JP2002312980A - Optical recording medium, method of manufacturing the same, and target for sputtering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the difference in the recording power margin in an optical recording medium which uses the CAV method and to increase the total power margin. SOLUTION: A planar annular optical disk 1 has a first information signal layer 7 and a protective layer 8 protecting the first information signal layer 7 on one principal plane of a disk substrate 2 and is used to record and reproduce information signals by the CAV method. The first information signal layer 7 consists of a first dielectric layer 3, phase change recording layer 4, second dielectric layer 5 and first reflecting layer 6 which can reflect laser light L1 . In the optical disk 1, the first reflecting layer 6 is made of AlCu or AgPdCu and the add amount of Cu included in the Al alloy or the add amount of Pd and Cu included in the Ag alloy in the first reflecting layer 6 is monotonously increased from the inner circumference to the outer circumference of the first reflecting layer 6 along the radial direction of the optical disk 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, a method for manufacturing the same, and a sputtering target, and more particularly, to a constant rotational speed (CAV, Constant Angular).
It is suitable for application to an optical recording medium for recording / reproducing an information signal in Velocity.

[0002]

2. Description of the Related Art Conventionally, as a practical example of a rewritable optical disk using a phase change recording material, a so-called DVD-R
W (Digital Versatile Disc-ReWritable) is commercially available. This DVD-RW is obtained by laminating two phase-change type disk-shaped optical recording media (hereinafter, optical disks). The optical disc 101 before bonding is shown in FIG.
FIG.

As shown in FIG. 18, in an optical disk 101 before bonding, a first dielectric layer 103 made of a dielectric material and a crystal phase are formed on one main surface 102a of a disk substrate 102 made of a PC. A phase change recording layer 104 on which an information signal is recorded using a phase change with a crystalline phase, a second dielectric layer 105, and a reflection layer 106 for reflecting a laser beam
And the first dielectric layer 103 to the reflective layer 10
The protective layers 107 for protecting the six stacked films are sequentially provided.

[0004] As shown in FIG. 19A, two optical disks 101 configured as described above are prepared, and the protective layers 107 on one main surface 102a side are bonded to each other by the adhesive layer 1.
By pasting through the DVD, a DVD-RW having a double-sided recording configuration can be obtained. When only one surface is used as a recording surface, as shown in FIG. 19B, a dummy disk in which a reflective layer 109 and a protective layer 107 are sequentially laminated on one main surface 102a of a disk substrate 102 is illustrated. The optical disk shown in FIG.
By bonding the 7 side through an adhesive layer 108,
A single-sided recording DVD-RW can be obtained.

[0005] Laser light used for recording / reproducing on such a DVD-RW 101 is applied to the disk substrate 10.
It is configured to irradiate the phase change recording layer 104 from the second side. In this DVD-RW 101, the linear velocity is 3.49 m / s, and the recording bit length is 0.267.
μm / bit, track pitch (Tp) 0.74μ
m, the wavelength of the laser beam is about 650 μm, the data transfer rate is 11 Mbps, and the recording capacity is 4.7 GB. However, considering the recent applications such as computers, the data transfer rate has been further improved,
Recording / reproduction by CAV at this high transfer rate is desired.

In order to achieve a larger capacity and a higher transfer rate than the DVD-RW 101, there is a method of reducing the spot size (spot diameter) of the recording laser beam and improving the recording linear velocity. It is valid. Here, in order to reduce the spot size of the recording laser light, specifically, a method of shortening the wavelength of the laser light, a method of increasing the numerical aperture (NA) of the objective lens, and the like are mentioned. it can.

In particular, when the wavelength of the laser beam is shortened and the NA of the objective lens is increased, the spot size can be made smaller than when each of these methods is used alone. For example, as a light source, the wavelength λ is 40
If a so-called blue-violet laser near 0 nm is used and an objective lens with an NA of 0.85 is used, theoretically higher density recording is possible.

As described above, in order to increase the recording density,
It is essential to improve NA / λ. in this case,
In order to achieve a recording capacity of 8 GB, it is necessary that the NA is at least 0.70 or more and the wavelength λ of the laser beam is 0.68 μm (680 nm) or less.

[0009] Considering the compatibility from the currently used red laser to the blue laser expected to be widely used in the future, it is optimal to set the light transmission layer to 10 to 177 µm. That is, in general, there is a correlation between the disk skew margin Θ, the light source wavelength λ of the recording / reproducing optical pickup, the numerical aperture (NA), and the film thickness t of the light transmission protective layer of the disk. The relationship between these parameters and the disk skew margin Θ on the basis of a compact disk (CD) whose playability has been sufficiently demonstrated in practice is described in Japanese Patent Application Laid-Open No. 3-225.
No. 650 (Reference 1).

According to Document 1, -84.115 (λ / N
A ³ /t)≦Θ≦84.115 (λ / NA ³ / t). Here, considering a specific limit value of the skew margin 場合 when the disks are actually mass-produced, 0.
A value of 4 ° is reasonable. This is because, when considering mass production, if the size is smaller than this, the manufacturing yield decreases, and the cost increases. Even for existing optical recording media, the limit value of the disc skew margin Θ is C
D is 0.6 ° and DVD is 0.4 °.

Therefore, when Θ is set to 0.4 ° and how much the thickness of the light transmission protective layer should be set by shortening the wavelength of the laser and increasing the NA, the wavelength λ of the laser light is calculated.
Is λ = 0.65 μm (red laser), the NA is required to be 0.78 or more. In addition, when the wavelength of the laser light is shortened and a semiconductor laser having a wavelength λ of about 0.4 μm is used and NA is fixed at 0.78 or more, the thickness t of the light transmission protection layer of the disk is 177 μm. It needs to be smaller below. On the other hand, the lower limit of the thickness of the light transmitting protective layer is determined by the protection function of the light transmitting protective layer for protecting the optical recording layer. Further, in consideration of the reliability and the influence of the collision of the second lens group, the thickness of the light transmission protection layer is set to 1
0 μm or more is desirable.

Here, an optical recording medium (optical disk) as described above, in which the light transmission protection layer is thinned, will be described. FIG. 20 shows the optical disc 201.

As shown in FIG. 20, an optical disc 201 having a thin light transmission protection layer is provided on a support substrate 202 with a reflection layer 203, a first dielectric layer 204, a recording layer 205, and a second dielectric layer. An optical recording layer 207 composed of the layer 206 and a light transmission protection layer 209 are laminated on the optical recording layer 207 via an adhesive layer 208. Among these, the support substrate 202 requires a certain degree of rigidity when it is formed of a single plate. Therefore, the thickness of the support substrate 202 is about 0.6 mm.

Incidentally, the DVD-RW1 as described above
01 or an optical recording medium such as the optical disk 201,
Polycarbonate resin and polyolefin resin used as a support substrate have heat resistance during melt molding,
It has the advantages that it is easy to mold, has little deterioration, and has excellent mechanical properties. Therefore, it is a material useful as a support substrate for an optical recording medium.

In the case where two disks are bonded to each other, it is important that a light-transmitting protective layer is formed by bonding a recording thin film on a support substrate and then bonding the recording thin film. In an optical disk, the yield and the reliability of the optical recording medium are often influenced by such bonding.

[0016]

SUMMARY OF THE INVENTION The above DVD-
It is required that even large-capacity, high-transfer-rate optical disks, such as the RW 101 and the optical disk 201 having a thin light transmission protection layer, be recordable and / or reproducible by CAV.

However, in the above-described phase-change recording medium, a thermal recording method using a laser beam is employed. Therefore, a change in temperature characteristics of heating and cooling of the medium due to CAV greatly affects the recording characteristics. give. Specifically,
In an optical disk having a flat annular shape with an outer diameter of 120 mm, the linear velocity at the innermost circumference and the linear velocity at the outermost circumference in the recording area differ by about 2.5 times. That is, if the outer diameter is 1
For a 20 mm optical disk, the linear velocity at the outer periphery is
Compared to the linear velocity on the center hole side (inner circumference), about 2.
5 times larger. As described above, since the linear velocities of the inner and outer peripheral portions of the optical disc are largely different, when recording an information signal on the optical disc, the recording characteristics are guaranteed at all linear velocities. It was difficult to guarantee.

Therefore, an object of the present invention is to provide an optical recording medium configured to record / reproduce an information signal by rotating a disk substrate at a constant angular velocity (CAV) and irradiating a laser beam. An optical recording medium and a method of manufacturing the optical recording medium, in which a difference in power margin, in particular, a difference in recording power margin between an inner peripheral portion and an outer peripheral portion of the optical recording medium can be suppressed, and the power margin of the entire optical recording medium is increased. It is to provide a method.

Another object of the present invention is to provide an optical disk having a flat annular shape configured to record / reproduce information signals by rotating a disk substrate at a constant angular velocity (CAV) and irradiating a laser beam. It is used for a sputtering method performed when manufacturing an optical recording medium capable of suppressing a difference in recording power margin in a recording medium, in particular, a difference in recording power margin between an inner periphery and an outer periphery and increasing a power margin of an entire optical disc. An object of the present invention is to provide a sputtering target.

[0020]

Means for Solving the Problems The present inventor has conducted intensive studies in order to solve the above-mentioned problems of the prior art. The outline is described below.

That is, according to the findings of the present inventors, CA
In an optical disk employing the V system, the number of revolutions during recording / reproducing of an information signal is constant. Therefore, as described above, the linear velocity in the inner peripheral part and the linear velocity in the outer peripheral part are about 2.5 times. Also, the linear velocity at the outer peripheral part is about 2.5 times the linear velocity at the inner peripheral part. As a result, the irradiation range of the laser spot per unit time also differs by about 2.5 times.

Therefore, the present inventor has developed a temperature characteristic such as a temperature rise or a cooling due to a difference in linear velocity between an inner peripheral portion and an outer peripheral portion at the time of recording or reproduction in an optical disk employing the CAV method. Various investigations were repeated in order to suppress the difference. As a result, the inventors came to focus on the reflective layer that affects the temperature characteristics.

That is, the inventor of the present invention changes the thermal conductivity of the reflective layer so that the temperature rise and the cooling in the recording layer of the optical disk can be made substantially equal over the entire surface of the recording layer. I came to remember that I could control it. Specifically, the thermal conductivity of the reflective layer is set to a value corresponding to the difference in linear velocity, that is, the characteristics of temperature rise and cooling in the portion irradiated with the laser beam are almost equal over the entire surface of the recording layer. If the thermal conductivity of the reflective layer in the portion irradiated with the laser beam can be made to be a thermal conductivity suitable for thermal recording, it is possible to guarantee the recording characteristics over the entire recording area of the optical disc. .

The present inventor has found that the thermal conductivity for obtaining the same characteristics as those at the inner peripheral portion at the outer peripheral portion of a flat annular optical disk having a relatively high linear velocity is as follows.
Further experiments and investigations were repeated. As a result, A
It has been recalled that when using an l-alloy or an Ag alloy, heat should be more easily stored in the outer peripheral portion of the optical disk, that is, the thermal conductivity should be reduced.

That is, according to the knowledge of the present inventors, in an Al alloy or an Ag alloy used as a reflection layer, A
The thermal conductivity changes depending on the amount of an additive containing l or Ag as a main component and a small amount added to these metals. Examples of the change in the thermal conductivity are shown in Tables 1 and 2 below.

[0026]

[Table 1]

[0027]

[Table 2]

From the above Tables 1 and 2, the thermal conductivity of the reflective layer is changed in the radial direction by changing the amount of the additive added to the main component such as Al or Ag in the reflective layer of the optical disk. Preferably. further,
In the outer peripheral portion of the reflective layer, if the addition amount is increased from the inner peripheral portion of the reflective layer, heat is easily stored in the outer peripheral portion of the reflective layer, and the same temperature characteristics as in the inner peripheral portion can be obtained. it can.

The present inventor can improve the degree of freedom of design if the thermal conductivity of the reflective layer can be changed in accordance with the desired characteristics of various optical discs. It has been recalled that a more favorable thermal conductivity distribution can be obtained.

In order to change the thermal conductivity of the reflective layer of such an optical disk in the radial direction, the present inventors have repeatedly studied the formation of the reflective layer, and formed the reflective layer. In the sputtering method mainly used, it has been conceived that the addition amount of a material in the sputtering target is changed in the radial direction of the target similarly to the above-mentioned reflection layer. And
In the CAV type optical disk, it is preferable to increase the amount of the above-described additive in the outer peripheral portion of the target than in the inner peripheral portion.

The present invention has been devised based on the above study.

Therefore, in order to achieve the above object,
According to a first aspect of the present invention, there is provided a flat annular disk substrate having, on one principal surface thereof, a reflective layer configured to reflect a laser beam used for recording and / or reproducing information signals in a planar annular shape. At least a recording layer configured to record an information signal is provided, and the information signal can be recorded and / or reproduced by rotating the disk substrate at a substantially constant angular velocity and irradiating at least the recording layer with a laser beam. An optical recording medium configured so that the reflective layer is made of an aluminum alloy in which an additive is added to aluminum, and the additive amount of the additive contained in the aluminum alloy forming the reflective layer is smaller than that of the disk substrate. In the radial direction.

In the first invention, in order to easily control the thermal conductivity of the aluminum alloy and to secure sufficient corrosion resistance, the additive is typically copper, and the content of the additive is Is from 0.5% by weight to 1.5% by weight.

According to a second aspect of the present invention, a laser beam used for recording and / or reproducing an information signal can be reflected on one principal surface of a planar annular disk substrate in a planar annular shape. At least a reflective layer and a recording layer configured to record information signals are provided, and the disk substrate is rotated at a substantially constant angular velocity, and at least a recording layer is irradiated with laser light to record information signals. And / or an optical recording medium configured to be reproducible, wherein the reflective layer is made of a silver alloy obtained by adding an additive to silver, and the amount of the additive contained in the silver alloy constituting the reflective layer is reduced. , Which vary along the radial direction of the planar annular disk substrate.

In the second invention, in order to easily control the thermal conductivity of the silver alloy and to secure sufficient corrosion resistance, the additives are typically calcium (Ca) and magnesium (Mg). ), Palladium (P
d), at least one element selected from the group consisting of iron (Fe) and copper (Cu), and preferably contains an additive in order to ensure good signal characteristics and sufficient corrosion resistance. The percentage is between 0.5% and 3.3% by weight.

