JP2013125554A - Method for manufacturing magnetic recording medium, magnetic recording medium and magnetic recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium, capable of maintaining high perpendicular orientation of a perpendicular magnetic layer and achieving higher recording density.SOLUTION: A method for manufacturing a magnetic recording medium in which at least a soft magnetic backing layer 31, a seed layer 32, an intermediate layer 33 and a perpendicular magnetic layer 34 are sequentially laminated on a nonmagnetic substrate 30 comprises: forming, as the seed layer 32, an eutectic alloy film including two or more kinds of elements composing an eutectic structure and having columnar crystal nuclei 32a dispersed in dot shapes; and forming a microcrystal film having the crystal nucleus 32a projected from the surface of the eutectic alloy film by applying an etching process to the surface of the eutectic alloy film.

Description

  The present invention relates to a method for manufacturing a magnetic recording medium, a magnetic recording medium, and a magnetic recording / reproducing apparatus.

  A hard disk drive (HDD), which is a kind of magnetic recording / reproducing apparatus, has an increasing recording density of 50% or more per year and is said to continue to increase in the future. With the increase in the recording density of hard disk devices, development of magnetic heads and magnetic recording media suitable for increasing the recording density is in progress.

  Some commercially available magnetic recording / reproducing apparatuses are equipped with a so-called perpendicular magnetic recording medium in which an easy axis of magnetization in a magnetic film is vertically oriented. Even when the recording density of the perpendicular magnetic recording medium is increased, the influence of the demagnetizing field in the boundary region between the recording bits is small and a clear bit boundary is formed, so that an increase in noise can be suppressed. In addition, the perpendicular magnetic recording medium is excellent in thermal fluctuation characteristics because it requires only a small decrease in recording bit volume as the recording density increases.

  Further, in order to meet the demand for higher recording density of magnetic recording media, it has been studied to use a single magnetic pole head having excellent writing ability for the perpendicular magnetic layer as a magnetic head. Specifically, by providing a layer made of a soft magnetic material called a backing layer between a perpendicular magnetic layer that is a recording layer and a nonmagnetic substrate, a magnetic flux between a single-pole head and a magnetic recording medium is provided. There has been proposed a magnetic recording medium with improved efficiency of entering and exiting.

  In addition, in order to improve the recording / reproducing characteristics and thermal fluctuation characteristics of the perpendicular magnetic recording medium, an orientation control layer is used to form a multi-layered magnetic layer, and the crystal grains of each magnetic layer are formed into continuous columnar crystals. It has been proposed to improve the vertical orientation of the magnetic layer (see, for example, Patent Document 1).

  Also, Ru is used as the orientation control layer (underlayer) of the magnetic recording medium, the orientation control layer has a two-layer structure, the initial layer portion is formed at a low gas pressure, and the surface portion has a higher gas pressure than the initial layer portion. Has been proposed (see, for example, Patent Document 2).

  In addition, since Ru has a dome-shaped convex portion formed at the top of the columnar crystal, crystal grains such as a magnetic layer are grown on the convex portion, and the separation structure of the grown crystal particles is promoted. It is known to have the effect of isolating crystal grains and growing magnetic grains in a columnar shape (see, for example, Patent Document 3).

JP 2004-310910 A JP 2004-22138 A JP 2007-272990 A

  By the way, the demand for higher recording density for magnetic recording media is not limited, and magnetic recording media are required to have higher characteristics than ever before. Specifically, in order to increase the recording density of the magnetic recording medium, it is necessary to refine the crystal constituting the orientation control layer described above and to refine the magnetic particles having a columnar structure formed thereon.

  The present invention has been proposed in view of such a conventional situation, and a method for manufacturing a magnetic recording medium capable of further increasing the recording density while maintaining the high perpendicular orientation of the perpendicular magnetic layer, and its It is an object of the present invention to provide a magnetic recording medium manufactured by using such a manufacturing method, and a magnetic recording / reproducing apparatus including such a magnetic recording medium.

The present invention provides the following means.
(1) A method of manufacturing a magnetic recording medium in which a soft magnetic backing layer, a seed layer, an intermediate layer, and a perpendicular magnetic layer are sequentially laminated on at least a nonmagnetic substrate,
As the seed layer, after forming a eutectic alloy film containing two or more elements constituting a eutectic structure and in which columnar crystal nuclei are dispersed in a dot shape, the surface of the eutectic alloy film is formed. Etching is performed to form a microcrystalline film in which the crystal nuclei protrude from the surface.
(2) After the eutectic alloy film is formed by sputtering, an etching gas containing at least one element selected from fluorine, chlorine, hydrogen, and oxygen is used for the surface of the eutectic alloy film. The method for manufacturing a magnetic recording medium according to item (1), wherein a microcrystalline film in which the crystal nuclei protrude from the surface is formed by performing an etching process.
(3) As the seed layer, at least one element selected from Al, Si, Ge, and C constituting the eutectic structure, and Al, Pd, Ag, Au, which have a lower etching rate than this one element, After forming a eutectic alloy film containing other elements selected from Sb, Ru, Cu, Pt, and Co and having columnar crystal nuclei dispersed in a dot shape, the surface of the eutectic alloy film The magnetic recording medium according to (1) or (2), wherein a microcrystalline film in which crystal nuclei containing the other elements protrude from the surface is formed by performing an etching process on Method.
(4) After forming a eutectic alloy film containing either AlRu or AlCu as the seed layer and in which columnar crystal nuclei are dispersed in the form of dots, etching is performed on the surface of the eutectic alloy film. The method for producing a magnetic recording medium according to item (3), wherein the treatment forms a microcrystalline film in which crystal nuclei containing either Ru or Cu protrude from the surface.
(5) After forming a eutectic alloy film containing AlSi, PdSi, AgSi, or AuSi as the seed layer and having columnar crystal nuclei dispersed in the form of dots, the surface of the eutectic alloy film is formed. The magnetic recording medium according to (3) above, wherein a microcrystalline film in which crystal nuclei containing any of Al, Pd, Ag, and Au protrude from the surface is formed by performing an etching process on Manufacturing method.
(6) After forming a eutectic alloy film containing any of AlGe, PdGe, AgGe, AuGe, and SbGe as the seed layer and having columnar crystal nuclei dispersed in a dot shape, the eutectic alloy film (3), wherein the crystal nucleus containing any one of Al, Pd, Ag, Au, and Sb forms a microcrystalline film protruding from the surface by etching the surface of Manufacturing method of magnetic recording medium.
(7) After forming a eutectic alloy film containing any of RuC, PtC, and CoC and having columnar crystal nuclei dispersed in a dot shape as the seed layer, the surface of the eutectic alloy film is formed. The method for manufacturing a magnetic recording medium according to (3) above, wherein a microcrystalline film in which crystal nuclei containing any one of Ru, Pt, and Co protrude from the surface is formed by performing an etching process.
(8) The method for manufacturing a magnetic recording medium according to any one of (1) to (7), wherein a Co alloy film having an amorphous structure is formed as the soft magnetic backing layer.
(9) The method for manufacturing a magnetic recording medium according to any one of (1) to (8), wherein a Ru or Ru alloy film is formed as the intermediate layer.
(10) The layers are crystal-grown starting from the seed layer so that the crystal grains constituting the perpendicular magnetic layer constitute columnar crystals continuous in the thickness direction together with the crystal grains constituting the intermediate layer. The method for manufacturing a magnetic recording medium according to any one of (1) to (9) above.
(11) A magnetic recording medium in which a soft magnetic backing layer, a seed layer, an intermediate layer, and a perpendicular magnetic layer are laminated in this order on at least a nonmagnetic substrate,
The seed layer is composed of a microcrystalline film with crystal nuclei protruding from the surface,
The magnetic recording medium according to claim 1, wherein the intermediate layer and the perpendicular magnetic layer form columnar crystals in which the crystal grains are continuous in the thickness direction starting from the crystal nucleus.
(12) The seed layer is formed of a microcrystalline film in which a crystal nucleus containing an element selected from Al, Pd, Ag, Au, Sb, Ru, Pt, and Co protrudes from the surface. The magnetic recording medium according to 11).
(13) The magnetic recording medium according to (11) or (12), wherein the soft magnetic underlayer is made of a Co alloy film having an amorphous structure.
(14) The magnetic recording medium according to any one of (12) to (13), wherein the intermediate layer is made of Ru or a Ru alloy film.
(15) The magnetic recording medium manufactured by the manufacturing method according to any one of (1) to (10) or the magnetic recording medium according to any one of (11) to (14) When,
A magnetic recording / reproducing apparatus comprising: a magnetic head for recording / reproducing information with respect to the magnetic recording medium.

