JP2013118044A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording area separation type magnetic recording medium (DTM, BPM) which is optimal for reducing flying height of a magnetic head.SOLUTION: There is provided a magnetic recording medium in which a portion having a relatively high element ratio of a ferromagnetic material and a portion 13 having a low element ratio thereof periodically exist in an in-plane direction in magnetic recording layers 6 and 7, and an average height of the portion having the relatively high element ratio of the ferromagnetic material from a substrate surface is higher than that of the portion having the low element ratio thereof from the substrate surface. In manufacturing of the recording area separation type magnetic recording medium in which the element ratio of the ferromagnetic material is relatively reduced by ion implantation, etching an ion implantation portion in advance allows the height after the ion implantation to be relatively reduced compared to the height of a portion having no ions implanted thereto.

Description

  The present invention relates to a pattern medium typified by a discrete track medium and a bit pattern medium suitable for high recording density, and a manufacturing method thereof.

  Magnetic disk devices used for storage devices such as large computers, workstations, and personal computers are becoming increasingly important year by year, and have been developed to have a large capacity and a small size. High density is indispensable for reducing the capacity and size of magnetic disk devices. One technique for increasing the density is to reduce medium noise by reducing the magnetization reversal unit of the magnetic recording medium. For this reason, the conventional magnetic recording medium employs a structure in which the ferromagnetic crystal grains constituting the magnetic recording layer are separated in advance by a nonmagnetic material contained in the magnetic recording layer.

  Currently, as a proposal to more actively control this separation area and improve the magnetic recording density, a discrete track medium (DTM) in which separation processing is performed between recording tracks, and further, separation processing is performed between recording bits. Bit-patterned media (BPM) has been researched and developed, and in any case, the separation zone forming technique is an important point for increasing the density.

As a method for producing DTM, a magnetic film processing type in which a magnetic film is physically processed by etching or the like has been proposed. The magnetic film processed DTM is generally manufactured by the following process.
(1) A metal thin film is provided on the recording layer and a resist is applied.
(2) A fine pattern is given to the resist by lithography.
(3) The metal thin film in the resist pattern recess is etched by a dry process to expose the recording layer.
(4) The exposed recording layer is etched by a dry process to form a recording track separation portion (groove).
(5) The remaining resist and metal thin film on the recording track (land) are removed.
(6) The groove portion is backfilled with a nonmagnetic material and flattened.
(7) A protective layer and a lubricating layer are provided.

  Thus, the magnetic film processing type DTM has not only a very complicated process, but also has a problem that the roughness of the backfilled and flattened surface is larger than that of the continuous medium, and the magnetic head flying property is not stable.

  As another DTM manufacturing method for solving the above-described problem, a method of demagnetizing the groove portion by ion implantation has been proposed. In Japanese Patent Laid-Open No. 2007-226862, a fine pattern is placed on the top of a magnetic recording medium formed up to a protective film, and ions of Si, In, B, P, C, and F are implanted using a commercially available ion implanter. ing. Japanese Patent Laid-Open No. 2006-309841 discloses that a DTM can be produced by implanting ions such as Ag, B, Cr, Mo, Al, and Nb through a stencil mask. Japanese Patent Laid-Open No. 2007-220164 discloses a method of forming a DTM by depositing Si in a concave portion of a finely processed resist and then selectively diffusing Si into the groove precursor region of the recording layer by irradiation with Ar ions. ing. In these disclosures, not only can the manufacturing method be simplified as compared to the magnetic film processed DTM medium, but also the floating property of the magnetic head is good due to the smoothness of the surface of the manufactured medium.

JP 2007-226862 A JP 2006-309841 A JP 2007-220164 A

  However, the production of DTM by ion implantation has a problem of increasing the volume of the implanted portion. That is, the portion where the element ratio of the ferromagnetic material is relatively lowered by ion implantation is increased in volume, and the height is increased as compared with the non-implanted portion. For this reason, the distance between the non-injection portion corresponding to the magnetic recording track and the magnetic head is increased. As a result, an increase in spacing loss becomes an impediment to higher recording density.

