JP2004334991A - Optical recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress swelling of a light transmission layer in an outer circumferential part of an optical recording medium wherein an information signal layer and the light transmission layer are successively stacked on one principal surface of a substrate. <P>SOLUTION: The signal surface 1a of a substrate 1 is formed by using a stamper of which the outer circumferential part of a transfer surface is swelled. An information signal layer 2 is formed on the signal surface 1a formed by the stamper. UV curing resin is applied to the information signal layer 2 by a spin coat method. The UV curing resin applied to the information signal layer 2 is cured to form a light transmission layer 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical recording medium in which an information signal layer and a light transmitting layer are sequentially laminated on one main surface of a substrate, and a method of manufacturing the same.
[0002]
[Prior art]
In recent years, next-generation high-density optical discs having a 0.1-mm-thick light-transmitting layer on an information signal layer formed on a substrate have been proposed for optical discs in order to meet the demand for higher recording density. ing. In this optical disk, recording / reproducing of an information signal is performed by irradiating the information signal layer from the light transmission layer side with blue-violet laser light focused by an objective lens having a high NA (for example, 0.85).
[0003]
As a method of manufacturing this next-generation high-density optical disk, an ultraviolet curable resin (UV resin) is applied to a thickness of 100 μm on an information signal layer formed on a substrate by spin coating, and then applied on the information signal layer. A production method has been proposed in which a light transmitting layer is formed by irradiating an ultraviolet curable resin with ultraviolet light.
[0004]
[Problems to be solved by the invention]
However, when an ultraviolet curable resin is applied on a substrate by spin coating, the ultraviolet curable resin swells on the outer peripheral portion due to surface tension. The starting point of the swelling has a characteristic that the thicker the ultraviolet curable resin is applied, the more the center is shifted to the center side. Therefore, depending on the thickness of the ultraviolet curable resin, the starting point of the gradient is located in the signal area. As described above, if the gradient starting point is located in the signal area, the spot shape of the laser beam is deformed at the portion where the light transmitting layer is raised at the time of recording / reproducing the information signal, and the recording / reproducing characteristics are deteriorated. The problem arises.
[0005]
FIG. 7 shows the substrate 101 on which one surface is coated with the ultraviolet curing resin 103 by the spin coating method. When the ultraviolet curable resin 103 is applied on the information signal layer 102 to a thickness of 100 μm, the starting point of the gradient is located at a position with a diameter d ₁₀₁ = 114 mm. In the next-generation high-density optical disk, the outer peripheral diameter (diameter) of the signal area is 117.5 mm, so the above-mentioned gradient starting point is within the signal area.
[0006]
Therefore, an object of the present invention is to provide an optical recording medium having an information signal layer and a light transmitting layer sequentially laminated on one main surface of a substrate, which can suppress the rise of the light transmitting layer in the outer peripheral portion. An object of the present invention is to provide a medium and a method for manufacturing the medium.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a first invention of the present application is directed to an optical recording medium in which an information signal layer and a light transmission layer are sequentially laminated on one main surface of a substrate,
An optical recording medium, characterized in that the substrate has, on an outer peripheral portion of one principal surface, an inclined surface where the thickness of the substrate decreases toward the outer periphery.
[0008]
According to the first invention of the present application, in a method for manufacturing an optical recording medium in which an information signal layer and a light transmitting layer are sequentially laminated on one main surface of a substrate, Since the inclined surface is formed such that the thickness of the substrate becomes thinner, when the resin is applied on one main surface of the substrate by a spin coating method, the resin is prevented from rising on the outer peripheral portion of the one main surface. Can be.
[0009]
The second invention of the present application is a method for manufacturing an optical recording medium using a stamper having an inclined surface in which the thickness of the stamper increases toward the outer periphery on the outer peripheral portion of the transfer surface,
Transferring the transfer surface of the stamper to the substrate to form one main surface of the substrate,
Forming an information signal layer on one main surface formed by the stamper;
A step of applying a resin on the information signal layer by spin coating,
Curing the resin applied on the information signal layer to form a light-transmitting layer.
