JP4949313B2 - Information recording medium, information recording apparatus, information recording method, and method for manufacturing the information recording medium - Google Patents

Description

  The present invention relates to an information recording medium capable of recording information by heating or by heating and magnetic action.

In recent years, the amount of information handled has become enormous due to the arrival of an advanced information society, and there has been a demand for a large capacity and high density recording apparatus. In the field of magnetic recording typified by hard disks, recording density exceeding 300 Gbit (300 Gbit / inch ² ) per square inch is being achieved by improving the characteristics of recording media, recording heads, and reproducing heads. . Improvement of the surface density of the recording medium is still progressing, and in the future, it is considered to exceed 1 Tbit per square inch (1 Tbit / inch ² ).

  As a recording method capable of recording magnetic bits with high spatial resolution on a magnetic recording medium, an optically assisted magnetic recording method has been proposed. The optically assisted magnetic recording system is attracting attention as a promising technology for next-generation high-density magnetic recording, and performs magnetic recording on a magnetic recording medium having a high coercive force (Hc) and resistant to thermal fluctuations. Specifically, the coercive force (Hc) of the magnetic recording medium is reduced by condensing light on the surface of the magnetic recording medium and locally raising the temperature of the magnetic recording medium. Magnetic recording is performed on the magnetic recording medium by applying an external magnetic field to the portion where the coercive force (Hc) is reduced. Patent Document 1 discloses a method of recording information on a magnetic recording medium on which a recording layer made of a ferrimagnetic material is formed using an optically assisted magnetic recording method.

  Patent Documents 2 to 4 disclose methods using near-field light as a heat source for locally heating a magnetic recording medium in the optically assisted magnetic recording method. Here, “near-field light” in this specification and the like is generated when light is incident on a minute structure smaller than the wavelength of light, for example, a structure such as an opening, and is very close to the opening. It refers to light (electromagnetic field) that is localized only in.

  Among these, in Patent Document 3, a probe using a planar scatterer that reduces the influence of near-field light generated in a portion other than the point where strong near-field light is generated, and the probe are recorded / recorded. An example applied to a playback apparatus is disclosed. Patent Document 4 discloses that an electromagnetic field can be generated by irradiating a conductor with laser light, generating a strong near field near the edge of the conductor, and generating a magnetic field around the conductor by flowing a current through the conductor. An example in which an element and the electromagnetic field generating element are applied to an information recording / reproducing apparatus is disclosed.

In addition to magnetic recording, in the field of optical recording, a recording medium having a high recording density such as a Blu-ray disc (registered trademark) has been developed. Also in the field of optical recording, the wavelength of a light source is shortened and the density is increased by using near-field light technology such as SIL (Solid Immersion Lens) and SIM (Solid Immersion Mirror). For example, Patent Document 5 discloses a near-field head using a combination of SIL and a minute aperture.
Japanese Patent Laid-Open No. 04-176034 (Patent No. 2617025) (published on June 23, 1992) Japanese Unexamined Patent Publication No. 2000-195002 (released on July 14, 2000) JP 2004-151046 A (published May 27, 2004) JP 2006-114099 A (published April 27, 2006) JP 2000-163797 A (released on June 16, 2000)

  Thus, in the optically assisted magnetic recording technology and the optical recording technology, it is necessary to heat the magnetic recording medium to a predetermined temperature during recording. Therefore, in order to increase the recording speed, that is, to shorten the time required for recording, it is necessary to increase the irradiation power of the semiconductor laser as the light source. In other words, the optically assisted magnetic recording technique and the optical recording technique have a problem that the recording speed is limited by the upper limit of the output of the semiconductor laser. Conversely, in order to increase the recording speed, a high-power laser beam must be generated, which causes a problem that the power consumption of the information recording apparatus increases.

  The present invention has been made in view of the above problems, and a main object thereof is to provide an information recording medium that shortens the time required for recording without increasing the power consumption of the light source. Also provided are a manufacturing method for manufacturing the information recording medium, an information recording apparatus for recording information on the information recording medium, and a method for recording information by the information recording apparatus.

In order to solve the above problems, an information recording medium according to the present invention provides
An information recording medium comprising an information recording layer formed directly or indirectly on a substrate and continuous in the in-plane direction of the substrate,
The information recording layer has a plurality of convex portions, and a metal body is provided between the adjacent convex portions via a dielectric.

  In the information recording medium according to the present invention, a metal body is provided via a dielectric between adjacent convex portions in the information recording layer. Therefore, when the information recording medium is irradiated with light, high-intensity electric field concentration (local plasmon) can be generated at the interface between the metal body and the dielectric. As a result, not only from the surface of the information recording medium but also from the inside of the information recording medium, the location where information is to be recorded in the information recording layer can be heated, so that the location where information is to be recorded can be efficiently heated. it can.

  As described above, the information recording medium according to the present invention can efficiently heat a portion where information is to be recorded in the information recording layer, and thus has an effect of increasing the information recording speed.

  Also, since plasmons converted from light emitted from the light source selectively propagate and localize at the interface between the dielectric and the metal body, only the area around the location where information is to be recorded in the information recording layer. Can cause electric field concentration. Thereby, since the information recording medium can be locally heated, the information can be recorded with high density.

  Furthermore, by forming the metal body in the concave portion between the adjacent convex portions, the metal body can be formed inside the information recording medium while keeping the surface of the information recording medium smooth. As a result, recording / reproducing can be performed with the recording / reproducing head being brought close to the information recording medium, so that it is possible to record information at a high density.

  In the information recording medium according to the present invention, it is preferable that the information recording layer is formed along the shape of the substrate surface.

  According to said structure, since the several convex part in an information recording layer can be formed by forming an information recording layer on a board | substrate, there exists an effect which can manufacture manufacture of an information recording medium easily. .

  In addition, since the convex portion of the information recording layer can be formed so as to follow the shape of the substrate surface, exposure to the air on the surface of the information recording layer, which was necessary in the conventional manufacturing method, and etching processing of the information recording layer Such a process can be avoided. For this reason, the effect which can prevent impairing the original characteristic of an information recording layer is produced.

  Furthermore, there is an effect that not only the information recording layer but also a dielectric and a metal can be continuously formed on the substrate.

  In the information recording medium according to the present invention, it is preferable that the metal body is continuously provided so as to surround the convex portion.

  According to said structure, since the metal body is provided continuously around the convex part currently formed in the information recording layer, the area | region enclosed by this metal body can be heated locally strongly. it can. This produces an effect that a minute recording area can be formed in the information recording medium.

  Further, when the information recording layer is made of a magnetic material, there is an effect that the information recording medium can function as a patterned medium.

  In the information recording medium according to the present invention, it is preferable that the metal body is divided into a plurality of portions around the convex portion.

  According to the above configuration, since the metal body is divided into a plurality of portions around the convex portion formed in the information recording layer, the plasmon generated at the interface between the metal body and the dielectric is It is confined to each metal body provided separately. This can cause an extremely high electric field concentration at the interface between the metal body and the dielectric. That is, the convex portion, which is a region surrounded by a metal body in which electric field concentration has occurred, can be heated extremely strongly locally.

  Therefore, it is possible to form a minute recording area in the information recording medium and to reduce the power consumption of the light source.

  Further, when the information recording layer is made of a magnetic material, there is an effect that the information recording medium can function as a patterned medium.

  In the information recording medium according to the present invention, the metal body is preferably provided continuously in the track length direction.

  According to said structure, the convex part currently formed in the information recording layer which is an area | region pinched | interposed into the metal body can be heated locally strongly. This produces an effect that a minute recording area can be formed in the information recording medium.

  Further, when the information recording layer is made of a magnetic material, the information recording medium can function as a discrete track medium.

  In the information recording medium according to the present invention, it is preferable that the metal body is made of gold, silver, aluminum, platinum, or an alloy containing at least one of these.

  According to the above configuration, gold, silver, aluminum, platinum, or an alloy containing at least one of them has high plasmon generation efficiency, and plasmon is efficiently generated at the interface between the metal body and the dielectric. Can be made.

  Therefore, by using the above substance as the metal body, there is an effect that a strong electric field can be concentrated at the interface between the metal body and the dielectric.

  In the information recording medium according to the present invention, the information recording layer is preferably made of a magnetic material.

  According to said structure, an information recording medium can be utilized as a magnetic recording medium suitable for optically assisted magnetic recording. That is, the information recording medium having the above configuration can be used as a magnetic recording medium with high density and reduced recording time without increasing the power consumption of the light source.

  Moreover, since the information recording layer is provided continuously, the convex portions in the information recording layer are connected by a magnetic material having a weak magnetic anisotropy. Thereby, since the convex portions generate weak exchange coupling force, the magnetostatic coupling force is relaxed. As a result, even when the interval between the convex portions is narrowed, the recording magnetic domains adjacent to each other are coupled with a strong magnetostatic coupling force, and it is possible to prevent the difficulty in recording with an external magnetic field. Play.

  In the information recording medium according to the present invention, the information recording layer is preferably made of an optical recording material.

