Method for manufacturing magnetic recording medium and magnetic recording / reproducing device

Abstract

The method for manufacturing a magnetic recording medium according to the present invention is a method for manufacturing a magnetic recording medium provided with a substrate, an underlayer, and a perpendicular magnetic layer having an L10 structure in this order, the method comprising: after the perpendicular magnetic layer is formed, heating the surface of the perpendicular magnetic layer by means of LED light emitted from an LED light source; and a step for improving the crystal orientation of the perpendicular magnetic layer, in which the base layer contains a NaCl-type compound, and the center wavelength of the LED light is 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 Art

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

[0003] CoCr alloys have been used for perpendicular magnetic layers. For example, FePt alloys having an L10 regular structure are known as materials having a higher perpendicular magnetic anisotropy than CoCr alloys. It is also known that the L10 regularization of FePt alloys requires heat treatment at a high temperature of 400°C or higher (for example, see Patent Document 1).

[0004] As a magnetic recording medium using a perpendicular magnetic layer comprising an FePt alloy, for example, a magnetic recording medium using a heat-assisted magnetic recording method is disclosed, which comprises, in sequence, an orientation-controlled base layer formed using an alloy with a BCC structure having Cr as a main component, a (100)-oriented crystalline base layer containing W, a barrier layer comprising MgO having a NaCl-type structure, and a magnetic layer comprising an FePt alloy having an L10 structure (for example, refer to Patent Document 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-40121

[0008] Patent Document 2: Japanese Patent Application Publication No. 2015-88197 Summary of the invention

[0009] Problems to be solved by the invention

[0010] As the application range of magnetic recording and reproducing devices expands, the recording density of magnetic recording media is required to be further improved. As a method of improving the recording density of magnetic recording media, there is a method of increasing the heating temperature when forming the magnetic layer to improve the crystal orientation of the perpendicular magnetic layer.

[0011] However, if the heating temperature of the perpendicular magnetic layer is increased, there are problems such as heating effect on the base layer, soft magnetic layer and non-magnetic substrate and subsequent problems. That is, the elements constituting the base layer diffuse to other layers, damaging the functions of other layers. The alloy constituting the soft magnetic layer crystallizes and the soft magnetic properties are damaged. The strain in the non-magnetic substrate is relaxed, the crystals contained in the non-magnetic substrate are coarsened, and the surface of the magnetic recording medium is undulated.

[0012] An object of one embodiment of the present invention is to provide a method for manufacturing a magnetic recording medium capable of suppressing the influence of heat generated during heating of a perpendicular magnetic layer on other layers and a substrate.

[0013] Methods for solving problems

[0014] The present invention has the following configurations.

[0015] (1) A method for manufacturing a magnetic recording medium, comprising:

[0016] After the vertical magnetic layer is formed, a process is performed to heat the surface of the vertical magnetic layer by LED light emitted from an LED light source to improve the crystal orientation of the vertical magnetic layer.

[0017] The above-mentioned base layer comprises a NaCl type compound,

[0018] The central wavelength of the LED light is less than 500 nm.

[0019] (2) In the method for producing a magnetic recording medium according to (1), the LED light source does not contain LED light having a central wavelength of 500 nm or more.

[0020] (3) The method for manufacturing a magnetic recording medium according to (1) or (2), wherein the central wavelength of the LED light is less than 500 nm, the diameter of the heated area is greater than 90 mm, and the light intensity is 1.5 W / cm 2 ~15W / cm 2 , the uniformity of the light intensity in the heating area is within ±15%.

[0021] (4) The method for producing a magnetic recording medium according to any one of (1) to (3), wherein the base layer is laminated in order from the substrate side and comprises:

[0022] The first underlayer is a bcc alloy with Cr as the main component and oriented in the (100) direction.

[0023] a second underlayer composed of a bcc alloy having W as a main component and oriented in a (100) direction; and

[0024] The third underlayer includes MgO, which is the NaCl type compound, as a main component.

[0025] The film thickness of the second underlayer is not less than (λ×0.1) nm when the central wavelength is λ nm.

[0026] (5) A magnetic recording and reproducing device comprising: a magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to any one of (1) to (4).

[0027] Effects of the Invention

[0028] One aspect of the present invention can provide a method for manufacturing a magnetic recording medium that can suppress the influence of heat generated during heating of a perpendicular magnetic layer on other layers and a substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic cross-sectional view showing an example of the structure of a magnetic recording medium obtained by the method for producing a magnetic recording medium according to an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram 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 an embodiment of the present invention.

[0031] Figure 3 It is a schematic diagram showing an example of a magnetic head. DETAILED DESCRIPTION

[0032] The following is a detailed description of the embodiments of the present invention. In addition, in order to facilitate the understanding of the description, the same symbols are attached to the same components in each drawing, and repeated descriptions are omitted. In addition, the scales of the components in the drawings are sometimes different from the actual ones. In this specification, "to" indicating a numerical range means that the numerical values ​​recorded before and after it are included as the lower limit and upper limit unless otherwise specified.

