WO2009119829A1 - 垂直磁気記録媒体、垂直磁気記録媒体の製造方法、および磁気記録再生装置 - Google Patents
垂直磁気記録媒体、垂直磁気記録媒体の製造方法、および磁気記録再生装置 Download PDFInfo
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- WO2009119829A1 WO2009119829A1 PCT/JP2009/056355 JP2009056355W WO2009119829A1 WO 2009119829 A1 WO2009119829 A1 WO 2009119829A1 JP 2009056355 W JP2009056355 W JP 2009056355W WO 2009119829 A1 WO2009119829 A1 WO 2009119829A1
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/855—Coating only part of a support with a magnetic layer
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- the present invention relates to a perpendicular magnetic recording medium used in a hard disk device or the like, a method of manufacturing a perpendicular magnetic recording medium, and a magnetic recording / reproducing apparatus including the perpendicular magnetic recording medium.
- the crystal grain size of the magnetic particles constituting the magnetic layer is often fine. While being fine is effective in reducing medium noise, from the viewpoint of thermal stability of magnetism, being fine is considered to be a state close to an unstable region. The above property is considered to be one of the reasons why the thermal stability is lowered when trying to improve the SN ratio.
- the magnetic recording apparatus is required to have an extremely accurate track servo technology.
- a method of performing a narrower track width than that at the time of recording is generally used in order to perform recording widely and to eliminate as much influence from adjacent tracks as possible when performing reproduction.
- this method can minimize the influence between tracks, but it is difficult to obtain a sufficient reproduction output. Therefore, there is a problem that it is difficult to ensure a sufficient SN ratio.
- a perpendicular magnetic recording medium generally has, for example, a substrate, a soft magnetic bottom layer (SUL), an intermediate layer, a perpendicular magnetic recording layer, and a protective film as necessary, in order, and a technique for increasing the recording density. It is used as.
- SUL soft magnetic bottom layer
- an intermediate layer a perpendicular magnetic recording layer
- a protective film as necessary, in order, and a technique for increasing the recording density. It is used as.
- even higher recording density is required for this perpendicular magnetic recording medium.
- One method for solving the fringe problem is a discrete track medium (see, for example, Patent Documents 1 and 2).
- Patent Document 1 describes a disc-shaped medium in which a recording part for recording data is a convex part and a guard band part for separating adjacent recording parts is a concave part.
- the convex part and the concave part may be understood as a high part and a low part, for example, a peak part and a valley part.
- Patent Document 2 discloses a recording track portion made of a magnetic member and a guard band portion between adjacent recording track portions, and is formed of a nonmagnetic material provided in the guard band portion.
- a magnetic disk having a separated region member has been proposed.
- an oxide, nitride, carbide, or boride, or a polymer compound of any one of C, CH, and CF is used as the separation region member.
- Patent Document 2 sputtering is performed until the guard band space is filled, so that the disk surface is covered with the SiO 2 film, and then the SiO 2 film is polished until the upper surface of the recording magnetic member of the recording track portion is exposed.
- sputtering is performed until the guard band space is filled, so that the disk surface is covered with the SiO 2 film, and then the SiO 2 film is polished until the upper surface of the recording magnetic member of the recording track portion is exposed.
- the recording portion is a convex portion and the guard band is a concave portion, there are irregularities on the disc surface.
- a disk-shaped medium having irregularities on the disk surface has a problem that the irregularities on the surface affect the flying characteristics of the recording / reproducing head.
- the magnetic disk described in Patent Document 2 is preferable in that there is no step between the recording magnetic member and the separation region member, so that the flying characteristics of the recording / reproducing head are not affected by the unevenness of the surface.
- a protective film may be formed on the surface after etching.
- the surface of the separation region member after etching is already rough, even if a protective film is formed on the surface of the product after etching, the surface smoothness may not be sufficiently obtained.
- a metal is used for the separation region, there is a problem that the surface of the film formed by sputtering or the like becomes non-uniform and it is difficult to flatten the surface.
- the magnetic disk including the separation region member using a nonmagnetic material described in Patent Document 2 has a problem that the surface is easily scratched due to the polishing process.
- the surface tends to be easily damaged when the magnetic head is accidentally collided after being incorporated in the magnetic recording / reproducing apparatus.
- a protective film may be formed on the surface of the magnetic disk.
- the protective film cannot withstand the collision of the magnetic head with the surface of the magnetic disk, and the surface could hurt.
- the present invention has been made in view of the above circumstances.
- the present invention is excellent in the smoothness of the surface of the separation region, can realize a high recording density, has no blurring of writing by a magnetic head, and has a stable electromagnetic conversion characteristic for a long time when provided in a magnetic recording / reproducing apparatus.
- the present invention comprises the perpendicular magnetic recording medium of the present invention, is excellent in the smoothness of the surface of the separation region, can realize a high recording density, has no blurring of writing by a magnetic head, and has stable electromagnetic conversion characteristics over a long period of time. It is an object of the present invention to provide a magnetic recording / reproducing apparatus having excellent impact resistance against a collision of a magnetic head or the like.
- the present inventor has found that the material of the granular structure has a fine crystal structure, so that the separation region portion becomes a separation region portion by making the structure including the material of the granular structure. It has been found that etching and / or polishing proceeds uniformly when the film is etched and / or polished. As a result, it has been found that the problem of surface roughness of the separation region portion after etching and / or polishing can be solved, and a separation region portion surface that is smooth and excellent in environmental resistance can be obtained. Further investigation by the inventor of the present application reveals that when a material having a granular structure is etched using a dry process, the surface becomes smooth as the etching proceeds even if the initial surface is uneven. It was.
- the inventor of the present application has a structure in which the recording portion includes a magnetic layer formed from a magnetic material having a granular structure, and further, a separation region portion is formed from a material having a granular structure. It is possible to prevent mutual diffusion of constituent elements in the separation region portion and the magnetic layer by approximating the composition of the material constituting the separation region portion and the composition of the material constituting the magnetic layer as necessary, as well as the structure. It has been found that the impact resistance against a collision of a magnetic head or the like can be improved.
- the first aspect of the present invention is the following recording medium.
- a recording layer having magnetic anisotropy in a direction perpendicular to the surface of the nonmagnetic substrate is formed on the nonmagnetic substrate,
- the recording layer is a perpendicular magnetic recording medium having a plurality of recording units and a plurality of separation region units separating the adjacent recording units, 2.
- Preferred examples of the recording medium of the first aspect will be described below.
- the recording portion is a laminated body and includes a magnetic layer formed of a magnetic material having a granular structure.
- the magnetic layer and the separation region include the same oxide.
- the magnetic layer and the separation region include Cr.
- the magnetic layer and the separation region include an oxide within a range of 5 to 40% by volume.
- the magnetic layer and the separation region are formed of SiO 2 , SiO, Cr 2 O 3 , CoO, Ta 2 O 3 , and TiO. It is preferable to include any one or more of 2 .
- the magnetic layer is disposed as an uppermost layer of the recording unit, and the recording unit and the separation are disposed on the recording layer. It is preferable that a protective film covering the region portion is formed.
- the second aspect of the present invention is the following method for manufacturing a perpendicular magnetic recording medium. (9): A recording layer having magnetic anisotropy in a direction perpendicular to the nonmagnetic substrate surface is formed on the nonmagnetic substrate, and the recording layer includes a plurality of recording units and the adjacent recording unit.
- a method of manufacturing a perpendicular magnetic recording medium having a plurality of separation region portions to be separated A recording layer forming step of forming a recording layer having magnetic anisotropy in a direction perpendicular to the nonmagnetic substrate surface on the nonmagnetic substrate; A groove forming step of forming a plurality of recording portions and a plurality of grooves separating the adjacent recording portions by removing a region to be the separation region portion from the recording layer to form a groove.
- Filling the groove with a material having a granular structure to form a separation region portion Preferred examples of the recording medium of the second aspect will be described below.
- the material of the granular structure described in the above (9) is preferably a nonmagnetic material.
- the recording unit includes a magnetic layer formed of a magnetic material having a granular structure.
- the step of filling the concave groove has the granular structure on the recording layer in which the concave groove is formed.
- the method for manufacturing a perpendicular magnetic recording medium according to (12) preferably includes a step of forming a protective film covering the recording portion and the separation region portion on the recording layer.
- the step of forming the concave groove includes applying a resist on the recording layer to form a resist layer, It is preferable that a step of removing the region of the resist layer to be the separation region portion and removing the region of the recording layer from which the resist layer has been removed is preferably used.
- the groove is filled with a material having a granular structure using a sputtering method in the step of filling the groove. Is preferred.
- the surface on which the nonmagnetic layer is formed is planarized using an ion beam etching method in the planarization step. preferable.
- a third aspect of the present invention is the following method for manufacturing a perpendicular magnetic recording medium.
