JP2011090731A - Method for manufacturing magnetic recording medium and magnetic recording medium, and magnetic recording and playing back device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium by which a magnetic recording medium with high recording density is obtained without blurring of a pattern on a magnetic layer, which can be a simple and convenient manufacturing process, and by which manufacturing is conducted with high productivity and a high yield, and to provide the magnetic recording medium and a magnetic recording and playing back device. <P>SOLUTION: The method for manufacturing the magnetic recording medium has: a step (A) to form the magnetic layer 2 on a nonmagnetic substrate 1; steps (B)-(D) to form a radiation reactive layer 3 which is patterned for the purpose of forming a magnetic recording pattern on the magnetic layer 2; a step (E) to generate an acid or a base from the radiation reactive layer 3 by irradiating the radiation reactive layer 3 with a radiation R; and a step (F) to make the acid or the base generated from the radiation reactive layer 3 react with the magnetic layer 2 to modify magnetic characteristics of the site 21 in this order. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a magnetic recording medium used in a magnetic recording / reproducing apparatus such as a hard disk device, a magnetic recording medium, and a magnetic recording / reproducing apparatus.

  In recent years, the application range of magnetic recording devices such as magnetic disk devices, flexible disk devices, and magnetic tape devices has been remarkably increased, and the importance has increased, and the recording density of magnetic recording media used in these devices has been significantly improved. Is being planned. In particular, since the introduction of MR head and PRML technology, the increase in surface recording density has become more intense, and in recent years GMR heads, TMR heads, etc. have also been introduced and continue to increase at a pace of about 1.5 times a year. ing.

  For these magnetic recording media, it is required to achieve higher recording density in the future, and it is required to achieve higher coercivity of the magnetic layer, higher signal-to-noise ratio (SNR) and higher resolution. Yes. In recent years, efforts have been made to improve the surface recording density by increasing the track density at the same time as improving the linear recording density. In particular, in the latest magnetic recording apparatus, the track density has reached 250 kTPI.

  In order to increase the surface recording density of the magnetic recording medium, it is necessary to reduce the pitch between tracks or bits and also reduce the groove spacing. However, as the track density is increased, magnetic recording information between adjacent tracks interferes with each other, and the problem that the magnetization transition region in the boundary region becomes a noise source and the SNR is easily lost. This directly deteriorates the bit error rate, which is an obstacle to the improvement of recording density. Therefore, in order to realize a magnetic recording medium having a high density and a high bit error rate, it is required to increase the signal intensity as much as possible at the same pitch, and the width (area) of the signal recording portion, that is, the land portion. It is required to have a pattern structure that widens the width and narrows the groove.

Also, in order to increase the linear recording density of a magnetic recording medium, it is necessary to increase the coercive force and thermal stabilization of the medium. To that end, it is essential to increase the anisotropic magnetic field of the magnetic material in the recording layer. is there. Correspondingly, it is necessary to increase the recording magnetic field by the head.
However, when the magnetic field of magnetic recording is increased and a magnetic force is applied to a minute region, crosstalk to adjacent tracks increases, and noise increases accordingly, so that the track density is increased. There is a problem that is difficult. For this reason, in a high-density magnetic recording / reproducing apparatus (hard disk device), discrete track type and bit patterned type magnetic recording media have been developed, and cross-track or bit-to-bit magnetic materials are removed or reduced to reduce cross It has been proposed to suppress talk. The above-mentioned discrete track type improves the track density by forming irregularities along the track on the surface of the magnetic recording medium and physically separating the recording tracks, so that thermal stabilization, SNR, or sufficient output is achieved. It is a technology to ensure. As another method for manufacturing a magnetic recording medium, a part of a magnetic layer is processed by ion milling to form a magnetic recording pattern, and the processed portion is filled with a nonmagnetic material to smooth the surface. There is also.

  As an example of the above-described discrete track type recording medium, a magnetic recording medium and a servo signal pattern that are physically separated are formed by forming a magnetic recording medium on a nonmagnetic substrate having a concavo-convex pattern formed on the surface. It is known to manufacture such a magnetic recording medium (see, for example, Patent Document 1). According to Japanese Patent Laid-Open No. 2004-228688, a technique is provided in which a ferromagnetic layer is formed on the surface of a substrate having a plurality of irregularities on the surface via a soft magnetic layer, and a protective film is formed on the surface. In the magnetic recording medium thus obtained, a magnetic recording area physically separated from the periphery is formed in the convex area. According to Patent Document 1, it is possible to form a high-density magnetic recording medium with less noise because it is possible to suppress the occurrence of domain walls in the soft magnetic layer, and thus it is difficult for thermal fluctuations to occur and there is no interference between adjacent signals. ing.

  In addition, as a method of manufacturing a discrete track type magnetic recording medium, for example, a method of forming a track after forming a magnetic recording medium composed of several thin films, a method for forming a track directly on a substrate surface in advance or for forming a track. There is a method of forming a thin film of a magnetic recording medium after forming an uneven pattern on the thin film layer (see, for example, Patent Documents 2 and 3).

  Also, the magnetic track area of the discrete track medium is formed by injecting ions such as nitrogen and oxygen into a pre-formed magnetic layer or irradiating a laser to change the magnetic characteristics of the part. (For example, refer to Patent Documents 4 to 6).

  As a process for manufacturing a conventional magnetic recording medium, for example, as shown in FIGS. 3A to 3J, a mask layer 103 is first formed on a magnetic layer 102 and then a resist is formed thereon. A layer 104 is formed, and pattern transfer is performed on the resist layer 104 using a stamper 105. Then, after processing the mask layer 103 using this pattern, the magnetic layer 102 is processed and modified to remove the mask layer 103, and if necessary, the recess formed on the surface of the magnetic layer 102 by etching is removed. A method of flattening the unevenness by embedding the nonmagnetic material 105 is employed.

JP 2004-164692 A JP 2004-178793 A JP 2004-178794 A Japanese Patent Laid-Open No. 5-205257 JP 2006-209952 A JP 2006-309841 A

  However, in the conventional manufacturing process as shown in FIGS. 3A to 3J, the number of processes is large as described above, and control is complicated because there are many parameters to be set. As explained, there was a problem that control became difficult.

  First, in the above manufacturing process, the mask layer 103 is used for processing because the pattern of the resist layer 104 alone is insufficient in shielding the milling ions when the magnetic layer 102 is processed. However, when the number of layers such as the mask layer 103 is increased, not only the process becomes complicated, but also the edge portion of the pattern of the magnetic layer 102 is removed in the mask removing process after the magnetic layer 102 is processed. For this reason, the edge portion of the magnetic layer 102 is rounded, and the pattern of the magnetic layer 102 is blurred and unclear.