[0033] A method for producing a magnetic recording medium according to the present embodiment will be described. When describing a method for producing a magnetic recording medium according to the present embodiment, a magnetic recording medium obtained by the method for producing a magnetic recording medium according to the present embodiment will be described.

[0034] [Magnetic recording media]

[0035] Figure 1 It is a schematic cross-sectional view showing an example of the structure of a magnetic recording medium obtained by the method for manufacturing a magnetic recording medium according to the present embodiment. Figure 1As shown, the 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.

[0036] in addition, Figure 1 In the figure, the protective layer 15 side is referred to as the upper side and the non-magnetic substrate 11 side is referred to as the lower side, which does not represent a general upper and lower relationship.

[0037] (Non-magnetic substrate)

[0038] Examples of materials constituting the nonmagnetic substrate 11 include Al alloys such as AlMg alloys, soda glass, aluminosilicate glass, amorphous glass, silicon, titanium, ceramics, sapphire, quartz, and resins. Among these, Al alloys, crystallized glass, amorphous glass, and other glasses are preferred.

[0039] As the non-magnetic substrate 11 , for example, a heat-resistant glass substrate having a softening temperature of 500° C. or higher, preferably 600° C. or higher is preferably used.

[0040] The outer diameter of the nonmagnetic substrate 11 is usually 2.5 inches or 3.5 inches.

[0041] (Soft magnetic layer)

[0042] The soft magnetic layer 12 is provided on the nonmagnetic 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 signals on the magnetic recording medium 10 .

[0043] Examples of the material constituting the soft magnetic layer 12 include soft magnetic alloys such as FeCo alloys, CoZrNb alloys, and CoTaZr alloys.

[0044] The soft magnetic layer 12 preferably has an amorphous structure. This can improve the soft magnetic properties of the soft magnetic layer 12 and improve surface smoothness, thereby reducing the flying height of the magnetic head and further improving the recording density of the magnetic recording medium 10 .

[0045] Alternatively, the soft magnetic layer 12 may be formed as a multilayer film with non-magnetic layers such as Ru films interposed therebetween to form an antiferromagnetic exchange coupling (AFC) film.

[0046] The total thickness of the soft magnetic layer 12 is appropriately determined according to the electromagnetic conversion characteristics of the magnetic recording medium 10 , and is preferably 20 nm to 120 nm, for example.

[0047] In addition, 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 when measuring an arbitrary location on the cross section of the soft magnetic layer 12. When measuring a plurality of locations at an arbitrary location on the cross section of the soft magnetic layer 12, the average value of the thickness of these measurement locations can be used. Hereinafter, the thickness of other layers other than the soft magnetic layer 12 can also be measured using the same measurement method as the thickness of the soft magnetic layer 12.

[0048] (basal layer)

[0049] The base layer 13 contains a NaCl type compound, preferably MgO as the NaCl type compound. If the magnetic grains having the L10 structure contained in the perpendicular magnetic layer 14 can be oriented (001), a multilayer structure containing other layers may be formed.

[0050] In addition, the base layer 13 more preferably includes a bcc alloy, for example, a Cr alloy, a W alloy, a Mo alloy, etc. These can be used alone or in combination of two or more. In addition, the layer using these materials can be made into a multilayer structure.

[0051] The base layer 13 is preferably formed by stacking a plurality of layers of different types. Figure 1 As shown, the base layer 13 includes a first base layer 13-1, a second base layer 13-2, and a third base layer 13-3. In addition, the base layer 13 may include a layer other than the first base layer 13-1, the second base layer 13-2, and the third base layer 13-3 as a fourth base layer 13-4. . . .

[0052] The first underlayer 13-1 is preferably formed of a layer of a bcc alloy containing Cr in a (100) orientation. Specific examples thereof include Cr, CrV, VCr, CrVTi, VCrTi, CrTa, and VCrTa.

[0053] The second base layer 13-2 is preferably stacked on the first base layer 13-1 and is formed of a (100) oriented bcc alloy having any one of W, Mo, V, and Ta as a main component. The layer formed of these materials can use a lattice constant of bcc alloy.

[0054] As the second base layer 13-2, it is preferred to use W, Mo, 80at% V-20at% Ta (V content 80at%, Ta content 20at%, the same expression below), 90at% Mo-10at% Ta, 90at% W-10at% Ta, VMo, etc.

[0055] The thickness of the second base layer 13-2 is preferably (λ×0.1) nm to 100 nm when the central wavelength of the irradiated light having a central wavelength of less than 500 nm is set to λ nm. For example, when light having a central wavelength of 400 nm is used, the thickness of the second base layer 13-2 is more preferably 40 nm to 100 nm. By setting the thickness of the second base layer 13-2 within the above preferred range, the heating effect caused by the irradiated light is reduced to the non-magnetic substrate 11 side relative to the second base layer 13-2, and the mutual diffusion between the first base layer 13-1 and the second base layer 13-2 can be prevented, and the expansion and contraction of the atomic lattice of the second base layer 13-2 can be reduced, thereby applying tensile stress to the third base layer 13-3 and the perpendicular magnetic layer 14, and the perpendicular magnetic layer 14 can be stably oriented in the (001) plane. In addition, the heating effect caused by the irradiated light is reduced to the soft magnetic layer 12 and the non-magnetic substrate 11, so that the crystallization of the alloy constituting the soft magnetic layer 12 can be prevented, and the strain of the non-magnetic substrate 11 can be relaxed.

