JP2012053937A - Magnetic recording medium manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium manufacturing method capable of manufacturing a magnetic recording medium with high recording density efficiently and at low cost while allowing efficient, accurate, stable and even magnetic transferring without causing the magnetic transfer to be incomplete.SOLUTION: A magnetic recording medium manufacturing method comprises the steps of: placing a master information carrier M, on which a transfer pattern corresponding to an information signal is formed, on a magnetic recording medium W, in which at least a perpendicular magnetic layer 4 is formed on a non-magnetic substrate 1; and subsequently, magnetically transferring the information signal from the master information carrier M to the magnetic recording medium W while applying an external magnetic field to the magnetic recording medium W from the side of the master information carrier M by magnetic field generating means G. In the steps of magnetic transferring, the master information carrier M is used that is provided with a magnetic layer 101 having a multi-layered structure in which at least one or more layers of each of a CoPt magnetic layer 101a and an FePt magnetic layer 101b are laminated.

Description

  The present invention relates to a method of manufacturing a magnetic recording medium used in a magnetic recording / reproducing apparatus such as a hard disk drive (HDD), and more specifically, magnetically transferring an information signal to a magnetic recording medium by a master information carrier. The present invention relates to a method for manufacturing a recording medium.

  The recording density of a hard disk drive (hard disk drive), which is a kind of magnetic recording / reproducing apparatus, is currently increasing by 1.5 times or more per year, and it is said that this trend will continue in the future. Along with this, development of a magnetic head and a magnetic recording medium suitable for increasing the recording density is in progress. In the latest magnetic recording apparatus, the track density has reached 320 kTPI.

  For this reason, 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 on the track. Specifically, in current hard disk drives, tracking servo signals, information signals such as address information signals and reproduction clock signals (hereinafter referred to as servo signals, etc.) are recorded at regular angular intervals during one round of the disk. Has been. 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 signals reproduced from the magnetic head at regular intervals. ing.

  Accordingly, since the servo signal and the like described above serve as a reference signal for the magnetic head to accurately scan the track, high positioning accuracy is required for writing these signals. For this reason, in a conventional hard disk drive manufacturing site, a servo signal recording device (hereinafter referred to as a servo writer) incorporating a high-precision position detection device is used to write a servo signal or the like to a magnetic recording medium. It has been broken. Further, 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 these magnetic recording media in order to increase productivity.

However, the following problems exist when the writing method of the servo signal or the like by the servo writer as described above is employed.
That is, in order to write signals over a large number of tracks while positioning the magnetic head with high accuracy by the above method, a long process time is required. Further, in order to improve productivity, many servo writers are used. Must be operated simultaneously. However, when the number of servo writers to be introduced into the process is increased, there is a problem that a large amount of cost is required for maintenance. Further, when the number of magnetic recording media that can be chucked at the same time is increased by increasing the spindle, blurring is likely to occur during rotation, which may lead to a decrease in writing accuracy with respect to the magnetic recording medium. For this reason, the number of magnetic recording media that can be chucked on one spindle is naturally limited. These problems become more serious as the track density of the magnetic recording medium improves and the number of tracks increases.

  In order to solve the above problem, in the step of writing servo signals and the like on the magnetic recording medium, a master information carrier on which magnetic transfer patterns corresponding to all servo signals and the like are written is used instead of the servo writer configured as described above. A method has been proposed in which signals written on the master information carrier are collectively magnetically transferred to a magnetic recording medium (see, for example, Patent Document 1). According to the method described in Patent Document 1, specifically, the master information carrier and the magnetic recording medium were written in the master information carrier while applying a magnetic field as energy for transfer from the outside in a state where the master information carrier and the magnetic recording medium were in close contact with each other. The signal is magnetically transferred to a magnetic recording medium. As a result, writing of servo signals and the like on the magnetic recording medium can be performed in a short time, and the master information carrier having the above configuration can be used repeatedly.

JP 10-40544 A

  However, as a result of intensive studies by the present inventors, it has become apparent that the following problems exist even when magnetic transfer to a magnetic recording medium is performed by the method described in Patent Document 1. .

In general, when magnetic transfer is performed on a magnetic recording medium having a coercive force of about 4000 oersted or more in the magnetic layer, sintering having a saturation magnetic flux density of about 3 Tesla on the back side of the master information carrier as described above. Processing is performed while rotating a magnet (NdFeB system, rectangular parallelepiped shape). However, the magnetic field generated from the sintered magnet is not necessarily uniform, and the magnetic field has a distribution characteristic that the magnetic field is strong in the central part but weak in the end part depending on the position of the magnet. Therefore, when magnetic transfer is performed by a conventional method, there is a problem that it is difficult to perform uniform magnetic transfer over the entire surface of the magnetic recording medium. For this reason, problems such as incomplete magnetic transfer and a decrease in transfer accuracy, and a decrease in productivity due to the time required for magnetic transfer have occurred.
Therefore, when performing magnetic transfer on a magnetic recording medium having a magnetic layer having a high coercive force, the magnetic transfer can be performed efficiently, accurately, stably and uniformly, regardless of whether the magnetic field is high or low. A method that could be performed was highly desired.

  The present invention has been made in view of the above problems, and even when magnetic transfer is performed on a magnetic recording medium in which the coercive force of the magnetic layer is increased, the magnetic transfer is efficient and high without imperfection. An object of the present invention is to provide a method of manufacturing a magnetic recording medium that can be performed stably and uniformly with high accuracy, and that can manufacture a high recording density magnetic recording medium efficiently and at low cost.

The present inventors have conducted intensive research to solve the above problem, and rotated a sintered magnet from the back side of the master information carrier with respect to a magnetic recording medium in which the coercive force of the magnetic layer is, for example, about 4000 oersted or more. Thus, when magnetic transfer was performed while applying a magnetic force, a method capable of improving transferability to a magnetic recording medium even when the magnetic field distribution of the sintered magnet was not uniform was studied. As a result, it was first found that when a magnetic layer is composed of CoPt, the writability in a low magnetic field is improved, and when the magnetic layer is composed of FePt, the writability in a high magnetic field is improved. Then, the magnetic layer provided in the master information carrier used for magnetic transfer has a multilayer structure composed of a CoPt magnetic layer and an FePt magnetic layer, so that magnetic transfer can be stably performed in either a high magnetic field or a low magnetic field. It was found that the transferability to a magnetic recording medium having a large coercive force dispersion could be improved, and the present invention was completed.
That is, the present invention adopts the following configuration.

