JP2009003111A - Pellicle frame - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pellicle frame made of an aluminum alloy that can maintain strength and rigidity as well as suppresses production of white dot defects even when the thickness of the frame is relatively thin and that achieves a larger size. <P>SOLUTION: The pellicle frame is made of an aluminum alloy, in which the row material is a 5000-series aluminum alloy having a relatively high Mg content in a structure with less crystallized substances to suppress generation of white dot defects. Thereby, the pellicle frame made of an aluminum alloy can maintain rigidity even when its thickness is relatively thin and can be made large in size to respond to a significantly increased size of a liquid crystal display of a thin liquid crystal television set. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is used to prevent foreign matters such as dust and dust from adhering to a photomask used in a lithography process when manufacturing a TFT-LCD (thin film transistor liquid crystal display: liquid crystal display panel) or the like. The present invention relates to a pellicle frame of a pellicle apparatus.

  When manufacturing a semiconductor device such as a TFT-LCD, LSI, or VLSI, patterning is performed by irradiating a semiconductor wafer or a liquid crystal original plate with light. At this time, if foreign matter such as dust or dust adheres to the exposure original plate (lithography mask or photomask) to be used, the transferred pattern is deformed by absorbing or bending the light irradiated with the foreign matter. There arises a problem that the dimensions, quality, appearance, etc. are impaired, such as the edge becoming rough and the ground becoming dirty. For example, in the case of a TFT-LCD, if a foreign substance adheres to the surface of the photomask, the foreign substance forms an image on a photoresist formed on the TFT-LCD mother glass, causing a circuit pattern defect. Become.

  These patterning operations are usually performed in a clean room, but it is difficult to always keep the exposure original plate clean even in such a clean room. For this reason, normally, dust-proof members called pellicle devices are arranged on both sides of the photomask to prevent foreign matter from adhering to the photomask.

  This pellicle has originally been used as a dust-proof cover for a photomask for semiconductor lithography such as LSI or VLSI. However, in recent years, it is also used for dust-proofing a photomask in a TFT circuit forming process and a color filter forming process in the manufacturing process of a liquid crystal display panel which is becoming increasingly fine. When pellicles that allow exposure light to pass well are arranged on both sides of the photomask, foreign matter present in the atmosphere is blocked by the pellicle and adheres to the pellicle film, causing foreign matter on the photomask surface. Adhesion can be prevented.

  Here, if the focus at the time of lithography is set on the pattern of the exposure original plate, the foreign matter on the pellicle film becomes irrelevant to the transfer and does not have an adverse effect. For example, in the case of TFT-LCD, the foreign matter adhering to the pellicle film does not form an image on the photoresist formed on the TFT-LCD mother glass due to the shift of the focus position, and the circuit pattern is defective. Is not generated.

  As disclosed in Patent Documents 1 to 3 and the like, this pellicle device basically has the following configuration. That is, a transparent pellicle film that transmits light used for exposure well is spread on the upper surface of a pellicle frame made of an aluminum alloy or the like whose surface has been subjected to blackening treatment such as black alumite. The shape of the pellicle frame is known, and as disclosed in the patent documents described later, a rectangular frame shape, or a substantially rectangular shape (approximately rectangular shape, outline) (Rectangular) frame shape or the like is mainstream or basic, but it has an appropriate frame shape according to the shape and use conditions of the photomask.

  The material of this pellicle frame (frame body) is 7000 series (Al-Zn-Mg series), 6000 series (Al-Mg-Si series), 5000 series (Al-Mg series), such as JIS A7075, A6061, A5052. It is made of an aluminum alloy selected from

  Then, a pellicle film made of a transparent polymer film such as nitrocellulose or a cellulose derivative or a fluoropolymer having a thickness of 10 μm or less is attached to one edge face of the pellicle frame body, and the other edge face is attached to the other edge face. Is used by adhering an adhesive and adhering the edge of the adhesive to the surface of the photomask.

  With the widespread use of various types of multimedia, there is a demand for a large pellicle that can be applied to a large photomask used in a photolithography process when manufacturing a large color TFT-LCD capable of high-quality and high-definition display. Therefore, as the size of the pellicle increases, naturally, there is an increasing demand for increasing the size of the aluminum alloy pellicle frame.

  For example, the size of a conventional pellicle for semiconductor lithography was about 150 mm square at the maximum, but the pellicle used in the lithography process of a liquid crystal display panel has a planar size of 1000 mm square as described later. The size is larger than that.

