JPH11311711A - Manufacture of optical element and manufactured optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it easy to align fine patterns with each other when they are molded at the same time. SOLUTION: This manufacturing method is characterized by that a dummy base material 1' is fixed to a 1st stamper 18 across an ultraviolet-ray setting type resin layer 52 independently of a die set, a 2nd stamper 17 is mounted on the dummy base material 1' across ultraviolet-ray setting type resin 53a, and the original plate pattern 17a of the 2nd stamper 17 is aligned with the original plate pattern 18a of the 1st stamper 18 by observing through a microscope. The alignment body A which is thus manufactured is mounted on the die set and the fine patterns 4b and 5b are molded by transferring the original plate patterns 18a and 17a to the ultraviolet-ray setting type resin layers 4 and 5 on both the top and reverse surfaces of the transparent base material 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical element in which optical patterns are collectively formed on both the front and back surfaces of a transparent base material, and more particularly, to ultraviolet light adhered to both front and back surfaces of a transparent base material. The present invention relates to a method for manufacturing a hologram element having fine patterns constituting a hologram and a diffraction grating by transferring a master pattern formed on a stamper to an ultraviolet-curable resin by sandwiching a curable resin between a pair of stampers. Further, the present invention relates to an optical element / hologram element manufactured by such a manufacturing method. The optical element targeted by the present invention may be any optical element having any optical pattern on both front and back surfaces, and in particular, a CD (audio CD, video CD), CD-RO
M, CD-R, LD, MD, DVD, DVD-ROM,
A hologram element used in an optical pickup that optically reads optical information recorded on an optical disk / magneto-optical disk such as a DVD-RAM and generates a focus error signal and a tracking error signal is suitable as an object of the present invention. .

[0002]

2. Description of the Related Art A hologram element used as a component of an optical pickup for an optical disk is usually of a size of several mm square, and is formed on a large transparent base material for the purpose of mass production at low cost. It is manufactured by dividing after forming a plurality of optical patterns at once. On the hologram element, an extremely fine pattern constituting a hologram or a diffraction grating (grating) is precisely formed. Conventionally, as a method of forming a fine pattern,
A method of applying the method of manufacturing a semiconductor device shown in FIG. 7 or a molding method using a generally ultraviolet-curable resin generally called a "2P method" or a "photopolymer method" (Photo Polymer) shown in FIGS. Manufacturing methods and other methods are known.

A method of manufacturing a hologram element to which a conventional method of manufacturing a semiconductor device is applied will be described with reference to FIG. Glass substrate 71 as a transparent substrate shown in FIG.
Is washed, and FIG.
7B, the photosensitive material 72 is applied by a spin coating method or the like, and then, as shown in FIG. 7C, a required pattern is formed on the photosensitive material 72 by exposure using a photolithography technique. As shown in FIG. 7D, a fine pattern 71a is formed on a glass substrate 71 via a pattern of a photosensitive material 72 by a reactive ion etching method in a gas atmosphere such as CF ₄ or CHF ₄ . At this time, the photosensitive material 72 is also etched at the same time, but the relationship between the processing rate of the glass base material 71 and the processing rate of the photosensitive material 72 is grasped in advance, and the fine pattern having a required depth is formed on the glass base material 71. Even after the formation of the glass substrate 71a, the photosensitive material 72 performs its mask function even after the formation of the glass substrate 7a.
The application thickness of the photosensitive material 72 is determined so as to remain on the surface 1. Next, as shown in FIG. 7E, the photosensitive material 72 is removed from the glass substrate 71 by dissolving with a solvent or by incineration in an oxygen gas atmosphere. A plurality of hologram elements are formed on the glass substrate 71 as described above. However, as shown in FIG. 7 (f), the hologram elements are cut into a finally required shape and size and divided into a plurality. required hologram element H ₁ is obtained by. The obtained hologram element is fixed to the cap of the laser unit (hollow fixing step). Summarizing the above along the flow of each process, the washing process of the transparent base material → the coating process of the photosensitive material → the exposing process → the etching process of fine pattern formation → the removing process of the photosensitive material → the anti-reflection film as needed This is a film forming step → separating step → hollow fixing step.

In this manufacturing method, a long time is required for the reactive ion etching step, and the manufacturing efficiency is not improved. Therefore, as one of the more efficient and inexpensive manufacturing methods, a 2P method (photograph) shown in FIG. The production method using the polymer method is effective.

FIG. 8 shows a method of forming a fine pattern on one side of a method of manufacturing a hologram element by the 2P method. As shown in FIG. 8A, a stamper 81 on which a master pattern 81a is formed in advance is used, and a liquid ultraviolet curable resin 82a is applied thereon.
As shown in FIG. 8 (b), a transparent base material 83 is further disposed thereon, and if necessary, pressurizing the ultraviolet curable resin 8 while applying pressure.
2a is sufficiently pressed and spread in the gap between the stamper 81 and the transparent substrate 83. The ultraviolet curable resin 82a is a stamper 81
Is pressed into every corner of the concave portion of the master pattern 81a. Next, after the ultraviolet curable resin 82a is cured by irradiating ultraviolet light, the cured transparent resin layer 82 is integrated with the transparent base material 83 by bonding as shown in FIG. Peel off. As the ultraviolet curable resin 82a, the stamper 8
A material having a higher adhesiveness to the transparent substrate 83 than to 1 is selected, or the adhesiveness of the transparent substrate 83 is higher than the adhesiveness of the stamper 81 by the pretreatment. By doing so, the transparent resin layer 8
2 can be peeled off from the stamper 81 in a state of being integrated with the transparent substrate 83. Thus, a hologram element intermediate product H ₁ ′ in which the transparent resin layer 82 having the fine pattern 82 b to which the master pattern 81 a of the stamper 81 has been transferred is integrated with the transparent base material 83 is obtained. Thereafter, the hologram element intermediate product H ₁ ′ is divided into a plurality of pieces to obtain a hologram element.