  According to the above configuration, the information recording medium can be used as an optical information recording medium suitable for optical information recording. In other words, the information recording medium having the above configuration is capable of high density and recording without increasing the power consumption of the light source. There is an effect that it can be utilized as an optical information recording medium in which the time required is shortened.

  An information recording / reproducing apparatus that records information on an information recording medium in which the information recording layer is made of a magnetic material or an information recording medium in which the information recording layer is made of an optical recording material and reproduces information from the recording medium also falls within the scope of the present invention. include.

  The information recording / reproducing apparatus according to the present invention further includes near-field light generating means for generating near-field light between the light source and the information recording medium and on the light path. Is preferred.

  According to said structure, the size of the light irradiated to an information recording medium can be made small below a wavelength size. As a result, the information recording layer can be more easily heated, so that the time required for information recording can be further shortened.

  Furthermore, a heating process of irradiating the information recording medium whose information recording layer is made of a magnetic material to heat the information recording area of the information recording medium, and a magnetic field applying process of applying a magnetic field to the information recording area The information recording method including the above is also included in the category of the present invention.

  Furthermore, an information recording method including a heating step of irradiating an information recording medium in which the information recording layer is made of an optical recording material and heating an information recording area of the information recording medium is also included in the scope of the present invention.

  Furthermore, an information reproducing method including a leakage magnetic field detection step of detecting a leakage magnetic field generated from an information recording medium whose information recording layer is made of a magnetic material is also included in the scope of the present invention.

  Furthermore, an information reproducing method including a light amount detection step of detecting the amount of reflected light reflected from an information recording medium whose information recording layer is made of an optical recording material is also included in the scope of the present invention.

  Also, a layer formed directly or indirectly on the substrate and continuously formed in the in-plane direction of the substrate, and forming an information recording layer having a plurality of convex portions, adjacent to the step A method of manufacturing an information recording medium including a step of forming a metal body via a dielectric between the convex portions is also included in the scope of the present invention.

  As described above, the information recording medium according to the present invention is formed on the information recording layer that is continuous in the in-plane direction of the substrate, and a metal body is interposed between the adjacent convex portions via a dielectric. Is provided.

  As a result, the recording density of the information recording medium can be increased and the time required for recording can be shortened (that is, the recording speed can be increased) without increasing the power consumption of the light source.

Embodiment 1
An embodiment of an information recording medium according to the present invention will be described below with reference to FIGS.

(Configuration of information recording medium 1a)
The configuration of the information recording medium 1a according to the present embodiment will be described below with reference to FIGS. 1 and 2 (a) to (c). FIG. 1 is a schematic cross-sectional view showing the configuration of the information recording medium 1a. 2A to 2C are plan views showing the configuration of the information recording medium 1a. FIG. 2A is a plan view taken along the line AA 'in FIG. 1, and FIG. It is a top view, (c) is a top view in CC 'of FIG.

  As shown in FIGS. 1 and 2 (a) to 2 (c), the information recording medium 1 a includes a substrate 11, a recording layer (information recording layer) 12, a dielectric 13, a metal body 14, and a protective layer 15. The recording head 70 shown in FIG. 1 is not a member constituting the information recording medium 1a, but is shown in FIG. 1 for convenience in order to facilitate understanding of the present invention.

  The information recording medium 1a records various information in the recording layer 12. More specifically, information is recorded in the region of the convex portion 12 a in the recording layer 12.

  Each member constituting the information recording medium 1a will be described below.

(Substrate 11)
The substrate 11 holds the recording layer 12 and the like formed thereon without being deformed, and has a plurality of convex portions 11a on the surface thereof.

  A plurality of convex portions 11 a are provided on the surface of the substrate 11. The convex portion 11a is reflected in the shape of the recording layer 12 (and the shape of the dielectric 13) to be formed later. In the present specification and the like, even if the substrate 11 and the convex portion 11a are made of different materials, the convex portion 11a is a part of the substrate.

(Recording layer 12)
The recording layer 12 is a layer made of a recording material that records and holds information. As shown in FIG. 1, the recording layer 12 is formed continuously in the in-plane direction of the substrate. That is, the recording layer 12 is formed as a continuous layer without being separated from each other by the dielectric 13 and the metal body 14.

  The recording layer 12 is provided with a convex portion 12 a so as to follow the shape of the convex portion 11 a on the substrate 11. That is, as shown in FIG. 1, the shape of the recording layer 12 is a shape along the surface shape of the substrate 11. Note that the shape of the recording layer 12 may not be along the surface shape of the substrate 11. The description of the case where the shape of the recording layer 12 is not along the surface shape of the substrate 11 will be described in the section of a modification of the information recording medium 1a.

(Dielectric 13)
The dielectric 13 is formed on the recording layer 12 to protect the recording layer 12 and to generate localized plasmons at the interface with the metal body 14 with high efficiency.

(Metal body 14)
The metal body 14 is provided via the dielectric 13 between the adjacent convex portions 12a. The metal body 14 is provided in order to generate localized plasmons at the interface with the dielectric 13 when the information recording medium 1a is irradiated with light.

(Protective layer 15)
The protective layer 15 is provided to protect the recording layer 12, the dielectric 13, and the metal body 14. A lubricating layer may be further provided on the protective layer 15 to prevent damage to the information recording medium 1a due to contact with the recording head 70 or an optical pickup.

(Recording head 70)
Finally, the configuration of the recording head 70 shown in FIG. 1 will be described below. As shown in FIG. 1, the recording head 70 includes a near-field light generating member 73, a condenser lens 74, and a light source 75. The generation of the near-field light 72 will be described in detail below.

  Specifically, the near-field light 72 is generated when the laser light 71 emitted from the light source 75 and passed through the condenser lens 74 passes through the near-field light generating member 73. The generated near-field light 72 is applied to the information recording medium 1a. The laser light 71 does not necessarily pass through the condenser lens 74, and the light emitted from the light source 75 may directly reach the near-field light generating member 73.

  As the near-field light generating member 73, a conventionally known one can be used. Specific examples include a metal plate or metal thin film in which a microscopic aperture smaller than the wavelength of the laser light source is formed, an optical waveguide or optical probe, a scatterer, and an electromagnetic field generating element.

  Note that the use of the near-field light generating member 73 is not indispensable when recording / reproducing information on the information recording medium according to the present invention. That is, the light emitted from the light source 75 may be directly irradiated onto the information recording medium 1 a through the condenser lens 74. At this time, the condenser lens 74 may be a single lens or a group lens in which a plurality of lenses are combined.

(Operational effect of information recording medium 1a)
In the information recording medium 1a, a metal body 14 is provided between adjacent convex portions 12a with a dielectric 13 interposed therebetween. As a result, plasmons are generated at the interface between the dielectric 13 and the metal body 14 when the near-field light 72 (laser light 71 when propagating light is used) is irradiated. A strong electric field concentration is caused at the interface with 14. As described above, in the information recording medium 1a, the concentration of the electric field can be caused inside the information recording medium 1a. Therefore, a desired location (location where information is recorded) of the recording layer 12 can be heated from the inside. That is, since the information recording portion in the recording layer 12 can be efficiently heated, the information recording speed can be increased without increasing the intensity of the near-field light 72 (laser light 71).

  In addition, the plasmon converted from the light emitted from the light source 75 selectively propagates and localizes at the interface between the dielectric 13 and the metal body 14, and therefore, a location where information is to be recorded in the recording layer 12. The concentration of the electric field can be caused only in the vicinity of the. Thereby, since the local heating in the information recording medium 1a can be performed, information can be recorded with high density.

  Here, “plasmon” in this specification and the like refers to a kind of electron density wave generated at the metal-dielectric interface. The plasmon converted from the near-field light (or laser light) propagates through the interface between the metal and the dielectric, and becomes a local plasmon in a localized state at a portion where the shape of the interface changes. This causes an electric field concentration and local plasmons are converted into heat.

  Moreover, the information recording medium 1a can form the metal body 14 inside the information recording medium 1a. Thereby, since the surface of the information recording medium 1a can be kept smooth, the recording / reproducing head can be brought close to the information recording medium 1a to perform recording / reproducing. Therefore, information can be recorded with high density.

  Furthermore, in the information recording medium 1 a, the recording layer 12 is provided as a continuous layer without being separated by the dielectric 13 and the metal body 14. Accordingly, the region surrounded by the metal body 14 can be heated locally and strongly, so that a minute recording region can be formed in the information recording medium 1a.

  When the recording layer 12 is made of a magnetic material, the information recording medium 1a can function as a patterned medium. In this case, the convex portions 12a of the recording layer 12 are connected by a magnetic material having a weak magnetic anisotropy. As a result, the convex portions 12a generate a weak exchange coupling force, so that the magnetostatic coupling force is relaxed. Therefore, even when the interval between the convex portions 12a is narrowed, that is, when the recording medium 1a is a high-density recording medium, adjacent recording magnetic domains are coupled with a strong magnetostatic coupling force, and recording by an external magnetic field is performed. Can be prevented from becoming difficult.

(Details of substrate 11)
The material and shape of the substrate 11 are not particularly limited as long as each layer such as the recording layer 12 can be held without being deformed.