[0056] The third underlayer 13-3 is preferably stacked on the second underlayer 13-2 and contains MgO as a main component as a NaCl type compound. The third underlayer 13-3 contains MgO as a main component, so that the magnetic grains having the L10 structure included in the perpendicular magnetic layer 14 can be oriented in the (001) direction.

[0057] (Perpendicular Magnetic Layer)

[0058] The perpendicular magnetic layer 14 includes magnetic grains having an L10 structure. Examples of the magnetic grains having an L10 structure include FePt alloy grains containing an FePt alloy and CoPt alloy grains containing a CoPt alloy.

[0059] The particle size of the magnetic particles is preferably 3 nm to 10 nm, and 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 with TEM.

[0060] The distance between the magnetic particles is preferably 4 nm to 12 nm, more preferably 5 nm to 9 nm. In addition, the distance between the magnetic particles refers to the distance between the centers of gravity of adjacent magnetic particles. The distance between the magnetic particles can be measured by a general measurement method such as observing a plane with a TEM.

[0061] Furthermore, the perpendicular magnetic layer 14 may have a granular structure including a grain boundary portion.

[0062] When the perpendicular magnetic layer 14 has a granular structure, the content of the grain boundary portion in the perpendicular magnetic layer 14 is preferably 25 volume % to 50 volume %, and more preferably 35 volume % to 45 volume %. If the content of the grain boundary portion in the perpendicular magnetic layer 14 is within the above preferred range, the anisotropy of the magnetic grains included in the perpendicular magnetic layer 14 can be improved.

[0063] Here, the grain boundary portion can contain carbides, nitrides, oxides, borides, etc. Specifically, BN, B4C, C, MoO3, GeO2, etc. can be cited.

[0064] The magnetic particles are preferably oriented in the c-axis direction, that is, (001) direction, with respect to the surface of the non-magnetic substrate 11 .

[0065] 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. When the thickness of the perpendicular magnetic layer 14 is within the above preferred range, high recording density can be achieved.

[0066] The perpendicular magnetic layer 14 can be formed on the base layer 13 by a sputtering method or the like.

[0067] The vertical magnetic layer 14 may include one magnetic layer or may include a plurality of magnetic layers stacked together. When the vertical magnetic layer 14 includes a plurality of magnetic layers, each magnetic layer may be formed using the same type of material or different types of materials. In addition, each magnetic layer may include a non-magnetic layer between each other. The non-magnetic layer may be formed using a general material used for magnetic recording media.

[0068] (Protective layer)

[0069] The protective layer 15 has a function of protecting the magnetic recording medium 10 from damage caused by contact between the magnetic head and the magnetic recording medium 10 .

[0070] As a material forming the protective layer 15 , for example, a carbon material such as diamond-like carbon (DLC; Diamond Like Carbon) can be used.

[0071] The thickness of the protective layer 15 is preferably 1 nm to 10 nm, and more preferably 2 nm to 6 nm.

[0072] In addition, in the present embodiment, the magnetic recording medium 10 may include a lubricant layer (not shown) on the protective layer 15. As a material forming the lubricant layer, for example, a resin such as perfluoropolyether can be used. The thickness of the lubricant layer is not particularly limited and can be set to any appropriate thickness, for example, it can be about 1.5 nm.

[0073] In this embodiment, the magnetic recording medium 10 may include a Ti-based underlayer containing Cr and Ti between the nonmagnetic 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.

[0074] 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 only of Ta. The thickness of the Ta-based underlayer is not particularly limited and may be any appropriate thickness.

[0075] [Method for producing magnetic recording medium]

[0076] The method for manufacturing a magnetic recording medium according to the present embodiment includes steps of forming the soft magnetic layer 12 , forming the base layer 13 , forming the perpendicular magnetic layer 14 , and forming the protective layer 15 , and may include other configurations such as a step of forming a lubricant layer.

[0077] In the method for manufacturing a magnetic recording medium according to the present embodiment, first, the soft magnetic layer 12 is formed on the prepared nonmagnetic substrate 11 (soft magnetic layer forming step).

[0078] As a method for forming the soft magnetic layer 12 , a general film forming method such as a sputtering method (sputtering method) can be used.

[0079] In the sputtering method, a target containing a material forming the soft magnetic layer 12 can be used.

[0080] As a target including a material forming the soft magnetic layer 12 , for example, a soft magnetic alloy such as a FeCo alloy, a CoZrNb alloy, or a CoTaZr alloy can be used.

[0081] As the sputtering method, a DC sputtering method, a DC magnetron sputtering method, an RF sputtering method, or the like can be used.

[0082] When forming the soft magnetic layer 12, RF (Radio Frequency) bias, DC bias, pulse DC, pulse DC bias, etc. can be used as necessary.

