JP2003085839A - Method of manufacturing optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an intermediate layer containing a radiation-curing resin and having rugged patterns, such as grooves and prepits, on its surface to have a uniform thickness and to exactly transfer the matrix patterns of the rugged patterns possessed by a stamper to the intermediate layer, in manufacturing an optical information medium having an information recording layer on the above intermediate layer. SOLUTION: This method of manufacturing the optical information medium is provided with a process of forming the intermediate layer transferred with the rugged patterns by forming a resin layer containing the radiation curing resin in the state of putting the same between the stamper having the rugged patterns on its surface and a substrate of the medium, then irradiating the resin layer with radiations and peeling the stamper, and a stamper, the surface of which has the rugged patterns formed thereon, is constituted of a cyclic polyolefin or polystyrene resin, is used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing an optical information medium.

[0002]

2. Description of the Related Art In recent years, there has been a great demand for higher density and larger capacity of optical discs. Currently, it has a recording capacity of about 4.7 GB on one side, which is about seven times that of a compact disc.
VD (Digital Versatile Disk) is on sale,
Development of a technology capable of recording more information is being actively conducted.

Techniques for increasing the recording capacity of an optical disk include shortening the wavelength of the recording / reproducing beam, increasing the NA (numerical aperture) of the objective lens in the recording / reproducing beam irradiation optical system, increasing the number of information recording layers, and multilevel. Records and the like. Among these, three-dimensional recording by increasing the number of information recording layers is capable of dramatically increasing the capacity at low cost, as compared with shortening the wavelength and increasing the NA. Multilayer optical information media for three-dimensional recording are disclosed in, for example, Japanese Patent Laid-Open Nos. 9-161329 and 9-631.
No. 22 and Japanese Patent Application Laid-Open No. 10-302315.

In a multi-layer optical information medium (hereinafter, also referred to as a multi-layer medium), as shown in each of the above publications, a plurality of information recording layers are generally laminated with an intermediate layer made of a transparent resin sandwiched therebetween. Target. Specifically, the first on the substrate
Of the information recording layer, an intermediate layer having a concavo-convex pattern on the surface thereof is formed thereon, and a second information recording layer is formed thereon, whereby the concavo-convex pattern is formed on the second information recording layer. Transcribe. As the uneven pattern, for example,
Examples include prepits and grooves (guide grooves) that hold data, tracking information, address information, and the like. To form this uneven pattern, as described in each of the above publications, 2P (Phot
o Polymerization) method is generally used.

In order to secure the stability of the focus servo, the multilayer medium is required to have a small variation in the distance between adjacent information recording layers in the in-plane direction of the medium. That is, the intermediate layer provided between the recording layers is required to have a uniform thickness. Also, if the thickness unevenness of the intermediate layer is large, when pressing the stamper to transfer the uneven pattern,
It is difficult for the stamper to press the intermediate layer uniformly, and as a result,
Transfer defects are likely to occur. Further, when the intermediate layer is composed of a radiation curable resin such as an ultraviolet curable resin, if the thickness of the intermediate layer is large, uneven curing tends to occur when the intermediate layer is cured, which also causes transfer defects. It tends to occur.

Further, even if the concave-convex pattern is accurately transferred from the stamper to the intermediate layer when the intermediate layer is formed, if the stamper is difficult to peel off from the intermediate layer, that is, if the releasability is poor, the intermediate layer is formed. A part of the peeling occurs together with the stamper, resulting in a defect. Therefore, it is required that the stamper has good releasability with respect to the resin forming the intermediate layer. Further, when the intermediate layer is composed of, for example, an ultraviolet curable resin and the intermediate layer is formed on the information recording layer opaque to ultraviolet rays, it is necessary to irradiate the intermediate layer with ultraviolet rays for curing through a stamper. Therefore, the stamper must be made of a material that is transparent to ultraviolet rays.

In the above-mentioned Japanese Patent Laid-Open No. 9-161329,
It has been proposed to provide a step of spreading the liquid resin between the substrate and the stamper by integrally rotating the substrate and the stamper while sandwiching the liquid resin between the substrate and the stamper. The publication does not describe the stamper constituent material, and does not pay attention to the releasability of the stamper. In this publication, ultraviolet rays are radiated through the substrate.

