JP2003016701A - Producing method of optical information medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which allows a transparent intermediate layer to be formed in a uniform thickness and allows a mother die pattern having a rugged pattern which is disposed on a stamper to be exactly transferred to the transparent intermediate layer in the production of a multilayer optical information medium in which a plurality of information recording layers are laminated via the transparent intermediate layer comprising resin and the rugged pattern retaining information on the surface of the transparent intermediate layer exists. SOLUTION: This producing method of optical information medium comprises a first coating process of forming a first resin layer on a substrate by means of a spin-coat method, a second coating process of forming a second resin layer by performing spin-coating while holding resin between the first resin layer and the stamper and obtaining a resin laminate consisting of both of the resin layers, a hardening process of forming the transparent intermediate layer by irradiating the resin laminate with active energy rays and hardening the same, a stripping process of stripping the stamper from the transparent intermediate layer and a laminating process of forming other information recording layers on the transparent intermediate layer.

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 a multilayer optical information medium having at least two information recording layers.

[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.

A multilayer optical information medium (hereinafter also referred to as a multilayer medium) may have a structure in which a plurality of information recording layers are laminated with a transparent intermediate layer made of a transparent resin sandwiched therebetween, as shown in the above-mentioned publications. It is common. Specifically, a first information recording layer is formed on a substrate, a transparent intermediate layer having an uneven pattern on the surface is formed thereon, and a second information recording layer is formed thereon, The uneven pattern is second
Is transferred to the information recording layer. As the uneven pattern,
For example, prepits and grooves (guide grooves) that hold data, tracking information, address information, and the like can be given. In forming the concavo-convex pattern, the resin layer is pressed by a stamper as described in the above-mentioned publications.
It is common to use the P (Photo Polymerization) method.

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 transparent intermediate layer provided between the recording layers is required to have a uniform thickness. Further, if the thickness of the transparent intermediate layer is large, it is difficult for the stamper to uniformly press the transparent intermediate layer when the uneven pattern is transferred by pressing with the stamper, and as a result, transfer defects are likely to occur. Further, when the transparent intermediate layer is composed of an active energy ray curable resin such as an ultraviolet curable resin, if the thickness of the transparent intermediate layer is large, uneven curing is likely to occur when the transparent intermediate layer is cured. Also tends to cause transfer defects.

Further, even if the transfer of the concave-convex pattern from the stamper to the transparent intermediate layer is accurate at the time of forming the transparent intermediate layer, if the stamper is difficult to peel off from the transparent intermediate layer,
That is, if the releasability is poor, a part of the transparent intermediate layer is peeled off together with the stamper, resulting in a defect. Therefore, it is required that the stamper has good releasability from the resin forming the transparent intermediate layer. When the transparent intermediate layer is made of, for example, an ultraviolet curable resin and the transparent intermediate layer is formed on the information recording layer opaque to ultraviolet rays, the transparent intermediate layer is irradiated with ultraviolet rays for curing through the stamper. Therefore, the stamper must be made of a material that is transparent to ultraviolet rays.

In the usual spin coating method, the resin is supplied to the surface of the substrate fixed to the rotary table, the substrate is rotated, and the resin is spread by the centrifugal force. Since the substrate has a central hole that is used when it is loaded into the optical disk drive, it is not possible to supply the resin to the center of rotation (center of the substrate), but to supply it annularly at an equal distance from the center of rotation. become. However, as the resin supply position is farther from the center of rotation, the thickness of the resin layer becomes thicker in the disk outer peripheral portion than in the disk inner peripheral portion. That is, the thickness unevenness in the radial direction of the transparent intermediate layer becomes large. In a multi-layer information medium, the number of transparent intermediate layers also increases as the number of information recording layers stacked increases, so that uneven thickness of the transparent intermediate layers is accumulated. As a result, even if the recording / reproducing beam is perpendicularly incident on the substrate at the outer peripheral portion of the disc, the recording / reproducing beam reflected on the surface of the information recording layer is not perpendicular to the substrate, and as a result, the amount of light returned to the optical pickup is increased. Will decrease. Therefore, the reproduction output is different between the inner peripheral portion and the outer peripheral portion of the disc.

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. In the usual spin coating method, after the resin is supplied to the surface of the disk-shaped substrate, the resin is spread by rotating the substrate. At that time, since the resin rises near the outer peripheral edge of the substrate due to the surface tension, the resin layer becomes thick near the outer peripheral edge of the substrate. On the other hand, according to the method described in the publication, since the resin is spread while being sandwiched between the substrate and the stamper, it is possible to prevent the resin layer from becoming thick near the outer peripheral edge of the substrate. The publication does not describe the stamper constituent material, and does not pay attention to the releasability of the stamper. Further, in the publication, ultraviolet rays are emitted through the substrate.

In Example 1 of Japanese Patent Laid-Open No. 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.

[0011]

SUMMARY OF THE INVENTION The present invention is a multilayer optical information medium in which a plurality of information recording layers are laminated with a transparent intermediate layer made of a resin, and an uneven pattern for holding information is present on the surface of the transparent intermediate layer. The objective of the present invention is to form the transparent intermediate layer to have a uniform thickness and to accurately transfer the master pattern of the concave-convex pattern, which the stamper has, to the transparent intermediate layer.

[0012]

The above objects are achieved by the present invention described in (1) to (11) below. (1) A plurality of information recording layers each having a concavo-convex pattern are laminated on a disc-shaped substrate, and a transparent intermediate layer through which a recording / reproducing beam can pass is present between adjacent information recording layers. A method for manufacturing an optical information medium containing a resin cured by active energy rays, comprising: a substrate having at least one information recording layer formed thereon; and a disc having a master pattern of the concavo-convex pattern. Each of the stampers having a circular shape is used as an object to be coated, and by rotating one of the objects to be coated, a coating solution containing a resin is spread on the surface of the one object to be coated to form a first resin layer. First coating step, and after supplying a coating liquid containing a resin to the surface of the first resin layer and / or the surface of the other coating target, the one coating target and the other coating target Facing the body In other words, the coating liquid is brought into contact with both the first resin layer and the other object to be coated, and then the one object to be coated and the other object to be coated are rotated together. To spread the coating liquid to form a second resin layer, and a resin laminate composed of the first resin layer and the second resin layer is applied to the one coating target and the other coating target. A second coating step in which the resin laminate is sandwiched between the coating body and a curing step of forming the transparent intermediate layer by irradiating the resin laminate with an active energy ray to cure the resin laminate; A method of manufacturing an optical information medium, comprising a peeling step of peeling from a transparent intermediate layer and a laminating step of forming another information recording layer on the transparent intermediate layer. (2) The method for producing an optical information medium according to (1), wherein in the first coating step, the first resin layer is incompletely or completely cured by irradiation with active energy rays. (3) In the first coating step, after forming the first resin layer, the active resin layer is irradiated with active energy rays while the rotation speed of the one of the objects to be coated is reduced, whereby the first resin layer is formed. The method for producing an optical information medium according to the above (1), wherein the resin is incompletely or completely cured. (4) In the first coating step, the one object to be coated has a central hole, and a disc portion for closing the central hole and a support integrated at the center of the disc portion. A closing means having a shaft is prepared, and the central hole is closed by the disk portion of the closing means, and the coating liquid is supplied to the outer peripheral surface of the support shaft, and then one of the objects to be coated is Manufacturing the optical information medium according to any one of the above (1) to (3), wherein the coating liquid is spread on the one object to be coated to form the first resin layer by rotating together with the closing means. Method. (5) The method for manufacturing an optical information medium according to any one of (1) to (4), wherein the stamper has a thickness of 0.3 to 1.8 mm. (6) The information recording layer has an information recording area, and the transparent intermediate layer is formed so that the average thickness on the information recording area is 5 to 50 μm.
1. A method for manufacturing an optical information medium according to any one of 1. (7) The average thickness on the information recording area is 0.
The method for manufacturing an optical information medium according to (6) above, wherein the second resin layer is formed so as to have a thickness of 5 μm or more and 40% or less of the thickness of the resin laminate. (8) In the second coating step, the coating liquid is brought into contact with both the first resin layer and the other object to be coated in a reduced pressure atmosphere (1) to (7).
1. A method for manufacturing an optical information medium according to any one of 1. (9) At the time of forming the first resin layer and / or when forming the second resin layer, at least a part of the coating liquid protruding from the outer peripheral edge of the body to be coated is scraped off. The method for manufacturing an optical information medium according to any one of 1) to 8). (10) The method for manufacturing an optical information medium according to any one of (1) to (9), wherein the stamper is made of a resin that transmits the active energy rays and the stamper is disposable. (11) As the stamper, at least the surface on which the matrix pattern is formed is made of a polyolefin resin or a fluororesin, and in the curing step, the resin laminate is irradiated with active energy rays through the stamper. A method for manufacturing an optical information medium according to any one of (1) to (10) above.