[0083] As the reactive gas, O 2 gas, H 2 O gas, N 2 gas, etc. can be used.

[0084] The sputtering gas pressure is appropriately adjusted so that the characteristics of each layer are optimized, and is usually within the range of about 0.1 Pa to 30 Pa.

[0085] Next, the base layer 13 is formed on the soft magnetic layer 12 (base layer forming step).

[0086] The step of forming the base layer may include a step of forming a first base layer, a step of forming a second base layer, and a step of forming a third base layer.

[0087] As a method for forming the first underlayer 13 - 1 , similarly to the method for forming the soft magnetic layer 12 , the first underlayer 13 - 1 can be formed by a sputtering method using a target containing a material for forming the first underlayer 13 - 1 .

[0088] As a target including a material forming the first underlayer 13-1, a target including a material forming the first underlayer 13-1 can be used. As a material forming the first underlayer 13-1, a bcc alloy containing Cr as a main component and having a (100) orientation, or the like can be used.

[0089] The sputtering conditions other than the material for forming the base layer 13 can be the same as the sputtering conditions for the soft magnetic layer 12 .

[0090] As a method for forming the second underlayer 13 - 2 , similarly to the method for forming the soft magnetic layer 12 , the second underlayer 13 - 2 can be formed by a sputtering method using a target containing a material for forming the second underlayer 13 - 2 .

[0091] As a target including a material forming the second underlayer 13-2, a target including a material forming the second underlayer 13-2 can be used. As a material forming the second underlayer 13-2, a bcc alloy containing W as a main component and having a (100) orientation of W or the like can be used.

[0092] The sputtering conditions other than the material for forming the second underlayer 13 - 2 can be the same as the sputtering conditions for the soft magnetic layer 12 .

[0093] As a method for forming the third underlayer 13 - 3 , similarly to the method for forming the soft magnetic layer 12 , the third underlayer 13 - 3 can be formed by a sputtering method using a target containing a material for forming the third underlayer 13 - 3 .

[0094] As a target including a material forming the third underlayer 13-3, a target including a material forming the third underlayer 13-3 can be used. As a material forming the third underlayer 13-3, a NaCl type compound can be used. As a NaCl type compound, MgO can be used.

[0095] The sputtering conditions other than the material for forming the third underlayer 13 - 3 can be the same as the sputtering conditions for the soft magnetic layer 12 .

[0096] Next, the perpendicular magnetic layer 14 is formed on the base layer 13 (perpendicular magnetic layer forming step).

[0097] As a method for forming the perpendicular magnetic layer 14 , similarly to the method for forming the soft magnetic layer 12 , the perpendicular magnetic layer 14 can be formed by a sputtering method using a target containing a material for forming the perpendicular magnetic layer 14 .

[0098] A target containing an alloy having an L10 structure can be used as a target containing a material forming the perpendicular magnetic layer 14. As the alloy having an L10 structure, an alloy containing Fe, Co, and Pt can be used, for example, a FePt alloy or a CoPt alloy.

[0099] The sputtering conditions other than the sputtering conditions for forming the perpendicular magnetic layer 14 can be the same as the sputtering conditions for the soft magnetic layer 12 .

[0100] Next, the surface of the perpendicular magnetic layer 14 is heated by LED light emitted from an LED light source while the perpendicular magnetic layer 14 is stacked on the nonmagnetic substrate 11 , the soft magnetic layer 12 , and the base layer 13 , thereby improving the crystal orientation of the perpendicular magnetic layer 14 (heating step).

[0101] The LED light source preferably has a central wavelength of less than 500 nm, a heating area diameter of more than 90 mm, and a light intensity of 1.5 W / cm 2 ~15W / cm 2 , the uniformity of the light intensity in the heating area is within ±15% of the LED light. Thus, the LED light source can efficiently heat only the perpendicular magnetic layer 14 by the LED light.

[0102] Here, the uniformity of the light intensity in the heated area is measured at the heating position of the LED light source, that is, at the position corresponding to the heating 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, measuring the distribution of light intensity in the substrate surface, and calculating the variation width relative to the average value of the light intensity distribution.

[0103] Furthermore, it is preferable to use an LED light source that does not contain light having a central wavelength of 500 nm or longer.

[0104] As mentioned above, in order to regularize the FePt alloy having the L10 regular structure, it is generally known that heat treatment at a high temperature of more than 400°C is required. This heat treatment has been carried out using electromagnetic waves such as halogen lamps, lasers, radio frequency, and microwaves. However, when a halogen lamp is used, the irradiation wavelength of the halogen lamp is as wide as about 500nm to 3.5μm, so the entire area from the non-magnetic substrate 11 to the vertical magnetic layer 14 will be heated. When a laser is used, by vibrating the laser at a specific wavelength, only a specific substance can be heated. The irradiation area of ​​the laser is narrow, and it is difficult to uniformly heat the entire surface of the vertical magnetic layer 14. When electromagnetic waves are used, the heating efficiency of the electromagnetic waves depends on the dielectric constant of the heated object, so it is not suitable for the electromagnetic waves to heat only the vertical magnetic layer 14.