In Example 1 of JP-A-9-63122, a semitransparent intermediate layer made of a mixture of silicon and silicon nitride is formed on a first read-only information surface made of phase pits for holding data. Then, an ultraviolet curable resin layer is provided thereon. The surface of this ultraviolet curable resin layer is formed with a second pit composed of phase pits formed by transfer from the stamper.
It is a playback-only information side. In this embodiment, a transparent stamper made of plastic is used, and ultraviolet rays are made incident through the stamper. In this publication, no attention is paid to making the thickness of the resin layer existing between the adjacent information surfaces uniform, and no attention is paid to the releasability of the stamper.

In the embodiment disclosed in Japanese Patent Laid-Open No. 10-302315, a photo-curable resin is dropped on a transparent stamper, a substrate is placed thereon, and then the transparent stamper is rotated at a rotation speed of 200.
Spread the photocurable resin by rotating it at 0 rpm,
Next, ultraviolet rays are irradiated through the transparent stamper to cure the resin. The transparent stamper comprises a transparent plastic disc having a thickness of 5 mm and a Ni stamper on which an uneven pattern is formed, filled with a photo-curable resin and cured by an ultraviolet lamp, and then the Ni stamper is peeled off. It is formed by. In this embodiment, the surface of the transparent stamper is made of a photo-curable resin, and the resin to be spread is a photo-curable resin, so that the stamper has poor releasability. Further, in the publication, both the photocurable resin on the surface of the transparent stamper and the photocurable resin to be spread are UV curable resins. The ultraviolet curable resin absorbs ultraviolet rays because the polymerization initiator remains after curing. Therefore, the transparent stamper used in this publication is low in transparency to ultraviolet rays, which is not preferable.

By the way, in an optical information medium having only one information recording layer, it is common to simultaneously form a concavo-convex pattern such as grooves and prepits when a resin substrate is manufactured by injection molding. However, for example, in an optical disk substrate that requires high accuracy such as a reference disk, a transparent resin layer having the above-mentioned concavo-convex pattern is formed on the surface of a highly rigid and highly accurate smooth substrate made of glass, etc. The information recording layer is also formed on the substrate. The concave-convex pattern is formed on the transparent resin layer by pressing with a stamper, similar to the intermediate layer in the multilayer optical information medium.

[0011]

In order to meet the demand for higher density and larger capacity of optical discs, it is necessary to increase battle recording density and track density. For that purpose, it is necessary to reduce the prepits or the groove pitch. Therefore, it is necessary to accurately form a master pattern of fine prepits and grooves on the stamper.

According to the present invention, when an optical information medium in which an information recording layer is formed on an intermediate layer containing a radiation curable resin and having a concavo-convex pattern such as grooves and prepits on the surface thereof, the intermediate layer is uniformly formed. The object is to accurately transfer the master block pattern of the concavo-convex pattern, which is included in the stamper, to the intermediate layer while being formed to have a uniform thickness.

[0013]

The above objects are achieved by the present invention described in (1) to (3) below. (1) An intermediate layer having at least one information recording layer on a substrate, and containing a radiation curable resin between the information recording layer and the substrate and / or between two adjacent information recording layers. A method of manufacturing an optical information medium having, wherein a resin layer containing a radiation curable resin is sandwiched between a stamper having a concave-convex pattern on the surface and a substrate,
Next, a step of forming an intermediate layer on which the concavo-convex pattern is transferred by irradiating the resin layer with radiation and then peeling off the stamper is provided. As the stamper, at least the surface on which the concavo-convex pattern is formed is circular. A method for manufacturing an optical information medium using a material composed of polyolefin or polystyrene resin. (2) The method for producing an optical information medium according to (1), wherein at least the surface on which the concavo-convex pattern is formed is made of an amorphous cyclic polyolefin as the stamper. (3) The method for manufacturing an optical information medium according to (1) or (2), wherein the arrangement pitch of the concavo-convex pattern is 0.7 μm or less.

[0014]

In the present invention, an intermediate layer having a concave-convex pattern on the surface is formed between the substrate and the information recording layer and / or between two adjacent information recording layers. The concavo-convex pattern is a prepit or a groove, and a reflective layer (including a semi-transparent layer) or a recording layer is formed on the concavo-convex pattern forming surface of the intermediate layer to form an information recording layer.

The intermediate layer is formed by pressing a resin layer containing a radiation curable resin with a stamper having a master pattern of the concavo-convex pattern.