In the case where the functions of signal light branching, focus control, and tracking control are integrated in one hologram element, a tracking beam is generated on the front surface side, and a light branch and a focus servo error signal are generated. In addition to forming a total of four fine patterns constituting a "hologram" for performing the above, one "diffraction grating" (grating) for generating a sub-beam for one of three spots of the tracking method is formed on the back surface side. Form a fine pattern. In this case, it is necessary to align the fine pattern of the hologram on the front surface and the fine pattern of the diffraction grating on the back surface with an accuracy of 10 μm or less.

In the case of the method of manufacturing a hologram element to which the method of manufacturing a semiconductor device shown in FIG. 7 described above is applied, when manufacturing a hologram element having a fine pattern on both the front and back surfaces, the fine pattern is formed on both the front and back surfaces at once. Since it is difficult to form a pattern, a method of first forming a fine pattern on one side and then forming a fine pattern on the other side through the same process is employed. In other words, when summarized along the flow of each process, the cleaning process of the transparent substrate →
Coating process of photosensitive material → exposure process → etching process of one fine pattern formation → removal process of photosensitive material → washing process of transparent substrate again → photosensitive material coating process → exposure process → other fine pattern formation Etching process → photosensitive material removing process → antireflection film forming process if necessary → separation process → hollow fixing process. In this case, in the exposure step for forming the other fine pattern, the exposure is performed by aligning the mask with one of the already formed fine patterns using a microscope. Although the alignment itself is not difficult, since fine patterns on the front and back cannot be formed at once, and the steps are performed in two steps, each of the steps of cleaning, coating, exposure, etching, and removal must be performed twice each. This has led to very poor manufacturing efficiency.

FIG. 9 shows a method of forming a fine pattern on both sides of the method of manufacturing a hologram element by the 2P method. As shown in FIG. 9A, a first stamper 91 on which one master pattern 91a is formed in advance.
A liquid UV-curable resin 92a is applied on the transparent substrate 93, and a UV-curable resin 94a is also applied on the transparent base material 93.
UV-transmitting second stamper 9 on which 5a is formed
5 and the first stamper 9 as shown in FIG.
1 and a transparent substrate 93
A second stamper 95 is superposed on the second member, and pressurized as necessary, so that the ultraviolet curable resins 92a and 94a are separated from each other by a gap between the stamper 91 and the transparent base 93 and a gap between the transparent base 93 and the stamper 95. And spread enough. Next, ultraviolet rays are irradiated through an ultraviolet-transmitting second stamper 95, thereby forming two layers of ultraviolet-curable resins 92a and 94a.
After curing, the transparent substrate 9 as shown in FIG.
The cured transparent resin layers 92 and 94 on both the front and back surfaces of No. 3 are integrated from the stampers 91 and 95 by bonding. As described above, the transparent resin layer 94 having one fine pattern 94b constituting the hologram on which the master pattern 95a of the second stamper 95 is transferred is integrated on the surface side of the transparent base material 93, and the transparent base material 93 is formed. A transparent resin layer 92 having the other fine pattern 92b constituting the diffraction grating to which the master pattern 91a of the first stamper 91 is transferred is obtained on the back side of the first stamper 91. More specifically, an anti-reflection film (not shown) is formed on the fine patterns on both sides by vapor deposition or the like to produce a hologram element intermediate product H ₂ ′, which is cut into a desired shape and size by dicing or the like. It is divided into a plurality to form a hologram element. Then, the hologram laser unit is manufactured by bonding the hologram element to the cap of the laser unit. In the case of the method for manufacturing the hologram element shown in FIG. 9, fine patterns on the front and back sides can be formed collectively, so that the manufacturing efficiency is high.

In the above-mentioned conventional method for manufacturing a hologram element in which fine patterns are formed in an aligned state on both the front and back surfaces using the 2P method (photopolymer method), the alignment is performed as follows. The stamper 91, the transparent substrate 93, and the ultraviolet-transmissive stamper 95 are mounted on a die set. Die set is stamper 91
A lower mold for fixing the stamper 95, an upper mold for fixing the UV-transmitting stamper 95, a guide post fixed to the upper mold and hanging down and sliding through the lower mold, an upper mold and a lower mold. And the like. FIG. 5 used in the description of [Embodiment of the invention] described later.
It is easy to understand if you refer to. In FIG.
(→ 95), 18 (→ 91) are stampers, 31 is a die set, 41 is an upper mold, 42 is a lower mold, 45 is a guide post, and 46 is a hydraulic cylinder. While the fixed state of the stamper 95 in the upper mold is locked, the stamper 91 placed on the lower mold is kept free. By closing the mold, the upper and lower stampers 95 and 91 are brought close to each other. The stamper 91 on the lower mold is aligned while visually observing the upper mold with a tool microscope. That is, a plurality of screws for fixing the lower stamper 91 are finely adjusted while observing the relative positional relationship between the master pattern 95a of the ultraviolet transmitting stamper 95 and the master pattern 91a of the lower stamper 91 with a microscope. Then, the lower stamper 91 is aligned so that the upper and lower master patterns exactly coincide with each other. When the alignment is completed, the screws are finally tightened and fixed.

By using the stampers 95, 91 in which both master patterns are aligned as described above, the master patterns 95a, 91a are transferred from the master patterns 95a, 91a to the ultraviolet-curable resins 94a, 92a on both the front and back surfaces of the transparent base material 93 to form fine patterns. Is formed, a fine pattern 94b for hologram and a fine pattern 92b for diffraction grating aligned as expected are formed on the transparent resin layers 94 and 92 on both front and back surfaces.

[0011]

However, the master patterns 91a, 9a of the two stampers 91, 95 as described above.
The work of alignment between 5a is a work in a state of being set in the die set, the die set is heavy, and fine adjustment of the screw must be performed in a very narrow space. In addition, fine adjustment of the screw is often performed repeatedly, and the like, so that the workability is extremely poor, and the alignment work requires a great amount of time and has a high risk.