[1] After superimposing a magnetic recording medium having at least a magnetic layer on a nonmagnetic substrate and a master information carrier on which a transfer pattern corresponding to an information signal is formed, an external magnetic field is applied from the master information carrier side. A magnetic recording medium manufacturing method including a step of magnetically transferring an information signal from the master information carrier to the magnetic recording medium while applying the magnetic information, wherein the step of performing the magnetic transfer includes a CoPt magnetic layer and FePt A method for manufacturing a magnetic recording medium, comprising using a master information carrier comprising a magnetic layer having a multilayer structure in which at least one magnetic layer is laminated.
[2] The magnetic layer provided in the master information carrier has a relationship in which the CoPt magnetic layer contains at least 70 atomic% or more of Co and Pt, and each content satisfies the following formula {Co> Pt}. And the FePt magnetic layer contains at least 60 atomic% of Fe and Pt, and each content satisfies the following formula {Fe> Pt}. The method for producing a magnetic recording medium according to [1].
[3] The above-mentioned [1] or [2], wherein the magnetic layer provided in the master information carrier is formed by alternately laminating a plurality of CoPt magnetic layers and FePt magnetic layers. A method of manufacturing a magnetic recording medium.
[4] The magnetic information according to any one of [1] to [3], wherein the master information carrier is formed by laminating at least the magnetic layer on a base material on which an uneven pattern is formed. A method for manufacturing a recording medium.
[5] The step of performing the magnetic transfer is performed by superimposing the master information carrier and the magnetic recording medium on the back side of the master information carrier while rotating a sintered magnet on the back side of the master information carrier. The method of manufacturing a magnetic recording medium according to any one of [1] to [4], wherein an information signal is magnetically transferred from the master information carrier to the magnetic recording medium by applying a magnetic field.

  According to the method of manufacturing a magnetic recording medium of the present invention, as described above, when performing magnetic transfer to the magnetic recording medium, a multilayer in which at least one or more CoPt magnetic layers and FePt magnetic layers are stacked. A method using a master information carrier provided with a magnetic layer having a structure is employed. As a result, when performing the magnetic transfer by superimposing the master information carrier and the magnetic recording medium, the magnetic transfer does not become incomplete in either a high magnetic field or a low magnetic field, and it is efficient, highly accurate, and stable. Since uniform magnetic transfer can be performed, transferability to a magnetic recording medium having a large coercive force dispersion is improved. Therefore, a magnetic recording medium having a high recording density can be manufactured efficiently and at low cost.

It is a figure which illustrates typically an example of the manufacturing method of the magnetic-recording medium based on this invention, (a) is sectional drawing which shows the magnetic transfer process using a master information carrier, (b) is equipped with a master information carrier. It is sectional drawing which shows the laminated structure of a magnetic layer. It is a figure which illustrates typically an example of the manufacturing method of the magnetic recording medium based on this invention, and is sectional drawing which shows the magnetic recording medium obtained by the manufacturing method of this invention. 1 is a schematic view schematically showing an example of a magnetic recording / reproducing apparatus using a magnetic recording medium according to the present invention.

  Hereinafter, a method for manufacturing a magnetic recording medium according to the present invention will be described with reference to FIGS. The drawings referred to in the following description are drawings for explaining a method of manufacturing a magnetic recording medium, and the size, thickness, dimensions, etc. of each part shown in FIG. Is different.

[Method of manufacturing magnetic recording medium]
As shown in FIG. 1A, a method for manufacturing a magnetic recording medium 10 (see FIGS. 2 and 3) to which the present invention is applied has at least a perpendicular magnetic layer (magnetic layer) 4 on a nonmagnetic substrate 1. After superposing the formed magnetic recording medium W and the master information carrier M on which the transfer pattern corresponding to the information signal is formed, the master information carrier M side applies the external magnetic field by the magnetic field generating means G, and the master The method includes a step of magnetically transferring an information signal from the information carrier M to the magnetic recording medium W (hereinafter sometimes referred to as a magnetic transfer step). The magnetic transfer step is shown in FIGS. As shown, the CoPt magnetic layer 101a and the FePt magnetic layer 101b use a master information carrier M including a multilayer magnetic layer 101 in which at least one layer is laminated.

  Further, the magnetic transfer step provided in the method for manufacturing the magnetic recording medium 10 of the present embodiment more specifically, after the master information carrier M and the magnetic recording medium W are overlapped, the back side of the master information carrier M That is, on the side opposite to the magnetic recording medium W side, an external magnetic field is applied to the magnetic recording medium W while rotating the magnetic field generating means G made of a sintered magnet, so that the magnetic recording medium is transferred from the master information carrier M. A magnetic recording medium 10 can be manufactured by magnetically transferring an information signal to W.

A magnetic recording medium 10 obtained by applying the manufacturing method of the present invention has a magnetic recording pattern (not shown) magnetically separated on a nonmagnetic substrate 1 as in the example shown in FIG. It is a plate-like plate having a substantially donut shape in plan view (see also reference numeral 10 in FIG. 3). Further, as illustrated in FIG. 2, the magnetic recording medium 10 is schematically configured by sequentially laminating at least a perpendicular magnetic layer 4 having a magnetic pattern and a protective layer 5 on a nonmagnetic substrate 1. . In the illustrated example, the magnetic recording medium 10 includes a soft magnetic underlayer 2 including two soft magnetic layers 2 a antiferromagnetically coupled to a nonmagnetic substrate 1 by a spacer layer 2 b, and an orientation control layer 3. The perpendicular magnetic layer 4, the protective layer 5, and the lubricant film 6 are sequentially laminated. In the illustrated example, the perpendicular magnetic layer 4 includes three layers of a lower magnetic layer 4a, an intermediate magnetic layer 4b, and an upper magnetic layer 4c, and is nonmagnetic between the magnetic layer 4a and the magnetic layer 4b. The non-magnetic layer 7b is sandwiched between the magnetic layer 4b and the magnetic layer 4c so that the magnetic layers 4a to 4c and the non-magnetic layers 7a and 7b are alternately stacked.
In the present invention, among these layers, layers other than the nonmagnetic substrate 1, the perpendicular magnetic layer 4, and the protective layer 5 can be appropriately selected and provided.

  Hereinafter, each step in the method of manufacturing the magnetic recording medium of the present embodiment will be described in detail with reference to FIGS. 1A, 1B, and 2 as appropriate.

"Lamination process (process for obtaining magnetic recording media)"
In the method of manufacturing the magnetic recording medium 10 according to the present invention, as a method of forming the soft magnetic underlayer 2, the orientation control layer 3, the perpendicular magnetic layer 4, the protective layer 5 and the lubricant film 6 on the nonmagnetic substrate 1, Conventionally known methods can be used without any limitation. Therefore, in this embodiment, a part of the detailed description of the process of forming each layer is omitted.

First, as shown in FIG. 2, a soft magnetic underlayer 2 is formed on a nonmagnetic substrate 1.
Specifically, a soft magnetic underlayer including two soft magnetic layers 2a antiferromagnetically coupled by a spacer layer 2b by depositing a soft magnetic material on the nonmagnetic substrate 1 using, for example, a sputtering method. 2 is formed. At this time, as a material of each layer constituting the soft magnetic underlayer 2, a conventionally known material such as an alloy containing Co as a main component can be used without any limitation.
In general, a sputtering method is used as a method for forming the soft magnetic underlayer 2, but other known methods can be used as appropriate.

