JP2005158110A - Optical recording disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording disk wherein data constituted of recording mark columns containing recording marks and blank regions between the recording marks adjacent to each other is recorded and reproduced even when the length of the recording mark and the length of the blank region are shorter than that of the resolution limit, recording capacity is increased and reproducing durability is enhanced. <P>SOLUTION: The optical recording disk comprises a laminated body wherein a decomposition reaction layer 8 containing a noble metal oxide as a main component, a dielectric layer 7 consisting essentially of a dielectric material containing sulfur, an intermediate layer 6 consisting essentially of a dielectric material containing an element other than sulfur as a main component or containing sulfur whose content is lower than the content of sulfur contained in the dielectric layer 7, and a light absorption layer 5 are successively laminated. The disk is so constituted that data are recorded and reproduced by irradiation with a laser beam L. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical recording disk, and more specifically, even when the length of a recording mark or the length of a blank area between adjacent recording marks is less than the resolution limit. Further, the present invention relates to an optical recording disk that can record and reproduce data composed of a recording mark string including a blank area, can greatly increase recording capacity, and can improve reproduction durability. Is.

  Conventionally, optical recording disks represented by CDs and DVDs have been widely used as recording media for recording digital data. In recent years, optical disks having a larger capacity and a higher data transfer rate have been used. Recording discs are being actively developed.

  In such an optical recording disk, the wavelength λ of the laser beam used for data recording / reproduction is reduced, the numerical aperture NA of the objective lens is increased, and the beam spot diameter of the laser beam is reduced, thereby reducing the optical recording disk. The recording capacity is increased.

  In an optical recording disk, the length of a recording mark recorded on the optical recording disk and the length between adjacent recording marks, that is, an area where no recording mark is formed (hereinafter referred to as “blank area”). If the length becomes less than the resolution limit, it becomes impossible to reproduce data from the optical recording disk.

  The resolution limit is determined by the wavelength λ of the laser beam and the numerical aperture NA of the objective lens for focusing the laser beam. The repetitive frequency between the recording mark and the blank area, that is, the spatial frequency is 2 NA / λ or more. In this case, it becomes impossible to read the data recorded in the recording mark and the blank area.

  Therefore, the lengths of the recording marks and blanks corresponding to the readable spatial frequency are each λ / 4NA or more, and the laser beam having the wavelength λ is focused on the surface of the optical recording disk by the objective lens having the numerical aperture NA. In this case, the recording mark and blank area having a length of λ / 4NA become the shortest recording mark and blank area that can be read.

  As described above, when data is reproduced, there is a resolution limit at which data can be reproduced, and there is a limit to the length of a record mark and the length of a blank area that can be reproduced. Therefore, even if recording marks and blank areas having a length less than the resolution limit are formed and data is recorded, the recorded data cannot be reproduced, so when recording data on an optical recording disk Since the length of the record mark that can be formed and the length of the blank area are inevitably limited, the record mark and the blank area are usually formed so as to be less than the resolution limit, and the optical recording disk There is no data recording.

  Therefore, in order to increase the recording capacity of the optical recording disk, the resolution limit is reduced by shortening the wavelength λ of the laser beam used for data reproduction or by increasing the numerical aperture NA of the objective lens, It is required to be able to reproduce data consisting of shorter recording marks and blank areas.

  However, there is a limit to shortening the wavelength λ of the laser beam used for data reproduction or increasing the numerical aperture NA of the objective lens. Therefore, by reducing the resolution limit, recording on an optical recording disk is possible. There was a limit to increasing the capacity.

  Also, even if the recording capacity of the optical recording disk can be increased by some method, it is not enough, and the recorded data deteriorates when the data recorded on the optical recording disk is repeatedly reproduced. However, it is necessary to have sufficient reproduction durability so that the signal characteristics of the reproduction signal do not deteriorate.

  Therefore, an object of the present invention is to provide a recording mark string including these recording marks and blank areas even when the length of the recording marks and the length of the blank area between adjacent recording marks are less than the resolution limit. An object of the present invention is to provide an optical recording disk capable of recording and reproducing structured data, greatly increasing the recording capacity, and improving the reproduction durability.

  An object of the present invention is an optical recording disk configured to be irradiated with a laser beam to record and reproduce data, and includes a decomposition reaction layer containing a noble metal oxide as a main component and sulfur. A dielectric layer containing a dielectric material as a main component and a dielectric material containing an element other than sulfur as a main component, or a dielectric containing a small amount of sulfur compared to the sulfur content contained in the dielectric layer This is achieved by an optical recording disk comprising a laminate in which an intermediate layer mainly composed of a body material and a light absorption layer are sequentially laminated.

  In the present invention, the optical recording disk includes a decomposition reaction layer containing a noble metal oxide as a main component.

  According to the inventor's research, a laser beam is irradiated onto an optical recording disk having a decomposition reaction layer containing a precious metal oxide as a main component, a recording mark row is formed in the decomposition reaction layer, and data is recorded. In this case, it is found that the data can be reproduced even when the length of the recording mark constituting the recording mark row and the length of the blank area between the adjacent recording marks are less than the resolution limit. Has been.

  Therefore, according to the present invention, the recording capacity of the optical recording disk can be greatly increased.

  Further, in the present invention, between the light absorption layer and the dielectric layer, a dielectric material containing an element excluding sulfur as a main component, or a content smaller than the content of sulfur contained in the dielectric layer An intermediate layer mainly composed of a dielectric material containing an amount of sulfur is formed.

  According to the inventor's research, when such an intermediate layer is formed on an optical recording disk, a high-power reproduction laser beam is repeatedly irradiated to reproduce data multiple times. It has been found that it is possible to effectively suppress deterioration of signal characteristics of a reproduction signal when data recorded on an optical recording disk is reproduced.

  Light absorption of a dielectric material containing as a main component an element excluding sulfur, or an intermediate layer containing as a main component a dielectric material containing a small amount of sulfur compared to the content of sulfur contained in the dielectric layer The reason why it is possible to suppress the deterioration of the signal characteristics of the reproduction signal when reproducing the data recorded on the optical recording disk when it is formed between the layer and the dielectric layer is not necessarily clear. By forming the intermediate layer having such a structure between the light absorption layer and the dielectric layer, the dielectric layer can be used even when the light absorption layer is heated by irradiation with a high-power reproducing laser beam. The sulfur contained in the layer was not mixed with the elements contained in the light absorption layer, and as a result, the adverse effect of the change in the state of the light absorption layer on the optical characteristics of the optical recording disk could be eliminated. I guess it is not.

  Therefore, according to this embodiment, it is possible to improve the reproduction durability of the optical recording disk.

  In a preferred embodiment of the present invention, when the laser beam is irradiated, the noble metal oxide contained as a main component in the decomposition reaction layer is decomposed into noble metal and oxygen, and the generated oxygen gas A cavity is formed, and the noble metal fine particles are precipitated in the cavity, so that a recording mark is formed in the decomposition reaction layer.

  According to the inventor's research, when an optical recording disk having a decomposition reaction layer containing a noble metal oxide as a main component is irradiated with a laser beam, the noble metal oxide contained as a main component in the decomposition reaction layer is converted into a noble metal. The oxygen gas is decomposed into oxygen and the generated oxygen gas forms cavities in the decomposition reaction layer. Precious metal fine particles are deposited in the cavities, recording marks are formed in the decomposition reaction layer, and data is recorded. Thus, when data is recorded on the optical recording disk, the length of the recording marks constituting the recording mark row and the length of the blank area between adjacent recording marks are less than the resolution limit. It has been found that the data is reproducible.