  As a material of the substrate 11, for example, a metal, an oxide, a nitride, a semiconductor, a resin, or the like can be used. More specifically, silicon dioxide, aluminum coated with nickel phosphide, polycarbonate and the like can be mentioned. In addition, since the recording medium 1a is generally circular, the substrate 11 is preferably circular. However, shapes other than circular may be used.

(Details of convex portion 11a)
The convex portion 11a may be made of the same material as the substrate 11, or may be made of a different material. Moreover, the convex part 11a may be formed by adhering on the board | substrate 11, and may be formed by shaving the board | substrate 11. FIG.

  Further, the cross-sectional shape of the convex portion 11a may be a shape having a curvature as shown in FIGS. 1 and 2 (a) to (c), or may be a rectangular shape or a shape close thereto. Furthermore, the shape when viewed from the top is not particularly limited, such as a circle (the convex portion 11a is a columnar shape), a rectangle (the convex portion 11a is a quadrangular prism shape), or a hexagon. The case where the cross-sectional shape of the convex portion 11a is not semicircular is shown in FIGS.

  The height of the convex portion 11a with respect to the surface of the substrate 11 (that is, the distance between the apex and the bottom portion of the convex portion 11a) is preferably 5 nm or more. This is to obtain the thickness of the metal body 14 formed between the convex portions 12 a in the recording layer 12.

(Details of recording layer 12)
The material of the recording layer 12 is not particularly limited, and can be appropriately set according to the type of the information recording medium 1a. For example, when the information recording medium 1a is a magnetic recording medium, the recording layer 12 is made of a magnetic material. In addition, the recording layer 12 is made of an optical recording medium twice as long as the information recording medium 1a is an optical recording medium.

  When the recording layer 12 is made of a magnetic material, the magnetic material is preferably made of, for example, a ferromagnetic material, a ferrimagnetic material, or a laminated film thereof. Of these laminated films, a perpendicular magnetization film having an easy axis in the direction perpendicular to the substrate surface is more preferable from the viewpoint of high density recording. More specifically, cobalt-chromium-platinum alloy, cobalt-chromium-platinum-boron alloy, cobalt-platinum alloy, cobalt-nickel-platinum alloy, iron-platinum alloy, iron-nickel-platinum alloy, terbium-iron alloy Terbium-iron-cobalt alloy, dysprosium-iron alloy, or dysprosium-iron-cobalt alloy. Further, a ferromagnetic material or a ferrimagnetic material mainly composed of these alloys may be used.

  When the recording layer 12 is made of an optical recording material, examples of the optical recording material include phases such as a bismuth-germanium alloy, an antimony-tellurium alloy, a germanium-antimony-tellurium alloy, an indium-antimony-tellurium alloy, and a germanium-antimony-tellurium alloy. Mention may be made of changing materials. The optical recording material may be a material mainly composed of these alloys. Of course, the optical recording material is not limited to the phase change material, and may be a write-once material. Examples of the write-once material include a silicon-copper alloy, an aluminum-copper alloy, or a material mainly composed of these. That is, the optical recording material is not particularly limited as long as it is a material applied to a recording material for a rewritable or write once optical disc.

  When the recording layer 12 is made of a magnetic material, a soft magnetic material layer (not shown) may be formed between the recording layer 12 and the substrate 11 (or the protrusion 11a). The soft magnetic layer is also referred to as a SUL (Soft Underlayer), and enhances the magnetic field in a direction perpendicular to the surface of the substrate 11 when an external magnetic field is applied to the recording layer 12 to assist recording. Is a layer. Examples of the material for the soft magnetic layer include a nickel-iron alloy, a nickel-iron-tantalum alloy, a cobalt-zirconium alloy, or a soft magnetic material mainly composed of these alloys. When the soft magnetic layer is formed, the convex portion 11a may not be formed on the substrate 11, but may be formed on the surface of the soft magnetic layer with the same or different material as the soft magnetic layer.

(Details of dielectric 13)
Examples of the material of the dielectric 13 include transparent dielectric materials represented by silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride, magnesium oxide, magnesium fluoride, and gallium nitride.

  From the viewpoint of bringing the recording head 70 and the recording layer 12 as close as possible, if the recording layer 12 can be protected only by the protective layer 15, the dielectric 13 should be formed only at a location in contact with the metal body 14. Good. That is, it does not have to be formed on the convex portion 12 a of the recording layer 12. In this case, the information recording medium 1a has a configuration in which the recording layer 12 and the protective layer 15 are in contact with each other.

  The thickness of the dielectric 13 is particularly preferably in the range of 2 nm or more and 30 nm or less. When the thickness of the dielectric 13 is 2 nm or more, electric field concentration can be caused at the interface between the metal body 14 and the dielectric 13. The upper limit of the width of the dielectric 13 is not particularly limited, but is preferably 30 nm or less in consideration of the distance that the near-field light 72 reaches the recording layer 12.

(Details of metal body 14)
As a material of the metal body 14, it is preferable to use gold, silver, aluminum, platinum, or an alloy mainly composed of at least one of these metals from the viewpoint of increasing the plasmon generation efficiency. Since these metals have high plasmon generation efficiency, plasmons can be efficiently generated at the interface with the dielectric 13.

  When gold or an alloy mainly composed of gold is used as the material of the metal body 14, strong electric field concentration can be obtained by using a light source that generates laser light having a wavelength of about 600 nm to 1.5 μm as the light source 75. Can cause. When silver, aluminum, platinum, or an alloy mainly composed of these metals is used as the material of the metal body 14, a strong electric field concentration can be obtained by using a light source that generates a short-wavelength laser beam of 600 nm or less as the light source 75. Can cause.

Moreover, it is preferable that the length (henceforth, width) in the direction parallel to the board | substrate 11 surface of the metal body 14 is the range of 2 nm or more and 50 nm or less. When the width of the metal body 14 is 2 nm or more, electric field concentration can be caused at the interface between the metal body 14 and the dielectric 13. The upper limit of the width of the metal body 14 is not particularly limited, but is preferably 50 nm or less when used in a high-density information recording medium having a surface density of about 1 Tbit / inch ² . When the width of the metal body 14 is not uniform, the maximum width is preferably in the above range.

  The length (hereinafter, thickness) in the direction perpendicular to the surface of the substrate 11 of the metal body 14 is preferably in the range of 2 nm or more and 70 nm or less. When the thickness of the metal body 14 is 2 nm or more, electric field concentration can be caused at the interface between the metal body 14 and the dielectric 13. The upper limit of the thickness of the metal body 14 is not particularly limited, but as the aspect ratio of the metal body 14 increases, the thickness of the metal body 14 increases. When the thickness of the metal body 14 is increased, it takes a long time to polish (etch) the metal body 14. For this reason, the thickness of the metal body 14 is desirably about 70 nm or less.

(Details of protective layer 15)
Examples of the material of the protective layer 15 include a smooth material as typified by diamond-like carbon (DLC), and a material having a high protective effect such as a hard thin film or a photo-curing resin.

(Method of manufacturing information recording medium 1a)
Next, a method for manufacturing the information recording medium 1a will be described below with reference to FIGS. 3 (a) to 3 (d). FIGS. 3A to 3D are views showing a method for manufacturing the information recording medium 1a. FIG. 3A shows the formation of the convex portion 11a on the substrate 11, and FIG. 3B shows the recording layer. 12 shows the formation of the dielectric 13 and the metal body 14, (c) shows the partial removal of the metal body 14, and (d) shows the formation of the protective layer 15.

  The manufacturing method of the information recording medium 1a mainly includes a dielectric 13 and a metal between the step of forming a recording layer 12 having a plurality of convex portions 12a and continuously provided and the adjacent convex portions 12a. Providing a body 14. Details of the method of manufacturing the information recording medium 1a including these steps will be described in detail below.

(Preparation of convex part 11a)
In the information recording medium 1a, the uneven shape in the recording layer 12 is realized by forming the recording layer 12 along the shape of the convex portion 11a. That is, the uneven shape in the information recording medium 1a depends on the formation of the convex portion 11a in the substrate 11a.

  The formation of the convex portion 11a on the substrate 11 is shown in FIG. The formation method of the convex part 11a will not be specifically limited if uneven | corrugated shape can be formed on the board | substrate 11. FIG. For example, the substrate 11 may be formed by etching using a resist formed into a dot shape using electron beam lithography as a mask. Alternatively, a method using self-assembled molecules may be used, and island-formed metal, oxide, or nitride may be used as the convex portion 11a. Alternatively, a method of etching the substrate 11 using these as a mask material may be used. For the etching of the substrate 11, for example, an ion milling method or a reactive ion etching (RIE) method can be used. Alternatively, the convex portion 11a may be formed by processing the substrate 11 directly using FIB (Focused Ion Beam).

At this time, when the portion formed on the convex portion 12a of the recording layer 12 is used for recording information and information of one bit is recorded corresponding to each convex portion 12a, the diameter of the convex portion 11a is It is preferable that the distance is approximately 20 nm and the interval between the convex portions 11a is approximately 5 nm. As a result, the information recording medium 1a can be an information recording medium having a surface density equivalent to 1 Tbit / inch ² . Of course, the information recording medium 1a does not necessarily have to be a medium on which one bit is recorded corresponding to each convex portion 12a, and a recording bit may be formed across a plurality of convex portions 11a.

