Method for manufacturing magnetic recording media

Abstract

A magnetic recording medium manufacturing method according to the present invention is a method for manufacturing a magnetic recording medium comprising a substrate, an underlayer, and a perpendicular magnetic layer having an L10 structure in this order, the method comprising a step in which after forming the perpendicular magnetic layer, the surface of the perpendicular magnetic layer is heated with LED light emitted from an LED light source to increase the crystal orientation of the perpendicular magnetic layer, wherein the underlayer contains an NaCl-type compound, and the LED light has a central wavelength of less than 500 nm.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a magnetic recording medium and a magnetic recording and reproducing device. [Background technology]

[0002] Magnetic recording media are widely used as recording media for recording and storing various types of data. Magnetic recording media generally have a non-magnetic substrate on which a soft magnetic layer, an underlayer, a perpendicular magnetic layer, and a protective layer are laminated in this order.

[0003] While CoCr-based alloys have traditionally been used for perpendicular magnetic layers, FePt alloys with an L10 ordered structure are known as materials with higher perpendicular magnetic anisotropy than CoCr-based alloys. It is known that the L10 ordering of FePt alloys requires heat treatment at high temperatures of 400°C or higher (see, for example, Patent Document 1).

[0004] As a magnetic recording medium using a perpendicular magnetic layer containing an FePt alloy, for example, a thermally assisted magnetic recording magnetic recording medium has been disclosed, which is formed by sequentially stacking an orientation control underlayer formed using an alloy with a BCC structure containing Cr as the main component, a (100)-oriented crystalline underlayer containing W, a barrier layer containing MgO with an NaCl structure, and a magnetic layer containing an FePt alloy with an L10 structure (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2011-40121 [Patent Document 2] Japanese Patent Application Publication No. 2015-88197 Summary of the Invention [Problem to be solved by the invention]

[0006] As the range of applications of magnetic recording and reproducing devices expands, there is a demand for further improvements in the recording density of magnetic recording media. One method for increasing the recording density of magnetic recording media is to increase the heating temperature during magnetic layer formation and thereby improve the crystalline orientation of the perpendicular magnetic layer.

[0007] However, increasing the heating temperature of the perpendicular magnetic layer also has the effect of heating the underlayer, soft magnetic layer, and non-magnetic substrate, resulting in the following problems: elements constituting the underlayer diffuse into other layers, impairing the functions of those layers; the alloy constituting the soft magnetic layer crystallizes, impairing the soft magnetic properties; and distortion in the non-magnetic substrate is relaxed, causing the crystals contained in the non-magnetic substrate to coarsen, resulting in waviness on the surface of the magnetic recording medium.

[0008] An object of one aspect of the present invention is to provide a method for manufacturing a magnetic recording medium that can suppress the influence of heat generated when the perpendicular magnetic layer is heated on other layers and the substrate. [Means for solving the problem]

[0009] The present invention has the following configuration. (1) A method for manufacturing a magnetic recording medium comprising, in this order, a substrate, an underlayer, and a perpendicular magnetic layer having an L10 structure, a step of, after forming the perpendicular magnetic layer, heating the surface of the perpendicular magnetic layer with LED light emitted from an LED light source to enhance the crystalline orientation of the perpendicular magnetic layer; the underlayer comprises an NaCl-type compound; A method for manufacturing a magnetic recording medium, wherein the LED light has a central wavelength of less than 500 nm. (2) The method for producing a magnetic recording medium according to (1), wherein the LED light source does not include LED light having a central wavelength of 500 nm or more. (3) The LED light has a central wavelength of less than 500 nm, a heating area with a diameter of 90 mm or more, and a light intensity of 1.5 W / cm 2 ~15W / cm 2 The method for producing a magnetic recording medium according to (1) or (2), wherein the uniformity of the light intensity within the heated region is within ±15%. (4) The underlayer is a first underlayer made of a bcc alloy containing Cr as the main component and oriented in a (100) direction; a second underlayer made of a W-based bcc alloy with a (100) orientation; a third underlayer containing MgO as a main component as the NaCl-type compound; are stacked in this order from the substrate side, The method for producing a magnetic recording medium according to any one of (1) to (3), wherein the second underlayer has a thickness of (λ×0.1) nm or more, where the central wavelength is λ nm. (5) A magnetic recording and reproducing device equipped with a magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to any one of (1) to (4). [Effects of the Invention]

[0010] One aspect of the present invention can provide a method for manufacturing a magnetic recording medium that can suppress the influence of heat generated when the perpendicular magnetic layer is heated on other layers and the substrate. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing an example of the configuration of a magnetic recording medium obtained by a method for producing a magnetic recording medium according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an example of a magnetic recording and reproducing device using a magnetic recording medium manufactured by a method for manufacturing a magnetic recording medium according to an embodiment of the present invention. [Figure 3] FIG. 1 is a schematic diagram illustrating an example of a magnetic head. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail. To facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals, and duplicate descriptions will be omitted. The scale of each component in the drawings may differ from the actual scale. In this specification, unless otherwise specified, "to" indicating a range of values means that the values before and after it are included as the lower and upper limits.

