JP2001176127A - Optical recording medium and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium which satisfies the limitation of the spacing loss in an optical system made higher in a numerical aperture and has sufficient preservation durability. SOLUTION: A magneto-optical disk 1 is constituted by successively laminating an under-coating layer 3, a thermal diffusion layer 4, a first dielectric layer 5, a recording layer 6 and a second dielectric layer 7 on a disk substrate 2. The second dielectric layer 7 is composed of diamond-like carbon. The deposition of the diamond-like carbon is executed by an RF sputtering method using gases formed by mixing gaseous H2, gaseous CH4 or gaseous C2H4 with gaseous Ar at a prescribed mixing ratio.

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 and a method of manufacturing the same, and more particularly, to a recording layer and a dielectric layer laminated on a substrate and recording an information signal by irradiating light from the dielectric layer side. / It is suitable for application to an optical recording medium for reproduction.

[0002]

2. Description of the Related Art Conventionally, a recording layer, a dielectric layer, and the like are sequentially laminated on a substrate, such as a magneto-optical disk and a phase-change optical disk, and light is incident on the recording layer in the laminated film. As a result, optical recording media on which information signals are read or written have become widespread.

[0003] In these optical recording media, the recording density has been increased in order to record as much information as possible.

[0004] With the increase in the density of such optical recording media, spot diameters of optical heads for recording / reproducing information signals on the optical recording media have been reduced. Various studies have been made to reduce the spot diameter of light applied to the recording layer.

Particularly, in recent years, a floating type optical head has been proposed which utilizes the technology of a floating type magnetic head employed in a hard disk device or the like.
This flying optical head is constructed by mounting an objective lens on a slider, and is used for recording / recording information signals.
The reproduction is performed from the side of the laminated film by floating so as to face the laminated film such as the recording layer and the dielectric layer of the optical recording medium.

As described above, when recording / reproducing an information signal by floating the floating optical head so as to face the laminated film, light from the floating optical head is incident from the laminated film side and the substrate is irradiated with light. Does not transmit. Therefore, the distance between the recording layer of the optical recording medium and the objective lens can be greatly reduced as compared with the conventional method in which light from the optical head is incident on the signal recording layer via the substrate. This makes it possible to increase the NA (numerical aperture) of the objective lens, and to reduce the spot diameter of light incident on the recording layer.

Further, recently, an optical system in which the NA is equivalently greater than 1 has been proposed (NFR, Near Fie).
ld Recording). According to this optical system, the spot diameter of light can be further reduced.

As described above, in the floating optical head adopted for the purpose of reducing the spot diameter of light, when recording / reproducing an information signal, the light is applied to the signal recording layer from the laminated film side. Is done. Therefore, in an optical recording medium in which information signals are recorded / reproduced by such a floating optical head, reverse film formation is adopted for film formation of the laminated film. That is, the order of lamination of the laminated films in this optical recording medium is the reverse of that in the conventional optical recording medium configured so that light enters through the substrate.

[0009]

The resolution of an optical disk is significantly improved by using an optical system with a high NA. However, in order to use an optical system with a higher NA, the distance (spacing loss) between the optical head and the signal recording layer of the optical recording medium must be reduced.

An optical recording medium employing the above-mentioned reverse order film formation meets such a demand. In other words, in the formation of the laminated film of the optical recording medium, by adopting the reverse film formation, the recording layer can be irradiated with light without passing through the substrate, so that the spacing loss can be significantly reduced. Becomes In an optical recording medium employing reverse film formation, the sum of the thickness of the protective film for protecting the signal recording layer and the flying height of the floating optical head is the spacing loss.

When NA is 1 or less, the flying height is
Since the thickness was from 100 to several thousand nm, the flying height itself was dominant in the spacing loss. However, the above-mentioned NF
When R is used, the spacing loss is limited to several tens of nm or less due to the relationship with the wavelength of the laser beam. Therefore, it is desirable that the thickness of the protective film is smaller than that in the related art.