- a magnetic recording / reproducing apparatus comprising a magnetic recording medium and a magnetic head for recording / reproducing information on / from the magnetic recording medium, wherein the magnetic recording medium is described in any one of (1) to (8)
- a magnetic recording / reproducing apparatus characterized by being a perpendicular magnetic recording medium.
- FIG. 1A is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1B is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1C is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1D is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1E is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1F is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1G is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1H is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1I is a diagram for explaining an example of the perpendicular magnetic recording medium of the present invention and the method for manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 2 is a perspective view showing an example of a hard disk device as the magnetic recording / reproducing apparatus of the present invention.
- a perpendicular magnetic recording medium 1 non-magnetic substrate, 2 Soft magnetic backing layer, 3 Orientation control layer 4 Magnetic layer 6 Recording layer 7 Resist layer 8 Medium 9 Stamper 9a Concave portion 10 Concave portion 11b Concave portion 12 Nonmagnetic layer 14 Separating region portion 15 Recording portion 16 Protective film 17 Lubricating layer
- a recording layer having magnetic anisotropy in the direction perpendicular to the nonmagnetic substrate surface is formed on a nonmagnetic substrate, and the recording layer is adjacent to the plurality of recording portions.
- the perpendicular magnetic recording medium has a separation region portion for separating the recording portion, and the separation region portion is made of a material having a granular structure, preferably a non-magnetic material. For this reason, the isolation
- the material having the granular structure has a fine crystal structure
- the separation region portion Etching and / or polishing of the film to be progressed uniformly.
- the problem of the rough surface of the separation region portion that occurs after etching and / or polishing is solved, and a separation region portion having a smooth and excellent surface resistance is obtained.
- a recording layer having magnetic anisotropy in the direction perpendicular to the nonmagnetic substrate surface is formed on a nonmagnetic substrate, and the recording layer is adjacent to a plurality of recording portions. Since the recording area is separated from the recording area, a high recording density can be realized. Further, when it is provided in a magnetic recording / reproducing apparatus, it is excellent with little writing blurring by a magnetic head. It is also possible to increase the track density.
- the recording portion includes a magnetic layer made of a magnetic material having a granular structure
- the separation region portion is made of a non-magnetic material having a granular structure.
- mutual diffusion of constituent elements in the separation region portion and the magnetic layer can be prevented. Therefore, by using such a perpendicular magnetic recording medium, a stable electromagnetic conversion characteristic can be obtained for a long time when the magnetic recording / reproducing apparatus is provided.
- the hardness and density of the separation region portion and the magnetic layer can be approximated. If both a soft part and a hard part exist, generally the soft part will be the starting point of a crack. However, in the present invention, the difference in hardness and density in the recording portion is small and the above-mentioned starting point is unlikely to occur. For this reason, it is excellent in impact resistance against a collision of a magnetic head or the like.
- the recording becomes a base layer of the protective film and supports the protective film
- the hardness and density of the portion and the separation region portion are close to each other. Therefore, as described above, the protective film is less likely to be damaged because it is difficult to start a crack, and the impact resistance is further improved.
- the recording portion includes a magnetic layer made of a magnetic material having a granular structure
- the separation region portion is made of a non-magnetic material having a granular structure.
- the etching rate and polishing rate between the separation region portion and the magnetic layer can be approximated.
- a continuous smooth surface can be formed on the separation region portion and the magnetic layer, and a recording layer having excellent surface smoothness can be easily obtained.
- the flying height of the magnetic head can be reduced when the perpendicular magnetic recording medium is provided in a magnetic recording / reproducing apparatus.
- the perpendicular magnetic recording medium manufacturing method of the present invention can manufacture the perpendicular magnetic recording medium of the present invention.
- the magnetic recording / reproducing apparatus of the present invention since the magnetic recording / reproducing apparatus of the present invention includes the perpendicular magnetic recording medium of the present invention, it has excellent smoothness on the surface of the separation region, can achieve a high recording density, has no blurring of writing by the magnetic head, and lasts for a long time. Stable electromagnetic conversion characteristics and excellent shock resistance against collisions of magnetic heads.
- Magnetic recording media 1A to 1I are diagrams for explaining an example of the perpendicular magnetic recording medium of the present invention and the method of manufacturing the perpendicular magnetic recording medium of the present invention.
- FIG. 1I is an enlarged sectional view showing a perpendicular magnetic recording medium of the present invention. In FIG. 1I, only a part of the disk-shaped perpendicular magnetic recording medium is shown enlarged.
- a perpendicular magnetic recording medium A shown in FIG. 1I includes a nonmagnetic substrate 1, a recording layer 6 formed on the nonmagnetic substrate 1, a protective film 16 formed on the recording layer 6, and a protective film 16 And a lubricating layer 17 formed thereon.
- the recording layer 6 has magnetic anisotropy in a direction perpendicular to the surface of the non-magnetic substrate 1 and, as shown in FIG. 15 and a separation region portion 14 for separating 15.
- the recording portion 15 is a recording track portion or a bit portion formed with a concentric predetermined width, and as shown in FIG. 1 (I), the soft magnetic underlayer 2, the orientation control layer 3, the magnetic layer 4, Are sequentially stacked.
- the magnetic layer 4 is disposed as the uppermost layer in the recording unit 15. Therefore, the upper surface of the recording layer 6 is composed of the surface portion of the magnetic layer 4 and the surface portion of the separation region portion 14.
- the upper surface of the recording portion 15 (the upper surface of the magnetic layer 4) and the upper surface of the separation region portion 14 are covered with a protective film 16. As shown in FIG. 1 (I), there is no step at the boundary between the magnetic layer 4 and the separation region portion 14, and the surface of the recording layer 6 is the surface portion of the magnetic layer 4 and the surface portion of the separation region portion 14.
- the surface roughness (Ra) of the recording layer 6 is preferably smaller, specifically 1 nm or less, more preferably 0.5 nm or less, and even more preferably 0.3 nm or less.
- the nonmagnetic substrate 1 can be selected as necessary. Any non-magnetic substrate such as an Al alloy substrate mainly composed of Al, such as an Al—Mg alloy, or a substrate made of crystallized glass, amorphous glass, silicon, titanium, ceramics, carbon, or various resins Can be selected and used. As the substrate made of crystallized glass, a lithium-based crystallized substrate can be used, and as the substrate made of amorphous glass, a soda lime glass or aluminosilicate glass substrate can be given. The average surface roughness Ra of the nonmagnetic substrate 1 is preferably small.
- the thickness of the substrate can be selected as required.
- the soft magnetic backing layer 2 is formed from a soft magnetic material.
- a material containing at least one of Fe, Co, and Ni can be given as a material for the soft magnetic backing layer 2.
- the material containing Fe, Co, and / or Ni used for the soft magnetic underlayer 2 include FeCo alloys (FeCoB, FeCoSiB, FeCoZr, and FeCoZrB), FeTa alloys (FeTaN, FeTaC, and the like), and Co alloys (CoTaZr). , CoZrNb, and CoB).
- the soft magnetic backing layer 2 may be a single layer, but preferably has a laminated structure. Although it may be designed as necessary, for example, a layer made of any one of Ru, Re, and Cu is provided between two soft magnetic films, and a predetermined thickness is provided, so that the layers are provided above and below.
- the soft magnetic film can be antiferromagnetically coupled. By making the soft magnetic underlayer 2 have such a laminated structure, it is possible to improve the phenomenon of WATE (Wide Area Track Erasure), which is a problem peculiar to the perpendicular magnetic recording medium.
- the thickness of the soft magnetic backing layer 2 can be selected as necessary, but is preferably 10 to 200 nm, more preferably 20 to 100 nm.
- the orientation control film 3 is provided as an underlayer for the magnetic layer 4 in order to control the crystal orientation and crystal size of the magnetic layer 4.
- the material used for the orientation control film 3 may be selected as necessary, but an element having an hcp structure or an fcc structure is preferable, and Ru is particularly preferable.
- the thickness of the orientation control film 3 is preferably 30 nm or less. If the thickness of the orientation control film 3 exceeds 30 nm, the magnetic head and soft magnetic backing during recording / reproduction are obtained in the magnetic recording / reproducing apparatus provided with the perpendicular magnetic recording medium A as shown in FIG. Since the distance to the layer 2 is increased, the OW (overwrite) characteristics and the resolution of the reproduction signal are lowered, which is not preferable.
- the thickness of the orientation control film 3 can be selected as necessary, but is preferably 1 to 100 nm, and more preferably 10 to 50 nm.
- the magnetic layer 4 is preferably composed of a magnetic material having a granular structure.
- the magnetic material having a granular structure means a structure in which a plurality of magnetic material particles are dispersed in an oxide as a matrix. In other words, it has a structure in which an oxide covers the periphery of a plurality of magnetic material particles.
- the magnetic material particles may have a columnar shape, but may have other shapes such as a spherical shape other than the columnar shape.
- the magnetic material particles may be larger than the thickness of the magnetic layer 4.
- the magnetic material particles may have a columnar shape that penetrates the magnetic layer 4 and is larger than the thickness of the magnetic layer 4.