  As described above, in the present invention, the columnar crystals of each layer grown continuously in the thickness direction from the seed layer to the uppermost layer of the perpendicular magnetic layer starting from the seed layer have fine and uniform grain sizes. It can comprise by the crystal grain which has. As a result, it is possible to provide a magnetic recording medium capable of maintaining a high perpendicular orientation of the perpendicular magnetic layer and further increasing the recording density, and a magnetic recording / reproducing apparatus including such a magnetic recording medium. is there.

It is sectional drawing which shows the state which the columnar crystal of each layer grew perpendicularly | vertically with respect to the substrate surface. It is a phase diagram of an AlSi alloy. It is the figure which showed typically the crystal structure of 56Al-44Si alloy, (a) is the top view, (b) is the sectional view, (c) is the sectional view after the etching. It is the figure which showed typically the crystal structure of an 87.4Al-12.6Si alloy, (a) is the top view, (b) is the sectional view, (c) is the sectional view after the etching. It is the figure which showed typically the crystal structure of 92Al-8Si alloy, (a) is the top view, (b) is the sectional view, (c) is the sectional view after the etching. It is sectional drawing which shows typically the characteristic part of the magnetic recording medium to which this invention is applied. It is sectional drawing which shows an example of the magnetic recording medium to which this invention is applied. It is sectional drawing which expands and shows the laminated structure of a magnetic layer and a nonmagnetic layer. It is a perspective view which shows an example of a magnetic recording / reproducing apparatus.

  Hereinafter, a magnetic recording medium and a magnetic recording / reproducing apparatus to which the present invention is applied will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Make it not exist.

  As described above, in order to improve the vertical orientation of the multi-layered magnetic layer and to make the magnetic particles finer and to homogenize the crystal grain size (to reduce variation in the grain size distribution), soft magnetism The crystal grains constituting the orientation control layer (the layer including the seed layer and the intermediate layer of the present invention) disposed between the backing layer (SUL) and the perpendicular magnetic layer must be refined and the crystal grain size must be homogenized. There is.

  That is, as shown in FIG. 1, the orientation control layer 11 is provided with a concavo-convex surface 11a having the top of each columnar crystal S ′ constituting the orientation control layer 11 having a dome-like convexity. Crystal grains of the magnetic layer (or nonmagnetic layer) 12 grow as columnar crystals S1 ′ in the thickness direction. The crystal grains of the nonmagnetic layer (or magnetic layer) 13 and the uppermost magnetic layer 14 formed on the columnar crystal S1 ′ are also columnar crystals S2 ′ and S3 ′ continuous to the columnar crystal S1 ′. Grow epitaxially.

  Thus, when the magnetic layers 12 to 14 are multilayered, the crystal grains constituting each of the layers 12 to 14 are continuous columnar crystals S 1 ′ to S 3 ′ from the orientation control layer 11 to the uppermost magnetic layer 14. The epitaxial growth is repeated. Note that the layer 13 illustrated in FIG. 1 is a layer having a granular structure, and an oxide 15 is formed around the columnar crystal S <b> 2 forming the layer 13.

  Therefore, if the crystal grains of the orientation control layer 11 are refined and the crystal grain size is homogenized, the density of the columnar crystals S constituting the orientation control layer 11 is increased, and the top of each of the columnar crystals S ′ is further increased. The columnar crystals S1 ′ to S3 ′ of the layers 12 to 14 that grow in a columnar shape in the thickness direction can also be densified.

  Here, a soft magnetic backing layer made of CoFe alloy or the like, a seed layer made of NiW, an intermediate layer made of Ru, and a perpendicular magnetic layer made of CoCrPt alloy or the like are laminated in this order on a nonmagnetic substrate. A perpendicular magnetic recording medium having the above structure will be exemplified.

  In this perpendicular magnetic recording medium, the soft magnetic underlayer has an amorphous structure. The seed layer forms fine crystal nuclei on the surface of the soft magnetic underlayer having this amorphous structure. Then, Ru as an intermediate layer forms c-axis-oriented columnar crystals starting from the crystal nucleus of the seed layer (seed crystal). Further, the perpendicular magnetic layer formed on this intermediate layer also becomes columnar crystals with c-axis orientation.

  Therefore, since the intermediate layer and the perpendicular magnetic layer form a columnar crystal in which each crystal particle starts in the thickness direction with the crystal nucleus of the seed layer as a starting point (seed crystal), the crystal nucleus of the seed layer below the intermediate layer and the perpendicular magnetic layer If it can be refined and homogenized, the crystal grains of these intermediate layer and perpendicular magnetic layer can be refined and the crystal grain size can be homogenized.

However, as a result of verification by the present inventors, in the seed layer using NiW, in order to form a crystal film having a heterogeneous size on the surface of the soft magnetic underlayer, the intermediate layer formed thereon is formed. It was concluded that there is a limit to the homogenization of columnar crystals. That is, it was found that in the seed layer using NiW, large columnar crystals and small columnar crystals are generated in the intermediate layer, and the density distribution of the columnar crystals varies.

  Therefore, the present inventors conducted further studies based on such knowledge. For example, an AlSi eutectic alloy film is sputtered to a thickness of about 5 nm on the soft magnetic backing layer having the amorphous structure described above. In this case, a fine eutectic alloy film having a uniform crystal grain size can be formed.

  On the other hand, when a Ru film is formed as an intermediate layer on this fine eutectic alloy film, the Ru film does not nucleate from the crystal particles constituting the eutectic alloy film, and has a columnar shape having a fine and uniform grain size. It turns out that it doesn't become a crystal.

  Here, the phase diagram of the AlSi alloy is shown in FIG. 2, where the Al / Si composition ratio (%) is (1) Al: Si = 56: 44, and (2) Al: Si = 87. The crystal structure when cooled from the liquid phase (L) to the solid layer (α + β) in the case of 4: 12.6 and (3) Al: Si = 92: 8 is shown in FIGS. Shown in

  FIG. 3 is a view schematically showing the crystal structure of (1) 56Al-44Si alloy, (a) is a plan view thereof, (b) is a sectional view thereof, and (c) is a state after the etching. It is sectional drawing. FIG. 4 is a diagram schematically showing the crystal structure of (2) 87.4Al-12.6Si alloy, (a) is a plan view thereof, (b) is a sectional view thereof, and (c) is an etching thereof. FIG. FIG. 5 is a diagram schematically showing the crystal structure of (3) 92Al-8Si alloy, (a) is a plan view thereof, (b) is a sectional view thereof, and (c) is a sectional view after etching. It is.

  (1) In the case of 56Al-44Si alloy, solid phase Si (primary crystal β) precipitates during cooling from the liquid phase (L) to the eutectic temperature (577 ± 1 ° C.) as shown in FIG. Al is concentrated until Si in the liquid phase (L) reaches 12.6%. Then, by cooling to a temperature lower than the eutectic temperature, solid phase 87.4Al-12.6Si (eutectic α + β) precipitates. As a result, as shown in FIGS. 3A and 3B, a crystal structure (hypercoagulant) in which columnar crystal nuclei (eutectic AlSi) are dispersed in dots (islands) in Si crystal (primary crystal Si). Crystal structure) is formed.

Then, after sputter-depositing a 56Al-44Si alloy film having such a crystal structure, the surface was subjected to an etching process using CF ₄ gas, and the etching rate was relatively high in the alloy film. Crystal nuclei containing low Al remained, and Si crystals having an etching rate higher than that of the crystal nuclei were removed. As a result, a microcrystalline film having crystal nuclei protruding from the surface as shown in FIG. 3C was formed.

  (2) In the case of the 87.4Al-12.6Si alloy, as shown in FIG. 2, the solid phase 87.4Al-12.6Si is cooled by cooling from the liquid phase (L) to a temperature lower than the eutectic temperature. (Eutectic α + β) precipitates. As a result, as shown in FIGS. 4A and 4B, a crystal structure (eutectic structure) in which Al and Si microcrystals are mixed is formed.

Then, after the sputtering of 87.4Al-12.6Si alloy film having such a crystal structure, it was subjected to etching treatment using a CF ₄ gas to the surface. As a result, as shown in FIG. 4C, the 87.4Al-12.6Si alloy film was removed. It should be noted that the etching conditions at this time needed to be etched under conditions where the removal effect was higher than in the case shown in FIG.

