Magnetic recording medium and magnetic storage device

Abstract

To provide a method for producing a magnetic recording medium capable of having a magnetic layer with high crystal orientation and few defects, a magnetic recording medium, and a magnetic storage device.SOLUTION: A method of producing a magnetic recording medium 1 includes: a step of forming a magnesium oxide underlayer 20 on a surface of a substrate 10 by a sputtering method with using a target containing magnesium oxide; and a step of forming a magnetic layer 30 on the surface side of the magnesium oxide underlayer 20, in which the target containing the magnesium oxide is heated to more than 600°C when forming the magnesium oxide underlayer 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a magnetic recording medium, a magnetic recording medium, and a magnetic storage device.

Background Art

[0002] A magnetic recording medium is generally manufactured by laminating an underlayer, a magnetic layer, and a protective layer in this order on a substrate. As a method for recording magnetic information on a magnetic recording medium, there is a heat assist recording method in which a magnetic recording medium is irradiated with laser light or the like to locally heat the surface of the magnetic layer, thereby reducing the coercivity of the magnetic layer and recording magnetic information. Since the heat assist recording method can achieve areal recording densities in the 1 Tbit / inch 2 class, it is being studied as a next-generation magnetic recording method capable of increasing the storage capacity with the miniaturization and high recording density of magnetic recording media.

[0003] As a magnetic recording medium that can be used for the heat assist recording method, for example, there is disclosed a magnetic recording medium including a substrate, a plurality of underlayers formed on the substrate, and a magnetic layer mainly composed of an alloy having an L10 structure, wherein the plurality of underlayers include a NiO underlayer and an orientation control layer (see, for example, Patent Document 1). In this magnetic recording medium, the orientation control layer includes an underlayer made of an alloy having a BCC structure and an underlayer such as MgO having an NaCl structure, and the NiO underlayer is made to have a (100) orientation.

[0004] When an FePt alloy having an L10 structure is used as the magnetic layer of a magnetic recording medium, the (001) plane is used as the crystal orientation plane of the magnetic layer. In order to orient the FePt alloy in the (001) direction, generally, MgO having a (100) orientation is often used as the underlayer. That is, since the (100) plane of MgO has a high lattice matching with the (001) plane of the FePt alloy, by forming a magnetic layer containing the FePt alloy above the MgO layer, the FePt alloy can be easily oriented in the (001) direction. Further, in the magnetic recording medium of Patent Document 1, since the NiO underlayer also has a (100) orientation, MgO is used as the underlayer of the orientation control layer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When MgO is used for forming an orientation control layer, a sputtering method is generally used for forming the MgO layer. However, since MgO has a high melting point, its sinterability is poor. When the MgO layer is formed by the sputtering method using a target with poor sinterability, abnormal discharge (arcing) occurs on the target surface, and the target surface melts and scatters, resulting in a problem that sputter dust is likely to be generated. Due to this sputter dust, the crystal orientation of the MgO layer deteriorates, and defects are likely to occur in the MgO layer. Therefore, the crystal orientation of the magnetic layer formed on the MgO layer deteriorates, and the possibility of defects occurring in the magnetic layer increases.

[0007] One aspect of the present invention aims to provide a method for manufacturing a magnetic recording medium capable of having a magnetic layer with high crystal orientation and few defects.

Means for Solving the Problems

[0008] One aspect of the method for manufacturing a magnetic recording medium according to the present invention includes a step of forming a magnesium oxide underlayer on the surface of a substrate by a sputtering method using a target containing magnesium oxide, and a step of forming a magnetic layer on the surface side of the magnesium oxide underlayer. When forming the magnesium oxide underlayer, the target containing magnesium oxide is heated to 600°C or higher.

[0009] A magnetic recording medium according to one aspect of the present invention includes a magnesium oxide underlayer and a magnetic layer containing an FePt alloy having an L10 structure. The magnesium oxide underlayer contains magnesium oxide, and the magnesium oxide has a peak of the O1s spectrum measured by XPS in the range of 531 eV to 533 eV.