For example, when a recording layer made of a Co alloy has a thickness of 20 nm, atoms of approximately 10 ¹⁷ atoms exist per 1 cm ² . When Cr ions are implanted at 10 ¹⁶ atoms for the purpose of deteriorating magnetic properties, a volume increase of 10% occurs when there is almost no change in density. Implanted ions diffuse in the in-plane direction in the magnetic layer and have an overall rise. However, the height of the implanted portion is higher than that of the non-implanted portion, and the distance from the magnetic head is the non-implanted portion (magnetic The recording track) is farther than the injection part. In order to reduce the medium noise at the time of read / write by the magnetic head, it is advantageous to make the contrast of the magnetic characteristics of the injection part and the non-injection part larger. Therefore, if the injection amount is increased, the volume increase becomes more remarkable. There was a problem that the spacing loss increased.

  The present invention has been made to solve the above-described problems, and a first object of the present invention is to provide a recording area separation type magnetic recording medium (DTM, BPM) optimum for lowering the flying height of the magnetic head. Is to do.

  A second object is to provide a method of manufacturing a recording area separation type magnetic recording medium (DTM, BPM) that is optimal for lowering the flying height of a magnetic head.

  In order to solve the above problems, the present invention mainly adopts the following configuration. That is, in a magnetic recording medium in which a magnetic recording layer is formed directly on the substrate or at least via an intermediate layer, the magnetic recording layer has a portion in which the element ratio of the ferromagnetic material is relatively high and a portion in which the low ratio is in the in-plane direction. The average height from the substrate surface of the portion where the element ratio of the ferromagnetic material is relatively high is higher than the average height from the substrate surface of the portion where the element ratio of the ferromagnetic material is low. Features.

  Furthermore, according to the present invention, in the ion-implanted recording region separation type magnetic recording medium, the average height from the substrate surface of the ion-implanted portion is 0.1 nm higher than the average height from the substrate surface of the non-implanted portion. By reducing the thickness to 3 nm or less, a recording area separation type magnetic recording medium suitable for increasing the recording density can be obtained. By making the average height from the substrate surface of the ion-implanted portion lower than the average height from the substrate surface of the non-implanted portion, the flying reference surface hs of the magnetic head is in accordance with the area ratio between the ion-implanted portion and the non-implanted portion. It becomes high. Specifically, when the high portion is (height h1, area ratio S1) and the low portion is (height h2, area ratio S2), hs is given by h1 × S1 + h2 × S2, and h1> hs> h2. Become. Accordingly, the distance between the non-injection portion, that is, the magnetic recording track and the magnetic head, can be made closer than in the case of h1 which is considered as the flying reference plane of the continuous medium. The reason why the thickness is 0.1 nm or more is based on the result indicating that the magnetic head is substantially approached above this value. The reason why the thickness is 3 nm or less is a problem in the flying stability of the magnetic head if it is larger than this value. It depends on the results that occur.

  In order to realize the above configuration, a mask layer having a fine pattern provided directly or via one or more thin films on the magnetic recording layer is used, and the element ratio of the ferromagnetic material is relatively lowered by ion implantation. When the region-separated magnetic recording medium is manufactured, the ion-implanted portion is etched in advance, so that the height after ion implantation is relatively lower than the non-implanted portion in the range of 0.1 nm to 3 nm. I can do things.

  A discrete track medium can be manufactured by forming the high-content portion and the low-content portion of the magnetic recording layer substantially concentrically. In addition, a bit patterned medium can be manufactured by forming a dot shape in which portions having a low content of nonmagnetic elements in the magnetic recording layer are arranged in an island shape.

  The element to be ion-implanted is any one selected from the group consisting of Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Ru, B, C, Si, Ge, Ar, Kr, Rn, and Xe. Use elements.

  According to the present invention, when a recording area separation type magnetic recording medium for the purpose of improving the recording density is manufactured by the ion implantation method, the distance between the recording area and the magnetic head (spacing loss) increases due to the increase in the volume of the implanted portion. Therefore, it becomes possible to reduce the spacing loss by removing the obstacle to the improvement of the recording density.