[0013] A method for manufacturing a magnetic recording medium according to this embodiment will be described. Before describing a method for manufacturing a magnetic recording medium according to this embodiment, a magnetic recording medium obtained by the method for manufacturing a magnetic recording medium according to this embodiment will be described.

[0014] [Magnetic recording media] 1 is a schematic cross-sectional view showing an example of the configuration of a magnetic recording medium obtained by the method for manufacturing a magnetic recording medium according to this embodiment. As shown in Fig. 1, a magnetic recording medium 10 includes a non-magnetic substrate 11, a soft magnetic layer 12, an underlayer 13, a perpendicular magnetic layer 14, and a protective layer 15, which are stacked in this order from the non-magnetic substrate 11 side.

[0015] In FIG. 1, the protective layer 15 side is referred to as the upper side and the non-magnetic substrate 11 side as the lower side, but this does not represent a universal upper-lower relationship.

[0016] (Non-magnetic substrate) Examples of materials that can be used to form the non-magnetic substrate 11 include Al alloys such as AlMg alloys, soda glass, aluminosilicate glass, amorphous glasses, silicon, titanium, ceramics, sapphire, quartz, resins, etc. Among these, Al alloys and glasses such as crystallized glass and amorphous glass are preferred.

[0017] As the non-magnetic substrate 11, it is preferable to use a heat-resistant glass substrate having a softening temperature of, for example, 500° C. or higher, preferably 600° C. or higher.

[0018] The outer diameter of the non-magnetic substrate 11 is typically 2.5 inches or 3.5 inches.

[0019] (Soft magnetic layer) The soft magnetic layer 12 is provided on the non-magnetic substrate 11 and has the function of guiding the recording magnetic field from the magnetic head and efficiently applying the perpendicular component of the recording magnetic field to the perpendicular magnetic layer 14 when recording a signal on the magnetic recording medium 10.

[0020] Examples of materials that can be used to form the soft magnetic layer 12 include soft magnetic alloys such as FeCo-based alloys, CoZrNb-based alloys, and CoTaZr-based alloys.

[0021] The soft magnetic layer 12 preferably has an amorphous structure, which enhances the soft magnetic properties of the soft magnetic layer 12 and improves the surface smoothness, thereby reducing the flying height of the magnetic head and further improving the recording density of the magnetic recording medium 10.

[0022] The soft magnetic layer 12 may be formed as an antiferromagnetic exchange coupling (AFC) film by depositing multiple layers with a non-magnetic layer such as a Ru film interposed therebetween.

[0023] The total thickness of the soft magnetic layer 12 is determined appropriately depending on the electromagnetic conversion characteristics of the magnetic recording medium 10, but is preferably, for example, 20 nm to 120 nm.

[0024] In this specification, the thickness of the soft magnetic layer 12 refers to the length in the direction perpendicular to the main surface of the soft magnetic layer 12. The thickness of the soft magnetic layer 12 is, for example, the thickness measured at an arbitrary location on the cross section of the soft magnetic layer 12. When measurements are taken at several arbitrary locations on the cross section of the soft magnetic layer 12, the average value of the thicknesses measured at these locations may be used. Hereinafter, the same measurement method as for the thickness of the soft magnetic layer 12 can be used for layers other than the soft magnetic layer 12.

[0025] (base layer) The underlayer 13 contains an NaCl-type compound, preferably MgO, and may have a multilayer structure including other layers as long as the magnetic grains having the L10 structure contained in the perpendicular magnetic layer 14 can be (001) oriented.

[0026] Furthermore, the underlayer 13 more preferably contains a bcc alloy, such as a Cr alloy, a W alloy, or a Mo alloy. These may be used alone or in combination of two or more. Furthermore, layers using these materials may form a multilayer structure.

[0027] The underlayer 13 is preferably configured by laminating a plurality of layers of different types. In this embodiment, as shown in Fig. 1, the underlayer 13 has a first underlayer 13-1, a second underlayer 13-2, and a third underlayer 13-3. The underlayer 13 may also include a layer other than the first underlayer 13-1, the second underlayer 13-2, and the third underlayer 13-3 as a fourth underlayer 13-4, etc.

[0028] The first underlayer 13-1 is preferably made of a (100) oriented bcc alloy containing Cr, specifically Cr, CrV, VCr, CrVTi, VCrTi, CrTa, and VCrTa.

[0029] The second underlayer 13-2 is preferably formed on the first underlayer 13-1 and is made of a (100) oriented bcc alloy whose main component is one of W, Mo, V, and Ta. The layer made of these materials can be a bcc alloy with a lattice constant of 3.06 Å to 3.16 Å.

[0030] It is preferable to use W, Mo, 80at%V-20at%Ta (V content 80at%, Ta content 20at%, hereinafter the same), 90at%Mo-10at%Ta, 90at%W-10at%Ta, VMo, etc. as the second underlayer 13-2.

