JP2009289337A - Method of manufacturing magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a magnetic recording medium, which comprises a magnetic recording layer where a plurality of magnetic recording elements performing magnetic recording are separated by non-magnetic material. <P>SOLUTION: An intermediate metal layer is exposed in gaps separating respective magnetic recording elements from one another, and non-metallic layers are generated on the top of the magnetic recording elements. When reducing an organo-metallic compound of a non-magnetic metal which is dissolved into a supercritical fluid by the difference between the properties thereof, the non-magnetic metal is selectively deposited on the surface of the intermediate metal layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a magnetic recording medium having a magnetic recording layer in which a plurality of magnetic recording elements for magnetic recording are separated by a nonmagnetic material.

  Magnetic disk drives are in the process of expanding their use and miniaturization, and magnetic recording media mounted in the drive are required to have higher recording density.

  However, with the increase in recording density of magnetic recording media, writing (cross writing) to tracks other than the recording target track (adjacent track) due to the expansion of the recording magnetic field of the magnetic head and / or reading of signals other than the target track (crossing) (Lead) has become a problem.

Therefore, as a candidate for a magnetic recording medium that can realize a further increase in recording density, a discrete track medium and a patterned medium having recording elements in which a magnetic recording layer is magnetically separated have been proposed (see, for example, Patent Document 1). Here, the discrete track medium means a medium in which each of a plurality of concentric recording tracks is magnetically separated from an adjacent recording track. The pattern medium means a medium in which each of a plurality of recording elements corresponding to 1 bit is magnetically separated from an adjacent recording element. In these magnetic recording media, from the viewpoint of stable flying of the magnetic head, it is preferable to fill the gaps between the recording elements with a nonmagnetic material such as SiO ₂ and to flatten the upper surfaces of the recording elements and the filler. It has been.

  As a method for filling the gaps between the recording elements, for example, a film forming method by a dry process such as a sputtering method, a CVD method, or an IBD method is known (see Patent Documents 2, 3, and 4).

  Further, as a planarization means, etching with an etching gas, ion beam etching, chemical polishing (CMP), and the like are known (see Patent Document 2 and Patent Document 4). In addition, a method of flattening by heating a filler deposited on a substrate by a sputtering method to a temperature equal to or higher than its melting point is also performed (see Patent Document 3).

  Furthermore, an attempt has been made to selectively perform CVD under specific conditions to selectively fill a gap between recording elements (see Patent Document 5).

JP-A-9-97419 JP 2006-85899 A JP 2005-1000049 A JP 2006-196143 A JP 2006-92659 A Special table 2003-514115 gazette Eiichi Kondo, Surface Technology, Vol.57, No.10, pp.13-18 (2006)

  However, in the film forming method using the dry process, it is difficult to selectively fill only the gaps between the magnetic recording elements, and the filler is deposited along the original unevenness. Therefore, when the upper surface of the material filling the gap is filled to approximately the same as or higher than the height of the recording element, the filling is stopped, and then the unnecessary filling material on the convex portion is removed. For example, a substantially flat surface that can withstand the flying of the magnetic head cannot be obtained.

  Further, even in the planarization process, it is difficult to control the operation at the level of several nanometers in the conventional CMP method, and there is a problem in productivity.

Further, the selective CVD method described in Patent Document 5 uses a special metal compound that can be gasified, such as tungsten hexafluoride (WF ₆ ) or triisobutylaluminum (Al (C ₄ H ₉ ) ₃ ). It must be used and is not universal.

  On the other hand, when a so-called wet process is used in which the filler is dissolved in a solvent and the solution is applied to the processed surface, the finer the gap between the magnetic recording elements, the more uniform the filling due to the influence of the surface tension. There is a problem that is difficult.

  The present invention has been made in view of the above points, and in a magnetic recording medium having a plurality of magnetic recording elements for magnetic recording, a non-magnetic metal is selectively used in a gap separating each recording element. It has been found that the above object can be achieved by depositing. The present invention has been completed based on such findings.

  Specifically, according to the present invention, an intermediate metal layer is exposed in the gap separating the magnetic recording elements, while a non-metallic layer is formed on the magnetic recording element. The organic metal compound of the nonmagnetic metal dissolved in the supercritical fluid is selectively reduced, and the nonmagnetic metal is selectively and uniformly deposited on the surface of the intermediate metal layer. Thus, a method for producing a magnetic recording medium having a magnetic recording layer in which a plurality of magnetic recording elements for magnetic recording are separated by a non-magnetic material is provided.

