JPWO2014112593A1 - Manufacturing method of optical element and manufacturing method of antireflection structure - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing an optical element that can uniformly and easily produce an antireflection structure on the entire non-flat surface. A method of manufacturing an optical element array 100, which is an optical element having a first optical surface 11d that is a macroscopic non-flat surface, wherein the first optical surface 11d is divided into a plurality of regions, and the first of the divided plurality of regions is the first. A first mask forming step of forming an island-shaped mask for one region, and the first region where the island-shaped mask is formed by the first mask forming step is etched to prevent reflection in the first region A first etching step for forming the structure 51; a second mask forming step for forming an island-shaped mask for a second region different from the first region among the plurality of regions after the first etching step; A second etching step of etching the second region where the island-shaped mask is formed by the second mask forming step to form the antireflection structure 51 in the second region.

Description

  The present invention relates to a method for manufacturing an optical element having an antireflection structure on the surface of the optical element, and a method for manufacturing the antireflection structure.

  In general, an optical lens used in a camera module or the like is subjected to antireflection processing in order to reduce ghost and flare due to surface reflection. As the most general antireflection processing, there is a method of providing an optical thin film called an antireflection film (see, for example, Patent Document 1).

  As another antireflection processing method, there is a method of providing an antireflection structure. The antireflection structure is formed by forming a concave / convex shape of light wavelength scale on the surface of an optical element such as a lens or a portion having a low density when viewed macroscopically, and reduces reflection. As a method for manufacturing the antireflection structure, there is a method in which a negative mold having an antireflection structure is prepared in a mold for molding, and the antireflection structure is transferred at the time of molding (for example, see Patent Document 2). As a method for manufacturing the antireflection structure, there is a method in which an island-shaped pattern mask is formed on a substrate by vapor deposition, and then etching is performed (for example, see Patent Document 3). Further, there is a method in which a single particle film is transferred onto a substrate and etching is performed using this single particle film as a mask (see, for example, Patent Document 4).

  When a mold is used as a method for producing a structure as in the method of Patent Document 2, an increase in the adhesion area with the resin results in an inhomogeneous optical element due to a defective mold release or deterioration of the mold. There are problems such as complicated die fabrication and very high costs.

  The method of Patent Document 3 is suitable for forming a mask with a flat surface, but it is difficult to form a mask uniformly at different surface angles on an optical surface having a relatively large curvature, and an island mask is formed at different surface angles. Difficult to form uniformly. Therefore, for example, it is difficult to uniformly produce a fine uneven structure on the entire curved surface. Further, in the method of Patent Document 4, it is difficult to uniformly apply a single particle film to a curved surface, and it takes time to transfer the single particle film.

  As a technique related to the manufacture of an optical element, there is a method of forming a lens surface by using a photoresist as a mask (see, for example, Patent Document 5). In this method, a resist mask having a desired thickness distribution is formed by tilting exposure light according to the curved surface of the optical surface of the lens, and an antireflection structure is formed by etching such as dry etching. It is conceivable to apply this to form a mask on a curved surface, but the light intensity decreases as the incident angle of exposure light increases, so the resist film thickness varies depending on the incident angle of exposure light, and the mask is uniform. Difficult to form. In addition, the light source must be tilted according to the curved surface, which complicates the apparatus. Further, it takes time to form a mask, and it is costly to process each lens. In addition, a method of producing an antireflection structure on the surface of a substrate by EB (Electron Beam) drawing is also conceivable, but there are problems in terms of feasibility and cost.

Special table 2010-519881 JP 2005-31538 A Special table 2010-511079 gazette JP 2009-034630 A JP 2004-309794 A

  An object of this invention is to provide the manufacturing method of the optical element which can produce the reflection preventing structure uniformly and easily on the whole non-flat surface.

  Another object of the present invention is to provide a method for producing the antireflection structure.

  In order to solve the above problems, an optical element manufacturing method according to the present invention is a method of manufacturing an optical element having a macroscopic non-flat surface, and the macro non-flat surface is divided into a plurality of regions. A first mask forming step of forming an island-shaped mask for the first region of the plurality of regions, and etching the first region where the island-shaped mask is formed by the first mask forming step; A first etching step of forming an antireflection structure in one region, and a second step of forming an island-shaped mask for a second region different from the first region after the first etching step. A mask forming step, and a second etching step of etching the second region where the island-shaped mask is formed by the second mask forming step to form an antireflection structure in the second region. Here, the macroscopic non-flat surface means a curved surface (a surface having a relatively large curvature) or a composite surface including a surface having a large surface angle. In addition, the first and second regions collectively refer to regions where island-shaped mask formation and etching are performed by a single mask formation step and etching step. That is, even if it is actually divided into a plurality of regions, it can be regarded as one region if island-shaped mask formation or etching is performed by a single mask formation step or etching step.

  According to the method for manufacturing an optical element, an antireflection structure can be relatively uniformly formed on a macroscopic non-flat surface. Therefore, the reflected light on the macroscopic non-flat surface is reduced, and the ghost that can be generated by the reflected light can be suppressed. When a mask is formed by a directional method, the ease with which a mask is formed differs between a portion having a relatively large surface angle and a portion having a relatively small surface angle on a macroscopic non-flat surface. However, the macroscopic non-flat surface is divided into a plurality of regions, and an anti-reflection structure is provided for the macro non-flat surface by providing a step of forming an island mask and an etching step for each of the divided regions. The body can be produced relatively uniformly. Thus, since it is not necessary to form a mask having a uniform thickness over the entire non-flat surface, the antireflection structure can be easily formed over the entire non-flat surface at low cost. Moreover, compared with the case where an antireflection film is provided, high heat resistance can be obtained by providing an antireflection structure.

  In a specific aspect or viewpoint of the present invention, in the optical element manufacturing method, the first region is a region having a relatively small surface angle with respect to the optical axis of the optical element among the macroscopic non-flat surfaces. . In this case, it is difficult to control mask formation in the subsequent second mask formation step and second etching step because the antireflection structure is formed in advance in a portion where the surface angle at which the antireflection structure is easy to produce is relatively small. A portion having a relatively large angle can be selectively processed.

  In another aspect of the present invention, in the second mask formation step, a mask is formed so as to entirely cover the antireflection structure formed in the first region by the first etching step, and the first region An island mask is formed for a second region different from the first region. In this case, in the second etching step, the antireflection structure formed in the first region covered with the mask is hardly etched, and the second region where the island-shaped mask is formed is preferentially etched. The Thereby, a more uniform antireflection structure can be formed over the entire non-flat surface. Here, covering the entire antireflection structure formed in the first region is based on a certain threshold regarding a height having an antireflection function in the uneven region including the structure. It means a state in which the area exceeding the threshold is substantially covered.

  In still another aspect of the present invention, the average film thickness of the first mask formed in the first mask formation process is different from the average film thickness of the second mask formed in the second mask formation process. By changing the thickness of the mask to be formed with respect to the macroscopic non-flat surface, the region where the island-shaped mask is formed can be adjusted. That is, a region different from the first region is obtained by making the average film thickness of the first mask formed in the first mask formation step different from the average film thickness of the second mask formed in the second mask formation step. It is possible to form an island-shaped mask.

  In still another aspect of the present invention, the average film thickness of the first mask formed in the first mask forming process is thinner than the average film thickness of the second mask formed in the second mask forming process. In this case, the island-shaped mask formed in the first mask forming step can be used for forming the antireflection structure, and the island-shaped mask portion of the mask formed in the second mask forming step is used for forming the antireflection structure. Available.

  In still another aspect of the present invention, the average thickness of the first mask formed in the first mask forming step is thicker than the average thickness of the second mask formed in the second mask forming step. In this case, the island-shaped mask portion of the mask formed in the first mask forming process can be used for forming the antireflection structure, and the island-shaped mask formed in the second mask forming process is used for forming the antireflection structure. Available.

