JP2001067725A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make no exfoliation cause of the interface of a transparent resin layer and a transparent substrate when a stamper is peeled off by laminating, on the uneven surface of the transparent substrate provided with the smooth surface and the uneven surface having minutely projecting and recessing parts, the transparent resin layer having an information recording surface where pit rows are formed on the side surface opposite to the uneven surface. SOLUTION: The transparent substrate 101 has the smooth surface 102 on one surface and the uneven surface 103 where the pit rows or groups are formed on the other surface. A surface area of the surface 103 is preferably made larger than that of the information recording surface 105. The transparent resin layer 104 consisting of an acrylic ultraviolet ray-curable resin is formed on the surface 103 of the substrate 101. The layer 104 has the surface 105 where the pit rows transferred from a stamper by a 2P method are formed. Probability to cause the exfoliation on the interface between the substrate 101 and the layer 104 can be made low by using this constitution when the stamper is peeled off from the layer 104.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information recording medium such as a compact disc (CD: Compact Disc) and a digital versatile disc (DVD: Digital Versatile Disc). The present invention relates to an optical information recording medium using a 2P (Photo Polymerization) molding method for transferring a fine pattern formed on a stamper to the ultraviolet curable resin.

[0002]

2. Description of the Related Art Conventionally, an ultraviolet curing resin is applied on a substrate, a stamper having a fine pattern such as a pit row or a guide groove is brought into close contact with the ultraviolet curing resin, and the ultraviolet curing resin is cured by irradiating ultraviolet rays. To transfer the fine pattern formed on the stamper to the ultraviolet curable resin.
(oto Polymerization) A molding method is known.

The method of forming a fine pattern by the 2P molding method can transfer the shape of the fine pattern formed on the stamper more faithfully than the injection molding method. Also,
There is no increase in the birefringence or internal stress of the substrate during molding unlike the injection molding method. For this reason, it is considered that the 2P molding method will be adopted in the production of optical disks having fine patterns such as higher-density pit rows and guide grooves.

FIG. 3 is a schematic diagram for explaining a part of a manufacturing process of an optical information recording medium using a conventional 2P molding method. In the figure, 301 is a transparent substrate, 302 is an ultraviolet curable resin, 30
Reference numeral 3 denotes a stamper, 304 denotes an ultraviolet irradiation device, 305 denotes ultraviolet light, and 306 denotes a transparent resin layer. An ultraviolet-curing resin 302 is applied to a transparent substrate 301 made of polycarbonate resin, acrylic resin, glass or the like having a thickness of 1.2 mm and having smooth surfaces on both sides (FIG. 3A).

The information recording surface of the nickel stamper 303 on which a fine pattern such as a pit row or a guide groove is formed is brought into close contact with the surface of the ultraviolet curable resin 302 (FIG. 3).
(B)). Next, until the ultraviolet curable resin layer 302 is in a cured state (a state in which the degree of curing of the ultraviolet curable resin is 99% or more), the ultraviolet irradiator 304 is applied from the transparent substrate 301 side.
(FIG. 3C).

When the ultraviolet curable resin 302 is cured to form the cured transparent resin layer 306, the irradiation of ultraviolet rays is stopped, and the stamper 303 is peeled from the transparent resin layer 306 (FIG. 3D). As described above, the pit rows recorded on the information recording surface of the stamper 303 can be transferred to the surface of the transparent resin layer 306 formed on the transparent substrate 301 by the steps of FIGS.

The surface of the transparent resin layer 306 on which the pit rows are transferred is covered with a reflective film made of a metal such as aluminum or gold, or a dielectric such as silicon nitride, and a protective layer or the like is formed on the surface of the reflective film. By forming the optical disk, an optical disk can be manufactured.

[0008] A CD is formed on a transparent substrate having a thickness of 1.2 mm.
The shortest pit length is about 0.9μm with a track pitch of 6mm
Are formed. In a DVD having a recording density of a CD increased to about 7 times or more, a pit row having a track pitch of 0.74 μm and a shortest pit length of about 0.4 μm is formed on a 0.6 mm thick transparent substrate.

[0009]

As shown in FIG.
On the stamper 303 for D or DVD, a pit row which is a fine uneven pattern as described above is formed. On the other hand, the surface of the transparent substrate 301 on which the ultraviolet curing resin layer is formed is a smooth surface. Therefore, the transparent resin layer 306
At the interface where the transparent substrate 301 and the transparent resin layer 306 are in contact with each other.

[0010] Therefore, the stamper 303 is formed of the transparent resin layer 3.
There is a problem in that when peeling from the substrate 06, peeling occurs at the interface between the transparent substrate 301 and the transparent resin layer 306.