  Next, as shown in FIG. 2, an orientation control layer 3 is further laminated on the soft magnetic underlayer 2 formed on the nonmagnetic substrate 1. At this time, a conventionally known material can be used as the material used for the orientation control layer 3, and a conventionally known method can be employed without any limitation as a forming method thereof.

Next, as shown in FIG. 2, the perpendicular magnetic layer 4 is further laminated on the orientation control layer 3. At this time, as shown in the example shown in FIG. 2, the perpendicular magnetic layer 4 can be formed to include three layers including a lower magnetic layer 4a, an intermediate magnetic layer 4b, and an upper magnetic layer 4c. Further, as in the illustrated example, the nonmagnetic layer 7a is further formed between the magnetic layer 4a and the magnetic layer 4b, and the nonmagnetic layer 7b is formed between the magnetic layer 4b and the magnetic layer 4c, whereby the magnetic layers 4a to 4b are formed. 4c and nonmagnetic layers 7a and 7b may be alternately stacked.
Moreover, a conventionally well-known material can be employ | adopted also as a material used for the perpendicular magnetic layer 4, As a formation method, conventionally well-known methods, such as a general magnetron sputtering method, can be employ | adopted without a restriction | limiting at all. .

  Next, as shown in FIG. 2, a protective layer 5 is formed so as to cover the perpendicular magnetic layer 4 formed in the above process. At this time, the protective layer 5 is formed by depositing a protective layer material as a thin film on the perpendicular magnetic layer 4 using, for example, a method such as P-CVD (plasma chemical vapor deposition). Further, the method for forming the protective layer 5 is not limited to the above-described P-CVD method, and a conventionally known method such as an ion beam method can be appropriately employed.

As a material of the protective layer 5, in addition to a hard carbon film such as Diamond Like Carbon generally used in the field, a material containing a protective layer material that is usually used can be used.
In the case of forming a hard carbon film as the protective layer 5, for example, as a forming device, a source gas containing carbon is excited and decomposed by high-frequency plasma, and carbon ions generated thereby are used to form the magnetic recording medium W. A film forming apparatus for forming carbon films on both surfaces of the nonmagnetic substrate 1 can be used.

  The protective layer 5 made of a hard carbon film formed by such a film forming apparatus and film forming method has very high adhesion, and becomes a dense film with high hardness. For this reason, when such a hard carbon film is used for the protective layer 5 of the magnetic recording medium W, the protective layer 5 can be made thin. As a result, the distance between the magnetic recording medium 10 obtained by magnetic transfer to the magnetic recording medium W and the magnetic head (see reference numeral 57 in FIG. 3) can be set narrow, so that the magnetic recording medium 10 Recording density of the magnetic recording medium 10 and the corrosion resistance of the magnetic recording medium 10 can be improved.

  Next, as shown in FIG. 2, a lubricant layer 6 made of a lubricant material is further formed on the protective layer 5 formed in the above step. At this time, as a material used for the lubricant layer 6, for example, a lubricant material such as perfluoropolyether, fluorinated alcohol, and fluorinated carboxylic acid can be used without any limitation.

(Cleaning process of magnetic recording media)
Next, in the present invention, after the magnetic recording medium W is manufactured in the above-described steps, the surface of the magnetic recording medium W is processed by a conventionally known wiping process or burnishing process before magnetic transfer is performed in a process described later. It is more preferable to perform the magnetic transfer described later with higher accuracy.

  The wiping process is performed using, for example, a cloth wiping tape as described in JP-A-10-106229. Specifically, although detailed illustration of the wiping process is omitted, the surface of the wiping tape is moved by the rubber contact roll or pad while the wiping tape is moved relative to the surface of the magnetic recording medium W. This is a process of lightly wiping the medium surface by pressing against the surface of W. By performing such processing, sputter dust and the like adhering to the surface of the magnetic recording medium W are removed, and the medium surface is cleaned.

  Examples of the wiping tape used for the wiping treatment include a wiping tape obtained by slitting a cloth made of ultrafine fibers into a belt shape, and a woven or knitted fabric of ultrafine fiber multifilament yarn.

  Further, the wiping tape is stretched between a supply reel and a take-up reel (not shown), is sequentially supplied from the supply reel, and is sequentially taken up by the take-up reel. In the course of traveling from the supply reel side to the take-up reel side, the surface (back surface) opposite to the wiping tape wiping surface is pressed by a backing roll such as rubber or felt, and the wiping surface of the wiping tape becomes magnetic. It is pressed against the surface of the recording medium W.

  The burnishing process is a process of polishing the surface using a polishing tape in order to remove protrusions on the surface of the magnetic recording medium W. This prevents a transfer pattern from becoming unclear or damaging the master information carrier M due to a gap between the magnetic recording medium W and the master information carrier M in a magnetic transfer process described later. It becomes possible. Further, when the magnetic recording medium 10 manufactured by performing magnetic transfer on the magnetic recording medium W is used to constitute a hard disk drive (see the magnetic recording / reproducing apparatus 50 shown in FIG. 3), the flying height of the magnetic head is further reduced. It becomes possible to do.

  Such burnishing is performed using a polishing tape coated with alumina abrasive grains, as described in, for example, Japanese Patent Application Laid-Open No. 11-277339. That is, the burnishing process is a process of lightly polishing the surface of the medium by pressing a polishing tape against the surface of the magnetic recording medium W using a rubber contact roll, although detailed illustration is omitted. More specifically, the rotation is performed by pressing the abrasive grain surface of the polishing tape against the surface of the magnetic recording medium W while rotating the magnetic recording medium W. Thereby, the protrusions on the surface of the magnetic recording medium W are polished and removed, and the surface of the medium is smoothed. Here, the polishing tape is stretched between the supply reel and the take-up reel, sequentially supplied from the supply reel, and sequentially taken up by the take-up reel. Then, while traveling from the supply reel side to the take-up reel side, the surface (back surface) opposite to the abrasive grain surface of the polishing tape is pressed by a backing roll such as rubber or felt, and the polishing surface of the polishing tape. Is pressed against the surface of the magnetic recording medium W.

  As the polishing tape (burnish tape) used for the burnishing treatment, a tape having an abrasive layer formed on a polyester base film is usually used. This abrasive layer slides in contact with the surface of the magnetic recording medium W, thereby removing minute dust adhering to the surface of the medium and polishing / removing abnormal protrusions existing on the surface of the medium. As a result, the surface of the medium is smoothed.

  As an abrasive, for example, chromium oxide, α-alumina, silicon carbide, nonmagnetic iron oxide, diamond, γ-alumina, α, γ-alumina, fused alumina, corundum having an average particle size of about 0.05 μm to 50 μm. Artificial diamond or the like is used.

  In general, the wiping process and the burnishing process as described above are performed after the formation of the lubricant layer 6. In the present invention, in addition to these processes, a magnetic recording medium is further used by using a cleaning agent. It is more preferable to perform W cleaning treatment. That is, it is more preferable to remove contaminants on the surface of the magnetic recording medium W, which cannot be removed by the wiping process or the burnishing process, with the cleaning agent.

