JP2010143161A - Mold, optical substrate, and method for manufacturing the mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To devise a mold and a method for manufacturing the mold, so that an antireflective fine structure can be accurately formed by transfer on an optical substrate without extension of the temperature cycle in injection molding of the optical substrate or the pressure retaining time in filling of resin, or the like. <P>SOLUTION: The mold includes a plurality of fine structure mold bodies, each having at least one of a protruding shape and a recessed shape for forming the antireflective fine structure by transfer on a surface of the optical substrate. A protruding connecting mold part for connecting adjacent protruding fine structure mold bodies or a recessed connecting mold part for connecting adjacent protruding fine structure mold bodies is formed each between the fine structure mold bodies. The height dimension of the protruding connecting mold part is smaller than the height dimension of the protruding fine structure mold bodies, and the depth dimension of the recessed connecting mold part is smaller than the depth dimension of the recessed fine structure mold bodies. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mold, an optical substrate, and a method for manufacturing the mold, and in particular, a mold for molding an optical substrate on which a microstructure for antireflection treatment is formed, and a microstructure for antireflection treatment is formed on the surface. The present invention relates to a manufactured optical substrate and a method for manufacturing the mold.

In general, in an optical substrate using a light-transmitting material, a surface treatment is performed on a light incident surface of the optical substrate in order to prevent reflection of incident light. As such a surface treatment, there are a process of laminating a dielectric thin film on the surface of the optical substrate by a vacuum deposition method or the like, and a process of forming a fine uneven pattern (fine structure) on the surface of the optical substrate.
The antireflection treatment for forming a fine concavo-convex pattern on the surface of the optical substrate is performed by molding a mold having a microstructure structure that transfers the concavo-convex pattern onto the surface when an optical substrate is manufactured by injection molding an optical synthetic resin. It is realized by using. Here, the optical substrate means a substrate for an optical element, a photoelectric conversion device, or a light emitting device.
In Patent Document 1 below, in order to improve transferability when an optical element on which a fine pattern is formed is produced by injection molding, a fine pattern (resist pattern) having conical irregularities is formed on a substrate. A silicon dioxide film is formed at the tip of the fine pattern and a wide width portion is provided at the tip. After the metal for the mold is deposited on the substrate on which this pattern is formed, the substrate is removed and the tip is over. There is described a method for forming a mold (stamper) having a fine pattern having a hung large portion.

The outline of this conventional mold manufacturing method is as follows (see FIG. 15; FIG. 15 is the same as FIG. 2 of the following patent document). Silicon dioxide films 33 and 34 are formed at the tip of the convex portion of the fine pattern (resist pattern) formed on the substrate to form a large portion 61 at the tip, and an electrolytic nickel layer is formed on the substrate 3, The back surface is polished to form a metal layer 6 that becomes a mold (stamper) having a predetermined thickness. Thereafter, the resist pattern 32 and the silicon dioxide film 33 are removed from the metal layer 6, whereby a hollow region of the overhanging large portion 61 is formed at the tip of the fine groove.
As described above, since the overhang-shaped large portion 61 is formed at the tip of the concave groove of the fine pattern, the resin melted when the optical element 70 having the antireflection structure 71 filled with the resin 7 is injection molded. Is filled at a high filling rate up to the tip of the groove.
JP 2007-9839 A

However, in the fine pattern with the conical unevenness according to the conventional technique, the pattern size is small and the aspect ratio which is the ratio of the pattern width or pattern diameter to the pattern height is large. If this aspect ratio is large, the melted resin has a high viscosity, and therefore the resin is not sufficiently filled in the concave / convex pattern of the mold. Therefore, there is a case where transfer becomes defective and sufficient antireflection characteristics cannot be obtained for the molded optical element. Conventionally, in order to prevent such a situation and improve the transferability of fine structures, the temperature cycle and the pressure holding time at the time of resin filling have been lengthened. For this reason, optical elements are produced in large quantities. The production efficiency at the time of doing so is poor, which leads to an increase in cost.
An object of the present invention is to prevent the above problems from occurring, and without increasing the temperature cycle, the pressure holding time during resin filling, etc., the antireflection microstructure on the optical substrate is highly accurate. An object of the present invention is to devise a mold and a method for manufacturing the mold so that the transfer can be formed.

According to the first aspect of the present invention, a plurality of fine structure molds having at least one of a convex shape and a concave shape forming an antireflection fine structure are formed on the surface of an optical substrate formed by transfer. In the molded mold, between the fine structure molds, a convex connection mold part connecting adjacent convex fine structure molds or a concave connection mold connecting adjacent convex fine structure molds. A height dimension of the convex coupling mold part is smaller than a height dimension of the convex microstructured mold body, and a depth dimension of the concave coupling mold part is the concave shape. The mold is characterized by being formed smaller than the depth dimension of the microstructured body.
The convex shape is a convex shape with respect to the mold surface, and the concave shape is a concave shape with respect to the mold surface.
According to a second aspect of the present invention, in the mold according to the first aspect, the shape of the microstructure structure is any one of a columnar shape, a conical shape, and a truncated cone shape.

According to a third aspect of the present invention, in the mold according to the first or second aspect, the plurality of fine structure molds are configured as a single block, and a width dimension of the connecting mold portion is between the plurality of blocks. A convex or concave segmented linear part having a larger width dimension and separating the blocks is arranged.
According to a fourth aspect of the present invention, in the mold according to any one of the first to third aspects, the fine structure mold is for forming an antireflection structure of an optical substrate to be molded. The mold body is formed at a pitch equal to or less than the wavelength of the light whose reflection should be suppressed, and the height dimension of the convex microstructure structure body or the depth dimension of the concave microstructure structure body, and the convexity. The ratio of the height dimension of the connecting part of the shape or the depth dimension of the connecting part of the concave shape is 2.5 to 5.

  According to a fifth aspect of the present invention, there is provided an optical substrate in which a plurality of microstructures having at least one of an antireflection convex shape and a concave shape are formed on a surface, and adjacent convex shapes are formed between the microstructures. A convex connecting portion for connecting the microstructures or a concave connecting portion for connecting adjacent concave microstructures is formed, and the height of the convex connecting portion is the height of the convex shape. The optical substrate is characterized in that it is smaller than the height dimension of the microstructure and the depth dimension of the concave connecting portion is smaller than the depth dimension of the concave microstructure.

  The invention according to claim 6 is the optical substrate according to claim 5, wherein the optical substrate is made of a synthetic resin having translucency.