Japanese Patent Application Laid-Open No. 2-232604 discloses a method of producing a dual-type grating in a place unrelated to a die set in the following process. That is, on the other hand, a surface grating is created on the substrate surface by an ultraviolet curing method. The back-surface grating stamper is fixedly arranged so that the laser beam emitted from the laser light source enters at right angles to the direction of the back-surface grating formed on the back-surface grating stamper. An ultraviolet curable resin is applied to the surface of the backside grating stamper. The back surface of the substrate on which the surface grating is formed is brought into close contact with the surface of the ultraviolet curable resin, and the substrate is moved and adjusted so that the laser beam is incident at right angles to the direction of the surface grating, thereby performing alignment. After this adjustment, the substrate is exposed to ultraviolet light to cure the ultraviolet-curable resin, and thereafter, the grating stamper for the back surface is peeled off, thereby producing a dual-type grating in which the grating for the front surface and the grating for the back surface are formed on both the front and back surfaces of the substrate. A laser light source is configured to be tiltable in a vertical plane on a holder provided on a stage that rotates in a horizontal plane. A trajectory plane that reflects a laser beam reflected from the back surface grating or the front surface grating as a straight line is arranged.

However, the technique described in this publication has a problem that alignment takes a lot of time and lacks mass productivity.

The present invention has been made in order to solve the above-mentioned problems, and is intended to simplify the alignment work and to be excellent in mass productivity as compared with the case where alignment is performed for each heavy die set. It is intended to be.

[0015]

According to the first aspect of the present invention, there is provided a method of manufacturing an optical element as described below. That is, a method for manufacturing an optical element, comprising a step of transferring a master pattern of a stamper as an optical pattern to both front and back surfaces of a transparent base material by sandwiching the transparent base material between a pair of first and second stampers, The master pattern of the first stamper and the master pattern of the second stamper are aligned, and in this state, the first stamper and the second stamper are temporarily fixed to the front and back surfaces of the dummy base material. It is preferable to use the same substrate as the transparent substrate as the dummy substrate. Then, the temporarily fixed alignment body is attached to the die set, and the first stamper is fixed to the lower die of the die set and the second stamper is fixed to the upper die while the alignment body remains as it is. After fixing, remove the dummy substrate from the alignment body. Thereby, the master pattern of the first stamper fixed to the lower mold and the master pattern of the second stamper fixed to the upper mold are aligned with high precision. Accordingly, in such an optical element in which the master patterns of both stampers are transferred to the front and back surfaces of the transparent substrate to form an optical pattern, the alignment of the optical patterns on both surfaces is performed with high precision. When aligning the master patterns of both stampers, alignment is performed using a dummy base material independently of the die set, which is advantageous in terms of both weight and working space compared to the case where alignment is performed for each heavy die set. Therefore, it is much simpler and less dangerous, the time required for alignment can be shortened, and mass production is excellent.

According to a second aspect of the present invention, there is provided a method for manufacturing an optical element according to the first aspect, wherein an ultraviolet ray transmitting type stamper is used as at least one of the stampers, and the ultraviolet curing resin is attached to both front and back surfaces of the transparent substrate. In this state, the transparent base material is sandwiched between both stampers, and the UV-curable resin is cured while the master patterns of both stampers are transferred to the UV-curable resin by irradiating ultraviolet rays through the UV-transmissive stamper. This is a method for manufacturing an optical element in which both stampers are separated from the ultraviolet-curable resin layer, and the alignment body is also manufactured using an ultraviolet-curable resin. That is, alignment of both stampers is performed as follows. Independently of the die set, an ultraviolet-curable resin is applied on the first stamper, a dummy base material is placed thereon, and the ultraviolet-curable resin is cured by irradiating ultraviolet rays to cure the first stamper. Is fixed to the dummy base material. Next, an ultraviolet curing resin is applied on the dummy base material, and a second ultraviolet transmission type stamper is mounted thereon. Then, the second stamper is moved in an uncured state of the ultraviolet-curable resin on the dummy base material, and alignment of the master pattern of the second stamper with respect to the master pattern of the first stamper is performed. Irradiate ultraviolet rays with the alignment completed and apply a second
Fix the stamper. As described above, the first stamper and the second stamper are temporarily fixed to the dummy base material in a state where each of the first stamper and the second stamper is interposed with the ultraviolet-curable resin and each master disk pattern is aligned. The rest is the same as in claim 1.

According to a third aspect of the present invention, there is provided a method of manufacturing an optical element according to the second aspect, wherein the ultraviolet curable resin is cured while the transparent base is protruded from both stampers, and the protruding portion of the transparent base is provided. The two stampers are peeled off from the ultraviolet-curable resin layer cured in a state where a force is applied. Since both stampers are peeled off by applying a force to the protruding portion of the transparent base material, the peeling from the ultraviolet curable resin layer can be performed efficiently and accurately.

According to a fourth aspect of the present invention, there is provided a method for manufacturing an optical element according to any one of the first to third aspects, wherein the plurality of die sets are prepared by fixing both stampers of the alignment body and removing the dummy base material. It is prepared so that when a failure occurs in one die set during manufacture using one die set, the die set is replaced with another die set. It can be performed continuously without interrupting production, and productivity is improved.

According to a fifth aspect of the present invention, there is provided a method of manufacturing an optical element, the method of manufacturing a hologram element according to any one of the second to fourth aspects. A fine pattern forming a hologram is formed on the layer, and a fine pattern forming a diffraction grating is formed on the other ultraviolet curable resin layer. The hologram element produces the above-described functions.

According to a sixth aspect of the present invention, there is provided a method of manufacturing an optical element according to any one of the second to fifth aspects, wherein the transparent substrate is made of a synthetic resin, A primer layer is interposed between the UV-curable resin layer and the UV-curable resin layer. The adhesiveness between the synthetic resin transparent substrate and the ultraviolet-curable resin layer is generally not good, and the adhesiveness is improved by interposing a primer layer.

The optical element according to claim 7 according to the present invention comprises:
It is manufactured by the above-described manufacturing method, wherein a primer layer is formed on both front and back surfaces of a transparent substrate made of a synthetic resin, and an ultraviolet curable resin layer having an optical pattern formed on each primer layer is formed. Is what it is. The alignment accuracy of the optical patterns on both the front and back surfaces is high, and the adhesion between the transparent substrate made of synthetic resin and the ultraviolet curable resin layer is good.

