JP2002275626A - Sputtering target, silicon carbide film, optical disk and production method for the optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive optical disk or the like which has little deterioration in quality even when repeatedly used. SOLUTION: The optical disk is provided with a first dielectric layer 2, a phase change recording layer 3, a second dielectric layer 4 and a reflection later 6 successively formed on a transparent substrate 1. A silicon carbide film 5 in an amorphous state which substantially does not contain freed carbon atoms and deposited while circulating an inert gas containing oxygen by applying a d.c. sputtering process to a sputtering target consisting of silicon carbide containing a silicon carbide having a cubic zinc blende structure (β type) by >=50 mol%, and in which the atomic number ratio between carbon and silicon is higher than 1/1 which is a stoichiometric composition, and containing surplus carbon in the range of <=20 mol%, constitutes at least a part of the second dielectric layer 4. The silicon carbide film 5 is arranged so as to be adjacent to the reflection layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target, a silicon carbide film, and an optical disk and a method for manufacturing an optical disk using the same, which can manufacture an optical disk which is inexpensive and has excellent durability.

[0002]

2. Description of the Related Art Recently, compact discs (CD, Comp
act Disk) and digital versatile disk (DVD, Digita)
l Rewritable (recordable) optical recording media, CD-RW (Compact Disk) in optical disks such as Versatile Disk
-ReWritable) and DVD-RW (Digital Versatile D)
isk-ReWritable) is widely used as a recording medium for storing data having a large data amount such as a moving image.

Conventionally, these rewritable recording media include a first dielectric layer, a phase change recording layer, a second dielectric layer, a reflective layer, and a protective layer which are sequentially formed on a transparent substrate such as glass. It is composed of The phase-change recording layer is made of a material that can transition between a crystalline state and an amorphous state, and is in a crystalline state at the beginning. A pulse-modulated laser beam is locally (recorded bit) applied to the crystalline phase change recording layer.
To melt a predetermined recording bit, rapidly cool it, and change it to an amorphous state. With the phase change, a predetermined recording bit changes its complex refractive index and records information modulated by laser light. At the time of reproduction, a low-output laser beam is irradiated to detect a difference in reflectance or a phase difference corresponding to the change in the complex refractive index, and read recorded information.

[0004] Further, recording is performed by irradiating a recording bit with a laser beam of low output necessary and sufficient for crystallizing the amorphous phase change recording layer and a laser beam containing rewriting information. The rewrite information is recorded over the information already recorded in the bit (overwrite,
Over Write).

At the time of this overwriting, the phase change recording layer is rapidly heated to a temperature equal to or higher than the melting point, melts, and is further rapidly cooled to solidify. In some cases, not only the dielectric layer in contact with the phase change recording layer but also the reflective layer and the transparent substrate may be deformed. In particular, when the rewriting operation is repeated, old data remains without being erased, or the S / N ratio (Signal to No.
This causes a phenomenon such as a decrease in ise), and causes a reading error during reproduction.

Therefore, for example, in Japanese Patent Application Laid-Open No. H11-3538, at least the second dielectric layer of the first and second dielectric layers is formed by high-frequency sputtering. A phase change optical disk composed of a silicon carbide layer is disclosed. By irradiation of laser light,
The heat generated in the phase change recording layer is satisfactorily conducted to the dielectric layer containing silicon carbide having good thermal conductivity and is dissipated, thereby reducing thermal damage to the phase change recording layer. In addition, the high rigidity of silicon carbide suppresses thermal deformation of the transparent substrate, so that rewriting performance can be improved.

Generally, silicon carbide having a rhombohedral wurtzite type structure (α type) having a stable crystal state is used as silicon carbide for a sputtering target. But,
Since α-type silicon carbide has a high specific resistance, a DC sputtering method requiring high electrical characteristics (low specific resistance) cannot be applied. Therefore, a high-frequency sputtering method is often used instead. The DC sputtering method can perform sputtering with an inexpensive apparatus configuration and has a high film forming rate.
The inability to apply the DC sputtering method is inconvenient for forming an inexpensive silicon carbide film. Furthermore, silicon carbide having a rhombohedral wurtzite type structure (α type) is more expensive than silicon carbide having a cubic zincblende type structure (β type) having another crystal structure.

In the case where the formed silicon carbide film has free silicon atoms in its crystal structure, the free silicon atoms diffuse into the adjacent phase change recording layer to improve optical recording characteristics. There is a problem of deterioration.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a sputtering target and a silicon carbide film capable of manufacturing an inexpensive optical disk having excellent durability. And Also,
It is another object of the present invention to provide an inexpensive optical disk and a method for manufacturing the optical disk, which have low quality deterioration even when used repeatedly.

[0010]

In order to achieve the above object, a sputtering target according to a first aspect of the present invention contains at least 50 mol% of silicon carbide having a cubic zinc-blende type structure (β type) and has a room temperature. , And is made of silicon carbide having a resistivity of 10 ⁻¹ Ωcm or less.

According to this structure, a sputtering target composed of silicon carbide having high conductivity (small resistivity) using inexpensive silicon carbide having a cubic zinc-blende type structure (β type) as a main component. Get. Since this sputtering target has a specific resistance to which a DC sputtering method can be applied, a silicon carbide film can be formed quickly and inexpensively by a DC sputtering method with a high film forming speed with a simple apparatus configuration.

Silicon carbide has a rhombohedral wurtzite structure (α
) And silicon carbide having a cubic zinc-blende type structure (β type). Silicon carbide having a cubic zinc-blende type structure (β type) transforms into a rhombohedral wurtzite type structure (α type) when processed at a high temperature in order to be processed into a predetermined shape as a sputtering target. By previously adding silicon carbide having a rhombohedral wurtzite structure (α type) to silicon carbide having a cubic zinc blende type structure (β type), the manufacturing time of a sputtering target can be reduced.

The silicon carbide may be formed by reacting and sintering powdery silicon carbide. For example, a powdery silicon carbide placed in a mold having a desired shape is processed at a high temperature and a high pressure, so that a sputtering target having a predetermined shape can be easily obtained.

[0014] The silicon carbide may have an atomic ratio of carbon to silicon of more than 1/1, which is the stoichiometric composition, and may contain an excess of carbon atoms within 20 mol%. Due to the excess carbon atoms, a sputtering target having a small specific resistance (high conductivity) to which a DC sputtering method can be applied can be obtained. In order to introduce excess carbon atoms into the sputtering target, powdered silicon carbide having a stoichiometric composition is mixed with powdered carbon, and a molded product obtained by reacting and sintering the mixture is used as a sputtering target. It is good. Thereby, a sputtering target having a small specific resistance can be easily manufactured.