  In still another aspect of the present invention, a mask removing step for removing a mask attached to a macroscopic non-flat surface is provided between the first etching step and the second mask forming step.

  In still another aspect of the present invention, the method includes a mask removal step of removing the mask attached to the macroscopic non-flat surface after the second etching step.

  In still another aspect of the present invention, the mask is formed by any one of vapor deposition, sputtering, and CVD in the first mask formation step and the second mask formation step. In this case, a mask having a film thickness suitable for forming the antireflection structure can be formed by utilizing the characteristics of mask formation by a directional method such as vapor deposition, sputtering, and CVD.

  In still another aspect of the present invention, the macroscopic non-flat surface is etched with either an ion beam or plasma in the first etching step and the second etching step.

  In still another aspect of the present invention, a region different from the first and second regions among the plurality of regions is divided into one or more, and a mask forming step similar to at least one of the first and second mask forming steps; An etching process similar to at least one of the first and second etching processes is performed once or more. In this case, the macroscopic non-flat surface is divided into three or more regions, and a mask formation step and an etching step are performed for each region. Thereby, the antireflection structure can be formed gradually or stepwise on the non-flat surface, and a more uniform structure can be produced even on a surface with a large curvature.

  In order to solve the above problems, a method for producing an antireflection structure according to the present invention is a method for producing an antireflection structure in which an antireflection structure is produced on an optical element having a macroscopic non-flat surface, A macroscopic non-flat surface is divided into a plurality of regions, and a first mask forming step of forming an island-shaped mask for the first region among the plurality of divided regions, and an island-like shape by the first mask forming step A first etching step of etching the first region in which the mask is formed to form an antireflection structure in the first region, and a first of the plurality of regions different from the first region after the first etching step. A second mask forming step of forming an island-shaped mask on the region 2 and the second region where the island-shaped mask is formed by the second mask forming step is etched to prevent reflection in the second region. Second etching step for forming structure Equipped with a.

  According to the method for manufacturing an antireflection structure, the antireflection structure can be relatively uniformly formed on a macroscopic non-flat surface. Therefore, the reflected light on the macroscopic non-flat surface is reduced, and the ghost that can be generated by the reflected light can be suppressed. Moreover, compared with the case where an antireflection film is provided, high heat resistance can be obtained by providing an antireflection structure.

1A is a plan view of the optical element of the first embodiment, FIG. 1B is a cross-sectional view taken along the line AA of the optical element shown in FIG. 1A, and FIG. 1C is a stack of the optical elements shown in FIG. It is an expanded sectional view of the separated lens unit. It is the elements on larger scale explaining the reflection preventing structure of the optical element of FIG. 1A, etc. It is a conceptual diagram of the section explaining the metallic mold used for manufacture of the optical element of Drawing 1A. It is a conceptual diagram explaining the processing apparatus used for manufacture of the optical element of FIG. 1A. 5A to 5C are diagrams for explaining a molding process of the optical element of FIG. 1A. It is a flowchart explaining the manufacturing process of the optical element of FIG. 1A. FIG. 7A is a conceptual diagram for explaining a first mask forming step in the manufacturing process of the optical element of FIG. 1A, and FIGS. 7B and 7C are conceptual diagrams for explaining a first etching step. FIG. 8A is a conceptual diagram illustrating a first mask forming step in the optical element manufacturing process of FIG. 1A, FIG. 8B is a conceptual diagram illustrating a first etching step, and FIG. 8C is a second mask. FIG. 8D is a conceptual diagram illustrating a forming process, and FIG. 8D is a conceptual diagram illustrating a second etching process. 9A and 9B are conceptual diagrams for explaining a second mask forming step in the manufacturing process of the optical element of FIG. 1A, and FIGS. 9C and 9D are conceptual diagrams for explaining a second etching step. It is a flowchart explaining the manufacturing process of the lens unit of FIG. 1C. 11A and 11B are diagrams illustrating an example and a comparative example of the optical element in FIG. 1A. 12A is a diagram illustrating an example of the optical element in FIG. 1A, and FIG. 12B is a diagram illustrating a comparative example. 13A and 13B are views for explaining an optical element according to the second embodiment. 14A and 14B are views for explaining an optical element according to the third embodiment. FIG. 15A is a conceptual diagram for explaining a first mask forming step in the optical element manufacturing process of the fourth embodiment, FIG. 15B is a conceptual diagram for explaining a first etching step, and FIG. 15C is a mask. It is a conceptual diagram explaining a removal process. FIG. 16A is a conceptual diagram for explaining a second mask forming step in the optical element manufacturing process of the fourth embodiment, and FIG. 16B is a conceptual diagram for explaining a second etching step.

[First Embodiment]
A method for manufacturing an optical element and a method for manufacturing an antireflection structure according to the first embodiment of the present invention will be described with reference to the drawings.

A lens unit 200 as an optical element shown in FIG. 1C is formed by laminating and cutting the optical element array 100 shown in FIGS. 1A and 1B. Here, the optical element array 100 will be described first. The optical element array 100 itself can be used as an optical element.
Optical Element Array As shown in FIGS. 1A and 1B, the optical element array 100 has a disc shape and includes a substrate 101, a first lens array layer 102, and a second lens array layer 103. The optical element array 100 has a structure in which composite lenses 10 described later are integrated in a matrix. For convenience of explanation, only four compound lenses 10 are shown, but the actual optical element array 100 includes a large number of compound lenses 10. Here, the first and second lens array layers 102 and 103 are bonded to the substrate 101 in alignment with each other with respect to translation in the XY plane perpendicular to the axis AX and rotation around the axis AX.

  The substrate 101 of the optical element array 100 is a circular flat plate extending along the XY plane, and is used for the purpose of stabilizing the shape of the optical element array 100 and facilitating molding. The substrate 101 is formed of resin, glass, photonic crystal, and those obtained by adding an additive thereto. In particular, glass and transparent resin excellent in light transmittance, and those obtained by adding additives to these are preferable. The thickness of the substrate 101 is basically determined by optical specifications. One or both surfaces of the substrate 101 may be subjected to surface treatment such as plasma, ion beam, polishing, heat treatment, dry etching, or wet etching according to the purpose such as cleaning or surface modification. Further, one or both surfaces of the substrate 101 may be subjected to processing such as protective film, resist processing, optical thin film deposition, etc., and surface processing and shape processing may be performed by cutting, molding, dicing, polishing, blasting, or the like. It may be done. For example, patterning of the lens diaphragm can be performed by resist processing using a black resin material. Further, by providing an infrared cut filter film on one side or both sides of the substrate 101, noise to the image sensor can be reduced.

  The first lens array layer 102 is made of resin and is formed on one surface 101 b of the substrate 101. The first lens array layer 102 is formed so as to cover the entire surface of the substrate 101 in consideration of ease of molding. The first lens array layer 102 has a circular outer shape in plan view, and includes a large number of first lens elements 11. The first lens element 11 includes a first lens body 11a and a first flange portion 11b as a set. The first lens elements 11 are two-dimensionally arranged at equal intervals in the XY plane. These first lens elements 11 are integrally molded through a flat connecting portion 11c. The shape of each first lens element 11 is substantially the same. The combined surface of the first lens element 11 and the connecting portion 11c is a first molding surface 102a that is collectively molded by transfer. The first lens body 11a is, for example, an aspheric lens part, and has a convex first optical surface 11d as an optical function part. In other words, the first optical surface 11d has a curved surface and is a macroscopic non-flat surface unlike the first flange surface 11g. The surrounding first flange portion 11b has a flat first flange surface 11g extending around the first optical surface 11d, and the outer periphery of the first flange portion 11b is also a connecting portion 11c. The first flange surface 11g is disposed in parallel to the XY plane perpendicular to the optical axis OA.