  Here, the contaminants as described above may be difficult to remove by washing after the step of forming the lubricant layer 6, the wiping process, and the burnishing process. The reason for this is speculated that if the contaminant is covered with the lubricant film 6, it becomes difficult to remove the contaminant due to its water repellency, and after wiping or burnishing, the contaminant is removed from the magnetic recording medium. It can be considered that it is difficult to remove it. For this reason, when the process of cleaning the magnetic recording medium with a cleaning agent is employed, it is preferably performed before the lubricant layer 6 is formed.

  Specifically, a method of immersing the magnetic recording medium W in the cleaning liquid in the cleaning tank is used for the surface of the magnetic recording medium on which the protective layer 5 is formed, for example, using a non-aqueous cleaning agent using a fluorine compound. it can. At this time, it is more preferable to apply ultrasonic vibration to the cleaning liquid in the cleaning tank because the cleaning power can be further increased. In addition, after the magnetic recording medium is cleaned using the cleaning liquid, a multi-step process of performing ultra-short immersion cleaning such as spin cleaning using pure water or pulling drying using dry air is adopted. You can also.

  As described above, before the magnetic transfer is performed, the surface of the magnetic recording medium W is washed by the above-described methods, so that dust, foreign matter, contaminants, and the like attached to the surface can be efficiently removed. Thereby, it is possible to prevent foreign matter and the like from being caught between the master information carrier M and the magnetic recording medium W in the magnetic transfer process described later, and high-precision magnetic transfer can be performed.

"Magnetic transfer process"
In the magnetic transfer process provided in the manufacturing method of the present invention, writing of a servo signal or the like to the magnetic recording medium W manufactured in the laminating process and cleaned in the cleaning process of the above conditions as necessary. Processing is performed by magnetic transfer.

  Specifically, in the magnetic transfer step, first, the signal recording surface of the magnetic recording medium W is initially magnetized. This initial magnetization is performed by applying an initial DC magnetic field in one direction in the track direction in the case of an in-plane magnetic recording medium, and in one direction in the direction perpendicular to the medium surface in the case of a perpendicular magnetic recording medium. By applying an initial DC magnetic field. This initial DC magnetic field can be applied using a permanent magnet or an electromagnet. As the permanent magnet, it is preferable to use an NdFeB-based sintered magnet that is more stable and has a strong magnetic force. In addition, it is preferable to apply the initial DC magnetic field 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.

  Next, as shown in FIG. 1A, the signal recording surface of the magnetic recording medium W after application of the initial DC magnetic field, and the master information carrier M on which the transfer pattern corresponding to the servo signal and the like is formed. In a state where the transfer surface is in contact with each other, they are brought into close contact with each other with a predetermined pressing force. Then, in this state, the magnetic field generating means G is configured so as to be relative to the transfer surface of the master information carrier M using, for example, a magnetic field generating means G configured to generate a magnetic field while the sintered magnet rotates. An external magnetic field for transfer is applied while moving in the track direction X. This external magnetic field for transfer is a magnetic field in the opposite direction to the initial DC magnetic field described above. Thereby, in the magnetic recording medium W, magnetization reversal occurs at a position facing the transfer pattern of the master information carrier M, and a magnetization pattern corresponding to a servo signal or the like is written by magnetic transfer.

  In FIG. 1A, for convenience of explanation, the magnetic recording medium W is shown only by the nonmagnetic substrate 1 and the perpendicular magnetic layer 4 and is laminated on the magnetic layer 101 as a master information carrier M. The protective layer (see reference numeral 102 in FIG. 1B) is omitted.

The master information carrier M used in the production method of the present invention can be produced by the following method.
Specifically, first, an electron beam resist is applied to the surface of a silicon wafer by spin coating. Next, the resist is irradiated with an electron beam modulated in accordance with a servo signal or the like using an electron beam exposure apparatus, and after exposure and development of the resist, silicon is removed by removing unexposed portions. A resist pattern corresponding to the transfer pattern is formed on the wafer.

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

  Next, a conductive layer made of Ni with a thickness of about 10 nm is formed on the master by sputtering. Next, 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 matrix. Thereafter, the Ni layer is removed from the master, and the Ni layer is cleaned and the like, and the Ni base material 100 having the convex portions 100a and the concave portions 100b formed on the surface as shown in FIG. 1A is obtained. In FIG. 2B, the convex portion 100a and the concave portion 100b provided in the magnetic layer 101 are omitted.

  Next, the magnetic layer 101 made of a perpendicular magnetic film is formed on the surface of the Ni substrate 100. The magnetic layer 101 can be made of the same material as that of the perpendicular magnetic layer 4 used in the magnetic recording medium W described above, and can be formed using the same method.

In the present invention, as shown in detail in FIG. 1B, at least one or more of the CoPt magnetic layer 101a and the FePt magnetic layer 101b are stacked in the magnetic layer 101 provided in the master information carrier M. It is configured as a multilayer structure. In the example shown in FIG. 1B, the CoPt magnetic layer 101a and the FePt magnetic layer 101b are alternately laminated in three layers on the Ni substrate 100.
As described above, when the magnetic layer 101 is formed on the Ni substrate 100 as a multilayer structure including the CoPt magnetic layer 101a and the FePt magnetic layer 101b, for example, the target is appropriately changed in the chamber of the DC sputtering apparatus. The method to do can be adopted.

  As a result of intensive research by the present inventors, when magnetic transfer using a master information carrier with CoPt as the material of the magnetic layer is performed, the writability in a low magnetic field is improved, and the material of the magnetic layer is changed. In the case of using FePt, it became clear that the writeability in a high magnetic field was improved. Based on the above knowledge, the present inventors have made the magnetic layer 101 of the master information carrier M a multilayer structure composed of the CoPt magnetic layer 101a and the FePt magnetic layer 101b, so that it can be stable in both high and low magnetic fields. And found that uniform magnetic transfer can be achieved. In the present invention, by performing magnetic transfer using the master information carrier M provided with the magnetic layer 101 having such a configuration, transferability to the magnetic recording medium W having a large coercive force dispersion can be improved.

Further, in the magnetic layer 101 provided in the master information carrier M used in the present invention, the CoPt magnetic layer 101a contains at least 70 atomic% or more of Co and Pt, and each content is represented by the following formula {Co> Pt}. More preferably, the FePt magnetic layer 101b contains at least 60 atomic% or more of Fe and Pt, and each content satisfies the following formula {Fe> Pt}. preferable. When the composition of the CoPt magnetic layer 101a is in the above relationship, the writability with respect to the magnetic recording medium W in a low magnetic field is further improved, and the composition of the FePt magnetic layer 101b is in the above relationship so that the write property in a high magnetic field is achieved. Is further improved.
In the present invention, other elements can be added to the CoPt magnetic layer or the FePt magnetic layer. The element to be added is appropriately selected mainly for the purpose of refining, isolating, and homogenizing the magnetic particle diameter of the magnetic particles constituting the magnetic layer. For example, Cr, B, Nd, Pr, Ru, There are Cu, Si, Pd, SiO ₂ , Cr ₂ O ₃ , and TiO ₂ .

