JP2007283581A - Manufacturing process of structural body having finely rugged surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process by which a structural body having a finely rugged surface is precisely and easily manufactured. <P>SOLUTION: A mold 10 has a molding section 12 which has a shape corresponding to the rugged structure 2 for antireflection, and a projection 15 sticking out from the level of the molding section 12, on one side 11 of its surfaces. A material to be molded 40 is placed in such a way that it is in contact with the mold 10 and apart from the molding section 12. The material to be molded 40 is softened and press-molded in the molding section 12 of the mold 10 to obtain the antireflection rugged structure 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a structure having a fine uneven structure on the surface.

  In recent years, various optical elements in which antireflection treatment for suppressing light reflection is performed on the surface have been proposed. As the antireflection treatment, for example, a multilayer formed by alternately laminating a film having a relatively low refractive index (low refractive index film) or a film having a low refractive index and a film having a relatively high refractive index (high refractive index film). The process which forms the antireflection film which consists of a film | membrane etc. on the surface is mentioned.

  However, an antireflective film composed of a low refractive index film or a multilayer film requires complicated steps such as vapor deposition and sputtering. For this reason, there is a problem that productivity is low and production cost is high. Further, an antireflection film composed of a low refractive index film or a multilayer film has a problem that wavelength dependency and incident angle dependency are large.

  In view of such a problem, as an antireflection treatment having a relatively small incident angle dependency and wavelength dependency, for example, a reflection composed of a plurality of cone-shaped projections (or cone-shaped recesses) arranged at a submicron pitch. There has been proposed a process for forming a prevention structure (hereinafter, sometimes referred to as an “antireflection uneven structure”) on the surface of an optical element. By forming this antireflection concavo-convex structure on the element surface, an abrupt refractive index change at the element interface is suppressed, and the refractive index gradually changes in the antireflection concavo-convex structure. For this reason, light reflection on the surface of the optical element is reduced, and a high light incidence rate into the optical element (specifically, high light having a wavelength equal to or greater than the pitch between the cone-shaped protrusions (cone-shaped recesses)). (Incident rate) can be realized.

  In addition, as a manufacturing method of the antireflection concavo-convex structure (structure having the antireflection concavo-convex structure formed on the surface), for example, it corresponds to the antireflection concavo-convex structure formed by a method such as electron beam (EB) drawing. There has been proposed a method of manufacturing a molded object made of quartz glass or the like through a pattern mask by dry etching (Patent Document 1).

In addition, a method has been proposed in which a molding made of glass or resin is press-molded using a molding die having a shape corresponding to the antireflection uneven structure to be formed.
JP 2001-272505 A

  However, in the method of obtaining the antireflection concavo-convex structure by dry etching described above, the surface after etching may become rough or the etching rate may become very slow depending on the molding target. For this reason, there exists a problem that the material of the to-be-molded object for obtaining an antireflection uneven structure will be limited. In this method, a mask having a fine structure must be formed by electron beam drawing. The mask fabrication by this electron beam drawing requires a very long period. For example, it takes about 5 hours to draw a circular pattern (diameter 0.20 μm) at a pitch of 0.25 μm in a 5 mm square region. . Furthermore, if an attempt is made to draw a pattern in a 50 mm square area, 500 hours are required. Therefore, there are problems that the manufacturing cost of the antireflection uneven structure increases and the manufacturing efficiency decreases.

  Furthermore, in electron beam drawing, it is difficult to accurately draw a pattern on a non-planar surface such as a lens surface or a lens barrel inner peripheral surface. For this reason, it is difficult to produce a non-planar mask corresponding to a non-planar surface such as the lens surface or the inner peripheral surface of the lens barrel. Therefore, it is difficult to form an antireflection uneven structure on a non-planar surface.

  On the other hand, in the manufacturing method of the antireflection concavo-convex structure by press molding, there is no restriction on the shape of the molding, for example, forming the antireflection concavo-convex structure on the lens surface, the inner peripheral surface of the lens barrel, etc. Can do. In addition, after producing the one-end mold, the antireflection concavo-convex structure can be mass-produced more easily and cheaply than the molding method by dry etching. For this reason, in recent years, the press molding method has attracted attention as a method of forming an antireflection uneven structure on various moldings.