  Invention of Claim 7 is the manufacturing method of the mold of Claim 1, Comprising: The process of forming the inorganic resist layer which consists of a pattern formation layer on a board | substrate, The said microstructure of a convex shape or a concave shape, A step of forming a latent image by changing the irradiation power of the laser beam according to a formation pattern of the convex connection mold part and the concave connection mold part, and a fine structure of the convex shape or the concave shape by an etching process A step of forming a mold body, the convex connection mold part or the concave connection mold part, and etching the substrate using the pattern as a mask to form a convex or concave microstructured structure body, the convex connection A method for manufacturing a mold, comprising: a step of forming a mold portion or the concave connecting mold portion; and a step of removing the mask.

The invention of claim 8 is characterized in that, in the mold according to claim 3, the segmented line-shaped portion is formed radially from the mold center.
The above-mentioned “sectioned linear portion” means a convex or concave structure that divides the block, “mold center” means the center of the mold, and “radially formed” means formed radially. To do.

A ninth aspect of the present invention is the mold according to the third aspect, characterized in that a sectional shape of the segmented line-shaped portion is U-shaped.
The above-mentioned “cross-sectional shape is U-shaped” means that the cross-sectional shape in the orthogonal direction of the segmented line-shaped portion is U-shaped.

  A tenth aspect of the present invention is the mold manufacturing method according to the seventh aspect, wherein in the step of etching the substrate using the pattern as a mask, the step of etching the mask and the step of etching the substrate are repeated. It is a mold manufacturing method characterized by forming a concave-shaped structure.

  According to an eleventh aspect of the present invention, in the mold according to any one of the first to fourth, eighth, and ninth aspects, irregularities smaller than the structure are randomly formed in a region where the fine structure, the connection mold portion, and the segmented line mold portion are not formed. It is characterized by being formed.

  According to a twelfth aspect of the present invention, in the mold manufacturing method according to the seventh aspect, in the step of etching the substrate using the pattern as a mask, etching is performed so that the light absorption layer in a region where the pattern is not formed remains in an island shape. The mold manufacturing method is characterized in that, by performing etching and etching the substrate using the island-shaped light absorption layer and the initial pattern as a mask, the unevenness and the structure smaller than the structure are formed at the same time.

[Invention of Claim 1]
According to the first aspect of the present invention, there is provided a microstructured body having at least one of a convex shape and a concave shape that forms an antireflection microstructure on the surface of an optical substrate that is transferred and formed. In a plurality of formed molds, between the microstructured molds formed on the surface of the mold, a convex coupling mold part that couples adjacent convex microstructured molds, or adjacent convex microstructures Concave-shaped connecting mold parts that connect the mold bodies are formed, and the height dimensions of these convex-shaped connecting mold parts are smaller than the height dimension of the convex microstructured mold body, and the concave-shaped connecting mold parts Since the depth dimension is smaller than the depth dimension of the concave microstructured mold body, the synthetic resin flows along the convex connection mold part or the concave connection mold part when molding the optical substrate. So the resin melted in the mold is sufficiently and quickly It is filled. Therefore, the transferability of the uneven microstructure is improved, and a highly accurate microstructure for preventing reflection of the optical substrate is formed.

[Invention of Claim 2]
According to the invention of claim 2, the shape of the microstructure structure of the mold is any one of a cylindrical shape, a cone shape, a truncated cone shape, a prismatic shape, a pyramid shape, and a truncated pyramid shape. A fine structure having an appropriate shape can be formed on the surface of the optical substrate in accordance with the specifications that require the required antireflection treatment.
The advantage of the conical shape and the truncated cone shape is easy to manufacture by the interference exposure method direct drawing method. In addition, the advantage of the prismatic shape and the prismatic trapezoidal shape is that a fine structure can be formed without gaps compared to the conical shape and the truncated cone shape, so that a high antireflection effect can be obtained.

[Invention of Claim 3]
According to the third aspect of the present invention, since the fine structure mold body of the mold is formed as a block, and the segmented linear part wider than the coupling mold part is disposed between the blocks, the synthetic resin is connected from the segmented linear part. It tends to flow to the mold part and further to the microstructure. Therefore, the fluidity of the synthetic resin is further improved during the molding of the optical substrate, so that the transferability of the microstructured structure is improved, and the microstructure for preventing reflection of the optical substrate is formed with high accuracy.

[Invention of Claim 4]
According to the mold of claim 4, the fine structure mold is formed at a pitch equal to or less than the wavelength of the light whose reflection should be suppressed, and the height of the convex fine structure mold or the concave fine structure is formed. The ratio between the depth dimension of the structural mold and the height dimension of the convex connecting mold part or the depth dimension of the concave connecting mold part maintains the antireflection function and improves transferability. It is set to 2.5 to 5 to obtain an effect. Therefore, the transferability is good, and the optical substrate based thereon can exhibit the desired antireflection effect.

[Invented in claim 5]
According to the invention described in claim 5, between the microstructures of the optical substrate, a convex connection part that connects adjacent convex microstructures or a recess that connects adjacent convex microstructures. A connecting portion having a shape is formed, the height dimension of the convex connecting portion is smaller than the height dimension of the convex microstructure, and the depth size of the concave connecting portion is that of the concave microstructure. Since it is formed smaller than the depth dimension, the synthetic resin is quickly and sufficiently filled into the mold at the time of manufacturing the optical substrate without impairing the antireflection effect. Thereby, transferability is improved, a fine structure for antireflection is formed with high accuracy, and a desired antireflection effect can be exhibited.

[Invention of Claim 6]
According to invention of Claim 6, since the optical substrate is shape | molded with the synthetic resin which has translucency, optical substrates, such as an optical element, a photoelectric conversion device, or a board | substrate for light emitting devices, can be replicated in large quantities. Manufacturing cost can be reduced.

[Invention of Claim 7]
According to the invention of claim 7, since the pattern is formed on the mold by heat mode lithography, a structure in which the connecting mold part is formed between the fine structure molds can be manufactured more easily than other methods, and the cost is reduced. can do.

[Invention of Claim 8]
According to the eighth aspect of the present invention, since the segmented linear part in the mold is formed radially from the mold center, the molten resin injected toward the mold center easily flows to the outer periphery along the segmented linear part. Become.

[Invention of Claim 9]
According to the ninth aspect of the present invention, since the sectional shape of the parting line mold portion in the mold is U-shaped, it is possible to reduce transfer defects caused by being caught by the resin substrate mold at the time of release.

[Invention of Claim 10]
According to the invention of claim 10, in the mold manufacturing method, the structure is formed by repeating the etching process of the inorganic resist layer and the light absorption layer and the etching process of the substrate, so that the height and taper angle of the structure are set. It can be controlled easily.