  As a material used for the first lens array layer 102, for example, a thermosetting resin, a thermoplastic resin, a photocurable resin, an organic-inorganic hybrid material, or the like is used. Specifically, examples of the photocurable resin include acrylic resin, allyl resin, epoxy resin, and fluorine resin. Examples of the thermosetting resin include a fluorine resin and a silicone resin. Examples of the thermoplastic resin include polycarbonate, polymethyl methacrylate, and cyclic olefin copolymer. Examples of the organic / inorganic hybrid material include polyimide / titania hybrid. The material used for the first lens array layer 102 is preferably a thermosetting resin or a photocurable resin, particularly considering heat resistance and good workability. By using a resin having a melting point of 200 ° C. or higher, or a resin that is unlikely to deteriorate such as cracks when heated to 200 ° C. or higher, the first optical surface 11d is deteriorated in the reflow process after molding or the shape of the antireflection structure described later. , Color and other changes can be suppressed.

  As shown in an enlarged view in FIG. 2, an antireflection structure 51 is provided on the first optical surface 11 d of the first lens element 11. In FIG. 2, in practice, the boundary between the first optical surface 11 d and the antireflection structure 51 does not exist clearly, but is indicated by a dotted line for convenience.

  The antireflection structure 51 is formed with a substantially uniform density on the entire surface of the first optical surface 11d, which is a macroscopic flat surface. The first optical surface 11d has a curved surface as described above, and when the first optical surface 11d is divided into a plurality of regions, the first region and a second region different from the first region among the plurality of regions. And divided. Specifically, a portion A1 having a relatively small surface angle with respect to the optical axis OA as the first region (the apex side of the first optical surface 11d) and a portion A2 having a relatively large surface angle as the second region ( And the outer edge side of the first optical surface 11d). The antireflection structure 51 is not formed in a lump but is formed in at least two manufacturing steps. Specifically, first, the first antireflection structure 51a is formed in the portion A1 having a relatively small surface angle. Thereafter, the second antireflection structure 51b is formed in the portion A2 having a relatively large surface angle. In the case of the present embodiment, the second mask MB formed in the manufacturing process of the antireflection structure 51 hardly remains on the second antireflection structure 51b of the antireflection structure 51, but the first reflection The second mask MB remains on the prevention structure 51a.

  The antireflection structure 51 has fine uneven shapes (that is, shapes in which fine protrusions are densely arranged) randomly arranged in a plane such as the first optical surface 11d. The antireflection structure 51 has a tapered structure in which the volume density of the concavo-convex shape increases from the incident light side toward the optical element center side. That is, the antireflection structure 51 is a collection of substantially cone-shaped fine protrusions. The roughness (Rz: 10-point average roughness) of the antireflection structure 51 is 10 nm or more and 1000 nm or less. The roughness Rz of the antireflection structure 51 is preferably 50 nm or more and 800 nm or less, and more preferably 250 nm or more and 800 nm or less. The antireflection structure 51 is formed by using an ion beam or plasma. In general, the reflectance at a certain interface is determined by the difference in refractive index between two spaces sandwiching the interface, and the surface reflectance increases as the difference increases. Since the antireflection structure 51 has a concavo-convex shape of the use wavelength level or less formed on the first optical surface 11d, there is a sudden change in refractive index between the antireflection structure 51 and the first optical surface 11d. There are no interfaces. Thereby, the refractive index change in the antireflection structure 51 becomes gradual, and the surface reflectance decreases. This effect does not depend on the wavelength or the incident angle. Therefore, the antireflection structure 51 can suppress wavelength dependency and angle dependency as compared with a conventional structure having a low refractive index layer or the like.

  Returning to FIG. 1B, the second lens array layer 103 is also made of resin and is formed on the other surface 101 c of the substrate 101. The second lens array layer 103 has a circular outer shape in a plan view, and two-dimensionally includes a plurality of second lens elements 12 each including the second lens body 12a and the second flange portion 12b in the XY plane. Are arranged at equal intervals. These second lens elements 12 are integrally molded via a flat connecting portion 12c. The combined surface of each second lens element 12 and the connecting portion 12c is a second molding surface 103a that is collectively molded by transfer. The second lens body 12a is, for example, an aspheric lens part, and has a concave second optical surface 12d as an optical function part. The surrounding second flange portion 12b has a flat second flange surface 12g extending around the second optical surface 12d, and the outer periphery of the second flange portion 12b is also a connecting portion 12c. The second flange surface 12g is disposed in parallel to the XY plane perpendicular to the optical axis OA. On the first optical surface 12d of the second lens element 12, an antireflection structure 51 shown in an enlarged manner in FIG. 2 is provided. Similar to the first optical surface 11d of the first lens element 11, the antireflection structure 51 includes a first antireflection structure 51a and a second antireflection structure 51b. That is, the first antireflection structure 51a is formed in the portion A1 having a relatively small surface angle with respect to the optical axis OA, and the second antireflection structure 51b is formed in the portion A2 having a relatively large surface angle. Since the shape, material, etc. of the second lens array layer 103 are the same as those of the first lens array layer 102, description thereof is omitted.

  In the optical element array 100, a stop may be provided between the substrate 101 and the first lens array layer 102 or between the substrate 101 and the second lens array layer 103. In this case, the aperture of the diaphragm is arranged in alignment with each of the first and second lens bodies 11a and 12a.

Lens Unit Hereinafter, the lens unit 200 separated from the optical element array 100 will be described with reference to FIG. 1C.

  The lens unit 200 is used as an imaging lens, for example. The lens unit 200 includes a first compound lens 10 and a second compound lens 110. The lens unit 200 is obtained by stacking and joining the optical element array 100 shown in FIGS. 1A and 1B and another optical element array, and then cutting out by dicing. Here, the dotted lines in FIG. 1A showing the optical element array 100 before cutting out indicate the outer edges of the multiple compound lenses 10 arranged at the lattice points. The outside of the compound lens 10 across the boundary line of each compound lens 10 is the connecting portions 11c and 12c.

  As shown in FIG. 1C, the compound lens 10 is a quadrangular prism-like member, and has a quadrangular outline when viewed from the optical axis OA direction. The compound lens 10 includes the first lens element 11, the second lens element 12, and the flat plate portion 13 sandwiched therebetween. The flat plate portion 13 is a portion obtained by cutting out the substrate 101.

  The second compound lens 110 has substantially the same configuration as the first compound lens 10, and includes a first lens element 111, a second lens element 112, and a flat plate portion 113.

  The lens unit 200 is housed in a separately prepared holder, for example, and is bonded to the imaging circuit board as an imaging lens.

  According to the lens unit 200 described above, since the second antireflection structure 51b is formed so as to extend to a region outside the first antireflection structure 51a of the base covered with the second mask MB, it is macroscopic. Thus, the antireflection structure 51 is formed relatively uniformly on the entire first and second optical surfaces 11d and 12d, which are non-flat surfaces. Therefore, the reflected light on the first and second optical surfaces 11d and 12d is reduced, and a ghost that can be generated by the reflected light can be suppressed. Further, since the antireflection structure 51 is formed of the same material as the first and second optical surfaces 11d and 12d, it is possible to prevent the occurrence of defects such as film peeling and cracks. Further, by using the optical element array 100 having the uniform antireflection structure 51, the lens unit 200 having high-precision optical characteristics is obtained.

Method of Manufacturing Optical Element Array Hereinafter, an example of a lens manufacturing apparatus for manufacturing the optical element array 100 shown in FIG. 1A and the like will be described with reference to FIGS. The lens manufacturing apparatus includes a molding device shown in FIG. 3 (only the molding die 40 is shown) and a processing device 60 shown in FIG.

  The molding apparatus is used for molding the optical element array 100 by pouring a fluid resin into the molding die 40 and solidifying it. Although illustration is omitted, in addition to the molding die 40 which is a main member, the molding apparatus applies a mold lifting and lowering device for causing the molding die 40 to move, open and close, and resin. A resin coating device for solidifying the resin, a UV light generating device for solidifying the resin, a mold release device for taking out the molded optical element array 100, a control driving device for driving these devices, and the like.

