JP2012022741A - Master information carrier and manufacturing method of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a master information carrier excellent in durability, which repetitively is used for magnetically writing and transferring information signals to be transferred to a magnetic recording medium.SOLUTION: The master information carrier comprises: a magnetic layer 101 written with information signals to be magnetically transferred to a magnetic recording medium; and a lubricant layer 103 disposed on the uppermost surface thereof. The lubricant layer 103 contains a compound in which two or more hydrogen atoms of a benzene ring are substituted with perfluoro ether groups having two or more hydroxyl groups at terminals. A master information carrier M is a master information carrier in which the applied amount of siloxane on the surface of the master information carrier M, which is exposed to air containing octamethylcyclotetrasiloxane for 8 hours or more under an atmospheric pressure, is less than or equal to four times the applied amount before being exposed.

Description

  The present invention relates to a master information carrier in which an information signal to be magnetically transferred to a magnetic recording medium such as a servo signal is written, and a method for manufacturing a magnetic recording medium to magnetically transfer an information signal to a magnetic recording medium using the master information carrier In particular, the present invention relates to a master information carrier that can be used repeatedly for magnetic transfer.

  Currently, in a hard disk drive (hard disk drive) which is a kind of magnetic recording / reproducing apparatus, the recording density is increased by 1.5 times or more per year, and it is said that the increasing trend will continue in the future. With the increase in the recording density of hard disk devices, development of magnetic heads and magnetic recording media suitable for increasing the recording density is in progress. In the latest magnetic recording media, the track density has reached 320 kTPI.

  In a magnetic recording medium having a high track density, the tracking servo technology of the magnetic head plays an important role in order to accurately scan the magnetic head over the track. In current hard disk drives, information signals such as servo signals for tracking and servo signals such as address information signals and reproduction clock signals are recorded at regular angular intervals during one round of the disk. Control is performed to correct the position of the magnetic head so that the magnetic head accurately scans the track while detecting the position of the magnetic head based on these information signals reproduced at regular intervals from the magnetic head. It has been broken.

The servo signal and the like described above serve as a reference signal for the magnetic head to accurately scan the track. For this reason, high positioning accuracy is required for writing servo signals and the like.
In a conventional hard disk drive manufacturing site, a servo signal recording device (hereinafter referred to as a servo writer) incorporating a highly accurate position detection device is used to write a servo signal to a magnetic recording medium. In general, the servo writer has a structure in which a large number of magnetic recording media are chucked on one spindle and servo signals and the like are simultaneously written on the multiple magnetic recording media in order to increase productivity.

When writing a servo signal using a servo writer, it takes a long time to write a signal over a large number of tracks while positioning the magnetic head with high accuracy, and there is a problem that productivity is low. In order to solve this problem, the number of magnetic recording media on which servo signals are simultaneously written may be increased.
However, if the number of servo writers is increased in order to increase the number of magnetic recording media on which servo signals are simultaneously written, a large cost is required for maintenance and management of the servo writers. Also, if the length of the servo writer spindle is increased and the number of magnetic recording media that can be chucked at the same time is increased, the magnetic recording medium is more likely to blur when writing servo signals, and the servo signal writing accuracy to the magnetic recording media is improved. descend. For this reason, there is a limit to the number of magnetic recording media that can be chucked on one spindle, and it has been difficult to increase the number of magnetic recording media that can be chucked simultaneously.

Further, the problem in increasing the number of servo writers described above and the problem in increasing the number of magnetic recording media that can be chucked at the same time become more serious as the track density of the magnetic recording medium increases and the number of tracks increases.
Thus, a technique for writing a servo signal or the like on a magnetic recording medium without using a servo writer has been proposed. Specifically, the information signal written on the master information carrier is magnetically recorded by superimposing a master information carrier on which an information signal such as a servo signal is written and a magnetic recording medium, and applying energy for transfer from the outside. Techniques for magnetic transfer to a medium have been proposed.

For example, in Patent Document 1 and Patent Document 2, the surface of the master information carrier surface is brought into contact with the surface of the magnetic recording medium by bringing the surface of the master information carrier in which the concavo-convex shape corresponding to the information signal is formed on the surface of the substrate. A technique for recording a magnetic pattern corresponding to a concavo-convex shape on a magnetic recording medium is described.
When performing magnetic transfer of an information signal to a magnetic recording medium using a master information carrier in which an information signal such as a servo signal to be magnetically transferred to the magnetic recording medium is written, magnetic recording is performed as compared to using a servo writer. The information signal can be written to the medium in a short time.
Further, Patent Document 1 describes burnishing as a technique for removing protrusions present on the surface of a magnetic recording medium.

JP 2001-006169 A JP 10-40544 A

A master information carrier on which an information signal used for magnetic transfer is written is very expensive, but can be used repeatedly when transferring an information signal to a magnetic recording medium. For this reason, the number of times that the master information carrier can be repeatedly used for magnetic transfer (the number of times it can be used) is increased to lower the manufacturing unit price of the magnetic recording medium, and the master information for commercial production of the magnetic recording medium on which the information signal is written. There is a need to be able to apply the carrier.
As a method of increasing the number of times the master information carrier can be used, the surface of the master information carrier is suppressed by removing protrusions and dust on the surface of the magnetic recording medium before performing magnetic transfer. A way to do this is conceivable. As a method for removing protrusions, dust, and the like on the surface of the magnetic recording medium, there are a varnishing process, a wiping process using a woven cloth, and wet cleaning.

  However, even if protrusions and dust on the surface of the magnetic recording medium are removed before the magnetic transfer, the transfer pattern may be incomplete before the master information carrier is damaged due to wear. For this reason, it has been difficult for the conventional technology to increase the number of times that the master information carrier can be used to a number sufficient to be applied to commercial production.

The present invention has been proposed in view of such circumstances, and an information signal to be magnetically transferred is written on a magnetic recording medium, and the master having excellent durability that can be used repeatedly for magnetic transfer is sufficiently large. An object is to provide an information carrier.
Another object of the present invention is to provide a method of manufacturing a magnetic recording medium, which includes a step of magnetically transferring an information signal to the magnetic recording medium using the master information carrier of the present invention that is sufficiently usable. .

The present inventors have intensively studied to solve the above problems. As a result, it was found that by repeatedly performing magnetic transfer on the magnetic recording medium, dirt is gradually accumulated on the surface of the master information carrier, and the transfer pattern transferred to the magnetic recording medium may become incomplete. .
Furthermore, the present inventor has repeatedly investigated the cause of contamination accumulated on the surface of the master information carrier. As a result, the main cause of contamination is a lubricant having a weak adhesive force with the surface of the magnetic recording medium, called freerubb, among the lubricants applied to the surface of the magnetic recording medium, and performs magnetic transfer to the magnetic recording medium. Each time, it was found that the magnetic recording medium was transferred and accumulated little by little on the surface of the master information carrier. And it became clear that this free lube easily aggregated, and this aggregate gradually absorbed impurities in the atmosphere, which corroded the surface of the master information carrier, and this corrosive substance was found to be a cause of contamination.

  In order to solve the problem of contamination of the master information carrier due to the lubricant applied to the surface of the magnetic recording medium, an information signal is sent to the magnetic recording medium before applying the lubricant to the surface of the magnetic recording medium. Magnetic transfer may be performed. However, even if the information signal is magnetically transferred to the magnetic recording medium before the lubricant is applied to the surface, it is difficult to increase the number of usable master information carriers that can be repeatedly used for magnetic transfer as shown below. there were.

  That is, the magnetic recording medium usually has a structure in which a magnetic layer, a protective layer, and a lubricating layer are sequentially laminated on a substrate. Therefore, when the information signal is magnetically transferred to the magnetic recording medium before the lubricant is applied to the surface and the lubricant layer is formed, the surface on which the information signal is magnetically transferred is provided to prevent damage to the magnetic layer. Thus, a hard protective layer made of a hard carbon film or the like is exposed. For this reason, when magnetically transferring an information signal to the magnetic recording medium, the protective layer exposed on the surface of the magnetic recording medium and the master information carrier come into contact with each other, and the wear of the master information carrier is promoted. Therefore, if the information signal is magnetically transferred to the magnetic recording medium before applying the lubricant to the surface, the problem of contamination of the master information carrier due to the lubricant can be solved, but the magnetic force after applying the lubricant to the surface can be solved. Compared to the case where the information signal is magnetically transferred to the recording medium, it is difficult to increase the number of times the master information carrier that can be used repeatedly for magnetic transfer can be used.