Furthermore, the present invention includes that the supercritical fluid in the above production method is supercritical CO ₂ in which hydrogen gas is dissolved. Further, the present invention includes that the nonmagnetic metal in the above production method is a material having conductivity, and that the nonmagnetic metal having conductivity is copper, chromium, titanium, niobium, or tantalum. Including. The present invention includes that the organometallic compound in the above production method is metal acetylacetonate, metal acetate, metal acetylacetate, cyclooctadiene dimethyl metal, metal hexafluoroacetylacetonate, or metal diisobutyrylmethanate. .

  Furthermore, the present invention includes a magnetic recording medium manufactured by any one of the above manufacturing methods.

  According to the method of the present invention, in the manufacture of a magnetic recording medium having a magnetic recording layer in which a plurality of magnetic recording elements for magnetic recording are separated by a nonmagnetic material, a process for removing the surplus filler as described above It is possible to provide a method of manufacturing a magnetic recording medium that can be filled with a nonmagnetic metal uniformly and a magnetic recording medium obtained thereby.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings. The following embodiment is merely an example of the present invention, and those skilled in the art can change the design as appropriate.

  FIG. 1 shows a process of manufacturing a magnetic recording medium having a magnetic recording layer in which a plurality of magnetic recording elements for magnetic recording are separated by a nonmagnetic material by the manufacturing method of the present invention. A magnetic recording medium 1300 manufactured according to the present invention is provided on a substrate 102, an intermediate metal layer 104, a magnetic recording element 103 provided separately on the intermediate metal layer 104, and a magnetic recording element 103. The non-metallic layer 105 and the non-magnetic metallic layer 106 deposited on the intermediate metallic layer 104 between the adjacent magnetic recording elements 103 are included (see FIG. 1 (3)). Hereinafter, it demonstrates for every process.

(Intermediate metal layer formation process)
First, the intermediate metal layer 104 is formed on the substrate 102 (not shown). The intermediate metal layer 104 serves as an underlayer for the magnetic recording element 103 and the nonmagnetic metal layer 106 provided thereafter.

  The substrate 102 used in the present invention is made of a non-magnetic material and can withstand the conditions (solvent, temperature, etc.) used for forming a magnetic recording element 103 described later and pattern processing thereof. Furthermore, it is preferable that it is excellent in dimensional stability. More specifically, the nonmagnetic substrate 102 is made of glass or aluminum as a base material, a silicon single crystal substrate, or the like.

  The intermediate metal layer 104 may be a nonmagnetic metal and is preferably conductive. The intermediate metal layer 104 can be formed using Ru, Os, Pt, Pd, Ir, Rh, Au, or an alloy containing these as main components from the viewpoint of chemical stability.

  The formation of the intermediate metal layer 104 can be performed using any method known in the art such as sputtering (including DC magnetron sputtering, RF magnetron sputtering, etc.), vacuum deposition, and the like. The intermediate metal layer usually has a thickness of 0.1 nm to 20 nm. By setting the film thickness within such a range, it is possible to impart characteristics necessary for high-density recording to the magnetic recording layer without deteriorating the magnetic characteristics and electromagnetic conversion characteristics of the magnetic recording layer.

  In the present invention, optionally, a nonmagnetic underlayer or soft magnetic underlayer (SUL) for controlling the crystal structure of the magnetic recording layer to improve its performance between the substrate 102 and the intermediate metal layer 104. Layer) and / or a seed layer (both not shown).

  The nonmagnetic underlayer can be formed using a nonmagnetic material containing Cr, such as Ti or CrTi alloy.

  The SUL layer is a layer for concentrating the perpendicular magnetic field on the magnetic recording layer. Soft magnetic materials that can be used for the SUL layer include crystalline materials such as FeTaC and Sendust (FeSiAl) alloys; microcrystalline materials such as FeTaC, CoFeNi, and CoNiP; Contains crystalline material. Although the optimum value of the film thickness of the SUL layer varies depending on the structure and characteristics of the magnetic head used for recording, it is preferably about 10 nm to 500 nm from the viewpoint of productivity.