Advantages of the Invention

[0010] According to one aspect of the present invention, it is possible to have a magnetic layer with high crystal orientation and few defects.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail. For ease of understanding of the description, the same reference numerals are given to the same components in each drawing, and redundant descriptions are omitted. Also, the scales of the respective members in the drawings may be different from the actual ones. In this specification, "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value, unless otherwise specified.

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

[0014] [Magnetic Recording Medium] FIG. 1 is a cross-sectional view showing an example of the configuration of a magnetic recording medium according to this embodiment. As shown in FIG. 1, the magnetic recording medium 1 includes a substrate 10, an underlayer 20, and a magnetic layer 30 containing an alloy having an L10 structure, which are laminated in this order from the substrate 10 side.

[0015] In this specification, the thickness direction (vertical direction) of the magnetic recording medium 1 is defined as the Z-axis direction, and the lateral direction (horizontal direction) orthogonal to the thickness direction is defined as the X-axis direction. The magnetic layer 30 side in the Z-axis direction is the +Z-axis direction, and the substrate 10 side is the -Z-axis direction. In the following description, for convenience of explanation, the +Z-axis direction is referred to as up or upward, and the -Z-axis direction is referred to as down or downward, but this does not represent a universal up-down relationship.

[0016] In FIG. 1, only the underlayer 20 and the magnetic layer 30 are shown above the substrate 10, but the magnetic recording medium 1 also includes the underlayer 20 and the magnetic layer 30 laminated in this order from the substrate 10 side below the substrate 10.

[0017] The magnetic recording medium 1 has the underlayer 20 and the magnetic layer 30 on both the upper and lower surfaces of the substrate 10, and information can be recorded on both the upper and lower surfaces of the substrate 10 (double-sided recording). However, it may also have the underlayer 20 and the magnetic layer 30 on only one of the upper or lower surfaces of the substrate 10, and information can be recorded on only one side of the substrate 10 (single-sided recording).

[0018] The material constituting the substrate 10 is not particularly limited as long as it is a material that can be used for a magnetic recording medium and can be used. Examples of the material constituting the substrate 10 include Al alloys such as AlMg alloy, soda glass, aluminosilicate glass, amorphous glasses, silicon, titanium, ceramics, sapphire, quartz, resins, and the like. Among these, glasses such as Al alloys, crystallized glass, and amorphous glass are preferable.

[0019] The underlayer 20 may include a magnesium oxide (MgO) underlayer 21 as the first underlayer and a second underlayer 22. The underlayer 20 includes the MgO underlayer (the first underlayer) 21 and the second underlayer 22, which are laminated in the order of the second underlayer 22 and the MgO underlayer 21 from the substrate 10 side.

[0020] The MgO underlayer 21 is provided above the second underlayer 22. The MgO underlayer 21 is preferably the uppermost layer (the layer farthest from the substrate 10) of the underlayer 20, preferably contains MgO, preferably consists essentially of MgO, and more preferably consists only of MgO. "Essentially" means that it may contain inevitable impurities that may be unavoidably contained in the manufacturing process in addition to MgO.

[0021] In the present embodiment, since the MgO underlayer 21 is in contact with the first magnetic layer 31, the (100) plane of MgO and the (001) plane of the magnetic alloy having the L10 structure contained in the first magnetic layer 31 are easily lattice-matched, so that the crystal orientation of the magnetic alloy can be improved.

[0022] As will be described later, the MgO underlayer 21 is formed by film formation under predetermined conditions by a sputtering method (sputtering). The MgO underlayer 21 has a peak of the O1s spectrum of MgO detected when measured by X-ray photoelectron spectroscopy (XPS) in the range of 531 eV to 533 eV. Details of the manufacturing conditions and characteristics of the MgO underlayer 21 will be described later.

[0023] The second underlayer 22 is provided above the substrate 10.

[0024] As the material constituting the second underlayer 22, there is no particular limitation as long as the first magnetic layer 31 can be (001)-oriented. For example, W, Cr having a (100) orientation, a Cr alloy having a BCC structure, an alloy having a B2 structure, etc. can be mentioned.

[0025] Examples of the Cr alloy having a BCC structure include a CrMn alloy, a CrMo alloy, a CrW alloy, a CrV alloy, a CrTi alloy, a CrRu alloy, etc.