In order to achieve the above object, the silicon carbide film according to the second aspect of the present invention has a cubic zinc-blende type structure (β
(Type) silicon carbide of at least 50 mol%, and has a specific resistance at room temperature of 10 ⁻¹ Ωcm or less. It is characterized by the following.

According to this structure, a silicon carbide film having low light absorption and suitable for a protective film of an optical disk is formed by using an inexpensive sputtering target mainly composed of silicon carbide having a cubic zinc-blend type structure (β type). , But cheap and quick.

In order to achieve the above object, the silicon carbide film according to the third aspect of the present invention has a cubic zinc-blend-type structure (β
Type) silicon carbide of at least 50 mol%, and the atomic ratio of carbon to silicon is larger than 1/1, which is a stoichiometric composition,
A sputtering target composed of silicon carbide containing an excess of carbon within 20 mol%, which is a coating in an amorphous state containing substantially no free carbon atoms, formed by applying a direct current sputtering method; It is characterized by the following.

According to this configuration, excess carbon introduced into the sputtering target to reduce the specific resistance so that the DC sputtering method can be applied is removed at the time of forming a film using the DC sputtering method. Since it does not contain free carbon which causes a decrease in the transparency of the coating, the transparency of the coating can be increased (light absorption can be reduced). Therefore, an inexpensive cubic zinc-blende type structure (β
By using a sputtering target mainly composed of silicon carbide of (type), a silicon carbide film having low light absorption and suitable for a protective film of an optical disk can be obtained.

In an oxygen-containing atmosphere, excess carbon introduced into the sputtering target may be removed as a gaseous oxide. Excess carbon is combined with oxygen and removed as a carbon oxide (mainly carbon dioxide) out of the system, whereby a silicon carbide film containing no free carbon can be easily obtained. Also, even if liberated silicon atoms that degrade the optical recording characteristics of the phase-change recording layer are present in the sputtering target, they can be combined with oxygen to form silicon oxide, thereby forming an amorphous silicon carbide film. Because it can be fixed inside, it is convenient.

In order to achieve the above object, an optical disc according to a fourth aspect of the present invention comprises a first dielectric layer, a phase change recording layer, and a second dielectric layer formed sequentially on a transparent substrate. An optical disc comprising a layer and a reflective layer, comprising at least 50 mol% of silicon carbide having a cubic zinc-blende type structure (β type),
An amorphous silicon carbide film formed by applying a DC sputtering method to a sputtering target composed of silicon carbide having a specific resistance at room temperature of 10 ⁻¹ Ωcm or less is formed on the second dielectric layer. Constitute at least a part of
It is arranged so as to be adjacent to the reflection layer.

According to this structure, the sputtering using a direct current power supply is applied by using an inexpensive sputtering target mainly composed of silicon carbide having a cubic zinc-blend-type structure (β type), so that light absorption is reduced. An optical disk in which a small silicon carbide film suitable for a protective film of an optical disk is quickly and inexpensively formed can be obtained.

In order to achieve the above object, an optical disk according to a fifth aspect of the present invention comprises a first dielectric layer, a phase change recording layer, and a second dielectric layer sequentially formed on a transparent substrate. An optical disc comprising a layer and a reflective layer, comprising at least 50 mol% of silicon carbide having a cubic zinc-blende type structure (β type),
The atomic ratio of carbon to silicon is 1/1, which is the stoichiometric composition.
A substantially amorphous carbon-free amorphous film formed by applying a direct current sputtering method to a sputtering target composed of silicon carbide containing an excess of carbon within 20 mol% or more. The silicon carbide film in a state forms at least a part of the second dielectric layer, and is arranged so as to be adjacent to the reflective layer.

According to this structure, the excess carbon introduced to reduce the specific resistance at the time of forming the film is removed by the simple structure of the apparatus and the DC sputtering method with a high film forming rate can be applied. In addition, the transparency of the film can be increased (light absorption can be reduced). Therefore, using a low-cost sputtering target mainly composed of silicon carbide having a cubic zinc-blende structure (β-type), an inexpensive and quick silicon carbide film suitable for a protective film of an optical disk with low light absorption is formed. The obtained optical disk is obtained.

The sputtering target may be treated in an oxygen-containing atmosphere to remove excess carbon as a gaseous oxide.

[0025] The second dielectric layer may be made of zinc sulfide-metal oxide, and the reflective layer may be made of silver or a silver alloy. Silver or a silver alloy is relatively inexpensive and has a high reflectance, so that it is suitable as a reflective layer. However, it has a disadvantage that it easily deteriorates by sulfurization. Since the silicon carbide film has an effect of restricting mass transfer, by being disposed between the second dielectric layer and the reflective layer,
It is possible to suppress the sulfur or silver alloy from being degraded by sulfuration due to the zinc sulfide-metal oxide constituting the second dielectric layer.

The phase change recording layer is made of Te, Se, S
It may be composed of a chalcogenide containing at least one element. The chalcogenide is suitable as a phase change recording layer because it can easily transition from a crystalline state to an amorphous state. Further, among chalcogenides, an In-Sb-Te alloy may be applied to the phase change recording layer.

In order to achieve the above object, a method for manufacturing an optical disc according to a sixth aspect of the present invention comprises the steps of:
A method for manufacturing an optical disk, comprising: sequentially forming a first dielectric layer, a phase change recording layer, a second dielectric layer, and a reflective layer, wherein the second dielectric layer is formed. The step of forming at least a part of the second dielectric layer and disposing a silicon carbide film adjacent to the reflective layer, wherein the silicon carbide film has a cubic zinc-blende structure (β-type). ) Containing at least 50 mol% of silicon carbide;
A sputtering target composed of silicon carbide having a resistivity at room temperature of 10 ⁻¹ Ωcm or less is a coating in an amorphous state formed by applying a DC sputtering method.
It is characterized by the following.

According to this method, the direct current sputtering method is applied to an inexpensive sputtering target mainly composed of silicon carbide having a cubic zinc-blende type structure (β type), thereby protecting the optical disk with low light absorption. An optical disk in which a silicon carbide film suitable for the film is quickly and inexpensively formed can be obtained.