  The noble metal oxide contained as the main component in the decomposition reaction layer is decomposed into noble metal and oxygen, and the generated oxygen gas forms cavities in the decomposition reaction layer, and noble metal fine particles precipitate in the cavities. When the recording mark is formed in the decomposition reaction layer and the data is recorded, the length of the recording mark constituting the recording mark row and the length of the blank area between the adjacent recording marks are less than the resolution limit. The reason why the data can be reproduced at any time is not necessarily clear, but the noble metal fine particles deposited in the cavity are irradiated with a laser beam for reproduction, generating near-field light and solving the problem. This may be because the image limit has disappeared, or because the resolution limit has decreased due to the interaction between the precious metal fine particles deposited in the cavity and the irradiated laser beam. It is.

  Therefore, according to the present invention, the recording capacity of the optical recording disk can be greatly increased.

  In the present invention, the noble metal oxide contained as a main component in the decomposition reaction layer of the optical recording disk is not particularly limited. From the viewpoint of easy formation of the oxide and efficiency of generating near-field light, An oxide containing one kind of noble metal selected from the group consisting of platinum and palladium is preferable, and platinum oxide PtOx is particularly preferable because of its high decomposition temperature.

  Platinum oxide PtOx has a higher decomposition temperature than other noble metal oxides. Therefore, when a recording mark is formed by irradiating a laser beam set at a recording power, the platinum beam is irradiated with the laser beam. Even if heat diffuses from the exposed region to the surrounding decomposition reaction layer, the decomposition reaction of the platinum oxide PtOx is prevented from occurring in the region other than the region irradiated with the laser beam. It becomes possible to form a recording mark by forming a cavity in a desired region.

  Even when data is reproduced by irradiation with a high-power reproducing laser beam, platinum oxide PtOx has a higher decomposition temperature than other noble metal oxides. There is no risk of being decomposed into oxygen. Therefore, even if data recorded on the optical recording disk is repeatedly reproduced, the shape of the recording mark does not change, a cavity is formed, and a recording mark is formed. Since no new cavity is formed in a region other than the above region, it becomes possible to improve the reproduction durability of the optical recording disk.

  In the present invention, in order to obtain a reproduction signal having good signal characteristics even when the length of a recording mark or the length of a blank area between adjacent recording marks is less than the resolution limit, platinum oxide is used. In the general formula PtOx, x is preferably 0.5 or more and 4.0 or less, and more preferably 1.0 or more and less than 3.

  In the present invention, when silver oxide AgOy is used as the noble metal oxide, y is preferably 0.5 or more and 1.5 or less, more preferably 0.5 or more and 1.0 or less. .

  In the present invention, preferably, the platinum fine particles formed by decomposition of the platinum oxide have a particle size smaller than the size of the cavity to be formed in the decomposition reaction layer, and the platinum oxide is decomposed. In general, when the platinum fine particles formed are sufficiently small compared to the size of the formed cavity, the shape of the cavity is adversely affected by the platinum fine particles deposited in the cavity, and the recording mark It becomes possible to effectively prevent an undesirable change in the shape.

  In the present invention, the light absorption layer is configured to absorb the laser beam and generate heat when irradiated with the laser beam through the light incident surface of the laser beam.

  When the light absorption layer is configured to absorb the laser beam and generate heat when irradiated with the laser beam, the decomposition reaction layer itself is difficult to generate heat when irradiated with the laser beam. However, the heat transferred from the light absorption layer can decompose the noble metal oxide contained as the main component in the decomposition reaction layer into the noble metal and oxygen, so that the decomposition reaction layer is easily deformed. In addition, even if the decomposition reaction layer is thinned or the decomposition reaction layer contains a noble metal oxide having a high laser beam transmission property, the optical recording disk can be irradiated with a laser beam to obtain a desired As described above, it is possible to decompose the noble metal oxide to form a recording mark.

  In the present invention, the light absorption layer preferably contains a material having high laser beam absorptivity and low thermal conductivity, and preferably contains at least one of Sb and Te.

In the present invention, as an alloy containing at least one of Sb and Te contained in the light absorption layer, (Sb _a Te _1-a ) _1-b M _b , or {(GeTe) _c (Sb ₂ Te ₃ ) _1- Those having a composition represented by _c } _{dX1 -d} are particularly preferred. Here, the element M represents an element excluding Sb and Te, and the element X represents an element excluding Sb, Te and Ge.

When the alloy containing at least one of Sb and Te contained in the light absorption layer has a composition represented by (Sb _a Te _1-a ) _1-b M _b , a and b are 0 ≦ a ≦ It is preferable that 1 and 0 ≦ b ≦ 0.25. When b exceeds 0.25, the light absorption coefficient is lower than the value required for the light absorption layer, and the thermal conductivity is lower than the value required for the light absorption layer. Absent.

  The element M is not particularly limited, but In, Ag, Au, Bi, Se, Al, Ge, P, H, Si, C, V, W, Ta, Zn, Mn, Ti, Sn, Pb It is preferable that at least one element selected from the group consisting of Pd, N, O and rare earth elements (Sc, Y and lanthanoid) is contained as a main component.

On the other hand, when the alloy containing at least one of Sb and Te contained in the light absorption layer has a composition represented by {(GeTe) _c (Sb ₂ Te ₃ ) _1-c } _d X _1-d , It is preferable that 1/3 ≦ c ≦ 2/3 and 0.9 ≦ d.

  The element X is not particularly limited, but In, Ag, Au, Bi, Se, Al, P, H, Si, C, V, W, Ta, Zn, Mn, Ti, Sn, Pb, Pd It is preferable that at least one element selected from the group consisting of N, O, and rare earth elements is contained as a main component.

  In the present invention, it is preferable that the dielectric layer, the intermediate layer, and the light absorption layer are deformed when the laser beam is irradiated and the decomposition reaction layer is decomposed into noble metal and oxygen to form a cavity.

  The region where the dielectric layer, the intermediate layer and the light absorption layer are deformed is different from the region where the dielectric layer, the intermediate layer and the light absorption layer are not deformed, so that a reproduced signal having better signal characteristics can be obtained. Can do.

  The object of the present invention is also an optical recording disk configured such that data is recorded and reproduced by irradiation with a laser beam, the decomposition reaction layer containing a noble metal oxide as a main component, and a second A dielectric layer, a light absorption layer, an intermediate layer, and a third dielectric layer are sequentially laminated, and the third dielectric layer includes a dielectric material containing sulfur as a main component. A dielectric material containing an element other than sulfur as a main component, or a dielectric material containing a small amount of sulfur compared to the content of sulfur contained in the third dielectric layer. This is achieved by an optical recording disc characterized in that it is contained as a main component.

  According to the present invention, even when the length of a recording mark or the length of a blank area between adjacent recording marks is less than the resolution limit, the recording mark row including these recording marks and the blank area is formed. In addition, it is possible to provide an optical recording disc that can record and reproduce data, greatly increase the recording capacity, and improve the reproduction durability.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view of an optical recording disk according to a preferred embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the track of the optical recording disk shown in FIG. It is a substantially expanded sectional view.

  As shown in FIG. 2, the optical recording disk 1 according to this embodiment includes a support substrate 2, and a reflective layer 3, a third dielectric layer 4, a light absorption layer 5, and The intermediate layer 6, the second dielectric layer 7, the decomposition reaction layer 8, the first dielectric layer 9, and the light transmission layer 10 are laminated in this order.