[0010]
According to the second aspect of the present invention, one main surface of the substrate is formed using a stamper having an inclined surface on the outer peripheral portion of the transfer surface where the thickness of the stamper increases toward the outer periphery, and the one main surface formed by the stamper is formed. An information signal layer is formed thereon, a resin is applied on the information signal layer by a spin coating method, and the resin applied on the information signal layer is cured to form a light transmitting layer. The resin can be prevented from rising at the outer peripheral portion.
[0011]
The third invention of the present application is a method for manufacturing an optical recording medium using a stamper having an inclined surface in which the thickness of the stamper increases toward the outer periphery on the outer peripheral portion of the transfer surface,
Transferring the transfer surface of the stamper to the substrate to form one main surface of the substrate,
Forming an information signal layer on one main surface formed by the stamper;
A step of applying a resin on the information signal layer by spin coating,
Curing the resin applied on the information signal layer to form a first light transmitting layer;
Pressing the outer peripheral portion of the first light transmitting layer;
A step of applying a resin on the first light transmitting layer by a spin coating method;
Curing the resin applied on the light-transmitting layer to form a second light-transmitting layer.
[0012]
According to the third aspect of the present invention, one main surface of the substrate is formed by using a stamper having an inclined surface on the outer peripheral portion of the transfer surface, where the thickness of the stamper increases toward the outer periphery, and the one main surface formed by the stamper An information signal layer is formed thereon, a resin is applied on the information signal layer by a spin coating method, and the resin applied on the information signal layer is cured to form a first light transmitting layer. Pressing the outer periphery of the transmission layer, applying a resin on the first light transmission layer by spin coating, and curing the resin applied on the first light transmission layer to form a second light transmission layer Therefore, it is possible to suppress the resin from rising on one main surface of the substrate and the outer peripheral portion of the first light transmitting layer during spin coating.
[0013]
The fourth invention of the present application is a step of pressing an outer peripheral portion of one main surface of the substrate to form an inclined surface on the outer peripheral portion of one main surface of the substrate, the thickness of the substrate decreasing toward the outer periphery.
Forming an information signal layer on one main surface of the substrate;
A step of applying a resin on the information signal layer by spin coating,
Curing the resin applied on the information signal layer to form a light-transmitting layer.
[0014]
According to the fourth aspect of the present invention, an inclined surface where the thickness of the substrate is reduced toward the outer periphery is formed on the outer peripheral portion of one main surface of the substrate, and an information signal layer is formed on one main surface of the substrate, A resin is applied on the information signal layer by a coating method, and the resin applied on the information signal layer is cured to form a light transmitting layer. Therefore, the resin is prevented from rising on one main surface of the substrate during spin coating. be able to.
[0015]
The fifth invention of the present application is a step of pressing an outer peripheral portion of one main surface of the substrate to form an inclined surface on the outer peripheral portion of the one main surface of the substrate, the thickness of the substrate decreasing toward the outer periphery,
Forming an information signal layer on one main surface of the substrate;
A step of applying a resin on the information signal layer by spin coating,
Curing the resin applied on the information signal layer to form a first light transmitting layer;
Pressing the outer peripheral portion of the first light transmitting layer;
A step of applying a resin on the first light transmitting layer by a spin coating method;
Curing the resin applied on the light-transmitting layer to form a second light-transmitting layer.
[0016]
According to the fifth aspect of the present invention, an inclined surface where the thickness of the substrate is reduced toward the outer periphery is formed on the outer peripheral portion of the one main surface of the substrate, and the information signal layer is formed on the one main surface of the substrate. A resin is applied on the information signal layer by a coating method, and the resin applied on the information signal layer is cured to form a first light transmitting layer. The outer peripheral portion of the first light transmitting layer is pressed, and spin coating is performed. A resin is applied on the first light transmitting layer by a method, and the resin applied on the first light transmitting layer is cured to form a second light transmitting layer. In addition, it is possible to suppress the resin from rising at the outer peripheral portion of the first light transmitting layer.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the configuration of an optical disc (optical recording medium) according to the first embodiment of the present invention. As shown in FIG. 1, this optical disc has a configuration in which an information signal layer 2 and a light transmitting layer 3 are sequentially laminated on one main surface of a substrate 1. Hereinafter, one principal surface of the substrate 1 on which the information signal layer 2 is formed is referred to as a signal surface 1a. This optical disc is, for example, a Blu-ray Disc.