In order to achieve the above object, a method for manufacturing an optical disk according to a seventh aspect of the present invention comprises:
A method for manufacturing an optical disk, comprising: sequentially forming a first dielectric layer, a phase change recording layer, a second dielectric layer, and a reflective layer, wherein the second dielectric layer is formed. Forming at least a portion of the second dielectric layer and forming a silicon carbide film adjacent to the reflective layer, wherein the silicon carbide film has a cubic zinc-blend structure (β-type). ) Containing at least 50 mol% of silicon carbide;
The atomic ratio of carbon to silicon is 1/1, which is the stoichiometric composition.
An amorphous state substantially free of carbon atoms and formed by applying a direct current sputtering method to a sputtering target composed of silicon carbide containing carbon in excess of 20 mol% or more. A coating.

According to this method, the excess carbon introduced to reduce the specific resistance so that the DC sputtering method having a high film forming rate can be applied with a simple apparatus configuration is removed at the time of film formation. In addition, the transparency of the film can be increased (light absorption can be reduced). Therefore, using a low-cost sputtering target mainly composed of silicon carbide having a cubic zinc-blende structure (β-type), an inexpensive and quick silicon carbide film suitable for a protective film of an optical disk with low light absorption is formed. The obtained optical disk is obtained.

The sputtering target may be treated in an oxygen-containing atmosphere to remove excess carbon as a gaseous oxide.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A sputtering target, a silicon carbide film, an optical disk and a method for manufacturing an optical disk according to an embodiment of the present invention will be described below with reference to the drawings.

Silicon carbide (SiC) is classified into a rhombohedral wurtzite type structure (α type), a cubic zinc-blende type structure (β type), and an amorphous fibrous structure. β-type silicon carbide is in powder form, is inexpensive, has low specific resistance, and is suitable as a sputtering target material as compared with α-type silicon carbide.

At room temperature (for example, in the range of 15 ° C. to 25 ° C.), 1
It is necessary to adjust the specific resistance to 0 ^-1 Ωcm or less. Therefore, when the ratio of carbon atoms (C) to silicon atoms (Si), which is the stoichiometric composition of the silicon carbide, is less than 1: 1 and within a range of 20 mol%, excess carbon atoms having good conductivity are added. The carbon powder is added so as to contain. At this time, powder of α-type silicon carbide may be appropriately added within a range not exceeding the component amount of β-type silicon carbide. β-type silicon carbide finally transitions to an α-type crystal structure during the production of a sputtering target described later. Therefore, in advance, α
By adding the silicon carbide of the mold as a component of the sputtering target material, the manufacturing time can be reduced.

Next, a method for manufacturing a sputtering target will be described. Silicon powder containing β-type silicon carbide as a main component (50 mol% or more) and carbon powder corresponding to an excess carbon component within 20 mol% of the stoichiometric composition of silicon carbide, Is mixed in an inert atmosphere using a mixing apparatus suitable for dry mixing of the powder, for example, a ball mill, for a predetermined time until the powder is uniformly dispersed in the silicon carbide powder to obtain a raw material powder for a sputtering target. Here, the particle size of the silicon carbide powder and the carbon powder used is not particularly limited. The carbon powder can be uniformly dispersed, and the silicon carbide powder or the carbon powder is in a cluster.
Any particle size may be used so as not to cause secondary aggregation such as r).

This raw material powder is filled into a mold having a predetermined shape,
The reaction is sintered by heating and pressurizing (high temperature and high pressure) for a predetermined time in a reduced-pressure atmosphere using a hot press (Hot Press) device having heat up and down. The surface of the obtained reaction sintered body is mechanically polished so as to have a smoothness such that non-uniformity of sputtering does not substantially occur.
Mechanical polishing of about μm is performed to remove irregularities on the surface to obtain a sputtering target having a predetermined shape.

Next, a method of forming a silicon carbide film using the sputtering target obtained as described above will be described. The sputtering method is roughly classified into a radio frequency (RF, Radio Frequency) sputtering method in which a high frequency voltage is applied and a direct current (DC, Direct Current) sputtering method in which a DC voltage is applied, depending on the type of voltage applied between the electrodes. You. It is desirable to use DC sputtering from the viewpoint that an inexpensive power supply is used, the apparatus configuration is simple, the film formation rate is high, and the temperature rise of the transparent substrate on which the film is formed can be suppressed. Further, a permanent magnet or an electromagnet may be arranged near the sputtering target and used in combination with a magnetron sputtering method that generates a magnetic field. Since the plasma density of the sputtering gas can be increased by the magnetic field applied near the sputtering target, the deposition rate can be increased.

A silicon carbide film having a composition deviating from the stoichiometric composition results in reduced film transparency. For this reason, the signal intensity at the time of recording / reproducing is reduced, which leads to deterioration of the recording characteristics of the optical disk. Therefore, in order to apply the DC sputtering method, using a sputtering target having an excess of carbon than the stoichiometric composition, and actually forming a film on the optical disc, the oxygen contained in the sputtering gas, Excess carbon content needs to be removed. Therefore, as a sputtering gas to be used, an inert gas (such as argon Ar) and oxygen are mixed at a predetermined ratio, and a predetermined flow rate is supplied to the sputtering apparatus.
Distribute. Here, the mixing ratio of oxygen includes a sufficient amount of oxygen to remove excess carbon atoms contained in the sputtering target as oxides (mainly carbon dioxide) out of the system, and includes a sputtering gas (inert gas).
It is sufficient that the stable plasma generation state is not hindered.

If the sputtering target contains free silicon atoms, the free silicon atoms will be present in the silicon carbide film formed by sputtering. In this case, the liberated silicon atoms diffuse into the phase change recording layer, and deteriorate the recording characteristics of the phase change recording layer. However, the silicon atoms released by the oxygen contained in the sputtering gas are fixed as silicon oxide (silicon oxide) in the amorphous silicon carbide film, so that the recording characteristics of the phase change recording layer are deteriorated. Never.

Next, the structure of the optical disk according to the embodiment of the present invention and a method of manufacturing the optical disk will be described. A first dielectric layer, a phase change recording layer, and a second dielectric layer were sequentially formed on a transparent substrate formed of glass or a transparent plastic such as polycarbonate on which a silicon carbide film was formed. The optical disk is fixedly arranged in a state facing the sputtering target. Alternatively, the optical disc may be rotatably arranged, and the sputtering process may be performed while rotating at a position facing the sputtering target.

The silicon carbide film formed by applying the direct current sputtering method as described above was observed by a transmission electron microscope (TEM), regardless of the crystal structure of the silicon carbide of the sputtering target. Has been found to be amorphous. Therefore, even when a raw material powder obtained by mixing α-type silicon carbide and β-type silicon carbide is used, the obtained silicon carbide film is the same.