  In the present embodiment, as shown in FIG. 1, the optical recording disk 1 is irradiated with a laser beam L from the light transmission layer 10 side, data is recorded, and recorded data is reproduced. It is configured. The laser beam L is focused on the optical recording disk 1 by an objective lens having a wavelength λ of 390 nm to 420 nm and a numerical aperture NA of 0.7 to 0.9.

  The support substrate 2 functions as a support for ensuring the mechanical strength required for the optical recording disk 1.

  The material for forming the support substrate 2 is not particularly limited as long as it can function as a support for the optical recording disk 1. The support substrate 2 can be formed of glass, ceramics, resin, or the like, for example. Of these, a resin is preferably used from the viewpoint of ease of molding. Examples of such a resin include polycarbonate resin, olefin resin, acrylic resin, epoxy resin, polystyrene resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, and urethane resin. Among these, polycarbonate resin and olefin resin are particularly preferable from the viewpoint of processability and optical characteristics.

  The thickness of the support substrate 2 is not particularly limited, but from the viewpoint of compatibility with the current optical recording disk, the support substrate 2 is formed to have a thickness of 1.0 mm to 1.2 mm. More preferably, it is formed to have a thickness of about 1.1 mm.

  As shown in FIG. 2, the reflective layer 3 is formed on the surface of the support substrate 2.

  The reflection layer 3 plays a role of reflecting the incident laser beam L via the light transmission layer 10 and emitting it from the light transmission layer 10 again.

  The material for forming the reflective layer 3 is not particularly limited as long as it can reflect the laser beam L. The reflective layer 3 can be made of Au, Ag, Cu, Pt, Al, Ti, Cr, Fe, It can be formed using at least one element selected from the group consisting of Co, Ni, Mg, Zn, Ge, and Si.

  The thickness of the reflective layer 3 is not particularly limited, but the reflective layer 3 is preferably formed to have a thickness of 5 nm to 200 nm.

  As shown in FIG. 2, a third dielectric layer 4 is formed on the surface of the reflective layer 3 of the optical recording disk 1.

  In the present embodiment, the third dielectric layer 4 has a function of protecting the support substrate 2 and the reflective layer 3 and physically and chemically protecting the light absorption layer 5 formed thereon. doing.

The dielectric material for forming the third dielectric layer 4 is not particularly limited. For example, the dielectric material is mainly composed of oxide, nitride, sulfide, fluoride, or a combination thereof. Depending on the body material, the third dielectric layer 4 can be formed, and the third dielectric layer 4 is preferably Si, Zn, Al, Ta, Ti, Co, Zr, Pb, Ag, Sn, It is formed of an oxide, nitride, sulfide, fluoride, or a composite thereof containing at least one metal selected from the group consisting of Ca, Ce, V, Cu, Fe, and Mg. As a dielectric material for forming the third dielectric layer 4, a mixture of ZnS and SiO ₂ is particularly preferable, and a molar ratio of ZnS and SiO ₂ is more preferably 80:20.

  The third dielectric layer 4 can be formed on the surface of the reflective layer 3 by, for example, a vapor phase growth method using a chemical species containing a constituent element of the third dielectric layer 4. Examples of the vapor deposition method include a vacuum deposition method and a sputtering method.

  The thickness of the third dielectric layer 4 is not particularly limited, but is preferably 10 nm to 140 nm.

  As shown in FIG. 2, a light absorption layer 5 is formed on the surface of the third dielectric layer 4 of the optical recording disk 1.

  In the present embodiment, the light absorption layer 5 absorbs the laser beam L when the optical recording disk 1 is irradiated with the laser beam L set to the recording power, generates heat, and generates generated heat, which will be described later. It has a function of transmitting to the decomposition reaction layer 8.

  In this embodiment, the light absorption layer 5 is formed of an alloy containing at least one of Sb and Te having a high light absorption coefficient and low thermal conductivity.

Examples of the alloy containing at least one of Sb and Te contained in the light absorption layer 5 include (Sb _a Te _1-a ) _1-b M _b , or {(GeTe) _c (Sb ₂ Te ₃ ) _1-c } _d It is particularly preferable to have a composition represented by X _1-d . Here, the element M represents an element excluding Sb and Te, and the element X represents an element excluding Sb, Te and Ge.

When the alloy containing at least one of Sb and Te contained in the light absorption layer 5 has a composition represented by (Sb _a Te _1-a ) _1-b M _b , a and b are 0 It is preferable that ≦ a ≦ 1 and 0 ≦ b ≦ 0.25. When b exceeds 0.25, the light absorption coefficient is lower than the value required for the light absorption layer 5, and the thermal conductivity is lower than the value required for the light absorption layer 5. It is not preferable.

  The element M is not particularly limited, but In, Ag, Au, Bi, Se, Al, Ge, P, H, Si, C, V, W, Ta, Zn, Mn, Ti, Sn, Pb It is preferable that at least one element selected from the group consisting of Pd, N, O and rare earth elements (Sc, Y and lanthanoid) is contained as a main component.

On the other hand, when the alloy containing at least one of Sb and Te contained in the light absorption layer 5 has a composition represented by {(GeTe) _c (Sb ₂ Te ₃ ) _1-c } _d X _1-d Is preferably 1/3 ≦ c ≦ 2/3 and 0.9 ≦ d.

  The element X is not particularly limited, but In, Ag, Au, Bi, Se, Al, P, H, Si, C, V, W, Ta, Zn, Mn, Ti, Sn, Pb, Pd It is preferable that at least one element selected from the group consisting of N, O, and rare earth elements is contained as a main component.

  In the case of using a laser beam L having a wavelength λ of 390 nm to 420 nm, it is particularly preferable that the element M contains at least one element selected from the group consisting of Ag, In, Ge and rare earth elements as a main component. It is particularly preferable that the element X contains at least one element selected from the group consisting of Ag, In and rare earth elements as a main component.

  The light absorption layer 5 can be formed on the surface of the third dielectric layer 4 by a vapor phase growth method using a chemical species containing a constituent element of the light absorption layer 5. Examples include vacuum deposition and sputtering.

  The light absorption layer 5 preferably has a thickness of 5 nm to 100 nm. When the thickness of the light absorption layer 5 is less than 5 nm, the light absorption rate is too low. On the other hand, when the thickness of the light absorption layer 5 exceeds 100 nm, the decomposition reaction layer 8 is formed as described later. When the cavity is formed, the light absorption layer 5 becomes difficult to be deformed, which is not preferable.

  As shown in FIG. 2, an intermediate layer 6 is formed on the surface of the light absorption layer 5.

  The intermediate layer 6 plays a role of preventing the data recorded on the optical recording disk 1 from being deteriorated when the optical recording disk 1 is irradiated with the laser beam L set to the reproduction power.

  The intermediate layer 6 is a dielectric material containing an oxide, nitride, fluoride, or a composite thereof as a main component, or a dielectric material containing a sulfide or a composite containing sulfide as a main component. Can be formed.

  In the present embodiment, there is no particular limitation when the intermediate layer 6 is formed of a dielectric material containing oxide, nitride, fluoride, or a composite thereof excluding sulfide as a main component. However, when the intermediate layer 6 is formed of a dielectric material containing, as a main component, sulfide or a composite containing sulfide, the content of sulfur contained in the intermediate layer 6 is the second dielectric. It is formed so as to be smaller than the content of sulfur contained in the layer 7.

The intermediate layer 6 is preferably made of at least one metal selected from the group consisting of Si, Zn, Al, Ta, Ti, Co, Zr, Pb, Sn, Ca, Ce, V, Cu, Fe, Mg, and Y. The intermediate layer 6 is formed by a mixture of ZnS and SiO ₂ from the viewpoint of optical constant, thermal conductivity, mechanical properties and the like, formed from an oxide, a nitride, a sulfide, a fluoride, or a composite thereof. It is particularly preferred that it be formed.

