JP5865145B2 - Concave micropattern forming method and concave micropattern substrate - Google Patents

Description

The present invention is a concave fine pattern including a microlens, and in particular, a concave pattern having an inclined surface is formed on the substrate surface, and then the concave pattern portion is embedded (filled) to flatten the substrate surface. The present invention belongs to the technical field of a concave fine pattern forming method for forming a concave fine pattern forming substrate having a shape to be flattened. Further, the present invention belongs to the technical field of a concave fine pattern substrate, a microlens, and a microlens array formed by using the method. In the present invention, the concave fine pattern refers to a fine pattern including a concave portion.

In an electro-optical device such as a projector, in each pixel of a liquid crystal device such as a liquid crystal panel used in the device, an area where light that can actually contribute to display is transmitted or reflected is various wirings, electronic elements, etc. Is essentially limited by the presence of. Therefore, conventionally, for example, in a liquid crystal device such as a liquid crystal panel, a microlens array in which convex microlenses and concave microlenses corresponding to each pixel are arranged at predetermined positions is formed on a counter substrate of a liquid crystal layer, A lens array substrate is attached to a counter substrate, and the amount of light incident on the liquid crystal layer is collected in units of pixels. By using the microlens array in the electro-optical device, the luminous flux is guided into the aperture region of each pixel, so that bright display is possible. The technique for forming such a microlens array is required to improve the lens shape accuracy and the efficiency of the forming process by using a technique for miniaturization. The fields of use of microlenses and microlens arrays will expand in the future, including fields that deal with the miniaturization of electro-optical devices and the improvement of light utilization efficiency.

As conventional techniques, various forming methods for forming a structure having a fine pattern in which microlenses having a fine structure such as a microlens are arrayed one-dimensionally or two-dimensionally have been proposed.

Patent Document 1 discloses a technique including a film forming process, a light patterning process, a light irradiation process, a heating process, and an etching process on a transparent substrate. For example, the film forming step is a step of forming a film having a uniform thickness with a heat-deformable photosensitive material on a transparent substrate, and the optical patterning step is a pattern corresponding to each lens in the microlens array and its arrangement. In accordance with the above, the step of photopatterning a film having a uniform thickness with a heat-deformable photosensitive material and the light irradiation step are steps in which light irradiation is performed on the entire surface of the photopatterned film. The type of light to be irradiated (wavelength region and intensity) is determined by the extent to which linear molecules are cut according to the material and form of the film. The heating step is a step of heating the light-irradiated film to a heat deformation temperature to form an array arrangement of the photosensitive material having a smooth convex shape by the heat deformability and surface tension of the photosensitive material. In the etching step, the surface on which the array array is formed is dry-etched, and the convex array array is engraved on the substrate to form a desired refractive index surface shape and the array array state on the substrate. It is a technology with a process.

In Patent Document 2, a film forming step for forming a film having a uniform thickness on a transparent substrate with a heat-deformable photosensitive material, and a pattern corresponding to each lens in the formed microlens array and the arrangement thereof are performed. A process of photopatterning the film, and a heating process of heating the film to a thermal deformation temperature to form an array of photosensitive materials having a smooth convex shape by the thermal deformation and surface tension of the photosensitive material. And an etching process for forming a desired refractive index surface shape and the array arrangement state on the substrate by performing dry etching and engraving the array arrangement of the convex shape on the substrate. . In Patent Document 1, light irradiation is performed on the entire surface of the photo-patterned film, and a light irradiation process is performed in order to cut linear molecules in the film by light energy. The light irradiation step for the patterned photosensitive material is omitted. It is conceivable that the same effect as the light irradiation of Patent Document 1 can be obtained by optical patterning.

Patent Document 3 discloses a technique for creating a biconvex or meniscus microlens or microlens array using a laser CVD method. This micro-lens formation method by the laser CVD method has a feature that the refractive index range can be widened by selecting a material gas, the lens diameter can be reduced by narrowing the laser beam, and it is not necessary to go through a mask process. is there. As a specific method, a laser beam split by a beam splitter is guided to both front and back surfaces of a substrate disposed in a CVD cell, and both front and back surfaces of the substrate are processed simultaneously, and a biconvex lens is formed on the front and back surfaces of the substrate. Is disclosed. And an optical system for directing one beam divided by a beam splitter that divides the laser light source toward one surface of the substrate and directing the other beam toward multiple surfaces of the substrate, and a condensing lens corresponding to each beam. There is disclosed a technique relating to a microlens forming apparatus that is arranged and supports the substrate on a position-adjustable substrate holder in a CVD cell. A technology to form a meniscus lens by forming a concave lens on the right side of the substrate fixed to the substrate holder and forming a convex lens on the left side of the substrate, and a lens equivalent to the pitch of the microlens array. Techniques for forming arrays are disclosed. This technique is a technique in which a laser beam is directly guided to the front and back surfaces of the substrate and processed, and there is no need to go through a mask formation process for the substrate surface.

