JP6772669B2 - Method for manufacturing fine concavo-convex structure, fine convex structure and fine concave structure - Google Patents

Description

The present disclosure relates to a fine concavo-convex structure and a method for producing a fine convex structure and a fine concave structure.

There are known articles that form a fine convex structure (pillar pattern) on the surface of a base material and can exhibit various functions by the fine convex structure. For example, an antireflection film has been proposed that utilizes the principle of the so-called moth eye structure in which a cone-shaped fine pillar structure such as a cone or a quadrangular pyramid is formed at a period equal to or less than the wavelength of visible light. (See Patent Document 1).

It has a nano-order convex structure (pillar pattern) on the metal surface, and when light is incident on the metal surface, the sparse and dense waves of free electrons (surface plasmon waves) on the metal surface are evanescent waves generated by the incident light. A plasmon resonance structure has been proposed which can be used as a high-sensitivity sensor, an optical filter, etc. by causing so-called surface plasmon resonance, which is excited by resonance with light (see Patent Document 2).

It exists on the surface of the wings of cicadas and dragonflies in research on biomimetics that artificially produces articles having functions unique to the living body by imitating the structure of the living body that can express various functions. It is known that the fine convex structure (pillar pattern) exhibits antibacterial and bactericidal properties against predetermined bacteria (see Non-Patent Document 1).

Conventionally, as a method for producing a fine concavo-convex structure having the fine convex structure (fine pillar pattern) capable of exhibiting various functions as described above, a fine concave structure (fine hole pattern) corresponding to the fine convex structure is used. A method of manufacturing by imprint lithography using an imprint mold having the above, a method of manufacturing by electron beam lithography, and the like are known. Since the manufacturing method by electron beam lithography requires a great deal of time and cost, the manufacturing method by imprint lithography using an imprint mold is more advantageous from the viewpoint of time and cost.

The imprint mold used for producing the fine concavo-convex structure is manufactured by, for example, electron beam lithography, and is therefore very expensive and takes a long time to manufacture. There is a demand for a new method capable of inexpensively producing the imprint mold and the fine concavo-convex structure.

As a method for producing the above-mentioned fine concavo-convex structure, metal nanoparticles conventionally produced by a micelle block copolymer nanolithography process are orderedly arranged on a substrate, and the substrate is etched using the metal nanoparticles as an etching mask to obtain a metal. A mold having a fine concavo-convex structure (fine pillar pattern) corresponding to the position of nanoparticles is produced, and a fine concavo-convex structure having the fine concavo-convex structure (fine pillar pattern) is manufactured by an etching process using the mold. A method for etching has been proposed (see Patent Document 3).

Japanese Unexamined Patent Publication No. 2011-33892 Japanese Unexamined Patent Publication No. 2015-25662 Japanese Patent Publication No. 2014-502035

“Biophysical Model of Bacterial Cell Interactions with Nanopatterned Cicada Wing Surfaces”, S. Pogodin et al., Biophysical Journal, 104, pp.835-840, 2013

In the method described in Patent Document 3, after the fine pillar pattern is formed by etching the substrate, the metal nanoparticles remaining on the substrate (on the fine pillar pattern) are removed. However, there is a problem that a part of the metal nanoparticles and deposits derived from the metal nanoparticles etched during the etching process of the substrate remain on the substrate, resulting in metal contamination. When metal contamination of the fine concavo-convex structure occurs, when the fine concavo-convex structure is an imprint mold, there is a problem that the desired fine concavo-convex structure is not formed in the product transferred by the imprint mold to which metal is attached. There is. Further, when metal contamination occurs in the product transferred by the imprint mold, desired performance (for example, optical performance) may not be obtained or environmental pollution may occur.

In view of the above problems, the present invention provides a fine concavo-convex structure that can be manufactured at low cost and that cannot cause metal contamination, and a method for manufacturing a fine convex structure and a fine concave structure. One purpose.

In order to solve the above problem, as one embodiment of the present invention, a base portion having a first surface and a second surface facing the first surface, and a plurality of base portions formed on the first surface side of the base portion. It is provided with a fine concave portion or a fine convex portion, and at least a part of the fine concave portion or the fine convex portion of the plurality of fine convex portions is the first surface of the base portion. A first region located on the side and a second region continuous with the first region are included, and the first region faces from the first surface side toward the bottom of the micro-concave portion or the tip of the micro-convex portion. Te is substantially region having the same width, the second region, the Ri region der width is gradually reduced toward the tip end portion of the bottom or the fine convex portions of the fine recesses, the said first region A circumferential step portion extending over the entire circumference of the fine concave portion or the fine convex portion is provided in a continuous portion with the second region, and the peripheral step portion is formed in a concave groove shape or a stepped shape. A fine concavo-convex structure is provided.

The second region is preferably a region in which at least the fine concave portion or the side wall of the fine convex portion is formed of a curved surface, and when the cut surface in the thickness direction of the base portion of the fine concave-convex structure is viewed. In addition, the first point on the side wall of the first region located on the bottom side of the micro-concave portion or the tip end side of the micro-convex portion, and the first region located at the axial intermediate point of the first region. The inclination of the base portion of the first line segment connecting the second point on the side wall with respect to the first surface is on the side wall of the second region located on the bottom side of the fine concave portion or the tip end side of the fine convex portion. It is preferable that the inclination of the base portion of the second line segment connecting the first point of the above and the second point on the side wall of the second region located on the base portion side with respect to the first surface is larger than the inclination.

The front Stories second region is preferably a region having a tapered and becomes pointed shape toward the tip end portion of the bottom or the fine convex portions of the fine recesses.

Wherein the first region is preferably the fine concave portion or the the height H ₁ of the width W _M and the first region of the axially intermediate portion of the fine protrusion is a region having a relation of the following formula.
1.5W _M ≤ H ₁ ≤ 5W _M
The base may be made of silicon or resin.

Further, as an embodiment of the present invention, a base portion having a first surface and a second surface facing the first surface, and a plurality of fine convex portions formed on the first surface side of the base portion are provided. A method for producing a fine convex structure, wherein a resin coating step of applying a curable resin containing silica particles on a first surface of a silicon substrate and the coating of a curable resin containing silica particles on the first surface of the silicon substrate. A resin curing step of curing the curable resin, a resin removing step of removing the cured curable resin and leaving the silica particles on the first surface, and the silicon substrate on which the silica particles remain. The first etching step of performing an anisotropic etching treatment using hydrogen bromide (HBr) as an etching gas on the first surface, and the silica remaining on the first surface of the substrate to which the etching treatment has been performed. It has a silica particle removing step of removing particles, and a second etching step of performing an isotropic etching treatment using a fluorine-based gas as an etchant on the first surface of the silicon substrate after the silica particle removing step. A method for manufacturing a fine convex structure is provided.

In the first etching step, the first surface of the silicon substrate may be etched to the extent that the silica particles are not erased. After the silica particle removing step, the first surface of the silicon substrate may be subjected to etching treatment. A second etching step of performing an etching treatment using hydrogen bromide (HBr) as an etching gas may be further provided. Further, in the first etching step, the first surface of the silicon substrate may be etched until the silica particles disappear.

As the silica particles, those having an average particle diameter of 5 nm to 300 μm can be used, and as the curable resin, a novolak-based phenol resin can be used.

Further, as one embodiment of the present invention, a fine portion including a first surface and a base portion having a second surface facing the first surface, and a plurality of fine recesses formed on the first surface side of the base portion. A method for manufacturing a concave structure, the step of transferring the plurality of fine convex portions of the fine convex structure manufactured by the method for manufacturing the fine convex structure to an imprint resin, and the plurality of steps. Provided is a method for producing a fine concave structure, which comprises a step of peeling the fine convex structure from the imprint resin on which the fine convex portion is transferred.