The stamper used in the present invention is entirely composed of a cyclic polyolefin or polystyrene resin, or at least the surface on which the matrix pattern is formed is composed of a cyclic polyolefin or polystyrene resin. Therefore, the releasability from the intermediate layer made of a cured product of the radiation curable resin is good, and the cyclic polyolefin is particularly good.

The stamper used in the present invention is permeable to the radiation. Therefore, it is possible to irradiate the radiation through the stamper. Therefore, the resin layer can be cured by irradiating radiation through the stamper. Therefore, even if the substrate is opaque or an opaque information recording layer exists between the substrate and the intermediate layer, there is no problem in curing the resin layer. Further, when the radiation is applied through the stamper, the curing of the resin layer starts from the region in contact with the stamper. Therefore, the releasability of the stamper is further improved.

Moreover, the cyclic polyolefin has a higher transmittance for ultraviolet rays not only for ultraviolet curable resins whose transmittance is low because of its high ultraviolet absorption but also for other resins such as polycarbonate. high. Therefore, in the present invention, since the resin layer can be irradiated with ultraviolet rays having sufficient intensity through the stamper, a sufficiently cured intermediate layer can be obtained.

The resin stamper mass-produced by injection molding is remarkably inexpensive and therefore can be disposable. On the other hand, a stamper manufactured by using another method or another material is expensive and is used repeatedly, but it is necessary to wash the resin adhering to the surface every time it is used.
On the other hand, since the disposable stamper does not need to be washed after use, the productivity of the medium is significantly improved and the medium production cost can be remarkably reduced.

By the way, in Japanese Patent Laid-Open No. 1-285040, a radiation curable resin is discharged onto the surface of a stamper, an optical disk substrate is pressed onto the stamper resin, and then irradiated with radiation, and then the stamper and the optical disk substrate. A method of transferring the pattern on the stamper surface to the optical disk surface by peeling the stamper is described. The invention described in the publication is
This is the same as the present invention in that the stamper is made of an olefin resin. However, the publication does not describe or suggest the use of cyclic polyolefin as the olefin resin. In the example of the publication, a stamper is manufactured using polymethylpentene which is a crystalline linear olefin resin. Further, the publication does not pay attention to the uniformity of the thickness of the radiation curable resin layer onto which the pattern is transferred. Further, the publication does not describe a multilayer medium.

As described above, in order to meet the demand for higher density and larger capacity of the optical information medium, it is necessary to accurately form a fine master pattern on the stamper. When the stamper is formed by injection molding, the mold shrinkage easily occurs due to shrinkage of the resin during cooling. That is, even if the concave-convex pattern is accurately transferred from the mold to the resin, the resin contracts during cooling, resulting in a shift in the pattern. Such a pattern shift has a greater effect as the pattern arrangement pitch is smaller even if the shift amount is the same.

The polymethylpentene used in the examples of the above-mentioned JP-A-1-285040 is a crystalline linear olefin resin, so that it is anisotropically greatly contracted during cooling during injection molding. Therefore, a large pattern shift occurs. The groove formed in the example of the publication has a wide pitch of 1.6 μm, but if polymethylpentene is used in the recent manufacture of a narrow track pitch medium, the pattern shift exceeds the allowable range. Further, since polymethylpentene is fragile, when it is made into a thin plate-like body such as a stamper, it becomes easily broken, which is a problem. further,
According to the research conducted by the inventors of the present invention, it has been found that when polymethylpentene is used, the stamper is more likely to be deformed (warp is twisted).

Further, polyethylene and polypropylene among the olefin resins also have crystallinity, and therefore, like the polymethylpentene, there is a problem of pattern displacement and cracking. In addition, since polyethylene and polypropylene do not have a relatively low molecular weight grade suitable for forming a fine pattern by injection molding, it is necessary to significantly increase the resin melting temperature during injection molding. Since the temperature at which the stamper is taken out becomes high, the stamper is likely to be deformed (warp or twist).

On the other hand, the cyclic polyolefin used in the present invention is usually amorphous, and since the polystyrene resin is amorphous, the above-mentioned pattern shift is small and the stamper deformation is small. . In particular, the amorphous cyclic polyolefin is preferable because the pattern shift and deformation of the stamper are significantly reduced and the stamper is hard to break.

