WO2012172755A1 - Sheet, mold, and manufacturing method thereof - Google Patents

Abstract

The micropattern formation method disclosed in the present patent application involves: a step (A) in which an ultraviolet-curable resin composition with an oxygen inhibiting property is provided on the top surface of a support; a step (B) in which a master mold having a unit micropattern formed on the molding surface is pressed against the ultraviolet-curable resin composition so as to bring the molding surface into contact with the ultraviolet-curable resin composition; a step (C) in which at least the area of the ultraviolet-curable resin composition where the unit micropattern has been transferred is cured by irradiating the ultraviolet-curable resin composition with ultraviolet rays with the master mold being pressed in an oxygen-containing atmosphere; a step (D) in which the master mold is separated from the ultraviolet-curable resin composition; a step (E) in which a unit transfer step, which includes the steps (B), (C), and (D), is repeated for more than one time in each subsequent area which includes an uncured area other than the area where the unit micropattern has already been transferred to the ultraviolet-curable resin composition; and a step (F) in which uncured sections of the ultraviolet-curable resin composition are removed. In the step (E), the subsequent area is overlapped partially with the cured area. In the step (B) of the step (E), the unit micropattern of the master mold is substantially filled with the ultraviolet-curable resin composition.

Description

Sheet and mold and method for producing the same

The present application relates to a method for forming a fine pattern, a mold and a sheet formed using the method.

Recently, a fine pattern transfer process called nanoimprint lithography has been actively studied. In nanoimprint lithography, a substrate having a fine pattern is used as a mold, and the fine pattern is transferred onto a resin. For nanoimprint lithography, a thermal method and a UV method are known.

In the thermal method, a mold having a fine structure formed is pressed against a resin heated to a glass transition temperature or higher to transfer the fine structure to the resin. The thermal method is superior to the UV method in selecting the material to be transferred. On the other hand, since it is necessary to heat and cool the substrate and mold, the throughput is inferior to that of the UV method, and a large pressure is required, so that the deformation of the base material becomes large. For this reason, when it is desired to transfer the fine structure to a large area by step and repeat, the alignment accuracy is deteriorated, and it becomes difficult to form a fine pattern on the large area sheet.

The UV method irradiates the ultraviolet curable resin composition with ultraviolet rays while pressing a mold having a microstructure formed on the ultraviolet curable resin composition, thereby transferring the fine structure onto the resin. Although the selectivity of the material to be transferred is inferior to that of the thermal method, transfer at room temperature is possible, and it is not necessary to heat or cool the substrate or mold. For this reason, it is possible to improve the throughput as compared with the thermal method. Further, since a large pressure is not required at the time of transfer, deformation of the base material and thermal shrinkage of the material are suppressed, which is superior to the thermal method in terms of transfer accuracy and alignment accuracy. For this reason, research and development for forming a fine pattern using the UV method in particular are being actively performed among nanoimprint lithography techniques.

However, in the UV nanoimprint lithography technology, when the mold is pressed against the ultraviolet curable resin composition applied to the substrate, a part of the ultraviolet curable resin composition protrudes to the side of the mold to form a raised portion. . For this reason, when the ultraviolet curable resin composition is irradiated with ultraviolet rays in this state, the protruding bulge portion is also cured, and a bulge portion is formed beside the fine structure pattern transferred by the mold. In this state, when the mold is shifted and pressed (step-and-repeat) to continuously form the fine structure, it is difficult to accurately form the fine structure pattern in the raised portion.

In order to solve such a problem, Patent Document 1 discloses a method of forming a fine structure in two stages. Specifically, an ultraviolet curable resin composition for imprinting is applied on a substrate, and first, the mold is pressed a plurality of times at a predetermined interval, and ultraviolet rays are irradiated only near the portion where the mold is pressed. Then, the fine structure is transferred to an ultraviolet curable resin for imprinting. Next, the substrate is etched using the UV curable resin for imprint as a mask, and the fine structure is transferred to the substrate. After removing the UV curable resin for imprinting, apply the UV curable resin composition for imprinting again on the substrate, press the mold in the area where the fine structure is not transferred, and irradiate with ultraviolet rays. Thus, the fine structure is transferred to the UV curable resin for imprinting. By etching the substrate again using the UV curable resin for imprinting as a mask, a substrate to which a continuous fine structure is transferred can be obtained.

Also, when forming a fine structure with a large area by the above method, it is necessary to press the mold many times to transfer the fine structure. In order to solve such problems, Patent Document 2 and Patent Document 3 disclose a method of continuously transferring a fine structure using a roller-shaped mold or a belt-shaped mold.

Japanese Patent Laid-Open No. 2008-247022 JP 2010-16441 A JP 2009-158731 A

However, according to the prior art, there are problems such that the manufacturing process is complicated, a large vacuum device is required, and it is difficult to form a uniform fine structure over a large area. .

One non-limiting exemplary embodiment of the present application provides a fine pattern forming method for forming a fine structure in a large area, and a mold and a sheet formed using the method.

The method for forming a fine pattern according to one aspect of the present invention includes a step (A) of disposing an ultraviolet curable resin composition having oxygen inhibition on the surface of a support, and a mold surface on which a unit fine pattern is formed. A step (B) of pressing the master mold against the ultraviolet curable resin composition so that the mold surface and the ultraviolet curable resin composition are in contact; and an atmosphere containing oxygen in a state where the master mold is pressed Under the step (C) of curing at least the region where the unit fine pattern is transferred in the ultraviolet curable resin composition by irradiating the ultraviolet curable resin composition with ultraviolet rays, and the master mold The step (D) of separating from the ultraviolet curable resin composition, and the unit fine pattern of the ultraviolet curable resin composition A step (E) of repeating the unit transfer step including the steps (B), (C) and (D) at least once in the next region including the uncured region other than the transferred cured region, and the ultraviolet curing. Step (F) of removing an uncured part of the mold resin composition, and in the step (E), the next region overlaps a part of the cured region, In the step (B) in E), the unit fine pattern of the master mold is substantially filled with the ultraviolet curable resin composition.

According to the method for forming a fine pattern according to one aspect of the present invention, an ultraviolet curable resin composition is used in which an ultraviolet curable resin composition having oxygen inhibition properties is used, irradiated with ultraviolet light in an oxygen-containing atmosphere, and a master mold is pressed. The resin composition is cured. For this reason, it is suppressed that a swell part hardens | cures and the large area fine pattern which transferred the unit fine pattern repeatedly can be manufactured.

