JP2005243240A - Optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk for reproducing which can be stably manufactured and is durable against an external environment and secular change, and on which pits or grooves for carrying information are formed in multiple layers. <P>SOLUTION: In this optical recording medium, a singular or a plurality of spacer layers in which the pits or grooves for carrying information are formed and a singular or a plurality of reflective layers, mutually overlap and constitute a multilayer. Further, in the optical recording medium, a silane coupling processing of a surface on which the reflective layer or the spacer layer mutually overlaps is carried out. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an optical disc, and more particularly to a playback optical disc in which pits or grooves carrying information are formed in multiple layers.

A so-called compact disc (hereinafter referred to as CD) shown in FIG. 7 is known as a conventional reproducing optical disc. FIG. 7 is a schematic sectional view of a portion where CD pits or grooves are formed. Reference numeral 101 denotes a translucent substrate, which is formed by attaching a stamper of a CD to a mold of a molding machine and injection molding or injection compression molding of a polycarbonate of a thermoplastic resin, thereby transferring pits of the stamper on the surface. Reference numeral 102 is usually a reflective layer, which is formed of a metal thin film obtained by coating aluminum or the like on the light-transmitting substrate 101 by vacuum evaporation or sputtering, and is in close contact with the light-transmitting substrate 101 to form CD pits 102a or grooves 102b. To do. Reference numeral 103 denotes a protective film, which is usually formed by applying and curing, for example, an ultraviolet curable acrylic resin to the substantially uniform thickness on the reflective layer 102 by a spin coating method in order to prevent the reflective layer 102 from being deteriorated or scratched. Is done. Reference numeral 104 denotes a CD label, which is, for example, a synthetic resin coating film coated on the protective film 103 by a method such as screen printing.

The conventional CD pits or grooves are formed as described above, and the pits 102a or grooves 102b are irradiated from above the surface of the CD transparent substrate 101 (in the direction of arrow A in FIG. 7) on which the laser beam of an optical pickup (not shown) rotates. The recorded information is reproduced by reading the reflected light.

However, with the recent increase in information density, high density is also required for the pits or grooves carried by the optical disk, and optical disks having a multi-layer structure of pits or grooves have been studied. In this case, in addition to the normal reflection layer 102, a plurality of spacer layers and intermediate reflection layers, which are alternately laminated between the translucent substrate 101 and the normal reflection layer 102, are provided. It is formed by forming pits or grooves to be held in multiple layers.

For example, as shown in FIG. 8 in the manufacturing process of an optical disk having two layers of pits or grooves, the multi-layered optical disk is first processed by the step (b) after the translucent substrate 101 is formed by the step (a). For example, an ultraviolet curable acrylic resin is formed on the stamper 105 on which the intermediate reflection layer 102 is formed, and then pits or grooves different from the pits or grooves carried by the first intermediate reflection layer 102 are transferred in the step (c). The first spacer layer 106 is formed by applying UV light from above the surface of the light-transmitting substrate 101 in a state where the first intermediate reflective layer 102 is stacked at a predetermined interval with respect to the stamper. Is done. Next, in step (d), the disk is peeled off from the stamper, and in step (e), a normal reflective layer 107 made of a metal thin film having a predetermined reflectance formed by vacuum deposition or sputtering is formed on the first spacer layer 106. It is formed. Next, a protective film is formed on the normal reflective layer 107 by a process (not shown), and a label is formed on the protective film to produce an optical disk having two pits or grooves.