In order to accurately transfer a fine pattern during injection molding, it is preferable to raise the resin melting temperature. Since cyclic polyolefin has a cyclic structure, it has high heat resistance. Therefore, since the resin melting temperature at the time of injection molding can be increased, a fine pattern can be accurately transferred. Moreover, even if the resin melting temperature during injection molding is set to a high temperature, the deformation of the stamper is small.

Further, the inventors of the present invention make the pattern deviation extremely small by setting the resin melting temperature at the time of injection molding of the cyclic polyolefin to be higher than the temperature generally used conventionally. It is possible,
Moreover, they have found that the amount of deformation of the stamper can be suppressed within a range where there is no problem.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

The optical information medium to which the present invention is applied has at least one information recording layer. The information recording layer in this specification includes at least a read-only layer or a recording layer. The read-only layer is a layer that has a concavo-convex pattern such as prepits for holding recorded information and reflects at least a part of the reproduction beam, and the recording layer contains a recording material such as a phase change material or an organic dye. However, it is a layer in which the recording mark can be rewritten and additionally recorded. The recording layer is provided with a concavo-convex pattern such as grooves and prepits for holding preformat information and tracking servo.

The multi-layer medium in the present specification has an information recording layer having a plurality of information recording layers and recording or reproducing by a recording / reproducing beam transmitted through other information recording layers. It is a medium. An intermediate layer through which a recording / reproducing beam can pass is present between adjacent information recording layers.

FIG. 1 and FIG. 2 respectively show an example of the structure of a multi-layer medium among the media manufactured by the present invention. Figure 1
The medium shown in (1) has a first intermediate layer TL-1, a first information recording layer IL-1, a second intermediate layer TL-2, and a second information recording layer IL-2 on a disc-shaped substrate SB. And protective layer PL
In this order. In addition, the medium shown in FIG. 2 has a first information recording layer IL-1, an intermediate layer TL, a second information recording layer IL-2, and a protective layer PL in this order on a disk-shaped substrate SB. FIG. 3 shows an example of the structure of a single-layer medium having only one information recording layer among the media manufactured by the present invention. The medium shown in FIG. 3 has a disc-shaped substrate SB,
It has an intermediate layer TL, an information recording layer IL, and a protective layer PL in this order.

In each of these media, the information recording layer IL,
IL-1 and IL-2 are each formed with a concavo-convex pattern including grooves and prepits. Also, FIG.
The medium shown in FIG. 1 corresponds to the first intermediate layer TL− from the medium shown in FIG.
It omits 1. Therefore, on the upper surface of the substrate SB,
An uneven pattern composed of grooves and prepits is formed.

The structure of each part of these media will be described below.

Substrate SB, Protective Layer PL In these media, the recording / reproducing beam enters not from the substrate SB side but from the protective layer PL side. Therefore, the substrate S
B need not be transparent to the recording / reproducing beam.
The thickness of the substrate SB is usually 0.2 to 1.8 mm, preferably 0.4 to 1.2 mm. Substrate S in FIG.
B may be made of a resin as in the case of a substrate of an ordinary optical information medium. In that case, the concavo-convex pattern on the surface of the substrate SB required for the information recording layer IL-1 can be formed by injection molding. On the other hand, the substrate SB in FIGS. 1 and 3 is
It is a highly rigid and smooth substrate made of glass, resin, metal, or the like, on which the intermediate layer TL-1 or TL having the uneven pattern formed by the 2P method is provided.

The protective layer PL has a light-transmitting property in order to transmit a recording / reproducing beam. For the protective layer PL, a resin plate or a glass plate having the same thickness as the substrate SB may be used. However, in order to increase the NA of the recording / reproducing beam irradiation optical system to correspond to the high recording density, it is preferable to thin the protective layer PL. In this case, the protective layer PL has a thickness of 30 to
It is preferable to select from the range of 300 μm. When the protective layer PL is too thin, the optical influence of dust adhering to the surface of the protective layer PL becomes large. On the other hand, if the protective layer PL is too thick, it becomes difficult to increase the NA.

When thinning the protective layer PL, for example, a sheet made of a transparent resin is attached to the protective layer PL with various adhesives or pressure-sensitive adhesives, or a transparent resin is applied to the protective layer PL. It may be PL.

In the medium having the structure shown in each of FIGS. 1 to 3, the recording / reproducing beam may be incident on the information recording layers IL, IL-1, IL-2 through the substrate SB.