  The thickness of the intermediate layer 6 is not particularly limited, but the intermediate layer 6 is preferably formed to have a thickness of 2 nm to 15 nm.

  If the thickness of the intermediate layer 6 is less than 2 nm, it is too thin to be formed as a continuous film. On the other hand, if the thickness of the intermediate layer 6 exceeds 15 nm, optical recording is performed. There is a problem that the reproduction characteristics when reproducing the data recorded on the disk 1 are deteriorated, which is not preferable.

  The intermediate layer 6 can be formed on the surface of the light absorption layer 5 by a vapor phase growth method using a chemical species containing the constituent element of the intermediate layer 6. Law.

  As shown in FIG. 2, a second dielectric layer 7 is formed on the surface of the intermediate layer 6.

  In the present embodiment, the second dielectric layer 7 has a function of physically and chemically protecting the decomposition reaction layer 8 described later together with the first dielectric layer 9 described later.

  As a material for forming the second dielectric layer 7, for example, the second dielectric layer 7 is formed of a dielectric material mainly composed of oxide, sulfide, nitride, or a combination thereof. The second dielectric layer 7 is preferably made of Si, Zn, Al, Ta, Ti, Co, Zr, Pb, Ag, Sn, Ca, Ce, V, Cu, Fe, and Mg. It is formed by a sulfide containing at least one selected metal or a composite containing a sulfide as a main component and containing an oxide, a nitride, or a fluoride.

  The second dielectric layer 7 can be formed on the surface of the light absorption layer 5 by a vapor phase growth method using a chemical species containing a constituent element of the second dielectric layer 7. Examples thereof include a vacuum deposition method and a sputtering method.

  The second dielectric layer 7 is preferably formed to have a thickness of 5 nm to 100 nm.

  As shown in FIG. 2, a decomposition reaction layer 8 is formed on the surface of the second dielectric layer 7.

  In this embodiment, the decomposition reaction layer 8 is used as a part of the recording layer, and a recording mark is formed in the decomposition reaction layer 8 when data is recorded on the optical recording disk 1.

  In this embodiment, the decomposition reaction layer 8 contains platinum oxide PtOx as a main component.

  In this embodiment, in order to obtain a reproduction signal having a high C / N ratio even when the length of a recording mark or the length of a blank area between adjacent recording marks is less than the resolution limit, 1 More preferably, 0 ≦ x <3.0.

  The decomposition reaction layer 8 can be formed on the surface of the second dielectric layer 7 by a vapor phase growth method using a chemical species containing a constituent element contained in the decomposition reaction layer 8 as a main component. Examples of the growth method include a vacuum deposition method and a sputtering method.

  The decomposition reaction layer 8 is formed so as to have a thickness of 2 nm to 20 nm, and preferably formed so as to have a thickness of 4 nm to 20 nm. Is not particularly limited.

  If the decomposition reaction layer 8 is too thin, the decomposition reaction layer 8 may not be formed as a continuous film. Conversely, if the decomposition reaction layer 8 is too thick, the decomposition reaction layer 8 Since it becomes difficult to deform, and as the length of the recording mark to be formed becomes shorter, it is considered that a cavity having a desired shape is less likely to be formed. In consideration of these, the thickness of the decomposition reaction layer is 2 nm to 20 nm. It is preferable to have a thickness of 4 nm to 20 nm.

  As shown in FIG. 2, a first dielectric layer 9 is formed on the surface of the decomposition reaction layer 8.

  In the present embodiment, the first dielectric layer 9 has a function of physically and chemically protecting the decomposition reaction layer 8.

  The material for forming the first dielectric layer 9 is not particularly limited. For example, the first dielectric layer 9 is formed using the same material as that of the third dielectric layer 4. be able to. The first dielectric layer 9 can be formed by a vapor phase growth method using chemical species including the constituent elements of the first dielectric layer 9, similarly to the third dielectric layer 4.

  As shown in FIG. 2, a light transmission layer 10 is formed on the surface of the first dielectric layer 9.

  The light transmission layer 10 is a layer through which the laser beam L is transmitted, and the surface of the light transmission layer 10 forms an incident surface of the laser beam L.

  The light transmission layer 10 preferably has a thickness of 10 μm to 200 μm, and more preferably, the light transmission layer 10 has a thickness of 50 μm to 150 μm.

  The material for forming the light transmission layer 10 is a material that is optically transparent, has little optical absorption and reflection in the wavelength region of 390 nm to 420 nm of the used laser beam L, and has low birefringence. There is no particular limitation, and when the light transmission layer 10 is formed by a spin coating method or the like, an ultraviolet curable resin, an electron beam curable resin, a thermosetting resin, or the like forms the light transmission layer 10. An active energy ray curable resin such as an ultraviolet curable resin or an electron beam curable resin is particularly preferably used for forming the light transmission layer 10.

  The light transmission layer 10 may be formed by adhering a sheet formed of a light transmission resin to the surface of the first dielectric layer 9 using an adhesive.

  The thickness of the light transmissive layer 10 is preferably 10 μm to 200 μm when the light transmissive layer 10 is formed by spin coating, and a sheet formed of a light transmissive resin is first bonded using an adhesive. When the light transmitting layer 10 is formed by bonding to the surface of the dielectric layer 9, the thickness is preferably 50 μm to 150 μm.

  On the optical recording disk 1 configured as described above, data is recorded and data is reproduced as follows.

  3A is a partially enlarged schematic cross-sectional view of the optical recording disk 1 before data is recorded, and FIG. 3B is a partially enlarged view of the optical recording disk 1 after data is recorded. FIG.

  When recording data on the optical recording disk 1, the optical recording disk 1 is irradiated with the laser beam L through the light transmission layer 10.

  In this embodiment, in order to record data at a high recording density, a laser beam L having a wavelength λ of 390 nm to 420 nm is applied to an optical recording disk 1 by an objective lens having a numerical aperture NA of 0.7 to 0.9. It is comprised so that it may concentrate on.

  The power of the laser beam L is set to be higher than 4 mW and not higher than 12 mW. Here, the power of the laser beam L is defined as the power of the laser beam L on the surface of the optical recording disk 1.

  When the optical recording disk 1 is irradiated with the laser beam L set to the recording power, the light absorption layer 5 is formed of an alloy containing at least one of Sb and Te having a high light absorption coefficient. The region of the light absorption layer 5 irradiated with the laser beam L is heated.

  The heat generated in the light absorption layer 5 is transferred to the decomposition reaction layer 8 and the temperature of the decomposition reaction layer 8 rises.

  Since platinum oxide contained as a main component in the decomposition reaction layer 8 has high permeability to the laser beam L, the decomposition reaction layer 8 itself hardly generates heat even when irradiated with the laser beam L, and the temperature of the decomposition reaction layer 8 is low. However, in this embodiment, the light absorption layer 5 formed of an alloy containing at least one of Sb and Te having a high light absorption coefficient is provided. Therefore, the light absorption layer 5 generates heat, the heat generated in the light absorption layer 5 is transmitted to the decomposition reaction layer 8, and the temperature of the decomposition reaction layer 8 rises.

  In this way, the decomposition reaction layer 8 is heated to a temperature higher than the decomposition temperature of platinum oxide, and the platinum oxide contained as the main component in the decomposition reaction layer 8 is decomposed into platinum and oxygen.

  As a result, as shown in FIG. 3B, platinum oxide is decomposed, and the generated oxygen gas forms cavities 8a in the decomposition reaction layer 8, and platinum fine particles 8b are formed in the cavities 8a. It precipitates in.

