JP2009238291A - Magnetic recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording medium in which variations in characteristics are reduced by suppressing the variations in each layer height when forming multilayered magnetic layers on the magnetic substance filled in nano-holes, and also provide its manufacturing method. <P>SOLUTION: The magnetic recording medium manufacturing method includes a step of forming base material on a substrate, a step of forming nano-holes on the base material, a step of filling a magnetic substance in the nano-holes, a step of polishing the magnetic substance overflowing the nano-holes, and a step of injecting ions into the base material from the surface polished in the polishing step toward the substrate side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium suitable for an external storage device of a computer and a hard disk device widely used as a consumer video recording device, and the like, and a method for manufacturing the same.

  As a next-generation ultra-high-density perpendicular magnetic recording medium, so-called patterned media that improve the bit density by reducing the magnetic interaction between them by separating and arranging magnetic materials that carry individual signals (magnetic bits) Is attracting attention. Among them, an alumina nanohole patterned medium produced by filling an inside of an alumina nanohole formed by anodizing an aluminum film with a ferromagnetic material is promising. This is because alumina nanohole patterned media can control the position of nanohole generation at a pitch of 10 nm to several tens of nm by creating a shallow depression that becomes the starting point (opening formation point) of nanohole generation on the aluminum film surface before anodic oxidation. Advantages that patterned media can be obtained relatively easily, and structural anisotropy can be imparted to the magnetic material by adjusting the diameter and height of the nanoholes. It is because it has the merit that it is excellent in.

  In the nanohole media, the magnetic material is needle-shaped, the aspect ratio is high, the distance from the surface to the underlying soft magnetic layer (SUL) is increased, and the magnetic flux below the magnetic nanopillar spreads to the side. For magnetic nanopillars formed by filling magnetic materials in nanoholes, the hard magnetic pillar (surface side (upper part)) / soft magnetic pillar (substrate side (lower part)) 2 It has been proposed to use a layer stack structure to condense magnetic flux to a soft magnetic material to suppress deterioration of resistance and improve retention characteristics while maintaining ease of writing (for example, Patent Document 1).

  Here, as shown in FIG. 5A to FIG. 5G, as a method for producing a magnetic nanopillar having a two-layered structure of hard magnetic pillars / soft magnetic pillars, a magnetic substance is applied from the bottom of the nanohole toward the surface by plating. A filling method has been proposed. However, merely performing plating causes variations in the height (length) of the hard magnetic material (FIG. 5F), resulting in large variations in characteristics. The depth of the nanohole can be controlled by the anodic oxidation time (Fig. 5B), but the plating current flowing through the nanohole varies due to the variation in the thickness of the insulating layer at the bottom of the nanohole (generally called the barrier layer). The filling speed will change. The plating current varies in inverse proportion (in the case of AC plating) or exponential function (in the case of DC plating) with respect to the variation in the thickness of the barrier layer. Therefore, even when the variation of the barrier layer thickness is small, the plating current varies greatly. In addition, when only one kind of magnetic material is filled in the nanohole, plating is performed until the pillar with the slowest growth rate overflows, and then the overflowed portion is polished and flattened to increase the height of the magnetic nanopillar. However, when stacking multiple magnetic bodies, the height of the final magnetic nanopillars can be adjusted, but the height of the hard magnetic bodies in the magnetic nanopillars is However, there is a problem that the characteristic variation becomes large (FIG. 5E).

  In order to solve this problem, as shown in FIGS. 6A to 6G, the magnetic nanopillar may have a three-layer stack structure of soft magnetic pillars / hard magnetic pillars / soft magnetic pillars to suppress variations in magnetic characteristics. It has been proposed (for example, Patent Document 2).

  Here, first, a base soft magnetic body is filled in the nanohole (FIG. 6C), and a hard magnetic body with a controlled pillar height is controlled on the filled base soft magnetic body by controlling the plating time. Filled (FIG. 6D), the filled hard magnetic material is filled with the soft magnetic material until it overflows from the nanohole (FIG. 6E), and the portion overflowing from the nanohole is polished (FIG. 6F). Thereby, the dispersion | variation in the height of a hard magnetic body is suppressed. However, compared to magnetic nanopillars with a two-layer stack structure of hard magnetic pillars (upper) / soft magnetic pillars (lower), since the height of the hard magnetic material is low, the overall variation is small, but the variation is It will not disappear completely. Further, when the hard magnetic material is distant from the surface, the effective flying height is increased, and the write / read characteristics are deteriorated.

International Publication No. 04/084193 Pamphlet JP 2006-277844 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, it is possible to provide a magnetic recording medium and a method of manufacturing the same that can suppress variation in height of each layer when forming a multi-layered magnetic layer filled in nanoholes, thereby suppressing variation in characteristics. Objective.