Information Recording Layer On the information recording layers IL, IL-1, IL-2, a concavo-convex pattern such as prepits and grooves is formed. This concavo-convex pattern is formed by transferring the concavo-convex pattern formed on the surface of the intermediate layers TL, TL-1, TL-2 or the substrate SB. The information recording layer includes at least a read-only layer or a recording layer.

The read-only layer needs to reflect part of the read beam (information recording layer IL-2) or most of the read beam (information recording layers IL and IL-1), and therefore metal (including alloy). The reflective layer is made of a film or a dielectric multilayer film.
The information recording layer in a read-only medium is usually composed of only a reflective layer.

The recording layer is of a rewritable type or a write-once type using a phase change recording material, a rewritable type using a magneto-optical recording material, or a write-once type using an organic dye as a recording material. It may be any one of the
Other recording materials may be used. However, it is preferable to use the phase-change recording material because the light transmittance is higher than that of other recording materials and therefore the number of recording layers can be increased. In the recording medium, the information recording layer may be composed of only the recording layer, but other layers such as a reflective layer and a dielectric layer may be provided if necessary.

For example, the information recording layer in a phase change recording medium is usually constructed by providing a dielectric layer on both sides of the recording layer. Further, the information recording layer IL-1 existing at the deepest side when seen from the recording / reproducing beam incident side is usually a reflection layer, a dielectric layer, a phase change recording layer, and a dielectric layer in this order from the bottom in the figure. It has a laminated structure. Since it is necessary to transmit a recording / reproducing beam to the information recording layer IL-2,
Although no reflective layer is provided, a reflective layer that is semi-transparent to the recording / reproducing beam may be provided, if necessary, to provide a structure similar to IL-1.

Intermediate Layer The intermediate layers TL, TL-1 and TL-2 are cured products of a radiation curable resin such as an ultraviolet curable resin and are used for recording / recording.
It is made of a material having a high transmittance for the reproduction beam. However, in FIGS. 1 and 3, the intermediate layers TL and TL-1 existing between the substrate SB and the information recording layers TL and TL-1.
Need not be transparent to the recording / reproducing beam.

The thickness of the intermediate layer existing between two adjacent information recording layers is not particularly limited, and in the case of a multi-layer medium, it may be set so that the crosstalk between the adjacent information recording layers falls within an allowable range. Is preferably 5 to 50 μm, more preferably 10 to 50 μm. On the other hand, the thickness of the intermediate layer existing between the substrate and the information recording layer is usually 1 to 10
It is preferably 0 μm.

Next, a method of forming the intermediate layer TL on the substrate SB when manufacturing the medium shown in FIG. 3 will be described. In the following, a case where an ultraviolet curable resin is used as the radiation curable resin will be described as an example, but in addition to this, a resin curable by another radiation such as an electron beam can also be used.

First, a resin layer containing a radiation curable resin is sandwiched between a stamper having a concave-convex pattern which is a master pattern of grooves or prepits and a substrate SB. At this time, the resin layer is pressed by applying an external force to the stamper, or the resin layer is pressed by the weight of the stamper. In this state, the resin layer is cured by irradiating ultraviolet rays through the stamper to form the intermediate layer TL. Next, the stamper is peeled off from the intermediate layer TL. After that, the information recording layer IL and the protective layer PL are formed to obtain the medium having the structure shown in FIG.

To put the resin layer between the stamper and the substrate SB, either of the following two methods may be used. In the first method, a resin layer is formed on the substrate SB by a spin coating method, and then a stamper is placed on the resin layer and pressed. In the second method, the resin is annularly supplied to the inner peripheral portion of the substrate SB, and the substrate SB and the stamper are integrally rotated and spin-coated while the stamper is placed on the resin. The resin is spread between the SB and the stamper.

In the present invention, at least the surface of the stamper which is in contact with the resin layer is made of a cyclic polyolefin or a polystyrene resin, and for the reasons described above, it is preferably made of an amorphous cyclic polyolefin. Any resin may be used as long as it has high transparency to ultraviolet rays used for curing the resin layer. Examples of the amorphous cyclic polyolefin excellent in ultraviolet light transmission include those starting from a norbornene compound. This product also has excellent heat resistance.

Specifically, an amorphous cyclic polyolefin having a repeating structural unit represented by the following formula (1) is preferable.