In the same way as for the discs having three or more layers, spacers are formed in the same manner as in steps (c) to (d) using a stamper to which pits or grooves corresponding to the respective layers are transferred following step (e) in FIG. By alternately laminating layers and reflective layers and then forming a protective film and a label, an optical disc having a multi-layered pit or groove is manufactured. As described above, a conventional optical disk having a multi-layer structure of pits or grooves was manufactured by repeating the stamper peeling process in proportion to the number of the reflective layers provided, but the reflective layer on the spacer layer or on the reflective layer was manufactured. When the spacer layer is molded, moisture may remain at the interface between the reflective layer and the spacer layer due to ambient humidity or moisture contained in the molding material. In this case, if the adhesion between the spacer layer and the reflective layer is weak, there is a drawback that when the stamper is peeled from the spacer layer, the spacer layer peels off from the reflective layer and remains on the stamper side, so that the disk cannot be easily manufactured.

In addition, since the manufactured optical disk partially peels off the spacer layer and the reflective layer due to the external environment and aging, the optical beam reflected or transmitted light path of the optical pickup that irradiates the disk is disturbed. There was a drawback that the pit could not be read.

The present invention has been made in view of the above drawbacks, and is a reproduction optical disc in which pits or grooves carrying information are formed in multiple layers, which can be stably manufactured and are resistant to external environment and aging. It is to provide.

According to the first aspect of the present invention, there is provided an optical recording medium in which a single or a plurality of spacer layers formed with pits or grooves for carrying information and a single or a plurality of reflecting layers overlap each other to form a multilayer. The layer or spacer layer comprises an optical recording medium characterized in that the surfaces overlapping each other are subjected to silane coupling treatment. According to a second aspect of the present invention, there is provided the optical recording medium according to the first aspect, wherein the reflective layer is made of a material having -OH groups, and a surface overlapping the spacer layer is subjected to silane coupling treatment. Constitute. The invention according to claim 3 is characterized in that the reflective layer is formed of an oxide film having a single layer or multiple layers, and a surface overlapping with the spacer layer is subjected to silane coupling treatment. An optical recording medium is provided.

Since the present invention is configured as described above, according to the first aspect of the present invention, when manufacturing a reproduction optical disc in which pits or grooves for carrying information are formed in multiple layers, the reflective layer that forms each layer Since the silane coupling process is performed on the surface where the spacer layer and the spacer layer overlap, the adhesion between the spacer layer and the reflective layer can be enhanced. According to the second aspect of the present invention, since each reflective layer of the optical disk according to the first aspect is made of a material having —OH groups, the reflective layer forming each layer and the spacer layer easily overlap each other. In addition, since the silane coupling treatment can be performed stably, the adhesion between the spacer layer and the reflective layer can be enhanced. According to the invention described in claim 3, since each reflective layer of the optical disk according to claim 1 is formed with a single layer or a multilayer oxide film on a surface overlapping with the spacer layer, the reflection forming each layer is formed. Since the silane coupling treatment can be easily and stably performed on the surface of the layer overlapping the spacer layer, the adhesion between the spacer layer and the reflective layer can be enhanced.

Next, a first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing a portion where pits or grooves are formed in a multilayer optical disk according to the first embodiment of the present invention, where (a) shows a case of a two-layer optical disk and (b) shows a case of a three-layer optical disk. ing. In the figure, reference numeral 1 denotes a light-transmitting substrate, and a thermoplastic resin having a predetermined light transmittance such as polycarbonate or acrylic resin by attaching a stamper having an uneven shape corresponding to a pit or groove on the surface to a mold of a molding machine. Is formed by transferring the pits or grooves of the stamper on the surface.

Reference numeral 2 denotes a first intermediate reflection layer. For example, a metal thin film or an organic dye or an inorganic dielectric such as a phthalocyanine derivative, a naphthalocyanine derivative, a spiropyran derivative, a spirooxazine derivative, or a diarylethene derivative is formed in a single layer or a plurality of layers with a predetermined thickness. The light-transmitting substrate 1 is coated on the light-transmitting substrate 1 to have a predetermined light reflectance and transmittance. The first layer pit 1a or groove 1b of the disk is formed in close contact with the light-transmitting substrate 1. . Further, an oxide film is formed on the surface of the first intermediate reflective layer 2 coated on the translucent substrate 1 by an oxidation treatment.