  The seed layer is a layer for controlling the crystal structure of the magnetic recording layer. Materials that can be used to form the seed layer include permalloy materials such as NiFeAl, NiFeSi, NiFeNb, NiFeB, NiFeNbB, NiFeMo, and NiFeCr; Co to permalloy materials such as CoNiFe, CoNiFeSi, CoNiFeB, and CoNiFeNb Furthermore, the added material; Co; or Co-based alloys such as CoB, CoSi, CoNi, CoFe and the like are included. The seed layer desirably has a film thickness sufficient to control the crystal structure of the magnetic recording layer. In general, the seed layer desirably has a film thickness of 3 nm to 50 nm.

  The above-described underlayer, SUL layer, and seed layer are formed using any method known in the art such as sputtering (including DC magnetron sputtering, RF magnetron sputtering, etc.), vacuum deposition, etc. can do.

(Magnetic recording layer formation process)
Next, the magnetic recording material layer 113 is formed on the intermediate metal layer 104. The magnetic recording material layer 113 is partially removed by a method described later to form a plurality of magnetic recording elements 103 that perform magnetic recording.

  In order to perform perpendicular magnetic recording, the magnetic recording material layer 113 has an easy magnetization axis (c-axis having a hexagonal close-packed (hcp) structure) of the material of the magnetic recording material layer 113 so that the surface of the recording medium (that is, for an information recording medium) It must be oriented perpendicularly to the main plane of the substrate.

Magnetic materials that can be used for the magnetic recording material layer 113 include alloy materials such as CoPt, CoCrPt, CoCrPtB, and CoCrPtTa. The magnetic recording material layer 113 can be preferably formed using a ferromagnetic material of an alloy containing at least Co and Pt. Alternatively, when a discrete track medium is formed, the magnetic recording material layer 113 is formed using a material having a granular structure in which magnetic crystal grains are dispersed in a matrix of nonmagnetic oxide or nonmagnetic nitride. May be. Materials having a granular structure that can be used include, but are not limited to, CoPt—SiO ₂ , CoCrPtO, CoCrPt—SiO ₂ , CoCrPt—Al ₂ O ₃ , CoPt—AlN, CoCrPt—Si ₃ N _4, etc. It is not a thing. When a material having a granular structure is used, magnetic separation between magnetic crystal grains adjacent in the magnetic recording material layer 113 is promoted to improve magnetic recording characteristics such as noise reduction, SNR improvement and recording resolution improvement. Can be planned.

  The thickness of the magnetic recording material layer 113 (that is, the thickness of the magnetic recording layer) is not particularly limited. However, from the viewpoint of improving productivity and recording density, the magnetic recording material layer 113 preferably has a thickness of 30 nm or less, more preferably 15 nm or less. The magnetic recording material layer 113 can be formed using any method known in the art, such as sputtering (including DC magnetron sputtering, RF magnetron sputtering, etc.), vacuum deposition, and the like.

(Non-metal layer forming process)
Next, a nonmetallic material layer 115 is formed on the magnetic recording material layer 113. The nonmetallic material layer 115 is partially removed together with the magnetic recording material layer 113 by a method to be described later to form a nonmetallic layer 105 that protects the upper surface of the magnetic recording element 103.

  The non-metallic material layer 115 may be any non-metallic material that is unlikely to cause a reduction reaction of an organic metal on the surface, such as carbon (amorphous carbon or the like), or various thin film materials known as materials for magnetic recording medium protective films. Can be used.

  The formation of the non-metallic material layer 115 can be performed using any method known in the art, such as sputtering (including DC magnetron sputtering, RF magnetron sputtering, etc.), vacuum deposition, and CVD. it can. The film thickness of the nonmetallic material layer 115 is not particularly limited, but is preferably 2 to 15 nm from the viewpoint of increasing the density of the obtained magnetic recording medium.

(Partial removal process of non-metal layer and magnetic recording layer)
Next, the magnetic recording material layer 113 and a part of the non-metallic material layer 115 are removed by an arbitrary method (not shown) to form the magnetic recording element 103 and the intermediate metal layer 104 is exposed (FIG. 1B). ).

