JP5244678B2 - Method for manufacturing magnetic recording medium - Google Patents

Description

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

  The recording density of a hard disk drive (HDD), which is a kind of magnetic recording / reproducing device, is currently increasing at an annual rate of 50% or more, and it is said that this trend will continue in the future. Along with this, development of magnetic heads and magnetic recording media suitable for high recording density is underway.

  Currently, a magnetic recording medium mounted on a commercially available magnetic recording / reproducing apparatus is a so-called perpendicular magnetic recording medium in which an easy axis of magnetization in a magnetic film is oriented mainly vertically. 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, since the recording bit volume decreases with the increase in recording density, the thermal fluctuation effect is strong. For this reason, in recent years, much attention has been paid and a medium structure suitable for perpendicular magnetic recording has been proposed.

  In order to meet the demand for higher recording density of magnetic recording media, it has been studied to use a single-pole head having excellent writing ability for the perpendicular magnetic layer. In order to deal with such a single magnetic pole head, a soft magnetic underlayer made of a soft magnetic material is provided between a perpendicular magnetic layer as a recording layer and a nonmagnetic substrate. A so-called two-layer magnetic recording medium has been proposed in which the efficiency of magnetic flux entry and exit between the two is improved.

  In other words, this two-layer magnetic recording medium has a function of increasing the recording magnetic field gradient by spatially concentrating the recording magnetic field by strengthening the recording magnetic field from the main magnetic pole of the magnetic recording head by the mirror image effect of the soft magnetic underlayer. There is.

  However, simply using a magnetic recording medium provided with a soft magnetic underlayer is not satisfactory in recording / reproduction characteristics, thermal fluctuation resistance, and recording resolution at the time of recording / reproduction. A magnetic recording medium excellent in these characteristics is not available. It is requested.

  For example, in Patent Document 1 below, in a perpendicular magnetic recording medium in which a perpendicular magnetic film and a protective lubricating film are provided on a nonmagnetic substrate via a backing magnetic layer, the backing magnetic layer is antiferromagnetically coupled to the backing magnetic layer. A magnetic flux leakage generated from the magnetic wall of the magnetic layer is prevented from flowing into the read head, and the magnetic wall present in the backing magnetic layer is fixed so that it does not move easily, thereby realizing a perpendicular magnetic recording medium having low noise characteristics. It is described.

  In Patent Document 2 below, a soft magnetic layer is formed from a plurality of layers, and a separation layer is provided between the soft magnetic layers, thereby increasing the magnetic permeability of the soft magnetic layer and reducing the magnetization transition region of the magnetic recording layer. It is described that a leakage magnetic field or a magnetic field from a magnetic head is drawn into a soft magnetic layer, the magnetism recorded in the magnetic recording layer is stabilized, and a writing magnetic field from the magnetic head is more effectively drawn out.

  In Patent Document 3 below, in order to set the film forming gas pressure when forming the soft magnetic film to 2 Pa to 30 Pa, one or more of Ne, Ar, Kr, and Xe are used as the film forming gas. It is described. Further, it is described that this can suppress the formation of domain walls in the soft magnetic film and prevent the occurrence of spike noise.

  Further, in Patent Document 4 below, when a soft magnetic layer is produced by magnetron sputtering, the film forming speed is kept high by using Xe and / or Kr having an atomic radius larger than that of Ar, and a desired film thickness is obtained. It is described that a soft magnetic layer can be produced in a short time and at low cost.

JP 2001-331920 A JP 2001-250223 A JP 2004-030740 A JP 2004-234746 A

  In the magnetic recording / reproducing apparatus using the perpendicular magnetic recording medium described above, leakage magnetic flux generated from the domain wall of the soft magnetic underlayer is prevented from flowing into the magnetic head, and the domain wall existing in the soft magnetic underlayer easily moves. In order to achieve low noise characteristics, the soft magnetic underlayer is composed of a plurality of layers, and each layer is antiferromagnetic coupling (anti-ferro coupling coupling, hereinafter referred to as AFC coupling). It is preferable to make it.

