WO2003041069A1

WO2003041069A1 - Multiple recording layer optical recording medium manufacturing method, multiple recording layer optical recording medium manufacturing apparatus, and multiple recording layer optical recording medium

Info

Publication number: WO2003041069A1
Application number: PCT/JP2002/010701
Authority: WO
Inventors: Tsuyoshi Komaki; Tetsuro Mizushima; Jiro Yoshinari
Original assignee: Tdk Corporation
Priority date: 2001-11-09
Filing date: 2002-10-15
Publication date: 2003-05-15
Also published as: JP2005141785A

Abstract

A multiple recording layer optical recording medium manufacturing method of manufacturing an optical recording medium (1) in which a plurality of layers (L1 and L0) each including a phase changing material layer (4b) to be initialized by light irradiation are formed on one side of a base (2), and a spacer layer (5) is formed between the layers (L1 and L0) includes, as an intermediate step, a step of forming the L1 layer which has a reflectance to the initializing laser beam impinging through a spacer layer (5) to be formed as an upper layer is 30% or under in the initialized state, initializing the L1 layer by irradiating the LT layer with the initializing laser beam, forming the spacer layer (5) on the initialized L1 layer, forming the L0 layer on the spacer layer (5), and initializing the L0 layer by irradiating the initializing laser beam thereon. The layers (L1 and L0) including recording layers (4 and 6) can be excellently initialized without increasing the thickness of the spacer layer (5).

Description

Itoda

Method for manufacturing multilayer recording layer type optical recording medium, apparatus for manufacturing multilayer recording layer type optical recording medium, and multilayer recording layer type optical recording medium

Technical field

The present invention relates to a multilayer recording layer type optical recording medium in which a plurality of layers each including a recording layer initialized by light irradiation are laminated on one surface side of a substrate and a spacer layer is formed between each layer. The present invention relates to a manufacturing method, an apparatus for manufacturing a multilayer recording layer type optical recording medium, and a multilayer recording layer type optical recording medium. Background art

Optical recording media are noted for their high density and large capacity, and are used for various purposes. In particular, rewritable optical recording media that allow erasing and re-recording of recorded information can be used to restore and update data, and can be repeatedly rewritten and used, contributing to expanding the use of optical recording media. It is expected to do. As this type of optical recording medium, a magneto-optical recording medium (MO) and a phase change optical recording medium have been developed and commercialized.

Among these, the applicant has already developed an optical recording medium 21 having a layer structure shown in FIG. 8 as a rewritable phase-change optical recording medium utilizing a phase change (hereinafter, also simply referred to as “optical recording medium”). are doing. The optical recording medium 21 has a structure in which a reflective layer 3, a recording layer 4, and a power layer 7 as a light transmitting layer are sequentially laminated on one surface (the upper surface in FIG. 1) of the substrate 2. ing. In this case, the base material 2 is formed into a flat plate shape (for example, a disk (disk) shape) having a predetermined thickness by injection molding using a resin material such as polycarbonate. On the surface of the substrate 2 (the upper surface in the figure), fine irregularities (not shown) such as a tracking servo group are formed at the time of molding. The reflective layer 3 is formed on the surface of the base material 2 on which fine irregularities are formed using a metal such as A1, Ag, or Ni. The recording layer 4 includes a first protective layer 4a, a phase-change material layer 4b, and a second It has a protective layer 4c, and these layers 4c, 4b, 4a are stacked on the reflective layer 3 in this order. The first protective layer 4 a and the second protective layer 4 c are formed using a dielectric material such as aluminum oxide or ZnS_Si ₂ , and the phase change material layer 4 b is formed, for example, , GeTeSb, InSbTe or AgGeInSbTe. The cover layer 7 is formed on the first protective layer 4a using a light-transmitting resin material.

In this optical recording medium 21, a recording laser beam (for example, a laser beam having a wavelength of 405 nm and set to a recording power) is irradiated onto the recording layer 4 from the cover layer 7 side, and the phase change material layer 4 b By forming a recording layer 4 containing a reversible phase change between an amorphous state and a crystalline state, recording marks are formed and erased. That is, in the recording layer 4 (particularly, the phase change material layer 4b), when the recording laser beam is irradiated, the irradiated portion is heated to a temperature equal to or higher than the melting point and then rapidly cooled (rapidly cooled). The recording mark is formed according to the recording signal. In the recording layer 4, when the recording laser beam is irradiated, the irradiated part is heated to a temperature higher than the crystallization temperature and then gradually cooled (slowly cooled) to be crystallized, thereby erasing a recording mark. Is done. On the other hand, at the time of reproduction, a laser beam for reproduction (for example, a laser beam having a wavelength of 405 nm and a lower power than that at the time of recording) is irradiated and the optical constant changes between the amorphous state and the crystalline state. The data is reproduced by determining the presence or absence of a recording mark by using the difference in the light reflectivity that changes.

When the optical recording medium 21 is manufactured, first, the base material 2 is formed into a disk shape having fine irregularities such as groups formed on its surface (one surface) by injection molding. Next, after forming the reflective layer 3 on one surface side of the base material 2, the recording layer 4 is formed on the reflective layer 3. At this time, the phase change material layer 4b and the first and second protective layers 4a and 4c are generally formed by a sputtering method. Next, the cover layer 7 is formed on the recording layer 4 by, for example, a spin coating method. In this case, the phase change material layer 4b in the recording layer 4 is in an amorphous state immediately after its formation, and Cannot be recorded. Therefore, in order to ship the optical recording medium 21 in an initialized state in which the user can immediately start using the optical recording medium 21, the recording layer 4 (particularly, the phase change material layer) is required in the manufacturing process of the optical recording medium 21. 4 b) needs to be initialized. For this reason, after forming the cover layer 7, the recording layer 4 is initialized. In this case, a high-power laser beam (hereinafter also referred to as "initialization laser beam") from the same direction as the irradiation direction of the reproduction laser beam or recording laser beam (direction from the power layer 7 side). To initialize the recording layer 4. At this time, a laser beam having a different wavelength from the recording laser beam and the reproduction laser beam is used as the initialization laser beam so that the initialization can be performed efficiently and in a short time and the production efficiency can be improved. Have been. In general, a laser beam having a wavelength of 810 nm is used as a laser beam for initialization. The laser beam for initialization has, for example, a numerical aperture NA (Numerical Aperture) of about 0.4 ( As an example, the light is irradiated onto the optical recording medium 21 through an objective lens having a value of 0.34). Thus, the manufacture of the optical recording medium 21 in which the recording layer 4 has been initialized is completed.