[0105] In this embodiment, the vertical magnetic layer 14 is heated using LED light emitted from an LED light source, thereby being able to efficiently heat the vertical magnetic layer 14. That is, Fe, Pt, and Co contained in the vertical magnetic layer 14 have a peak of light absorption on the short wavelength side of less than 500 nm. The LED light emitted from the LED light source of this embodiment also has a wide heating area, and the uniformity of the light intensity in the heating area is also high, so the entire area of ​​the vertical magnetic layer 14 can be heated approximately uniformly.

[0106] In addition, the NaCl type compound contained in the third base layer 13-3 has a peak of light absorption above 500nm, so it is difficult to heat up when heated by LED light, and has a heat insulation effect. Therefore, in the heating process of the perpendicular magnetic layer 14, the temperature increase of the non-magnetic substrate 11, the soft magnetic layer 12 and the base layer 13 can be suppressed.

[0107] The penetration depth of light is determined by the wavelength, and it is considered that the depth is about 0.1λnm (λ is the central wavelength of the irradiated light (unit: nm)), so the light radiated from the halogen lamp in the past penetrates into the deep layer and heats it. In contrast, the LED light radiated from the LED light source is difficult to penetrate from the irradiated surface to the deep layer, and the heating effect is reduced. Therefore, by making the layer thickness of the second base layer 13-2 0.1λnm~100nm, the temperature rise of the layer lower than the second base layer 13-2 can be further suppressed. In addition, by thickening the second base layer 13-2, the tensile stress applied to the third base layer 13-3, which is a NaCl-type compound layer, can be increased.

[0108] Furthermore, since the outer diameter of the nonmagnetic substrate 11 is generally 2.5 inches or 3.5 inches, the entire nonmagnetic substrate 11 can be uniformly heated by setting the diameter of the heating region of the LED light source to 90 mm or more.

[0109] Cr contained in the first base layer 13-1 is an element that is easy to diffuse thermally. As a result, the thermal diffusion at the interface between the first base layer 13-1 and the second base layer 13-2 can be suppressed by the thermal insulation effect of the second base layer 13-2 and the third base layer 13-3 as a layer containing a NaCl type compound. As a result, it is possible to suppress the diffusion of Cr atoms to the second base layer 13-2 such as the W alloy layer, thereby suppressing the lattice contraction of the second base layer 13-2 due to the replacement of W atoms with Cr atoms. As a result, the tensile stress applied by the third base layer 13-3 containing MgO as a main component is reduced, and it is possible to suppress the obstruction of the regularization of the FePt-based alloy and the like contained in the perpendicular magnetic layer 14.

[0110] Furthermore, due to the heat insulating effect of the second underlayer 13 - 2 and the third underlayer 13 - 3 , heating of the soft magnetic layer 12 located below the first underlayer 13 - 1 can be suppressed, thereby suppressing crystallization of the soft magnetic layer 12 .

[0111] Furthermore, since the second underlayer 13-2 has a heat insulating effect, it is not necessary to increase the thickness of the third underlayer 13-3 which is a layer containing a NaCl type compound, thereby reducing the tensile stress associated with thickening the third underlayer 13-3.

[0112] Furthermore, the heat insulating effect of the second base layer 13 - 2 and the third base layer 13 - 3 suppresses heating of the nonmagnetic substrate 11 located below the first base layer 13 - 1 , thereby reducing the occurrence of undulations due to strain relaxation and coarsening of crystals.

[0113] Next, the protective layer 15 is formed on the perpendicular magnetic layer 14 (a step of forming the protective layer 15 ).

[0114] There is no particular limitation on the film forming method of the protective layer 15. For example, a general film forming method such as an RF-CVD (Radio Frequency-Chemical Vapor Deposition) method in which a raw material gas containing hydrocarbons is decomposed by high-frequency plasma to form a film, an IBD (Ion Beam Deposition) method in which a raw material gas is ionized by electrons emitted from a filament to form a film, or an FCVA (Filtered Cathodic Vacuum Arc) method in which a solid carbon target is used to form a film without using a raw material gas can be used.

[0115] Furthermore, the lubricant layer 16 can be formed on the surface of the protective layer 15 using a general coating method or the like (lubricant layer forming step).

[0116] As described above, by forming the protective layer 15 on the perpendicular magnetic layer 14, the Figure 1A magnetic recording medium 10 is shown.

[0117] Thus, the method for manufacturing a magnetic recording medium according to the present embodiment includes a step for forming a perpendicular magnetic layer and a step for heating the perpendicular magnetic layer. In the step for heating the perpendicular magnetic layer, the surface of the perpendicular magnetic layer 14 is heated by the LED light emitted by the LED light source. The LED light source irradiates LED light having a central wavelength of less than 500 nm. Thus, the method for manufacturing a magnetic recording medium according to the present embodiment can heat only the perpendicular magnetic layer 14 approximately uniformly throughout its entire area by the LED light emitted from the LED light source, and can suppress the LED light from reaching the non-magnetic substrate 11, the soft magnetic layer 12, and the base layer 13 located at a lower layer than the perpendicular magnetic layer 14 and heating them. Thus, the method for manufacturing a magnetic recording medium according to the present embodiment can efficiently heat only the perpendicular magnetic layer 14 while suppressing the influence of heating on the non-magnetic substrate 11, the soft magnetic layer 12, and the base layer 13 located at a lower side than the perpendicular magnetic layer 14.