  However, as described below, the conventional press molding method has a problem that it is difficult to repeatedly form a high-definition antireflection uneven structure.

  Conventionally, when forming an antireflection concavo-convex structure by press molding, first, for example, a glass object is placed on a lower mold on which a fine structure corresponding to the antireflection concavo-convex structure is formed, and further molding is performed. Place the upper mold on the object. Then, after heating the molded object together with the upper mold and the lower mold to soften the molded object, the molded article softened with the upper mold and the lower mold is press-molded to prevent the antireflection irregularities on the molded object. Form a structure. As described above, in the conventional press molding method, it is necessary to place the cured product on a fine structure corresponding to the antireflection concavo-convex structure, so that the mold is formed by repeated contact with the hard product. The formed fine structure may be deformed and further damaged, and it may be difficult to stably form a high-definition antireflection uneven structure.

  Such problems such as deformation and breakage of the mold are common not only when the antireflection uneven structure is manufactured, but also when a structure having a fine uneven structure is manufactured by press molding.

  This invention is made | formed in view of such a point, The place made into the objective is to provide the method which can manufacture the structure which has a fine uneven structure stably with high definition.

  In order to achieve the above object, the present invention is directed to the manufacture of a structure having a fine concavo-convex structure formed on the surface, and a molded part having a shape corresponding to the concavo-convex structure and a protruding part protruding from the molded part are provided. A step of placing a molding object so as to be in contact with the protrusion while being spaced apart from the molding portion with respect to a molding die formed on one surface, a step of softening the arranged molding material, and a softened coating And a step of obtaining a structure by press-molding a molded product with a molding part of a mold.

  According to the present invention, a structure having a fine concavo-convex structure can be stably manufactured with high definition.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view of an antireflection concavo-convex structure 1 manufactured in the first embodiment.

  First, the structure of the antireflection uneven structure 1 will be described with reference to FIG. The antireflection uneven structure 1 is a parallel plate-like structure in which an antireflection uneven structure 2 is formed on both surfaces 1a and 1b. Here, each antireflection concavo-convex structure 2 is composed of a plurality of surfaces inclined with respect to the surface direction (plate surface direction). Specifically, the antireflection concavo-convex structure 2 is composed of a plurality of conical recesses 3. The pitch between the cone-shaped recesses 3 (the distance between the lowest points of the adjacent cone-shaped recesses 3) P is set to, for example, 300 nm or less (for example, 150 nm). The reflection of light having a wavelength equal to or greater than the pitch P of the body-shaped recess 3 is suppressed. In addition, it is preferable that the depth D of the cone-shaped recessed part 3 is more than a pitch (namely, an aspect ratio is 1 or more), for example, can be 150 nm. By further increasing the depth D of the conical recess 3, light reflection on the surfaces 1a and 1b can be more effectively suppressed.

  The antireflection concavo-convex structure 1 may be formed of a light reflective material such as a metal such as aluminum or silver, or may be formed of a light transmissive material such as glass (for example, quartz glass) or a resin. It may be formed. By forming the antireflection concavo-convex structure 1 with a light reflective material such as a metal, incident light is absorbed by the antireflection concavo-convex structure 2 and does not produce substantially reflected light (components of optical elements and optical devices). For example, a lens barrel member attached to the imaging device can be realized. Further, by forming the antireflection concavo-convex structure 1 with a light-transmitting material such as glass, reflection on the surfaces 1a and 1b on which the antireflection concavo-convex structure 2 is formed is suppressed, and incident light is transmitted with high transmittance. An optical element (lens, prism, etc.) to be realized can be realized.

  In the first embodiment, an example in which the antireflection concavo-convex structure 2 is composed of a plurality of conical recesses 3 will be described. However, the antireflection concavo-convex structure 2 may be composed of a plurality of conical projections. Good. In this case, the reflection preventing concavo-convex structure 2 suppresses reflection of light having a wavelength equal to or greater than the pitch between the cone-shaped projections (the distance between the apexes of adjacent cone-shaped projections).