  At the same time, as shown in FIG. 3B, the decomposition reaction layer 8 is deformed together with the second dielectric layer 7 by the pressure of the oxygen gas.

  Thus, the cavity 8a is formed, and the region where the second dielectric layer 7 and the decomposition reaction layer 8 are deformed has optical characteristics different from those of other regions. Therefore, the cavity 8a is formed, and the second dielectric layer A recording mark is formed by a region where the 7 and the decomposition reaction layer 8 are deformed.

  In the present embodiment, the recording mark formed in this way and the blank area between adjacent recording marks include those having a length shorter than λ / 4NA, and there are recording mark rows less than the resolution limit. It is formed.

  In this embodiment, since the decomposition reaction layer 8 contains platinum oxide having a high decomposition temperature as a main component, the recording mark is formed by irradiating the laser beam L set at the recording power. In this case, even when heat diffuses from the region irradiated with the laser beam L to the surrounding decomposition reaction layer 8, the decomposition reaction of platinum oxide occurs in a region other than the region irradiated with the laser beam. Therefore, the cavity 8a can be formed in a desired region of the decomposition reaction layer 8 to form a recording mark.

  Further, in the present embodiment, platinum oxide is decomposed and platinum fine particles 8b are deposited in the cavities 8a to form recording marks. The particle diameter of the platinum fine particles 8b is determined by the decomposition reaction. Since the size of the cavity 8a to be formed in the layer 8 is smaller, the shape of the cavity 8a is adversely affected by the platinum fine particles 8b deposited in the cavity 8a, and an undesirable change occurs in the shape of the recording mark. Can be prevented.

  In this way, data is recorded on the optical recording disk 1, and the data recorded on the optical recording disk 1 is reproduced as follows.

  When reproducing data recorded on the optical recording disk 1, first, a laser beam L having a wavelength λ of 390 to 420 nm is applied to the optical recording disk by an objective lens having a numerical aperture NA of 0.7 to 0.9. 1 is condensed.

  In this embodiment, the power of the laser beam L applied to the optical recording disk 1 for reproducing data is higher than usual and is set to 1 mW to 4 mW.

  According to the inventor's research, a laser beam L having a wavelength λ of 390 nm to 420 nm is thus passed through the light transmission layer 10 using an objective lens having a numerical aperture NA of 0.7 to 0.9. By collecting light on the optical recording disk 1, data can be reproduced even when the length of the recording mark constituting the recording mark row and the length of the blank area between adjacent recording marks are less than the resolution limit. It has been found possible.

  Platinum oxide contained as a main component in the decomposition reaction layer 8 is decomposed into platinum and oxygen, and the generated oxygen gas forms cavities 8a in the decomposition reaction layer 8, and platinum fine particles 8b are cavities. 8a, when the recording mark is formed in the decomposition reaction layer 8 and the data is recorded, the length of the recording mark constituting the recording mark row and the length of the blank area between the adjacent recording marks are The reason why data can be reproduced even when the resolution is below the resolution limit is not necessarily clear, but by reproducing the laser beam L for reproduction onto the platinum fine particles 8b deposited in the cavity 8a. The resolution limit is small because the near-field light is generated and the resolution limit disappears, or due to the interaction between the platinum fine particles 8b deposited in the cavity 8a and the irradiated laser beam L. It is presumed that it is the order became clause.

  In the present embodiment, the decomposition reaction layer 8 contains platinum oxide having a high decomposition temperature as a main component, so that even when data is reproduced by irradiation with a high-power reproducing laser beam, platinum is also used. There is no possibility that the oxide is decomposed into platinum and oxygen. Therefore, even if data recorded on the optical recording disk 1 is reproduced repeatedly, the shape of the recording mark does not change, and the cavity 8a is formed. In addition, since no new cavity is formed in a region other than the region where the recording mark is formed, it is possible to improve the reproduction durability of the optical recording disk 1.

  Further, in the present embodiment, a dielectric material containing an element other than sulfur as a main component or a second dielectric layer 7 is included between the light absorption layer 5 and the second dielectric layer 7. The intermediate layer 6 mainly composed of a dielectric material containing sulfur with a small content compared to the content of sulfur is formed, and according to the study of the present inventor, the intermediate layer 6 is high when having such a configuration. Even when data is reproduced a plurality of times by repeatedly irradiating with a power reproducing laser beam, the signal characteristics of the reproduction signal when the data recorded on the optical recording disk 1 is reproduced are deteriorated. It has been found that it can be suppressed.

  Dielectric material containing as a main component an element excluding sulfur, or an intermediate layer containing as a main component a dielectric material containing a small amount of sulfur compared to the content of sulfur contained in the second dielectric layer 7 When 6 is formed between the light absorption layer 5 and the second dielectric layer 7, it is possible to suppress deterioration in the signal characteristics of the reproduction signal when the data recorded on the optical recording disk 1 is reproduced. The reason why the laser beam can be produced is not necessarily clear, but the intermediate layer 6 having such a configuration is formed between the light absorption layer 5 and the second dielectric layer 7 so that a high-power reproducing laser beam is irradiated. Even when the light absorption layer 5 is heated, the sulfur contained in the second dielectric layer 7 does not mix with the elements contained in the light absorption layer 5, and as a result, the light absorption layer 5. The adverse effect on the optical characteristics of the change of the state of the can was eliminated It is presumed that it is the fit.

  Therefore, according to this embodiment, the reproduction durability of the optical recording disk 1 can be further improved.

  4 is a schematic perspective view of an optical recording disk according to another preferred embodiment of the present invention, and FIG. 5 is indicated by B in the cross section along the track of the optical recording disk shown in FIG. It is a substantially expanded sectional view of a part.

  As shown in FIG. 5, the optical recording disk 20 according to this embodiment includes a support substrate 2, and on the support substrate 2, the reflective layer 3, the third dielectric layer 4, the intermediate layer 16, The light absorption layer 5, the second dielectric layer 7, the decomposition reaction layer 8, the first dielectric layer 9, and the light transmission layer 10 are laminated in this order. Unlike the optical recording disk 1 shown, an intermediate layer 16 is formed between the third dielectric layer 4 and the light absorption layer 5.

  Similar to the intermediate layer 6 shown in FIG. 2, the intermediate layer 16 deteriorates the data recorded on the optical recording disk 20 when the optical recording disk 20 is irradiated with the laser beam L set to the reproduction power. It plays a role to prevent it.

  The intermediate layer 16 can be formed of the same dielectric material as that of the intermediate layer 6 shown in FIG. 2, and is mainly composed of oxide, nitride, fluoride, or a composite thereof except sulfide. In the case of being formed of a dielectric material containing, there is no particular limitation, but in the case of being formed of a dielectric material containing a sulfide or a composite containing sulfide as a main component, it is included in the intermediate layer 16. The sulfur content is formed so as to be smaller than the sulfur content contained in the third dielectric layer 4.

  The thickness of the intermediate layer 16 is not particularly limited, but the intermediate layer 16 is preferably formed to have a thickness of 2 nm or more.

  When the thickness of the intermediate layer 16 is less than 2 nm, it is not preferable because the thickness is too thin and it is difficult to form the continuous layer 16 as a continuous film.

  The intermediate layer 16 can be formed on the surface of the third dielectric layer 4 by a vapor phase growth method using a chemical species containing a constituent element of the intermediate layer 16. Method, sputtering method and the like.

