JP4404898B2 - Method for producing curved mold having fine concavo-convex structure and method for producing optical element using this mold - Google Patents

Description

  The present invention relates to a method for manufacturing a curved mold having a fine concavo-convex structure such as an antireflection structure, and a method for manufacturing a curved mold having a fine concavo-convex structure using a member that can be easily curved and used. The present invention relates to a method for manufacturing an optical element.

Conventionally, in an optical element such as an optical pickup using a light-transmitting material such as glass or plastic, an aspherical lens or the like, a surface treatment for preventing reflection is performed on a light incident surface of a substrate. As the surface treatment, there are a method of forming a multilayer film on which a thin dielectric film is superposed on the surface of the light-transmitting substrate by vacuum deposition or the like, and a method of providing fine and dense irregularities on the surface of the optical element.

  It has been known that an antireflection structure having a fine and dense concavo-convex shape on the surface of an optical element is formed by plastic molding using a mold (see, for example, Patent Document 1).

  A mold for molding an optical element having an antireflection structure composed of fine and dense irregularities uses quartz or silicon as a base material, and a predetermined antireflection structure is formed on this base material by etching, This base material is made by plating.

By the way, in order to provide the above-described antireflection structure in a lens having a predetermined curvature such as a lens of an optical pickup, it is necessary to perform a predetermined curved surface processing on quartz or silicon as a base material.
JP-A-62-96902

  In the case of a lens having a complicated surface shape such as an aspheric lens, it is difficult to process the base material for forming a mold. That is, when quartz, silicon, or the like is used as a base material, it is difficult to process these base materials, and cracks, chips, etc. often occur during formation, and it takes time and money to manufacture a mold. There was a problem.

  The present invention has been made to solve the above-described conventional problems, and easily manufactures a mold capable of adding a fine and precise uneven shape to a lens having a complicated surface shape such as an aspherical lens. It aims to provide a possible method.

  Another object of the present invention is to provide a method by which an optical element such as a lens having a complicated surface shape such as an aspherical lens having a fine and dense uneven surface formed thereon can be easily manufactured.

  The method for manufacturing a curved mold having a fine concavo-convex structure according to the present invention includes forming a silicon-based film on a curved base material formed in a predetermined shape, and using the mask on the silicon-based film, a fine concavo-convex structure having a predetermined shape This pattern was formed by etching, and a metal for mold was deposited on the silicon-based film on which this fine concavo-convex structure pattern was formed, and the fine concavo-convex structure pattern was transferred to this metal for mold In the method of manufacturing a curved surface mold having a fine concavo-convex structure by removing a post-silicon-based film and forming a mold having a fine concavo-convex structure on a curved surface, the mask is made of a photoresist, and the silicon-based film is formed on the curved base material. An antireflection film is formed between the two.

  A release material film may be formed between the curved base material and the silicon-based film.

  Further, according to the method of manufacturing a mold having a fine concavo-convex structure according to the present invention, a silicon-based film is formed on a curved base material formed in a predetermined shape, and an effective region portion is fine in a predetermined shape on the silicon-based film. A mask having a concavo-convex pattern, with the volume ratio of the concavo-convex pattern changing toward the outside, is provided. Using this mask, the depth of the fine concavo-convex is gradually increased in the silicon-based film from the outer periphery toward the inner periphery. The depth is increased, and a fine pattern in which unevenness of a predetermined depth and shape is formed in an effective region is formed by etching, and a metal for a mold is deposited on the substrate on which the unevenness pattern is formed, After the concave / convex pattern is transferred to the mold metal, the substrate and the mold metal are separated to form a mold.

  In the method of manufacturing an optical element according to the present invention, a silicon-based film is formed on a curved base material formed in a predetermined shape, and a fine concavo-convex structure pattern having a predetermined shape is etched using the mask on the silicon-based film. The metal film for metal mold is deposited on the silicon film on which the pattern of the fine concavo-convex structure is formed, and the silicon film is transferred to the metal for mold after transferring the pattern of the fine concavo-convex structure And forming a mold having a fine concavo-convex structure on the curved surface, attaching the mold to at least one of a fixed mold and a movable mold, and performing injection molding using the fixed mold and the movable mold, at least An optical element having a fine concavo-convex structure on one surface is manufactured.