  However, the inventor's research shows that when such a complicated multilayer structure is provided in the lowermost layer of the magnetic recording medium, the surface roughness of the magnetic recording medium is deteriorated, and thereby the scratch resistance of the magnetic recording medium is lowered. It became clear. This is presumably because the surface of the substrate is contaminated before and after the start of sputtering of each layer, and this contaminant reduces the density of the entire film and increases the roughness of the growth surface. Also, gas particles used for sputtering are mixed into the film, which causes a decrease in the density of the film.

  The present invention has been proposed in view of such conventional circumstances, and is intended to cope with higher recording density by increasing the density of the soft magnetic underlayer and decreasing the surface roughness. An object of the present invention is to provide a method for manufacturing a magnetic recording medium, and a magnetic recording / reproducing apparatus including the magnetic recording medium manufactured by such a method.

  As a result of intensive studies to solve the above problems, the present inventor uses Kr or Xe as the sputtering gas when forming the soft magnetic layer by the sputtering method, and the sputtering gas pressure is set to 0.3 Pa or less. By this, it becomes possible to generate high-energy sputtered particles, and gas particles mixed in the film are reduced, and it is found that a soft magnetic underlayer having a high density and a high flatness can be formed. The present invention has been completed.

That is, the present invention provides the following means.
(1) a soft magnetic underlayer in which a plurality of soft magnetic layers are antiferromagnetically coupled on at least a nonmagnetic substrate, and a perpendicular magnetic layer whose easy axis is oriented perpendicularly to the nonmagnetic substrate; A method for producing a magnetic recording medium comprising:
A method of manufacturing a magnetic recording medium, wherein the soft magnetic layer is formed by a sputtering method, Kr or Xe is used as a sputtering gas, and the pressure of the sputtering gas is set to 0.3 Pa or less.
(2) A method of manufacturing a magnetic recording medium according to the pressure of the sputtering gas in the preceding paragraph (1), characterized in that the 0.1Pa or less.

  As described above, according to the present invention, it is possible to form a soft magnetic underlayer having a high density and a high density, and the surface of the magnetic layer or the like formed thereon is also smoothed, It becomes possible to manufacture a magnetic recording medium with high smoothness. Further, when such a magnetic recording medium is used, the flying height of the magnetic head can be reduced, and the electromagnetic conversion characteristics of the magnetic recording / reproducing apparatus can be improved. Further, in such a magnetic recording medium, the hardness of the soft magnetic underlayer serving as the base of the laminated structure is increased, so that the scratch resistance on the medium surface can be increased. Therefore, it is possible to provide a highly reliable magnetic recording / reproducing apparatus.

It is sectional drawing which shows an example of the magnetic recording medium manufactured by applying this invention. It is sectional drawing which expands and shows the laminated structure of the magnetic recording medium shown in FIG. 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.

(Method of manufacturing magnetic recording medium)
The present invention includes a soft magnetic underlayer in which a plurality of soft magnetic layers are antiferromagnetically coupled on at least a nonmagnetic substrate, and a perpendicular magnetic layer having an easy axis of magnetization oriented perpendicularly to the nonmagnetic substrate. A soft magnetic layer is formed by sputtering, Kr or Xe is used as a sputtering gas, and the pressure of the sputtering gas is 0.3 Pa or less. To do.

  In the present invention, in order to accurately measure the gas pressure, the vacuum gauge and the measurement place are carefully evaluated. That is, since inert gases such as Ar, Kr, and Xe have greatly different ionization degrees, it is difficult to obtain an accurate gas pressure with an ionization vacuum gauge. Therefore, in the present invention, the gas pressure of each inert gas was evaluated with a diaphragm vacuum gauge that is not affected by the degree of ionization. The gas pressure was measured near the cathode as close to the discharge space as possible.

Here, Table 1 shows the atomic weight, ionization potential [eV], and atomic radius [Å] of He, Ne, Ar, Kr, and Xe, which are inert gases.
Conventionally, an inert gas such as Ar is used as the sputtering gas. On the other hand, Kr or Xe used for sputtering the soft magnetic layer in the present invention has a lower ionization potential than Ar conventionally used.

  Therefore, in the present invention, when the soft magnetic layer is formed by sputtering, Kr or Xe can be used as a sputtering gas, so that the discharge can be performed at a lower pressure than when Ar is used. Can be lowered.