  Next, the manufacturing method of the antireflection uneven structure 1 will be described in detail with reference to FIGS. FIG. 2 is a cross-sectional view of a mold 10 used for manufacturing the antireflection uneven structure 1. FIG. 3 is a cross-sectional view showing a main configuration of a manufacturing apparatus 4 for manufacturing the antireflection uneven structure 1. FIG. 4 is a cross-sectional view illustrating a process of press-molding the molding 40. FIG. 5 is a cross-sectional view showing a process of taking out the molded antireflection uneven structure 1.

  As shown in FIG. 3, the manufacturing apparatus 4 includes a cylindrical body mold 30, and a forming mold 10 a and a forming mold 10 b that are slidably fitted to the body mold 30. In the first embodiment, the mold 10a and the mold 10b are molds having the same shape, but when the shape of the surface 1a and the shape of the surface 1b of the antireflection uneven structure 1 are different from each other. Of course, the mold 10a and the mold 10b may be different from each other in correspondence with the surfaces 1a and 1b, respectively. In the first embodiment, the molding die 10a and the molding die 10b are collectively referred to as the molding die 10. In the description of the molding die 10a and the molding die 10b, components having substantially the same function are referred to by common reference numerals.

  As shown in FIG. 2, the central portion of one surface 11 of the mold 10 (10a, 10b) has a shape corresponding to the antireflection uneven structure 2, that is, each corresponds to the shape of the conical recess 3. The molding part 12 in which the structure 13 which consists of the several cone-shaped projection part 14 was formed is provided. And the linear protrusion part 15 of the cross-sectional square shape (for example, rectangular shape or trapezoid shape) extended in the depth direction in FIG. Is formed.

  First, as shown in FIG. 3, a parallel plate-shaped object 40 made of, for example, glass or resin is disposed between the mold 10 a and the mold 10 b. Specifically, the molding 40 is placed on the molding die 10a, and the molding die 10b is placed thereon so that the molding portion 12 faces the molding 40. The molding 40 is, for example, a plate-shaped body made of 15 mm × 15 mm × 1.0 mm crown borosilicate glass (glass transition temperature (Tg): 501 ° C., yield point (softening temperature: At: 549 ° C.)). Can do.

  Here, if the molded object 40 in a cured state comes into contact with the fine cone-shaped protrusions 14 formed on the mold 10a and the mold 10b, the cone-shaped protrusions 14 are deformed and damaged. There is a risk of it. In particular, when the molded object 40 is harder than the molds 10a and 10b at room temperature, for example, when the molds 10a and 10b are made of metal and the molded object 40 is made of glass. The molds 10a and 10b are highly likely to be deformed and damaged. If the cone-shaped protrusion 14 is deformed or damaged, the high-definition antireflection uneven structure 1 cannot be obtained. However, in Embodiment 1, the molding die 10 a is formed with linear protrusions 15 that are located on both sides of the molding part 12 and project from the molding part 12. For this reason, the to-be-molded product 40 is supported by the linear protrusion part 15 of the shaping | molding die 10a, and does not contact | abut to the fine cone-shaped projection part 14 formed in the shaping | molding part 12 of the shaping | molding die 10a. For this reason, the deformation | transformation and damage of the shaping | molding part 12 (cone-shaped projection part 14) of the shaping | molding die 10a resulting from the to-be-molded article 40 contact | abutted in the hardening state are prevented. Similarly, since the linear protrusion 15 located on both sides of the molding portion 12 and projecting from the molding portion 12 is also formed in the molding die 10b, the linear projection 15 is formed in the molding die 10b. The to-be-molded product 40 which is supported by being brought into contact with 40 and is in a cured state does not come into contact with the fine cone-shaped protrusion 14 formed in the forming portion 12 of the forming die 10b. For this reason, the deformation | transformation and damage of the shaping | molding part 12 (cone-shaped projection part 14) of the shaping | molding die 10b resulting from contact with the comparatively hard to-be-molded object 40 are prevented.