  According to the inventor's research, a dielectric material containing an element excluding sulfur as a main component, or a dielectric containing a small amount of sulfur compared to the content of sulfur contained in the third dielectric layer 4 When the intermediate layer 16 mainly composed of the body material is formed between the third dielectric layer 4 and the light absorption layer 5, the high-power reproducing laser beam is repeatedly irradiated, and a plurality of times, It has been found that even when data is reproduced, it is possible to effectively suppress the deterioration of the signal characteristics of the reproduced signal when the data recorded on the optical recording disk 20 is reproduced. According to this, it becomes possible to improve the reproduction durability of the optical recording disk 20.

  Examples are given below to clarify the effects of the present invention.

Example 1
A polycarbonate substrate having a thickness of 1.1 mm and a diameter of 120 mm was set in a sputtering apparatus, and a reflective layer containing Ag, Pd and Cu and having a thickness of 20 nm was formed on the polycarbonate substrate by a sputtering method.

Next, a third dielectric layer having a thickness of 100 nm was formed on the surface of the reflective layer by sputtering using a mixture of ZnS and SiO ₂ as a target. As the mixture of ZnS and SiO _2, the molar ratio of ZnS and SiO ₂ was used target 80:20.

Next, a light absorption layer having a thickness of 20 nm was formed on the surface of the third dielectric layer by sputtering using Sb and Te as targets. The composition of the light absorption layer was Sb ₇₄ Te ₂₆ in terms of atomic ratio.

Next, an intermediate layer having a thickness of 5 nm was formed on the surface of the light absorption layer by sputtering using a target made of a mixture of ZnS and SiO ₂ . As the mixture of ZnS and SiO _2, the molar ratio of ZnS and SiO ₂ was used target 50:50.

Next, a second dielectric layer having a thickness of 60 nm was formed on the surface of the intermediate layer by sputtering using a target made of a mixture of ZnS and SiO ₂ . As the mixture of ZnS and SiO _2, the molar ratio of ZnS and SiO ₂ was used target 80:20.

  Next, on the surface of the second dielectric layer, a mixed gas of Ar gas and oxygen gas is used as a sputtering gas, and a Pt target is used to form platinum oxide as a main component by sputtering using a Pt target. A decomposition reaction layer having was formed.

Finally, a first dielectric layer having a thickness of 95 nm was formed on the surface of the decomposition reaction layer by sputtering using a target made of a mixture of ZnS and SiO ₂ . As the mixture of ZnS and SiO _2, the molar ratio of ZnS and SiO ₂ was used target 80:20.

  Thus, an optical recording disk sample # 1 was produced.

  Next, the optical recording disk sample is formed except that the second dielectric layer is formed on the surface of the light absorption layer without forming the intermediate layer and the thickness of the first dielectric layer is set to 75 nm. In the same manner as in # 1, an optical recording disk comparison sample # 1 was produced.

  Next, the optical recording disk sample # 1 was set in an optical recording disk evaluation apparatus “DDU1000” (trade name) manufactured by Pulstec Industrial Co., Ltd., and a blue laser beam having a wavelength of 405 nm was used as a recording laser beam. Using an objective lens having a numerical NA of 0.85, the laser beam is condensed through the first dielectric layer, and a resolution mark of less than 120 nm of a 75 nm recording mark, a 75 nm blank area, Of the optical recording disk sample # 1 under the following conditions: a recording mark string consisting of repetition of the recording mark and a recording mark string consisting of repetition of the 300 nm recording mark longer than the resolution limit and the 300 nm blank area. Formed into layers. Here, the recording power was set to 5.0 mW.

Recording linear velocity: 4.9 m / s
Recording method: On-groove recording After the formation of the recording mark row, the same optical recording disk evaluation apparatus is used to reproduce the data recorded on the optical recording disk sample # 1, and to measure and reproduce the C / N ratio of the reproduction signal. The reflectance was measured when the recording mark array was irradiated with a laser beam set to power. Here, the reproduction power of the laser beam was set to 2.0 mW, and the reproduction linear velocity was set to 4.9 m / s.

  The measurement result of the C / N ratio of the reproduction signal when reproducing the data recorded by forming the record mark row of 75 nm is shown by the curve A in FIG. 6, and the record mark row of 300 nm is formed and recorded. The measurement result of the C / N ratio of the reproduced signal when the reproduced data is reproduced is shown by a curve A in FIG.

  Next, using the same optical recording disk evaluation apparatus, the data recorded on the optical recording disk sample # 1 is repeatedly reproduced up to 1000 times, and the C / N ratio and reflectance of the reproduction signal when the number of reproductions is 1000 times are obtained. While measuring, the change in reflectance was calculated based on the measured reflectance. Here, the change in the reflectance is the reflectance when the recorded data is reproduced 1000 times when the reflectance when the data recorded on the optical recording disk sample # 1 is reproduced once is 1.0. It was defined by the ratio to the reflectance when the recorded data was reproduced once.

  The measurement result of the C / N ratio of the reproduction signal when the data recorded by forming the record mark row of 75 nm is reproduced 1000 times is shown by the curve A in FIG. 6, and the record mark row of 300 nm is formed. The measurement result of the C / N ratio of the reproduced signal when the recorded data is reproduced 1000 times is shown by a curve A in FIG.

  The change in reflectance when the data recorded with the 75 nm recording mark row is reproduced 1000 times is shown by the curve A in FIG. 8, and the data recorded with the 300 nm recording mark row recorded. The change in reflectance when 1000 is reproduced 1000 times is shown by curve A in FIG.

  Next, using the same optical recording disk evaluation apparatus, data recorded by forming a record mark string of 75 nm on the decomposition reaction layer of the optical recording disk sample # 1 was repeatedly reproduced up to 10,000 times, and the number of reproductions was 2000 times. The C / N ratio and the reflectance of the reproduction signal at 4000 times, 7000 times, and 10,000 times were measured, and the change in the reflectance was calculated.

  The measurement result and the calculation result are shown by a curve A in FIG. 6 and a curve A in FIG. 7, respectively.

  Next, data recorded by forming a 300 nm recording mark row in the decomposition reaction layer of the optical recording disk sample # 1 is repeatedly reproduced up to 4000 times, and the reproduction signal C when the number of reproductions is 2000 times and 4000 times. The / N ratio and the reflectance were measured, and the change in reflectance was calculated.

The measurement result and the calculation result are shown by a curve A in FIG. 8 and a curve A in FIG. 9, respectively.
Next, the optical recording disk comparison sample # 1 was set in the same optical recording disk evaluation apparatus, and recording mark rows of 75 nm and 300 nm were formed in the decomposition reaction layer in the same manner as the optical recording disk sample # 1. Here, the recording power of the laser beam was set to 5.0 mW.

  Next, using the same optical recording disk evaluation apparatus, data recorded by forming a record mark string of 75 nm on the decomposition reaction layer of the optical recording disk sample # 1 was repeatedly reproduced up to 10,000 times, and the number of reproductions was 2000 times. The C / N ratio and the reflectance of the reproduction signal at 4000 times, 7000 times, and 10,000 times were measured, and the change in the reflectance was calculated. Here, the reproduction power of the laser beam was set to 2.0 mW, and the reproduction linear velocity was set to 4.9 m / s.

The measurement result and the calculation result are shown by a curve B in FIG. 6 and a curve B in FIG. 7, respectively.
Next, data recorded by forming a 300 nm recording mark row in the decomposition reaction layer of the optical recording disk comparative sample # 1 is repeatedly reproduced up to 4000 times, and the reproduction signal when the number of reproductions is 2000 times and 4000 times is reproduced. While measuring the C / N ratio and the reflectance, the change in reflectance was calculated.

  The measurement result and the calculation result are shown by a curve B in FIG. 8 and a curve B in FIG. 9, respectively.