  As the size of the pellicle frame increases, the pellicle frame is required to have a high strength aluminum alloy as a material (base material) as a basic characteristic in order to maintain the state of the pellicle film. The In manufacturing the pellicle frame, first, the pellicle film is spread on a temporary frame body having a strength that does not deform due to film tension, and then the pellicle film is attached to the pellicle frame. At this time, the long side of the pellicle frame tends to be deformed inward by the tension of the pellicle film. If the strength of the aluminum alloy (the rigidity of the pellicle frame) is low, the dimensional specifications and flatness required for the pellicle are satisfied. It may not be possible.

  In addition, the pellicle frame needs to maintain shape accuracy and flatness so as not to cause a defect in a high-precision circuit pattern during lithography when it is repeatedly used in the TFT-LCD manufacturing process. When the shape accuracy and flatness of the pellicle frame deteriorate during repeated use, it can no longer be used as a dustproof member and is discarded. Therefore, durability of the pellicle frame, such as maintaining the shape accuracy and flatness in the repeated use of the pellicle frame, is also an important characteristic. For this reason, the aluminum alloy as a base material also needs strength and rigidity capable of maintaining such shape accuracy and flatness.

  Furthermore, in addition to these mechanical properties, the pellicle frame or the material aluminum alloy is required to have excellent surface properties as basic properties. That is, in the circuit pattern transfer process described above, in order to obtain a clear transfer pattern by preventing reflection of light from the light source, the material aluminum alloy is subjected to black alumite treatment by natural coloring method or anodization treatment. After being applied, it is dyed black.

  However, when each of the above blackening treatments is performed on the surface of the aluminum alloy, a film defect called a so-called white spot is likely to occur on the blackened surface. In recent years, line widths in patterns have become increasingly narrower, and when the thickness is reduced to about 0.5 to 1 μm, depending on the number and size of these white spots, the reflection of light during exposure may make the transferred pattern unclear. Problems have become apparent.

  In addition, these white spots may interfere with the progress of the inspection work for adhered dust depending on the number and size of occurrence. That is, in an apparatus for transferring a circuit pattern, dust adhering to apparatus system members is removed by checking the presence by visual inspection or mechanical inspection. As the circuit pattern becomes thinner, the inspection standard for adhered dust has become increasingly strict in recent years, and even fine dust that has not been a problem in the past has been targeted for inspection. However, since the white spot is confused with these adhering dust, the number of false white spots to be inspected increases and the progress of work is hindered.

  These white spot defects are caused by coarse crystallized substances (intermetallic compounds) on the surface of the material aluminum alloy. Conventionally, various aluminum alloys have been proposed in order to suppress this crystallized substance and suppress white spot defects. For example, in Patent Document 4, an extruded shape of a 7000 series aluminum alloy that expresses high strength by heat treatment is used for a pellicle frame, and an extruded shape that causes the generation of white spot defects in order to prevent the occurrence of white spot defects. It has been proposed to reduce the size and number of crystallized material.

  Further, in Patent Document 5, in order to increase the size of the pellicle frame, it is not a heat-treatable aluminum alloy as in Patent Document 4, but a non-5000 type non-metal such as A5052 having an Mg content of 3.5% by mass or less. A pellicle frame using a heat-treatable aluminum alloy sheet has been proposed. In Patent Document 5, as in Patent Document 4, the size and number of crystallized materials of the raw material aluminum alloy are suppressed to suppress the generation of white spots.

However, when the size of the pellicle frame is increased, the extruded shape as in Patent Document 4 has a limit in the size of the cross-sectional shape, and there is no joint between the sides. I can't make a shape. Therefore, as in Patent Document 5, the center portion of the aluminum alloy plate is removed and processed to produce a pellicle frame having a substantially rectangular frame shape with no joints between the sides.
JP 58-219033 JP 2002-202589 A JP 2006-323178 A JP 2001-279359 A JP 2006-349881 A

  However, even in Patent Document 4 in which the pellicle frame can be enlarged, the planar size of the integrated pellicle frame produced from the plate is only about 915 mm × 760 mm square as far as the numerical value of the embodiment is seen. . Further, the thickness of the material aluminum alloy sheet is only about 5.8 mm as far as the numerical values of the examples are seen. In addition, the 0.2% proof stress of, for example, a JIS 5052 aluminum alloy sheet having an Mg content of 3.5% by mass or less is only 100 MPa or less for a normal O material.

  On the other hand, the pellicle frame has been remarkably increased in size with the recent increase in size of liquid crystal displays of thin liquid crystal televisions such as 40 to 60 inches. The enlarged rectangular pellicle frame has a planar size in which the maximum length of one side is 1200 mm or more, for example, 1400 mm × 1700 mm square.

  However, even if the size of the pellicle frame is increased, the thickness of the material aluminum alloy (the pellicle frame) is limited in order to minimize the increase in weight of the pellicle frame due to the demand for weight reduction of the pellicle device itself. The design is suppressed to a range of about 5.0 to 7.0 mm. That is, even when the pellicle frame is enlarged, the thickness of the material aluminum alloy cannot be made much thicker than the thickness of about 5.8 mm in the case of the small pellicle frame.