Means for solving the problems are as follows. That is,
The method for producing a magnetic recording medium of the present invention includes a base material forming step of forming a base material on a substrate, a nanohole forming step of forming nanoholes in the base material, and a magnetic material that fills the nanoholes with a magnetic material. A filling step, a polishing step for polishing the magnetic material overflowing from the nanoholes, and an ion implantation step for injecting ions into the base material from the polishing surface in the polishing step toward the substrate side. And
In the method for manufacturing the magnetic recording medium, the base material is formed on the substrate in the base material forming step. In the nanohole forming step, the nanohole is formed in the base material. In the magnetic substance filling step, the nanoholes are filled with a magnetic substance. In the polishing step, the magnetic material overflowing from the nanohole is polished. In the ion implantation step, ions are implanted into the base material from the polishing surface in the polishing step toward the substrate side. As a result, by appropriately setting the ion implantation energy, only the substrate side portion of the filled magnetic material can be preferentially modified with high precision. For example, when a hard magnetic material is filled as a magnetic body, only the substrate side can be preferentially softened. As a result, it is possible to suppress variations in the height of the hard magnetic portion and the soft magnetic portion in the magnetic material filled in the nanohole, thereby suppressing the characteristic variation and improving the characteristics of the nanohole patterned disk. Can do. Further, a magnetic recording medium having a hard magnetic / soft magnetic stack structure can be easily manufactured.

  The magnetic recording medium of the present invention is a magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium, wherein the substrate, the base material on which the nanoholes are formed, and a magnetic material filled in the nanoholes, And the coercive force (magnetic coercive force) of the magnetic material filled in the nanoholes is continuously increased from the substrate side toward the base material side.

  According to the present invention, magnetic recording that can solve the conventional problems and suppress the variation in the height of each layer when forming a multi-layered magnetic layer in the nanohole, thereby suppressing the characteristic variation. A medium and a manufacturing method thereof can be provided.

(Method of manufacturing magnetic recording medium)
The method for producing a magnetic recording medium of the present invention includes at least a base material forming step, a nanohole forming step, a magnetic material filling step, a polishing step, and an ion implantation step, and further appropriately selected according to need. These steps are included.

-Base material formation process-
The said base material formation process is a process of forming a base material on a board | substrate (FIG. 1A).

--- Board--
There is no restriction | limiting in particular about the material, a shape, a structure, a magnitude | size, etc. as said board | substrate, According to the objective, it can select suitably.
The material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include glass, silicon, quartz, and SiO ₂ / Si formed by forming a thermal oxide film on the silicon surface. These may be used individually by 1 type and may use 2 or more types together.
There is no restriction | limiting in particular as said shape, Although it can select suitably according to the objective, For example, plate shape, disk shape (disk shape), etc. are mentioned suitably. Among these, when applied to a magnetic recording medium such as a hard disk, a disk shape (disk shape) is preferable.

--Base material--
There is no restriction | limiting in particular as said base material, Although it can select suitably according to the objective, For example, a metal material is mentioned suitably. The metal material may be, for example, any of a simple metal, an oxide thereof, a nitride, an alloy, and the like. Among these, for example, alumina (aluminum oxide), aluminum, and the like are preferable. Among these, aluminum is particularly preferable.

  The base material can be formed according to a known method, for example, preferably by a sputtering method (sputtering), a vapor deposition method, or the like. There is no restriction | limiting in particular as formation conditions of this base material, According to the objective, it can select suitably. In the case of the sputtering method, sputtering can be performed using a target formed of the base material. The target used in this case preferably has high purity, and when the base material is aluminum, it is preferably 99.990% or more.

There is no restriction | limiting in particular as thickness of the said base material, Although it can select suitably according to the objective, For example, 500 nm or less is preferable and 5-200 nm is more preferable.
When the thickness of the substrate exceeds 500 nm, it may be difficult to fill a nanohole described later with a magnetic material.

-Nanohole formation process-
The nanohole forming step is a step of forming nanoholes in the substrate (FIG. 1B).

--- Nanohole--
The nanohole may be formed as a hole penetrating the base material, or may be formed as a hole (dent) without penetrating the base material, but the nanohole penetrates the base material. It is preferable that it is formed as a through hole.

  The arrangement of the nanoholes is not particularly limited and can be appropriately selected depending on the purpose.For example, the nanoholes may be arranged in parallel in one direction, or arranged in at least one of concentric and spiral shapes. It may be.

  In addition, it is preferable that the nanoholes in adjacent nanohole rows are arranged in the radial direction. In this case, the magnetic recording medium is capable of high-density recording and high-speed recording without increasing the write current of the magnetic head, has a large capacity, has excellent overwrite characteristics, and has uniform characteristics. There is no problem of light etc. and it is extremely high quality.

  The width of the array of nanoholes is not particularly limited and can be appropriately selected according to the purpose.For example, one array is used as a data region in that tracking can be easily performed. When another adjacent array is used as a guard band region, the ratio of the width between the data region and the guard band region is preferably 2: 1. Specifically, the array width suitable for the data region is preferably 15 to 200 nm, for example, and the array width suitable for the guard band region is preferably 7 to 100 nm, for example.