[0013]

In the present invention, in the first coating step, as shown in FIG. 5, the surface of one coated object 11 composed of the substrate SB and the first information recording layer IL-1 is spin-coated. Thus, the first resin layer RL-1 is formed.

Next, in the second coating step, as shown in FIG. 9, the first resin layer RL- is formed between the other coated body 12 made of the stamper 100 and the one coated body 11. 1 and the coating liquid 500 are sandwiched, both the coated objects 11 and 12 are rotated together, so that the coating liquid 50
0 is spread to form the second resin layer RL-2 shown in FIG. Thereby, between the two objects 11 and 12 to be coated,
A resin laminated body RL including the first resin layer RL-1 and the second resin layer RL-2 is formed.

Next, in the curing step, the resin laminated body RL is irradiated with active energy rays such as ultraviolet rays to be cured to form a transparent intermediate layer TL.

Next, in the peeling step, as shown in FIG. 12, the stamper 100 is peeled from the transparent intermediate layer TL.

Next, in the laminating step, as shown in FIG. 13, the second information recording layer IL- is formed on the transparent intermediate layer TL.
Form 2.

According to the method disclosed in the above-mentioned Japanese Patent Laid-Open No. 9-161329, when forming the transparent intermediate layer, the substrate and the stamper are rotated integrally with the liquid resin sandwiched between the substrate and the stamper. Thus, a step of spreading the liquid resin between the substrate and the stamper is provided. This step is similar to the second coating step in the present invention. However, in the same publication, almost the entire resin layer that becomes the transparent intermediate layer is formed by the step of spreading the liquid resin between the substrate and the stamper, whereas in the second coating step of the present invention, curing is performed by curing. Only a part (second resin layer RL-2) of the resin laminated body RL to be the transparent intermediate layer TL is formed. In the method of spreading the resin between the substrate and the stamper, it is possible to prevent the resin from rising due to surface tension near the outer peripheral edge of the resin layer, but the thickness of the resin layer increases from the inner peripheral portion to the outer peripheral portion. It cannot be completely suppressed. The amount of increase in thickness becomes smaller as the resin layer becomes thinner. Also, the first
Also in the normal spin coating method used in the coating step, the thickness of the resin layer increases from the inner peripheral portion toward the outer peripheral portion, and the amount of increase in thickness becomes smaller as the resin layer becomes thinner.

Therefore, in the present invention in which the resin layers are formed separately, the variation in the thickness of each resin layer in the radial direction is small, and the sum of these variation in thickness, that is, the variation in the thickness of the resin laminate RL is small. The amount is smaller than the amount of thickness variation in the resin layer of the same thickness formed by one spin coating. Further, in order to form a thin resin layer, a low-viscosity coating liquid is used, and the coating liquid is spread by rotating the object to be coated at high speed for a long time. Therefore, even if air bubbles are mixed in the coating liquid, they easily come off during spreading. Therefore, in the present invention, it is difficult for bubbles to enter the transparent intermediate layer TL.

In the first coating step, the first resin layer RL-
It is preferred to cure 1 incompletely or completely. The following effects are realized by this curing.

The first effect is to improve the mechanical properties of the medium. This effect is realized when the first resin layer RL-1 is imperfectly cured in the first coating step. In this case, the first resin layer RL that was incompletely cured in the first coating step
-1 is completely cured in the curing step. That is, the curing is divided into two. In this case, the amount of shrinkage of the resin layer is smaller than that in the case where the resin layer is completely cured at once. Therefore, the mechanical properties of the medium are good.

Next, the second effect will be described. When the first resin layer RL-1 is not cured in the first coating step, the first resin layer RL-1 has fluidity, and therefore the first resin layer RL- is formed by the second coating step. There is a case where flow occurs in No. 1 and uneven thickness occurs. This problem can be solved by incompletely or completely curing the first resin layer RL-1 in the first coating step.

Next, the third effect will be described. At least part of the second coating step is performed in order to prevent air bubbles from being mixed between the first resin layer RL-1 and the stamper 100.
As described below, it is preferable to carry out under a reduced pressure atmosphere. However, at this time, if the first resin layer RL-1 is not cured, the volatile components contained in the first resin layer RL-1 are easily volatilized in the reduced pressure atmosphere. Therefore, air bubbles made of the volatile component are likely to be mixed into the resin laminated body RL. This problem can be solved if the first resin layer RL-1 is incompletely or completely cured in the first coating step.
Further, since it is possible to further increase the degree of pressure reduction, it is possible to almost completely prevent bubbles from being mixed with a gas other than the volatile component.

Incompletely curing the first resin layer RL-1 in the first coating step is also effective when both resin layers are made of different materials. in this case,
The second resin layer R without completely curing the first resin layer RL-1
When L-2 is laminated, the mixing of both resin layers proceeds, so that the effect of forming both resin layers from different materials is reduced. On the other hand, when the first resin layer RL-1 is completely cured and then the second resin layer RL-2 is laminated, the interface between both resin layers becomes clear, so that recording /
As a result of the higher reflectance of the reproducing beam, the recording / reproducing characteristics are adversely affected. On the other hand, if the second resin layer RL-2 is laminated on the incompletely cured first resin layer RL-1,
These problems can be solved.

In the first coating step, the first resin layer RL
When -1 is incompletely or completely cured, as shown in FIG. 5, after rotating the object to be coated 11 to form the first resin layer RL-1 by spin coating, as shown in FIG. Moreover, it is preferable to irradiate the active energy ray while reducing the rotation speed of the object to be coated 11. At the time of spin coating, the outer peripheral portion of the spread resin layer tends to rise,
By irradiating the active energy ray while gradually lowering the rotation of the object to be coated 11, the ridge can be suppressed. Further, since the centrifugal force acting on the resin layer during curing is smoothly reduced, the resin layer is less likely to have uneven thickness and physical properties.