(A) to (e) are process cross sections showing a first embodiment of a fine pattern forming method according to the present invention. (F) to (i) are process cross sections showing a first embodiment of a fine pattern forming method according to the present invention. (A) And (b) is the perspective view and side view of a master mold which are used in 1st Embodiment of the fine pattern formation method. (A) to (c) is a diagram showing the relationship between the cured region and the next region in the first embodiment of the fine pattern forming method. (A) to (c) are cross-sectional views showing a fine structure formed by the first embodiment of the fine pattern forming method. It is a figure which shows the structure of the nanoimprint system used in order to implement 1st Embodiment of the fine pattern formation method. (A) And (b) is the perspective view and side view of a master mold used in 2nd Embodiment of the fine pattern formation method, (c) is a figure which shows the two-dimensional arrangement | positioning of a hexagonal unit fine pattern It is. (A) is the figure which compared the relationship between the area of a mold surface, and the maximum flow length a which resin should move by a square and a hexagon, (b) is the maximum flow length a in a square and a hexagon. It is a figure which shows a position. (A) to (i) are perspective views showing an embodiment of a mold according to the present invention and showing a manufacturing process of a low sleeve mold. (A) is a perspective view which shows embodiment of a roast sleeve mold, (b) is a figure explaining the method of forming a fine pattern using the loin sleeve mold shown to (a). FIGS. 7A and 7B are an enlarged view of a loose sleeve mold in the vicinity of a press roll and an ultraviolet curable resin composition in contact with the loose sleeve mold in the step of forming a fine pattern using the loose sleeve mold shown in FIG. It is an enlarged view of a thing. (A) And (b) is the top view and sectional drawing which show embodiment of the optical sheet by this invention. (A) And (b) is the top view and sectional drawing which show embodiment of the optical sheet by this invention. (A) And (b) is the top view and sectional drawing which show other embodiment of the optical sheet by this invention. (A) And (b) is the top view and sectional drawing which show other embodiment of the optical sheet by this invention. (A) to (c) are cross-sectional views showing the steps of Experimental Example 1. It is the result of Experimental example 1, Comprising: The relationship between extrusion resin volume and the amount of swelling is shown. It is a result of Experimental example 2, Comprising: The laser microscope image and the image which extracted the defect of the center part of the unit fine pattern of a master mold, and the boundary vicinity of an adjacent unit fine pattern are shown. It is a result of Experimental Example 2 and shows a transfer rate. It is a result of Experimental example 3, Comprising: (a) shows a laser microscope image, (b) has shown the cross-sectional profile in the straight line a of the laser microscope image of (a).

The outline of one embodiment of the present invention is as follows.

The fine pattern forming method according to one embodiment of the present invention includes a step (A) of disposing an ultraviolet curable resin composition having oxygen inhibition on the surface of a support, and a mold surface on which a unit fine pattern is formed. A step (B) of pressing the master mold against the ultraviolet curable resin composition so that the mold surface and the ultraviolet curable resin composition are in contact; and an atmosphere containing oxygen in a state where the master mold is pressed Under the step (C) of curing at least the region where the unit fine pattern is transferred in the ultraviolet curable resin composition by irradiating the ultraviolet curable resin composition with ultraviolet rays, and the master mold The step (D) of separating from the ultraviolet curable resin composition, and the unit fine pattern of the ultraviolet curable resin composition A step (E) of repeating the unit transfer step including the steps (B), (C) and (D) at least once in the next region including the uncured region other than the transferred cured region, and the ultraviolet curing. Step (F) of removing an uncured part of the mold resin composition, and in the step (E), the next region overlaps a part of the cured region, In the step (B) in E), the unit fine pattern of the master mold is substantially filled with the ultraviolet curable resin composition.

The mold surface has a hexagonal shape.

The atmosphere containing oxygen contains 15% by volume or more of oxygen.

The support has a plate shape, a cylindrical shape, or a roll sleeve shape.

The mold which is one embodiment of the present invention is a support, and a resin cured layer which is supported on the support and has a fine pattern formed on the surface by any of the fine pattern formation methods described above, A metal layer provided on the surface of the cured resin layer.

The fine pattern is transferred to the sheet according to one embodiment of the present invention using the mold.

A sheet according to an embodiment of the present invention includes a support, a resin cured layer of an ultraviolet curable resin disposed on the surface of the support, and a plurality of unit fine patterns transferred onto the surface of the resin cured layer. The upper surface of each unit fine pattern is not parallel to the surface of the support, and a step is provided between the upper surfaces of a pair of adjacent unit fine patterns.

The sheet according to an aspect of the present invention includes a support, a resin cured layer of an ultraviolet curable resin disposed on the surface of the support, a plurality of unit fine patterns transferred onto the surface of the resin cured layer, A metal layer provided on the surface of the cured resin layer, the upper surface of each unit fine pattern is not parallel to the surface of the support, and a step is provided between the upper surfaces of a pair of adjacent unit fine patterns. Yes.

(First embodiment)
Hereinafter, a first embodiment of a fine pattern forming method according to the present invention will be described. In the present embodiment, the fine pattern is formed by repeating the unit fine pattern and is formed in the ultraviolet curable resin.

First, as shown in FIG. 1A (a), an ultraviolet curable resin composition 20 is prepared on a support 10. The support 10 may be made of a metal, a semiconductor such as silicon, glass, a resin such as PET (polyethylene terephthalate) or acrylic, and a structural material having various thicknesses. As described below, when the ultraviolet curable resin composition 20 is irradiated via the support 10 with ultraviolet rays for curing the ultraviolet curable resin composition 20, the support 10 transmits the ultraviolet rays. It is preferable that it is comprised with the material to do.

The support 10 preferably has a smooth surface 10a on which a fine pattern is formed. The support 10 may be substantially flat in the region where the unit fine pattern is transferred, and the entire support 10 may have a plate shape, a cylindrical shape, or a roll sleeve shape, and is flexible. You may have. The size of the surface 10a can be adjusted according to the size of the unit fine pattern, the number of repetitions of the unit fine pattern, and the use of the fine pattern to be formed.

As the ultraviolet curable resin composition 20, various ultraviolet curable resin compositions that are cured by irradiation with ultraviolet rays can be used. It is preferable that the ultraviolet curable resin composition 20 has an oxygen inhibitory property that inhibits polymerization in the presence of oxygen. As the ultraviolet curable resin composition 20 having such properties, various radical polymerization type ultraviolet curable resin compositions are preferably used. Typically, such a radical polymerization type ultraviolet curable resin composition includes a photopolymerization initiator and a monomer or oligomer having a vinyl group or a methacryl group capable of radical polymerization. In the present specification, the “ultraviolet curable resin composition” refers to an ultraviolet curable resin before curing.

The ultraviolet curable resin composition 20 is uniformly applied to the surface 10a of the support 10 by a spin coat method, a bar coat method, or the like, and has a layer shape. The thickness t1 of the applied ultraviolet curable resin composition 20 depends on the use of the fine pattern, the depth of the fine pattern to be transferred, and the like. Moreover, as will be described below, if the applied ultraviolet curable resin composition 20 is too thick, it is difficult to control the inhibition of curing of the ultraviolet curable resin composition 20. For this reason, the thickness t1 is preferably 10 μm or less, and more preferably 1 μm or less. On the other hand, the lower limit value of the thickness t1 depends on the shape of the fine pattern to be formed and the pattern depth. For this reason, it can determine suitably according to the fine pattern which should be formed.

Next, a master mold 30 is prepared. 2A and 2B are a schematic perspective view and a side view of the master mold 30. FIG. The master mold 30 has a mold surface 30a, and a unit fine pattern 31 is formed on the mold surface 30a. The mold surface 30a has a rectangular shape. It may be a rectangle or a square. The unit fine pattern 31 is preferably formed up to the end of the mold surface 30a. Thereby, when the unit fine pattern 31 of the master mold 30 is adjacently transferred to the ultraviolet curable resin composition 20 a plurality of times, the adjacent unit fine pattern 31 can be continuously formed without interruption. The master mold 30 is made of quartz, glass, a silicon substrate, or the like. It is preferable that the unit fine pattern 31 is made of a material that can be easily formed. Moreover, when irradiating an ultraviolet-ray from the mold side, it is preferable that the master mold 30 is comprised with the material with the high transmittance | permeability of an ultraviolet-ray. If necessary, a material excellent in releasability may be selected, or a coating for enhancing mold release may be applied to the surface of the unit fine pattern 31.