The optical element according to claim 8 according to the present invention comprises:
In claim 7, an antireflection film is formed on each of the ultraviolet-curable resin layers. In addition to preventing reflection of incident light, weather resistance is also improved.

According to a ninth aspect of the present invention, there is provided an optical element for a hologram element, wherein the optical pattern of one of the ultraviolet-curable resin layers is a fine pattern constituting a hologram. The optical pattern of the other UV-curable resin layer is a fine pattern constituting a diffraction grating. This is advantageous for detecting each signal when used in a hologram laser unit.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method for manufacturing an optical element (hologram element) according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a hologram element H according to the embodiment and a hologram laser unit HL produced by attaching the hologram element to a laser unit U.
It is sectional drawing which shows the schematic structure of. Primer layers 2 and 3 are formed on the front and back surfaces of a transparent base material 1 made of a synthetic resin having ultraviolet transparency, and ultraviolet curable resin layers 4 and 5 each having a fine pattern formed on each of the primer layers 2 and 3. Is formed. The UV-curable resin layer has good adhesion to glass, but is not very good to synthetic resin. Therefore, the primer layers 2 and 3 are interposed between the transparent substrate 1 made of synthetic resin and the ultraviolet-curable resin layers 4 and 5, and the adhesion is secured by the primer layers 2 and 3. The fine pattern formed on the surface (upper surface) of the upper ultraviolet curable resin layer 4 is for hologram, and the fine pattern formed on the surface (lower surface) of the lower ultraviolet curable resin layer 5 is a diffraction grating. (Grating). These fine patterns are formed by the 2P method (photopolymer method) (described later). Each fine pattern is not shown because it is fine. The fine pattern of the upper ultraviolet curable resin layer 4 and the fine pattern of the lower ultraviolet curable resin layer 5 are aligned (aligned) in a predetermined positional relationship. Anti-reflection films 6 and 7 having excellent weather resistance are formed on the ultraviolet-curable resin layers 4 and 5, respectively. The hologram element H has the above configuration.

The structure of the laser unit U is as follows. A laser chip 11 and a light receiving element 12 for reading signal light are fixed to a heat sink 10 a integral with the stem 10, the whole is covered with a cap 13, and a glass window 14 is fixed to an opening of the cap 13. The hologram element H is fixed to the upper surface of the cap 13 via the adhesive 15 with the lower antireflection film 7 via the adhesive 15 in a state where the hologram laser unit HL is centered with the glass window 14. I have.

Explaining the material of each part, as the transparent substrate 1 made of synthetic resin, for example, acrylic resin is preferable from the viewpoint of transparency, strength, and flatness. Among them, an acrylic extruded molding material (manufactured by Sumitomo Chemical Co., Ltd.) Spepex, grade name E011) are preferred. By making the transparent substrate 1 made of a synthetic resin, the cost can be reduced as compared with that made of glass. However, since it is made of a synthetic resin, there is a problem of adhesion to the ultraviolet curable resin layers 4 and 5, so that it is necessary to interpose the primer layers 2 and 3. However, this can be inexpensive. The hologram element H using the primer layers 2 and 3 has not been known so far. N-vinyl-2-pyrrolidone is preferable as the primer layers 2 and 3 from the viewpoint of workability. As the UV-curable resin layers 4 and 5, MP-107 manufactured by Mitsubishi Rayon Co., Ltd. is preferable from the viewpoint of the leaking property with the base material and the hardness at the time of curing. The antireflection films 6 and 7 preferably have a two-layer structure of a ZrO ₂ + TiO ₂ mixed layer and SiO ₂ from the viewpoint of adhesion to a base material and deposition at a low temperature. As the adhesive 15, an ultraviolet curable adhesive is preferable from the viewpoint of reliability of the adhesive strength. In addition to the above, the synthetic resin constituting the transparent substrate 1 may be polyolefin, PET, or PP. It should be noted that polycarbonate resin is not applicable because it has poor ultraviolet transmittance. As the primer layers 2 and 3, an ultraviolet curable resin containing N-vinylpyrrolidone, acrylic acid,
A strong alkaline solution may be used, the UV-curable resin layers 4 and 5 may be MP121 manufactured by Mitsubishi Rayon Co., Ltd., and the antireflection films 6 and 7 may include a first layer containing ZrO ₂ and a second layer of SiO ₂ . May be used. The adhesive 15 needs to be cured in a short time (several seconds) and the position of the adhesive 15 must be adjustable.

Next, the steps of the method of manufacturing the hologram laser unit HL having the above-described configuration will be described with reference to FIG.

In the first cleaning step S1, the transparent substrate 1 is cleaned. 130 sheets of 130 mm × 130 mm × 3 mm transparent base material 1 were mounted on a cassette, and the cassette was immersed in pure water and subjected to ultrasonic cleaning for 2 minutes.
Then, the substrate was immersed in isopropyl alcohol (IPA) and subjected to ultrasonic cleaning for 2 minutes, followed by air drying.

In a second step, a pretreatment step, ie, a primer treatment step S2, the ten transparent substrates 1 mounted on the cassette are immersed together with the cassette in a solution of N-vinyl-2-pyrrolidone, taken out and spin-dried. Excess liquid was removed by a method and dried in a clean bake oven at 85 ° C. for 10 minutes to form the primer layers 2 and 3 on both the front and back surfaces of the transparent substrate 1. For spin drying, a rinser dryer MODEL160 manufactured by Vertec Co., Ltd.
A 0-3 spin dryer was used. In this spin dryer, a shielding material made of Teflon (polytetrafluoroethylene; a trademark of DuPont) having corrosion resistance to a liquid of N-vinyl-2-pyrrolidone is used.
Explosion-proof measures were also taken in consideration of the flammability characteristics of this liquid.