Therefore, the present inventors have intensively studied to make a master information carrier that hardly accumulates dirt on the surface.
As a result, it has been found that it is only necessary to provide a lubricant layer that is difficult to get dirty on the outermost surface of the master information carrier, and the present invention has been completed. That is, the present invention provides the following means.

  (1) A master information carrier comprising a magnetic layer on which an information signal to be magnetically transferred to a magnetic recording medium is written, and a lubricant layer disposed on the outermost surface, wherein the lubricant layer is a hydrogen of a benzene ring. A compound containing two or more substituted atoms and a perfluoroether group having two or more hydroxyl groups at its end, and after exposing the master information carrier to air containing octamethylcyclotetrasiloxane at atmospheric pressure for at least 8 hours The master information carrier is characterized in that the adhesion amount of siloxane on the surface of the master information carrier is not more than 4 times the adhesion amount before exposure.

(2) The master information carrier according to (1), wherein the compound has a chemical formula represented by the following formula (1) and an average molecular weight is in the range of 1000 to 5000.
However, in following formula (1), p and q show an integer.

(3) The master information carrier according to (1) or (2), wherein the lubricant layer has a thickness in a range of 5 to 30 mm.
(4) The master information carrier according to any one of (1) to (3), wherein the magnetic layer includes a convex portion having a shape corresponding to the information signal.

(5) a step of forming a magnetic layer on the substrate; and an information signal writing step of writing an information signal to the magnetic layer, wherein in the information signal writing step, a plurality of the substrates on which the magnetic layer is formed A method for manufacturing a magnetic recording medium, wherein the information signal is repeatedly magnetically transferred to the magnetic layer using the master information carrier according to any one of (1) to (4).
(6) The method for manufacturing a magnetic recording medium according to (5), wherein a protective layer and a lubricating layer are sequentially stacked on the magnetic layer before the information signal writing step.
(7) In the information signal writing step, the information signal is magnetically transferred to the magnetic layer of one or more of the substrates, and then the information signal is magnetically transferred to the magnetic layer of the next substrate. The method of manufacturing a magnetic recording medium according to (5) or (6), wherein a step of washing the master information carrier is performed until or before performing the information signal writing step.

  The master information carrier of the present invention is a master information carrier comprising a magnetic layer in which an information signal to be magnetically transferred to a magnetic recording medium is written, and a lubricant layer disposed on the outermost surface. And a compound obtained by substituting two or more hydrogen atoms of a benzene ring and a perfluoroether group having two or more hydroxyl groups at its ends, and the master information carrier is in an atmosphere containing octamethylcyclotetrasiloxane at 8 at atmospheric pressure. Since the amount of siloxane deposited on the surface of the master information carrier after exposure for more than 4 hours is less than 4 times the amount deposited before exposure, dirt is unlikely to accumulate on the surface. That is, the lubricant layer of the present invention makes it difficult to transfer the freerub contained in the lubricant applied to the surface of the magnetic recording medium, and takes in the slightly transferred freerub into the lubricant layer without agglomerating, and this It makes it difficult to absorb the impurities in the atmosphere to the incorporated freerub. In addition, the lubricant layer of the present invention has a strong effect of protecting the master information carrier from impurities in the atmosphere.

  Therefore, even if the magnetic recording medium on which the information signal is written has a lubricant layer formed by applying a lubricant on the outermost surface, the master information carrier of the present invention can be used repeatedly for magnetic transfer. It can be used many times and has excellent durability.

  The method for producing a magnetic recording medium of the present invention is a method for magnetically transferring the information signal repeatedly to the magnetic layers of the plurality of substrates on which a magnetic layer is formed, using the master information carrier of the present invention. Therefore, the number of times that one master information carrier can be used is sufficiently increased. As a result, according to the method for manufacturing a magnetic recording medium of the present invention, the production cost of the magnetic recording medium can be greatly reduced.

FIG. 1 is an enlarged sectional view showing a part of an example of the master information carrier of the present invention. FIG. 2 is a cross-sectional view showing an example of a magnetic recording medium manufactured by using the magnetic recording medium manufacturing method of the present invention. FIG. 3 is a cross-sectional view for explaining a process of writing an information signal to the magnetic layer of the magnetic recording medium in the method for manufacturing a magnetic recording medium of the present invention.

  Hereinafter, a master information carrier and a method of manufacturing a magnetic recording medium according to the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make the features easy to understand, the portions that become the features may be schematically shown for convenience, and the dimensional ratios of the portions are not always the same as the actual ones.

"Master information carrier"
FIG. 1 is an enlarged sectional view showing a part of an example of the master information carrier of the present invention. A master information carrier M shown in FIG. 1 includes a base material 100, a magnetic layer 101 formed on the base material 100, a protective layer 102 formed on the magnetic layer 101, and a lubrication formed on the protective layer 102. And an agent layer 103. As shown in FIG. 1, the lubricant layer 103 is disposed on the outermost surface of the master information carrier M.

The substrate 100 is made of a material such as Ni or a Ni alloy that can be precisely processed, and is preferably made of Ni. As shown in FIG. 1, the base material 100 is provided with a base material convex part 100a and a base material concave part 100b on the surface.
In addition, an underlayer made of a Ru film or the like may be provided between the base material 100 and the magnetic layer 101.

As shown in FIG. 1, the magnetic layer 101 is formed along the shape of the base convex portion 100 a and the base concave portion 100 b formed on the surface of the base 100. Thus, the magnetic layer 101 is written with an information signal to be magnetically transferred to the magnetic recording medium. Of the magnetic layer 101 formed on the substrate 100, the magnetic layer projection 101a formed on the substrate projection 100a of the substrate 100 has a shape corresponding to an information signal to be magnetically transferred to the magnetic recording medium. And used for magnetic transfer of magnetic recording media. Also, in the magnetic layer 101, the magnetic layer recess 101b formed on the substrate recess 100b of the substrate 100 is a portion that does not come into contact with the magnetic recording medium when magnetically transferred to the magnetic recording medium. It is not used for magnetic transfer.
As the magnetic layer 101, a conventionally known material can be used, and specifically, a material that can be used for a magnetic layer of a magnetic recording medium to be described later can be used.

  The protective layer 102 is provided between the magnetic layer 101 and the lubricant layer 103. The protective layer 102 prevents corrosion of the magnetic layer 101 of the master information carrier M, enhances the wear resistance of the master information carrier M, and increases the number of usable times that can be used for repeated magnetic transfer of the master information carrier M. is there. As the protective layer 102, a conventionally known material can be used. For example, a hard carbon film having a thickness of about several nm can be used. When the protective layer 102 is made of a carbon film, it is chemically stable and highly resistant.

  The lubricant layer 103 is a compound obtained by substituting two or more hydrogen atoms of a benzene ring and a perfluoroether group having two or more hydroxyl groups at the end (hereinafter, simply referred to as “perfluoroether group having two hydroxyl groups at the ends”). In some cases, it is referred to as “bound compound”). When such a lubricant layer 103 is disposed on the outermost surface of the master information carrier M and exposed to an atmosphere containing a siloxane compound, the amount of adsorption to the surface of the master information carrier M is low. Specifically, the lubricant layer 103 has an exposure amount of siloxane on the surface of the master information carrier M after the master information carrier M is exposed to air containing octamethylcyclotetrasiloxane at atmospheric pressure for 8 hours or more. It becomes 4 times or less of the adhesion amount before carrying out.