According to the present invention, in an optical information recording medium using the 2P method, when a stamper is peeled, the probability of occurrence of a defect that peeling occurs at the interface between the transparent resin layer and the transparent substrate can be reduced. It is an object of the present invention to provide an optical information recording medium that can be manufactured at a high yield.

[0012]

In order to solve the above-mentioned problems, the invention according to claim 1 of the present application is directed to an optical information recording medium having a transparent surface having a smooth surface and an uneven surface on which fine unevenness is formed. A substrate, a transparent resin layer having an information recording surface laminated on the uneven surface and having a pit row formed on a surface opposite to the uneven surface, and a reflective film formed so as to cover the information recording surface. It is characterized by having.

According to a second aspect of the present invention, in the optical information recording medium according to the first aspect, a surface area of the uneven surface is larger than a surface area of the information recording surface.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing the configuration of an embodiment of the optical information recording medium of the present invention. In the figure, 101 is a transparent substrate, 102 is a smooth surface, 103 is an uneven surface, 104 is a transparent resin layer, 105 is an information recording surface, 106 is a reflective film, 1
Reference numeral 07 denotes a protective film. In FIG. 1, a transparent substrate 101
Is a substrate made of acrylic resin having a diameter of 120 mm, an inner diameter of 15 mm, and a thickness of 1.2 mm. The refractive index of the transparent substrate 101 is about 1.49. One surface of the transparent substrate 101 is a smooth surface 102 which is a smooth surface, and the other surface is an uneven surface 103 on which pit rows or grooves are formed.

The width, depth and track pitch of the pit rows or grooves formed on the uneven surface 103 are arbitrary, but it is preferable that the surface area is larger than the surface area of the information recording surface 105 described later. In this embodiment, the uneven surface 1
03, a groove having a depth of about 130 nm and a width of about 500 nm is formed at a track pitch of 1.0 μm in a region from a diameter of 30 mm to a diameter of 119 mm.

The transparent substrate 101 is formed by an injection molding method using a stamper in which a groove having a depth of about 130 nm and a width of about 500 nm is formed in a region having a diameter of 30 to 119 mm as described later. But,
Since the grooves on the uneven surface 103 are only for increasing the adhesion between the transparent substrate 101 and the transparent resin layer 104, it is not always necessary that the shape of the grooves formed on the stamper be faithfully transferred. . Therefore, molding can be performed under conditions such as pressure, temperature, and the like at the time of injection molding, in which birefringence hardly occurs in the transparent substrate 101.

On the uneven surface 103 of the transparent substrate 101, a transparent resin layer 104 made of an acrylic ultraviolet curable resin is formed with a thickness of about 50 μm. Transparent resin layer 104
It is preferable to use a material having a refractive index substantially the same as that of the transparent substrate 101. If the refractive index difference between the two is large, a part of the reproduction laser light is reflected at the interface between the uneven surface 103 and the transparent resin layer 104, and there is a possibility that the quality of the reproduction signal is degraded. In this embodiment, an acrylic UV curable resin having a refractive index of about 1.50 was used.

The transparent resin layer 104 is formed on the information recording surface 10 on which the pit train transferred from the stamper by the 2P method is formed.
5 is provided. In this embodiment, the pit row is a CD.
The pit length is about 0.9 μm
3.3 μm, depth about 120 nm, width about 500 nm,
The track pitch is 1.6 μm, and the information recording surface 105 is formed in a region from a diameter of 45 mm to a diameter of 118 mm.

The information recording surface 105 of the transparent resin layer 104
It is covered with a reflective film 106 made of a metal such as aluminum or gold. The surface of the reflective film 106 is covered with a protective film 107 made of an ultraviolet curable resin or the like.

FIG. 2 is a schematic diagram for explaining a manufacturing process of the optical information recording medium of the present embodiment. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. 201 is an ultraviolet curing resin, 202 is a stamper, 203 is an ultraviolet irradiation device, and 204 is ultraviolet light. As shown in FIG. 2A, it is formed by an injection molding method, is made of acrylic resin having a diameter of 120 mm, an inner diameter of 15 mm, and a thickness of 1.2 mm, and has a smooth surface 102 and a depth of 30 mm to 119 mm. Is about 130 nm and a groove having a width of about 500 nm is formed at a track pitch of 1.0 μm.
And acrylic ultraviolet curable resin 201 (MP manufactured by Mitsubishi Rayon Co., Ltd.) on the uneven surface 103 of the transparent substrate 101 provided with
-403) is added dropwise.