  As a method for removing a part of the magnetic recording material layer 113 and the non-metallic material layer 115, any method known in the art such as a dry etching method can be used. The gas used for dry etching can be appropriately selected by those skilled in the art depending on the material used for the magnetic recording material layer 113 and / or the non-metallic material layer 115. The removal process is performed until at least the intermediate metal layer 104 is exposed.

  Further, by performing the removal step along a predetermined pattern, it is possible to form the magnetic recording element 103 separated into desired sections and the non-metal layer 105 protecting the upper surface thereof. For example, an optional mask layer (not shown) is provided on the non-metallic material layer 115, and a desired layer is formed on the mask layer by an arbitrary method known in the art such as a photolithographic method and / or a nanoimprint method. After transferring the pattern, a part of the magnetic recording material layer 113 and the nonmetallic material layer 115 is removed by dry etching to form the magnetic recording element 103 and the nonmetallic layer 105 separated by a gap having a desired pattern. Also good. For example, in the present invention, in the case of a discrete track medium, the magnetic recording elements 103 having a track width of 15 to 50 nm can be separated and formed at an interval of 15 to 50 nm. In the case of a patterned medium, magnetic recording elements having a bit diameter of 5 to 30 nm can be separated and formed at intervals of 5 to 30 nm.

(Non-magnetic metal filling process)
The organometallic compound dissolved in the supercritical fluid is selectively reduced on the intermediate metal layer 104 exposed in the gap separating the magnetic recording element 103 and the nonmetallic layer 105 to form the nonmagnetic metal layer 106. To do.

  The organometallic compound that is reduced to form the nonmagnetic metal layer 106 includes an organometallic compound having copper, chromium, titanium, niobium, tantalum, or the like as a central metal. Preferably, the organometallic compound comprises metal acetylacetonate, metal acetate, metal acetylacetate, cyclooctadiene dimethyl metal, metal hexafluoroacetylacetonate, metal diisobutyrylmethanate containing the aforementioned metals.

The supercritical fluid that can be used in the present invention is not particularly limited as long as it dissolves the organometallic compound and the reduction reaction of the organometallic compound proceeds therein. Carbon dioxide (CO ₂ ) Known supercritical fluids such as water, ethane, propane, butane, heptane, dimethyl ether and ethanol can be used. From the viewpoints of operability, solvent ability as a supercritical fluid, and / or economy, CO ₂ is preferable.

Further, a reducing agent such as hydrogen may be added to the supercritical fluid in order to promote the reduction reaction of the organometallic compound. The reducing agent is preferably hydrogen. The amount of reducing agent added is relative to the supercritical fluid. 10 ppm to 2,000 ppm is preferred.

  FIG. 2 is an outline of a nonmagnetic metal filling apparatus using a supercritical fluid used in the present embodiment. Hereinafter, a preferred embodiment of the non-magnetic metal selective deposition process using a supercritical fluid will be described in more detail with reference to FIG.

(1) Liquid CO ₂ contained in a siphon type high pressure vessel 201 is taken out from the high pressure vessel 201 and supplied to the reaction chamber 207 by the high pressure pump 204. Here, when a part of the extracted CO ₂ is vaporized by being depressurized during the extraction, the extracted CO ₂ may be completely liquefied by the cooling unit 203. When a small amount of hydrogen (reducing agent) is added to the supercritical fluid to promote the reduction reaction of the organometallic compound, hydrogen (reducing agent) may be mixed with liquid CO ₂ through the mixing device 205. .

  (2) In the reaction chamber 207, the processing medium 1200 provided with the magnetic recording element 103 and the non-metal layer 105 separated by the voids having a desired pattern formed by the above process and an appropriate amount of the organometallic compound are installed.

(3) The reaction chamber 207 is filled with liquid CO ₂ , the valves 206a and 206b are closed, and then heated by the heater 208 to generate a supercritical CO ₂ fluid. The heating temperature is preferably 150 to 300 ° C., and the pressure in the reaction chamber is preferably 10 to 15 MPa. The pressure is based on the value of a pressure gauge (not shown) provided in the reaction chamber. When the internal pressure becomes higher than the target pressure due to the heating of CO ₂ , the valve 206b is opened, and the pressure regulator You may adjust to a desired pressure in 209.