  The arrangement pattern of the nanoholes in the arrangement of the nanoholes is not particularly limited and can be appropriately selected according to the purpose. However, at least one of the adjacent arrangements is the closest packed in a hexagonal close-packed lattice shape. It is preferable that the pattern is formed as a result. Since the hexagonal close-packed lattice is the most stable pattern in alumina nanoholes, fluctuations in the pattern other than the intentionally introduced pattern change can be minimized.

The opening diameter in the nanohole is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably large enough to make the magnetic layer a single magnetic domain, specifically, the pitch of the nanoholes Of 2/3 or less, and more preferably 1/3 to 2/5. For example, when the pitch of the nanoholes is 30 nm, 20 nm or less is preferable, and 10 to 12 nm is more preferable.
If the aperture diameter in the nanohole exceeds 2/3 of the nanohole pitch, for example, 20 nm when the pitch is 30 nm, the magnetic recording medium may not have a single domain structure.

  The formation of the nanohole is not particularly limited and can be performed according to a known method. For example, after forming a layer (metal layer) of a base material by a sputtering method, a vapor deposition method or the like, the nanohole is formed by anodizing treatment. Can be performed. Anodization treatment of aluminum or the like is preferable in that a large number of nanoholes can be formed evenly at almost equal intervals.

  Note that nanoholes formed by anodizing treatment are usually randomly arranged, but a pattern for forming a plurality of regular arrays of nanoholes on the metal layer (desired depressions) before the anodizing treatment. Is preferably formed in advance. In this case, the anodizing treatment is advantageous in that the nanoholes can be efficiently formed only on the pattern.

  The method for forming the pattern is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (1) circular convex portions arranged in a pattern (for example, a hexagonal close-packed lattice) A stamper having a surface pattern formed with a plurality of regular arrays (when applied to a magnetic disk or the like, the convex arrays are arranged concentrically or spirally) as a surface shape, the metal layer (for example, A method of forming a pattern in which a plurality of circles are regularly arranged in a hexagonal close-packed lattice, and (2) after forming a resin layer or a photoresist layer on the metal layer, These are patterned by an ordinary photo process or an imprint method using a stamper, etched, etc., to form a pattern (for example, hexagonal close-packed) on the surface of the metal layer. A method of forming a plurality of regularly arranged recesses formed by arranging a child-like) of the formed pattern, and the like.

  The stamper is not particularly limited and may be appropriately selected depending on the purpose. From the viewpoint that it is most widely used as a material for producing a fine structure in the semiconductor field, silicon, a silicon oxide film, and the like. From the viewpoint of continuous use durability, a silicon carbide substrate and the like are included, and a Ni stamper used for molding an optical disk and the like is also included. The stamper can be used multiple times. There is no restriction | limiting in particular as the method of the said imprint transfer, According to the objective, it can select suitably from well-known methods. The resist material for the photoresist layer includes not only a photoresist material but also an electron beam resist material. There is no restriction | limiting in particular as said photoresist material, It can select suitably from well-known materials in the semiconductor field | area etc., For example, the material etc. which can utilize near ultraviolet light, near-field light, etc. are mentioned.

The pitch of the nanoholes is appropriately determined depending on the voltage in the anodizing treatment, and is approximately 2.5 times (nm) of the anodizing voltage (V). Therefore, the voltage in the anodizing treatment is not particularly limited, but is preferably 3 to 40 V, and more preferably 3 to 10 V, for example.
When the voltage is 3 to 40 V, the recording medium can be densified. When the voltage is 3 to 10 V, the pitch of the nanoholes can be 7 to 25 nm. This is particularly advantageous in that the density of the medium can be further increased.
In addition, there is no restriction | limiting in particular as a kind, density | concentration, temperature, time, etc. of the electrolyte solution in the said anodizing process, According to the number of nanoholes to form, a magnitude | size, an aspect-ratio, etc., it can select suitably. For example, preferable examples of the electrolyte include a diluted phosphoric acid solution, a diluted oxalic acid solution, and a diluted sulfuric acid solution. In any case, the adjustment of the aspect ratio of the nanohole can be performed by increasing the diameter of the nanohole (alumina pore) by immersing in a phosphoric acid solution after the anodizing treatment.

-Magnetic material filling process-
The magnetic material filling step is a step of filling the magnetic material in the nanohole (FIG. 1C).

--- Magnetic material--
The material of the magnetic body is not particularly limited and can be appropriately selected from known materials according to the purpose. Examples of the material for the recording layer of the magnetic recording medium include Fe, Co, Ni, FeCo, Preferable examples include at least one hard magnetic material selected from FeNi, CoNi, CoNiP, FePt, CoPt, and NiPt. These may be used individually by 1 type and may use 2 or more types together. In the present application, for example, a hard magnetic material is filled in the nanohole as a magnetic material.