[0026] Examples of the alloy having a B2 structure include a RuAl alloy, a NiAl alloy, etc.

[0027] Note that the number of stacked layers of the underlayer 20 is not particularly limited, and each may be three or more layers.

[0028] When the number of stacked layers of the underlayer 20 is three or more, the underlayer other than the MgO underlayer 21 can be formed using the same material as the second underlayer 22.

[0029] The magnetic layer 30 includes a first magnetic layer 31 and a second magnetic layer 32 stacked in this order from the MgO underlayer 21 side.

[0030] The first magnetic layer 31 is the lowermost layer of the magnetic layer 30 (the layer closest to the substrate 10), and preferably contains an alloy having an L10 structure.

[0031] The alloy having an L10 structure constituting the first magnetic layer 31 preferably further contains Fe or Co and Pt. Specifically, as the alloy having an L10 structure, an FePt alloy or a CoPt alloy is preferably used. The magnetocrystalline anisotropy constant (Ku) of the FePt alloy is 7×10 6 J / m 3 or less, and the Ku of the CoPt alloy is 5×10 6 J / m 3 or less, and in both cases, 1×10 6 J / m 3It is a material with a high Ku value for the stage (high Ku material). Therefore, by using an FePt alloy or a CoPt alloy as the material constituting the first magnetic layer 31, the magnetic layer 30 can refine the magnetic particles constituting the magnetic layer 30, for example, until the particle size becomes 6 nm or less while maintaining thermal stability.

[0032] The first magnetic layer 31 may further contain a grain boundary segregation material and have a granular structure. Thereby, the first magnetic layer 31 is likely to be (001)-oriented, and the lattice matching with the (100)-oriented MgO underlayer 21 is improved.

[0033] Examples of the grain boundary segregation material contained in the first magnetic layer 31 include nitrides such as VN, BN, SiN, and TiN, carbides such as C and VC, borides such as BN, etc., and two or more kinds may be used in combination.

[0034] The second magnetic layer 32 preferably contains an alloy having an L10 structure, similar to the first magnetic layer 31. Thereby, the (001)-orientability of the magnetic layer 30 is improved. That is, as the second magnetic layer 32, a magnetic film epitaxially grown along the orientation of the first magnetic layer 31 can be formed.

[0035] The alloy having an L10 structure constituting the second magnetic layer 32 preferably contains Fe or Co and Pt, similar to the first magnetic layer 31.

[0036] The second magnetic layer 32 may further contain a grain boundary segregation material and have a granular structure, similar to the first magnetic layer 31.

[0037] Examples of the grain boundary segregation material contained in the second magnetic layer 32 include nitrides such as VN, BN, SiN, and TiN, carbides such as C and VC, borides such as BN, oxides such as SiO2, TiO2, Cr2O3, Al2O3, Ta2O5, ZrO2, Y2O3, CeO2, MnO, TiO, and ZnO, etc., and two or more kinds may be used in combination.

[0038] Note that the number of stacked layers of the magnetic layer 30 is not particularly limited, and may be three or more.

[0039] When the number of stacked magnetic layers 30 is three or more, the magnetic layers other than the first magnetic layer 31 can be formed using the same material as the second magnetic layer 32.

[0040] The magnetic recording medium 1 preferably includes a protective layer 40 on the magnetic layer 30.

[0041] The protective layer 40 has a function of protecting the magnetic recording medium 1 from damage due to contact with a magnetic head or the like.

[0042] The thickness of the protective layer 40 is preferably 1 nm to 6 nm. If the thickness of the protective layer 40 is 1 nm to 6 nm, the flying characteristics of the magnetic head become good, the magnetic spacing becomes small, and the SNR of the magnetic recording medium 1 is improved.

[0043] The magnetic recording medium 1 may further have a lubricant layer 50 on the protective layer 40.

[0044] Examples of the material constituting the lubricant layer 50 include fluororesins such as perfluoropolyether.