On the other hand, in an optical recording medium employing reverse film formation, the storage durability of the signal recording layer has been ensured by a protective film made of a dielectric such as silicon nitride (SiN) and carbon (C). That is, in the optical recording medium, the protective film also requires optical characteristics. for that reason,
For the dielectric, SiN or the like is used. This SiN is
Although it is optically transparent and has chemical stability, it has a problem in mechanical lubricity. Therefore, in order to ensure lubricity, a layer made of C having excellent lubricity is provided on the dielectric. And the performance as this protective film is
It is closely related to its film thickness. That is, the storage durability improves as the thickness of the protective film increases. Therefore, it is desirable that the thickness of the protective film be large.

The above two requirements for the thickness of the protective film have a trade-off relationship with each other. That is, in order to improve the storage durability, it is necessary to increase the thickness of the protective film. On the other hand, when an optical system with a high NA such as NFR is adopted, the spacing loss is limited, so that it is necessary to reduce the thickness of the protective film. Therefore, compatibility of these is a major problem for realizing an optical recording medium compatible with high NA. Further, after performing recording by perpendicular magnetic recording using a magneto-optical recording material for the recording layer, GMR (Giant Magneto-Re
In a recording method in which reproduction is performed using a magnetic head such as a sistive) head, it is necessary to make the protective film thin.

Accordingly, an object of the present invention is to provide an optical recording medium which performs recording / reproduction by irradiating light from the side of a laminated film formed on a substrate, when using an optical system with a high NA. An object of the present invention is to provide an optical recording medium which can satisfy the limitation of loss and has sufficient storage durability and a method for manufacturing the same.

[0015]

In order to achieve the above object, a first invention of the present invention is to provide at least a first invention on a substrate.
Wherein the dielectric layer, the recording layer, and the second dielectric layer are sequentially laminated, wherein the second dielectric layer is made of diamond-like carbon.

In the first invention, typically, at least an undercoat layer and a heat diffusion layer are sequentially provided below the first dielectric layer on the substrate.

In the first invention, typically, the optical recording medium records / reproduces information signals by irradiating the substrate with light from the side where the recording layer exists.

According to a second aspect of the present invention, there is provided a method of manufacturing an optical recording medium in which at least a first dielectric layer, a recording layer, and a second dielectric layer are sequentially laminated on a substrate, The second dielectric layer is formed by depositing diamond-like carbon on the recording layer.

In the second aspect of the present invention, preferably, a mixed gas to which a gas containing hydrogen as a constituent element is added in forming the diamond-like carbon film. In the second invention, the gas containing at least hydrogen as a constituent element is at least one gas selected from the group consisting of hydrogen gas, methane (CH ₄ ) gas, and ethylene (C ₂ H ₄ ) gas. is there.

In the second invention, preferably, the gas containing hydrogen as a constituent element used for forming the diamond-like carbon is a hydrogen gas, and the mixing ratio of the hydrogen gas to the mixed gas is 10% or more and 25% or more. % Or less.

In the second invention, preferably, the gas containing hydrogen as a constituent element used for forming the diamond-like carbon is methane gas, and the mixing ratio of the methane gas to the mixed gas is 5% or more and 20% or less. It is.

In the second invention, preferably, the gas containing hydrogen as a constituent element used for forming the diamond-like carbon is ethylene gas, and the mixture ratio of ethylene gas to the mixed gas is 5% to 15%. % Or less.

In the second invention, typically, the thin film forming technique is a sputtering method or a plasma chemical vapor deposition (plasma CVD) method, but other film forming techniques can also be used.