The magnetic material, said material is not particularly limited as long as it is formed as a perpendicular magnetization film by, and can be appropriately selected depending on the intended purpose, for example, a Ll ₀ ordered structure, and the substrate C axis Preferred examples include those oriented in the vertical direction, those having an fcc structure or a bcc structure, and having the C-axis aligned in the direction perpendicular to the substrate.

There is no restriction | limiting in particular and the filling of the said magnetic body in the nanohole can be performed in accordance with a well-known method, For example, it can carry out by the electroplating method etc.
Specifically, after the substrate is immersed in a plating solution, a voltage is applied using the electrode layer as an electrode, whereby the magnetic material is deposited or deposited.

-Polishing process-
The polishing step is a step of polishing the magnetic material overflowing from the nanoholes (FIG. 1D).
The polishing of the magnetic material overflowing from the nanoholes is not particularly limited and can be performed according to a known method, and examples thereof include a CMP process.

-Ion implantation process-
The ion implantation step is a step of implanting ions into the base material from the polishing surface in the polishing step toward the substrate side (FIG. 1E).

--Ion--
The ions to be implanted are not particularly limited and can be appropriately selected from known ones according to the purpose. (I) The magnetic material filled in the nanohole is either Co or Co alloy. In the case where the magnetic material filled in the nanohole is Ni and a Ni alloy, it is preferably an Fe ion, and (iii) in the nanohole. When the filled magnetic body is either Fe or an Fe alloy, Ni ions are preferable.
When the magnetic material filled in the nanohole is a material having high crystal anisotropy such as L10 phase CoPt, it is preferable to inject a rare gas such as Ar or Xe instead of ions. .

--Ion implantation--
The ion implantation is not particularly limited as long as only the substrate side portion of the filled magnetic material (hard magnetic material) is preferentially softened. Although it can be selected, it is preferable to set the energy of the ion implantation to an energy at which the substrate side end portion of the magnetic material filled in the nanohole becomes Ra of the implantation ion distribution curve by the TRIM simulation.

--- Ra of implanted ion distribution curve by TRIM simulation ---
As shown in FIG. 2, Ra of the implantation ion distribution curve by the TRIM simulation indicates a peak value of implantation ion distribution curve data by each TRIM simulation in a graph in which the vertical axis represents the ion density and the horizontal axis represents the depth.

  For a magnetic recording medium (for example, nanohole patterned media) produced by filling a nanohole formed in the base material with a magnetic material, the substrate side end of the magnetic material (magnetic pillar) filled in the nanohole The substrate side portion of the filled magnetic material (magnetic pillar) is formed by ion implantation with energy set so that Ra is near the interface between the magnetic pillar and the underlying soft magnetic layer (6a in FIG. 1E). The composition of the filled magnetic material is changed by giving priority to the composition of the filled magnetic material or by making the crystal structure of only the substrate side portion (lower portion of the magnetic pillar) of the filled magnetic material amorphous. The coercive force of only the substrate side part (lower part of the magnetic pillar) is reduced to make it softer. At that time, since the base material (for example, non-magnetic matrix (anodized alumina, SiOx, etc.)) is composed of lighter elements than the magnetic substance filled in the nanoholes, the ion blocking ability is higher than that of the magnetic substance. Low, most ions pass through. Therefore, even if magnetic metal is injected, it does not remain in the base material (for example, nonmagnetic matrix (anodized alumina, SiOx, etc.)), and the magnetic insulation does not deteriorate.

-Other processes-
The other steps are not particularly limited and may be appropriately selected depending on the purpose. For example, the underlayer soft magnetic formation step, the electrode layer formation step, the surface treatment step, the protective film formation step, and the lubricant application step Etc.

--Base soft magnetic layer formation process--
The base soft magnetic layer forming step is a step of forming a base soft magnetic layer on the substrate.
Examples of the substrate include those described above.
The underlayer soft magnetic layer can be formed according to a known method. For example, the underlayer soft magnetic layer may be formed by a sputtering method (sputtering), a vacuum film forming method such as a vapor deposition method, or electrodeposition (electrodeposition method). Alternatively, it may be formed by electroless plating.
The base soft magnetic layer having a desired thickness is formed on the substrate by the base soft magnetic layer forming step.

--- Electrode layer formation process--
The electrode layer forming step is a step of forming an electrode layer between the base material and the base soft magnetic layer.
The electrode layer can be formed according to a known method, but can be suitably performed by, for example, a sputtering method (sputtering) or a vapor deposition method. There is no restriction | limiting in particular as formation conditions of this electrode layer, According to the objective, it can select suitably.
The electrode layer formed by the electrode layer forming step is used as an electrode when a magnetic material is formed by electrodeposition.