Reference numeral 3 denotes a first spacer layer. For example, an ultraviolet curable acrylic resin is uniformly applied on a stamper (not shown) to which the second pit or groove is transferred, and the first intermediate reflection layer 2 is applied to the stamper. It is formed by irradiating with ultraviolet rays from above the surface of the translucent substrate 1 in a state of being overlapped at a predetermined interval. In this case, the oxide film formed on the surface of the first intermediate reflective layer 2 in advance is subjected to a silane coupling process described later.

Reference numeral 4 denotes a second intermediate reflection layer, which is coated on the first spacer layer 3 in a single layer or multiple layers with a predetermined thickness using the same material as that of the first intermediate reflection layer 2 and has a predetermined light reflectance. In addition, the second pit or groove of the disk is formed in close contact with the first spacer layer 3.

Reference numeral 5 denotes a second spacer layer, which is formed on the second intermediate reflective layer 4 with a predetermined thickness using the same method as the first spacer layer 3 using an ultraviolet curable acrylic resin. Also in this case, the oxide film formed on the surface of the second intermediate reflective layer 4 is subjected to a silane coupling process described later.

Reference numeral 6 denotes a normal reflection layer. In (a), a metal such as aluminum is laminated on the first spacer layer 3 and is in close contact with the first spacer layer 3 by vacuum deposition or sputtering. Grooves are formed, and in (b), the pits or grooves of the third layer of the disk are formed by being stacked on the second spacer layer 5 and in close contact with the second spacer layer 5. Further, the protective film 103 is formed on the normal reflection layer 6 in FIG. 1 in order to prevent the deterioration and scratches of each reflection layer of the disk.

Here, the silane coupling process described above, for example, when moisture is applied to the surface of the glass substrate 7 so that the copper foil and the printed paint are in close contact with each other when the patterning of the electric circuit and the silk printing of characters are performed on the glass substrate 7. It is a hydrophobic treatment for repelling, and hexamethyldisilazane 9 as a drug is placed in a sealed container, and the glass plate to be treated is left in the gas phase treatment to form the glass substrate 7 as shown in FIG. It is obtained by replacing H of —OH group 8 present on the surface with —Si (CH ₃ ) ₃ 10. Thus, the silane coupling treatment has an effect of hydrophobizing a hydrophilic material such as a material containing —OH groups or oxides by a substitution treatment.

Examples of the agent used for the silane coupling treatment of the multilayer optical disk of FIG. 1 in the present invention include (1) vinyltriethoxysilane, (2) γ-glycidoxypropyltrimethoxysilane, and (3) γ-aminopropyltri. Ethoxysilane, (4) γ-methacryloxypropyltrimethoxysilane, (5) N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, (6) hexamethyldisilazane, (7) tetramethyldisilazane In both cases, when the reflective layer 2 or the first reflective layer 4 or the second reflective layer 6 is subjected to silane coupling treatment, -O of the oxide film on the surface of each reflective layer becomes -Si (CH3) ₃ . Substituted to be hydrophobic. Therefore, since moisture does not remain at the interface between the reflective layer 2 and the first spacer layer 3 and at the interface between the first reflective layer 4 and the second spacer layer 5, the adhesion is increased.

(1) vinyltriethoxysilane, (2) γ-glycidoxypropyltrimethoxysilane, (3) γ-aminopropyltriethoxysilane, (4) γ-methacryloxypropyltrimethoxysilane, (5) N- Since (β-aminoethyl) -γ-aminopropyltrimethoxysilane has a relatively low vapor pressure, it is dissolved in methyl alcohol, ethyl alcohol or the like in an amount of about 5 to 10% and is used after being applied to a cloth or paper towel. It can also be applied by spin coating.

In addition, (6) hexamethyldisilazane and (7) tetramethyldisilazane, which have relatively high vapor pressure, place each chemical in a sealed container and leave the substrate to be processed in the gas phase. Can be applied.