[0031] The thickness of the second underlayer 13-2 is preferably (λ×0.1) nm to 100 nm, where λ is the center wavelength of the irradiated light having a center wavelength of less than 500 nm. For example, when light having a center wavelength of 400 nm is used, the thickness of the second underlayer 13-2 is more preferably 40 nm to 100 nm. By setting the thickness of the second underlayer 13-2 within the above-mentioned preferred range, the heating effect of the irradiated light is reduced from extending to the non-magnetic substrate 11 side of the second underlayer 13-2, interdiffusion between the first underlayer 13-1 and the second underlayer 13-2 is prevented, and expansion and contraction of the atomic lattice of the second underlayer 13-2 can be reduced. This allows tensile stress to be applied to the third underlayer 13-3 and the perpendicular magnetic layer 14, and the perpendicular magnetic layer 14 can be stably oriented in the (001) plane. Furthermore, the heating effect of the irradiated light on the soft magnetic layer 12 and the non-magnetic substrate 11 is reduced, so that crystallization of the alloy constituting the soft magnetic layer 12 and relaxation of the strain in the non-magnetic substrate 11 can be prevented.

[0032] The third underlayer 13-3 is stacked on the second underlayer 13-2 and preferably contains MgO as a NaCl-type compound as a main component, which allows the magnetic grains having the L10 structure contained in the perpendicular magnetic layer 14 to be (001) oriented.

[0033] (perpendicular magnetic layer) The perpendicular magnetic layer 14 includes magnetic grains having an L10 structure. Examples of magnetic grains having an L10 structure include FePt-based alloy grains including FePt-based alloys and CoPt-based alloy grains including CoPt-based alloys.

[0034] The particle size of the magnetic particles is preferably 3 nm to 10 nm, more preferably 4 nm to 7 nm. The particle size of the magnetic particles can be measured by a general measurement method such as observing a plane surface with a TEM.

[0035] The distance between magnetic particles is preferably 4 nm to 12 nm, more preferably 5 nm to 9 nm. The distance between magnetic particles refers to the distance between the centers of gravity of adjacent magnetic particles. The distance between magnetic particles can be measured by a general measurement method, for example, by observing a plane with a TEM.

[0036] The perpendicular magnetic layer 14 may have a granular structure including grain boundaries.

[0037] When the perpendicular magnetic layer 14 has a granular structure, the content of the grain boundary parts in the perpendicular magnetic layer 14 is preferably 25 to 50 volume %, more preferably 35 to 45 volume %. If the content of the grain boundary parts in the perpendicular magnetic layer 14 is within the above-mentioned preferred range, the anisotropy of the magnetic grains contained in the perpendicular magnetic layer 14 can be increased.

[0038] Here, the grain boundary portion may contain carbides, nitrides, oxides, borides, etc. Specific examples include BN, B4C, C, MoO3, and GeO2.

[0039] The magnetic particles are preferably c-axis oriented, that is, (001) oriented, relative to the surface of the non-magnetic substrate 11 .

[0040] The thickness of the perpendicular magnetic layer 14 is preferably 8 nm to 20 nm, more preferably 10 nm to 18 nm, and even more preferably 10 nm to 15 nm. If the thickness of the perpendicular magnetic layer 14 is within the above preferred range, high recording density can be achieved.

[0041] The perpendicular magnetic layer 14 can be formed on the underlayer 13 by sputtering or the like.

[0042] The perpendicular magnetic layer 14 may include one magnetic layer or multiple stacked magnetic layers. When the perpendicular magnetic layer 14 includes multiple magnetic layers, the magnetic layers may be formed using the same type of material or different types of materials. A non-magnetic layer may be included between the magnetic layers. The non-magnetic layer may be formed using a material commonly used in magnetic recording media.

[0043] (protective layer) The protective layer 15 has the function of protecting the magnetic recording medium 10 from damage caused by contact between the magnetic head and the magnetic recording medium 10 .

[0044] The protective layer 15 may be made of a carbon material such as diamond-like carbon (DLC).

[0045] The thickness of the protective layer 15 is preferably 1 nm to 10 nm, and more preferably 2 nm to 6 nm.

[0046] In this embodiment, the magnetic recording medium 10 may include a lubricant layer (not shown) on the protective layer 15. The lubricant layer may be formed from a material such as a resin such as perfluoropolyether. The thickness of the lubricant layer is not particularly limited and may be any appropriate thickness, for example, about 1.5 nm.

[0047] In this embodiment, the magnetic recording medium 10 may include a Ti-based underlayer containing Cr and Ti between the non-magnetic substrate 11 and the soft magnetic layer 12. The thickness of the Ti-based underlayer is not particularly limited and may be any appropriate thickness.

[0048] In this embodiment, the magnetic recording medium 10 may include a Ta-based underlayer containing Ta between the soft magnetic layer 12 and the underlayer 13. The Ta-based underlayer may be composed of Ta alone. The thickness of the Ta-based underlayer is not particularly limited and may be any appropriate thickness.