Here, the first and second dielectric layers are desirably made of a transparent zinc sulfide (ZnS) -metal oxide. More preferably, the first and second dielectric layers are made of ZnS—SiO ₂ or ZnS—N
b ₂ O ₅ . Cycle characteristics of rewriting and additional writing (overwrite, overwrite) and stability over time can be achieved, and the number of times of repetitive use can be increased. Further, the second dielectric layer may be substantially composed of only a silicon carbide film.

Further, as the phase change recording layer, Te, S
e, In-Sb-Te containing at least one element of S
It is preferable to be composed of a chalcogenide such as a system, Ge-Sb-Te system or Ge-Te system. More preferably, the phase change recording layer has a high transition speed between a crystalline state and an amorphous state, and has a relatively stable amorphous state.
-Sb-Te alloy. Cycle characteristics such as the number of repetitions and the number of rewrites can be improved. In addition, silver (Ag) is added to the In-Sb-Te system.
An alloy to which phase addition or the like is added may be used for the phase change recording layer.

The phase change recording layer, like the silicon carbide film,
The film is formed using a DC sputtering method. on the other hand,
The first and second dielectric layers are formed using a high-frequency sputtering method due to their electrical characteristics.

The reflection layer is formed on a silicon carbide film formed as a protective film on the second dielectric layer. The reflective layer
It is composed of a metal element or a metal compound (alloy) having a high reflectance with respect to the wavelength of the recording / reproducing laser beam. For example, silver (Ag), aluminum (Al),
Silicon (Si) -based and germanium (Ge) -based materials are preferred. The reflection layer is more preferably made of a silver or aluminum metal element or an alloy thereof having high reflectance even in a short wavelength region.

When the reflective layer is made of silver or a silver alloy, if the reflective layer is in direct contact with the second dielectric layer, zinc sulfide-metal oxide constituting the second dielectric layer There is a possibility that sulfur (S) element derived from the substance diffuses into the reflective layer and causes sulfur sulfide deterioration. However, since the silicon carbide film disposed between the reflective layer and the second dielectric layer has a sufficiently dense structure even in an amorphous state, mass transfer is suppressed. effective. Therefore, since the sulfur element cannot diffuse into the reflection layer via the silicon carbide film, the silver element in the reflection layer does not deteriorate by sulfurization.

The reflection layer is formed by applying a direct current sputtering method similarly to the silicon carbide film.

The thicknesses of the first dielectric layer, the phase change recording layer, the second dielectric layer, the silicon carbide film, and the reflective layer formed sequentially on the transparent substrate are as follows. It is set to a practical range based on the required optical characteristics, thermal characteristics, and mass transfer characteristics.

The bonding substrate is adhered to the optical disk on which the reflective layer is formed using a resin adhesive, and a protective layer is formed on the reflective layer. The bonding transparent substrate is made of the same material as the transparent substrate. Alternatively, a UV-curable resin having transparency may be applied on the reflective layer, and the UV-curable resin may be cured by irradiating UV rays to form a protective layer.

FIG. 1 is a partial sectional view showing an example of the optical disk obtained in this way. The transparent substrate 1 is made of a transparent plastic such as a polycarbonate resin and an acrylic resin. Although not shown, a pregroove having a predetermined groove depth and a predetermined groove width at a predetermined pitch is formed on the transparent substrate 1. On this transparent substrate 1, a first dielectric layer 2 composed of zinc sulfide-metal oxide, a phase change recording layer 3 composed of chalcogenide, and a zinc sulfide-metal oxide A bonded substrate 8 made of the same material as the transparent substrate 1 via a second dielectric layer 4, a silicon carbide film 5, a reflective layer 6 made of silver or a silver alloy, and a resin adhesive layer 7 Are sequentially formed.

As described above, a sputtering target containing inexpensive α-type silicon carbide as a main component and containing an excess carbon content of 20 mol% or less is prepared. A DC sputtering method with a high film formation rate is applied to this sputtering target with a low-cost apparatus configuration under the flow of a sputtering gas containing oxygen. Therefore, a silicon carbide film having physical, optical, thermal and mechanical properties suitable for an optical disk is quickly and inexpensively formed on the second dielectric layer composed of zinc sulfide-metal oxide. be able to.
Since the silicon carbide film formed in this manner does not have excess carbon atoms and free silicon atoms, it has high transparency, suppresses deterioration of the reflective layer by sulfuration, and improves the optical recording characteristics of the phase change recording layer. Can be maintained. Therefore, it is possible to obtain an inexpensive and highly durable optical disk.

Hereinafter, concrete examples of the present embodiment,
The sputtering target, the silicon carbide film, the method for manufacturing the optical disk and the optical disk, and the results of evaluating the silicon carbide film and the optical disk according to the embodiment of the present invention will be described in more detail using comparative examples.

Example 1 In order to prepare a sputtering target, first, β-SiC powder having an average particle size of 2 μm and carbon powder having an average particle size of 1 μm were mixed in a molar ratio of S
It is blended so that iC: C = 99: 1. The formulation was mixed for 10 hours in an argon (Ar) atmosphere using a ball mill.

Then, a pressure of 100 kg / cm ² was applied to the mixed powder by using a vacuum hot press device,
The mixture was treated at 1500 ° C. for 2 hours and reaction-sintered. The surface of the obtained sintered body was cut by 0.6 mm by mechanical polishing,
A sputtering target having a diameter of 200 mm and a thickness of 5 mm was obtained.

Using this sputtering target,
Silicon (Si) wafer and polycarbonate (Poly
A silicon carbide film was formed on a substrate of a carbonate resin sheet using a direct current (DC) magnetron sputtering apparatus. The sputtering conditions are DC output 2k
W, the atmosphere pressure was 0.4 Pa, the flow rate was adjusted so that the inert gas was the main component, and oxygen was contained at a volume ratio of 5%, and the mixture was circulated in a chamber (Chamber). The discharge between the electrodes during film formation was stable.

Next, on a Si wafer substrate and polycarbonate
Peeling off each silicon carbide film formed on the substrate
And an ellipsometer (Ellipsometer)
Used and evaluated. At a wavelength of 633 nm, the refractive index
2.1, optical absorption coefficient 1 × 10 ^-5showed that. Light absorption
It is small and has optical characteristics necessary for use on optical discs.
I was prepared. Also formed on polycarbonate substrate
Silicon carbide coating was transferred to a transmission electron microscope (TEM, Transp
arent Electron Microscopoy)
The coating was in an amorphous state.