Furthermore, as an embodiment of the present invention, a base portion having a first surface and a second surface facing the first surface, and a plurality of fine convex portions formed on the first surface side of the base portion are provided. A method for manufacturing a fine convex structure to be provided, the step of transferring the plurality of fine recesses of the fine concave structure manufactured by the method for manufacturing the fine concave structure to an imprint resin, and the plurality of steps. Provided is a method for producing a fine convex structure, which comprises a step of peeling the fine concave structure from the imprint resin to which the fine concaves have been transferred.

According to the present invention, it is possible to provide a fine concavo-convex structure that can be manufactured at low cost and that is unlikely to cause metal contamination, and a method for manufacturing a fine convex structure and a fine concave structure.

FIG. 1 is a cut end view showing a schematic configuration of a fine concavo-convex structure (fine convex structure) according to the first embodiment of the present invention. FIG. 2 is a partially enlarged cut end view showing a schematic configuration of a fine convex portion in the fine uneven structure according to the first embodiment of the present invention. FIG. 3 is a partially enlarged cut end view showing a schematic configuration of another aspect of the fine convex portion in the fine uneven structure according to the first embodiment of the present invention. FIG. 4 is a process flow chart showing each step of the method for manufacturing a fine concavo-convex structure according to the first embodiment of the present invention on a cut end face. FIG. 5 is a cut end view showing a schematic configuration of a fine concavo-convex structure (fine convex structure) according to a second embodiment of the present invention. FIG. 6 is a partially enlarged cut end view showing a schematic configuration of a fine convex portion in the fine uneven structure according to the second embodiment of the present invention. FIG. 7 is a partially enlarged cut end view showing a schematic configuration of another aspect of the fine convex portion in the fine concave-convex structure according to the second embodiment of the present invention. FIG. 8 is a process flow chart showing each step of the method for manufacturing a fine concavo-convex structure according to a second embodiment of the present invention on a cut end face. FIG. 9 shows a process flow showing each step of a method of manufacturing a replica mold as a fine concavo-convex structure (fine concave structure) using the imprint mold 1 according to the first embodiment of the present invention on the cut end face. It is a figure. FIG. 10 shows a process flow showing each step of a method of manufacturing a replica mold as a fine concavo-convex structure (fine concave structure) using the imprint mold 1 according to the second embodiment of the present invention on the cut end face. It is a figure. FIG. 11 is a process flow chart showing each step of a method of manufacturing a fine concavo-convex structure (fine convex structure) using a replica mold according to the first embodiment of the present invention on a cut end face. FIG. 12 is a process flow chart showing each step of the method of manufacturing a fine concavo-convex structure (fine convex structure) using the replica mold in the second embodiment of the present invention on the cut end face. FIG. 13 is a cross-sectional view showing a schematic configuration of an article to which the fine concavo-convex structure according to the first and second embodiments of the present invention is applied. FIG. 14 is an exploded perspective view showing a schematic configuration of an article to which the fine concavo-convex structure according to the first and second embodiments of the present invention is applied. FIG. 15 is an SEM photograph of the fine convex portion of the imprint mold produced in Example 1 observed with an electron microscope (SEM). FIG. 16 is an SEM photograph of the fine convex portion of the imprint mold produced in Example 2 observed with an electron microscope (SEM).

Embodiments of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, in order to facilitate understanding, the shape, scale, aspect ratio, etc. of each part may be changed or exaggerated from the actual product.

The numerical range represented by using "~" in the present specification and the like means a range including each of the numerical values before and after "~" as a lower limit value and an upper limit value.

In the present specification and the like, terms such as "film", "sheet" and "board" are not distinguished from each other based on the difference in designation. For example, "board" is a concept that includes members that can be generally called "sheet" or "film".

[First Embodiment]
FIG. 1 is a cut end view showing a schematic configuration of a fine convex structure as a specific example of the fine uneven structure according to the first embodiment, and FIG. 2 is a cut end view showing a schematic configuration of the fine convex structure according to the first embodiment. FIG. 3 is a partially enlarged cut end view showing a schematic configuration of a fine convex portion in a structure, and FIG. 3 is a partially enlarged cut showing a schematic configuration of another aspect of the fine convex portion in the microconvex structure according to the first embodiment. It is an end view. In the first embodiment, an imprint mold as a fine convex structure including a fine convex portion will be described as an example, but the present invention is not limited to this embodiment. For the fine concavo-convex structure according to the first embodiment, a fine concave structure (for example, a replica mold) which is manufactured through an imprint process using the imprint mold and has fine recesses, or the replica mold is used. A fine convex structure (including, for example, an imprint mold), which is produced through the imprinting process and has a fine convex portion, may also be included.

[Imprint mold]
As shown in FIG. 1, the imprint mold 1 according to the first embodiment has a base portion 2 having a first surface 2A and a second surface 2B facing the first surface 2A, and a first surface 2A of the base portion 2. It is provided with a plurality of pillar-shaped fine convex portions 3 located on the side. The base portion 2 and the fine convex portion 3 may be made of the same material or may be made of different materials. The imprint mold 1 is, for example, a semiconductor such as silicon or gallium nitride; glass such as quartz glass, soda glass, fluorite, calcium fluoride substrate, magnesium fluoride substrate, acrylic glass; polycarbonate, polypropylene, polyethylene, silicone or the like. Resin: It may be composed of a metal such as nickel, titanium, or aluminum. When the base portion 2 and the fine convex portion 3 are made of different materials, each of the base portion 2 and the fine convex portion 3 is an arbitrary material selected from those exemplified as the materials constituting the above-mentioned imprint mold 1. It may be composed of.

The plan view shape of the base portion 2 is not particularly limited, and examples thereof include a substantially rectangular shape and a substantially circular shape. As will be described later, when the imprint mold 1 according to the first embodiment is manufactured using the silicon substrate 20 (see FIG. 4 (A)), the plan view shape of the base 2 is usually a substantially circular shape. is there.

The size of the base 2 is not particularly limited, but for example, when the plan view shape of the base 2 is a substantially circular shape, it is about 200 to 300 mmφ. The thickness T ₂ of the base 2, the intensity, considering handling properties, etc., for example, may be appropriately set within a range of about 100Myuemu～1mm.

As shown in FIG. 2, in the first embodiment, the fine convex portion 3 is located on the first surface 2A side of the base portion 2 and projects from the first surface 2A in a substantially orthogonal direction to the first surface 2A. One region 31 and a second region 32 continuous with the first region 31 are included. Here, the substantially orthogonal direction is a direction that intersects the first surface 2A at about 90 °, and includes, for example, a direction that intersects at 80 ° to 90 °.

The first region 31 is a region having substantially the same width W ₃₁ from the first surface 2A side toward the tip (top) 33 of the fine convex portion 3. The second region 32 is a region in which the width W ₃₂ gradually decreases toward the tip (top) 33 of the fine convex portion 3.

In the first embodiment, when the cut surface of the base 2 of the imprint mold 1 in the thickness direction is viewed, the first point P311 and the second point P312 on the side wall 34 of the first region 31 are connected. The inclination θ1 of the base 2 of the line segment L1 with respect to the first surface 2A is the first surface 2A of the base 2 of the second line segment L2 connecting the first point 321 and the second point 322 on the side wall 34 of the second region 32. Greater than the slope θ2 with respect to. Therefore, the first region 31 and the second region 32 of the fine convex portion 3 can also be defined by the inclinations θ1 and θ2. The slope θ1 is, for example, 75 ° to 90 °. The slope θ2 is, for example, 30 ° to 80 °. The first point P311 of the first region 31 is a point located at half the height (H _31/2 ) of the height H ₃₁ of the first region 31 from the first surface 2A of the base portion 2, and is the second. The point P312 is a point located on the most tip (top) 33 side in the first region 31. Further, the first point P321 of the second region 32 is the same point as the second point P312 of the first region 31, and the second point P322 is the height H ₃₂ from the first point P321 to the second region ₃₂ . It is a point located at half the height (H _32/2 ). The side wall 34 of the first region 31 on the side closer to the tip 33 than the first point P311 of the first region 31 is farther from the tip 33 than the first point P311 (closer to the first surface 2A of the base 2). It may have a larger inclination with respect to the first surface 2A of the base portion 2 than the side wall 34 of the first region 31 in the above. That is, the area of the cross section parallel to the first surface 2A of the base portion 2 in the first region 31 may become larger as it gets closer to the first surface 2A of the base portion 2. This is expected to increase the physical strength of the fine convex portion 3. Further, the shape of the portion where the side wall 34 of the first region 31 is continuous with the first surface 2A of the base portion 2 may be a round shape. Thereby, the stress that can be generated in the continuous portion can be dispersed.