In the present invention, the rare earth alloy constituting the recording layer is typically Tb ₂₀ (FeCo ₁₅ ) ₈₀ , but is preferably composed of Tb ₂₀ (FeCo ₁₀ ) ₈₀ and Tb ₂₀ (FeC ₁₅ ).
o ₂₀ ) ₈₀ , Tb ₂₁ (FeCo ₁₅ ) ₇₉ , Tb ₂₁ (FeCo ₁₅ )
₁₀ ) ₇₉ , Tb ₂₁ (FeCo ₂₀ ) ₇₉ , Tb ₂₄ (FeC
o ₁₅ ) ₇₆ , Tb ₂₄ (FeCo ₁₀ ) ₇₆ , Tb ₂₄ (FeCo _10
20 ) ₇₆ and, in these compositions, Tb, Dy
(Dysprosium), at least one rare earth alloy selected from the group consisting of those substituted with NdTb (neodymium terbium) or Gd (gadolinium). Further, in the present invention, preferably, the recording / reproducing layer is formed of a laminated film of a TbFeCo film and a GdFeCo film. The composition is G
d ₂₈ (FeCo ₁₅ ) ₇₂ , Gd ₃₂ (FeCo ₁₅ ) ₆₈ , Gd
₂₈ (FeCo ₂₅ ) ₇₂ or Gd ₃₂ (FeCo ₂₅ ) ₆₈ . Further, in the present invention, preferably, a TbFeCoCr alloy, Tb
A quaternary alloy such as an FeCoNi alloy or a TbFeCoSi alloy, or a quaternary alloy such as a DyFeCo alloy or a GdFeCo alloy.
It is also possible to use a base alloy. Further, in the present invention, a TbFeCo alloy, TbFeC
oCr alloy, TbFeCoNi alloy, TbFeCoSi
It is also possible to use a laminated film in which at least two kinds of rare earth alloys selected from the group consisting of an alloy, a DyFeCo alloy and a GdFeCo alloy are laminated. The rare earth alloys described above are optimized according to the wavelength of the light source used for recording / reproduction and the required functions.

According to the optical recording medium and the method of manufacturing the same according to the present invention, an optical recording medium having at least a first dielectric layer, a recording layer and a second dielectric layer on a substrate is provided. In the medium, the mechanical strength of the optical recording medium can be improved and the lubricity of the surface of the optical recording medium can be improved by forming the second dielectric layer from diamond-like carbon. Can be.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

First, a magneto-optical disk according to an embodiment of the present invention will be described. FIG. 1 shows a magneto-optical disk 1 according to this embodiment. Note that the magneto-optical disk 1 according to this embodiment is configured such that light is incident from the side where the laminated film is provided on the substrate by an optical head near the recording layer such as a floating optical head, for example. This is a magneto-optical disk of a type in which information signals are recorded / reproduced.

As shown in FIG. 1, a magneto-optical disk 1 according to this embodiment has an undercoat layer 3, a heat diffusion layer 4, a first dielectric layer 5, a recording layer 6 and a second Of dielectric layers 7 are sequentially laminated.

The disk substrate 2 is formed by molding a resin material into a disk shape by, for example, an injection molding method. As the resin material, for example, a low water-absorbing resin such as a cycloolefin polymer (for example, ZEONEX (registered trademark)) or polycarbonate is used. In one embodiment, for example, a resin made of a cycloolefin polymer is used. Note that, as the disk substrate 2, for example, a substrate made of a metal such as aluminum (Al) or a glass substrate can be used.

The undercoat layer 3 provided on the disk substrate 2 is made of, for example, SiN having a thickness of about 10 nm.
Consists of This undercoat layer 3 is
To prevent the water (H ₂ O) contained in the heat diffusion layer 4 and the recording layer 6 from diffusing. By preventing the diffusion of water in this way, the heat diffusion layer 4 and the recording layer 6 can be prevented.
Can reduce the occurrence of corrosion. The undercoat layer 3 is for improving the adhesion between the heat diffusion layer 4 and the disk substrate 2 as compared with the case where the undercoat layer 3 is not provided.

The thermal diffusion layer 4 provided on the undercoat layer 3 is made of, for example, Al, silver (Ag) or an alloy thereof having a thickness of about 40 nm. In this embodiment, for example, silver palladium is used. Copper alloy (AgPdC
u). The heat diffusion layer 4 is for diffusing heat generated inside the recording layer 6 due to light incident on the recording layer 6. By diffusing the heat generated in the recording layer 6 to the heat diffusion layer 4, the size of the recording mark in the recording layer 6 is controlled. Thereby, the recording / reproducing characteristics are maintained in a good state.