- the magnetic material particles may be formed of a material selected as necessary.
- Preferable examples include materials containing Co, Cr, and / or Pe.
- the shape and size of the magnetic material particles can be selected as necessary.
- a preferable shape includes a columnar shape.
- a preferred size is about 1 to 50 nm in length and 1 to 10 nm in width.
- the magnetic layer 4 preferably contains magnetic material particles in a range of 99 to 70 at%, more preferably in a range of 95 to 85 at%.
- the magnetic material having a granular structure in the present invention may be a material having a structure in which the periphery of the magnetic material particles is completely covered with an oxide, but only a part of the material is covered with an oxide. There may be.
- a material having a structure in which only the side surfaces of the magnetic material particles are covered with the oxide so as to include columnar crystals (magnetic material particles) penetrating up and down the oxide layer may be used.
- the magnetic material of the granular structure constituting the magnetic layer 4 can be selected as necessary, but it is particularly preferable to use a magnetic material containing at least Co, Pt and an oxide.
- the amount of Co is selected as necessary, but is preferably 50 to 80 atomic% with respect to the entire magnetic material particle.
- the amount of Pt is preferably 10 to 20 atomic% with respect to the entire magnetic material particle.
- elements such as Cr, B, Cu, Ta, and Zr may be added to the magnetic material as necessary for the purpose of improving SNR characteristics (S / N ratio). The amounts of these elements are selected as necessary, but each is preferably 5 to 25 atomic% with respect to the entire magnetic material particles.
- the oxide contained in the magnetic material having the granular structure constituting the magnetic layer 4 can be selected as necessary.
- one or more of SiO 2 , SiO, Cr 2 O 3 , CoO, Ta 2 O 3 , and TiO 2 can be used.
- the magnetic layer 4 preferably contains an oxide within a range of 15 to 40% by volume, more preferably within a range of 15 to 25% by volume. If the volume of the oxide is less than 15% by volume, the SNR characteristics may be insufficient, such being undesirable. On the other hand, when the volume of the oxide exceeds 40% by volume, there is a possibility that a coercive force sufficient for a high recording density cannot be obtained, which is not preferable.
- the nucleation magnetic field (-Hn) of the magnetic layer 4 is preferably 1.5 (kOe) or more. If ⁇ Hn is less than 1.5 (kOe), thermal fluctuation may occur, which is not preferable.
- the thickness of the magnetic layer 4 is preferably 6 to 18 nm. By setting the thickness of the magnetic layer 4 within the above range, it is preferable because sufficient output can be secured without causing deterioration of the OW characteristics.
- the separation region portion 14 is preferably made of a material having a granular structure.
- the material having the granular structure can be described as a non-magnetic material having a granular structure.
- the “nonmagnetic material” and “nonmagnetic material particles” do not have to be completely nonmagnetic magnetically.
- “non-magnetic material” and “non-magnetic material particles” are magnetic to a degree sufficient to separate the magnetic recording portion and to allow magnetic recording and reproduction to the magnetic recording portion. It is a material with reduced That is, the non-magnetic material is a material having lower magnetism than the magnetic material of the magnetic recording portion.
- the material having a granular structure used in the separation region means a structure in which a plurality of material particles, that is, nonmagnetic material particles are dispersed in an oxide as a matrix. In other words, it has a structure in which a plurality of nonmagnetic material particles are covered with an oxide.
- the nonmagnetic material particles may be spherical, but may be other shapes such as non-spherical or columnar.
- the nonmagnetic material particles may be larger than the thickness of the separation region portion 14, and the nonmagnetic material particles may have a columnar shape that penetrates the separation region portion 14 and is larger than the thickness of the magnetic layer 4.
- the nonmagnetic material particles may be formed of a material selected as necessary, and preferred examples include materials containing Co, Cr, and / or Pe.
- the size and shape may be selected as necessary, but preferred sizes are about 1 to 50 nm in length and about 1 to 10 nm in width.
- the separation region 14 preferably contains the material particles in the range of 99 to 70 at%, more preferably in the range of 95 to 85 at%.
- the oxide contained in the nonmagnetic material having a granular structure can be selected as necessary.
- the non-magnetic material having a granular structure in the present invention may be a material having a structure in which the periphery of the non-magnetic material particles is completely covered with oxide, but only a part of the structure is covered with oxide. It may be a material. For example, a material having a structure in which only the side surfaces of the nonmagnetic material particles are covered with an oxide may be used.
- the material of the granular structure constituting the separation region portion 14 it is more preferable to use a granular non-magnetic material containing at least Cr. Since the granular structure material containing Cr is easy to dry-etch, the separation region portion 14 having a smooth and excellent surface with excellent environmental resistance can be easily obtained.
- the proportion of Cr can be selected as necessary, but it is preferably 25 to 50 atomic% with respect to the nonmagnetic particles. If the amount is not large, an element showing magnetism may be included.
- the oxide contained in the nonmagnetic material having a granular structure include one or more of SiO 2 , SiO, Cr 2 O 3 , CoO, Ta 2 O 3 , and TiO 2 .
- the separation region portion 14 preferably contains an oxide within a range of 15 to 40% by volume, more preferably within a range of 20 to 30% by volume.
- the same oxide is used for the material constituting the magnetic layer 4 and the material constituting the separation region portion 14.
- the size of the covalent bond between oxygen and the element constituting the oxide is reduced between the magnetic layer 4 and the separation region portion 14 due to the difference in the included oxide.
- interdiffusion of oxygen atoms caused by the difference in the size of the covalent bond between oxygen and the element constituting the oxide that is, from the oxide of the recording track portion 15.
- the movement of oxygen atoms to the separation region portion 14 or the movement of oxygen atoms from the oxide in the separation region portion 14 to the recording track portion 15 is less likely to occur.
- (2) Cr is included as one of the material composing the magnetic layer 4 and the material composing the separation region portion 14.
- Cr when the magnetic recording / reproducing apparatus including the perpendicular magnetic recording medium A as shown in FIG. 1I is used, the SNR characteristics can be improved, and the magnetic layer 4 and the isolation region 14 are dry etched. Becomes easy. As a result, when the separation region portion 14 and the magnetic layer 4 are simultaneously dry-etched, the recording layer 6 having excellent surface smoothness can be easily obtained.
- the material constituting the magnetic layer 4 and the material constituting the separation region portion 14 contain an oxide within a range of 5 to 40% by volume, preferably within a range of 10 to 20% by volume.
- the amount of oxide is preferably the same or close to each other, but may be different within this range.
- the etching rate and polishing rate between the separation region portion 14 and the magnetic layer 4 can be further approximated. Therefore, when the separation region portion 14 and the magnetic layer 4 are etched and / or polished simultaneously, a step is not generated at the boundary portion between the separation region portion 14 and the magnetic layer 4, and the magnetic field on the separation region portion 14 is not affected. It is possible to easily form a continuous smooth surface on the layer 4.
- any one or more of SiO 2 , SiO, Cr 2 O 3 , CoO, Ta 2 O 3 , and TiO 2 are used.
- the magnetic layer and the separation region portion preferably contain the same compound, but may contain different materials.
- the magnetic layer 4 has a granular structure, and magnetic particles can be isolated and miniaturized, and the magnetic characteristics of the magnetic layer 4 can be improved.
- the etching characteristics of the nonmagnetic material constituting the separation region portion 14 can be further improved, and a smooth etching surface can be obtained.
- Co, Pt, or the like may be added to the magnetic layer 4 and the separation region portion 14 in order to approximate the materials of the magnetic layer 4 and the separation region portion 14.
- the magnetic layer 4 can be a magnetic layer having a granular structure with better noise characteristics.
- the separation region portion 14 has a structure similar to that of the magnetic layer 4, and the etching characteristics of both can be made the same.
- Co, Pt, or the like is added to the magnetic layer 4 and the separation region portion 14, the nonmagnetic particles in the separation region portion 14 are preferably a Cr alloy containing Co as the first main component.
- the protective film 16 can be selected as necessary. What is used as a protective film of a general magnetic recording medium can be appropriately used. For example, a thin film of DLC (Diamond Like Carbon) is used. In addition to the DLC thin film, the protective layer 16 is made of a carbonaceous layer such as C, hydrogenated C, nitrogenated C, Almophas C, or SiC, SiO 2 , Zr 2 O 3 , or TiN. A thin film can be used. The protective layer 16 may be composed of two or more thin film layers. The thickness of the protective layer 16 is preferably 1 to 10 nm, more preferably 1 to 5 nm, and it is preferably set as thin as possible within a range that can ensure sufficient durability.
- DLC Diamond Like Carbon
- the lubricant layer 17 may be selected as necessary, and may be formed using a material selected from a fluorine-based lubricant, a hydrocarbon-based lubricant, and a mixture thereof.
- the thickness of the lubricating layer 17 may be selected as necessary, but is usually 1 to 4 nm.