  As described above, according to the present invention, it is possible to easily form a curved base material having a predetermined curved surface shape even if it is a complicated shape such as a spherical surface or an aspherical object, and the curved surface of the curved base material. Based on this, it is possible to form a curved surface mold having a predetermined curved surface and having a fine and dense concavo-convex shape structure even if it is a complicated shape such as a spherical surface or an aspherical object.

  In addition, since the resist patterning can be performed more precisely by providing the antireflection film, it is possible to form a curved mold having an antireflection structure having a finer and dense uneven shape.

  By using the release material film, the mold side and the base material side can be easily separated.

  In addition, the depth of the antireflection function gradually increases from the outer periphery toward the inner periphery, and by using a curved mold having an antireflection structure in which conical irregularities are formed at a predetermined pitch in the effective region, When the resin is filled, it becomes easy to peel off from the outer peripheral side, and there is no possibility that the mold (stamper) or the molded product is damaged.

It is sectional drawing which shows manufacture of the curved surface mold | die which has an antireflection structure concerning 1st Embodiment of this invention according to a process. It is sectional drawing which shows manufacture of the curved-surface metal mold | die which has an antireflection structure concerning 2nd Embodiment of this invention according to process. It is sectional drawing which shows manufacture of the curved-surface metal mold | die which has an antireflection structure concerning 3rd Embodiment of this invention according to process. It is sectional drawing which shows manufacture of the curved-surface metal mold | die which has an antireflection structure concerning 4th Embodiment of this invention according to process. It is a top view which shows the exposure process for deepening the depth of the reflection preventing function of an optical element gradually toward the inner periphery from the outer periphery of an optical element. It is a figure which shows the relationship between the metal mold | die of each area | region of the optical element manufactured by this invention, and the adhesive force of a molded article. It is side sectional drawing which shows the shape and structure of a shaping | molding die used for the manufacturing method of the optical element concerning this invention.

Explanation of symbols

1 curved member 2 the silicon dioxide film (SiO ₂₎ film 3 resist film 4 metal layers 4a, 4b mold (stamper)

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the manufacturing process of a curved mold having an antireflection structure composed of dense and fine irregularities according to the first embodiment of the present invention.

  As shown in FIG. 1A, a curved base material 1 having a predetermined curved surface shape such as a spherical surface such as an objective lens for an optical pickup or a collimator lens, or an aspherical surface for an axis is prepared. As the curved base material 1, a metal base material that can be easily processed into a curved surface, a resin base material formed from the metal mold, or a glass base material is used. In this embodiment, it is formed by mirror finishing to a predetermined curved surface such as a spherical surface or an aspherical surface of an axis by an ultra-precision micro-machining machine that rotates a diamond tool against an aluminum alloy or carbon-free copper having good machinability. Has been.

Subsequently, as shown in FIG. 1B, a silicon dioxide film (SiO ₂ ) film 2 is formed as a silicon-based film on the surface of the curved base material 1 on which a predetermined curved surface is formed by a sputtering method from 500 nm to 1 μm. About a film is formed. In this embodiment, a silicon dioxide film (SiO ₂ ) film 2 having a thickness of 900 nm is formed by RF magnetron sputtering using a SiO ₂ target. Film formation conditions at this time are as follows: a substrate temperature is 200 ° C., an argon (Ar) gas flow rate is 20 sccm, and a pressure is 1.36 Pa using a SiO ₂ target.

Then, a resist is applied on the silicon dioxide film (SiO ₂ ) film 2 as shown in FIG. The resist coating was performed by spin coating at a rotational speed of 4000 rpm using, for example, a trade name “TDUR-P009” manufactured by Tokyo Ohka Kogyo Co., Ltd. as a resist to form a resist film 3 having a thickness of 600 nm.

  Subsequently, as shown in FIG. 1D, the applied resist film 3 is exposed and developed to form a resist pattern 30. In this embodiment, a two-beam interference exposure apparatus (wavelength λ = 266 nm) was used as an exposure apparatus, the first exposure was performed with an exposure power of 750 mJ, the substrate was rotated 90 degrees, and multiple exposure was performed with an exposure power of 750 mJ. And it developed with the brand name "NMD-W" by Tokyo Ohka Kogyo Co., Ltd., and formed the resist pattern 30 in which many conical protrusions were formed with a pitch of 250 nm.