-Surface treatment process-
The surface treatment step is a step of polishing and flattening the surface of the magnetic recording medium.
There is no restriction | limiting in particular as the method of surface treatment in the said surface treatment process, According to a well-known method, it can carry out, for example, CMP process etc. are mentioned. When the surface of the magnetic recording medium is smoothed by the surface treatment step, the magnetic head such as a perpendicular magnetic recording head can be stably levitated, thereby achieving both high density recording and ensuring reliability due to low levitating. This is advantageous in that it can.

--Protective film formation process--
The protective film forming step is a step of forming a protective film.
There is no restriction | limiting in particular as said protective film, According to the objective, it can select suitably, For example, a carbon film etc. can be mentioned.
The protective film can be formed according to a known method, but can be suitably performed by, for example, a sputtering method (sputtering). There is no restriction | limiting in particular as formation conditions of this protective film, According to the objective, it can select suitably.

--- Lubricant application process ---
The lubricant application step is a step of applying a lubricant.
There is no restriction | limiting in particular as said lubricant, According to the objective, it can select suitably.
The lubricant can be applied according to a known method.

(Magnetic recording medium)
The magnetic recording medium of the present invention is a magnetic recording medium manufactured by the method of manufacturing the magnetic recording medium of the present invention, and includes a substrate, a base material on which nanoholes are formed, and a magnetic material filled in the nanoholes. And, if necessary, other layers.

  The coercive force in the magnetic material filled in the nanoholes continuously increases from the substrate side toward the base material side. That is, the magnetic material filled in the nanohole is composed of a soft magnetic material (soft magnetic layer) disposed on the substrate side and a hard magnetic material (hard magnetic layer) disposed on the substrate side 2. Layer structure.

  Examples of the substrate include those described above.

  The substrate is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include anodized alumina formed by anodizing aluminum and a nonmagnetic matrix such as SiOx. It is done.

  Examples of the hard magnetic material (hard magnetic layer) include those described above.

  The soft magnetic material (soft magnetic layer) is not particularly limited and may be appropriately selected from known materials according to the purpose. For example, it is selected from NiFe, FeSiAl, FeC, FeCoB, FeCoNiB and CoZrNb. Suitable examples include at least one kind. These may be used individually by 1 type and may use 2 or more types together.

  The thickness of the soft magnetic layer is not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected according to the depth of the nanoholes in the porous layer, the thickness of the hard magnetic layer, and the like. Examples include (1) an aspect in which the thickness of the hard magnetic layer exceeds the thickness, and (2) an aspect in which the sum of the thickness of the base soft magnetic layer exceeds the thickness of the hard magnetic layer.

The soft magnetic layer is advantageous in that the magnetic flux from the magnetic head used for magnetic recording can be effectively converged on the hard magnetic layer, and the perpendicular component of the magnetic field of the magnetic head can be increased. . Preferably, the soft magnetic layer can form a magnetic circuit of a recording magnetic field input from the magnetic head together with the magnetic head together with the underlying soft magnetic layer.
The soft magnetic layer preferably has an easy magnetization axis in a direction substantially perpendicular to the substrate surface. In this case, when recording is performed with a perpendicular magnetic recording head, it is possible to control the concentration of magnetic flux from the perpendicular magnetic recording head, the optimum magnetic recording / reproducing characteristics at the recording density used, and the like. As a result of concentrating on the layers, the write efficiency is greatly improved, the write current is reduced, and the overwrite characteristics are remarkably improved as compared with the conventional magnetic recording apparatus.

In the magnetic recording medium of the present invention, a base soft magnetic layer may be provided between the substrate and the base material.
There is no restriction | limiting in particular as a material of the said foundation | substrate soft magnetic layer, Although it can select suitably from well-known things, For example, what was mentioned above as a material of the said soft magnetic layer is mentioned suitably. These materials may be used individually by 1 type, may use 2 or more types together, and may mutually be the same as the material of the said soft-magnetic layer, and may differ.

The underlayer soft magnetic layer preferably has an easy magnetization axis in the in-plane direction of the substrate surface. In this case, a magnetic circuit in which the magnetic flux from the magnetic head used for magnetic recording is effectively closed can be formed, and the vertical component of the magnetic field of the magnetic head can be increased. The underlying soft magnetic layer is also effective in single domain recording with a bit size (opening diameter of the nanohole) of 100 nm or less.
The formation of the underlying soft magnetic layer is not particularly limited and can be performed according to a known method. For example, it can be performed by electrodeposition (electrodeposition method) or electroless plating.

  There is no restriction | limiting in particular as said other layer, Although it can select suitably according to the objective, For example, an electrode layer, a protective layer, etc. are mentioned.

The electrode layer is a layer that functions as an electrode when the magnetic layer is formed by electrodeposition or the like, and is generally provided on the substrate and below the magnetic layer. When the magnetic layer is formed by electrodeposition, the electrode layer may be used as an electrode, but the base soft magnetic layer or the like may be used as an electrode.
There is no restriction | limiting in particular as a material of the said electrode layer, According to the objective, it can select suitably, For example, Cr, Co, Pt, Cu, Ir, Rh, these alloys, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. The electrode layer may further contain W, Nb, Ti, Ta, Si, O, etc. in addition to these materials.