A pattern such as a microlens having a fine pattern is formed by the method for forming a fine pattern according to Patent Documents 1 to 3, and then the surface of the substrate on which the fine pattern is formed is covered with a buried layer made of a film forming material as a surface layer. By flattening and further planarizing by laminating a flattening layer on the surface layer, it is possible to form a product having a shape in which the entire substrate surface is flattened (flattened).

In Patent Document 1, a technique including a film forming process for forming a film having a uniform thickness on a substrate with a thermally deformable photosensitive material, a photo patterning process, a light irradiation process, a heating process, and an etching process. Is disclosed. The technique of Patent Document 1 has a problem that it takes time and man-hours for manufacturing because a fine pattern forming process is performed through a mask layer and thus involves many complicated processes.

Patent Document 2 discloses a technique including a film forming process for forming a film having a uniform thickness on a substrate using a heat-deformable photosensitive material, a process for photopatterning, a heating process, and an etching process. Has been. In Patent Document 1, light irradiation is performed on the entire surface of the photo-patterned film, and a light irradiation process is performed in order to cut linear molecules in the film by light energy. The light irradiation step for the patterned photosensitive material is omitted. It is conceivable that the same effect can be obtained by optical patterning. The technique of Patent Document 2 has a problem that it takes a lot of time and man-hours for manufacturing because the process of forming a fine pattern is complicated and many processes are performed through a mask layer.

Patent Document 3 discloses a technique for creating a biconvex or meniscus microlens or microlens array using a laser CVD method. This CVD microlens formation method has features such that the refractive index range can be widened by selecting a material gas, the lens diameter can be reduced by narrowing the laser beam, and it is not necessary to go through a mask process. . The technique of Patent Document 3 is a technique in which a laser beam is guided directly to the front and back surfaces of the substrate and does not require a mask formation process for the substrate surface.

In the technique of Patent Document 3, the fine pattern forming process by the laser CVD method can be directly formed on the substrate surface without performing the mask layer, but the fabrication using the drawing method using the laser beam is possible. Therefore, there is a problem that it may be unsuitable for manufacturing a large number of substrates having fine patterns.

As described above, the techniques of Patent Documents 1 and 2 are contents for manufacturing a microlens through a mask layer, and the techniques of Patent Documents 1 and 2 are mask layers made of a photosensitive material on a transparent material substrate. The mask layer is formed by exposing and patterning a fine pattern by light irradiation, and the fine pattern is heated to form a desired microlens or microlens array. This is a technique for forming a microlens and a microlens array through a process of forming a mask layer and engraving the lens shape of the mask layer on a transparent material substrate. There was a problem. The technique of Patent Document 3 is a technique for directly producing a microlens on a transparent material substrate without using a mask layer. In the technique of Patent Document 3, the fine pattern forming process by the laser CVD method can be directly formed on the substrate surface without performing the mask layer, but the fabrication using the drawing method using the laser beam is possible. Therefore, there is a problem that it may be unsuitable for manufacturing a large number of substrates having fine patterns.

Although the prior art which concerns on patent documents 1-3 is the technique applied to the formation method of a micro lens, there exists a problem that it is inferior in production efficiency, requiring a long process and many process steps in the case of fine pattern formation. is there. The present inventor has a technique for forming a concave fine pattern including a concave portion for forming a microlens or the like on a substrate via a mask layer, and then filling the substrate with any layer of a film-forming substance (filling). A technique for fabricating a substrate having a structure in which a film-forming substance is embedded in the concave fine pattern was studied through the steps of forming a film, providing a surface layer on the substrate surface, and further planarizing the surface layer. And it came to this invention which concerns on the structure and formation method of a board | substrate which has a concave fine pattern containing the concave structure applicable to a microlens.