  (3) In the case of 92Al-8Si alloy, solid phase Al (primary crystal α) precipitates during cooling from the liquid phase (L) to the eutectic temperature, as shown in FIG. The Si is concentrated until the Si content in 1) reaches 12.6%. Then, by cooling to a temperature lower than the eutectic temperature, solid phase 87.4Al-12.6Si (eutectic α + β) precipitates. As a result, as shown in FIGS. 5A and 5B, a crystal structure in which columnar crystal nuclei (eutectic AlSi) are dispersed in a dot shape (island shape) in an Al crystal (primary crystal Al) (sub-common). Crystal structure) is formed.

Then, after sputtering the 92Al-8Si alloy film having such a crystal structure, the surface was subjected to etching treatment using CF ₄ gas, and the etching rate was relatively high in the alloy film. Low Al crystals remained, and crystal nuclei containing Si having a higher etching rate than the Al crystals were removed. As a result, a microcrystalline film having a recess between Al crystals as shown in FIG. 5C was formed. It should be noted that the etching conditions at this time needed to be etched under conditions where the removal effect was higher than in the case shown in FIG.

  Based on the above findings, the present inventors formed a Ru film on the microcrystalline film in which the crystal nucleus of (1) protruded from the surface. As a result, it has been found that uniform columnar crystals of Ru are formed starting from the crystal nucleus, and the present invention has been completed.

  That is, the present invention has been made on the basis of the above-described knowledge. At least a soft magnetic backing layer, a seed layer, an intermediate layer, and a perpendicular magnetic layer are arranged in this order on a nonmagnetic substrate. When producing a magnetic recording medium laminated with the above, as a seed layer, an eutectic alloy film containing two or more elements constituting a eutectic structure and having columnar crystal nuclei dispersed in a dot shape was formed. Thereafter, the surface of the eutectic alloy film is etched to form a microcrystalline film having crystal nuclei protruding from the surface.

  As a result, the seed layer forms fine and homogeneous crystal nuclei. The convex crystal nuclei of the microcrystalline film forming the seed layer are used as starting points (seed crystals) from the intermediate layer to the perpendicular magnetic layer. The columnar crystals of each layer that are continuously grown in the thickness direction up to the uppermost layer can be constituted by crystal grains having a fine and uniform grain size.

  In addition, as the seed layer, at least one element selected from Al, Si, Ge, and C constituting the eutectic structure, and Al, Pd, Ag, Au, and Sb having a lower etching rate than the one element. , Ru, Pt, and other elements selected from Co, and after forming a eutectic alloy film in which columnar crystal nuclei are dispersed in a dot shape, the surface of the eutectic alloy film is formed. By performing an etching process, it is preferable to form a microcrystalline film in which crystal nuclei protrude from the surface.

  Among these, in the case of forming a eutectic alloy film containing Al as the one element, an eutectic alloy film containing either AlRu or AlCu and having columnar crystal nuclei dispersed in a dot shape was formed. Later, it is preferable to form a microcrystalline film in which crystal nuclei containing either Ru or Cu protrude from the surface by etching the surface of the eutectic alloy film.

  On the other hand, when forming a eutectic alloy film containing Si as the one element, the eutectic alloy film includes any one of AlSi, PdSi, AgSi, and AuSi, and columnar crystal nuclei are dispersed in dots. After forming the crystal structure, the surface of the eutectic alloy film is etched to form a microcrystalline film in which crystal nuclei containing any of Al, Pd, Ag, Au, and Sb protrude from the surface. Is preferred.

  On the other hand, in the case of forming a eutectic alloy film containing Ge as the one element, a eutectic containing AlGe, PdGe, AgGe, AuGe, or SbGe and having columnar crystal nuclei dispersed in dots. After forming the alloy film, the surface of the eutectic alloy film is etched to form a microcrystalline film in which crystal nuclei containing any of Al, Pd, Ag, Au, and Sb protrude from the surface. It is preferable to do.

  On the other hand, when forming a eutectic alloy film containing C as the one element, a eutectic alloy film containing any of RuC, PtC, and CoC and having columnar crystal nuclei dispersed in a dot shape is formed. Then, it is preferable to form a microcrystalline film in which crystal nuclei including any one of Ru, Pt, and Co protrude from the surface by performing an etching process on the surface of the eutectic alloy film.

  Although these eutectic alloy films depend on the alloy composition, the film thickness is preferably in the range of 4 to 10 nm, for example. When the film thickness of the eutectic alloy film is thinner than 4 nm, the eutectic alloy film may be partly island-shaped and not be a continuous film. In addition, the grain size of the crystal grains constituting the eutectic alloy film may not be uniform. On the other hand, when the film thickness of the eutectic alloy film is larger than 10 nm, the crystal grains constituting the eutectic alloy film are coarsened, and it becomes difficult to form the fine columnar crystals of Ru.

In the present invention, as a method for etching the surface of the eutectic alloy film, for example, at least an element selected from fluorine (F), chlorine (Cl), hydrogen (H), and oxygen (O) is used. It is preferable to perform dry etching using an etching gas containing one or more. In particular, in the case of an AlSi eutectic alloy film, CF ₄ gas or SF ₆ gas having a high etching selectivity between Al and Si can be suitably used. In this case, Si having an etching rate lower than that of Al can be selectively removed by dry etching.

In addition, for example, when etching is performed on the surface of a eutectic alloy film such as AlRu, AlSi, or AlCu, chlorine (Cl ₂ ) gas can be preferably used. In particular, in the case of an AlCu eutectic alloy film, a Cl ₂ gas having a high etching selectivity between Al and Cu can be suitably used. In this case, Al having an etching rate lower than that of Ru, Si, or Cu can be selectively removed by dry etching.

  Thus, the eutectic alloy film containing Al becomes one element that is selectively removed by the etching depending on the alloy composition and the etching gas, or forms a convex crystal nucleus after the etching. Or other elements.

  The crystal nucleus in the eutectic alloy film may be an alloy including a plurality of compositions. On the other hand, the phase (matrix) other than the crystal nuclei in the eutectic alloy film preferably has a single composition. Moreover, the element (primary crystal) which precipitates first tends to form a matrix.

  Further, a rare gas group can be used as the etching gas. In this case, it is possible to form the convex crystal nuclei using the difference in etching rate in the eutectic alloy film.

The features of the present invention will be described in more detail with reference to FIG.
In the present invention, as schematically shown in FIG. 2, for example, a Co alloy film having an amorphous structure is formed on the nonmagnetic substrate 30 as the soft magnetic backing layer 31.

  And in this invention, after sputter-depositing eutectic alloy films, such as AlSi and PdSi, for example as seed layer 32 on this soft magnetic backing layer 31, by carrying out dry etching of this eutectic alloy film, Si in the eutectic alloy film is selectively removed. As a result, a microcrystalline film is formed in which crystal nuclei 32a containing Al and Pd protrude from the surface.

  Thereafter, an intermediate layer 33 made of, for example, Ru or a Ru alloy is formed on the seed layer 32. Thereby, the crystal grains constituting the intermediate layer 33 are epitaxially grown as columnar crystals S1 continuous in the thickness direction while corresponding to the crystal nuclei 32a of the seed layer 32 in a 1: 1 ratio.

  In addition, a dome-shaped convex portion 33 a is formed at the top of each columnar crystal S <b> 1 constituting the intermediate layer 33. As a result, the crystal grains of the perpendicular magnetic layer 34 formed on the convex portion 33a can be epitaxially grown so as to form a columnar crystal S2 continuous in the thickness direction while corresponding 1: 1.

  As described above, in the present invention, the crystal nucleus is continuously grown in the thickness direction from the intermediate layer 33 to the uppermost layer of the perpendicular magnetic layer 34 using the crystal nucleus of the seed layer 32 as a starting point (seed crystal). The columnar crystals S1 and S2 of each layer can be composed of crystal particles having a fine and uniform particle size.

  Therefore, according to the present invention, a magnetic recording medium capable of maintaining a high perpendicular orientation of the perpendicular magnetic layer and further increasing the recording density, and a magnetic recording / reproducing apparatus equipped with such a magnetic recording medium are provided. Is possible.

FIG. 3 shows an example of a magnetic recording medium to which the present invention is applied.
As shown in FIG. 3, this magnetic recording medium has a soft magnetic backing layer 2, a seed layer 9, an intermediate layer 3, a perpendicular magnetic layer 4, a protective layer 5, and a lubricant on a nonmagnetic substrate 1. It has a structure in which the layers 6 are sequentially laminated.