[Invention of Claim 11]
According to the eleventh aspect of the present invention, since the unevenness finer than the structure is formed in a flat region where the structure is not formed, a resin having fluidity such as a molten resin is used in the substrate transfer step. The unevenness is not filled, and the resin comes into contact with the protrusions.
Therefore, when transferring to the resin substrate, the contact area between the resin and the mold can be reduced, so that the releasability can be improved.

[Invention of Claim 12]
According to the twelfth aspect of the invention, since the substrate is etched with a part of the light absorption layer serving as a mask remaining, fine irregularities can be formed on the substrate without adding a new process.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is an enlarged view of a part of a mold having the microstructure of the first embodiment, (a) is a plan view, (b) is a perspective view, and FIG. 2 is A in FIG. It is sectional drawing equivalent to -A line.
The mold 100 is used to mold an optical substrate, and an antireflection microstructure is formed on the optical substrate. A plurality of columnar microstructures 120 are formed on the substrate 110 of the mold 100 for manufacturing an optical substrate. Here, a fine structure formed on the optical substrate for antireflection is called a fine structure, and a fine structure formed on the mold for transferring the fine structure to the optical substrate is called a fine structure mold.
In the mold 100, a plurality of fine structure molds 120 are formed in a rectangular lattice shape in the vertical and horizontal directions with a pitch p and a dot pitch d. When an optical substrate is manufactured using this mold 100, a large number of concave microstructures formed by transferring the microstructured structure 120 are arranged on the surface of the optical substrate, and a desired antireflection effect is exhibited. Is done.
Further, among these microstructured structures 120, adjacent microstructured structures 120 are connected by a connecting mold part 130 having a convex shape in the column direction (vertical direction in FIG. 1A). Further, the convex connecting mold part 130 has a height dimension smaller than the height dimension of the microstructured structure 120. For this reason, in this example, since the synthetic resin flows along the convex connecting mold part 130 at the time of molding the optical substrate, it spreads over the entire mold.
Therefore, the synthetic resin is sufficiently filled in the mold 100, the transferability is improved, and the transfer accuracy of the microstructure for preventing reflection of the optical substrate is high.
In this example, as shown in FIG. 2, when the height of the microstructure 120 is H, and the height of the convex connecting mold part 130 is h, the ratio of h to H (H / h) is 2. 5 to 5 is desirable. By setting the ratio of h and H in this way, the transferability of the fine structure to the optical substrate can be improved, and a desired antireflection effect can be exerted on the optical substrate.

[Second Embodiment]
Next, a second embodiment will be described. FIG. 3 is an enlarged view of a part of the mold according to the second embodiment, wherein (a) is a plan view and (b) is a perspective view.
A plurality of columnar microstructures 220 are formed on the substrate 210 of the mold 200. A plurality of fine structure molds 220 are formed in a square lattice pattern in the vertical and horizontal directions with a pitch p and a dot pitch d. Further, in the mold 200 of the second embodiment, connecting portions 230V and 230H that are convex in the vertical and horizontal directions in the figure are formed between the microstructured structures 220 adjacent to each other in the four directions. According to this, since the microstructured structure 220 is connected by the convex connecting portions 230V and 230H in four directions, the synthetic resin extends along the convex connecting portions 230V and 230H when the optical substrate is molded. Flowing. For this reason, since it spreads to the whole mold, the transfer property of a synthetic resin improves.
In this embodiment, it is preferable that the height of the fine structure mold 220 and the height dimensions of the connecting portions 230V and 230H are the same as those in the first embodiment.
The advantage of the second embodiment is that since the connecting portions 230V and 230H are formed on the four sides of the structure, the fluidity of the synthetic resin is higher than that of the first embodiment, and the transferability is further improved.

[Third Embodiment]
Next, a third embodiment will be described. 4A and 4B are enlarged views of a part of the mold according to the third embodiment. FIG. 4A is a plan view and FIG. 4B is a perspective view.
A plurality of columnar microstructures 320 are formed on the substrate 310 of the mold 300. A plurality of fine structure molds 320 are formed in a matrix in the vertical and horizontal directions with a pitch p and a dot pitch d. Among these fine structure molds 320, adjacent fine structure molds 320 are connected by a connecting mold part 330 having a convex shape in the column direction (vertical direction in FIG. 4A).
Further, the mold 300 of the third embodiment is formed as a block 340 in which fine structures are arranged in a plurality of rows, for example, 4 rows, and the block 340 is a parting line type having a width wider than that of the convex connecting die portion 330. The portion 350 is sandwiched. Further, the height dimension of the convex connecting mold part 330 is set to be approximately the same as that of the microstructured structure 320. Note that the number of columns of the microstructured structure 320 constituting the block 340 is not limited to four and can be set to a desired value.
In addition, when the segmented linear part 350 is formed radially from the mold center, the injected molten resin easily flows to the outer periphery along the segmented linear part, so that the entire mold surface can be filled with resin.
The sectional shape of the segmented linear part 350 can be either rectangular or U-shaped. However, in consideration of releasability, if it is U-shaped, the resin substrate is caught by the segmented part at the time of mold release. This can reduce the transfer failure. Therefore, the U-shape is preferable.
The above-mentioned “rectangle” means that the cross-sectional shape in the direction orthogonal to the segmented linear part 350 is a rectangle, and the above “U-shape” means that the cross-sectional shape is substantially U-shaped. To do.
In the mold 300 of this embodiment, when the optical substrate is molded, the synthetic resin flows through the segmented line mold part 350, and the fluidity to the fine structure mold 320 and the connection mold part 330 is improved, so that the transferability of the fine structure mold 320 is improved. The microstructure for preventing reflection of the optical substrate is formed with high accuracy.
The advantage of the third embodiment is that the fine structure is formed for each block, and the block line wider than the line part is formed at the boundary of the block, so that the fluidity of the resin is further improved than the mold of claim 1. Therefore, transferability is further improved.

[Fourth Embodiment]
Next, a fourth embodiment will be described. FIG. 5 is an enlarged view of a part of the mold according to the fourth embodiment, wherein (a) is a plan view and (b) is a perspective view.
A plurality of columnar microstructures 420 are formed on the substrate 410 of the mold 400. A plurality of fine structure molds 420 are formed so as to form a matrix in the vertical and horizontal directions with a pitch p and a dot pitch d. Further, in the mold 400 according to this example, connecting portions 430V and 430H having convex shapes in the vertical direction and the horizontal direction in the figure are formed between the microstructured structures 420 adjacent to each other in the four directions.
Further, the mold 400 of the fourth embodiment is formed as a block 440 in which a fine structure is collected in a plurality of matrices, for example, 3 rows and 4 columns, and the four sides of the block 440 are formed by the convex connecting mold part 430. It is made to pinch | interpose with the wide division | segmentation linear part 450. FIG. In addition, the height of the convex segmented linear part 450 is set to be approximately the same as that of the fine structure 420. Note that the number of matrixes of the fine structure type 320 constituting the block 440 is not limited to 3 rows and 4 columns, and may be a desired value.
According to the mold 400 of the fourth embodiment, the synthetic resin flows through the dividing line mold part 450 when the optical substrate is molded, and the fluidity to the fine structure mold 420 and the connection mold part 430 is improved, so that the fine structure mold 420 is obtained. Transferability is improved, and a fine structure for preventing reflection of the optical substrate is formed with high accuracy.
Since the fine structure according to the fourth embodiment is formed for each block, and a block line having a width wider than the line portion is formed at the block boundary, the fluidity of the resin is further improved compared to the mold according to claim 1, and further transfer is performed. Improves.