However, development and commercialization of an optical recording medium having a larger capacity is desired, and the applicant has developed an optical recording medium 31 having a larger capacity based on the optical recording medium 21. The optical recording medium 31 will be described with reference to FIG. Note that the same components as those of the optical recording medium 21 are denoted by the same reference numerals, and redundant description will be omitted. The optical recording medium 31 is a so-called single-sided multilayer (for example, two layers) recording layer type optical recording medium (hereinafter, also referred to as “multilayer recording layer type optical recording medium”), as shown in FIG. On one side (upper surface in the figure) of the material 2, an L1 layer including a reflective layer 3 and a recording layer 4, a spacer layer 5 as a light transmitting layer, and a recording layer 6 (hereinafter, “: L 0 layer) and a cover layer 7 as a light transmitting layer are sequentially laminated. In this case, the thickness TH of the spacer layer 5 is usually set to about 20 μιη, and fine irregularities such as groups are formed on the surface on the L0 layer side. The recording layer 6 has a first protective layer 6a, a phase change material layer 6b, and a second protective layer 6c. b and 6a are laminated in this order on the surface of the spacer layer 5 on which fine irregularities are formed. In this case, each layer 6 a, 6 b, 6 c is formed of a strictly different material or B from each corresponding layer 4 a, 4 b, 4 c, but has the same function. . The force-par layer 7 is formed on the L0 layer using a resin material.

Also in this optical recording medium 31, it is necessary to initialize the recording layers 4 and 6 during the manufacturing process. In this case, as shown in FIG. 10, after forming the cover layer 7 in the same manner as in the optical recording medium 21, the objective lens 11 is used in the same manner as in the initialization for the optical recording medium 21. And initialize. Specifically, the L1 layer including the recording layer 4 is initialized by irradiating the L1 layer from the cover layer 7 side with the initialization laser beam LIN emitted from the objective lens 11, and then, as shown in FIG. As shown, the L 0 layer is initialized by irradiating the L 0 layer with the initialization laser beam L IN. Thus, the manufacture of the optical recording medium 31 in which the first layer and the zero layer are initialized is completed. Disclosure of the invention

As a result of studying the method of manufacturing the above-described multilayer recording layer type optical recording medium, the inventors have found the following points to be improved. That is, in this manufacturing method, as shown in FIG. 10, when the L 0 layer formed on the spacer layer 5 is initialized, the initialization laser beam L IN applied to the L 0 layer is used. A part of the laser beam LPE passes through the L0 layer and the spacer layer 5 to reach the L1 layer, and a part of the laser beam LRE of the laser beam LPE is reflected by the L1 layer. In this case, interference occurs due to unevenness in the thickness of the spacer layer 5 between the reflected laser beam LRE and the initialization laser beam L IN applied to the L 0 layer. For this reason, the amount of light absorbed by the L0 layer is partially different, and as a result, the amount of heat generated differs for each portion of the L0 layer (heat generation unevenness occurs in the L0 layer). Therefore, due to the re-irradiation of the reflected laser beam LRE, the crystal state of the L0 layer, particularly the phase change material layer 6b in the recording layer 6, becomes uneven, and the L0 layer is not initialized properly. There is a possibility that this point will be improved preferable. On the other hand, it is also conceivable to initialize the L1 layer after forming the L0 layer. In this case, the initializing laser beam L IN needs to be set to a high power in consideration of the amount of absorption when passing through the L 0 layer. However, at present, it is technically difficult to manufacture a laser element capable of outputting such a high-precision initialization laser beam LIN.

On the other hand, in order to reduce the above-mentioned influence of the laser beam LRE, a manufacturing method utilizing the fact that the initialization laser beam L IN is non-parallel light focused by the objective lens 11 is considered. Specifically, in this manufacturing method, the laser beam applied to the L1 layer in a state where the initialization laser beam LIN is focused on the L0 layer by forming the spacer layer 5 to be thicker By increasing the beam diameter of the beam, the beam diameter of the laser beam LRE reflected by the L1 layer and irradiated onto the L0 layer is specified to be larger. According to this manufacturing method, since the amount of light per unit area of the laser beam LRE applied to the L0 layer due to reflection is reduced, heat generated in the L0 layer due to the irradiation of the laser beam LRE is suppressed. The occurrence of unevenness in the crystal state of the L 0 layer (particularly, the phase change material layer 6 b in the recording layer 6) due to the LRE irradiation can be avoided. However, since the thickness of the spacer layer 5 as the light transmitting layer depends on the standard of the optical recording medium 31 and the specification of the drive device, it cannot be designed freely. It is difficult to adopt. The present invention has been made in order to solve such points to be improved, and a multilayer recording layer type optical recording medium capable of satisfactorily initializing each layer including the recording layer without increasing the thickness of the spacer layer. A main object is to provide a manufacturing method and a manufacturing apparatus. Another object is to provide a multilayer recording layer type optical recording medium in which each layer is well initialized.

In the method for manufacturing a multilayer recording layer type optical recording medium according to the present invention, a plurality of layers each including a recording layer initially formed by light irradiation are formed on one surface side of a base material, and a gap is formed between the respective layers. Manufacturing method for manufacturing a multilayer recording layer type optical recording medium having a base layer formed thereon And forming, as an intermediate step, one layer in which the light reflectance with respect to an initialization laser beam incident through the spacer layer as an upper layer is 30% or less in an initialized state. Irradiating the formed one layer with the laser beam for initialization to initialize the laser beam, forming the spacer layer on the initialized layer, and forming the spacer layer on the formed layer. Forming the other layer, and irradiating the formed other layer with the initialization laser beam to initialize the other layer. Further, in the apparatus for manufacturing a multilayer recording layer type optical recording medium according to the present invention, a plurality of layers each including a recording layer initialized by light irradiation are formed on one surface side of the base material, and a space is formed between the respective layers. 1. A manufacturing apparatus for manufacturing a multilayer recording layer type optical recording medium having a semiconductor layer formed thereon, wherein an optical reflectance with respect to an initializing laser beam incident through the spacer layer as an upper layer is initially set. A first layer forming apparatus for forming one layer that is 30% or less in an initialized state, and a first initializing step of irradiating the formed one layer with the initialization laser beam to initialize the layer. Device, a spacer layer forming device for forming the spacer layer on the initialized layer, and a second layer forming for forming another layer on the formed spacer layer Initialization of the device and other layers formed And a second initialization device for irradiating a laser beam for initialization.