There is no restriction | limiting in particular as thickness of the said electrode layer, According to the objective, it can select suitably. One electrode layer may be provided, or two or more electrode layers may be provided.
The formation of the electrode layer is not particularly limited and can be performed according to a known method. For example, the electrode layer can be formed by a sputtering method, a vapor deposition method, or the like.

The protective layer is a layer having a function of protecting the magnetic layer, and is provided on the surface or above the magnetic layer. The protective layer may be provided in only one layer, may be provided in two or more layers, may have a single layer structure, or may have a laminated structure.
There is no restriction | limiting in particular as a material of the said protective layer, According to the objective, it can select suitably, For example, DLC (diamond-like carbon) etc. are mentioned.

There is no restriction | limiting in particular as thickness of the said protective layer, According to the objective, it can select suitably.
The formation of the protective layer is not particularly limited, and can be performed according to a known method according to the purpose. For example, it can be performed by a plasma CVD method, a coating method, or the like.

The magnetic recording medium of the present invention can be used for various types of magnetic recording using a magnetic head, but can be suitably used for magnetic recording using a single pole head.
The magnetic recording medium of the present invention is capable of high-density recording and high-speed recording without increasing the write current of the magnetic head, has a large capacity, has excellent overwrite characteristics, uniform characteristics, and high quality. For this reason, the magnetic recording medium can be designed and used as various magnetic recording media. For example, the magnetic recording medium is designed for a hard disk device widely used as an external storage device of a computer, a consumer video recording device, or the like. It can be used, and can be particularly suitably designed and used for a magnetic disk such as a hard disk.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

Example 1
As shown in FIG. 1A, a sputtering method is used to deposit a 50 nm Ta film (adhesion layer 2) / 100 nm Ni film (which will later become the underlying soft magnetic layer 3) / 5 nm Ta on the HDD disk substrate 1. Film (oxidation stop layer 4) / 100 nm Al film (base material 5) was formed.

  Next, anodization is performed using a 0.3 M oxalic acid bath at a voltage of 40 V, and the Al film 5 is made porous alumina up to the Ta film (oxidation stop layer 4) to form an anodized alumina 5a. Nanoholes were formed at an average pitch of 100 nm (FIG. 1B). Here, anodic oxidation is performed without texture treatment. However, it is also possible to control the arrangement of nanoholes by patterning the Al film 5 as a starting point for generating nanoholes before anodic oxidation.

  Next, Co as the ferromagnetic material 6 was filled in the nanohole with an alternating current of 11 V using a sulfuric acid Co-boric acid bath (FIG. 1C). Filling was performed until Co sufficiently overflowed from the nanohole surface, and the overflowed Co was removed and planarized by surface polishing (FIG. 1D).

Next, Fe ions were implanted at 1.6 × 10 ¹⁷ (cm ⁻² ) at an acceleration voltage of 300 keV (FIG. 1E).

  Further, a DLC (diamond-like carbon) film having a thickness of 5 nm was formed by a sputtering method, and a lubricant was applied by a dipping method to form a protective film (lubricant layer) 7 to produce a magnetic medium (FIG. 1F). ).

In the magnetic nanopillar portion 8 (FIG. 1F), as shown in the TRIM simulation result of FIG. 3A, the Fe concentration reaches 50% near the Co layer 20-Ni layer 80 interface (depth 90 nm), and Fe 50%. -Co 50% soft magnetic (permendurized). On the other hand, on the surface side (depth around 0 nm), the Fe concentration was 5% or less, and ferromagnetism was maintained.
Also in the Ni layer, Fe 40% -Ni 60% near the interface with the Co layer (depth 100 nm) and Fe 10% -Ni 90% near the interface with the Ta layer (depth 150 nm) softening (permalloy) did.

On the other hand, in the alumina matrix portion, as shown in the TRIM simulation result of FIG. 3B, Fe ions almost completely permeate through the alumina matrix (alumina layer), and almost all of the Fe ions are injected into the Ni layer. The Ni layer was softened (permalloyed). Fe ions that permeated the Ni layer were also implanted into the nonmagnetic Ta layer and the disk substrate, but there was no significant effect because the Fe ion concentration was low and the distance from the magnetic material was long.
3A and 3B, the Ta film as the oxidation stop layer 4 is omitted.