In this embodiment, a step portion 30d having a width X and a depth T is provided around the mold surface 30a. The step portion 30 d holds the bulge of the ultraviolet curable resin composition 20 when the master mold 30 is pressed against the ultraviolet curable resin composition 20. Thus, when the master mold 30 is attached to the nanoimprint apparatus and a fine pattern is formed by the method of this embodiment, the ultraviolet curable resin composition 20 can be prevented from adhering to the member that supports the master mold 30. it can.

The unit fine pattern 31 formed on the mold surface 30a has various shapes depending on the application. A pattern obtained by inverting the fine pattern 31 is transferred to the surface of the ultraviolet curable resin composition 20. In the present embodiment, the unit fine pattern 31 has a structure in which rectangular concave portions are regularly arranged in two dimensions. However, a structure in which unit structures are randomly arranged may be used. The depth of the fine pattern 31 may be one level, or the fine pattern 31 having two or more different depths. For example, the fine patterns disclosed in JP2009-217292, WO2010 / 131440, WO2010 / 131439, and WO2010 / 131434 can be suitably used. The size d2 of the minimum structural unit of the unit fine pattern 31 depends on the application, the ultraviolet curable resin composition 20 used, the nanoimprint apparatus, and the like. In the present embodiment, the size d2 of the minimum structural unit of the unit fine pattern 31 is, for example, not less than 10 nm and not more than 1 mm, and the depth t2 is, for example, 10 nm to 1 mm. The length L of one side of the unit fine pattern 31 is, for example, 1 mm to 50 mm. 2A and 2B, the master mold 30 is more schematically shown, and the size of the fine pattern 31 is easy to understand. It is greatly expressed compared to. Further, the step portion 30d is not shown.

The unit fine pattern 31 and the stepped portion 30d are produced by, for example, a semiconductor process or high-precision grinding and have good edge roughness. In particular, the edge 31a of the unit fine pattern 31 is preferably excellent in linearity and smoothness. When roughness is poor due to chipping or microcracking at the edge 31a, when the master mold 30 is lowered with high parallelism with respect to the ultraviolet curable resin composition 20, the master molding 30 and the ultraviolet curable resin composition 20 are reduced. Air is trapped in the vicinity of the edge 31a and is not pushed out, and bubble biting occurs. As a result, pattern non-transfer is likely to occur at the portion where the bubble is bitten. Further, when the edge roughness is poor, unevenness is likely to occur in the size of the swelled portion described below.

Next, as shown in FIG. 1A (b), the master mold 30 is arranged so that the mold surface 30 a faces the ultraviolet curable resin composition 20. The master mold 30 is pressed against the ultraviolet curable resin composition 20 so that the mold surface 30a is in contact with the ultraviolet curable resin composition 20 as indicated by an arrow in FIG. 1A (b).

As shown in FIG. 1A (c), the concave portion of the unit fine pattern 31 is filled with the ultraviolet curable resin composition 20 by pressing the master mold 30 against the ultraviolet curable resin composition 20. Further, a part of the ultraviolet curable resin composition 20 excluded by pressing the master mold 30 forms a raised portion 20b, and a step portion 30d of the master mold 30 (not shown in FIG. 1A (c)). It adheres to the side wall.

In a state where the master mold 30 is pressed against the ultraviolet curable resin composition 20, the whole is exposed to an atmosphere containing oxygen, and the ultraviolet curable resin composition 20 is irradiated with ultraviolet rays. Preferably, the atmosphere contains 15% by volume or more of oxygen, and more preferably contains 20.6% by volume or more. There is no restriction | limiting in particular in content of oxygen contained in atmosphere, What is necessary is just 100 volume% or less.

It is preferable to irradiate ultraviolet rays only to a region in contact with the master mold 30 in the ultraviolet curable resin composition 20 disposed on the support 10. For example, the ultraviolet curable resin composition 20 is irradiated with ultraviolet rays through a mask (not shown) in which a region corresponding to the mold surface 30a of the master mold 30 is opened. Thereby, the region where the unit fine pattern 31 of the master mold 30 is transferred is cured to form the cured region 21. Since the whole is placed in an atmosphere containing oxygen, the raised portion 20b of the ultraviolet curable resin composition 20 is exposed to an atmosphere containing oxygen and polymerization is inhibited. On the other hand, since the region where the unit fine pattern 31 is transferred is in contact with the master mold 30, it is not exposed to an atmosphere containing oxygen. For this reason, only the region where the unit fine pattern 31 is transferred selectively becomes the cured region 21. However, if the raised portion 20b becomes too large, oxygen from the surface does not reach the inside of the raised portion 20b, and the inside of the raised portion 20b may be cured. For this reason, it is preferable to adjust the thickness of the ultraviolet curable resin composition 20 formed on the support 10 and the intensity and range of the irradiated ultraviolet rays so that the raised portion 20b does not become too large.

It is known that radical polymerization type ultraviolet curable resins have oxygen inhibition properties. For this reason, in order to make the ultraviolet curable resin sufficiently, it is common to irradiate ultraviolet rays in an atmosphere in which oxygen does not exist. In particular, in UV nanoimprint lithography, it is necessary to transfer a fine pattern. Therefore, it may be preferable to perform nanoimprint lithography in an atmosphere in which oxygen is not present. However, the present invention forms a region that is partially not easily affected by oxygen while exposing the whole to an oxygen-containing atmosphere, and cures only that region, thereby converting the unit fine pattern of the master mold into an ultraviolet curable type. The transfer to the resin composition is realized repeatedly.

As shown in FIG. 1A (d), when the master mold 30 is pulled up from the ultraviolet curable resin composition 20 and separated, a cured region 21 having a unit fine pattern 31 ′ obtained by inverting the unit fine pattern 31 is formed. . At this time, since the raised portion 20b attached to the side surface of the step portion of the master mold 30 loses support, a part of the uncured raised portion 20b falls due to the surface tension and overlaps the cured region 21. The width d1 in which the uncured raised portion 20b overlaps from the end of the cured region 21 depends on the size of the raised portion 20b.

As shown in FIG. 1A (e), the pulled-up master mold 30 is moved in the horizontal direction, and in the next region 22 including the uncured region other than the cured region 21 in the ultraviolet curable resin composition 20, the master mold 30 is lowered and the master mold 30 is pressed against the ultraviolet curable resin composition 20 as shown in FIG. 1B (f).

In this state, the whole is exposed to an atmosphere containing oxygen, and the ultraviolet curable resin composition 20 is irradiated with ultraviolet rays. As a result, the next region 22 is cured. Thereafter, as shown in FIGS. 1B (g) and (h), the unit fine pattern obtained by inverting the unit fine pattern 31 by moving the master mold 30 and curing the ultraviolet curable resin composition 20 is repeated. 31 'are formed sequentially.