(4) The organometallic compound in the reaction chamber 207 gradually dissolves in the supercritical CO ₂ fluid and comes into contact with the processing medium 1200. Since the supercritical fluid has zero surface tension (Non-Patent Document 1), even a void having a fine pattern formed on the surface of the processing medium 1200 can be uniformly infiltrated. Then, the organometallic compound dissolved in the supercritical CO ₂ fluid comes into contact with the conductive intermediate metal layer 104, and the reduction reaction of the organometallic compound is preferentially started on the intermediate metal layer 104. On the other hand, on the non-metal layer 105 provided on the upper surface of the magnetic recording element 103, the reduction reaction of the organometallic compound does not proceed, so that the non-magnetic metal is not deposited. As a result, the nonmagnetic metal layer 106 can be selectively formed only on the intermediate metal layer 104 exposed between the adjacent magnetic recording element 103 and the nonmetal layer 105.

Further, the metal filling apparatus using the supercritical CO ₂ fluid is not limited to the batch type configuration shown in FIG. 2, and may be, for example, a type (not shown) that flows the supercritical CO ₂ fluid.

  Further, optionally, the surface of the magnetic recording medium 1300 thus obtained may be polished to adjust the substrate surface shape.

  Finally, a protective layer and / or a lubricant layer may be optionally formed so as to cover the nonmetallic layer 105 and the nonmagnetic layer 107. The protective layer is a layer for protecting each constituent layer below the magnetic recording layer below it. The protective layer can be formed using various thin film materials known as carbon (amorphous carbon or the like) or a material for a magnetic recording medium protective film. The protective layer can be generally formed using a sputtering method (including a DC magnetron sputtering method, an RF magnetron sputtering method, etc.), a vacuum deposition method, a CVD method, or the like.

  The lubricant layer is a layer for providing lubrication when the recording / reading head is in contact with the magnetic recording medium. For example, the lubricant layer is a perfluoropolyether liquid lubricant or known in the art. It can be formed using a variety of liquid lubricant materials. The liquid lubricant layer can be formed using any coating method known in the art such as a dip coating method or a spin coating method.

(Example 1)
A silicon substrate 102 having a diameter of 65 mm and a thickness of 0.635 mm and a nominal size of 2.5 inches is cleaned and dried, and is then sputtered on the main surface to form an underlayer made of CrTi with a thickness of 2 nm, a thickness of 40 nm. Then, a SUL layer made of CoZrNd, a seed layer made of CoNiFeSi with a thickness of 16 nm, an intermediate metal layer 104 made of Ru with a thickness of 12 nm are formed, and then a CoCrPt—SiO ₂ magnetic recording material layer 113 with a thickness of 20 nm is formed. An amorphous carbon nonmetallic material layer 115 having a thickness of 10 nm was formed to be a starting medium 1100 to be processed.

A patterned resist layer was formed on the surface of the starting medium 1100 using a nanoprint method. First, a resist called spin-on-glass (SOG) was spin-coated on the surface of the starting medium 1100 to be processed. A Ni stamper produced by electroforming was pressed at a pressure of 15 kN / cm ² (150 MPa) over 120 seconds against the obtained coating film to form a resist layer having a concavo-convex pattern. The film thickness at the convex portion of the resist layer was 50 nm. Subsequently, the SOG remaining film remaining in the pattern recess of the resist layer was removed by oxygen ashing to expose the nonmetallic material layer 115. Next, the nonmetallic material layer 115 exposed by Ar milling and the magnetic recording material layer 113 therebelow were removed to form a plurality of magnetic recording elements 103. Here, the end point of Ar milling was determined by confirming the exposure of the intermediate metal layer 104 using an end point monitor. Since Ru is chemically stable, it is advantageous to use Ru as the intermediate metal layer 104. Each of the obtained plurality of magnetic recording elements 103 was a dot having a diameter of 20 nm, and was arranged at an interval of 20 nm.