Example 2 α-Si having an average particle size of 2 μm
A mixed powder of C and β-SiC (containing 50 mol% of β-SiC) and a carbon powder having an average particle size of 1 μm are represented by a molar ratio.
It is blended so that SiC: C = 99: 1. The formulation was mixed for 10 hours in an argon (Ar) atmosphere using a ball mill.

Next, a sputtering target was obtained in the same manner as in Example 1. Further, using the obtained sputtering target, a silicon carbide film was formed on each of the Si wafer substrate and the polycarbonate substrate by applying the same apparatus and the same processing conditions as those in Example 1. The discharge between the electrodes during film formation was stable.

Next, the respective silicon carbide films formed on the Si wafer substrate and the polycarbonate substrate were peeled off, and evaluated using an ellipsometer. Wavelength 633n
At m, the refractive index was 2.1 and the optical absorption coefficient was 1E-5. It has low light absorption and has the optical characteristics necessary for use in optical discs. In addition, as a result of observing the silicon carbide film formed on the polycarbonate substrate using a transmission electron microscope, the film was in an amorphous state.

Example 3 α-Si having an average particle size of 2 μm
A mixed powder of C and β-SiC (containing 50 mol% of β-SiC) and a carbon powder having an average particle size of 1 μm are represented by a molar ratio.
It is blended so that SiC: C = 99: 1. The formulation was mixed for 10 hours in an argon (Ar) atmosphere using a ball mill.

Next, a sputtering target was obtained in the same manner as in Example 1. Furthermore, using the obtained sputtering target, except that only an inert gas was passed, the same apparatus and the same processing conditions as those in Example 1 were applied to the surface of the Si wafer and the surface of the polycarbonate substrate. Then, a silicon carbide film was formed. The discharge between the electrodes during film formation was stable.

Next, the respective silicon carbide films formed on the Si wafer substrate and the polycarbonate substrate were peeled off, and evaluated using an ellipsometer. Wavelength 633n
At m, the refractive index is 2.6 and the optical absorption coefficient is 6 × 10 ^−2.
showed that. It was found that the light absorption was large as compared with the silicon carbide coatings obtained in Example 1 and Example 2. Also,
Silicon carbide coating formed on polycarbonate substrate,
As a result of observation using a transmission electron microscope, the coating was in an amorphous state.

Example 4 α-Si having an average particle size of 2 μm
A mixed powder of C and β-SiC (containing 80 mol% of β-SiC) and a carbon powder having an average particle diameter of 1 μm are represented by a molar ratio of:
It is blended so that SiC: C = 95: 5. The formulation was mixed for 10 hours in an argon (Ar) atmosphere using a ball mill.

Next, a sputtering target was obtained in the same manner as in Example 1. Further, using the obtained sputtering target, a silicon carbide film was formed on each of the Si wafer substrate and the polycarbonate substrate by applying the same apparatus and the same processing conditions as those in Example 1. The discharge between the electrodes during film formation was stable.

Next, the respective silicon carbide films formed on the Si wafer substrate and the polycarbonate substrate were peeled off and evaluated using an ellipsometer. Wavelength 633n
At m, the refractive index is 2.1 and the optical absorption coefficient is 1 × 10 ^−5.
showed that. It has low light absorption and has the optical characteristics necessary for use in optical discs. In addition, as a result of observing the silicon carbide film formed on the polycarbonate substrate using a transmission electron microscope, the film was in an amorphous state.

Example 5 A first dielectric layer, 80 nm thick, was formed on a polycarbonate substrate having a diameter of 120 mm.
ZnS—SiO ₂ layer and a phase change recording layer having a thickness of 2
0 nm Ag-In-Sb-Te alloy layer (Ag 4 at%, In 6 at%, Sb 60 at%, Te 30 at%)
Then, a 12-nm-thick SiC film as a second dielectric layer and a 120-nm-thick pure Ag layer as a reflective layer were sequentially formed.

Using a sputtering target having a diameter of 200 mm, sputtering was performed by a single-wafer sputtering apparatus to form respective films. ZnS-
Only when forming SiO ₂ , a high-frequency sputtering method applying a high-frequency voltage was applied, and for other films, a DC sputtering method applying a DC voltage was applied.

The sputtering conditions for forming the ZnS—SiO ₂ film are as follows: high-frequency output: 3 kW, atmosphere pressure: 0.5
Pa, and only argon gas was allowed to flow through the chamber. The Ag-In-Sb-Te layer has a DC output of 0.3 k.
The film was formed under the conditions of W and an atmospheric pressure of 0.3 Pa. The pure Ag layer was formed under the conditions of a DC output of 4 kW and an atmospheric pressure of 0.6 Pa. The SiC film was formed using the sputtering target obtained in Example 2 under the same conditions as in Example 2.
A film was formed.

A resin adhesive is applied to the reflective layer of the polycarbonate substrate on which the above-described layer is formed, and is bonded to a polycarbonate sheet serving as a protective layer to have a diameter of 120 m.
An optical disk having a size of 0.6 mm and a thickness conforming to the DVD-RW standard was obtained. This disk was laser-annealed to crystallize the phase-change recording layer.
The evaluation was performed using a pickup having an objective lens having a numerical aperture NA (Numerical Aperture). The linear velocity for recording and playback is
The recording density was 3.5 m / sec, the recording density was 0.267 μm / bit, and the signal was recorded in a random pattern using EFM +, which is a standard modulation method for DVD.

A rewriting operation was performed with a laser output of 15 mW at the time of recording and a laser output of 7.5 mW at the time of erasing, and the number of times of rewriting was repeatedly examined. Even after recording and reproducing 10,000 times, the jitter value of the data and the clock was 10% or less, which was in an error-free range.
The reflectance of the signal recorded on the optical disk was 18% or more, satisfying the standard value of the reflectance of a read-only DVD.

[0071] (Example 6) using the same conditions as the same apparatus used in Example 5, on a polycarbonate substrate having a diameter of 120 mm, a ZnS-SiO ₂ layer having a thickness of 80 nm, a thickness of 20 nm Ag -In-Sb-Te layer (Ag4
Atomic%, In 6 atomic%, Sb 60 atomic%, Te 30 atomic%), a ZnS—SiO ₂ layer having a thickness of 10 nm, and a thickness of 5 nm.
An SiC film having a thickness of 120 nm and a pure Ag layer having a thickness of 120 nm were sequentially formed. Here, the second dielectric layer is made of ZnS-S
It is composed of an iO ₂ layer and a SiC coating.