FIG. 4 is a schematic cross-sectional view showing a manufacturing process of a magnetic disk according to the present invention. FIG. 4 is a schematic cross-sectional view showing a manufacturing process of a magnetic disk according to the present invention. FIG. 4 is a schematic cross-sectional view showing a manufacturing process of a magnetic disk according to the present invention. FIG. 4 is a schematic cross-sectional view showing a manufacturing process of a magnetic disk according to the present invention. FIG. 4 is a schematic cross-sectional view showing a manufacturing process of a magnetic disk according to the present invention. DTM, the height of the etched portion based on the non-etched portion of the Co-based alloy magnetic layer (recording layer 2) and the height of the ion-implanted portion based on the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2) The figure which shows a relationship. FIG. 4 is a schematic cross-sectional view showing a manufacturing process of a magnetic disk according to the present invention. The figure which shows the relationship between the height of the ion implantation part on the basis of the non-implantation part of a DTM and Co type alloy magnetic layer (recording layer 2), and glide noise. The figure which shows the relationship between the height of the ion implantation part on the basis of the non-implantation part of a DTM and Co type alloy magnetic layer (recording layer 2), and output resolution Re. The figure which shows the relationship between the height of an ion implantation part on the basis of the non-implantation part of a BPM and Co type alloy magnetic layer (recording layer 2), and glide noise. The figure which shows the relationship between the height of the ion implantation part on the basis of the non-implantation part of BPM and Co type alloy magnetic layer (recording layer 2), and output resolution Re.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing a manufacturing process of a recording area separation type magnetic recording medium according to an embodiment of the present invention. This magnetic recording medium (magnetic disk) includes an AlTi adhesion layer 2, a soft magnetic layer 3, a NiW seed layer 4, a Ru intermediate layer 5, and a Co-based alloy granular magnetic layer formed on both surfaces of a nonmagnetic substrate (substrate) 1. (Recording layer 1) 6, Co-based alloy magnetic layer (recording layer 2) 7, and Ta mask layer precursor 8. The soft magnetic layer 3 is a laminated film of an FeCo-based lower soft magnetic layer 3a, a Ru antiferromagnetic coupling layer 3b, and an FeCo-based upper soft magnetic layer 3c.

  The steps until the Ta mask layer precursor 8 was formed on the nonmagnetic substrate 1 were performed according to a normal manufacturing method as described below.

First, a soda lime glass substrate (outer diameter 65 mm, inner diameter 15 mm, thickness 0.635 mm) used as the substrate 1 was sufficiently washed. This was introduced into a vacuum chamber evacuated to about 1.3 × 10 ⁻⁵ Pa (1.0 × 10 ⁻⁷ Torr) or less. First, it was transferred to an adhesion layer forming chamber, and an Al-50 at% Ti adhesion layer 2 was formed to 5 nm by DC magnetron sputtering under an Ar atmosphere of about 0.8 Pa (6 mTorr). Subsequently, the lower soft magnetic layer 3a is transferred to the lower soft magnetic layer forming chamber, and the Fe-35at% Co-9at% Ta-4at% Zr alloy lower soft magnetic layer 3a is formed by DC magnetron sputtering under an Ar atmosphere of about 0.8 Pa (6 mTorr). A 25 nm film was formed. Subsequently, it was transferred to the antiferromagnetic coupling layer forming chamber, and a Ru layer 3b of 0.5 nm was formed by DC magnetron sputtering under an Ar atmosphere of about 0.8 Pa (6 mTorr). Subsequently, it is transported to the upper soft magnetic layer forming chamber, and the upper soft magnetic layer 3c of Fe-35at% Co-9at% Ta-4at% Zr alloy is formed by DC magnetron sputtering under the condition of Ar atmosphere of about 0.8 Pa (6 mTorr). Was deposited to 25 nm.

Subsequently, the substrate temperature is increased to 55 ° C. after being transferred to the substrate cooling chamber and lowered to 55 ° C., and then transferred to the seed layer forming chamber, where DC is applied under the condition of Ar atmosphere of about 0.9 Pa (7 mTorr). The Ni-8 at% W seed layer 4 was formed to 8 nm by magnetron sputtering. Subsequently, it was transferred to an intermediate layer forming chamber, and a Ru intermediate layer 5 having a thickness of 15 nm was formed by DC magnetron sputtering under an Ar atmosphere of about 2 Pa (15 mTorr). Further, it is transported to the magnetic recording layer forming chamber 1 and from a 90 mol% (Co-15 at% Cr-18 at% Pt) 8 mol% SiO ₂ alloy by DC magnetron sputtering under an Ar atmosphere of about 0.9 Pa (7 mTorr). After forming a granular magnetic layer (recording layer 1) 6 having a thickness of 13 nm, the granular magnetic layer (recording layer 1) 6 is transferred to the magnetic recording layer forming chamber 2 and is subjected to Co-13 at% Cr-- by DC magnetron sputtering under an Ar atmosphere of about 0.8 Pa (6 mTorr). An 18 at% Pt-7 at% B magnetic layer (recording layer 2) 7 was formed to a thickness of 6 nm. Subsequently, the film was transferred to a Cr mask layer precursor formation chamber, and a Ta mask layer precursor 8 was formed to 30 nm by DC magnetron sputtering under an Ar atmosphere of about 0.9 Pa (7 mTorr).