Next, as shown in FIG. 1E, the silicon dioxide film (SiO ₂ ) film 2 is patterned by reactive ion etching (RIE) using the resist pattern 30 as a mask. In this embodiment, the trade name “NLD-800” manufactured by ULVAC, Inc. was used as the RIE etching apparatus. As the etching gas, a mixed gas of C ₄ F ₈ and CH ₂ F ₂ is used, the antenna power source is 1500 W, the bias power source is 400 W, the etching rate of the silicon dioxide film (SiO ₂ ) is 12 nm / sec, and the processing depth is A 500 nm conical groove 21 was formed.

Thereafter, as shown in FIG. 1 (f), when the resist film on which the resist pattern 30 is formed is removed by oxygen plasma ashing, the surface has a predetermined curved surface, and conical fine and dense irregularities are provided on the surface. Thus, the antireflection structure 2a made of the silicon dioxide film (SiO ₂ ) is formed.

Then, as shown in FIG. 1G, a metal layer 4 to be a mold (stamper) is formed on the antireflection structure 2a made of a silicon dioxide film (SiO ₂ ). The metal layer 4 is formed by first forming a nickel (Ni) seed layer by sputtering, forming a nickel layer thereon by electroplating, and polishing the back surface to form a mold (stamper) having a predetermined thickness. 4 is formed.

Finally, as shown in FIG. 1 (h), the metal mold (stamper) 4a is mechanically peeled off from the boundary between the silicon dioxide film (SiO ₂ ) and the metal layer 4 to obtain a pitch of 250 nm according to this embodiment. A curved mold 4a having an antireflection structure in which conical fine and dense irregularities are formed is obtained.

  In the above-described embodiment, the curved base material 1 having a predetermined curved surface shape can be easily formed by an ultra-precise micro-machining machine even if the shape is a complicated shape such as a spherical surface or an aspherical object. Then, based on the curved surface of the curved base material 1, by passing through the steps (b) to (h), the curved base material 1 has a predetermined curved surface even if it has a complicated shape such as a spherical surface or an aspherical surface for an axis. Thus, it is possible to form the curved mold 4a having an antireflection structure having a fine and dense uneven shape.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view showing the production of a curved mold having an antireflection structure according to the second embodiment of the present invention by process. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted to avoid duplication.

  As shown in FIG. 2A, similarly to the first embodiment, a curved base material 1 having a predetermined curved surface shape such as a spherical surface such as an objective lens for an optical pickup, a collimator lens, and an aspherical surface for an axis is prepared.

Subsequently, as shown in FIG. 2B, an antireflection material 11 is provided on the surface of the curved base material 1 on which a predetermined curved surface is formed. In the second embodiment, as the antireflection material 11, a chromium (Cr) film having a thickness of 100 nm and a chromium oxide (CrO) film having a thickness of 100 nm are formed by sputtering. In addition to the above, the antireflection material 11 may be made of materials such as Al ₂ O ₃ , CeO ₂ , LaF ₃ , MgF ₃ , TiO ₂ , TiN, ZnS, and ZrO ₂ .

Thereafter, as shown in FIG. 2C, a silicon dioxide film (SiO ₂ ) film 2 is formed on the antireflection material 11 formed on the curved base material 1 by a sputtering method to a thickness of about 500 nm to 1 μm. In this embodiment, a silicon dioxide film (SiO ₂ ) film 2 having a thickness of 900 nm is formed. This silicon dioxide film (SiO ₂ ) film 2 was formed under the same conditions as in the first embodiment.

Then, as shown in FIG. 2D, a resist film 3 having a thickness of 600 nm is formed on the silicon dioxide film (SiO ₂ ) film 2. The resist film 3 is also the same as that in the first embodiment.

  Subsequently, as shown in FIG. 2E, the applied resist film 3 is exposed and developed in the same manner as in the first embodiment, and a resist pattern in which many conical projections are formed at a pitch of 250 nm. 30 was formed.

Next, as shown in FIG. 2F, the silicon dioxide film (SiO ₂ ) film 2 is patterned by reactive ion etching (RIE) as in the first embodiment using the resist pattern 30 as a mask. To do. By this patterning, a conical groove 21 having a processing depth of 500 nm was formed. This patterning was also performed under the same conditions as in the first embodiment.