“Having substantially the same width W ₃₁ ” in the first region 31 means that the width W ₃₁ of the first region ₃₁ is reduced in the direction from the first surface 2A side toward the tip portion 33 as compared with the second region 32. It means that the width W ₃₁ of the first region 31 does not decrease as the ratio is small or the direction from the first surface 2A side toward the tip portion 33. For example, the difference between the width W ₃₁ at the lower end of the first region 31 (the portion continuous with the first surface 2A of the base 2 in FIG. 2) and the width at the second point P312 of the first region 31 is dW ₃₁ and the second. when the difference between the width in the width and the distal end portion 33 in the first point P321 of the area 32 and dW _32, when the value of dW ₃₁ / H ₃₁ is smaller than the value of dW ₃₂ / H _32, the first region 31 It can be evaluated that the widths W _{31 of} are substantially the same. When the value of dW ₃₁ / H ₃₁ is set to half or less of the value of dW ₃₂ / H ₃₂ , the aspect ratio (height / width) of the fine convex portion 3 becomes large, and improvement of various functions is expected.

In the case where the width W ₃₁ of the first region 31 is reduced according to the direction toward the distal end portion 33 from the first surface 2A side of the base 2, dW ₃₁ / H ₃₁ is, for example, about 0.1 to 0.3 May be good. If the width W ₃₁ of the first region 31 is reduced according to the direction toward the distal end portion 33 from the first surface 2A side of the base 2, or in the case where no change in accordance with the direction, dW ₃₂ / H ₃₂ is 0.3 to 2 It may be about 0.0. By setting dW ₃₁ / H ₃₁ and dW ₃₂ / H ₃₂ in the above range, the aspect ratio (height / width) of the fine convex portion 3 can be increased as a whole, and the physical strength of the fine convex portion 3 can be increased. Can be further enhanced.

When the cut surface of the fine convex portion 3 in the thickness direction of the base portion 2 is viewed from an arbitrary direction with the tip portion 33 located upward and the base portion 2 located downward, the fine convex portions 3 are left and right. It may have a symmetrical shape or may have a left-right asymmetrical shape. The fine convex portion 3 shown in FIGS. 2 and 3 is a first region 31 on each of a first side (for example, the left side) of the cut surface and a second side (for example, the right side) facing the first side. 1st point P311 and 2nd point P312, horizontal positions of 1st point P321 and 2nd point P322 of the 2nd region, and inclination of the side wall 34 of the 1st region 31 (inclination of the base 2 with respect to the 1st surface 2A) Are substantially the same, and can be evaluated as having a symmetrical shape. In this case, the function of the plurality of fine convex portions 3 may appear isotropically. On the other hand, the first point P311 and the second point P312 of the first region 31 on the first side (for example, the left side) of the cut surface and the second side (for example, the right side) facing the first side, respectively. At least one of the horizontal positions of the first point P321 and the second point P322 of the second region and the inclination of the side wall 34 of the first region 31 (the inclination of the base 2 with respect to the first surface 2A) does not substantially match. In this case, the fine convex portion 3 can be evaluated to have a left-right asymmetrical shape. In this case, the function of the plurality of fine convex portions 3 may appear anisotropically. For example, when the shape and height of the second region 32 seen from the first side (for example, the left side) are different from the shape and height of the second region 32 seen from the second side (for example, the right side), the first The degree of function expressed by the side and the function expressed by the second side may differ.

The plan-view shape of the fine convex portion 3 is not particularly limited, but may be appropriately set according to the shape, dispersibility, and the like of the silica particles 41 described later. One aspect of the plan view shape of the fine convex portion 3 is a substantially circular shape. Further, another aspect of the plan view shape of the fine convex portion 3 is an island-shaped shape whose contour is composed of a curved line.

The dimensions of the fine convex portion 3 having a substantially circular shape in a plan view are not particularly limited. As will be described later, since the imprint mold 1 according to the first embodiment can be manufactured through an etching process using the silica particles 41 as a mask (see FIG. 4), the dimensions of the fine convex portion 3 are the silica particles. It can be set in a range according to the particle size distribution, dispersibility, etc. of 41. For example, the size of the fine convex portion 3 is about 10 nm to 300 μm. The dimensions of the fine convex portion 3 are defined by the circumscribed circle of the side wall 34 of the fine convex portion 3 in a plan view, and are a scanning electron microscope (for example, product name: SU-8000, manufactured by Hitachi High-Technologies Co., Ltd.) and a transmission type. It can be measured using an electron microscope, an atomic force microscope, or the like.

Similarly the width W ₃₁ of the first region 31, the particle size distribution of the silica particles 41 (particle size distribution) can be set in a range corresponding to the dispersibility and the like. For example, the width W ₃₁ of the first region 31 of the fine convex portion 3 is about 5 nm to 300 μm, may be about 5 to 500 nm, or may be about 10 to 300 nm. The width W ₃₁ of the first region 31 of the fine convex portion 3 is defined as the width of the portion where the first region 31 is continuous with the first surface 2A of the base portion 2, and is defined as a scanning electron microscope (for example, product name: SU). -8000, manufactured by Hitachi High-Technologies Corporation), can be measured using a transmission electron microscope, an atomic force microscope, or the like.

The height H ₃ of the fine convex portion 3 is not particularly limited. As will be described later, since the imprint mold 1 according to the present embodiment is manufactured through an etching process of the silicon substrate 20 using the silica particles 41 as a mask, the height H ₃ of the fine convex portion ₃ is the silica particles. It can be set according to the etching selection ratio between the 41 and the silicon substrate 20. For example, the height H ₃ of the fine projections 3 is about 10 to 1000 nm, may be about 50 to 800 nm, may be about 100-600 nm.

The height H ₃₁ of the first region 31 of the fine convex portion 3 can be set according to the etching selectivity between the silica particles 41 and the silicon substrate 20, the diameter of the silica particles 41, and the like. The height H ₃₂ of the second region 32 may be set according to the etching selection ratio and the like of the silica particles 41 and the silicon substrate 20. For example, the height H ₃₁ of the first region 31 can be represented by the following formula relationship in relation to the width W ₃₁ of the lower end of the fine projections 3.
1.5W ₃₁ ≤ H ₃₁ ≤ 5W ₃₁
Further, the height H ₃₁ of the first region 31 may be represented by the following formula relationship in relation to the width W ₃₁ of the lower end of the fine projections 3.
2W ₃₁ ≤ H ₃₁ ≤ 4W ₃₁

In the second region 32, at least the side wall 34 of the fine convex portion 3 is composed of a curved surface. As shown in FIG. 2, the entire second region 32 may be curved in a dome shape, and as shown in FIG. 3, the tip portion (top) 33 is a substantially flat surface (substantially referred to as the first surface 2A). It is a parallel surface), and the side wall 34 may be curved outward in a convex shape.

Width W ₃₂ of the second point P322 of the second region 32 may be, for example, about 0.1 to 0.3 times the width W ₃₁ of the lower end of the first region 31. The height H ₃₂ of the second region 32 is not particularly limited, for example, it may be about 10 nm to 100 nm. The distance D between the adjacent fine convex portions 3 is not particularly limited, but may be, for example, about 50 nm to 500 nm or about 100 nm to 250 nm. Even if there is a convex portion having a shape different from that of the fine convex portion 3 around the fine convex portion 3, the distance between the fine convex portion 3 and the convex portion is within the above range. May be good.