  Therefore, such a large-sized pellicle frame material aluminum alloy has improved strength (pellicle frame rigidity) capable of maintaining the above-described shape accuracy and flatness even when the thickness is relatively thin as described above. It becomes important. As described above, the durability of the pellicle frame that is repeatedly used in the TFT-LCD manufacturing process, which can ensure the shape accuracy and flatness during the repeated use, is an important factor for reducing the cost of the process.

  These large pellicle frame material aluminum alloys have this shape accuracy and flatness ensuring durability, which is a necessary basic characteristic of the pellicle frame, and the size and number of crystallized substances in the aluminum alloy structure. It is also desired to achieve the above after suppressing the occurrence of the white spot defect by suppressing the above.

  On the other hand, in the 5000 series aluminum alloy sheet material of Mg content 3.5 mass% or less of the said patent document 4, as a planar magnitude | size, for example, the medium-sized pellicle frame whose one side is 700 mm or less in size. Can be used. However, in the above-mentioned Patent Document 4, the above-mentioned large-sized pellicle frame having a maximum length of 1200 mm or more on one side and a thickness in the range of 5.0 to 7.0 mm and the small pellicle frame If the thickness cannot be increased as much as the thickness of the case, the shape accuracy and flatness cannot be ensured during repeated use, and durability is not achieved.

  The present invention has been made in order to solve such problems, and the object thereof is to ensure strength and rigidity even when the thickness is relatively thin, and to suppress the occurrence of the white spot defect and increase the size. The object is to provide a pellicle frame made of aluminum alloy.

  In order to achieve this object, the gist of the pellicle frame of the present invention is a pellicle frame made of an aluminum alloy, and the aluminum alloy has a mass% of Mg: more than 3.5% and not more than 5.5%. And Ti: 0.005 to 0.15%, B: 0.0005 to 0.05%, one or two of them, Fe: 0.15% or less, Si: 0.10% or less In the structure observation by a scanning electron microscope 10,000 times as much as this aluminum alloy, the total area ratio occupied in the field of the crystallized substance to be observed is 5 %, And the maximum crystallized diameter of the observed crystals is a structure having a circle equivalent diameter of 3 μm or less.

  Here, it is preferable that the pellicle frame is processed by removing a central portion of the material aluminum alloy plate, and has an integrated rectangular frame shape with no joints between the sides. Moreover, it is preferable that only the black alumite-treated film by the natural color development method is provided after the material aluminum alloy surface of the pellicle frame is roughened to a satin finish. Furthermore, it is preferable that the maximum length of one side of the pellicle frame is 1200 mm or more and the thickness is 5.0 to 7.0 mm as the enlarged pellicle frame for the TFT-LCD manufacturing process. The length and thickness of one side of the pellicle frame are also the length and thickness of the material aluminum alloy plate.

  The pellicle frame of the present invention ensures the strength and rigidity of the pellicle frame that is relatively thin and large in size, as the material aluminum alloy is a Mg-Al-based 5000-based aluminum alloy with a relatively high Mg content. And improve durability.

  At the same time, the amount of specific impurity elements inevitably mixed in from melting raw materials such as scrap, such as Fe and Si, is regulated, and the amount of crystallized substances (intermetallic compounds) of these elements and Al is reduced.

  In addition, the size and the amount of crystallization are further influenced by the manufacturing conditions of the plate material such as heat treatment conditions, and the area ratio of the crystallization product and the size of the maximum crystallization product are controlled, Suppresses the occurrence of white spot defects.

  Therefore, according to the present invention, the maximum pellicle frame has a maximum length of one side of 1200 mm or more and a thickness of 5.0 to 7.0 mm, and a relatively small thickness for the size. As a result, the strength and rigidity can be secured and the durability can be improved. For this reason, it contributes also to the efficiency of the circuit pattern transfer work which was enlarged and miniaturized.

  Hereinafter, embodiments of the present invention will be specifically described for each requirement.

(Material aluminum alloy composition)
The material aluminum alloy composition constituting the pellicle frame of the present invention has a maximum length of one side of 1200 mm or more and a thickness of 5.0 to 7.0 mm. The strength and rigidity of the formed pellicle frame shall be ensured. In addition, the amount of crystallized substances (intermetallic compounds) between elements and Al is reduced, and the area ratio of crystallized substances and the maximum size of the crystallized substances are suppressed as much as possible depending on the plate manufacturing conditions such as heat treatment conditions. Thus, the occurrence of the white spot defect is suppressed.