  As the substrate 1, in addition to soda lime glass, chemically strengthened aluminosilicate, Al—Mg alloy substrate subjected to Ni—P electroless plating, ceramics made of silicon, borosilicate glass, etc., or ceramics subjected to glass glazing It is possible to use a non-magnetic rigid substrate made of, for example.

  The adhesion layer 2 is provided in order to prevent electrochemical elution of alkali metal from soda lime glass and to improve adhesion between the glass and the soft magnetic layer 3, and in addition to AlTi, NiTa, AlTa , CrTi, CoTi, NiTaZr, NiCrZr, CrTiAl, CrTiTa, CoTiNi or CoTiAl, and the thickness is arbitrary. Further, it can be omitted if it is not necessary to use it.

  A soft magnetic domain pinned layer may be provided between the adhesion layer 2 and the soft magnetic layer 3. As a typical configuration in this case, Ni-18 at% Fe of 6 nm, Fe-50 at% Mn of 17 nm, and Co-10 at% Fe of 3 nm are sequentially formed on the adhesion layer 2 in this order. A magnetic layer 3 was provided. As the seed layer 4, a NiFe alloy, NiTa alloy, TaTi alloy, or the like can also be used. Further, a CrTi alloy may be laminated between the seed layer 4 and the soft magnetic layer 3. The substrate cooling step can be performed before the formation of the upper soft magnetic layer 3c and before the formation of the recording layer 6, not after the formation of the upper soft magnetic layer 3c, and a plurality of these may be combined.

  The substrate 1 formed up to the Ta mask layer precursor 8 is taken out of the vacuum layer, put into a resist coating machine, and a methyl methacrylate resin (PMMA) layer 9 is provided as a resist material on the Ta mask layer precursor by 80 nm. A desired fine pattern shown in FIG. 2 was formed by the nanoimprint technique. That is, the stamper used for forming the fine pattern includes a region where the width of the resist convex portion is 60 nm, the width of the resist concave portion is 40 nm, and the residue can be embossed concentrically into a shape of 5 nm.

Next, the substrate provided up to the PMMA layer 9 having the fine pattern was introduced into a vacuum apparatus different from the one formed up to the Ta mask layer precursor 8, and the Ta mask layer 82 was formed. First, it was transferred to a reactive oxygen ion etching (RIE-O ₂ ) chamber using oxygen to remove the resist residue of 5 nm. Subsequently, the film was transferred to an ion beam etching (IBE) chamber using Ar to remove all 30 nm of the Ta mask precursor layer under the resist removal portion and to etch the Co-based alloy magnetic layer (recording layer 2) 7 several nm. At this time, several types of samples were produced by changing the etching depth, and used for the evaluation or ion implantation process described later. For comparison, a sample in which only the Ta mask precursor layer 30 nm was etched and the Co-based alloy magnetic layer (recording layer 2) 7 was not etched was prepared and evaluated at the same time. FIG. 3 shows a schematic cross-sectional view of the magnetic recording medium according to the present invention that has undergone the above steps. Subsequently, the Ta mask layer 82 shown in FIG. 4 was formed by removing the PMMA layer 9 by transferring it to the reactive oxygen ion etching (RIE-O ₂ ) chamber without taking out from the vacuum layer. When all of the PMMA layer 9 is simultaneously removed during the etching of the Ta mask precursor layer under the resist removal portion and the Co-based alloy magnetic layer (recording layer 2) 7 by the Ar ion beam etching described above, reactive oxygen ion etching (RIE-O) ₂ ) can be omitted.

  For several types of samples formed up to the Ta mask layer, each one has the height of the etched portion with respect to the non-etched portion of the Co-based alloy magnetic layer (recording layer 2) 7, and the atomic force microscopy (AFM). Evaluated.