The inventor initially studied a method of forming a concave fine pattern in the steps of FIGS. 4A to 4F as shown in the flow of FIG. In the figure, the cross-sectional parts of the constituent members are simply expressed. As shown in FIG. 4A, for example, a mask layer made of a photosensitive material such as a photoresist is laminated on the entire surface of a substrate 11 made of a transparent material such as optical glass or quartz, and a mask having a desired shape is formed. The pattern is formed by photolithography or imprinting, and then finely formed as an inverted trapezoidal mask layer 12 having different dimensions on the upper surface side and lower surface side of the mask layer by an oblique exposure method as described in Patent Document 4. Form a pattern. Although the mask layer formed in FIG. 3 of Patent Document 4 has a trapezoidal mask shape, an inverted trapezoidal fine pattern forming mask layer can be formed by arranging the light shielding mask member at the time of exposure. . Next, as shown in FIG. 4B, a first film-forming material is formed on the surface of the substrate 11 by a vacuum film-forming apparatus, and a first film-forming layer 14 made of the first material is formed. . At this time, a concave fine pattern is formed on the first film formation layer 14 by the inverted trapezoidal mask layer 12. As the film forming material is formed on the surface of the substrate 11 along the shape of the mask layer 12, concave portions having different thickness distributions are formed. Next, as shown in FIG. 4C, the mask layer 12 is removed from the surface of the substrate 11 using a photosensitive material remover or the like, whereby a concave fine pattern 13 is formed in the first film formation layer 14. As shown in FIG. 4D, a second mask layer 15 having an opening in the concave fine pattern 13 is formed using a photosensitive material such as a photoresist. Further, a second film-forming material is formed on the surface of the substrate 11 so as to embed the opening through the opening of the second mask layer 15, so that the second film-forming material is formed. A film layer 16 is formed. The technique of forming the second film formation layer through the opening of the second mask layer 15 is formed in the opening of the mask layer 15 made of a photosensitive material as shown in FIG. It is a technology that can be formed into a film. As shown in FIG. 4E, the second mask layer 15 is removed from the surface of the substrate 11 by using a photosensitive material remover or the like, so that the second concave layer of the concave micropattern formed in FIG. The concave fine pattern 13 in which the film forming material is embedded is formed. Next, as shown in FIG. 4F, a second or third film forming material is formed on the surface of the substrate 11. By adding a film forming process for flattening the surface of the substrate 11, the substrate 11 on which the concave fine pattern 13 is formed is formed.

The concave micropattern 13 can act as a concave microlens with respect to a light beam incident on the substrate from the back side where the micropattern is formed by making the substrate 11 a transparent substrate made of a transparent material. Yes, each concave portion is arranged as a concave lens at a desired pitch, and can be used as a microlens array. Depending on the type of wavelength of the light beam used, a substrate using a material (for example, Si) other than visible light, for example, transparent to infrared light may be used.

In the above-described technique at the examination stage according to the present invention, a mask pattern having a desired shape is formed by photolithography or imprint on a film forming member on a substrate on which a shape such as a predetermined recess is to be created, and the mask shape is used. In addition, there is a need for a film forming process using vacuum film forming technology, a process of removing a mask substrate from a vacuum film forming apparatus, removing a mask layer, and then performing a film forming process again using a vacuum film forming apparatus to fill a recess. There is a problem that continuous film formation in the same chamber cannot be performed, and the number of steps increases, which increases the cost of manufacturing.

Japanese Patent Laid-Open No. 06-250002 Japanese Patent Laid-Open No. 06-194502 Japanese Patent Laid-Open No. 03-162578 JP 2000-30607 A Japanese Patent Laid-Open No. 05-047761

The present invention has been made under such circumstances, and such pattern formation + embedding (hole filling) / planarization can be easily performed by a single continuous film forming process in the chamber of the same vacuum film forming apparatus. An object of the present invention is to provide a process for forming a substrate having a concave fine pattern.