The first dielectric layer 5 provided on the thermal diffusion layer 4 is made of, for example, SiN having a thickness of 10 nm.
The first dielectric layer 5 is for optically enhancing the magneto-optical effect.

The recording layer 6 provided on the first dielectric layer 5 is made of a rare earth alloy composed of a rare earth metal terbium (Tb) and transition metals iron (Fe) and cobalt (Co). The composition of Tb is, for example, 19 to 24.
%. In this embodiment, the recording layer 6
Is formed of, for example, Tb ₂₀ (FeC
o ₁₅ ) _{Consists of 80} . This recording layer 6 produces a magneto-optical effect,
This is for recording an information signal.

The second dielectric layer 7 provided on the recording layer 6 is made of diamond-like carbon (DLC).
The thickness of the second dielectric layer 7 is, for example, 20 to 50 n.
m, and in this embodiment, for example, 35 nm. This second dielectric layer 7 is for improving the storage stability of the recording layer 6.

Next, a method of manufacturing the magneto-optical disk 1 configured as described above will be described.

In the method of manufacturing the magneto-optical disk 1 according to this embodiment, first, the disk substrate 2 for film formation is carried into a vacuum chamber and placed at a predetermined position.
Next, for example, using a mixed gas of Ar gas and N ₂ gas,
A SiN film is formed on the disk substrate 2 by a reactive sputtering method using a Si target. Thus, the undercoat layer 3 made of SiN is formed on the disk substrate 2. Here, the pressure of the mixed gas in the reactive sputtering method is, for example, 0.2 Pa.

Next, the disk substrate 2 on which the undercoat layer 3 is formed is carried into a vacuum chamber in which an AgPdCu target is installed, and is placed at a predetermined position. Next, AgPdCu is formed on the undercoat layer 3 by a sputtering method using, for example, a mixed gas obtained by adding N ₂ gas to Ar gas as a discharge gas and using a target made of AgPdCu. By this, Ag
A thermal diffusion layer 4 made of PdCu is formed. Here, as an example of sputtering conditions for forming the thermal diffusion layer 4, Ar gas is used as the gas, and the pressure is 0.5 Pa.

Next, the disk substrate 2 on which the heat diffusion layer 4 made of AgPdCu is formed is transported into a vacuum chamber in which a Si target is installed, and is placed at a predetermined position. Thereafter, for example, by sputtering using a mixed gas of Ar gas and N ₂ gas, S
iN is deposited. Thereby, the first dielectric layer 5 made of SiN is formed. Here, the pressure of the mixed gas is
For example, it is 0.5 Pa.

Next, the disk substrate 2 on which the first dielectric layer 5 is formed is transported to a vacuum chamber in which a target made of TbFeCo is installed, and is placed at a predetermined position. Then, Tb ₂₀ (FeCo ₁₅ ) _{80 is formed} on the first dielectric layer 5 by, for example, a sputtering method using Ar gas.
Is formed. Here, as an example of conditions for forming the recording layer 6, an Ar gas is used as an atmospheric gas, and the pressure is 0.5 Pa. Also, TbFeC
In addition to o, a multi-layer structure in which DyFeCo, GdFeCo, or an alloy film thereof is stacked can be used.

Next, the disk substrate 2 on which the recording layer 6 has been formed is transported to a sputtering chamber and placed at a predetermined position. After that, in this sputtering chamber, a DLC is formed on the recording layer 6 by, for example, an RF sputtering method. Here, in the film formation of the DLC by the RF sputtering method, for example, a mixed gas obtained by adding a gas containing H as a constituent element such as an H ₂ gas, a CH ₄ gas, or a C ₂ H ₄ gas to an Ar gas is used. . Here, when a mixed gas obtained by adding H ₂ gas to Ar gas is used, the mixing ratio of H ₂ gas is selected from 10 to 25%, and when a mixed gas obtained by adding CH ₄ gas to Ar gas is used, CH ₄ is used. The mixing ratio of the gas is selected from 5 to 20%, and when using a mixed gas obtained by adding C ₂ H ₄ gas to Ar gas, the mixing ratio of the C ₂ H ₄ gas is selected from 5 to 15%. As described above, the DLC containing H ₂ on the recording layer 6
A second dielectric layer 7 is formed.