  As shown in FIG. 3, the molding die 40 includes a first die 41, a second die 42, and a spacer 43. The first lens array layer 102 and the second lens array layer 103 are sequentially formed on both surfaces 101b and 101c of the substrate 101, and the first mold 41 is located on the one surface 101b side that becomes the upper side of the substrate 101 when releasing. The second mold 42 is placed in close contact with the second lens array layer 103 on the other surface 101 c side, which is the lower side of the substrate 101.

  The first mold 41 is for molding the first molding surface 102 a of the optical element array 100. The first mold 41 is made of, for example, light transmissive glass and has a thick disk-shaped outer shape. The first mold 41 has a first transfer surface 41 b corresponding to the first molding surface 102 a of the first lens array layer 102 on the end surface 41 a on the substrate 101 side. That is, a plurality of first transfer surfaces 41b are formed on the end surface 41a. The first transfer surface 41b includes a first optical surface transfer surface 41c for forming the first optical surface 11d of the first molding surface 102a and a first flange surface transfer surface 41d for forming the first flange surface 11g. Including.

  The second mold 42 is for molding the second molding surface 103 a of the optical element array 100. Similarly to the first mold 41, the second mold 42 is made of, for example, light-transmitting glass and has a thick disk-shaped outer shape. The second mold 42 has a second transfer surface 42 b corresponding to the second molding surface 103 a of the second lens array layer 103 on the end surface 42 a on the substrate 101 side. The second transfer surface 42b includes a second optical surface transfer surface 42c for forming the second optical surface 12d of the second molding surface 103a and a second flange surface transfer surface 42d for forming the second flange surface 12g. Including.

  The spacer 43 forms the side surface 100 a of the optical element array 100 and defines the thickness of the first and second lens array layers 102 and 103. The spacer 43 is sandwiched between the first mold 41 and the second mold 42 and has an annular outer shape.

  As shown in FIG. 4, the processing device 60 includes a vacuum chamber 61, a stage 62, an ion gun 63, a neutralization gun 64, a vapor deposition device 65, gas supply units 66 and 67, a gas discharge unit 68, And a control unit 69.

  The vacuum chamber 61 is for keeping the inside of the processing apparatus 60 airtight. In the vacuum chamber 61, a stage 62, an ion gun 63, a neutralizing gun 64, and a vapor deposition device 65 are provided. The vacuum chamber 61 communicates with the gas supply units 66 and 67 through the port 61a, and communicates with the gas discharge unit 68 through the port 61b.

  The stage 62 is provided in the upper part of the vacuum chamber 61 and can move in the X direction, the Y direction, and the Z direction. The optical element array 100 is placed and fixed on the stage surface 62a facing the ion gun 63 and the like of the stage 62. By adjusting the position of the stage 62, the position of the optical element array 100 is adjusted.

  The ion gun 63 is for forming the antireflection structure 51 on the first and second optical surfaces 11 d and 12 d of the optical element array 100. The ion gun 63 extracts ions in the plasma by applying a voltage or the like, and discharges the ions outside the ion gun 63. Specifically, the ion gun 63 ionizes the supplied gas and applies a beam voltage between the anode 63 a and the cathode 63 b of the ion gun 63. The ion gun 63 allows ionized gas (for example, positive ions) to approach and pass the cathode 63b side, and discharges it into the vacuum chamber 61 as an ion beam. The emitted ion beam is applied to the first and second optical surfaces 11 d and 12 d of the optical element array 100 on the stage 62. As a result, the exposed resin portions in the first and second optical surfaces 11d and 12d where the first mask MA described later is not formed are etched.

  The neutralizing gun 64 is for neutralizing ions in the ion beam to suppress the influence of electrolytic distribution. An ionizing gas is introduced into the neutralizing gun 64 from a gas introduction source (not shown), and the introduced gas is ionized. When electrons generated by ionization are discharged to the vacuum chamber 61, the gas ionized by the ion gun 63 is neutralized by the electrons. A neutralization grid may be used instead of the neutralization gun 64.

The vapor deposition device 65 is for forming a first mask MA, which will be described later, on the optical element array 100. The vapor deposition apparatus 65 is, for example, SiO ₂ , Al ₂ O ₃ , MgF ₂ , ZrO ₂ , TiO ₂ , Ta ₂ O ₅ , CeO ₂ , ZnO, ZnS, MgO, In, Si, Cr, Al, Ag, and a mixture thereof. Vacuum deposition is performed. Thereby, the first mask MA having different thicknesses depending on the surface angle can be formed on the first and second optical surfaces 11 d and 12 d of the optical element array 100. Note that if a sputtering device or an ion beam sputtering device is provided instead of the vapor deposition device 65, sputtering, ion beam sputtering, or the like can be performed. Further, the first mask MA may be formed using a CVD apparatus without using the vapor deposition apparatus 65.

The gas supply units 66 and 67 supply an introduction gas for irradiating an ion beam. As the introduction gas, an inert gas and a reactive gas are used. Examples of the inert gas include argon (Ar), nitrogen (N ₂ ), helium (He), krypton (Kr), neon (Ne), and a mixed gas thereof. Examples of the reactive gas include oxygen (O ₂ ), carbon tetrafluoride (CF ₄ ), sulfur hexafluoride (SF ₆ ), and trifluoromethane (CHF ₃ ). Here, Ar, O ₂ , N ₂ , and a mixed gas thereof are preferable because they are relatively inexpensive. Among them, O ₂ and a mixed gas containing the same are particularly preferable because reactive etching can be simultaneously performed in addition to physical etching when the first and second optical surfaces 11d and 12d are etched.

  The gas exhaust unit 68 is for exhausting the inside of the vacuum chamber 61. The inside of the vacuum chamber 61 is exhausted to a predetermined degree of vacuum by the gas discharge unit 68.

  The control unit 69 is for controlling operations of the stage 62, the ion gun 63, the neutralization gun 64, the vapor deposition device 65, and the gas discharge unit 68.

  Hereinafter, a manufacturing process of the optical element array 100 shown in FIG. 1A and the like will be described with reference to FIGS. The manufacturing process of the wafer lens 100 roughly includes a molding process in which a resin is applied to the substrate 101 and molding, and a first antireflection structure 51a is formed on the first and second optical surfaces 11d and 12d. The structure forming step and the second structure forming step of forming the second antireflection structure 51b on the first and second optical surfaces 11d and 12d.

[Molding process]
The molding step is performed by operating a mold lifting device, a resin coating device, and a UV light generator (not shown) while using the first and second molds 41 and 42 shown in FIG.

  First, the first lens array layer 102 is formed on one surface 101b of the substrate 101 (step S11). Specifically, as shown in FIG. 5A, the side surface 101 a of the substrate 101 is fixed with a spacer 43 in advance. Here, the substrate 101 is placed on the stage SS, and the other surface 101c serving as a lower surface is brought into close contact with the upper surface of the stage SS, so that the warpage of the substrate 101 is prevented. The resin coating apparatus is operated to apply the resin onto one surface 101b which is the upper surface of the substrate 101 fixed on the stage SS. The mold lifting device is operated, and the first mold 41 is lowered toward the substrate 101 coated with resin in a state where the first mold 41 is aligned with the stage SS or the like. Between the substrate 101 and the first mold 41, the end surface 43 a of the spacer 43 is in contact with the substrate 101, and the end surface 43 b perpendicular to the end surface 43 a of the spacer 43 is in contact with the outer edge portion 41 e of the first mold 41. Resin thickness, that is, the thickness of the connecting portion 11c (first flange portion 11b) of the first lens array layer 102 is defined. The UV light generator is operated to irradiate UV light from the upper side of the first mold 41, and the resin sandwiched between the one surface 101b of the substrate 101 and the end surface 41a of the first mold 41 is solidified.