In a third step, a 2P molding step (photopolymer molding step) S3, as will be described in detail later, the first stamper 18 and the second stamper 17 are aligned with each other. Using a transparent substrate 1
UV curable resin layers 4 and 5, each having a fine pattern on the surface, were formed on the primer layers 2 and 3 on both the front and back surfaces. First, the outline of the 2P molding step S3 will be described with reference to FIG. Details will be described later. As shown in FIG. 3A, liquid ultraviolet rays are formed on the first stamper 18 on which a plurality of inverted master patterns 18a of fine patterns 5b (an example of an optical pattern) constituting a diffraction grating are formed in advance. The curable resin 5a is applied, the transparent substrate 1 is disposed above the curable resin 5a, and the liquid ultraviolet curable resin 4a is also applied on the primer layer 2 on the upper surface of the transparent substrate 1, and the second stamper The first stamper 18 on which the master pattern 18a is aligned with the 17 master patterns 17a is raised, and the mold is clamped and pressed as shown in FIG. 3B. On the second stamper 17, a plurality of inverted master patterns 17a of a fine pattern 4b (an example of an optical pattern) constituting a hologram are formed in advance. The two stampers 17 and 18 are transparent to ultraviolet rays. For example, a quartz substrate manufactured by Nippon Quartz Co., Ltd. is used, and a fine pattern is formed in advance by photolithography. By irradiating ultraviolet rays from outside the second stamper 17 while both stampers 17 and 18 are under pressure, the two layers of ultraviolet curable resins 4a and 5a are cured. By this curing, the UV-curable resin layers 4 and 5 are integrated on the primer layers 2 and 3, and the master patterns 17 a and 18 a from the stampers 17 and 18 are formed on the surfaces of the UV-curable resin layers 4 and 5. Inverted fine patterns 4b and 5b are transferred and formed by a plurality. Next, the mold is released from both stampers 17 and 18. In releasing the mold, the fact that the dimensions of the transparent substrate 1 are larger than the stampers 17 and 18 and that the outer peripheral portion of the transparent substrate 1 protrudes from the outer peripheral surfaces of the stampers 17 and 18 is used. As a specific example,
The size of the transparent substrate 1 is 130 mm square, and the stamper 17,
18 has a diameter of 125 mm. When releasing the stampers 17 and 18 with the upper mold 41 and the lower mold 42 of the die set 31, which will be described later, being opened, a force is applied to the protruding portion 1a of the transparent substrate 1 so that the transparent substrate Since the transparent substrate 1 having the primer layer and the ultraviolet-curable resin layer is released by utilizing the elastic deformation of the substrate 1, the release can be easily performed.

The fourth step, an anti-reflection film forming step S4
Then, as shown in FIG. 3C, the ultraviolet-curable resin layers 4, 5
Antireflection films 6 and 7 are formed thereon. Specifically, Zr was deposited using a deposition apparatus BMC-850DCI manufactured by SYNCHRON CORPORATION.
A two-layer structure of an O ₂ + TiO ₂ mixed layer and a SiO ₂ layer was formed by a high frequency ion plating method (RF-IP). This means that the hologram element intermediate product H 'has been manufactured. The antireflection films 6 and 7, the adhesiveness between the substrate, but preferably has in view of the possible deposition at low temperatures of the composition, the first layer ZrO ₂ alone layer, ZrO ₂ + Ti
An O mixed layer or a ZrO ₂ + Ti ₂ O ₃ mixed layer may be used.

In the fifth dividing step S5, which is shown in FIG.
As shown in (d), a hologram element intermediate product H ', which is a transparent substrate 1 having a primer layer, an ultraviolet curable resin layer, and an antireflection film, has a required shape and size using a dicing apparatus manufactured by Disco Corporation. To produce a plurality of hologram elements H. This hologram element H is as shown in FIG. In FIG. 3, in order to facilitate understanding, the master patterns 17a and 18a and the transferred fine patterns 4a are used.
Although b and 5b are clearly shown in an uneven state, a fine pattern is not shown in FIG.

To explain the structure of the hologram element H again, primer layers 2 and 3 are formed on the front and back surfaces of a transparent substrate 1 made of synthetic resin, and an ultraviolet-curable resin layer is formed on each of the primer layers 2 and 3. 4, 5 are formed, a fine pattern 4b constituting a hologram is formed on the surface (upper surface) of the upper ultraviolet-curable resin layer 4, and on the surface (lower surface) of the lower ultraviolet-curable resin layer 5. Are formed in such a state that the fine pattern 5b constituting the diffraction grating (grating) is aligned with the upper fine pattern 4b, and the antireflection films 6, 7 also have a function of covering and protecting each fine pattern.
Are formed on the ultraviolet-curable resin layers 4 and 5. In the method of manufacturing the hologram element H described above, the fine patterns 4b and 5b on the front and back sides can be collectively formed for a plurality of pieces, so that the manufacturing efficiency is high.

In the sixth step, the hollow fixing step S6, the cap 13 of the laser unit U already manufactured as shown in FIG. 1 using an ultraviolet curing adhesive "3851" manufactured by Loctite as the adhesive 15. The hologram element H is adhered to the upper surface of the hologram to complete the hologram laser unit HL.

Next, the 2P molding step S3 will be described in more detail. FIG. 4 shows components of the 2P molding apparatus 30. The 2P molding apparatus 30 includes a die set 31, a die set mounting section 32, a transport system 33, and an exposure section 34. FIG. 5 is a side view showing the structure of the die set 31. The first stamper 18 is fixed to the lower mold 42 by a stamper fixing part 44, and the second stamper 17 is fixed to the upper mold 41 by the stamper fixing part 43. Guide posts 45 are arranged at the four corners between the upper mold 41 and the lower mold 42, and the lower mold 42 is raised by the hydraulic cylinder 46 while being guided by the guide posts 45, so that the upper mold 41 is moved to the upper mold 41. In contrast, the mold is closed and the mold is opened. The hydraulic cylinder 46 is on the die set mounting section 32 side.