  The lubricant layer 103 does not cover the entire surface of the protective layer 102, but is formed in an island shape or a mesh shape on the surface of the protective layer 102. Therefore, the environmental pollutant easily passes through the lubricant layer 103 and reaches the surface of the protective layer 102 therebelow. When a “polar site” exists on the surface of the protective layer 102, such as when the protective layer 102 is made of a carbon film, environmental pollutants adhere to the “polar site” of the protective layer 102. Environmental pollutants adhering to the protective layer 102 aggregate at that location to contaminate the master information carrier M, pass through the protective layer 102 and reach the magnetic layer 101, corrode the magnetic layer 101, and lower the magnetic properties. . Further, the corrosive matter of the magnetic layer 101 diffuses on the surface of the protective layer 102 and contaminates the magnetic recording medium when magnetically transferred to the magnetic recording medium using the master information carrier M.

Examples of environmental pollutants that adhere to the protective layer 102 include ionic impurities. Examples of metal ions contained in ionic impurities include sodium ions and potassium ions. Examples of inorganic ions contained in ionic impurities include silicon ions, chlorine ions, HCO ₃ ions, HSO ₄ ions, sulfate ions, ammonia ions, oxalate ions, and formate ions.

In the present embodiment, the lubricant layer 103 contains a compound in which two or more hydrogen atoms of a benzene ring and a perfluoroether group having two or more hydroxyl groups at its ends are substituted, and the skeleton of the compound is in the skeleton of the compound. Contains a hydroxyl group (—OH) and a benzene ring (phenylene (—C ₆ H ₄ —)) as highly polar functional groups. The functional group having a large polarity contained in the lubricant layer 103 is firmly formed as a “polar site” that is a functional group on the surface of the protective layer 102 by forming the lubricant layer 103 on the outermost surface of the master information carrier M. Are combined. In the master information carrier M of the present embodiment, the lubricant layer 103 and the protective layer 102 are firmly bonded, so that the resistance against environmental pollutants on the surface of the master information carrier M is increased, and magnetic recording is performed. There is an effect that the free lube from the medium W is not brought close. In addition, even if free lubricant transferred from the magnetic recording medium is mixed in the lubricant layer 103, the free lubricant is uniformly taken into the lubricant layer 103, and dirt via the free lubricant is difficult to accumulate. .

In the master information carrier M of the present embodiment, as a method for evaluating the bonding force between the lubricant layer 103 and the protective layer 102, the amount of siloxane adsorbed on the surface of the master information carrier M can be used.
Siloxane is a compound having silicon and oxygen as a skeleton, and is a general term for those having Si—O—Si bonds (siloxane bonds). Siloxane can be represented by the general formula R ₃ SiO— (R ₂ SiO) n—SiR ₃ (R represents an alkyl group).

  In this embodiment, when measuring the adsorption rate of siloxane on the surface of the master information carrier M, octamethylcyclotetrasiloxane is used as the siloxane. Octamethylcyclotetrasiloxane is bonded to “polar sites” of the protective layer 102, and when a polar functional group contained in the lubricant layer 103 is bonded to “polar sites”, It is something that is not bound to "site".

  Therefore, the master information carrier M is exposed to an atmosphere containing octamethylcyclotetrasiloxane, and the amount of octamethylcyclotetrasiloxane adsorbed on the surface of the master information carrier M is examined. It is possible to quantify the binding force with the highly polar functional group contained in the lubricant layer 103 and to quantify the resistance of the master information carrier M to environmental pollutants.

The amount of siloxane adsorbed on the surface of the master information carrier M can be measured using a secondary ion mass spectrometer or the like.
In this embodiment, the master information carrier M is exposed to air containing octamethylcyclotetrasiloxane at atmospheric pressure for 8 hours or more. By setting the exposure time to 8 hours or longer, octamethylcyclotetrasiloxane can be reliably bonded to the “polar site” of the protective layer 102 to which the functional group having a large polarity contained in the lubricant layer 103 is not bonded. Therefore, the adsorption amount of siloxane is stabilized. Therefore, the amount of siloxane adsorbed on the surface of the master information carrier M can be used as a reliable method for evaluating the bonding force between the lubricant layer 103 and the protective layer 102.

  The ratio of octamethylcyclotetrasiloxane in the air when the master information carrier M is exposed to air containing octamethylcyclotetrasiloxane is preferably 0.1 to 5% by volume, and 0.2 to 2 The range of volume% is more preferable, and the range of 0.5 to 1 volume% is particularly preferable. If the proportion of octamethylcyclotetrasiloxane is less than 0.1% by volume, the amount of siloxane adsorbed is not saturated and the reproducibility is poor, and this is not preferable. If it exceeds 5% by volume, an excess is deposited on the surface. It is not preferable because there are cases. When the proportion of octamethylcyclotetrasiloxane is in the range of 0.2 to 2% by volume, more preferably in the range of 0.5 to 1% by volume, the amount of siloxane adsorbed is preferable.

  The adsorption rate of siloxane on the surface of the master information carrier M is 4 times or less, preferably 3 times or less, more preferably 1.5 times or less. If the adsorption rate of siloxane exceeds 4 times, dirt is likely to accumulate on the surface of the master information carrier M, and a master information carrier M having excellent durability that can be used repeatedly for magnetic transfer is obtained. Absent.

  Further, in a compound in which two or more hydrogen atoms of a benzene ring contained in the lubricant layer 103 and a perfluoroether group having two or more hydroxyl groups at the terminal are substituted, two perfluoroether groups are bonded to the benzene ring. The position can be any of ortho, meta, and para. In consideration of the large molecular weight of the perfluoropolyether compound, the perfluoropolyether compound is bonded to the para position as the compound contained in the lubricant layer 103 as shown in the following formula (2). It is preferable to use what was done.

  In the above formula (2), p and q represent integers. Moreover, it is preferable that the average molecular weight of the compound shown by said Formula (2) exists in the range of 1000-5000.

  When the compound contained in the lubricant layer 103 is a compound represented by the above formula (2), the lubricant layer 103 and the protective layer 102 can be bonded more firmly, and in addition, the lubricant layer on the surface of the protective layer 102 The arrangement of 103 can be regular. Examples of the compound represented by the above formula (2) include ARJ-DD (trade name, manufactured by Matsumura Oil Research Institute (MORESCO)), or reaction products obtained by synthesizing and purifying these related materials as starting materials. Is mentioned.

  Further, the compound contained in the lubricant layer 103 is a compound obtained by substituting one or more hydrogen atoms of a benzene ring and one or more perfluoroether groups having three or more hydroxyl groups at the terminals (hereinafter simply referred to as “three hydroxyl groups at the terminals”). It may be referred to as “a compound having a perfluoroether group bonded”. This makes it possible to increase the functional group having a large polarity contained in the compound, and to further increase the bond between the functional group having a large polarity in the lubricant layer 103 and the “polar site” in the protective layer 102.

Further, the compound contained in the lubricant layer 103 may be a single compound, but may be two or more kinds of compounds.
When the compound contained in the lubricant layer 103 is a single compound, the compounds are likely to be regularly arranged in a network shape, but environmental pollutants are deposited on the surface of the protective layer 102 through the voids of the network made of the compound. May adhere. On the other hand, when the compound contained in the lubricant layer 103 is two or more kinds of compounds, the voids in a regular network arrangement composed of the compound can be filled with another compound. Thus, the coverage of the surface of the protective layer 102 can be increased.

 When the compound contained in the lubricant layer 103 is two or more types of compounds, at least the first component composed of a compound having a perfluoroether group having two hydroxyl groups at the ends bonded thereto, and the molecular weight relative to the first component It is preferable to contain other compounds that are 3 to 1/3 times. In this case, since the other compound is easily embedded in the voids of the mesh formed by the first component, the coverage of the surface of the protective layer 102 with the lubricant layer 103 can be further increased.

Further, in the case where the compound contained in the lubricant layer 103 is two or more kinds of compounds, 50 mass% of the first component composed of a compound in which a perfluoroether group having two hydroxyl groups is bonded to the terminal is contained in the lubricant layer 103. % Or more, preferably 70% by mass or more, more preferably 80% by mass or more.
When the content of the first component in the lubricant layer 103 is less than 50% by mass, the bonding force between the lubricant layer 103 and the protective layer 102 is not preferable. On the other hand, if the content of the first component exceeds 90% by mass, the regular arrangement of the compound on the surface of the protective film is increased, and voids are likely to be generated.