  Here, in the conventional manufacturing process as shown in FIGS. 3A to 3J, the edge portion of the resist layer 104 having the transfer pattern shown in FIG. 3B is the sharpest. It can be seen that the edge portion is gradually rounded and the pattern becomes blurred and unclear as the number of steps increases. In particular, in the removal process of the mask layer 103 between the steps of FIGS. 3D to 3F, the edge of the magnetic layer 102 is also removed, so that the rectangularity of the magnetic recording portion is reduced, and from that location. There is a problem that the error rate is reduced due to a decrease in the number of signals.

  Further, since the manufacturing process is complicated, there are problems that the number of parameters for controlling each process increases and the control becomes difficult and the manufacturing yield decreases. Further, in the embedding process for flattening the unevenness generated in the magnetic layer 102 after that, it is necessary to form an embedding material having a film thickness of at least twice the film thickness of the magnetic layer 102. There was a problem of more than double. In the subsequent flattening step, it is difficult to completely flatten the surface of the magnetic layer, and there is a problem that the flying characteristics of the magnetic head deteriorate due to the unevenness remaining on the surface. In addition, there is a big problem that the manufacturing cost is increased due to the above-described problems in the manufacturing process.

The present invention has been made in view of the above problems, and a magnetic recording medium having a high recording density can be obtained without blurring the pattern of the magnetic layer, and a simple manufacturing process can be achieved with high productivity. An object of the present invention is to provide a method of manufacturing a magnetic recording medium that can be manufactured with a high yield.
It is another object of the present invention to provide a magnetic recording medium obtained by the production method of the present invention, having excellent recording / reproducing characteristics and capable of handling a high recording density.
It is another object of the present invention to provide a magnetic recording / reproducing apparatus including the magnetic recording medium of the present invention and having excellent high recording density characteristics.

The present inventors have conducted intensive research to solve the above problems. As a result, an acid generation layer is formed on the surface of the magnetic layer, and the separation region portion of the magnetic recording pattern is imprinted on the acid generation layer with a stamper, and then the excess portion of the acid generation layer is wet etched (or dry etching). Next, the acid generation layer is irradiated with reaction light to generate an acid, and the acid reacts with the magnetic layer to modify the magnetic properties of the part, and then the acid after reaction by wet etching or the like It has been found that by using the method for removing the generation layer, it is possible to form a clear pattern without scraping the edge of the magnetic layer, and the present invention has been completed.
That is, the present invention adopts the following configuration.

  [1] A method for manufacturing a magnetic recording medium having a magnetically separated magnetic recording pattern, the method comprising: forming a magnetic layer on a nonmagnetic substrate; and forming the magnetic recording pattern on the magnetic layer Forming a patterned radiation reaction layer; irradiating the radiation reaction layer with radiation; generating an acid or base from the radiation reaction layer; acid or base generated from the radiation reaction layer; and the magnetic layer; And a step of modifying the magnetic properties of the reaction site in this order.

[2] The radiation reaction layer contains a radiation decomposable compound, and the radiation decomposable compound generates an acid or a base as a decomposition product upon irradiation with radiation, or the generated decomposition product is separated from other substances. The method for producing a magnetic recording medium according to the above [1], which is a substance that reacts to generate an acid or a base.
[3] The magnetic recording medium according to the above [1] or [2], wherein the radiation reaction layer is formed of a photoacid generator, and ultraviolet rays or heat rays are used as radiation applied to the radiation reaction layer. Production method.
[4] The method for producing a magnetic recording medium according to any one of [1] to [3], wherein a nanoimprint method is used in the step of forming the patterned radiation reaction layer.
[5] The method for manufacturing a magnetic recording medium according to the above [4], wherein after the nanoimprint is applied to the radiation reaction layer, the radiation reaction layer is subjected to wet etching to form a patterned radiation reaction layer. .

[6] The photoacid generator includes cyclohexylsulfonyl diazomethane, t-butylsulfonyl diazomethane, p-toluenesulfonyl diazomethane, a mixture of triphenylsulfonium and trifluoronetane sulfonate, diphenyl-4-methylphenyl sulfonate. The above-mentioned [3, which contains at least one of a mixture of phonium and trifluoromethane sulfonate and a mixture of diphenyl-2,4,6-trimethylphenyl sulfonate and p-toluene sulfonate. ] The manufacturing method of the magnetic-recording medium of any one of [5].
[7] Any one of the above [1] to [6], wherein after the step of modifying the magnetic properties of the magnetic layer, the radiation reaction layer after reaction with radiation is removed by wet cleaning. A method for producing the magnetic recording medium according to 1.

[8] A magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to any one of [1] to [7].
[9] A magnetic recording / reproducing apparatus comprising at least the magnetic recording medium according to [8] above and a magnetic head for recording / reproducing information on / from the magnetic recording medium.

  According to the method for producing a magnetic recording medium of the present invention, a step of forming a magnetic layer on a nonmagnetic substrate, a step of forming a patterned radiation reaction layer for forming a magnetic recording pattern on the magnetic layer, Irradiating the radiation reaction layer with radiation to generate an acid or base from the radiation reaction layer, and reacting the acid or base generated from the radiation reaction layer with the magnetic layer to modify the magnetic properties of the reaction site By having the steps in this order, the magnetic recording portion and the nonmagnetic portion having a clear pattern can be formed without cutting the edge portion of the magnetic layer, so that the corrosion resistance is improved, and the productivity and the yield are improved. . In addition, since the pattern of the radiation reaction layer can be accurately controlled only by the etching processing time, the width of the magnetic recording portion can be formed wide, and a high signal error and a high bit error rate are ensured. A magnetic recording medium can be manufactured. Therefore, it is possible to significantly reduce the manufacturing cost with a simple process, and to manufacture a magnetic recording medium having a high recording density with high productivity and high yield.

Further, according to the magnetic recording medium of the present invention, since it is a magnetic recording medium obtained by the production method of the present invention, a magnetic recording medium having excellent recording / reproducing characteristics and capable of dealing with a high recording density can be realized.
In addition, since the magnetic recording / reproducing apparatus of the present invention includes the magnetic recording medium of the present invention, a magnetic recording / reproducing apparatus excellent in high recording density characteristics can be realized.