In the imprint mold 1 according to the first embodiment having the above-described configuration, the fine convex portion 3 has a substantially columnar shape, and the first region having substantially the same width W ₃₁ and at least the side wall along the axial direction thereof. A second region in which 34 is curved and the width W ₃₂ gradually decreases toward the tip (top) 33 is included. Therefore, a replica mold is produced through the imprint process using the imprint mold 1 according to the first embodiment, and the imprint mold 1 according to the first embodiment is produced by the imprint process using the replica mold. A fine concavo-convex structure (fine convex structure) having a fine convex portion having substantially the same shape as the fine convex portion 3 can be manufactured inexpensively and easily.

[Manufacturing method of imprint mold]
Next, an example of the method for manufacturing the imprint mold 1 according to the first embodiment will be described. FIG. 4 is a process flow chart showing each process of the imprint mold manufacturing method according to the first embodiment on the cut end face.

First, a silicon substrate 20 having a first surface 2A and a second surface 2B facing the first surface 2A is prepared, and a resist composition 40 containing silica particles 41 is applied on the first surface 20A of the silicon substrate 20 by a spin coating method or the like. Apply (see FIG. 4 (A)).

Examples of the silica particles 41 contained in the resist composition 40 include those having an average particle diameter (number average particle diameter) of 5 nm to 300 μm, preferably 5 nm to 1000 nm. The particle size distribution of the silica particles 41 is not particularly limited, but is preferably as narrow as possible. The particle size distribution of the silica particles 41 is one of the important factors that determine the shape of the fine convex portion 3, and by using the silica particles 41 having a narrow particle size distribution, the fine convex portion 3 having a desired shape is formed. This makes it possible to reduce variations in the shape of the fine convex portion 3.

Further, as the silica particles 41, those whose surface is modified with a functional group such as an alkyl group such as a methyl group, an ethyl group or an octadecyl group can be used. Since the surface of the silica particles 41 is modified with the above functional groups, the silica particles 41 can be appropriately dispersed in the resist composition 40 without agglutination. As a method of modifying the surface of the silica particles 41 with the above functional groups, for example, the surface of the silica particles is activated by subjecting the silica particles to UV ozone treatment, plasma treatment, or vacuum ultraviolet (VUV) treatment, and the surface is activated. Examples thereof include a method of immersing the converted silica particles in a silane coupling agent solution containing an alkyl group such as a methyl group, an ethyl group and an octadecyl group, or a method of exposing the silane coupling agent to a gas atmosphere.

As the resin material constituting the resist composition 40, for example, a positive type or negative type resist, a UV curable resin and the like can be used. Examples of the positive resist include those containing a novolak polymer such as a bisphenol A skeleton novolak resist, a photoacid generator, and a quencher (dissolution inhibitor), and the negative resist includes a bisphenol A skeleton novolac. Examples thereof include a novolak polymer such as a resist, a photoacid generator, and a cross-linking agent. Examples of the UV curable resin include those containing an acrylic monomer and a photoinitiator.

The resist composition 40 may contain additives such as a surfactant whose dispersibility and surface energy of the silica particles 41 can be adjusted. As a result, the silica particles 41 can be appropriately dispersed in the resist composition 40 and in the state of being applied on the first surface 20A of the silicon substrate 20 without agglutinating the silica particles 41.

Next, the resist composition 40 applied on the first surface 20A of the silicon substrate 20 is cured (see FIG. 4B). As a method for curing the resist composition 40, a method according to the curing characteristics of the resin material constituting the resist composition 40 can be adopted. For example, when the resin material constituting the resist composition 40 is an ultraviolet curable resin, the resist composition 40 can be cured by irradiating the resist composition 40 with ultraviolet UV rays.

When the resist composition 40 is cured by irradiation with ultraviolet rays and UV rays, if desired, a mask having a predetermined opening may be used for patterning. When the resin material constituting the resist composition 40 is a negative photoresist material, only the resist composition 40 in the region exposed through the opening can be cured, and the resist composition 40 can be cured on the first surface 20A of the silicon substrate 20. The fine convex portion 3 can be formed only in a desired region in the above.

Subsequently, the resin material in the resist composition 40 cured on the first surface 20A of the silicon substrate 20 is removed by ashing or the like (see FIG. 4C). As a result, the silica particles 41 can be left on the first surface 20A of the silicon substrate 20 in a state of being appropriately dispersed. In this way, the silica particles 41 are arranged directly on the first surface 20A of the silicon substrate 20. Note that the direct arrangement means that a separate mask material or the like is not interposed between the silica particles 41 and the first surface 20A of the silicon substrate 20.

Then, an anisotropic dry etching process using hydrogen bromide (HBr) as an etching gas is performed using the silica particles 41 as a mask (see FIG. 4D). In such a dry etching process, the first surface 20A side of the silicon substrate 20 is etched according to the etching selectivity of the silica particles 41 and the silicon substrate 20, and a pillar-shaped (substantially columnar) pattern is formed. At this time, the silica particles 41 are also etched, but until the silica particles 41 are etched by the radius thereof, the portion not covered by the silica particles 41 is etched along the thickness direction of the silicon substrate. , A pillar-shaped pattern is formed (see FIG. 4 (D)). After that, when the silica particles 41 are further etched, the peripheral edge of the tip of the pillar-shaped pattern covered with the silica particles 41 is etched, and the side wall is formed as a curved surface (see FIG. 4E). Then, the etching process is completed before or substantially at the same time as the silica particles 41 disappear. As a result, the fine convex portion 3 having the shape shown in FIG. 2 or 3 is formed on the first surface 20A side of the silicon substrate 20.

As described above, in the first embodiment, a pillar-shaped pattern having dimensions corresponding to the diameter of the silica particles 41 is formed until the silica particles 41 are etched by the radius thereof, and then the pillar-shaped pattern is formed. Since the peripheral edge of the tip of the pattern is etched, a fine convex portion 3 including a substantially columnar first region 31 and a second region 32 whose side wall 34 is formed of a curved surface is formed. Therefore, the width W ₃₁ of the lower end of the first region 31, the diameter of the silica particles 41 and becomes substantially the same as an etching mask, the height H ₃₁ of the first region 31 has a radius etch selectivity of the silica particles 41 It is represented by the product of. Therefore, the height H ₃₁ of the first region 31 can be represented by the following formula relationship in relation to the width W ₃₁ of the lower end of the fine projections 3.
1.5W ₃₁ ≤ H ₃₁ ≤ 5W ₃₁

Finally, using hydrofluoric acid (HF) or the like, the silica particles 41 remaining on the fine convex portion 3 are etched and removed. As a result, a fine region including a first region having substantially the same width W ₃₁ along the axial direction and a second region in which at least the side wall 34 is curved and the width W ₃₂ gradually decreases toward the tip (top) 33. An imprint mold 1 having a protrusion 3 can be manufactured.

According to the method for producing an imprint mold according to the first embodiment described above, the fine convex portion 3 having a desired shape is formed by an etching process using the silica particles 41 contained in the resist composition 40 as a mask. Therefore, the imprint mold 1 can be manufactured at low cost without causing metal contamination or the like.

[Second Embodiment]
FIG. 5 is a cut end view showing a schematic configuration of a fine convex structure as a specific example of the fine uneven structure according to the second embodiment, and FIG. 6 is a cut end view showing a schematic configuration of the fine convex structure according to the second embodiment. FIG. 7 is a partially enlarged cut end view showing a schematic configuration of a fine convex portion in a structure, and FIG. 7 is a partially enlarged cut showing a schematic configuration of another aspect of the fine convex portion in the microconvex structure according to the second embodiment. It is an end view. In the second embodiment, an imprint mold as a fine convex structure including a fine convex portion will be described as an example, but the present invention is not limited to this embodiment. For the fine concavo-convex structure according to the second embodiment, a fine concave structure (for example, a replica mold) which is manufactured through an imprint process using the imprint mold and has fine recesses, or the replica mold is used. A fine convex structure (including, for example, an imprint mold), which is produced through the imprinting process and has a fine convex portion, may also be included.