  As a composition for satisfying these characteristics, the composition of the aluminum alloy constituting the pellicle frame of the present invention is, by mass%, Mg: more than 3.5% and 5.5% or less, and Ti: 0.005 to 0.005. Including 0.15%, B: 0.0005-0.05% or two types, Fe: 0.15% or less, Si: 0.10% or less, the balance being Al and inevitable An Al—Mg composition composed of impurities is used. Further, this composition may further contain 0.03 to 1.0% by mass in total of one or more selected from Mn, Cr, Zr and Cu. In addition,% display of content of each element is all the mass%.

(Remainder composition)
In the material aluminum alloy constituting the pellicle frame of the present invention, the balance composition is basically composed of Al (aluminum) and inevitable impurities. However, the inevitable impurities are allowed to contain V, Zn, or other elements as long as the above characteristics are not impaired. More specifically, the content up to V: 0.3% or less and Zn: 0.5% or less is allowed.

  For example, from the viewpoint of recycling, not only high-purity Al ingots but also 5000 series alloys, other Al alloy scrap materials, low-purity Al ingots, etc. are used as melting raw materials as melting materials. In the case of melting, Fe, Si and the above elements are necessarily contained. Further, reducing these elements to, for example, below the detection limit itself increases the cost, and practically it is necessary to allow a certain amount of inclusion. For this reason, in the present invention, as described above, these impurity elements are allowed to be contained in an amount that does not inhibit the intended effect of the present invention.

(Mg: over 3.5% and up to 5.5%)
Mg is an essential element that imparts strength to the aluminum alloy by solid solution strengthening. If the Mg content is less than 3.5%, the strength and rigidity of the enlarged pellicle frame having a maximum side length of 1200 mm or more and a thickness of 5.0 to 7.0 mm cannot be ensured. On the other hand, when the Mg content exceeds 5.5%, the rolling workability during the production of the aluminum alloy plate (hot rolled plate) is impaired, and the workability when the aluminum alloy plate is cut into a pellicle frame. Damage.

(One or two of Ti and B)
In order to prevent cast cracking, improve hot-rolling workability, and workability such as cutting into a pellicle frame when manufacturing an aluminum alloy plate, one or two of Ti and B are included. When Ti and B are contained, an intermetallic compound such as an Al—Ti system or a Ti—B system is formed in the molten metal, and these serve as nuclei of solidified crystal grains to provide an ingot structure or a hot-rolled sheet structure (crystal Grain) can be made finer.

  If the contents of Ti and B are too small, these effects are not obtained. On the other hand, if the contents of Ti and B are too large, intermetallic compounds such as Al-Ti and Ti-B or Al-Ti And coarse intermetallic compounds such as Ti-B system, or some undissolved Ti or B is present in the matrix, which causes white point defects during the black alumite treatment. . Accordingly, one or two of Ti: 0.005 to 0.15% and B: 0.0005 to 0.05% are contained.

(Fe, Si)
In order to suppress crystallized substances, among impurity elements, particularly, Fe and Si contents that are easy to constitute a crystallized substance (intermetallic compound) with Al and that the content (mixing amount) tends to increase. Is regulated to Fe: 0.15% or less and Si: 0.10% or less. When the amount of Fe and Si is larger than this, the amount of crystallized substances such as Al-Fe type and Al-Fe-Si type is large, the size of the crystallized substance is coarsened, and the crystallized substance is in the present invention. It cannot be controlled within the specified range.

(Mn, Cr, Zr and Cu)
Mn, Cr, Zr and Cu are contained in a small amount and are effective for refining the crystal grains of the aluminum alloy structure. For this reason, it is possible to ensure workability such as prevention of cast cracking, improvement of hot-rolling workability, and cutting into a pellicle frame when manufacturing an aluminum alloy plate. When it is desired to exert such an effect, a total of 0.03 to 1.0% by mass of one or more selected from Mn, Cr, Zr and Cu is selectively contained. If the total content of Mn, Cr, Zr and Cu is less than 0.03%, there is no content effect. On the other hand, if the total content of these elements exceeds 1.0%, The resulting coarse crystallized product increases, and these cause white spot defects during the black alumite treatment. The total content of these elements does not exceed the upper limit. The upper limit of each element is as follows: Mn content is 0.3%, Cr content is 0.2%, and Zr content is 0.00. 2%, Cu content is 0.5%.

(Material aluminum alloy structure)
The structure of the material aluminum alloy that constitutes the pellicle frame of the present invention has a crystallized area ratio and maximum crystallized size in order to prevent white point defects during black anodizing treatment by the natural coloring method. And the occurrence of the white spot defect is suppressed.