In order to achieve the above object, the present invention provides a transparent substrate made of a transparent material and a first opening corresponding to a fine pattern formed on the transparent substrate, as described in claim 1. Preparing a first mask having a first closing portion, a second opening having a pattern in which the first opening portion and the closing portion are reversed, and a second mask having a second closing portion. And placing the transparent substrate and the mask in a vacuum film forming apparatus with the surface of the transparent substrate and the first mask spaced apart from each other;
A first film forming step of forming a first film forming material in a vacuum form from the side facing the transparent substrate and the mask in the vacuum film forming apparatus, and a first film forming step of the transparent substrate by the first film forming step. Forming a concave portion of the first film-forming material layer immediately below the first closing portion of the first mask, removing the first mask,
The transparent substrate and the second mask are spaced apart from the surface of the transparent substrate in the vacuum film-forming apparatus, and the second opening is aligned with the recess of the first film-forming material layer. A step of placing a mask, a step of vacuum-depositing a second film-forming material from the side facing the mask and the transparent substrate in the vacuum film-forming apparatus, and a recess of the first film-forming material layer Is a method of forming a concave fine pattern, which includes a step of embedding a second film-forming substance and a step of removing the second mask.

In the present invention, when a film is formed in an apparatus chamber using a vacuum film forming apparatus such as a vacuum deposition apparatus, a vacuum sputtering apparatus, or a directional CVD apparatus, the substrate is separated from the film forming surface on the film forming surface. By installing an arbitrary mask, the film formation material is formed on the surface of the substrate to be processed using the fact that the film formation material wraps around the substrate surface at the lower part of the mask via the pattern opening of the mask. This is based on a technique for forming a concave concave fine pattern having an inclined surface. In order to generate the wraparound phenomenon due to the mask of the film forming substance, use a vacuum film forming apparatus configured to deposit the film forming material on the substrate surface side and in a direction parallel to the normal line of the substrate surface. is necessary. In addition, in order to form a plurality of film forming materials, it is necessary to change the target for supplying the film forming material in the vacuum film forming apparatus.

As shown in FIGS. 1 (a), (b), (c), (d), (e), and (f), the forming method of the present invention uses a first mask on a portion where a concave fine pattern is to be formed. The film is formed in a state of being separated from the substrate to be processed. Then, a recess having a different film thickness of the film forming material is generated from directly under the first mask to the opening of the first mask. A concave fine pattern is formed using the film thickness distribution of the recesses having different film thicknesses. The first mask is removed, and then the concave fine pattern is embedded (filled). For this embedding, the film forming material target of the vacuum film forming apparatus is changed according to the type of film forming material used for the embedding, and the film forming conditions are changed and adjusted at the same time. This target change and film formation condition change adjustment can be performed from outside the vacuum film formation apparatus without removing the substrate to be processed. For this embedding, a second mask whose opening and closing pattern is opposite to the first mask at the time of forming the concave fine pattern is spaced from the surface of the substrate to be processed, and the first film formation is performed. The transparent substrate and the mask layer are placed so that the second opening is aligned with the concave portion of the material layer, and the second film forming material is formed. Thereafter, the mask used for the embedding is removed, and a film having an arbitrary thickness is formed on the entire surface of the embedding substrate, thereby realizing pattern formation + embedding (hole filling) / planarization.

The first mask and the second mask are removed by using a mask moving positioning device provided in the vacuum film forming apparatus, and in the vacuum film forming apparatus, during the series of processes, the first mask and the second mask are removed. The mask can be moved from the substrate to be processed. A known optical pattern alignment apparatus can be used for alignment between the concave fine pattern on the substrate to be processed and the opening of the second mask.

For the first mask and the second mask, for example, a known anisotropic dry etching technique can be used to process a mask having an opening of 5 μm to 7 μm with respect to the mask plate thickness of 500 μm of this embodiment. is there. Further, it is effective that the mask material is a material having the same thermal expansion coefficient as the material of the substrate to be processed.

According to the present invention, pattern formation + embedding (hole filling) / planarization can be easily realized by a single film forming process. In the pattern formation flow described above, by exchanging the first mask and the second mask in the chamber, it is basically possible to form a continuous process called “vacuum film formation”. There is no need to perform multiple processes. Specifically, since a plurality of facilities are not required and a so-called “process flow” process does not occur, man-hours related to the forming process can be reduced, and effects such as labor cost reduction can be achieved. In the conventional technology, it is necessary to flow a very long process, and it is easy to produce a concave fine pattern substrate that requires a long time and a large number of man-hours and is expensive. It becomes possible.

1 (a), (b), (c), (d), (e), and (f) are diagrams showing the flow of each process of the concave fine pattern forming method according to the present invention. It is a figure which shows the wraparound to the to-be-processed substrate surface with respect to the 1st mask of the 1st film-forming substance which concerns on this invention. It is a figure which shows the surroundings to the recessed part of the to-be-processed substrate with respect to the 2nd mask of the 2nd film-forming substance concerning this invention, and embedding of a recessed part. 4 (a), (b), (c), (d), (e), and (f) are diagrams showing respective processes of the concave fine pattern forming method according to the technique at the examination stage according to the present invention. .