  And the to-be-molded object 40 arrange | positioned is softened. For example, when the molding 40 is substantially made of glass, thermoplastic resin, or the like, the molding 40 is softened by heating the molding dies 10 a and 10 b together with the molding 40. In this case, the heating temperature can be close to or higher than the softening temperature of the molding 40. Specifically, when the molding 40 is made of the above-described crown borosilicate glass, the molding 40 can be softened by heating to 590 ° C., for example. After the molding 40 is softened, the molding 40 is pressed with the molding die 10a and the molding die 10b (for example, 1000N for 3 minutes) to transfer the shape of the molding part 12 to both surfaces of the molding 40. Thereby, the antireflection uneven structure 1 in which the antireflection uneven structure 2 is formed on both surfaces can be obtained. In this pressing step, the antireflection uneven structure 2 is formed by the molding portion 12 of the molding dies 10a and 10b as described above, and the linear protrusion 15 of the molding die 10a and the linear protrusion 15 of the molding die 10b, Concave portions 1c and 1d are formed on the surfaces 1a and 1b, respectively. For example, when the antireflection concavo-convex structure 1 is an optical element, it is preferable to set the position of the linear protrusion 15 so that the regions where the recesses 1c and 1d are formed are located outside the optically effective region.

  After the press molding is completed, as shown in FIG. 5, after the obtained antireflection uneven structure 1 is cured (for example, by cooling to about 300 ° C.), the mold 10b is removed and separated from the mold 10a. The antireflection concavo-convex structure 1 is completed by molding. In order to prevent the molding dies 10a and 10b and the molded antireflection concavo-convex structure 1 from being fused, an alloy containing a noble metal such as platinum or a noble metal on each surface of the molding dies 10a and 10b. It is preferable to previously form a release film substantially formed of carbon or the like.

  In the pressing process using the molding dies 10a and 10b, the molding part 12 of the molding dies 10a and 10b comes into contact with the workpiece 40. However, since the molding 40 is already in a softened state when it comes into contact. The possibility that the molded part 12 is deformed / damaged by contact with the molding 40 is extremely small.

  As described above, the linear protrusions 15 are provided so that the molded object 40 in a cured state does not come into contact with the molding part 12 having a fine concavo-convex structure (a plurality of conical protrusions 14). Therefore, deformation and damage of the molded part 12 are suppressed, and a structure having fine unevenness such as the antireflection uneven structure 1 can be stably manufactured with high definition. Further, as in the first embodiment, according to the press molding, the antireflection uneven structure 1 can be manufactured much more easily than using dry etching.

  Although the linear protrusion 15 is provided here, the shape of the protrusion is limited as long as the molded object 40 in a cured state can be prevented from coming into contact with the molded part 12. For example, the protrusion may be formed in a triangular or polygonal line with a cross section, a columnar shape (columnar shape, polygonal columnar shape, etc.), a cone shape (conical shape, a polygonal pyramid shape, etc.), or A plurality of protrusions having a truncated cone shape (such as a truncated cone shape and a polygonal truncated cone shape) may be provided. Further, the height of the protruding portion 15 to be provided is not particularly limited as long as the molding portion 12 in a cured state does not contact the molding target 40.

  Moreover, the manufacturing method of the shaping | molding die 10 is not specifically limited, For example, it can manufacture in the following way.

  6-10 is sectional drawing showing the process of producing the shaping | molding die 10. FIG. Specifically, FIG. 6 is a cross-sectional view of the substrate 20 for producing the mold 10. FIG. 7 is a cross-sectional view illustrating a process of forming the first mask layer 21. FIG. 8 is a cross-sectional view illustrating a process of forming the second mask layer 22. FIG. 9 is a cross-sectional view showing a process of etching the first mask layer 21 from above the patterned second mask layer 22. FIG. 10 is a cross-sectional view showing a process of forming the mold 10 by etching the substrate 20 from above the patterned first mask layer 21.