In the first and second aspects of the present invention, in the planar annular optical recording medium, the thermal conductivity of the inner peripheral portion is increased and the thermal conductivity of the outer peripheral portion is made lower than that of the inner peripheral portion. Therefore, the additive amount of the additive at the outer peripheral portion of the reflective layer is larger than the additive amount of the additive at the inner peripheral portion of the reflective layer. In order to ensure good signal characteristics when recording / reproducing an information signal at a constant angular velocity, the amount of the additive added to the reflective layer is preferably set along the radial direction of the disk substrate. Therefore, the thickness increases from the inner peripheral portion to the outer peripheral portion of the reflection layer.

In the first and second aspects of the present invention, in order to increase the capacity of the optical recording medium such as a conventional DVD-RW, a groove track having irregularities is typically formed on one main surface of a disk substrate. The track pitch of the groove track is 0.74 μm or less. Further, the track pitch of the groove track is determined by the spot diameter of the laser light to be irradiated, and preferably, the track pitch is 0.2
μm or more.

In the first and second inventions, in order to make the optical recording medium rewritable or recordable, the recording layer typically records an information signal by at least two reversible state changes. Preferably, the recording layer is made of a phase change material capable of recording an information signal by a phase change between a crystalline phase and an amorphous phase.

In the first and second inventions, 65
Recording of information signals using a laser beam of about 0 nm and / or
Or, in order to perform reproduction, specifically, a first dielectric layer, a first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer which are sequentially laminated on one main surface of a disk substrate. The first information signal layer is irradiated with laser light from the other main surface opposite to the one main surface of the disk substrate toward the first information signal layer. The signal can be recorded and / or reproduced. Also,
In order to protect the first information signal layer contributing to recording / reproduction of the information signal, typically, a protection layer is provided on the first information signal layer on one main surface of the disk substrate via an adhesive layer. Is provided. In addition, a two-sided recording type optical recording medium can be configured by using two optical recording media configured as described above and bonding the first protective layer side through an adhesive. It is. In addition, a single-sided recording type optical recording medium is formed by using an optical recording medium configured as described above and a dummy disk having no information signal layer for recording / reproducing and bonding them together. It is also possible.

In the first and second aspects of the present invention, recording / reproducing of information signals is performed using an optical pickup in which the wavelength of the laser beam is made shorter and the objective lens is made higher in numerical aperture (NA). Therefore, preferably, the optical recording medium according to the first and second inventions has a reflective layer, a third dielectric layer, a recording layer and a fourth layer on one main surface of a disk substrate.
A second information signal layer, which is formed by sequentially laminating the dielectric layers, is provided, and a laser beam is directed toward the second information signal layer from the side where the second information signal layer exists on the disk substrate. By irradiating, the information signal can be recorded and / or reproduced. In addition, the wavelength of the laser light is shortened, and the objective lens has a higher numerical aperture (NA).
In order to protect the second information signal layer from the optical head when recording / reproducing the information signal using the optical pickup formed on the second information signal layer on one main surface of the disk substrate, A light-transmitting protective layer capable of transmitting at least laser light is provided via the second adhesive layer.

According to a third aspect of the present invention, a laser beam used for recording and / or reproducing an information signal can be reflected on one principal surface of a planar annular disk substrate in a planar annular shape. In the method for manufacturing an optical recording medium provided with at least a reflective layer and a recording layer configured to record information signals, the reflective layer is made of an aluminum alloy in which an additive is added to aluminum, and the The reflective layer is formed so that the additive amount of the contained additive varies along the radial direction of the disk substrate.

In the third aspect of the present invention, typically, a sputtering target made of an aluminum alloy and having at least an additive amount in the inner peripheral portion and an additive amount in the outer peripheral portion different from each other is used. Form a reflective layer.

In the third aspect of the present invention, the additive is typically copper, and is formed so that the content of the additive is in the range of 0.5% by weight or more and 1.5% by weight or less. .

According to a fourth aspect of the present invention, a laser beam used for recording and / or reproducing an information signal can be reflected on one principal surface of a planar annular disk substrate in a planar annular shape. In the method for manufacturing an optical recording medium provided with at least a reflective layer and a recording layer configured to record an information signal, the reflective layer is made of a silver alloy in which an additive is added to silver, and the silver alloy contains The amount of additive contained is
The reflective layer is formed so as to change along the radial direction of the disk substrate.

In the fourth aspect of the invention, typically, a sputtering target made of a silver alloy and having at least an additive amount of an additive in the inner peripheral portion and an additive amount of the additive in the outer peripheral portion different from each other is used. Form a reflective layer. In the fourth aspect, typically, the additive is at least one element selected from the group consisting of calcium, magnesium, palladium, iron, and copper.

In the fourth invention, typically, the content of the additive in the reflection layer is formed so as to be 0.5% by weight or more and 3.3% by weight or less.

In the third and fourth aspects of the present invention, typically, the amount of the additive added to the reflective layer is changed along the radial direction of the disk substrate from the inner periphery of the reflective layer. It is formed so as to continuously increase monotonically toward the outer periphery.

In the third and fourth inventions, typically, a disk substrate and a sputtering target are opposed to each other, and a center axis of the disk substrate in a direction perpendicular to one main surface of the disk substrate; The reflective layer is formed by arranging the sputtering target in a direction perpendicular to the fixed surface of the sputtering target so that the center axis of the sputtering target coincides with the central axis of the sputtering target. Further, at least when the reflective layer is formed on one main surface of the disk substrate, the disk substrate is rotated in an in-plane direction around a central axis of the disk substrate. Preferably, one sputtering target and one disk substrate are opposed to each other, the disk substrate is rotated in the in-plane direction, and the material of the sputtering target is formed on the disk substrate. Forming a reflective layer.

In the third and fourth aspects of the present invention, typically, a sputtering target is used in which the amount of additive in the outer peripheral portion is larger than the amount of additive in the inner peripheral portion. The reflective layer is formed such that the amount of the additive added to the outer peripheral portion of the reflective layer is larger than the amount of the additive added to the inner peripheral portion of the reflective layer.

In the third and fourth inventions, typically, the additive amount of the additive in the inner peripheral portion and the additive amount in the outer peripheral portion are different from each other, and the inner peripheral portion and the outer peripheral portion are different from each other. For sputtering, the additive amount of the additive in the middle portion sandwiched between is different from any of the additive amount of the additive in the inner peripheral portion and the additive amount in the outer peripheral portion. A reflective layer is formed using a target.

In the third and fourth aspects of the present invention, typically, an uneven groove track is formed on one main surface of the disk substrate, and the track pitch of the groove track is 0.7.
4 μm or less. Further, the track pitch of the groove track is determined by the spot diameter of the laser beam to be irradiated and the like, and preferably, the track pitch is 0.2 μm or more.

In the third and fourth aspects of the invention, typically, the recording layer is made of a phase change material capable of recording an information signal by a phase change between a crystalline phase and an amorphous phase.

In the third and fourth inventions, the first dielectric layer, the recording layer, and the second
Forming a first information signal layer in which a dielectric layer and a reflective layer are sequentially laminated to irradiate a laser beam toward a recording layer from the other main surface of the disk substrate opposite to the one main surface. To form a recordable and / or reproducible information signal. Further, in the third and fourth inventions, preferably, a protective layer is formed on the first information signal layer on one main surface of the disk substrate via an adhesive layer.

In the third and fourth inventions, typically, a reflective layer, a third dielectric layer, a recording layer and a fourth dielectric layer are sequentially laminated on one main surface of a disk substrate. By forming the second information signal layer, the information signal can be recorded and / or reproduced by irradiating the disk substrate with laser light from the side where the second information signal layer is present toward the recording layer. Formed. In the third and fourth inventions, preferably, a light transmission protection that can transmit at least laser light via an adhesive layer is provided on the second information signal layer on one main surface of the disk substrate. A layer is provided.

According to a fifth aspect of the present invention, there is provided a sputtering target having a substantially columnar structure, a substantially principal surface having a substantially circular shape, and a principal surface capable of being sputtered. At least the amount of the additive added to the outer peripheral portion of the one main surface of the circular shape and the amount of the additive contained in the center portion of the one main surface of the circular shape. It is characterized in that it is configured so that the amount of addition of the substance is different.

In the fifth aspect of the present invention, when used for forming a reflective layer in an optical recording medium, typically, a material serving as a main component in a sputtering target is aluminum (Al), and an additive is added to aluminum. It consists of a contained aluminum alloy. Further, in addition to being used for the reflective layer of the optical recording medium, in order to ensure characteristics such as corrosion resistance and sufficient reflectivity in the reflective layer, the additive is preferably copper, and The rate is
Preferably, it is 0.5% by weight or more and 1.5% by weight or less.

In the fifth aspect of the present invention, a material that is a main component of the sputtering target is typically silver so that it can be used for forming a reflective layer of an optical recording medium. Is comprised of a silver alloy. Further, while being used in the reflective layer, in order to ensure characteristics such as corrosion resistance and sufficient reflectance in the reflective layer, the additive is preferably a group consisting of calcium, magnesium, palladium, iron and copper. It is composed of at least one element selected from the group consisting of at least one element, and the content of the additive is preferably 0.5% by weight or more and 3.3% by weight or less.

In the fifth aspect of the invention, typically, the additive amount at the outer peripheral portion of the circular sputtering surface is
It is configured to be larger than the additive amount of the additive in the inner peripheral portion of the circular sputtering surface.

In the fifth aspect of the invention, typically, the sputtering target comprises a first target having a disk shape and a second target having an annular shape. The first target portion is fitted into the opening of the second target portion while the central axis of the portion matches the central axis of the second target portion. Further, the amount of the additive added to the second target portion is configured to be larger than the amount of the additive added to the first target portion. In addition, in order to obtain a desired additive amount distribution in the additive, preferably, the second target portion includes a plurality of annular target portions having an annular shape, and the plurality of annular target portions include They are fitted to each other with their central axes aligned. In addition, in the film to be formed, a second target portion is typically formed in order to form a film so that the additive amount of the additive is sequentially increased from the inner peripheral side to the outer peripheral side. The amount of the additive added to one annular target portion of the plurality of annular target portions is equal to the amount of the additive added to the annular target portion on the inner peripheral side of the annular target portion. Be more than quantity.

In the fifth aspect of the invention, the sputtering target is typically formed on one main surface of a disk substrate of an optical recording medium capable of recording and / or reproducing information signals. In forming at least one layer of the laminated film and forming a planar annular reflective layer configured to be able to reflect laser light used at the time of recording and / or reproducing information signals on the optical recording medium. Used.

In the present invention, typically, a polycarbonate resin used as a material of the light transmission protective layer is:
It is produced by a phosgene method synthesized by reacting a dihydric phenol (for example, bisphenol A) with phosgene in the presence of an acid binder (for example, sodium hydroxide (NaOH) or the like). , Other than ordinary polycarbonate resins, a branched polycarbonate having a phenolic hydroxyl group as a branching agent, a long-chain alkyl polycarbonate resin such as a long-chain alkyl acid chloride or a long-chain alkyl ester-substituted phenol as a terminal terminator, and the above-mentioned branching agent And a terminal long-chain alkyl branched polycarbonate resin using both a terminal terminator and a mixture thereof. And
These polycarbonate resins are put into an extruder, melted by a heating device such as a heater, extruded into a sheet, and formed into a sheet by using a plurality of cooling rolls.

In the present invention, typically, the recording material constituting the whole or a part of the optical recording layer is made of a material which undergoes a reversible state change by irradiation with a laser beam. In particular, a phase change material that causes a reversible phase change (phase transition) between an amorphous state and a crystalline state is preferable, and any known material such as a chalcogen compound or a simple chalcogen can be used. Specifically, tellurium (T
e), selenium (Se), germanium antimony tellurium (Ge-Sb-Te), Ge-Te, Sb-Te,
Indium antimony tellurium (In-Sb-T
e), silver, indium, antimony, tellurium (Ag-I
n-Sb-Te), gold, indium, antimony, tellurium (Au-In-Sb-Te), germanium, antimony, tellurium, palladium (Ge-Sb-Te-P)
d), germanium, antimony, tellurium, selenium (G
e-Sb-Te-Se), indium antimony selenium (In-Sb-Se), bismuth tellurium (Bi-
Te), bismuth selenium (Bi-Se), Sb-S
e, Ge-Sb-Te-Bi, germanium-antimony tellurium-cobalt (Ge-Sb-Te-Co), or a system containing Ge-Sb-Te-Au, or nitrogen (N), oxygen And a system into which a gas additive such as (O) is introduced. Among them, particularly preferred are those containing Sb-Te as a main component, and those containing Sb-Te as a main component, such as Sb-Te.
It is preferable to use one to which an arbitrary element such as e, Pd, Ge, or In is added.

In the present invention, when a phase change recording layer is used as the recording layer, the phase change (phase transition) between the amorphous state and the crystalline state is reversibly performed by the intensity of the laser beam. Can be. Then, recording, reproduction, erasing, and the like are performed by utilizing an optical change such as reflectance due to the two state changes of the amorphous state and the crystalline state, or overwriting is directly performed without erasing (overwriting). And so on. Normally, after a recording layer is formed, the recording layer is crystallized once to perform initialization (format), and thereafter, recording / reproduction is performed.

The present invention relates to, for example, DVR (Digital Vid
eo Recording system) such as an optical disc having a thin light transmitting layer, and has an emission wavelength of 650 nm.
A so-called DVR-red configured to record and reproduce information signals using a semiconductor laser of about m, and a configuration configured to record and reproduce information signals by using a semiconductor laser with an emission wavelength of about 400 nm. So-called DV
It is possible to apply to an optical disc such as R-blue. This DVR is preferably configured so that an information signal can be recorded by using an objective lens whose NA is increased to 0.85 or more by combining two lenses in series. And has a storage capacity of about 22 GB. An optical disk to which the present invention is preferably applied, such as the DVR, is preferably housed in a cartridge, but the application of the present invention is not necessarily limited to the one housed in a cartridge.

According to the optical recording medium and the method for manufacturing the same according to the first to fourth aspects of the present invention, the amount of the additive contained in the aluminum alloy or the silver alloy in the reflective layer can be reduced. By changing the reflection layer along the radial direction of the disk substrate, the thermal conductivity of the reflective layer can be changed along the radial direction of the disk substrate.