When the compound contained in the lubricant layer 103 is two or more kinds of compounds, the content of the compound other than the first component in the lubricant layer 103 is preferably 5% by mass or more, and preferably 10% by mass or more. More preferably, it is more preferably 20% by mass or more.
When the compound contained in the lubricant layer 103 is two or more kinds of compounds, if the content of the compound other than the first component in the lubricant layer 103 is less than 5% by mass, the compound by the compound other than the first component There is a possibility that the effect of filling the regular mesh-like voids composed of one component is insufficient.

When there are two or more compounds contained in the lubricant layer 103, specifically, for example, a compound in which a perfluoroether group having two hydroxyl groups is bonded to a terminal and a perfluoroether group having three hydroxyl groups at the terminal It is preferable to contain the compound which couple | bonded.
In addition, when there are two or more kinds of compounds contained in the lubricant layer 103, the compound represented by the above formula (2) in which a perfluoroether group having two hydroxyl groups is bonded to the terminal and the perfluoro having three hydroxyl groups at the terminal are shown. In addition to the compound to which the ether group is bonded, one or more compounds selected from the following chemical formulas (3) to (7) may be contained. Chemical formula (3), chemical formula (4), chemical formula (5), and chemical formula (6) are perfluoropolyether compounds. Chemical formula (7) is a phosphazene compound having a perfluorooxyalkylene unit.

In addition, the compound shown to the said Chemical formula (3)-(6) has the terminal functional group structure represented by at least 1 or more (A) or (B) in the structure. Further, in the above chemical formula (7), x is an integer from 1 to 5, R ₁ is either hydrogen atom, a halogenated alkyl group having 1 to 4 alkyl groups or carbon atoms having 1 to 4 carbon atoms, R ₂ is a perfluoropolyether chain having a terminal group of —CH ₂ OH or —CH (OH) CH ₂ OH. In addition, the perfluoropolyether chain of R _{2 in} the chemical formula (7) is at least one of (CF ₂ CF ₂ O), (CF ₂ O), and (CF ₂ CF ₂ CF ₂ O) as a repeating unit. including.

Examples of the compounds represented by the chemical formulas (3) to (6) include Fomblin Z-DOL (trade name, manufactured by Solvay Solexis), Fomblin Z-TETRAOL (trade name, manufactured by Solvay Solexis), or these. Reaction products obtained by synthesis and purification using related substances as starting materials can be mentioned.
Moreover, as a compound of Chemical formula (7), X-1p (trade name, manufactured by Dow Chemical Co., Ltd.), MORESCO PHOSPHAROL A20H-2000 (trade name, manufactured by Matsumura Oil Research Institute (MORESCO)), A20H-DD (trade name, And a reaction product obtained by synthesizing and purifying these related substances as starting materials.

  The average film thickness of the lubricant layer 103 is preferably in the range of 0.5 nm (5 mm) to 3 nm (30 mm), more preferably in the range of 5 mm to 20 mm, and most preferably in the range of 8 mm to 14 mm. Within. When the average film thickness of the lubricant layer 103 is in the range of 0.5 nm (5 mm) to 3 nm (30 mm), the surface coverage of the protective layer 102 by the lubricant layer 103 is sufficiently obtained, and the master information carrier M As a result, the master information carrier M having excellent adsorption resistance against environmental pollutants such as siloxane can be obtained.

In order to manufacture the master information carrier shown in FIG. 1, first, a master for producing the master information carrier M is formed.
The master can be manufactured by a known method. For example, after a resist is applied to the surface of a silicon wafer by spin coating, the resist is exposed and developed by irradiating the resist with an electron beam using an electron beam exposure apparatus. Thereafter, a resist pattern corresponding to the information signal magnetically transferred to the magnetic recording medium is formed on the silicon wafer by removing the unexposed portion of the resist.

  Next, using this resist pattern as a mask, a reactive etching process is performed on the silicon wafer, and a portion not masked by the resist pattern is dug down. Thereafter, the resist remaining on the silicon wafer is removed with a solvent, and the silicon wafer is dried to obtain a master for producing the master information carrier M.

  Next, a conductive layer made of Ni is formed with a thickness of about 10 nm on the master by sputtering or the like. Subsequently, a Ni layer having a thickness of several microns is formed on the master by electroforming using the master on which the conductive layer is formed as a mother die. After that, the Ni layer is removed from the master, and cleaning or the like is performed to obtain a base material 100 made of Ni having a base material convex portion 100a and a base material concave portion 100b on the surface as shown in FIG.

Next, as shown in FIG. 1, along the shape of the base material convex part 100a and the base material recessed part 100b formed on the surface of the base material 100 on the base material 100 using well-known methods, such as a sputtering method. The magnetic layer 101 is formed.
Subsequently, the protective layer 102 is formed on the magnetic layer 101 by using a known method such as a CVD method.

Thereafter, the lubricant layer 103 is formed on the protective layer 102 by the following method or the like.
The lubricant layer 103 is formed by a method of preparing a lubricant layer forming solution (coating solution) and applying the lubricant layer forming solution onto the protective layer 102.
A method for preparing a lubricant layer forming solution includes a compound in which two or more hydrogen atoms of a benzene ring and a perfluoroether group having two or more hydroxyl groups at its ends are substituted, and usually has a viscosity. A method of diluting a lubricant, which is a large oily liquid, with a solvent to a concentration suitable for the coating method. Examples of the solvent contained in the lubricant layer forming solution include fluorinated solvents such as Vertrel XF (trade name, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.).

  As a method of applying the lubricant layer forming solution onto the protective layer 102, a spin coating method, a dip method, or the like can be used. For example, when the lubricant layer forming solution is applied on the protective layer 102 by the dip method, the lubricant layer forming solution is placed in the dipping tank of the dip coater, and the layers up to the protective layer 102 are formed in the dipping tank. A method of forming the lubricant layer 103 with a uniform film thickness on the protective layer 102 by immersing the base material 100 and pulling up the base material 100 from the immersion tank at a predetermined speed can be used.

  Next, a step of heating the lubricant layer 103 formed in this manner and a step of irradiating the lubricant layer 103 with ultraviolet rays are performed. By performing the step of heating the lubricant layer 103 and the step of irradiating the lubricant layer 103 with ultraviolet rays, the solvent contained in the coating solution used when forming the lubricant layer 103 can be removed, and the lubricant layer 103 is also removed. The bonding force between the polar functional group and the functional group on the surface of the protective layer 102 can be further increased.

The heating temperature in the step of heating the lubricant layer 103 is higher than the boiling temperature of the solvent contained in the coating solution so that the solvent contained in the coating solution can be effectively removed without adversely affecting the lubricant layer 103. It is preferable that the temperature is within the range of the decomposition temperature of the lubricant. Specifically, the heating temperature in the step of heating the lubricant layer 103 is preferably in the range of 40 ° C. to 200 ° C., more preferably in the range of 80 ° C. to 130 ° C.
Further, the heating time in the step of heating the lubricant layer 103 can be appropriately determined according to the heating temperature, but is preferably in the range of 30 seconds to 120 minutes, more preferably in the range of 1 minute to 20 minutes.

Next, a step of irradiating the lubricant layer 103 with ultraviolet rays is performed. In the step of irradiating the lubricant layer 103 with ultraviolet rays, the irradiation intensity is preferably in the range of 0.5 to 100 (mW / cm ² ), and in the range of 1 to 50 (mW / cm ² ). It is more preferable. Further, in the step of irradiating the lubricant layer 103 with ultraviolet rays, the irradiation time is preferably in the range of 0.1 second to 30 minutes, and more preferably in the range of 1 second to 30 seconds.

  In the step of irradiating the lubricant layer 103 with ultraviolet rays, a known light source such as a low-pressure mercury lamp, a high-pressure mercury lamp, or an excimer lamp can be used as the light source. As the light source, it is preferable to use a low-pressure mercury lamp or excimer lamp having a spectrum of low-wavelength light with a wavelength of 260 nm or less that provides high light energy in order to increase the bonding force between the lubricant layer 103 and the protective layer 102.