The substrate formed up to the Ta mask layer 82 was transported to the Cr ion implantation chamber without taking it out of the vacuum layer except for the one subjected to the AFM evaluation. The Cr ion implantation chamber is a plasma beam system having a Cr arc discharge mechanism and an ion transport mechanism using a magnetic field filter, and a high voltage DC pulse bias can be applied to the substrate. In the present invention, Cr ions are implanted across the entire surface of the substrate at a bias voltage of −20 kV. At this time, several types of samples were produced by changing the injection amount by changing the injection time. Subsequently, the Ta mask layer was transferred to the reactive CF ₄ ion etching chamber and all of the Ta mask layer was removed by CF ₄ ion etching, so that the ion implantation portion 13 shown in FIG. 5 was provided. The relationship between the ion implantation time and the implantation amount was obtained by injecting chromium ions on a Cr-free substrate in advance and obtaining the result by Rutherford backscattering analysis. Ions are implanted into the implanted portion at the time of ion implantation, but the mask layer removing step described above can be omitted when the mask portion uses implantation conditions or a combination of mask layers that are etched by ion energy.

  For several types of samples formed up to the ion implantation part 13, each one has the height of the ion implantation part 13 with respect to the non-implanted part of the Co-based alloy magnetic layer (recording layer 2) 7, and the atomic force microscopy ( AFM).

The height of the etched portion relative to the non-etched portion of the Co-based alloy magnetic layer (recording layer 2) 7 before ion implantation, and the non-ion-implanted portion of the Co-based alloy magnetic layer (recording layer 2) 7 after ion implantation. Table 1 and FIG. 6 show the relationship between the height of the ion implantation portion 13 and the ion implantation amount as a reference. In Table 1 and FIG. 6, A is the height (nm) of the etched portion with respect to the non-etched portion of the Co-based alloy magnetic layer (recording layer 2) 7, and B is the Co-based alloy magnetic layer (recording layer 2) 7 The height (nm) of the ion-implanted portion 13 with reference to the non-implanted portion, and C is the ion implantation amount ((× 10 ¹⁵ ) atoms / cm ² ).

The substrate formed up to the ion implantation portion 13 is transferred to the DLC protective film formation chamber without being taken out of the vacuum layer except for the one subjected to the above AFM evaluation, and is subjected to RF under the condition of a C ₂ H ₂ atmosphere of about 10 Pa. A DLC protective film 10 having a thickness of 3 nm was formed by a CVD method.

  A plurality of samples prepared by the above method were used, and a fluorocarbon-based lubricating film 11 was provided on the DLC protective film 10 to form a discrete track magnetic recording medium (DTM) shown in FIG. This thickness was quantified with a Fourier transfer infrared spectroscopic analyzer (FT-IR), and was 1.0 nm for all samples. A plurality of magnetic recording media provided with these fluorocarbon-based lubricating films 11 were used, and the following evaluations on the flying stability of the magnetic head and the read / write (RW) characteristics were evaluated using a spin stand.

  As an evaluation of the flying stability of the magnetic recording medium, glide noise (GN) by a head (glide head) on which a piezoelectric element is mounted was measured. Glide noise is noise output from the piezoelectric element when the glide head is flying over the magnetic recording medium. A large glide noise means that the slider does not stably float on the magnetic recording medium.

  The glide noise measurement method is as follows. The glide head was levitated on the rotating magnetic recording medium, and moved by 0.05 mm from a radial position of 16.5 mm to 41.5 mm of the magnetic recording medium. At each radial position, the noise of the piezoelectric element was measured for one round of the magnetic recording medium, and the average value was obtained. Furthermore, the average value for each radial position was averaged and defined as the glide noise of the magnetic recording medium. Here, the flying height of the glide head was 6 nm. Usually, when the relative speed of the glide head with the rotating magnetic recording medium changes, the flying height changes. Therefore, in order to avoid a change in the flying height, the rotational speed of the magnetic recording medium is changed every time the glide head is moved, and the relative speed is controlled to be constant even if the radial position changes. The voltage of the piezoelectric element was output through an amplifier and a frequency separator. The gain of the amplifier was 60 dB (decibel), and the frequency separator bandwidth was 100 kHz to 2 MHz. If the value of glide noise is 30 mV or less, it can be determined that the flying property of the head is stable. If it exceeds 30 mV, it can be determined that the head is unstable and is not suitable as a magnetic recording medium.

  The results of the glide noise evaluation are shown in Table 2 and FIG. Co-based alloy magnetic layer (recording layer 2) 7 When the height of the ion implanted portion 13 with respect to the non-implanted portion is -3 nm or more and 3 nm or less, the glide noise is 30 mV or less, and when the step is larger than 3 nm, the glide noise Becomes larger than 30 mV. That is, if the height of the ion-implanted portion 13 with respect to the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2) 7 is in the range of −3 nm to 3 nm, it cannot be said that the surface shape is suitable for a magnetic recording medium. I understood that.

