid anodic oxidation treatment was 27.1. Frame material for immersed pellicle (Examples 3-4, 3-6, 3-
7, 3-8 and Examples 4-1, 4-2, 4-3, 4-
No. 4,4-5) shows that the lightness index L * 1 after dyeing is as low as 26.7 to 22.4 in the dyeing treatment with an organic dye. It turns out that surrounding property becomes favorable.

The lightness of the pellicle frame prepared in the comparative example was L * 2 after irradiation of 49.6, and the lightness difference ΔL between before and after irradiation was 20.8, indicating that the color was sharply faded.

[0058]

As described above, the aluminum pellicle frame of the present invention contains carbon in the oxide film,
Even when irradiated with high-energy ultraviolet rays, there is little fading of the black organic dye, and it can withstand long-term use. As a result, the circuit transfer cost in the lithography process can be reduced, and furthermore, the reflection of the irradiation light is small, and the circuit pattern can be precisely transferred without blurring.

In addition, since an organic acid having a functional group containing at least carbon and oxygen is used as the electrolyte of the electrolytic solution of the anodizing treatment, carbon can be easily contained in the oxide film. The organic dye can be easily attached and the dyeing time can be shortened simply by adding an acid to the electrolyte or immersing it in an acid-containing aqueous solution after the anodic oxidation treatment.

Further, a pellicle frame having little effect of fading of the black organic dye even when irradiated with high-energy ultraviolet rays and having an effect of withstanding long-term use can be manufactured by a simple process.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing one side of a cross section of a pellicle frame in an enlarged manner.

FIG. 2 is a perspective view of an aluminum pellicle frame according to the present invention.

3A and 3B show a usage form of a pellicle frame, in which FIG. 3A is a cross-sectional view showing a state in which the pellicle frame is attached to a photoresist mask, and FIG. 3B is a cross-sectional view of the pellicle frame.

FIG. 4 is a flowchart showing a procedure for manufacturing a pellicle frame.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Irradiation light 2 Black organic dye layer 3 Passing irradiation light 4 Anodized film 5 Pore (hole) 6 Aluminum ground of pellicle frame material 7 Reflected light whose passing irradiation light 3 was reflected by aluminum ground 6 and changed its direction 8 Carbon or carbon compound taken in film 4 11 Pellicle frame 11A Corner 12 Photoresist mask 13 Circuit wiring diagram 14 Pellicle film 15 Adhesive protective film 16 Adhesive

Claims (8)

[Claims] An anodic oxide film containing carbon and / or a carbon compound dispersed therein is formed on the surface of an aluminum pellicle frame material, and a black organic dye layer is formed on the anodic oxide film. An aluminum pellicle frame. 2. The anodic oxide film has a thickness of 5 to 15 μm.
The aluminum pellicle frame according to claim 1, wherein: 3. A first step of anodizing an aluminum pellicle frame material in an organic acid electrolyte having a functional group containing at least carbon and oxygen as constituent elements, and the anodized pellicle. A second step of dyeing the frame material with a black organic dye. A method for manufacturing an aluminum pellicle frame. 4. The method for producing an aluminum pellicle frame according to claim 3, wherein the organic acid electrolyte contains an inorganic acid. 5. The method according to claim 3, wherein a step of dipping the pellicle frame material anodized in the first step in an aqueous acid solution is inserted before the second step. Manufacturing method of aluminum pellicle frame. 6. The method for producing an aluminum pellicle frame according to claim 3, wherein the functional group is a carboxyl group. 7. The method for producing an aluminum pellicle frame according to claim 4, wherein the inorganic acid is an inorganic acid containing sulfuric acid, phosphoric acid or a mixed acid thereof as a main component. 8. The method for producing an aluminum pellicle frame according to claim 5, wherein the aqueous acid solution is an aqueous acid solution containing nitric acid, sulfuric acid or a mixed acid thereof as a main component.