  The perpendicular magnetic layer 4 includes, from the nonmagnetic substrate 1 side, three layers of a lower magnetic layer 4a, an intermediate magnetic layer 4b, and an upper magnetic layer 4c, and between the magnetic layer 4a and the magnetic layer 4b. By including the upper nonmagnetic layer 7b between the lower nonmagnetic layer 7a and the magnetic layer 4b and the magnetic layer 4c, the magnetic layers 4a to 4c and the nonmagnetic layers 7a and 7b are alternately stacked. It has a structure.

  As the nonmagnetic substrate 1, for example, a metal substrate made of a metal material such as aluminum or an aluminum alloy may be used. For example, a nonmetal substrate made of a nonmetal material such as glass, ceramic, silicon, silicon carbide, or carbon. May be used. In addition, it is also possible to use a substrate in which a NiP layer or a NiP alloy layer is formed on the surface of the metal substrate or nonmetal substrate by using, for example, a plating method or a sputtering method.

  As the glass substrate, for example, amorphous glass or crystallized glass can be used, and as the amorphous glass, for example, general-purpose soda lime glass or aluminosilicate glass can be used. In addition, as the crystallized glass, for example, lithium-based crystallized glass can be used. As the ceramic substrate, for example, general-purpose aluminum oxide, a sintered body mainly composed of aluminum nitride, silicon nitride, or the like, or a fiber reinforced material thereof can be used.

  The nonmagnetic substrate 1 preferably has an average surface roughness (Ra) of 2 nm (20 mm) or less, preferably 1 nm or less from the viewpoint of suitable for high recording density recording with a magnetic head flying low. Further, it is preferable that the surface fine waviness (Wa) is 0.3 nm or less (more preferably 0.25 nm or less) from the viewpoint of being suitable for high recording density recording with the magnetic head flying low. In addition, it is possible to use a magnetic head having a chamfered portion at the end face and a surface average roughness (Ra) of at least one of the side surface portion of 10 nm or less (more preferably 9.5 nm or less). Preferred for stability. In addition, microwaviness (Wa) can be measured as surface average roughness in a measuring range of 80 μm, for example, using a surface roughness measuring device P-12 (manufactured by KLM-Tencor).

  Further, when the nonmagnetic substrate 1 is in contact with the soft magnetic backing layer 2 containing Co or Fe as a main component, there is a possibility that corrosion proceeds due to the influence of surface adsorption gas, moisture, diffusion of substrate components, and the like. is there. In this case, it is preferable to provide an adhesion layer between the nonmagnetic substrate 1 and the soft magnetic backing layer 2, thereby suppressing these. In addition, as a material of the adhesion layer, for example, Cr, Cr alloy, Ti, Ti alloy, or the like can be selected as appropriate. The thickness of the adhesion layer is preferably 2 nm (30 mm) or more.

  The soft magnetic underlayer 2 increases the component of the magnetic flux generated from the magnetic head in the direction perpendicular to the substrate surface, and further strengthens the direction of magnetization of the perpendicular magnetic layer 4 on which information is recorded to be perpendicular to the nonmagnetic substrate 1. It is provided to fix in any direction. This effect becomes more conspicuous particularly when a single pole head for perpendicular recording is used as a magnetic head for recording and reproduction.

  As the soft magnetic backing layer 2, for example, an amorphous or microcrystalline soft magnetic material containing Fe, Ni, Co, or the like can be used. Specific examples of soft magnetic materials include CoFe alloys (CoFeTaZr, CoFeZrNb, etc.), FeCo alloys (FeCo, FeCoV, etc.), FeNi alloys (FeNi, FeNiMo, FeNiCr, FeNiSi, etc.), and FeAl. Alloys (FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, FeAlO, etc.), FeCr alloys (FeCr, FeCrTi, FeCrCu, etc.), FeTa alloys (FeTa, FeTaC, FeTaN, etc.), FeMg alloys (FeMgO, etc.), Examples thereof include FeZr alloys (FeZrN, etc.), FeC alloys, FeN alloys, FeSi alloys, FeP alloys, FeNb alloys, FeHf alloys, FeB alloys, and the like.

  In addition, the soft magnetic underlayer 2 is made of a Co alloy containing 80 atomic% or more of Co, at least one of Zr, Nb, Ta, Cr, Mo, etc., and having an amorphous or microcrystalline structure. Can be used. Specific examples of the specific material include CoZr, CoZrNb, CoZrTa, CoZrCr, and CoZrMo-based alloys.

  The soft magnetic backing layer 2 is composed of two soft magnetic films, and a Ru film is preferably provided between the two soft magnetic films. By adjusting the film thickness of the Ru film in the range of 0.4 to 1.0 nm or 1.6 to 2.6 nm, the two-layer soft magnetic film has an AFC structure, and such an AFC structure is adopted. Thus, so-called spike noise can be suppressed.

  The seed layer 9 and the intermediate layer 3 are for functioning as an orientation control layer for controlling the orientation and crystal size of the layer immediately above. Since the seed layer 9 and the intermediate layer 3 can be formed by sequentially stacking the seed layer 32 and the intermediate layer 33 shown in FIG. 2, the description thereof will be omitted.

  Further, it is preferable to provide a nonmagnetic underlayer 8 between the intermediate layer 3 and the perpendicular magnetic layer 4. In the initial portion of the perpendicular magnetic layer 4 directly above the intermediate layer 3, disorder of crystal growth is likely to occur, which causes noise. The occurrence of noise can be suppressed by replacing the disturbed portion of the initial portion with the nonmagnetic underlayer 8.

The nonmagnetic underlayer 8 is preferably made of a material mainly containing Co and further containing an oxide. The Cr content is preferably 25 atomic% or more and 50 atomic% or less. As the oxide, for example, oxides such as Cr, Si, Ta, Al, Ti, Mg, and Co are preferably used, and among them, TiO ₂ , Cr ₂ O ₃ , SiO _{2, and the} like are preferably used. it can. The content of the oxide is preferably 3 mol% or more and 18 mol% or less with respect to the total amount of mol calculated as one compound, for example, an alloy such as Co, Cr, and Pt constituting the magnetic particles.

The nonmagnetic underlayer 8 is preferably made of a complex oxide to which two or more kinds of oxides are added. Among these, Cr ₂ O ₃ —SiO ₂ , Cr ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ —SiO ₂ —TiO _{2 and the} like can be preferably used. Furthermore, CoCr—SiO ₂ , CoCr—TiO ₂ , CoCr—Cr ₂ O ₃ —SiO ₂ , CoCr—TiO ₂ —Cr ₂ O ₃ , CoCr—Cr ₂ O ₃ —TiO ₂ —SiO ₂ or the like is preferably used. Can do. Further, Pt may be added from the viewpoint of crystal growth.

  The thickness of the nonmagnetic underlayer 8 is preferably 0.2 nm or more and 3 nm or less. If the thickness exceeds 3 nm, Hc and Hn decrease, which is not preferable.

The magnetic layer 4a is made of a material mainly containing Co and further containing an oxide. As this oxide, for example, an oxide such as Cr, Si, Ta, Al, Ti, Mg, Co is preferably used. . Among _{them, TiO 2, Cr 2 O 3} , SiO ₂ or the like can be suitably used. The magnetic layer 4a is preferably made of a complex oxide to which two or more kinds of oxides are added. Among these, Cr ₂ O ₃ —SiO ₂ , Cr ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ —SiO ₂ —TiO _{2 and the} like can be preferably used.

  As shown in FIG. 4, in the magnetic layer 4 a, it is preferable that magnetic particles (magnetized crystal particles) 42 are dispersed in a layer including the oxide 41. The magnetic particles 42 preferably have a columnar structure that vertically penetrates the magnetic layers 4a and 4b and further the magnetic layer 4c. By having such a structure, the orientation and crystallinity of the magnetic particles 42 of the magnetic layer 4a are improved, and as a result, a signal / noise ratio (S / N ratio) suitable for high-density recording can be obtained. .

  In order to obtain such a structure, the amount of the oxide 41 to be contained and the film formation conditions of the magnetic layer 4a are important. That is, the content of the oxide 41 is 3 mol% or more and 18 mol% or less with respect to the total mol amount of the magnetic particles 42, for example, an alloy such as Co, Cr, and Pt calculated as one compound. preferable. More preferably, it is 6 mol% or more and 13 mol% or less.