[Imprint mold]
As shown in FIG. 5, the imprint mold 1 according to the second embodiment has a base portion 2 having a first surface 2A and a second surface 2B facing the first surface 2A, and a first surface 2A of the base portion 2. It is provided with a plurality of pillar-shaped fine convex portions 3 located on the side. The base portion 2 and the fine convex portion 3 may be made of the same material or may be made of different materials. The imprint mold 1 is, for example, a semiconductor such as silicon or gallium nitride; glass such as quartz glass, soda glass, fluorite, calcium fluoride substrate, magnesium fluoride substrate, acrylic glass; polycarbonate, polypropylene, polyethylene, silicone or the like. Resin: It may be composed of a metal such as nickel, titanium, or aluminum. When the base portion 2 and the fine convex portion 3 are made of different materials, each of the base portion 2 and the fine convex portion 3 is an arbitrary material selected from those exemplified as the materials constituting the above-mentioned imprint mold 1. It may be composed of.

The plan view shape of the base portion 2 is not particularly limited, and examples thereof include a substantially rectangular shape and a substantially circular shape. As will be described later, when the imprint mold 1 according to the second embodiment is manufactured using the silicon substrate 20 (see FIG. 8A), the plan view shape of the base portion 2 is usually a substantially circular shape. is there.

The size of the base 2 is not particularly limited, but for example, when the plan view shape of the base 2 is a substantially circular shape, it is about 200 to 300 mmφ. The thickness T ₂ of the base 2, the intensity, considering handling properties, etc., for example, may be appropriately set within a range of about 100Myuemu～1mm.

As shown in FIG. 6, in the second embodiment, the fine convex portion 3 is located on the first surface 2A side of the base portion 2 and projects from the first surface 2A in a substantially orthogonal direction to the first surface 2A. One region 31 and a second region 32 continuous with the first region 31 are included. Here, the substantially orthogonal direction is a direction that intersects the first surface 2A at about 90 °, and includes, for example, a direction that intersects at 80 ° to 90 °.

The first region 31 is a region having substantially the same width W ₃₁ from the first surface 2A side toward the tip (top) 33 of the fine convex portion 3. The second region 32 is a region in which the width W ₃₂ gradually decreases toward the tip (top) 33 of the fine convex portion 3.

In the second embodiment, when the cut surface of the base 2 of the imprint mold 1 in the thickness direction is viewed, the first point P311 and the second point P312 on the side wall 34 of the first region 31 are connected. The inclination θ1 of the base 2 of the line segment L1 with respect to the first surface 2A is the first surface 2A of the base 2 of the second line segment L2 connecting the first point 321 and the second point 322 on the side wall 34 of the second region 32. Greater than the slope θ2 with respect to. Therefore, the first region 31 and the second region 32 of the fine convex portion 3 can also be defined by the inclinations θ1 and θ2. The slope θ1 is, for example, 75 ° to 90 °. The slope θ2 is, for example, 30 ° to 80 °. The first point P311 of the first region 31 is a point located at half the height (H _31/2 ) of the height H ₃₁ of the first region 31 from the first surface 2A of the base portion 2, and is the second. The point P312 is a point located on the most tip (top) 33 side in the first region 31. Further, the first point P321 of the second region 32 is a point at the same height position as the second point P312 of the first region 31, and the second point P322 is from the first point P321 to the second region 32. a point located on half the height of the height _{H 32 (H 32/2)} . The side wall 34 of the first region 31 on the side closer to the tip 33 than the first point P311 of the first region 31 is farther from the tip 33 than the first point P311 (closer to the first surface 2A of the base 2). It may have a larger inclination with respect to the first surface 2A of the base portion 2 than the side wall 34 of the first region 31 in the above. That is, the area of the cross section parallel to the first surface 2A of the base portion 2 in the first region 31 may become larger as it gets closer to the first surface 2A of the base portion 2. As a result, it is expected that the physical strength of the fine convex portion 3 will increase. Further, the shape of the portion where the side wall 34 of the first region 31 is continuous with the first surface 2A of the base portion 2 may be a round shape. Thereby, the stress that can be generated in the continuous portion can be dispersed.

“Having substantially the same width W ₃₁ ” in the first region 31 means that the width W ₃₁ of the first region ₃₁ is reduced in the direction from the first surface 2A side toward the tip portion 33 as compared with the second region 32. It means that the width W ₃₁ of the first region 31 does not decrease as the ratio is small or the direction from the first surface 2A side toward the tip portion 33. For example, the difference between the width W ₃₁ at the lower end of the first region 31 (the portion continuous with the first surface 2A of the base 2 in FIG. 6) and the width at the second point P312 of the first region 31 is dW ₃₁ and the second. when the difference between the width in the width and the distal end portion 33 in the first point P321 of the area 32 and dW _32, when the value of dW ₃₁ / H ₃₁ is smaller than the value of dW ₃₂ / H _32, the first region 31 It can be evaluated that the widths W _{31 of} are substantially the same. When the value of dW ₃₁ / H ₃₁ is set to half or less of the value of dW ₃₂ / H ₃₂ , the aspect ratio (height / width) of the fine convex portion 3 becomes large, and improvement of various functions is expected.

In the case where the width W ₃₁ of the first region 31 is reduced according to the direction toward the distal end portion 33 from the first surface 2A side of the base 2, dW ₃₁ / H ₃₁ is, for example, about 0.1 to 0.3 May be good. If the width W ₃₁ of the first region 31 is reduced according to the direction toward the distal end portion 33 from the first surface 2A side of the base 2, or in the case where no change in accordance with the direction, dW ₃₂ / H ₃₂ is 0.3 to 2 It may be about 0.0. By setting dW ₃₁ / H ₃₁ and dW ₃₂ / H ₃₂ in the above range, the aspect ratio (height / width) of the fine convex portion 3 can be increased as a whole, and the physical strength of the fine convex portion 3 can be increased. Can be further enhanced.

When the cut surface of the fine convex portion 3 in the thickness direction of the base portion 2 is viewed from an arbitrary direction with the tip portion 33 located upward and the base portion 2 located downward, the fine convex portions 3 are left and right. It may have a symmetrical shape or may have a left-right asymmetrical shape. The fine convex portion 3 shown in FIGS. 6 and 7 is a first region 31 on each of a first side (for example, the left side) of the cut surface and a second side (for example, the right side) facing the first side. 1st point P311 and 2nd point P312, horizontal positions of 1st point P321 and 2nd point P322 of the 2nd region, and inclination of the side wall 34 of the 1st region 31 (inclination of the base 2 with respect to the 1st surface 2A) Are substantially the same, and can be evaluated as having a symmetrical shape. In this case, the function of the plurality of fine convex portions 3 may appear isotropically. On the other hand, the first point P311 and the second point P312 of the first region 31 on the first side (for example, the left side) of the cut surface and the second side (for example, the right side) facing the first side, respectively. At least one of the horizontal positions of the first point P321 and the second point P322 of the second region and the inclination of the side wall 34 of the first region 31 (the inclination of the base 2 with respect to the first surface 2A) does not substantially match. In this case, the fine convex portion 3 can be evaluated to have a left-right asymmetrical shape. In this case, the function of the plurality of fine convex portions 3 may appear anisotropically. For example, when the shape and height of the second region 32 seen from the first side (for example, the left side) are different from the shape and height of the second region 32 seen from the second side (for example, the right side), the first The degree of function expressed by the side and the function expressed by the second side may differ.

The plan-view shape of the fine convex portion 3 is not particularly limited, but may be appropriately set according to the shape, dispersibility, and the like of the silica particles 41 described later. One aspect of the plan view shape of the fine convex portion 3 is a substantially circular shape. Further, another aspect of the plan view shape of the fine convex portion 3 is an island-shaped shape whose contour is composed of a curved line.