It is a figure which illustrates typically the manufacturing method and magnetic recording medium of a magnetic recording medium which concern on this invention, and is sectional drawing which shows each process of forming each layer on a nonmagnetic substrate. 1 is a schematic view schematically showing a magnetic recording / reproducing apparatus using a magnetic recording medium according to the present invention. It is a schematic cross-sectional view showing each step of a conventional method for manufacturing a magnetic recording medium.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a method for manufacturing a magnetic recording medium, a magnetic recording medium, and a magnetic recording / reproducing apparatus according to the invention will be described with reference to the accompanying drawings.
1A to 1H are cross-sectional views schematically illustrating each step of the magnetic recording medium manufacturing method of the present embodiment and the magnetic recording medium obtained thereby, and FIG. It is the schematic explaining typically an example of the magnetic recording / reproducing apparatus provided with a magnetic recording medium. The drawings to be referred to in the following description are drawings for explaining a method of manufacturing a magnetic recording medium, a magnetic recording medium, and a magnetic recording / reproducing apparatus, and the size, thickness, dimensions, and the like of each part shown in the drawings are as follows. This is different from the dimensional relationship of an actual magnetic recording medium or the like.

  In the method of manufacturing the magnetic recording medium 10 of the present embodiment, a step of forming the magnetic layer 2 on the nonmagnetic substrate 1 and a patterned radiation reaction layer 3 for forming a magnetic recording pattern on the magnetic layer 2 are formed. A step of irradiating the radiation reaction layer 3 with radiation to generate an acid or a base from the radiation reaction layer 3, a reaction of the acid or base generated from the radiation reaction layer 3 with the magnetic layer 2, and the reaction And a step of modifying the magnetic properties of the portions in this order.

[Magnetic recording medium]
The magnetic recording medium 10 obtained by the manufacturing method of this embodiment will be described in detail using the schematic cross-sectional view shown in FIG. 1 (H) and the example of the magnetic recording / reproducing apparatus 50 shown in FIG. FIG. 1 is a longitudinal sectional view showing a process of forming each layer on a nonmagnetic substrate 1 and a layer structure of a magnetic recording medium 10 obtained thereby.
Further, the magnetic recording medium 10 of the present embodiment has a magnetic recording pattern (not shown) that is magnetically separated on the nonmagnetic substrate 1, and has a substantially donut-shaped plate shape in plan view (FIG. 2 (see reference numeral 10 in the magnetic recording / reproducing apparatus 50 in FIG. 2).

  As shown in FIG. 1H, the magnetic recording medium 10 of the present embodiment is schematically configured by sequentially laminating a magnetic layer 2 having a magnetic pattern and a protective layer 9 on a nonmagnetic substrate 1. The Further, the magnetic recording medium 10 of the example described in the present embodiment is not illustrated in detail, but a lower layer composed of, for example, a soft magnetic layer or an orientation control layer between the nonmagnetic substrate 1 and the magnetic layer 2. It is also possible to adopt a configuration in which a ground layer and an intermediate layer are arranged and a lubricating layer is provided on the protective layer 9. Among these layers, layers other than the nonmagnetic substrate 1 and the magnetic layer 2 can be appropriately selected and provided.

  The magnetic recording medium 10 includes a magnetic layer 2 that is magnetized in a direction perpendicular to the non-magnetic substrate 1, and includes a magnetic head 57 including a read head and a write head (the magnetic recording / reproducing apparatus in FIG. 2). 50), information signals are written to and read from a magnetic recording pattern (not shown).

  As the nonmagnetic substrate 1, for example, a metal substrate made of a metal material of aluminum or an aluminum alloy such as an Al—Mg alloy can be used, and glass, ceramic, silicon, silicon carbide, titanium, carbon, various resins can be used. For example, a nonmagnetic substrate made of a nonmetallic material may be used.

Examples of the glass substrate used for the nonmagnetic substrate 1 include amorphous glass and crystallized glass. Of these, general-purpose soda lime glass and aluminosilicate glass can be used as the amorphous glass, and lithium crystallized glass can be used as the crystallized glass. Further, as the ceramic substrate, a sintered body mainly composed of general-purpose aluminum oxide, aluminum nitride, silicon nitride, or the like, or a fiber reinforced material thereof can be used. Further, as the nonmagnetic substrate 1, it is possible to use a metal substrate or a nonmetal substrate having the NiP layer or the NiP alloy layer formed on the surface of the nonmagnetic substrate by using a plating method or a sputtering method. .
As the nonmagnetic substrate 1 used in the present embodiment, among the above materials, a substrate made of an aluminum alloy, crystallized glass, or silicon is preferably used.

The nonmagnetic substrate 1 preferably has an average surface roughness Ra of 1 nm (10 Å) or less, more preferably 0.5 nm (5 Å) or less in high recording density recording with a magnetic head flying low.
Further, the non-magnetic substrate 1 has a surface micro-waviness (Wa) of 0.3 nm or less, more preferably 0.25 nm or less, as described above, which is suitable for high recording density recording with a magnetic head flying low. is there.

Further, the nonmagnetic substrate 1 uses a chamfered portion of the chamfer portion at the end face and a surface average roughness Ra of at least one of the side surface portions of 10 nm or less, more preferably 9.5 nm or less. This is preferable from the viewpoint of the flight stability of the magnetic head.
Here, the fine waviness (Wa) described in the present embodiment is, for example, a surface roughness measuring device (model number: P-1; manufactured by KLM-Tencor), and the surface average roughness in a measurement range of 80 μm. Can be measured.

  It is more preferable to provide an adhesion layer on the surface of the nonmagnetic substrate 1, that is, on the magnetic layer 2 side. When the nonmagnetic substrate 1 and a soft magnetic layer (underlayer) (not shown) mainly composed of Co or Fe are in direct contact with each other, the influence of adsorbed gas, moisture on the surface of the nonmagnetic substrate 1 or diffusion of substrate components Therefore, there is a possibility that the corrosion proceeds. In order to suppress the progress of such corrosion, it is preferable to provide an adhesion layer on the nonmagnetic substrate 1. As a material constituting the adhesion layer, for example, Cr, Cr alloy, Ti, Ti alloy and the like can be appropriately selected, and the thickness is preferably 30 mm or more.

  The soft magnetic layer increases the direction component of the magnetic flux generated from the magnetic head in the direction perpendicular to the nonmagnetic substrate, and the magnetization direction of the magnetic layer 2 on which information is recorded is more strongly perpendicular to the nonmagnetic substrate 1. It can be provided for the purpose of fixing in any direction. The action obtained by providing such a soft magnetic layer is preferable because it becomes more remarkable particularly when a single magnetic pole head for perpendicular recording is used as a magnetic head for magnetic recording and reproduction. As such a soft magnetic layer, a soft magnetic material, for example, a material containing Fe, Ni, or Co can be used.