  Further, according to the study of the present inventor, the Ar sputterable gas pressure is 0.4 Pa or higher for the soft magnetic alloy generally used as the soft magnetic underlayer of the magnetic recording medium. The gas pressure capable of sputtering Kr or Xe is 0.01 Pa or more.

  Examples of the soft magnetic alloy include CoFe alloys (CoFeTaZr, CoFeZrNb, etc.), CoZr alloys (CoZrNb, CoZrTa, CoZrCr, CoZrMo, etc.), FeCo alloys (FeCo, FeCoV, etc.), and FeNi alloys. Alloys (FeNi, FeNiMo, FeNiCr, FeNiSi, etc.), FeAl alloys (FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, FeAlO, etc.), FeCr alloys (FeCr, FeCrTi, FeCrCu, etc.), FeTa alloys (FeTa, FeTaC, etc.) , FeTaN, etc.), FeMg alloys (FeMgO, etc.), FeZr alloys (FeZrN, etc.), FeC alloys, FeN alloys, FeSi alloys, FeP alloys, FeNb alloys, eHf-based alloy, and the like can be given FeB-based alloy.

  In particular, when the soft magnetic underlayer is formed by sputtering using Kr or Xe as the soft magnetic alloy and a gas pressure in the range of 0.1 Pa to 0.3 Pa, the density of the soft magnetic underlayer is reduced. In addition, a soft magnetic underlayer having high flatness can be formed. This is because the sputtering pressure is reduced, gas particles are mixed into the film, and the mass of the sputtered particles is increased, so that the sputtered particles become high energy and the density and flatness of the film are increased. It is done.

FIG. 1 shows an example of a magnetic recording medium manufactured by applying the present invention.
As shown in FIG. 1, this magnetic recording medium includes a soft magnetic underlayer 2, an orientation control layer 3, a perpendicular magnetic layer 4, a carbon protective layer 5, and a lubricating layer 6 on a nonmagnetic substrate 1. Are sequentially stacked.

  Among these, the soft magnetic underlayer 2 and the orientation control layer 3 constitute an underlayer. The soft magnetic underlayer 2 includes two soft magnetic layers 2a that are AFC (anti-ferro-coupled) coupled via a spacer layer 2b. The perpendicular magnetic layer 4 includes three layers of a lower magnetic layer 4a, an intermediate magnetic layer 4b, and an upper magnetic layer 4c, and the nonmagnetic layer 7a is formed between the magnetic layer 4a and the magnetic layer 4b. By sandwiching the nonmagnetic layer 7b between 4b and the magnetic layer 4c, the magnetic layers 4a to 4c and the nonmagnetic layers 7a and 7b are alternately stacked.

  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 underlayer 2 mainly composed of Co or Fe, there is a possibility that the corrosion progresses due to the adsorption gas on the surface, the influence of moisture, the diffusion of the 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 underlayer 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 underlayer 2, for example, a 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.

  The soft magnetic underlayer 2 has a microcrystalline structure such as FeAlO, FeMgO, FeTaN, FeZrN or the like containing Fe of 60 at% (atomic%) or more, or a granular structure in which fine crystal particles are dispersed in a matrix. Materials can be used.

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

  The coercive force Hc of the soft magnetic underlayer 2 is preferably 100 Oe or less (preferably 20 Oe or less). 1 Oe is 79 A / m. When the coercive force Hc exceeds the above range, the soft magnetic characteristics are insufficient, and the reproduced waveform is changed from a so-called rectangular wave to a distorted waveform, which is not preferable.

  The saturation magnetic flux density Bs of the soft magnetic underlayer 2 is preferably 0.6 T or more (preferably 1 T or more). If this Bs is less than the above range, the reproduced waveform becomes a waveform having distortion from a so-called rectangular wave, which is not preferable.

  The product Bs · t (T · nm) of the saturation magnetic flux density Bs (T) of the soft magnetic underlayer 2 and the layer thickness t (nm) of the soft magnetic underlayer 2 is 15 T · nm or more (preferably 25 T · nm). nm or more). If this Bs · t is less than the above range, the reproduced waveform will be distorted and the OW (OverWrite) characteristic (recording characteristic) will be deteriorated.