Thereafter, as shown in FIG. 2G, when the resist 30 is removed by oxygen plasma ashing, a silicon dioxide film (SiO ₂ ) having a predetermined curved surface and having conical fine and dense irregularities on the surface. ) Is formed.

Then, as shown in FIG. 2H, a metal layer 4 to be a mold (stamper) is formed on the antireflection structure 2a made of a silicon dioxide film (SiO ₂ ).

Finally, as shown in FIG. 2 (i), the mold (stamper) 4a is mechanically peeled off from the boundary between the silicon dioxide film (SiO ₂ ) and the metal layer 4 to obtain a pitch of 250 nm according to this embodiment. A curved mold 4a having an antireflection structure in which conical irregularities are formed is obtained.

  In the second embodiment, in addition to the effects of the first embodiment, the resist patterning can be performed more precisely by the antireflection material 11, so that the antireflection structure having a finer and more precise uneven shape can be obtained. It is possible to form the curved mold 4a having the same.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view showing the production of a curved mold having an antireflection structure according to a third embodiment of the present invention by process. In addition, the same code | symbol is attached | subjected to the same part as 1st, 2nd embodiment, and the detailed description is omitted in order to avoid duplication.

  As shown in FIG. 3A, similarly to the first embodiment, a curved base material 1 having a predetermined curved shape such as a spherical surface such as an optical pickup objective lens and a collimator lens, and an axial aspheric surface is prepared.

  Subsequently, as shown in FIG. 3B, a release material 12 having an antireflection function is provided on the surface of the curved base material 1 on which a predetermined curved surface is formed. In the third embodiment, the mold release material 12 is applied with a resist having an antireflection function corresponding to ultraviolet rays and hard-baked. In this embodiment, the product name “SWK-248DTr” manufactured by Tokyo Ohka Kogyo Co., Ltd. was used as the resist and hard-baked at 180 ° C.

Thereafter, as shown in FIG. 3C, a silicon dioxide film (SiO ₂ ) film 2 is formed on the mold release material 12 formed on the curved base material 1 by a sputtering method to a thickness of about 500 nm to 1 μm. In this embodiment, a silicon dioxide film (SiO ₂ ) film 2 having a thickness of 900 nm is formed. This silicon dioxide film (SiO ₂ ) film 2 was formed under the same conditions as in the first embodiment.

Then, as shown in FIG. 3D, a resist film 3 having a thickness of 600 nm is formed on the silicon dioxide film (SiO ₂ ) film 2. The resist film 3 is also the same as that in the first embodiment.

  Subsequently, as shown in FIG. 3E, a resist pattern in which a plurality of conical protrusions are formed at a pitch of 250 nm by exposing and developing the applied resist film 3 in the same manner as in the first embodiment. 30 was formed.

Next, as shown in FIG. 3F, using the resist pattern 30 as a mask, the silicon dioxide film (SiO ₂ ) film 2 is patterned by reactive ion etching (RIE) as in the first embodiment. To do. By this patterning, a conical groove 21 having a processing depth of 500 nm was formed. This patterning was also performed under the same conditions as in the first embodiment.

Thereafter, as shown in FIG. 3G, when the resist 30 is removed by oxygen plasma ashing, a silicon dioxide film (SiO ₂ ) having a predetermined curved surface and having conical fine and dense irregularities on the surface. ) Is formed.

Then, as shown in FIG. 3H, a metal layer 4 to be a mold (stamper) is formed on the antireflection structure 2a made of a silicon dioxide film (SiO ₂ ).

Thereafter, as shown in FIG. 3 (i), integrally to separate the mold (stamper) 4a and a releasing member 12 and the silicon dioxide film mechanically silicon dioxide film from the boundary between the _{(SiO 2) (SiO 2)} .

Subsequently, as shown in FIG. 3J, the release material resist adhered to the mold (stamper) side is removed by oxygen plasma, and a silicon dioxide film (SiO ₂ ) is formed by reactive ion etching (RIE). ) Remove only 2a. At this time, CHF ₃ was used as an etching gas. In this way, the curved surface mold 4a having the antireflection structure in which conical irregularities are formed at a pitch of 250 nm according to this embodiment is obtained.

  In the third embodiment, the mold (stamper) side and the base material 1 side can be easily separated.