When performing spin coating in the first coating step, it is preferable to use the closing means 300 having the shape shown in FIG. The closing means 300 includes a disc portion 301.
And the support shaft 30 integrated in the center of the disc portion 301.
2 and. As shown in FIG. 4, this closing means 300
The central hole CH of the substrate SB is closed with a coating liquid 50
If 0 is supplied to the outer peripheral surface of the support shaft 302 to perform spin coating, the coating liquid 500 can be supplied near the center of rotation.
The thickness unevenness of the first resin layer RL-1 in the radial direction can be further suppressed, and as a result, the thickness unevenness of the transparent intermediate layer can be further suppressed. Moreover, since the closing means 300 can be operated by gripping the support shaft 302, the closing means 300 can be easily handled in the medium manufacturing process, and in particular, the closing means 300 can be easily removed after spin coating.

The stamper 100 has a thickness of 0.3 to 1.8.
mm is preferred. Since it is difficult to manufacture a stamper without any deformation such as warpage, the stamper has a deformation. In the second application step, as shown in FIG. 10, the stamper 10 is used when forming the second resin layer RL-2.
Rotate 0. The centrifugal force generated by this rotation works to correct the warp of the stamper 100. At this time, if the stamper 100 has a relatively small thickness of 0.3 to 1.8 mm, the warp of the stamper 100 can be effectively corrected by the centrifugal force.

The first resin layer R on the information recording area
The thickness of L-1 and the average thickness of the second resin layer RL-2 are preferably set so that the average thickness of the transparent intermediate layer TL on the information recording area is 5 to 50 μm. However, when the closing means 300 is used when forming the first resin layer RL-1, it is possible to considerably reduce the thickness variation of the first resin layer RL-1. Therefore, in that case, the thinner the second resin layer RL-2 is, the smaller the variation in the thickness of the resin laminated body RL becomes. In this case, the average thickness of the second resin layer RL-2 on the information recording area is preferably 0.5 μm or more and 40% or less of the thickness of the resin laminate RL. Thereby, it is possible to reduce the thickness variation of the resin laminate RL and prevent the bubbles from being mixed into the second resin layer RL-2 in which the bubbles are easily mixed.

In the second coating step, it is preferable that the first resin layer RL-1 and the coating liquid 500 are sandwiched between the objects to be coated 11, 12 in a reduced pressure atmosphere. As a result, it is possible to prevent bubbles from being mixed into the transparent intermediate layer TL, and to suppress adverse effects on the recording / reproducing characteristics.

When the first resin layer RL-1 is formed and / or the second resin layer RL-2 is formed, the coating liquid is spread by centrifugal force, so that the outer peripheral edge of the object to be coated is The coating solution overflows from the. In the present invention, it is preferable to scrape off at least a part of the coating liquid that has overflowed. As a result, the amount of the coating liquid protruding from the outer peripheral edge of the substrate SB is made uniform over the entire circumferential direction. Therefore, it is not necessary to completely scrape the resin layer after the resin layer is completely cured to form the transparent intermediate layer. When the first resin layer RL-1 is incompletely or completely cured, this scraping is performed before the curing.

The stamper 100 is preferably made of a resin that can transmit active energy rays for curing the resin laminate RL. As a result, even if the first information recording layer IL-1 existing between the substrate SB and the resin laminated body RL is opaque to the active energy rays, the stamper 1
It is possible to irradiate the resin laminated body RL with the active energy ray through 00 to cure the resin laminated body RL. Also, the stamper 100
If the active energy ray is irradiated through the resin laminate R
The hardening of L begins in the area in contact with the stamper 100. Therefore, the releasability of the stamper 100 is good.

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.

The stamper used in the present invention is preferably composed entirely of a polyolefin resin or a fluororesin, or at least the surface on which the matrix pattern is formed is composed of a polyolefin resin or a fluororesin. Such a stamper has good releasability from the transparent intermediate layer made of a cured product of the active energy ray-curable resin. In addition, the polyolefin resin and the fluororesin have a high UV absorptivity, and thus have a low UV absorptivity with respect to other resins such as polycarbonate as well as UV curable resins whose transmittance is low. taller than. Therefore, when ultraviolet rays are irradiated through such a stamper, the resin laminate RL can be irradiated with ultraviolet rays of sufficient intensity through the stamper, so that a sufficiently cured transparent intermediate layer TL is obtained.

In the first coating step of the present invention,
The object to be coated on which the first resin layer RL-1 is formed may be the stamper 100. Even in that case, the effects of the present invention are similarly realized.

[0035]

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

Optical Information Medium The optical information medium to which the present invention is applied has a structure in which at least two information recording layers are laminated. 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 this specification includes an information recording layer which has a plurality of information recording layers and which is recorded or reproduced by a recording / reproducing beam transmitted through other information recording layers. It is a medium. A transparent intermediate layer through which a recording / reproducing beam can pass is present between adjacent information recording layers.

FIG. 1 shows an example of the structure of a multi-layer medium manufactured according to the present invention. In the medium shown in FIG. 1, a first information recording layer IL-1 is provided on a disc-shaped substrate SB, and second information recording is performed on the information recording layer IL-1 via a transparent intermediate layer TL. The layer IL-2 is laminated. In the first information recording layer IL-1 and the second information recording layer IL-2,
Concavo-convex patterns composed of grooves and pre-pits are formed respectively. A protective layer PL is formed on the second information recording layer IL-2. The configuration of each part of this medium will be described below.

Substrate SB, Protective Layer PL In the medium shown in FIG. 1, the recording / reproducing beam is incident not from the substrate SB side but from the protective layer PL side. Therefore, the substrate SB does not need to 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. The substrate SB may be made of resin like the substrate of a normal optical information medium. In that case, the concavo-convex pattern on the surface of the substrate SB necessary for the first information recording layer IL-1 can be formed by injection molding. However, by forming the uneven pattern by the 2P method on the surface of a rigid substrate such as a glass plate, a resin plate, or a metal plate,
It may be the substrate SB.

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 adhesives, or a transparent resin is applied to the protective layer PL. It may be PL.

In the medium having the structure shown in FIG. 1, the recording / reproducing beam is transmitted through the substrate SB to the information recording layer IL-.
1, it may be configured to enter the IL-2.

Information Recording Layer On the information recording layers IL-1 and IL-2, a concavo-convex pattern such as prepits and grooves is formed. This uneven pattern is formed by transferring the uneven pattern formed on the surface of the transparent intermediate layer TL. However, the information recording layer IL that is deepest in the recording / reproducing beam from the incident side.
-1 is formed by transferring the concavo-convex pattern provided on the substrate SB. The information recording layer includes at least a read-only layer or a recording layer.

Since the read-only layer needs to reflect a part of the reproduction beam (information recording layer IL-2) or a large part (information recording layer IL-1), it is a 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. In addition, the information recording layer IL-1 existing at the deepest side when viewed from the recording / reproducing beam incident side is normally the reflective layer, the dielectric layer, the phase change recording layer, and the dielectric layer in this order from the bottom in FIG. 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.

The composition of the phase change recording material used in the present invention is not particularly limited, but a material containing at least Sb and Te is preferable. Since the recording layer made of only Sb and Te has a low crystallization temperature of about 130 ° C. and insufficient storage reliability, it is preferable to add other elements. In this case, the additional element is element M (element M is In,
Ag, Au, Bi, Se, Al, P, Ge, H, Si,
C, V, W, Ta, Zn, Ti, Ce, Tb, Sn, P
which is at least one element selected from b, Pd and Y). Of these, Ge is particularly preferable because it has a high effect of improving storage reliability.