After the unit fine pattern 31 ′ is formed a desired number of times, the unit fine pattern 31 is removed by removing the uncured ultraviolet curable resin composition 20 with an organic solvent such as ethanol as shown in FIG. 1B (i). A cured resin layer 20 ′ having a fine pattern in which “is arranged” is obtained. The fine structure 40 including the support 10 and the cured resin layer 20 ′ supported by the support 10 may be used as it is for various applications, or may be used as a mold for transferring a fine pattern. In this case, for example, a metal layer may be formed on the surface of the cured resin layer 20 ′ by sputtering, plating, or the like to improve durability. For example, a large-area optical sheet having a fine pattern directly on the surface may be produced using the fine pattern forming method according to the present embodiment. Alternatively, the fine structure 40 may be manufactured using the flat plate-shaped or roll sleeve-shaped support 10, and the large-sized optical sheet may be manufactured using the manufactured fine structure as a flat plate mold or a roll sleeve mold.

Next, the arrangement of unit fine patterns formed in the fine pattern forming method of this embodiment will be described. As shown in FIGS. 1B (e) and (f), when the master mold 30 is pressed against the ultraviolet curable resin composition 20 adjacent to the already-cured cured region 21, the next region with respect to the cured region 21 22 can take three arrangements, when adjacent to each other without a gap, when overlapping, and when arranged with a gap.

First, the case of adjoining without a gap will be described. In this case, as shown in FIG. 3A, the master mold 30 is adjacent to the curing region 21 so that the boundary defining the next region 22 and the boundary defining the curing region 21 are in contact with each other. Press against composition 20. As described above, when the cured region 21 is formed, since the ultraviolet curable resin composition 20 is irradiated with ultraviolet rays in an atmosphere containing oxygen, the raised portion 20b is not cured. For this reason, the next region 22 can be determined without leaving a space between the cured region 21 and the next region 22. FIG. 4A schematically shows the microstructure 41 formed in this way. As shown in FIG. 4A, in the cured resin layer 20 ', a plurality of unit fine patterns 31' are formed adjacent to each other without a gap. This arrangement is particularly suitable when the position where the master mold 30 is lowered can be accurately aligned, or when it is desired to form a fine pattern in which the boundaries of the unit fine patterns 31 'are accurately aligned. Since the plurality of unit fine patterns 31 ′ do not overlap, the upper surface 31 ′ a of each unit fine pattern 31 ′ is parallel to the surface 10 a of the support 10.

Next, the case where the next region 22 overlaps the cured region 21 will be described. In this case, as shown in FIG. 3B, the master mold 30 is pressed against the ultraviolet curable resin composition 20 adjacent to the cured region 21 so that the next region 22 overlaps a part of the cured region 21. As described above, when the master mold 30 is pulled up from the cured region 21, a part of the uncured raised portion 20b overlaps the cured region 21 in the range of the width d1. Therefore, if the overlap d3 between the next region 22 and the cured region 21 is within the width d1, the concave portion of the mold surface 30a of the master mold 30 is filled with the ultraviolet curable resin composition 20, and therefore the next region 22 The unit fine pattern 31 'is correctly formed on the entire surface. When the plurality of unit fine patterns 31 ′ are two-dimensionally arranged, the next region 22 may overlap the cured region 21 in two directions in which the unit fine patterns 31 ′ are arranged, or may overlap only in one direction. As shown in FIG. 3B, when the master mold 30 is pressed against the ultraviolet curable resin composition 20 so that the next region 22 overlaps a part of the cured region 21, the master mold 30 is against the support 10. However, it is preferable to arrange them diagonally so that the cured region 21 side is high and the opposite side is low.

FIG. 4B schematically shows the fine structure 42 formed in this way. As shown in FIG. 4B, in the resin cured layer 20 ', one end of each unit fine pattern 31' overlaps with the adjacent unit fine pattern 31 '. For this reason, the unit fine pattern 31 'is continuously formed. As shown in FIG. 4B, the upper surface 31 ′ a of each unit fine pattern 31 ′ is not parallel to the surface 10 a of the support 10 by pressing the master mold 30 obliquely. A step Z is provided in a direction perpendicular to the upper surface 31'a between the upper surfaces 31'a of a pair of adjacent unit fine patterns 31 '. As will be described below, the fine structure 42 having such a level difference Z, when used as a cylindrical mold, is easy to remove bubbles when transferring a fine pattern, and suppresses the occurrence of defects. In addition, the fine pattern of the fine structure 42 can be accurately transferred. According to this arrangement, the unit fine pattern 31 ′ can be continuously formed without accurately aligning the position where the master mold 30 is lowered.

Next, a case where a gap is provided between the cured region 21 and the next region 22 will be described. As shown in FIG. 3C, in this case, the UV curable resin composition is adjacent to the cured region 21 so that the next region 22 is positioned with a gap from the end of the cured region 21. Press 20 The gap d2 between the next region 22 and the cured region 21 can be determined according to the specifications of the fine pattern to be produced. When the next region 22 is determined, the region other than the cured region 21 in the ultraviolet curable resin composition 20 is in an uncured state, so that in principle, the gap d2 is an arbitrary value as long as it is 0 μm or more. Can take. However, when the gap d2 becomes too large, the interval between the unit fine patterns 31 'becomes large and the gap d2 becomes conspicuous in the produced fine pattern. Therefore, the gap d2 is preferably 0.2 μm or less.

FIG. 4C schematically shows the fine structure 43 formed in this way. As shown in FIG. 4C, in the fine structure 43, a plurality of cured resin layers 20 ′ having unit fine patterns 31 ′ are formed on the support 10. Each cured resin layer 20 'is not connected to the adjacent cured resin layer 20' and is independent. This is because the region that becomes the gap d2 in the ultraviolet curable resin composition 20 is an uncured region, so that the ultraviolet curable resin composition 20 in the region that becomes the gap d2 is finally removed. According to this arrangement, the plurality of unit fine patterns 31 ′ can be formed without accurately aligning the position where the master mold 30 is lowered.

The fine pattern forming method of the present embodiment can be executed using, for example, the nanoimprint system 50 shown in FIG. The nanoimprint system 50 includes a glove box 51, an ultraviolet irradiation type imprint apparatus 52, an exposure time adjustment controller 53, an XY stage controller 54, an oxygen concentration meter 55, and a substrate chuck vacuum pump 56. The ultraviolet irradiation type imprint apparatus 52 is disposed in the glove box 51, and the glove box 51 is provided with an introduction port for introducing nitrogen and oxygen and an exhaust port for exhausting the inside of the glove box 51. The ultraviolet irradiation type imprint apparatus 52, the exposure time adjustment controller 53, the XY stage controller 54, the oxygen concentration meter 55, and the substrate chuck vacuum pump 56 are connected to the ultraviolet irradiation type imprint apparatus 52.

After the ultraviolet curable resin composition 20 is applied to the support 10, the support is introduced into the ultraviolet irradiation imprint apparatus 52. Thereafter, the inside of the glove box 51 is exhausted, and oxygen and nitrogen are introduced. The oxygen concentration in the glove box 51 is confirmed by the oxygen concentration meter 55, and the ultraviolet curable resin composition 20 is used by using the exposure time adjustment controller 53 and the XY stage controller 54 according to the fine pattern forming method of the present embodiment described above. Is cured.

Thereafter, the support body 10 is taken out from the glove box 51, and the uncured ultraviolet curable resin composition 20 is removed to remove the microstructures 41, 42 shown in FIG. 4 (a), (b) or (c). 43 can be obtained.