  Next, the RW characteristics of a sample in which the height of the ion-implanted portion 13 with respect to the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2) 7 which can be said to be a surface shape suitable for a magnetic recording medium is −3 nm to 3 nm. Evaluated.

  The evaluation method of the RW characteristic is as follows. The magnetic head was floated on the rotating magnetic recording medium, and the electromagnetic conversion characteristics were measured with a skew angle of 0 ° at a radial position of 21 mm of the magnetic recording medium. The peripheral speed of the magnetic recording medium was constant at 10 m / s, and the magnetic head was set to have a mechanical flying height of 4 nm on a continuous medium having a uniform surface. The ratio of the signal output of 8.93 kiloflux change / mm (227 kFCI) to the signal output at 37 kiloflux change / mm (940 kFCI) is the output resolution Re (Re (%) = S (940 kFCI) / S (227 kFCI) × 100 ). It can be said that the larger the Re, the more suitable the recording density.

  The evaluation results of the output resolution Re are shown in Table 3 and FIG.

The Re of a so-called continuous medium sample in which the Co-based alloy magnetic layer (recording layer 2) 7 was not etched and no ion implantation was performed was 50%. On the other hand, the Re of the sample in which the Co-based alloy magnetic layer (recording layer 2) 7 was etched to form a physical track shape but no ion implantation was performed was 44 to 50%, which is equivalent to that of the continuous medium. It was the following. This is because, although the distance between the magnetic recording track and the magnetic head is reduced, the track separation portion remains ferromagnetic, and the leakage magnetic flux from this portion has an adverse effect on the electromagnetic conversion characteristics. When the Co-based alloy magnetic layer (recording layer 2) 7 is etched and the ion implantation amount is changed from 1 × 10E + 15 to 1 × 10E + 17 (atoms / cm ² ), the Co-based alloy magnetic layer (recording layer 2) 7 Re becomes 50% or more when the height of the ion-implanted portion 13 with respect to the non-implanted portion is set to −0.1 nm or less. This is because ion implantation deteriorates the magnetism of the implanted portion and does not adversely affect the electromagnetic conversion characteristics, and the average height from the substrate surface of the ion implanted portion is lower than the average height from the substrate surface of the non-implanted portion. This is because the flying reference plane of the magnetic head is lowered, and the distance between the non-injection portion, that is, the magnetic recording track and the magnetic head can be reduced.

  Next, after providing 80 nm of a methyl methacrylate resin (PMMA) layer 9 as a resist material on the Ta mask layer precursor, when forming a fine pattern by nanoimprint technology, the size of the resist protrusion is Φ17 nm. A bit patterned media (BPM) was prepared and evaluated in the same manner as in the above-described embodiment except that the resist residue could be embossed concentrically into a 25 nm pitch and 5 nm resist residue. By this manufacturing method, a BPM in which a portion having a relatively high element ratio of the ferromagnetic material exists in an island shape is formed. For the evaluation of electromagnetic conversion characteristics, the method used in DTM is applied simply, and the ratio of the signal output of 10 kiloflux change / mm (254 kFCI) to the signal output at 40 kiloflux change / mm (1016 kFCI) is expressed as output resolution Re ( Re (%) = S (1016 kFCI) / S (254 kFCI) × 100).

  The evaluation results of BPM are shown in FIG. 10 and Table 4, and FIG. 11 and Table 5. FIG. 10 and Table 4 show the relationship between the height of the ion-implanted portion and the glide noise based on the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2). FIG. 11 and Table 5 show the relationship between the height of the ion-implanted portion and the output resolution Re (%) with reference to the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2).

  When the height of the ion-implanted portion 13 with respect to the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2) 7 is -3 nm or more and 3 nm or less, the glide noise is 30 mV or less, and the step is larger than 3 nm. Glide noise becomes larger than 30 mV. That is, as in the case of DTM, the surface of the ion-implanted portion 13 with respect to the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2) 7 is a surface suitable for a magnetic recording medium unless it is in the range of −3 nm to 3 nm. It is not a shape.