  An orientation control layer (not shown) can be provided on the soft magnetic layer. By providing this orientation control layer, it is possible to refine the crystal grains of the magnetic layer 2 and improve the recording / reproducing characteristics. The material constituting the orientation control layer is not particularly limited, but for example, a material having an hcp structure, an fcc structure, or an amorphous structure is preferable. In particular, Ru-based alloys, Ni-based alloys, Co-based alloys, Pt-based alloys, and Cu-based alloys are particularly preferable, and these alloys may be used in a multilayered manner. Moreover, since the surface shape of the orientation control layer affects the orientation and the surface shape of the magnetic layer 2, it is preferable to have an optimum surface shape and appropriate roughness.

It is more preferable to provide a nonmagnetic intermediate layer (not shown) between the orientation control layer and the magnetic layer 2 described later. In the initial portion of the magnetic layer 2 immediately above the orientation control layer, disorder of crystal growth is likely to occur, which causes noise. The occurrence of noise can be suppressed by replacing the initial portion of the magnetic layer 2 in which the disorder of crystal growth has occurred with a nonmagnetic intermediate layer. As such an intermediate layer, for example, it is preferable to employ a material containing Co as a main component and further containing an oxide. The oxide constituting the intermediate layer is preferably an oxide of Cr, Si, Ta, Al, Ti, Mg, Co, and particularly preferably TiO ₂ , Cr ₂ O ₃ , and SiO _2. .

The magnetic layer 2 is a magnetic recording layer provided on the nonmagnetic substrate 1, and is formed, for example, on an underlayer or an intermediate layer provided as appropriate on the nonmagnetic substrate 1 as described above.
The magnetic layer 2 provided in the magnetic recording medium 10 of the present embodiment may be either an in-plane magnetic layer or a perpendicular magnetic layer. However, in order to achieve a higher recording density, a perpendicular magnetic layer is used. It is preferable.

The magnetic layer 2 is preferably formed from an alloy mainly composed of Co.
As the magnetic layer 2 for the in-plane magnetic recording medium, for example, a laminated structure composed of a nonmagnetic CrMo underlayer and a ferromagnetic CoCrPtTa magnetic layer can be used. Examples of the magnetic layer 2 for perpendicular magnetic recording media include soft magnetic FeCo alloys (FeCoB, FeCoSiB, FeCoZr, FeCoZrB, FeCoZrBCu, etc.), FeTa alloys (FeTaN, FeTaC, etc.), Co alloys (CoTaZr, CoZrNB, CoB, etc.), an orientation control film such as Pt, Pd, NiCr, NiFeCr, an intermediate film such as Ru, and a 60Co-15Cr-15Pt alloy or a 70Co-5Cr-15Pt-10SiO ₂ alloy. It is possible to use a laminated magnetic layer.

  The perpendicular coercive force (Hc) of the magnetic layer 2 is preferably 3000 [Oe] or more. If the perpendicular coercive force of the magnetic layer 2 is less than 3000 [Oe], the recording / reproducing characteristics, particularly the frequency characteristics, and the thermal fluctuation characteristics also deteriorate, which is not preferable as a high-density recording medium.

  Moreover, it is preferable that the reverse domain nucleation magnetic field (-Hn) of the magnetic layer 2 is 1500 [Oe] or more. If the reverse domain nucleation magnetic field (-Hn) of the magnetic layer 2 is less than 1500 [Oe], it is not preferable because the thermal fluctuation resistance is poor.

  The magnetic layer 2 preferably has an average particle diameter of 3 to 12 nm. This average particle diameter can be obtained, for example, by observing the magnetic layer 2 with a TEM (transmission electron microscope) and image-processing the observed image.

  The lower limit of the total thickness of the magnetic layer 2 is preferably 3 nm, and more preferably 5 nm. Further, the upper limit of the thickness of the magnetic layer 2 is preferably 20 nm, and more preferably 15 nm. If the thickness of the magnetic layer 2 is less than the above, sufficient reproduction output cannot be obtained, and the thermal fluctuation characteristics are also deteriorated. On the other hand, if the thickness of the magnetic layer 2 exceeds the above range, the magnetic particles in the perpendicular magnetic layer are enlarged, and noise during recording / reproduction increases, which is represented by the S / N ratio and recording characteristics (OW). Recording / reproduction characteristics are deteriorated.

  The magnetic layer 2 may be formed with a film thickness that can provide sufficient head input / output in accordance with the type of magnetic alloy used, the laminated structure, and the like. The film thickness of the magnetic layer 2 needs to be a certain thickness or more in order to obtain a certain level of output during reproduction. On the other hand, each parameter indicating the recording / reproduction characteristics deteriorates as the output increases. Therefore, it is necessary to set an optimum film thickness.

  The magnetic layer 2 provided in the magnetic recording medium 10 of the present invention is provided in a manufacturing method described later, and includes a step (E) of generating an acid or a base by irradiating the patterned radiation reaction layer 3 with radiation R, and these The magnetism separated by the non-magnetized or weakly magnetized region 21 in each step (F) of reacting the acid or base with the magnetic layer 2 and modifying the magnetic properties of the reaction site (region 21). A recording pattern is formed.

The magnetic recording medium according to the present invention is not limited to the example shown in FIG. 1H, and the magnetic layer 2 can be configured as a multilayer film composed of a plurality of magnetic layers. For example, the magnetic layer 2 may have a multilayer film structure including a lower magnetic layer, an intermediate magnetic layer, and an upper magnetic layer (not shown). In this case, it is more preferable to provide a nonmagnetic layer between the layers. .
Further, when the magnetic layer 2 is composed of a plurality of magnetic layers, the lower magnetic layer on the nonmagnetic substrate 1 side is a magnetic layer having a granular structure, and the upper magnetic layer on the protective layer 9 side described later is non-oxide-free. A magnetic layer having a granular structure is preferable. With such a configuration, it is possible to more easily control and adjust each characteristic such as the thermal stabilization characteristic, the recording characteristic (OW), and the S / N ratio of the magnetic recording medium.

  Further, by providing a nonmagnetic layer between the plurality of magnetic layers constituting the magnetic layer 2, the magnetization reversal of individual films can be facilitated, and the dispersion of the magnetization reversal of the entire magnetic particles can be reduced. Thereby, the S / N ratio of the magnetic recording medium 10 can be further improved. As such a nonmagnetic layer, a material having an hcp structure is preferably used, and examples thereof include a CoCr alloy.

In the magnetic recording medium 10 of the present embodiment, it is preferable to further provide a protective layer 9 on the magnetic layer 2 as shown in FIG. The protective layer 9 prevents corrosion of the magnetic layer 2 and prevents damage to the surface of the medium when the magnetic head (see reference numeral 57 in FIG. 2) contacts the magnetic recording medium. As such a protective layer 9, a conventionally known material can be used. For example, Diamond Like Carbon, carbon (C), hydrogenated carbon (H _x C), nitrogenated carbon (CN), alumocarbon, silicon carbide A carbonaceous layer such as (SiC) or a material containing a commonly used protective film material such as SiO ₂ , Zr ₂ O ₃ , or TiN can be used.