- FIG. 1A is an enlarged cross-sectional view showing a state in which a recording layer is formed on a nonmagnetic substrate.
- FIG. 1B is an enlarged cross-sectional view showing a state in which a resist layer is formed on the recording layer.
- FIG. 1C is an enlarged cross-sectional view showing a state in which the resist layer portion corresponding to the region to be the separation region portion is removed using a stamper.
- FIG. 1D is an enlarged cross-sectional view showing a state where the entire resist layer is removed and a plurality of concave grooves for separating the recording portion into a plurality of portions are formed in the recording portion (recording layer).
- FIG. 1F is an enlarged cross-sectional view showing a state in which a layer of a non-magnetic material having a granular structure is deposited on a recording portion in which a concave groove is formed.
- FIG. 1G is an enlarged cross-sectional view showing a state where the surface of the nonmagnetic material layer is removed and the surface of the recording layer is smoothed.
- FIG. 1H is an enlarged cross-sectional view showing a state in which a protective layer is formed on the smoothed surface of the recording layer.
- a soft magnetic backing layer 2 and an orientation control layer 3 are formed on a disk-like nonmagnetic substrate 1. And the magnetic layer 4 are sequentially formed to form a recording layer 6 that is a laminate (recording layer forming step).
- a mask layer 5 made of carbon is provided on the recording layer 6 by sputtering, CVD, or the like.
- the mask layer 5 is provided as necessary in order to more reliably shield the portion of the recording layer 6 that becomes the recording portion 15 when the portion of the recording layer 6 corresponding to the separation region portion 14 is removed.
- a resist is applied on the recording layer 6 provided with the mask layer 5 to form a medium 8 on which the resist layer 7 is formed, as shown in FIG.
- the resist used for forming the resist layer 7 can be selected as necessary, and industrially used photoresists can be widely used.
- the resist layer 7 is usually formed by a method in which a resist is thinly and uniformly applied using spin coating or the like and then baked at a predetermined temperature and time using an oven as necessary to remove unnecessary organic solvents. Can be formed. Note that the method of forming the resist layer 7 may be appropriately adjusted according to the properties of the resist to be used.
- the stamper 9 is brought into close contact with the surface of the medium 8 and pressed at a high pressure to remove a portion of the resist layer 7 in a region to be the separation region portion 14, as shown in FIG.
- the stamper 9 can be selected as necessary.
- it is a disk-shaped stamper that matches the disk-shaped non-magnetic substrate 1, and has a concave portion 9a corresponding to the surface shape of the recording section 15 of the perpendicular magnetic recording medium A shown in FIG. Etc. can be used.
- the stamper 9 is obtained, for example, by forming a fine recess 9a shape on a metal plate using a method such as electron beam drawing.
- the material of the stamper 9 is not particularly limited as long as it has sufficient hardness and durability.
- a metal such as Ni is used.
- the recording layer 6 and the mask layer 5 in the region from which the resist layer 7 has been removed are formed by using an ion beam etching (IBE) method or ion milling.
- IBE ion beam etching
- a plurality of recording portions 15 including the magnetic layer 4 and a plurality of concave grooves 11b separating the adjacent recording portions 15 are formed.
- the resist layer 7 remaining on the recording portion 15 is removed (concave groove forming step).
- the shape, position, and size of the recording unit 15 and the groove 11b are selected as necessary.
- the recording layer 6 obtained here has a structure in which the recording portions 15 and the concave grooves 11b positioned between the recording portions 15 are alternately formed in the diameter direction.
- the mask layer 5 remaining on the recording portion 15 is removed by oxygen plasma etching, ion milling, or the like.
- a nonmagnetic material having a granular structure is deposited on the recording layer 6 in which the concave groove 11b is formed to form a nonmagnetic layer 12 (nonmagnetic layer forming step).
- the groove 11b is filled with a non-magnetic material having a granular structure to form the separation region portion 14 (groove filling process).
- the non-magnetic layer 12 is made of a non-magnetic material having a granular structure, even when the initial surface of the non-magnetic layer 12 before planarization is uneven and uneven, as the planarization by polishing or etching progresses, Unevenness is relaxed and the surface can be smoothed.
- the removal thickness of the magnetic layer 4 that is removed simultaneously with the nonmagnetic layer 12 is not particularly limited. For example, it is preferable to remove 1 nm or more so that the planarization effect of removing the nonmagnetic layer 12 and the magnetic layer 4 simultaneously can be sufficiently obtained.
- the performance of the obtained perpendicular magnetic recording medium A is not impaired, and the surface of the recording layer 6 including the recording portion 15 and the separation region portion 14 is sufficient to be used for the perpendicular magnetic recording medium A.
- Any method may be used as long as it can be processed so smoothly. For example, polishing by a CMP (Chemical Mechanical Polish) method or dry etching such as an ion beam etching method can be used, but an ion beam etching method is preferably used.
- polishing by a CMP (Chemical Mechanical Polish) method or dry etching such as an ion beam etching method can be used, but an ion beam etching method is preferably used.
- a DLC film which is a protective film 16 that covers the planarized recording portion 15 and separation region portion 14, is formed using a film forming method such as a plasma CVD method.
- a film forming method such as a plasma CVD method.
- the lubricating layer 17 is further formed on the protective film 16 to obtain the perpendicular magnetic recording medium A shown in FIG.
- a recording layer 6 having magnetic anisotropy in the direction perpendicular to the surface of the nonmagnetic substrate 1 is formed on the nonmagnetic substrate 1, and the recording layer 6 includes a plurality of recording layers. Part 15 and separation region part 14 for separating adjacent recording parts 15.
- the recording portion 15 includes a magnetic layer 4 preferably made of a magnetic material having a granular structure
- the separation region portion 14 is made of a non-magnetic material having a granular structure
- the separation region portion 14 Since the separation region portion 14 is made of a non-magnetic material having a granular structure, the separation region portion 14 has a fine crystal structure. Since the crystal structure is fine, the progress of etching becomes uniform. As a result, when the nonmagnetic layer 12 is etched and / or polished to obtain the separation region portion 14, the nonmagnetic layer 12 is uniformly etched and / or polished. Can progress. After the etching and / or polishing, the separation region portion 14 having a smooth surface with excellent environmental resistance is obtained.
- the perpendicular magnetic recording medium A of the present embodiment is unlikely to cause mutual diffusion of constituent elements between the separation region portion 14 and the magnetic layer 4, and when it is provided in a magnetic recording / reproducing apparatus, writing with a magnetic head is possible. There is little blur.
- the composition of the material of the separation region portion 14 and the magnetic layer 4 can be approximated, the hardness and density of the separation region portion 14 and the magnetic layer 4 can also be approximated. As a result, the hardness and density of the entire surface can be made substantially uniform, the impact resistance of the surface of the recording layer 6 composed of the separation region portion 14 and the magnetic layer 4 is improved, and the resistance to collision of the magnetic head and the like is improved. Excellent impact properties. Further, in the perpendicular magnetic recording medium A of the present embodiment, the magnetic layer 4 is disposed on the uppermost layer of the recording unit 15 and the protective film 16 that covers the recording unit 15 and the separation region unit 14 is provided.
- the recording portion 15 and the separation region portion 14 that serve as the underlayer 16 and support the protective film 16 have similar hardness and density. Therefore, the protective film 16 can absorb the impact uniformly over the entire surface when the magnetic head or the like comes in contact with it, and is very resistant to damage and has excellent impact resistance. Therefore, the perpendicular magnetic recording medium A has very excellent impact resistance.
- the method for manufacturing the perpendicular magnetic recording medium A of the present embodiment can manufacture the perpendicular magnetic recording medium A of the present embodiment.
- a smooth surface in which the separation region portion 14 and the magnetic layer 4 are continuous can be obtained.
- the pattern shape including the recording portion 15 and the separation region portion 14 can be easily formed with high accuracy.
- FIG. 2 is a perspective view showing a hard disk device as an example of the magnetic recording / reproducing apparatus of the present invention.
- the magnetic recording / reproducing apparatus B shown in FIG. 2 includes a rectangular box-shaped housing 21 whose upper surface is open, and a top cover (not shown) that closes the opening of the housing 21.
- a perpendicular magnetic recording medium A shown in FIG. 1 (I) a spindle motor 23, a magnetic head 24 (single pole head), a head actuator 25, a voice coil motor 27, and a head amplifier circuit are provided. 28 are housed.
- the spindle motor 23 is a driving unit that supports and rotates the perpendicular magnetic recording medium A.
- the magnetic head 24 includes a recording unit and a reproducing unit, and records and reproduces magnetic signals on the perpendicular magnetic recording medium A.
- the magnetic head 24 can be selected as necessary, and for example, a GMR head or a TMR head can be used. When a GMR head or a TMR head is used as the magnetic head 24, a sufficient signal intensity can be obtained even at a high recording density, and a magnetic recording / reproducing apparatus B having a high recording density can be realized.