[0018]
The substrate 1 has an annular shape having a center hole (not shown) at the center. The thickness _{t 1} of the substrate 1 is selected to be, for example, 1.1 mm. The center hole diameter of the substrate 1 is selected to be, for example, 15 mm. Outside diameter _{d 1} of the substrate 1 is selected to be, for example, 120 mm.
[0019]
Further, as a material of the substrate 1, for example, polycarbonate (PC), acrylic, or polyolefin is used. In the optical disc according to the first embodiment, recording / reproducing of an information signal is performed by irradiating a laser beam from the side on which the light transmitting layer 3 is provided. Therefore, an opaque plastic or the like is used as a material of the substrate 1. It is also possible.
[0020]
A signal area 4 is set on the signal surface 1a of the substrate 1. The signal area 4 is formed with irregularities such as pits or grooves, and the outer peripheral diameter (diameter) of the signal area 4 is selected to be, for example, 117.5 mm. In addition, the substrate 1 has an inclined surface on the outer peripheral portion of the signal surface 1a where the thickness of the substrate 1 decreases toward the outer periphery. The starting point of the inclined surface is selected at a position equal to or larger than the outer diameter of the signal region 4, for example, at a position having a diameter of 117.5 mm. The difference between the thickness t ₃ of the substrate 1 in the outer periphery of the substrate 1, the thickness t ₁ of the substrate 1 in the signal region 4 is, for example, 50 [mu] m.
[0021]
The information signal layer 2 is a reflective film made of, for example, Au, Ag, an Ag alloy, Al, or an Al alloy when the optical disc is of a read-only type. When the optical disc is of the write-once type, the information signal layer 2 is formed by sequentially laminating a reflective film and a recording layer made of an organic dye material on the signal surface 1a of the substrate 1. When the optical disc is of a rewritable type, the information signal layer 2 is formed by sequentially laminating a reflective film, a lower dielectric layer, a layer change recording layer, and an upper electric layer on the signal surface 1a of the substrate 1. Be composed.
[0022]
The light transmitting layer 3 is made of a resin having a good light transmitting property. As the resin, for example, urethane or epoxy acrylate is used. The thickness _{t 2} of the light transmission layer 3 is selected from the 100 [mu] m or less the range of 20 [mu] m, it is selected to be, for example, 100 [mu] m.
[0023]
Next, a method of manufacturing the optical disc according to the first embodiment of the present invention will be described. FIG. 2 shows a cross section of a stamper used in the method for manufacturing an optical disk according to the first embodiment of the present invention. FIG. 3 is a sectional view for explaining the method for manufacturing the optical disc according to the first embodiment of the present invention.
[0024]
As shown in FIG. 2, a transfer area 12 for forming the signal area 4 of the substrate 1 is set on one main surface of the stamper 11. The transfer area 12 has irregularities formed thereon, and the irregularities have a pattern opposite to that formed in the signal area 4 of the substrate 1. Hereinafter, one main surface on the side where the unevenness is formed is referred to as a transfer surface 11a.
[0025]
In addition, the stamper 11 has an inclined surface on the outer peripheral portion of the transfer surface 11a where the thickness of the stamper increases toward the outer periphery. The starting point of the inclination of the inclined surface is selected at a position equal to or larger than the outer diameter of the transfer area 12, for example, at a position having a diameter of 117.5 mm. The difference _{t 11} and the thickness of the stamper 11 in the thickness and the transfer region of the stamper 11 in the outer periphery of the transfer surface 11a is, for example, 50 [mu] m. As the material of the stamper 11, a metal such as Ni is selected.