Further, in the step of irradiating the lubricant layer 103 with ultraviolet rays, the lubricant may be decomposed by ozone formed by the decomposition of oxygen in the atmosphere by the ultraviolet rays. Therefore, it is preferable to irradiate the lubricant layer 103 with ultraviolet rays in an oxygen-free atmosphere such as a nitrogen gas atmosphere, an argon gas atmosphere, or a vacuum.
The step of heating the lubricant layer 103 may be performed before or after the step of irradiating the lubricant layer 103 with ultraviolet rays, but may be performed before the step of irradiating with ultraviolet rays. Is preferred.

  Through the above steps, a master information carrier M on which an information signal to be magnetically transferred to a magnetic recording medium is written is obtained.

  Since the master information carrier M of the present embodiment includes the magnetic layer 101 on which an information signal to be magnetically transferred to the magnetic recording medium is written and the lubricant layer 103 disposed on the outermost surface, the surface is soiled. It is difficult to accumulate. Therefore, even if the magnetic recording medium on which the information signal is written has a lubricant layer formed by applying a lubricant on the outermost surface, the lubricant is hardly transferred to the outermost surface of the master information carrier M. , Dirt due to the lubricant of the master information carrier M is difficult to accumulate. Therefore, the master information carrier M of the present embodiment has a sufficiently large number of usable times that can be repeatedly used for magnetic transfer, and has excellent durability.

"Magnetic recording media"
FIG. 2 is a cross-sectional view showing an example of a magnetic recording medium manufactured using the method for manufacturing a magnetic recording medium of the present invention. In the magnetic recording medium W shown in FIG. 2, a soft magnetic underlayer 32, an orientation control layer 33, a perpendicular magnetic layer 34, a protective layer 35, and a lubricating layer 36 are sequentially laminated on a nonmagnetic substrate 31. Is. An information signal having a magnetization pattern corresponding to a servo signal or the like is written on the perpendicular magnetic layer 34 of the magnetic recording medium W by magnetic transfer.

  As the nonmagnetic substrate 31, for example, a metal substrate made of a metal material such as aluminum or an aluminum alloy, a nonmetal substrate made of a nonmetal material such as glass, ceramic, silicon, silicon carbide, or carbon can be used. Further, as the nonmagnetic substrate 31, a metal substrate or a substrate having a NiP layer or a NiP alloy layer formed on the surface of the nonmetal substrate by using, for example, a plating method or a sputtering method can be used.

As the glass substrate used as the nonmagnetic substrate 31, for example, amorphous glass or crystallized glass can be used. As the amorphous glass, for example, general-purpose soda lime glass or aluminosilicate glass can be used. In addition, as the crystallized glass, for example, lithium-based crystallized glass can be used.
As the ceramic substrate used as the nonmagnetic substrate 31, for example, general-purpose aluminum oxide, a sintered body mainly composed of aluminum nitride, silicon nitride, or the like, or a fiber reinforced material thereof can be used.

The nonmagnetic substrate 31 preferably has an average surface roughness (Ra) of 1 nm (10 Å) or less, preferably 0.5 nm or less from the viewpoint of being suitable for high recording density recording with a magnetic head flying low. For the flight stability of the magnetic head, it is preferable that the surface average roughness (Ra) of at least one of the chamfered portion and the side surface portion of the chamfer portion at the end face is 10 nm or less, more preferably 9.5 nm or less. preferable.
Further, the nonmagnetic substrate 31 has a surface micro-waviness (Wa) of 0.3 nm or less, more preferably 0.25 nm or less from the viewpoint of being suitable for high recording density recording with a magnetic head flying low. preferable. In addition, microwaviness (Wa) can be measured as surface average roughness in a measuring range of 80 μm, for example, using a surface roughness measuring device P-12 (manufactured by KLM-Tencor).

  Further, it is preferable to provide an adhesion layer between the nonmagnetic substrate 31 and the soft magnetic underlayer 32. Since the nonmagnetic substrate 31 is in contact with the soft magnetic underlayer 32 containing Co or Fe as a main component, there is a possibility that corrosion proceeds due to the influence of adsorbed gas and moisture on the surface, diffusion of substrate components, and the like. By providing an adhesion layer between the nonmagnetic substrate 31 and the soft magnetic underlayer 32, corrosion of the nonmagnetic substrate 31 can be suppressed. As a material for the adhesion layer, for example, Cr, Cr alloy, Ti, Ti alloy, or the like can be selected as appropriate. The thickness of the adhesion layer is not particularly limited, but is preferably 2 nm (20 mm) or more in order to effectively suppress the corrosion of the nonmagnetic substrate 31.

As shown in FIG. 2, the soft magnetic underlayer 32 preferably includes two soft magnetic layers 32a antiferromagnetically coupled by a spacer layer 32b.
As the soft magnetic layer 32a, a material containing Fe: Co in the range of 40:60 to 70:30 (atomic ratio) is preferably used. The soft magnetic layer 32a preferably contains any one selected from Ta, Nb, Zr, and Cr in the range of 1 to 8 atomic% in order to increase the magnetic permeability and the corrosion resistance. .
As the spacer layer 32b, Ru, Re, Cu, or the like can be used, and it is particularly preferable to use Ru among them.

  The orientation control layer 33 is intended to improve the recording / reproducing characteristics by refining the crystal grains of the perpendicular magnetic layer 34. The orientation control layer 33 is not particularly limited, but a material having an hcp structure, an fcc structure, or an amorphous structure is preferably used. In particular, the orientation control layer 33 is preferably made of a Ru alloy, Ni alloy, Co alloy, Pt alloy, or Cu alloy. In addition, the orientation control layer 33 may be formed by multilayering these alloys. For example, a multilayer structure in which a Ni-based alloy and a Ru-based alloy are laminated from the substrate side, or a Co-based alloy and a Ru-based alloy. It is preferable to adopt a multilayer structure in which Pt-based alloys and Ru-based alloys are stacked.

  In the magnetic recording medium W of this embodiment, a nonmagnetic underlayer 38 is provided between the orientation control layer 33 and the perpendicular magnetic layer 34 as shown in FIG. When the perpendicular magnetic layer 34 is disposed immediately above the orientation control layer 33, disorder of crystal growth that causes noise is likely to occur in the perpendicular magnetic layer 34 immediately above the orientation control layer 33. In this embodiment, since the nonmagnetic underlayer 38 is provided between the orientation control layer 33 and the perpendicular magnetic layer 34, the portion where the crystal growth disorder directly above the orientation control layer 33 is likely to occur is perpendicular magnetic. The layer 34 is replaced with the nonmagnetic underlayer 38, and the generation of noise due to the disorder of the crystal growth of the perpendicular magnetic layer 34 can be suppressed.

As the nonmagnetic underlayer 38, it is preferable to use a layer made of a material containing Co as a main component and further containing an oxide. The Cr content is preferably 25 atomic% or more and 50 atomic% or less. As the oxide contained in the nonmagnetic underlayer 38, for example, an oxide such as Cr, Si, Ta, Al, Ti, Mg, Co is preferably used, and in particular, TiO ₂ , Cr ₂ O ₃ , SiO _{2 are used.} Etc. are preferably used. The content of the oxide contained in the nonmagnetic underlayer 38 is preferably 3 mol% or more and 18 mol% or less, for example, with respect to the total mol calculated from an alloy such as Co, Cr, and Pt as one compound. .
As shown in FIG. 2, a nonmagnetic underlayer 38 is preferably provided between the orientation control layer 33 and the perpendicular magnetic layer 34, but it may not be provided.

  In the magnetic recording medium W of the present embodiment, the perpendicular magnetic layer 34 includes three layers of a lower magnetic layer 34a, an intermediate magnetic layer 34b, and an upper magnetic layer 34c, and between the magnetic layer 34a and the magnetic layer 34b. The nonmagnetic layer 37a is sandwiched between the magnetic layers 34b and 34c, and the magnetic layers 34a to 34c and the nonmagnetic layers 37a and 37b are alternately stacked. Have.