[0045] The magnetic recording medium 1 according to the present embodiment includes an MgO underlayer 21 containing MgO and a magnetic layer 30, and the MgO contained in the MgO underlayer 21 has a peak of the O1s spectrum detected by XPS in the range of 531 eV to 533 eV. Since the MgO underlayer 21 has a high crystal orientation and few defects, the magnetic layer 30 formed above the MgO underlayer 21 can also be formed with high crystal orientation and less likely to cause defects, similar to the MgO underlayer 21. Therefore, the magnetic recording medium 1 can have a magnetic layer 30 with high crystal orientation and few defects above the MgO underlayer 21.

[0046] [Manufacturing Method of Magnetic Recording Medium] The manufacturing method of the magnetic recording medium according to this embodiment includes a step of forming an MgO underlayer (first underlayer) and a step of forming a magnetic layer, and may include other components such as a step of forming a second underlayer, a step of forming a protective layer, and a step of forming a lubricant layer.

[0047] The manufacturing method of the magnetic recording medium according to this embodiment includes a step of forming a second underlayer, a step of forming an MgO underlayer (first underlayer), a step of forming a magnetic layer, a step of forming a protective layer, and a step of forming a lubricant layer.

[0048] In the manufacturing method of the magnetic recording medium according to this embodiment, first, as shown in FIG. 2, an MgO underlayer 21 may be formed on the surface of a substrate 10 (step of forming the first underlayer).

[0049] Next, as shown in FIG. 3, an MgO underlayer 21 is formed on the surface of the second underlayer 22 by a sputtering method (sputter method) using a target containing MgO (step of forming the MgO underlayer).

[0050] When forming the MgO underlayer 21, it is preferable to heat the target containing MgO to 600°C or higher, more preferably to 800°C or higher, and even more preferably to 1000°C or higher.

[0051] Since MgO has a high melting point, its sinterability is poor. Therefore, it is difficult to manufacture an MgO target containing sufficiently high-density MgO as a sputtering target. Since the relative density of a normal MgO target is about 65% to 98%, abnormal discharge (arcing) easily occurs on the target surface during sputtering. Due to this arcing, sputter dust generated by melting and scattering of the target surface adheres to the film formation surface which is the upper surface of the MgO underlayer 21, resulting in a decrease in the crystallinity of the MgO underlayer 21 and an increased tendency for defects to occur in the MgO underlayer 21. These are also passed on to the magnetic layer 30 formed on the upper surface of the MgO underlayer 21, causing a decrease in the crystallinity of the magnetic layer 30 and the introduction of defects into the magnetic layer 30, which may result in unreadable / writable areas on the data surface of the magnetic recording medium 1 and a decrease in the product yield.

[0052] As a result of intensive studies on the reduction of crystallinity of the magnetic layer 30 and the generation of defects in the magnetic layer 30, the inventors of the present application focused on the film formation conditions during the formation of the MgO underlayer 21, particularly the heating temperature of the MgO target containing MgO. By sputtering while heating the MgO target to an extremely high temperature of 600 °C or higher, the generation of sputter dust can be suppressed, and an MgO underlayer 21 with high crystal orientation and few defects can be formed. It has been found that the magnetic layer 30 formed above the MgO underlayer 21 also has improved crystal orientation and reduced defects.

[0053] FIG. 4 is a diagram showing an example of the relationship between the target temperature of the MgO target and the amount of sputter dust generated in the chamber of the sputtering apparatus. Note that FIG. 4 shows the result of performing sputtering for 2 hours using an MgO target with a relative density of 85% and a diameter of 120 mm, with an input power of 1 kW, a sputter gas pressure of 3 Pa, and an Ar gas as the sputter gas, using the RF sputtering method, and determining the amount of sputter dust. The amount of sputter dust was counted for the dust adhering within the range of a radius of 16 mm to 48 mm on one side of a substrate for a magnetic recording medium with a diameter of 3.5 inches. Note that the film formation time of the MgO film during the production of the magnetic recording medium is usually about 10 seconds. As shown in FIG. 4, if the target temperature of the MgO target is set to 600 °C or higher and sputtering is performed, the number of sputter dust can be reduced to 1 / 2 or less compared to the case where sputtering is performed with the target temperature of the MgO target set to 400 °C or lower.