[0026]
Hereinafter, the method of manufacturing the optical disc according to the first embodiment will be described with reference to FIG. First, the transfer surface 11a of the stamper shown in FIG. 2 is transferred to the substrate 1 by, for example, an injection molding method. As a result, as shown in FIG. 3A, a signal surface 1a having irregularities such as pits or grooves is formed on the substrate 1. Next, as shown in FIG. 3B, the information signal layer 2 is formed on the signal surface 1a of the substrate 1 by, for example, a sputtering method.
[0027]
Next, an ultraviolet curable resin is applied on the information signal layer 2 by spin coating. At this time, the number of rotations of the substrate 101 is selected in consideration of the thickness of the ultraviolet curable resin after application, and is selected, for example, from a range of 3000 rpm to 10000 rpm. Further, the viscosity of the ultraviolet curable resin is selected from the range of 500 cps to 5000 cps at room temperature. Next, ultraviolet rays are applied to the ultraviolet curable resin applied on the information signal layer 2. Thereby, the ultraviolet curable resin is cured, and the light transmitting layer 3 is formed on the information signal layer 2 of the substrate 1 as shown in FIG. 3C.
[0028]
According to the first embodiment of the present invention, the following effects can be obtained.
The signal surface 1a of the substrate 1 is formed using the stamper 11 in which the outer peripheral portion of the transfer surface 11a is raised, the information signal layer 2 is formed on the signal surface 1a formed by the stamper 11, and the information signal is formed by spin coating. In order to form the light transmitting layer 3 by applying an ultraviolet curable resin on the layer 2 and curing the ultraviolet curable resin applied on the information signal layer 2, the ultraviolet curable resin is applied on the outer peripheral portion of the signal surface 1a during spin coating. The swelling can be suppressed, and the starting point of the swelling can be set on the outer peripheral side of the signal region 4. Thereby, the deformation of the spot shape on the information signal layer 2 can be suppressed, and good recording / reproducing characteristics can be realized.
[0029]
Further, even when the ultraviolet curable resin is applied on the information signal layer 2 to a thickness in the range of 20 μm to 100 μm by the spin coating method, the thickness tolerance can be suppressed to ± 2 μm or less. Therefore, the light transmitting layer 3 having a thickness of 20 μm to 100 μm and excellent in uniformity can be formed on the information signal layer 2.
[0030]
Further, the light transmitting layer 3 having a uniform thickness can be formed on the signal surface 1a of the substrate 1 without using an expensive sheet. Therefore, the material cost and the equipment cost can be reduced, and the next-generation high-density optical disk can be manufactured at low cost.
[0031]
Next, a second embodiment of the present invention will be described. FIG. 4 is a sectional view for explaining a method for manufacturing an optical disk according to the second embodiment of the present invention. Hereinafter, a method for manufacturing an optical disc according to the second embodiment of the present invention will be described with reference to FIG.
[0032]
First, the transfer surface of the conventional stamper is transferred to the substrate 1 by, for example, an injection molding method. Thereby, as shown in FIG. 4A, a signal surface 1a having irregularities such as pits or grooves is formed on the substrate 1.
[0033]
Next, the substrate 1 is placed at a predetermined position of a press device (not shown), and the center position of the ring-shaped press section 21 and the center position of the substrate 1 are matched. Then, as shown in FIG. 4B, the press section 21 is lowered toward the signal surface 1a of the substrate 1, and the outer peripheral portion of the signal surface 1a is pressed. Thereby, as shown in FIG. 4C, the outer peripheral portion of the signal surface 1a is recessed, and an inclined surface in which the thickness of the substrate 1 decreases toward the outer periphery is formed on the outer peripheral portion of the signal surface 1a. The pressing pressure at the time of pressing is selected, for example, to 100 kg. The press time is selected, for example, from the range of 3 s to 5 s. The press section 21 is configured to be heatable, and it is preferable that the press section 21 be overheated during pressing. The temperature of the press section 21 at the time of pressing is selected to be, for example, 180 ° C.
[0034]
Thereafter, as in the first embodiment, the information signal layer 2 and the light transmitting layer 3 are sequentially laminated on the signal surface 1a of the substrate 1. Thus, the intended optical disc according to the second embodiment is manufactured. According to the second embodiment of the present invention, the same effects as those of the first embodiment can be obtained.