(Area and size of crystallized product)
For this reason, in the structure observation with a scanning electron microscope (SEM) at 10,000 times the material aluminum alloy, the total area ratio in the visual field of the observed crystallized material is 5% or less, and the observed crystal The maximum crystallized product diameter is 3 μm or less in equivalent circle diameter. When the total area ratio of these crystallized substances exceeds 5% and is too large, and the maximum crystallized substance diameter exceeds 3 μm in terms of the equivalent circle diameter, during the black alumite treatment by the natural coloring method, Causes white spot defects.

  If the total area ratio of the observed crystallized matter in the visual field is 5% or less, and the maximum crystallized crystal diameter is 3 μm or less in terms of the equivalent circle diameter, the natural coloring method In the case of the black alumite treatment by, no white spot defect having an adverse effect occurs. Also, even if white spot defects occur, they are very small and dispersed, and are not optically detected as large crystallized substances, and the transfer wiring diagram is reflected by reflection of natural light or light from the light source. The degree of blur is reduced. Also, the probability of being confirmed as dust is greatly reduced.

In addition, the intermetallic compound (crystallized product) that causes white point defects in the black alumite treatment by the natural color development method is not limited to the above-described compounds such as Al-Fe and Al-Fe-Si. Similarly, Mg as the alloy element and intermetallic compounds with other elements also cause white spot defects. Examples of all intermetallic compounds are too many to be performed, but representative examples are intermetallic compounds such as Al—Cu—Mg, Al ₇ Cu ₂ Fe, Al ₂ CuMg, and MgZn ₂ .

  Therefore, in the present invention, the kind of crystallized matter that defines the area and the maximum size is not limited to intermetallic compounds such as Al-Fe type and Al-Fe-Si type. It is prescribed as. In other words, the area and the maximum size are defined as described above for all the crystallized substances observed in the visual field in the observation of the structure by SEM 10,000 times that of the aluminum alloy.

  In order to identify the crystallized substance in the aluminum alloy structure observed within the field of view, that is, an intermetallic compound, the same field of view as in the structure observation by a 10,000 times scanning electron microscope (SEM) is observed by X-ray diffraction. By analysis, it can be identified as a specific intermetallic compound, and is defined as the above-mentioned area and maximum size. Note that the area and maximum size of these crystallized substances can be measured by image analysis processing in the SEM visual field.

(Crystal grain size)
As explained in the section of the aluminum alloy composition, the material aluminum alloy constituting the pellicle frame of the present invention is a process such as prevention of casting cracking, improvement of hot-rolling workability and cutting into a pellicle frame when manufacturing an aluminum alloy plate. In order to ensure the properties, it is preferable to refine the crystal grain size in the aluminum alloy structure. The standard for refining the crystal grain size is preferably 25 μm or less as the average crystal grain size.

  The crystal grain size referred to in the present invention is the maximum diameter of the crystal grains in the rolling direction in the longitudinal section (perpendicular section in the sheet thickness direction) in the rolling direction (sheet longitudinal direction) in the case of hot-rolled sheets. If so, the maximum diameter of crystal grains in the longitudinal direction of the plate in the longitudinal direction (perpendicular cross section in the thickness direction) in the casting direction (the longitudinal direction of the plate). Here, the measurement location of the aluminum alloy (plate) is measured at a depth portion of the plate thickness direction 1/4 of an arbitrary location of the plate, and these measurement results are averaged.

  These average crystal grain sizes are measured and analyzed by SEM (Scanning Electron Microscope) -EBSP (Electron Diffraction) “Electron Back Scattering Pattern” and EBSD “Electron Back Scattering Diffraction”. These crystal analyzes use a crystal analysis method based on an electronic channeling pattern method (ECP method). And the maximum diameter of each crystal grain of the said direction observed in the predetermined | prescribed measurement area | region in an aluminum alloy structure | tissue is each measured, and the average value of the obtained result is calculated and calculated | required.

  More specifically, a plurality of sampled plate cross-section sample surfaces from each part of the above-mentioned aluminum alloy are mechanically polished, and about 0.25 mm from the sample surface is scraped off by mechanical polishing, and further subjected to buffing and electropolishing. Prepare a sample adjusted. The measurement site is the sample polishing surface, the measurement area of the sample is 1000 μm × 1000 μm, and the measurement step interval is 3 μm, for example.

  For example, SEM (JEOLJSM5410) manufactured by JEOL Ltd. is used as the SEM apparatus, and for example, EBSP: manufactured by TSL (OIM) is used as the EBSP measurement / analysis system. For the measurement of the area and size of the crystallized matter, the SEM apparatus and the sample measurement conditions may be the same as the crystal grain size measurement.