Next, a second embodiment of the present invention will be described below with reference to FIGS. FIG. 3 is a schematic sectional view showing the pits or grooves of the double-layer optical disk in the second embodiment of the present invention. In the figure, reference numeral 11 denotes a translucent substrate. By attaching a stamper to a mold of a molding machine and injection-molding polycarbonate having a refractive index of 1.569 to a thickness of about 1 mm, the pits of the stamper are transferred to the surface. ing.

Reference numeral 12 denotes a first intermediate reflection layer having four layers, a dielectric 12a made of SiO ₂ having a refractive index of 1.5 and a thickness of 1300 Å, and a dielectric made of ZnSSiO ₂ having a refractive index of 2.11 and a thickness of 924 Å. A multilayer film is formed by sequentially coating a body 12b, a dielectric 12c made of SiO ₂ having a refractive index of 1.5 and a thickness of 1300 angstroms, and a dielectric 12d made of ZnSSiO ₂ having a refractive index of 2.11 and a thickness of 924 angstroms. The first layer pits 11a and grooves 11b of the disk are formed in close contact with the translucent substrate 1. The dielectric 12d on the surface of the first intermediate reflective layer 12 has been subjected to the silane coupling process described above, and the surface of the first intermediate reflective layer 12 has hydrophobicity.

Reference numeral 13 denotes a first spacer layer, which is formed by uniformly applying, for example, an ultraviolet curable acrylic resin having a refractive index of 1.569 on a stamper (not shown) onto which a second layer of pits or grooves has been transferred. A thickness of about several tens of μm is formed by irradiating ultraviolet rays from above the surface of the translucent substrate 11 in a state where 12 is overlapped with the stamper at a predetermined interval. In this case, since the surface of the first intermediate reflective layer 12 is hydrophobic, the first spacer layer 13 and the first intermediate reflective layer 12 have a high adhesion. Reference numeral 14 denotes a normal reflective layer, which is obtained by forming aluminum on the first spacer layer 13 to a thickness of 1000 angstroms by vacuum evaporation or sputtering. Reference numeral 15 denotes a protective film made of an ultraviolet curable acrylic resin, which is usually formed on the reflective layer with a thickness of about 10 μm in order to prevent deterioration and scratches of each reflective layer of the disk. A label 16 is formed by a coating film by paper or silk printing to form an optical disk having two layers of pits or grooves.

FIG. 4 is a graph showing the measurement results of the reflectance and transmittance of the first intermediate reflective layer 12 when the thickness of the dielectric 12d is changed in the two-layer optical disk of FIG. In FIG. 4, the vertical axis represents the reflectance or transmittance, and the horizontal axis represents the thickness of the dielectric 12d. The light used for the measurement is laser light having a wavelength of 780 nm, and the reflectance 17 and the transmittance 18 in FIG. 4 are obtained by irradiation from the direction of arrow B in FIG. From the figure, when the thickness of the dielectric 12d is 924 angstroms, the reflectance 17 of the first intermediate reflective layer 12 is about 37% and the transmittance 18 is about 63%.

Therefore, the reflected light obtained by irradiating the first layer pit and the second layer pit of the optical pickup with a convergent laser beam (not shown) from above the two-layer optical disk in FIG. 3 is received by the optical receiver of the pickup. When the information is read, when the light beam is focused on the first intermediate reflection layer 12 carrying the first layer pit, the reflected light from the first layer pit is received with a reflectance of about 37%. Is done.

When the light beam is focused on the normal reflection layer 14 carrying the second layer of pits, the light irradiated from the optical pickup passes through the first intermediate reflection layer 12 with a transmittance of 63%, and then the normal reflection layer. 14 is totally reflected with a slight loss, and again passes through the first intermediate reflection layer 12 with a transmittance of 63%, and then received by the light receiver of the pickup. For this reason, the reflectance of the reflected light from the pit of the second layer obtained by the light receiver is substantially equal to the reflectance of the reflected light from the pit of the first layer.