As shown in FIG. 2B, the information recording surface of the stamper 202 is pressed against the ultraviolet curable resin 201 while applying pressure. On the information recording surface of the stamper 202, a pit row having a pit length of about 0.9 μm to 3.3 μm, a depth of about 120 nm, a width of about 500 nm, and a track pitch of 1.6 μm conforming to the CD standard is 45 mm in diameter. From diameter 118
mm. In the above steps, the ultraviolet curable resin 201 may be dropped on the stamper 202 and the uneven surface 103 of the transparent substrate 101 may be pressed against the ultraviolet curable resin 201 while being pressed.

As shown in FIG. 2C, the transparent substrate 101
UV irradiation device 203 (HIGHMERCURY LAMP [OZON
LESS]), in a nitrogen atmosphere, irradiation power of 80 W, irradiation energy of 1000 mJ / cm ² and ultraviolet rays 204 for 5 minutes,
The ultraviolet curing resin 201 is cured.

As shown in FIG. 2D, the stamper 202
Is peeled from the transparent substrate 101, the information recording surface 105 is transferred and cured, and the transparent resin layer 10 is
4 and the stamper 202. According to this embodiment, since the uneven surface 103 is provided on the transparent substrate 101,
The area where the uneven surface 103 and the transparent resin layer 104 are in contact with each other is larger than the area where the smooth surface of the conventional transparent substrate and the transparent resin layer are in contact with each other. The adhesion of is increased. Therefore, when the transparent substrate 101 having the uneven surface 103 according to the present embodiment is used, the transparent substrate 101 and the transparent substrate 101 are removed when the stamper is peeled off, compared to the conventional case where the transparent substrate having both flat surfaces is used. The probability of occurrence of separation at the interface with the resin layer 104 is reduced.

The transparent substrate 101 on which the information recording surface 105 has been transferred by the 2P method is attached to a sputtering device (not shown), and a metal such as aluminum or gold is sputtered to obtain an information recording surface as shown in FIG. A reflective film 106 is formed on 105. Further, the reflection film 10
The transparent substrate 101 on which 5 is formed is attached to a spin coater (not shown), and an ultraviolet curable resin is applied to form a protective film 107 on the reflective film 106 as shown in FIG.

Next, the results of measuring the yield rate when the stamper is peeled off when the transparent substrate having the uneven surface of the present embodiment is used and when the conventional transparent substrate having both flat surfaces is used are shown. . In the first embodiment, the surface area of the uneven surface 103 is smaller than the information recording surface 1.
In the case where the surface area is larger than the surface area of
In the case where the surface area of No. 3 is equal to or smaller than the surface area of the information recording surface 105, the comparative example is a case where a conventional transparent substrate having smooth both surfaces is used. In each case, the same stamper 202 is used, and the curing conditions of the ultraviolet curable resin 201 are the same as those described above.
Those having peeled off at the interface between No. 4 and the transparent substrate 101 were regarded as defective.

While the yield of the comparative example is 75%,
The yield in the case of the first embodiment is 100%, and the yield in the second embodiment is 95%, which is an improved yield. From this result, it can be seen that when the transparent substrate provided with the uneven surface 103 is used, peeling is less likely to occur at the interface between the transparent resin layer 104 and the transparent substrate 101 when the stamper 202 is peeled.

In the above embodiment, the grooves are formed on the uneven surface 103 of the transparent substrate 101. However, the present invention is not limited to this, and a pit row may be used instead of the grooves. Further, the transparent substrate 101 may have a rough surface 103 whose surface is roughened by sandblasting, ion etching, or the like, or by friction using sandpaper, steel wool, or the like.

[0028]

According to the present invention, in an optical information recording medium using the 2P method, when a stamper is peeled off, the probability of occurrence of a defect that peeling occurs at the interface between the transparent resin layer and the transparent substrate is reduced. It is possible to provide an optical information recording medium that can be manufactured at a high yield.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of an optical information recording medium of the present invention.

FIG. 2 is a schematic diagram for explaining a manufacturing process of the optical information recording medium of the present embodiment.

FIG. 3 is a schematic diagram illustrating a part of a manufacturing process of an optical information recording medium using a conventional 2P molding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Transparent substrate 102 Smooth surface 103 Uneven surface 104 Transparent resin layer 105 Information recording surface 106 Reflective film 107 Protective film 201 UV curable resin 202 Stamper 203 UV irradiation device 204 UV 301 Transparent substrate 302 UV curable resin 303 Stamper 304 UV irradiation device 305 UV 306 transparent resin layer

Claims (2)

[Claims] 1. A transparent substrate having a smooth surface and an uneven surface on which fine unevenness is formed, and an information recording surface laminated on the uneven surface and having a pit row formed on a surface opposite to the uneven surface. An optical information recording medium, comprising: a transparent resin layer having: a reflective film formed to cover the information recording surface. 2. The optical information recording medium according to claim 1, wherein
The optical information recording medium according to claim 1, wherein a surface area of the uneven surface is larger than a surface area of the information recording surface.