The magnetic layers 34a and 34b preferably have a granular structure, and it is preferable to use a material mainly containing Co and further containing an oxide. As the oxides included in the magnetic layers 34a and 34b, for example, oxides such as Cr, Si, Ta, Al, Ti, Mg, and Co are preferably used, and in particular, TiO ₂ , Cr ₂ O ₃ , and SiO _{2 are used.} Etc. are preferably used.
The lower magnetic layer 34a preferably contains a composite oxide to which two or more kinds of oxides are added. Among these, Cr ₂ O ₃ —SiO ₂ , Cr ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ —SiO ₂ —TiO _{2 and the} like can be preferably used.

As a material suitable for the magnetic layers 34a and 34b, for example, 90 (Co14Cr18Pt) -10 (SiO ₂ ) {Cr content of 14 atomic%, Pt content of 18 atomic%, and the remainder Co magnetic particles as one compound. calculated molarity 90 mol%, 10 _mol% oxide composition consisting _{SiO 2}, 92 (Co10Cr16Pt)} -8 (SiO 2), other _{94 (Co8Cr14Pt4Nb) -6 (Cr 2} O 3), (CoCrPt) - _{(Ta 2 O 5), (} CoCrPt) - (Cr 2 O 3) - (TiO 2), (CoCrPt) - (Cr 2 O 3) - (SiO 2), (CoCrPt) - (Cr 2 O 3) - _{(SiO 2) - (TiO 2} ), (CoCrPtMo) - (TiO), (CoCrPtW) - (TiO 2), (CoCrPtB) _{(Al 2 O 3), (} CoCrPtTaNd) - (MgO), (CoCrPtBCu) - (Y 2 O 3), (CoCrPtRu) - can be exemplified compositions such as (SiO _2).

  The upper magnetic layer 34c is preferably a magnetic layer containing no oxide. Specific examples of materials suitable for the upper magnetic layer 34c include materials obtained by removing oxides from materials suitable for the magnetic layers 34a and 34b described above.

  The perpendicular magnetic layer 34 may be composed of four or more magnetic layers. For example, a magnetic layer having a granular structure may be formed by adding one layer to the magnetic layers 34a and 34b to form three layers, and a perpendicular magnetic layer having a four-layer structure in which a magnetic layer 34c containing no oxide is provided thereon. Alternatively, a perpendicular magnetic layer 34 having a four-layer structure in which a magnetic layer 34c not containing an oxide is provided as a two-layer structure on the granular magnetic layers 34a and 34b may be used.

  In addition, nonmagnetic layers 37 a and 37 b are preferably provided between three or more magnetic layers constituting the perpendicular magnetic layer 34. By providing the nonmagnetic layers 37a and 37b with an appropriate thickness, magnetization reversal of individual films can be facilitated, and dispersion of magnetization reversal of the entire magnetic particles can be reduced. As a result, the S / N ratio can be further improved. Conventionally known materials can be used for the nonmagnetic layers 37a and 37b, and for example, Ru, Re, Cu, or the like can be used.

The protective layer 35 is for preventing corrosion of the perpendicular magnetic layer 34 and preventing damage to the surface when the magnetic head contacts the magnetic recording medium W. For the protective layer 35, a conventionally known material can be used. For example, a material containing C, SiO ₂ , ZrO ₂ or the like can be used. The thickness of the protective layer 35 is preferably 1 to 10 nm from the viewpoint of high recording density because the distance between the magnetic head and the magnetic recording medium W can be reduced.

  When the lubricant layer 36 uses the master information carrier M to write an information signal to the magnetic layer 34 of the magnetic recording medium W, the protective layer 35 comes into contact with the master information carrier M to promote wear of the master information carrier M. It is what prevents it. As the lubricating layer 36, a conventionally known material can be used, and for example, it can be formed by applying a lubricant such as perfluoropolyether, fluorinated alcohol, fluorinated carboxylic acid or the like on the protective layer 35.

"Method of manufacturing magnetic recording medium"
In order to manufacture the magnetic recording medium W shown in FIG. 2, first, an adhesion layer, a soft magnetic underlayer 32, an orientation control layer 33, a nonmagnetic underlayer 38, and a perpendicular magnetic layer are formed on a nonmagnetic substrate 31. 34, a protective layer 35, and a lubricating layer 36 are sequentially stacked. Thereafter, in the present embodiment, an information signal writing step of writing an information signal to the magnetic layer 34 of the magnetic recording medium W is performed.

  The laminated structure forming step can be performed by a known method. For example, an adhesion layer, a soft magnetic underlayer 32 including a soft magnetic layer 32a, a spacer layer 32b, and a soft magnetic layer 32a, an orientation control layer 33, and a nonmagnetic underlayer are formed on the nonmagnetic substrate 31 by sputtering or the like. 38. A perpendicular magnetic layer 34 including a lower magnetic layer 34a, a nonmagnetic layer 37a, an intermediate magnetic layer 34b, a nonmagnetic layer 37b, and an upper magnetic layer 34c is laminated in this order from the bottom. Thereafter, the protective layer 35 is formed using a CVD method or the like. Next, the lubricant layer 36 is formed on the protective layer 35 by a method of applying a lubricant or the like.

  In the present embodiment, it is preferable to provide a step of periodically cleaning the master information carrier M in the information signal writing step of writing the information signal to the magnetic layer 34 of the magnetic recording medium W. “Regularly” refers to providing a cleaning process for the master information carrier M, for example, every 5000 to 50000 magnetic transfer processes. Depending on the cleaning liquid used in the cleaning process, the lubricant layer applied to the surface of the master information carrier M may be removed. In this case, after the master information carrier M is cleaned, a lubricant layer application process is provided.

  In this embodiment, the master information carrier M shown in FIG. 1 in which the lubricant layer 103 is disposed on the outermost surface is used as the master information carrier M in the information signal writing step. Since the lubricant layer 103 is provided on the outermost surface, not only dirt is hardly accumulated on the surface of the master information carrier M but also dirt attached to the surface is easily removed. Therefore, the master information carrier M having a very clean surface can be easily obtained by washing the master information carrier M before performing the information signal writing step. Further, when the information signal writing step is performed after cleaning the master information carrier M, the master signal carrier M having a very clean surface is used to write the information signal to the magnetic layer 34 of the magnetic recording medium W. It is possible to more effectively suppress the transfer pattern transferred to the magnetic recording medium W from becoming incomplete due to the accumulation of dirt on the surface of the information carrier. Therefore, the number of times that the master information carrier M can be used for repeated magnetic transfer can be further increased.

  Since the master information carrier M of the present embodiment easily removes dirt attached to the surface, it can be easily and effectively cleaned by any known method, and a clean surface can be obtained. For this reason, the cleaning method used in the step of cleaning the master information carrier M is not particularly limited. For example, as a method of cleaning the master information carrier M, one or more types selected from a method of immersing the master information carrier M in a cleaning tank in which a cleaning liquid flows in a laminar state, a wiping process, spin cleaning, and the like. The method can be used one or more times.

In particular, the method of immersing the master information carrier M in the cleaning tank in which the cleaning liquid flows in a laminar state is a method in which ionic impurities such as metal corrosives are accumulated as dirt. This is preferable because it can be efficiently removed from the surface of the information carrier.
Further, in the method of cleaning by immersing the master information carrier M in the cleaning tank in which the cleaning liquid flows in a laminar flow state, it is preferable to clean the master information carrier M while flowing the cleaning liquid laterally in the cleaning tank. . In this case, since the cleaning liquid containing the contaminant can be quickly discharged out of the immersion tank, the contaminant can be prevented from reattaching to the surface of the master information carrier M. As a result, a master information carrier M having a clean surface that cannot be obtained by conventional methods is obtained.

  In the step of cleaning the master information carrier M, when cleaning the master information carrier M using a cleaning liquid, it is preferable to use a cleaning liquid containing hydrogen water as the cleaning liquid. Hydrogen water is ultrapure water or one obtained by dissolving high purity hydrogen gas in pure water, and is a water cluster that is made smaller to increase the cleaning ability. When a cleaning liquid containing hydrogen water is used as the cleaning liquid, corrosion of the master information carrier M due to the cleaning liquid is unlikely to occur, and stains made of metal corrosives transferred from the magnetic recording medium to the master information carrier M can be obtained with high cleaning power. Can be removed. In particular, when the dissolved hydrogen concentration in the hydrogen water is in the range of 0.1 ppm to 5 ppm and the redox potential of the hydrogen water is in the range of −200 mV to −800 mV, the function can be enhanced.