As described above, when reading the pits carried by each layer of the two-layer optical disc in FIG. 3, the pits of each layer can be read only by selectively focusing on the pits of each layer using one optical pickup. It is not necessary to use a plurality of pickups in the multi-layer disk reader, and the structure of the reader is simplified.

In the embodiment of the present invention, an optical disk having two or three pits or grooves has been described. However, it may be composed of four or more layers as shown in FIG. In the embodiments of the present invention, the reflective layer is usually formed of aluminum, but a metal such as an aluminum-titanium alloy, gold, silver, nickel, chromium, or copper may be used. Further, each intermediate reflective layer of the multilayer disk is made of a dielectric made of an oxide, but a material having a predetermined reflectance and transmittance having an —OH group may be used. Further, each intermediate reflection layer and each spacer layer of the multilayer disc may have different reflectances and transmittances, and are appropriately selected according to the target reflectance of each layer of the disc.

Further, in the present invention, the pits or grooves carried by each layer of the multilayer disk are configured to receive and read the reflected light by irradiating the light beam of the optical pickup from one side of the disk. As shown in FIG. 6, it may be configured to read from both sides of the disk.

1 is a schematic cross-sectional view of a multilayer optical disc in a first embodiment of the present invention. It shows a state in which the glass surface is subjected to silane coupling treatment by the chemical used in the present invention to be substituted from hydrophilic to hydrophobic. It is a schematic sectional drawing of the double layer optical disk in the 2nd Example in this invention. FIG. 4 is a graph showing the measurement results of the reflectance and transmittance of the first intermediate reflective layer of the two-layer optical disk of FIG. 3 in the present invention. It is a schematic sectional drawing of the multilayer (N layer) optical disc in the other Example of this invention. It is a schematic sectional drawing of the multilayer optical disk for double-sided reading in the other Example of this invention. It is a schematic sectional drawing of the part in which the pit or groove of CD in the past was formed. The conventional manufacturing process of a two-layer optical disc is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ...... Translucent substrate 2 ... 1st intermediate | middle reflective layer 3 ... 1st spacer layer 4 ... 2nd intermediate | middle reflective layer 5 ... 2nd spacer layer 6 ... ··· Normal reflective layer 7 ··· Glass substrate 8 ··· -OH group 9 ··· Hexamethyldisilazane 10 ··· -Si (CH3) 3
11... Translucent substrate 11a... Pit 11b... Groove 12... First intermediate reflection layer 12a.. Dielectric 12b.. Dielectric 12c. 1 spacer layer 14 ... normal reflective layer 15 ... protective film 16 ... label 17 ... reflectance 18 ... transmittance 19 ... (N-2) intermediate reflective layer 20 ... (N-2) spacer layer 21 ... (N-1) intermediate reflection layer 22 ... (N-1) spacer layer 23 ... normal reflection layer 24 ... translucent substrate 25 ..Normal reflection layer 26 ... fourth spacer layer 27 ... fourth intermediate reflection layer 28 ... third spacer layer 29 ... third intermediate reflection layer 30 ... translucent substrate

Claims (3)

An optical recording medium having a multilayer in which a single or a plurality of spacer layers formed with pits or grooves for carrying information and a single or a plurality of reflective layers are alternately overlapped with each other. An optical recording medium, wherein a surface overlapping with the spacer layer is subjected to silane coupling treatment. The optical recording medium according to claim 1, wherein the reflective layer is made of a material having an —OH group, and a surface overlapping the spacer layer is subjected to silane coupling treatment. 2. The optical recording medium according to claim 1, wherein the reflective layer is formed of an oxide film having a single layer or a multilayer surface, and a surface overlapping with the spacer layer is subjected to silane coupling treatment.

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