  In the soft magnetic underlayer 2, a Ru film is provided as a spacer layer 2b between two soft magnetic layers 2a. Further, by adjusting the film thickness of the Ru film, the two soft magnetic layers 2a have an AFC structure. By adopting such an AFC structure, so-called spike noise can be suppressed. The soft magnetic underlayer 2 is preferably composed of at least two or more soft magnetic layers 2a, and a Ru film is preferably provided as a spacer layer 2b between the soft magnetic layers 2a.

  The outermost surface (surface on the orientation control layer 3 side) of the soft magnetic underlayer 2 is preferably formed by partially or completely oxidizing the material constituting the soft magnetic underlayer 2. For example, the material constituting the soft magnetic underlayer 2 is partially oxidized on the surface of the soft magnetic underlayer 2 (surface on the orientation control layer 3 side) and its vicinity, or an oxide of the above material is formed. Are preferably arranged. Thereby, since the magnetic fluctuation of the surface of the soft magnetic underlayer 2 can be suppressed, the noise caused by the magnetic fluctuation can be reduced and the recording / reproducing characteristics of the magnetic recording medium can be improved.

  Here, in the present invention, when the soft magnetic layer 2a is formed by the sputtering method, Kr or Xe is used as the sputtering gas, and the pressure of the sputtering gas is 0.3 Pa or less, preferably 0.1 Pa to 0.00. It shall be in the range of 3 Pa.

  As shown in Table 1 above, since Kr and Xe have a lower ionization potential than Ar, they are easily ionized even at a low gas pressure. On the other hand, since the atomic weight is large, high-energy sputtered particles can be formed. .

  This effect is greater for Xe than for Kr. Therefore, in order to express the effect of the present invention, 40% by volume or more of Kr and 30% by volume or more of Xe are contained in other inert gases such as Ar. It is preferable to use a sputtering gas. Furthermore, it is preferable to contain as much Kr or Xe as possible in the sputtering gas, and most preferably, Xe is used at 100%.

  The orientation control layer 3 can improve the recording / reproducing characteristics by refining the crystal grains of the perpendicular magnetic layer 4. Such a material is not particularly limited, but a material having an hcp structure, an fcc structure, or an amorphous structure is preferable. In particular, Ru-based alloys, Ni-based alloys, Co-based alloys, Pt-based alloys, and Cu-based alloys are preferable, and these alloys may be multilayered. For example, it is preferable to adopt a multilayer structure of Ni-based alloy and Ru-based alloy, a multilayer structure of Co-based alloy and Ru-based alloy, or a multilayer structure of Pt-based alloy and Ru-based alloy from the substrate side.

  For example, in the case of a Ni-based alloy, it is made of at least one material selected from NiW alloy, NiTa alloy, NiNb alloy, NiTi alloy, NiZr alloy, NiMn alloy and NiFe alloy containing 33 to 96 at% Ni. Is preferred. Further, it may be a nonmagnetic material containing 33 to 96 at% Ni and containing at least one or more of Sc, Y, Ti, Zr, Hf, Nb, Ta, and C. In this case, the Ni content is preferably in the range of 33 at% to 96 at% in order to maintain the effect as the orientation control layer 3 and to have a range without magnetism.

  The thickness of the orientation control layer 3 is preferably 5 to 40 nm, more preferably 8 to 30 nm, as the total thickness in the case of multiple layers. When the thickness of the orientation control layer 3 is within the above range, the perpendicular orientation of the perpendicular magnetic layer 4 is particularly high, and the distance between the magnetic head and the soft magnetic underlayer 2 during recording can be reduced. The recording / reproducing characteristics can be improved without reducing the signal resolution.

  On the other hand, when the thickness of the orientation control layer 3 is less than the above range, the perpendicular orientation in the perpendicular magnetic layer 4 is lowered, and the recording / reproducing characteristics and the thermal fluctuation resistance are degraded. On the other hand, if the thickness of the orientation control layer 3 exceeds the above range, the magnetic particle diameter of the perpendicular magnetic layer 4 is increased, and noise characteristics may be deteriorated. In addition, since the distance between the magnetic head and the soft magnetic underlayer 2 during recording increases, the resolution of the reproduction signal and the reproduction output decrease.