The dimensions of the fine convex portion 3 having a substantially circular shape in a plan view are not particularly limited. As will be described later, since the imprint mold 1 according to the second embodiment can be manufactured through an etching process using the silica particles 41 as a mask (see FIG. 8), the dimensions of the fine convex portion 3 are the silica particles. It can be set in a range according to the particle size distribution, dispersibility, etc. of 41. For example, the size of the fine convex portion 3 is about 10 nm to 300 μm. The dimensions of the fine convex portion 3 are defined by the circumscribed circle of the side wall 34 of the fine convex portion 3 in a plan view, and are a scanning electron microscope (for example, product name: SU-8000, manufactured by Hitachi High-Technologies Co., Ltd.) and a transmission type. It can be measured using an electron microscope, an atomic force microscope, or the like.

Similarly the width W ₃₁ of the first region 31, the particle size distribution of the silica particles 41 (particle size distribution) can be set in a range corresponding to the dispersibility and the like. For example, the width W ₃₁ of the first region 31 of the fine convex portion 3 is about 5 nm to 300 μm, may be about 5 to 500 nm, or may be about 10 to 300 nm. The width W ₃₁ of the first region 31 of the fine convex portion 3 is defined as the width of the portion where the first region 31 is continuous with the first surface 2A of the base portion 2, and is defined as a scanning electron microscope (for example, product name: SU). -8000, manufactured by Hitachi High-Technologies Corporation), can be measured using a transmission electron microscope, an atomic force microscope, or the like.

The height H ₃ of the fine convex portion 3 is not particularly limited. As will be described later, since the imprint mold 1 according to the second embodiment can be manufactured through an etching process of the silicon substrate 20 using the silica particles 41 as a mask, the height H ₃ of the fine convex portion ₃ is set. It can be set according to the etching selectivity of the silica particles 41 and the silicon substrate 20. For example, the height H ₃ of the fine projections 3 is about 10 to 1000 nm, may be about 50 to 800 nm, may be about 100-600 nm.

The height H ₃₁ of the first region 31 of the fine convex portion 3 can be set according to the etching selectivity between the silica particles 41 and the silicon substrate 20, the diameter of the silica particles 41, and the like. The height H ₃₂ of the second region 32 may be set according to the etching selection ratio and the like of the silica particles 41 and the silicon substrate 20. For example, the height H ₃₁ of the first region 31 can be represented by the following formula relationship in relation to the width W ₃₁ of the lower end of the fine projections 3.
1.5W ₃₁ ≤ H ₃₁ ≤ 5W ₃₁
Further, the height H ₃₁ of the first region 31 may be represented by the following formula relationship in relation to the width W ₃₁ of the lower end of the fine projections 3.
2W ₃₁ ≤ H ₃₁ ≤ 4W ₃₁

In the imprint mold 1 according to the second embodiment, the tip (top) 33 of the second region 32 of the fine convex portion 3 has a sharpened shape. Since the tip (top) 33 of the fine convex portion 3 has a sharpened shape, it becomes easy to release the mold from the imprint resin during the imprint process using the imprint mold 1.

In the second embodiment, the continuous portion between the first region 31 and the second region 32 is provided with a circumferential step portion 35 extending over substantially the entire circumference of the fine convex portion 3. By providing such a circumferential step portion 35, it is possible to increase the area density of the sharp-edged shape in a plan view, particularly in the embodiment shown in FIG. 6, which can be obtained by using the imprint mold 1. It is expected that the antibacterial action will be improved in resin sheets and the like. It is considered that it is difficult for certain bacteria to form a scaffold on the fine convex portion 3 having a sharp shape, whereby the growth of the bacteria can be suppressed.

As shown in FIG. 6, the peripheral step portion 35 may be configured in a concave groove shape that opens toward the tip portion (top) 33 side, or as shown in FIG. 7, it is configured in a stepped shape. You may be. The shape of the circumferential step portion 35 can be adjusted by adjusting the etching conditions in the method for manufacturing the imprint mold 1 described later.

The width W ₃₅ of the circumferential step portion 35 is not particularly limited, and may be, for example, about 1 nm to 30 nm or about 3 nm to 20 nm. The width W ₃₅ of the circumferential step portion 35 can be measured using a scanning electron microscope (for example, product name: SU-8000, manufactured by Hitachi High-Technologies Corporation), a transmission electron microscope, an atomic force microscope, or the like. ..

Width W ₃₂ of the second point P322 of the second region 32 may be, for example, about 0.1 to 0.3 times the width W ₃₁ of the lower end of the first region 31. The height H ₃₂ of the second region 32 is not particularly limited, for example, it may be about 10 nm to 100 nm. The distance D between the adjacent fine convex portions 3 is not particularly limited, but may be, for example, about 50 nm to 500 nm or about 100 nm to 250 nm. Even if there is a convex portion having a shape different from that of the fine convex portion 3 around the fine convex portion 3, the distance between the fine convex portion 3 and the convex portion is within the above range. May be good.

In the imprint mold 1 according to the second embodiment having the above-described configuration, the fine convex portion 3 has a substantially columnar shape, and the first region having substantially the same width W ₃₁ and the tip portion along the axial direction thereof. It includes a second region in which the width W ₃₂ gradually decreases toward (top) 33. Therefore, a replica mold is produced through the imprint process using the imprint mold 1 according to the second embodiment, and the imprint mold 1 according to the first embodiment is produced by the imprint process using the replica mold. A fine concavo-convex structure (fine convex structure) having a fine convex portion having substantially the same shape as the fine convex portion 3 can be manufactured inexpensively and easily.

[Manufacturing method of imprint mold]
Next, an example of the method for manufacturing the imprint mold 1 according to the second embodiment will be described. FIG. 8 is a process flow chart showing each process of the imprint mold manufacturing method according to the second embodiment on the cut end face.

First, a silicon substrate 20 having a first surface 2A and a second surface 2B facing the first surface 2A is prepared, and a resist composition 40 containing silica particles 41 is applied onto the first surface 20A of the silicon substrate 20 by a spin coating method. (See FIG. 8 (A)).

Examples of the silica particles 41 contained in the resist composition 40 include those having an average particle diameter (number average particle diameter) of 5 nm to 300 μm, preferably 5 nm to 1000 nm. The particle size distribution of the silica particles 41 is not particularly limited, but is preferably as narrow as possible. The particle size distribution of the silica particles 41 is one of the important factors that determine the shape of the fine convex portion 3, and by using the silica particles 41 having a narrow particle size distribution, the fine convex portion 3 having a desired shape is formed. This makes it possible to reduce variations in the shape of the fine convex portion 3.

Further, as the silica particles 41, those whose surface is modified with a functional group such as an alkyl group such as a methyl group, an ethyl group or an octadecyl group can be used. Since the surface of the silica particles 41 is modified with the above functional groups, the silica particles 41 can be appropriately dispersed in the resist composition 40 without agglutination. As a method of modifying the surface of the silica particles 41 with the above functional groups, for example, the surface of the silica particles is activated by subjecting the silica particles to UV ozone treatment, plasma treatment, or vacuum ultraviolet (VUV) treatment, and the surface is activated. Examples thereof include a method of immersing the converted silica particles in a silane coupling agent solution containing an alkyl group such as a methyl group, an ethyl group and an octadecyl group, or a method of exposing the silane coupling agent to a gas atmosphere.

As the resin material constituting the resist composition 40, for example, a positive type or negative type resist, a UV curable resin and the like can be used. Examples of the positive resist include those containing a novolak polymer such as a bisphenol A skeleton novolak resist, a photoacid generator, and a quencher (dissolution inhibitor), and the negative resist includes a bisphenol A skeleton novolac. Examples thereof include a novolak polymer such as a resist, a photoacid generator, and a cross-linking agent. Examples of the UV curable resin include those containing an acrylic monomer and a photoinitiator.