According to the fifth aspect of the present invention, the sputtering target is formed by adding an additive to a material serving as a main component, and at least the outer periphery of one principal surface to be sputtered. The amount of the additive contained in the part and the amount of the additive contained in the inner peripheral part of the sputtering surface are different from each other, so that the amount of the additive contained in the film to be formed is included. The amount of the additive can be changed along the radial direction of the disk substrate. When the sputtering target is used for forming an optical recording medium, physical properties such as thermal conductivity of a film formed on one main surface of the disk substrate of the optical recording medium are measured along the radial direction of the disk substrate. Can be changed.

[0067]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding portions are denoted by the same reference numerals.

First, the optical recording medium according to the first embodiment of the present invention will be described. FIG. 1 shows an optical recording medium according to the first embodiment.

The optical recording medium according to the first embodiment is a phase-change disk-shaped optical recording medium shown in FIG.
(Optical disks). The optical disk 1 before bonding is formed on one main surface 2 of the disk substrate 2.
On a, a first information signal layer 7, which is formed by sequentially laminating a first dielectric layer 3, a phase change recording layer 4, a second dielectric layer 5, and a first reflective layer 6, is provided. The protection layer 8 is provided so as to cover the first information signal layer 7.

Then, provided on the disk substrate 2,
First dielectric layer 3, phase change recording layer 4, second dielectric layer 5
And the first information signal layer 7 composed of the first reflection layer 6 has a planar annular shape and an inner diameter of, for example, 50 mm.
(Radius r _S1 = 25 mm), and the outer diameter is, for example, 110 mm (radius r _S2 = 55 mm).

The disk substrate 2 is made of a plastic material such as a polycarbonate resin, a polyolefin resin or an acrylic resin, or glass. As a material of the disk substrate, a material that can transmit at least a laser beam used for recording / reproducing information signals is selected, and from the viewpoint of cost and the like, it is preferable to use a plastic material. The thickness of the disk substrate 2 is, for example, about 0.6 mm. Also, this disk substrate 2
An uneven groove track is formed on one main surface 2a, and a convex portion (land) and a concave portion (groove) are formed in a track shape. Here, the track pitch Tp of the concave and convex groove tracks of the disk substrate 2 is, for example, 0.74 μm. In such a groove track, a wavy wobble (not shown) for reading an address at the time of recording / reproducing information is formed. Here, the amplitude of this wobble is sufficient for a sufficient wobble signal (W
It is selected from the viewpoint of securing obble signal) and preventing deterioration of recording signal characteristics, and specifically, is selected from 8 to 36 nm.

Further, the material of the first dielectric layer 3 and the second dielectric layer 5 is a material having a low absorptivity to the recording / reproducing laser light, specifically, an extinction coefficient k. It is preferable to use a material of 0.3 or less, and taking into consideration the viewpoint of heat resistance, for example, ZnS—SiO ₂ (particularly, having a molar ratio of about 4: 1) can be mentioned. The first dielectric layer 3 and the second dielectric layer 5 may be made of different materials.

The film thickness of the first dielectric layer 3 is set from the viewpoint of reflectance and modulation.
Specifically, it is selected from 60 to 140 nm, and in the first embodiment, is selected, for example, to 80 nm. The thickness of the second dielectric layer 5 is set from the viewpoint of the heat sink effect of the phase-change recording layer 4 and the prevention of deterioration of asymmetry characteristics.
m is preferable, and in the first embodiment, for example, it is 24 nm.

The phase change recording layer 4 is made of, for example, SbTe.
Made of alloy. The composition of the SbTe alloy constituting the phase-change recording layer 4 is reduced in storage stability, signal characteristics,
In particular, it is set from the viewpoint of a decrease in jitter characteristics, crystallization of the phase change recording layer 4, a decrease in reproduction stability, or a decrease in signal characteristics in high and low linear velocity regions. Further, the thickness of the phase change recording layer 4 is set from the viewpoint of preventing the deterioration of the repetitive recording characteristics and the decrease of the modulation, and is specifically selected from 5 to 25 nm. In the first embodiment, For example, it is selected to be 14 nm.

The first reflection layer 6 is made of, for example, metal or metalloid. In consideration of the reflection function of the first reflection layer 6, the material of the first reflection layer 6 has a reflectivity with respect to the wavelength of the laser beam used for recording and reproduction, and has a thermal conductivity of, for example, 4.0 × 10 ^-2 to 4.
5 × 10 ² J / m · K · s (4.0 × 10 ^{−4 to} 4.5 J)
/ Cm · K · s), and is preferably composed of a metal element, a metalloid element, and a compound or mixture thereof having a value within the range. That is, as a material of the first reflection layer 6, specifically, aluminum (Al), silver (Ag),
Gold (Au), nickel (Ni), chromium (Cr), titanium (Ti), palladium (Pd), cobalt (Co),
A simple substance such as silicon (Si), tantalum (Ta), tungsten (W), molybdenum (Mo), and germanium (Ge), or an alloy mainly including these simple substances can be given. And considering the practicality,
Of these, Al-based, Ag-based, Au-based, Si-based or Ge-based alloy materials are preferable. Specifically, when an alloy is used as the material of the first reflection layer 6, for example, AlC
u, AlTi, AlCr, AlCo, AlMgSi, A
gPdCu, AgPdTi, AgCuTi, AgPdC
a, AgPdMg, AgPdFe, Ag or SiB is preferred. Further, the material of the first reflection layer 6 is set in consideration of optical characteristics and thermal characteristics. That is, in general, when the thickness of the first reflective layer 6 is set to a size (for example, 50 nm or more) at which laser light does not pass,
The reflectivity is increased and the heat dissipation is improved. In particular,
Al-based materials and Ag-based materials have a wavelength λ of 40, for example.
The reflectance is 80 with respect to irradiation of blue laser light of about 0 nm.
% Or more, and has a high reflectance even when the laser light has a short wavelength. Therefore, as the first reflective layer 6, an alloy mainly containing Al or an alloy mainly containing Ag is preferable. From the above, in the first embodiment, an AlCu alloy is used for the first reflection layer 6. In addition, the thickness of the first reflective layer 6 is such that the diffusion of heat generated in the phase change recording layer 4, that is, the thermal cooling property is sufficiently ensured, the jitter property is kept good, and the stress generated in the first reflective layer 6 Is set from the viewpoint of minimizing the influence on mechanical properties such as skew, and specifically, 50 to 2
00 nm, and in the first embodiment,
For example, 150 nm is selected.

Further, in the first embodiment, the composition of the first reflection layer 6 is changed along the radial direction of the disk substrate 2. That is, the first reflection layer 6
Is made of, for example, AlCu, and the center O of the disk substrate 2 is
When the composition at the inner periphery near the radius r _S1 = 25 mm from AlCu _α (% by weight) and the composition at the outer periphery near the radius r _S2 = 55 mm are AlCu _β (% by weight),
In the first embodiment, the configuration is such that α <β is satisfied. In the optical disk according to the first embodiment, it is preferable to satisfy 0.5 ≦ α in order to secure sufficient corrosion resistance, and to satisfy β ≦ in order to sufficiently increase the thermal conductivity. It is preferably 1.5. Preferably, in such an additive, the addition amount of Cu is preferably increased continuously in the radial direction from the radius r _S1 to the radius r _S2 on the disk substrate 2. The change in the composition of the material forming the first reflective layer 6 may be set to α ≧ β in accordance with desired characteristics in addition to the above.
Can be changed within the range from the inner peripheral portion to the outer peripheral portion of the first reflection layer 6 along the radial direction. The change in the composition of the first reflective layer 6 according to the first embodiment will be described later in detail.

As described above, the first dielectric layer 3, the phase-change recording layer 4, the second
The dielectric layer 5 and the first reflective layer 6 are sequentially laminated to form a first information signal layer 7 according to the first embodiment.

The protection layer 8 provided so as to cover the first information signal layer 7 is made of, for example, an ultraviolet curable resin. The thickness of the protective layer 8 is, for example, 15 μm.

Then, two optical disks 1 according to the first embodiment configured as described above are prepared, and the protective layers 8 on the one main surface 2a side are bonded together as shown in FIG. By laminating via the layer 9, a double-sided recording type optical disk 10 can be obtained.

Further, as shown in FIG.
A dummy disk 12 in which a reflective layer 11 and a protective layer 8 are sequentially laminated on one main surface 2a is produced, and the protective layer 8 between the dummy disk 12 and the optical disk 1 is bonded to each other via an adhesive layer 9. Thus, it is possible to obtain the single-sided recording type optical disc 13 in which the side on which the optical disc 1 exists is the recordable side.

In the optical disk 1 configured as described above, a laser beam emitted from a predetermined optical pickup is irradiated from the other main surface 2b side of the disk substrate 2 to record and / or reproduce information signals. Is performed.

Next, a method of manufacturing the optical disk 1 configured as described above will be described. That is, a sputtering method is generally used to form a thin film on the optical disc 1. When manufacturing this optical disc 1,
In the RF reactive sputtering method and the like, a long time is required for film formation, and thus a film formation method using a DC sputtering method is often used. In this sputtering method, a mask for fixing a substrate and a pallet are attached to the disk substrate 2, and then the disk substrate 2 is loaded into a vacuum chamber for film formation. Then, after sequentially forming a dielectric layer and a recording layer, the disk substrate is removed outside the vacuum chamber. Thereafter, in the same manner, a new substrate is attached and put into a vacuum chamber, and optical disks are sequentially manufactured.

Hereinafter, an outline of a specific configuration and operation of a DC sputtering apparatus used for a sputtering method in manufacturing the optical disk 1 will be described. FIG. 4 shows a stationary facing type DC sputtering apparatus according to the first embodiment. FIG. 5 shows a target, a disk substrate, and a target used in the DC sputtering apparatus.
The planar positional relationship is shown. The stationary facing sputtering apparatus is a single-wafer sputtering apparatus that forms a thin film on one disk substrate 2.

As shown in FIG. 4, in the sputtering apparatus according to the first embodiment, a vacuum chamber 21 serving as a film forming chamber, a vacuum control unit 22 for controlling a vacuum state in the vacuum chamber 21, DC high voltage power supply 2
3, a sputtering cathode unit 25 connected to the plasma discharge DC high-voltage power supply 23 through a power supply line 24, a pallet 26 opposed to the sputtering cathode unit 25 at a predetermined distance, and Ar
And a sputtering gas supply unit 27 for supplying a sputtering gas such as an inert gas or a reaction gas into the vacuum chamber 21.

In the sputtering cathode section 25, a target 28 made of a target material such as an AlCu alloy, an SbTe alloy, or ZnS—SiO ₂ functioning as a negative electrode, and a backing plate 29 configured to fix the target 28 The backing plate 29 includes a magnet system 30 provided on a surface of the backing plate 29 opposite to the surface to which the target 28 is fixed. In addition, a pair of electrodes is constituted by a pallet 26 functioning as a positive electrode and a target 28 functioning as a negative electrode. On the pallet 26, a disk substrate 2, which is a film-forming object, is attached to the sputtering cathode portion 25 by an inner peripheral mask 31 and an outer peripheral mask 32 with a disk base 33 interposed therebetween. In addition, the pallet 26 is rotated in the in-plane direction of the disk substrate 2 on the surface of the pallet 26 opposite to the surface on which the disk base 33 is mounted, whereby the disk substrate 2 is rotated.
A substrate rotation drive unit 34 for rotating the substrate is provided so as to be interlocked therewith.

In the sputtering apparatus 20 according to the first embodiment, the disk substrate 2 as a film-forming object having a flat annular shape as shown in FIG.
5C, the center O of the disk substrate 2 and the center O ′ of the target 28 in a planar positional relationship with the target 28 made of a film-forming material having a disc shape as shown in FIG. Are arranged so as to substantially coincide with each other. In addition, the disk substrate 2 is configured to be able to rotate around its center O by a substrate rotation drive unit 34 shown in FIG.

As described above, the sputtering apparatus used for manufacturing the optical disk in the first embodiment is configured.

When the DC sputtering apparatus shown in FIG. 4 is used, first, the inside of the vacuum chamber 21 is evacuated by the vacuum controller 22 until a predetermined vacuum state suitable for sputtering is reached.

Next, a sputtering gas such as Ar gas or N ₂ gas is introduced into the vacuum chamber 21 by the sputtering gas supply unit 27 until a predetermined pressure is reached. Thereafter, in this state, the DC high-voltage power supply 2 for plasma discharge is used.
3, a predetermined negative potential is applied to the target 28 by applying a predetermined negative potential to the backing plate 29. Thereby, the pallet 26 forming a pair of electrodes
An electric field is generated between the power supply and the backing plate 29 to generate glow discharge. By this glow discharge, the ionized Ar gas sputters the target 28. As a result, the target material is hit from the target 28 in a state of atoms or the like. The beaten target material is deposited on the surface of the disk substrate 2 attached to the pallet 26 arranged to face the target 28. By continuing this deposition for a predetermined time, a thin film made of a desired material is formed on the disk substrate 2.

In the manufacture of the optical disk according to the first embodiment, a predetermined film is sequentially formed on the disk substrate 2 by using a plurality of sputtering apparatuses configured as described above. Note that, in the following manufacturing process, the same reference numerals as in the DC sputtering apparatus described above are used for the reference numerals of the sputtering apparatus used for forming each layer.

In the manufacture of the optical disk according to the first embodiment, first, the disk substrate 2 such as a PC substrate is loaded into the vacuum chamber 21 in which the target 28 made of ZnS-SiO ₂ is installed, and the pallet 26 Fixed to. The target 28 used here is:
As shown in FIG. 6A, this is a target having a disk shape in which ZnS—SiO ₂ is almost uniformly molded. Next, the pressure in the vacuum chamber 21 is reduced to, for example, 1.0 × 10 ^−4.
Vacuum to about Pa. Thereafter, the vacuum chamber 21
Sputtering is performed while introducing an inert gas such as Ar gas into the
the formation of the nS-SiO _2. As a result, the first dielectric layer 3 made of ZnS—SiO ₂ is formed on the disk substrate 2. After that, the first chamber 28 in which the target 28 made of ZnS-SiO ₂ is
The disk substrate 2 on which the dielectric layer 3 is formed is carried out.