The first stamper 18 is fixed to the lower mold 42 via the stamper fixing part 44, and the second stamper 17 is fixed to the upper mold 41 via the stamper fixing part 43. At this time, the master pattern 18a for a plurality of first stampers 18 and the master pattern 17a for a plurality of second stampers 17 are aligned (aligned) with an accuracy of several μm. This will be described later. The die set 31 is mounted on the die set mounting section 32. FIG.
As shown in (a), a liquid UV-curable resin 5a is applied dropwise onto the first stamper 18 with a dispenser or the like, and the transparent substrate 1 with a primer layer is disposed thereon,
A liquid ultraviolet curable resin 4a was similarly applied dropwise onto the transparent substrate 1 having the primer layer. UV curable resin 4
a- and 5a as MP-107 manufactured by Mitsubishi Rayon Co., Ltd.
Was applied at a viscosity of 330 cps. The pressure of the dispenser was 3 kg / cm ² , the application time was 100 msec, and the application amount was 0.1 g. After the application, the die set 31 was clamped by driving the hydraulic cylinder 46. That is, the first stamper 18 is raised together with the lower mold 42 with the guide post 45 as a guide, and the transparent substrate 1 with the primer layer is sandwiched and pressed between the first stamper 18 and the second stamper 17. . The applied pressure was 3 kg / cm ² , and the pressurized state was maintained for 2 minutes and 30 seconds. Next, in the holding state, the die set 31 is moved from the die set mounting section 32 to the exposure section 3 by the transport system 33.
Then, as shown in FIG. 3 (b), the substrate was irradiated with ultraviolet rays (UV) for 20 seconds in the exposure section 34 to completely cure the ultraviolet curing resins 4a and 5a. The thickness of each of the UV-curable resin layers 4 and 5 formed at this time is 5 to 10 μm.
Met. In this way, the holograms and the fine patterns 4b and 5b of the diffraction grating were transferred and copied to the ultraviolet-curable resin layers 4 and 5, respectively, with the master patterns 17a and 18a of the stampers 17 and 18 turned upside down. Since the master patterns 17a and 18a of the stampers 17 and 18 are accurately aligned in advance, the fine patterns 4b and 5b replicated on the ultraviolet-curable resin layers 4 and 5 are also accurately aligned. After the exposure and curing, the die set 31 is returned to the die set mounting section 32 by the transport system 33 and transported to release the pressurized state.
The mold 1 is opened, and the transparent substrate 1 having the primer layer and the ultraviolet-curable resin layer having the fine patterns formed on both sides is released from the stampers 17 and 18.

The primer layer obtained as described above
An adhesion test was performed on the transparent substrate 1 having the ultraviolet-curable resin layer. When a tape peel test was performed in which fine streaks were formed in a grid pattern of 5 mm × 5 mm and peeled off with a tape, a transparent substrate 1 made of synthetic resin (acrylic resin) and ultraviolet-curable resin layers 4 and 5 were formed. No peeling occurred between the samples. This is because the primer layers 2 and 3 are interposed between them to enhance the adhesion.

Next, a method of aligning the fine patterns 4b and 5b formed on the front and back surfaces of the transparent substrate 1 with the primer layer and the ultraviolet curable resin layer in the above-described 2P molding step S3 will be specifically described. . The alignment accuracy between the fine patterns 4b and 5b on both sides needs to be 20 μm or less as in the case of the glass hologram element in which the current tracking beam generation function and the light branching / error signal generation function are integrated. In order to perform alignment with such an accuracy, the alignment accuracy of the corresponding master pattern between the first stamper 18 and the second stamper 17 fixed to the die set 31 needs to be about 10 μm or less. is there. This is because it is necessary to allow for the lateral displacement of the guide post 45 during mold clamping. The straightness of the guide post 45 due to the clearance is 5 to 10 in the lateral displacement with respect to the extension and contraction length of about 30 cm.
μm.

Although alignment of the fine patterns 4b and 5b on both sides can be performed for each die set, carrying a heavy die set requires a great deal of labor and involves danger. May be damaged. Therefore, the first stamper 18
In order to easily perform the alignment between fine patterns between the second stamper 17 and the second stamper 17, the following method is used. This will be described with reference to FIG. As shown in FIG. 6A, the first stamper 18 and the second stamper 17 are removed from the die set 31, and the first stamper 18 is positioned on the fixing jig 51 having the stamper fitting recess 51a on the upper surface. In this state, the UV-curable resin 52a is applied dropwise onto the first stamper 18, and a dummy substrate 1 'having the same material, size and shape as the transparent substrate 1 is placed thereon. The dummy substrate 1 ′ is fixed to the first stamper 18 by applying ultraviolet light to irradiate ultraviolet rays from above the transparent dummy substrate 1 ′ to cure the ultraviolet-curable resin 52 a. Next, an ultraviolet curable resin 5 is placed on the dummy substrate 1 '.
3a is applied dropwise, and the second stamper 17 is placed thereon and pressed. While visually observing from above using a tool microscope, the second stamper 17 is manually moved in the horizontal plane by X.
By moving in the Y direction, the second stamper 17 is moved with respect to the master pattern 18a of the first stamper 18.
The master pattern 17a is aligned with an accuracy of several μm. Alignment is performed on three or more of a plurality of upper and lower opposed master patterns. That is, the fixing jig 5
1 is moved by an XY table (not shown),
Alignment at multiple locations is performed by changing the position to be observed with a tool microscope. While maintaining the alignment state, ultraviolet rays are irradiated to cure the ultraviolet curing resin 53a, and the second stamper 17 is fixed to the dummy substrate 1 '.
As described above, as shown in FIG. 6B, the first stamper 18 and the second stamper 17 are aligned with the respective master patterns 18a and 17a with high precision via the dummy base 1 '. Is fixed. The positions of the first stamper 18 and the second stamper 17 substantially coincide with each other, and the outer peripheral portion of the dummy base 1 ′ protrudes evenly. The protruding portion is indicated by 1a '. Separately from the die set 31, the stampers 17, 18 are taken out independently, and after that, by using the fixing jig 51 and the dummy base material 1 ′, alignment between the master patterns 17 a, 18 a can be performed, and the overall weight is light. , And can be easily aligned with little labor and little danger. The alignment body A shown in FIG. 6B, which is an integral body of the dummy base material 1 ', the ultraviolet curing resin layers 52 and 53, and the stampers 17 and 18, is removed from the fixing jig 51, and the die set 31 is formed. , The first stamper 18 is fixed on the lower mold 42 with the stamper fixing portion 44, and the mold is clamped to bring the second stamper 17 into contact with the upper mold 41 and fixed on the stamper fixing portion 43. I do. This operation can be performed quickly and easily because simple screwing is sufficient and the screws need only be tightened evenly. After fixing, the mold is opened, and the dummy base material 1 'is peeled off by applying a force to the protruding portion 1a' and taken out. As a result, the first stamper 18 fixed to the lower mold 42 by the stamper fixing section 44 and the second stamper 17 fixed to the upper mold 41 by the stamper fixing section 43 have respective master disk patterns 18a, 17a. Is fixedly held in a state of being aligned with high accuracy of several μm. Therefore, thereafter, in the 2P molding step S3, the ultraviolet curable resin layer 4,
5, the fine pattern 4 transferred from the stampers 17 and 18
The b and 5b are always formed as a hologram fine pattern 4b and a diffraction grating fine pattern 5b in a state of being aligned with high accuracy of several μm.