(Preparation of recording layer 12, dielectric 13 and metal 14)
Subsequently, as shown in FIG. 3B, the recording layer 12 is formed on the substrate 11 and the convex portion 11a by using a technique such as sputtering or vapor deposition. At this time, since the shape of the recording layer 12 is formed along the substrate 11 and the convex portion 11a, the recording layer 12 in the region where the convex portion 11a is formed becomes a convex portion, and the convex portion 11a is formed. The recording layer 12 in the non-existing region becomes a recess. That is, the convex part 12a in the recording layer 12 is formed.

  And while forming the dielectric 13 between the adjacent convex parts 12a, the metal body 14 is formed. At this time, the metal body 14 is formed via the dielectric 13. The dielectric 13 and the metal 14 can also be formed by the same method as that for the recording layer 12.

  Subsequently, as shown in FIG. 3C, the surface is flattened until at least a part of the dielectric 13 appears on the surface of the information recording medium 1a. Thereby, the metal body 14 formed on the convex part 12a is scraped off. This step can be realized by, for example, polishing by CMP (Chemical Mechanical Polishing), reverse sputtering using a sputtering apparatus, or ion milling.

(Preparation of protective layer 15)
Finally, as shown in FIG. 3D, the protective layer 15 is formed. Thereby, the information recording medium 1a is completed. In addition, you may make it form a lubricating layer as needed.

(Function and effect of manufacturing method)
Thus, in the manufacturing method of the information recording medium 1a, since the convex part 12a of the recording layer 12 can be formed in the form which follows the shape of the board | substrate 11 and the convex part 11a, it was required in the conventional manufacturing method. Steps such as air exposure to the surface of the recording layer 12 and etching after the recording layer 12 is formed can be avoided. For this reason, it is possible to prevent the original characteristics of the recording layer 12 from being impaired. Further, as the material of the recording layer 12, a material that is easily oxidized or nitrided can be applied.

(Information recording method of information recording medium 1a)
Next, a method for recording information in the information recording medium 1a will be described below. The information recording medium 1a according to the present embodiment may be recorded using the near-field light 72, or may be recorded using propagating light (laser light 71) without using the near-field light generating member 73. It may be. In the present embodiment, a method for recording information on the information recording medium 1a by using the near-field light 72 will be described. Note that the phenomenon occurring inside the recording medium is the same when propagating light (laser light 71) is used.

(When the information recording medium 1a is a magnetic recording medium)
When the information recording medium 1a is a magnetic recording medium, the recording method for the information recording medium 1a mainly includes a heating step of heating the recording layer 12 by irradiating the near-field light 72 to the information recording medium 1a. And a magnetic field applying step of applying a magnetic field to the information recording medium 1a.

(Heating process)
As described above, the near-field light 72 is generated by the laser light 71 passing through the near-field light generating member 73. The generated near-field light 72 is applied to the information recording medium 1a. Thereby, the recording layer 12 in the irradiated region is heated. More specifically, when the near-field light 72 is irradiated, plasmons are generated at the interface between the dielectric 13 and the metal body 14, causing a strong electric field concentration. Due to the concentration of the electric field, heat is generated inside the information recording medium 1a.

(Magnetic field application process)
When the recording layer 12 is heated, the coercive force of the magnetic material forming the recording layer 12 decreases to approach the Curie temperature. At this time, the magnetization of the recording layer 12 can be reversed by applying an external magnetic field exceeding the coercive force of the recording layer 12 in the heated region to the information recording medium 1a. Thereby, information can be recorded on the information recording medium 1a.

(When the information recording medium 1a is an optical information recording medium)
When the information recording medium 1a is an optical information recording medium, the recording method for the information recording medium 1a mainly includes a heating step of heating the recording layer 12 by irradiating the information recording medium 1a with near-field light 72. Including. Since the heating process is the same as that of the magnetic recording medium, a detailed description thereof is omitted. Specifically, in the case of an optical information recording medium, a state where the heated recording layer 12 has a reflectivity different from that of an unheated region due to phase change or new generation of a compound. To change. Thereby, information can be recorded on the information recording medium 1a.

(Modification of information recording medium 1a)
Modified examples of the information recording medium 1a are shown in FIGS. 4 to 6 are schematic cross-sectional views showing configurations of modified examples of the information recording medium 1a.

(Shape of convex part 11a)
Although the case where the cross-sectional shape of the convex part 11a is a semicircle shape is illustrated above, it is not limited to this. For example, as shown in FIG. 4, the cross-sectional shape of the convex portion 11a may be rectangular, or may be trapezoidal as shown in FIG.

  Even when the cross-sectional shape of the convex portion 11a is variously changed as shown in FIGS. 4 and 5, the same effect can be obtained by the same operation as that of the information recording medium 1a shown in FIG.

(When the convex portion 11a is not provided)
FIG. 6 is a schematic cross-sectional view showing the configuration of the information recording medium 1 b in which the convex portion 11 a is not provided on the substrate 11. As shown in FIG. 6, if the convex part 12a is formed in the recording layer 12, the convex part 11a is not necessarily required in the information recording medium 1a.

  If a plurality of convex portions 12 a are formed on the recording layer 12, the metal body 14 can be formed in the concave portion between the adjacent convex portions 12 a through the dielectric 13. Therefore, even the information recording medium 1b shown in FIG. 6 can achieve the same effects as the information recording medium 1a shown in FIG.

  Even when the convex portion 11a is not provided, the shape and size of the convex portion 12a are the same as the shape and size of the convex portion 11a. That is, the shape of the convex portion 12a is not particularly limited, and the height of the convex portion 12a is preferably 5 nm or more.

(Method of manufacturing information recording medium 1b)
A method for manufacturing the information recording medium 1b when the convex portion 11a is not provided on the substrate 11 will be described below with reference to FIG. 7A and 7B are diagrams showing a method of manufacturing the information recording medium 1b, in which FIG. 7A shows the formation of the recording layer 12, FIG. 7B shows the formation of the mask portion 20, and FIG. 7C shows the recording. 5 shows etching of the layer 12, (d) shows formation of the dielectric 13 and the metal body 14, (e) shows grinding of the metal body 14, and (f) shows formation of the protective layer 15. Is shown.

  First, as shown in FIG. 7A, after the recording layer 12 is formed on the substrate 11, the mask portion 20 is formed as shown in FIG. 7B. The mask part 20 can be formed by the same method as the formation of the convex part 11a. Subsequently, as shown in FIG. 7C, the recording layer 12 is etched using an ion milling method or a reactive ion etching (RIE) method. At this time, the mask portion 20 serves as a mask for etching. After the etching, the mask portion 20 remaining on the surface is removed as necessary to obtain the convex portion 12a.

  Next, after forming the dielectric 13 and the metal body 14 as shown in FIG. 7D, at least a part of the dielectric 13 is formed on the surface of the information recording medium 1b as shown in FIG. 7E. The metal body 14 is scraped off while the surface is flattened until it appears. Similar to the method shown in FIG. 3C, this step can be realized by polishing by CMP (Chemical Mechanical Polishing), reverse sputtering using a sputtering apparatus, or ion milling. Finally, as shown in FIG. 7F, the protective layer 15 is formed to complete the information recording medium 1b. In addition, you may apply | coat and form a lubricating layer as needed.

(Additional notes)
In the information recording medium 1a, the layer thickness of the recording layer 12 between adjacent convex portions 12a, that is, the thickness of the concave portion in the recording layer 12, is determined by the shadowing (shielding) effect at the time of film formation. Thinner. In addition, when the recording layer 12 is made of a magnetic material having perpendicular magnetization, the recording layer 12 formed on the inclined surface of the convex portion 11 a has the easy axis direction of magnetization inclined toward the in-plane direction of the substrate 11. Yes. That is, the magnetic anisotropy in the direction perpendicular to the substrate surface of the recording layer 12 formed on the slopes of the concave and convex portions 11a in the recording layer 12 is reduced.

  Therefore, when the region of the convex portion 12a of the recording layer 12 is used as a recording region, since the coupling between the adjacent convex portions 12a is weakened, it is easy to cause independent magnetization reversal for each convex portion 12a. That is, the recording layer 12 is a layer formed continuously, but can form magnetic bits in units of individual convex portions 12a.

  In the information recording medium 1a, the positional relationship between the protrusions 11a formed on the substrate 11 is arranged in both the vertical direction and the horizontal direction as shown in FIGS. It does not have to be. The arrangement may be arranged only in the vertical direction or the horizontal direction, may be arranged randomly, or there may be a portion where the convex portion 11a does not exist partially. Further, the size of the convex portions 11a may not be uniform.

[Embodiment 2]
Another embodiment of the information recording medium according to the present invention will be described below with reference to FIGS. 8 and 9 (a) to (c). In addition, about the member similar to Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

(Configuration of information recording medium 1c)
The configuration of the information recording medium 1c according to this embodiment will be described with reference to FIGS. 8 and 9 (a) to (c). FIG. 8 is a schematic cross-sectional view showing the configuration of the information recording medium 1c. 9A to 9C are plan views showing the configuration of the information recording medium 1c. FIG. 9A is a plan view taken along the line AA 'in FIG. 8, and FIG. 9B is a view taken along line BB' in FIG. It is a top view, (c) is a top view in CC 'of FIG.