As described above, according to the fine pattern forming method of the present embodiment, an ultraviolet curable resin composition having an oxygen-inhibiting property, irradiated with ultraviolet rays in an atmosphere containing oxygen, and pressed against a master mold. The resin composition is cured. Under the present circumstances, since superposition | polymerization is inhibited in the part which is not in contact with a master mold, it is suppressed that a swelling part hardens | cures. Therefore, even when the master mold is repeatedly pressed and a part of the ultraviolet curable resin composition is sequentially cured, an unnecessary cured portion is not generated at the end of the unit fine pattern transferred from the master mold, and the unit fine pattern It is possible to form a fine pattern transferred without a joint.

(Second Embodiment)
The second embodiment of the fine pattern forming method according to the present invention will be described below. The fine pattern forming method of the present embodiment is the same as that of the first embodiment except that the shape of the mold surface of the master mold is different. For this reason, a different part from 1st Embodiment is mainly demonstrated.

6 (a) and 6 (b) are a schematic perspective view and a side view of the master mold 30 used in the present embodiment. The master mold 30 has a mold surface 30a, and a unit fine pattern 31 is formed on the mold surface 30a. The mold surface 30a of the master mold 30 used in the present embodiment has a hexagonal shape, for example, a regular hexagonal shape. The unit fine pattern 31 is preferably formed up to the end of the mold surface 30a. In this case, the unit fine pattern 31 also has a hexagonal or regular hexagonal shape. As in the first embodiment, when the unit fine pattern 31 of the master mold 30 is adjacently transferred to the ultraviolet curable resin composition 20 a plurality of times, the adjacent unit fine pattern 31 is continuous without interruption. Can be formed.

The size d2 of the minimum constituent unit of the unit fine pattern 31 depends on the application, the ultraviolet curable resin composition 20 used, the nanoimprint apparatus, and the like. In the present embodiment, the size d2 of the minimum structural unit of the unit fine pattern 31 is, for example, not less than 10 nm and not more than 1 mm, and the depth t2 is, for example, 10 nm to 1 mm. The length L of one side (one side of the hexagon) of the unit fine pattern 31 is, for example, 1 mm to 50 mm.

As shown in FIG. 6C, when the unit fine pattern 31 has a hexagonal shape and the unit fine pattern 31 is transferred without a gap in the two-dimensional space, In the direction A1 perpendicular to each side of the square, a plurality of unit fine patterns 31 ′ are arranged so that the centers of the adjacent unit fine patterns 31 ′ are located on the direction A1. On the other hand, in a direction A2 connecting each vertex of the hexagon and the center of the hexagon, one side of the adjacent unit fine pattern 31 is located on the direction A2. When the direction A1 is taken in the x-axis direction, the unit fine pattern 31 is arranged in the x direction with the interval between two parallel sides of the unit fine pattern 31 'facing each other, but adjacent to the y direction. This is because the unit fine pattern 31 ′ to be shifted is arranged by being shifted by ½ period in the x direction.

When the unit fine pattern 31 is transferred without a gap in the two-dimensional space as shown in FIG. 6C, first, as described in the first embodiment, the mold 30 shown in FIGS. 6A and 6B. Is pressed against the ultraviolet curable resin composition 20, and the unit fine pattern 31 ′ obtained by inverting the unit fine pattern 31 is directed to the ultraviolet curable resin composition 20 in one direction (the x direction in FIG. 6C or the A1 direction). Are formed sequentially. Thereby, the transfer of the unit fine pattern in the first row is completed.

After that, returning to the position of the unit fine pattern 31 ′ formed first, the row direction is such that the first unit fine pattern 31 ′ of the second row is adjacent to the first and second unit fine patterns 31 ′ of the first row. By shifting the position of the master mold 30 in the x direction (FIG. 6C) and the column direction (y direction in FIG. 6C) and repeating the same process, the second row, the third row, etc. The unit fine pattern is transferred.

As described in the first embodiment, when the master mold 30 is pressed against the ultraviolet curable resin composition 20 adjacent to the already formed cured region 21, in the direction A1 (FIG. 6C), When the next region 22 is adjacent to the cured region 21 without a gap, the next region 22 may be arranged in three cases, in the case of overlapping, or in the case of being arranged with a gap.

On the other hand, when the master mold 30 is pressed against the ultraviolet curable resin composition 20 adjacent to the already formed cured region 21 in the direction perpendicular to the direction A1, that is, in the second row, the third row, etc., 2- It is preferable that the hardened regions 21 in the immediately preceding rows such as the first row and the 3-1 row are adjacent to each other without a gap or arranged with a gap. Since the unit fine pattern 31 has a hexagonal shape, the unit fine pattern 31 ′ in one row is adjacent to the two unit fine patterns 31 ′ in the previous row. This is because a step in the previous row is located in the middle of “and it may be difficult to transfer the shape of the correct unit fine pattern 31 ′.

In the fine pattern forming method of the present embodiment, the mold surface 30a of the master mold 30 has a hexagonal shape. Thereby, in addition to the various effects of 1st Embodiment, the bubble biting at the time of transferring the unit fine pattern 31 can be suppressed.

When UV imprinting is performed using the master mold 30, if the area of the mold surface 30 a of the master mold 30 is small, the number of times the unit fine pattern 31 is transferred to form a sheet increases, and an error occurs during transfer. In addition to increasing the probability of occurrence, it causes a significant increase in tact time, resulting in an increase in cost. For this reason, the mold surface 30a of the master mold 30 is preferably as large as possible. However, when the mold surface 30a is too large, the occurrence probability of bubble biting increases.

Generally, during UV imprinting, when the master mold and the ultraviolet curable resin composition come into contact with each other, bubbles are embraced on the contact surface. This is considered to be because the flatness of the master mold cannot be reduced to zero, or the surface flatness on the outermost surface of the composition cannot be reduced to 0 when the ultraviolet curable resin composition is applied. The generated bubbles are pushed out of the contact area of the mold together with the ultraviolet curable resin composition in the course of pressing the ultraviolet curable resin composition with the master mold. For this reason, the transfer can be performed without the appearance of bubble biting on the cured product under appropriate transfer conditions. However, when the mold surface of the master mold is enlarged, the flow distance for the resin composition containing foam to move out of the contact area with the mold increases, so that the foam can be excluded out of the contact area. Unable to increase the probability of an error due to foam biting.

In order to solve this conflicting problem, in this embodiment, the mold surface is formed of a hexagon. FIG. 7A is a diagram in which the relationship between the area of the mold surface and the maximum flow length a to which the resin should move is compared between a square and a hexagon. FIG. 7B shows the position of the maximum flow length a in a square and a hexagon. In the square and hexagon, the diagonal distance is the longest and the maximum flow length a is obtained. As can be seen from FIG. 7A, the maximum flow length a increases as the mold surface area increases, but the hexagonal maximum flow length a is 12.3% shorter than the square. For this reason, according to the formation method of the fine pattern of this embodiment, generation | occurrence | production of the defect by bubble biting can be suppressed compared with the past, and the fine pattern of a fine structure can be transcribe | transferred more correctly.

The fine pattern forming method of the present embodiment can be executed using, for example, the nanoimprint system 50 shown in FIG. 6 as in the first embodiment.

(Third embodiment)
An embodiment of a mold according to the present invention will be described. As described in the first and second embodiments, large-area molds having various shapes can be produced by the fine pattern forming method of the present invention. The loin sleeve mold having a fine pattern manufactured by the method described in the first or second embodiment and the manufacturing method thereof will be described below.