  In Example 1, Fe ions were implanted into Co to soften (permendurized), but Fe was injected into Ni to soften (permalloy), or CoPt (metal). Even in a method in which Ar is injected into the tube compound) to make it amorphous, similarly, only the substrate side portion of the magnetic nanopillar can be preferentially softened. In addition, when the magnetic nanopillar is softened due to the composition variation of the magnetic nanopillar, the crystallinity of the ferromagnetic (ferromagnetic layer) is recovered and further improved by heat treatment at a low temperature (150 ° C. or lower). You can also. In addition, since the implanted ions are implanted in a magnetic nanopillar and in the underlying soft magnetic layer (SUL) in a self-aligned manner, so-called patterning resist processing or the like is unnecessary, but surface roughness due to a sputtering phenomenon is eliminated. In order to prevent this, a protective film may be formed before ion implantation.

  Furthermore, the matrix portion is not particularly limited as long as it has a low ion stopping ability with respect to the magnetic nanopillar, and therefore the same process can be applied even when SiOx or the like is used instead of alumina. Needless to say.

  FIG. 4 is a graph showing a hysteresis curve when a perpendicular magnetic field is applied to the magnetic recording medium, (a) shows the case of the magnetic recording medium of the present invention, and (b) shows a single magnetic layer. 5C shows the case of the magnetic recording medium, FIG. 5F shows the case of the magnetic recording medium of FIG. 5F (the magnetic material is a hard magnetic layer / soft magnetic layer two-layer structure), and FIG. 6D shows the magnetic recording medium of FIG. The case where the magnetic body is a soft magnetic layer / hard magnetic layer / soft magnetic layer three-layer structure) is shown.

  In the magnetic recording medium of FIG. 5F ((c) in FIG. 4), the coercive force can be reduced as compared with the magnetic recording medium ((b) in FIG. 4) in which the magnetic substance is a single layer, but the hard magnetic layer Due to the variation in height, the coercive force varies, and the squareness ratio deteriorates. In the magnetic recording medium of FIG. 6G ((d) in FIG. 4), the coercive force can be lowered compared to the magnetic recording medium of FIG. 5F ((c) in FIG. 4), but the variation in coercive force is eliminated. It is not possible to cause a decrease in the squareness ratio. On the other hand, according to the magnetic recording medium of the present invention ((a) in FIG. 4), it is possible to suppress variations in the height of the hard magnetic part and the soft magnetic part in the magnetic material filled in the nanohole, Thus, the coercive force can be lowered without lowering the squareness ratio. Further, according to the magnetic recording medium of the present invention, when the magnetization in the zero magnetic field is made constant, the writing can be performed on the magnetic material with a lower magnetic field, so that the writing characteristics can be improved.

The preferred embodiments of the present invention are as follows.
(Additional remark 1) The base material formation process which forms a base material on a board | substrate, the nanohole formation process which forms a nanohole in the said base material, the magnetic body filling process which fills a magnetic body in the said nanohole, From the said nanohole A magnetic recording medium manufacturing comprising: a polishing step of polishing an overflowing magnetic material; and an ion implantation step of implanting ions into the base material from a polishing surface in the polishing step toward the substrate side Method.
(Additional remark 2) The manufacturing method of the magnetic recording medium of Additional remark 1 which fills a hard magnetic material as said magnetic body.
(Supplementary note 3) The supplementary note 1 or 2, wherein, in the ion implantation step, ions are implanted at an energy at which a substrate side end portion of the magnetic material filled in the nanohole becomes Ra of an implantation ion distribution curve by TRIM simulation. A method of manufacturing a magnetic recording medium.
(Additional remark 4) The manufacturing method of the magnetic recording medium of Additional remark 2 or 3 whose magnetic body with which the said nanohole was filled is either Co and Co alloy, and the said implanted ion is Fe ion.
(Additional remark 5) The manufacturing method of the magnetic recording medium of Additional remark 2 or 3 whose magnetic body with which the said nanohole was filled is either Ni and Ni alloy, and the said implanted ion is Fe ion.
(Additional remark 6) The manufacturing method of the magnetic recording medium of Additional remark 1 or 3 whose magnetic body with which the said nanohole was filled is either Fe and Fe alloy, and the said ion which injected is Ni ion.
(Appendix 7) A base material forming step for forming a base material on a substrate, a nanohole forming step for forming nanoholes in the base material, a magnetic material filling step for filling magnetic materials in the nanoholes, and the nanoholes A magnetic recording medium comprising: a polishing step for polishing an overflowing magnetic material; and a rare gas injection step for injecting a rare gas into the base material from the polishing surface in the polishing step toward the substrate side. Manufacturing method.
(Additional remark 8) The manufacturing method of the magnetic-recording medium of Additional remark 7 whose said noble gas is either Ar and Xe.
(Supplementary note 9) A magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to any one of supplementary notes 1 to 8, wherein the substrate, the base material on which the nanoholes are formed, and filling the nanoholes A magnetic recording medium, wherein the coercive force of the magnetic material filled in the nanoholes continuously increases from the substrate side toward the base material side. .

The magnetic recording medium of the present invention can be suitably used for hard disk drives and the like that are widely used as external storage devices for computers, consumer video recording devices, and the like.
The method for producing a magnetic recording medium of the present invention can be suitably used for producing the magnetic recording medium of the present invention.