  By the way, when an optical element is formed by resin filling using a mold having an antireflection function composed of the above-described fine irregularities, the resin is filled into a high aspect fine pattern. For this reason, the load when peeling resin and a metal mold | die becomes large. In particular, since the adhesive force increases sharply at the boundary between the patternless region and the pattern region, the stamper and the molded product may be damaged. Therefore, this fourth embodiment reduces the load during peeling. Therefore, from the outer periphery to the inner periphery of the optical element, the depth of the unevenness of the antireflection function of the optical element is gradually increased, and the load at the time of peeling is gradually increased, and the resin is filled. Sometimes it is easy to peel off from the outer peripheral side. Hereinafter, the fourth embodiment will be described with reference to FIGS.

  FIG. 4 is a cross-sectional view showing the production of a curved mold having an antireflection structure according to a fourth embodiment of the present invention by process, and FIG. 5 gradually shows the optical element from the outer periphery toward the inner periphery. It is a top view which shows the exposure process for deepening the depth of the unevenness | corrugation of this antireflection function. In addition, the same code | symbol is attached | subjected to the same part as 1st, 2nd, 3rd embodiment, and in order to avoid duplication, the detailed description is omitted.

  As shown in FIG. 4A, a curved base material 1 having a predetermined curved surface shape such as a spherical surface such as an optical pickup objective lens and a collimator lens, and an axial target aspherical surface is prepared.

Subsequently, as shown in FIG. 4B, a silicon dioxide film (SiO ₂ ) film 2 having a thickness of 900 nm is formed on the surface of the curved base material 1 on which a predetermined curved surface is formed by RF magnetron sputtering. . This silicon dioxide film (SiO ₂ ) film 2 was formed under the same conditions as in the first embodiment.

Then, as shown in FIG. 4C, a resist is applied on the silicon dioxide film (SiO ₂ ) film 2. For example, a resist coating 3a having a film thickness of 600 nm is formed by spin coating at a rotation speed of 3000 rpm using a negative resist for electron beam having a trade name “NEB22” manufactured by Sumitomo Chemical Co., Ltd. as a resist. Formed.

Subsequently, as shown in FIGS. 4D and 5, the applied resist film 3a is irradiated using an EB drawing apparatus. Irradiation increased the irradiation energy toward the outer periphery. For example, as shown in FIG. 5, to draw irradiated with 100μm square, the effective area 30a is irradiated at an energy of 10 [mu] C / cm ^2, an outer region corresponding 30b1 thereof is irradiated with energy of 12μC / cm ² The outer region 30b2 was irradiated with an energy of 14 μC / cm ² , and the outermost region 30b3 was irradiated with an energy of 16 μC / cm ² . Then, after EB drawing, after a 2-minute exposure bake (PEB) on a hot plate at 110 ° C., development was performed for 2 minutes with a developer model “MF CD-26” manufactured by Shibley Far East Co., Ltd. As a result, a large number of conical protrusions were formed at a pitch of 250 nm in the effective area 30a, and the resist pattern 31 of the area 30b where the protrusions became thicker toward the outside was formed. The resist pattern 31 becomes a mask in which the volume ratio of the concavo-convex pattern changes from the effective region to the outside.

Next, as shown in FIG. 4E, the silicon dioxide film (SiO ₂ ) film 2 is patterned by reactive ion etching (RIE) using the resist pattern 31 as a mask. In this embodiment, the product name “NLD-800” manufactured by ULVAC, Inc. is used as the RIE etching apparatus, the mixed gas of C ₄ F ₈ and CH ₂ F ₂ is used as the etching gas, and the antenna power supply is used. Etching was performed so that a groove 21 having a processing depth of 500 nm was formed in the effective region at 1500 W, a bias power source of 400 W, and an etching rate of the silicon dioxide film (SiO ₂ ) of 12 nm / sec. As a result, in the region located outside the effective region 30a, a pattern was formed in which the depth of the antireflection function groove gradually increased from the outer periphery toward the inner periphery.

Thereafter, as shown in FIG. 4 (f), when the resist 30 is removed by oxygen plasma ashing, a region having a predetermined curved surface and located outside the effective region 30a gradually increases from the outer periphery toward the inner periphery. Accordingly, the depth of the antireflection function is deepened, and the antireflection structure 2b made of a predetermined fine and dense silicon dioxide film (SiO ₂ ) is formed in the effective region 30a.