As shown in FIG. 8A, a flexible roll sleeve 110 is prepared as a support, and an ultraviolet curable resin composition 20 is applied to the surface. As the roll sleeve 110, a stainless steel roll whose surface is flattened by welding and polishing can be used.

As shown in FIGS. 8B to 8I, the master mold 30 is repeatedly pressed against the ultraviolet curable resin composition 20 applied to the roll sleeve 110 as described in the first embodiment, and ultraviolet rays are applied. By irradiation, unit fine patterns 31 ′ are sequentially formed. The cured region and the next region may be arranged in any relationship shown in FIGS. 4 (a), (b), and (c).

As shown in FIG. 8 (i), after the unit fine pattern 31 ′ is formed on the entire ultraviolet curable resin composition 20 applied to the roll sleeve 110, the uncured ultraviolet curable resin composition 20 is made of ethanol or the like. By washing away with an organic solvent, a fine structure 141 having a fine pattern formed on the surface of the roll sleeve 110 is obtained.

A roll sleeve mold 142 shown in FIG. 9A is obtained by forming a metal thin film on the surface of the fine pattern of the fine structure 141 by vapor deposition or plating. Alternatively, a roll sleeve mold may be manufactured by transferring the fine structure 141 to silicone.

The roll sleeve mold 142 includes a microstructure 141 including a roll sleeve 110 and a cured resin layer 20 ′ supported by the roll sleeve 110, and a plurality of unit fine patterns 31 ′ are formed on the surface of the cured resin layer 20 ′. Has been. As described above, the arrangement of the plurality of unit fine patterns 31 ′ may be any of those shown in FIGS. 4A, 4B, and 4C, but the fine structure 141 is shown in FIG. The microstructure 42 shown is preferable.

FIG. 9B shows how the pattern is transferred to the ultraviolet curable resin composition 220 using the roll sleeve mold 142. First, the ultraviolet curable resin composition 220 is applied on the support 210. The roll sleeve mold 142 is supported by the auxiliary roll 201 and the press roll 202, and is held by the press roll 202 so that the surface of the roll sleeve mold 142 is pressed against the ultraviolet curable resin composition 220 on the support 210.

The support 210 is moved in synchronization with the rotation of the roll sleeve mold 142, and, for example, ultraviolet rays from the ultraviolet lamp 203 are irradiated only from the support 210 side to the vicinity of the press roll 202. Thereby, the fine pattern of the roll sleeve mold 142 is sequentially transferred to the ultraviolet curable resin composition 220 by the pressing of the press roll 202, and ultraviolet rays are irradiated in the transferred state. For this reason, as the support 210 moves, the cured resin layer 220 ′ to which the fine pattern has been transferred is sequentially generated.

FIG. 10A is an enlarged view showing the vicinity of the press roll 202. Moreover, FIG.10 (b) has expanded and shown the part which the roll sleeve mold 142 and the ultraviolet curable resin composition 220 contact | connect.

When the fine structure 141 of the roll sleeve mold 142 is the fine structure 42 shown in FIG. 4B, the surface 31′a of each unit fine pattern 31 ′ is formed on the support 10 as shown in FIG. It is not parallel but inclined with respect to the surface 10a. Further, a step z is formed between the surface 31'a of the unit fine pattern 31 'and the surface 31'a of the adjacent unit fine pattern 31'. For this reason, as shown in FIG. 10B, when the roll sleeve mold 142 is in contact with the ultraviolet curable resin composition 220, in the region where each unit fine pattern 31 ′ is transferred, the traveling direction of the support 210 (x direction) ) Has changed from Ax to Ay. For this reason, the extrusion force Px acts on the ultraviolet curable resin composition 220. The presence of this Px improves the fluidity of the ultraviolet curable resin composition 220. For example, even if the resin composition is trapped at a specific point on the surface of the roll sleeve mold due to various factors such as dust, formation of a fine structure, and unevenness of the release agent, bubbles are generated and the resin composition is Even if an unfilled point occurs, the resin can be filled by an extrusion force. Therefore, transfer with few defects can be performed, and a cured resin layer 220 'to which a fine pattern with few defects is transferred can be obtained.

(Fourth embodiment)
An embodiment of an optical sheet according to the present invention will be described.

11A and 11B are a plan view and a cross-sectional view of the optical sheet 242. FIG. The optical sheet 242 includes a support 210 and a cured resin layer 220 ′ disposed on the support 210. A plurality of unit fine patterns 31 ′ are formed on the surface of the cured resin layer 220 ′. The unit fine pattern 31 'has a square shape. The plurality of unit fine patterns 31 ′ are two-dimensionally arranged at intervals A, for example. Such an optical sheet 242 can be manufactured using, for example, the fine pattern forming method described in the first embodiment and the roll sleeve mold described in the second embodiment.

The size of the unit fine pattern 31 ′ depends on the size at which the master mold can be manufactured at a low cost, the transfer rate at which the unit fine pattern of the master mold can be correctly transferred by one transfer, the size of the optical sheet to be formed, and the like. Further, the unit irradiation pattern 31 'can be enlarged as the ultraviolet irradiation type imprint apparatus can move the master mold with high alignment accuracy and can be pressed down to the ultraviolet curable resin composition with a large pressure.

As shown in FIG. 9B, in the resin cured layer 220 ′, the upper surface 31 ′ a of each unit fine pattern 31 ′ is not parallel to the surface 220 a of the support 210. A step z is formed between the upper surfaces 31'a of the adjacent unit fine patterns 31 '. Such a structure can be manufactured using, for example, the roll sleeve mold described in the second embodiment. The level difference z is determined according to the specifications of the optical sheet 242.

FIGS. 12A and 12B are a plan view and a cross-sectional view of another optical sheet 242. FIG. In the sheet 242 shown in FIGS. 12A and 12B, the unit fine pattern 31 'has a regular hexagonal shape. Other structures are the same as those of the optical sheet 242 shown in FIGS.

FIGS. 13A and 13B are a plan view and a cross-sectional view of an optical sheet 241 having another form. The optical sheet 242 includes a support 210 and a cured resin layer 220 ′ disposed on the support 210. In the resin cured layer 220 ', each unit fine pattern 31a is arranged without providing a gap between the adjacent unit fine patterns 31'. Therefore, the upper surface 31 ′ a of each unit fine pattern 31 ′ is parallel to the surface 220 a of the support 210. The unit fine pattern 31 'has a square shape.

The optical sheet 241 having such a structure can be manufactured by using a mold having a fine structure in which unit fine patterns 31 ′ are arranged as shown in FIG.

FIGS. 14A and 14B are a plan view and a cross-sectional view of an optical sheet 241 having still another form. Except that the unit fine pattern 31 ′ has a regular hexagonal shape, it is the same as the optical sheet 242 shown in FIGS. 13A and 13B.

(Experimental example)
An experiment was conducted to confirm the effect of the embodiment of the fine pattern forming method of the present invention. Hereinafter, experiments and results will be described.

(Experimental example 1)
First, the conditions under which the raised portion formed when the master mold was pressed against the ultraviolet curable resin composition were not cured were determined.