[0054] In addition, the MgO film produced by the sputtering method with the heating temperature of the MgO target set to 600 °C or higher using an MgO target also differs in physical properties from the MgO film produced by the conventional method. Note that the conventional method is the case where film formation is performed without heating the MgO target, specifically, the case where film formation is performed with the temperature of the MgO target at 400 °C or lower. In this case, the back surface of the MgO target is usually water-cooled.

[0055] FIG. 5 is an O1s spectrum of a magnesium oxide film measured by X-ray photoelectron spectroscopy (XPS). In FIG. 5, (a) is the spectrum of the magnesium oxide film formed by the conventional method, and (b) is the spectrum of the magnesium oxide film manufactured by the manufacturing method of the magnetic recording medium according to the present embodiment. As shown in FIG. 5, in (a), there is a peak of the O1s spectrum near 530 eV. On the other hand, in (b), the peak of the O1s spectrum is shifted about 1 eV to the high energy side and is in the range of 531 eV to 533 eV.

[0056] According to the study by the inventors of the present application, such a peak shift becomes more prominent toward the surface layer side of the MgO film, and it is considered that it is caused by the substitution of a part of the oxygen in MgO with OH.

[0057] And it can be said that due to this substitution, the lattice matching between the MgO(100) plane and the (001) plane of the FePt alloy having the L10 structure is enhanced, and the (001) orientation of the FePt alloy film is enhanced.

[0058] Since the sputtering target containing MgO used in the sputtering method is usually an insulator, it is preferable to use the RF sputtering method as the sputtering method. On the other hand, when the sputtering target has conductivity, the DC sputtering method or the DC magnetron sputtering method can be used.

[0059] Next, as shown in FIG. 6, a magnetic layer 30 is formed on the surface of the MgO underlayer 21 (magnetic layer forming step).

[0060] In the magnetic layer forming step, a first magnetic layer 31 is formed on the surface of the MgO underlayer 21 (first magnetic layer forming step).

[0061] As a method for forming the first magnetic layer 31, it can be formed by a sputtering method using a target containing a material for forming the first magnetic layer 31.

[0062] As the target containing the material for forming the first magnetic layer 31, it is preferable to use a target containing an alloy having an L10 structure. As the alloy having an L10 structure, an alloy containing Fe or Co and Pt or the like can be used. For example, an FePt alloy, a CoPt alloy, or the like can be used.

[0063] As the sputtering method, a film formation method such as a DC magnetron sputtering method or an RF sputtering method can be used.

[0064] When forming the first magnetic layer 31, if necessary, an RF (Radio Frequency) bias, a DC bias, a pulsed DC, a pulsed DC bias, or the like may be used.

[0065] As the reactive gas, O2 gas, H2O gas, N2 gas, or the like may be used.

[0066] The sputtering gas pressure is appropriately adjusted so that the characteristics of each layer are optimized, but it is usually in the range of about 0.1 Pa to 30 Pa.

[0067] Thereafter, a second magnetic layer 32 is formed on the surface of the first magnetic layer 31 (second magnetic layer formation step).

[0068] As the method for forming the second magnetic layer 32, similar to the method for forming the first magnetic layer 31, it can be formed by a sputtering method using a target containing the material for forming the second magnetic layer 32.

[0069] As the target containing the material for forming the second magnetic layer 32, the same target as the target containing the material for forming the first magnetic layer 31 can be used.

[0070] The sputtering conditions can be the same as the sputtering conditions of the first magnetic layer 31.

[0071] Next, as shown in FIG. 1, a protective layer 40 is formed on the surface of the magnetic layer 30 (protective layer formation step).

[0072] As a method for forming the protective layer 40, there is no particular limitation. For example, an RF-CVD (Radio Frequency-Chemical Vapor Deposition) method in which a raw material gas composed of 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, 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, and the like can be mentioned.

[0073] Furthermore, a lubricant layer 50 may be formed on the surface of the protective layer 40 by using a general coating method or the like (formation step of the lubricant layer).