  The above range is preferable as the content of the oxide 41 in the magnetic layer 4a. When the magnetic layer 4a is formed, the oxide 41 is precipitated around the magnetic particles 42, and the magnetic particles 42 are isolated and refined. This is because it becomes possible. On the other hand, when the content of the oxide 41 exceeds the above range, the oxide 41 remains in the magnetic particle 42, impairs the orientation and crystallinity of the magnetic particle 42, and further above and below the magnetic particle 42. The oxide 41 is deposited, and as a result, a columnar structure in which the magnetic particles 42 penetrate through the magnetic layers 4a to 4c is not formed. In addition, when the content of the oxide 41 is less than the above range, separation and refinement of the magnetic particles 42 are insufficient, resulting in an increase in noise during recording and reproduction, and a signal / This is not preferable because the noise ratio (S / N ratio) cannot be obtained.

  The content of Cr in the magnetic layer 4a is preferably 20 atomic% or less (more preferably 6 atomic% or more and 16 atomic% or less). The reason why the Cr content is in the above range is that the magnetic anisotropy constant Ku of the magnetic particles 42 is not lowered too much, and high magnetization is maintained. As a result, recording / reproduction characteristics suitable for high-density recording and sufficient heat This is because fluctuation characteristics can be obtained.

  On the other hand, when the Cr content exceeds the above range, the magnetic anisotropy constant Ku of the magnetic particles 42 becomes small, so that the thermal fluctuation characteristics deteriorate, and the crystallinity and orientation of the magnetic particles 42 deteriorate. As a result, the recording / reproduction characteristics deteriorate, which is not preferable. Further, when the Cr content is less than the above range, the magnetic anisotropy constant Ku of the magnetic particles 42 is high, so that the perpendicular coercive force becomes too high and data is sufficiently written by a magnetic head when data is recorded. This is not preferable because the recording characteristics (OW) are unsuitable for high density recording.

  The content of Pt in the magnetic layer 4a is preferably 8 atom% or more and 25 atom% or less. The reason why the Pt content is within the above range is that the magnetic anisotropy constant Ku required for the perpendicular magnetic layer 4 is low when it is less than 8 atomic%. On the other hand, when it exceeds 25 atomic%, a stacking fault occurs inside the magnetic particle 42, and as a result, the magnetic anisotropy constant Ku decreases. Therefore, in order to obtain thermal fluctuation characteristics and recording / reproduction characteristics suitable for high-density recording, the Pt content is preferably set in the above range.

  In addition, when the Pt content exceeds the above range, an fcc structure layer is formed in the magnetic particles 42, and the crystallinity and orientation may be impaired. On the other hand, if the Pt content is less than the above range, the magnetic anisotropy constant Ku for obtaining thermal fluctuation characteristics suitable for high-density recording cannot be obtained.

  In addition to Co, Cr, Pt and oxide 41, the magnetic layer 4a contains one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re. Can be included. By including the above elements, the miniaturization of the magnetic particles 42 can be promoted or the crystallinity and orientation can be improved, and recording / reproduction characteristics and thermal fluctuation characteristics suitable for higher density recording can be obtained.

  Further, the total content of the above elements is preferably 8 atomic% or less. If it exceeds 8 atomic%, a phase other than the hcp phase is formed in the magnetic particles 42, so that the crystallinity and orientation of the magnetic particles 42 are disturbed. As a result, recording / reproduction characteristics and thermal fluctuation suitable for high density recording are obtained. Since characteristics cannot be obtained, it is not preferable.

As a material suitable for the magnetic layer 4a, for example, 90 (Co14Cr18Pt) -10 (SiO ₂ ) {Cr content of 14 atomic%, Pt content of 18 atomic%, and the balance Co were calculated as one compound. Molar concentration is 90 mol%, oxide composition composed of SiO ₂ is 10 mol%}, 92 (Co10Cr16Pt) -8 (SiO ₂ ), 94 (Co8Cr14Pt4Nb) -6 (Cr ₂ O ₃ ), and (CoCrPt)-(Ta _{2 O 5), (CoCrPt)} - (Cr 2 O 3) - (TiO 2), (CoCrPt) - (Cr 2 O 3) - (SiO 2), (CoCrPt) - (Cr 2 O 3) - (SiO _{2) - (TiO 2),} (CoCrPtMo) - (TiO), (CoCrPtW) - (TiO 2), (CoCrPtB) - (Al 2 Examples thereof include compositions such as (O ₃ ), (CoCrPtTaNd)-(MgO), (CoCrPtBCu)-(Y ₂ O ₃ ), (CoCrPtRu)-(SiO ₂ ).

  Since the magnetic layer 4b can be made of the same material as the magnetic layer 4a, the description thereof will be omitted. In the magnetic layer 4b, it is preferable that magnetic particles (crystal grains having magnetism) 42 are dispersed in the layer. As shown in FIG. 4, the magnetic particles 42 preferably have a columnar structure that vertically penetrates the magnetic layers 4a and 4b and further the magnetic layer 4c. By forming such a structure, the orientation and crystallinity of the magnetic particles 42 of the magnetic layer 4b are improved, and as a result, a signal / noise ratio (S / N ratio) suitable for high-density recording can be obtained. it can.

  The magnetic layer 4c is preferably made of a material that contains Co as a main component and does not contain an oxide. As shown in FIG. 4, the magnetic particles 42 in the layer form columnar shapes from the magnetic particles 42 in the magnetic layer 4a. The structure is preferably epitaxially grown. In this case, the magnetic particles 42 of the magnetic layers 4a to 4c are preferably epitaxially grown in a columnar shape in a one-to-one correspondence in each layer. Further, the magnetic particles 42 of the magnetic layer 4b are epitaxially grown from the magnetic particles 42 in the magnetic layer 4a, so that the magnetic particles 42 of the magnetic layer 4b are miniaturized and the crystallinity and orientation are further improved. Become.

  The content of Cr in the magnetic layer 4c is preferably 10 atomic percent or more and 24 atomic percent or less. By setting the Cr content in the above range, a sufficient output during data reproduction can be ensured, and even better thermal fluctuation characteristics can be obtained. On the other hand, when the content of Cr exceeds the above range, the magnetization of the magnetic layer 4c becomes too small, which is not preferable. When the Cr content is less than the above range, the magnetic particles 42 are not sufficiently separated and refined, noise during recording / reproduction increases, and a signal / noise ratio (S) suitable for high-density recording (S / N ratio) is not obtained.

  The magnetic layer 4c may be made of a material containing Pt in addition to Co and Cr. The content of Pt in the magnetic layer 4c is preferably 6 atom% or more and 20 atom% or less. When the Pt content is in the above range, a sufficient coercive force suitable for high recording density can be obtained, and a high reproduction output during recording and reproduction can be maintained, resulting in recording suitable for high density recording. Reproduction characteristics and thermal fluctuation characteristics can be obtained.

  On the other hand, when the content of Pt exceeds the above range, an fcc-structured phase is formed in the magnetic layer 4c, which is not preferable because the crystallinity and orientation may be impaired. On the other hand, if the Pt content is less than the above range, the magnetic anisotropy constant Ku for obtaining thermal fluctuation characteristics suitable for high-density recording cannot be obtained.

  The magnetic layer 4c contains one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn in addition to Co, Cr, and Pt. Can do. By including the above elements, the miniaturization of the magnetic particles 42 can be promoted or crystallinity and orientation can be improved, and recording / reproduction characteristics and thermal fluctuation characteristics suitable for higher density recording can be obtained.

  The total content of the above elements is preferably 16 atomic% or less. On the other hand, when the content exceeds 16 atomic%, a phase other than the hcp phase is formed in the magnetic particles 42, so that the crystallinity and orientation of the magnetic particles 42 are disturbed. As a result, recording / reproduction suitable for high-density recording It is not preferable because characteristics and thermal fluctuation characteristics cannot be obtained.

  Examples of suitable materials for the magnetic layer 4c include CoCrPt and CoCrPtB. In the case of the CoCrPtB system, the total content of Cr and B is preferably 18 atom% or more and 28 atom% or less.

  Suitable materials for the magnetic layer 4c include, for example, Co14-24Cr8-22Pt {Cr content 14-24 atomic%, Pt content 8-22 atomic%, balance Co} in CoCrPt series, Co10 in CoCrPtB series. 24Cr8-22Pt0-16B {Cr content 10-24 atom%, Pt content 8-22 atom%, B content 0-16 atom%, balance Co} is preferred. In other systems, in CoCrPtTa system, Co10-24Cr8-22Pt1-5Ta {Cr content 10-24 atom%, Pt content 8-22 atom%, Ta content 1-5 atom%, balance Co}, CoCrPtTaB system Then, Co10-24Cr8-22Pt1-5Ta1-10B {Cr content 10-24 atomic%, Pt content 8-22 atomic%, Ta content 1-5 atomic%, B content 1-10 atomic%, balance Co }, Other materials such as CoCrPtBNd, CoCrPtTaNd, CoCrPtNb, CoCrPtBW, CoCrPtMo, CoCrPtCuRu, and CoCrPtRe may be used.