[0048]

[Chemical 1]

In the above formula (1), q is an integer of 0 to 4, and R ₁ and R ₂ are each a hydrogen atom, a halogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, an ethylidene group or methoxy. It represents a carbonyl group, a cyano group or a pyridyl group. R ₁ and R ₂ may be the same or different. R ₁ and R ₂ may be bonded to each other to form a ring.

The amorphous cyclic polyolefin used in the present invention is preferably a homopolymer composed of only the same units among the repeating structural units represented by the above formula (1), but R ₁ , R ₂ and It may be a copolymer composed of a plurality of types of repeating structural units in which one or more of q are different from each other. Further, it may be a copolymer containing other structural units, such as ethylene, in addition to the repeating structural unit. The amorphous cyclic polyolefin used in the present invention preferably has a number average molecular weight of 5,000 to 100,000, particularly 10,000 to 40,000.

The halogen atom, the ester group, the nitrile group and the pyridyl group in the formula (1) may be referred to as polar groups in the following description.

Such an amorphous cyclic polyolefin is
As the monomer, for example, norbornene, and an alkyl and / or alkylidene-substituted product thereof, for example, 5-
Methyl-2-norbornene, 5,6-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, etc .; dicyclopentadiene, 2,3-dihydro Dicyclopentadiene, alkyl substitution products thereof such as methyl, ethyl, propyl and butyl, and polar group substitution products such as halogen: dimethanooctahydronaphthalene, alkyl and / or alkylidene substitution products thereof, and polar group substitution products such as halogen. Body, for example 6-methyl-1,4:
5,8-Dimethano-1,4,4a, 5,6,7,8,8
a-Octahydronaphthalene, 6-ethyl-1,4:
5,8-Dimethano-1,4,4a, 5,6,7,8,8
a-octahydronaphthalene, 6-ethylidene-1,
4: 5,8-dimethano-1,4,4a, 5,6,7,
8,8a-octahydronaphthalene, 6-chloro-1,
4: 5,8-dimethano-1,4,4a, 5,6,7,
8,8a-octahydronaphthalene, 6-cyano-1,
4: 5,8-dimethano-1,4,4a, 5,6,7,
8,8a-octahydronaphthalene, 6-pyridyl-
1,4: 5,8-Dimethano-1,4,4a, 5,6
7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5,8-dimethano-1,4,4
a, 5,6,7,8,8a-octahydronaphthalene, etc .; a cyclopentadiene trimer, for example, 4,
9: 5,8-Dimethano-3a, 4,4a, 5,8,8
a, 9,9a-octahydro-1H-benzoindene,
4,11: 5,10: 6,9-trimethano-3a, 4
4a, 5, 5a, 6, 9, 9a, 10, 10a, 11,
A saturated polymer produced by hydrogenating a ring-opening polymer obtained by polymerizing 11a-dodecahydro-1H-cyclopentaanthracene and the like by a known ring-opening polymerization method by a conventional hydrogenation method. .

Regarding such a cyclic polyolefin, JP-A-3-223341 and JP-A-60-
It is described in Japanese Unexamined Patent Publication No. 26024.

When an amorphous cyclic polyolefin is used,
For example, as described in JP-A-5-81699, an alkylphenol condensate may be mixed with an amorphous cyclic polyolefin.

In the present invention, commercially available amorphous cyclic polyolefin can be used. Examples of commercially available amorphous cyclic polyolefins include Zeonex and Zeonoa (both manufactured by Zeon Corporation), Apel (manufactured by Mitsui Chemicals, Inc.), Arton (manufactured by JSR Corporation), and the like. Arton and Zeonex are obtained by ring-opening polymerization of norbornene-based monomers and hydrogenation. Apel is an ethylene-tetracyclododecene copolymer {(C
₂ H _{4) m} - is a _{(C 12 H 16) n}} . Of these,
Zeonex, Zeonoa and Apel are preferred, Zeonex and Zeonoa are more preferred, and Zeonex is even more preferred. Zeonex E28R for Zeonex
And Zeonex 280R are preferred, and Zenore as Zenoa
1060R and Zeonor 1420R are preferred. Zeonex E28R and Zeonex 280R have a repeating structural unit represented by the above formula (1).