In the above description, the master patterns 17a and 18a are aligned with each other to align the two stampers 17 and 18.
Alternatively, the alignment may be performed between the markers formed in FIG. In FIG. 3, a plurality of cross-shaped markers serving as a reference of a cutting line when cutting into a plurality of pieces by dicing are shown.
Although formed on the hologram element intermediate product H 'shown in (c), a plurality of cross marks for transferring the markers to the ultraviolet-curable resin layers 4 and 5 are formed on the stampers 17 and 18. The two cross marks are visually aligned under a tool microscope. Alternatively, three or four circular marks may be formed, and the positions of the respective centers of gravity of both circular marks may be calculated by image recognition technology to align the centers of gravity. In addition,
The marker may have any shape, any arrangement, any number.

At least two die sets to which the aligned stampers 17 and 18 obtained as described above are fixed are prepared, one is used for actual operation, and one is stored for standby. Aligned stamper 1
The 2P molding step S3 of forming the fine patterns 4b and 5b on the ultraviolet-curable resin layers 4 and 5 on the transparent substrate 1 with the primer layer by using 7 and 18 is repeated for a plurality of transparent substrates 1. During this time, at least one of the stampers 17 and 18 is shifted. The displacement is checked by sampling microscopy, but when the displacement exceeds a certain limit, the die set that has been on standby can be replaced with a new one to quickly reproduce the stamper in a normal alignment state. , Without interrupting production.

While the preferred embodiment has been described above, the present invention includes the following configuration.

(1) In the above embodiment, the transparent substrate 1
Since a synthetic resin material was used as the transparent substrate 1, it was necessary to improve the adhesion to the ultraviolet-curable resin layers 4 and 5.
The primer layers 2 and 3 were formed thereon, and the ultraviolet curable resin layers 4 and 5 were formed thereon. However, the fine pattern 4b,
The UV-curable resin layers 4 and 5 need not be formed of the resin layer 5b. When a resin layer having good adhesion to the transparent substrate 1 made of synthetic resin is used, the primer layers 2 and 3 are not required. .
The same applies when a glass substrate is used as the transparent substrate 1.

(2) The resin layer for forming the fine pattern may be a resin layer which is cured by light having a wavelength other than ultraviolet rays, an electron beam or radiation, in addition to the ultraviolet curable resin layer. A thermosetting resin layer may be used. Therefore, the stamper does not necessarily have to be of the ultraviolet transmission type, and may be opaque in some cases.

(3) When manufacturing the alignment body A, the stampers 17 and 18 are temporarily fixed to the dummy base material 1 'using an ultraviolet curable resin, but a general adhesive is used instead of the ultraviolet curable resin. May be used. In this case, the dummy substrate 1 'may be opaque.

(4) Although both stampers 17 and 18 are of an ultraviolet transmitting type, the lower first stamper 18 may not have an ultraviolet transmitting property. For example, a metal film may be formed on the outer surface (lower surface), or an irregular surface may be formed on the outer surface.

The above items (1) to (4) are independent of each other, and any number of these items may be appropriately combined.

It should be noted that the wording representing each component described in the claims, the wording representing the connection relationship between the components,
All arbitrary words, including words representing each state, each action, each action, each process, etc., are merely expressions for convenience of explanation, and therefore should not be interpreted restrictively in any way. It must be construed that all equivalent expressions are included without departing from the spirit of the technical idea of the present invention, or the meaning of each word must be interpreted in the broadest sense. The words in the section of the means for solving the problems and the section of the effect of the invention should be interpreted in the same manner. In particular, "optical elements", "optical patterns", "fine patterns", "holograms", "diffraction gratings", "stampers", "master patterns", "transparent substrates", "dummy substrates", "ultraviolet curable resins", "alignment bodies", "die" The terms “set”, “primer layer”, “anti-reflection film” and the like must be interpreted as such.

[0050]

According to a first aspect of the present invention, there is provided a method of manufacturing an optical element.
According to the invention, the master pattern of the first stamper and the second master
In this state, the first stamper and the second stamper are temporarily fixed to the front and back surfaces of the dummy base material, and the temporarily fixed alignment body is fixed to the die set. In addition, since the dummy base material is removed from the alignment body, the master pattern of the first stamper and the master pattern of the second stamper can be aligned with high accuracy. Independently of the above, alignment is performed using a dummy base material, so that alignment can be performed extremely easily and efficiently as compared with the case where alignment is performed for each heavy die set.