[0074] The method for manufacturing a magnetic recording medium according to this embodiment includes a step of forming an MgO underlayer and a step of forming a magnetic layer. In the step of forming the MgO underlayer, an MgO target containing MgO is heated to 600°C or higher to form the MgO underlayer 21. Thereby, it is possible to suppress the generation of sputter dust due to the MgO target in the chamber of the sputtering apparatus when forming the MgO underlayer 21. As a result, the MgO underlayer 21 can be formed in a state with high crystal orientation and few defects. When the O1s spectrum peak of the MgO contained in the obtained MgO underlayer 21 is measured by XPS, it is detected within the range of 531 eV to 533 eV. From this measurement result by XPS, the obtained MgO underlayer 21 is (100)-oriented and has high crystal orientation. When an FePt alloy is used as the magnetic layer 30, the (001) plane is used as the crystal orientation plane of the magnetic layer 30. Therefore, by enhancing the crystal orientation of the MgO underlayer 21, the crystal orientation of the magnetic layer 30 formed on its surface can be enhanced. In addition, by increasing the crystal orientation, defects generated in the magnetic layer 30 can be reduced. Therefore, according to the method for manufacturing a magnetic recording medium according to this embodiment, a magnetic recording medium 1 having a magnetic layer 30 with high crystal orientation and few defects can be manufactured.

[0075] That is, when the first magnetic layer 31 or the second magnetic layer 32 included in the magnetic layer 30 contains a FePt alloy, the (001) plane is used as the crystal orientation plane of the magnetic layer 30. And, the MgO included in the MgO underlayer 21 is (100)-oriented. Since the (100) plane of the MgO included in the MgO underlayer 21 has a high lattice matching with the (001) plane of the FePt alloy having the L10 structure included in the magnetic layer 30, by forming the magnetic layer 30 containing the FePt alloy on the MgO underlayer 21, the magnetic layer 30 containing the FePt alloy is easily (001)-oriented. Therefore, by enhancing the crystal orientation property of the MgO underlayer 21 and reducing defects, the crystal orientation property of the magnetic layer 30 formed on its surface can be enhanced and the defects can be reduced.

[0076] In the manufacturing method of the magnetic recording medium according to the present embodiment, in the step of forming the MgO underlayer, even if a target containing MgO at a high density is not manufactured as the sputtering target, an MgO underlayer 21 with enhanced crystal orientation property and suppressed generation of defects can be formed. Therefore, according to the manufacturing method of the magnetic recording medium according to the present embodiment, an MgO underlayer 21 with high crystal orientation property and few defects can be formed using the conventional target containing MgO.

[0077] In the manufacturing method of the magnetic recording medium according to the present embodiment, in the step of forming the MgO underlayer, the MgO underlayer 21 can be formed by heating a target containing MgO to 800 °C or higher. Thereby, the crystal orientation property of the MgO underlayer 21 can be more reliably enhanced and the defects can be reduced. Therefore, the crystal orientation property of the magnetic layer 30 formed on its surface can be more reliably enhanced and the defects generated in the magnetic layer 30 can be reduced. Therefore, according to the manufacturing method of the magnetic recording medium according to the present embodiment, the magnetic recording medium 1 can have a magnetic layer 30 with higher crystal orientation property and fewer defects.

[0078] The method for manufacturing a magnetic recording medium according to this embodiment can include at least one of an FePt alloy and a CoPt alloy having an L10 structure in the magnetic layer 30. Both the FePt alloy and the CoPt alloy are high Ku materials on the order of 1×10 6 J / m 3 . Therefore, by using at least one of the FePt alloy and the CoPt alloy as the material constituting the magnetic layer 30, the magnetic particles constituting the magnetic layer 30 can be refined, for example, until the particle size becomes 6 nm or less while maintaining the thermal stability. Thus, when the thermal assist recording method is used as the recording method, the magnetic layer 30 can have a coercive force of several tens of kOe at room temperature, and magnetic information can be easily recorded on the magnetic layer 30 by the recording magnetic field of the magnetic head.

[0079] In addition, the magnetic layer 30 including at least one of the FePt alloy and the CoPt alloy can use the (001) plane as the crystal orientation plane. Since the MgO underlayer 21 is (100)-oriented, the lattice matching between the (100) plane of MgO or CoPt and the (001) plane of the FePt alloy is high, so the crystal orientation of the magnetic layer 30 is easily enhanced. Therefore, according to the method for manufacturing a magnetic recording medium according to this embodiment, the magnetic recording medium 1 can have a magnetic layer 30 with higher crystal orientation and fewer defects.