In each of the first to fourth embodiments described above, the shape of the fine structure mold is a cylindrical shape. However, depending on the antireflection specifications required for the optical substrate, this shape may be a conical shape or a truncated cone in addition to the cylindrical shape. It can be any of a shape, a quadrangular prism shape, a quadrangular pyramid shape, a quadrangular pyramid shape, an elliptical column shape, an elliptical cone shape, an elliptic frustum shape, or a bell shape. Moreover, it can also be based on the shape of many other types which combined these suitably.
Although a combination of various types of shapes, the advantage over the single shape is that the antireflection effect is high.

Further, in each of the first to fourth embodiments described above, the fine structure mold and the connecting portion have a convex shape protruding from the surface of the substrate, but the fine structure mold has a concave shape recessed from the surface of the substrate. can do. In this case, the concave microstructured molds are connected by a concave connecting mold part that is recessed from the surface. Then, the depth dimension of the concave connection mold part is made smaller than the depth dimension of the fine structure mold body. At this time, the depth dimension of the fine structure mold body and the depth dimension of the concave connection mold part The ratio is preferably 2.5 to 5. By the way, these are not critically technically significant, but less than 2.5, the antireflection effect is small, and conversely, when larger than 5, there is a tendency for transfer failure to occur, so this range is suitable for practical use. It is a range.
When a concave microstructure is used, the transferability of the microstructure to the optical substrate is improved in the same manner as when a convex microstructure is used, thereby preventing reflection of the optical substrate. A fine structure is formed with high accuracy.

In addition, although the mold of the said embodiment forms only one of a convex-shaped fine structure type | mold body and a concave-shaped fine structure type body, it forms by mixing the fine structure type | mold body of both shapes together. Can do. In this case, a convex connection mold part is formed between the convex fine structure molds, and a concave connection mold part is formed between the concave fine structure molds.
Furthermore, in each of the above examples, a square lattice structure in which the fine structure molds are arranged vertically and horizontally is used. However, a triangular lattice structure, a hexagonal lattice structure, or an indefinite state that is not aligned may be used.

[Fifth Embodiment]
Next, a fifth embodiment will be described. This embodiment is a method for manufacturing a mold and an optical substrate.
The mold is manufactured by the following steps (1) to (7), and the optical substrate is manufactured by the following step (8). FIG. 6 shows a mold and an optical substrate manufacturing method according to the fifth embodiment, and (a) to (h) are schematic views showing respective steps.
In the fifth embodiment, first, a quartz matrix having the same shape as that of the microstructure and the connecting portion of the optical substrate to be manufactured is manufactured, Ni casting is performed on this matrix, and nickel Manufactured a master stamper. Therefore, the optical substrate and the mother die are the same type, and the mother die, the optical substrate, and the master stamper have opposite shapes.

(1) Film Formation Step First, as shown in FIG. 6A, AgInSbTe (film thickness 12 nm) is formed as a light absorption layer 520 on a polished and cleaned quartz substrate 510 by a DC sputtering method. On the absorption layer 520, ZnS—SiO 2 (film thickness 75 nm) to be the pattern formation layer 530 is formed by an RF sputtering method. As a result, the master 500 is created.
Note that the light absorption layer 520 and the pattern formation layer 530 formed on the quartz substrate 510 correspond to a resist layer in photolithography.

(2) Exposure Step Next, as shown in FIG. 6B, the master 500 created in the film forming step is exposed with an exposure apparatus. The exposure apparatus condenses the laser beam LB having a wavelength of 413 nm with an objective lens 621 of NA 0.9 to form a latent image on the master 500. The schematic configuration of an exposure apparatus used in this mold manufacturing method is as shown in FIG. The exposure apparatus 600 includes a motor 610 that rotates the master 500 and an optical pickup 620 that performs exposure by moving the rotating master 500 from the left to the right in the drawing (FIG. 6B). Thus, by exposing the master 500 with the optical pickup 620, a latent image is formed in a spiral shape on the master 500. The intensity of the laser beam is determined by an optical modulator (not shown). As shown in FIG. 6B, the optical pickup 620 includes an objective lens 621 that is a convex lens, and condenses the laser light LB on the master 500. Further, the optical pickup 620 includes a focus servo mechanism so as to always collect light at the focus position on the surface of the master.

An example of the modulation of the power of the laser light irradiated by the optical pickup 620 is schematically shown in FIG. As shown in FIG. 8A, in the case where the connecting portion 536 is formed between the fine structures 535 formed on the master 500, the power of the laser beam is modulated so that the pattern forming layer 530 causes a desired thermal alteration. To do. On the other hand, as shown in FIG. 8B, when the connecting portion (see the connecting portion 536) is not formed between the microstructures, the pattern forming layer heats the power of the laser light between the microstructures 537. The power is low enough not to change quality.
Heat is generated in the light absorption layer by the laser light irradiation, and the pattern formation layer 530 and the light absorption layer 520 are thermally altered by the heat. Here, a heat-affected portion 521 is formed in the light absorption layer 520, and a heat-affected portion 531 and other heat-affected portions 532 are formed in the pattern forming layer 530. In the pattern formation layer 530, the region that undergoes thermal alteration depends on the laser power, the thermal alteration portion 531 formed with high power reaches the surface of the pattern formation layer 530, and the other thermal alteration portion 532 formed with low power is It does not reach the surface of the pattern formation layer 530. Therefore, in this example, the heat affected zone 531 reaches the surface of the pattern forming layer 530, while the other heat affected zone 532 does not reach the surface of the pattern forming layer 530.

  This process is heat mode lithography in which a latent image is formed on the resist layer by thermally modifying the resist layer including the light absorption layer 520 and the pattern forming layer 530. This heat mode lithography has a feature that a pattern smaller than the focused spot diameter of laser light can be formed. For this reason, a pattern finer than normal photolithography can be formed. Further, compared to EB lithography using an electron beam, the apparatus cost can be reduced and the exposure time can be shortened.