Next, the disk substrate 2 on which the first dielectric layer 3 is formed is carried into a vacuum chamber 21 in which a target 28 made of an SbTe alloy as a phase change recording material is installed, and is fixed on a pallet 26. I do. Note that the target 28 used here is a SbT
This is a disk-shaped target in which an e-alloy material is almost uniformly molded. Next, the pressure in the vacuum chamber 21 is evacuated to, for example, about 1.0 × 10 ⁻⁴ Pa. Then, while introducing an inert gas such as Ar gas into the vacuum chamber 21, Sb is deposited on the first dielectric layer 3.
Te is deposited. Thereby, S on the first dielectric layer 3
The phase change recording layer 4 made of the bTe alloy is formed. Thereafter, the disk substrate 2 formed up to the phase change recording layer 4 is carried out from the vacuum chamber 21 in which the SbTe alloy target is installed.

Next, the disk substrate 2 on which the first dielectric layer 3 and the phase change recording layer 4 are sequentially laminated is mounted on a ZnS-Si
It is carried into the vacuum chamber 21 in which the target 28 made of O ₂ is installed, and is fixed to the pallet 26. Note that the target 28 used here is a ZnS-
This is a disk-shaped target in which a SiO ₂ material is almost uniformly molded. Next, the pressure in the vacuum chamber 21 is evacuated to, for example, about 1.0 × 10 ⁻⁴ Pa. Thereafter, ZnS—SiO ₂ is formed on the phase change recording layer 4 by performing sputtering while introducing an inert gas such as Ar gas into the vacuum chamber 21. As a result, the ZnS-SiO
_{A second} dielectric layer 5 of 2 is formed. Thereafter, the disk substrate 2 formed up to the second dielectric layer 5 is carried out from the vacuum chamber 21 in which the target 28 made of ZnS-SiO ₂ is installed.

Next, the first dielectric layer 3, the phase change recording layer 4
And disk substrate 2 on which second dielectric layer 5 is formed
Is loaded into a vacuum chamber 21 in which a target 28 made of, for example, an AlCu alloy obtained by adding Cu to Al is fixed to a pallet 26. Next, an AlCu alloy is formed on the second dielectric layer 5 by a sputtering method using, for example, Ar gas as a sputtering gas. Thus, the first reflection layer 6 made of an AlCu alloy is formed on the second dielectric layer 5. Here, in forming the first reflection layer 6 according to the first embodiment, the disk substrate 2
The composition on the inner circumferential side near the radius r _S1 = 25 mm from the center O is AlCu _0.5, and the radius r _S2 = 55 m from the center O.
The composition on the outer periphery near m is AlCu _1.2 . Then, from the radius r _{S1 on the} disk substrate 2 to the radius r
_It is formed such that the addition amount of Cu continuously and monotonically increases in the radial direction toward _S2 .

Thereafter, the disk substrate 2 on which the first dielectric layer 3, the phase change recording layer 4, the second dielectric layer 5, and the first reflective layer 6 are sequentially stacked is carried out from the vacuum chamber 21.

Subsequently, a protective layer 8 made of, for example, an ultraviolet curable resin is formed on the entire surface of the disk substrate 2 using, for example, a spin coater so as to cover the first information signal layer 7.

Thus, the optical disc 1 shown in FIG. 1 is manufactured.

Thereafter, two optical disks 1 manufactured as described above are prepared, and the optical disks 1 are bonded via the adhesive layer 9 so that the protective layer 8 side faces inside. Thus, the double-sided recording type optical disc 10 shown in FIG. 2 is manufactured.

A dummy disk 12 is manufactured in a manufacturing process different from that of the optical disk 1 shown in FIG. 1, and the optical disk 1 and the dummy disk 12 are bonded together so that their protective layers 8 are on the inside. Lamination is performed via the layer 9. Thus, the single-sided recording type optical disc 13 shown in FIG. 3 is manufactured.

Next, the first and second examples based on the above-described first embodiment and a first comparative example for comparing the effects of the first embodiment will be described.

First Embodiment In the first embodiment, the first reflection layer 6 of the optical disc 1 is made of an AlCu alloy. Further, the optical disc 1 according to the first embodiment is
The composition of the AlCu alloy constituting the reflective layer 6 is such that the addition amount of Cu continuously increases in the radial direction from the radius r _S1 to the radius r _S2 . That is, the disk substrate 2
The composition of the first reflective layer 6 on the inner peripheral side in the vicinity of a radius r _S1 = 25 mm from the center O of, for example, Cu is set to 0.1 in Al.
AlCu _0.5 containing 5% by weight, while radius r _S2 =
The composition of the first reflective layer 6 on the outer peripheral side near 55 mm is, for example, AlC containing 1.2% by weight of Cu in Al.
u _1.2 . Further, the composition of the AlCu alloy of the first reflective layer 6, i.e., the Cu content is from the inner circumference side in the radial r _S1 toward the outer circumferential side in the radial r _S2, 1.2% to 0.5% by weight It is configured to change continuously up to. By changing the Cu concentration distribution of the AlCu alloy constituting the first reflective layer 6 along the radial direction of the disk substrate 2, the optical disk 1 has a heat dependent on the concentration of Cu as an additive. When the conductivity is higher than the first reflective layer 6
Are different on the inner peripheral side and the outer peripheral side.

In forming the first reflective layer 6 according to the first embodiment, the sputtering apparatus 20 shown in FIG. 4 is used and the target 28 shown in FIG. 6B is used. That is, the target 28 used to form the first reflective layer 6 according to the first embodiment has a composition corresponding to the inner peripheral side of the first reflective layer 6, that is, a disk-shaped target made of AlCu _0.5 . a low concentration target portion 28a, provided so as to surround the low concentration target portion 28a, composition corresponding to the outer peripheral side of the first reflective layer 6, i.e. annular consists AlCu _1.2 high density target portion 28b It is composed of

Here, the fitting portion 28 of the target 28
c will be described. FIG. 7 shows the target 28 of FIG. 6B.
7 shows an example of a cross section taken along line VII-VII of the fitting portion 28c of FIG.

That is, in the example shown in FIG. 7A, in the fitting portion 28c, both target portions can be fitted. That is, the low concentration target portion 28a
Is formed in a truncated cone shape, and the low-concentration target portion 28a can be fitted to the center of the high-concentration target portion 28b, and a truncated cone-shaped opening whose center coincides with the center of the high-concentration target portion 28b I do. Then, the target 28 in which the low-concentration target portion 28a is fitted into the opening of the high-concentration target portion 28b is, for example, indium (I
n) and a bonding agent 35 such as solder made of tin (Sn)
Are joined to the backing plate 29.
As described above, since the low concentration target portion 28a is formed in a truncated cone shape and the low concentration target portion 28a is fitted in the opening of the high concentration target portion 28b to form the target 28, the fitting portion 28c In this case, it is possible to prevent the sputtered particles from colliding with the bonding agent 35.

In the example shown in FIG. 7B, in the fitting portion 28c, the fitting portion 2 in one target portion is used.
8c is formed in a concave shape that is substantially semicircularly concave, and the fitting portion 28c in the other target portion is formed.
Are formed in a convex shape which is raised almost in a semicircular shape along the concave shape in one target portion. And
The concave shape and the convex shape are combined with each other, and the low concentration target portion 28a is fitted into the opening of the high concentration target portion 28b to form the target 28. Then, the target 28 is bonded to the backing plate 29 using a bonding agent 35 such as solder. By configuring the fitting portion 28c in this way, it is possible to prevent the sputtered particles from colliding with the bonding agent 35.

In the example shown in FIG. 7C, in the fitting portion 28c, the low-concentration target portion 28a has a plurality of cylindrical bodies (two cylindrical bodies in FIG. 7C) having different outer diameters. And a plurality of toroids having a high concentration target portion 28b having different inner diameters and having the same outer diameter (two annular bodies in FIG. 7C). Are stacked in the order of the inner diameter with their outer circumferences matched. That is, the high-concentration target portion 28b has a stepped opening into which the low-concentration target portion 28a can be fitted. Then, the target 2 in which the step-shaped low-density target portion 28a is fitted into the step-shaped opening of the high-density target portion 28b.
8 is bonded to the backing plate 29 using a bonding agent 35. By configuring the fitting portion 28c in this manner, it is possible to prevent the sputtered particles from colliding with the bonding agent 35 in the fitting portion 28c.

As described above, the low concentration target portion 28a
And the high-concentration target portion 28b, it is possible to prevent the sputter particles from colliding with the bonding agent 35 and sputtering the bonding agent 35 itself. Thereby, for example, undesired In or Pb
And the like can be prevented from being mixed into the first reflection layer 6.

Then, the target 2 having the above configuration
8 and the first reflective layer 6 of the disk substrate 2
Are formed to face each other with their central axes overlapping. FIG. 8 shows a positional relationship between the target 28 and the disk substrate 2 arranged facing each other along a plane perpendicular to the facing surface.

As shown in FIG. 8, in the first embodiment, a center hole 2c is formed as a disk substrate 2, and a first dielectric layer 3 and a phase change recording layer 4 are formed on one main surface thereof. And a disk substrate on which the second dielectric layer 5 is sequentially laminated, and a low concentration target portion 28a and a high concentration target portion 28b
A two-part target fitted in c (see FIG. 6B) is used. Here, the outer diameter φ of the disk substrate is, for example, φ = 120 mm (radius r _S = 60 mm). The radius of the low-concentration target portion 28a is selected to be about the middle portion along the radial direction in the recording area 36 of the optical disk 1 manufactured in the first embodiment, and specifically, r _T1 = 40 mm (diameter 80 mm ). The outer diameter Φ of the high-concentration target portion 28b having an annular shape on the outer peripheral side is selected to be equal to or larger than the outer diameter of the disk substrate 2, specifically, Φ = 200 mm (radius R _T = 100 mm). The inner diameter is selected so as to substantially match the diameter of the low concentration target portion 28a. In addition, target 2
The distance (inter-TS distance d _TS ) between the sputtering surface No. 8 and one main surface of the disk substrate 2 on which the laminated film is formed is 30 to 50 m.
m, specifically, for example, d _TS = 40 mm.

Then, the target 28 and the disk substrate 2 are arranged in the vacuum chamber 21 as described above, and the first example is formed on the disk substrate 2 by the sputtering method described in the first embodiment. Is formed, and thereafter, a predetermined process is sequentially performed as described in the first embodiment. Thus, the optical disc 1 according to the first embodiment is manufactured.

Second Embodiment In the second embodiment, as in the first embodiment, the first reflection layer 6 of the optical disc 1 is made of AlC.
AlCu made of a u-alloy and constituting the first reflective layer 6
The composition of the alloy is configured such that the addition amount of Cu continuously increases in the radial direction from the radius r _S1 to the radius r _S2 . Further, unlike the first embodiment, the composition of the inner peripheral portion of the first reflective layer 6 near the radius r _S1 = 25 mm from the center O of the disk substrate 2 is, for example, 0.5 wt% of Cu in Al AlC and was AlCu _0.5, while the first composition of the reflection layer 6 in the first outer peripheral portion of the reflection layer 6 in the vicinity of radius r _S2 = 55 mm, for example containing 1.5% by weight of Cu to Al
u _1.5, and further, the inner peripheral portion (r _S1 =
25 mm) and an outer peripheral portion (r _S2 = 55 mm),
That is, the first in the middle part of the radius r _S3 = about 40 mm
The composition of the reflective layer 6 is, for example, 1.0% by weight of Cu in Al.
AlCu _1.0 contained. Then, the first reflection layer 6
The composition of the AlCu alloy, i.e. the content of Cu is, toward the outer periphery of the radius r _S2 from the inner periphery of the radius r _S1 through the periphery in the radius r _S3, from 0.5 wt% 1.0 It is configured to increase monotonically continuously from 1.5% by weight to 1.5% by weight. Then, similarly to the optical disc 1 according to the first embodiment, by changing the Cu concentration distribution of the AlCu alloy constituting the first reflective layer 6 along the radial direction of the disc substrate 2, the optical disc 1 The thermal conductivity depending on the concentration of Cu as the additive is configured to be different between the inner peripheral side and the outer peripheral side of the first reflection layer 6.

Further, the first reflection according to the second embodiment is performed.
In the formation of the layer 6, the sputtering apparatus shown in FIG.
20 and the target 28 shown in FIG.
Used. That is, the first reflection according to the second embodiment.
The target 28 used in forming the layer 6 includes a first
The composition corresponding to the inner peripheral portion of the reflective layer 6, that is, AlCu
_0.5Disc-shaped low-concentration target portion 28d composed of
So as to surround the low concentration target portion 28d.
A composition corresponding to the middle portion of the first reflective layer 6,
That is, AlCu_1.0Annular medium concentration
Target portion 28e and the medium concentration target portion 28e.
The outer peripheral portion of the first reflective layer 6 is provided so as to surround the first reflective layer 6.
, That is, AlCu_1.5Composed of
And an annular high-concentration target portion 28f.
The fitting portion 28c is shown in FIG. 7 according to the first embodiment.
This is the same as in the fitting portion 28c.

The target 2 having the above configuration
8 and the first reflective layer 6 of the disk substrate 2
Are formed to face each other with their central axes overlapping. FIG. 9 shows a positional relationship between the target 28 and the disk substrate 2 which are arranged to face each other along a plane perpendicular to the facing surface.

As shown in FIG. 9, in the first embodiment, a center hole 2c is formed as a disk substrate 2, and a first dielectric layer 3 and a phase change recording layer 4 are formed on one main surface thereof. And a low density target portion 28d, a medium density target portion 28e, and a high density target portion 28b are fitted in the fitting portion 28c as the target 28 using a disk substrate on which the second dielectric layer 5 is sequentially laminated. The divided target (see FIG. 6C) is used. here,
The outer diameter φ of the disc substrate is, for example, φ = 120 mm (radius r _S = 60 mm). In addition, the low concentration target section 2
The radius r _T2 of 8d is selected to be approximately the radially divided portion of the recording area 36 of the optical disc 1 manufactured in the second embodiment, and specifically, r _T2 = 25 mm (outer diameter: 50 mm). Is chosen. Further, the outer peripheral radius r _T3 of the annular middle concentration target portion e in the middle of the three divisions is specifically r _T3 = 40 mm (outer diameter: 80 mm)
And the inner diameter is selected so as to substantially match the outer diameter of the low-concentration target portion 28d. The outer diameter Φ of the high-concentration target portion 28f having an annular shape on the outer peripheral side is specifically, for example, Φ = 200 m, as in the first embodiment.
m (radius R _T = 100 mm), and the inner diameter is selected so as to substantially match the outer diameter of the medium concentration target portion 28e. The distance between the sputtering surface of the target 28 and one principal surface of the disk substrate 2 on which the laminated film is formed (inter-TS distance d _TS ) is selected to be 30 to 50 mm, and specifically, for example, d _TS = 40 mm. To be elected.