  As shown in FIGS. 8 and 9 (a) to 9 (c), the information recording medium 1 c includes a substrate 11, a recording layer 12, a dielectric 13, a metal body 14, and a protective layer 15. The substrate 11 is provided with a convex portion 11a, and the recording layer 12 is formed along the shape of the convex portion 11a. That is, a plurality of convex portions 12a are formed on the recording layer 12 where the convex portions 11a are formed. Since these members have been described in detail in the first embodiment, the description thereof is omitted here. As in FIG. 1, the recording head 70 does not constitute the information recording medium 1c, but is shown in FIG. 8 for convenience in order to facilitate understanding of the present invention.

  As shown in FIG. 9A, the information recording medium 1c according to the present embodiment is provided by separating the metal body 14 into a plurality of parts around the convex part 11a (in other words, around the convex part 12a). It has been. In other words, the metal body 14 is provided discretely around the convex portion 12a.

  Even when the metal body 14 is provided discretely around the convex portion 12a, the metal body 14 is interposed between the adjacent convex portions 12a via the dielectric 13 as shown in FIG. Can be formed.

  Although the metal body 14 is not illustrated in FIG. 8, this is a cross-sectional view at a position where the height of the convex portion 11 a is the highest, so that the metal bodies are provided discretely. This is because 14 does not appear in the cross section. If it is sectional drawing in the position where the height of the convex part 11a is low, the metal body 14 will appear like the sectional view shown in FIG.

(Operational effect of information recording medium 1c)
Even in the case where the metal body 14 is provided discretely around the convex portion 12a as in the information recording medium 1c, the irradiation of the near-field light 72 (the laser light 71 when using propagating light) is performed. At this time, strong electric field concentration can be caused at the interface between the dielectric 13 and the metal 14. Therefore, a desired portion of the recording layer 12 can be heated from the inside in the information recording medium 1c.

  As a result, as with the information recording medium 1a, the recording density can be increased and the information recording speed can be increased without increasing the power consumption of the light source 75.

  In the information recording layer 1c, plasmons generated at the interface between the metal body 14 and the dielectric 13 are confined for each metal body 14 provided in a divided manner. This can cause a very high electric field concentration at the interface between the metal body 14 and the dielectric 13. That is, the convex portion 12a, which is a region surrounded by the metal body 14 where electric field concentration has occurred, can be heated extremely strongly locally.

  Therefore, a minute recording area can be formed in the information recording medium 1c, and the power consumption of the light source 75 can be reduced. If the recording layer 12 is made of a magnetic material, the information recording medium 1c can function as a patterned medium.

(Method of manufacturing information recording medium 1c)
A method for manufacturing the information recording medium 1c will be described below. The information recording medium 1c can be manufactured by substantially the same manufacturing method as the information recording medium 1a described above. Therefore, in the present embodiment, only differences from the method for manufacturing the information recording medium 1a will be described below.

  The information recording medium 1c is manufactured by making the film thickness of the metal body 14 thinner than that for manufacturing the information recording medium 1a in the process of forming the metal body 14 (that is, the process shown in FIG. 3B). be able to.

  Further, in the step of polishing, etching or ion milling the metal body 14 (that is, the step shown in FIG. 3D), the metal body 14 can also be manufactured by increasing the time of polishing, etching or ion milling. More specifically, the metal body 14 formed in the shallow region of the recess is scraped out of the metal body 14 formed via the dielectric 13 formed in the recess between the adjacent protrusions 12a. Polish or etch until removed. As a result, the information recording medium 1c in which the metal bodies 14 around the convex portions 12a are discrete can be obtained.

  When the polishing or etching time is lengthened, it is preferable to make the dielectric 13 thicker than the case where the information recording medium 1a is manufactured in order to prevent the recording layer 12 from being scraped off. .

[Embodiment 3]
Another embodiment of the information recording medium according to the present invention will be described below with reference to FIGS. 10 and 11 (a) and (b). In addition, about the member similar to Embodiment 1 and 2, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

(Configuration of information recording medium 1d)
The configuration of the information recording medium 1d according to the present embodiment will be described with reference to FIGS. 10 and 11 (a) and (b). FIG. 10 is a schematic cross-sectional view showing the configuration of the information recording medium 1d. 11 (a) and 11 (b) are plan views showing the configuration of the information recording medium 1d, (a) is a plan view taken along the line AA 'in FIG. 10, and (b) is in BB' in FIG. It is a top view.

  As shown in FIGS. 10 and 11 (a) and 11 (b), the information recording medium 1 d includes a substrate 11, a recording layer 12, a dielectric 13, a metal body 14, and a protective layer 15. Further, the substrate 11 has a convex portion 11a formed continuously in the track length direction of the information recording medium 1d, and the recording layer 12 is formed along the shape of the convex portion 11a. That is, the convex portion 12a is formed on the recording layer 12 at the position where the convex portion 11a is formed. Since these members have been described in detail in the first and second embodiments, the description thereof is omitted here. 1 and 8, the recording head 70 does not constitute the information recording medium 1d, but is shown in FIG. 10 for the sake of convenience in order to facilitate understanding of the present invention.

(Operational effect of information recording medium 1d)
Thus, even if the convex portion 11a is formed continuously in the track length direction of the information recording medium 1d, as shown in FIGS. 10 and 11 (a) and (b), the adjacent convex portion A metal body 14 can be formed between the portions 12 a via the dielectric 13. Therefore, a strong electric field concentration can be caused at the interface between the dielectric 13 and the metal body 14 upon irradiation with the near-field light 72 (laser light 71 when propagating light is used). Therefore, a desired portion of the recording layer 12 can be heated from the inside in the information recording medium 1c.

  As a result, as in the information recording medium 1a, the recording density of the information recording medium 1d can be increased and the information recording speed can be increased without increasing the power consumption of the light source 75.

  Further, in the information recording medium 1d, the convex portion 12a that is a region sandwiched between the metal bodies 14 can be locally heated strongly. Thereby, a minute recording area can be formed in the information recording medium 1d. In the case where the recording layer 12 is made of a magnetic material, the information recording medium 1d can function as a discrete track medium.

(Method of manufacturing information recording medium 1d)
A method for manufacturing the information recording medium 1d will be described below. The information recording medium 1d can be manufactured by substantially the same manufacturing method as the above-described information recording medium 1a. Therefore, in the present embodiment, only differences from the method for manufacturing the information recording medium 1a will be described below. Therefore, only the process of forming the convex part 11a is demonstrated here.

  In the manufacture of the information recording medium 1d, in the process of FIG. 3A, the convex portions 11a are continuously formed in the track length direction of the information recording medium 1d. At this time, the convex portion 11a continuously formed in the track length direction can be formed by etching the substrate 11 using, for example, a resist formed in a linear shape by electron beam lithography as a mask. . For the etching of the substrate 11, for example, an ion milling method or a reactive ion etching (RIE) method can be used.

  Further, the substrate 11 may be directly processed by FIB (Focused Ion Beam) to form the convex portion 11a continuously formed in the track length direction.

In the information recording medium 1d, in order to make the surface density equivalent to 1 Tbit / inch ² , for example, the pitch of the convex portions 11a is set to 25 nm. Of course, the information recording medium 1d does not necessarily have to record bits between the adjacent convex portions 11a, and the recording bits may be formed across the plurality of convex portions 11a.

  As described above, in the information recording medium 1d, similarly to the manufacturing method of the information recording medium 1a, after exposure to the atmosphere on the surface of the recording layer 12 or deposition of the recording layer 12, which is required in the conventional manufacturing method of discrete media. Therefore, the damage (damage) to the recording layer 12 can be reduced. Further, as the material of the recording layer 12, a material that is easily oxidized or nitrided can be applied.

(Modification of information recording medium 1d)
In the information recording medium 1d, when the recording layer 12 is made of a magnetic material, a soft magnetic material layer (not shown) may be formed between the recording layer 12 and the substrate 11 (or the convex portion 11a). When the magnetic layer is formed, the protrusion 11a may not be formed on the substrate 11, but may be formed on the surface of the soft magnetic layer with the same or different material as the soft magnetic layer.

(Additional notes)
In the information recording medium 1d, the thickness of the recording layer 12 between adjacent convex portions 12a, that is, the thickness of the concave portion in the recording layer 12, is determined by the shadowing (shielding) effect during film formation. Thinner. In addition, when the recording layer 12 is made of a magnetic material having perpendicular magnetization, the recording layer 12 formed on the inclined surface of the convex portion 11 a has the easy axis direction of magnetization inclined toward the in-plane direction of the substrate 11. Yes. That is, the magnetic anisotropy in the direction perpendicular to the substrate surface of the recording layer 12 formed on the slopes of the concave and convex portions 11a in the recording layer 12 is reduced.