In the method and apparatus for manufacturing a multilayer optical recording medium, when manufacturing a multilayer recording layer type optical recording medium, as an intermediate step, light reflection with respect to an initialization laser beam incident through a spacer layer is performed. One layer having a ratio of 30% or less in the initialized state is formed, and the formed one layer is initialized by irradiating a laser beam for initialization, and a spacer is formed on the initialized layer. One layer is formed by forming a layer, forming another layer on the formed spacer layer, and irradiating the formed other layer with a laser beam for initialization. It is possible to reliably avoid the occurrence of unevenness in the initialization state in another layer due to the above-described interference between the reflected initialization laser beam and the initialization laser beam passed through another layer. . As a result, It is possible to manufacture a high-quality multilayer recording layer type optical recording medium in which each layer including the recording layer is uniformly and satisfactorily initialized without increasing the thickness of the laser layer.

In the method for manufacturing a multilayer recording layer type optical recording medium according to the present invention, a plurality of layers each including a recording layer initialized by light irradiation are formed on one surface side of a base material, and a spacer layer is interposed between the respective layers. A method for manufacturing a multilayer recording layer type optical recording medium, wherein a light reflectance for an initialization laser beam incident through the spacer layer as an upper layer is determined as an intermediate step. Forming one of the layers having an initial state of 30% or less, forming the spacer layer on the formed one layer, and forming the spacer layer on the formed layer; Initializing by irradiating the laser beam for initialization through a spacer layer, forming another layer on the formed spacer layer, and performing initialization on the formed other layer Initialize by irradiating laser beam for Process.

Further, in the apparatus for manufacturing a multilayer recording layer type optical recording medium according to the present invention, a plurality of layers each including a recording layer initialized by light irradiation are formed on one surface side of the base material, and a space is formed between the respective layers. 1. A manufacturing apparatus for manufacturing a multilayer recording layer type optical recording medium having a semiconductor layer formed thereon, wherein an optical reflectance with respect to an initializing laser beam incident through the spacer layer as an upper layer is initially set. A first layer forming apparatus for forming one layer that is 30% or less in an activated state; a spacer layer forming apparatus for forming the spacer layer on the formed one layer; A first initialization device that initializes the formed one layer by irradiating the initialization laser beam through the formed spacer layer, and on the formed spacer layer; A second layer forming apparatus for forming the other layer, It is constituted by a second initialization device for initializing by irradiating a laser beam for the initialization to the other layers and the formation.

In the method and apparatus for manufacturing a multilayer optical recording medium, when manufacturing a multilayer recording layer type optical recording medium, as an intermediate step, light reflection with respect to an initialization laser beam incident through a spacer layer is performed. One layer whose ratio is less than 30% A spacer layer is formed on one of the formed layers, and the formed one layer is initialized by irradiating an initialization laser beam through the spacer layer to initialize the layer. Another layer is formed on the formed spacer layer, and the formed other layer is irradiated with a laser beam for initialization to initialize the laser beam. It is possible to reliably avoid the occurrence of unevenness in the initialization state in the other layer due to the above-described interference between the laser beam for initialization and the laser beam for initialization passed through the other layer. As a result, it is possible to manufacture a high-quality multilayer recording layer type optical recording medium in which each layer including the recording layer is uniformly and satisfactorily initialized without increasing the thickness of the spacer layer.

In this case, in the method for manufacturing a multilayer optical recording medium, it is preferable that the light reflectance of the one layer with respect to one recording laser beam and one reproduction laser beam is set to 20% or more. Further, in the apparatus for manufacturing a multilayer optical recording medium, the first layer forming device forms the light reflectance of the one layer with respect to the recording laser beam and the reproducing laser beam to be 20% or more. It is preferable that it is comprised so that it may perform. With this configuration, it is possible to effectively prevent an error from occurring when recording and reproducing data by the recording and reproducing apparatus owned by the user.

Further, in the method for producing a multilayer optical recording medium, light having a wavelength of less than 500 nm is used as the recording laser beam and the reproducing laser beam, and the wavelength is 500 nm as the initialization laser beam. It is preferable to use light having a wavelength of 1000 nm or less. Further, it is preferable that the recording layer is formed of a phase change material. Further, in the apparatus for manufacturing a multilayer optical recording medium, light having a wavelength of less than 500 nm is used as the recording laser beam and the reproducing laser beam, and the first and second initialization devices include: It is preferable that the laser beam for initialization is configured to use light having a wavelength of 500 nm or more and 100 nm or less. Further, it is preferable that the first and second layer forming apparatuses are configured to form the recording layer using a phase change material. In a multilayer recording layer type optical recording medium according to the present invention, a plurality of layers each including a recording layer initialized by light irradiation are formed on one surface side of a base material, and a spacer layer is provided between the respective layers. Is a multi-layer recording layer type optical recording medium in which a layer other than an uppermost layer of the plurality of layers is initialized through the spacer layer as an upper layer. The light reflectance for the laser beam for use is less than 30% in the initialized state.

In this multilayer recording layer type optical recording medium, a plurality of layers each including a recording layer initialized by light irradiation are formed on one surface side of the base material, and a spacer layer is formed between each layer. In a multilayer recording layer type optical recording medium, the light reflectance for the initialization laser beam incident through the spacer layers of the other layers except the uppermost layer among the plurality of layers is 30% in the initialized state. With the following formation, the amount of irradiation by the initialization laser beam reflected by a layer that is one layer farther than the initialization target layer can be sufficiently reduced, so that regardless of the thickness of the spacer layer, Thus, it is possible to provide a high-quality multilayer recording layer type optical recording medium in which each layer including the recording layer is uniformly and satisfactorily initialized.