As shown in FIG. 15A, the ultraviolet curable resin composition 320 was applied on the support 310 by spin coating. The thickness t of the ultraviolet curable resin composition 320 was changed by changing the spin coating conditions. As the ultraviolet curable resin composition 320, PAK01-200 manufactured by Toyo Gosei Co., Ltd. having oxygen inhibition properties was used. In the master mold 330, a SiO ₂ layer having a thickness of 0.6 μm was deposited on a plate glass having a thickness of 0.5 mm, and processed into a rectangular shape having a side of 8 mm. The edge end face was processed by dicing with a resin blade so that the chip of the edge was 1 μm or less.

Next, as shown in FIG. 15 (b), the master mold 330 was pressed against the ultraviolet curable resin composition 320 and cured by irradiation with ultraviolet rays. As the imprint apparatus, Nanoimprint apparatus EUN-4200 manufactured by Engineering System Co., Ltd. was used. The UV-LED light source (wavelength 375 nm / ultraviolet light intensity 2.57 mW / cm ² ) attached to the nanoimprint apparatus was used as the light source, and curing was performed by irradiating the ultraviolet curable resin composition 320 with ultraviolet light for 60 seconds. . The transfer pressure was 2.26 N / mm ² . EGC1720 manufactured by 3M was used as the mold release agent. Curing was performed in an atmosphere containing oxygen at a ratio of 0.5, 10, 15, 20.6% by volume.

As shown in FIG. 15 (c), after pulling up the master mold 330, the uncured ultraviolet curable resin composition 320 is removed with ethanol, and the rising amount D and the partial thickness t ′ where the master mold 330 is in contact with each other. Was measured using a laser microscope.

The extruded resin volume was determined by A × (t−t ′), where A is the area of the master mold 330. FIG. 16 shows the relationship between the swell amount D and the extruded resin volume.

As can be seen from FIG. 16, when the atmosphere during ultraviolet irradiation contains 15% by volume or more of oxygen, the effect of suppressing the swell amount D appears significantly. Further, if the oxygen content is 20.6% by volume, even if the extruded resin volume is 0.001 cm ³ , the swell amount D can be made almost zero. From these results, it can be seen that the swell amount D can be controlled by adjusting the oxygen concentration in the atmosphere and the thickness t of the ultraviolet curable resin composition 320.

(Experimental example 2)
Next, a master mold having a random fine pattern is actually used, and as described in the first embodiment, the master mold is pressed against the ultraviolet curable resin composition so that the cured region and the next region overlap. Then, a fine pattern was formed and evaluated.

As shown in FIG. 15 (a), a PET film (Toyobo Cosmo Shine double-sided easy adhesion treatment) having a thickness of 250 μm was used as the support 310. The UV curable resin composition 320 was applied to the easily adhesive surface of the PET film by spin coating. The thickness of the ultraviolet curable resin composition 320 was 300 nm. In this experimental example, the support 310 has a plate shape, but a sleeve roll may be used as the support as long as a desired structure is obtained. As the ultraviolet curable resin composition 320, PAK01-200 manufactured by Toyo Gosei Co., Ltd. having oxygen inhibition properties was used.

The master mold 330 is a three-dimensional random structure in which a SiO ₂ layer having a thickness of 0.6 μm is deposited on a plate glass having a thickness of 0.5 mm, and multi-stage fine processing is performed on the SiO ₂ layer by lithography and etching. Formed. The master mold had a square shape of about 8 mm square, and the edge end face was processed without chipping by dicing with a resin blade.

As the imprint apparatus, a nanoimprint apparatus EUN-4200 manufactured by Engineering System Co., Ltd. was used, and a stage capable of step-and-repeat was attached. The master mold was fixed to the quartz top plate using a double-sided tape that transmits ultraviolet rays, and the quartz top plate was fixed to the nanoimprint apparatus. The UV-LED light source (wavelength 375 nm / ultraviolet light intensity 2.57 mW / cm ² ) attached to the nanoimprint apparatus was used as the light source, and curing was performed by irradiating the ultraviolet curable resin composition 320 with ultraviolet light for 60 seconds. . The transfer pressure was 2.26 N / mm ² . EGC1720 manufactured by 3M was used as the mold release agent. The transfer was performed in an air atmosphere (oxygen concentration 20.6%).

After the unit fine pattern of the master mold 330 was transferred once under these conditions, the unit fine pattern was transferred a plurality of times so that the next region overlaps a part of the cured region as described in the first embodiment. The overlapping amount was about 20 μm. After the transfer, the uncured ultraviolet curable resin composition 320 was removed with ethanol and allowed to dry naturally.

After the transfer, the structure of the boundary portion was photographed using a Keyence laser microscope VK9700. Since the fine pattern to be transferred has a random shape, the transfer rate was determined by the following method. First, areas other than the minimum processing dimension were extracted near the boundary between two adjacent unit fine patterns of the created fine structure by image processing, and the areas were integrated. Next, the integrated area was similarly determined in the vicinity of the center of the unit fine pattern of the master mold, and the ratio of the integrated area near the boundary to the integrated area of the master mold was taken as the transfer rate. For comparison, a sample in which a unit fine pattern was transferred by irradiating ultraviolet rays in a nitrogen atmosphere containing no oxygen and producing a unit fine pattern was prepared, and the transfer rate was determined by the same method.

FIG. 17 shows a laser microscope image of the center part of the unit fine pattern of the master mold and a laser microscope image near the boundary between two adjacent unit fine patterns in the conventional example and the example. Moreover, the image which extracted the defect is shown under each image. A portion shown in black in the image from which the defect is extracted indicates a region other than the minimum processing size. It indicates that the more black portions are on the mold, the more transfer defects are generated. FIG. 18 shows the transfer rate of each sample. The measurement was evaluated at 5 points for each sample.

17 and 18, it can be seen that the conventional sample has a low transfer rate and a large variation in the transfer rate. On the other hand, the transfer rate of the sample of the example is high and the transfer rate variation is small. This indicates that the transfer failure and the variation due to the hardening of the raised portion are greatly suppressed near the boundary with the adjacent unit fine pattern by performing the transfer in an atmosphere containing oxygen.

(Experimental example 3)
The raised portion produced when the transfer was performed in an atmosphere containing 0.5% by volume of oxygen was evaluated. Using an atmosphere containing 0.5% by volume of oxygen as the atmosphere at the time of transfer, a fine pattern was formed under the same conditions as in Experimental Example 2 except that the master mold 330 was transferred only once and evaluated with a laser microscope. went. FIG. 19A shows a laser microscope image. FIG. 19B shows a cross-sectional profile along the straight line a in FIG.

As shown in FIGS. 19A and 19B, when the oxygen contained in the atmosphere at the time of transfer is small, curing of the raised portion cannot be sufficiently suppressed. For this reason, a raised portion of several μm is generated adjacent to the transferred unit fine pattern. In this way, when the raised portion is cured, it is difficult to form the next unit fine pattern adjacent to the transferred unit fine pattern.

(Experimental example 4)
An experimental example in which a fine pattern is produced by the method of the second embodiment will be described.