  Therefore, when the region of the convex portion 12a of the recording layer 12 is used as a recording region, the coupling between the adjacent convex portions 12a is weakened, and thus the magnetic coupling force between the adjacent convex portions 12a is also weakened. . Therefore, the magnetic coupling force between adjacent tracks can be cut off even though the recording layer 12 is a continuous layer. As a result, the track width can be narrowed, so that the recording medium 1d can be a discrete track medium-like magnetic recording medium.

  The information recording medium 1 d may be provided with a guide groove for tracking on the substrate 11. In the information recording medium 1d, particularly when the guide groove and the region where the metal body 14 is formed, the guide groove and the near-field light generating member are formed without reducing the information recording region. And can be made possible.

  In order to realize such an information recording medium 1d, when forming the convex portion 11a, the convex portion 11a has a height necessary for embedding the metal body 14 in the concave portion between the adjacent convex portions 12a, and It is necessary to form the guide groove at a height (depth) that is combined with the height (depth) of the guide groove. This can be realized, for example, by lengthening the etching time when forming the convex portion 11a using an etching process using a resist as a mask.

  Note that the guide grooves as described above can also be formed in the information recording media 1a, 1b, and 1c described in the first and second embodiments.

[Embodiment 4]
Information recording / reproducing apparatus for recording information on the information recording media according to the first to third embodiments (that is, optically assisted magnetic recording media) in which a magnetic material is applied to the recording layer 12 and reading information from the information recording media Embodiment 4 will be described below. In addition, about the member similar to Embodiment 1-3, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

(Configuration of information recording / reproducing apparatus 500)
The configuration of the information recording / reproducing apparatus 500 will be described below with reference to FIG. FIG. 12 is a block diagram showing the configuration of the information recording / reproducing apparatus 500.

  The information recording / reproducing apparatus 500 includes a magnetic recording / reproducing head 501, a slider 502, a magnetic disk 503, a spindle 506, a suspension arm 507, a voice coil motor 508, and a control unit 509.

  The magnetic disk 503 is a disk using a magnetic material for the recording layers 12 of the information recording media 1a to 1d described in the first to third embodiments.

  The spindle 506 rotates the magnetic disk 503. The slider 502 is supported by a suspension arm 507, and the suspension arm 507 is driven on the magnetic disk 503 by a voice coil motor 508. Conventionally known spindles 506, suspension arms 507, and voice coil motors 508 can be used. The magnetic recording / reproducing head 501 and the control unit 509 will be described in detail below.

(Magnetic recording / reproducing head 501)
The magnetic recording / reproducing head 501 is provided on the slider 502 and records / reproduces information on / from the information recording medium by an optically assisted recording method. That is, a laser light source for irradiating laser light, a magnetic field applying unit for applying a magnetic field to the information recording medium, and a magnetic field detecting unit for detecting a leakage magnetic field generated from the information recording medium are provided.

  A specific operation of the magnetic recording / reproducing head 501 will be described below. First, when the spindle 506 is rotated, the magnetic disk 503 is rotated to generate an air flow. Using the generated air flow, the slider 502 floats on the magnetic disk 503 by about 5 to 10 nm. Information is recorded by the magnetic recording / reproducing head 501 provided at the tip of the flying slider 502 irradiating the magnetic disk 503 with a light beam and applying a recording magnetic field. Information is reproduced by the magnetic field detection means provided in the magnetic recording / reproducing head 501 detecting the leakage magnetic field from the magnetic disk 503.

  As the magnetic recording / reproducing head 501 and the slider 502 provided with the magnetic recording / reproducing head 501, conventionally known ones can be used. The magnetic recording / reproducing head 501 includes a near-field light generating member 73, a light source 75, and a magnetic field applying unit (not shown), and irradiates the magnetic disk 503 with laser light 71 or near-field light 72 to generate a magnetic field. There is no particular limitation as long as it can be applied and includes magnetic field detection means (not shown) for detecting a leakage magnetic field from the magnetic disk 503. As the magnetic field application means, for example, a conventionally known magnetic coil or magnetic pole is used, and for the magnetic field detection means, for example, a conventionally known GMR (Giant Magneto Resistance) element or TMR (Tunneling Magneto Resistance) element is used. it can. The slider 502 may be a slider used in a conventional hard disk device. A conventionally known light source 75 can also be used. The near-field light generating member 73 is as described above in the first embodiment.

  Note that the light source 75 is not necessarily provided in the magnetic recording / reproducing head 501 as long as the laser light 71 is applied to the near-field light generating member 73. For example, the suspension arm 507 may be provided. Further, when the near-field light generating member 73 is irradiated with the laser beam 71, an optical waveguide or a grating shape may be used.

(Control unit 509)
As shown in FIG. 12, the control unit 509 includes a rotation drive control unit 510, a signal processing unit 511, an output control unit 512, and a recording unit 513, and includes a slider 502, a spindle 506, a suspension arm 507, and a voice. This is for controlling the operation of the coil motor 508.

  The rotation drive control unit 510 controls the rotation drive of the spindle 506. The rotation drive control at this time includes, for example, CAV (Constant Angular Velocity) control in which the rotation speed is constant regardless of the radial position of the magnetic recording / reproducing head 501, and the linear velocity according to the radial position of the magnetic recording / reproducing head 501. CLV (Constant Linear Velocity) control to change the rotation speed so that the constant is constant, ZCAV (Zoned CAV) control to control the rotation speed by dividing the track into zones, and the linear velocity is constant by dividing the track into zones ZCLV (Zoned CLV) control that changes the rotation speed can be used.

  In the case of CAV control, the rotational drive control unit 510 drives the spindle 506 at a predetermined rotational speed so that the rotational speed of the spindle 506 is constant. In the case of CLV control, the radial position of the magnetic recording / reproducing head 501 is detected, and the rotational speed is controlled accordingly. In the case of ZCAV control and ZCLV control, the zone position of the magnetic recording / reproducing head 501 is detected, and control is performed so that the rotational speed or linear velocity is constant according to this.

  The signal processing unit 511 transmits and receives signals to and from the magnetic recording / reproducing head 501. Specifically, it is as follows. At the time of recording, the recording information is encoded by the signal processing unit 511 so that the recording information is replaced with the light emission pattern of the laser beam emitted from the recording / reproducing head 501 to the magnetic disk 503 and the generation pattern of the magnetic field. Is sent to the recording / reproducing head 501. During reproduction, information detected by the magnetic recording / reproducing head 501 is extracted by the signal processing unit 511 as reproduction information.

  The output control unit 512 adjusts the output of the laser light emitted from the magnetic recording / reproducing head 501. In addition, the storage unit 513 stores information read from the magnetic disk 503, reference information for the signal processing unit 511 to determine the generation pattern of the laser beam and the generation pattern of the magnetic field, and the output control unit 512 outputs the output of the laser beam. This is a memory for storing reference information for determination.

(Operation of information recording / reproducing apparatus 500)
Next, recording and reproduction operations of the information recording / reproducing apparatus 500 will be described below.

  When the information recording / reproducing apparatus 500 is turned on, the magnetic recording / reproducing head 501 floats on the magnetic disk 503 as described above. Subsequently, when the magnetic recording / reproducing head 501 is energized, laser light 71 is emitted from the light source 75, and the emitted laser light 71 is applied to the near-field light generating member 73 to generate near-field light 72. To do. At this time, a recording magnetic field is emitted from the magnetic field generation source in accordance with the laser light 71 emitted from the light source 75. At this time, the output control unit 512 adjusts the power of the light source so that the coercive force of the area to be recorded on the recording layer 12 of the magnetic disk 503 is smaller than the recording magnetic field applied from the magnetic recording / reproducing head 501. As a result, the coercive force of the recording area of the recording layer 12 that is locally heated by the near-field light is smaller than the recording magnetic field, so that recording is performed on the magnetic disk 503.

  In addition, as described above, reproduction of recorded information on the magnetic disk 503 is performed by the magnetic field detection unit of the magnetic recording / reproducing head 501 detecting the leakage magnetic field from the magnetic disk 503. The detected leakage magnetic field is converted into an electric signal, whereby the recorded information on the magnetic disk 503 is reproduced.

  In this embodiment, only the recording / reproducing apparatus for the magnetic recording medium in which the magnetic material is applied to the recording layer 12 has been described. However, if an optical recording material is used for the recording layer 12, it can be used as an optical information recording medium. It is. In this case, as the information recording / reproducing apparatus, an optical information recording / reproducing apparatus capable of recording / reproducing with respect to a conventionally known optical information recording medium such as CD, DVD, BD, or the like manufactured using other known techniques. It becomes an information recording / reproducing apparatus. In these optical information recording / reproducing apparatuses, a part of the recording layer 12 of the information recording media 1a to 1d is heated by the irradiation of the laser beam 71 (near-field light 72), and the reflectance of the heated region changes. Information is recorded. When reproducing information, the information is reproduced by irradiating laser light 71 (near-field light 72) having a lower power than that during recording and detecting the amount of reflected light from the recording layer 12. In using these optical information recording / reproducing apparatuses, the protective layer 15 may be made of a transparent dielectric material or a resin material, and the thickness thereof may be appropriately changed according to the optical system of the recording / reproducing apparatus. Further, the laser beam 71 is not necessarily incident from the protective layer 15 side. When a transparent substrate is used as the substrate 11, the laser beam 71 may be incident from the substrate 11 side.