- the flying height of the magnetic head 24 can be selected as necessary. For example, by setting the flying height to 0.005 ⁇ m to 0.020 ⁇ m, the output can be improved and a high device S / N ratio can be obtained. The magnetic recording / reproducing apparatus B having a large capacity and high reliability can be obtained.
- the head actuator 25 supports the magnetic head 24 movably with respect to the magnetic recording medium 22.
- the head actuator 25 has a suspension with a magnetic head 24 mounted at the tip thereof, and is rotatably supported by a rotating shaft 26.
- the voice coil motor 27 rotates and positions the head actuator 25 via the rotary shaft 26.
- the recording density can be further improved by combining the signal processing circuit based on the maximum likelihood decoding method. For example, a sufficient S / N ratio can be obtained even when recording and reproduction are performed at a track density of 100 kTPI or more, a linear recording density of 1000 kbpI or more, and a recording density of 100 Gbit / inch or more per square inch.
- a magnetic recording / reproducing apparatus B shown in FIG. 2 is an apparatus including the perpendicular magnetic recording medium A shown in FIG. Therefore, a high recording density can be realized, there is no blurring of writing by the magnetic head 24, stable electromagnetic conversion characteristics can be obtained over a long period of time, and the impact resistance against collision of the magnetic head 24 and the like is excellent.
- the perpendicular magnetic recording medium A shown in FIG. 1 (I) was manufactured by the manufacturing method described below.
- a non-magnetic substrate 1 a cleaned disk-shaped glass substrate for HD (Ohara Co., Ltd., outer diameter 0.85 inch) was prepared, and the vacuum was evacuated to 1.0 ⁇ 10 ⁇ 5 Pa or less in advance. Installed in the chamber. Then, 65Fe-25Co-10B (atomic%) is deposited on the nonmagnetic substrate 1 in an order of 50 nm without heating, Ru is 0.8 nm, and 65Fe-25Co-10B (atomic%) is deposited in the order of 50 nm. A backing layer 2 was formed.
- an orientation control layer 3 made of Ru and having a thickness of 20 nm was formed on the soft magnetic backing layer 2.
- a recording layer 6 was formed by further forming a 12 nm-thick magnetic layer 4 made of 65Co-10Cr-15Pt-10SiO 2 (atomic%) on the orientation control layer 3.
- the magnetic layer 4 has a granular structure in which magnetic material particles made of Co, Cr, and Pt are dispersed in SiO 2 .
- the nonmagnetic substrate 1 on which the recording layer 6 was formed was taken out from the vacuum chamber, and a 4 nm thick mask layer 5 made of carbon was formed on the recording layer 6. Thereafter, a resist was applied on the recording layer 6 on which the mask layer 5 was formed using spin coating. Thereafter, the resist-coated nonmagnetic substrate 1 was baked in a constant temperature bath at about 100 ° C. for 20 minutes to remove excess solvent, thereby obtaining a resist layer. Next, using a Ni stamper in which concentric concave portions having a track pitch of 150 nm are formed, the resist layer in the region to be the separation region portion 14 is removed, and a desired uneven portion is formed on the substrate 1. Formed.
- the nonmagnetic substrate 1 on which the resist layer having the concavo-convex portion is formed is placed in a high vacuum chamber, and a region where the resist layer is not formed (region to be the separation region portion 14) is formed using an ion beam etching method.
- the recording layer 6 and the mask layer 5 were removed to form concentric concave grooves 11b.
- the mask layer 5 and the resist layer 7 remaining on the recording portion 15 were removed.
- a 40Co-35Cr-15Pt-10SiO 2 (atomic%) film which is a nonmagnetic material having a granular structure, is deposited on the recording layer 6 in which the concave groove 11b is formed by using an RF (high frequency) sputtering method.
- This non-magnetic material has the same kind of elements as compared with the magnetic material, but exhibits non-magnetism because the amount of Co is small.
- the separation region portion 14 in which the non-magnetic material having a granular structure was filled in the concave groove 11b was formed. Having a granular structure can be confirmed by an SEM photograph or a TEM photograph. Subsequently, the surface of the nonmagnetic layer formed by ion beam etching was flattened, and about 1 nm was simultaneously removed from the surface of the nonmagnetic layer and the magnetic layer 4 to expose the magnetic layer 4.
- a protective film 16 made of a DLC film having a thickness of 4 nm is formed on the recording layer 6 by plasma CVD, and a lubricating layer 17 is formed on the protective film 16 by applying a lubricant of 2 nm.
- Comparative Examples 1 to 4 A perpendicular magnetic recording medium was fabricated in the same manner as in the above-described example except that SiO 2 , Si, Cr, or Cr 2 O 3 shown in Table 1 was used as the material of the separation region portion 14. In Comparative Example 1 to Comparative Example 4, the granular structure is of course not included in the separation region portion.