  First, a substrate 20 for forming the mold 10 shown in FIG. 6 is prepared. The substrate 20 may be a quartz glass substrate of 20 mm × 20 mm × 5 mm, for example. Quartz glass is a material having excellent high-temperature strength, heat resistance, and less surface roughness due to dry etching. Therefore, a high-definition mold 10 can be obtained by using a substrate 20 made of quartz glass. Next, as shown in FIG. 7, a first mask layer 21 made of chromium or the like is formed on the substrate 20 by, eg, sputtering. The thickness of the first mask layer 21 can be set to, for example, about 0.1 μm. Prior to the formation of the first mask layer 21, the surface of the substrate 20 on the side on which the first mask layer 21 is formed is subjected to high precision grinding and polishing, for example, Ra (arithmetic) defined in JIS. It is preferable that the surface is flattened to an average roughness) of about 20 nm.

Further, as shown in FIG. 8, a second mask layer 22 made of an X-ray photosensitive material such as PMMA is formed on the first mask layer 21 by using, for example, a spin coating method. The layer thickness of the second mask layer 22 can be set to, for example, about 0.5 μm. Then, using an EB (electron beam) drawing method or the like, patterning is performed into a shape corresponding to the shape of the forming portion 12 and the linear protrusion portion 15 of the forming die 10 on which the second mask layer 22 is to be formed. After that, as shown in FIG. 9, the first mask layer 21 is etched (for example, wet etching) from above the patterned second mask layer 22 to be patterned. Then, as shown in FIG. 10, the substrate 20 can be processed into the mold 10 by etching the substrate 20 from above the patterned first mask layer 21. When the substrate 20 is a quartz substrate, the etching of the substrate 20 can be performed in an RF dry etching apparatus using, for example, a mixed gas of CHF ₃ gas and O ₂ gas as an etching gas. The first mask layer 21 is removed from the substrate 20 in the etching process of the substrate 20.

  Further, if necessary, a release film (for example, an Ir—Rh alloy film having a thickness of about 0.05 μm) may be formed on the surface 11 of the obtained mold 10.

  As described above, the preferred embodiment of the present invention has been described by taking the production of the parallel plate-shaped antireflection uneven structure 1 as an example, but the shape of the antireflection uneven structure 1 manufactured in the present invention is particularly limited. Instead, it may be, for example, a biconcave lens shape, a biconvex lens shape, a single flat concave lens shape or a convex lens shape, a meniscus lens shape, a cylindrical shape (such as a cylindrical shape), or a columnar shape (such as a prismatic shape or a cylindrical shape). As a further example, in the following Embodiment 2, an embodiment of the present invention will be further described by taking as an example the production of the antireflection uneven structure 50 as a biconvex lens-like optical element. In the following description of the second embodiment, components having substantially the same function will be described with reference numerals common to the first embodiment, and description thereof will be omitted.

(Embodiment 2)
FIG. 11 is a cross-sectional view of the antireflection concavo-convex structure 50 manufactured in the second embodiment.

  The antireflection concavo-convex structure 50 is a biconvex lens, and the antireflection concavo-convex structure 2 including a plurality of conical concave portions 3 is formed on both lens surfaces 50a and 50b. Such an antireflection concavo-convex structure 50 is very difficult to manufacture by the conventional manufacturing method by etching, but can be easily manufactured by the press molding method as follows. Also in the second embodiment, since the molded object 70 in a cured state does not contact the molding surface 62 of the molding die 60, deformation / damage of the molding die 60 is suppressed, and a highly accurate antireflection uneven structure. 50 can be manufactured stably.

  12 and 13 are cross-sectional views showing the manufacturing process of the antireflection concavo-convex structure 50. Specifically, FIG. 12 is a cross-sectional view illustrating a process of press-molding the molding 70. FIG. 13 is a cross-sectional view showing a state after the molding 70 is press-molded.

  First, the molds 60a and 60b as shown in FIG. 12 (the molds 60a and 60b may be collectively referred to as the mold 60. The description of the mold 60a and the mold 60b has substantially the same function. The component is referred to by a common code). Specifically, the molding die 60 has a molding part in which a structure 62 composed of a plurality of conical projections 63 corresponding to the surface 50a or 50b on which the antireflection uneven structure 2 is formed is formed on one surface thereof. 61 and a projecting portion 64 having a rectangular cross section formed in a ring shape so as to project from the forming portion 61 around the forming portion 61.