When the atomic ratio of the constituent elements of the recording layer is represented by the formula I Sb _a Te _b M _c and a + b + c = 1, preferably a = 0.2 to 0.85 and b = 0.1 to 0.6. , C = 0 to 0.25, and more preferably c = 0.01 to 0.25. If the Sb content is too low, the crystallization speed will not be sufficiently high, and overwriting will be difficult. On the other hand, if the Sb content is too high, the crystallization speed becomes too fast, making it difficult to form amorphous recording marks.
If the M content is too small, the effect due to the addition of M becomes insufficient, and if the M content is too large, the change in reflectance due to the phase change becomes small and it is difficult to obtain a sufficient degree of modulation. If the Te content is too low, it becomes difficult to form an amorphous state and it becomes difficult to form a recording mark. On the other hand, if the Te content is too high, the crystallization speed becomes slow and overwriting becomes difficult.

In the multi-layer medium, since a plurality of recording layers are overlapped as described above, the light quantity loss of the recording / reproducing beam becomes large. Therefore, it is preferable that the recording layer is as thin as possible within the range where the function as the recording layer is not impaired. However, if it is too thin, the function as a recording layer is impaired. Therefore, the thickness of the recording layer is preferably 2 to 50 nm, more preferably 4 to 20 nm.

When the phase change type recording layer is used, the information recording layer preferably has a structure in which the recording layer is sandwiched between a pair of dielectric layers as described above. In this structure, the recording layer and each dielectric layer are preferably formed by a sputtering method. As the dielectric used for the dielectric layer, for example, S
Various compounds containing at least one metal component selected from i, Ge, Zn, Al, rare earth elements and the like are preferable.
The compound is preferably an oxide, a nitride, a sulfide or a fluoride, and a mixture containing two or more of these compounds can also be used. The thickness of each dielectric layer is 10
It is preferably 500 nm.

Transparent Intermediate Layer The transparent intermediate layer TL is a cured product of an active energy ray curable resin such as an ultraviolet curable resin and is made of a material having a high transmittance for a recording / reproducing beam.

The thickness of the transparent intermediate layer is not particularly limited and may be set so that the crosstalk between the adjacent information recording layers falls within an allowable range, but it is preferably 5 to 50 μm, more preferably 10 to 50 μm. is there. If the transparent intermediate layer is too thin, the crosstalk will be too large. On the other hand, if the transparent intermediate layer is too thick, the thickness unevenness tends to increase, the internal stress tends to increase, and the total thickness of the medium also increases. The average thickness means the arithmetic average of the maximum thickness and the minimum thickness on the information recording area. In the present specification, the information recording area is an area in which pre-pits or grooves are formed and information can be held (recorded) in a read-only information recording layer or an additionally recordable or rewritable information recording layer. That is, it is a recordable track existing area. The recordable track includes a track for recording data (normal recording track) and a track for trial writing.

As described above, when the transparent intermediate layer is formed by the usual spin coating method, the thickness unevenness in the radial direction of the transparent intermediate layer becomes large, so that the reproduction output differs between the inner peripheral portion and the outer peripheral portion. In addition, unevenness in transfer is likely to occur when the pattern is transferred from the stamper. On the information recording area, the difference between the maximum thickness and the minimum thickness of the transparent intermediate layer is preferably 10 μm or less, more preferably 6 μm or less, and further preferably 3 μm or less. In the present invention, since the thickness unevenness of the transparent intermediate layer can be reduced in this way, it is possible to suppress the reproduction output fluctuation and the occurrence of transfer defects.

The smaller the difference between the maximum thickness and the minimum thickness of the transparent intermediate layer is, the more preferable it is. However, when the spin coating method is used, it is difficult to reduce the difference to zero. Further, if the difference is sufficiently small, the influence on the reproduction output fluctuation is small. Therefore, it is not necessary to reduce the above difference to less than 1 μm.

Manufacturing Method Next, the case where the manufacturing method of the present invention is applied to the manufacture of the medium shown in FIG. 1 will be described. In the manufacturing method of the present invention,
A first coating process, a second coating process, a curing process, a peeling process, and a laminating process described below are provided.

In the following, a case where an ultraviolet curable resin is used as the active energy ray curable resin will be described as an example, but in addition to this, a resin curable by another active energy ray such as an electron beam can also be used. is there.

First Coating Step In the first coating step, the substrate on which at least one information recording layer is formed and the disk-shaped stamper having the master pattern are used as coating objects. Then, the first resin layer is formed on the surface of one of the objects to be coated by spin coating. In the following, as shown in FIG. 7, a case where the substrate SB on which the first information recording layer IL-1 is formed is used as the one coated object 11 will be described as an example.

In this step, first, as shown in FIGS. 2 and 3, the substrate SB having the central hole CH is placed on the turntable 200. The first information recording layer IL-1 is already formed on the substrate SB. The center hole CH of the substrate SB is fixed by being fitted into the annular protrusion 201 of the turntable 200. Although these figures are sectional views, only the end faces appearing in the section are shown, and the illustration in the depth direction is omitted. The same applies to the sectional views thereafter.

Then, the central hole CH is closed by the closing means 300.
Close up. The closing means 300 includes a disk portion 301 for closing the central hole CH and a support shaft 30 integrated in the center thereof.
2 and a convex portion 303 integrated with the disc portion 301 on the side facing the central hole CH. By fitting the convex portion 303 to the inner peripheral portion of the protrusion 201, the closing means 30
0 is fixed to the turntable 200 and the substrate SB
And the closing means 300 can be positioned. However, the turntable 2 of the substrate SB and the closing means 300
The method of fixing to 00 is not particularly limited, and for example, the substrate SB
And the closing means 300 are fitted, the closing means 300
May be fitted to the turntable 200.

Next, as shown in FIG. 4, the coating liquid 500 made of resin or resin solution is discharged from the nozzle 4 serving as a discharging means.
It is discharged from 00 and supplied to the outer peripheral surface of the support shaft 302.
At this time, the rotary table 200 is rotated at a relatively low speed, preferably 20 to 100 rpm, so that the coating liquid 500 is evenly spread on the disk portion 301.

Then, as shown in FIG. 5, the turntable 200 is rotated at a relatively high speed to apply the coating liquid 50.
Spread 0. As a result, the first resin layer RL-1 is formed on the substrate SB.

The spreading condition of the coating liquid is not particularly limited. It is known that the thickness of a coating film is theoretically proportional to the square root of the viscosity of the coating liquid when the conditions other than the viscosity of the coating liquid are the same in the spin coating method. On the other hand, the higher the rotation speed and the longer the rotation time, the thinner the coating film. Therefore, the rotation speed and the rotation time during spin coating may be appropriately determined according to the viscosity of the coating liquid so that the first resin layer RL-1 has a predetermined thickness.

As described above, in the first coating step, it is preferable that the first resin layer RL-1 is incompletely or completely cured by irradiation with ultraviolet rays.