According to the second aspect of the present invention, the dummy base is fixed via the ultraviolet curable resin applied on the first stamper, and the second base is fixed on the ultraviolet curable resin applied on the dummy base. An ultraviolet-transmitting stamper is placed, and the second stamper is moved while the ultraviolet-curable resin is in an uncured state, so that the first
The alignment of the master pattern of the second stamper is performed with respect to the master pattern of the stamper, and the present invention can be favorably applied to an optical element having a general form.

According to the third aspect of the present invention, since both stampers are peeled by applying a force to the protruding portion of the transparent substrate, the peeling from the ultraviolet-curable resin layer can be performed efficiently.

According to the fourth aspect of the present invention, a plurality of die sets in which both stampers of the alignment body are fixed and the dummy base material is removed are prepared, and when a malfunction occurs in the active die set, another die set is prepared. Since the replacement is performed, the production is not interrupted and the productivity can be improved.

According to the fifth aspect of the present invention, it is possible to favorably manufacture a hologram element in which a fine pattern forming a hologram and a fine pattern forming a diffraction grating are formed on both sides.

According to the invention of claim 6, the adhesion between the transparent substrate made of a synthetic resin and the ultraviolet-curable resin layers on the front and back can be improved.

According to the present invention for the optical element, the alignment accuracy of the optical patterns on both the front and back surfaces is high, and the adhesion between the transparent substrate made of synthetic resin and the ultraviolet curable resin layer is good. In addition, reflection of incident light can be prevented, and weather resistance is good. Further, it is advantageous for detecting each signal when used in a hologram laser unit.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a schematic structure of a hologram element (optical element) according to an embodiment of the present invention and a hologram laser unit manufactured by attaching the element.

FIG. 2 is a process chart of a method of manufacturing a hologram laser unit according to the embodiment.

FIG. 3 is an explanatory diagram of a method of manufacturing a hologram element by a 2P method (photopolymer method) according to the embodiment;

FIG. 4 is a diagram showing components of a 2P molding apparatus used in the method of manufacturing a hologram element according to the embodiment.

FIG. 5 is a side view showing a structure of a die set in the 2P molding apparatus according to the embodiment.

FIG. 6 is an explanatory diagram of a method of aligning a master pattern of a first stamper and a master pattern of a second stamper in the method of manufacturing a hologram element according to the embodiment;

FIG. 7 is an explanatory diagram of a method of manufacturing a hologram element to which a conventional method of manufacturing a semiconductor device is applied.

FIG. 8 is an explanatory view of a method of manufacturing a hologram element by a conventional molding method using a UV-curable resin called a 2P method (photopolymer method).

FIG. 9 is an explanatory view of a method of manufacturing a hologram element by a conventional 2P method, wherein a fine pattern is formed on both front and back surfaces.

[Explanation of symbols]

H: hologram element U: laser unit HL: hologram laser unit H ': hologram element intermediate product 1: transparent substrate 1': dummy substrate 1a, 1a ': protruding part 2, 3, ... Primer layers 4, 5 ... UV-curable resin layers 4a, 5a ...
UV curable resin 4b, 5b Fine pattern 6, 7 Antireflection film 11 Laser chip 12 Light receiving element 13 Cap 15 UV curable adhesive 17 Second stamper 17a .. Master pattern 18 first stamper 18a master pattern 30 2P molding device 31 die set 32 die set mounting section 33 transfer system 34 exposure section 41 upper mold 42 …… Lower mold 43,44 ……
Stamper fixing section 45 Guide post 46 Hydraulic cylinder 51 Fixing jigs 52, 53
UV-curable resin layer 52a, 53a ... UV-curable resin

Claims (9)

[Claims] 1. A method of manufacturing an optical element, comprising a step of transferring an optical pattern from a master pattern of a first stamper and a second stamper to both front and back surfaces of a transparent substrate, wherein both stampers are aligned with each other. A method for manufacturing an optical element, wherein the dummy base is temporarily fixed to a dummy base in a state, and both stampers of the temporarily fixed alignment are fixed to a die set, and then the dummy base is removed from the alignment base. 2. An ultraviolet-transmitting stamper, wherein an ultraviolet-transmitting stamper is used as at least one of the stampers, and the transparent substrate is sandwiched by both stampers in a state of being adhered to an ultraviolet-curable resin on the front and back surfaces of the transparent substrate. Production of an optical element in which the UV-curable resin is cured while the master patterns of both stampers are transferred to the UV-curable resin by irradiating ultraviolet rays through the resin, and the stampers are peeled off from the cured UV-curable resin layer 2. The method according to claim 1, wherein the alignment body is also manufactured using an ultraviolet curable resin. 3. The UV-curable resin is cured in a state where the transparent base material protrudes from both stampers, and both stampers are separated from the UV-curable resin layer cured in a state where a force is applied to the protruding portion of the transparent base material. The method for manufacturing an optical element according to claim 2, wherein 4. A plurality of die sets in which both stampers of an alignment body are fixed and a dummy base material is removed are prepared, and when a defect occurs in the die set during manufacturing using one die set, another die set is prepared. 4. The method for manufacturing an optical element according to claim 1, wherein the optical element is replaced with a set. 5. The method according to claim 2, wherein a fine pattern forming a hologram is formed on one of the ultraviolet curing resin layers on the front and back surfaces, and a fine pattern forming a diffraction grating is formed on the other ultraviolet curing resin layer. Item 5. A method for manufacturing an optical element as a hologram element according to any one of Items 4 to 4. 6. The method according to claim 2, wherein a synthetic resin is used as the transparent substrate, and a primer layer is interposed between the transparent substrate and the front and back ultraviolet-curable resin layers. A method for producing the optical element described in the above. 7. An optical element in which a primer layer is formed on both front and back surfaces of a transparent substrate made of a synthetic resin, and an ultraviolet curable resin layer having an optical pattern formed on each primer layer is formed. 8. The optical element according to claim 7, wherein an antireflection film is formed on each of the ultraviolet curable resin layers. 9. The optical pattern of one of the ultraviolet-curable resin layers is a fine pattern constituting a hologram, and the optical pattern of the other ultraviolet-curable resin layer is a fine pattern constituting a diffraction grating. Item 9. An optical element as the hologram element according to item 8.