[0049] [Magnetic recording medium manufacturing method] The method for manufacturing the magnetic recording medium according to this embodiment includes the steps of forming the soft magnetic layer 12, the underlayer 13, the perpendicular magnetic layer 14, and the protective layer 15, and may also include other steps such as the step of forming a lubricant layer.

[0050] In the method for manufacturing a magnetic recording medium according to this embodiment, first, the soft magnetic layer 12 is formed on the prepared non-magnetic substrate 11 (soft magnetic layer forming step).

[0051] The soft magnetic layer 12 can be formed by a general film formation method such as sputtering.

[0052] In the sputtering method, a target containing the material for forming the soft magnetic layer 12 can be used.

[0053] As a target containing a material for forming the soft magnetic layer 12, for example, a soft magnetic alloy such as an FeCo-based alloy, a CoZrNb-based alloy, or a CoTaZr-based alloy can be used.

[0054] As the sputtering method, DC sputtering, DC magnetron sputtering, RF sputtering, or the like can be used.

[0055] When forming the soft magnetic layer 12, an RF (Radio Frequency) bias, a DC bias, a pulse DC, a pulse DC bias, or the like may be used as needed.

[0056] As the reactive gas, O2 gas, H2O gas, N2 gas, or the like may be used.

[0057] The sputtering gas pressure is adjusted appropriately to optimize the properties of each layer, but is usually within the range of about 0.1 Pa to 30 Pa.

[0058] Next, the underlayer 13 is formed on the soft magnetic layer 12 (underlayer forming step).

[0059] The step of forming the underlayer may include a step of forming a first underlayer, a step of forming a second underlayer, and a step of forming a third underlayer.

[0060] As a method for forming the first underlayer 13-1, similar to the method for forming the soft magnetic layer 12, the first underlayer 13-1 can be formed by sputtering using a target containing the material for forming the first underlayer 13-1.

[0061] No. The material for forming the first underlayer 13-1 may be a Cr alloy in which a bcc alloy containing Cr as the main component is oriented in the (100) direction. As a target containing a material for forming the first underlayer 13-1, a Cr alloy containing Cr as a main component can be used.

[0062] The sputtering conditions other than those for the material forming the underlayer 13 can be the same as those for the soft magnetic layer 12 .

[0063] As a method for forming the second underlayer 13-2, similar to the method for forming the soft magnetic layer 12, the second underlayer 13-2 can be formed by sputtering using a target containing a material for forming the second underlayer 13-2.

[0064] No. The material for forming the second underlayer 13-2 may be a W alloy in which a bcc alloy containing W as the main component is oriented in the (100) direction. As a target containing a material for forming the second underlayer 13-2, a W alloy containing W as a main component or the like can be used.

[0065] The sputtering conditions other than those for the material forming the second underlayer 13-2 can be the same as those for the soft magnetic layer 12.

[0066] As a method for forming the third underlayer 13-3, similar to the method for forming the soft magnetic layer 12, the third underlayer 13-3 can be formed by sputtering using a target containing a material for forming the third underlayer 13-3.

[0067] No. The material for forming the underlayer 13-3 may be a NaCl-type compound, etc. Examples of the NaCl-type compound include MgO. As a target containing a material for forming the third underlayer 13-3, an NaCl-type compound or the like can be used.

[0068] The sputtering conditions for the materials other than those for forming the third underlayer 13-3 can be the same as those for the soft magnetic layer 12.

[0069] Next, the perpendicular magnetic layer 14 is formed on the underlayer 13 (perpendicular magnetic layer forming step).

[0070] The perpendicular magnetic layer 14 can be formed by sputtering using a target containing the material for forming the perpendicular magnetic layer 14, similar to the method for forming the soft magnetic layer 12.

[0071] A target containing an alloy having an L10 structure can be used as the target containing the material for forming the perpendicular magnetic layer 14. As the alloy having the L10 structure, an alloy containing Fe or Co and Pt or the like can be used, such as an FePt-based alloy or a CoPt-based alloy.

[0072] The sputtering conditions for the material other than that for forming the perpendicular magnetic layer 14 can be the same as those for the soft magnetic layer 12 .

[0073] Next, with the perpendicular magnetic layer 14 stacked on the non-magnetic substrate 11, the soft magnetic layer 12, and the underlayer 13, the surface of the perpendicular magnetic layer 14 is heated by LED light emitted from an LED light source to enhance the crystalline orientation of the perpendicular magnetic layer 14 (heating process).

[0074] The LED light source has a central wavelength of less than 500 nm, a heating area with a diameter of 90 mm or more, and a light intensity of 1.5 W / cm 2 ~15W / cm 2 It is preferable to irradiate the LED light with a uniformity of light intensity within ±15% within the heated region, so that the LED light source can efficiently heat only the perpendicular magnetic layer 14 with the LED light.

[0075] Here, the uniformity of the light intensity within the heated region is measured at the heating position by the LED light source, i.e., at a location corresponding to the heated surface of the perpendicular magnetic layer 14. The measurement can be performed using a known method, for example, by placing a light intensity meter at the position of the non-magnetic substrate 11 to measure the light intensity distribution within the substrate surface and calculating the fluctuation range relative to the average value of the light intensity distribution.