A resin adhesive is applied to the reflective layer of the polycarbonate substrate on which the above-described layer is formed, and the resin layer is bonded to a polycarbonate sheet as a protective layer to have a diameter of 120 m.
An optical disk having a size of 0.6 mm and a thickness conforming to the DVD-RW standard was obtained. This disk was laser-annealed to crystallize the phase-change recording layer, and evaluated with the pickup used in Example 5. The linear velocity for recording and playback is
The recording density was 3.5 m / sec, the recording density was 0.267 μm / bit, and the signal was a random pattern recorded using EFM +.

A rewriting operation was performed with a laser output of 12 mW during recording and a laser output of 6.4 mW during erasing, and the number of times of rewriting was repeatedly examined. Even after recording and reproducing 10,000 times, the jitter value of data and clock was 8% or less, which was in an error-free range. This optical disk is heated at 80 ° C. and 85 RH (relative humidity, relative humidity).
The sample was treated in the atmosphere of y) for 500 hours, and evaluated again after the high temperature and high humidity test. With respect to the signal recorded before the high-temperature and high-humidity test, the dropout accompanied by the burst caused by the deterioration of Ag of the reflective layer did not occur, and the signal could be reproduced without error. The reflectance of the signal recorded on the optical disk was 20% or more, which satisfied the standard value of the reflectance of a read-only DVD.

[0074] (Example 7) using the same apparatus used in Example 6, on a polycarbonate substrate having a diameter of 120 mm, a ZnS-SiO ₂ layer having a thickness of 80 nm, a thickness of 20n
m Ag-In-Sb-Te layer (Ag 4 at%, In 6
Atomic%, Sb 60 atomic%, Te 30 atomic%) and thickness 1
0 nm ZnS—Nb ₂ O ₅ layer and 5 nm thick SiC
A film and a pure Ag layer having a thickness of 120 nm were sequentially formed.
Here, compared with Example 6, in place of ZnS-SiO ₂ layer, using a _ZnS-Nb 2 _{O 5} layer, the second dielectric layer, _ZnS-Nb 2 _{O 5} layer and the SiC film Consists of

The ZnS—Nb ₂ O ₅ layer has a DC output of 2 k
A film was formed under the conditions of W and an atmospheric pressure of 0.5 Pa. The sputtering conditions for the other layers are the same as in Example 6.

A resin adhesive is applied to the reflective layer of the polycarbonate substrate on which the above-described layer is formed, and the resin layer is bonded to a polycarbonate sheet as a protective layer to have a diameter of 120 m.
An optical disk having a size of 0.6 mm and a thickness conforming to the DVD-RW standard was obtained. This disk was laser-annealed to crystallize the phase-change recording layer, and evaluated with the pickup used in Example 5. The linear velocity for recording and playback is
The recording density was 3.5 m / sec, the recording density was 0.267 μm / bit, and the signal was a random pattern recorded using EFM +.

A rewriting operation was performed with a laser output of 14 mW at the time of recording and a laser output of 7.7 mW at the time of erasing, and the number of times of rewriting was repeatedly examined. Even after recording and reproducing 20,000 times, the jitter value of data and clock was 8% or less, which was in an error-free range. The reflectance of the signal recorded on the optical disk was 20% or more, which satisfied the standard value of the reflectance of a read-only DVD. This optical disk was evaluated again after a high-temperature and high-humidity test in which the optical disk was treated in an atmosphere of 80 ° C. and 85 RH for 500 hours. With respect to the signal recorded before the high-temperature and high-humidity test, the dropout accompanied by the burst caused by the deterioration of Ag of the reflective layer did not occur, and the signal could be reproduced without error.

Example 8 Using the same apparatus used in Example 7, a ZnS—SiO ₂ layer having a thickness of 80 nm and a thickness of 20 n were formed on a polycarbonate substrate having a diameter of 120 mm.
m Ag-In-Sb-Te layer (Ag 4 at%, In 6
Atomic%, Sb 60 atomic%, Te 30 atomic%) and thickness 1
0 nm ZnS—Nb ₂ O ₅ layer and 5 nm thick SiC
The coating and a 120 nm thick Ag-Ru-Cu layer (Ag9
8.1% by weight, Ru 0.9% by weight and Cu 1% by weight). Here, compared to Example 7, a silver alloy Ag-Ru-Cu layer was used for the reflective layer instead of the pure Ag layer.

The Ag—Ru—Cu layer has a DC output of 4 kW,
The film was formed under the condition of an atmospheric pressure of 0.6 Pa. The sputtering conditions for the other layers are the same as in Example 7.

A resin adhesive is applied to the reflective layer of the polycarbonate substrate on which the above-described layer is formed, and the resin layer is bonded to a polycarbonate sheet as a protective layer to have a diameter of 120 m.
An optical disk having a size of 0.6 mm and a thickness conforming to the DVD-RW standard was obtained. This disk was laser-annealed to crystallize the phase-change recording layer, and evaluated with the pickup used in Example 5. The linear velocity for recording and playback is
The recording density was 3.5 m / sec, the recording density was 0.267 μm / bit, and the signal was a random pattern recorded using EFM +.

A rewriting operation was performed with a laser output of 14 mW at the time of recording and a laser output of 7.7 mW at the time of erasing, and the number of times of rewriting was repeatedly examined. Even after recording and reproducing 20,000 times, the jitter value of data and clock was 8% or less, which was in an error-free range. The reflectance of the signal recorded on the optical disk was 20% or more, which satisfied the standard value of the reflectance of a read-only DVD. This optical disk was evaluated again after a high-temperature and high-humidity test in which the optical disk was treated in an atmosphere of 80 ° C. and 85 RH for 500 hours. With respect to the signal recorded before the high-temperature and high-humidity test, the dropout accompanied by the burst caused by the deterioration of Ag of the reflective layer did not occur, and the signal could be reproduced without error.

Comparative Example 1 In order to obtain a raw material powder for a sputtering target, α-SiC having an average particle size of 2 μm was used.
The powder was mixed for 10 hours in an argon (Ar) atmosphere. Then, a pressure of 100 kg / cm ² was applied to the raw material powder using a vacuum hot press device to 1500
C. for 2 hours, followed by reaction sintering. The surface of the obtained sintered body was cut by 0.6 mm by mechanical polishing to have a diameter of 20 mm.
A sputtering target having a thickness of 0 mm and a thickness of 5 mm was obtained.