Note that the shape of the microstructure 537 in the case where the connecting portion is not provided is a circular shape in the example of FIG. 8, but the shape of the microstructure 537 can be changed depending on the irradiation time of the laser light.
FIG. 9 is a partially enlarged view of a mold in which another microstructure shape is formed. On the surface of the mold 500, the microstructure 581 has an elliptical shape, and a connecting portion 582 that is continuous in the major axis direction of the microstructure 581 is formed.
Thus, in order to make the fine structure material 581 into an ellipse, the laser irradiation time at the time of formation may be increased. That is, when the microstructure material is circular with a diameter d, for example, the laser irradiation time is t1, whereas when the ellipse has a major axis that is twice the minor axis d, it is approximately twice the circular shape. is there.
Further, as the fine structure material, any one of a conical shape, a truncated cone shape, a prism shape, and a pyramid shape can be adopted _.

(3) Development Step Next, as shown in FIG. 6C, the exposed master 500 is etched with a hydrofluoric acid aqueous solution. Then, the portion of the pattern formation layer 530 that has not been irradiated with the laser light is removed with a hydrofluoric acid aqueous solution, and a pattern of ZnS—SiO ₂ and AgInSbTe corresponding to the laser irradiation is formed on the master. At this time, the heat-affected portion 531 irradiated with high laser power reaches the surface of the pattern forming layer 530 and becomes thicker, and the other heat-affected portions 532 irradiated with low laser power are heat-affected to the surface. Therefore, the surface portion is removed by etching and becomes thin.

(4) Light Absorbing Layer Removal Step Next, as shown in FIG. 6D, the light absorbing layer 520 is removed by Ar ion sputter etching to expose the quartz substrate 510 of the master 500 in the laser light non-irradiated portion. In the next etching process, the heat-affected portions 531 and 532 composed of the remaining ZnS—SiO ₂ thin film and AgInSbTe thin film become mask layers.

(5) Etching Step In this step, quartz is etched by reactive ion etching (RIE) using the pattern constituted by the thermally altered portions 531 and 532 as a mask. Taking advantage of the fact that the ZnS-SiO ₂ film thickness is different between the heat-affected portion 531 corresponding to the microstructure portion and the heat-affected portion 532 corresponding to the connecting portion, the microstructure 511 and the connecting portion 512 are made to have different heights. To form. Note that the height of the microstructure 511 can be controlled by etching time. In addition, since the wall surface inclination angle of the fine structure 511 can be controlled by the Ar ion sputter etching conditions and the RIE conditions, it is possible to form not only a columnar shape but also a conical or bell-shaped fine structure.
Specifically, this is a method of increasing the taper angle of the structure formed on the quartz substrate by repeating the etching of the pattern as a mask and the etching of the quartz substrate a plurality of times.

FIG. 13 is a flowchart of the etching process. In the etching process, first, the light absorption layer in the region where the pattern is not formed is removed by Ar ion sputter etching to expose the surface of the quartz substrate (FIG. 13B). Next, the quartz substrate is etched by reactive ion etching (RIE) using the pattern as a mask (FIG. 13C). The etching depth of the quartz substrate at this time is, for example, H / 3, where H is the final depth. At this time, the process gas is CHF3, the gas flow rate is 20 sccm, and the RF power is 150 W for etching.
Next, the mask is etched again by Ar ion etching (FIG. 13D). As a result, the diameters of the pattern formation layer and the light absorption layer, which are masks, are smaller than before etching. Subsequently, if the final depth of the quartz substrate is H by RIE, for example, etching is performed by H1 / 3 (FIG. 13E). By repeating this process three times (up to FIG. 13 (g)), the quartz substrate is etched to the desired final depth, and the taper angle of the structure is increased by gradually decreasing the mask diameter. . The taper angle can be controlled by the number of repetitions of Ar ion sputter etching and RIE and the etching amount of the mask by Ar ion etching.
Further, by changing the Ar ion sputter etching conditions (for example, etching time, etching power, etc.), it is possible to form fine irregularities on the mold surface on which no pattern is formed. With this mold, it is possible to reduce the contact area with the resin and improve the releasability.

FIG. 14 is a flowchart of the etching process. First, the light absorption layer in a region where no pattern is formed is etched by Ar ion sputter etching (FIG. 14B). At this time, the etching is performed under an etching condition in which a part of the light absorption layer remains in an island shape. In this example, the etching was performed in a shorter time (50 to 70% time) than the etching time required to completely remove the light absorption layer. It is also possible to control the etching power outside the etching time, the Ar flow rate, and a combination of these conditions.
Next, the quartz substrate is etched by RIE (FIG. 14C). Since the light absorption layer has etching resistance to RIE and serves as a mask, the quartz substrate is etched according to the light absorption layer remaining in an island shape. Thus, a fine uneven shape smaller than the pattern is formed on the quartz substrate together with the pattern.
As described above, finer irregularities than the pattern can be formed by changing the conditions of the Ar ion sputter etching without adding a new process.

(6) Light Absorbing Layer and Pattern Forming Layer Removal Step As shown in FIG. 6 (f), after the pattern forming layer 530 was wet etched with a hydrochloric acid aqueous solution, the light absorbing layer 520 was removed with a sodium hydroxide aqueous solution by wet etching. Thereafter, sufficient washing with water is performed to obtain a mother die 550 in which the fine structure 511 and the connecting portion 512 are formed on the quartz substrate 510. At this time, the microstructure 511 and the connecting portion 512 are convex shapes protruding from the surface of the mother die 550. Using this mother die 550 as a mold, it is possible to manufacture a resinous optical substrate having a microstructure reversibly formed. In this embodiment, nickel having a shape reversed from the mother die 550 by the following steps is used. A manufactured master stamper 560 is manufactured, and an optical substrate of the same type as the mother die 550 is produced.

(7) Stampering Step After forming a conductive thin film such as Ni on the mother die 550, as shown in FIG. 6 (g), Ni electroforming is performed to create a master stamper 560 made of Ni. In the master stamper 560, the fine structure mold body 561 and the connection mold portion 562 are concave with respect to the surface of the master stamper 560. If the master stamper 560 is further electroformed to duplicate the sun stamper, a convex microstructure can be formed on the surface of the sun stamper. As a mold for manufacturing an optical substrate, either a master stamper or a sun stamper can be used as necessary.

(8) Optical substrate transfer process When the surface shape of the master stamper 560 is transferred to the surface of the optical substrate 570 made of synthetic resin using the produced master stamper 560 as a mold, an optical substrate having a fine structure is obtained. As the transfer method, there are an injection molding method, a photocuring method, a thermosetting method and the like, but an injection molding method capable of efficiently producing a substrate is desirable.