In this case, the plurality of layers are so adjusted that the light reflectance with respect to the recording laser beam and the reproduction laser beam incident through the spacer layer as the upper layer is 20% or more in the initialized state. It is preferable that other layers except the uppermost layer are formed. With such a configuration, data can be satisfactorily recorded by the recording / reproducing apparatus owned by the user, and the recorded data can be satisfactorily reproduced.

Further, light having a wavelength of less than 500 nm is used as the recording laser beam and the reproducing laser beam, and the other layers except the top layer among the plurality of layers have wavelengths of 500 nm or more. It is preferable that the laser beam has been initialized with the above-mentioned laser beam for initialization of 100 nm or less. Further, it is preferable that the recording layer is formed of a phase change material. This disclosure relates to the subject matter included in Japanese Patent Application No. 2001-344179 filed on November 9, 2001, and all of these disclosures are expressly incorporated herein by reference. . BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view showing a schematic configuration of a multilayer (two-layer) recording layer type optical recording medium 1 according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of the manufacturing apparatus 200 for the optical recording medium 1.

FIG. 3 is an explanatory diagram for explaining the effect on the L0 layer due to the irradiation of the laser beam LRE reflected by the L1 layer when initializing the optical recording medium 1 on which the L1 layer and the L0 layer are formed. It is.

Fig. 4 shows the simulation results when the light reflectivity of the L1 layer in the optical recording medium 1 was variously changed and the quality of initialization of the L0 layer in each optical recording medium 1 was simulated. It is a simulation result explanatory view.

FIG. 5 is an explanatory diagram showing conditions for a simulation corresponding to the simulation results shown in FIG.

Figure 6 shows various changes in the thickness of the L1 layer in the optical recording medium 1, and the L1 layer with respect to the initialization laser beam LIN (wavelength: 810 nm) when the L1 layer is in the initialized state (crystalline state). FIG. 9 is an explanatory diagram of simulation results showing simulation results when simulating the characteristics of the light reflectance of FIG.

FIG. 7 shows various changes in the thickness of the L 1 layer in the optical recording medium 1 for both the L 1 layer in the initialized state (crystalline state) and the uninitialized state (amorphous state). FIG. 9 is an explanatory diagram of simulation results showing simulation results when simulating the characteristics of the light reflectance of the L1 layer with respect to a recording / reproducing laser beam (wavelength: 405 nm).

FIG. 8 is a cross-sectional view showing a schematic configuration of a conventional single-layer recording layer type optical recording medium 21. FIG. 9 is a cross-sectional view showing a schematic configuration of a multilayer (two-layer) recording layer type optical recording medium 31 that has been already developed by the applicant.

FIG. 10 is a view for explaining the influence on the L0 layer due to the irradiation of the laser beam LRE reflected by the L1 layer when the optical recording medium 31 on which the L1 layer and the L0 layer are formed is initialized. FIG. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of a multilayer recording layer type optical recording medium, a method of manufacturing the same, and a manufacturing apparatus according to the present invention will be described with reference to the accompanying drawings. Note that components having the same structures as those of the optical recording media 21 and 31 described above are denoted by the same reference numerals and redundant description is omitted.

First, the configuration of a multilayer recording layer type optical recording medium (hereinafter, also referred to as “optical recording medium”) 1 in the present invention will be described with reference to FIG.

As shown in FIG. 1, the optical recording medium 1 has a surface on which fine irregularities are formed on the substrate 2 (the ± surface in FIG. 1).

) Side, an L1 layer, a spacer layer 5, an L0 layer, and a cover layer 7 are sequentially laminated.

In this case, the L1 layer is composed of the reflective layer 3 and the recording layer 4, and has a laser beam for initialization (wavelength within the range of 500 nm to 100 nm, hereinafter 810 nm as an example). ) Is formed to have a light reflectance of 3% or more and 30% or less, more preferably 5% or more and 25% or less. The light reflectance in the present invention refers to a state in which the spacer layer 5 is formed as an upper layer on a layer (for example, the L1 layer) and the layer (the L1 layer in this example) is initialized. Means the reflectance when the laser beam for initialization is irradiated from the spacer layer 5 side. That is, the reflectivity of this layer (the L1 layer in this example) changes depending on what layer is present on the layer closest to the incident light (specifically, the first protective layer 4a). This is the layer that is in contact with the layer closest to the incident light. This is due to the difference in the refractive index difference. Specifically, the refractive index of the recording layer (first protective layer 4a) is 2.25, the refractive index of the spacer layer 5 is about 1.6, and the refractive index of air is 1. 0, the refractive index difference between the recording layer (first protective layer 4a) and the spacer layer 5 is about 0.65, and the refractive index difference between the recording layer (first protective layer 4a) and air is It is about 1.25. Therefore, depending on the method of measuring the reflectivity, the influence of the surface reflection of the spacer layer 5 is included, so that even when the reflectivity of the layer (L1 layer) itself is, for example, 30%, the actual reflectivity is measured. Measurements can exceed 30%. For example, in the above example, since the refractive index of the spacer layer 5 is 1.6, the surface reflection is about 5%, and the actual measured value is about 35%. Therefore, in the measurement method including the surface reflection, when the refractive index of the spacer layer 5 is known, it is necessary to subtract the surface reflection from the measured value. On the other hand, it is also possible to measure by focusing on the L1 layer without being affected by surface reflection. For this measurement, a photometer with an optical system capable of focusing on that layer (L1 layer) or It can be measured by an evaluation device.