- the following evaluations were performed on the perpendicular magnetic recording media of Examples and Comparative Examples 1 to 4 thus obtained.
- the perpendicular magnetic recording media of Examples and Comparative Examples 1 to 4 were put in an oven in an environment of a temperature of 80 ° C. and a humidity of 80% and held for 720 hours.
- the signal-to-noise ratio (SNR) and coercive force (Hc) of the perpendicular magnetic recording media of Examples and Comparative Examples 1 to 4 were measured before and after placing in the oven. The results are shown in Table 1.
- a read / write analyzer RWA1632 manufactured by GUZIK and a spin stand S1701MP were used, a magnetic head using a shielded type head for the writing unit and a GMR element for the reproducing unit, and 160 kFCI and 960 kFCI.
- the rms value rootmean square-inches) when the above signal was written was evaluated.
- the perpendicular magnetic recording media of the examples have no scratches and excellent surface impact resistance.
- scratches are observed in the perpendicular magnetic recording media of Comparative Examples 1 to 4, and it can be seen that the impact resistance is low as compared with the Examples.
- smoothness is indirectly evaluated by the above-described impact resistance evaluation (scratch evaluation).
- the smoothness is excellent, there is no damage due to contact and no scratches are generated.
- the comparative example is inferior in smoothness, so damage due to contact is large, and the number of scratches generated is large.
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Abstract
Description
本願は、2008年3月28日に、日本に出願された特願2008-88146号に基づき優先権を主張し、その内容をここに援用する。
特に記録の熱的安定性は、大きな技術的課題である。とりわけ、前述のSN比を改善しようとすると、この熱的安定性が低下するケースが多いため、SN比と熱的安定性の2つの両立は、今後の開発の目標となっている。SN比に優れた媒体では、一般的に磁性層を構成する磁性粒子の結晶粒サイズが微細であることが多い。微細である事は媒体ノイズの軽減に有効である反面、磁性の熱的安定性の観点からは、微細である事は不安定領域に近い状態であると考えられる。上記の性質が、SN比を改善しようとすると熱的安定性が低下する理由の一つとなっていると思われる。
以上のような高面記録密度の媒体において好ましいSN比を確保しつつかつ熱的安定性を確保するために、従来の面内磁気記録方式とは異なり、薄膜媒体の膜面に対して垂直方向に磁化記録を行う、垂直磁気記録媒体が近年用いられている。
フリンジの問題を解決する方法の一つとしては、ディスクリートトラック媒体が挙げられる(例えば、特許文献1、2参照)。
また、特許文献2には、磁性部材でつくられた記録トラック部と、互いに隣接する記録トラック部間にあるガードバンド部とを有し、かつガードバンド部内に設けられた非磁性の材料で形成された分離領域部材を具備する磁気ディスクが提案されている。また、特許文献2には、分離領域部材として、酸化物、窒化物、炭化物、又は硼化物を、あるいは、C系、CH系、及びCF系のうちのいずれかの重合化合物を、使用する事が例示されている。さらに、特許文献2には、ガードバンドスペースが埋まるまでスパッタすることにより、ディスク表面をSiO2膜で覆い、その後、記録トラック部の記録磁性部材の上面が露出するまでSiO2膜を研磨すると同時にSiO2膜を平坦化することにより、記録磁性部材および分離領域部材が交互に表面にあらわれたディスクを得る技術が記載されている。
一方、特許文献2に記載された磁気ディスクでは、記録磁性部材と分離領域部材との段差がないので、表面の凹凸による記録再生ヘッドの浮上特性への影響がないという点で好ましい。
また、特許文献2では、特許文献2の磁気ディスクを製造するために、分離領域部材を形成する膜を表面に設けた後、イオンビームエッチング等によって、記録磁性部材の上面が露出するまで、分離領域部材を形成する膜をエッチングして平坦化する。しかしながらこの時に、エッチング後の記録トラック部間にある分離領域部材の表面が荒れてしまい、表面の平滑性が不十分になるという問題があった。この問題を解決するためには、エッチング後の表面上に保護膜を形成することも考えられる。しかしながら、エッチング後の分離領域部材の表面既に荒れているため、エッチング後の製品の表面上に保護膜を形成したとしても、表面の平滑性が十分に得られない場合があった。また、分離領域部に金属を用いた場合でも、スパッタ等により成膜した膜表面に不均一が生じ、その平坦化が難しいという問題があった。
また、本発明は、本発明の垂直磁気記録媒体を備え、分離領域部表面の平滑性に優れ、高記録密度を実現でき、磁気ヘッドによる書きにじみがなく、長期に渡って安定した電磁変換特性が得られ、磁気ヘッドなどの衝突に対する耐衝撃性に優れた、磁気記録再生装置を提供することを目的とする。
(1):非磁性基板上に、前記非磁性基板面に対して垂直方向に磁気異方性を有する記録層が形成され、
前記記録層が、複数の記録部と、隣接する前記記録部を分離する複数の分離領域部と、を有する垂直磁気記録媒体であって、
前記分離領域部が、グラニュラー構造の材料から形成されることを特徴とする垂直磁気記録媒体。
第一の態様の記録媒体において好ましい例を以下に述べる。
(2):上記(1)に記載の分離領域部のグラニュラー構造の材料が、非磁性材料であることが好ましい。
(3):上記(1)に記載の垂直磁気記録媒体は、前記記録部が積層体であり、かつグラニュラー構造の磁性材料から形成される磁性層を含むことが好ましい。
(4):上記(2)に記載の垂直磁気記録媒体は、前記磁性層および前記分離領域部が、同一の酸化物を含むことが好ましい。
(5):上記(2)または(3)に記載の垂直磁気記録媒体は、前記磁性層および前記分離領域部が、Crを含むことが好ましい。
(6):上記(2)~(5)に記載の垂直磁気記録媒体は、前記磁性層および前記分離領域部が、5~40体積%の範囲内で酸化物を含むことが好ましい。
(7):上記(2)~(5)に記載の垂直磁気記録媒体は、前記磁性層および前記分離領域部が、SiO2、SiO、Cr2O3、CoO、Ta2O3、及びTiO2のいずれか一種以上を含むことが好ましい。
(8):上記(2)~(7)に記載の垂直磁気記録媒体は、前記記録部の最上層として前記磁性層が配置されており、前記記録層上には、前記記録部と前記分離領域部とを覆う保護膜が形成されていることが好ましい。
(9):非磁性基板上に、前記非磁性基板面に対して垂直方向に磁気異方性を有する記録層が形成され、前記記録層が、複数の記録部と、隣接する前記記録部を分離する複数の分離領域部とを有する、垂直磁気記録媒体の製造方法であって、
非磁性基板上に、非磁性基板面に対して垂直方向に磁気異方性を有する記録層を形成する記録層形成工程と、
前記記録層から、前記分離領域部となる領域を除去して凹溝を形成することによって、複数の記録部と、隣接する前記記録部を分離する複数の凹溝とを形成する凹溝形成工程と、
前記凹溝にグラニュラー構造の材料を充填し、分離領域部を形成する凹溝充填工程と、を含む。
第二の態様の記録媒体において好ましい例を以下に述べる。
(10):上記(9)に記載の、凹溝に充填されるグラニュラー構造の材料が、非磁性材料であることが好ましい。
(11):上記(9)に記載の垂直磁気記録媒体の製造方法は、前記記録部が、グラニュラー構造の磁性材料から形成される磁性層を含むが好ましい。
(12):上記(9)~(11)に記載の垂直磁気記録媒体の製造方法は、前記凹溝を充填する工程が、前記凹溝の形成された前記記録層上に、前記グラニュラー構造の材料を堆積させて、前記凹溝に前記材料が充填された非磁性層を形成する非磁性層形成工程と、
前記磁性層の表面が露出しかつ前記磁性層の表面の一部が除去されるまで、前記非磁性層を除去して、前記非磁性層の形成された表面上を平坦化する、工程とを備えることが好ましい。
(13):上記(12)に記載の垂直磁気記録媒体の製造方法は、前記記録層上に、前記記録部と前記分離領域部とを覆う保護膜を形成する工程を有することが好ましい。
(14):上記(9)~(13)に記載の垂直磁気記録媒体の製造方法は、前記凹溝を形成する工程が、前記記録層上にレジストを塗布してレジスト層を形成し、スタンパーを用いて、前記分離領域部となる前記レジスト層の領域を除去し、前記レジスト層が除去された前記記録層の領域を除去する工程を備えることが好ましい。
(15):上記(9)~(14)に記載の垂直磁気記録媒体の製造方法は、前記凹溝を充填する工程において、スパッタ法を用いて前記凹溝にグラニュラー構造の材料を充填することが好ましい。
(16):上記(11)に記載の垂直磁気記録媒体の製造方法は、前記平坦化する工程において、イオンビームエッチング法を用いて前記非磁性層の形成された表面上を平坦化することが好ましい。
(17):磁気記録媒体と、該磁気記録媒体に情報を記録再生する磁気ヘッドとを備えた磁気記録再生装置であって、前記磁気記録媒体が(1)~(8)のいずれかに記載の垂直磁気記録媒体であることを特徴とする磁気記録再生装置。
1 非磁性基板、
2 軟磁性裏打ち層、
3 配向性御層
4 磁性層
6 記録層
7 レジスト層
8 媒体
9 スタンパー