Then, in the vacuum chamber 21 of the sputtering apparatus 20, the target 28 and the disk substrate 2 are arranged as described above, and the disk substrate 2 is placed on the disk substrate 2 by the sputtering method described in the first embodiment.
The first reflection layer 6 according to the second embodiment is formed, and thereafter, a predetermined process is sequentially performed as described in the first embodiment. Thus, the optical disc 1 according to the second embodiment is manufactured.

First Comparative Example In this first comparative example, the first embodiment is different from the first embodiment.
Similarly, the first reflection layer 6 of the optical disc 1 is made of AlC
u alloy. Also, unlike the first embodiment, a half
Diameter r_S1= Inner periphery of the first reflective layer 6 near 25 mm
From the radius r_S2= First reflective layer 6 near 55 mm
Up to the outer peripheral portion, the composition of the first reflective layer 6 is substantially the same.
Specifically, Al contains 1.0% by weight of Cu.
AlCu having_1.0And That is, the first reflection layer 6
Composition of AlCu alloy, ie Cu content
Is the radius r_S1Radius r from the inner circumference of_S3Half through the middle circumference
Diameter r _S2About 1.0% by weight toward the outer periphery of
It is configured to be constant. Thus, day
A first reflection layer 6 is formed along the radial direction of the disk substrate 2.
That the concentration distribution of Cu in the AlCu alloy is constant
Heat conduction in the first reflective layer 6 of the optical disc 1
The rate is designed to be almost constant over the entire surface.
You.

Further, in forming the first reflective layer 6 according to the first comparative example, a sputtering apparatus which is compatible with a large number of sheets and is used for manufacturing a conventional optical disk using two targets is used. That is, in this sputtering apparatus, the eight disk substrates 2 are fixed to the disk base 33 in the sputtering apparatus 20 shown in FIG.
The structure is such that two targets 28 are fixed to the portion. FIG. 10 shows the positional relationship between the disk substrate 2 and the target 28 in the sputtering apparatus thus configured, in a plane along these surfaces.

As shown in FIG. 10A, the eight disk substrates 2 are fixed such that the centers of the disk substrates 2 are located on the circumference.
Is configured to rotate in the direction of the arrow b around the center of the circle where the center of is located. That is, the disk substrate 2 is configured to revolve around the center of the circle. FIG.
As shown in FIG. 0B, two targets 28 are fixed side by side. Then, as shown in FIG. 10C, the eight disk substrates 2 are revolved and the sputtering of the target 28 is performed.

As the target, an undivided target similar to the target 28 shown in FIG. 6A is used. That is, the target 28 used when forming the first reflective layer 6 according to the first comparative example is made of Al
AlCu in which Cu as an additive is evenly distributed
Consists of _1.0 .

Then, in the vacuum chamber 21 of the sputtering apparatus 20, the target 28 and the disk substrate 2 are arranged as described above, and sputtering is performed while revolving the disk substrate 2, so that the disk substrate 2 The first reflection layer 6 according to the first comparative example is formed, and thereafter, a predetermined process is sequentially performed as described in the first embodiment. Thus, the optical disc 1 according to the first comparative example is manufactured. The rest of the configuration and the manufacture of the optical disc 1 according to the first comparative example are the same as those in the first embodiment, and a description thereof will not be repeated.

The present inventor has made the first
The jitter characteristics of each of the optical discs 1 according to the example, the second example, and the first comparative example were evaluated. That is, the optical disc 1 is moved at a linear velocity of 3.49 m at the innermost circumference (r _S1 = 25 mm) of the recording area.
/ S, and a constant angular velocity (CAV) such that the linear velocity at the outermost periphery (r _S2 = 55 mm) is 8.30 m / s.
Rotate with. At the same time, a laser beam L ₁ having a wavelength of about 650 nm is irradiated from the other main surface 2 b side of the disc substrate 2 toward the first information signal layer 7 through an objective lens having a numerical aperture NA of 0.65. Thereby, the optical disk 1
Record an information signal. In recording this information signal, the linear density is set to 0.267 μm per bit. Then, using the recording waveform of Pe / Pp = 0.45 in the recording waveform shown in FIG. 11 as the recording waveform,
The recording power Pp (mW) dependency of jitter was evaluated.
Here, the evaluation result of the jitter characteristic of the optical disk 1 according to the first embodiment is shown in FIG. 12, and the evaluation result of the jitter characteristic of the optical disk 1 according to the second embodiment is shown in FIG.
FIG. 14 shows an evaluation result of the jitter characteristic of the optical disc 1 according to the first comparative example. The recording power dependency of the jitter at the innermost circumference (radius r _S1 = 25 mm) of the recording area 36 of the optical disk 1 is indicated by a black circle (●), and the recording power of the jitter at the outermost circumference (radius r _S2 = 55 mm). Dependencies are indicated by open triangles (△).

From FIG. 12, FIG. 13 and FIG. 14, the recording power dependence of the jitter characteristic at the inner peripheral portion (radius r _S1 ) of the optical disk 1 is shown in the first embodiment, the second embodiment, and the first embodiment. In any of the optical discs 1 according to the comparative examples, the jitter decreases almost monotonically from about 12.5% to about 8% as the recording power is increased. That is, in the inner peripheral portion of the optical disc 1, the recording power dependence of the jitter has almost the same tendency, and it can be seen that there is almost no difference between them. That is, in the low linear velocity region, it can be seen that there is almost no difference between the first comparative example and the first and second examples.

On the other hand, the outer peripheral portion (radius r _S2 ) of the optical disk 1
The recording power dependence of jitter in
In the optical disc 1 according to the first comparative example shown in FIG.
The jitter value (14%) at p = 11 mW is minimized, and the jitter value sharply increases as the recording power is increased. When Pp = 15 mW, the jitter value exceeds 25%, and the jitter characteristic increases. Whereas the optical disc 1 according to the first embodiment shown in FIG. 12 and the optical disc 1 according to the second embodiment shown in FIG. 13 have a jitter value (1) at Pp = 11 mW.
(Approximately 2.5%), the jitter value gradually increases with increasing recording power, and Pp =
It can be seen that the jitter value is about 15% even at 15 mW. That is, it can be seen that the jitter characteristics of the optical disc 1 according to the first and second embodiments are greatly improved in the high linear velocity region in the outer peripheral portion.

According to the knowledge obtained as a result of the inventor's earnest study on the above evaluations, in the optical disc 1 according to the first comparative example, as the recording power was increased, the jitter characteristics deteriorated. This is because the thermal conductivity of the first reflective layer 6 at the outer peripheral portion during recording is equal to that at the inner peripheral portion, so that the cooling speed is higher at the outer peripheral portion, which is a high linear velocity region, than at the inner peripheral portion. This is because crystallization is not sufficiently performed and the film becomes amorphous. On the other hand, in the first and second examples based on the first embodiment of the present invention, even when the recording power is increased, the composition of the first In the inner peripheral portion of the first reflective layer 6, the additive amount (Cu) is reduced in order to increase the thermal conductivity in accordance with the characteristics of the optical disc 1 in particular. In the outer peripheral portion of the first reflection layer 6,
Since the amount of the additive is increased to reduce the thermal conductivity, the cooling rate at the time of recording in the outer peripheral portion is reduced,
This is because crystallization can be performed even at a high linear velocity.

As described above, according to the first embodiment, the first reflection layer 6 of the optical disc 1 is made of an AlCu alloy, and the composition of the AlCu alloy forming the first reflection layer 6 is To be different between the peripheral portion and the outer peripheral portion, specifically, the composition of the inner peripheral portion of the first reflective layer 6 is set to AlCu _0.5 and the composition of the outer peripheral portion is different from AlCu _1.2, and Since the composition of the inner peripheral portion of the first reflective layer 6 is AlCu _0.5 , the composition of the middle peripheral portion is AlCu _1.0, and the composition of the outer peripheral portion is AlCu _1.5 , the first reflection caused by these compositions is obtained. The thermal conductivity of the layer 6 can be changed along the radial direction of the optical disc 1. Therefore, in the optical disc 1, the crystallization and the amorphization of the phase change recording layer 4 in the low linear velocity region on the inner peripheral portion can be controlled well, and the optical disc 1 can be controlled.
The crystallization and amorphization of the phase change recording layer 4 in the high linear velocity region on the outer peripheral portion can be performed without deteriorating the recording characteristics. This suppresses a difference in the recording power margin over the entire surface of the optical disc 1, so that the overall power margin can be increased. Therefore, good recording / reproducing characteristics can be obtained in the optical disc 1 employing the CAV method.

Next, an optical recording medium according to a second embodiment of the present invention will be described. FIG. 15 shows an optical disk according to the second embodiment.

As shown in FIG. 15, in the phase-change type optical disk 40 according to the second embodiment, a second reflection layer 42 and a third dielectric layer 43 are formed on one main surface of a disk substrate 41. , A second information signal layer 46 configured by sequentially laminating a recording layer 44 and a fourth dielectric layer 45. Also, the second on the main surface of the disk substrate 41
A light transmission layer 49 in which an adhesive layer 47 and a light transmission protection layer 48 are sequentially laminated is provided on a main surface of the information signal layer 46 opposite to the side on which the disk substrate 41 is present. As described above, the second information signal layer 46 and the light transmitting layer 49 are sequentially provided on one main surface of the disk substrate 41, and the optical disk 40 according to the second embodiment is configured. In this optical disc 40, recording /
The laser light L ₁ for reproduction, the light transmission layer 49 is irradiated from the side provided with respect to the disk substrate 41. The optical disk 40 is an optical disk that employs a so-called land / groove recording method in which an information signal is recorded on both the unevenness formed on one main surface thereof.

The disk substrate 41 is made of a plastic material excellent in cost reduction, such as a polycarbonate resin, a polyolefin resin, and an acrylic resin.
When using polycarbonate (PC) among these materials, those having a thermal expansion coefficient of about 7.0 × 10 ⁻⁵ and a flexural modulus of about 2.4 × 10 ⁴ are used. When a low water-absorbing polyolefin resin such as a cycloolefin polymer (for example, ZEONEX (registered trademark)) is used, the coefficient of thermal expansion is about 6.0 × 10 ⁻⁵ ,
A material having a flexural modulus of about 2.3 × 10 ⁴ is used.
The optical disc 40 according to the second embodiment is configured to record / reproduce an information signal by irradiating the disc substrate 41 with laser light from the side where the thin light transmitting layer 49 is provided. Have been. Therefore, as the disk substrate 41, it is not necessary to consider whether the disk substrate 41 has transmissivity or not. For example, a substrate made of a metal such as Al can be used. The disk substrate 41 is manufactured by, for example, an injection molding method or an ultraviolet curing resin.
This is performed by the P method. In addition, the thickness of the disk substrate 41 is selected from 0.3 to 1.3 mm, and in the second embodiment, is selected to be, for example, 1.1 mm. this is,
If the thickness of the disk substrate is smaller than 0.3 mm, the strength of the optical disk 40 itself is reduced or the optical disk 40 is easily warped. On the other hand, when the thickness of the disk substrate 41 is 1.
If it is larger than 3 mm, the thickness of the optical disk 40 becomes larger than the thickness of the optical disk such as a CD or DVD (about 1.2 mm), and the CD or DVD and the optical disk according to the second embodiment are different from each other. This is because there is a possibility that the same disk tray cannot be shared when considering the commercialization of the drive devices corresponding to both.

The disk substrate 41 has a planar annular shape with a center hole (not shown) formed in the center. The inner diameter (diameter of the center hole) of the disk substrate 41 is, for example, 15 mm, and the outer diameter is, for example, 120 m.
m. In addition, on one main surface of the disk substrate 41 on which the second information signal layer 46 is formed, groove tracks (not shown) formed of lands and grooves are formed. The track pitch T in this uneven groove track
p is, for example, 0.3 μm. Further, the groove track may be formed in various shapes such as a spiral shape, a concentric shape, and a pit row. The optical disc 40 can be rotated to move the laser spot to an arbitrary position by the guide using the groove track.

The second reflective layer 42 is made of, for example, metal or
Made of semi-metal. Then, the antireflection in the second reflection layer 42
Considering the radiation function, the material of the second reflective layer 42
Is opposite to the wavelength of the laser beam used for recording and reproduction.
It has radioactivity and thermal conductivity of, for example, 4.0 × 10
^-2~ 4.5 × 10^TwoJ / m · K · s (4.0 × 10^-Four~
Metal element having a value within the range of 4.5 J / cm · K · s)
Elements, metalloid elements, and their compounds or mixtures
Preferably. That is, the second reflection layer 42
As the material, specifically, Al, Ag, Au, Ni,
Cr, Ti, Pd, Co, Si, Ta, W, Mo, Ge
Etc., or alloys containing these
Can be mentioned. And consider the practicality aspect
And Al-based, Ag-based, Au-based, and Si-based
Or a Ge-based material is preferable. Also, the second reflection layer 42
When an alloy is used as the material of
u, AlTi, AlCr, AlCo, AlMgSi, A
gPdCu, AgPdTi, AgCuTi, AgPdC
a, AgPdMg, AgPdFe, Ag or SiB
Which is preferred. Further, the material of the second reflection layer 42 is
It is set in consideration of chemical characteristics and thermal characteristics. That is,
In general, the thickness of the second reflective layer 42 _TwoBut
Set to a size that does not transmit (for example, 50 nm or more)
Then, the reflectance increases and the heat dissipation improves.
You. In particular, Al-based materials and Ag-based materials have a wavelength λ of 4
Reflection of blue laser light of about 00 nm
When the laser light has a short wavelength, such as when the rate becomes 80% or more,
Has a high reflectivity, so that the main component is Al.
An alloy or an alloy containing Ag as a main component is preferable. More than
Therefore, in the second embodiment, the second reflection
As the layer 42, for example, an Ag alloy is used. Also, the second
The thickness of the reflective layer 42 depends on the diffusion of heat generated in the recording
In other words, sufficient thermal cooling characteristics and good jitter characteristics
While maintaining, the stress generated in the second reflective layer 42
Minimize impact on mechanical properties such as skew
It is set from the point of view, specifically, 50 to 200 nm
In the second embodiment, for example, 12
0 nm is selected.