[0118] The method for manufacturing a magnetic recording medium according to the present embodiment can further increase the heating temperature of the perpendicular magnetic layer 14 by LED light, thereby further improving the crystal orientation of the perpendicular magnetic layer 14. In addition, the method for manufacturing a magnetic recording medium according to the present embodiment can suppress the diffusion of elements constituting the base layer 13 to the soft magnetic layer 12 by the heat of heating the perpendicular magnetic layer 14, thereby suppressing the obstruction of the amorphous structure of the soft magnetic layer 12 and the damage of the soft magnetic properties of the soft magnetic layer 12. Furthermore, the undulation of the non-magnetic substrate 11 due to the heat of heating the perpendicular magnetic layer 14 can be reduced. As a result, the surface undulation of the magnetic recording medium 10 of the method for manufacturing a magnetic recording medium according to the present embodiment is small, and a magnetic recording medium 10 with excellent electromagnetic conversion characteristics can be manufactured.

[0119] In the manufacturing method of the magnetic recording medium involved in the present embodiment, the LED light source may not contain LED light with a central wavelength of more than 500nm. The third base layer 13-3 has a peak of light absorption above 500nm, so it can have a heat insulation effect that is difficult to produce due to the temperature rise caused by the LED light. Therefore, in the heating process of the vertical magnetic layer 14, the manufacturing method of the magnetic recording medium involved in the present embodiment can prevent the non-magnetic substrate 11, the soft magnetic layer 12 and the base layer 13 located below the vertical magnetic layer 14 from heating, thereby more reliably suppressing the influence of heating on these components.

[0120] In the method for manufacturing a magnetic recording medium according to the present embodiment, the LED light used for irradiation may have a central wavelength of less than 500 nm, a heating area diameter of 90 mm or more, and a light intensity of 1.5 W / cm 2 ~15W / cm 2, the uniformity of the light intensity in the heating area is within ±15% of the LED light. Therefore, the method for manufacturing a magnetic recording medium according to the present embodiment can heat only the perpendicular magnetic layer 14 throughout its entire area more uniformly by the LED light, and can further suppress the LED light from reaching the non-magnetic substrate 11, the soft magnetic layer 12, and the base layer 13 located below the perpendicular magnetic layer 14 for heating. Therefore, the method for manufacturing a magnetic recording medium according to the present embodiment can heat only the perpendicular magnetic layer 14 more efficiently, while further suppressing the influence of heating on the non-magnetic substrate 11, the soft magnetic layer 12, and the base layer 13 located below the perpendicular magnetic layer 14.

[0121] In the manufacturing method of the magnetic recording medium involved in the present embodiment, the base layer 13 is stacked in sequence from the non-magnetic substrate 11 side and has a first base layer 13-1, a second base layer 13-2 and a third base layer 13-3, and when the central wavelength is set to λnm, the film thickness of the second base layer 13-2 can be made to be (λ×0.1)nm or more. Thus, the manufacturing method of the magnetic recording medium involved in the present embodiment can further reliably suppress the temperature rise caused by LED light on the non-magnetic substrate 11 and the soft magnetic layer 12 located below the second base layer 13-2, and can increase the tensile stress of the third base layer 13-3. Therefore, according to the manufacturing method of the magnetic recording medium involved in the present embodiment, the influence of heating caused by LED light on the non-magnetic substrate 11 and the soft magnetic layer 12 located below the second base layer 13-2 can be further reliably suppressed, so that the electromagnetic conversion characteristics of the magnetic recording medium 10 can be improved.

[0122] [Magnetic recording and reproducing device]

[0123] The magnetic recording and reproducing device using the magnetic recording medium manufactured by the manufacturing method of the magnetic recording medium involved in the present embodiment is described. The magnetic recording and reproducing device involved in the present embodiment is not particularly limited in form as long as it has the magnetic recording medium manufactured by the manufacturing method of the magnetic recording medium involved in the present embodiment. In addition, here, the situation in which the magnetic recording and reproducing device uses the thermal assisted recording method to record magnetic information on the magnetic recording medium is described.

[0124] Figure 2 It 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 the present embodiment. Figure 2As shown, the magnetic recording and reproducing device 100 can include: a magnetic recording medium 101, a magnetic recording medium driving unit 102 for rotating the magnetic recording medium 101, a magnetic head 103 having a near-field light generating element at the front end, a magnetic head driving unit 104 for moving the magnetic head 103, and a recording and reproducing signal processing unit 105. The magnetic recording medium 101 adopts the magnetic recording medium 10 manufactured using the manufacturing method of the magnetic recording medium according to the present embodiment.