9a 凹部
10 凹凸部
11b 凹溝
12 非磁性層
14 分離領域部
15 記録部
16 保護膜
17 潤滑層
本発明の垂直磁気記録媒体は、非磁性基板上に、非磁性基板面に対して垂直方向に磁気異方性を有する記録層が形成され、記録層が、複数の記録部と、隣接する前記記録部を分離する分離領域部とを有する垂直磁気記録媒体であり、分離領域部がグラニュラー構造の材料、好ましくは非磁性材料、から構成される。このため、平滑で耐環境性に優れた表面を有する分離領域部が容易に得られる。より詳細には、グラニュラー構造の材料は、微細な結晶構造を有するので、グラニュラー構造の材料からなる分離領域部を得るために分離領域部となる膜をエッチングおよび/または研磨した場合、分離領域部となる膜のエッチングおよび/または研磨が均一に進行する。その結果、エッチングおよび/または研磨後に生じる分離領域部表面の荒れの問題が解消され、平滑で耐環境性に優れた表面を有する分離領域部が得られる。
また、本発明の磁気記録再生装置は、本発明の垂直磁気記録媒体を備えるので、分離領域部表面の平滑性に優れ、高記録密度を実現でき、磁気ヘッドによる書きにじみがなく、長期に渡って安定した電磁変換特性が得られ、磁気ヘッドなどの衝突に対する耐衝撃性に優れる。
「磁気記録媒体」
図1(A)~図1(I)は、本発明の垂直磁気記録媒体および本発明の垂直磁気記録媒体の製造方法の一例を説明する図である。図1(I)は本発明の垂直磁気記録媒体を示した拡大断面図である。なお、図1(I)においては、円盤状の垂直磁気記録媒体の一部のみを拡大して示している。
記録層6は、非磁性基板1面に対して垂直方向に磁気異方性を有し、図1(I)に示されるように、磁気記録される複数の記録部15と、隣接する記録部15を分離する、分離領域部14とを有している。記録部15は、同心円状の所定の幅で形成された記録トラック部またはビット部であり、図1(I)に示されるように、軟磁性裏打ち層2と配向制御層3と磁性層4とが順次積層されている。
図1(I)に示されるように、磁性層4と分離領域部14との境界部分には段差がなく、記録層6の表面は、磁性層4の表面部分と分離領域部14の表面部分とから構成される、連続した平滑面となっている。記録層6の表面粗さ(Ra)は小さい方が好ましく、具体的には、1nm以下が好ましく、0.5nm以下がより好ましく、0.3nm以下がさらに好ましい。記録層6の表面粗さが小さい程、記録層6上に形成される保護膜16および潤滑層17の表面粗さを小さくすることができ、表面の平坦性に優れた垂直磁気記録媒体Aとすることができる。表面の平坦性に優れた垂直磁気記録媒体Aは、磁気記録再生装置に備えられた際に、磁気ヘッドの浮上量を小さくすることが可能であるので、より一層の高密度磁気記録を実現できる。
非磁性基板1の平均表面粗さRaは小さい方が好ましい。具体的には、1nm以下、好ましくは0.5nm以下である事が、磁性層4の垂直配向性が良好なものとなる点や、後述するようにスタンパーを高圧でプレスする際における圧力分布を小さくすることができ、加工の均一性が向上する点などから好ましい。また、非磁性基板1の表面の微小うねりWaが0.3nm以下、より好ましくは0.2nm以下であると、スタンパーを高圧でプレスする際における圧力分布が小さくなり、加工の均一性が向上する点から好ましい。基板の厚さは必要に応じて選択できる。
また、磁性層4は、15~40体積%の範囲内で、より好ましくは15~25体積%の範囲内で、酸化物を含むものであることが好ましい。酸化物の体積が15体積%未満であると、SNR特性が不十分となる恐れがあるため好ましくない。また、酸化物の体積が40体積%を超えると、高記録密度に対応するだけの保磁力を得ることができない恐れがあるため好ましくない。
また、磁性層4の厚さは、6~18nmであることが好ましい。磁性層4の厚さを上記範囲とすることで、OW特性の悪化を生じさせることなく、十分な出力を確保することができ、好ましい。
また、本願発明におけるグラニュラー構造の非磁性材料は、非磁性材料粒子の周囲が完全に酸化物で覆われた構造の材料であってもよいが、一部のみが酸化物で覆われた構造の材料であってもよい。例えば、非磁性材料粒子の側面のみが酸化物に覆われた構造の材料であってもよい。
また、グラニュラー構造の非磁性材料に含まれる酸化物としては、SiO2、SiO、Cr2O3、CoO、Ta2O3、及びTiO2のいずれか一種以上などを挙げることができる。これらの酸化物を含むグラニュラー構造の非磁性材料とすることで、ドライエッチング等が容易なものとなるため好ましい。
また、分離領域部14は、15~40体積%の範囲内で、より好ましくは20~30体積%の範囲内で、酸化物を含むものであることが好ましい。分離領域部14に含まれる酸化物の体積率を上記範囲とすることにより、分離領域部14を形成する際のドライエッチングを容易とすることができ、ドライエッチング後に得られる分離領域部14の表面の粗さを均一にすることができる。
本実施形態においては、磁性層4を構成する材料と分離領域部14を構成する材料とを互いにさらに近似させるために、磁性層4および分離領域部14を構成する材料を、少なくとも以下の(1)~(5)に示すいずれかの構成とすることがより好ましい。
また、磁性層4および分離領域部14に、CoやPt等を添加する場合、分離領域部14における非磁性粒子は、第一主成分としてCoを含むCr合金であることが好ましい。
保護層16の膜厚は1~10nmであることが好ましく、1~5nmとすることがさらに好ましく、十分な耐久性を確保できる範囲でできるだけ薄く設定することが好ましい。
次に、本発明の垂直磁気記録媒体の製造方法の一例として、図1(I)に示す垂直磁気記録媒体Aの製造方法を、図1(A)~図1(H)を用いて説明する。
図1(A)は、非磁性基板上に記録層を形成した状態を示す拡大断面図である。図1(B)は、前記記録層上にレジスト層を形成した状態を示す拡大断面図である。図1(C)は、スタンパーを用いて、分離領域部となる領域に該当するレジスト層部分を除去した状態を示す拡大断面図である。図1(D)は、レジスト層全体が除去され、記録部(記録層)に、記録部を複数に分離する複数の凹溝が形成された状態を示す拡大断面図である。図1(F)は、凹溝が形成された記録部上に、グラニュラー構造の非磁性材料の層が堆積された状態を示す拡大断面図である。図1(G)は、非磁性材料の層の表面を除去し、記録層の表面が平滑化された状態を示す拡大断面図である。図1(H)は、平滑化された記録層の表面に、保護層が形成された状態を示す拡大断面図である。
その後、マスク層5の設けられた記録層6上にレジストを塗布し、図1(B)に示すように、レジスト層7の形成された媒体8を形成する。レジスト層7の形成に用いられるレジストは必要に応じて選択でき、工業的に使用されているフォトレジストなどを広く使用できる。レジスト層7は、通常、スピンコートなどを用いてレジストを薄く均一に塗布した後、必要に応じて、オーブンを用いて所定の温度および時間で焼成し、不要な有機溶剤などを除去する方法によって形成できる。なお、レジスト層7の形成方法は、使用するレジストの性質などに合わせて適宜調整してよい。
スタンパー9は必要に応じて選択できる。例えば、円盤状の非磁性基板1に合致する円盤状スタンパーであって、図1(I)に示す垂直磁気記録媒体Aの記録部15の表面形状に対応する凹部9aが表面に形成されたスタンパーなどを用いることができる。スタンパー9は、例えば、金属プレート上に電子線描画などの方法を用いて、微細な凹部9a形状を形成することによって得られる。スタンパー9の材料としては、十分な硬度および耐久性を有するものであればよく、特に限定されないが、例えばNiなどの金属が使用される。
その後、図1(E)に示すように、記録部15上に残っているマスク層5を、酸素プラズマエッチングやイオンミリング等により除去する。
なお、凹溝11b内にグラニュラー構造の非磁性材料が充填されていない部分があると、記録部15間の磁気的相互作用が十分に遮断されず、十分な記録再生特性が得られない場合がある。また、凹溝11b内のグラニュラー構造の非磁性材料が充填されていない部分が、大気中の酸素などのガスと接触することにより、垂直磁気記録媒体Aの耐食性に悪影響を及ぼす懸念がある。
非磁性層12が形成された後に表面上を平坦化する際に、非磁性層12と同時に除去される磁性層4の除去厚みは、特に限定されない。例えば、非磁性層12と磁性層4とを同時に除去する平坦化効果が十分に得られるように、1nm以上除去されることが好ましい。
その後、保護膜16上に潤滑層17をさらに形成することにより、図1(I)に示す垂直磁気記録媒体Aが得られる。
さらに、本実施形態の垂直磁気記録媒体Aでは、記録部15の最上層に磁性層4が配置され、記録部15と分離領域部14とを覆う保護膜16が設けられているが、保護膜16の下地層となって保護膜16を支える記録部15および分離領域部14は、その硬度や密度が互いに近似している。よって、保護膜16は、磁気ヘッドなどが偶発的に接触した場合に、表面全域において均一に衝撃を吸収できる、損傷を受けにくく非常に耐衝撃性に優れたものとなる。したがって、垂直磁気記録媒体Aは、非常に優れた耐衝撃性有するものとなる。
次に、本発明の磁気記録再生装置の一例として、図1(I)に示す垂直磁気記録媒体Aを備えた磁気記録再生装置を、図2を用いて説明する。
図2は、本発明の磁気記録再生装置の一例である、ハードディスク装置を示した斜視図である。図2に示す磁気記録再生装置Bは、上面側が開口した矩形箱状の筐体21と、筐体21の開口を塞ぐ図示略のトップカバーとを有する。筐体21内には、図1(I)に示す垂直磁気記録媒体Aと、スピンドルモータ23と、磁気ヘッド24(単磁極ヘッド)と、ヘッドアクチュエータ25と、ボイスコイルモータ27と、ヘッドアンプ回路28とが収納されている。
また、磁気ヘッド24は、記録部と再生部とを有し、垂直磁気記録媒体Aに対して磁気信号の記録および再生を行う。磁気ヘッド24は必要に応じて選択でき、例えばGMRヘッドあるいはTMRヘッドを用いることができる。磁気ヘッド24としてGMRヘッドあるいはTMRヘッドを用いた場合、高記録密度においても十分な信号強度を得ることができ、高記録密度を持った磁気記録再生装置Bを実現することができる。また、磁気ヘッド24の浮上量は必要に応じて選択でき、例えば0.005μm~0.020μmとすることで、出力を向上させることができ、また高い装置S/N比が得られ、その結果、大容量で高い信頼性を有する磁気記録再生装置Bとすることができる。
また、ボイスコイルモータ27は、回転軸26を介してヘッドアクチュエータ25を回転させるとともに位置決めする。
以下に示す製造方法により、図1(I)に示される垂直磁気記録媒体Aを作製した。
まず、非磁性基板1として、洗浄済み円盤状のHD用ガラス基板(オハラ(株)製、外径0.85インチ)を用意し、あらかじめ1.0×10-5Pa以下に真空排気した真空チャンバ内に設置した。そして、非磁性基板1上に、65Fe-25Co-10B(原子%)を加熱なしで50nm、Ruを0.8nm、65Fe-25Co-10B(原子%)を50nm順に成膜することにより、軟磁性裏打ち層2を形成した。続いて、軟磁性裏打ち層2上に、Ruからなる厚み20nmの配向制御層3を形成した。前記配向制御層3上に更に65Co-10Cr-15Pt-10SiO2(原子%)からなる厚み12nmの磁性層4を形成することにより、記録層6を形成した。この磁性層4は、Co、Cr及びPtからなる磁性材料粒子がSiO2中に分散した、グラニュラー構造を有する。