  Since the surface shape of the orientation control layer 3 affects the surface shape of the perpendicular magnetic layer 4 and the protective layer 5, the surface irregularities of the magnetic recording medium are reduced to reduce the flying height of the magnetic head during recording and reproduction. For this, the surface average roughness Ra of the orientation control layer 3 is preferably 2 nm or less. Thereby, the unevenness on the surface of the magnetic recording medium can be reduced, the flying height of the magnetic head during recording and reproduction can be sufficiently lowered, and the recording density can be increased.

  Further, oxygen, nitrogen, or the like may be introduced into the gas for forming the orientation control layer 3. For example, when a sputtering method is used as the film forming method, the process gas is a gas in which oxygen is mixed in an amount of 0.05 to 50% (preferably 0.1 to 20%) by volume with argon, and nitrogen is added to argon. Is preferably used in a volume ratio of 0.01 to 20% (preferably 0.02 to 10%).

Further, the orientation control layer 3 may have a structure in which metal particles are dispersed in an oxide, a metal nitride, or a metal carbide. 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. Furthermore, for example, NiTa—SiO ₂ , RuCo—Ta ₂ O ₅ , Ru—SiO ₂ , Pt—Si ₃ N ₄ , Pd—TaC, or the like can be used.

  The content of the oxide, metal nitride, or metal carbide in the orientation control layer 3 is preferably 1 mol% or more and 12 mol% or less with respect to the alloy. When the content of oxide, metal nitride, or metal carbide in the orientation control layer 3 exceeds the above range, the oxide, metal nitride, or metal carbide remains in the metal particles, and the crystallinity of the metal particles and In addition to impairing the orientation, the crystallinity and orientation of the magnetic layer formed on the orientation control layer 3 may be impaired. Moreover, when the content of the oxide, metal nitride, or metal carbide in the orientation control layer 3 is less than the above range, it is not preferable because the effect of addition of the oxide, metal nitride, or metal carbide cannot be obtained. .

  Here, in the initial part of the perpendicular magnetic layer 4 immediately above the orientation control 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. For this reason, it is preferable to provide a nonmagnetic underlayer 8 between the orientation control layer 3 and the perpendicular magnetic layer 4 as shown in FIG.

The nonmagnetic underlayer 8 is preferably made of a material mainly containing Co and further containing an oxide. The Cr content is preferably 25 at% (atomic%) or more and 50 at% 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.

As shown in FIG. 2, the magnetic layer 4a is made of a material containing Co as a main component and an oxide 41. Examples of the oxide 41 include Cr, Si, Ta, Al, Ti, Mg, and Co. It is preferable to use an oxide such as 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.

  In the magnetic layer 4a, it is preferable that magnetic particles (crystal grains having magnetism) 42 are dispersed in the layer. 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 4 at% or more and 19 at% or less (more preferably 6 at% or more and 17 at% 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 at% or more and 20 at% 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 at%. On the other hand, if it exceeds 20 at%, 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 at% or less. If it exceeds 8 at%, 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, resulting in recording / reproducing characteristics and thermal fluctuation characteristics suitable for high-density recording. Is not preferred because it cannot be obtained.

As a material suitable for the magnetic layer 4a, for example, 90 (Co14Cr18Pt) -10 (SiO ₂ ) {Cr content 14at%, Pt content 18at%, molar concentration calculated as one compound with magnetic particles composed of the remaining Co. Is 90 mol%, the oxide composition 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 O ₃ ), (CoCrPtTaNd) — (MgO), (CoCrPtBCu) — (Y ₂ O ₃ ), (CoCrPtRu) — (SiO ₂ ), and the like.

As shown in FIG. 2, the magnetic layer 4 b is preferably made of a material containing Co as a main component and further containing an oxide 41. The oxide 41 is preferably an oxide of Cr, Si, Ta, Al, Ti, Mg, and Co. Of these, TiO ₂ , Cr ₂ O ₃ , and SiO ₂ can be preferably used. The magnetic layer 4b is preferably made of a composite oxide to which two or more types of oxides 41 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.