  Next, the second lens array layer 103 is formed on the other surface 101 c of the substrate 101. As shown in FIG. 5B, the mold lifting device is operated to invert the first mold 41 and the first lens array layer 102 in an integrated state. The resin coating apparatus is operated to apply the resin onto the other surface 101c of the fixed substrate 101. The mold lifting device is operated, and the second mold 42 is lowered toward the substrate 101 in a state where the second mold 42 is aligned with the first mold 41 and the like. With the end face 43c perpendicular to the end face 43a of the spacer 43 in contact with the outer edge portion 42e of the second mold 42, the resin thickness between the substrate 101 and the second mold 42, that is, the second lens array layer 103 The thickness of the connecting portion 12c (second flange portion 12b) is defined. The UV light generator is operated and UV light is irradiated from above the second mold 42 to solidify the resin.

  Finally, after the resin forming the first and second lens array layers 102 and 103 is solidified, the optical element array 100 is separated from the first and second molds 41 and 42 and the spacer 43 as shown in FIG. 5C. Mold (step S12).

[First structure forming step]
The first structure forming process includes a first mask forming process and a first etching process. By this step, the first antireflection structure 51a is formed in the portion A1 having a relatively small surface angle in the first optical surface 11d (step S13). Since the processing steps for the first and second optical surfaces 11d and 12d are the same, only the case where the antireflection structure 51 is formed on the first optical surface 11d will be described for convenience.

A) First Mask Formation Step The first mask formation step in this step is performed as a pretreatment for irradiating the optical element array 100 with an ion beam, and forms a first mask MA that spreads locally on the first optical surface 11d. To do. The first mask MA is formed in preference to the portion A1 (first region) of the first optical surface 11d having a relatively small surface angle at which the mask is easily formed. The first mask MA has a fine island pattern as shown in an enlarged view in FIGS. 7A and 8A. The first mask MA has a plurality of islands IM arranged at random. The first mask formation step is performed using a technique such as photoresist application, film deposition, or electron beam drawing. For example, when a film deposition method is used, an initial process of thin film growth is used. In the initial growth process of the thin film, a state where the growth nucleus of the film grows as an island IM, that is, island growth occurs. In the state of island growth before the film is layered, there are a portion where the island IM is present and a portion where the first optical surface 11d is exposed. Therefore, as a mask having a fine island-shaped shielding pattern. Function.

When the film deposition method is used, the first mask forming step is performed in the processing apparatus 60 as the film forming apparatus shown in FIG. The number density and size of the islands IM of the first mask MA can be appropriately changed by adjusting the film growth conditions. The average height of the deposited island IM is preferably 3 nm, for example. Examples of the material of the first mask MA include a low refractive transparent material and a high refractive transparent material. Specifically, examples of the low refractive transparent material include SiO ₂ , Al ₂ O ₃ , and MgF ₂ . Examples of the highly refractive transparent material include ZrO ₂ , TiO ₂ , ZnO, MgO, and Ta ₂ O ₅ . In particular, in the case of a low refractive transparent material, even if it remains on the antireflection structure 51, it is difficult to cause reflection. By patterning the first mask MA, a difference in etching rate occurs according to the position on the surface of the first optical surface 11d, and a fine uneven shape can be formed in a first etching step described later.
Further, when these mask materials are formed, IAD (ion-assisted deposition; a method of performing ion beam and vapor deposition simultaneously) may be employed. By performing IAD, a similar mask can be manufactured regardless of the type of substrate. This is presumably because the surface diffusion of the vapor deposition particles is promoted by the ion beam and is likely to be island-like.

  In the case where the first mask MA is formed by film deposition, as shown in FIG. 4, the first mask forming process is performed before the first etching process is performed by disposing, for example, the vapor deposition apparatus 65 in the processing apparatus 60. be able to. Thereby, the evacuation time for the first etching step can be omitted.

B) 1st etching process The 1st etching process in this process is performed by using the processing apparatus 60 as an etching apparatus shown in FIG.

  First, the optical element array 100 is arranged on the stage 62 so that an ion beam emitted from the ion gun 63 of the processing apparatus 60 is irradiated onto a target surface of the optical element array 100, that is, the first optical surface 11d.

Next, the gas in the vacuum chamber 61 is exhausted by the gas exhaust unit 68. The back pressure maintained by the exhaust is 1 × 10 ⁻¹ Pa or less. The back pressure is more preferably 1 × 10 ⁻³ Pa or less. The back pressure needs to be 1/10 or less of the introduced gas described later.

Next, an introduction gas is introduced into the vacuum chamber 61. For example, Ar, O ₂ , N ₂ , He, Kr, Ne, CF ₄ , SF ₆ , CHF ₃ , or a mixed gas thereof is used as the introduced gas. Here, when an inert gas and a reactive gas are used as the introduced gas, the etching rate can be easily adjusted. The pressure of the introduced gas is 10 Pa or less. The pressure of the introduced gas is more preferably 1 × 10 ⁻¹ Pa or less. Etching at a lower gas pressure lengthens the mean free path of ions. Therefore, the kinetic energy of ions is not easily lost before colliding with the first optical surface 11d, and the etching rate is increased. Therefore, the etching rate can be increased by setting the total pressure so that the mean free path of ions is the same as the distance between the optical element array 100 and the ion gun 63 or about 1/10. In the first etching step, the difference between the maximum etching rate and the minimum etching rate in the portion where the first optical surface 11d is disposed is within 10% of the maximum etching rate.

  An ion beam is emitted in the state of the vacuum chamber 61 described above, and ion irradiation is performed on the first optical surface 11d. At this time, the acceleration energy of ions is 1 W to 100 kW. The acceleration energy of ions is preferably 10 W to 10 kW, and more preferably 10 W to 500 W.

  By irradiation with the ion beam, as shown in FIG. 7B, the portion of the optical element array 100 where the resin is exposed is etched together with the island IM of the first mask MA. As a result, as shown in FIGS. 7C and 8B, the portion A1 of the first optical surface 11d having a relatively small surface angle with respect to the ion beam source and the deposition source is moved from the incident light side to the optical element center side or back side. A first antireflection structure 51a having a structure in which the volume density of the uneven shape increases as it goes is formed. Note that the first mask MA may remain on the first antireflection structure 51a as shown in FIG. 7B. After the first etching step, a mask removal step for removing the first mask MA attached to the first optical surface 11d may be performed. In this case, for example, the first mask MA is removed by adjusting the ion beam.

[Second structure forming step]
In the second structure forming step, the second antireflection structure 51b of the antireflection structure 51 is formed by the same method as the first mask forming step and the first etching step in the first structure forming step. That is, this process includes a second mask forming process and a second etching process. By this step, the second antireflection structure 51b is formed in the portion A2 (second region) having a relatively large surface angle in the first optical surface 11d (step S14). In addition, about the 2nd mask formation process and a 2nd etching process, description of the process element common to a 1st mask formation process and a 1st etching process is abbreviate | omitted.

A) Second Mask Formation Step In this step, the second mask MB is formed on the first optical surface 11d by the same method as the first mask formation step. The average film thickness of the second mask MB is larger than the average film thickness of the first mask MA. As a result, as shown in FIG. 8C, the obtained second mask MB is a portion having a relatively large surface angle with the main mask MB1 formed in the portion A1 having a relatively small surface angle of the first optical surface 11d. And an auxiliary mask MB2 formed on A2. As shown in FIGS. 8C and 9A, in the present embodiment, the main mask MB1 is formed so as to entirely cover the first antireflection structure 51a. In other words, the main mask MB1 is based on a certain threshold regarding the height of the protrusion or the depth of the unevenness that exhibits the antireflection function in the uneven region including the structure formed on the first optical surface 11d. As shown, the third antireflection structure 52 is formed together with the ground so as to substantially cover the region exceeding the threshold. As shown in FIGS. 8C and 9B, in the present embodiment, the auxiliary mask MB2 is an island-shaped mask portion, and is formed in a region of the first optical surface 11d where the antireflection structure 51 has not yet been formed. Yes. The auxiliary mask MB2 is thinner than the main mask MB1. The main mask MB1 is a substantially uniform film near the center of the optical axis OA, and the thickness of the thickest part is about 5 nm to 9 nm. That is, the thickness of the main mask MB1 in the second mask formation step in the second structure forming step is thicker than the thickness of the first mask MA in the first mask formation step in the first structure formation step. Similar to the first mask MA, the auxiliary mask MB2 has a fine island pattern (island IM). That is, in the portion A2 having a relatively large surface angle, there are a portion where the island IM exists and a portion where the first optical surface 11d is exposed. The auxiliary mask MB2 can function as a thinner and finer shielding pattern than the main mask MB1. Note that the boundary between the main mask MB1 and the auxiliary mask MB2 is not strict, and the second mask MB has a surface angle from a portion having the smallest surface angle with respect to the vapor deposition source (vertex on the optical axis OA in the drawing). It gradually becomes thinner toward the large outer edge. In other words, the main mask MB1 may not completely cover the first antireflection structure 51a away from the optical axis OA.