  In the present invention, the magnetic layer 101 provided in the master information carrier M is formed by alternately laminating a plurality of CoPt magnetic layers 101a and FePt magnetic layers 101b. More preferable. In the example shown in FIG. 2, in the Ni base material 100, a plurality of CoPt magnetic layers 101a and FePt magnetic layers 101b are alternately stacked in this order from the Ni base material 100 side. Are stacked.

  Of the magnetic layer 101 formed on the surface of the Ni substrate 100, the magnetic layer 101 in the portion where the convex portion 100a is formed is used for magnetic transfer to the magnetic recording medium W, and the concave portion 100b is formed. Since the formed magnetic layer 101 is not in contact with the magnetic recording medium W, it is not used for magnetic transfer.

  Further, as shown in FIG. 1B, the protective layer 102 is formed on the Ni base material 100 by applying the same material as that of the protective layer 4 used in the magnetic recording medium W described above. This protective layer 102 is for enhancing the wear resistance of the master information carrier M. For example, by applying a hard carbon film material or the like by a conventionally known method, a carbon film having a thickness of about several nm is formed. It is formed.

The master information carrier M on which a transfer pattern corresponding to a servo signal or the like is formed can be obtained by the method as described above. The master information carrier M obtained in this way can be used repeatedly when performing magnetic transfer.
Further, the master information carrier M used in the present invention has a multi-layer structure composed of the CoPt magnetic layer 101a and the FePt magnetic layer 101b as described above, so that it is stable in both high and low magnetic fields. And uniform magnetic transfer. By using the master information carrier M provided with the magnetic layer 101 having such a configuration, it is possible to improve transferability when performing magnetic transfer on the magnetic recording medium W having a large coercive force dispersion.

  The magnetic field generating means G can be composed of a permanent magnet such as a sintered magnet, an electromagnet, or the like. In the case of an in-plane magnetic recording medium, an external magnetic field for transfer is generated in the other direction of the track, and perpendicular magnetic recording is performed. In the case of a medium, an external magnetic field for transfer is generated in the other direction perpendicular to the medium surface. The magnetic field generating means G can be rotated 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.

  In the present invention, as the permanent magnet used in the magnetic field generating means G, a more stable and strong magnetic NdFeB-based sintered magnet can be employed. And it can be set as the structure which generates a magnetic field, rotating a sintered magnet in the back surface side of the magnetic recording medium W, ie, the opposite side to the magnetic recording medium W.

  For example, when an NdFeB sintered magnet having a saturation magnetic flux density of about 3 Tesla is used as the magnetic field generating means G, the sintered magnet is usually configured in a rectangular parallelepiped shape, and the magnetic recording medium W A magnetic field is generated by rotating on the back side. However, when a magnetic field is generated with such a configuration, as described above, the magnetic field generated from the sintered magnet is not necessarily uniform. Therefore, the conventional method performs stable magnetic transfer over the entire surface of the magnetic recording medium. It has become difficult.

  In the present invention, the magnetic layer 101 of the master information carrier M has a multilayer structure composed of the CoPt magnetic layer 101a and the FePt magnetic layer 101b, so that the magnetic transfer can be performed stably and uniformly in either a high magnetic field or a low magnetic field. be able to. That is, even when the magnetic field generating means G configured to generate a magnetic field by rotating the sintered magnet is used on the back side of the master information carrier M, stable magnetic transfer can be performed. Therefore, for example, even when magnetic transfer is performed on the magnetic recording medium W in which the coercive force of the perpendicular magnetic layer 4 is increased to 4000 oersted or more, excellent transferability can be obtained.

  Here, the magnetic recording medium 10 built in the hard disk drive generally has a magnetic layer formed on both surfaces of the non-magnetic substrate 1, and a single hard disk drive has a plurality of magnetic recording media 10. Is often built-in. For this reason, in a hard disk drive, a plurality of magnetic heads are integrally moved and operated by a stack structure, but the track width of the magnetic recording medium 10 is becoming increasingly narrow, and data is written on the signal recording surface of one magnetic recording medium 10. It is difficult to position the magnetic head on another signal recording surface using the servo signal or the like because of the accuracy of the stack structure of the head. Therefore, in the magnetic transfer process of the present invention, it is preferable to write servo signals or the like on both surfaces of the magnetic recording medium W by magnetic transfer. Specifically, both surfaces of the magnetic recording medium W are sandwiched between a pair of master information carriers M, and in this state, transfer is performed using the magnetic field generating means G from the side opposite to the transfer surface of the master information carriers M. Apply an external magnetic field. Thereby, servo signals and the like can be written on both surfaces of the magnetic recording medium W.

  The magnetic transfer process provided in the manufacturing method of the present invention employs a method of performing magnetic transfer on the magnetic recording medium W using the master information carrier M provided with the magnetic layer 101 having the multilayer structure as described above. . As a result, when performing magnetic transfer to the magnetic recording medium W, magnetic transfer can be performed efficiently, with high accuracy, stably and uniformly without imperfect magnetic transfer in either a high magnetic field or a low magnetic field. Further, transferability to the magnetic recording medium W having a large coercive force dispersion can be improved.

  The coercive force Hc of the perpendicular magnetic layer 4 is usually 320 kA / m (about 4000 Oe) or more. Therefore, in the magnetic transfer process, after the perpendicular magnetic layer 4 is initially DC magnetized, both sides of the magnetic recording medium W are sandwiched by the master information carrier M, and a magnetic field having a magnetic transfer strength is applied via the master information carrier M. Thus, it is preferable to perform magnetic transfer.

  After the magnetic transfer step, a glide inspection is performed on the obtained magnetic recording medium 10. The glide inspection is a process for inspecting whether or not there are projections on the surface of the magnetic recording medium 10. That is, when recording / reproduction is performed on the magnetic recording medium 10 using the magnetic head, if there is a protrusion with a height higher than the flying height (the distance between the medium and the magnetic head) on the surface of the magnetic recording medium 10, The head collides with the protrusions, which may cause damage to the magnetic head or cause a defect in the magnetic recording medium 10. In the glide inspection, the presence or absence of such high protrusions is inspected.

  The magnetic recording medium 10 that has passed the glide inspection is normally subjected to a certification inspection. The certification inspection is similar to recording / reproduction of a normal hard disk drive, after a predetermined signal is recorded on the magnetic recording medium 10 with a magnetic head, the signal is reproduced, and the magnetic recording medium is reproduced by the obtained reproduction signal. 10 is used to check the quality of the medium such as the electrical characteristics of the magnetic recording medium 10 and the presence or absence of defects.