Further, in the second embodiment, the second embodiment
2 in the radial direction of the disk substrate 41
It is configured to vary along. That is, the second reflection
The layer 42 is made of, for example, an Ag alloy (AgM (M is at least 1
Elements)) and the center O of the disk substrate 41
Radius r from_S1= The composition at the inner periphery near 25 mm
AgM_γ(% By weight), radius r_S2= Outer circumference around 55mm
AgM _δ(% By weight)
In the second embodiment, the configuration is such that γ <δ is satisfied.
Has been established. Further, the optical disk according to the second embodiment is used.
In the disc, in order to ensure sufficient corrosion resistance,
0.5 ≦ γ is preferable, and the thermal conductivity is
In order to secure a sufficient value, it is preferable that δ ≦ 3.3.
Good. And, in such an additive M, preferably
Is the radius r of the disk substrate 41_S1Radius r_S2To
It is configured so that the addition amount increases monotonically in the radial direction
It is. Note that a set of materials forming the second reflective layer 42
In addition to the above, depending on the desired characteristics,
γ ≧ β may be satisfied, and the half of the disk substrate 41 may be set.
From the inner periphery to the outer periphery of the second reflection layer 42 along the radial direction.
It is possible to vary within a range. Ma
The composition of the second reflection layer 42 according to the second embodiment
The details of the change will be described later.

The third dielectric layer 43 and the fourth dielectric layer 45 are made of a material having a low absorption capacity for the recording / reproducing laser beam. It is preferable to use a material having a value of 0.3 or less. In the second embodiment, as the third dielectric layer 43 and the fourth dielectric layer 45, for example, ZnS—SiO ₂ (particularly, the molar ratio is about 4: 1) is used. The thickness of the third dielectric layer 43 is, for example, 14 nm, and the thickness of the fourth dielectric layer 45 is, for example, 140 nm.

The recording layer 44 is provided on the optical disc 40.
Since a phase-change type optical disk is adopted as the optical disk, the optical disk is made of a phase-change recording material. In the second embodiment,
For example, it is made of an SbTe-based material, specifically, SbTe.
The thickness of the recording layer 44 is, for example, 12 nm.

The adhesive layer 47 provided on the second information signal layer 46 is made of, for example, a pressure-sensitive adhesive or an ultraviolet curable resin. In order to prevent the second information signal layer 46 from changing with time, the outer peripheral end of the adhesive layer 47 in the radial direction is preferably 0.5 mm or more from the outer peripheral end of the second information signal layer 46 in the radial direction. It is provided so as to be on the outer peripheral side.

Further, the adhesive layer 4 is formed on the second information signal layer 46.
The light transmission protection layer 48 formed through the layer 7 is preferably made of a material having a low absorptivity to laser light used for recording / reproduction, and a material having a laser light transmittance of 90% or more. It is more desirable to configure. Specifically, the light transmission protection layer 48 is made of a planar annular sheet-like base made of, for example, a polycarbonate resin material or a polyolefin resin. Specifically, when polycarbonate (PC) is used, the thermal expansion coefficient is 7.0 × 10 ^−5.
When a polyolefin resin (for example, ZEONEX (registered trademark)) is used, the thermal expansion coefficient is about 6.0 × 10 ⁻⁵ and the flexural modulus is about 2.4 × 10 ^4. Is about 2.3 × 10 ⁴ . The thickness of the light transmission protection layer 48 is 3 to 177.
In the second embodiment, the thickness is selected so that the total thickness with the adhesive layer 47 becomes, for example, 100 μm. The light transmission protection layer 48 according to the second embodiment is formed by charging a polycarbonate resin into an extruder and heating the polycarbonate resin with a heater (not shown).
Is formed at a temperature of 250 to 300 ° C. using a plurality of cooling rolls, formed into a sheet shape using a plurality of cooling rolls, and cut into a shape conforming to the disk substrate 41.

Further, as a method for producing the optical disk 40 configured as described above, the following two methods can be roughly divided.

The first method is a method in which a multilayer film is laminated on a support substrate in which a guide groove is formed, and finally, a smooth light transmitting protective layer is formed. As a method of forming the light transmission protection layer,
For example, a method of laminating an optically sufficiently smooth light-transmitting sheet (film) made of a polycarbonate resin or a polyolefin resin having a thickness of 100 μm or less by using an ultraviolet-curable resin as an adhesive, or by applying an adhesive. A method of laminating via a pressure-sensitive adhesive having a function can be used.

The second method is a method of laminating a multilayer film on the light transmitting protective layer in which the guide groove is formed, and finally forming a smooth disk substrate 41. In addition, thickness 100μ
As a method of forming the groove tracks of the unevenness on the light transmitting protective layer of m or less, an injection molding method, a 2P method, a method of transferring the unevenness by pressing and pressing, or the like can be used.

Of the two methods described above, the step of forming irregularities on the light transmitting protective layer or the step of forming a multilayer film is not always easy. Therefore, the first method is used in consideration of mass productivity. It is desirable. Hereinafter, a method of manufacturing the optical disc 40 by the first method of the above two methods will be described. In the sputtering apparatus used for manufacturing the optical disk 40 according to the second embodiment, a stationary facing sputtering apparatus of a sheet type capable of rotating on the same substrate as in the first embodiment is used, and a description thereof will be omitted. . In addition, the sputtering target has the same structure as the target 28 shown in FIG. 6 and uses a target made of a different material, and a detailed description thereof will be omitted.

In the method of manufacturing an optical disk according to the second embodiment, first, a disk substrate 2 such as a PC substrate is placed on a target 28 made of an Ag alloy in which an additive (M) is added to Ag. It is carried into the installed vacuum chamber 21 and fixed to the pallet 26. In addition,
As shown in FIG. 6B, the target 28 used here has a low concentration target portion 28a and a high concentration target portion 2.
8b is a disk-shaped target 28 divided into two. Next, an Ag alloy is formed on one main surface of the disk substrate 41 by a sputtering method using, for example, Ar gas as a sputtering gas. Thereby, the disk substrate 41
A second reflective layer 42 made of an Ag alloy is formed on one main surface of the second reflective layer 42. Here, in the formation of the second reflective layer 42 according to the second embodiment, the composition AgM in the inner peripheral portion near the radius r _S1 = 25 mm from the center O of the disk substrate 41 is used.
and _gamma, in the composition Alm _[delta] at the outer peripheral portion in the vicinity of radius r _S2 = 55 mm from the center O, as a gamma <[delta],
The M is formed such that the addition amount of M continuously increases monotonously in the radial direction from the radius r _S1 to the radius r _S2 on the disk substrate 41.

Next, the disk substrate 41 on which the second reflection layer 42 is formed is carried into the vacuum chamber 21 in which the target 28 made of, for example, ZnS-SiO ₂ is installed.
It is fixed to the pallet 26. Note that the target 28 used here is ZnS—SiO ₂ , as shown in FIG. 6A.
Is a substantially disk-shaped target molded almost uniformly. Next, the pressure in the vacuum chamber 21 is evacuated to, for example, about 1.0 × 10 ⁻⁴ Pa. afterwards,
By performing sputtering while introducing an inert gas such as Ar gas into the vacuum chamber 21, the second
Depositing a ZnS-SiO ₂ on the reflective layer 42 of. Thus, a third dielectric layer 43 made of ZnS—SiO ₂ is formed on the second reflective layer 42. Then, this Zn
The disk substrate 41 on which the third dielectric layer 43 is formed is carried out from the vacuum chamber 21 in which the target 28 made of S-SiO ₂ is installed.

Next, the disk substrate 41 on which the second reflective layer 42 and the third dielectric layer 43 are formed is placed in the vacuum chamber 21 in which the target 28 made of an SbTe alloy as a phase change recording material is installed. It is carried in and fixed to the pallet 26. The target 28 used here is:
As shown in FIG. 6A, a target 28 having a disc shape and formed of a substantially uniform SbTe alloy material. Next, the pressure in the vacuum chamber 21 is set to, for example, 1.0 ×
Evacuate to about 10 ^-4 Pa. Thereafter, SbTe is formed on the third dielectric layer 43 while introducing an inert gas such as Ar gas into the vacuum chamber 21. Thus, the recording layer 44 made of the SbTe alloy is formed on the third dielectric layer 43. Thereafter, the disk substrate 41 formed up to the recording layer 44 is carried out from the vacuum chamber 21 in which the SbTe alloy target is installed.

Next, the disk substrate 4 on which the second reflection layer 42, the third dielectric layer 43, and the recording layer 44 are sequentially laminated.
1 is carried into a vacuum chamber 21 in which a target 28 made of ZnS-SiO ₂ is installed, and is fixed to a pallet 26. The target 28 used here is a disk-shaped target in which ZnS—SiO ₂ is almost uniformly molded as shown in FIG. 6A. Next, the pressure in the vacuum chamber 21 is reduced to, for example, 1.0 × 10 ^−4.
Vacuum to about Pa. Thereafter, the vacuum chamber 21
The sputtering is performed while introducing an inert gas such as Ar gas into the
S-SiO ₂ is formed. As a result, a fourth dielectric layer 45 made of ZnS—SiO ₂ is formed on the recording layer 44. Then, the second chamber is placed on one main surface from the vacuum chamber 21.
The disc substrate 41 on which the second information signal layer 46 including the reflective layer 42, the third dielectric layer 43, the recording layer 44, and the second dielectric layer 45 is formed is carried out.

Thereafter, the light transmitting protection layer 48 made of a flat annular light transmitting sheet is formed by using a predetermined bonding apparatus which prevents the blocking phenomenon and the mixing of air bubbles.
A sheet having an adhesive layer 47 made of a pressure-sensitive adhesive (PSA) adhered to one surface of the disc substrate 41 on one main surface of the disc substrate 41 on which the second information signal layer 46 is formed, on the surface of the adhesive layer 47. Match. Thereby, the second of the disk substrate 41
A light transmitting layer 49 is formed so as to cover the information signal layer 46 of FIG.

As described above, the optical disk 40 shown in FIG.
Is manufactured.

After that, if necessary, two optical disks 40 manufactured as described above are prepared, and the disk substrate 41 side is placed inside, and the optical disks 40 are bonded using a predetermined adhesive. Then, a double-sided recording type optical disk is manufactured.

Next, a third example based on the above-described second embodiment and a second comparative example for comparing the effects of the second embodiment will be described.

Third Embodiment In the third embodiment, the optical disc 40
The second reflection layer 42 is made of AgPdCu. Sand
That is, PdCu is used as M in AgM. Ma
Further, the optical disc 40 according to the first embodiment is
The composition of the AgPdCu alloy constituting the second reflective layer 42 is
Radius r_S1Radius r_S2In the radial direction toward, Pd and
The addition amount of Cu is configured to increase continuously and monotonously.
That is, the radius r from the center O of the disk substrate 41_S1=
Composition of the second reflective layer 42 in the inner peripheral portion near 25 mm
For example, containing 0.6% by weight of Pd in Ag
Containing 0.8% by weight of Cu_0.6Cu_0.8When
And, on the other hand, the radius r_S2= 55th in the outer periphery near 55 mm
2, the composition of the reflection layer 42 is, for example,
A containing 1.2% by weight of Cu and 1.2% by weight of Cu
gPd_1.0Cu_1.2And Also, the second reflective layer 42
AgPdCu alloy composition, ie, radius r _S1Within
Radius r from the circumference_S2PdCu content toward the outer periphery
Continuously increases monotonically from 1.4% to 2.2% by weight
And the Pd content is from 0.6% by weight to 1.0% by weight.
Continuously monotonically increasing, Cu content from 0.8% by weight
Constructed to increase monotonically continuously to 1.2% by weight
ing. Then, along the radial direction of the disk substrate 2,
Pd in AgPdCu alloy constituting the second reflection layer 42
By changing the Cu concentration distribution, the optical disk 4
0, depends on the concentration of PdCu as additive
The thermal conductivity differs between the inner peripheral side and the outer peripheral side of the second reflection layer 42.
It is configured to be.

In forming the second reflective layer 42 according to the third embodiment, the sputtering apparatus 20 shown in FIG. 4 is used and the target 28 shown in FIG. 6B is used.
Is used. That is, the target 28 used in forming the second reflective layer 42 according to the third embodiment has a composition corresponding to the inner peripheral side of the second reflective layer 42, that is, Ag.
A disk-shaped low-concentration target portion 28a composed of Pd _0.6 Cu _0.8 and a composition corresponding to the outer peripheral portion of the second reflection layer 42, which are provided so as to surround the low-concentration target portion 28a, ie, AlPd _0.8 And an annular high-concentration target portion 28b made of Cu _1.2 .

Then, the target 2 having the above configuration
The sputter surface 8 and the one main surface of the disk substrate 41 on which the second reflective layer 42 is formed face each other with their central axes overlapping. The positional relationship between the target 28 and the disk substrate 41 arranged opposite to each other is the same as that shown in FIG.

Then, similarly to the first embodiment, the target 28 and the disk substrate 41 are arranged in the vacuum chamber 21 in the same manner as shown in FIG. The second embodiment according to the third embodiment
Is formed, and thereafter, a predetermined process is sequentially performed as described in the second embodiment. Thus, the optical disc 40 according to the third embodiment is manufactured.

Second Comparative Example In this second comparative example, the second reflection layer 42 of the optical disc 40 is
It is composed of a gPdCu alloy. Further, different from the third embodiment, the second reflection layer 42 having a radius of about r _S2 = 55 mm extends from the inner peripheral portion of the second reflection layer 42 having a radius of about r _S1 = 25 mm.
Up to the outer peripheral portion, the composition of the second reflective layer 42 is substantially the same, and specifically, 0.8 wt% of Pd is added to Ag.
AgP containing 1.0% by weight of Cu
d _0.8 Cu _1.0 . That is, the A of the second reflection layer 42
gPdCu alloy composition, that is, the content of PdCu,
From the inner periphery of the radius r _S1 toward the outer circumferential portion of the radius r _S2, it is configured to be constant at the order of 1.8 wt%.
Thus, along the radial direction of the disk substrate 41, the Pd in the AgPdCu alloy forming the second reflective layer 42
By keeping the concentration distribution of Cu and Cu constant, the thermal conductivity of the second reflective layer 42 of the optical disc 40 is configured to be substantially constant over the entire surface. In addition,
In forming the second reflective layer 42 according to the second comparative example, an apparatus similar to the sputtering apparatus 20 shown in FIG. 4 is used.