Next, the manufacturing apparatus 200 for the optical recording medium 1 will be described with reference to FIG. The manufacturing apparatus 200 includes a reflective layer forming apparatus 101, a recording layer forming apparatus (first layer forming apparatus) 102, an initializing apparatus (first initializing apparatus) 103, a spacer layer forming apparatus 201, and a recording layer. The apparatus includes a forming apparatus (second layer forming apparatus) 202, an initializing apparatus (second initializing apparatus) 203, and a light transmitting layer forming apparatus 104. In this case, the reflective layer forming apparatus 101 includes a reflective layer forming chamber 101a and a sputtering apparatus 101b disposed in the reflective layer forming chamber 101a. It has a function of forming the reflective layer 3 on the surface by the sputtering device 101b. The recording layer forming apparatus 102 includes a recording layer forming chamber 102a and a sputtering apparatus 102b disposed in the recording layer forming chamber 102a, and is provided on the surface of the base material 2 carried into the recording layer forming chamber 102a. It has a function of forming the recording layer 4 by the sputtering device 102b. The initialization device 103 includes a rotation mechanism 103a for rotating the base material 2 and an initialization laser driven by a tracking mechanism (not shown) along a group formed on the base material 2. A pickup 103 b for irradiating the substrate 2 with one beam LIN, and a function of initializing the recording layer 4 formed on the surface of the substrate 2. The spacer layer forming apparatus 201 includes a rotating mechanism 2 O la for rotating the substrate 2, a dropping mechanism for the coating liquid R 1 (not shown), a transparent stamper 201 b and an ultraviolet irradiation mechanism (not shown). ), And has a function of forming a spacer layer 5 as a light transmitting layer on the surface of the substrate 2 by a spin coating method. The recording layer forming apparatus 202 includes a recording layer forming chamber 202a and a sputtering apparatus 202b disposed in the recording layer forming chamber 202a. It has a function of forming the recording layer 6 on the surface of the loaded base material 2 with a sputtering device 202b. The initialization device 203 includes a rotation mechanism 203 for rotating the substrate 2 and an initialization laser beam L IN along a group formed on the substrate 2 by being driven by a tracking mechanism (not shown). And a function of initializing the recording layer 6 formed on the surface of the substrate 2. The light-transmitting layer forming device 104 includes a rotation mechanism 104 for rotating the base material 2, a dropping mechanism 104 b for the coating liquid R, and an ultraviolet irradiation mechanism (not shown). In addition, it has a function of forming a power par layer 7 as a light transmitting layer by a spin coating method.

Next, a method for manufacturing the optical recording medium 1 will be described.

First, the base material 2 is formed into a disk shape having fine irregularities such as groups formed on its surface (one surface) by injection molding. Next, after the reflective layer 3 is formed on one surface side of the base material 2 by the reflective layer forming device 101, the recording layer 4 is formed on the reflective layer 3 by the recording layer forming device 102. At this time, the phase change material layer 4b is formed by, for example, a sputtering method. Further, the L1 layer is formed such that the light reflectance with respect to the initialization laser beam LIN incident via the spacer layer 5 is 30% or less in the initialized state. Specifically, the film thickness thereof formed to a thickness which is described below with reference to the dielectric of the first protective layer 4 a of L 1 layer e.g. Sani匕aluminum or Z n S- S I_〇 _2, etc. .

Next, a laser beam for recording and a laser for reproduction were applied to the formed L1 layer. The initializing device 103 irradiates the laser beam LIN for initialization from the same direction as the irradiation direction of the laser beam (hereinafter, both laser beams are also collectively referred to as “recording / reproducing laser beam”). Initialize the L1 layer containing the layer (specifically, the L1 layer containing the phase change material layer 4b). At this point, without initializing the L1 layer, after forming the spacer layer 5 on the L1 layer by the spacer layer forming apparatus 201, the L1 layer is formed as described later. The initialization can be performed by the initialization device 103.

Next, for example, a 2P method using a transparent stamper 201b is performed by a spacer layer forming apparatus 201 to form a spacer layer 5 having a thickness TH of, for example, 20 on the L1 layer. To achieve. In this case, a resin material having a light transmitting property (coating solution R 1) is dropped on the surface of the base material 2 on which the recording layer 4 is formed, and the resin material is applied onto the first protective layer 4 a by spin coating. After being applied in the form of a thin film, a transparent stamper 201b for forming fine unevenness such as a group is placed on the applied resin material in an uncured state. Thereafter, the resin material is cured by irradiating ultraviolet rays, and then the transparent stamper 201b is removed. At this time, fine irregularities are formed on the upper surface of the spacer layer 5 by the fine irregularities formed on the surface of the transparent stamper 201b. At this point, the L1 layer can be initialized as described above. Next, the L0 layer is formed on the surface of the spacer layer 5 on which the fine unevenness is formed by the recording layer forming apparatus 202. At this time, the L0 layer is formed by, for example, a sputtering method.

Next, the formed L0 layer is irradiated with the initialization laser beam LIN by the initialization device 203 from the same direction as the irradiation direction of the recording / reproducing laser beam, and the L0 layer including the recording layer 6 is irradiated. Initialize layer 0. At this time, as shown in FIG. 3, a part of the initialization laser beam L IN irradiating the L 0 layer from the lens 11 in the pickup 203 b to the L 0 layer is L 0 Layer and spacer layer 5 to reach layer L1. Further, a part of the laser beam LRE of the laser beam LPE that has reached the L1 layer is reflected by the L1 layer (in particular, the reflection layer 3 in the L1 layer) to irradiate the L0 layer. In this case, the initialized L1 layer laser beam Since the reflectance is 30% or less, the light amount of the laser beam LRE irradiating the L0 layer is reduced to at least 30% or less based on the light amount of the laser beam LPE passing through the L0 layer. Here, the formation of the L1 layer, the initialization of the L1 layer, the formation of the spacer layer 5, the formation of the L0 layer, and the initialization of the L0 layer correspond to intermediate steps in the present invention. Finally, the cover layer 7 is formed on the initialized L 0 layer using, for example, a spin coat method using the light transmitting layer forming apparatus 104. Specifically, a resin material (coating liquid R) of a light-transmitting resin is dropped on the L0 layer of the base material 2 by a dropping mechanism 104b, and then the rotating mechanism 104a is operated. The resin material is applied in a thin film on the L0 layer by rotating the base material 2 (by spin coating), and then the resin material is cured by irradiating ultraviolet rays. Thus, the manufacture of the optical recording medium 1 is completed. Note that a manufacturing method in which the force-par layer 7 is formed after the formation of the L0 layer and the L0 layer is initialized thereafter may be employed.