Then, from the sputtering chamber,
The disk substrate 2 on which all the films are formed is unloaded. As described above, the intended magneto-optical disk 1 according to this embodiment is manufactured.

The storage durability of the magneto-optical disk 1 manufactured as described above and the optical characteristics of the second dielectric film 7 were evaluated. The evaluation of the storage durability and the optical characteristics was performed on a DLC film formed by changing the kind of the mixed gas and the mixing ratio of the gas variously. Table 1 shows the evaluation results. Here, as described above, the gas used at the time of film formation is Ar gas, H gas,
A mixed gas to which _two gases, CH ₄ gas or C ₂ H ₄ gas is added is used, and their mixing ratio is shown in parentheses. Regarding the storage durability of the magneto-optical disk 1, after performing an acceleration test for 600 hours in an environment at a temperature of 80 ° C. and a humidity of 85%, a defect in the magneto-optical disk 1 was observed by an optical microscope, If no defect with a diameter of 50 μm or more was observed at all over the entire surface, it was judged as good (indicated by 、), and if any defect was observed, as bad (indicated by x). did.

In Table 1, for comparison, a second dielectric layer 7 made of DLC, which was formed under conditions deviating from the film formation conditions of DLC in the above-described embodiment, is also similar. The results of the evaluation are also shown.

[0044]

[Table 1]

Experiment No. 1 in Table 1 1 to No. 7 indicates that when a mixed gas of Ar gas and H ₂ gas is used as a gas during DLC film formation, the storage durability of the magneto-optical disk 1 is poor when the mixing ratio of H ₂ gas is 30%. It turns out that it becomes.

In general, if the optical absorption coefficient of a film for a predetermined wavelength of light is 0.2 or less, the film is
It is almost transparent for the predetermined light wavelength. Therefore, it can be provided above the recording layer 6 of the magneto-optical disk 1. With this in mind, from Table 1, since the optical absorption coefficient when the mixing ratio is 5% or less of the H ₂ gas is understood that greater than 0.2, more than 5% of the mixing ratio of the H ₂ gas It can be seen that it is possible to use the DLC film formed under the condition of being larger and 10% or more as the upper layer of the recording layer 6 in the magneto-optical disk 1.

Therefore, the second on the surface of the magneto-optical disk 1
When the mixed layer of Ar gas and H ₂ gas is used in the DLC film formation, when the mixture ratio of H ₂ gas is 10 to 25%,
Magneto-optical disk 1 satisfying storage durability and optical characteristics
Can be manufactured.

In Table 1, the experiment No. 8 to No. From 13,
When a mixed gas of Ar gas and CH ₄ gas is used as a gas at the time of DLC film formation, the mixing ratio of CH ₄ gas is set to 20%.
When it is made larger and 25%, the magneto-optical disk 1
It can be seen that the storage durability was poor.

From Table 1, it can be seen that the optical absorption coefficient is larger than 0.2 when the mixing ratio of CH ₄ gas is 2.5%. This makes it possible to use the DLC film formed under the condition that the mixing ratio of the CH ₄ gas is larger than 2.5% and 5% or more as the upper layer of the recording layer 6 in the magneto-optical disk 1. It turns out that it becomes.

Therefore, the second on the surface of the magneto-optical disk 1
In the case where a mixed gas of Ar gas and CH ₄ gas is used in the DLC film formation, when the mixing ratio of CH ₄ gas is 5 to 20%,
Magneto-optical disk 1 satisfying storage durability and optical characteristics
Can be manufactured.

In Table 1, the experiment No. 14-No. From FIG. 18, when a mixed gas of Ar gas and C ₂ H ₄ gas is used as a gas at the time of film formation of DLC, when the mixture ratio of C ₂ H ₄ gas is made larger than 15% and 20%, It can be seen that the storage durability of the magneto-optical disk 1 is poor.