Upon curing, after forming the first resin layer RL-1, the blocking means 300 may be removed from the substrate SB and then irradiated with ultraviolet rays. However, in the present invention, FIG.
After forming the first resin layer RL-1 in step 2, it is preferable to irradiate with ultraviolet rays in the process of decelerating the rotation speed of the substrate SB in spin coating, as shown in FIG. It is preferable that the ultraviolet irradiation be started from the start of deceleration until 30% of the deceleration time elapses and continued at least until 80% of the deceleration time elapses. If the start of irradiation is delayed, the resin layer tends to rise on the outer peripheral side.
In addition, if the irradiation start is delayed, the resin does not cure to a relatively low rotation range, and as a result, the centrifugal force becomes weak in the non-cured state, so that the protrusion on the outer peripheral portion tends to increase.
If the timing of stopping the ultraviolet irradiation is too early, the resin layer is likely to be uneven. The decrease profile of the rotation speed of the substrate SB is not particularly limited as long as the rotation speed decrease amount (deceleration rate) per unit time is constant or smoothly changes from the initial stage to the stop. That is,
The deceleration rate may be constant, or may be gradually decreased or gradually increased, but it is usually preferable to set it to be constant.

Even when the resin layer is incompletely cured, it is preferable that the resin layer is cured to such an extent that the resin layer has substantially no fluidity. UV irradiation amount therefor varies depending the resin layer-forming material, preferably 10 mJ / cm ² or more, more preferably 30 mJ / cm ² or more. Further, in order to realize the effect of incomplete curing, the irradiation amount is preferably such that tackiness remains in the resin layer, specifically, preferably 200 mJ / cm ² or less, more preferably 10 mJ / cm ² or less.
It is 0 mJ / cm ² or less.

While decelerating the rotation speed, the first resin layer RL
In the method of hardening -1, the blocking means 300 irradiates with ultraviolet rays in a state of being filled in the substrate SB. At this time, when the coating liquid on the surface of the closing means 300 is also irradiated with ultraviolet rays, when the closing means 300 is removed from the substrate SB after hardening, particularly when complete curing is performed, the first resin layer RL-1. There is a possibility that burrs may be generated on the inner peripheral edge of the burrs and fragments of burrs may scatter, which is not preferable. In order to prevent the occurrence of such burrs, it is preferable to irradiate ultraviolet rays except in the vicinity of the closing means 300. That is, it is preferable to control the irradiation range such that the inner diameter of the ultraviolet irradiation region is slightly larger than the outer diameter of the disc portion 301 of the closing means 300. Further, when the coating liquid is spread, the coating liquid is radially scattered from the outer peripheral edge of the substrate SB. However, when the coating liquid is also irradiated with ultraviolet rays, the scattered coating liquid is cured while being radially extended from the outer peripheral edge of the substrate. Cheap. In order to prevent this, it is preferable to control the irradiation range so that the outer peripheral edge of the ultraviolet irradiation region substantially coincides with the outer peripheral edge of the substrate SB.

The irradiation range is, for example, the ultraviolet source and the substrate SB.
It can be controlled by arranging a mask having a predetermined shape between and and blocking ultraviolet rays. It can also be controlled by using a projection exposure machine capable of precise pattern irradiation. Further, other than the projection exposure machine, any type of ultraviolet irradiation device capable of selectively irradiating a specific area may be used. Examples of such a device include a spot UV irradiation device and multi-light manufactured by Ushio Electric Co., Ltd. In the spot UV irradiation device, a lens can be attached to the tip of the optical fiber unit to adjust the shape of the irradiation area. For example, if the irradiation area is rectangular and irradiation is performed while rotating the substrate SB, the surface of the first resin layer RL-1 can be irradiated in a ring shape. When using the multi-light, the mask is preferably used together.

Before the first resin layer RL-1 is cured, it is preferable to scrape off at least part of the coating liquid protruding from the outer peripheral edge of the substrate SB during spreading, as described above. Specifically, it is preferable to use a shaving means having a thin plate-like portion such as a knife blade, and bring it close to the outer peripheral side surface of the substrate SB to shave off the coating liquid.

Next, by separating the closing means 300 from the substrate SB, as shown in FIG. 7, the first resin layer RL-
A coated body 11 having 1 on the surface is obtained.

Second Coating Step In the second coating step, first, as shown in FIG. 8, a coating liquid 500 made of a resin or a resin solution is discharged from a nozzle 400 which is a discharging means to form a first resin. Supply near the inner periphery of the layer RL-1. At this time, the rotary table 200 is rotated at least once at a relatively low speed to form an annular pool of the coating liquid 500.

The ultraviolet curable resin contained in the coating liquid 500 is preferably the same as the ultraviolet curable resin contained in the coating liquid used in the first coating step, but a different resin may be used if necessary. You may choose.

Then, as shown in FIG.
0 (body 12 to be coated) is brought into contact with the coating liquid 500 and pressed. At this time, the coating liquid 5 is applied by the weight of the stamper 100.
00 may be pressed, or the coating liquid 500 may be pressed by applying a load to the stamper 100 from the outside.
In order to prevent the deformation of 00, the stamper 100 is preferably pressed by its own weight.

Although the coating liquid 500 is supplied only on the first resin layer RL-1 in FIG. 9, the coating liquid 500 is not shown.
May be supplied near the inner peripheral portion of the stamper 100, or may be supplied to both the first resin layer RL-1 and the stamper 100.

Then, as shown in FIG. 10, the substrate SB is rotated integrally with the stamper 100 at a relatively high speed, so that the coating liquid 50 is applied between the substrate SB and the stamper 100.
0 is spread to form the second resin layer RL-2. Thereby, the first resin layer RL-1 and the second resin layer RL-2
The resin laminated body RL consisting of and is sandwiched between the one coated body 11 and the other coated body 12.

The rotation speed and the rotation time for spreading the coating liquid are not particularly limited, and the master pattern on the surface of the stamper 100 can be accurately transferred to the second resin layer RL-2, and So that the resin layer RL-2 has a predetermined thickness,
Although it may be appropriately determined according to the viscosity of the coating liquid, the viscosity of the coating liquid is usually 50 to 1000 cP and the rotation speed is 500
It is preferable to set the rotation speed to ˜6000 rpm and the rotation time to 1 to 10 seconds.

Second resin layer R on the information recording area
The average thickness of L-2 is preferably 0.5 μm or more, and the same applies to the first resin layer RL-1. It is difficult to uniformly form a resin layer having a thickness of less than 0.5 μm, and if the resin layer is too thin, the adhesive strength will be insufficient. In addition, as described above, the first resin layer RL-
When the closing means 300 is used for forming 1, the average thickness of the second resin layer RL-2 is preferably 0.5 μm or more and 40% or less of the thickness of the resin laminate RL. Thereby, the thickness variation of the resin laminated body RL can be reduced and the second resin layer RL-2 in which air bubbles are easily mixed is easily formed.
It is possible to prevent bubbles from being mixed in. The average thickness in this case means the arithmetic mean of the maximum thickness and the minimum thickness on the information recording area.

Contact between the stamper 100 and the coating liquid 500 is preferably performed in a reduced pressure atmosphere. The pressure of the reduced pressure atmosphere is preferably 30 kPa or less, more preferably 10 kPa or less. Thereby, the second resin layer RL-
It is possible to prevent air bubbles from being mixed into 2. In addition,
It is not necessary to spread the coating liquid 500 in a reduced pressure atmosphere,
It may be performed under a pressurized atmosphere.

After forming the second resin layer RL-2, the coating liquid protruding from the outer peripheral edge of the substrate SB and the outer peripheral edge of the stamper 100 is scraped off in the same manner as in the first coating step when the rotational speed is reduced. May be.

Curing Step, Peeling Step, Laminating Step In the curing step, as shown in FIG. 11, the resin laminated body RL is completely cured by irradiation with ultraviolet rays through the stamper 100 to form the transparent intermediate layer TL. The substrate SB
You may irradiate with ultraviolet rays while rotating.