As the support 10, a PET film (Toyobo Cosmo Shine double-sided easy adhesion treatment) having a thickness of 250 μm was used. The ultraviolet curable resin composition was applied to the easily adhesive surface of the support 10 by spin coating. In this experiment, a sleeve was not used, but a sleeve roll may be used as a support if a desired structure is obtained. The UV curable resin composition used was NIAC23 manufactured by Daicel Chemical Industries, which has oxygen-inhibiting properties and can be prepared to have a low viscosity suitable for thin film formation. The thickness of the ultraviolet curable resin composition was about 300 nm by adjusting the rotation speed of the spin coat. The master mold 30 used has a three-dimensional random structure by depositing 0.6 μm of SiO ₂ on a 0.5 mm thick white glass, and then subjecting the formed SiO ₂ film to multistage fine processing by lithography and etching. A unit fine pattern 31 was formed. In the present embodiment, the unit fine pattern 31 ′ formed on the support 10 may be a three-dimensional random structure, and therefore, the unit fine pattern 31 to be transferred and the unit fine pattern 31 ′ to be formed are not considered. It was. However, it is preferable to form a pattern obtained by inverting the unit fine pattern 31 ′ to be formed on the support 10 as the unit fine pattern 31 in the master mold 30 as necessary.

Thereafter, a resist having a hexagonal pattern is formed on the unit fine pattern 31 by photolithography, the SiO ₂ film is etched by ECR using the resist as a mask, and a mold surface 30a having a hexagonal step shape is formed. Formed. This etching may be performed by a wet process. However, in this case, it is preferable that the end of the unit fine pattern 31 is not located at the position where the step shape is to be formed. When the end of the unit fine pattern 31 is located at the position where the step shape is to be formed, the etching proceeds from the surface of the unit fine pattern 31, so that the fine structure is reflected at the edge and the roughness of the edge increases. In this case, when the unit fine pattern 31 is transferred, the amount of swelling of the resin composition varies depending on the position of the edge, and a region where the influence of oxygen inhibition is weak is generated. Can occur.

As the imprint apparatus, a nanoimprint apparatus EUN-4200 manufactured by Engineering System Co., Ltd. was used and a stage capable of step-and-repeat was attached. The master mold was fixed to the quartz top plate using a double-sided tape that transmits ultraviolet rays, and the quartz top plate was fixed to the nanoimprint apparatus. The UV-LED light source (wavelength 375 nm / ultraviolet intensity 2.57 mW / cm ² ) attached to the nanoimprint apparatus was used as the light source, and curing was performed by irradiating the ultraviolet curable resin composition 20 with ultraviolet rays for 60 seconds. . The transfer pressure was 2.26 N / mm ² . EGC1720 manufactured by 3M was used as the mold release agent. The transfer was performed in an air atmosphere (oxygen concentration 20.6%). Under this condition, the unit fine pattern 31 was transferred once, and then the unit fine pattern 31 was repeatedly transferred by step & repeat. The overlapping amount of the transfer after the second time was about 20 μm. After imprinting, the uncured resin was washed with ethanol and dried by air blow.

Thereafter, the entire region of the support 10 was irradiated with ultraviolet rays in a nitrogen atmosphere and afterbaked at 60 ° C. to completely cure the resin. Thus, a sheet-like mold was obtained in which the unit fine patterns 31 ′ were two-dimensionally arranged and the transferred resin cured layer was provided on the support.

After that, the produced sheet-like mold was attached to the outer surface of the cylindrical dedicated container. Next, a cylindrical container having a larger diameter than the cylindrical container on which the sheet-shaped mold is attached is prepared, and the cylindrical container on which the sheet-shaped mold is attached is disposed inside the large-diameter cylindrical container. A silicone resin (SIM260 manufactured by Shin-Etsu Chemical Co., Ltd.) was filled between the containers and cured. As a result, a roll sleeve mold having a silicone resin layer on which the unit fine pattern 31 ′ was transferred was obtained. Further, the surface of the silicone resin layer was plated with nickel to obtain a roll sleeve mold in which the unit fine patterns 31 'were two-dimensionally arranged on the surface. By using this roll sleeve mold, a large area sheet having a fine structure was produced by a roll-to-roll method. In addition to the current method, a sheet mold that is directly coated with a high-hardness thin film coating (for example, diamond-like carbon coating) may be used as a sleeve mold, or a structure is produced by step-and-repeat inside the sleeve. However, nickel plating may be directly applied thereto. By producing a roll sheet by the fine pattern forming method of the present embodiment, an optical sheet having a three-dimensional microstructure can be provided with high quality and low cost.

The method for forming a fine pattern disclosed in the present application is suitably used for forming a fine pattern of a large area, an optical sheet used for preventing reflection, improving emission efficiency, improving light distribution characteristics, and other various uses. It is suitably used for forming a fine pattern used in the above, or for producing a mold for forming these.

10, 110, 210 Support 20, 220 UV curable resin composition 21 Curing region 22 Next region 30 Master mold 31 Unit fine pattern 40, 41, 42, 43, 141 Microstructure 50 Nanoimprint system 51 Glove box 52 UV Irradiation type imprint apparatus 53 Exposure time adjustment controller 54 XY stage controller 55 Oxygen concentration meter 56 Vacuum pump for substrate chuck 201 Auxiliary roll 202 Press roll 241 242 Optical sheet

Claims (8)

1. A step (A) of disposing an ultraviolet curable resin composition having oxygen inhibition properties on the surface of the support;
   A step (B) of pressing a master mold having a mold surface on which a unit fine pattern is formed against the ultraviolet curable resin composition so that the mold surface and the ultraviolet curable resin composition are in contact with each other;
   In a state where the master mold is pressed, at least the unit fine pattern of the ultraviolet curable resin composition is transferred by irradiating the ultraviolet curable resin composition with ultraviolet rays in an atmosphere containing oxygen. A step (C) of curing the region;
   Separating the master mold from the ultraviolet curable resin composition (D);
   Unit transfer including the steps (B), (C) and (D) in the next region including the uncured region other than the cured region to which the unit fine pattern has been transferred in the ultraviolet curable resin composition. A step (E) of repeating the step one or more times;
   Step (F) of removing an uncured portion of the ultraviolet curable resin composition;
   Including
   In the step (E), the next region overlaps a part of the cured region,
   In the step (B) in the step (E), a method for forming a fine pattern in which the unit fine pattern of the master mold is substantially filled with the ultraviolet curable resin composition.
2. The method for forming a fine pattern according to claim 1, wherein the mold surface has a hexagonal shape.
3. The method for forming a fine pattern according to claim 1 or 2, wherein the oxygen-containing atmosphere contains 15% by volume or more of the oxygen.
4. The method for forming a fine pattern according to any one of claims 1 to 3, wherein the support has a plate shape, a cylindrical shape, or a roll sleeve shape.
5. A support;
   A resin cured layer, which is supported on the support and has a fine pattern formed on the surface by the method for forming a fine pattern according to any one of claims 1 to 4,
   A mold for forming a fine pattern comprising a metal layer provided on the surface of the cured resin layer.
6. A sheet on which a fine pattern is transferred using the mold according to claim 5.
7. A support;
   A resin cured layer of an ultraviolet curable resin disposed on the surface of the support;
   A plurality of unit fine patterns transferred to the surface of the cured resin layer;
   The sheet | seat in which the upper surface of each said unit fine pattern is non-parallel to the surface of the said support body, and the level | step difference is provided between the upper surfaces of a pair of adjacent unit fine pattern.
8. A support;
   A resin cured layer of an ultraviolet curable resin disposed on the surface of the support;
   A plurality of unit fine patterns transferred onto the surface of the cured resin layer, a metal layer provided on the surface of the cured resin layer,
   With
   The upper surface of each unit fine pattern is non-parallel to the surface of the support,
   A mold in which a step is provided between the upper surfaces of a pair of adjacent unit fine patterns.

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