Further, the step of cleaning the master information carrier M may be a multi-step process. Examples of the multistage process include a method in which the master information carrier M is washed with a cleaning solution containing hydrogen water and an alkali and then washed with a cleaning solution containing hydrogen water and no alkali. When the master information carrier M is cleaned using a cleaning liquid containing hydrogen water and an alkali such as KOH, NH ₄ OH, or NaOH, the cleaning power can be increased as compared with the case where only hydrogen water is used as the cleaning liquid. it can.

However, if alkali remains on the surface of the master information carrier M after washing, it causes contamination of the master information carrier M.
In order to prevent alkali remaining on the master information carrier M after washing, it is preferable to use KOH or NH ₄ OH as the alkali contained in the washing liquid, and the alkali concentration in the washing liquid is 0.05 ppm to 5 ppm. It is preferable to be in the range. In addition, it is preferable that the master information carrier M is washed with a cleaning liquid containing alkali water and hydrogen water, and then washed with a cleaning liquid containing hydrogen water without containing alkali. By performing such a multi-stage process, it is possible to increase the detergency of the master information carrier M while preventing alkali from remaining on the master information carrier M.

  Further, when performing the wiping process as a method of cleaning the master information carrier M, for example, while the wiping tape made of cloth or the like is moved relative to the surface of the magnetic recording medium W, the wiping tape is made by a rubber contact roll or pad. A method of wiping the surface of the medium lightly by pressing the surface against the surface of the magnetic recording medium W can be used. By performing such a wiping process, it is possible to remove dirt such as spatter dust attached to the surface of the magnetic recording medium W.

  As described above, the step of cleaning the master information carrier M may be performed before the information signal writing step, but in the information signal writing step described later, the magnetic layer (in this embodiment) of one or more substrates. The information signal is magnetically transferred to the magnetic layer 34 of the non-magnetic substrate 31 including the layers up to the lubricating layer 36 formed in the laminated structure forming step, and then the information is transferred to the magnetic layer of the next substrate. It may be performed before the signal is magnetically transferred. In this case, the step of cleaning the master information carrier M is preferably performed periodically as shown below.

  That is, the contamination of the master information carrier M is mainly caused by a free loop that is transferred and stored little by little from the magnetic recording medium W to which the information signal is magnetically transferred to the master information carrier M by repeatedly performing the information signal writing process. It is. The accumulated freerubb absorbs impurities in the atmosphere and gradually erodes the transfer surface of the master information carrier M, thereby reducing the transfer accuracy of the master information carrier M. Therefore, the step of cleaning the master information carrier M is preferably performed periodically before the transfer accuracy of the master information carrier M decreases due to accumulation of dirt. Specifically, it is preferable to perform a step of cleaning the master information carrier M every time an information signal is magnetically transferred to 5000 to 50000 substrates.

  Next, the signal recording surface which is the surface on which the magnetic layer 34 of the magnetic recording medium W is provided is initially magnetized. The initial magnetization of the signal recording surface is performed by applying an initial DC magnetic field in one direction in the track direction when manufacturing an in-plane magnetic recording medium, and with respect to the medium surface when manufacturing a perpendicular magnetic recording medium. This is done by applying an initial DC magnetic field in one direction perpendicular. The initial DC magnetic field used for the initial magnetization can be applied to the magnetic recording medium W using a permanent magnet or an electromagnet. The application of the initial DC magnetic field is preferably performed in a non-contact state with the magnetic recording medium W in order to maintain the cleanliness of the surface of the magnetic recording medium W. As the permanent magnet, it is preferable to use an NdFeB-based sintered magnet that is more stable and has a strong magnetic force.

Next, an information signal writing process for writing an information signal to the magnetic layer 34 of the magnetic recording medium W is performed.
In the information signal writing step, an information signal corresponding to a servo signal or the like is written on the magnetic recording medium W by magnetically transferring the information signal to the magnetic layer 34 of the magnetic recording medium W using the master information carrier M.
FIG. 3 is a cross-sectional view for explaining a process of writing an information signal to the magnetic layer of the magnetic recording medium in the method for manufacturing a magnetic recording medium of the present invention. 3, in order to make the drawing easy to see, only the base material 100 and the magnetic layer 101 are shown in the master information carrier M, and only the nonmagnetic substrate 31 and the magnetic layer 34 are shown in the magnetic recording medium W. Further, illustration of other members constituting the magnetic recording medium W is omitted.

  In the information signal writing step, first, the signal recording surface (the surface on the magnetic layer 34 side) of the magnetic recording medium W after the initial magnetization is brought into contact with the surface on the magnetic layer 101 side of the cleaned master information carrier M. In this state, they are brought into close contact with a predetermined pressing force. Then, as shown in FIG. 3, the master information carrier M is moved from the surface of the master information carrier M on the base material 100 side while moving the magnetic field generation means G relatively in the track direction X using the magnetic field generation means G. An external magnetic field for transfer is applied to the magnetic recording medium W.

The magnetic field generating means G used in the information signal writing step is composed of an electromagnet or a permanent magnet. The magnetic field generating means G is capable of rotating in the track direction X to the center of the magnetic recording medium W while generating an external magnetic field in the same direction in the radial direction of the magnetic recording medium W.
When writing an information signal to the in-plane magnetic recording medium, an external magnetic field for transfer is generated in the other direction of the track. When writing an information signal on a perpendicular magnetic recording medium, an external magnetic field for transfer is generated in the other direction perpendicular to the medium surface. The external magnetic field for transfer is a magnetic field in the opposite direction to the initial DC magnetic field applied when the magnetic recording medium W is initially magnetized.

  Thus, by applying an external magnetic field for transfer to the master information carrier M and the magnetic recording medium W, the transfer pattern of the master information carrier M in the magnetic layer 34 of the magnetic recording medium W is changed as shown in FIG. Magnetization reversal occurs at a location facing the magnetic layer convex portion 101a and the magnetic layer concave portion 101b constituting the same. As a result, a magnetization pattern which is an information signal corresponding to a servo signal or the like written on the master information carrier M is magnetically transferred to the magnetic layer 34 of the magnetic recording medium W and written.

  In the present embodiment, as the magnetic recording medium W, as shown in FIG. 2, an example in which each layer including the magnetic layer 34 is provided only on one surface of the nonmagnetic substrate 31 has been described. However, each layer provided on the nonmagnetic substrate 31 shown in FIG. 2 may be provided on both surfaces of the nonmagnetic substrate 31.

  When the magnetic recording medium W is provided with the layers including the magnetic layer 34 on both surfaces of the nonmagnetic substrate 31, the information signal writing step sandwiches both surfaces of the magnetic recording medium W with a pair of master information carriers M. The transfer is preferably performed by applying an external magnetic field for transfer to the master information carrier M and the magnetic recording medium W from the surface of each master information carrier M on the base material 100 side using the magnetic field generating means G. Thereby, information signals corresponding to servo signals and the like can be written on both surfaces of the magnetic recording medium W easily and efficiently.

  The manufacturing method of the magnetic recording medium W of this embodiment is a method of magnetically transferring an information signal to the magnetic layer 34 of the nonmagnetic substrate 31 using the master information carrier M having the lubricant layer 103 disposed on the outermost surface. Therefore, the number of times that one master information carrier M can be used can be sufficiently increased. As a result, according to the method for manufacturing the magnetic recording medium W of the present embodiment, the production cost of the magnetic recording medium W can be significantly reduced.

Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to the Example shown below, In the range which does not change the summary, it can change suitably and can implement.
Example 1
<Manufacture of master information carrier>
A substrate made of Ni having a substrate convex portion and a substrate concave portion having a shape corresponding to a transfer pattern such as a servo signal of 271 k tracks / inch on the surface was prepared. The track corresponding to the information signal magnetically transferred to the base magnetic recording medium W has a width of 120 nm, the track interval is 60 nm, and the step between the base convex portion and the base concave portion (transfer pattern step) is 45 nm. Met.