B) Second Etching Step In this step, the first optical surface 11d of the optical element array 100 is irradiated with an ion beam as in the first etching step. As a result, as shown in FIGS. 8D and 9C, together with the island IM of the auxiliary mask MB2 of the second mask MB, the exposed portion of the first optical surface 11d, that is, the portion A2 having a relatively large surface angle is etched. As a result, the second antireflection structure 51b is formed in the portion A2 having a relatively large surface angle. As a result, the entire first optical surface 11d has a concavo-convex shape as it goes from the incident light side toward the optical element center side. An antireflection structure 51 having a structure in which the volume density increases is formed.

  Note that, after the second etching step, as shown in FIG. 9D, a mask removal step of removing the second mask MB attached to the first optical surface 11d may be performed. In this case, for example, the second mask MB is removed by adjusting the ion beam. The main mask MB1 that covers the first antireflection structure 51a as a whole can be maintained or removed as it is by selecting the etching conditions and the like.

  Thus, the optical element array 100 having the antireflection structure 51 on the first optical surface 11d shown in FIG. 1A and the like is completed.

Manufacturing Method of Lens Unit Hereinafter, a manufacturing method of the lens unit 200 will be described with reference to FIG.

  First, the optical element array 100 is stacked and temporarily fixed (step S21). At this time, a part of the optical element array 100 is marked, and the optical element array 100 and another optical element array are aligned and stacked. These optical element arrays are designed to exhibit optical properties when stacked. Therefore, there is no need for optical adjustment, and the cost can be reduced.

  Next, the stacked optical element array 100 is cut (step S22). This cutting process includes a laser and a dicer.

  Thus, the lens unit 200 shown in FIG. 1C is completed.

  According to the optical element manufacturing method and the like described above, the antireflection structure 51 can be manufactured relatively uniformly on the first optical surface 11d which is a macroscopic non-flat surface. Therefore, the reflected light on the first optical surface 11d is reduced, and ghosts that can be generated by the reflected light can be suppressed. When the mask is formed by a directional method such as vapor deposition, the ease of mask formation differs between the portion A2 having a relatively large surface angle and the portion A1 having a relatively small surface angle on the first optical surface 11d. However, the first optical surface 11d is divided into a plurality of regions, and an island-shaped mask forming step and an etching step are provided for each divided region, so that the first optical surface 11d, which is a macroscopic non-flat surface, is provided. However, the antireflection structure 51 can be relatively uniformly manufactured. Thus, since it is not necessary to form a mask having a uniform film thickness over the entire non-flat surface, the antireflection structure 51 can be easily formed over the entire non-flat surface at low cost. Moreover, compared with the case where an antireflection film is provided on the first optical surface 11d, high heat resistance can be obtained by providing the antireflection structure 51.

〔Example〕
Hereinafter, examples of the first structure forming step and the second structure forming step in the present embodiment will be described.
A double-sided lens made of a thermoplastic resin was used as the base material of the antireflection structure 51. In the first mask formation step of the first structure formation step, a first mask MA of TiO ₂ was formed on an untreated substrate using the vapor deposition apparatus 65 shown in FIG. In this step, the film thickness of the first mask MA was set such that the average film thickness at the thickest part was about 3 nm. In this case, the first mask MA is formed as an island-shaped pattern in a portion A1 having a relatively small surface angle (near the apex of the first optical surface 11d) of the convex first optical surface 11d. Thereafter, in the first etching process of the first structure forming process, an ion beam etching process is performed with a mixed gas of Ar and O ₂ on the base material on which the first mask MA is formed using the ion gun 63 shown in FIG. 50 minutes. As a result, the first antireflection structure 51a of the antireflection structure 51 is produced in the portion A1 having a relatively small surface angle of the first optical surface 11d.
In this example and the comparative example, the average film thickness can be measured using a crystal resonator included in the vapor deposition apparatus 65. Specifically, the increase in mass due to the deposition of the vapor deposition material on the crystal unit is obtained from the decrease in the frequency of the crystal unit, and the average film thickness is calculated using information such as the density and impedance of the vapor deposition material. Can be calculated. Further, APEL manufactured by Mitsui Chemicals, Inc. was used for the base material that is the object of structure formation, and was molded so as to have a surface angle of about 0 ° to 75 °.

Thereafter, in the second mask forming step of the second structure forming step, a second mask MB of SiO ₂ was formed on the substrate using the vapor deposition apparatus 65 shown in FIG. In this step, the film thickness of the second mask MB is set so that the average film thickness at the thickest part is about 9 nm. In this case, the main mask MB1 of the second mask MB entirely covers a portion A1 having a relatively small surface angle (near the apex of the first optical surface 11d) of the convex first optical surface 11d. On the other hand, the auxiliary mask MB2 is formed as an island pattern in the portion A2 having a relatively large surface angle. Thereafter, in the second etching step of the second structure forming step, ion beam etching treatment was performed for 80 minutes with a mixed gas of Ar and O ₂ on the base material on which the second mask MB was formed. As a result, the second antireflection structure 51b of the antireflection structure 51 is produced in the portion A2 having a relatively large surface angle in the first optical surface 11d.

  11A, 11B, and 12A show the reflectivity of the first optical surface 11d of this example. FIG. 11A shows the visible light average reflectance with respect to the surface angle. In FIG. 11A, the line a indicates the reflectance after the first structure forming step, and the line c indicates the reflectance after the second structure forming step. . FIG. 11B shows the reflectance of the first optical surface 11d after the first structure forming step, and FIG. 12A shows the reflectance of the first optical surface 11d after the second structure forming step. In FIGS. 11B and 12A, the lines d, e, f, g, h, k, m, and n are plane angles of 0 °, 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, and 70 °, respectively. Indicates. The surface angle in the figure is an angle with respect to the optical axis OA, and the surface angle of the vertex of the first optical surface 11d is 0 °. The reflectance was measured using a microspectrophotometer (USPM-RUIII, manufactured by Olympus). The reflectance at each surface angle was measured perpendicular to the surface at each surface angle.

  As shown in FIGS. 11A and 11B, in the first optical surface 11d after the first structure forming step, the reflectance is relatively low at the surface angles of 0 ° and 20 ° corresponding to the portion A1 having a relatively small surface angle. The reflectance was relatively high at the surface angles of 40 ° and 60 ° corresponding to the portion A2 having a relatively large surface angle. On the other hand, as shown in FIG. 12A, the first optical surface 11d after the second structure forming step is reflected even at a surface angle of 40 °, 50 °, 60 °, and 70 ° corresponding to the portion A2 having a relatively large surface angle. The rate was low.

[Comparative Example]
Hereinafter, a comparative example of the second structure forming step will be described.
In the comparative example, the first mask forming step and the first etching step are the same as those in the above-described embodiment, and the film thickness of the first mask MA is set so that the average film thickness at the thickest portion is about 3 nm.