In this case, the inventor changed the film thickness of the first protective layer 4a constituting the L1 layer to change the optical recording medium when the light reflectance of the L1 layer with respect to the initialization laser beam LIN was changed. The quality of the initialization of the L 0 layer for the body 1 was simulated. Figure 4 shows the results of this simulation. Further, an example in which the first protective layer 4a in the spacer layer 5 and the L1 layer at the time of performing this simulation was manufactured to a predetermined thickness, the phase change material layer 4b in the L1 layer, and the first protective layer 4a in the L1 layer. FIG. 5 shows each refractive index, each optical extinction coefficient, and each film thickness of the 2 protective layer 4c, the reflective layer 3, and the substrate 2.

According to the simulation results shown in FIG. 4, when the light reflectance of the L1 layer with respect to the initialization laser beam L IN is set to 30% or less, the initialization state is determined to be good. When the rate is set to 31% or more, the initialization state becomes a result of the failure judgment. Therefore, as is clear from the simulation results, by setting the light reflectance of the L1 layer to the initialization laser beam IN to 30% or less, the portion of the recording layer 6 that is initialized and its surroundings is set. The result of the above interference based on the re-irradiation of the laser beam L RE to the already initialized part The occurrence of unevenness in the crystal state can be reliably avoided, and as a result, the L0 layer including the recording layer 6 can be uniformly and satisfactorily initialized.

The inventor has also simulated the relationship between the film thickness of the first protective layer 4a constituting the L1 layer and the light reflectance of the L1 layer with respect to the initialization laser beam LIN. Is shown in FIG. According to this simulation result, when using the dielectrics, such as, for example, Z n S- S i 0 ₂ as a main material of the first protective layer 4 a constituting the L 1 layer, the first protective layer in the L 1 layer By setting the thickness of 4a within the range of about 96 nm to about 159 nm (the range indicated by A in the figure), the L1 layer is initialized in the initialized state (crystalline state). The light reflectance of the L1 layer with respect to the laser beam LIN can be set to 30% or less.

Also, as the optical recording medium 1, a recording / reproducing device (a laser beam for recording / reproducing is emitted from an objective lens having an aperture of about 0.85) used by a user is used to form the L1 layer. It is necessary to be able to record and play back recorded data well. In this case, the inventor has determined that the recording / reproducing apparatus has a small variation depending on the characteristics of the recording / reproducing device, but the wavelength is not less than 395 nm and not more than 415 nm (for example, 405 m). By ensuring that the light reflectance of the L1 layer is at least 20% (preferably 30%), good focus characteristics can be obtained, and the data recorded on the L1 layer can be recorded and reproduced well. Verify that they can do it. In this case, the “light reflectance of the L1 layer” is, as described above, a layer on the incident side of the recording / reproducing laser beam with respect to the spacer layer 5 (for example, the L0 layer or the cover layer 7). Is the light reflectance measured when the force is adjusted to the L1 layer via the spacer layer 5 in a state where the influence of Means light reflectance without considering the effects of decay. The inventor of the present invention has sought to find out the film thickness condition of the first protective layer 4a in the L1 layer in order to secure the light reflectance of the L1 layer with respect to the recording / reproducing laser beam of 20% or more. The relationship between the film thickness and the light reflectance of the L1 layer with respect to the recording / reproducing laser beam was simulated. The simulation Figure 7 shows the results. According to this simulation result, the thickness of the first protective layer 4a in the L1 layer is in the range of about 0 nm to about 12 nm (within the range indicated by B1 in the figure) and about 36 nm to about 36 nm. Either within the range of 102 nm (within the range indicated by B2 in the figure) or within the range of about 1261111 to about 192nm (within the range indicated by B3 in the figure). It is understood that, by setting the L 1 layer, in the initialized state (crystal state) of the L 1 layer, the light reflectance of the L 1 layer with respect to one recording / reproducing laser beam can be secured to 20% or more. Therefore, in order to be able to perform good initialization using the laser beam LIN for initialization at the time of manufacturing the optical recording medium 1 and to be able to record and reproduce data satisfactorily by the recording / reproducing device used by the user, If the thickness of the first protective layer 4a constituting the L1 layer is set to any one of the overlapping ranges of the range A in FIG. 6 and the range B1, the range B2 or the range B3 in FIG. Good. That is, since there is no overlap between the range A and the range B1, any film thickness in the range C1 of about 96 nm to about 102 nm, which is the overlap of the range A and the range B2, or the range A Approximately 1 26 which is the overlap of ! ! ! ! The film thickness may be set to an arbitrary value within the range C2 of about 59 nm. Furthermore, according to FIGS. 6 and 7, even within these ranges C l and C 2, the light reflectance of the L1 layer with respect to the initialization laser beam L IN is lower, and the recording / reproducing laser From the viewpoint that it is preferable that the light reflectance of the L1 layer for one beam is higher, the thickness of the first protective layer 4a constituting the L1 layer should be in the range of 137 nm to 145 nm, preferably 140 nm. It can be said that setting to about nm is most preferable. When there is another such overlapping range, within the other range, the light reflectance of the L1 layer with respect to the initialization laser beam L IN is lower, and the recording / reproducing laser beam has a lower reflectance. It is also possible to set an arbitrary film thickness with a higher light reflectance of the L1 layer.

As described above, according to the manufacturing method and the manufacturing apparatus 200 of the optical recording medium 1, the light reflectance of the L1 layer with respect to the initialization laser beam LIN is set to 30% or less. During initialization, the laser beam that has passed through the L0 layer The light amount of the laser beam LRE reflected by the L1 layer can be reduced to 30% or less of the light amount of the laser beam LPE when passing through the L0 layer. Therefore, without increasing the thickness of the spacer layer 5, it is possible to reliably avoid the occurrence of the crystal state unevenness due to the re-irradiation of the laser beam LRE in the LO layer. It can be initialized well. Also, by ensuring that the light reflectance of the L1 layer with respect to the recording / reproducing laser beam is 20% or more, data recorded on the L1 layer can be recorded and reproduced satisfactorily.