The inventor of the present invention has made the third
In each of the optical discs 40 according to the example of the present invention and the second comparative example, the jitter characteristics were evaluated, especially for the outer peripheral portion. That is, the linear velocity of the optical disc 40 at the outer peripheral portion (r _S2 = 55 mm) is 5.7 m / s.
It is rotated at a constant angular velocity (CAV) such that At the same time, the laser beam L ₂ having a wavelength of about 405 nm is directed toward the second information signal layer 46 from the side of the disk substrate 41 where the light transmitting layer 49 is provided, through an objective lens having a numerical aperture NA of 0.85. Irradiate. Thereby, the optical disk 4
An information signal is recorded at 0. In recording this information signal, the linear density is set to 0.13 μm (0.
13 μm / bit). FIG. 16 shows the result of evaluating the dependency of jitter on the recording power Pp (mW) using the recording waveform of Pe / Pp = 0.45 in the recording waveform shown in FIG. The recording power dependency of the jitter in the optical disc according to the third embodiment is indicated by a black circle (•), and the recording power dependency of the jitter in the second comparative example is indicated by a white triangle (△).

As shown in FIG. 16, the recording power dependence of the jitter at the outer peripheral portion (radius r _S2 ) of the optical disk 40 is higher than that of the optical disk 40 according to the second comparative example.
= 3.8 mW, the jitter value (8.7%) is minimized, and the jitter value sharply increases as the recording power is increased. When Pp = 5 mW, the jitter value exceeds 11%. On the other hand, in the optical disk 40 according to the third embodiment, when Pp = 3 mW or more, the jitter value increases only moderately with increasing recording power. .
That is, in the high linear velocity region at the outer peripheral portion, the third
It can be seen that the jitter characteristic of the optical disc 40 according to the example is greatly improved as compared with the conventional second comparative example. That is, the wavelength of the laser beam used for recording / reproduction is shortened, and the optical disk 40 according to the second embodiment corresponding to the increase in NA has the same effect as the optical disk 1 according to the first embodiment. It can be seen that can be obtained.

As described above, according to the second embodiment, the second reflective layer 42 of the optical disk 40 is made of an Ag alloy, and the composition of the Ag alloy forming the second reflective layer 42 is As different between the peripheral part and the outer peripheral part, specifically,
The composition of the inner peripheral portion of the second reflection layer 42 is AgPd _0.6 C
u _0.8 and the composition of the outer peripheral part are different from those of AgPd _1.0 Cu _1.2 ,
Can be changed along the radial direction of the optical disc 40. Therefore, in the optical disc 40, crystallization and amorphization of the recording layer 44 in the low linear velocity region on the inner peripheral portion can be controlled well, and recording in the high linear velocity region on the outer peripheral portion of the optical disc 40 can be performed. The crystallization and amorphization of the layer 44 can be performed without deteriorating the recording characteristics. Thus, a difference in recording power margin due to a difference in linear velocity can be suppressed over the entire surface of the optical disc 40, and a total power margin can be increased. Therefore, good recording / reproducing characteristics can be obtained in the optical disc 40 employing the CAV method.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical concept of the present invention are possible.

For example, in the above embodiment,
The method of forming each film and the material of the disk substrate and the protective layer are merely examples, and a different film forming method may be used as necessary. May be.

For example, as the first information signal layer 7 in the first embodiment or the second information signal layer 46 in the second embodiment, as shown in FIG. The third reflecting layer 51, which is configured to change along the radial direction, the fifth dielectric layer 52 made of a dielectric, the first recording layer 53, the second recording layer 54, and the third made of the dielectric It is also possible to form a structure in which the six dielectric layers 55 are sequentially stacked or in a reverse order. Here, the first recording layer 53 and the second recording layer 54 are selected so as to differ from one another in material, composition, or complex refractive index. The recording layer may be composed of three or more layers, each of which has a different material, composition, or complex refractive index.

In the first and second embodiments, for example, ZnS-Si is used as the material of the dielectric layer.
Although O ₂ was used, any material can be used as long as the extinction coefficient k is 0.3 or less. Specifically, as the material of the dielectric layer, Al, Si, Ta, T
i, Zr, Nb, Mg, B, Zn, Pb, Ca, La,
Materials consisting of nitrides, oxides, carbides, fluorides, sulfides, oxynitrides, oxycarbides, or oxycarbides of metals such as Ge and metals and metalloids, and materials containing these as main components It can be used. More specifically, as a material of the first dielectric layer 3 and the second dielectric layer 5, AlN _x (0.5 ≦ x ≦ 1, especially Al
N)), Al ₂ O _3-x (0 ≦ x ≦ 1, (in particular, Al
₂ O ₃ )), Si ₃ N _4-x (0 ≦ x ≦ 1, especially (Si
₃ N ₄ )), SiO _x (1 ≦ x ≦ 2, (especially SiO ₂ , S
iO), MgO, Y ₂ O ₃ , MgAl ₂ O ₄ , TiO _x (1
≦ x ≦ 2 (particularly TiO ₂ ), BaTiO ₃ , SrT
iO ₃ , Ta ₂ O _5-x (0 ≦ x ≦ 1, (in particular, Ta
₂ O ₅ )), GeO _x (1 ≦ x ≦ 2), SiC, ZnS,
PbS, Ge-N, Ge-NO, Si-NO, Ca
It is also possible to use F ₂ , LaF, MgF ₂ , NaF, TiF _4, etc. Further, a material containing these materials as a main component or a mixture of these materials, for example, AlN—Si
O ₂ can also be used.

For example, in the above-described second embodiment, the disk substrate 41 is manufactured by an injection molding method or a photopolymer method. 1.1m thick
Any method can be used as long as it can obtain a disk shape having a diameter of 120 mm and an optically sufficient surface smoothness of the substrate surface.

In the above embodiment, the recording layer is made of a SbTe-based phase change material. However, the recording layer is not limited to a material other than the phase change material. Terbium iron (TbFe), TbFeCo, GdFe, GdF
An eCo-based magneto-optical recording material can also be used.
Also, the present invention relates to an aluminum (Al) alloy or a silver (A
g) It is also possible to apply to a read-only (ROM) disk using an alloy as a reflective layer.

In the first embodiment described above,
Although the low concentration target portion 28a and the high concentration target portion 28b of the target 28 are fitted to each other,
The target 28 is placed on one principal surface of a circular columnar structure,
It is also possible to use a target whose additive concentration changes continuously in the radial direction.

Further, in the first example according to the first embodiment described above, the AlCu
The composition of the alloy was AlCu _0.5 on the inner circumference and AlC on the outer circumference.
u _1.2, and the addition amount of Cu is continuously increased from the inner periphery toward the outer periphery. In the second embodiment, the composition of the AlCu alloy forming the second reflective layer 42 is changed to the inner periphery. Is AlCu _0.5 , the middle part is AlCu _1.0 , and the outer part is Al
As Cu _1.5 , the added amount of Cu is continuously increased from the inner peripheral portion toward the outer peripheral portion. However, in the added amount (additive concentration) and the added amount distribution (additive concentration distribution), It is not necessarily limited to the above-described values and distributions, and other addition amounts and addition amount distributions are also possible.

[0164]

As described above, according to the first to fourth aspects of the present invention, the reflection layer contained in the aluminum alloy or the silver alloy in the reflection layer constituting the laminated film portion of the optical recording medium. By changing the amount of the additive in the radial direction of the disk substrate, the thermal conductivity of the reflective layer can be changed in the radial direction of the disk substrate. Therefore, by rotating the disk substrate at a constant angular velocity and irradiating the laser beam,
CAV configured to record / reproduce information signals
In the optical recording medium employing the method, the difference in the recording power margin, in particular, the difference in the recording power margin between the inner peripheral portion and the outer peripheral portion of the optical recording medium can be suppressed, and the overall Power margin can be increased.

According to the fifth aspect of the present invention, the material is made of a material obtained by adding an additive to a material serving as a main component, and is added at least to the outer peripheral portion of one circular main surface. Since the additive amount of the additive is different from the additive amount of the additive contained in the central portion of the one main surface of the circular shape, the composition material of the film formed on the disk substrate is reduced. Since the additive amount of the contained additive can be changed along the radial direction of the disk substrate,
Physical characteristics such as thermal conductivity of the film to be formed can be changed along the radial direction of the disk substrate. Therefore, when the reflective layer of the optical recording medium is formed using this target, the difference in the recording power margin in the optical recording medium, particularly, the difference in the recording power margin between the inner circumference and the outer circumference is suppressed, and the power margin of the entire medium is reduced. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical disc before bonding according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a double-sided recording type optical disc after two optical discs shown in FIG. 1 are bonded together.

FIG. 3 is a cross-sectional view showing the single-sided recording type optical disc after bonding the optical disc shown in FIG. 1 and a dummy disc.

FIG. 4 is a schematic diagram showing a DC sputtering apparatus used for forming each layer constituting an information signal layer according to the first embodiment of the present invention.

FIG. 5 is a plan view showing a disk substrate according to the first embodiment of the present invention, a target, and their planar positional relationship.

FIG. 6 is a plan view showing a target used for manufacturing the optical disc according to the first embodiment of the present invention.

FIG. 7 is a cross-sectional view for explaining a fitting portion in the divided target according to the first embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a positional relationship between the disk substrate and the target along a plane perpendicular to the surfaces of the disk substrate and the target of the first example of the first embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a positional relationship between the disk substrate and the target along a plane perpendicular to the planes of the disk substrate and the target of the second example of the first embodiment of the present invention.

FIG. 10 is a plan view for explaining a planar positional relationship between a disk substrate and a target in a sputtering apparatus used for forming a reflective layer of an optical disk according to a first comparative example.

FIG. 11 is a graph showing a recording light emission pattern used when evaluating the jitter characteristic of the optical disc according to the first embodiment of the present invention.

FIG. 12 is a graph showing the recording power dependence of jitter at the inner and outer peripheral portions of the optical disc according to the first example based on the first embodiment of the present invention.

FIG. 13 is a graph showing the recording power dependence of jitter in the inner and outer peripheral portions of the optical disc according to the second example based on the first embodiment of the present invention.

FIG. 14 shows a first prior art for comparison with the first and second examples based on the first embodiment of the present invention.
7 is a graph showing the dependency of jitter on recording power in Comparative Example.

FIG. 15 is a sectional view showing an optical disc according to a second embodiment of the present invention.

FIG. 16 shows the dependency of jitter on the recording power in the outer peripheral portion of the optical disc according to the third embodiment based on the second embodiment of the present invention, and the outer peripheral portion of the optical disc according to the second comparative example based on the prior art. 6 is a graph showing the recording power dependency of jitter.

FIG. 17 is a sectional view showing another example of the information signal layer having the reflection layer according to the present invention.

FIG. 18 is a cross-sectional view showing an optical disk constituting a conventional DVD-RW.

FIG. 19 is a cross-sectional view showing a double-sided recording type DVD-RW and a single-sided recording type DVD-RW according to the related art.

FIG. 20 is a cross-sectional view showing an optical disk having a thin light transmitting layer and recording / reproducing an information signal by irradiating a laser beam to a disk substrate from the side where the light transmitting layer is provided. .

[Explanation of symbols]

1, 40: optical disk, 2, 41: disk substrate, 2a: one main surface, 2b: other main surface, 2c ...
Center hole, 3 ... first dielectric layer, 4 ... phase change recording layer, 5 ... second dielectric layer, 6 ... first reflective layer, 7 ... first Information signal layer, 8 ... protective layer,
9, 47: adhesive layer, 10: double-sided recording type optical disk, 13: single-sided recording type optical disk, 28: target, 28a, 28d: low concentration target portion, 2
8b, 28f ... high concentration target part, 28c ...
Fitting part, 28e ... Medium concentration target part, 34 ...
Substrate rotation drive unit, 35 ... bonding agent, 36 ... recording area, 42 ... second reflective layer, 43 ... third dielectric layer, 44 ... recording layer, 45 ... .4th dielectric layer, 4
6 ... second information signal layer, 48 ... light transmission protection layer,
49 ・ ・ ・ Light transmitting layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G11B 7/26 531 G11B 7/26 531 F term (reference) 4K029 AA24 BA22 BA23 BC07 BD00 BD09 CA05 DC04 DC13 5D029 JB13 KB03 KB08 MA13 MA14 MA17 RA19 RA34 RA45 RA46 RA49 WB11 5D121 AA02 AA04 AA05 AA07 AA09 EE03 EE09 EE13 FF01

Claims (66)