The resist composition 40 may contain additives such as a surfactant whose dispersibility and surface energy of the silica particles 41 can be adjusted. As a result, the silica particles 41 can be appropriately dispersed in the resist composition 40 and in the state of being applied on the first surface 20A of the silicon substrate 20 without agglutinating the silica particles 41.

Next, the resist composition 40 applied on the first surface 20A of the silicon substrate 20 is cured (see FIG. 8B). As a method for curing the resist composition 40, a method according to the curing characteristics of the resin material constituting the resist composition 40 can be adopted. For example, when the resin material constituting the resist composition 40 is an ultraviolet curable resin, the resist composition 40 can be cured by irradiating the resist composition 40 with ultraviolet UV rays.

When the resist composition 40 is cured by irradiation with ultraviolet rays and UV rays, if desired, a mask having a predetermined opening may be used for patterning. When the resin material constituting the resist composition 40 is a negative photoresist material, only the resist composition 40 in the region exposed through the opening can be cured, and the resist composition 40 can be cured on the first surface 20A of the silicon substrate 20. The fine convex portion 3 can be formed only in a desired region in the above.

Subsequently, the resin material in the resist composition 40 cured on the first surface 20A of the silicon substrate 20 is removed by ashing or the like (see FIG. 8C). As a result, the silica particles 41 can be left on the first surface 20A of the silicon substrate 20 in a state of being appropriately dispersed. In this way, the silica particles 41 are arranged directly on the first surface 20A of the silicon substrate 20. Note that the direct arrangement means that a separate mask material or the like is not interposed between the silica particles 41 and the first surface 20A of the silicon substrate 20.

Then, an anisotropic dry etching process using hydrogen bromide (HBr) as an etching gas is performed using the silica particles 41 as a mask (see FIG. 8D). In such a dry etching process, the first surface 20A side of the silicon substrate 20 is etched according to the etching selectivity of the silica particles 41 and the silicon substrate 20, and a pillar-shaped (substantially columnar) pattern is formed. At this time, the silica particles 41 are also etched, but the portion not covered by the silica particles 41 is etched along the thickness direction of the silicon substrate 20 until the silica particles 41 are etched by the radius thereof. Therefore, a pillar-shaped pattern is formed.

When the silica particles 41 are etched by the radius thereof, the anisotropic dry etching process is completed, and the remaining silica particles 41 are removed by using hydrofluoric acid (HF) or the like. Then, an isotropic etching process using a fluorine-based gas such as CF ₄ or SF ₆ as an etchant is performed (see FIG. 8 (E)). By isotropic etching, the tip of the pillar-shaped pattern is etched so as to have a tapered shape, while the deposits during the anisotropic dry etching process are attached to the side wall of the pillar-shaped pattern. , The deposit reduces the etching rate of the side wall of the pillar-shaped pattern. As a result, the circumferential step portion 35 is formed in the continuous portion between the first region 31 and the second region 32. In this way, the fine convex portion 3 having the shape shown in FIG. 6 or 7 is formed.

According to the method for producing an imprint mold according to the second embodiment described above, the fine convex portion 3 having a desired shape is formed by an etching process using the silica particles 41 contained in the resist composition 40 as a mask. Therefore, the imprint mold 1 can be manufactured at low cost without causing metal contamination or the like.

[Manufacturing method of fine uneven structure]
A method for manufacturing a fine concavo-convex structure using the imprint mold 1 according to the first and second embodiments will be described. FIG. 9 is a process flow chart showing each step of a method of manufacturing a replica mold as a fine concavo-convex structure (fine concave structure) using the imprint mold 1 according to the first embodiment on the cut end face. FIG. 10 is a process flow chart showing each step of a method of manufacturing a replica mold as a fine concavo-convex structure (fine concave structure) using the imprint mold 1 according to the second embodiment on the cut end face. FIG. 11 is a process flow chart showing each step of the method of manufacturing a fine concavo-convex structure (fine convex structure) using the replica mold in the first embodiment on the cut end face. It is a process flow chart which shows each process of the method of manufacturing the fine concavo-convex structure (fine convex structure) by using the replica mold in 2nd Embodiment by the cut end face. Examples of the fine concavo-convex structure (fine convex structure) 1'' manufactured as described below include an antibacterial sheet, a sterilization sheet, a structure for DNA analysis, a plasmon resonance structure, and a microchannel. Examples thereof include antireflection films such as moth-eye films, cell culture sheets, cell separation devices, and imprint molds.

First, a replica mold 1'as a fine concave structure used for manufacturing the fine concave-convex structure 1 "is manufactured by using the imprint mold 1 according to the first and second embodiments. As shown in FIGS. 9A and 10A, the fine convex portion 3 formed on the first surface 2A side of the base portion 2 of the imprint mold 1 according to the first and second embodiments is upward. The imprint mold 1 is placed toward the surface, and a curable resin material 10'such as an epoxy resin, a phenol resin, a polyimide resin, a polysulfone resin, a polyester resin, or a polycarbonate resin is placed on the first surface 2A side. Apply to.

Next, as shown in FIGS. 9 (B) and 10 (B), the curable resin material 10'applied to the first surface 2A side is cured, and then the imprint mold 1 is peeled off. As a result, the replica mold 1'with a base portion 2'having a first surface 2A'and a second surface 2B' facing the first surface 2A'and a fine recess 3'formed on the first surface 2A' side of the base portion 2' Is produced. The fine concave portion 3'corresponds to the fine convex portion 3 ″ required for the fine concave-convex structure 1 ″.

Subsequently, as shown in FIGS. 11A and 12A, a curable resin such as an epoxy resin, a phenol resin, a polyimide resin, a polysulfone resin, a polyester resin, or a polycarbonate resin 10'' The fine recess 3'of the replica mold 1'is transferred to. Then, as shown in FIGS. 11B and 12B, the replica mold 1'is peeled off from the cured resin 10''. As a result, a base portion 2 ″ having a first surface 2A ″ and a second surface 2B ″ facing the first surface 2A ″ and a fine convex portion 3 ″ formed on the first surface 2A ″ side of the base portion 2 ″ are formed. A fine concavo-convex structure (fine convex structure) 1 ″ including the above can be manufactured.

The fine concavo-convex structure 1 ″ manufactured as described above has a fine convex portion 3 ″ having substantially the same shape as the fine convex portion 3 of the imprint mold 1 according to the first and second embodiments. Therefore, according to the fine concavo-convex structure 1 ″ obtained from the imprint mold 1 according to the first embodiment, by forming the fine concavo-convex structure 1 ″ in a film shape, it can be used as an antireflection film or the like. can do. Further, according to the fine concavo-convex structure 1 ″ obtained from the imprint mold 1 according to the second embodiment, the fine concavo-convex structure 1 ″ is formed into a film and used as an antibacterial sheet or the like. be able to.

[Application example]
An example of an article (product) to which the fine concavo-convex structure according to the first and second embodiments is applied will be described. FIG. 13 is a cross-sectional view showing a schematic configuration of an article to which the fine concavo-convex structure according to the first and second embodiments is applied, and FIG. 14 is a cross-sectional view showing the fine concavo-convex structure according to the first and second embodiments. It is an exploded perspective view which shows the schematic structure of the article to which.

The articles shown in FIGS. 13 and 14 are, for example, a display 100 as a display panel 101 and a fine concavo-convex structure 1 according to the first and second embodiments provided on the display panel 101. It includes a functional sheet 102. The functional sheet 102 is, for example, an antireflection sheet or an antiglare sheet. The display panel 101 of the display 100 is arranged on the second surface 2B side of the base portion 2 of the fine concavo-convex structure 1. In the functional sheet 102 in FIGS. 13 and 14, the fine convex portion 3 is not shown. The shaded area in FIG. 14 represents the area where the fine convex portion 3 is provided.