Table 1 shows that the optical absorption coefficient is larger than 0.2 when the mixing ratio of C ₂ H ₄ gas is 2.5%. Thereby, the DLC film formed under the condition that the mixing ratio of the C ₂ H ₄ gas is larger than 2.5% and 5% or more is used as the upper layer of the recording layer 6 in the magneto-optical disk 1. It turns out that it becomes possible.

Therefore, the second on the surface of the magneto-optical disk 1
When the mixed layer of Ar gas and C ₂ H ₄ gas is used in the film formation of DLC, the mixture ratio of C ₂ H ₄ gas is set to 5 to 15%. Furthermore, the magneto-optical disk 1 satisfying the storage durability and the optical characteristics can be manufactured.

From the above evaluations, the second dielectric layer 7 provided on the recording layer 6 of the magneto-optical disk 1 is composed of DLC, and is used when forming the second dielectric layer 7 composed of DLC. By setting the conditions of the gas to be used as the conditions in one embodiment, the optical characteristics are satisfied, the storage durability,
It can be seen that the magneto-optical disk 1 excellent in denseness can be manufactured.

As described above, according to this embodiment, the second dielectric layer 7 provided on the recording layer 6 is made of diamond-like carbon (DLC), so that the magneto-optical disk 1 The lubricating property of the outermost layer can be improved while maintaining the storage durability of the magneto-optical disk 1, and the mechanical strength of the magneto-optical disk 1 can be improved. Thus, the thickness of the second dielectric layer 7 can be reduced while maintaining sufficient protection characteristics and recording characteristics in the recording layer 6, so that the spacing loss can be reduced. Therefore, a high NA such as NFR is used for recording / reproducing with respect to the magneto-optical disk 1.
In the case where a simplified optical system is used, or in the case where recording is performed by perpendicular magnetic recording and reproduction is performed using a magnetic head such as a GMR head, the spacing loss can be sufficiently reduced. In addition, since the mechanical strength of the magneto-optical disk 1 can be improved, the film formation surface of the magneto-optical disk 1 can be directly mechanically chucked in a reproducing apparatus. In the conventional method, it is not necessary to provide a region where a film is not formed by a mask, that is, a so-called inner and outer peripheral mask region. As a result, the film formation process can be performed without using a mask, so that corrosion from the end of the substrate of the magneto-optical disk 1 can be controlled.

Further, a phase change type optical disk using the phase change recording layer as the recording layer 6 was also manufactured by the same method as the above-mentioned manufacturing method. In this optical disk, the same effect as in the above-described magneto-optical disk 1 was confirmed.

Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. is there.

For example, the materials and thicknesses of the respective layers of the magneto-optical disk 1 described in the above-described embodiment are merely examples, and different materials and thicknesses may be used as necessary.

Further, for example, in the above-described embodiment, the present invention is applied to a magneto-optical disk. However, the present invention can be applied to other optical recording media having a different recording method other than the magneto-optical disk. For example, the present invention
D, CD-ROM, DVD-ROM, etc., a read-only optical recording medium for reproducing information signals using the presence or absence of concave and convex pits and holes, and the difference in reflectance between the crystalline phase and the amorphous phase;
It has a write-once optical recording medium using an organic dye such as a CD-R, or a recording layer made of a germanium (Ge) alloy or an indium (In) alloy, and has a crystal phase and an amorphous phase in this recording layer. It is also possible to apply the present invention to a rewritable optical recording medium such as a phase change type optical disk which records / reproduces a signal by utilizing the phase change of the optical recording medium.

For example, in the above embodiment,
The recording layer 6 may have a multilayer structure in which magneto-optical recording / reproducing layers having different properties are stacked. Further, a structure capable of performing magnetic super-resolution and magnetic domain expansion reproduction may be provided by a multilayer film including a magneto-optical recording / reproducing layer and a layer other than the magneto-optical recording / reproducing layer.