Then, as shown in FIG. 4G, a metal layer 4 to be a mold (stamper) is formed on the antireflection structure 2b made of a silicon dioxide film (SiO ₂ ). The metal layer 4 is formed by first forming a nickel (Ni) seed layer by sputtering, forming a nickel layer thereon by electroplating, and polishing the back surface to form a mold (stamper) having a predetermined thickness. 4 is formed.

Finally, as shown in FIG. 4 (f), the effective area 30a according to this embodiment is removed by mechanically peeling the mold (stamper) 4a from the boundary between the silicon dioxide film (SiO ₂ ) and the metal layer 4. The region located outside the region has an antireflection structure in which the groove of the antireflection function gradually increases in depth from the outer periphery toward the inner periphery, and the effective region 30a has an antireflection structure in which conical irregularities are formed at a pitch of 250 nm. A curved mold 4b is obtained.

  As described above, in the region located outside the effective region 30a, the depth of the antireflection function gradually increases from the outer periphery toward the inner periphery, and conical irregularities are formed at a predetermined pitch in the effective region 30a. By using the curved metal mold 4b having the antireflection structure, it is easy to peel off from the outer peripheral side when the resin is filled, and there is no possibility that the stamper or the molded product is damaged.

  A molded product is created using a mold in which all of the antireflection structures having the same depth shown in FIG. 1 are formed. Moreover, a molded product is created using the mold shown in FIG. The adhesion force when the mold of FIG. 1 is used and when the mold of FIG. 4 is used will be compared. As a result, as shown in FIG. 6, according to the present invention, the adhesion force in the region 11b from the outer peripheral portion toward the outer periphery is reduced. As a result, according to the fourth embodiment of the present invention, when the resin is filled, it is easy to peel off from the outer peripheral side, and there is no possibility that the stamper or the molded product is damaged.

  Even if the structure of the fourth embodiment is applied to the second and third embodiments, the same effect can be obtained.

In the above-described embodiment, a silicon dioxide film (SiO ₂ ) film is used as the silicon-based film, but a silicon (Si) film, a silicon (SiN) nitride film, or the like can also be used. Further, an SOG film formed by spin coating using organosilane or the like can be used as a silicon-based film.

  Next, a case where an optical element is manufactured using the above-described mold according to the present invention will be described with reference to FIG. FIG. 7 is a side sectional view showing the shape and structure of a mold used in the method of manufacturing an optical element according to the present invention. This mold includes a fixed mold 60 and a movable mold 70. A movable mold 70 is abutted against the fixed mold 60 to form a cavity 80 between the two molds 60, 70, and a gate 81 connected to the cavity 80 is formed around a part of the cavity 80. Molten plastic resin is supplied to the cavity 80 through the gate 81, and the inside is filled with the resin.

  The fixed mold 60 includes a first member 61 at the center and a second member 62 on the peripheral side. Both the members 61 and 62 are made of steel and are integrally fixed to each other. The first member 61 is formed with a smooth concave molding surface 61a facing the movable mold 70, and the second member 61 is formed with a molding surface 61b of an annular groove disposed around the molding surface 61a. Yes. The molding surface 61a of the first member 61 corresponds to one lens surface of a lens (not shown) that is a molded product, and the molding surface 62a of the second member 62 corresponds to a flange provided around the lens.

  The movable mold 70 includes a protruding portion 71 that is a mold member on the center side, and a main body portion 72 that supports the protruding portion 71 from the periphery. A die (stamper) 4a manufactured by the method according to any one of the first to fourth embodiments of the present invention described above is attached to the tip of the protruding portion 71. The mold 4a is formed in a concave surface corresponding to the other lens surface of the lens, and an antireflection structure 40a formed of a fine and dense uneven surface is formed on the concave surface. A peripheral molding surface 72a formed by the main body 72 corresponds to a peripheral flange.

  The protruding portion 71 is attached so as to be slidable in the axial (X) direction in a state of being fitted into a hole 72 b provided in the main body portion 72. After the mold opening for separating the two molds 60 and 70, the protrusion 71 is moved toward the fixed mold 60 with respect to the main body 72, thereby releasing the lens remaining on the movable mold 70 side.