Next, the nonmagnetic metal was deposited on the exposed intermediate metal layer 104 of the processing medium 1200 obtained above using the supercritical fluid filling apparatus shown in FIG. Specifically, ten processing media 1200 are installed on a support jig made of Teflon (registered trademark) in a reaction chamber 207 having a volume of 2.5 L, and at the same time, Teflon (registered) containing 10 g of copper (II) acetylacetonate. (Trademark) beaker was also installed in the reaction chamber 207. The amount of copper (III) acetylacetonate is not limited to 10 g, but may be an amount that can sufficiently fill the reduced voids formed in the pattern for separating the magnetic recording element 103 with the reduced metallic copper. After sealing the reaction chamber 207, the valve 206 a was opened, and the reaction chamber 207 was filled with liquid CO _{2 in} which hydrogen gas at 7.4 MPa was dissolved at 40 ° C. Thereafter, the temperature in the chamber was raised to 230 ° C. by the heater 208 for heating to generate a supercritical CO ₂ fluid. The pressure at this time was 12 MPa. The temperature and pressure were maintained for 60 seconds, and the gap between the magnetic recording elements 103 of the processing medium 1200 was filled with metallic copper.

Thereafter, the temperature of the reaction chamber 207 was lowered to 150 ° C., and CO ₂ was exhausted through the valve 206 _b and the pressure regulator 209.

  Subsequently, back etching with Ar gas was performed to flatten the surface, and the surface arithmetic average roughness Ra (JIS B0601: 2001) was adjusted to 0.2 nm or less. Further, a 3 nm thick protective layer made of amorphous carbon (a-C) was formed thereon. Finally, a 2 nm thick lubricant layer made of a lubricant was formed using a dip method to obtain a magnetic recording medium.

  By the method described above, a smooth surface with high flying stability was obtained in a short time, and as a result, an inexpensive and highly reliable magnetic recording medium was obtained. The flying stability is obtained when the rotational speed of the signal from the piezoelectric element when the test head equipped with the piezoelectric element travels on the magnetic recording medium and collides with the convex part of the magnetic recording medium is reduced. By investigating what is coming (avalanche test).

(Example 2)
Instead of copper (II) acetylacetonate described in Example 1, chromium (III) acetylacetonate, titanium (III) acetylacetonate, niobium (III) acetylacetonate, and tantalum (III) acetylacetonate, respectively. The voids formed in a pattern on the surface of the processing medium 1200 were filled with metal titanium, metal chromium, metal titanium, metal niobium, and metal tantalum, respectively. Other conditions are the same as in Example 1. Also in this case, good floating stability was shown.

It is the figure which showed the manufacturing method of the magnetic recording medium of this invention. It is the figure which showed the outline | summary of the filling apparatus of the nonmagnetic material by the supercritical fluid used for this embodiment.

Explanation of symbols

102 Substrate 103 Magnetic recording element 104 Intermediate metal layer 105 Non-metallic layer 106 Non-magnetic metal layer 113 Magnetic recording material layer 115 Non-metallic material layer 1100 Processing start medium 1200 Processing medium 1300 Magnetic recording medium 201 High pressure vessel 203 Cooling unit 204 High pressure pump 205 Mixer 206a Valve 206b Valve 207 Reaction chamber 208 Heater 209 Pressure regulator

Claims (6)

Forming an intermediate metal layer on the substrate;
Forming a magnetic recording material layer on the intermediate metal layer;
Forming a non-metallic material layer on the magnetic material layer;
Removing a part of the non-metallic material layer and the magnetic recording material layer to form a plurality of magnetic recording elements and exposing the intermediate metal layer; and a supercritical fluid in which the organometallic compound of the non-magnetic metal is dissolved. And reducing the organometallic compound to a metal, thereby selectively depositing a non-magnetic metal material on the exposed intermediate metal layer, and separating the plurality of magnetic recording elements with the non-magnetic metal material. And a step of forming a magnetic recording layer. The method of manufacturing a magnetic recording medium according to claim 1, wherein the supercritical fluid is supercritical CO ₂ in which hydrogen gas is dissolved.   3. The method of manufacturing a magnetic recording medium according to claim 1, wherein the non-magnetic metal has conductivity.   4. The method of manufacturing a magnetic recording medium according to claim 3, wherein the nonmagnetic metal is copper, chromium, titanium, niobium, or tantalum.   The organic metal compound is metal acetylacetonate, metal acetate, metal acetylacetate, cyclooctadiene dimethyl metal, metal hexafluoroacetylacetonate, or metal diisobutyrylmethanate. A method of manufacturing a magnetic recording medium.   A magnetic recording medium manufactured by the method according to claim 1.

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