The resin stamper is manufactured by the injection molding method. In the injection molding method, a pattern formed on a metal stamper made of Ni or the like is transferred to a resin to produce a resin stamper. In injection molding of cyclic polyolefin, especially Zeonex described above, it is preferable to set the resin melting temperature (also referred to as cylinder temperature) as high as possible within a range not exceeding the heat resistance of the resin used. By increasing the resin melting temperature, it becomes easy to accurately transfer a fine pattern from the mold (metal stamper) to the resin. Specifically, the resin melting temperature is 320 ° C. or higher, particularly 350 ° C.
The above is preferable. However, if the resin melting temperature is too high, the decomposition of the resin proceeds, which is not preferable, and the generated decomposed product adheres to the surface of the metal stamper to deteriorate the surface property of the resin stamper, which is not preferable. Therefore, the resin melting temperature is preferably 400 ° C. or lower, and particularly preferably 380 ° C. or lower.

The shape and size of the stamper are not particularly limited, but usually, the stamper has substantially the same shape as the resin layer to which the pattern is transferred, and its outer diameter and inner diameter are substantially the same as the outer diameter and inner diameter of the resin layer, respectively. Good. However, if the outer diameter of the stamper is set to be slightly larger than the outer diameter of the substrate SB,
The stamper can be easily peeled off from the intermediate layer. The thickness of the stamper is usually preferably in the range of 0.3-3 mm. If the stamper is too thin, it will be difficult to form the stamper, and it will be difficult to form a uniform uneven pattern over the entire surface of the stamper. On the other hand, if the stamper is too thick, the rigidity of the stamper becomes too high. Since it is difficult to manufacture a stamper without any deformation such as warpage, the stamper has a deformation. The slight deformation is corrected when the stamper is pressed, but it is difficult to correct when the stamper has high rigidity. Therefore, if the stamper is too thick,
The deformation of the stamper is directly transferred to the intermediate layer,
The uneven thickness of the intermediate layer becomes large.

In the method of spreading the resin by rotating the substrate SB and the stamper while sandwiching the resin between them, the centrifugal force generated by the rotation acts to correct the warp of the stamper. In order to effectively utilize this function, it is preferable to make the stamper relatively thin. Specifically, the stamper thickness is 0.3 to 1.8 mm, and particularly 0.3 to
It is preferably 1.4 mm.

The present invention is particularly effective for transferring a fine and accurate uneven pattern from the stamper to the intermediate layer. Specifically, it is particularly effective when the arrangement pitch of the concavo-convex pattern, that is, the groove arrangement pitch or the prepit row arrangement pitch is 0.7 μm or less, and particularly 0.6 μm or less. By applying the present invention, such a fine pattern can be accurately transferred to the intermediate layer. However, if the arrangement pitch of the patterns is too narrow, accurate transfer becomes difficult. Therefore, it is usually preferable to apply the present invention to the formation of a concavo-convex pattern having an arrangement pitch of 0.1 μm or more.

In the read-only medium in which the prepits hold information, the arrangement pitch of the prepit rows and the track pitch are the same, and in the optical recording medium of the groove recording system, the track pitch and the groove arrangement pitch are the same. . On the other hand, in the land / groove recording type optical recording medium, the track pitch is 1/2 times the groove arrangement pitch. For example, in the DVD-RW which is the groove recording method, both the track pitch and the groove arrangement pitch are 0.74 μm, and in the DVD-RAM which is the land / groove recording method, the track pitch is as narrow as 0.61 μm, but the groove arrangement is The pitch is 1.22 μm.

The present invention is characterized in that the stamper is made of a specific resin, and the above-mentioned effects can be obtained. Therefore, the specific procedure and conditions for forming the intermediate layer using the stamper are not particularly limited. That is, no matter what the procedure and conditions are, the use of the stamper limited by the present invention provides superior effects to the case where the conventional stamper is used under the same procedure and conditions.

[0062]

[Example] A Ni stamper having a thickness of 0.3 mm and an outer diameter of 150 mm was attached to a mold, and a resin stamper having a thickness of 0.6 mm and an outer diameter of 120 mm was continuously molded by injection molding. The concavo-convex pattern formed on the resin stamper is a groove pattern having a width of 0.16 μm, an arrangement pitch of 0.32 μm and a depth of 25 nm. The resins used are shown in Table 1 below. The resin melting temperature and mold temperature during injection molding are 3 for Zeonex E28R.
The temperature was set to 60 ° C. and 130 ° C., and other resins were also optimized according to each resin so as to minimize the pattern shift and deformation of the resin stamper.