  The magnetic recording medium 10 manufactured by applying the present invention is different from the conventional certify inspection because servo signals and the like are already written therein. That is, in the magnetic recording medium 10 manufactured by applying the present invention, an inspection of a format in which reading / writing is performed by positioning the magnetic head at a specific position using a servo signal or the like magnetically transferred to the magnetic recording medium 10 is performed. Do.

  In the present invention, a foreign matter is generated between the master information carrier M and the magnetic recording medium W by performing magnetic transfer on the magnetic recording medium W whose surface is highly cleaned by the various cleaning methods described above. It is possible to suppress biting, and it is possible to perform magnetic transfer with higher accuracy.

[Magnetic recording medium]
Next, an example of the magnetic recording medium 10 manufactured by applying the present invention is shown in FIG. The magnetic recording medium 10 shown in FIG. 2 includes a soft magnetic underlayer 2 including two soft magnetic layers 2a antiferromagnetically coupled by a spacer layer 2b on a nonmagnetic substrate 1, an orientation control layer 3, and the like. The perpendicular magnetic layer 4, the protective layer 5, and the lubricant film 6 are sequentially laminated.

  The perpendicular magnetic layer 4 includes three layers of a lower magnetic layer 4a, an intermediate magnetic layer 4b, and an upper magnetic layer 4c, and a nonmagnetic layer 7a is interposed between the magnetic layer 4a and the magnetic layer 4b. By sandwiching the nonmagnetic layer 7b between the magnetic layer 4b and the magnetic layer 4c, the magnetic layers 4a to 4c and the nonmagnetic layers 7a and 7b are alternately stacked.

  The magnetic recording medium 10 obtained by applying the manufacturing method of the present invention includes the perpendicular magnetic layer 4 that is magnetized in the perpendicular direction of the nonmagnetic substrate 1, thereby providing a magnetic head 57 that includes a read head and a write head. (See the magnetic recording / reproducing apparatus 50 in FIG. 3), information signals are written to and read from a magnetic recording pattern (not shown).

  As the nonmagnetic substrate 1, for example, a metal substrate made of a metal material such as aluminum or an aluminum alloy may be used, and a nonmetal substrate made of a nonmetal material such as glass, ceramic, silicon, silicon carbide, or carbon. May be used. In addition, it is also possible to use a substrate in which a NiP layer or a NiP alloy layer is formed on the surface of the metal substrate or nonmetal substrate by using, for example, a plating method or a sputtering method.

  As the glass substrate used for the nonmagnetic substrate 1, 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, 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 1 has an average surface roughness (Ra) of 1 nm (10 mm) or less, more preferably 0.5 nm or less, which is suitable for high recording density recording with a magnetic head flying low. To preferred. Further, it is more suitable for high recording density recording in which the magnetic head is floated as described above that the surface waviness (Wa) is 0.3 nm or less (more preferably 0.25 nm or less). Further preferred. In addition, it is possible to use a magnetic head having a surface average roughness (Ra) of at least one of the chamfered portion of the chamfer portion on the end surface and the side surface portion of 10 nm or less, more preferably 9.5 nm or less. From the point of view, it is 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, when the nonmagnetic substrate 1 is in contact with the soft magnetic underlayer 2 mainly composed of Co or Fe, the corrosion may proceed due to the influence of surface adsorption gas, moisture, diffusion of substrate components, and the like. . In such a case, it is preferable to provide an adhesion layer (not shown) between the nonmagnetic substrate 1 and the soft magnetic underlayer 2, thereby suppressing the above-described corrosion progress. The material of the adhesion layer can be appropriately selected from, for example, Cr, Cr alloy, Ti, Ti alloy and the like. The thickness of the adhesion layer is preferably 2 nm (20 mm) or more.

  As the soft magnetic layers 2a and 2c, it is preferable to use a material containing Fe: Co in the range of 40:60 to 70:30 (atomic ratio). Moreover, in order to improve the magnetic permeability and corrosion resistance, it is more preferable to contain any one selected from Ta, Nb, Zr, and Cr in the range of 1 to 8 atomic%. As the spacer layer 2b, Ru, Re, Cu, or the like can be used. Among these, it is particularly preferable to use Ru.

  The orientation control layer 3 is for improving the recording / reproducing characteristics by refining the crystal grains of the perpendicular magnetic layer 4. The material of the orientation control layer 3 is not particularly limited, but it is preferable to use a material having an hcp structure, an fcc structure, or an amorphous structure. In particular, a Ru-based alloy, Ni-based alloy, Co-based alloy, Pt-based alloys and Cu-based alloys are preferably used. These alloys may be multilayered, for example, a multilayer structure of Ni-based alloy and Ru-based alloy, a multilayer structure of Co-based alloy and Ru-based alloy, a Pt-based alloy and a Ru-based alloy from the substrate side. It is preferable to adopt a multilayer structure.

  Here, in the initial part of the perpendicular magnetic layer 4 immediately above the orientation control layer 3, disorder of crystal growth is likely to occur, which causes noise. In such a case, it is preferable to provide a nonmagnetic underlayer 8 between the orientation control layer 3 and the perpendicular magnetic layer 4. Thereby, the disordered part in the initial part of the perpendicular magnetic layer 4 can be replaced with the nonmagnetic underlayer 8, and the generation of noise can be suppressed.

As the nonmagnetic underlayer 8, it is preferable to use a material composed mainly of Co and further containing an oxide. The Co content in the nonmagnetic underlayer 8 is preferably 25 atomic% or more and 50 atomic% or less. As the oxide, for example, oxides such as Cr, Si, Ta, Al, Ti, Mg, and Co are preferably used, and among them, TiO ₂ , Cr ₂ O ₃ , SiO _{2 and the} like are particularly preferably used. Can do. The content of the oxide is preferably 3 mol% or more and 18 mol% or less with respect to the total mol amount of the magnetic particles, for example, an alloy such as Co, Cr, and Pt calculated as one compound.

As the magnetic layers 4a, 4b, and 4c constituting the perpendicular magnetic layer 4, it is preferable to use a material mainly containing Co and further containing an oxide. Examples of the oxide include Cr, Si, Ta, It is preferable to use an oxide such as Al, Ti, Mg, or Co. Among these, in _particular, it can be used TiO _{2, Cr} 2 O 3, a SiO ₂ or the like suitably. The lower magnetic layer 4a is preferably made of a complex 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 4a, 4b, and 4c, for example, 90 (Co14Cr18Pt) -10 (SiO ₂ ) {Cr content of 14 atomic%, Pt content of 18 atomic%, and the remainder of Co containing one magnetic particle. molar concentrations calculated as compound 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) - (TiO2), (CoCrPtB) _{(Al 2 O 3), (} CoCrPtTaNd) - (MgO), (CoCrPtBCu) - (Y 2 O 3), (CoCrPtRu) - can be exemplified (SiO ₂₎ composition, and the like.