[0125] Figure 3 1 is a schematic diagram showing an example of the magnetic head 103 . Figure 3 As shown, the magnetic head 103 includes a recording head 110 and a reproducing head 120 .

[0126] The recording head 110 has: a main magnetic pole 111, an auxiliary magnetic pole 112, a coil 113 for generating a magnetic field, a laser diode (LD) 114 as a laser generating unit for heating the magnetic recording medium 101, and a waveguide 116 for transmitting the laser light L generated by the LD 114 to the near-field light generating element 115.

[0127] The reproducing head 120 includes a shield 121 and a reproducing element 122 sandwiched by the shield 121 .

[0128] Figure 3 As shown, the magnetic recording and reproducing device 100 installs the central portion of the magnetic recording medium 101 on the rotating axis of the spindle motor, and while the magnetic head 103 floats and moves, information is written or read relative to the magnetic recording medium 101 on the surface of the magnetic recording medium 101 that is driven to rotate by the spindle motor.

[0129] The magnetic recording and reproducing device 100 according to the present embodiment uses the magnetic recording medium 101 manufactured using the method for manufacturing a magnetic recording medium according to the present embodiment. As a result, the magnetic recording medium 101 can have excellent electromagnetic conversion characteristics, thereby stably having a high recording density.

[0130] Example

[0131] Hereinafter, although an Example and a comparative example are shown and embodiment is demonstrated concretely, embodiment is not limited to these Examples and comparative examples.

[0132] <Example 1>

[0133] [Manufacturing of magnetic recording media]

[0134] A magnetic recording medium was produced by the method described below.

[0135] First, on a glass substrate with an outer diameter of 2.5 inches, a Ti-based base layer with a thickness of 50 nm and containing 50 at% Cr-50 at% Ti (Cr content 50 at%, Ti content 50 at%) is formed, and then a 40 at% Co-46 at% Fe-14 at% B soft magnetic layer with a thickness of 150 nm is formed. Then, the glass substrate is heated to 320°C by a halogen lamp to form a Ta base layer with a thickness of 10nm including Ta, a first base layer with a thickness of 10nm including 42.5at% Cr-50at% V-7.5at% Ti, a second base layer with a thickness of 60nm including W, a third base layer with a thickness of 3nm including MgO, and a vertical magnetic layer with a thickness of 10nm including 82mol% (50at% Fe-50at% Pt)-10mol% SiO2-8mol% BN (Fe content of 50at%, Pt content of 50at%, FePt content of 82mol%, SiO2 content of 10mol%, BN content of 8mol%).

[0136] Then, the surface of the perpendicular magnetic layer is irradiated with LED light from an LED light source to heat the surface of the perpendicular magnetic layer. The LED light source has a central wavelength of 395nm (excluding light with a central wavelength of 500nm or more), the irradiation area (heating area) is 100mm in diameter (effective area), and the light intensity in the effective area is 11W / cm 2 The uniformity of the light intensity on the substrate surface in the effective area 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.

[0137] Next, a protective layer having a thickness of 4 nm and containing diamond-like carbon (DLC) was formed on the perpendicular magnetic layer, and then a liquid lubricant layer having a thickness of 1.5 nm and containing perfluoropolyether was formed by coating.

[0138] The above steps are used to manufacture a magnetic recording medium. The thickness of the third base layer and the heating conditions of the perpendicular magnetic layer (heating means, central wavelength, wavelength range, light intensity, uniformity of light intensity (light intensity uniformity), and the presence or absence of light with a central wavelength of 500 nm or more) are shown in Tables 1 and 2.

[0139] [Evaluation of characteristics of magnetic recording media]

[0140] As the characteristics of the magnetic recording medium, the orientation of the perpendicular magnetic layer and the SNR as the electromagnetic conversion characteristic were measured and evaluated.

[0141] (Measurement of Orientation of Perpendicular Magnetic Layer)

[0142] The (001) intensity of the FePt alloy constituting the perpendicular magnetic layer was measured using an X-ray diffraction device to evaluate the (001) orientation of the perpendicular magnetic layer. Tables 1 and 2 show the measurement results of the (001) intensity of the FePt alloy.

[0143] (Measurement of electromagnetic conversion characteristics)

[0144] The electromagnetic conversion characteristic (SNR) was measured by a rotating bracket tester using a magnetic head equipped with a laser spot heating mechanism. At this time, the current input by the laser diode was adjusted so that the half width of the recording track (MWW) defined as the half width of the reproduced signal waveform was 70nm, and the SNR was confirmed. The results of the SNR measurement are shown in Tables 1 and 2.

[0145] <Examples 2 to 14>

[0146] In Example 1, the film thickness of the second base layer and the heating conditions of the vertical magnetic layer (heating means, central wavelength, wavelength range, light intensity, light intensity uniformity and the presence or absence of light with a central wavelength of more than 500nm) are changed to the conditions shown in Tables 1 and 2 for manufacturing. Except for this, the same manufacturing method as Example 1 is followed.