For example, in the above-described embodiment, the formation of the recording layer 6 made of TbFeCo
Although the recording layer 6 is formed by a sputtering method using a Co target, the recording layer 6 may be formed by a simultaneous sputtering method using a Tb target, an Fe target, and a Co target. In addition, Cr (chromium) is added to TbFeCo,
An additive such as Ni (nickel) or Si (silicon) may be mixed.

Further, for example, in the above-described embodiment, an example in which the second dielectric layer 7 made of DLC is formed by a sputtering method has been described. As the sputtering method, magnetron sputtering method, collimated sputtering Method, long throw sputtering method,
RF sputtering, ECR sputtering, R
An F-DC coupled bias sputtering method or the like can be used. Further, the film formation of the second dielectric layer 7 is performed by DC
Plasma CVD using a power supply type plasma CVD apparatus
It is also possible to use a method, and it is also possible to form a film using an apparatus such as an ion plating apparatus or a plasma polymerization apparatus utilizing a plasma reaction. Further, as a plasma CVD apparatus, an RF power supply type plasma CVD is used.
It is also possible to use an apparatus, an ECR plasma CVD apparatus, a helicon wave plasma CVD apparatus, or the like.

Further, for example, in the above-described embodiment, a layer made of AgPdCu is used as the heat diffusion layer 4.
It is also possible to use a nitride containing Al such as 1N or AlTiN.

[0064]

As described above, according to the present invention, in an optical recording medium in which at least a first dielectric layer, a recording layer, and a second dielectric layer are sequentially laminated on a substrate, Since the dielectric layer is made of diamond-like carbon, sufficient storage durability can be ensured in an optical recording medium that performs recording / reproduction by irradiating light from the side of the laminated film formed on the substrate. In addition, it is possible to obtain an optical recording medium capable of reducing a spacing loss to an extent that satisfies a restriction when employing an optical system with a high NA.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a magneto-optical disk according to an embodiment of the present invention.

[Description of Signs] 1 ... Magneto-optical disk, 2 ... Disk substrate, 3 ...
..Undercoat layer, 4 ... thermal diffusion layer, 5 ... first dielectric layer, 6 ... recording layer, 7 ... second dielectric layer

Claims (9)

[Claims] 1. An optical recording medium in which at least a first dielectric layer, a recording layer, and a second dielectric layer are sequentially laminated on a substrate, wherein the second dielectric layer is made of diamond-like carbon. Characteristic optical recording medium. 2. The optical recording medium according to claim 1, wherein at least an undercoat layer and a heat diffusion layer are sequentially laminated below the first dielectric layer on the substrate. . 3. The method according to claim 1, wherein when recording / reproducing information on / from the recording layer, the substrate is irradiated with light from a side where the second dielectric layer exists. The optical recording medium according to claim 1, wherein: 4. At least a first dielectric layer on a substrate,
In a method for manufacturing an optical recording medium in which a recording layer and a second dielectric layer are sequentially laminated, the second dielectric layer is formed by forming diamond-like carbon on the recording layer by a thin film forming technique. A method for manufacturing an optical recording medium, wherein 5. The method for producing an optical recording medium according to claim 4, wherein a mixed gas to which a gas containing hydrogen is added as a constituent element is used in the film formation of the diamond-like carbon. 6. The gas containing hydrogen as the constituent element,
5. The method according to claim 4, wherein the gas is at least one kind of gas selected from the group consisting of hydrogen gas, methane gas, and ethylene gas. 7. The optical recording according to claim 4, wherein the gas containing hydrogen as the constituent element is hydrogen gas, and a mixing ratio of the hydrogen gas to the mixed gas is 10% or more and 25% or less. The method of manufacturing the medium. 8. The optical recording medium according to claim 4, wherein the gas containing hydrogen as a constituent element is methane gas, and a mixing ratio of the methane gas to the mixed gas is 5% or more and 20% or less. Production method. 9. The optical recording according to claim 4, wherein the gas containing hydrogen as the constituent element is ethylene gas, and a mixing ratio of the ethylene gas to the mixed gas is 5% or more and 15% or less. The method of manufacturing the medium.