[Sixth Embodiment]
Next, a sixth embodiment will be described. This embodiment is a mold manufactured by the manufacturing method of the fifth embodiment.
This mold has a shape in which the unevenness of the mold 100 in FIG. 1 is inverted, and includes a concave microstructured mold body and a concave connecting mold part. This mold is made of nickel (the mold 1, the mold 2, the mold 3, and the mold 4, respectively) having a depth of the connection mold part of 0, 50, 100, and 200 nm, and has a transferability of the fine structure. evaluated. In each mold, a fine structure having a pitch p and a dot pitch d of 300 nm, a dot diameter of 200 nm, and a height of 250 nm is formed. The pattern height of the connection mold part was controlled by controlling the exposure laser power.
A polycarbonate optical substrate was produced by injection molding using the molds 1 to 4, and the height of the microstructure of the substrate and the mold (depth in the mold) was measured by AFM. The measurement results are as shown in Table 1 below.

  When the ratio of the height or depth of the transferred substrate structure to the depth or height of the mold structure is the transfer rate, the transfer rate when the mold line depth is 0 nm, that is, when there is no line, is While the transfer rate was about 60%, the transfer rate improved as the line height was increased. When a line having a depth of 100 nm or more was formed between the fine structures, the transfer rate was improved by about 1.7 times compared to the case where the line was not formed.

[Seventh Embodiment]
Next, a seventh embodiment will be described. This embodiment is a mold manufactured by the manufacturing method of the fifth embodiment.
This mold is made of quartz having a connected mold portion height of 0, 50, 100, and 200 nm (referred to as mold a, mold b, mold c, and mold d, respectively). evaluated. The shape of the substrate was the same as that shown in FIG. 1, and a release agent was applied to the quartz mold surface by a dipping method.
Using molds a to d, a resinous optical substrate was manufactured by a photocuring method. As a method for producing an optical substrate, first, an ultraviolet curable resin is applied onto a transparent polycarbonate optical substrate by a spin coating method, and after a quartz mold is pressure-bonded thereon, ultraviolet rays are irradiated from the mold side to apply the resin. Cured. Thereafter, the optical substrate was peeled off from the master stamper to form a fine structure on the optical substrate. A resin substrate was produced from each mold by this photocuring method, and the structure height of the substrate was measured. The heights of the substrate structures produced from the molds a, b, c, and d were 200, 250, 250, and 250 nm, respectively. Also in the photocuring method, the transfer rate was improved due to the formation of the line portion.

[Eighth Embodiment]
Next, an eighth embodiment will be described. This embodiment is a polycarbonate optical substrate manufactured by an injection molding method. The reflectance of the optical substrate at a wavelength of 500 nm was measured. The reflectivities of the optical substrates produced using the molds 1 to 4 of the sixth embodiment (see Table 1 above) were 3%, 2%, 1%, and 2%. The antireflection effect was observed for the reflectance of about 4% of the polycarbonate substrate on which the fine structure was not formed. This is lower than that of the conventional example (the height and density of the fine structure are the same as those of this embodiment).
Note that the effect is higher when the height of the fine structure of the substrate is higher, as in the case of the conventional example. However, when the height of the fine structure is 150 nm or less, the effect is not significant, and 500 nm. Productivity falls remarkably that it is above. Therefore, in practice, it is preferable to stop within the range of 300 nm or less.

Moreover, although the reflectance by the mold 4 in Table 1 is relatively high at 2%, it is considered that the antireflection effect by the fine structure is reduced because the line portion is deep. When the depth of the line portion is about 1/5 to 2/5 of the depth of the structure, the improvement of the transfer rate and the antireflection effect are compatible. That is, when the ratio of the height of the structure in the mold to the height of the line portion is 2.5 to 5, an improvement in transferability and an antireflection effect can be obtained. The same effect was obtained for the substrate produced using the molds a to d by the photocuring method.
If the optical substrate material is a resin substrate having translucency such as polycarbonate or polyolefin, it can be applied to optical substrates such as diffraction gratings and lenses having antireflection structures, light emitting devices, and photoelectric conversion devices. .
According to the present invention, an optical substrate can be duplicated in a large amount by an injection molding method or a photocuring method, and in particular, in the injection molding method, a substrate can be produced efficiently.

[Ninth Embodiment]
Next, a ninth embodiment will be described. This embodiment is made of nickel, a plurality of fine structure molds are arranged in a square lattice, and a block is formed by combining a plurality of rows and a plurality of columns. A wide segmental linear part is formed (see FIG. 5), and concave and convex microstructures are mixed. FIG. 10 shows an outline of an exposure apparatus used for manufacturing the ninth embodiment. The exposure apparatus used in this embodiment draws a pattern by a raster scan method using an optical pickup 820 on a master having a light absorption layer and a pattern forming layer laminated on a quartz master 500. The optical pickup 820 includes an objective lens and the like as shown in FIG. A laser power and laser beam irradiation timing were controlled by an optical modulator (not shown) to form a latent image on the master. Then, Ni mold was produced through the same process (Drawing 6 (c)-(h)) after the development process of the manufacturing method of the above-mentioned mold.
Transferability was compared between a mold having a segmented linear part and a mold having no segmental linear part. The diameter of the microstructure structure of each mold is 150 nm, the pitch p and the dot pitch d are 250 nm, the height of the microstructure structure is 300 nm, the width of the connection mold part is 100 nm, and the height of the connection mold part is 50 nm. did. The width of the segmented linear part was 150 nm and the height was 300 nm. The height of the microstructure of the optical substrate produced from the mold in which the segmented linear part was formed was 290 nm, whereas the height of the microstructure of the optical substrate produced from the mold in which the segmented linear part was not formed Was 240 nm. From this, it can be seen that the formation of the segmented linear part improves the flowability of the synthetic resin and improves the transferability.

[Tenth embodiment]
Next, a tenth embodiment will be described. This embodiment is another method for manufacturing a mold.
The structure of the mold manufactured in the tenth embodiment is schematically shown in FIG. 11, and the manufacturing method of the tenth embodiment is shown in FIG. And each process of this manufacturing method is as having shown to Fig.12 (a)-(k).
A mold 900 manufactured in the tenth embodiment is made of quartz, and as shown in FIG. 11, a concave fine structure body 920 and a concave shape structure 920 connecting adjacent fine structure bodies 920 to the substrate 910. The connection mold part 930, the convex fine structure mold 940, and the convex connection mold part 950 for connecting the fine structure mold 940 are mixed.