Using this sputtering target,
Silicon (Si) wafer and polycarbonate (Poly
A silicon carbide film was formed on a substrate of a carbonate resin sheet using a direct current (DC) magnetron sputtering apparatus, but the discharge between the electrodes during the film formation was unstable and a uniform film was formed. Could not film. In addition, the discharge time was short, and it was not possible to form a practically sufficient film thickness.

(Comparative Example 2) Average particle size is 2 μm β-SiC
And a carbon powder having an average particle diameter of 1 μm were blended in a molar ratio of SiC: C = 99: 1. Using a ball mill, this formulation is converted to argon (Ar)
The mixture was mixed for 10 hours in an atmosphere.

Next, a sputtering target was obtained in the same manner as in Comparative Example 1. Further, using the obtained sputtering target, a silicon carbide film was formed on the Si wafer substrate and the polycarbonate substrate using a DC magnetron sputtering apparatus. Sputtering conditions: DC output 2 kW, atmosphere pressure 0.4 Pa
And an argon (Ar) gas in a chamber (Chamber)
It was distributed inside. The discharge between the electrodes during film formation was stable.

Next, the respective silicon carbide films formed on the Si wafer substrate and the polycarbonate substrate were peeled off and evaluated using an ellipsometer. Wavelength 633n
At m, the refractive index is 2.6 and the optical absorption coefficient is 5 × 10 ^−2.
showed that. Light absorption was large, and was insufficient for use in optical discs. In addition, as a result of observing the silicon carbide film formed on the polycarbonate substrate using a transmission electron microscope, the film was in an amorphous state.

Comparative Example 3 A first dielectric layer having a thickness of 80 nm was formed on a polycarbonate substrate having a diameter of 120 mm.
ZnS—SiO ₂ layer and a phase change recording layer having a thickness of 2
0 nm Ag-In-Sb-Te alloy layer (Ag 4 at%, In 6 at%, Sb 60 at%, Te 30 at%)
Then, a 12-nm-thick SiC film as a second dielectric layer and a 120-nm-thick pure Ag layer as a reflective layer were sequentially formed.

Using a sputtering target having a diameter of 200 mm, sputtering was performed by a single-wafer sputtering apparatus to form respective films. ZnS-
Only when forming SiO ₂ , a high-frequency sputtering method applying a high-frequency voltage was applied, and for other films, a DC sputtering method applying a DC voltage was applied.

The sputtering conditions for forming the ZnS—SiO ₂ film were as follows: high-frequency output: 3 kW, atmospheric pressure: 0.5
Pa, and only argon gas was allowed to flow through the chamber. The Ag-In-Sb-Te layer has a DC output of 0.3 k.
The film was formed under the conditions of W and an atmospheric pressure of 0.3 Pa. The pure Ag layer was formed under the conditions of a DC output of 4 kW and an atmospheric pressure of 0.6 Pa. The SiC film was formed using the sputtering target obtained in Comparative Example 2 under the same conditions as in Comparative Example 2.
A film was formed.

A resin adhesive is applied to the reflective layer of the polycarbonate substrate on which the above-described layer is formed, and is adhered to a polycarbonate sheet as a protective layer to have a diameter of 120 m.
An optical disk having a size of 0.6 mm and a thickness conforming to the DVD-RW standard was obtained. This disk was laser-annealed to crystallize the phase-change recording layer, and evaluated with the pickup used in Example 5. The linear velocity for recording and playback is
The recording density was 3.5 m / sec, the recording density was 0.267 μm / bit, and the signal was recorded in a random pattern using EFM +, which is a standard modulation method for DVD.

A rewriting operation was performed with a laser output of 15 mW at the time of recording and a laser output of 7.5 mW at the time of erasing, and the number of times of rewriting was repeatedly examined. The reflectivity of a signal recorded on an optical disk is about 14%, and a read-only DVD
Did not satisfy the standard value of reflectance. This is Si
This is because the light absorption of the C film was large and the reflectance of the optical disk was lowered.

Comparative Example 4 A first dielectric layer having a thickness of 80 nm was formed on a polycarbonate substrate having a diameter of 120 mm.
ZnS—SiO ₂ layer and a phase change recording layer having a thickness of 2
0 nm Ag-In-Sb-Te alloy layer (Ag 4 at%, In 6 at%, Sb 60 at%, Te 30 at%)
Then, a 12-nm-thick SiC film as a second dielectric layer and a 120-nm-thick pure Ag layer as a reflective layer were sequentially formed.

Using the same apparatus and the same conditions as in Comparative Example 3, each film was formed using a sputtering target having a diameter of 200 mm.

A resin adhesive is applied to the reflective layer of the polycarbonate substrate on which the above-described layer is formed, and is bonded to a polycarbonate sheet serving as a protective layer, and has a diameter of 120 m.
An optical disk having a size of 0.6 mm and a thickness conforming to the DVD-RW standard was obtained. This disk was laser-annealed to crystallize the phase-change recording layer, and evaluated with the pickup used in Example 1. The linear velocity for recording and playback is
The recording density was 3.5 m / sec, the recording density was 0.267 μm / bit, and the signal was recorded in a random pattern using EFM +, which is a standard modulation method for DVD.

A rewriting operation was performed with a laser output of 15 mW at the time of recording and a laser output of 7.5 mW at the time of erasing, and the number of times of rewriting was repeatedly examined. Even after recording and reproducing 10,000 times, the jitter value of data and clock is 10%.
That is all, it was not error free. The reflectance of the signal recorded on the optical disk was 18% or less, and did not satisfy the standard value of the reflectance of a read-only DVD.

The present invention is not limited to the above-described embodiments and examples, and its application and modification are arbitrary. For example, a sputtering target and a silicon carbide film have optical properties and the like suitable for optical disc applications, but have excellent mechanical properties with high rigidity, physical properties with a dense structure that suppresses mass transfer, and high thermal conductivity. It can be used for various uses other than the optical disc use by utilizing the thermal characteristics having high heat resistance and the chemical stability having high chemical resistance. For example, the protective film of the thermal head of the printer,
It can be used for various device members, sensor members, optical thin film members, etc., such as a protective film of a magnetic head.

The apparatus (ball mill) for mixing the raw material powder of the sputtering target, the apparatus for subjecting the mixed powder to reaction sintering and processing into a predetermined shape (vacuum hot press apparatus), and the apparatus described in the above embodiment and examples, The pickup for evaluating the optical disk and the evaluation method are not limited to the above-described embodiments and the like, and are optional. For example, as a device for mixing raw material powders, a dry mixing device such as a Henschel mixer or a jet mill can be applied in addition to a ball mill.