In the second mask formation step of the comparative example, a SiO ₂ mask was formed on the substrate using the vapor deposition apparatus 65 shown in FIG. In this step, the film thickness of the mask was such that the average film thickness at the thickest part was about 3 nm. In this case, the mask is formed as an island-shaped pattern in a portion A1 having a relatively small surface angle of the convex first optical surface 11d. Thereafter, in the second etching process of the comparative example, an ion beam etching process was performed for 50 minutes with a mixed gas of Ar and O ₂ on the base material on which the mask was formed using the ion gun 63 shown in FIG.

  11A, 11B, and 12B show the reflectance of the first optical surface 11d of the comparative example. FIG. 11A shows the average reflectance with respect to the surface angle. In FIG. 11A, line a shows the reflectance after the first etching step, and line b shows the reflectance after the second etching step. FIG. 11B shows the reflectance of the first optical surface 11d after the first etching step, as in the above embodiment. FIG. 12B shows the reflectance of the first optical surface 11d after the second etching step of the comparative example. It is. In FIGS. 11B and 12B, the lines d, e, f, g, h, k, m, and n are plane angles of 0 °, 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, and 70 °, respectively. Indicates. The method of measuring the reflectance is the same as in the above embodiment.

  As shown in FIGS. 11A and 11B, in the first optical surface 11d after the first etching step, the reflectance is relatively low at surface angles of 0 ° and 20 ° corresponding to the portion A1 having a relatively small surface angle. At the surface angles of 40 ° and 60 ° corresponding to the relatively large portion A2, the reflectance was relatively high as in the above-described example. On the other hand, as shown in FIG. 12B, in the first optical surface 11d after the second etching step of the comparative example, the surface angles corresponding to the portion A2 having a relatively large surface angle are 40 °, 50 °, 60 °, and 70 °. The reflectivity remains high, and the reflectivities of 0 °, 10 °, and 20 ° corresponding to A1 having a relatively low surface angle have increased.

[Second Embodiment]
Hereinafter, a method for manufacturing an optical element according to the second embodiment will be described. The optical element manufacturing method according to the second embodiment is a modification of the optical element manufacturing method according to the first embodiment, and items not specifically described are the same as those in the first embodiment.

  As shown in FIGS. 13A and 13B, the first optical surface 11d has a composite surface including a surface having a large surface angle. The first optical surface 11d is a convex surface as a whole, and the center, that is, the vicinity of the optical axis OA is recessed. As in the first embodiment, the first optical surface 11d is divided into a first region and a second region when divided into a plurality of regions. Specifically, as the second region, a portion A2 having a relatively large surface angle is provided on the center side and the outer edge side of the first optical surface 11d. Further, as the first region, the portion A1 having a relatively small surface angle is provided between the portion A2 having a relatively large surface angle and the vicinity of the center.

  In the first optical surface 11d of FIGS. 13A and 13B, the first mask MA is formed in the portion A1 having a relatively small surface angle by the first mask forming step of the first structure forming step. Further, the first antireflection structure 51a is formed in the portion A1 having a relatively small surface angle by the first etching process of the first structure forming process. In addition, the second mask forming step of the second structure forming step forms the main mask MB1 of the second mask MB in the portion A1 having a relatively small surface angle, and the auxiliary mask MB2 in the portion A2 having a relatively large surface angle. Is formed. Further, the remaining second antireflection structure 51b among the antireflection structures 51 is formed in the portion A2 having a relatively large surface angle by the second etching process of the second structure forming process.

[Third Embodiment]
Hereinafter, a method for manufacturing an optical element according to the third embodiment will be described. The optical element manufacturing method according to the third embodiment is a modification of the optical element manufacturing method according to the first embodiment, and items not particularly described are the same as those in the first embodiment.

  In the present embodiment, a region different from the first and second regions among the plurality of regions of the first optical surface 11d is divided into one or more, and after the second structure forming step, the same mask as the second mask forming step The formation process and the etching process similar to the second etching process are performed in accordance with the number of regions. That is, the antireflection structure 51 is formed by dividing the first optical surface 11d into not only the first and second regions but also three or more regions.

  For example, as conceptually shown in FIGS. 14A and 14B, a portion A3 having the largest surface angle compared to the portions A1 and A2 corresponding to the first and second regions in the first optical surface 11d is a third optical surface. As a region, the mask formation step and the etching step are performed at least once to form the second antireflection structure 51b (see FIG. 7C and the like) in the portion A3 as the third region. Here, in the mask formation step of the portion A3 which is the third region, the whole type covers not only the portion A1 as the first region but also the second antireflection structure 51b of the portion A2 as the second region. Main mask MB1 is formed.

  In this case, the thickness of the second mask MB in consideration of the formation state of the second antireflection structure 51b (FIG. 7C) in the second region and the third antireflection structure 52 (FIG. 9A) in the first region. By adjusting the second antireflection structure 51b, the second antireflection structure 51b can be formed also in the third region. At this time, the mask portion formed in the portion A2 as the second region is not limited to the thick layer covering the whole, but may be an extremely thin layer, or the density of the island pattern is the third. It may be sufficiently higher than the portion A3 as the region. Accordingly, the first optical surface 11d can be divided into a predetermined range according to the size of the surface angle, and the second antireflection structure 51b can be gradually formed from a portion having a small surface angle to a portion having a large surface angle.

  The first optical surface 11d is divided into three or more regions, and after the first structure forming step, a mask forming step for forming a discrete island mask in the same manner as the first mask step, and a first etching step The same etching process may be performed. In this case, for example, the third region has a larger surface angle than the first region and a smaller surface angle than the second region.

[Fourth Embodiment]
Hereinafter, a method for manufacturing an optical element according to the fourth embodiment will be described. The optical element manufacturing method according to the fourth embodiment is a modification of the optical element manufacturing method according to the first embodiment, and items not specifically described are the same as those in the first embodiment.

  In the present embodiment, the first optical surface 11d includes a portion A2 having a relatively large surface angle with respect to the optical axis OA as the first region (the outer edge side of the first optical surface 11d), and a surface angle as the second region. Is divided into a relatively small portion A1 (the apex side of the first optical surface 11d). In the present embodiment, in the first structure forming step, the second antireflection structure 51b is formed in the portion A2 where the surface angle of the first optical surface 11d is relatively large. In the second structure forming step, the surface angle is The first antireflection structure 51a is formed in the relatively small portion A1.

[First structure forming step]
This step includes a first mask forming step, a first etching step, and a mask removing step.

A) First Mask Formation Step First, as shown in FIG. 15A, a second mask MB is formed on the first optical surface 11d as in the second mask formation step of the first embodiment. The second mask MB has a main mask MB1 formed in a portion A1 having a relatively small surface angle of the first optical surface 11d and an auxiliary mask MB2 formed in a portion A2 having a relatively large surface angle. The main mask MB1 is formed so as to entirely cover the portion A1 having a relatively small surface angle. The auxiliary mask MB2 is an island-shaped mask portion, and is formed as a fine island-shaped pattern (island IM) in a portion A2 having a relatively large surface angle.

B) First Etching Step Next, the first optical surface 11d of the optical element array 100 is irradiated with an ion beam. As a result, as shown in FIG. 15B, together with the island IM of the auxiliary mask MB2 of the second mask MB, the exposed portion of the first optical surface 11d, that is, the portion A2 having a relatively large surface angle is etched. At this time, the portion A1 with a relatively small surface angle covering the main mask MB1 is not etched. Thereby, the second antireflection structure 51b is formed only in the portion A2 having a relatively large surface angle.

C) Mask Removal Step Next, as shown in FIG. 15C, the second mask MB attached to the first optical surface 11d is removed. Specifically, for example, the mask is removed by an ion beam or plasma, or the mask is removed by dipping in a mask removing solution.

[Second structure forming step]
This step includes a second mask forming step and a second etching step.