  As is apparent from FIG. 6, when recording data is recorded by forming a recording mark string less than the resolution limit, and the recorded data is repeatedly reproduced a plurality of times, the optical recording disk comparison sample # in which no intermediate layer is formed In contrast, the C / N ratio of the reproduction signal decreased as the number of reproductions increased, whereas an intermediate layer was provided between the light absorption layer and the second dielectric layer. In the optical recording disk sample # 1, it was recognized that the C / N of the reproduction signal hardly changed even when the number of reproductions was increased.

  As is clear from FIG. 8, when the reproducing laser beam is repeatedly irradiated a plurality of times to the recording mark row formed in the decomposition reaction layer and less than the resolution limit, the optical recording disc sample # 1 Compared to the recording disk comparative sample # 1, the gradient at which the reflectance decreases is gentle, and it was confirmed that the recording disk had high reproduction durability.

  Further, as apparent from FIGS. 7 and 9, when data is recorded by forming a record mark string longer than the resolution limit, and the recorded data is reproduced repeatedly over a plurality of times, the optical recording disk sample # 1 Both the gradient at which the C / N ratio of the reproduced signal decreases and the gradient at which the reflectance decreases are lower than those of the optical recording disk comparison sample # 1, and recording was performed by forming recording marks longer than the resolution limit. It was confirmed that the data had high reproduction durability even when the data was repeatedly reproduced multiple times.

Example 2
A polycarbonate substrate having a thickness of 1.1 mm and a diameter of 120 mm was set in a sputtering apparatus, and a reflective layer containing Ag, Pd and Cu and having a thickness of 40 nm was formed on the polycarbonate substrate by a sputtering method.

  Next, a third dielectric layer and a light absorbing layer were sequentially formed on the surface of the reflective layer in the same manner as in the optical recording disk sample # 1.

Next, an intermediate layer having a thickness of 5 nm was formed on the surface of the light absorption layer by sputtering using an Al ₂ O ₃ target.

  Next, a second dielectric layer and a decomposition reaction layer were sequentially formed on the surface of the intermediate layer in the same manner as in the optical recording disk sample # 1.

Finally, a first dielectric layer having a thickness of 90 nm was formed on the surface of the decomposition reaction layer by sputtering using a target made of a mixture of ZnS and SiO ₂ . As the mixture of ZnS and SiO _2, the molar ratio of ZnS and SiO ₂ was used target 80:20.

  Thus, an optical recording disk sample # 2 was produced.

  Next, an optical recording disk sample # 3 was produced as follows.

  In the same manner as in the optical recording disk sample # 2, a reflective layer and a third dielectric layer were sequentially formed on a polycarbonate substrate.

Next, an intermediate layer having a thickness of 5 nm was formed on the surface of the third dielectric layer by a sputtering method using an Al ₂ O ₃ target.

  Next, a light absorption layer, a second dielectric layer, and a decomposition reaction layer are sequentially formed on the surface of the intermediate layer in the same manner as in the optical recording disk sample # 1, and finally, the optical recording disk sample # 2 In the same manner as described above, a first dielectric layer having a thickness of 90 nm was formed.

  Thus, an optical recording disc sample # 3 was produced.

  Next, an optical recording disk sample is formed except that the intermediate layer is not formed on the surface of the light absorption layer, the second dielectric layer is formed, and the thickness of the first dielectric layer is set to 70 nm. In the same manner as in # 2, an optical recording disk comparison sample # 2 was produced.

  Next, optical recording disk samples # 2 and # 3 and optical recording disk comparison sample # 2 are sequentially set in the same optical recording disk evaluation apparatus as the optical recording disk evaluation apparatus used in the first embodiment. In the same manner as described above, in the decomposition reaction layers of the optical recording disk samples # 2 and # 3 and the optical recording disk comparison sample # 2, a recording mark string composed of a repetition of a 75 nm recording mark and a 75 nm blank area, and 300 nm Each of the recording mark rows formed by repeating the recording mark and the 300 nm blank region was formed. Here, the recording power of the laser beam was set to 7.0 mW, and the recording linear velocity was set to 4.9 m / s.

  Next, using the same optical recording disk evaluation apparatus, the data recorded in the optical recording disk samples # 2 and # 3 and the optical recording disk comparison sample # 2 are repeatedly reproduced up to 10,000 times, and the number of times of reproduction is 1, The C / N ratio and reflectance of the reproduced signal at 2000 times, 4000 times, 7000 times, and 10,000 times were measured, and the change in reflectance was calculated. Here, the reproduction power of the laser beam was set to 2.4 mW, and the reproduction linear velocity was set to 4.9 m / s.

  C / N ratio of reproduced signal when data recorded by forming a record mark row of 75 nm in the decomposition reaction layer of optical recording disk samples # 2 and # 3 and optical recording disk comparison sample # 2 is reproduced 10,000 times The measurement results are shown in curve C, curve D, and curve E in FIG. 10, respectively. In the decomposition reaction layers of optical recording disk samples # 2 and # 3 and optical recording disk comparison sample # 2, 300 nm The measurement results of the C / N ratio of the reproduction signal when the data recorded by forming the recording mark row is reproduced 10,000 times are shown by a curve C, a curve D, and a curve E in FIG.

  The change in reflectance when data recorded by forming a record mark row of 75 nm on the decomposition reaction layer of the optical recording disk samples # 2 and # 3 and the optical recording disk comparison sample # 2 is reproduced 10,000 times. 12 are shown in curve C, curve D and curve E in FIG. 12, respectively, and a 300 nm recording mark row is formed on the decomposition reaction layers of optical recording disk samples # 2 and # 3 and optical recording disk comparison sample # 2. The change in reflectance when the formed and recorded data is reproduced 10,000 times is shown by curve C, curve D, and curve E in FIG.

  As is clear from FIG. 10, when recording data is recorded by forming a record mark row less than the resolution limit, and the recorded data is repeatedly reproduced a plurality of times, the optical recording disc comparison sample # in which no intermediate layer is formed However, when the number of reproductions exceeds 2000, the C / N ratio of the reproduction signal is remarkably lowered, whereas the optical recording in which an intermediate layer is formed between the light absorption layer and the second dielectric layer. In the disk sample # 2 and the optical recording disk sample # 3 in which the intermediate layer is formed between the third dielectric layer and the light absorption layer, the C / N of the reproduction signal is increased even if the number of reproductions is increased. Was found to change little.

  Further, as apparent from FIG. 12, when the recording mark row formed in the decomposition reaction layer and less than the resolution limit is repeatedly irradiated with the reproducing laser beam a plurality of times, the reflection is reflected in the optical recording disk sample # 2. It is recognized that the gradient in which the rate decreases is the gradual and has the highest reproduction durability. Also in the optical recording disc sample # 3, the gradient in which the reflectance decreases after the optical recording disc sample # 2. It was found to be gradual and have high reproduction durability.

  Further, as apparent from FIG. 11, when data is recorded by forming a record mark string longer than the resolution limit, and the recorded data is repeatedly reproduced a plurality of times, the optical recording disk comparison sample # 2 is reproduced In the optical recording disk samples # 2 and # 3, it was recognized that the C / N of the reproduction signal hardly changed when the value of 4,000 exceeded 4000 times. It was. However, in the optical recording disk samples # 2 and # 3, it was recognized that the C / N ratio of the reproduction signal was lower when the number of reproductions was less than 10,000, compared to the optical recording disk comparison sample # 2. In any case, even if the number of reproductions is increased, the C / N ratio of 40 dB or more is maintained. Therefore, there is no problem even if the optical recording disk is repeatedly used in an actual use environment.