  Next, the molding object 70 is placed on the molding die 60a, and the molding die 60b is placed thereon. Here, the molded object 70 is formed in a disk shape having a substantially elliptical cross section, and is disposed so as to contact the protruding portion 64 of the molding dies 60 a and 60 b but not to the molded portion 61. For this reason, it is suppressed that the to-be-molded product 70 in a hardening state contacts the plurality of cone-shaped projections 63 formed in the molding part 61, and deformation / damage of the molding part 61 is prevented. Therefore, similarly to the first embodiment, the antireflection concavo-convex structure 50 can be stably manufactured with high definition.

  Next, after the molding 70 is softened by heating or the like together with the molding dies 60a and 60b, the molding 70 is press-molded with the molding dies 60a and 60b as shown in FIG. The shape is transferred to the molding 70 to mold the antireflection uneven structure 50. Also in this pressing process, since the molding 70 that contacts the molding part 61 is in a softened state, the molding part 61 is less likely to be deformed or damaged in the pressing process.

  Finally, the formed antireflection concavo-convex structure 50 is cured by cooling or the like, and is taken out of the molds 60a and 60b to complete the antireflection concavo-convex structure 50.

  The present invention is widely applicable to optical elements such as screens, lens barrels, shielding members, fluorescent lamps, and solar cells in addition to optical elements such as lens elements, prism elements, and mirror elements that require antireflection effects. These are suitable for an optical pickup optical system of an optical reproducing / recording apparatus on which an optical element or optical member is mounted, a photographing optical type of a digital still camera, a projection system and an illumination system of a projector, an optical scanning optical system, and the like.

1 is a cross-sectional view of an antireflection uneven structure 1. FIG. 1 is a cross-sectional view of a mold 10. 4 is a cross-sectional view illustrating a configuration of a main part of the manufacturing apparatus 4. FIG. It is sectional drawing showing the process of press-molding the to-be-molded product. It is sectional drawing showing the process of taking out the shaping | molding antireflection uneven structure 1. 2 is a cross-sectional view of a substrate 20. FIG. 5 is a cross-sectional view illustrating a process of forming a first mask layer 21. FIG. 5 is a cross-sectional view illustrating a process of forming a second mask layer 22. FIG. 5 is a cross-sectional view illustrating a process of etching the first mask layer 21 from above the patterned second mask layer 22. FIG. FIG. 5 is a cross-sectional view illustrating a process of forming the mold 10 by etching the substrate 20 from above the patterned first mask layer 21. 3 is a cross-sectional view of an antireflection concavo-convex structure 50. FIG. It is sectional drawing showing the process of press-molding the to-be-molded product. It is sectional drawing showing the state after the to-be-molded product 70 is press-molded.

Explanation of symbols

1, 50 Unreflective structure for antireflection
2 Anti-reflective uneven structure
3 Conical recess
4 Manufacturing equipment
10, 60 Mold
12, 61 Molding part
14, 63 Cone-shaped protrusion
15, 64 Protrusion
20 substrates
21 First mask layer
22 Second mask layer
30 torso
40, 70 molding

Claims (5)

A method for producing a structure in which a fine uneven structure is formed on a surface,
A molding part having a shape corresponding to the concavo-convex structure and a projection part protruding from the molding part are in contact with the projection part while being spaced apart from the molding part with respect to a molding die formed on one surface. Placing the molding on
A step of softening the molded article arranged above;
Obtaining the structure by press-molding the softened article with the molding part of the mold; and
A method of manufacturing a structure comprising: In the manufacturing method of the structure according to claim 1,
The concavo-convex structure includes a plurality of surfaces inclined with respect to the surface direction, and suppresses light reflection. In the manufacturing method of the structure according to claim 1,
The concavo-convex structure includes a plurality of cone-shaped projections, and suppresses reflection of light having a pitch or more between the plurality of cone-shaped projections. In the manufacturing method of the structure according to claim 1,
The manufacturing method of a structure, wherein the concavo-convex structure is constituted by a plurality of conical recesses, and suppresses reflection of light having a pitch or more between the plurality of conical recesses. In the manufacturing method of the structure according to claim 1,
The said structure is a manufacturing method of the structure which is an optical element.

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