(Additional notes)
When a magnetic material is used for the recording layers 12 of the information recording media 1a to 1d described in Embodiments 1 to 3 and the information recording media 1a to 1d are used as optically assisted magnetic recording media, laser light is used as information during reproduction. An optically assisted reproduction system that irradiates the recording media 1a to 1d and detects a leakage magnetic field may be applied.

  In this case, since electric field concentration occurs in the information recording media 1a to 1d even during reproduction, optically assisted reproduction with a lower laser output than before is possible. Therefore, the power consumption of the light source 75 can be reduced, and the reproduction speed can be increased.

  The present invention has been specifically described above based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims and are different. Embodiments obtained by appropriately combining technical means disclosed in the respective embodiments are also included in the technical scope of the present invention.

  Hereinafter, an Example is shown and it demonstrates in more detail about the form of this invention. Of course, the present invention is not limited to the following examples, and various modes are possible for details.

[Example 1]
A method for measuring the electric field strength and the measurement result in the information recording medium 1a will be described below. The electric field strength was measured by simulating the information recording medium 1a when irradiated with a laser beam 71 having a wavelength of 680 nm by using an FDTD (Fine Difference Time Domain) method.

(Measurement method of electric field strength)
The following settings were made during the simulation. The intensity distribution of the laser beam 71 was a Gaussian distribution, and the spot diameter was 700 nm. The near-field light generating member 73 was a gold thin film with a thickness of 100 nm having a mortar-shaped minute opening (incident part diameter 400 nm, outgoing part diameter 20 nm). The distance between the near-field light generating member 73 and the information recording medium 1a was 5 nm. The incident light was deflected circularly, and the peak intensity (| E | ² ) of the electric field of the laser light was 1 (V / m) ² .

  In the information recording medium 1a used for the simulation, both the substrate 11 and the convex portion 11a are made of silicon dioxide, and the convex portions 11a are arranged at intervals of 25 nm. The height of the convex part 11a was 15 nm. The recording layer 12 was a cobalt-platinum alloy. The film thickness at the apex of the convex portion 11a was 10 nm. For the dielectric 13, silicon dioxide was used. The dielectric 13 was formed on the recording layer 12 with a film thickness of 7 nm. Gold was used for the metal body 14. The metal body 14 was formed to have a width of 7 nm and a height of 6 nm in the cross section shown in FIG. Note that the top of the dielectric 13 provided on the convex portion 11a was scraped in a range of 18 nm in width, and a carbon film was formed as the protective layer 15 with a film thickness of 5 nm.

(Measurement result of electric field strength)
The measurement result of the electric field intensity in the information recording medium 1a according to Embodiment 1 is shown in FIG. FIG. 13 is a diagram showing the electric field strength when the information recording medium 1a is irradiated with laser light in the cross section shown in FIG. Note that FIG. 13 is upside down from the schematic cross-sectional view shown in FIG. That is, the laser beam is irradiated from below in FIG.

  As shown in FIG. 13, it was confirmed that the near-field light was generated in the minute opening of the near-field light generating member 73 by the laser light irradiation and was irradiated to the recording layer 12 of the information recording medium 1a. . Furthermore, a local strong electric field concentration could be observed inside the information recording medium 1a in the vicinity of the interface between the metal body 14 and the dielectric 13 in the region irradiated with the near-field light 72.

As shown in FIG. 13, the electric field strength (| E | ² ) at the location where the electric field is concentrated is approximately the same as the electric field strength (50 (V / m) ² strength) at the exit portion of the minute aperture, It was strong.

  This is because the near-field light 72 applied to the surface of the information recording medium 1a is converted into plasmons inside the information recording medium 1a, more specifically, at the interface between the dielectric 13 and the metal body 14, and as an electric field, This is because it caused concentration. As a result, the information recording medium 1a can be heated from the inside, so that the portion of the recording layer 12 where information is to be recorded can be heated sufficiently efficiently while reducing the power consumption of the light source 75.

  FIG. 14 shows the measurement results of the electric field strength in the plane shown in FIG. As shown in FIG. 14, the electric field concentration at the interface between the dielectric 13 and the metal body 14 occurs so as to surround the convex portion 12a, and the recording layer 12 surrounded by the region where the electric field strength is strong is particularly heated. It became clear that information was easily recorded.

[Comparative Example 1]
The electric field strength of the information recording medium 101a having the same configuration as in Example 1 except that the metal body 14 is not replaced with the dielectric 13 in Example 1 by the same method as in Example 1. Was measured.

  FIG. 15 shows the measurement result of the electric field strength in the cross section corresponding to FIG. 1 in the information recording medium 101a. FIG. 15 is a diagram showing the electric field intensity when the information recording medium 101a is irradiated with laser light. Like FIG. 13, the laser light is irradiated from below in FIG.

  As shown in FIG. 15, there was no electric field concentration in the information recording medium 101a as high as the electric field intensity comparable to the electric field intensity at the exit portion of the minute aperture as seen in Example 1.

[Comparative Example 2]
The information recording medium 102a having the same configuration as that of the first embodiment except that the dielectric 13 is not used and the entire portion of the dielectric 13 is replaced with the metal member 14 in the first embodiment. The strength was measured.

  FIG. 16 shows the measurement result of the electric field strength in the cross section corresponding to FIG. 1 in the information recording medium 102a. FIG. 16 is a diagram showing the electric field strength when the information recording medium 102a is irradiated with laser light, and the laser light is irradiated from below in FIG. 16 as in FIGS.

  As shown in FIG. 16, electric field concentration was not confirmed in the information recording medium 102a.

[Example 2]
In the configuration of the first embodiment, the information recording medium 1a has the same configuration as that of the first embodiment except that the recording layer 12 is replaced with a bismuth-germanium alloy used for an optical information recording medium from a cobalt-platinum alloy that is a magnetic material. The electric field strength was measured by the same method as in Example 1. As a result, regardless of the material change of the recording layer 12, high-intensity electric field concentration similar to the results shown in FIGS. 13 and 14 is confirmed inside the information recording medium 1a (near the interface between the dielectric 13 and the metal 14). As a result, it has been clarified that even when the material of the recording layer 12 is an optical information recording material, high electric field concentration can be obtained.

Example 3
In the configuration of Embodiment 1, the near-field generating member 73 is removed, and the electric field strength (cross section shown in FIG. 1) when propagating light (laser light 71) emitted from the light source 75 is applied to the information recording medium 1a is shown. 17 shows. As shown in FIG. 17, even when propagating light is directly applied to the information recording medium 1a without using the near-field generating member 73, the interface between the metal body 14 and the dielectric 13 is formed inside the information recording medium 1a. Electric field concentration was confirmed in the vicinity. The electric field peak intensity (| E | ² ) at this time exceeds 5 (V / m) ² and the electric field exceeds the electric field peak intensity (1 (V / m) ² ) of incident propagating light (laser light). Concentration was obtained.

[Comparative Example 3]
In Example 3, the information recording medium is changed to the information recording medium 101a that does not use the metal body 14 shown in Comparative Example 1, and the propagation light (laser light 71) emitted from the light source 75 is used as in Example 3. The electric field strength when irradiated to the information recording medium 101a was measured.

  As a result, high-intensity electric field concentration as seen in Example 3 was not confirmed in the information recording medium 101a.

[Comparative Example 4]
The electric field strength was measured by the same method as in Example 3 for the same information recording medium 102a as in Example 3 except that the dielectric 13 was not used in Example 3 and all the parts of the dielectric 13 were replaced with the metal body 14. did.

  As a result, electric field concentration was not confirmed in the information recording medium 102a.

Example 4
The measurement result of the electric field strength in the information recording medium 1c according to Embodiment 2 is shown in FIG. FIG. 18 is a diagram showing the measurement result of the electric field strength in the plane shown in FIG. 9A when the information recording medium 1c is irradiated with laser light.

  As shown in FIG. 18, even when the metal body 14 is discretely arranged around the convex portion 12a, a strong local electric field is generated in the vicinity of the interface between the dielectric 13 and the metal body 14 inside the information recording medium 1c. Was able to measure concentration.

The electric field strength (| E | ² ) at the location where the electric field is concentrated is much higher than the electric field strength (50 (V / m) ² slightly) at the exit portion of the minute aperture and exceeds 200 (V / m) ² . It became extremely strong. This is because the metal bodies 14 are discretely arranged, so that plasmons generated near the interface between the dielectric body 13 and the metal body 14 cannot propagate through the metal body 14 (diffuse around). The plasmon is considered to be an effect of confining each metal body 14.

  As a result, the recording layer 12 can be heated from the inside of the information recording medium 1b with extremely strong power, so that the portion to be recorded can be heated sufficiently efficiently while reducing the power consumption of the light source 75. Further, as shown in FIG. 18, it was confirmed that the electric field concentration at the interface between the dielectric 13 and the metal body 14 was particularly strongly generated at the four points surrounding the convex portion 12a. That is, it has been clarified that the recording layer 12 in the region surrounded by the four points where the electric field is concentrated is heated particularly strongly and information is easily recorded.