  In the following steps (1) to (5), the concave microstructured mold 920 and the connecting mold part 930 are formed, and then in the processes (6) to (11), the convex microstructured mold 940 and the connecting mold are formed. A portion 950 is formed.

(1) Film forming process 1
As shown in FIG. 12A, a pattern formation layer 1020 was formed on a polished and cleaned quartz substrate 1010 by RF sputtering so that the film thickness of ZnTe was 70 nm. This is the master 1030. The pattern forming layer 1020 may be a mixture of ZnTe and SiO ₂ .

(2) Exposure step 1
The produced master 1030 is exposed with a laser beam LB focused at a wavelength of 413 nm and NA 0.9 of the objective lens 1101 using an optical pickup 1100 to form a latent image (FIG. 12B). At this time, the laser beam is irradiated at a power corresponding to the concave microstructured body 920 at a higher power than that of the connection mold part 930. By irradiating the laser beam LB, heat is generated in the pattern formation layer 1020, and the heat-affected portion 1021 is formed in a predetermined region of the pattern formation layer by the heat. The depth of the thermally altered portion 1021 depends on the power of the laser beam. The thermally altered portion 1021 irradiated with high power is thermally altered to the surface of the pattern formation layer 1020, and the thermally altered portion 1021 irradiated with low power is It does not reach the direction. In FIG. 12B, all the thermally affected portions 1021 are drawn to the same thickness, but actually, the thermally affected portion 1021 is formed to have a different thickness as shown in FIG. 6B. .

  As described above, the shape of the fine structure mold 920 can be controlled to be circular, elliptical, or the like depending on the laser irradiation time when the fine structure mold 920 is formed. When the connection mold part 930 is not formed between the fine structure molds 920, as shown in FIG. 8B, the power of the laser light between the fine structure molds is low enough to prevent the pattern formation layer from being thermally altered. Set to power. When the connection mold part 930 is formed between the microstructured molds 920, as shown in FIG. 8A, the intensity of the laser beam is adjusted to the extent that thermal alteration occurs to a desired depth in the pattern formation layer.

(3) Development step 1
As shown in FIG. 12C, when the exposed master 1030 is etched with a hydrofluoric acid aqueous solution, the heat-affected portion 1021 irradiated with the laser light of the pattern forming layer 1020 is removed with the hydrofluoric acid aqueous solution. A removal portion 1022 corresponding to the removal portion 1022 is formed, and a pattern of ZnTe by the removal portion 1022 is formed on the master 1030. At this time, the portion of the structure irradiated with high laser power becomes a wide hole, and the region of the line irradiated with low laser power becomes a narrow groove.

(4) Etching process 1
As shown in FIG. 12D, the quartz substrate 1010 is etched by reactive ion etching (RIE) using the ZnTe pattern as a mask. As a result, the bottom portion (the upper surface of the quartz substrate 1010) of the removal portion 1022 of the pattern formation layer 1020 is removed, and the concave portion 1011 is formed. At this time, by utilizing the fact that the width dimension of the pattern is different between the fine structure mold and the connection mold part, the height can be different between the fine structure mold and the connection mold part.

(5) Pattern Formation Layer Removal Step As shown in FIG. 12 (e), the pattern formation layer 1020 is wet-etched with an aqueous hydrochloric acid solution, and then washed with sufficient water to thereby form a concave portion corresponding to the microstructured structure 920. A quartz substrate 1010 on which 1011 is formed is obtained. At this stage, the quartz substrate 1010 can be used as a mold to replicate a resin substrate on which a fine structure is formed, and a Ni mold can be produced based on this quartz substrate. In the embodiment, further processing is performed to create a mold including the microstructured body 940.

(6) Film forming process 2
Next, as shown in FIG. 12F, the process shown in FIG. 6A is performed on the surface of the quartz substrate 1010 of the master 1030 created by the process of (5). That is, the light absorption layer 1040 made of AgInSbTe and the pattern formation layer 1050 made of ZnS—SiO ₂ are applied on the quartz substrate 1010.

(7) Exposure process 2
Further, as shown in FIG. 12G, the process shown in FIG. 6B is performed on the master 1030 created in (6). That is, exposure is performed with a laser beam from the optical pickup 1100 to form a latent image. In this step, a pattern corresponding to the microstructured structure 940 and the connection mold part 950 having a convex shape is exposed between the concave connection mold part 930 and the microstructured structure 940. As a result, the heat affected zone 1041 and the heat affected zone 1051 are formed in the light absorption layer 1040 and the pattern forming layer 1050. At this time, the film thickness of the thermally affected portion 1051 irradiated with high laser power becomes thick because the heat affected light reaches the surface of the pattern forming layer 1050, and the thermally affected portion 1051 irradiated with low laser power Since the surface of the formation layer 1050 is not thermally altered, it is thin. In FIG. 12G, all the thermally altered portions 1051 are drawn to the same thickness, but the thermally altered portion 1051 is formed to have a different thickness as shown in FIG. 6B.

(8) Development step 2
Next, as shown in FIG. 12 (h), the development process shown in FIG. 6 (c) is performed on the master 1030 that has been subjected to the process (7). Due to the development process, the master 1030 is etched with a hydrofluoric acid aqueous solution, and the portion of the pattern forming layer 1050 that has not been irradiated with the laser light is removed with the hydrofluoric acid aqueous solution, and the pattern of the thermally altered portion 1041 and the thermally altered portion 1051 is formed on the master 1030. Is formed. At this time, the film thickness of the thermally affected portion 1051 irradiated with high laser power becomes thick because the heat affected light reaches the surface of the pattern forming layer 1050, and the thermally affected portion 1051 irradiated with low laser power Since the surface of the formation layer 1050 is not thermally denatured, the portion is removed by etching and thus becomes thin.

(9) Light Absorbing Layer Removal Step Next, as shown in FIG. 12 (i), the process shown in FIG. 6 (d) is performed on the master 1030. In this process, the light absorption layer 1040 is removed by Ar ion sputter etching to expose the quartz substrate 1010 covered with the pattern constituted by the thermally altered portion 1041 and the thermally altered portion 1051.

(10) Etching process 2
Next, as shown in FIG. 12 (j), the process shown in FIG. 6 (e) is performed on the master 1030 that has been processed in (9). In this process, the quartz substrate 1010 is etched by reactive ion etching (RIE) using the pattern formed by the thermally altered portion 1041 and the thermally altered portion 1051 as a mask.

(11) Light Absorbing Layer and Pattern Forming Layer Removal Step Then, as shown in FIG. 12 (k), the master 1030 subjected to the processing (10) is subjected to the processing shown in FIG. 6 (f). In this process, the heat-affected portion 1051 of the pattern forming layer 1050 is wet etched with an aqueous hydrochloric acid solution, and then the heat-affected portion 1041 of the light absorption layer 1040 is removed by wet etching with an aqueous sodium hydroxide solution. Thereafter, sufficient water washing is performed.
By performing these processes, it is possible to manufacture a mold 900 in which the concave microstructured mold 920 and the convex microstructured mold 940 are present.