  In the magnetic layer 4b, it is preferable that magnetic particles (crystal particles having magnetism) 42 are dispersed in the layer. The magnetic particles 42 preferably form 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 content of the oxide 41 in the magnetic layer 4b is preferably 3 mol% or more and 18 mol% or less with respect to the total amount of compounds such as Co, Cr, and Pt constituting the magnetic particles 42. 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 4b. When the magnetic layer 4b 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. Further, 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 / 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 4b is preferably 4 at% or more and 18 at% or less (more preferably 8 at% or more and 15 at% 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, resulting in 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 Pt content in the magnetic layer 4b is preferably 10 at% or more and 22 at% or less. The content of Pt in the above range is less than 10 at% because the magnetic anisotropy constant Ku required for the perpendicular magnetic layer 4 is not preferable. On the other hand, if it exceeds 22 at%, a stacking fault occurs inside the magnetic particle 42, and as a result, the magnetic anisotropy constant Ku becomes low, which is not preferable. 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.

  The magnetic layer 4b includes one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and the oxide 41. 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 at% or less. If it exceeds 8 at%, 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, resulting in recording / reproducing characteristics and thermal fluctuation characteristics suitable for high-density recording. Is not preferred because it cannot be obtained.

  As shown in FIG. 2, the magnetic layer 4c is preferably made of a material containing Co as a main component and not containing the oxide 41, and the magnetic particles 42 in the layer are columnar from the magnetic particles 42 in the magnetic layer 4a. Preferably, the structure is 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 at% or more and 24 at% 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 8 at% or more and 20 at% 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 at% or less. On the other hand, if it exceeds 16 at%, 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, resulting in recording / reproduction characteristics suitable for high-density recording. This is not preferable because 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 at% or more and 28 at% or less.

  Suitable materials for the magnetic layer 4c include, for example, Co14-24Cr8-22Pt {Cr content 14-24at%, Pt content 8-22at%, balance Co} in CoCrPt series, Co10-24Cr8 ~ in CoCrPtB series. 22Pt0-16B {Cr content: 10-24at%, Pt content: 8-22at%, B content: 0-16at%, balance Co} is preferable. In other systems, Co10-24Cr8-22Pt1-5Ta {Cr content 10-24at%, Pt content 8-22at%, Ta content 1-5at%, balance Co} in CoCrPtTa system, Co10 in CoCrPtTaB system -24Cr8-22Pt1-5Ta1-10B {Cr content 10-24at%, Pt content 8-22at%, Ta content 1-5at%, B content 1-10at%, balance Co}, CoCrPtBNd Examples thereof include materials such as a CoCrPtTaNd system, a CoCrPtNb system, a CoCrPtBW system, a CoCrPtMo system, a CoCrPtCuRu system, and a CoCrPtRe system.

  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.

  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. 2) 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.

  That is, the thickness of the nonmagnetic layer 7 is a range in which the magnetostatic coupling of each layer constituting the perpendicular magnetic layer 4 is not completely broken, specifically 0.1 nm or more and 2 nm or less (more preferably 0.1 or more and 0.8 nm). Or less).

  When the three or more magnetic layers 4a, 4b, 4c of the present invention are ferromagnetically coupled (ferro coupling coupling, hereinafter referred to as FC coupling) and magnetostatic coupling is completely broken, M Since the −H loop becomes a loop that reverses in two stages, it can be easily discriminated. When this two-stage loop occurs, it means that the magnetic grains do not reverse all at once with respect to the magnetic field from the magnetic head, and as a result, the S / N ratio at the time of reproduction is significantly deteriorated and the resolution is lowered. Therefore, it is not preferable.

  However, when Ru or Ru alloy is used, AFC coupling occurs in the range of 0.6 nm to 1.2 nm. In the present invention, it is essential that each magnetic layer 4a, 4b, 4c is magnetostatically coupled by FC instead of AFC coupling.

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, CoCrX ₁ alloy _{(X 1} is, Pt, Ta, Zr, Re , Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W , 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 at%. 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, CrX ₂ (X ₂ represents at least one element selected from Ti, W, Mo, Nb, Ta, Si, Al, B, C, and Zr. ) And the like can be preferably used. In this case, the Cr content is preferably 60 at% 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.