[0076] It is also preferable to use an LED light source that does not include light with a central wavelength of 500 nm or more.

[0077] As mentioned above, it is known that heat treatment at a high temperature of 400°C or higher is generally required to order an FePt alloy with an L10 ordered structure. Conventionally, this heat treatment has been performed using electromagnetic waves, such as halogen lamps, lasers, radio frequency waves, and microwaves. However, when using a halogen lamp, the irradiation wavelength of the halogen lamp is broad, approximately 500 nm to 3.5 μm, and the entire area from the nonmagnetic substrate 11 to the perpendicular magnetic layer 14 is heated. When using a laser, it is possible to heat only a specific material by oscillating the laser at a specific wavelength, but the laser's irradiation area is small, making it difficult to uniformly heat the entire surface of the perpendicular magnetic layer 14. When using electromagnetic waves, the heating efficiency of the electromagnetic waves depends on the dielectric constant of the heated object, so electromagnetic waves are not suitable for heating only the perpendicular magnetic layer 14.

[0078] In this embodiment, the perpendicular magnetic layer 14 can be efficiently heated by using LED light emitted from an LED light source to heat the perpendicular magnetic layer 14. That is, Fe, Pt, and Co contained in the perpendicular magnetic layer 14 have optical absorption peaks on the short wavelength side of less than 500 nm. The LED light emitted from the LED light source of this embodiment heats a wide area and has high uniformity of light intensity within the heated area, so the entire area of the perpendicular magnetic layer 14 can be heated approximately uniformly.

[0079] Furthermore, the NaCl-type compound contained in the third underlayer 13-3 has a light absorption peak at 500 nm or more, making it difficult for the temperature to rise when heated by LED light, and thus has a heat insulating effect, which makes it possible to suppress temperature rise in the nonmagnetic substrate 11, soft magnetic layer 12, and underlayer 13 during the heating process of the perpendicular magnetic layer 14.

[0080] The penetration depth of light is determined by its wavelength, and is thought to be approximately 0.1λnm (λ is the central wavelength of the irradiated light (unit: nm)). Therefore, light emitted from a conventional halogen lamp penetrates deep into layers to heat them. In contrast, LED light emitted from an LED light source does not penetrate deep into layers from the irradiated surface, resulting in a reduced heating effect. Therefore, by setting the thickness of the second underlayer 13-2 to 0.1λnm to 100nm, it is possible to further suppress the temperature rise of layers below the second underlayer 13-2. Furthermore, by increasing the thickness of the second underlayer 13-2, it is possible to increase the tensile stress applied to the third underlayer 13-3, which is an NaCl-type compound layer.

[0081] Furthermore, since the outer diameter of the non-magnetic substrate 11 is typically 2.5 inches or 3.5 inches, by making the diameter of the area heated by the LED light source 90 mm or more, the entire non-magnetic substrate 11 can be heated uniformly.

[0082] The Cr contained in the first underlayer 13-1 is a thermally diffusible element, and the insulating effect between the second underlayer 13-2 and the third underlayer 13-3, which is a layer containing an NaCl-type compound, suppresses thermal diffusion at the interface between the first underlayer 13-1 and the second underlayer 13-2. This suppresses the diffusion of Cr atoms into the second underlayer 13-2, such as a W alloy layer, and suppresses the W atoms from substituting for Cr atoms, thereby suppressing lattice contraction of the second underlayer 13-2. This reduces the tensile stress applied to the third underlayer 13-3, which contains MgO as its main component, and suppresses the inhibition of ordering of the FePt-based alloy contained in the perpendicular magnetic layer 14.

[0083] Furthermore, the heat insulating effect of the second underlayer 13-2 and the third underlayer 13-3 can prevent the soft magnetic layer 12 located below the first underlayer 13-1 from being heated, thereby preventing the soft magnetic layer 12 from being crystallized.

[0084] Furthermore, since the second underlayer 13-2 has a heat insulating effect, there is no need to increase the thickness of the third underlayer 13-3, which is a layer containing an NaCl-type compound, and therefore the decrease in tensile stress that accompanies the thickening of the third underlayer 13-3 can be reduced.

[0085] Furthermore, the heat insulating effect of the second underlayer 13-2 and the third underlayer 13-3 prevents heating of the non-magnetic substrate 11 located below the first underlayer 13-1, thereby reducing the occurrence of waviness due to strain relaxation and crystal coarsening.

[0086] Next, the protective layer 15 is formed on the perpendicular magnetic layer 14 (step of forming the protective layer 15).

[0087] The method for forming the protective layer 15 is not particularly limited, but may be any of the following general film-forming methods: RF-CVD (Radio Frequency-Chemical Vapor Deposition), which forms a film by decomposing a raw material gas consisting of hydrocarbons using high-frequency plasma; IBD (Ion Beam Deposition), which forms a film by ionizing a raw material gas using electrons emitted from a filament; and FCVA (Filtered Cathodic Vacuum Arc), which forms a film using a solid carbon target without using a raw material gas.