  The perpendicular coercive force (Hc) of the perpendicular magnetic layer 4 is preferably 3000 [Oe] or more. When the coercive force is less than 3000 [Oe], the recording / reproducing characteristics, particularly the frequency characteristics, are deteriorated, and the thermal fluctuation characteristics are also deteriorated, which is not preferable as a high-density recording medium.

  The reverse magnetic domain nucleation magnetic field (-Hn) of the perpendicular magnetic layer 4 is preferably 1500 [Oe] or more. When the reverse domain nucleation magnetic field (-Hn) is less than 1500 [Oe], the thermal fluctuation resistance is poor, which is not preferable.

  The perpendicular magnetic layer 4 preferably has an average particle diameter of magnetic particles of 3 to 12 nm. This average particle diameter can be obtained, for example, by observing the perpendicular magnetic layer 4 with a TEM (transmission electron microscope) and image-processing the observed image.

  The thickness of the perpendicular magnetic layer 4 is preferably 5 to 20 nm. If the thickness of the perpendicular magnetic layer 4 is less than the above, sufficient reproduction output cannot be obtained, and the thermal fluctuation characteristics also deteriorate. When the thickness of the perpendicular magnetic layer 4 exceeds the above range, the magnetic particles in the perpendicular magnetic layer 4 are enlarged, increasing noise during recording and reproduction, and a signal / noise ratio (S / N). Ratio) and recording / reproducing characteristics represented by recording characteristics (OW) are not preferable.

The protective layer 5 is for preventing corrosion of the perpendicular magnetic layer 4 and preventing damage to the surface of the medium when the magnetic head comes into contact with the medium, and a conventionally known material can be used, for example, C, SiO ₂ and those containing ZrO ₂ can be used. The thickness of the protective layer 5 is preferably 1 to 10 nm from the viewpoint of high recording density because the distance between the head and the medium can be reduced.

  For the lubricating layer 6, it is preferable to use a lubricant such as perfluoropolyether, fluorinated alcohol, fluorinated carboxylic acid, or the like.

  In the present invention, the magnetic layer on the nonmagnetic substrate 1 side is preferably a granular magnetic layer, and the magnetic layer on the protective layer 5 side is preferably a non-granular magnetic layer containing no oxide. With this configuration, it is possible to more easily control and adjust each characteristic such as the thermal fluctuation characteristic, recording characteristic (OW), and S / N ratio of the magnetic recording medium.

  In the present invention, the perpendicular magnetic layer 4 can be composed of four or more magnetic layers. For example, in addition to the magnetic layers 4a and 4b, a magnetic layer having a granular structure is composed of three layers, and a magnetic layer 4c not containing an oxide is provided thereon, and a magnetic layer not containing an oxide is also provided. The layer 4c may have a two-layer structure and be provided on the magnetic layers 4a and 4b.

  In the present invention, it is preferable to provide a nonmagnetic layer 7 (indicated by reference numerals 7a and 7b in FIG. 5) between three or more magnetic layers constituting the perpendicular magnetic layer 4. By providing the nonmagnetic layer 7 with an appropriate thickness, magnetization reversal of individual films can be facilitated, and dispersion of magnetization reversal of the entire magnetic particles can be reduced. As a result, the S / N ratio can be further improved.

  As the nonmagnetic layer 7 provided between the magnetic layers constituting the perpendicular magnetic layer 4, it is preferable to use a material having an hcp structure. Specifically, for example, Ru, Ru alloy, CoCr alloy, CoCrX1 alloy (X1 is Pt, Ta, Zr, Re, Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W, Mo, Mo. , Ti, V, Zr, or B represents at least one element or two or more elements).

  When a CoCr-based alloy is used as the nonmagnetic layer 7 provided between the magnetic layers constituting the perpendicular magnetic layer 4, the Co content is preferably in the range of 30 to 80 atomic%. This is because within this range, the coupling between the magnetic layers can be adjusted to be small.

  Further, as the nonmagnetic layer 7 provided between the magnetic layers constituting the perpendicular magnetic layer 4, as an alloy having an hcp structure, an alloy such as Ru, Re, Ti, Y, Hf, Zn, or the like can be used other than Ru. .

  Further, as the nonmagnetic layer 7 provided between the magnetic layers constituting the perpendicular magnetic layer 4, metals or alloys having other structures may be used as long as the crystallinity and orientation of the upper and lower magnetic layers are not impaired. it can. Specifically, for example, Pd, Pt, Cu, Ag, Au, Ir, Mo, W, Ta, Nb, V, Bi, Sn, Si, Al, C, B, Cr, or an alloy thereof is used. it can. In particular, as a Cr alloy, CrX2 (X2 represents at least one element selected from Ti, W, Mo, Nb, Ta, Si, Al, B, C, and Zr) or the like. Can be suitably used. In this case, the Cr content is preferably 60 atomic% or more.

As the nonmagnetic layer 7 provided between the magnetic layers constituting the perpendicular magnetic layer 4, it is preferable to use a layer having a structure in which metal particles of the above alloy are dispersed in an oxide, a metal nitride, or a metal carbide. Further, it is more preferable that the metal particles have a columnar structure penetrating the nonmagnetic layer 7 vertically. In order to obtain such a structure, it is preferable to use an alloy material containing an oxide, a metal nitride, or a metal carbide. Specifically, as the oxide, for example, SiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , Cr ₂ O ₃ , MgO, Y ₂ O ₃ , TiO _2, etc. As the metal nitride, for example, AlN, Si For example, TaC, BC, SiC, or the like can be used as the metal carbide such as ₃ N ₄ , TaN, or CrN. Further, for example, CoCr—SiO ₂ , CoCr—TiO ₂ , CoCr—Cr ₂ O ₃ , CoCrPt—Ta ₂ O ₅ , Ru—SiO ₂ , Ru—Si ₃ N ₄ , Pd—TaC, and the like can be used.

  The content of the oxide, metal nitride, or metal carbide in the nonmagnetic layer 7 provided between the magnetic layers constituting the perpendicular magnetic layer 4 is a content that does not impair the crystal growth and crystal orientation of the perpendicular magnetic film. Is preferred. In addition, the content of oxide, metal nitride, or metal carbide is preferably 4 mol% or more and 30 mol% or less with respect to the alloy.

  When the content of the oxide, metal nitride, or metal carbide in the nonmagnetic layer 7 exceeds the above range, the oxide, metal nitride, or metal carbide remains in the metal particle, and the metal particle In addition to impairing crystallinity and orientation, oxides, metal nitrides, or metal carbides are also deposited on the top and bottom of the metal particles, making it difficult for the metal particles to have a columnar structure that vertically penetrates the nonmagnetic layer 7. This is not preferable because the crystallinity and orientation of the magnetic layer formed on the magnetic layer 7 may be impaired. On the other hand, when the content of the oxide, metal nitride, or metal carbide in the nonmagnetic layer 7 is less than the above range, the effect of adding the oxide, metal nitride, or metal carbide cannot be obtained. Therefore, it is not preferable.

(Magnetic recording / reproducing device)
FIG. 5 shows an example of a magnetic recording / reproducing apparatus to which the present invention is applied.
This magnetic recording / reproducing apparatus includes a perpendicular magnetic recording medium 50 having the configuration shown in FIG. 3, a medium driving unit 51 that rotationally drives the perpendicular magnetic recording medium 50, and a magnetic head that records and reproduces information on the perpendicular magnetic recording medium 50. 52, a head drive unit 53 that moves the magnetic head 52 relative to the perpendicular magnetic recording medium 50, and a recording / reproducing signal processing system 54. Further, the recording / reproducing signal processing system 54 can process data input from the outside and send a recording signal to the magnetic head 52, process a reproducing signal from the magnetic head 52, and send the data to the outside. ing.