(Manufacture of aluminum alloy material)
The material aluminum alloy (plate, plate material) constituting the pellicle frame of the present invention is prepared by melting a molten metal having the above-described aluminum alloy composition by a conventional method, casting the ingot, and after this homogenization heat treatment, By hot rolling at a predetermined rolling rate, it can be preferably manufactured as a plate having a thickness of 5.0 to 7.0 mm as a pellicle frame. The manufactured material aluminum alloy sheet is subjected to a tempering treatment such as an annealing treatment as it is, as necessary.

  In this casting, it is preferable to use a DC casting method or a continuous casting method such as a twin roll in that the molten metal is rapidly cooled to crystallize small crystals and the crystal grains become finer. With a continuous casting method such as this twin roll, a thin slab having a thickness of 5.0 to 7.0 mm can be cast, and a homogenization heat treatment step and a thin plate hot rolling step can be omitted.

  Homogenization heat treatment is 450 to 550 ° C as a guide. If the homogenization heat treatment temperature is too low, homogenization will be insufficient. Further, in the case of hot rolling following this homogenization heat treatment, the hot rolling finish temperature becomes low, and the hot rolled sheet structure cannot be a recrystallized grain structure. It becomes a mixed grain structure with the crystal grain structure, and the crystal grain size cannot be refined. On the other hand, it is not necessary to make the homogenization heat treatment temperature higher than 550 ° C., and burning tends to occur.

  The end temperature in the case of hot rolling is preferably set to 300 ° C. or higher in order to refine the crystal grain size as a recrystallized grain structure. When the hot rolling end temperature is less than 300 ° C., as described above, a mixed grain structure is formed and the crystal grain size cannot be refined.

  In order to obtain an integrated frame shape having a maximum length of one side of 1200 mm or more and a thickness of 5.0 to 7.0 mm without any joint between the sides as the enlarged pellicle frame Thus, it is preferable that the material aluminum alloy is a hot-rolled sheet or a thin slab formed by a continuous casting method. In addition, as a raw material aluminum alloy plate, a thick plate having such a thickness cannot be produced by cold rolling as in Patent Document 5 because the capacity of the rolling mill is exceeded.

(Pellicle frame production)
As for these raw material aluminum alloys, hot-rolled sheets or thin slabs produced by a continuous casting method are processed such that the central portion of the plate is removed in a rectangular shape while the remaining peripheral edge is processed into a rectangular frame shape. In other words, the four sides that make up a rectangle are produced by subjecting a pellicle frame, which is an integrated rectangular frame that has no joints between adjacent sides, to machining such as cutting, punching, grinding, and polishing. Is done. At this time, the enlarged pellicle frame preferably has a maximum length of one side of 1200 mm or more and a thickness of 5.0 to 7.0 mm.

(Blackening treatment)
In this way, the material aluminum alloy produced in the shape of the pellicle frame is a black anodized film by the natural coloring method, especially after the aluminum alloy surface that becomes the edge of the pellicle frame body is roughened to a satin finish It is preferable that only is provided. Here, in order to make the surface black anodized so as not to reflect natural light or light from the light source as much as possible, the surface of the aluminum alloy is shot blasted, sandblasted, or roughened rather than the surface of the aluminum alloy being a mirror surface. It is preferable that the surface is finely roughened to a satin finish (satin finish) by a known mechanical roughening treatment such as skin pass rolling using a roll that has been turned into a roll. Note that, as usual, a series of surface treatments for roughening and blackening is performed not only on a part of the surface serving as the edge surface but also on the entire surface of the aluminum alloy.

  The natural color development in the black alumite treatment by the natural color development method is one that develops color and becomes darker as the anodic oxide film grows. Generally, by a known treatment method such as an alloy color development method or an electrolytic coloration method. Done. In the former alloy coloring method, an alloy element of an aluminum alloy is a main coloring factor. For example, in the process of anodizing in sulfuric acid, an alloy component is eluted as an intermetallic compound in anodized anodized black anodized. A film (layer) can be formed. The latter electrolytic coloring method is, for example, a method of coloring using an electrolytic solution based on an organic acid such as sulfonic acid or dicarboxylic acid, and a black alumite film (layer) can be formed on the surface of the aluminum material. it can. Here, in the process of anodizing in sulfuric acid by the alloy coloring method, even if the alloy component is eluted into the alumite as an intermetallic compound, the film defect such as the white defect does not occur.

  As described above, the material subjected to the black alumite treatment by the natural coloring method has light resistance to short wavelength light such as excimer laser light and far ultraviolet light. For this reason, even if it irradiates with such a short wavelength light, it does not discolor by degradation, an alumite layer is destroyed, and it does not generate dust. In addition, the anodized layer formed by this method is flat and has a very small and dense hole, so that no foreign matter enters the hole and there is little possibility of dust generation during handling of the pellicle. It can be suitably used as the inner surface of the frame. The 5000 series aluminum alloy according to the present invention having the composition described above can form a good black alumite film on the surface by black anodizing treatment by a natural coloring method after suppressing the crystallization. it can. As a result, the pellicle frame of the present invention can satisfy the dust-proof property, which is a basic characteristic of the pellicle frame.