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.

(Magnetic recording / reproducing device)
FIG. 3 shows an example of a magnetic recording / reproducing apparatus to which the present invention is applied.
The magnetic recording / reproducing apparatus includes a magnetic recording medium 50 having the configuration shown in FIG. 1, a medium driving unit 51 that rotationally drives the magnetic recording medium 50, a magnetic head 52 that records and reproduces information on the magnetic recording medium 50, and A head driving unit 53 that moves the magnetic head 52 relative to the magnetic recording medium 50 and a recording / reproducing signal processing system 54 are provided. 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. Further, as the magnetic head 52 used in the magnetic recording / reproducing apparatus to which the present invention is applied, a magnetic head suitable for a higher recording density having a GMR element utilizing a giant magnetoresistance effect (GMR) as a reproducing element is used. be able to.

  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 inches in outer diameter) is accommodated in a film forming chamber of a DC magnetron sputtering apparatus (C-3040 made by Anelva Co., Ltd.), and the ultimate vacuum After the inside of the film formation chamber was evacuated to 1 × 10 ⁻⁵ Pa, an adhesion layer having a layer thickness of 10 nm was formed on the glass substrate using a Cr target. Further, on this adhesion layer, a layer thickness of 25 nm is obtained at a substrate temperature of 100 ° C. or lower using a target of 55Fe-30Co-15Ta {Fe content 55 at%, Co content 30 at%, Ta content 15 at%}. A soft magnetic layer is formed, and a Ru layer is formed thereon with a thickness of 1.6 nm. Then, a Co-20Fe-5Zr-5Ta soft magnetic layer is further formed with a thickness of 25 nm. An underlayer was used.

  Further, a DC magnetron sputtering method was used for forming the soft magnetic layer. As the sputtering gas, Kr (concentration 100%) was used, and the discharge gas pressure was 0.1 Pa.

  Next, on the soft magnetic underlayer 2, Ni-6W {W content 6 at%, remaining Ni} target and Ru target were sequentially formed with a layer thickness of 5 nm and 20 nm, respectively. The control layer was used.

Next, on the alignment control layer _{3, (Co15Cr16Pt) 91- (SiO} 2) 6- (TiO 2) 3 {Cr content 15 at%, Pt content of 18 at%, 91 mol% of the alloy the remainder Co, SiO ₂ A magnetic layer having a composition of 6 mol% of an oxide composed of 3 mol% of an oxide composed of Cr ₂ O ₃ and 3 mol% of an oxide composed of TiO ₂ was formed with a sputtering pressure of 2 Pa and a layer thickness of 3 nm. In this magnetic layer, Ku was 2.2 × 10 ⁶ (erg / cc) and Ms was 500 (emu / cc).

Next, on the magnetic layer was deposited at a layer thickness of 0.3nm nonmagnetic layer composed of _{(Co30Cr) 88- (TiO 2)} 12.

Next, on the non-magnetic layer was formed by _(Co11Cr18Pt) 92- thickness 4nm and (SiO 2) 5-magnetic layer made of _(TiO 2) 3 as a sputtering pressure 2 Pa.

Next, a nonmagnetic layer made of Ru was formed with a layer thickness of 0.3 nm on the magnetic layer. In this magnetic layer, Ku was 4 × 10 ⁶ (erg / cc) and Ms was 600 (emu / cc).

Next, a magnetic layer is formed on the nonmagnetic layer using a target composed of Co20Cr14Pt3B {Cr content 20 at%, Pt content 14 at%, B content 3 at%, balance Co} and a sputtering pressure of 0.6 Pa. The film was formed with a layer thickness of 4 nm. In this magnetic layer, Ku was 1.5 × 10 ⁶ (erg / cc), and Ms was 400 (emu / cc).

  Next, a protective layer having a thickness of 3.0 nm was formed by a CVD method, and then a lubricating layer made of perfluoropolyether was formed by a dipping method to obtain a magnetic recording medium of Example 1.