The thickness of the protective layer 9 is preferably in the range of 1 to 10 nm from the viewpoint of high recording density because the distance between the magnetic head and the magnetic recording medium can be reduced. When the thickness of the protective layer exceeds the above range, the distance between the magnetic head and the magnetic layer 2 becomes large, and there is a possibility that a sufficiently strong input / output signal cannot be obtained.
Further, the protective layer 9 may be composed of two or more layers.

  In the magnetic recording medium 10 of this embodiment, as described above, it is more preferable to further form a lubricating layer (not shown) on the protective layer 9. As the lubricant used in the lubricating layer, it is preferable to use a hydrocarbon-based lubricant, a mixture thereof, and the like in addition to a fluorine-based lubricant such as perfluoropolyether, fluorinated alcohol, and fluorinated carboxylic acid. The lubricating layer is usually formed with a thickness of 1 to 4 nm.

  The magnetic recording medium 10 has a magnetic recording pattern (not shown) formed by the magnetic layer 2 in the above-described configuration and is magnetically recorded or reproduced by a magnetic head (see the magnetic head 57 of the magnetic recording / reproducing apparatus 50 shown in FIG. 2). It is set as the structure which can perform. In addition, since the magnetic recording medium 10 of the present embodiment is obtained by the manufacturing method according to the present invention described below, excellent recording / reproduction characteristics are ensured and high recording density can be accommodated.

[Method of manufacturing magnetic recording medium]
Hereinafter, the method for manufacturing the magnetic recording medium of the present embodiment will be described in detail with reference to FIGS. 1A to 1H as appropriate.
As described above, the method for manufacturing the magnetic recording medium 10 of the present embodiment includes the step (A) of forming the magnetic layer 2 on the nonmagnetic substrate 1 and the step of forming the magnetic recording pattern on the magnetic layer 2. Steps (B) to (D) for forming the patterned radiation reaction layer 3, steps (E) for irradiating the radiation reaction layer 3 with radiation R to generate an acid or base from the radiation reaction layer 3, and radiation reaction A step (F) of reacting the acid or base generated from the layer 3 with the magnetic layer 2 and modifying the magnetic properties of the reaction site in this order. In the example shown in FIGS. 1A to 1H, after the step (F), the step (G) of removing the radiation reaction layer 3 after reacting with the radiation R by dry etching, and the magnetic layer The step (H) of covering the surface of 2 with the protective layer 9 is provided in this order.

In the method of manufacturing the magnetic recording medium 10 according to the present invention, conventionally known methods are used for steps other than the steps of forming the magnetic layer 2 and the radiation reaction layer 3 shown in FIGS. be able to. Therefore, in the present embodiment, detailed description of each step of forming the protective layer 9 and the lubricating layer thereon as well as the base layer and intermediate layer (not shown) is omitted.
Hereinafter, each step will be described in detail.

"Process (A)"
First, in step (A), the magnetic layer 2 is formed on the nonmagnetic substrate 1.
Specifically, as shown in FIG. 1A, for example, the above-described alloy containing Co as a main component is deposited on the non-magnetic substrate 1 using a sputtering method to form the magnetic layer 2. To do.
In general, a sputtering method is used as a method of forming the magnetic layer 2, but other known methods can be used as appropriate.

“Processes (B) to (D)”
Next, as shown in FIGS. 1B to 1D, a patterned radiation reaction layer 3 for forming a magnetic recording pattern is formed on the magnetic layer 2 formed in the step (A).

  Specifically, as shown in FIG. 1B, first, as a step (B), the radiation reaction layer 3 is formed on the magnetic layer 2. In the present invention, the method for forming the radiation reaction layer 3 is not particularly declared, and for example, as with the magnetic layer 2, it can be formed by sputtering.

In the present invention, it is preferable to use a material containing a radiation decomposable compound as the radiation reaction layer 3.
Here, the radiation-decomposable compound described in the present invention means that an acid or a base is generated as a decomposition product upon irradiation with radiation, or the generated decomposition product reacts with another substance to form an acid or a base. It is a substance to be generated. That is, by incorporating such a compound into the patterned radiation reaction layer 3, the magnetic particles constituting the magnetic layer 2 and the acid or base are partially reacted to improve the magnetic properties of the reaction site. Thus, a magnetic recording pattern can be easily formed. Therefore, it is possible to remarkably simplify the manufacturing process conventionally used to form the magnetic layer 2 having a clear magnetic recording pattern, and to manufacture the magnetic recording medium 10 with high productivity and high yield. Is possible.

  The radiodegradable compounds described in the present invention are specifically any, as described above, that have any necessary properties, i.e., properties that selectively generate or decompose acids or bases upon exposure to radiation. Compounds can also be used. For example, a mixture of a dipyridyl compound such as 4,4′-dipyridyl compound and a photosensitive cyclopropenone compound such as 1,2-diphenylcyclopropenone, which reacts when heated (when heated). Substances that produce oxoindolizine, trialkylorthoesters such as triethyl orthoformate that are photochemical reactants, dialkylaminophenylethylenes such as 1,1-bis (4′-dialkylamino) phenylethylene and triarylsulfonium, radiation Various trialkylorthoesters such as triethylorthoformate, triethylorthoacetate, trimethylorthobenzoate, etc. that generate near-infrared absorbing materials when exposed to light, such as diarylindonium salts and tria that release strong acids when exposed to radiation Reel sulfonium salt, etc. Or polymers and copolymers of carbon tetrabromide, hexabromoethane, tris (trichloromethyl) triazine, trichloromethylpyrone, and vinyl chloride known to generate hydrogen chloride and other hydrogen halides when exposed to electron beams Halogenated materials such as can be used.

  In the present invention, it is particularly preferable to use a photoacid generator as the radiation-decomposable compound used in the radiation reaction layer 3. This is because magnetic particles are particularly suitable for forming a sharp magnetic recording pattern in a short time because their magnetic properties are easily modified by acid. Examples of such a photoacid generator include cyclohexylsulfonyl diazomethane (manufactured by Wako Pure Chemical Industries, Ltd., WPAG-145), t-butylsulfonyl diazomethane (manufactured by Wako Pure Chemical Industries, Ltd., WPAG-170), p. -Toluenesulfonyl diazomethane (manufactured by Wako Pure Chemical Industries, WPAG-199), a mixture of triphenylsulfonium and trifluoronetane sulfonate (manufactured by Wako Pure Chemical Industries, WPAG-281), diphenyl-4- A mixture of methylphenylsulfonium and trifluoromethanesulfonate (manufactured by Wako Pure Chemical Industries, Ltd., WPAG-336), diphenyl-2,4,6-trimethylphenylsulfonium and p-toluenesulfonate Mixture (manufactured by Wako Pure Chemical Industries, WPAG It is particularly preferred to use 367), and the like.