[0147] <Comparative Examples 1 to 7>

[0148] In Example 1, the film thickness of the second base layer and the heating conditions of the perpendicular magnetic layer (heating means, central wavelength, wavelength range, light intensity, light intensity uniformity, and the presence or absence of light with a central wavelength of 500nm or more) were changed to the conditions shown in Tables 1 and 2 for manufacturing, and the same method as in Example 1 was used. In addition, when heating the perpendicular magnetic layer, halogen lamps were used in Comparative Examples 3, 5, and 6, and the heating time was 10 seconds, and the surface temperature of the perpendicular magnetic layer was up to 550°C. The halogen lamp used a central wavelength of 1000nm, and the wavelength range used was 350nm to 3500nm. In Comparative Example 4, radio frequency was used. The heating time was 10 seconds, and the surface temperature of the perpendicular magnetic layer was up to 550°C. The vibration frequency of the radio frequency was 13.56MHz, and the maximum output was 1kW.

[0149] [Table 1]

[0150]

[0151] [Table 2]

[0152]

[0153] From Tables 1 and 2, in Examples 1 to 14, the (001) intensity of the FePt alloy constituting the perpendicular magnetic layer is 205.4 or more, and the SNR of the magnetic recording medium is 2.68 dB or more. On the other hand, in Comparative Examples 1 to 7, the (001) orientation of the perpendicular magnetic layer is 205.9 or less, and the SNR of the magnetic recording medium is 2.65 dB or less.

[0154] The manufacturing method of the magnetic recording medium of Examples 1 to 14 is different from the manufacturing method of the magnetic recording medium of Comparative Examples 1 to 7. After forming a perpendicular magnetic layer on the third base layer containing MgO, the surface of the perpendicular magnetic layer is irradiated with LED light from an LED light source under predetermined irradiation conditions, and the surface of the perpendicular magnetic layer is heated by the LED light. Moreover, the manufacturing method of the magnetic recording medium of Examples 1 to 14 is to irradiate LED light with a central wavelength of less than 395nm from an LED light source. Therefore, in the manufacturing method of the magnetic recording medium of Examples 1 to 14, it is confirmed that the heat during the heating of the perpendicular magnetic layer is suppressed to affect the glass substrate, Ti-based base layer, soft magnetic layer, first base layer, second base layer and third base layer located on the lower side of the perpendicular magnetic layer, and the magnetic recording medium can be manufactured. Therefore, it can be said that the magnetic recording medium involved in this embodiment can be effectively used in a magnetic recording and reproducing device.

[0155] As described above, the embodiments are described, and the above embodiments are provided 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, changes, etc. can be made without departing from the scope of the main purpose of the invention. These embodiments and their modifications are included in the scope and main purpose of the invention, and are included in the scope of equality with the invention described in the claims.

[0156] This application claims the priority based on Japanese Patent Application No. 2022-070962 filed with the Japan Patent Office on April 22, 2022, and cites all the contents described in the above application.

[0157] Explanation of symbols

[0158] 10.101 Magnetic Recording Media

[0159] 11 Non-magnetic substrate

[0160] 12 Soft magnetic layer

[0161] 13 Basal layer

[0162] 13-1 The first basal layer

[0163] 13-2 Second basal layer

[0164] 13-3 The third basal layer

[0165] 14. Perpendicular Magnetic Layer

[0166] 15. Protective layer

[0167] 100 Magnetic recording and reproducing device

[0168] 102 Magnetic recording medium drive unit

[0169] 103 Magnetic Head

[0170] 104 Magnetic head drive unit

[0171] 105 Recording and reproduction signal processing unit

Claims

1. A method for manufacturing a magnetic recording medium, which is a method for manufacturing a magnetic recording medium having a substrate, a base layer, and a perpendicular magnetic layer having an L10 structure in sequence, comprising: After the vertical magnetic layer is formed, a process of heating the surface of the vertical magnetic layer by LED light emitted from an LED light source to improve the crystal orientation of the vertical magnetic layer, The base layer comprises a NaCl type compound, The central wavelength of the LED light is less than 500 nm.

2. The method for manufacturing a magnetic recording medium according to claim 1, The LED light source does not contain LED light with a central wavelength of more than 500 nm.

3. The method for producing a magnetic recording medium according to claim 1 or 2, The central wavelength of the LED light is less than 500nm, the diameter of the heating area is more than 90mm, and the light intensity is 1.5W / cm 2 ~15W / cm 2 , the uniformity of the light intensity in the heating area is within ±15%.

4. The method for producing a magnetic recording medium according to any one of claims 1 to 3, The base layer is stacked in order from the substrate side and comprises: The first underlayer is a bcc alloy with Cr as the main component and oriented in the (100) direction. a second underlayer composed of a bcc alloy having W as a main component and oriented in a (100) direction; and The third base layer includes MgO, which is the NaCl type compound, as a main component. The film thickness of the second base layer is greater than or equal to (λ×0.1) nm when the central wavelength is λ nm.

5. A magnetic recording and reproducing device, comprising: A magnetic recording medium produced by the method for producing a magnetic recording medium according to any one of claims 1 to 4.

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