  In the magnetic recording / reproducing apparatus to which the present invention is applied, in order to meet the demand for further increasing the recording density of the perpendicular magnetic recording medium, a single pole head having excellent writing ability for the perpendicular magnetic layer 5 is used as the magnetic head 52. preferable. In the perpendicular magnetic recording medium 50, the soft magnetic backing layer 2 is provided between the nonmagnetic substrate 1 and the perpendicular magnetic layer 4 so as to correspond to such a single magnetic pole head, and the perpendicular magnetic recording medium 50 is perpendicular to the single magnetic pole head. The efficiency of entering and exiting the magnetic flux with the layer 4 can be improved.

  In the magnetic recording / reproducing apparatus, a magnetic head 52 having a GMR element using a giant magnetoresistive effect (GMR) as a reproducing element and suitable for higher recording density can be used.

  According to the magnetic recording / reproducing apparatus, by adopting the magnetic recording medium to which the present invention is applied as the magnetic recording medium 50, miniaturization of magnetic particles and magnetic isolation are promoted, and the S / N during reproduction is increased. Ratio can be greatly improved, thermal fluctuation characteristics can be improved, and a medium having excellent recording characteristics (OW) can be obtained. A recording / reproducing apparatus can be obtained.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

Example 1
In Example 1, first, a cleaned glass substrate (manufactured by Konica Minolta Co., Ltd., 2.5 inch outer diameter) is accommodated in a film forming chamber of a DC magnetron sputtering apparatus (C-3040 made by Anelva Co., Ltd.), and an ultimate vacuum After the inside of the film formation chamber was evacuated to a pressure of 1 × 10 ⁻⁵ Pa, an adhesion layer having a thickness of 10 nm was formed on the glass substrate using a Cr target. Further, on this adhesion layer, the substrate temperature is set to 100 ° C. or less, and Co-20Fe-5Zr-5Ta {Fe content 20 atomic%, Zr content 5 atomic%, Ta content 5 atomic%, and the balance Co}. A soft magnetic layer having a layer thickness of 25 nm was formed using a target, a Ru layer having a layer thickness of 0.7 nm was formed thereon, and then a Co-20Fe-5Zr-5Ta target was used again to form a layer thickness. A 25 nm soft magnetic layer was formed and used as a soft magnetic backing layer.

Next, a seed layer having a layer thickness of 5 nm was formed on the soft magnetic underlayer using a 56Al-44Si eutectic target at a sputtering pressure of 0.5 Pa. Next, dry etching was performed on the surface of the AlSi thin film with CF ₄ gas at 40 sccm, the pressure in the reaction vessel at 0.5 Pa, the RF power at 200 W, and the substrate bias at 15 W for 10 seconds.

  Next, an alignment control layer having a layer thickness of 20 nm was formed using a Ru target. When forming the orientation control layer, Ru having a layer thickness of 10 nm was formed with a sputtering pressure of 0.8 Pa, and then Ru having a layer thickness of 10 nm was formed with a sputtering pressure of 1.5 Pa.

Next, on the orientation control layer, 91 (Co15Cr16Pt) -6 (SiO ₂ ) -3 (TiO ₂ ) {Cr content of 15 atomic%, Pt content of 18 atomic%, and the remaining Co alloy of 91 mol%, SiO the oxide of ₂ 6 mol%, the oxide of TiO ₂ by using a target of 3 mol%}, was formed a magnetic layer having a thickness of 9 nm. The sputtering pressure at this time was 2 Pa.

Next, on the magnetic layer, 92 (Co11Cr18Pt) -5 (SiO ₂ ) -3 (TiO ₂ ) {Cr content of 11 atomic%, Pt content of 18 atomic%, and the balance Co of 92 mol%, SiO ₂ A magnetic layer having a thickness of 6 nm was formed using a target of 5 mol% of an oxide composed of 3 mol% and 3 mol% of an oxide composed of TiO ₂ . The sputtering pressure at this time was 2 Pa.

  At this stage, planar TEM observation of the magnetic layer having a granular structure is performed, and the average particle size <D> [nm] of the magnetic particles and the particle size dispersion σ / <D> [ %] Was measured. The measurement is performed before the Co20Cr14Pt3B magnetic layer is formed in order to facilitate evaluation of the average particle diameter of the magnetic particles.

  As a result, in Example 1, as shown in Table 1, <D> was 5.5 nm and σ / <D> was 7.2%.

  Next, a magnetic layer having a thickness of 7 nm is formed on the magnetic layer using a target of Co20Cr14Pt3B {Cr content 20 atomic%, Pt content 14 atomic%, B content 3 atomic%, balance Co}. did. The sputtering pressure at this time was 0.6 Pa.

  Next, a protective layer having a thickness of 3.0 nm is formed on the magnetic layer by a CVD method, and then a 1 nm thick lubricating film made of perfluoropolyether is formed by a dipping method. A recording medium was obtained.

  For the magnetic recording medium of Example 1, the coercive force dispersion “ΔHc / Hc”, “SNR [dB]”, the overwrite characteristic “OW [dB]”, and the bit error rate “BER” were measured, and the recording / reproduction characteristics were measured. Was evaluated.

For the measurement of SNR, OW, and BER, a read / write analyzer 1632 and spin stand S1701MP manufactured by Guzik, USA were used.
For the SNR, the output-to-noise ratio was calculated with S as the output at a linear recording density of 750 kFCI and N as the rms (root mean square) value at a linear recording density of 1500 kFCI.
On the other hand, OW was calculated as a reproduction output ratio (attenuation rate) of a 750 kFCI signal before and after overwriting a signal with a linear recording density of 100 kFCI after recording a signal with a linear recording density of 750 kFCI.
On the other hand, BER was similarly calculated by “−log (number of error bits / total number of bits)” when a signal was recorded at a linear recording density of 1500 kFCI.

  As a result, in Example 1, as shown in Table 1 above, ΔHc / Hc was 0.067, SNR was 20.7 dB, OW was 35.1 dB, and BER was 5.81.

(Examples 2 to 16)
In Examples 2 to 16, the composition of the seed layer using the eutectic target was the material shown in Table 1 above, and the etching gas was changed to Table 1 in the same manner as in Example 1 up to the granular magnetic layer. A film was formed.

  And about Examples 1-16, the planar TEM observation of the produced granular magnetic layer was performed, the average particle diameter <D> of the magnetic particle, and the particle size dispersion | distribution (sigma) / <D> normalized with this average particle diameter Was measured.

  As a result, as shown in Table 1 above, among Examples 1 to 16, the average particle diameter <D> of the 56Al44Si eutectic alloy of Example 1 was the smallest value of 5.5 nm.

  In addition, Table 1 shows the evaluation results of “ΔHc / Hc”, “SNR”, “OW”, and “BER” of Examples 2 to 16.

(Comparative Example 1)
In Comparative Example 1, as in Example 1, a cleaned glass substrate (manufactured by Konica Minolta, 2.5 inch outer diameter) is accommodated in a film forming chamber of a DC magnetron sputtering apparatus (C-3040, manufactured by Anelva). Then, after the inside of the film formation chamber was evacuated under reduced pressure until the ultimate vacuum reached 1 × 10 ⁻⁵ Pa, an adhesion layer having a thickness of 10 nm was formed on the glass substrate using a Cr target. Further, on this adhesion layer, the substrate temperature is set to 100 ° C. or less, and Co-20Fe-5Zr-5Ta {Fe content 20 atomic%, Zr content 5 atomic%, Ta content 5 atomic%, and the balance Co}. A soft magnetic layer having a layer thickness of 25 nm was formed using a target, a Ru layer having a layer thickness of 0.7 nm was formed thereon, and then a Co-20Fe-5Zr-5Ta target was used again to form a layer thickness. A 25 nm soft magnetic layer was formed and used as a soft magnetic backing layer.

Next, a seed layer having a layer thickness of 5 nm was formed on the soft magnetic underlayer using a 92Al-8Si eutectic target at a sputtering pressure of 0.5 Pa. Next, the surface of the AlSi thin film was dry-etched for 20 seconds at a CF ₄ gas of 40 sccm, a pressure in the reaction vessel of 0.5 Pa, an RF power of 300 W, and a substrate bias of 40 W. At this time, unlike the convex portions of Examples 1 to 16, a microcrystalline film having a concave portion was formed.

  Next, an alignment control layer having a layer thickness of 20 nm was formed using a Ru target. When forming the orientation control layer, Ru having a layer thickness of 10 nm was formed with a sputtering pressure of 0.8 Pa, and then Ru having a layer thickness of 10 nm was formed with a sputtering pressure of 1.5 Pa.