It should be noted that the present invention is not limited to the above-described embodiment of the invention, and can be appropriately modified. For example, in the embodiment of the present invention, an example has been described in which the thickness of the first protective layer 4a in the L1 layer is changed to change the light reflectance of the L1 layer, but the present invention is not limited to this. For example, by appropriately selecting the material of the first protective layer 4a and setting its refractive index to a predetermined value, the light reflectance of the L1 layer can be set to the above-mentioned specified value. In this case, the light reflectivity of the L1 layer depends on the interference condition of light between the layers constituting the L1 layer, and the interference condition of the light depends on the optical path length of each layer. The relationship is equal to the value obtained by multiplying the refractive index of the layer by the film thickness. For this reason, while the film thickness of the first protective layer 4a is kept constant, for example, when the refractive index is changed by changing the material, the light reflectance also varies with the refractive index of the first protective layer 4a described above. It is almost the same as when the film thickness is changed while maintaining the constant. Therefore, the optimum refractive index can be obtained in the same manner as in the simulation described above. By forming the first protective layer 4a to have this refractive index, the laser beam LRE on the recording layer 6 is re-irradiated. Therefore, it is possible to reliably and uniformly initialize the L 0 layer including the recording layer 6 because the occurrence of the unevenness in the crystal state caused by the above can be avoided. Further, even if the film thickness and material of the second protective layer 4c are appropriately changed, that is, the refractive index is appropriately changed, the same operation and effect as when the refractive index of the first protective layer 4a is changed can be obtained. be able to. Further, the light reflectance of the L1 layer is also affected by the material (refractive index) of the spacer layer 5. Therefore, the light reflectance of the L1 layer may be changed by changing the material of the spacer layer 5. Further, in the embodiment of the present invention, the example in which the optical recording medium 1 of the two-layer recording layer type optical recording medium having the two recording layers 4 and 6 is described, but the formation of the spacer layer 5 By repeating the formation of the recording layer 6 and the initialization for the recording layer 6, a multilayer recording layer type optical recording medium having three or more recording layers and each recording layer uniformly initialized is manufactured. Can also. The manufacturing apparatus in this case is configured by increasing the spacer layer forming apparatus 201, the recording layer forming apparatus 202, and the initializing apparatus 203 in the manufacturing apparatus 200 by the number of times of repetition. For example, when manufacturing a three-layer recording layer type optical recording medium in which an L2 layer, an L1 layer, and an L0 layer having substantially the same structure as the L1 layer of the optical recording medium 1 are sequentially laminated on the substrate 2, The method includes forming the L2 layer on the substrate 2, initializing the L2 layer, forming the spacer layer 5, forming the L1 layer, initializing the L1 layer, forming the spacer layer 5, Each step of forming the L0 layer, initializing the L0 layer, forming the force-par layer 7, or forming the L2 layer on the base material 2, forming the spacer layer 5, initializing the L2 layer, The steps of forming the L1 layer, forming the spacer layer 5, initializing the L1 layer, forming the L0 layer, forming the cover layer 7, and initializing the L0 layer are sequentially performed. In this case, the L1 layer should be initialized uniformly and well by setting the light reflectance of the L2 layer to the initialization laser beam LIN to 30% or less. Can be. Further, with regard to the initialization of the L0 layer, the L0 layer can be uniformly and satisfactorily initialized by setting the light reflectance of the L1 layer with respect to the initialization laser beam LIN to 30% or less. In this case, the first protective layer (4a or 6a) and the second protective layer other than the layer farthest from the incident light (L0 layer for two layers, L0 layer and L1 layer for three layers) A metal layer can be used as a part of the protective layer (4c or 6a), and the present invention can be applied to this configuration. Further, a ROM layer can be included in a plurality of layers in the multilayer recording layer type optical recording medium according to the present invention, and it is not necessary to initialize all of the plurality of layers, and any one of the layers can be initialized. You may.

On the other hand, for initialization of the L0 layer, the L0 layer is irradiated not only with the L1 layer but also with the initialization laser beam LIN reflected by the L2 layer. However Since the distance between the L0 layer and the L2 layer is almost twice as large as the distance between the L0 and L1 layers, the amount of light reflected by the L2 layer is To 1Z4. In addition, the light reflected by the L2 layer passes through the L1 layer twice after passing through the L0 layer and before being reflected by the L2 layer and reaching the L0 layer. Therefore, the amount of light reflected by the L2 layer is a value obtained by further multiplying the value reduced to 1/4 by the square coefficient of the transmittance of the L1 layer. Therefore, the amount of light reflected by the L2 layer is negligible compared to the light reflected by the L1 layer, and only the light reflected by the L1 layer needs to be considered when initializing the LO layer. That is, when a single layer is initialized in a multilayer recording layer type optical recording medium, only the influence of reflected light by a layer farther from the incident light than the one to be initialized needs to be considered. The light reflectance for the initialization laser beam LIN in the layer far from the incident light may be set to 30% or less.

Further, in the embodiment of the present invention, the light reflectance of the L1 layer with respect to the initialization laser beam LIN is specified to a specific predetermined value, but the L1 layer with respect to the initialization laser beam LIN is specified. From the viewpoint that the light reflectivity is preferably lower and the light reflectivity of the L1 layer with respect to the recording / reproducing laser beam is preferably higher, the L1 layer with respect to the initialization laser beam LIN is preferred. It is also possible to adopt a configuration in which the light reflectance of the layer 1 is formed to be lower than the light reflectance of the L1 layer with respect to the recording / reproduction laser beam. Industrial applicability

As described above, according to the method for manufacturing a multilayer recording layer type optical recording medium according to the present invention, when manufacturing the multilayer recording layer type optical recording medium, the light is incident via the spacer layer as an intermediate step. A single layer having a light reflectance of 30% or less in the initialized state with respect to the initializing laser beam is formed, and the formed one layer is irradiated with the initializing laser beam to be initialized. A spacer layer is formed on the formed layer, another layer is formed on the formed spacer layer, and an initialization is performed on the formed other layer. By irradiating with a laser beam and initializing, in the other layer caused by the above-described interference between the initializing laser beam reflected by one layer and the initializing laser beam passing through another layer, The occurrence of unevenness in the initialized state can be reliably avoided. Therefore, a multilayer recording layer type optical recording medium capable of producing a high quality multilayer recording layer type optical recording medium in which each layer including the recording layer is uniformly and satisfactorily initialized without increasing the thickness of the spacer layer. A manufacturing method is realized.