[0098]

According to the present invention, it is possible to provide a sputtering target, a silicon carbide film, and an optical disk and a method for manufacturing an optical disk using these, which can manufacture an optical disk which is inexpensive and has excellent durability. it can.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating an example of an optical disc according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transparent substrate 2 first dielectric layer 3 phase change recording layer 4 second dielectric layer 5 silicon carbide coating 6 reflective layer 7 resin adhesive layer 8 bonded substrate

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G11B 7/24 534 G11B 7/24 538E 7/26 531 535 535 B41M 5/26 X 538 C04B 35/56 101U 7/26 531 101Y (72) Inventor Masato Hariya 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Kazunori Ito 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hiroko Tashiro 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hajime 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 2H111 EA23 FA01 FA12 FA21 FA23 GA03 4G001 BA22 BA60 BB22 BB60 BC13 BC42 BC47 BD22 BE02 BE03 4K029 AA06 AA11 BA56 BB02 BD00 CA05 DC05 DC09 5D029 JA01 LA14 LA17 LB01 LB07 MA13 5D121 AA04 EE03 EE09 EE14

Claims (17)

[Claims] 1. A method according to claim 1, which comprises at least 50 mol% of silicon carbide having a cubic zinc-blende type structure (β type) and a specific resistance at room temperature of 10 ⁻¹ Ωcm.
A sputtering target comprising the following silicon carbide. 2. The silicon carbide according to claim 1, wherein said silicon carbide has a rhombohedral wurtzite type structure (α type) and a cubic zinc blende type structure (β type). 2. The sputtering target according to 1. 3. The sputtering target according to claim 1, wherein the silicon carbide is formed by reacting and sintering powdery silicon carbide. 4. The silicon carbide according to claim 1, wherein the atomic ratio of carbon to silicon is greater than 1/1, which is the stoichiometric composition, and contains an excess of carbon atoms within 20 mol%. The sputtering target according to claim 1. 5. The silicon carbide is a molded product obtained by mixing powdered silicon carbide having a stoichiometric composition with powdered carbon and subjecting the mixture to reaction sintering. The sputtering target according to claim 4, characterized in that: 6. A layer containing at least 50 mol% of silicon carbide having a cubic zincblende structure (β type) and having a specific resistance at room temperature of 10 ⁻¹ Ωcm.
A silicon carbide film formed by applying a direct current sputtering method to the following sputtering target and being a film in an amorphous state. 7. A composition containing at least 50 mol% of silicon carbide having a cubic zincblende type structure (β type), wherein the atomic ratio of carbon to silicon is larger than 1/1, which is the stoichiometric composition, and is 20 mol% or more. % Of a silicon carbide containing an excessive amount of carbon in an amount of not more than an amorphous state, which is formed by applying a direct current sputtering method to a sputtering target composed of silicon carbide containing an excessive amount of carbon. Characteristic silicon carbide film. 8. The silicon carbide film according to claim 7, wherein the excess carbon is removed as a gaseous oxide using the sputtering target in an oxygen-containing atmosphere. 9. An optical disc comprising a first dielectric layer, a phase-change recording layer, a second dielectric layer, and a reflective layer sequentially formed on a transparent substrate, wherein: A non- sputtering target formed by applying a direct-current sputtering method to a sputtering target containing silicon carbide having a type structure (β type) of 50 mol% or more and having a specific resistance at room temperature of 10 ^-1 Ωcm or less. An optical disc, characterized in that a crystalline silicon carbide film forms at least a part of the second dielectric layer and is arranged adjacent to the reflective layer. 10. An optical disk comprising a first dielectric layer, a phase-change recording layer, a second dielectric layer, and a reflective layer sequentially formed on a transparent substrate, comprising: a cubic zinc-blende; Containing at least 50 mol% of silicon carbide having a type structure (β type) and having an atomic ratio of carbon to silicon of more than 1/1, which is the stoichiometric composition, and containing excess carbon within 20 mol%. An amorphous silicon carbide coating substantially free of carbon atoms, which is formed by applying a direct current sputtering method to a sputtering target composed of silicon, is formed on at least one of the second dielectric layers. An optical disc, comprising: an optical disc, and disposed so as to be adjacent to the reflective layer. 11. The optical disk according to claim 10, wherein the sputtering target is processed in an oxygen-containing atmosphere, and the excess carbon is removed as a gaseous oxide. 12. The method according to claim 9, wherein the second dielectric layer is made of zinc sulfide-metal oxide, and the reflective layer is made of silver or a silver alloy. An optical disk according to claim 1. 13. The method according to claim 9, wherein the phase change recording layer is made of a chalcogenide containing at least one of Te, Se, and S. optical disk. 14. The chalcogenide is In-Sb-T.
The optical disc according to claim 13, wherein the optical disc is an e-based alloy. 15. A method of manufacturing an optical disk, comprising the steps of sequentially forming a first dielectric layer, a phase change recording layer, a second dielectric layer, and a reflective layer on a transparent substrate. Forming the second dielectric layer, the method comprising forming at least a part of the second dielectric layer and forming a silicon carbide film adjacent to the reflective layer; Contains 50 mol% or more of silicon carbide having a cubic zinc-blende structure (β type) and has a specific resistance of 10 at room temperature.
^A method for manufacturing an optical disk, characterized in that the film is an amorphous film formed by applying a DC sputtering method to a sputtering target composed of silicon carbide of ^-1 Ωcm or less. 16. A method for manufacturing an optical disk, comprising the steps of sequentially forming a first dielectric layer, a phase change recording layer, a second dielectric layer, and a reflective layer on a transparent substrate. Forming the second dielectric layer, the method comprising forming at least a part of the second dielectric layer and forming a silicon carbide film adjacent to the reflective layer; Contains at least 50 mol% of silicon carbide having a cubic zinc-blende type structure (β type), and the atomic ratio of carbon to silicon is greater than 1/1, which is the stoichiometric composition, within 20 mol%. A sputtering target composed of silicon carbide containing excess carbon, formed by applying a direct current sputtering method, and is a film in an amorphous state that does not substantially contain free carbon atoms. An optical disc manufacturing method. 17. The method according to claim 16, wherein the excess carbon is removed as a gaseous oxide using the sputtering target in an oxygen-containing atmosphere.