  On the other hand, a surface that forms a porous alumite layer on the surface of the aluminum alloy material, anodizes with sulfuric acid solution (alumite treatment), and then adsorbs black organic dye into the pores to blacken it. There is also a processing method. However, in recent years, there has been a demand for miniaturization of the line width of integrated circuits, and therefore it is desired to use an exposure light source with an extremely short wavelength. However, when such a short wavelength excimer laser is used for a long time, the light resistance of the organic dye is insufficient, so in the black organic dye system, the inner surface of the pellicle frame is discolored, There is also a risk that the oxide film will be destroyed and generate dust.

(Manufacture of pellicle)
For example, a method for manufacturing a pellicle for lithography is performed by a known method disclosed in Patent Documents 1 to 3 and the like. That is, nitrocellulose, cellulose acetate, fluorine-based polymer, etc. that transmit light used for exposure well are appropriately selected, and these are diluted in a solvent, applied on a substrate, heated at a temperature of 200 ° C. or lower, and the solvent. First, a transparent pellicle film is obtained. Thereafter, the obtained pellicle film is adhered and fixed to the temporary frame body, peeled off from the substrate, and then a good solvent is applied to the blackened pellicle frame, applied, and stretched, and then the temporary frame body is formed. Remove. Then, the pellicle film on the upper surface of the pellicle frame is air-dried and bonded. At this time, the pellicle film may be adhered with an adhesive such as an acrylic resin, an epoxy resin, or a fluororesin, and further, a polybutene resin, a polyvinyl acetate resin, an acrylic resin is attached to the lower surface of the pellicle frame for mounting on the exposure original plate. In addition, an adhesive layer made of silicone resin or the like, and a reticle adhesive protecting liner for the purpose of protecting the adhesive layer may be provided.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

  Next, examples of the present invention will be described. A 5000 series aluminum alloy having the compositions of A to E (invention example) and F to H (comparative example) shown in Table 1 was melted to cast an ingot. The ingot was hot rolled after 12 hours (h) homogenization heat treatment in common at each temperature shown in Table 2 to produce a 6.0 mm thick plate. In the aluminum alloy structure of each example, the area ratio of the crystallized product and the maximum crystallized product size were controlled by the temperature of the homogenization heat treatment together with the average crystal grain size.

  From the manufactured aluminum alloy hot-rolled sheet, a test piece was cut out as it was (in a non-tempered state), and each test and evaluation were performed. These results are shown in Table 2.

(Organization)
Using the SEM, SEM-EBSP and EBSD, and the measurement conditions described above, the microstructure of the hot-rolled sheet test piece was observed, and the area ratio of the crystallized material and the maximum crystallized material size (circle) Equivalent diameter) and average crystals were measured.

(Mechanical properties)
The test piece was subjected to a tensile test, and tensile strength (MPa) and 0.2% yield strength (MPa) were measured. As test conditions, No. 5 test piece (25 mm × 50 mmGL × sheet thickness) of JISZ2201 perpendicular to the rolling direction was sampled from the hot-rolled sheet, and a tensile test was performed. The tensile test was conducted at room temperature of 20 ° C. based on JISZ2241 (1980) (metal material tensile test method). The crosshead speed was 5 mm / min, and the test was performed at a constant speed until the test piece broke.

(Pellicle frame evaluation)
The produced aluminum alloy hot-rolled sheet is directly subjected to tempering treatment such as annealing (as a non-tempered hot-rolled sheet), and the central part of the plate is deleted and the peripheral part is a rectangular frame. As a large pellicle frame. The large size pellicle frame rectangular frame had an outside dimension of 1400 mm × 1700 mm square, an edge surface (plane) width of 7.0 mm, and a thickness of 6.0 mm.

After the surface of this aluminum alloy pellicle frame was cleaned, glass beads were used, and surface treatment was performed for 30 seconds with a sandblasting apparatus having a discharge pressure of 2.0 kg / cm ² to roughen the surface into a satin finish.

  Next, after treating and washing in a caustic soda treatment bath at room temperature for 10 seconds, anodizing in sulfuric acid by an alloy coloring method, and elution of alloy components such as Mg as an intermetallic compound in alumite An alumite film (layer) was formed. The anodizing treatment was performed at a conversion voltage of 15 V (1.5 A) in a 15% aqueous sulfuric acid solution at a liquid temperature of 25 ° C.