  In the present invention, the perpendicular magnetic layer 4 having the above composition can be composed of four or more magnetic layers. For example, in addition to the magnetic layers 4a and 4b, a magnetic layer having a granular structure is constituted by three layers, and a magnetic layer 4c not containing an oxide is provided thereon, and a magnetic layer not containing an oxide is also provided. The layer 4c may have a two-layer structure and be provided on the magnetic layers 4a and 4b.

  Further, in the present invention, as shown in FIG. 2A, it is more preferable to further provide nonmagnetic layers 7a and 7b between each of three or more magnetic layers constituting the perpendicular magnetic layer 4. Thus, by providing the nonmagnetic layer 7 with an appropriate thickness between the layers of the perpendicular magnetic layer 4, magnetization reversal of individual films can be facilitated, and dispersion of magnetization reversal of the entire magnetic particles can be reduced. it can. As a result, the S / N ratio of the magnetic recording medium can be further improved.

The protective layer 5 is provided to prevent corrosion of the perpendicular magnetic layer 4 and to prevent damage to the surface of the medium when the magnetic head (see reference numeral 57 in FIG. 3) contacts the magnetic recording medium. It is. As such a protective layer 5, a conventionally well-known material can be used, for example, it can be comprised from a hard carbon film (C). In addition, as the material of the protective layer 5, it is possible to use a material containing a commonly used protective layer material such as SiO ₂ or ZrO ₂ .

  The thickness of the protective layer 5 is preferably in the range of 1 to 10 nm because the distance between the magnetic head and the magnetic recording medium can be reduced, which is preferable from the viewpoint of high recording density. When the thickness of the protective layer exceeds the above range, the distance between the magnetic head and the perpendicular magnetic layer becomes large, and there is a possibility that a sufficiently strong input / output signal cannot be obtained. The protective layer 5 may be composed of two or more layers.

  The lubricant film 6 is formed, for example, by applying a lubricant such as perfluoropolyether, fluorinated alcohol, or fluorinated carboxylic acid on the protective layer 5. The lubricant film 6 is usually formed with a thickness of about 1 to 4 nm.

  In the magnetic recording medium 10, the above-described configuration allows the magnetic recording pattern (not shown) formed by the perpendicular magnetic layer 4 to be magnetically recorded by the magnetic head (see the magnetic head 57 of the magnetic recording / reproducing apparatus 50 shown in FIG. 3). The reproduction can be performed. In addition, since the magnetic recording medium 10 of the present embodiment is obtained by the manufacturing method according to the present invention, excellent recording / reproducing characteristics are ensured and high recording density can be accommodated.

[Magnetic recording / reproducing device]
Next, FIG. 3 shows a configuration of a magnetic recording / reproducing apparatus (hard disk drive) including the magnetic recording medium 10 manufactured by applying the present invention.
A magnetic recording / reproducing apparatus 50 shown in FIG. 3 includes a magnetic recording medium 10 manufactured by applying the present invention as shown in FIG. 2, a medium driving unit 51 that drives the magnetic recording medium 10 in the recording direction, and a recording A magnetic head 57 that records and reproduces information on the magnetic recording medium 10, a head drive unit 58 that moves the magnetic head 57 relative to the magnetic recording medium 10, and a signal input to the magnetic head 57. The recording / reproducing signal system 59 is combined with recording / reproducing signal processing means for reproducing the output signal from the magnetic head 57. By combining these, the magnetic recording / reproducing apparatus 50 with high recording density can be configured.

  The recording / reproducing signal system 59 can process data input from the outside and send the recording signal to the magnetic head 57, and can process the reproducing signal from the magnetic head 57 and send the data to the outside. ing. As the magnetic head 57 provided in the magnetic recording / reproducing apparatus, a magnetic head suitable for a higher recording density having a GMR element utilizing a giant magnetoresistive effect (GMR) as a reproducing element can be used.

  According to the magnetic recording / reproducing apparatus 50 having the above configuration, as the magnetic recording medium, the magnetic recording medium 10 manufactured by applying the present invention and having high recording density, high-speed writing, and excellent electromagnetic conversion characteristics is employed. It is possible to realize an excellent hard disk drive.

  According to the method of manufacturing the magnetic recording medium 10 according to the present invention as described above, the CoPt magnetic layer 101a and the FePt magnetic layer 101b can be used for magnetic transfer to the magnetic recording medium W as described above. A method using a master information carrier M in which each layer includes a magnetic layer 101 having a multilayer structure in which at least one layer is laminated is adopted. As a result, when performing magnetic transfer by superimposing the master information carrier M and the magnetic recording medium W, the magnetic transfer is not incomplete in either a high magnetic field or a low magnetic field. Thus, the magnetic transfer can be performed uniformly, and the transferability to the magnetic recording medium W having a large coercive force dispersion is improved. Therefore, the magnetic recording medium 10 having a high recording density can be manufactured efficiently and at low cost.

  Next, the manufacturing method of the magnetic recording medium of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples, and the gist thereof is not changed. It can be implemented with appropriate modifications within the range.

[Example]
(Manufacture of magnetic recording media)
In Examples, first, a cleaned glass substrate (manufactured by Konica Minolta Co., Ltd., 2.5 inches in outer diameter) is accommodated in a film forming chamber of a DC magnetron sputtering apparatus (C-3040 made by Anelva Co., Ltd.), and the ultimate vacuum is achieved. After evacuating the film formation chamber to 1 × 10 ⁻⁵ Pa, an adhesion layer having a thickness of 10 nm was formed on the glass substrate using a 60Cr-40Ti target. Further, on this adhesion layer, a target of 46Fe-46Co-5Zr-3B {Fe content 46 atomic%, Co content 46 atomic%, Zr content 5 atomic%, B content 3 atomic%} was used. A soft magnetic layer having a layer thickness of 34 nm is formed at a substrate temperature of 100 ° C. or less, and a Ru layer is formed thereon with a layer thickness of 0.76 nm. Then, a soft magnetic layer of 46Fe-46Co-5Zr-3B is formed. A layer having a thickness of 34 nm was formed and used as a soft magnetic underlayer.

  Next, on the soft magnetic underlayer, Ni-6W {W content 6 atom%, balance Ni} target and Ru target were sequentially formed with a layer thickness of 5 nm and 20 nm, respectively, and these were oriented. The control layer was used.

Then, on the orientation control layer, a magnetic layer of a multilayer structure, 84 (Co12Cr16Pt) -16TiO ₂ (film thickness 3nm), Ru47.5Co (thickness 0.5nm), 91 (Co11.5Cr13Pt10Ru) -4SiO 2 -3Cr ₂ O ₃ -2TiO ₂ (film thickness: 3 nm) and Co15Cr16Pt6B (film thickness: 3 nm) were stacked.

  Next, a carbon protective layer having a layer thickness of 2.5 nm was formed on the magnetic layer by a CVD method.

  Next, the surface of the magnetic recording medium on which the protective layer was formed was washed. Specifically, the surface of the protective layer was cleaned by immersing the magnetic recording medium having the protective layer formed therein in a cleaning liquid in a cleaning tank using a non-aqueous cleaning agent using a fluorine compound.