[0088] Furthermore, a lubricant layer 16 may be formed on the surface of the protective layer 15 by using a general coating method or the like (lubricant layer forming step).

[0089] As described above, by forming the protective layer 15 on the perpendicular magnetic layer 14, the magnetic recording medium 10 shown in FIG. 1 is obtained.

[0090] As described above, the method for manufacturing a magnetic recording medium according to this embodiment includes a step of forming a perpendicular magnetic layer and a step of heating the perpendicular magnetic layer. In the step of heating the perpendicular magnetic layer, the surface of the perpendicular magnetic layer 14 is heated by LED light emitted from an LED light source. The LED light source irradiates LED light with a central wavelength of less than 500 nm. As a result, the method for manufacturing a magnetic recording medium according to this embodiment can heat only the perpendicular magnetic layer 14 substantially uniformly across its entire area by the LED light emitted from the LED light source, and can prevent the LED light from reaching and heating the non-magnetic substrate 11, soft magnetic layer 12, and underlayer 13, which are located below the perpendicular magnetic layer 14. Therefore, the method for manufacturing a magnetic recording medium according to this embodiment can efficiently heat only the perpendicular magnetic layer 14 while preventing the heating from affecting the non-magnetic substrate 11, soft magnetic layer 12, and underlayer 13, which are located below the perpendicular magnetic layer 14.

[0091] The method for manufacturing a magnetic recording medium according to this embodiment can further increase the heating temperature of the perpendicular magnetic layer 14 by using LED light, thereby further improving the crystal orientation of the perpendicular magnetic layer 14. Furthermore, the method for manufacturing a magnetic recording medium according to this embodiment can prevent elements constituting the underlayer 13 from diffusing into the soft magnetic layer 12 due to the heat generated when the perpendicular magnetic layer 14 is heated, thereby preventing the amorphous structure of the soft magnetic layer 12 from being disturbed and the soft magnetic properties of the soft magnetic layer 12 from being impaired. Furthermore, the method for manufacturing a magnetic recording medium according to this embodiment can reduce the occurrence of waviness in the non-magnetic substrate 11 due to the heat generated when the perpendicular magnetic layer 14 is heated. Therefore, the method for manufacturing a magnetic recording medium according to this embodiment can manufacture a magnetic recording medium 10 with less waviness on the surface thereof and excellent electromagnetic conversion properties.

[0092] In the method for manufacturing a magnetic recording medium according to this embodiment, the LED light source can be configured not to include LED light with a central wavelength of 500 nm or more. Because the third underlayer 13-3 has a light absorption peak at 500 nm or more, it is less likely to be heated by the LED light and has a heat-insulating effect. Therefore, in the method for manufacturing a magnetic recording medium according to this embodiment, the temperature of the non-magnetic substrate 11, soft magnetic layer 12, and underlayer 13, which are located below the perpendicular magnetic layer 14, can be prevented from rising during the heating step of the perpendicular magnetic layer 14, thereby more reliably minimizing the effects of heating on these components.

[0093] In the method for manufacturing a magnetic recording medium according to this embodiment, the LED light to be irradiated has a central wavelength of less than 500 nm, the heated area has a diameter of 90 mm or more, and the light intensity is 1.5 W / cm 2 ~15W / cm 2 and LED light can be used in which the uniformity of the light intensity within the heated region is within ±15%. As a result, the method for manufacturing a magnetic recording medium according to this embodiment can more uniformly heat only the perpendicular magnetic layer 14 across its entire region with LED light, and can more effectively prevent the LED light from reaching and heating the non-magnetic substrate 11, soft magnetic layer 12, and underlayer 13, which are located below the perpendicular magnetic layer 14. Therefore, the method for manufacturing a magnetic recording medium according to this embodiment can more efficiently heat only the perpendicular magnetic layer 14, and can more effectively prevent the influence of heating from affecting the non-magnetic substrate 11, soft magnetic layer 12, and underlayer 13, which are located below the perpendicular magnetic layer 14.

[0094] In the method for manufacturing a magnetic recording medium according to this embodiment, the underlayer 13 includes a first underlayer 13-1, a second underlayer 13-2, and a third underlayer 13-3 stacked in this order from the non-magnetic substrate 11 side. The thickness of the second underlayer 13-2 can be set to (λ×0.1) nm or more, where λ is the center wavelength. This allows the method for manufacturing a magnetic recording medium according to this embodiment to more reliably suppress the temperature rise caused by LED light in the non-magnetic substrate 11 and the soft magnetic layer 12 located below the second underlayer 13-2, and to increase the tensile stress of the third underlayer 13-3. Therefore, the method for manufacturing a magnetic recording medium according to this embodiment can more reliably suppress the influence of heating caused by LED light on the non-magnetic substrate 11 and the soft magnetic layer 12 located below the second underlayer 13-2, thereby improving the electromagnetic conversion characteristics of the magnetic recording medium 10.