On such a base material, a base layer made of a Ru film having a layer thickness of 10 nm was formed along the shape of the base material convex portions and the base material concave portions using a DC sputtering method. Thereafter, along the shape of the base convex portion and the base concave portion on the underlayer, a DC sputtering method is used to form a 70Co-5Cr-15Pt-10SiO ₂ alloy film having a thickness of 20 nm and an 80Co-5Cr layer having a thickness of 15 nm. A magnetic layer composed of a −15 Pt alloy film was sequentially laminated to form a magnetic layer in which an information signal magnetically transferred to the magnetic recording medium W was written.

Next, a protective layer made of a carbon film having a thickness of 20 nm was formed on the magnetic layer by a CVD method.
Thereafter, ARJ-DD (trade name, manufactured by Matsumura Oil Research Institute (MORESCO), average molecular weight of about 3000), which is a compound represented by the above formula (2), was applied on the protective layer using a dip method. Then, the master information carrier M of Example 1 was obtained by baking at 80 ° C. for 60 seconds to form a lubricant layer. The thickness of the lubricant layer was 2 nm.
The obtained master information carrier M is put into a sealed container having an internal volume of 1 liter, 50 μL of octamethylcyclotetrasiloxane is dropped into the container with a microsyringe, and atmospheric pressure is applied to the air containing octamethylcyclotetrasiloxane. Then, the amount of siloxane deposited on the surface of the master information carrier M was examined by SIMS (secondary ion mass spectrometer), and it was twice that before the exposure.

<Manufacture of magnetic recording media>
As a non-magnetic substrate, a cleaned glass substrate (manufactured by Konica Minolta Co., Ltd., 2.5 inches in outer diameter) is prepared, accommodated in a film forming chamber of a DC magnetron sputtering apparatus (C-3040 made by Anelva), and an ultimate vacuum is obtained. The film formation chamber was evacuated until the ^pressure reached 1 × 10 ⁻⁵ Pa.
Thereafter, an adhesion layer having a layer thickness of 10 nm was formed on the glass substrate using a 60Cr-40Ti target.

Next, on the adhesion layer, a target of 46Fe-46Co-5Zr-3B {Fe content 46 atom%, Co content 46 atom%, Zr content 5 atom%, B content 3 atom%} was used. A soft magnetic layer having a layer thickness of 34 nm, a Ru layer having a layer thickness of 0.76 nm, and a 46Fe-46Co-5Zr-3B soft magnetic layer having a layer thickness of 34 nm were formed at a substrate temperature of ℃ or less, and this was formed as a soft magnetic underlayer It was.
Next, on the soft magnetic underlayer, a Ni-6W {W content 6 atom%, the balance Ni} target and a Ru target were sequentially formed with a layer thickness of 5 nm and 20 nm, respectively, and this was subjected to orientation control. Layered.

Then, on the orientation control layer, a magnetic layer of a multilayer structure by a sputtering method, 84 (Co12Cr16Pt) -16TiO ₂ (film thickness _{3nm), 91 (Co5Cr22Pt) -4SiO} 2 -3Cr 2 O 3 -2TiO 2 (Thickness 3 nm), Ru47.5Co (thickness 0.5 nm), and Co15Cr16Pt6B (thickness 3 nm) were laminated.

Next, a protective layer made of a carbon film having a thickness of 2.5 nm was formed by a CVD method.
Next, a lubricant layer made of perfluoropolyether was applied on the protective layer by a dipping method to form a lubricant layer having a thickness of 15 Å. The magnetic recording medium W was obtained through the above steps.

Next, an information signal writing step was performed in which the signal recording surface, which is the surface on which the magnetic layer of the magnetic recording medium W is provided, was initially magnetized and an information signal was written to the magnetic layer of the magnetic recording medium W.
In the information signal writing process, the signal recording surface of the magnetic recording medium W after initial magnetization and the surface on the magnetic layer side of the master information carrier M are brought into close contact with each other with a predetermined pressing force, and master information is written. An external magnetic field for transfer is applied to the master information carrier M and the magnetic recording medium W while moving the magnetic field generating means G relatively in the track direction X from the surface of the carrier M on the substrate side. Then, a magnetization pattern which is an information signal corresponding to a servo signal or the like written on the master information carrier M was magnetically transferred to the magnetic layer of the magnetic recording medium W and written.

Each time 20,000 magnetic recording media were magnetically transferred by the above method, the master information carrier M was washed. The master information carrier M was washed in a three-stage washing process by removing the master information carrier M from the magnetic transfer device. Specifically, all of the cleaning tanks used in each cleaning step are made of SUS, have a volume of 20 liters, and 500 W ultrasonic vibration is applied to the inside. In each washing tank, 15 liters of hydrogen water having a dissolved hydrogen concentration of 1.5 ppm and an oxidation-reduction potential of −550 mV produced using ultrapure water is added. Further, 0.1 ppm of KOH is added to the first washing tank. did. The master information carrier M was immersed in this three-stage washing tank in order and washed in each washing tank for 30 seconds. The master information carrier M after washing was pulled up and dried using dry air.
Thereafter, a lubricant layer was formed on the master information carrier M using the dipping method under the same conditions as described above.

  Such an information signal writing process was performed a plurality of times, and the number of usable master information carriers that can be repeatedly used for magnetic transfer was examined. As a result, in Example 1, 231,000 times of magnetic transfer were possible.

(Comparative Example 1)
A magnetic recording medium was manufactured in the same manner as in Example 1 except that the lubricant layer was not provided. The master information carrier M was washed for every magnetic transfer of 20,000 magnetic recording media. As a result, in Comparative Example 1, 165,000 times of magnetic transfer were possible.

  31 ... Nonmagnetic substrate 32 ... Soft magnetic underlayer 32a ... Soft magnetic layer 32b ... Spacer layer 33 ... Orientation control layer 34 ... Perpendicular magnetic layer 34a, 34b, 34c ... Magnetic layer 35 ... Protective layer 36 ... Lubricating layer 37a, 37b ... Nonmagnetic layer 38 ... Nonmagnetic underlayer 100 ... Base material 100a ... Base material convex part 100b ... Base material concave part 101 ... Magnetic layer 101a ... Magnetic layer convex part 101b ... Magnetic layer concave part 102 ... Protective layer 103 ... Lubricant layer W ... Magnetic recording medium M ... Master information carrier G ... Magnetic field generating means

Claims (7)

  A master information carrier comprising a magnetic layer on which an information signal to be magnetically transferred to a magnetic recording medium is written, and a lubricant layer disposed on the outermost surface, the lubricant layer comprising hydrogen atoms of a benzene ring, A compound containing two or more perfluoroether groups terminated with two or more hydroxyl groups, and the master information carrier exposed to air containing octamethylcyclotetrasiloxane at atmospheric pressure for 8 hours or more, A master information carrier characterized in that the amount of siloxane deposited on the surface of the master information carrier is 4 times or less of the amount deposited before exposure. The master information carrier according to claim 1, wherein the compound has a chemical formula represented by the following formula (1) and an average molecular weight is in a range of 1000 to 5000.
However, in following formula (1), p and q show an integer.

  The master information carrier according to claim 1 or 2, wherein a film thickness of the lubricant layer is in a range of 5 to 30 mm.   The master information carrier according to any one of claims 1 to 3, wherein the magnetic layer includes a convex portion having a shape corresponding to the information signal.   Forming a magnetic layer on a substrate; and an information signal writing step of writing an information signal to the magnetic layer, wherein the magnetic layers of the plurality of substrates on which the magnetic layer is formed in the information signal writing step On the other hand, a method of manufacturing a magnetic recording medium, wherein the information signal is repeatedly magnetically transferred using the master information carrier according to any one of claims 1 to 4.   6. The method of manufacturing a magnetic recording medium according to claim 5, wherein a protective layer and a lubricating layer are sequentially laminated on the magnetic layer before performing the information signal writing step.   In the information signal writing step, after the information signal is magnetically transferred to the magnetic layer of one or more of the substrates, the information signal is magnetically transferred to the magnetic layer of the next substrate. The method of manufacturing a magnetic recording medium according to claim 5 or 6, wherein a step of washing the master information carrier is performed before the information signal writing step.

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