The functional sheet 102 (fine concavo-convex structure 1) shown in FIGS. 13 and 14 selectively has a fine convex portion 3 at a position corresponding to the display portion 101A of the display panel 101 of the display 100, and the display panel. The fine convex portion 3 is not provided at the position corresponding to the outer peripheral portion 101B of the 101. According to this application example, the antireflection performance or the antiglare performance can be selectively imparted only to the position corresponding to the display unit 101A of the display panel 101 of the display 100.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

In the first and second embodiments, the first region having substantially the same width W ₃₁ and at least the side wall 34 are curved along the axial direction, and the width W ₃₂ is formed toward the tip (top) 33. Although the fine concavo-convex structure (imprint mold 1) including the fine concavo-convex portion 3 including the gradually decreasing second region has been described as an example, the fine concavo-convex structure of the present invention has the fine concavo-convex portion 3 of the above shape or As long as the micro-concave 3 having a corresponding shape is provided, the micro-convex or the micro-concave having another shape (for example, substantially columnar shape, substantially conical shape, etc.) may be provided.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the present invention is not limited to the following Examples and the like.

[Example 1]
A resist composition containing silica particles (average particle diameter (number average particle diameter): 100 nm) and a novolak-based phenol polymer is applied by spin coating on the first surface of a silicon substrate (200 mmφ) having a substantially circular shape in a plan view. Then, a resist composition film was formed.

The resist composition film on the first surface of the silicon substrate was irradiated with ultraviolet rays to cure the resist composition, and the cured product of the resist composition was removed by an ashing treatment with oxygen plasma. After removing the cured product of the resist composition, silica particles remained on the first surface of the silicon substrate in an appropriately dispersed state.

The silicon substrate was subjected to an anisotropic dry etching process using hydrogen bromide (HBr) as an etching gas, and the dry etching process was completed before the silica particles disappeared. Then, the silica particles remaining on the tip (top) of the fine convex portion formed on the first surface of the silicon substrate were removed by etching with hydrofluoric acid (HF).

The fine convex portion of the imprint mold thus produced was observed with an electron microscope (SEM). The SEM photograph by the electron microscope is shown in FIG. As shown in FIG. 15, the dry etching process using the silica particles as a mask is performed, and the dry etching process is completed before the silica particles disappear, so that the width W ₃₁ is substantially the same along the axial direction. An imprint mold including a first region of the above and a second region in which at least the side wall 34 is curved and the width W ₃₂ gradually decreases toward the tip (top) 33, and includes a fine convex portion 3 having the shape shown in FIG. It was confirmed that it can be manufactured.

[Example 2]
The anisotropic dry etching process is completed before 1/2 of the average particle size of the silica particles is etched, the remaining silica particles are removed by etching with hydrofluoric acid (HF), and CF ₄ is further added. An imprint mold was produced in the same manner as in Example 1 except that the isotropic etching treatment used as an etchant was performed.

The fine convex portion of the imprint mold thus produced was observed with an electron microscope (SEM). The SEM photograph by the electron microscope is shown in FIG. As shown in FIG. 16, by performing a dry etching process using the silica particles as a mask and performing an isotropic etching process after removing the silica particles in the middle, the width W ₃₁ is substantially the same along the axial direction. FIG. 6 includes a first region, a second region in which the width W ₃₂ gradually decreases toward the tip (top) 33, and a circumferential step portion located at a continuous portion between the first region and the second region. It was confirmed that an imprint mold having the fine convex portion 3 having the shape shown can be manufactured.

1 ... Imprint mold (fine uneven structure)
1'... Replica mold (fine concave structure)
1'' ... Fine convex structure 2,2', 2'' ... Base 2A, 2A', 2A'' ... First surface 2B, 2B', 2B'' ... Second surface 3,3'' ... Fine Convex 31 ... 1st region 32 ... 2nd region 33 ... Tip 3'... Micro concave

Claims (13)

A base having a first surface and a second surface facing the first surface,
It is provided with a plurality of fine concave portions or fine convex portions formed on the first surface side of the base portion.
At least a part of the fine recesses of the plurality of fine recesses or at least a part of the fine convex portions of the plurality of fine convex portions are the first region located on the first surface side of the base portion and the said first region. Including the second region continuous with the first region,
The first region is a region having substantially the same width from the first surface side toward the bottom of the micro-concave portion or the tip of the micro-convex portion.
Said second region, Ri region der width is gradually reduced in accordance with the bottom or toward the tip portion of the fine protrusion of the fine recesses,
In the continuous portion between the first region and the second region, a circumferential step portion extending over the entire circumference of the fine concave portion or the fine convex portion is provided.
The circumferential step portion is a fine concavo-convex structure having a concave groove shape or a stepped shape . The fine concavo-convex structure according to claim 1, wherein the second region is a region in which at least the fine concave portion or the side wall of the fine convex portion is formed of a curved surface. When the cut surface of the fine concavo-convex structure in the thickness direction of the base is viewed, the first point on the side wall of the first region located on the bottom side of the fine concave portion or the tip end side of the fine convex portion. And the inclination of the base portion of the first line segment connecting the second point on the side wall of the first region located at the axial intermediate point of the first region with respect to the first surface is the bottom side of the fine recess. Alternatively, a second line segment connecting a first point on the side wall of the second region located on the tip end side of the fine convex portion and a second point on the side wall of the second region located on the base side. The fine concavo-convex structure according to claim 1 or 2, which is larger than the inclination of the base portion with respect to the first surface. The fine concavo-convex structure according to any one of claims 1 to 3, wherein the second region is a region having a sharpened shape that tapers toward the bottom of the fine concave portion or the tip end portion of the fine convex portion. Said first region, said axial height of the width W _M and the first area of the intermediate portion H ₁ of the fine concave portion or the fine convex portions is a region having a relation of the following formula, according to claim 1 The fine concavo-convex structure according to any one of 4 .
1.5W _M ≤ H ₁ ≤ 5W _M The fine concavo-convex structure according to any one of claims 1 to 5 , wherein the base is made of silicon. The fine concavo-convex structure according to any one of claims 1 to 5 , wherein the base is made of a resin. A method for manufacturing a fine convex structure including a base portion having a first surface and a second surface facing the first surface, and a plurality of fine convex portions formed on the first surface side of the base portion. There,
A resin coating process in which a curable resin containing silica particles is applied onto the first surface of a silicon substrate, and
A resin curing step of curing the curable resin applied on the first surface of the silicon substrate, and
A resin removing step of removing the cured curable resin and leaving the silica particles on the first surface.
A first etching step of performing an anisotropic etching process using hydrogen bromide (HBr) as an etching gas on the first surface of the silicon substrate on which the silica particles remain.
A silica particle removing step of removing the silica particles remaining on the first surface of the silicon substrate subjected to the etching treatment .
A fine convex structure having a second etching step of performing an isotropic etching process using a fluorine-based gas as an etchant on the first surface of the silicon substrate after the silica particle removing step. Manufacturing method. The method for producing a fine convex structure according to claim 8 , wherein in the first etching step, the first surface of the silicon substrate is etched so as not to eliminate the silica particles. The method for producing a fine convex structure according to claim 8 or 9 , wherein the average particle size of the silica particles is 5 nm to 300 μm. The method for producing a fine convex structure according to any one of claims 8 to 10 , wherein the curable resin is a novolak-based phenol resin. A method for producing a fine concave structure including a base portion having a first surface and a second surface facing the first surface, and a plurality of fine concave portions formed on the first surface side of the base portion. ,
A step of transferring the plurality of fine convex portions of the fine convex structure manufactured by the manufacturing method according to any one of claims 8 to 11 to an imprint resin.
A method for producing a fine concave structure, comprising a step of peeling the fine convex structure from the imprint resin to which the plurality of fine convex portions are transferred. A method for manufacturing a fine convex structure including a base portion having a first surface and a second surface facing the first surface, and a plurality of fine convex portions formed on the first surface side of the base portion. There,
A step of transferring the plurality of fine recesses of the fine concave structure manufactured by the manufacturing method according to claim 12 to an imprint resin.
A method for producing a fine convex structure, comprising a step of peeling the fine concave structure from the imprint resin to which the plurality of fine concaves have been transferred.