In the RW characteristics of the sample in which the height of the ion-implanted portion 13 with respect to the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2) 7 is −3 nm or more and 3 nm or less, the Co-based alloy with respect to Re 48% of the continuous medium When the magnetic layer (recording layer 2) 7 is etched and the ion implantation amount is changed from 1 × 10E + 15 to 1 × 10E + 17 (atoms / cm ² ), the non-implanted portion of the Co-based alloy magnetic layer (recording layer 2) 7 Re becomes 48% or more when the height of the ion implantation part 13 with respect to is set to −0.1 nm or less. As in the DTM results, the magnetism of the implanted portion deteriorates due to ion implantation and does not adversely affect the electromagnetic conversion characteristics, and the average height from the substrate surface of the ion implanted portion is the average from the substrate surface of the non-implanted portion. This is because the flying reference plane of the magnetic head is relatively close by being lower than the height, and the distance between the non-injection portion, that is, the magnetic recording track, and the magnetic head can be reduced.

  In summary, in the ion-implanted recording region separation type magnetic recording medium, the average height from the substrate surface of the ion-implanted portion is 0.1 nm or more and 3 nm or less than the average height from the substrate surface of the non-implanted portion. By lowering the recording area, a recording area separation type magnetic recording medium suitable for increasing the recording density can be obtained.

  The ion-implanted recording region separation type magnetic recording medium includes a mask layer having a fine pattern directly or via one or more thin films on the magnetic recording layer, and the element ratio of the ferromagnetic material is increased by ion implantation. By etching the ion-implanted portion in advance at the time of manufacturing a relatively low recording area separation type magnetic recording medium, the height after ion implantation is relatively 0.1 nm or more and 3 nm as compared with the non-implanted portion. It is obtained by lowering in the following range.

As an ion implantation method, not only the plasma beam method described above but also the ion beam method does not affect the present invention. Further, not only Cr but also Mo, W, V, Nb, Ta, Ti, Zr, Hf, Ru, B, C, Si, Ge, Ar, Kr, Rn, and Xe may be used as the implanted ion species. The means for etching the Co alloy magnetic layer (recording layer 2) in advance before ion implantation is not limited to the Ar ion beam etching described above, but a reaction using a C—F gas such as tetrafluoromethane (CF ₄ ). Even reactive ion etching (RIE) has no effect on the present invention.

  When the magnetic recording isolation region is manufactured by the ion implantation method, in addition to the method of applying a fine mask to the non-implantation region, it is also possible to selectively implant ions into the recording layer by reducing the focal point of the ion beam to about 30 nm or less. It is.

  Further, as a method of lowering the height of the ion implanted portion after ion implantation in the range of not less than 0.1 nm and not more than 3 nm relative to the non-implanted portion, in addition to the method of etching the ion implanted portion in advance, It is also possible to perform implantation while controlling energy and etching.

DESCRIPTION OF SYMBOLS 1 ... Nonmagnetic substrate 2 ... Adhesion layer 3 ... Soft magnetic layer 3a ... Lower soft magnetic layer 3b ... Antiferromagnetic coupling layer 3c ... Upper soft magnetic layer 4 ... Seed layer 5 ... Intermediate layer 6 ... Co-based alloy granular magnetic layer ( Recording layer 1)
7: Co-based alloy magnetic layer (recording layer 2)
8 ... Ta mask layer precursor 82 ... Ta mask layer 9 ... Methyl methacrylate resin (PMMA) layer

Claims (3)

In a magnetic recording medium having a magnetic recording layer formed on a substrate,
In the magnetic recording layer, a relatively high portion and a low portion of the element ratio of the ferromagnetic material are periodically present in the in-plane direction,
The average height from the substrate surface of the portion where the element ratio of the ferromagnetic material is relatively high is higher by 0.1 nm or more and 3 nm or less than the average height from the substrate surface of the portion where the element ratio of the ferromagnetic material is low,
Nonmagnetic elements are ion-implanted in the portion where the element ratio of the ferromagnetic material is relatively low,
The nonmagnetic element extends through the uppermost layer of the magnetic recording layer and partially extends to the magnetic recording layer below the uppermost layer of the magnetic recording layer. A characteristic magnetic recording medium.   2. The magnetic recording medium according to claim 1, wherein the ferromagnetic material has a relatively high element ratio and a low element part of a discrete track type having continuous in the circumferential direction and periodicity in the radial direction. Magnetic recording media.   2. The magnetic recording medium according to claim 1, wherein the ferromagnetic material is of a bit pattern type in which a portion having a relatively high element ratio exists in an island shape.

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