Next, as shown in FIG. 12, the transparent intermediate layer T
The stamper 100 is peeled off from L. In order to easily perform this peeling, it is necessary to cure the transparent intermediate layer TL almost completely. If the curing is insufficient, the transparent intermediate layer TL still has adhesiveness, and thus the stamper 100 is difficult to peel off. Further, if the curing is insufficient, the mechanical strength of the transparent intermediate layer TL becomes insufficient, so that the transparent intermediate layer TL may be damaged when the stamper 100 is peeled off. In order to sufficiently cure the transparent intermediate layer TL, the irradiation amount of ultraviolet rays is 1 J /
It is preferably at least cm ² .

Next, as shown in FIG.
The second information recording layer IL-2 is formed on the surface of the transparent intermediate layer TL exposed by the peeling of No. 0 by the sputtering method or the coating method.

Closing Means The closing means used in the coating step will be described. Although the main effect of the present invention is realized even when the closing means is not used, the aforementioned effect is realized by using the closing means.

The closing means used in the present invention is not limited to the structure shown in FIG. 2 and may be any means having a disc portion and a support shaft. The closing means 300 shown in FIG. 2 has a circular truncated cone portion 3
01 and a cylindrical support shaft 302, but other than this, for example, the closing means having the configurations shown in FIGS. 14 (A) to 14 (D) can also be used.

The closing means shown in FIG. 14A has a circular truncated cone-shaped disc portion 301 whose lower surface is hollowed out, and an inverted circular truncated cone-shaped support shaft 302. If the support shaft has an inverted truncated cone shape, the application start position of the application liquid can be brought closer to the center of the disc portion 301, so that the unevenness of the thickness of the coating film can be further reduced. Moreover, unlike the case where the entire support shaft 302 is made thin, it is possible to suppress a decrease in the mechanical strength of the support shaft 302. Further, when the support shaft 302 is gripped by a chuck or the like, it is difficult for the support shaft 302 to fall, which is advantageous when attaching and detaching the closing means and when carrying it. The entire support shaft 302 does not have to have an inverted truncated cone shape. That is, it is sufficient that at least a part of the support shaft 302 has a truncated cone shape whose diameter gradually decreases toward the disc portion 301, and the diameter of the support shaft does not increase in a region closer to the disc portion.

The closing means shown in FIG.
The cross-sectional shape of 01 is different from that in FIG. Disk part 30
In order to spread the coating liquid evenly on the surface of No. 1, it is preferable that the thickness of the disk portion 301 gradually decreases toward the outer peripheral portion.
In that case, in the cross section of the disk portion 301, the shape of the upper edge on which the coating liquid is spread may be linear as shown in FIG. 14 (A), or as shown in FIG. 14 (B). It may be curved. Further, as shown in FIG. 14C, the outer circumference of the disc portion 301 may be a vertical surface. However, in FIG.
In (C), the thickness t on the outer periphery of the disc portion 301 is
It is preferably 0.4 mm or less. If the thickness t is too large, it becomes difficult to apply the resin layer evenly. Further, as shown in FIG. 14D, the disc portion 301 may have a uniform thickness.

In the closing means, the minimum diameter of the support shaft 302 near the disc portion 301 is preferably less than 4 mm,
It is more preferably 2 mm or less. If the diameter of the support shaft 302 in the vicinity of the disk portion 301 is too large, the application start position will be separated from the center of the disk portion 301, and the uneven thickness of the resin layer in the radial direction will increase. However, if the diameter of the support shaft 302 in the vicinity of the disc portion 301 is too small, the mechanical strength of the support shaft 302 becomes insufficient, so the minimum diameter is preferably 0.5 mm or more, more preferably 0.7 mm or more. Is. The length of the support shaft 302 is not particularly limited, and may be appropriately determined so as to facilitate the supply of the coating liquid to the outer peripheral surface of the support shaft 302 and the ease of handling when gripping. Preferably 5-100
mm, more preferably 10 to 30 mm. Support shaft 302
If is too short, it becomes difficult to supply the coating liquid to the outer peripheral surface, and it becomes difficult to grip. On the other hand, if the support shaft 302 is too long, the handling becomes troublesome.

The diameter of the disk portion 301 is larger than the diameter of the central hole CH of the substrate SB, and the first information recording layer IL
It should be smaller than the inner diameter of -1. However, the coating liquid 50
Since 0 may go around the lower surface of the disk portion 301 and contaminate the inner peripheral surface of the substrate SB, the diameter of the disk portion 301 is preferably 4 mm or more, particularly 8 mm or more larger than the diameter of the central hole CH. . Further, when the disc portion 301 is removed, the shape of the resin layer in the vicinity thereof is likely to be disturbed, so that the disc portion 3
The diameter of 01 is 3 than the inner diameter of the first information recording layer IL-1.
It is preferable that the size is smaller than mm, especially smaller than 5 mm. The specific size varies depending on the diameter of the central hole and the inner diameter of the information recording layer, but when applied to the manufacture of an optical disc having a diameter of about 60 to 130 mm, the diameter of the disk portion 301 is usually 2
It is preferable that the thickness is in the range of 0 to 40 mm, particularly 25 to 38 mm.

The constituent material of the closing means is not particularly limited, and may be any of metal, resin, ceramic and the like, and may be a composite material using two or more of these. Also,
The disc portion 301 and the support shaft 302 may be made of different materials. However, since the mechanical strength, durability, and dimensional accuracy are good, the closing means is preferably made of metal. As the metal, for example, stainless alloy, aluminum and aluminum alloy are preferable.

The surface of the closing means 300, particularly the disc portion 301.
It is preferable that the entire surface of (1) has a lower surface tension than the coating liquid. If the surface of the blocking means 300 is hard to wet with the coating liquid, the coating liquid attached to the surface of the blocking means can be easily washed. The surface tension can be controlled by appropriately selecting the constituent material of the closing means, but it is preferable to apply a water repellent / oil repellent treatment such as Teflon (registered trademark) processing to the region where the surface tension is desired to be lowered.

By the way, although it is not a multi-layer medium, the central hole of the disk substrate is closed by a closing member such as a plate member, a disk portion, a closing plate, a cap, etc. Is known to perform spin coating (Japanese Patent Laid-Open Nos. 10-320850, 10-249264, and 10-28948).
No. 9, gazette 11-195250, gazette 11-19.
5251 publication).

However, the closing means described in each of these publications has the following problems.

The above-mentioned JP-A-10-320850, JP-A-10-249264, and JP-A-11-1952.
Japanese Patent Laid-Open No. 50 does not describe a method of removing the plate-shaped member or the cap that is the closing means after spin coating, and it is difficult to industrially utilize it.

In the above-mentioned Japanese Patent Laid-Open No. 10-289489, after spin coating, the disk portion which is the closing means is punched out or removed by adsorption with an electromagnet, and then the resin layer is cured while rotating the disk substrate. Has been done. However, when the closing means is removed by punching and electromagnet, a large acceleration is applied to the closing means, so that the resin coating film is likely to be disturbed.

The above-mentioned Japanese Patent Laid-Open No. 11-195251 describes a closing means having a structure in which a support is integrated in the center of a circular cap. The publication describes that the provision of this support facilitates attachment / detachment and positioning of the closing means. This support is a hollow cylinder having at least one hole or a plurality of rods. A resin layer is formed on the disk substrate by injecting resin into the inside of the hollow cylinder or a region surrounded by a plurality of rod-shaped bodies and then integrally rotating the disk substrate and the closing means. By using this closing means, the closing means can be easily removed. In this publication, it is described that the resin layer is cured while the disc substrate is stationary after the blocking means is separated from the disc substrate.