[0080] [Magnetic storage device] A magnetic storage device using the magnetic recording medium according to this embodiment will be described. The magnetic storage device according to this embodiment is not particularly limited in form as long as it has the magnetic recording medium according to this embodiment. Here, a case where the magnetic storage device records magnetic information on the magnetic recording medium using the thermal assist recording method will be described.

[0081] The magnetic storage device according to this embodiment can include, for example, a magnetic recording medium drive unit for rotating the magnetic recording medium according to this embodiment, a magnetic head provided with a near-field light generation element at the tip, a magnetic head drive unit for moving the magnetic head, and a recording and reproducing signal processing unit.

[0082] Further, the magnetic head has, for example, a laser light generation unit for heating a magnetic recording medium, and a waveguide for guiding the laser light generated from the laser light generation unit to a near-field light generation element.

[0083] FIG. 7 is a perspective view showing an example of a magnetic storage device using the magnetic recording medium according to the present embodiment. As shown in FIG. 7, the magnetic storage 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 generation element at its tip, a magnetic head driving unit 104 for moving the magnetic head 103, and a recording / reproducing signal processing unit 105. The magnetic recording medium 101 uses the magnetic recording medium 1 according to the above-described present embodiment.

[0084] FIG. 8 is a schematic diagram showing an example of the magnetic head 103. As shown in FIG. 8, the magnetic head 103 includes a recording head 110 and a reproducing head 120.

[0085] The recording head 110 includes a main magnetic pole 111, an auxiliary magnetic pole 112, a coil 113 for generating a magnetic field, a laser diode (LD) 114 which is a laser light generation unit, and a waveguide 116 for transmitting the laser light L generated from the LD 114 to the near-field light generation element 115.

[0086] The reproducing head 120 includes a shield 121 and a reproducing element 122 sandwiched by the shield 121.

[0087] As shown in FIG. 3, in the magnetic storage device 100, the center of the magnetic recording medium 101 is attached to the rotation axis of the spindle motor, and while the magnetic head 103 floats and travels on the surface of the magnetic recording medium 101 rotationally driven by the spindle motor, information is written or read to / from the magnetic recording medium 101.

[0088] In the magnetic storage device 100 according to the present embodiment, by using the magnetic recording medium 1 according to the present embodiment for the magnetic recording medium 101, the magnetic recording medium 101 can be made to have a higher recording density, so that the recording density can be increased.

Example

[0089] Hereinafter, embodiments will be specifically described by showing examples and comparative examples, but the embodiments are not limited to these examples and comparative examples.

[0090] <Example 1> [Manufacture of Magnetic Recording Medium] A magnetic recording medium was manufactured by the following method.

[0091] On a heat-resistant glass substrate, a 50 nm thick 50 atomic% Cr - 50 atomic% Ti alloy film (third underlayer) and a 25 nm thick 75 atomic% Co - 20 atomic% Ta - 5 atomic% B alloy film (soft magnetic underlayer) were formed in this order. Next, after heating the substrate to 250 °C, a 10 nm thick Cr film (second underlayer) was formed. At this time, a DC magnetron sputtering apparatus (C-3040, manufactured by Anelva Corporation) was used for forming the third underlayer, the soft magnetic underlayer, and the second underlayer.

[0092] Next, using an RF sputtering apparatus, an MgO underlayer which is the first underlayer was formed. Specifically, an MgO target with a relative density of 85% and a diameter of 120 mm was used, the target temperature was set to 1000 °C, the input power was 1 kW, the sputtering gas was Ar, and the sputtering gas pressure was 3 Pa, and discharge was carried out for 12 seconds to form a 2 nm thick MgO film.

[0093] Next, after heating the substrate to 520 °C, a 3 nm thick 60 mol% (52 at% Fe - 48 at% Pt) - 40 mol% C film (first magnetic layer) and a 5 nm thick 82 mol% (52 at% Fe - 48 at% Pt) - 18 mol% SiO2 film (second magnetic layer) were formed in this order. At this time, a DC magnetron sputtering apparatus (C-3040, manufactured by Anelva Corporation) was used for forming the first magnetic layer and the second magnetic layer.