  Next, an alignment control layer having a layer thickness of 20 nm was formed using a Ru target. When forming the orientation control layer, Ru having a layer thickness of 10 nm was formed with a sputtering pressure of 0.8 Pa, and then Ru having a layer thickness of 10 nm was formed with a sputtering pressure of 1.5 Pa.

Next, on the orientation control layer, 91 (Co15Cr16Pt) -6 (SiO ₂ ) -3 (TiO ₂ ) {Cr content of 15 atomic%, Pt content of 18 atomic%, and the remaining Co alloy of 91 mol%, SiO 2 A magnetic layer having a thickness of 9 nm was formed using a target of 6 mol% of an oxide made of 3 mol% and 3 mol% of an oxide made of TiO ₂ . The sputtering pressure at this time was 2 Pa.

Next, on the magnetic layer, 92 (Co11Cr18Pt) -5 (SiO ₂ ) -3 (TiO ₂ ) {Cr content of 11 atomic%, Pt content of 18 atomic%, and the balance Co of 92 mol%, SiO ₂ A magnetic layer having a thickness of 6 nm was formed using a target of 5 mol% of an oxide composed of 3 mol% and 3 mol% of an oxide composed of TiO ₂ . The sputtering pressure at this time was 2 Pa.

  At this stage, planar TEM observation of the magnetic layer having a granular structure was performed. As a result, in Comparative Example 1, as shown in Table 1 above, <D> is 9.3 nm and σ / <D> is 16.4%, which is a boundary layer between magnetic particles as compared with Example 1. Was thin, and it was confirmed that the particles were not sufficiently separated.

  Next, a magnetic layer having a thickness of 7 nm is formed on the magnetic layer using a target of Co20Cr14Pt3B {Cr content 20 atomic%, Pt content 14 atomic%, B content 3 atomic%, balance Co}. did. The sputtering pressure at this time was 0.6 Pa.

  Next, a protective layer having a thickness of 3.0 nm is formed on the magnetic layer by a CVD method, and then a 1 nm thick lubricating film made of perfluoropolyether is formed by a dipping method. A recording medium was obtained.

  When the recording / reproduction characteristics of the magnetic recording medium of Comparative Example 1 were evaluated in the same manner as in Example 1, ΔHc / Hc was 0.164, SNR was 17.1 dB, OW was 38.8 dB, and BER was 3 .10.

(Comparative Example 2)
In Comparative Example 2, a magnetic recording medium was produced in the same manner as in Example 1 except that NiW was used as the seed layer. Specifically, using a Ni-6W {W content 6 atom%, remaining Ni} target, the layer thickness was 5 nm at a sputtering pressure of 0.6 Pa. Note that dry etching after forming the seed layer was not performed.

  The magnetic recording medium of Comparative Example 2 was also evaluated for the size of the magnetic particles and the recording / reproducing characteristics as in Example 1. As a result, in Comparative Example 2, as shown in Table 1 above, <D> is 8.8 nm, σ / <D> is 13.8, ΔHc / Hc is 0.122, SNR is 18.8 dB, and OW is It was 32.5 dB and BER was 3.81.

1 ... Non-magnetic substrate
2 ... Soft magnetic backing layer
3 ... Middle layer
4 ... perpendicular magnetic layer
4a: lower magnetic layer
4b ... middle magnetic layer
4c ... upper magnetic layer
5 ... Protective layer
6 ... Lubrication layer
7 ... Nonmagnetic layer
7a: lower nonmagnetic layer
7b: upper nonmagnetic layer
8 ... Nonmagnetic underlayer
9 ... Seed layer 11 ... Orientation control layer
11a ... uneven surface
12-14: Magnetic layer or nonmagnetic layer
S, S1 to S3 ... columnar crystals
30 ... Non-magnetic substrate
31 ... Soft magnetic underlayer
32 ... Seed layer
32a ... Crystal nucleus
33 ... Middle layer
34 ... perpendicular magnetic layer
50. Magnetic recording medium
51. Medium drive unit
52. Magnetic head
53. Head drive unit
54. Recording / reproducing signal processing system

Claims (15)

A method of manufacturing a magnetic recording medium in which a soft magnetic backing layer, a seed layer, an intermediate layer, and a perpendicular magnetic layer are sequentially laminated on at least a nonmagnetic substrate,
As the seed layer, after forming a eutectic alloy film containing two or more elements constituting a eutectic structure and in which columnar crystal nuclei are dispersed in a dot shape, the surface of the eutectic alloy film is formed. Etching is performed to form a microcrystalline film in which the crystal nuclei protrude from the surface.   After the eutectic alloy film is formed by sputtering, an etching process is performed on the surface of the eutectic alloy film using an etching gas containing at least one element selected from fluorine, chlorine, hydrogen, and oxygen. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein a microcrystalline film in which the crystal nuclei protrude from a surface is formed.   As the seed layer, at least one element selected from Al, Si, Ge, and C constituting the eutectic structure, and Al, Pd, Ag, Au, Sb, and Ru having a lower etching rate than this one element. , Cu, Pt, and other elements selected from Co, and after forming a eutectic alloy film in which columnar crystal nuclei are dispersed in the form of dots, the surface of the eutectic alloy film is formed. 3. The method of manufacturing a magnetic recording medium according to claim 2, wherein a microcrystalline film in which crystal nuclei containing the other elements protrude from the surface is formed by performing an etching process.   After forming a eutectic alloy film containing either AlRu or AlCu as the seed layer and in which columnar crystal nuclei are dispersed in the form of dots, the surface of the eutectic alloy film is etched. 4. The method of manufacturing a magnetic recording medium according to claim 3, wherein a microcrystalline film in which crystal nuclei containing either Ru or Cu protrude from the surface is formed.   After forming a eutectic alloy film containing AlSi, PdSi, AgSi, or AuSi as the seed layer and having columnar crystal nuclei dispersed in a dot shape, the surface of the eutectic alloy film is formed. 4. The method of manufacturing a magnetic recording medium according to claim 3, wherein a microcrystalline film in which crystal nuclei containing any of Si, Si, Si, and Si protrude from the surface is formed by performing an etching process.   After forming a eutectic alloy film containing any of AlGe, PdGe, AgGe, AuGe, and SbGe as the seed layer and having columnar crystal nuclei dispersed in a dot shape, the surface of the eutectic alloy film is formed. 4. The method of manufacturing a magnetic recording medium according to claim 3, wherein a microcrystalline film in which crystal nuclei containing Al, Pd, Ag, Au, and Sb protrude from the surface is formed by performing an etching process. .   After forming a eutectic alloy film containing RuC, PtC, or CoC as a seed layer and having columnar crystal nuclei dispersed in a dot shape, the surface of the eutectic alloy film is etched. The method of manufacturing a magnetic recording medium according to claim 3, wherein a microcrystalline film in which crystal nuclei containing any one of Ru, Pt, and Co protrude from the surface is formed by applying.   The method for manufacturing a magnetic recording medium according to claim 1, wherein a Co alloy film having an amorphous structure is formed as the soft magnetic backing layer.   The method for manufacturing a magnetic recording medium according to claim 1, wherein a Ru or Ru alloy film is formed as the intermediate layer.   Each layer is crystal-grown starting from the seed layer so that the crystal grains constituting the perpendicular magnetic layer constitute columnar crystals continuous in the thickness direction together with the crystal grains constituting the intermediate layer. Item 10. A method for manufacturing a magnetic recording medium according to any one of Items 1 to 9. A magnetic recording medium in which a soft magnetic backing layer, a seed layer, an intermediate layer, and a perpendicular magnetic layer are laminated in this order on at least a nonmagnetic substrate,
The seed layer is composed of a microcrystalline film with crystal nuclei protruding from the surface,
The magnetic recording medium according to claim 1, wherein the intermediate layer and the perpendicular magnetic layer form columnar crystals in which the crystal grains are continuous in the thickness direction starting from the crystal nucleus.   The seed layer is formed of a microcrystalline film in which a crystal nucleus mainly composed of an element selected from Al, Pd, Ag, Au, Sb, Ru, Pt, and Co protrudes from the surface. 11. A magnetic recording medium according to 11.   The magnetic recording medium according to claim 11, wherein the soft magnetic underlayer is made of a Co alloy film having an amorphous structure.   The magnetic recording medium according to claim 11, wherein the intermediate layer is made of Ru or a Ru alloy film. The magnetic recording medium manufactured by the manufacturing method according to any one of claims 1 to 10, or the magnetic recording medium according to any one of claims 11 to 14,
A magnetic recording / reproducing apparatus comprising: a magnetic head for recording / reproducing information with respect to the magnetic recording medium.

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