In this publication, the resin is caused to flow out through a hole provided in the hollow cylinder of the closing means or between the adjacent rod-shaped bodies for spin coating. Therefore, the resin is blocked by the wall (region other than the hole) of the support or the rod-shaped body. In addition, the blocked resin may flow onto the disk substrate at an unpredictable timing. Therefore, the coating film tends to be uneven. In addition, this closing means,
Since the shape of the surface in contact with the resin is complicated and the area in contact with the resin is large, it is difficult to clean the closing means. When the resin remains on the surface of the blocking means, the coating film is likely to be uneven. Further, in Table 1 of the publication, the outer diameter of the hollow cylinder is 4
The thickness variation of the coating film was investigated for the case of ~ 16 mm. From this result, the thickness variation of the coating film depends on the outer diameter of the hollow cylinder, and the larger the outer diameter, the greater the thickness variation. Recognize. That is, even if the resin is supplied to the inside of the hollow cylinder, the application start position does not coincide with the center of rotation, and the outer peripheral position of the hollow cylinder is considered to be the application start position. Considering that the viscosity of the resin is relatively high, it is difficult to make the outer diameter of the hollow cylinder less than 4 mm. Therefore, in the method described in the publication, it is necessary to make the thickness unevenness of the resin coating extremely small. Is difficult

In contrast to such a conventional closing means, the closing means 300 used in the present invention as shown in FIG.
01 is provided with a support shaft 302. Since the closing means 300 can be operated by gripping the support shaft 302, the closing means 300 can be easily handled in the medium manufacturing process, and in particular, the closing means 300 can be easily removed after spin coating.

In Japanese Patent Laid-Open No. 11-195251, the resin is blocked by the wall of the support or the rod-shaped body, so that the coating film is likely to be uneven as described above. On the other hand, in the closing means shown in FIG. 2, since the coating liquid is supplied to the outer peripheral surface of the support shaft to perform spin coating, unevenness in the coating film is unlikely to occur. Further, in the closing means shown in FIG. 2, since the resin adheres to the outer peripheral surface of the support shaft, it is easier to clean the closing means than in the above-mentioned JP-A-11-195251. Further, in JP-A-11-195251, the coating liquid is supplied into the hollow cylindrical support, so that the outer diameter of the support is reduced to secure the fluidity of the coating liquid having a relatively high viscosity. Therefore, the coating start position is relatively far from the center of rotation. On the other hand, in the closing means shown in FIG. 2, the outer diameter of the support shaft can be made significantly smaller than that in the publication, so that the uneven thickness of the coating film can be significantly reduced.

[0098] will be described preferred configurations of the stamper used in the stamper present invention.

In the present invention, since it is possible to irradiate the resin laminate RL with ultraviolet rays through the stamper 100,
It is preferable that the stamper 100 is made of a resin that can transmit ultraviolet rays, and in order to facilitate the release of the stamper 100 from the transparent intermediate layer TL, at least the surface of the stamper 100 in contact with the transparent intermediate layer TL (concavo-convex pattern The forming surface) is more preferably made of a polyolefin resin or a fluororesin. The polyolefin resin may be appropriately selected from polyethylene, polypropylene and polymethylpentene, for example. Further, as the fluororesin, for example, polytetrafluoroethylene, poly
It may be appropriately selected from (chlorotrifluoroethylene) and polyperfluoroalkenyl vinyl ether.

The method of manufacturing the stamper 100 is not particularly limited, but when the stamper is made of a polyolefin resin, it is preferably manufactured by an injection molding method. Further, when the stamper is made of a fluororesin, a manufacturing method may be appropriately selected from a pressure molding firing method, an extrusion molding method, a compression molding method, an injection molding method and the like depending on the kind of the fluororesin. The master pattern provided on the surface of the stamper 100 can be simultaneously formed at the time of molding. However, a polyolefin resin layer or a fluororesin layer having the master block pattern is formed by a 2P method on a relatively rigid substrate made of a material (resin, glass, etc.) having high permeability to active energy rays, The stamper 100 may be manufactured.

The shape and size of the stamper 100 are not particularly limited, but normally, the stamper 100 is annular like the substrate SB, and its outer diameter and inner diameter may be substantially the same as the outer diameter and inner diameter of the substrate SB, respectively. However, if the outer diameter of the stamper 100 is set to be slightly larger than the outer diameter of the substrate SB, the stamper 100 can be easily peeled from the transparent intermediate layer TL in the peeling step. The thickness of the stamper 100 is usually
It is preferably within the range of 0.3 to 3 mm. If the stamper 100 is too thin, it will be difficult to form the stamper, and it will be difficult to form a uniform master pattern over the entire surface of the stamper. On the other hand, if the stamper 100 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,
There is a deformation in the stamper. 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 resin laminated body RL, and the thickness unevenness of the resin laminated body RL becomes large.

In the second coating step, the second resin layer RL-
The stamper 100 is rotated when forming 2. The centrifugal force generated by the rotation at this time works to correct the warp of the stamper 100. In order to effectively use this function, it is preferable to make the stamper 100 relatively thin,
Specifically, the thickness is 0.3 to 1.8 mm, particularly 0.3 to 1.
It is preferably 4 mm.

[0103]

[Example] Outer diameter 120 having a groove pattern on the surface
A disc-shaped substrate SB (made of polycarbonate) having a diameter of 15 mm, an inner diameter (diameter of the central hole) of 15 mm, and a thickness of 1.2 mm was prepared by injection molding. In addition, a transparent stamper 100 (made of polymethylpentene) having a diameter of 120 mm and a thickness of 0.6 mm provided with a groove pattern mother pattern on the surface was produced by injection molding. In the substrate SB and the stamper 100,
The groove arrangement pitch was 0.6 μm, and the groove depth was 40 nm. A reflective layer, a dielectric layer, a phase-change recording layer and a dielectric layer were formed in this order on the groove pattern forming surface of the substrate SB by a sputtering method to form a first information recording layer IL-1.

Then, a transparent intermediate layer TL was formed by the following procedure using the method of using the closing means 300 as shown in FIGS. The closing means 300 used is made of a stainless alloy and has a shape shown in FIG. 2. The disk portion 301 has a diameter of 38 mm and the support shaft 32 has a diameter of 1 mm.
mm, length 20 mm.

First, the substrate SB is placed on a rotary table, the closing means 300 is fitted into the center hole CH of the substrate SB, and then the ultraviolet curable resin (manufactured by Nippon Kayaku Co., Ltd.) is rotated while rotating the rotary table at 60 rpm. MPZ203, viscosity 90 mPas at 25 ° C.) is supplied to the outer peripheral surface of the support shaft 302,
The resin was then spread by rotating the turntable at 2000 rpm for 6 seconds. When spreading this resin,
At 5 seconds after the spreading was almost completed, the thin plate-shaped scraping means was brought close to the outer peripheral surface of the substrate, and the resin protruding to the outer peripheral surface of the substrate was scraped for 1 second. Then, the shaving means is moved away from the substrate, and the deceleration of the rotary table is started. The strength is 160 mW / cm ² after 0.3 seconds from the start of deceleration.
UV rays of 0.5 seconds were irradiated. The ultraviolet irradiation amount at this time was 80 mJ / cm ² , and thus the first resin layer RL-1 in the incompletely cured state was formed. The time from the start of deceleration to the stop of rotation was 1 second.