[0094] Next, using the ion beam method, a 3 nm thick carbon film was formed as a protective layer, and then a perfluoropolyether film was formed as a lubricant layer by the coating method to obtain a magnetic recording medium.

[0095] ((001) orientation of the magnetic layer) Using an X-ray diffractometer (manufactured by Philips), the X-ray diffraction spectrum of the substrate after forming the second magnetic layer was measured, and the full width at half maximum of the (200) peak of the FePt alloy was determined.

[0096] The (001) orientation of the second magnetic layer was evaluated using the full width at half maximum of the (200) peak of the FePt alloy having the L10 structure contained in the second magnetic layer. Here, the (001) peak of the FePt alloy does not have a sufficiently large appearance angle 2θ. Therefore, even if the low angle side is expanded to the measurement limit when measuring the rocking curve, the intensity of the (001) peak of the FePt alloy is not stable compared to the case where there is no peak, and it is difficult to analyze the full width at half maximum. Due to such measurement reasons, it is difficult to evaluate the (001) orientation of the magnetic layer using the full width at half maximum of the (001) peak of the FePt alloy. On the other hand, the (200) peak of the FePt alloy appears when the FePt alloy is (001) oriented, and since the appearance angle 2θ is sufficiently large, it is suitable for evaluating the (001) orientation of the magnetic layer.

[0097] The evaluation results of the full width at half maximum of the (200) peak of the FePt alloy are shown in Table 1. Also, the yield when manufacturing 1000 magnetic recording media under the same conditions as above was evaluated using an error tester. The evaluation results are shown in Table 1.

[0098] <Examples 2 to 3, Comparative Example 1> In Example 1, it was carried out in the same manner as in Example 1 except that the heating temperature of the MgO target during the formation of the MgO underlayer was changed to the temperature shown in Table 1. The evaluation results of the full width at half maximum of the (200) peak of the FePt alloy and the yield when manufacturing 1000 magnetic recording media under the same conditions in each example and comparative example are shown in Table 1.

[0099]

Table 1

[0100] From Table 1, in Examples 1 to 3, the yield when manufacturing 1000 magnetic recording media was 98.7% or more. On the other hand, in Comparative Example 1, the yield when manufacturing 1000 magnetic recording media was 98.1%.

[0101] Examples 1 to 3, different from Comparative Example 1, by forming the MgO underlayer at a MgO target temperature of 600°C or higher when forming the MgO underlayer and manufacturing the magnetic recording medium, it was confirmed that the orientation of the second magnetic layer can be enhanced and the yield can be improved. Therefore, according to the method for manufacturing a magnetic recording medium according to this embodiment, it can be said that the magnetic recording medium can be manufactured with high efficiency.

[0102] As described above, the embodiments have been explained. However, the above embodiments are presented as examples, and the present invention is not limited by the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, replacements, changes, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0103] 1, 101 Magnetic recording medium 10 Substrate 20 Underlayer 21 Magnesium oxide (MgO) underlayer (first underlayer) 22 Second underlayer 30 Magnetic layer 31 First magnetic layer 32 Second magnetic layer 100 Magnetic storage device

Claims

1. forming a magnesium oxide underlayer on a surface of a substrate by a sputtering method using a target containing magnesium oxide; forming a magnetic layer on a surface side of the magnesium oxide underlayer; Including, The method for producing a magnetic recording medium, wherein a target containing the magnesium oxide is heated to 600° C. or higher when the magnesium oxide underlayer is formed.

2. 2. The method for producing a magnetic recording medium according to claim 1, wherein the target containing magnesium oxide is heated to 800[deg.] C. or higher.

3. The magnetic layer is L1 ０ 3. The method for producing a magnetic recording medium according to claim 1, wherein the magnetic recording medium contains at least one of an FePt alloy and a CoPt alloy having the structure.

4. a magnesium oxide underlayer containing magnesium oxide; L1 ０ a magnetic layer including an FePt alloy having a structure; Equipped with The magnesium oxide has an O1s spectrum peak of 531 eV to 533 eV when measured by X-ray photoelectron spectroscopy.

5. A magnetic storage device comprising the magnetic recording medium according to claim 4.

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