Claims

The scope of the claims

1. A multilayer recording layer type optical recording medium in which a plurality of layers each including a recording layer initialized by light irradiation is formed on the surface side of a base material and a spacer layer is formed between the respective layers. A manufacturing method for manufacturing,

Forming, as an intermediate step, one layer having a light reflectance of 30% or less in an initialized state with respect to an initializing laser beam incident through the spacer layer as an upper layer,

Irradiating the laser beam for initialization to the formed one layer to initialize,

Forming the spacer layer on the initialized layer;

Forming another layer on the formed spacer layer,

A method for manufacturing a multilayer recording layer type optical recording medium, comprising a step of irradiating the formed other layer with the laser beam for initialization to initialize the layer.

2. A multilayer recording layer type optical recording medium in which a plurality of layers each including a recording layer initialized by light irradiation is formed on the surface side of the base material and a spacer layer is formed between the respective layers. A manufacturing method for manufacturing,

Forming the spacer layer on the formed one layer,

Initializing the formed one layer by irradiating the laser beam for initialization through the formed spacer layer,

Forming another layer on the formed spacer layer,

3. The recording laser beam and the reproduction laser beam of the one layer 2. The method for producing a multilayer recording layer type optical recording medium according to claim 1, wherein the optical reflectance is set to 20% or more.

3. The method of manufacturing a multilayer recording layer type optical recording medium according to claim 2, wherein a light reflectance of the one layer with respect to a recording laser beam and a reproducing laser beam is set to 20% or more.

5. Light having a wavelength of less than 500 nm is used as the recording laser beam and the reproducing laser beam, and light having a wavelength of 500 nm or more and 100 nm or less is used as the initialization laser beam. 4. The method for producing a multilayer recording layer type optical recording medium according to claim 3, wherein:

6. 500 n as the recording laser beam and the reproduction laser beam

The method according to claim 4, wherein light having a wavelength less than Hi is used, and light having a wavelength of 500 nm or more and 100 nm or less is used as the initialization laser beam.

7. The method for manufacturing a multilayer recording layer type optical recording medium according to claim 1, wherein the recording layer is formed of a phase change material.

8. The method for producing a multilayer recording layer type optical recording medium according to claim 2, wherein the recording layer is formed of a phase change material.

9. A multilayer recording layer type optical recording medium in which a plurality of layers each including a recording layer initialized by light irradiation are formed on the surface side of the base material and a spacer layer is formed between the respective layers. A manufacturing apparatus for manufacturing,

A first layer forming apparatus for forming one layer in which the light reflectance with respect to an initialization laser beam incident through the spacer layer as an upper layer is 30% or less in an initialized state; ,

A first initialization device that initializes the formed one layer by irradiating the initialization laser beam with the laser beam;

A spacer layer forming apparatus for forming the spacer layer on the initialized layer, A second layer forming apparatus for forming another layer on the formed spacer layer, and a second layer for irradiating the formed other layer with the initialization laser beam for initialization. An apparatus for manufacturing a multilayer recording layer type optical recording medium, comprising: an initialization apparatus.

10. A multilayer recording layer type optical recording medium in which a plurality of layers each including a recording layer initialized by light irradiation is formed on one surface side of a base material and a spacer layer is formed between the respective layers. A manufacturing apparatus for manufacturing,

A spacer layer forming apparatus for forming the spacer layer on the formed one layer; and the initialization laser beam to the formed one layer via the formed spacer layer. An i-th initialization device for irradiating and initializing;

A second layer forming apparatus for forming another layer on the formed spacer layer, and a second layer for irradiating the formed other layer with the initialization laser beam to initialize the other layer An apparatus for manufacturing a multilayer recording layer type optical recording medium, comprising: an initialization apparatus.

11. The first layer forming apparatus forms the one layer with a light reflectance of 20% or more with respect to a recording laser beam and a reproducing laser beam.

12. The first layer forming apparatus according to claim 10, wherein the first layer forms a light reflectance of at least 20% with respect to a recording laser beam and a reproducing laser beam.

13. Light having a wavelength of less than 500 nm is used as the recording laser beam and the reproducing laser beam, and the first and second initialization devices have a wavelength of 500 as the initialization laser beam. The apparatus for manufacturing a multilayer recording layer type optical recording medium according to claim 11, wherein light having a wavelength of 0 nm or more and 100 nm or less is used.

14. Light having a wavelength of less than 500 nm is used as the recording laser beam and the reproduction laser beam, and the first and second initialization devices have wavelengths as the initialization laser beam. 13. The apparatus for manufacturing a multilayer recording layer type optical recording medium according to claim 12, wherein light having a wavelength of 500 nm or more and 100 nm or less is used.

15. The apparatus for manufacturing a multilayer recording layer type optical recording medium according to claim 9, wherein the first and second layer forming apparatuses form the recording layer using a phase change material.

16. The apparatus for manufacturing a multilayer recording layer type optical recording medium according to claim 10, wherein the first and second layer forming apparatuses form the recording layer using a phase change material.

17. Multilayer recording layer type optical recording medium in which a plurality of layers each including a recording layer initialized by light irradiation are formed on one surface side of a base material and a spacer layer is formed between the respective layers. So,

Of the plurality of layers, the layers other than the uppermost layer have a light reflectance of 30% in the initialized state with respect to the initialization laser beam incident through the spacer layer as an upper layer. A multilayer recording layer type optical recording medium formed below.

18. The other layers of the plurality of layers except the uppermost layer have a light reflectance with respect to a recording laser beam and a reproducing laser beam incident through the spacer layer as an upper layer. 18. The multilayer recording layer type optical recording medium according to claim 17, wherein the optical recording medium is formed at 20% or more in an initialized state.

19. Light having a wavelength of less than 500 nm is used as the recording laser beam and the reproduction laser beam, and the wavelength of the other layers except the top layer of the plurality of layers is 500 nm. 19. The multilayer recording layer type optical recording medium according to claim 18, wherein the optical recording medium is initialized with the initialization laser beam having a wavelength of 100 nm or less.

20. The multilayer recording layer type optical recording medium according to any one of claims 17 to 19, wherein the recording layer is formed of a phase change material.