Next, as a step (C), a negative pattern of the magnetic recording pattern is transferred to the radiation reaction layer 3 using a nanoimprint method.
Specifically, as shown in FIG. 1C, the negative pattern of the magnetic recording pattern is transferred to the radiation reaction layer 3 by pressing a nanoimprint stamp (not shown) against the radiation reaction layer 3.

  As the nanoimprinting method used in the present invention, a conventionally known method can be used without any limitation. For example, as a nanoimprinting stamp, a metal stamp or a resin stamp can be used in addition to a glass stamp. In addition, as a nanoimprint stamp, negative patterns of various magnetic recording patterns such as a servo signal pattern such as a burst pattern, a gray code pattern, a preamble pattern, and an address pattern are formed in addition to a track pattern for recording normal data. Things can be used.

  Moreover, it is preferable that the thickness L of the part 31 corresponding to the negative pattern of the radiation reaction layer 3 after transferring the negative pattern of the magnetic recording pattern to the radiation reaction layer 3 is in the range of 0 to 10 nm. By setting the thickness L of the portion 31 of the radiation reaction layer 3 within this range, the sagging of the edge portion of the radiation reaction layer 3 is eliminated in the later-described step (D) in which the radiation reaction layer 3 is wet-etched. The shielding property against the etchant of the layer 3 can be improved, and the magnetic recording pattern formation characteristics by the radiation reaction layer 3 can be improved.

Next, as step (D), the radiation reaction layer 3 patterned with the negative pattern of the magnetic recording pattern is formed by performing wet etching on the radiation reaction layer 3 that has been nanoimprinted according to the above procedure.
Specifically, as shown in FIG. 1D, the radiation reaction layer 3 is patterned into a negative pattern of the magnetic recording pattern by dissolving and removing the portion 31 of the radiation reaction layer 3 using an etching solution. Moreover, as a wet etching method used in this case, a conventionally known method can be used without any limitation.

"Process (E)"
Next, in the step (E), the radiation reaction layer 3 is irradiated with radiation R to generate an acid or a base from the radiation reaction layer 3.
Specifically, as shown in FIG. 1E, an acid or a base is generated from the radiation reaction layer 3 by irradiating the patterned radiation reaction layer 3 with radiation R (reference A in the figure). See). At this time, as the radiation R irradiated to the radiation reaction layer 3, for example, ultraviolet rays or heat rays can be used, and electromagnetic waves having a wide concept such as visible rays, X-rays, and gamma rays can be used. . In addition, when a photoacid generator is used for the radiation reaction layer 3, use of ultraviolet rays or heat rays as the radiation R can generate an acid or a base from the radiation reaction layer 3 more effectively. preferable.

  In the example shown in FIG. 1E, the radiation R is irradiated not only to the radiation reaction layer 3 but also to the magnetic layer 2 exposed from between the patterns of the radiation reaction layer 3. There is no particular problem because it is not affected by R irradiation.

"Process (F)"
Next, in step (F), the acid or base generated from the radiation reaction layer 3 is reacted with the magnetic layer 2 to modify the magnetic properties of the reaction site.
Specifically, as shown in FIG. 1 (F), the acid or base generated from the radiation reaction layer 3 is reacted with the portion covered with the radiation reaction layer 3 in the magnetic layer 2 (site 21 in the figure). See). As a result, the magnetic characteristics of the magnetic layer 2 corresponding to the reaction site, that is, the region 21 corresponding to the patterned radiation reaction layer 3 is modified and separated by the non-magnetic or weak magnetized region 21. A pattern is formed.

According to the manufacturing method of the present invention, by forming the magnetic recording pattern on the magnetic layer 2 by the above steps (B) to (F), the magnetic recording of a clear pattern is achieved without cutting the edge portion of the magnetic layer 2. A portion as well as a nonmagnetic portion (see portion 21 in FIG. 1F) can be formed. Thereby, the corrosion resistance of the magnetic layer 2 becomes good, and the effect that productivity and a manufacturing yield improve is acquired.
Moreover, since the pattern of the radiation reaction layer 3 can be accurately controlled only by the etching process time in the step (D), the width of the magnetic recording pattern can be formed wide. Thereby, it is possible to manufacture the magnetic recording medium 10 with a high signal intensity and a high bit error rate.

"Process (G)"
Next, in the step (G), the radiation reaction layer 3 remaining on the magnetic layer 2 and reacting with the radiation R is removed by wet etching.
Specifically, as shown in FIG. 1G, the radiation reaction layer 3 on the magnetic layer 2 is selectively removed using an etching solution, as in the step (D). As a wet etching method used in this case, a conventionally known method can be used without any limitation.

  In the present embodiment, a method using a wet etching method is described as a method for removing the radiation reaction layer 3 remaining after the reaction, but the method is not limited thereto. For example, in addition to methods such as reactive ion etching and ion milling, a general dry etching method can also be used and can be appropriately employed.

"Process (H)"
Next, in the step (H), the surface of the magnetic layer 2 is covered with the protective layer 9.
Specifically, as shown in FIG. 1H, the protective layer 9 is formed by depositing a protective film material as a thin film on the magnetic layer 2 using, for example, a method such as P-CVD. . Further, the method for forming the protective layer 9 is not limited to the above-described P-CVD method, and a conventionally known method such as an MOCVD method can also be appropriately employed.

  As the material for the protective layer 9, as described above, a material including a protective film material that is usually used can be used in addition to the diamond like carbon generally used in the field.

  Furthermore, in the manufacturing method of the present invention, after forming the protective layer 9 in the step (H), the lubricating layer made of a lubricant material (not shown) is further formed on the protective layer 9 using the same method as described above. It is more preferable to form a layer.

  Through the above steps, the magnetic layer 2 having a magnetically separated magnetic recording pattern is formed. By forming a magnetically separated magnetic recording pattern, it is possible to eliminate writing blur when performing magnetic recording on the magnetic recording medium 10 and to provide the magnetic recording medium 10 having a high surface recording density. . In particular, the method for forming a magnetic recording pattern in the manufacturing method of the present invention does not require a physical processing step of the magnetic layer 2 and a step of embedding a nonmagnetic material or the like in the processing portion. It becomes possible to improve the cleanliness and flatness.

  The magnetically separated magnetic recording pattern described in the present invention means that the magnetic layer 2 is modified (demagnetized) when the magnetic recording medium 10 is viewed from the surface side (upper side in FIG. 1 (H)). Or the state isolate | separated by the site | part 21 weakened). That is, when the magnetic recording medium 10 is viewed from the surface side, if the magnetic layer 2 is separated by modification of the magnetic characteristics, there is no problem even if it is not separated at the bottom, and in such a case, the magnetic layer 2 is also magnetically separated. This is included in the concept of magnetic recording patterns.