These are enlarged views of a part of the mold having the microstructure of the first embodiment, wherein (a) is a plan view and (b) is a perspective view. Is a cross-sectional view taken along line AA in FIG. These are enlarged views of the mold of the second embodiment, (a) is a plan view, (b) is a perspective view. These are enlarged views of the mold of the third embodiment, (a) is a plan view, (b) is a perspective view. These are enlarged views of the mold of the fourth embodiment, (a) is a plan view, (b) is a perspective view. These show the manufacturing method of the mold and optical substrate of 5th Embodiment, (a)-(h) is a schematic diagram which shows each process. These are the schematic block diagrams of the exposure apparatus used with the manufacturing method of 5th Embodiment. FIG. 3 is a schematic diagram showing an example of modulation of the power of laser light irradiated by the optical pickup Fig. 2 is a schematic diagram showing another example of laser light irradiation FIG. 10 is a schematic view of an exposure apparatus used for manufacturing the ninth embodiment. These are schematic diagrams showing the configuration of a mold manufactured by the manufacturing method of the tenth embodiment. These show the manufacturing method of the mold of 10th Embodiment, (a)-(k) is a schematic diagram which shows each process. These show the flow of the etching process of 5th Embodiment, (a)-(g) is a schematic diagram which shows each process. These show the flow of the other etching process of 5th Embodiment, (a)-(c) is a schematic diagram which shows each process FIG. 3 is a cross-sectional view showing a method for manufacturing an optical element manufacturing mold according to the prior art according to processes.

Explanation of symbols

100: Mold 110: Substrate 120: Microstructure mold body 130: Connection mold part 200: Mold 210: Substrate 220: Microstructure mold body 230H, 230V: Connection part 300: Mold 310: Substrate 320: Microstructure mold body 330: Connection Mold part 340: Block 350: Dividing line mold part 400: Mold 410: Substrate 420: Fine structure mold body 430: Connection mold part 430H, 430V: Connection part 440: Block 450: Dividing line mold part 500: Master disk 510: Quartz substrate 511 Fine structure 512: Connection portion 520: Light absorption layer 521: Thermally altered portion 530: Pattern formation layer 531, 532: Thermally altered portion 535: Fine structure 536: Connection portion 537: Fine structure
550: Master mold 560: Master stamper 561: Fine structure mold 562: Connection mold part 570: Optical substrate 581: Fine structure material 582: Connection part 600: Exposure device 610: Motor 620: Optical pickup 621: Objective lens 820: Light Pickup 900: Mold 910: Substrate 920: Fine structure mold 930: Connection mold part 940: Fine structure mold 950: Connection mold part 1010: Quartz substrate 1011: Concave shape part 1020: Pattern formation layer 1021: Thermal alteration part 1022: Removal unit 1030: Master 1040: Light absorption layer 1041: Thermal alteration unit 1050: Pattern formation layer 1051: Thermal alteration unit 1100: Optical pickup

Claims (12)

In a mold in which a plurality of fine structure molds forming at least one of a convex shape and a concave shape forming an antireflection fine structure on the surface of an optical substrate to be transferred and formed,
Between the fine structure molds, a convex connection mold part that connects adjacent convex fine structure molds or a concave connection mold part that connects adjacent convex fine structure molds is formed. And
The height dimension of the convex connecting mold portion is smaller than the height dimension of the convex microstructured structure,
A mold characterized in that a depth dimension of the concave connecting mold part is smaller than a depth dimension of the concave microstructured body.   2. The mold according to claim 1, wherein the shape of the microstructure structure is any one of a columnar shape, a cone shape, a truncated cone shape, a prismatic shape, a pyramid shape, and a truncated pyramid shape. The plurality of microstructured bodies are configured as a block of blocks;
3. A convex or concave segmented line-shaped part that divides the block and has a width dimension larger than the width dimension of the connecting mold part is disposed between the plurality of blocks. The mold described. The fine structure mold is for forming an antireflection structure of an optical substrate to be molded,
The microstructured body is formed with a pitch equal to or less than the wavelength of the light whose reflection should be suppressed,
The height dimension of the convex microstructured mold body or the depth dimension of the concave microstructured mold body, and the height dimension of the convex coupling mold part or the depth dimension of the concave coupling mold part The mold according to claim 1, wherein the ratio is 2.5 to 5. 5. In the optical substrate in which a plurality of microstructures of at least one of a convex shape and a concave shape for reflection prevention are formed on the surface,
Between the fine structures, a convex connection part that connects adjacent convex fine structures or a concave connection part that connects adjacent concave fine structures is formed,
The height dimension of the convex connecting portion is smaller than the height dimension of the convex microstructure, and the depth dimension of the concave connecting portion is smaller than the depth dimension of the concave microstructure. An optical substrate characterized by being made.   6. The optical substrate according to claim 5, comprising a synthetic resin having translucency. It is a manufacturing method of the mold according to claim 1, Comprising:
Forming an inorganic resist layer comprising at least a light absorbing layer and a pattern forming layer on the substrate;
A step of forming a latent image by changing an irradiation power of laser light according to a formation pattern of the convex or concave fine structure mold, the convex connection mold part, and the concave connection mold part;
Forming the convex or concave microstructure structure, the convex connection mold part or the concave connection mold part by an etching process; and
Etching the substrate using the pattern as a mask to form a convex or concave microstructured structure, the convex connection mold part or the concave connection mold part; and
Removing the mask;
The manufacturing method of the mold characterized by including. In the mold according to claim 3,
The mold characterized in that the segmented linear part is formed radially from the mold center. In the mold according to claim 3,
A mold characterized in that a sectional shape of the segmented line-shaped portion is U-shaped. The mold manufacturing method according to claim 7,
In the step of etching the substrate using the pattern as a mask, the step of etching the mask and the step of etching the substrate are repeated to form a convex concave structure. . The mold according to claims 1 to 4, 8 and 9,
A mold characterized in that irregularities smaller than the structure are randomly formed in a region where the fine structure, the connecting mold part, and the segmented line mold part are not formed. The mold manufacturing method according to claim 7,
In the step of etching the substrate using the pattern as a mask, etching is performed so that the light absorption layer in a region where the pattern is not formed remains in an island shape, and the substrate is formed using the island-shaped light absorption layer and the previous pattern as a mask. The mold manufacturing method is characterized by simultaneously forming unevenness and a structure smaller than the structure by etching.

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