  About the pellicle frame created by blackening these surfaces, all the one rectangular frame surface that becomes the edge of the pellicle frame under a condenser lamp with an illuminance of 300,000 lux was measured with a 10 × stereo microscope. The number of the above-mentioned white spots (defects) accompanied by light reflection was observed in order in the longitudinal direction. This is an inspection that is at least 10 times more severe than visual observation in terms of the accuracy of finding a white spot having a size that has a substantial adverse effect. The results are shown in Table 2.

  In addition, for the pellicle frame created by blackening the surface, the bending rigidity was evaluated in a simulated manner in order to evaluate durability such as dimensional accuracy and flatness during repeated use. In the bending stiffness test, both ends were placed on a rigid base and only the both ends were supported entirely, while the center length of 1000 mm was not supported. In this state, a load of 100 MPa was repeatedly applied to the central portion (both sides arranged in parallel) of the frame body for 1 minute each by a rigid body having a length over the entire width direction of the frame body. Then, when this load was applied 100 times, the amount of deflection of the central portion of the pellicle frame that was permanently deformed was measured using a surface plate and a gap gauge.

  The measured deflection amount of 50 μm or less was evaluated as “◯” because even a large pellicle frame has high durability such as rigidity, dimensional accuracy and flatness during repeated use. Also, the amount of deflection exceeding 50 μm and not more than 100 μm was evaluated as Δ because it could not be used with a small pellicle frame, although it could not be used with a large pellicle frame. Moreover, the case where the amount of deflection exceeded 100 μm was evaluated as x because the rigidity was insufficient and it could not be used for the pellicle frame. The results are also shown in Table 2.

  As can be seen from the results of Tables 1 and 2, the pellicle frames of Invention Examples 1 to 5 that are within the composition range of the aluminum alloy component of the present invention and satisfy the structural requirements of the crystallized product have the number of white spot defects described above. It is suppressed and has excellent rigidity.

  On the other hand, among the pellicle frames obtained by Comparative Examples 6 to 11, Comparative Examples 6 to 8 are within the aluminum alloy component composition range of the present invention, but the homogenization heat treatment temperature is too low, and the crystallographic structure requirements. The number of white point defects described above is large. Also, the average crystal grain is large and the rigidity is inferior.

  In Comparative Examples 9 and 10, the Mg content is too low, the homogenization heat treatment temperature is appropriate, the structure requirement of the crystallized material is satisfied, and the number of white spot defects described above is small, but the rigidity is poor.

  In Comparative Example 11, although the Mg content is too large and the homogenization heat treatment temperature is appropriate, the number of white spot defects described above is large. Also, the average crystal grain is large and the rigidity is inferior.

  From the above results, even if the present invention is a large pellicle frame, it is excellent in suppressing white spots in the pellicle frame, excellent in rigidity, and has high durability such as dimensional accuracy and flatness during repeated use. The effect is supported.

  According to the present invention, the maximum length of one side is 1200 mm or more, and the thickness is 5.0 to 7.0 mm. Strength and rigidity can be secured and durability can be improved. Moreover, this effect can be achieved while suppressing the occurrence of white spots in the pellicle frame. For this reason, it is optimally used for a pellicle frame having a large area for increasing the efficiency of a circuit pattern transfer operation with a large area and a fine pattern.

Claims (5)

  A pellicle frame made of an aluminum alloy, and this material aluminum alloy contains, in mass%, Mg: more than 3.5% and 5.5% or less, and Ti: 0.005 to 0.15%, B A composition containing 0.0005 to 0.05% of one or two elements, Fe: 0.15% or less, Si: 0.10% or less, and the balance of Al and inevitable impurities. In addition, the total area ratio in the visual field of the observed crystallized substance is 5% or less in the observation of the structure of this aluminum alloy by a scanning electron microscope at a magnification of 10,000 times. A pellicle frame characterized by having a structure in which the diameter of the crystallized material is a circle equivalent diameter of 3 μm or less.   2. The pellicle frame according to claim 1, wherein the material aluminum alloy of the pellicle frame further includes 0.03 to 1.0% by mass in total of one or more selected from Mn, Cr, Zr, and Cu. .   The pellicle frame is processed by removing a central portion of the material aluminum alloy plate, and has an integrated rectangular frame shape with no joints between the sides. Pellicle frame.   The pellicle frame according to any one of claims 1 to 3, wherein the surface of the aluminum alloy material of the pellicle frame is roughened to a satin finish, and only a black anodized film by a natural color development method is provided.   The pellicle frame according to any one of claims 1 to 4, wherein a maximum length of one side of the pellicle frame is 1200 mm or more and a thickness is 5.0 to 7.0 mm.