A) Second Mask Formation Step First, as shown in FIG. 16A, a first mask MA is formed on the first optical surface 11d as in the first mask formation step of the first embodiment. The average film thickness of the second mask MB is smaller than the average film thickness of the first mask MA. As a result, the first mask MA is formed as a fine island-shaped pattern (island IM) in a portion A1 having a relatively small surface angle of the first optical surface 11d. Since the main mask MB1 attached to the portion A1 having a relatively small surface angle is removed in the mask removal step of the previous step, the first optical surface 11d is exposed in the portion where the island IM is not formed. It is in a state. In the present embodiment, the thickness of the first mask MA in the second mask forming step in the second structure forming step is thinner than the thickness of the main mask MB1 in the first mask forming step in the first structure forming step. . As a result, a mask is hardly formed in the portion A2 having a relatively large surface angle.

B) Second etching step Next, the first optical surface 11d of the optical element array 100 is irradiated with an ion beam. As shown in FIG. 16B, together with the island IM of the first mask MA, the exposed portion of the first optical surface 11d, that is, the portion A1 having a relatively small surface angle is etched. Thereby, the first antireflection structure 51a is formed in the portion A1 having a relatively small surface angle. As a result, the antireflection structure 51 is uniformly formed on the entire first optical surface 11d.

  Note that the first mask MA attached to the first optical surface 11d may be removed after the second etching step.

  The optical element array manufacturing method according to the present embodiment has been described above. However, the optical element array manufacturing method according to the present invention is not limited to the above. For example, in the above embodiment, the shapes and sizes of the first and second optical surfaces 11d and 12d can be changed as appropriate according to the application and function.

  Moreover, in the said embodiment, each 1st and 2nd lens element 11 and 12 does not need to be connected. That is, a part of the substrate 101 may be exposed. Further, the first lens array layer 102 or the second lens array layer 103 may be provided only on one side of the substrate 101. Further, the optical element array may be formed by using only the resin without using the substrate 101. In this case, the first and second lens array layers 102 and 103 are integrally molded.

  In the above embodiment, the optical element array 100 is used for various purposes such as a mirror, a diffractive structure, an illumination component, and an optical transmission component in addition to the lens.

  Moreover, in the said embodiment, the optical element array 100 does not need to be disk shape, and can have various outlines, such as an ellipse. For example, the cutting process can be simplified by forming the optical element array 100 into a square plate shape from the beginning.

  In the above-described embodiment, the number of the first and second lens elements 11 and 12 formed in the optical element array 100 is not limited to four as illustrated, and may be two or more. At this time, the arrangement of the first and second lens elements 11 and 12 is preferably on a lattice point for convenience of dicing. Furthermore, the interval between the adjacent first and second lens elements 11 and 12 is not limited to the illustrated one, and can be set as appropriate in consideration of workability and the like.

  In the above embodiment, the resin is applied to the one surface 101b and the other surface 101c of the substrate 101, but the resin is applied to the first and second transfer surfaces 41b and 42b of the first and second molds 41 and 42. It may be applied.

  In the above-described embodiment, various methods can be used as the method for forming the optical element array 100 other than a method using a mold in which a resin is poured into the molding die 40 and solidified. For example, the optical element array 100 may be manufactured using heat fusion, heat treatment, vapor deposition, injection molding, coating, etching after deposition, or the like. In consideration of the shape accuracy and molding time of the first and second optical surfaces 11d and 12d, a method using injection molding or a mold is preferable.

  In the above embodiment, the first antireflection structure 51a may be formed in advance by another method without depending on the first structure forming step. For example, the first antireflection structure 51a can be formed by etching or the like using a photoresist, particles, or the like as a mask.

  Moreover, in the said embodiment, although the two gas supply parts 66 and 67 are provided, 1 or 3 or more may be sufficient.

  In the above embodiment, the islands IM of the mask MA may not be randomly arranged.

  Moreover, in the said embodiment, the magnitude | size of a 1st area | region and a 2nd area | region can be suitably changed with the thickness of the mask formed in a 1st and 2nd mask formation process.

  In the third embodiment, the first optical surface 11d is divided into a predetermined range according to the size of the surface angle, and the antireflection structure 51 is gradually formed from a portion having a small surface angle to a portion having a large surface angle. If the manufacturing method of the embodiment is modified, the antireflection structure 51 can be gradually formed from a portion having a large surface angle to a small portion.

  In the above embodiment, the optical element array 100 need not be stacked. Further, the optical element array 100 may be left in a wafer shape without being cut.

  In the above embodiment, in the manufacturing process of the optical element array 100, the first and second lens array layers 102 and 103 are first molded and then released. The second lens array layer 103 may be molded and released after the release. In addition, each step may be performed continuously on the first and second lens array layers 102 and 103, or each step may be performed on the first lens array layer 102 and then the second lens array layer 103 may be formed. On the other hand, you may perform each process.

  In the above embodiment, a protective layer may be provided on the antireflection structure 51. In this case, a protective layer can be formed using the vapor deposition apparatus 65 shown in FIG.

Claims (12)

A method of manufacturing an optical element having a macroscopic non-flat surface,
A first mask forming step of dividing the macroscopic non-flat surface into a plurality of regions, and forming an island-shaped mask with respect to a first region among the plurality of divided regions;
Etching the first region where the island-shaped mask is formed by the first mask forming step to form an antireflection structure in the first region; and
A second mask forming step of forming an island-shaped mask for a second region different from the first region among the plurality of regions after the first etching step;
A second etching step of etching the second region where the island-shaped mask is formed by the second mask forming step to form an antireflection structure in the second region. Method.   2. The method for manufacturing an optical element according to claim 1, wherein the first region is a region having a relatively small surface angle with respect to an optical axis of the optical element in the macroscopic non-flat surface.   In the second mask forming step, a mask is formed so as to entirely cover the antireflection structure formed in the first region by the first etching step, and the second mask is different from the first region. The method for manufacturing an optical element according to claim 1, wherein an island-shaped mask is formed for the two regions.   The average film thickness of the first mask formed in the first mask formation step and the average film thickness of the second mask formed in the second mask formation step are different from each other. The manufacturing method of the optical element of description.   5. The optical element manufacturing method according to claim 4, wherein an average film thickness of the first mask formed in the first mask formation step is thinner than an average film thickness of the second mask formed in the second mask formation step. Method.   The optical element manufacturing according to claim 4, wherein an average film thickness of the first mask formed in the first mask forming process is thicker than an average film thickness of the second mask formed in the second mask forming process. Method.   7. The method according to claim 1, further comprising a mask removal step of removing a mask attached to the macroscopic non-flat surface between the first etching step and the second mask formation step. Of manufacturing the optical element.   The method for manufacturing an optical element according to any one of claims 1 to 7, further comprising a mask removal step of removing a mask attached to the macroscopic non-flat surface after the second etching step.   The method for manufacturing an optical element according to claim 1, wherein in the first mask forming step and the second mask forming step, a mask is formed by any one of vapor deposition, sputtering, and CVD.   The optical element manufacturing method according to any one of claims 1 to 9, wherein in the first etching step and the second etching step, the macroscopic non-flat surface is etched with either an ion beam or plasma. Method.   Dividing the region different from the first and second regions into one or more of the plurality of regions, a mask formation step similar to at least one of the first and second mask formation steps, and the first and second regions The method for manufacturing an optical element according to any one of claims 1 to 10, wherein at least one of the etching steps and the same etching step are performed once or more. A method for producing an antireflection structure for producing an antireflection structure on an optical element having a macroscopic non-flat surface,
A first mask forming step of dividing the macroscopic non-flat surface into a plurality of regions, and forming an island-shaped mask with respect to a first region among the plurality of divided regions;
Etching the first region where the island-shaped mask is formed by the first mask forming step to form an antireflection structure in the first region; and
A second mask forming step of forming an island-shaped mask for a second region different from the first region among the plurality of regions after the first etching step;
An antireflection structure comprising: a second etching step of etching the second region where the island-shaped mask is formed by the second mask formation step to form an antireflection structure in the second region. Manufacturing method.

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