[0095] [Magnetic recording and playback device] A magnetic recording and reproducing device using a magnetic recording medium manufactured using the manufacturing method for a magnetic recording medium according to this embodiment will be described. The magnetic recording and reproducing device according to this embodiment is not particularly limited in form as long as it has a magnetic recording medium manufactured using the manufacturing method for a magnetic recording medium according to this embodiment. Note that this description will be made for a case in which the magnetic recording and reproducing device records magnetic information on the magnetic recording medium using a thermally assisted recording method.

[0096] Fig. 2 is a perspective view showing an example of a magnetic recording and reproducing device using a magnetic recording medium manufactured using the method for manufacturing a magnetic recording medium according to this embodiment. As shown in Fig. 2, the magnetic recording and reproducing device 100 can include a magnetic recording medium 101, a magnetic recording medium drive unit 102 for rotating the magnetic recording medium 101, a magnetic head 103 equipped with a near-field light generating element at its tip, a magnetic head drive unit 104 for moving the magnetic head 103, and a recording and reproducing signal processing unit 105. The magnetic recording medium 101 used is the magnetic recording medium 10 manufactured using the method for manufacturing a magnetic recording medium according to this embodiment described above.

[0097] 3 is a schematic diagram showing an example of the magnetic head 103. As shown in FIG.

[0098] The recording head 110 has a main magnetic pole 111, an auxiliary magnetic pole 112, a coil 113 that generates a magnetic field, a laser diode (LD) 114 that is a laser light generating unit that heats the magnetic recording medium 101, and a waveguide 116 that transmits the laser L generated from the LD 114 to a near-field light generating element 115.

[0099] The read head 120 has a shield 121 and a read element 122 sandwiched between the shields 121 .

[0100] As shown in Figure 3, in the magnetic recording and reproducing device 100, the center of the magnetic recording medium 101 is attached to the rotating shaft of a spindle motor, and the magnetic head 103 writes or reads information to or from the magnetic recording medium 101 while floating and running above the surface of the magnetic recording medium 101, which is rotated by the spindle motor.

[0101] The magnetic recording and reproducing device 100 of this embodiment uses a magnetic recording medium 101 manufactured using the magnetic recording medium manufacturing method of this embodiment, which allows the magnetic recording medium 101 to have excellent electromagnetic conversion characteristics, and therefore can have a stable high recording density. [Example]

[0102] Hereinafter, the embodiments will be specifically described with reference to examples and comparative examples, but the embodiments are not limited to these examples and comparative examples.

[0103] Example 1 [Magnetic recording media manufacturing] A magnetic recording medium was produced by the following method.

[0104] First, a 50 nm thick Ti-based underlayer consisting of 50 at% Cr-50 at% Ti (Cr content 50 at%, Ti content 50 at%) was formed on a glass substrate with an outer diameter of 2.5 inches, and then a 150 nm thick 40 at% Co-46 at% Fe-14 at% B soft magnetic layer was formed. The glass substrate was then heated to 320°C using a halogen lamp, and a 10 nm thick Ta underlayer, a 10 nm thick first underlayer consisting of 42.5 at% Cr-50 at% V-7.5 at% Ti, a 60 nm thick second underlayer consisting of W, a 3 nm thick third underlayer consisting of MgO, and a 10 nm thick perpendicular magnetic layer consisting of 82 mol% (50 at% Fe-50 at% Pt)-10 mol% SiO2-8 mol% BN (Fe content 50 at%, Pt content 50 at% FePt alloy content 82 mol%, SiO2 content 10 mol%, BN content 8 mol%) were deposited.

[0105] The surface of the perpendicular magnetic layer was then heated by irradiating it with LED light from an LED light source. The LED light source had a central wavelength of 395 nm (excluding light with a central wavelength of 500 nm or more), an irradiation area (area to be heated) with a diameter of 100 mm (effective area), and a light intensity of 11 W / cm within the effective area. 2 The uniformity of the light intensity on the substrate surface within the effective region was within ±7%, the heating time was 10 seconds, and the surface temperature of the perpendicular magnetic layer was set to a maximum of 550°C.

[0106] Next, a 4 nm thick protective layer made of diamond-like carbon (DLC) was formed on the perpendicular magnetic layer, and then a 1.5 nm thick liquid lubricant layer made of perfluoropolyether was formed by coating.

[0107] The magnetic recording medium was manufactured by the above process. The film thickness of the third underlayer and the heating conditions of the perpendicular magnetic layer (heating means, center wavelength, wavelength range, light intensity, light intensity uniformity (light intensity uniformity), and presence or absence of light with a center wavelength of 500 nm or more) are shown in Tables 1 and 2.

[0108] [Characteristics evaluation of magnetic recording media] As the characteristics of the magnetic recording medium, the orientation of the perpendicular magnetic layer and the SNR, which is the electromagnetic conversion characteristic, were measured and evaluated.

[0109] (Measurement of the orientation of the perpendicular magnetic layer) The (001) intensity of the FePt alloy constituting the perpendicular magnetic layer was measured using an X-ray diffraction apparatus, and the (001) orientation of the perpendicular magnetic layer was evaluated. The measurement results of the (001) intensity of the FePt alloy are shown in Tables 1 and 2.