  Further, in the magnetic recording pattern referred to in the present invention, the modified portion 21 does not have to be completely nonmagnetic. That is, even if the portion 21 has a slight coercive force or saturation magnetization, if the magnetic head can read and write to the magnetic recording pattern portion, the magnetic recording pattern separated magnetically can do.

  The magnetic recording pattern in the present invention is a so-called patterned medium in which the magnetic recording pattern is arranged with a certain regularity for each bit, a medium in which the magnetic recording pattern is arranged in a track shape, and other servo Including signal patterns. Among these, in particular, the fact that the magnetically separated magnetic recording pattern is a magnetic recording track and a servo signal pattern can be applied to a so-called discrete type magnetic recording medium, whereby the simplicity in the manufacturing process can be improved. To preferred.

  According to the method for manufacturing the magnetic recording medium 10 according to the present invention as described above, the step of forming the magnetic layer 2 on the nonmagnetic substrate 1 and the method for forming the magnetic recording pattern on the magnetic layer 2 are described. A step of forming a patterned radiation reaction layer 3; a step of irradiating the radiation reaction layer 3 with radiation R to generate an acid or base from the radiation reaction layer 3; and an acid or base generated from the radiation reaction layer 3 and magnetism By reacting with the layer 2 and modifying the magnetic properties of the reaction site in this order, the magnetic recording portion and the non-magnetic portion have a clear pattern without the edge portion of the magnetic layer 2 being scraped. Therefore, the corrosion resistance is improved, and the productivity and the yield are improved. Further, since the pattern of the radiation reaction layer 3 can be accurately controlled only by the etching process time, the width of the magnetic recording portion can be formed wide, and a high signal error and a high bit error rate are ensured. Thus, the magnetic recording medium 10 having excellent surface smoothness can be manufactured. Accordingly, the manufacturing cost can be greatly reduced by a simple process, and the magnetic recording medium 10 with high productivity and high yield can be manufactured.

[Magnetic recording / reproducing device]
Next, FIG. 2 shows the configuration of a magnetic recording / reproducing apparatus (hard disk drive) according to the present invention. As shown in FIG. 2, the magnetic recording / reproducing apparatus 50 according to the present invention comprises the above-described magnetic recording medium 10 according to the present invention, a medium driving unit 51 for driving the magnetic recording medium 10 in the recording direction, a recording unit, and a reproducing unit. A magnetic head 57; a head drive unit 58 for moving the magnetic head 57 relative to the magnetic recording medium 10; and a recording / reproduction signal processing means for performing signal input to the magnetic head 57 and output signal reproduction from the magnetic head 57. And a recording / reproducing signal system 59 in combination. By combining these, the magnetic recording / reproducing apparatus 50 with high recording density can be configured.

  Since the magnetic recording / reproducing apparatus 50 according to the present embodiment uses the magnetic recording medium 1 having the above-described configuration, the magnetic recording / reproducing apparatus 50 has sufficient reproduction output and high SNR, and has excellent flying characteristics of the magnetic head 57 and accurate magnetic recording. Recording / reproducing operations can be performed, and excellent high-density recording characteristics can be obtained.

  When the flying height of the magnetic head 57 is 0.005 μm to 0.010 μm, which is lower than the conventional height, the output is improved and a high device SNR is obtained, and the magnetic capacity is high and the reliability is high. A recording / reproducing apparatus 50 can be provided. In addition, when the signal processing circuit based on the maximum likelihood decoding method is combined, the recording density can be further improved. For example, the track density is 300 ktracks / inch or more, the linear recording density is 1000 kbits / inch or more, and 300 Gbits per square inch. Sufficient SNR can be obtained even when recording / reproducing is performed at the above high recording density.

  Furthermore, in this embodiment, the reproducing element of the magnetic head 57 described above is composed of a GMR head, a TMR head or the like using a giant magnetoresistive effect, so that a sufficient signal intensity can be obtained even at a high recording density. Thus, a magnetic recording / reproducing apparatus having a high recording density can be realized.

  Next, a method for manufacturing a magnetic recording medium, a magnetic recording medium, and a magnetic recording / reproducing apparatus according to the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is limited only to these examples. It is not something.

(Example)
First, a vacuum chamber in which a cleaned HD glass substrate was set was evacuated to 1.0 × 10 ⁻⁵ Pa or less in advance. The glass substrate used here is composed of Li ₂ Si ₂ O ₅ , Al ₂ O ₃ —K ₂ O, Al ₂ O ₃ —K ₂ O, MgO—P ₂ O ₅ , and Sb ₂ O ₃ —ZnO. The material is crystallized glass, and the outer diameter is 65 mm, the inner diameter is 20 mm, and the average surface roughness (Ra) is 2 angstroms.

Next, on the glass substrate, a thin film is laminated in the order of CrTi layer as an adhesion layer, FeCoB as a soft magnetic layer, Ru as an intermediate layer, and 70Co-5Cr-15Pt-10SiO ₂ alloy as a magnetic layer by using a DC sputtering method. did. The thicknesses of these layers were CrTi adhesion layer: 5 nm, FeCoB soft magnetic layer: 60 nm, Ru intermediate layer: 10 nm, and magnetic layer: 15 nm.

  When a sample of the magnetic recording medium (manufactured intermediate product) manufactured through the above steps was subjected to an evaluation test using a Kerr effect measuring machine, the coercive force (Hc) was 4800 Oe, and the Kerr rotation angle strength (θk) was 0.12 ( Arbitrary unit).

  Next, a radiation reaction layer was formed on the magnetic layer of the magnetic recording medium (manufactured intermediate product) manufactured in the above process by using a spin coating method. As a material for the radiation reaction layer, cyclohexyl sulfonyl diazomethane (manufactured by Wako Pure Chemical Industries, Ltd., WPAG-145) as a photoacid generator was used, and the layer thickness was 40 nm. Further, at the time of coating the radiation reaction layer, the photoacid generator was heated to a temperature of about 130 ° C. to be plasticized.

Then, a glass stamp having a pattern with a track pitch of 81 nm, a track width of 30 nm, and a recording area width of 51 nm was pressed against the radiation reaction layer at a pressure of 1 MPa (about 8.8 kgf / cm ² ). Thereafter, the substrate was cooled to solidify the radiation reaction layer, and the stamp pattern was transferred. Here, the film thickness of the groove portion of the transferred pattern (the portion having a width of 51 nm serving as a recording region) was 15 nm to 18 nm.
Through the above process, a negative pattern of the magnetic recording pattern was formed in the radiation reaction layer using the nanoimprint method.