[0035]
Next, a third embodiment of the present invention will be described. 5 and 6 are sectional views for explaining a method for manufacturing an optical disk according to the third embodiment of the present invention. Hereinafter, a method for manufacturing an optical disk according to the third embodiment of the present invention will be described with reference to FIGS.
[0036]
First, as in the first embodiment, the substrate 1 is formed, and the information signal layer 2 is formed on the signal surface 1a of the substrate 1. Next, an ultraviolet curable resin is applied on the information signal layer 2 by spin coating. The thickness of the ultraviolet curable resin after application is in a range of, for example, 20 μm to 100 μm, for example, 25 μm. At this time, the number of rotations of the substrate 1 is selected in consideration of the thickness of the ultraviolet curable resin after application, and is selected, for example, from a range of 3000 rpm to 10000 rpm. In addition, the clay of the ultraviolet curing resin is selected from the range of 500 cps to 5000 cps at room temperature.
[0037]
Next, ultraviolet rays are applied to the ultraviolet curable resin applied on the information signal layer 2. Thereby, the ultraviolet curing resin is cured, and the first light transmitting layer 3a is formed on the information signal layer 2 as shown in FIG. 5A.
[0038]
Next, the substrate 1 is placed at a predetermined position of a press device (not shown), and the center position of the ring-shaped press section 21 and the center position of the substrate 1 are matched. Then, as shown in FIG. 5B, the press section 21 is lowered toward the signal surface 1a of the substrate 1, and the outer peripheral portion of the signal surface 1a is pressed. As a result, as shown in FIG. 6A, the ridge formed on the outer peripheral portion of the first light transmitting layer 3a is crushed, and the surface of the first light transmitting layer 3a on which the laser beam is irradiated is substantially flat. In a state. The pressing pressure at the time of pressing is selected, for example, to 100 kg. The press time is selected, for example, from the range of 3 s to 5 s. The press section 21 is configured to be heatable, and it is preferable that the press section 21 be overheated during pressing. The temperature of the press section 21 at the time of pressing is selected to be, for example, 180 ° C.
[0039]
Next, an ultraviolet curable resin is applied on the first light transmitting layer 3a by spin coating. The thickness of the ultraviolet curable resin after application is in a range of, for example, 20 μm to 100 μm, and is, for example, 75 μm. At this time, the number of rotations of the substrate 1 is selected in consideration of the thickness of the ultraviolet curable resin after application, and is selected, for example, from a range of 3000 rpm to 10000 rpm. In addition, the clay of the ultraviolet curing resin is selected from 500 cps to 5000 cps at room temperature.
[0040]
Next, ultraviolet rays are applied to the ultraviolet curable resin formed on the signal surface 1a. Thereby, the ultraviolet curable resin is cured, and as shown in FIG. 6B, the second light transmitting layer 3b is formed on the first light transmitting layer 3a. As described above, the target optical disc according to the third embodiment is manufactured. According to the third embodiment of the present invention, the same effects as in the first embodiment can be obtained.
[0041]
Next, a fourth embodiment of the present invention will be described. Hereinafter, a method for manufacturing the optical disc according to the fourth embodiment of the present invention will be described. First, in the same manner as in the second embodiment, the substrate 1 is formed, the outer peripheral portion of the signal surface 1a is pressed, and the information signal layer 2 is formed on the signal surface 1a. Then, in the same manner as in the third embodiment, the first light transmitting layer 3a is formed on the signal surface 1a, and the outer periphery of the first light transmitting layer 3a is pressed. Then, the second light transmitting layer 3b is formed. As described above, the intended optical disc according to the fourth embodiment is manufactured. According to the fourth embodiment of the present invention, the same effects as in the first embodiment can be obtained.
[0042]
As described above, the first to fourth embodiments of the present invention have been specifically described. However, the present invention is not limited to the above-described first to fourth embodiments. Various modifications are possible.
[0043]
For example, the numerical values given in the above-described first to fourth embodiments are merely examples, and different numerical values may be used as needed.