次に、トラックピッチ(Track pitch)150nmの同心円状の凹部が形成されているNi製のスタンパーを用いて、分離領域部14となる領域のレジスト層を除去し、基板1上に所望の凹凸部を形成した。その後、凹凸部を有するレジスト層が形成された非磁性基板1を高真空チャンバ内に設置し、イオンビームエッチング法を用いて、レジスト層の形成されていない領域(分離領域部14となる領域)の記録層6およびマスク層5を除去して、同心円状の凹溝11bを形成した。その後、記録部15上に残っているマスク層5およびレジスト層7を除去した。
続いて、イオンビームエッチングを用いて形成された非磁性層の表面上を平坦化するとともに、非磁性層と磁性層4の表面から1nm程度とを同時に除去して磁性層4を露出させた。
分離領域部14の材料として、表1に示すSiO2、Si、Cr、またはCr2O3を用いたこと以外は、上述の実施例と同様にして垂直磁気記録媒体を作製した。
なお比較例1~比較例4では、分離領域部に充填されたものはもちろんグラニュラー構造を有しない。
(電磁変換特性の経時変化評価)
実施例および比較例1~4の垂直磁気記録媒体を、温度80℃、湿度80%の環境下のオーブンに投入して、720時間保持した。オーブンに投入する前と後における、実施例および比較例1~4の垂直磁気記録媒体の信号対雑音比(SNR)および保磁力(Hc)を測定した。その結果を表1に示す。
なお、SNRの評価では、GUZIK社製リードライトアナライザRWA1632、およびスピンスタンドS1701MPを用い、書き込み部にシールディッドタイプヘッド、及び再生部にGMR素子を用いた磁気ヘッドを使用し、160kFCI、および、960kFCIの信号を書き込んだ際のrms値(rootmean square-inches)で評価を行った。
実施例および比較例1~4の垂直磁気記録媒体を5600rpmで回転させ、その表面の一定半径の箇所に、磁気ヘッドを0.5秒ずつ1000回接触させ、垂直磁気記録媒体の表面が受けるダメージを比較した。
ダメージの評価は、垂直磁気記録媒体の表面を300倍のノルマルスキー微分干渉光学顕微鏡で観察し、観察される傷の本数を計測することにより行った。その結果を表1に示す。
なお前述の耐衝撃性評価(スクラッチ評価)によって間接的に平滑性も評価される。本発明では平滑性に優れるため接触によるダメージがなく傷が発生せず、一方比較例では平滑性に劣るため接触によるダメージが大きく、発生した傷の本数が多い。
Claims (17)
- 非磁性基板上に、
前記非磁性基板面に対して垂直方向に磁気異方性を有する記録層が形成され、
前記記録層が、複数の記録部と、隣接する前記記録部を分離する複数の分離領域部とを有する垂直磁気記録媒体であって、
前記分離領域部が、グラニュラー構造の材料から形成されることを特徴とする垂直磁気記録媒体。 - 前記グラニュラー構造の材料が非磁性材料であることを特徴とする請求項1に記載の垂直磁気記録媒体。
- 前記記録部が積層体であり、グラニュラー構造の磁性材料から形成される磁性層を含むものであることを特徴とする請求項1に記載の垂直磁気記録媒体。
- 前記磁性層および前記分離領域部が、同一の酸化物を含むことを特徴とする請求項3に記載の垂直磁気記録媒体。
- 前記磁性層および前記分離領域部が、Crを含むことを特徴とする請求項3に記載の垂直磁気記録媒体。
- 前記磁性層および前記分離領域部が、5~40体積%の範囲内で酸化物を含むことを特徴とする請求項3に記載の垂直磁気記録媒体。
- 前記磁性層および前記分離領域部が、SiO2、SiO、Cr2O3、CoO、Ta2O3、及びTiO2のいずれか一種以上を含むことを特徴とする請求項3に記載の垂直磁気記録媒体。
- 前記記録部の最上層として前記磁性層が配置されており、
前記記録層上には、前記記録部と前記分離領域部とを覆う保護膜が形成されていることを特徴とする請求項3に記載の垂直磁気記録媒体。 - 非磁性基板上に、前記非磁性基板面に対して垂直方向に磁気異方性を有する記録層が形成され、前記記録層が、複数の記録部と、隣接する前記記録部を分離する複数の分離領域部とを有する垂直磁気記録媒体の製造方法であって、
非磁性基板上に、非磁性基板面に対して垂直方向に磁気異方性を有する記録層を形成する工程と、
前記記録層から、分離領域部となる領域を除去して凹溝を形成することによって、複数の記録部と、隣接する前記記録部を分離する複数の凹溝と、を形成する工程と、
前記凹溝にグラニュラー構造の材料を充填し分離領域部を形成する工程と、
を含む、垂直磁気記録媒体の製造方法。 - 前記凹溝に充填される前記グラニュラー構造の材料が非磁性材料であることを特徴とする請求項9に記載の垂直磁気記録媒体の製造方法。
- 前記記録部が、グラニュラー構造の磁性材料から形成される磁性層を含むことを特徴とする請求項9に記載の垂直磁気記録媒体の製造方法。
- 前記凹溝を充填する工程が、
前記凹溝の形成された前記記録層上に、前記グラニュラー構造の材料を堆積させて前記凹溝に前記材料が充填された非磁性層を形成する工程と、
前記磁性層の表面が露出しかつ前記磁性層の表面の一部が除去されるまで、前記非磁性層を除去して、前記非磁性層の形成された表面上を平坦化する、工程とを備えることを特徴とする請求項11に記載の垂直磁気記録媒体の製造方法。 - 前記記録層上に、前記記録部と前記分離領域部とを覆う保護膜を形成する工程を有することを特徴とする請求項12に記載の垂直磁気記録媒体の製造方法。
- 前記凹溝を形成する工程が、前記記録層上にレジストを塗布してレジスト層を形成し、スタンパーを用いて、前記分離領域部となる前記レジスト層の領域を除去し、前記レジスト層が除去された前記記録層の領域を除去する工程を備えることを特徴とする請求項11に記載の垂直磁気記録媒体の製造方法。
- 前記凹溝を充填する工程において、スパッタ法を用いて前記凹溝にグラニュラー構造の材料を充填することを特徴とする請求項11に記載の垂直磁気記録媒体の製造方法。
- 前記平坦化する工程において、イオンビームエッチング法を用いて前記非磁性層の形成された表面上を平坦化することを特徴とする請求項12に記載の垂直磁気記録媒体の製造方法。
- 磁気記録媒体と、該磁気記録媒体に情報を記録再生する磁気ヘッドとを備えた磁気記録再生装置であって、
前記磁気記録媒体が請求項1に記載の垂直磁気記録媒体であることを特徴とする磁気記録再生装置。
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US12/934,209 US20110019308A1 (en) | 2008-03-28 | 2009-03-27 | Perpendicular magnetic recording medium, method of manufacturing perpendicular magnetic recording medium, and magnetic recording/reproducing apparatus |
JP2010505860A JP4848469B2 (ja) | 2008-03-28 | 2009-03-27 | 垂直磁気記録媒体の製造方法 |
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JP2011129209A (ja) * | 2009-12-18 | 2011-06-30 | Showa Denko Kk | 磁気記録媒体の製造方法及び磁気記録再生装置 |
CN102737651A (zh) * | 2011-03-31 | 2012-10-17 | 西部数据传媒公司 | 具有多个交换耦合的磁层的记录介质 |
US9911448B2 (en) | 2012-01-16 | 2018-03-06 | Kabushiki Kaisha Toshiba | Perpendicular magnetic recording medium, method of manufacturing the same, and magnetic recording/reproduction apparatus |
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US6383645B1 (en) * | 1998-03-23 | 2002-05-07 | Kabushiki Kaisha Ohara | Glass-ceramic substrate for an information storage medium |
CN1125789C (zh) * | 2000-05-16 | 2003-10-29 | 湖北新华光信息材料股份有限公司 | 一种高强度磁盘基板用微晶玻璃及其制造方法 |
US6865044B1 (en) * | 2003-12-03 | 2005-03-08 | Hitachi Global Storage Technologies Netherlands B.V. | Method for magnetic recording on patterned multilevel perpendicular media using thermal assistance and fixed write current |
JP4214522B2 (ja) * | 2004-01-28 | 2009-01-28 | 富士電機デバイステクノロジー株式会社 | 垂直磁気記録媒体、および、その製造方法 |
JP4540557B2 (ja) * | 2004-07-05 | 2010-09-08 | 富士電機デバイステクノロジー株式会社 | 垂直磁気記録媒体 |
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JP2006286158A (ja) * | 2005-04-05 | 2006-10-19 | Canon Inc | 磁気記録媒体及びその製造方法 |
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JP2011129209A (ja) * | 2009-12-18 | 2011-06-30 | Showa Denko Kk | 磁気記録媒体の製造方法及び磁気記録再生装置 |
CN102737651A (zh) * | 2011-03-31 | 2012-10-17 | 西部数据传媒公司 | 具有多个交换耦合的磁层的记录介质 |
CN102737651B (zh) * | 2011-03-31 | 2017-05-24 | 西部数据传媒公司 | 具有多个交换耦合的磁层的记录介质 |
US9911448B2 (en) | 2012-01-16 | 2018-03-06 | Kabushiki Kaisha Toshiba | Perpendicular magnetic recording medium, method of manufacturing the same, and magnetic recording/reproduction apparatus |
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JP4848469B2 (ja) | 2011-12-28 |
CN102047330A (zh) | 2011-05-04 |
US20110019308A1 (en) | 2011-01-27 |
CN102047330B (zh) | 2014-08-27 |
JPWO2009119829A1 (ja) | 2011-07-28 |
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