Next, the groove part in the pattern formed in the radiation reaction layer (photoacid generator) was removed by pure water cleaning.
Next, the surface of the patterned radiation reaction layer is irradiated with ultraviolet light having a wavelength of 254 nm for 15 minutes to cause the acid generated from the photoacid generator forming the radiation reaction layer to react with the magnetic layer. The magnetic properties were modified.
Thereafter, the radiation reaction layer after the reaction was removed by washing with pure water.

  With respect to the magnetic recording medium manufactured by the above process, the magnetic properties of the reacted part in the magnetic layer were calculated by disassembling the measurement loop of the Kerr effect measuring machine. As a result, Hc was 1200 Oe and θk was 0.03. It was.

  In this embodiment, a protective layer made of a carbon protective film material is formed on the surface of the magnetic layer with a thickness of 4 nm using the CVD method. The recording medium was completed.

With respect to the magnetic recording medium manufactured by the above method, the electromagnetic conversion characteristics (SNR and 3T-squash) and the head flying height (glide avalanche) were measured.
Here, the electromagnetic conversion characteristics are evaluated using a spin stand. In this case, the evaluation head uses a perpendicular recording head for recording and a TuMR head for reading, and records a signal of 750 kFCI. SNR value and 3T-squash were measured.

  The magnetic recording medium manufactured in this example has an SNR of 13.9 dB, a 3T-square of 90%, excellent RW characteristics, and a minimum flying height by a head flying height measuring device of 6 nm. It was confirmed that the head flying characteristics were also stable. That is, it was confirmed that the surface of the magnetic recording medium had high smoothness and excellent separation characteristics due to the nonmagnetic portion between the tracks of the magnetic layer.

(Comparative example)
A magnetic recording medium was manufactured in the same procedure as in the above example, except that the step of forming the magnetic recording pattern on the magnetic layer was performed in the conventional manufacturing process as shown in FIGS. .
That is, after forming a magnetic layer in the same procedure as in the above example, a carbon mask layer was formed to a thickness of 30 nm on the surface, and a UV curable resin was applied to the surface to a thickness of 200 nm. Thereafter, further, an imprint having the same pattern as in the example was applied thereon.

Next, the imprinted surface resist is removed by ion milling using CF ₄ gas, and the underlying carbon layer is removed by ion milling using a mixed gas of argon and oxygen. Thus, the processed portion of the magnetic layer was exposed.
Next, the magnetic layer was processed by ion milling using argon gas, and was etched by about 14 nm in the thickness direction of the magnetic layer. Thereafter, the resin remaining on the surface and the carbon mask layer were removed by ashing using oxygen gas. Thereafter, a CrTi film having a thickness of about 30 nm was formed on the surface of the magnetic layer by sputtering, and the surface was planarized by CMP using a diamond slurry.
Then, a protective layer made of a carbon protective film material is formed on the flattened surface with a thickness of 4 nm by using the CVD method, and then a lubricant is applied with a thickness of 1.5 nm to form a magnetic recording medium. Was completed.

  The magnetic recording medium manufactured in this comparative example had an SNR of 12.8 dB and a 3T-squash of 90%. However, the minimum flying height measured by the head flying height measuring instrument was 9 nm, and it was confirmed that the head flying characteristics were inferior to the magnetic recording media of the above examples and the smoothness of the surface of the magnetic recording media was poor. .

  As described above, it is clear from the results of this example that the magnetic recording medium obtained by the manufacturing method according to the present invention has excellent recording / reproducing characteristics, excellent electromagnetic conversion characteristics, and can cope with a high recording density. It was.

  The magnetic recording medium manufacturing method of the present invention is applied to a manufacturing process of a magnetic recording medium used in a magnetic recording / reproducing apparatus, so-called a hard disk drive, thereby manufacturing a magnetic recording medium having excellent electromagnetic conversion characteristics with high productivity. The industrial applicability is immeasurable.

DESCRIPTION OF SYMBOLS 1 ... Nonmagnetic board | substrate, 2 ... Magnetic layer, 21 ... Site | part (reaction location), 3 ... Radiation reaction layer, 10 ... Magnetic recording medium, 50 ... Magnetic recording / reproducing apparatus, 57 ... Magnetic head, R ... Radiation, A ... Radiation Acids or bases generated from the reaction layer (acids or bases generated when degradable organisms generated from the radiation reaction layer react with other substances)

Claims (9)

A method for producing a magnetic recording medium having a magnetically separated magnetic recording pattern, comprising:
Forming a magnetic layer on a non-magnetic substrate;
Forming a patterned radiation reaction layer for forming a magnetic recording pattern on the magnetic layer;
Irradiating the radiation reaction layer with radiation to generate an acid or base from the radiation reaction layer;
A method for producing a magnetic recording medium, comprising the steps of reacting an acid or base generated from the radiation reaction layer with the magnetic layer and modifying magnetic properties of the reaction site in this order.   The radiation reaction layer contains a radiolytic compound, and the radiolytic compound generates an acid or a base as a decomposition product upon irradiation with radiation, or the generated decomposition product reacts with another substance. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic recording medium is a substance that generates an acid or a base.   3. The method of manufacturing a magnetic recording medium according to claim 1, wherein the radiation reaction layer is formed of a photoacid generator, and ultraviolet rays or heat rays are used as radiation applied to the radiation reaction layer.   4. The method of manufacturing a magnetic recording medium according to claim 1, wherein a nanoimprint method is used in the step of forming the patterned radiation reaction layer. 5.   The method of manufacturing a magnetic recording medium according to claim 4, wherein after the nanoimprint is applied to the radiation reaction layer, the radiation reaction layer is subjected to wet etching to form a patterned radiation reaction layer.   The photoacid generator is cyclohexylsulfonyl diazomethane, t-butylsulfonyl diazomethane, p-toluenesulfonyl diazomethane, a mixture of triphenylsulfonium and trifluoronetanesulfonate, diphenyl-4-methylphenylsulfonium and 3. A mixture of trifluoromethane sulfonate and a mixture of diphenyl-2,4,6-trimethylphenyl sulfonate and p-toluene sulfonate. 6. The method for producing a magnetic recording medium according to any one of 5 above.   The magnetism according to any one of claims 1 to 6, wherein after the step of modifying the magnetic properties of the magnetic layer, the radiation reaction layer after reaction with radiation is removed by wet cleaning. A method for manufacturing a recording medium.   A magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to claim 1.   9. A magnetic recording / reproducing apparatus comprising at least the magnetic recording medium according to claim 8 and a magnetic head for recording / reproducing information on / from the magnetic recording medium.

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