FIG. 1A is a process diagram for explaining a base material forming process in the method of manufacturing a magnetic recording medium of the present invention. FIG. 1B is a process diagram for explaining a nanohole forming process in the method for manufacturing a magnetic recording medium of the present invention. FIG. 1C is a process diagram for explaining a magnetic material filling process in the method of manufacturing a magnetic recording medium according to the present invention. FIG. 1D is a process diagram for explaining a polishing process in the method for manufacturing a magnetic recording medium of the present invention. FIG. 1E is a process diagram for explaining an ion implantation process in the method of manufacturing a magnetic recording medium according to the present invention. FIG. 1F is a process diagram for explaining a protective film formation process (lubricant application process) in the method for manufacturing a magnetic recording medium of the present invention. FIG. 2 is a diagram for explaining Ra of an implanted ion distribution curve by a TRIM simulation. FIG. 3A is a graph showing an implanted ion distribution by a TRIM simulation of a magnetic nanopillar portion. FIG. 3B is a graph showing an implanted ion distribution by the TRIM simulation of the alumina matrix portion. FIG. 4 is a graph showing a hysteresis curve when a perpendicular magnetic field is applied to the magnetic recording medium, (a) shows the case of the magnetic recording medium of the present invention, and (b) shows a single magnetic layer. 5C shows the case of the magnetic recording medium, FIG. 5F shows the case of the magnetic recording medium of FIG. 5F (the magnetic material is a hard magnetic layer / soft magnetic layer two-layer structure), and FIG. 6D shows the magnetic recording medium of FIG. The case where the magnetic body is a soft magnetic layer / hard magnetic layer / soft magnetic layer three-layer structure) is shown. FIG. 5A is a process diagram for explaining a base material forming process in a conventional method of manufacturing a magnetic recording medium. FIG. 5B is a process diagram for explaining a nanohole forming process in the conventional method of manufacturing a magnetic recording medium. FIG. 5C is a process diagram for explaining the soft magnetic plating process in the conventional method of manufacturing a magnetic recording medium. FIG. 5D is a process diagram for describing a hard magnetic material plating process in a conventional method of manufacturing a magnetic recording medium. FIG. 5E is a process diagram for explaining a polishing process in the conventional method of manufacturing a magnetic recording medium. FIG. 5F is a process diagram for explaining a protective film formation process (lubricant application process) in a conventional method of manufacturing a magnetic recording medium. FIG. 6A is a process diagram for explaining a base material forming process in a conventional method of manufacturing a magnetic recording medium. FIG. 6B is a process diagram for explaining a nanohole forming process in the conventional method of manufacturing a magnetic recording medium. FIG. 6C is a process diagram for explaining a soft magnetic material plating process in a conventional method of manufacturing a magnetic recording medium. FIG. 6D is a process diagram for describing a hard magnetic material plating process in a conventional method of manufacturing a magnetic recording medium. FIG. 6E is a process diagram for explaining a soft magnetic plating process in the conventional method of manufacturing a magnetic recording medium. FIG. 6F is a process diagram for describing a polishing process in a conventional method of manufacturing a magnetic recording medium. FIG. 6G is a process diagram for explaining a protective film formation process (lubricant application process) in a conventional method of manufacturing a magnetic recording medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Adhesion layer 3 Underlayer soft magnetic layer 4 Oxidation stop layer 5 Base material 5a Anodized alumina 6 Ferromagnetic material 7 Protective film (lubricant layer)
8 Magnetic nano-pillar part

Claims (6)

A base material forming step of forming a base material on the substrate;
A nanohole forming step of forming nanoholes in the substrate;
A magnetic material filling step of filling the nanohole with a magnetic material;
A polishing step of polishing the magnetic material overflowing from the nanohole;
An ion implantation step of implanting ions into the base material from the polishing surface in the polishing step toward the substrate side;
A method for manufacturing a magnetic recording medium, comprising:   The method of manufacturing a magnetic recording medium according to claim 1, wherein a hard magnetic material is filled as the magnetic body.   3. The magnetic recording medium according to claim 1, wherein, in the ion implantation step, ions are implanted with energy at a substrate side end portion of the magnetic material filled in the nanohole being Ra of an implantation ion distribution curve by TRIM simulation. Manufacturing method.   4. The method of manufacturing a magnetic recording medium according to claim 2, wherein the magnetic material filled in the nanohole is one of Co and a Co alloy, and the implanted ions are Fe ions.   4. The method of manufacturing a magnetic recording medium according to claim 2, wherein the magnetic material filled in the nanohole is one of Ni and a Ni alloy, and the implanted ions are Fe ions.   A magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to claim 1, wherein the substrate, the base material on which the nanoholes are formed, and the nanoholes are filled. A magnetic recording medium characterized in that the coercive force of the magnetic material filled in the nanoholes continuously increases from the substrate side toward the base material side.