  Next, molding of a lens using the mold shown in FIG. 7 will be briefly described. First, the mold is closed by joining the movable mold 70 to the fixed mold 60. At this time, the fixed mold 60 and the movable mold 70 are fixed in a state of being aligned with each other using an alignment mechanism such as a fitting pin (not shown). By such mold closing, a cavity 80 having a shape in which the molding surfaces 61 a and 61 b of the fixed mold 60 and the molding surfaces 40 a and 72 a of the movable mold 70 are closed is formed between both the molds 60 and 70.

  Next, molten plastic resin is injected into the cavity 80 formed between the two molds 60 and 70. The molten plastic resin is introduced into the cavity 80 between the two molds 60 and 70 through the gate 81, and the cavity 80 is filled with the molten plastic resin.

  Subsequently, the molten plastic resin filled in the cavity 80 is radiated and cooled. The temperature of the molten plastic resin injected into the cavity 80 is normally 200 to 300 ° C., and is in contact with the molding surfaces 40 a, 72 a, 61 a and 61 b of both molds 60 and 70 which are normally held at 100 to 180 ° C. The molten plastic resin is cooled and cured. At this time, the molten plastic resin almost completely enters the fine uneven pattern formed on the molding surface 40 a of the protruding portion 71.

  Next, it waits until the molten plastic resin filled in the cavity 80 is completely cured. Thereby, a lens corresponding to the shape of the cavity 80 is obtained. One surface of the lens is a smooth convex surface corresponding to the molding surface 61a, and the other surface of the lens is a convex surface having an antireflection structure corresponding to the molding surface 40a. A flange is formed around the lens corresponding to the molding surfaces 61b and 72a.

  Thereafter, mold opening for separating the movable mold 70 from the fixed mold 60 is performed. As a result, the molded product remains on the movable mold 70 side and is released from the fixed mold 60.

  And the protrusion part 71 is driven to the stationary mold | type 60 side from the state accommodated in the main-body part 72 using the drive device which is not shown in figure. Thus, the lens can be completely released from the movable mold 71, that is, separated.

  The lens thus obtained can be applied to an optical pickup device. In the embodiment described above, a mold having a fine concavo-convex pattern is attached to the movable mold 70, but it is attached to the fixed mold 60 side, attached to both the movable mold 70 and the fixed mold 60, or manufactured. The mold according to the present invention may be used as the movable mold 70 and the fixed mold 60 as appropriate according to the design of the optical element to be performed.

  In the above-described embodiment, an antireflection structure is given as an example of a fine and dense concavo-convex shape. However, if the concavo-convex shape is fine and dense, an optical element pattern structure having other functions is manufactured. In this case, the present invention can be applied. For example, the present invention can be applied to manufacturing a fine pattern constituting a retardation plate, a fine pattern constituting a diffraction grating, and the like.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention can be applied to a method of manufacturing a diffraction grating for an optical pickup, a retardation plate for an optical pickup, an optical pickup lens, a display cover for a mobile phone, and the like, and can be used when an antireflection structure is provided on the surface of these members. .

Claims (3)

A silicon-based film is formed on a curved base material formed in a predetermined shape, and a pattern of a fine concavo-convex structure of a predetermined shape is formed by etching the silicon-based film using a mask. A metal mold is deposited on a silicon-based film on which a pattern is formed, a pattern with a fine concavo-convex structure is transferred to the metal for the mold, the silicon-based film is removed, and a mold having a fine concavo-convex structure on a curved surface In the method of manufacturing a curved mold having a fine relief structure,
The method of manufacturing a curved mold having a fine concavo-convex structure, wherein the mask is made of a photoresist, and an antireflection film is formed between the curved base material and a silicon-based film .   2. The method for producing a curved mold having a fine concavo-convex structure according to claim 1, wherein a release material film is formed between the curved base material and the silicon-based film.   A silicon-based film is formed on a curved base material formed in a predetermined shape, and the effective area portion has a pattern of fine irregularities of a predetermined shape on the silicon-based film, and the volume of the irregular pattern increases toward the outside. A mask having a changed ratio is provided, and using this mask, the depth of fine unevenness gradually increases from the outer periphery to the inner periphery, and the unevenness of a predetermined depth and shape is increased in the effective region. The formed fine pattern is formed by etching, a metal for a mold is deposited on the substrate on which the concave / convex pattern is formed, and after the concave / convex pattern is transferred to the metal for the mold, the substrate and the metal A method for producing a mold having a fine concavo-convex structure, wherein a mold is formed by separating a mold metal.

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