Example 5
In the configuration of Example 4, the information recording medium 1c has the same configuration as that of Example 4 except that the recording layer 12 is replaced with a bismuth-germanium alloy used for an optical information recording medium from a cobalt-platinum alloy, which is a magnetic material. The electric field strength was measured by the same method as in Example 1. As a result, regardless of the material change of the recording layer 12, the extremely high electric field concentration similar to the result shown in FIG. 18 is confirmed inside the information recording medium 1c (near the interface between the dielectric 13 and the metal 14). It was found that even when the material of the recording layer 12 is an optical information recording material, high-intensity electric field concentration can be obtained.

Example 6
In the configuration of Example 4, the near-field generating member 73 was removed, and the electric field strength when the propagation light emitted from the light source 75 was applied to the information recording medium 1b was measured. As a result, even when propagating light (laser light 71) is directly applied to the information recording medium 1b without using the near-field generating member 73, the metal body 14 and the dielectric 13 are formed inside the information recording medium 1b. Electric field concentration exceeding the electric field peak intensity of propagating light (laser beam 71) incident near the interface was confirmed.

Example 7
Using the information recording medium 1d according to Embodiment 3, the electric field strength was measured by the same method as in Example 1.

  The measurement result of the electric field strength in the information recording medium 1d is shown in FIG. FIG. 19 is a diagram showing the electric field strength in the cross section shown in FIG. 10 when the information recording medium 1d is irradiated with laser light. As shown in FIG. 19, strong electric field concentration could be measured inside the information recording medium 1d in the region irradiated with the near-field light 72 (near the interface between the dielectric 13 and the metal body 14).

As shown in FIG. 19, the electric field strength (| E | ² ) at the location where the electric field is concentrated is almost the same as the electric field strength (50 (V / m) ² strength) at the exit portion of the minute aperture, It was very strong.

  As a result, the recording layer 12 can be heated from the inside of the information recording medium 1d, so that the portion of the recording layer 12 where information is to be recorded can be sufficiently efficiently heated while reducing the power consumption of the light source 75. it can.

[Comparative Example 5]
In Example 7, the information recording medium 101c having the same configuration as in Example 7 was replaced by the same method as in Example 7 except that the metal body 14 was replaced with the dielectric 13 without using the metal body 14. The electric field strength was measured.

  As a result, no high-intensity electric field concentration comparable to the electric field intensity at the exit portion of the minute aperture as in Example 7 was found in the information recording medium 101c.

[Comparative Example 6]
In Example 7, the electric field strength was measured by the same method as in Example 7 for the same information recording medium 102c as in Example 7 except that the dielectric 13 was not used and all the part of the dielectric 13 was replaced with the metal body 14. did.

  As a result, electric field concentration was not confirmed in the information recording medium 102c.

Example 8
In the configuration of Example 7, the near-field generating member 73 was removed, and the electric field intensity was measured when the information recording medium 1d was irradiated with propagating light (laser light 71) emitted from the light source 75. As a result, even when propagating light (laser light 71) is directly applied to the information recording medium 1d without using the near-field generating member 73, the dielectric 13 and the metal body 14 are formed inside the information recording medium 1d. Electric field concentration exceeding the electric field peak intensity (1 (V / m) ² ) of propagating light (laser beam 71) incident in the vicinity of the interface was confirmed.

  Specifically, the information recording medium according to the present invention is suitably used as an information recording medium represented by a hard disk, a CD (Compact Disc), a DVD (Digital Versatile Disc), a BD (Blu-ray Disc), and the like. Can do.

1 is a schematic cross-sectional view showing a configuration of an information recording medium according to Embodiment 1. FIG. FIG. 2 is a plan view showing a configuration of an information recording medium according to Embodiment 1, wherein (a) is a plan view taken along the line AA ′ in FIG. 1, and (b) is a plan view taken along the line BB ′ in FIG. c) is a plan view taken along line CC ′ of FIG. 2A and 2B are diagrams illustrating a method for manufacturing an information recording medium according to Embodiment 1, wherein FIG. 1A illustrates formation of a convex portion on a substrate, and FIG. 2B illustrates formation of a recording layer, a dielectric, and a metal body. , (C) shows the partial removal of the metal body, and (d) shows the formation of the protective layer. 6 is a schematic cross-sectional view showing a configuration of a modification of the information recording medium according to Embodiment 1. FIG. 6 is a schematic cross-sectional view showing a configuration of still another modification of the information recording medium according to Embodiment 1. FIG. 6 is a schematic cross-sectional view showing a configuration of still another modification of the information recording medium according to Embodiment 1. FIG. 6A and 6B are diagrams illustrating a manufacturing method of a modification example of the information recording medium according to the first embodiment, in which FIG. 5A illustrates formation of a recording layer, FIG. 5B illustrates formation of a mask, and FIG. FIG. 5 shows etching of the layers, (d) shows the formation of the dielectric and metal bodies, (e) shows the grinding of the metal bodies, and (f) shows the formation of the protective layer. 6 is a schematic cross-sectional view showing a configuration of an information recording medium according to Embodiment 2. FIG. FIG. 9 is a plan view showing a configuration of an information recording medium according to Embodiment 2, wherein (a) is a plan view taken along the line AA ′ of FIG. 8, and (b) is a plan view taken along the line BB ′ of FIG. c) is a plan view taken along line CC ′ of FIG. 6 is a schematic cross-sectional view showing a configuration of an information recording medium according to Embodiment 3. FIG. It is a top view which shows the structure of the information recording medium which concerns on Embodiment 3, (a) is a top view in the AA 'line of FIG. 10, (b) is a top view in the BB' line of FIG. It is a block diagram which shows the structure of the information recording / reproducing apparatus which concerns on Embodiment 4. FIG. 3 is a diagram showing the electric field strength measured in Example 1. FIG. 3 is a diagram showing the electric field strength measured in Example 1. 6 is a diagram showing electric field strength measured in Comparative Example 1. FIG. 10 is a diagram showing electric field strength measured in Comparative Example 2. FIG. 6 is a diagram showing electric field strength measured in Example 3. FIG. It is a figure showing the electric field strength measured in Example 4. It is a figure showing the electric field strength measured in Example 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Information recording medium 1b Information recording medium 1c Information recording medium 1d Information recording medium 11 Substrate 11a Convex part 12 Recording layer (information recording layer)
12a Convex part 13 Dielectric 14 Metal body 15 Protective layer 70 Recording head

Claims (16)

An information recording medium comprising an information recording layer formed directly or indirectly on a substrate and continuous in the in-plane direction of the substrate,
The information recording layer has a plurality of protrusions, and a metal body is provided between the adjacent protrusions via a dielectric ,
An information recording medium , wherein the metal body is not provided on the top of the convex portion .   The information recording medium according to claim 1, wherein the information recording layer is formed along a shape of the substrate surface.   The information recording medium according to claim 1, wherein the metal body is continuously provided so as to surround the convex portion.   The information recording medium according to claim 1, wherein the metal body is divided into a plurality of parts around the convex portion.   The information recording medium according to claim 1, wherein the metal body is provided continuously in a track length direction.   6. The information recording medium according to claim 1, wherein the metal body is made of gold, silver, aluminum, platinum, or an alloy containing at least one of these.   The information recording medium according to claim 1, wherein the information recording layer is made of a magnetic material.   The information recording medium according to claim 1, wherein the information recording layer is made of an optical recording material. A light source for irradiating the information recording medium according to claim 7 with light so that plasmons are generated in the vicinity of an interface between the dielectric and the metal ,
Magnetic field applying means for applying a magnetic field to the information recording medium;
Magnetic field detection means for detecting a leakage magnetic field leaking from the information recording medium;
An information recording / reproducing apparatus comprising: A light source for irradiating the information recording medium according to claim 8 with light so that plasmons are generated in the vicinity of an interface between the dielectric and the metal ,
A light amount detecting means for detecting a light amount reflected from the recording medium;
An information recording / reproducing apparatus comprising:   The information recording / reproducing apparatus according to claim 9, further comprising a near-field light generation unit between the light source and the information recording medium and on the light path. A heating step of irradiating the information recording medium according to claim 7 with light to heat an information recording area in the information recording medium;
A magnetic field application step of applying a magnetic field to the information recording area;
An information recording method comprising:   An information reproducing method comprising a leakage magnetic field detection step of detecting a leakage magnetic field generated from the information recording medium according to claim 7.   9. An information recording method comprising a heating step of irradiating the information recording medium according to claim 8 with light to heat an information recording area in the information recording medium.   An information reproducing method comprising a light amount detecting step of detecting a light amount of reflected light reflected from the information recording medium according to claim 8. An information recording layer, the information recording layer has a plurality of protrusions, and a metal body is provided between the adjacent protrusions via a dielectric, the top of the protrusions Is a method of manufacturing an information recording medium not provided with a metal body,
A layer formed directly or indirectly on the substrate, continuously formed in the in-plane direction of the substrate, and forming an information recording layer having a plurality of convex portions;
And a step of forming a metal body via a dielectric between the adjacent convex portions.

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