  Then, a lubricant layer made of perfluoropolyether was formed to a thickness of 15 angstroms on the surface of the protective layer after washing by dipping, thereby obtaining the magnetic recording medium of the example.

  Next, a wiping process was performed on the magnetic recording medium that had been cleaned up after the formation of the lubricant layer. At this time, as the wiping tape, a tape made of a peelable conjugate fiber having a wire diameter of 2 μm made of nylon resin and polyester resin was used. The wiping process was performed with the rotational speed of the magnetic recording medium being 300 rpm, the wiping tape feed speed being 10 mm / second, the pressing force when pressing the wiping tape against the magnetic recording medium was 98 mN, and the processing time being 5 seconds.

  Next, a burnishing process was performed on the magnetic recording medium subjected to the wiping process. At this time, as the burnish tape, a film in which crystal growth type alumina particles having an average particle diameter of 0.5 μm were fixed with an epoxy resin on a polyethylene terephthalate film was used. The burnishing process was performed with the rotational speed of the magnetic recording medium being 300 rpm, the polishing tape feed speed of 10 mm / second, the pressing force when pressing the polishing tape against the magnetic disk was 98 mN, and the processing time was 5 seconds.

  Next, initial magnetization was applied to the burnished magnetic recording medium. Specifically, a magnetic field of 10 kOe penetrating the magnetic recording medium was applied to both data surfaces of the magnetic recording medium using an NdFeB-based sintered magnet.

(Manufacture of master information carrier)
A master information carrier having a transfer pattern such as a 271k track / inch servo signal was manufactured. At this time, a master information carrier was manufactured with a track having a width of 120 nm, a track interval of 60 nm, and a transfer pattern step of 45 nm. Further, in this master information carrier, a Ru film having a layer thickness of 10 nm is formed on a Ni base material having a convex portion and a concave portion by using a DC sputtering method, and a magnetic layer is formed thereon with a layer thickness as a magnetic layer. A 5 nm thick 70Co30Pt layer, a 5 nm thick 70Fe30Pt layer, a 5 nm thick 70Co30Pt layer, and a 5 nm thick 70Fe30Pt layer were stacked. A carbon film having a thickness of 20 nm was formed thereon as a protective layer.

(Magnetic transfer process)
Next, servo signals and the like were written on the burnished magnetic recording medium by magnetic transfer using the master information carrier. Specifically, the master information carrier was brought into close contact with both surfaces of the magnetic recording medium subjected to initial magnetization at a pressure of 98 mN, and a recording magnetic field was applied from the back surface of the master information carrier. The intensity of this recording magnetic field was 4 kOe, and the transfer time was 10 seconds.
The magnetic recording medium was manufactured by performing magnetic transfer on the magnetic recording medium under such conditions.

(Evaluation of magnetic recording media after magnetic transfer)
In this example, the following evaluation was performed on the magnetic recording medium manufactured by the above method. Specifically, the reproduction characteristics of the servo signal were measured using a read / write analyzer (model number: RWA1632; manufactured by GUZIK, USA) and a spin stand (model number: S1701MP). This apparatus reads a servo signal or the like recorded on a magnetic recording medium, and can position the magnetic head using this signal. At this time, a magnetic head using TuMR was used as the magnetic head for evaluation, and the S / N ratio at the time of servo signal reading was evaluated. As a result, the S / N ratio during reproduction of the servo signal was 16.8 dB.

[Comparative Example 1]
The magnetic recording medium was magnetically transferred and evaluated in the same manner as in the above example. In Comparative Example 1, a 70Co30Pt layer having a thickness of 20 nm was used as the magnetic layer of the master information carrier. As a result, the S / N ratio during reproduction of the servo signal was 15.9 dB.

[Comparative Example 2]
The magnetic recording medium was magnetically transferred and evaluated in the same manner as in the above example. In Comparative Example 2, a 70Fe30Pt layer having a thickness of 20 nm was used as the magnetic layer of the master information carrier. As a result, the S / N ratio during reproduction of the servo signal was 15.3 dB.

[Comparative Example 3]
Been magnetic transfer and the evaluation of the magnetic recording medium as in the above examples, in Comparative Example 3, as the magnetic layer of the master information carrier, with 70Co-5Cr-15Pt-10SiO ₂ alloy film having a thickness of 20nm . As a result, the S / N ratio during reproduction of the servo signal was 16.3 dB.

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

10: Magnetic recording medium,
W: Magnetic recording medium,
1 ... non-magnetic substrate,
2. Soft magnetic underlayer,
2b Spacer layer,
2a ... soft magnetic layer,
3 ... orientation control layer,
4 ... perpendicular magnetic layer (magnetic layer),
4a, 4b, 4c ... magnetic layer,
5 ... protective layer,
6 ... Lubricant film,
7, 7a, 7b ... nonmagnetic layer,
50. Magnetic recording / reproducing apparatus,
51. Medium drive unit,
57 ... Magnetic head,
58 ... head drive unit,
59. Recording / reproduction signal system,
M ... Master information carrier,
100 ... Ni base material,
100a ... convex part,
100b ... recess,
101: Magnetic layer (perpendicular magnetic film),
101a ... CoPt magnetic layer,
101b ... FePt magnetic layer,
102 ... protective layer,
G: Magnetic field generation means

Claims (5)

After superimposing a magnetic recording medium having at least a magnetic layer on a non-magnetic substrate and a master information carrier on which a transfer pattern corresponding to an information signal is formed, an external magnetic field is applied from the master information carrier side. However, a method of manufacturing a magnetic recording medium including a step of magnetically transferring an information signal from the master information carrier to the magnetic recording medium,
The step of performing magnetic transfer uses a master information carrier comprising a CoPt magnetic layer and a magnetic layer having a multilayer structure in which at least one FePt magnetic layer is laminated. Manufacturing method.   The magnetic layer included in the master information carrier is such that the CoPt magnetic layer contains at least 70 atomic% of Co and Pt, and each content satisfies the following formula {Co> Pt}. The FePt magnetic layer contains Fe and Pt at least 60 atomic% or more, and each content satisfies the following formula {Fe> Pt}. A method for producing the magnetic recording medium according to claim.   3. The magnetic recording medium according to claim 1, wherein the magnetic layer included in the master information carrier is formed by alternately laminating a plurality of CoPt magnetic layers and FePt magnetic layers. Production method.   The magnetic recording medium according to any one of claims 1 to 3, wherein the master information carrier is formed by laminating at least the magnetic layer on a base material on which a concavo-convex pattern is formed. Manufacturing method.   The step of performing the magnetic transfer includes applying the external magnetic field to the magnetic recording medium while rotating the sintered magnet on the back side of the master information carrier after superimposing the master information carrier and the magnetic recording medium. 5. The method of manufacturing a magnetic recording medium according to claim 1, wherein an information signal is magnetically transferred from the master information carrier to the magnetic recording medium.

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