UV spot cure BHG-250 manufactured by Mejiro Precision Co., Ltd. was used as the ultraviolet irradiation means, and the irradiation range was set to a circle with a diameter of 120 mm so that the entire surface of the substrate was irradiated with ultraviolet rays. However, a mask having a diameter of 40 mm was arranged on the closing means 300 so that the ultraviolet rays were not irradiated.

Then, after removing the closing means 300,
While rotating the substrate SB at a low speed, the ultraviolet curable resin was dropped near the inner circumference of the first resin layer RL-1 over about one round. Then, after the rotation is stopped once, the stamper 100 is placed on the dropped ultraviolet curing resin, the substrate SB and the stamper 100 are integrally rotated at about the same time, and the rotation speed is maintained at 6000 rpm for about 10 seconds. After the UV curable resin was spread by, the rotation was stopped. As a result, the second resin layer RL-2 was formed.
The average thickness of the second resin layer RL-2 on the information recording area was 4 μm.

Next, the resin laminate RL was cured by irradiating it with ultraviolet rays through the stamper 100 to form a transparent intermediate layer TL. The UV irradiation dose was 1 J / cm ² . Next, the stamper 100 was peeled off from the transparent intermediate layer TL. The ultraviolet curable resin did not adhere to the peeled stamper 100, and it was confirmed that the stamper 100 has good mold releasability. In the formed transparent intermediate layer TL, air bubbles were not observed at all over the entire surface.

Then, an Au thin film having a thickness of 60 nm was formed as a second information recording layer IL-2 on the transparent intermediate layer TL by a sputtering method to obtain a sample for evaluation. When the surface of the Au thin film of this evaluation sample was observed with a scanning electron microscope, it was confirmed that there were no transfer defects and that the groove pattern was transferred accurately.

The thickness variation in the radial direction of the transparent intermediate layer TL of this evaluation sample was measured by a laser focus displacement meter LT8010 manufactured by Keyence Corporation. The results are shown in Table 1. In Table 1, ΔT is the difference between the maximum thickness and the minimum thickness of the transparent intermediate layer on the information recording area (range of radius 23 to 58 mm), and T _M is the average thickness of the transparent intermediate layer.

[0111]

[Table 1]

As shown in Table 1, this transparent intermediate layer has a small ΔT and good thickness uniformity.

[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 cross-sectional view for explaining a part of the first coating step.

FIG. 3 is a cross-sectional view for explaining a part of the first coating step.

FIG. 4 is a cross-sectional view for explaining a part of the first coating step.

FIG. 5 is a cross-sectional view for explaining a part of the first coating step.

FIG. 6 is a cross-sectional view for explaining a part of the first coating step.

FIG. 7 is a cross-sectional view for explaining a part of the first coating step.

FIG. 8 is a cross-sectional view for explaining a part of the second coating step.

FIG. 9 is a sectional view for explaining a part of the second coating step.

FIG. 10 is a cross-sectional view for explaining a part of the second coating step.

FIG. 11 is a cross-sectional view for explaining a curing process.

FIG. 12 is a cross-sectional view for explaining a peeling process.

FIG. 13 is a cross-sectional view for explaining a laminating process.

14 (A) to (D) are cross-sectional views showing a configuration example of a closing means.

[Explanation of symbols]

CH center hole IL-1, IL-2 information recording layer PL protective layer RL resin laminate RL-1 first resin layer RL-2 second resin layer SB substrate TL transparent intermediate layer 11, 12 coated object 100 stamper 200 turntable 201 protrusion 300 blocking means 301 Disc part 302 support shaft 303 convex 400 nozzles 500 coating liquid

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5D029 JB13 LB07                 5D121 AA03 CA06 CA10 EE22 EE23                       EE26 GG02

Claims (11)

[Claims] 1. A plurality of information recording layers having a concavo-convex pattern are laminated on a disc-shaped substrate, and a transparent intermediate layer through which a recording / reproducing beam can pass is present between adjacent information recording layers. A method for producing an optical information medium, wherein an intermediate layer contains a resin cured by active energy rays, comprising a substrate on which at least one information recording layer is formed, and a master pattern of the concavo-convex pattern. Each of the disc-shaped stampers has an object to be coated, and by rotating one of the objects to be coated, a coating solution containing a resin is spread on the surface of the one object to be coated to form the first resin layer. First forming step of forming, and after supplying a coating liquid containing a resin to the surface of the first resin layer and / or the surface of the other object to be coated, the one object to be coated and the other object to be coated Object to be coated By facing each other and bringing the coating liquid into contact with both the first resin layer and the other object to be coated, and then rotating the one object to be coated and the other object to be coated together. To spread the coating liquid to form a second resin layer,
A second coating step in which a resin laminated body including the first resin layer and the second resin layer is sandwiched between the one object to be coated and the other object to be coated; A curing step of forming the transparent intermediate layer by irradiating the resin laminate with an active energy ray and curing, a peeling step of peeling the stamper from the transparent intermediate layer, and other information on the transparent intermediate layer. A method of manufacturing an optical information medium, comprising a laminating step of forming a recording layer. 2. The method of manufacturing an optical information medium according to claim 1, wherein in the first coating step, the first resin layer is incompletely or completely cured by irradiation with an active energy ray. 3. In the first coating step, after the first resin layer is formed, irradiation with active energy rays is performed while reducing the rotation speed of the one of the objects to be coated, The method for manufacturing an optical information medium according to claim 1, wherein the resin layer is incompletely or completely cured. 4. In the first coating step, the one object to be coated has a central hole, and a disc portion for closing the central hole and a central portion of the disc portion are integrated. Preparing a closing means having a supporting shaft, and closing the central hole with the disk portion of the closing means,
After the coating liquid is supplied to the outer peripheral surface of the support shaft, the one coating object is rotated together with the closing means to spread the coating liquid on the one coating object. The method for manufacturing an optical information medium according to claim 1, wherein the resin layer is formed. 5. The stamper has a thickness of 0.3 to 1.8 mm.
5. The method for manufacturing an optical information medium according to claim 1. 6. The information recording layer has an information recording area, and the average thickness on the information recording area is 5 to 50.
The transparent intermediate layer is formed to have a thickness of μm.
5. The method for manufacturing the optical information medium according to any one of 5 above. 7. The optical information according to claim 6, wherein the second resin layer is formed so that the average thickness on the information recording area is 0.5 μm or more and 40% or less of the thickness of the resin laminate. Medium manufacturing method. 8. The method according to claim 1, wherein in the second coating step, the coating liquid is in contact with both the first resin layer and the other object to be coated in a reduced pressure atmosphere. A method for manufacturing the optical information medium. 9. When forming the first resin layer and / or
Alternatively, the method of manufacturing an optical information medium according to claim 1, wherein at the time of forming the second resin layer, at least a part of the coating liquid protruding from the outer peripheral edge of the coated object is scraped off. 10. The method for manufacturing an optical information medium according to claim 1, wherein the stamper is made of a resin that can transmit the active energy rays, and the stamper is made disposable. 11. The stamper is one in which at least the surface on which the matrix pattern is formed is made of a polyolefin resin or a fluororesin, and in the curing step, active energy rays are passed through the stamper to the resin laminate. The method for manufacturing an optical information medium according to claim 1, wherein the optical information medium is irradiated with light.