(Example 2)
In Example 2, Kr (concentration: 100%) was used as the sputtering gas for forming the soft magnetic layer, but the discharge gas pressure was 0.3 Pa. Otherwise, the magnetic recording medium was manufactured under the same conditions as in Example 1.

(Comparative Example 1)
In Comparative Example 1, Ar (concentration 100%) was used as the sputtering gas for forming the soft magnetic underlayer. In Ar, discharge at 0.1 Pa was not possible, so the discharge gas pressure was 3 Pa. Otherwise, the magnetic recording medium was manufactured under the same conditions as in Example 1.

(Comparative Example 2)
In Comparative Example 2, Kr (concentration 100%) was used as the sputtering gas for forming the soft magnetic underlayer, but the discharge gas pressure was 3 Pa. Otherwise, the magnetic recording medium was manufactured under the same conditions as in Example 1.

(Comparative Example 3)
In Comparative Example 3, Kr (concentration 100%) was used as the sputtering gas for forming the soft magnetic underlayer, but the discharge gas pressure was 0.5 Pa. Otherwise, the magnetic recording medium was manufactured under the same conditions as in Example 1.

(Comparative Example 4)
In Comparative Example 4, Kr (concentration 100%) was used as the sputtering gas for forming the soft magnetic underlayer, but the discharge gas pressure was 1 Pa. Otherwise, the magnetic recording medium was manufactured under the same conditions as in Example 1.

  The magnetic recording media of Examples 1 and 2 and Comparative Examples 1 to 4 were evaluated using the read / write analyzer RWA1632 and spin stand S1701MP manufactured by GUZIK, Inc. Went. The evaluation results are shown in Table 2.

  As the magnetic head, a head using a single pole magnetic pole on the writing side and a TMR element on the reading side was used. The S / N ratio was measured as a recording density of 750 kFCI.

  Further, the magnetic recording media of Examples 1 and 2 and Comparative Examples 1 to 4 were subjected to a scratch test for evaluating scratch resistance. The scratch test was performed using a SAF tester manufactured by Kubota. As test conditions, the magnetic recording medium was rotated at 12000 rpm, and the seek operation was repeated on the disk surface at a speed of 5 inches / second for 2 hours using a PP6 head, and then the presence or absence of scratches was confirmed with an optical microscope. Then, such a scratch test was performed on each of the 20 magnetic recording media of Examples 1 and 2 and Comparative Examples 1 to 4, and the occurrence rate (%) of the scratch was obtained. The evaluation results are shown in Table 2.

  From the evaluation results shown in Table 2, the magnetic recording media of Examples 1 and 2 that are within the scope of the present invention are more electromagnetic conversion characteristics and scratch resistant than the magnetic recording media of Comparative Examples 1 to 4 that are outside the scope of the present invention. It turns out that it is excellent in.

1 ... Non-magnetic substrate
2. Soft magnetic underlayer
2a ... magnetic layer 2b ... spacer layer 3 ... orientation control layer
4 ... perpendicular magnetic layer
4a: lower magnetic layer
4b ... middle magnetic layer
4c ... upper magnetic layer
5 ... Protective layer
6 ... Lubrication layer
7, 7a, 7b ... nonmagnetic layer
8 ... Nonmagnetic underlayer
7a: lower nonmagnetic layer
7b: upper nonmagnetic layer
41 ... Oxides
42 ... Magnetic particles (non-magnetic particles in the layers 7a and 7b)
50. Magnetic recording medium
51. Medium drive unit
52. Magnetic head
53. Head drive unit
54. Recording / reproducing signal processing system

Claims (2)

A soft magnetic underlayer obtained by antiferromagnetically coupling a plurality of soft magnetic layers on at least a nonmagnetic substrate;
A method of manufacturing a magnetic recording medium comprising a perpendicular magnetic layer having an easy axis of magnetization oriented perpendicularly to the non-magnetic substrate,
A method of manufacturing a magnetic recording medium, wherein the soft magnetic layer is formed by a sputtering method, Kr or Xe is used as a sputtering gas, and the pressure of the sputtering gas is set to 0.3 Pa or less. Method for producing a magnetic recording medium according to claim 1, characterized in that at most 0.1Pa pressure of the sputtering gas.

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