[Claims] A reflection layer formed on one main surface of a planar annular disk substrate and capable of reflecting a laser beam used for recording and / or reproducing of an information signal in a planar annular shape, and the information signal is transferred to the reflective layer. At least a recording layer configured to be recordable is provided, and the information signal is recordable and / or by rotating the disc substrate at a substantially constant angular velocity and irradiating the laser beam to at least the recording layer. An optical recording medium configured to be reproducible, wherein the reflective layer is made of an aluminum alloy in which an additive is added to aluminum, and the amount of the additive contained in the aluminum alloy forming the reflective layer Wherein the optical recording medium changes along the radial direction of the disk substrate. 2. The method according to claim 1, wherein an amount of the additive at an outer peripheral portion of the reflective layer is larger than an amount of the additive at an inner peripheral portion of the reflective layer. 2. The optical recording medium according to 1. 3. The method according to claim 1, wherein an amount of the additive added to the reflective layer increases from an inner peripheral portion to an outer peripheral portion of the reflective layer along a radial direction of the disk substrate. The optical recording medium according to claim 1, wherein 4. The optical device according to claim 1, wherein the additive is copper, and the content of the additive in the reflective layer is 0.5% by weight or more and 1.5% by weight or less. recoding media. 5. The optical recording medium according to claim 1, wherein an uneven groove track is formed on the one main surface of the disk substrate, and a track pitch of the groove track is 0.74 μm or less. . 6. The optical recording medium according to claim 1, wherein the recording layer is configured to be capable of recording the information signal by at least two reversibly changing states. 7. The optical recording medium according to claim 1, wherein said recording layer is made of a phase change material capable of recording said information signal by a phase change between a crystalline phase and an amorphous phase. . 8. A first information signal layer in which a first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer are sequentially laminated on one main surface of the disk substrate. Is provided, by irradiating the recording layer with laser light from the other main surface opposite to the one main surface of the disk substrate,
2. The optical recording medium according to claim 1, wherein the information signal is recordable and / or reproducible. 9. The disk drive according to claim 8, wherein a protection layer for protecting the first information signal layer is provided on the first information signal layer on one main surface of the disk substrate. Optical recording medium. 10. A second information signal layer in which the reflective layer, the third dielectric layer, the recording layer, and the fourth dielectric layer are sequentially laminated on one main surface of the disk substrate. And irradiating the disk substrate with laser light from the side where the second information signal layer is present toward the recording layer, so that the information signal can be recorded and / or reproduced. 2. The method according to claim 1, wherein
The optical recording medium according to the above. 11. A light transmission that allows at least the laser light to pass through the adhesive layer on the second information signal layer on one main surface of the disk substrate and protects the second information signal layer. The optical recording medium according to claim 10, further comprising a protective layer. 12. A reflective layer formed on one principal surface of a planar annular disk substrate and capable of reflecting a laser beam used for recording and / or reproduction of an information signal in a planar annular shape, and the information signal is transferred to the reflective layer. At least a recording layer configured to be recordable is provided, and the information signal is recordable and / or by rotating the disc substrate at a substantially constant angular velocity and irradiating the laser beam to at least the recording layer. An optical recording medium configured to be reproducible, wherein the reflective layer is made of a silver alloy in which an additive is added to silver, and the amount of the additive contained in the silver alloy constituting the reflective layer The optical recording medium is characterized by changing along a radial direction of the disk substrate having a flat annular shape. 13. The method according to claim 1, wherein an amount of the additive at an outer peripheral portion of the reflective layer is larger than an amount of the additive at an inner peripheral portion of the reflective layer. 13. The optical recording medium according to 12. 14. The optical recording medium according to claim 12, wherein said additive is at least one element selected from the group consisting of calcium, magnesium, palladium, iron and copper. 15. The additive is at least one element selected from the group consisting of calcium, magnesium, palladium, iron and copper, and the content of the additive in the reflective layer is 0.5% by weight. 3.3% or more
13. The composition according to claim 12, wherein the amount is not more than weight percent.
The optical recording medium according to the above. 16. The optical recording medium according to claim 12, wherein an uneven groove track is formed on said one main surface of said disk substrate, and a track pitch of said groove track is 0.74 μm or less. . 17. The optical recording medium according to claim 12, wherein the recording layer is configured to record the information signal by at least two reversibly changing states. 18. The optical recording medium according to claim 12, wherein said recording layer is made of a phase change material capable of recording said information signal by a phase change between a crystalline phase and an amorphous phase. . 19. A first substrate on one main surface of the disk substrate.
A first information signal layer, which is formed by sequentially laminating a dielectric layer, a recording layer, a second dielectric layer, and the reflective layer, and providing a first information signal layer on a side opposite to one main surface of the disk substrate. 13. The optical recording medium according to claim 12, wherein the information signal is recordable and / or reproducible by irradiating a laser beam from the main surface toward the recording layer. 20. A protection layer for protecting the first information signal layer on the first information signal layer on one main surface of the disk substrate.
10. The optical recording medium according to item 9. 21. A second information signal layer in which the reflective layer, the third dielectric layer, the recording layer, and the fourth dielectric layer are sequentially laminated on one main surface of the disk substrate. And irradiating the disk substrate with laser light from the side where the second information signal layer is present toward the recording layer, so that the information signal can be recorded and / or reproduced. 2. The method according to claim 1, wherein
3. The optical recording medium according to 2. 22. Light transmission protection for transmitting at least the laser beam and protecting the second information signal layer via an adhesive layer on the second information signal layer on one main surface of the disk substrate. 22. The optical recording medium according to claim 21, wherein a layer is provided. 23. A reflection layer formed on one principal surface of a planar annular disk substrate and capable of reflecting a laser beam used for recording and / or reproducing of an information signal in a planar annular shape, and the information signal is transferred to the reflective layer. In the method for manufacturing an optical recording medium provided with at least a recording layer configured to be recordable, the reflective layer is made of an aluminum alloy in which an additive is added to aluminum, and the reflection layer is contained in the aluminum alloy. A method for manufacturing an optical recording medium, comprising: forming the reflective layer so that the amount of the additive varies along the radial direction of the disk substrate. 24. The reflective layer is formed such that the additive amount of the additive monotonically increases from the inner periphery to the outer periphery of the reflective layer along a radial direction of the disk substrate. A method for manufacturing an optical recording medium according to claim 23. 25. The reflecting layer is formed by a sputtering method using a sputtering target made of the aluminum alloy and having different amounts of the additive in the inner periphery and the additive in the outer periphery. The method for manufacturing an optical recording medium according to claim 23, wherein the film is formed as a film. 26. The disk substrate and the sputtering target are opposed to each other, and a center axis of the disk substrate in a direction perpendicular to one main surface of the disk substrate and a surface perpendicular to a fixing surface of the sputtering target. 26. The method of manufacturing an optical recording medium according to claim 25, wherein the reflective layer is formed in a state where the central axes of the sputtering targets in the directions overlap each other. 27. When forming the reflective layer on at least one principal surface of the disk substrate, the disk substrate is
27. The method of manufacturing an optical recording medium according to claim 26, wherein the disk substrate is rotated in an in-plane direction around the central axis. 28. The sputtering target, wherein the additive amount of the additive in the outer peripheral portion is larger than the additive amount of the additive in the inner peripheral portion, whereby the aluminum in the outer peripheral portion of the reflective layer is used. 26. The optical recording medium according to claim 25, wherein an amount of the additive in the alloy is larger than an amount of the additive in the aluminum alloy in an inner peripheral portion of the reflective layer. Production method. 29. An addition amount of the additive in the inner peripheral portion and an additive amount of the additive in the outer peripheral portion are different from each other, and a middle peripheral portion sandwiched between the inner peripheral portion and the outer peripheral portion. Using a sputtering target configured to be different from any addition amount of the additive in the inner peripheral portion and the additive amount of the additive in the outer peripheral portion. 24. The method for manufacturing an optical recording medium according to claim 23, wherein said reflective layer is formed. 30. The reflective layer is formed so that the additive is copper and the content of the additive in the reflective layer is in the range of 0.5% by weight or more and 1.5% by weight or less. 3. The method according to claim 2, wherein
4. The method for producing an optical recording medium according to 3. 31. The optical recording medium according to claim 23, wherein an uneven groove track is formed on the one main surface of the disk substrate, and a track pitch of the groove track is 0.74 μm or less. Manufacturing method. 32. The method for manufacturing an optical recording medium according to claim 23, wherein said recording layer is made of a material which causes at least two reversible changes in state. 33. The method of manufacturing an optical recording medium according to claim 23, wherein said recording layer is made of a phase change material in which a phase change between a crystalline phase and an amorphous phase occurs. 34. A first surface on one main surface of the disk substrate.
Forming a first information signal layer by sequentially forming a dielectric layer, the recording layer, the second dielectric layer, and the reflective layer, thereby forming a first information signal layer on the opposite side to one main surface of the disk substrate. The method for manufacturing an optical recording medium according to claim 23, wherein the information signal is recordable and / or reproducible by irradiating a laser beam from the main surface toward the recording layer. 35. The apparatus according to claim 34, wherein a protection layer for protecting the first information signal layer is formed on the first information signal layer on one main surface of the disk substrate. A method for manufacturing an optical recording medium. 36. A second information signal layer in which the reflective layer, the third dielectric layer, the recording layer, and the fourth dielectric layer are sequentially laminated on one main surface of the disk substrate. By irradiating the disk substrate with laser light from the side where the second information signal layer is present toward the recording layer, the information signal can be recorded and / or reproduced. A method for manufacturing an optical recording medium according to claim 23. 37. A light transmission that allows at least the laser light to pass through an adhesive layer and protects the second information signal layer on the second information signal layer on one main surface of the disk substrate. The method for manufacturing an optical recording medium according to claim 36, wherein a protective layer is formed. 38. A reflection layer formed on one principal surface of a planar annular disk substrate and capable of reflecting a laser beam used for recording and / or reproducing of an information signal in a planar annular shape, and the information signal is transferred to the reflective layer. In the method for manufacturing an optical recording medium provided with at least a recording layer configured to be recordable, the reflection layer is made of a silver alloy in which an additive is added to silver, and the reflection layer is contained in the silver alloy. A method for manufacturing an optical recording medium, wherein the reflective layer is formed so that the amount of the additive varies along the radial direction of the disk substrate. 39. The reflective layer is formed such that the additive amount of the additive monotonically increases from an inner periphery to an outer periphery of the reflective layer along a radial direction of the disk substrate. The method for producing an optical recording medium according to claim 38. 40. The reflective layer is formed by a sputtering method using a sputtering target made of the silver alloy and having a different additive amount of the additive in the inner peripheral portion and an additive amount in the outer peripheral portion. The method for producing an optical recording medium according to claim 38, wherein the optical recording medium is formed into a film. 41. The disk substrate and the sputtering target are opposed to each other, and are perpendicular to a center axis of the disk substrate in a direction perpendicular to one main surface of the disk substrate and a fixing surface of the sputtering target. 41. The method for manufacturing an optical recording medium according to claim 40, wherein the reflective layer is formed in a state where the central axes of the sputtering targets in different directions overlap each other. 42. When forming the reflective layer on at least one principal surface of the disk substrate, the disk substrate is
42. The method for manufacturing an optical recording medium according to claim 41, wherein the disk substrate is rotated in an in-plane direction around the central axis. 43. A sputtering target in which the additive amount of the additive in the outer peripheral portion is larger than the additive amount of the additive in the inner peripheral portion as the sputtering target is added to the outer peripheral portion of the reflective layer. 41. The method of manufacturing an optical recording medium according to claim 40, wherein the amount of the additive is larger than the amount of the additive in the silver alloy in the inner peripheral portion of the reflective layer. . 44. An additive amount of the additive in the inner peripheral portion and an additive amount of the additive in the outer peripheral portion are different from each other, and a middle peripheral portion sandwiched between the inner peripheral portion and the outer peripheral portion. Using a sputtering target configured to be different from any addition amount of the additive in the inner peripheral portion and the additive amount of the additive in the outer peripheral portion. 39. The method for manufacturing an optical recording medium according to claim 38, wherein said reflective layer is formed. 45. The method according to claim 38, wherein the additive is at least one element selected from the group consisting of calcium, magnesium, palladium, iron and copper. 46. The reflective layer is formed such that the content of the additive in the reflective layer is in the range of 0.5% by weight or more and 3.3% by weight or less. The method for producing an optical recording medium according to claim 38. 47. The optical recording medium according to claim 38, wherein an uneven groove track is formed on said one main surface of said disk substrate, and a track pitch of said groove track is 0.74 μm or less. Manufacturing method. 48. The method of manufacturing an optical recording medium according to claim 38, wherein said recording layer is made of a material which causes at least two reversible changes in state. 49. The method for manufacturing an optical recording medium according to claim 38, wherein said recording layer is made of a phase change material in which a phase change between a crystalline phase and an amorphous phase occurs. 50. A first substrate on one main surface of the disk substrate.
Forming a first information signal layer by sequentially forming a dielectric layer, the recording layer, the second dielectric layer, and the reflective layer, thereby forming a first information signal layer on the opposite side to one main surface of the disk substrate. The method for manufacturing an optical recording medium according to claim 38, wherein the information signal is recordable and / or reproducible by irradiating a laser beam from the main surface to the recording layer. 51. A protection layer for protecting the first information signal layer on the first information signal layer on one main surface of the disk substrate. A method for manufacturing an optical recording medium. 52. A second information signal layer is formed by sequentially forming the reflective layer, the third dielectric layer, the recording layer, and the fourth dielectric layer on one main surface of the disk substrate. By irradiating the disk substrate with laser light from the side where the second information signal layer is present toward the recording layer, the information signal can be recorded and / or reproduced. The method for manufacturing an optical recording medium according to claim 38, wherein: 53. A light transmission that allows at least the laser light to pass through an adhesive layer and protects the second information signal layer on the second information signal layer on one main surface of the disk substrate. The method for producing an optical recording medium according to claim 52, wherein a protective layer is formed. 54. A sputtering target having a substantially cylindrical structure and one principal surface having a substantially circular shape of the above-mentioned cylindrical structure capable of being sputtered, wherein an additive is added to a material serving as a main component. At least the additive amount of the additive added to the outer peripheral portion of the one main surface of the circular shape and the additive amount of the additive contained in the central portion of the one main surface of the circular shape are different from each other. A sputtering target, which is configured to be different. 55. The sputtering target according to claim 54, wherein the material serving as the main component is aluminum. 56. The sputtering target according to claim 55, wherein the additive is copper. 57. The sputtering target according to claim 55, wherein the content of the additive is 0.5% by weight or more and 1.5% by weight or less. 58. The sputtering target according to claim 54, wherein the material serving as the main component is silver. 59. The sputtering target according to claim 58, wherein said additive comprises at least one element selected from the group consisting of calcium, magnesium, palladium, iron and copper. 60. The sputtering target according to claim 58, wherein the content of the additive is 0.5% by weight or more and 3.3% by weight or less. 61. An additive amount of the additive at an outer peripheral portion of the one main surface of the circular shape is larger than an additive amount of the additive at a central portion of the one main surface of the circular shape. 54. The sputtering target according to 54. 62. A first target portion having one main surface having a circular shape, and a second target portion having one main surface having an annular shape, wherein a central axis of the first target portion is provided. 55. The sputtering according to claim 54, wherein the first target portion is fitted into an opening of the second target portion while the center axis of the second target portion overlaps with the central axis of the second target portion. For target. 63. An additive amount of the additive added to the second target portion is larger than an additive amount of the additive added to the first target portion. 62. The sputtering target according to 62. 64. The second target portion is composed of a plurality of annular target portions, each of which has a main surface having an annular shape, and the plurality of annular target portions overlap each other while overlapping their central axes. 63. The sputtering target according to claim 62, wherein the sputtering target is fitted. 65. The amount of the additive added to one of the plurality of annular target portions constituting the second target portion, which is added to the inner periphery of the annular target portion, 65. The sputtering target according to claim 64, wherein the amount of the additive added to the annular target portion on the side and the first target portion is greater than the additive amount. 66. An optical recording medium capable of recording and / or reproducing information signals, comprising at least one layer of a laminated film formed on one main surface of a disk substrate, and the optical recording medium comprising: 55. A method for forming a reflective layer by a sputtering method capable of reflecting a laser beam used for recording and / or reproducing the information signal on a medium.
The target for sputtering according to the above.