Ten of a large number of resin stampers obtained by continuous molding were taken out, and the number of sheets in which pattern deviation and cracking occurred was checked by visual inspection. Further, the amount of contact of the resin stamper was measured with a machine precision measuring device (LM-1200) of Ono Sokki Co., Ltd. The results are shown in Table 1.

Next, an ultraviolet curable resin is sandwiched between a 1.1 mm-thick smooth polycarbonate substrate and a resin stamper, the resin is spread by spin coating, and then the resin is irradiated with ultraviolet rays through the resin stamper. Cure
An intermediate layer was formed. Then, the resin stamper was peeled off from the intermediate layer. After this series of operations, the presence or absence of adhesion of the ultraviolet curable resin and the deformation of the resin stamper were examined. This measurement was performed for each of the resin stampers shown in Table 1 for 10 sheets. Table 1 shows the number of resin stampers on which resin adhesion and deformation have occurred.

[0065]

[Table 1]

The effects of the present invention are clear from Table 1. Resin stamper No. 1, N made of amorphous cyclic polyolefin
In o.2, extremely excellent results are obtained in terms of moldability and transferability. On the other hand, a resin stamper N made of polymethylpentene, which is a crystalline linear olefin resin
It can be seen that in o.4, the pattern shift occurs and the surface runout is large, and therefore it is not suitable for forming a fine pattern in the intermediate layer. If the surface runout is large, an intermediate layer having a uniform thickness cannot be formed, so that the information recording layer formed on the intermediate layer is warped or distorted, and the focus servo or tracking servo becomes unstable. In addition,
In this case, the allowable value of the surface runout amount is 100 μm or less.

A resin stamper made of polystyrene is used.
In No. 3, although peeling was possible from the intermediate layer, cracking occurred.
On the other hand, the resin stamper No. 6 made of polycarbonate and the resin stamper No. 7 made of PMMA (polymethylmethacrylate) have high adhesiveness to the ultraviolet curable resin, so that the resin stamper and the polycarbonate substrate are separated when peeled from the intermediate layer. It has been destroyed.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a configuration example of an optical information medium manufactured according to the present invention.

FIG. 2 is a partial cross-sectional view showing a configuration example of an optical information medium manufactured according to the present invention.

FIG. 3 is a partial cross-sectional view showing a configuration example of an optical information medium manufactured according to the present invention.

[Explanation of symbols]

IL, IL-1, IL-2 information recording layer PL protective layer SB substrate TL, TL-1, TL-2 intermediate layer

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/24 563 G11B 7/24 563D // B29L 17:00 B29L 17:00 (72) Inventor Toshifumi Tanaka Tokyo Central 1-13-1, Nihonbashi-ku, T-DK Co., Ltd. (72) Inventor Sou Komaki 1-13-1, Nihonbashi, Chuo-ku, Tokyo T-DK Co., Ltd. F-term (reference) 4F204 AA44 AH79 AJ03 EA03 EA04 EB01 EB29 EK18 4F209 AH79 AJ03 AJ09 PA02 PB01 PC08 PQ11 5D029 LB02 WB11 5D121 AA04 CA06 EE22

Claims (3)

[Claims] 1. A substrate has at least one information recording layer, and a radiation curable resin is contained between the information recording layer and the substrate and / or between two adjacent information recording layers. A method of manufacturing an optical information medium having an intermediate layer, comprising: a stamper having a concave-convex pattern on its surface and a substrate,
A step is provided in which a resin layer containing a radiation curable resin is sandwiched, then the resin layer is irradiated with radiation, and then the stamper is peeled off to form an intermediate layer to which the concavo-convex pattern is transferred. A method for manufacturing an optical information medium using, as the stamper, at least a surface on which the concavo-convex pattern is formed is made of a cyclic polyolefin or a polystyrene resin. 2. The method for manufacturing an optical information medium according to claim 1, wherein at least the surface on which the concavo-convex pattern is formed is made of amorphous cyclic polyolefin as the stamper. 3. The arrangement pitch of the concavo-convex pattern is 0.7.
3. The method for manufacturing an optical information medium according to claim 1, wherein the optical information medium has a thickness of not more than μm.