[0110] (Measurement of electromagnetic conversion characteristics) The signal-to-noise ratio (SNR) was measured using a spin stand tester with a magnetic head equipped with a laser spot heating mechanism. The current input to the laser diode was adjusted so that the recording track width (MWW), defined as the half-width of the playback signal waveform, was 70 nm, and the SNR was confirmed. The SNR measurement results are shown in Tables 1 and 2.

[0111] <Examples 2 to 14> In Example 1, the film thickness of the second underlayer and the heating conditions of the perpendicular magnetic layer (heating means, central wavelength, wavelength range, light intensity, light intensity uniformity, and presence or absence of light with a central wavelength of 500 nm or more) were changed to the conditions shown in Tables 1 and 2, but the manufacturing process was the same as in Example 1.

[0112] <Comparative Examples 1 to 7> The same procedures as in Example 1 were carried out except that the film thickness of the second underlayer and the heating conditions of the perpendicular magnetic layer (heating means, central wavelength, wavelength range, light intensity, light intensity uniformity, and presence or absence of light with a central wavelength of 500 nm or more) were changed to the conditions shown in Tables 1 and 2. In Comparative Examples 3, 5, and 6, a halogen lamp was used to heat the perpendicular magnetic layer, the heating time was 10 seconds, and the surface temperature of the perpendicular magnetic layer was up to 550°C. The halogen lamp used had a central wavelength of 1000 nm and a wavelength range of 350 nm to 3500 nm. In Comparative Example 4, high frequency radiation was used. The heating time was 10 seconds, and the surface temperature of the perpendicular magnetic layer was up to 550°C. The high frequency radiation had an oscillation frequency of 13.56 MHz and a maximum output of 1 kW.

[0113] [Table 1]

[0114] [Table 2]

[0115] As can be seen from Tables 1 and 2, the (001) intensity of the FePt alloy constituting the perpendicular magnetic layer was 205.4 or more, and the SNR of the magnetic recording medium was 2.68 dB or more in Examples 1 to 14. On the other hand, in Comparative Examples 1 to 7, the (001) orientation of the perpendicular magnetic layer was 205.9 or less, and the SNR of the magnetic recording medium was 2.65 dB or less.

[0116] The manufacturing methods of the magnetic recording media of Examples 1 to 14 differ from the manufacturing methods of the magnetic recording media of Comparative Examples 1 to 7 in that a perpendicular magnetic layer is formed on a third underlayer made of MgO, and then LED light from an LED light source is irradiated onto the surface of the perpendicular magnetic layer under predetermined irradiation conditions to heat the surface of the perpendicular magnetic layer with the LED light. The manufacturing methods of the magnetic recording media of Examples 1 to 14 irradiated LED light from the LED light source with LED light having a center wavelength of 395 nm or less. This confirmed that the manufacturing methods of the magnetic recording media of Examples 1 to 14 could manufacture magnetic recording media while minimizing the influence of heat generated during heating on the glass substrate, Ti-based underlayer, soft magnetic layer, first underlayer, second underlayer, and third underlayer located below the perpendicular magnetic layer. Therefore, it can be said that the magnetic recording media of this embodiment can be effectively used in magnetic recording and reproducing devices.

[0117] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims.

[0118] This application claims priority based on Japanese Patent Application No. 2022-070962, filed with the Japan Patent Office on April 22, 2022, and incorporates by reference all of the contents of said application. [Explanation of symbols]

[0119] 10, 101 Magnetic recording media 11 Non-magnetic substrate 12 Soft magnetic layer 13 Base layer 13-1 1st base layer 13-2 Second base layer 13-3 3rd base layer 14 Perpendicular magnetic layer 15 Protective layer 100 Magnetic recording and reproducing device 102 Magnetic recording medium drive unit 103 Magnetic Head 104 Magnetic head drive unit 105 Recording / playback signal processing section

Claims

1. Substrate, underlayer, and L1 ０ A method for manufacturing a magnetic recording medium having a perpendicular magnetic layer having a structure in this order, comprising: a step of, after forming the perpendicular magnetic layer, heating the surface of the perpendicular magnetic layer with LED light emitted from an LED light source to enhance the crystalline orientation of the perpendicular magnetic layer; the underlayer comprises an NaCl-type compound; The method for manufacturing a magnetic recording medium, wherein the LED light has a central wavelength of less than 500 nm.

2. 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein the LED light source does not include LED light having a central wavelength of 500 nm or more.

3. The LED light has a diameter of 90 mm or more and a light intensity of 1.5 W / cm ２ ~15 W / cm ２ 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein the uniformity of the light intensity within the heated region is within ±15%.

4. The underlayer is a first underlayer made of a bcc alloy containing Cr as a main component and oriented in the (100) direction; a second underlayer made of a W-based bcc alloy with a (100) orientation; a third underlayer containing MgO as a main component as the NaCl-type compound; are stacked in this order from the substrate side, 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein the thickness of the second underlayer is (.lambda..times.0.1) nm or more, where .lambda. nm is the center wavelength.

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