FIG. 1 shows a flow of a forming method according to one embodiment of the present invention. A substrate 1 in FIG. 1 is a substrate to be processed which is made of a transparent material such as optical glass or quartz similar to the technique in the examination stage of the present invention. Moreover, the board | substrate using materials (for example, Si) transparent with respect to infrared rays other than visible light, for example according to the kind of wavelength of the light beam used may be sufficient. In FIG. 1A, a mask having a pattern closing portion width of 7 μm and a thickness of 500 μm is prepared as a first mask 2 on a substrate 1, and the gap between the surface of the substrate 1 and the lower surface of the first mask 2 is set to 100 μm. A tantalum oxide ( Ta ₂ O ₅ ) layer, which is a first film forming material, is formed to be 1 μm apart from each other. Next, as shown in FIG. 1B, the concave fine pattern 3 of the tantalum oxide layer 4 is formed on the substrate 1. Subsequently, as shown in FIG. 1C, a second mask having a pattern opening of 5 μm and a thickness of 500 μm is formed immediately above the concave fine pattern 3 of the tantalum oxide layer 4 and the second surface layer 4 of the substrate 1. The gap with the lower surface of the mask 5 is spaced apart by 100 μm, and the center of each of the second opening and the concave fine pattern 3 which is the concave portion is aligned with the concave portion 3 of the tantalum oxide layer 4 of the first film forming material. Thus, by placing the substrate 1 and the second mask layer 5, a silicon oxide (SiO ₂ ) layer 6, which is a second film forming material, was formed to a thickness of 1 μm. Next, as shown in FIG. 1 (d), to form a fine pattern with embedded silicon oxide (SiO ₂₎ in a concave micro pattern 3 as a recess. Then, as shown in FIG.1 (e), the 2nd mask was removed and the concave fine pattern board | substrate 1 with which the surface of the board | substrate 1 was planarized was formed.

By taking out the surface of the substrate 1 from the vacuum film forming apparatus and performing so-called chemical mechanical polishing (CMP), the surface of the substrate 1 can be made into a mirror plane. The CMP process is a technique for smoothly mirror-finishing the surface of a substrate such as optical glass, and is generally performed in a CMP processing apparatus using a polishing cloth, an abrasive, and a polishing liquid having a chemical etching action. is there. Next, as shown in FIG. 1F, a silicon oxide (SiO ₂ ) layer 7 having a thickness of 3 μm was formed. Through the above steps, a process of forming a buried (hole filling) layer with another film forming material on the concave fine pattern 3 as shown in FIG. It can be carried out by one continuous process in the chamber of the membrane apparatus. It implements suitably according to the required optical performance.

The present invention is a technique that utilizes the wraparound of a film forming material to a mask member placed in a position opposite to the film forming method of the film forming material in vacuum film formation. At a general pressure (1 Pa or less) in vacuum film formation, the average free process length of atoms of the film formation material is 3.7 cm or more, so the scale for so-called fine patterns (several μm to several tens of μm level) Since the order is different, it can be considered that the film-forming substance proceeds in a substantially straight line, so this wraparound phenomenon can be roughly estimated by the following logic.

In FIG. 2, when the thickness of the first mask 2 is a, the closed portion width dimension of the first mask 2 is b, and the gap between the substrate 1 to be processed and the mask 2 is c, the first film formation is performed. The wraparound range x of the layer can be roughly calculated as x = (b × c) / a. When the opening of the first mask 2 is sufficiently large, θ in FIG. 2 is about 45 °, and the wraparound range x is x when the film thickness of the first film formation layer 4 is t. = T has been found by experiments by the present inventors. From the contents of the above experiment, film formation was performed under the following conditions. (1) A mask 2 having a pattern closing portion width of 7 μm and a thickness of 500 μm is arranged on the substrate 1 with a gap of 100 μm from the substrate 1, and a tantalum oxide ( Ta ₂ O ₅ ) layer 4 is formed to a thickness of 1 μm. A concave fine pattern 3 was formed in a tantalum oxide layer ( Ta ₂ O ₅ ) 4 on the substrate 1. (2) Subsequently, the mask 2 is removed, and as shown in FIG. 3, a mask opening (indicated by d) 5 μm directly above the concave fine pattern 3 of the tantalum oxide ( Ta ₂ O ₅ ) layer 4, A second mask 5 having a thickness of 500 μm was spaced apart from the substrate 1 with a gap of 100 μm, and a silicon oxide (SiO ₂ ) layer 6 was formed to a thickness of 1 μm. Thereafter, the mask 5 was removed, and a silicon oxide (SiO ₂ ) layer 7 (shown in FIG. 1F) was formed to a thickness of 3 μm. By this step, the concave fine pattern 3 as shown in FIG. 1 (f) is filled (filled) with another film forming material to flatten the substrate, and the step of forming the substrate having the concave fine pattern is performed in the chamber of the same vacuum film forming apparatus. Thus, it can be carried out by one continuous process.