[0044]
In the above-described first to fourth embodiments, an example in which the present invention is applied to an optical disc having one information signal layer 2 has been described. However, an optical disc having a plurality of information signal layers has been described. The present invention may be applied. In this case, it goes without saying that the present invention is also applicable when forming the intermediate layer (light transmitting layer).
[0045]
【The invention's effect】
As described above, according to the present invention, in an optical recording medium manufacturing method in which an information signal layer and a light transmitting layer are sequentially laminated on one main surface of a substrate, Since the inclined surface where the thickness of the substrate is reduced toward the outer periphery is formed, when the resin is applied on the signal surface of the substrate by spin coating, the resin is prevented from rising at the outer periphery of the signal surface. be able to. Thereby, deformation of the spot shape at the outer peripheral portion can be suppressed, and good signal characteristics can be realized also at the outer peripheral portion.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a configuration of an optical disc according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing an example of a configuration of a stamper according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view for explaining the method for manufacturing the optical disc according to the first embodiment of the present invention.
FIG. 4 is a cross-sectional view for explaining a method of manufacturing an optical disc according to a second embodiment of the present invention.
FIG. 5 is a sectional view for explaining a method for manufacturing an optical disc according to a third embodiment of the present invention.
FIG. 6 is a sectional view for explaining a method of manufacturing an optical disc according to a third embodiment of the present invention.
FIG. 7 is a cross-sectional view illustrating an example of a configuration of a conventional optical disc.
[Explanation of symbols]
1, 101 ... substrate, 1a ... signal surface, 1b, 11b ... back surface, 2, 102 ... information signal layer, 3 ... light transmission layer, 4 ... signal area, 11 ... ..Stamper, 11a..transfer area, 21..press part, 103..ultraviolet curing resin

Claims (5)

An optical recording medium in which an information signal layer and a light transmission layer are sequentially laminated on one main surface of a substrate,
An optical recording medium, characterized in that the substrate has, on an outer peripheral portion of one principal surface, an inclined surface where the thickness of the substrate decreases toward the outer periphery. A method for manufacturing an optical recording medium using a stamper having an inclined surface in which the thickness of the stamper increases toward the outer periphery on the outer peripheral portion of the transfer surface,
Transferring the transfer surface of the stamper to a substrate to form one main surface of the substrate,
Forming an information signal layer on the one main surface formed by the stamper;
A step of applying a resin on the information signal layer by spin coating,
Curing the resin applied on the information signal layer to form a light transmitting layer. A method for manufacturing an optical recording medium using a stamper having an inclined surface in which the thickness of the stamper increases toward the outer periphery on the outer peripheral portion of the transfer surface,
Transferring the transfer surface of the stamper to a substrate to form one main surface of the substrate,
Forming an information signal layer on the one main surface formed by the stamper;
A step of applying a resin on the information signal layer by spin coating,
Curing the resin applied on the information signal layer to form a first light transmitting layer;
Pressing an outer peripheral portion of the first light transmitting layer;
Applying a resin onto the first light transmitting layer by spin coating,
Curing the resin applied on the light transmitting layer to form a second light transmitting layer. Pressing the outer peripheral portion of one main surface of the substrate, and forming an inclined surface on the outer peripheral portion of the one main surface of the substrate, in which the thickness of the substrate decreases toward the outer periphery,
Forming an information signal layer on one main surface of the substrate;
A step of applying a resin on the information signal layer by spin coating,
Curing the resin applied on the information signal layer to form a light-transmitting layer. Pressing the outer peripheral portion of one main surface of the substrate, and forming an inclined surface on the outer peripheral portion of the one main surface of the substrate, in which the thickness of the substrate decreases toward the outer periphery,
Forming an information signal layer on one main surface of the substrate;
A step of applying a resin on the information signal layer by spin coating,
Curing the resin applied on the information signal layer to form a first light transmitting layer;
Pressing an outer peripheral portion of the first light transmitting layer;
Applying a resin onto the first light transmitting layer by spin coating,
Curing the resin applied on the light transmitting layer to form a second light transmitting layer.

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