  Further, as is apparent from FIG. 13, when a recording laser beam longer than the resolution limit formed in the decomposition reaction layer is repeatedly irradiated with a reproducing laser beam a plurality of times, optical recording disk samples # 2 and # 3 In both of the optical recording disk comparison samples # 2, the number of reproduction decreased as the number of reproductions increased. However, when the number of reproductions reached 4000 or more, in the optical recording disk samples # 2 and # 3, As compared with the optical recording disk comparative sample # 2, it was confirmed that the change in reflectance was small and that the reproduction durability was high.

  The present invention is not limited to the above embodiments and examples, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. It goes without saying that it is a thing.

  For example, in the optical recording disk 1 according to the embodiment shown in FIGS. 1 and 2, an intermediate layer 16 is formed between the light absorbing layer 5 and the second dielectric layer 7, and FIGS. 3 and 4 are used. In the optical recording disk 20 according to the embodiment shown in FIG. 1, an intermediate layer 16 is formed between the third dielectric layer 4 and the light absorption layer 5. It may be formed both between the second dielectric layer 7 and between the third dielectric layer 4 and the light absorption layer 5.

  An optical recording disk 1 according to the embodiment shown in FIGS. 1 and 2 includes a support substrate 2, and a reflective layer 3, a third dielectric layer 4, and a light absorption layer 5 are provided on the support substrate 2. The intermediate layer 6, the second dielectric layer 7, the decomposition reaction layer 8, the first dielectric layer 9, and the light transmission layer 10 are laminated in this order, and the light transmission layer 10 side However, the present invention is not limited to this. For example, the present invention includes a light transmissive substrate having a thickness of about 0.6 mm and is light transmissive. A first dielectric layer 9, a decomposition reaction layer 8, a second dielectric layer 7, an intermediate layer 6, a light absorption layer 5, and a third dielectric layer 4 are sequentially stacked on the substrate. The present invention can also be applied to a DVD-type optical recording disk configured to be irradiated with the laser beam L from the light transmissive substrate side.

  Further, in the optical recording disks 1 and 20 according to the embodiments shown in FIGS. 1 and 2 and FIGS. 4 and 5, the decomposition reaction layer 8 and the second dielectric are formed from the light incident surface of the laser beam L. The layer 7 and the light absorption layer 5 are laminated in this order, but the present invention is not limited to this. For example, from the opposite side of the light incident surface of the laser beam L, the decomposition reaction layer 8 and the first layer The second dielectric layer 7 and the light absorption layer 5 may be laminated in order, or from the light incident surface of the laser beam L, the light absorption layer, the dielectric layer, the decomposition reaction layer, and the dielectric layer And a light absorption layer may be laminated in order. That is, in the present invention, the optical recording disk only needs to have a laminate in which the decomposition reaction layer and the light absorption layer are formed with at least the dielectric layer interposed therebetween.

FIG. 1 is a schematic cross-sectional view of an optical recording disk according to a preferred embodiment of the present invention. FIG. 2 is a schematic enlarged cross-sectional view of a portion indicated by A in FIG. 3A is a partially enlarged schematic sectional view of the optical recording disk before data is recorded, and FIG. 3B is a partially enlarged schematic sectional view of the optical recording disk after data is recorded. FIG. FIG. 4 is a schematic cross-sectional view of an optical recording disk according to another preferred embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view of a portion indicated by B in FIG. FIG. 6 shows the number of reproductions and the C / N ratio of the reproduction signal when reproducing data recorded with recording marks less than the resolution limit for the optical recording disk sample # 1 and the optical recording disk comparison sample # 1. It is a graph which shows the relationship. FIG. 7 shows the number of reproductions and the C / N ratio of the reproduction signal when reproducing data recorded with recording marks longer than the resolution limit for the optical recording disk sample # 1 and the optical recording disk comparison sample # 1. It is a graph which shows the relationship. FIG. 8 shows the relationship between the number of reproductions and the change in reflectance when reproducing data recorded with recording marks less than the resolution limit for optical recording disk sample # 1 and optical recording disk comparison sample # 1. It is a graph to show. FIG. 9 shows the relationship between the number of reproductions and the change in reflectance when reproducing data recorded with recording marks longer than the resolution limit for the optical recording disk sample # 1 and the optical recording disk comparison sample # 1. It is a graph to show. FIG. 10 shows the number of times of reproduction and the C of the reproduction signal when reproducing the data recorded with the recording mark less than the resolution limit for the optical recording disk samples # 2 and # 3 and the optical recording disk comparison sample # 2. It is a graph which shows the relationship with / N ratio. FIG. 11 shows the number of reproductions and C of the reproduction signal when reproducing data recorded by forming recording marks longer than the resolution limit for the optical recording disk samples # 2 and # 3 and the optical recording disk comparison sample # 2. It is a graph which shows the relationship with / N ratio. FIG. 12 shows changes in the number of reproductions and reflectance when data recorded with recording marks less than the resolution limit is reproduced for optical recording disk samples # 2 and # 3 and optical recording disk comparison sample # 2. It is a graph which shows the relationship. FIG. 13 shows changes in the number of reproductions and reflectance when data recorded with recording marks longer than the resolution limit is reproduced for optical recording disk samples # 2 and # 3 and optical recording disk comparison sample # 2. It is a graph which shows the relationship.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical recording disk 2 Support substrate 3 Reflective layer 4 Third dielectric layer 5 Light absorption layer 6 Intermediate layer 7 Second dielectric layer 8 Decomposition reaction layer 9 First dielectric layer 10 Light transmission layer 16 Intermediate layer 20 Optical recording disc

Claims (7)

An optical recording disk configured such that data is recorded and reproduced by irradiation with a laser beam, the decomposition reaction layer including a noble metal oxide as a main component, and a dielectric material including sulfur as a main component. And a dielectric material containing as a main component an element excluding sulfur, or a dielectric material containing a small amount of sulfur as compared with the content of sulfur contained in the dielectric layer. An optical recording disk comprising a laminate in which an intermediate layer and a light absorption layer are sequentially laminated. An optical recording disk configured to be irradiated with a laser beam to record and reproduce data, a decomposition reaction layer containing a precious metal oxide as a main component, a second dielectric layer, and light absorption A layer, an intermediate layer, and a third dielectric layer stacked in order, the third dielectric layer including a dielectric material containing sulfur as a main component, and the intermediate layer including sulfur A dielectric material containing as a main component an element other than the above, or a dielectric material containing a small amount of sulfur as compared with the content of sulfur contained in the third dielectric layer as a main component. A featured optical recording disc. When the laser beam is irradiated, the noble metal oxide contained as a main component in the decomposition reaction layer is decomposed into noble metal and oxygen, and the generated oxygen gas forms a cavity, and the noble metal The optical recording disk according to claim 1, wherein a recording mark is formed in the decomposition reaction layer by depositing the fine particles in the cavity. The noble metal oxide is composed of platinum oxide, and is decomposed into platinum and oxygen when irradiated with the laser beam through a light incident surface of the laser beam. The optical recording disk described. The platinum fine particles have a particle size smaller than the size of the cavity to be formed in the decomposition reaction layer (the particle size of the platinum fine particles is defined as a diameter when the platinum fine particles are spherical). The optical recording disk according to claim 4. The optical recording disk according to claim 1, wherein the light absorption layer includes at least one of Sb and Te. The light according to claim 1, wherein the dielectric layer, the intermediate layer, and the light absorption layer are configured to be deformed as the cavity is formed in the decomposition reaction layer. Recording disc.

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