As described above, according to the fine pattern forming method of the present invention, it is possible to provide a substrate on which a fine pattern is formed with a simple configuration, and the microlens can be applied to an electro-optical device such as a liquid crystal projector. And can be applied to a microlens array.

1, 11 Substrate 12 First mask layer,
2 First mask 3, 13 Recessed fine pattern 4, 14 First film formation layer 15 Second mask layer 5 Second mask 6, 16 Second film formation layer 7, 17 Third film formation layer

Claims (10)

A step of preparing a transparent substrate made of a transparent material, a first mask having a first opening and a first closing portion corresponding to a fine pattern formed on the transparent substrate, and the first opening Preparing a second opening having a reverse pattern of the closing portion and a second mask having the second closing portion;
A step of placing the transparent substrate and the mask apart from the surface of the transparent substrate in the vacuum film forming apparatus, and facing the transparent substrate and the mask in the vacuum film forming apparatus; A first film-forming step of vacuum-depositing a first film-forming substance from the side to be performed;
A step of forming a concave portion of the first film-forming material layer immediately below the first closing portion of the first mask of the transparent substrate by the first film-forming step; and a step of removing the first mask ,
The transparent substrate and the second mask are spaced apart from the surface of the transparent substrate in the vacuum film-forming apparatus, and the second opening is aligned with the recess of the first film-forming material layer. Placing a mask layer, vacuum depositing a second film-forming material from the side facing the mask and the transparent substrate in the vacuum film-forming apparatus, and forming the first film-forming material layer A method for forming a concave fine pattern, comprising: embedding a concave portion with the second film-forming substance; and removing the second mask. The concave fine pattern forming method according to claim 1,
The second opening is aligned with the concave portion of the first film-forming material layer in a state where the second opening width of the second mask is narrower than the closing width of the first mask. A method for forming a concave fine pattern, comprising mounting a second mask and depositing a second film-forming material. The concave fine pattern forming method according to claim 1,
After the recess of the first film-forming material layer is filled with the second film-forming material and after the second mask layer is removed, the third film-forming material is vacuum-deposited on the transparent substrate surface. A method for forming a concave fine pattern, further comprising a step of forming a film in the apparatus.   2. The concave fine pattern forming method according to claim 1, wherein after the step of filling the concave portion of the first film-forming material layer with the second film-forming material, the second film-forming material is removed by chemical mechanical polishing. A method for forming a concave fine pattern, comprising: a flattening step of flattening the surface of the transparent substrate. In the concave fine pattern forming method according to claim 1 or 2,
A method for forming a concave fine pattern, wherein the substrate is made of various optical glasses, quartz, or various single crystals. In the concave fine pattern forming method according to claim 1 or 2,
The method for forming a concave fine pattern, wherein the first film forming material is a material transparent to light. In the concave fine pattern forming method according to claim 1 or 2,
The method for forming a concave fine pattern, wherein the second film forming material is a material transparent to light. In the concave fine pattern forming method according to claim 6,
The method for forming a concave fine pattern, wherein the first film forming material is tantalum oxide ( Ta ₂ O ₅ ). The concave fine pattern forming method according to claim 7,
The method for forming a concave fine pattern, wherein the second film-forming material is silicon oxide (SiO ₂ ). On the transparent substrate, a first film-forming layer, a concave fine pattern having a concave portion provided in the first film-forming layer, a second film-forming layer embedded in the concave part of the concave micro-pattern, A fine pattern substrate having a concave fine pattern provided on a second film formation layer .

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