JP2002170231A - Magnetic transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve signal quality by making an adhering distance uniform between a master carrier and a slave medium in a magnetic transfer method for magnetically transferring an information signal such as a servo signal from the master carrier to the slave medium. SOLUTION: When magnetic transfer is preformed by adhering a master carrier 3 bearing information and a slave medium 2 to each other, and applying a transfer magnetic field by a magnetic field generating means 5, the recording surface of the slave medium 2 and the information bearing surface of the master carrier 3 are adhered to each other through a liquid layer 4, and an adhering distance is made uniform across a surface. Liquid having lubricity is preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic transfer method for magnetically transferring information from a master carrier carrying information to a slave medium.

[0002]

2. Description of the Related Art A magnetic transfer method transfers a magnetic pattern corresponding to information (for example, a servo signal) carried on a master carrier by applying a transfer magnetic field while the master carrier and the slave medium are in close contact with each other. It is. Examples of the magnetic transfer method include JP-A-63-183623, JP-A-10-40544, and JP-A-10-26.
No. 9566, and the like.

[0003]

By the way, at the time of magnetic transfer by the above magnetic transfer method, the state of close contact between the slave medium and the master carrier affects the signal quality after the magnetic transfer. Ideally, it is required that the distance between the recording surface of the slave medium and the information carrying surface of the master carrier be 100 nm or less, and that the entire surface be closely adhered in a uniform state.

However, dust is present between the master carrier and the slave medium, and a space is generated between the master carrier and the slave medium near the dust in accordance with the size of the dust. There are cases. For this reason, a difference corresponding to the distance is generated in the transferred magnetic signal and the signal quality is degraded, an intensity distribution is generated in the read reproduction output, and a sufficient tracking function is obtained when the recorded signal is a servo signal. Without the reliability.
It has been found that the main cause of the dust is that dust or the like generated during the manufacturing process of the slave medium adheres to the surface.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a magnetic transfer method capable of making the contact distance between a slave medium and a master carrier uniform in magnetic transfer and improving signal quality. Is what you do.

[0006]

A magnetic transfer method according to the present invention is directed to a magnetic transfer method in which a master carrier carrying an information signal and a slave medium are brought into close contact with each other to apply a transfer magnetic field to perform magnetic transfer. The recording surface of the slave medium and the information carrying surface of the master carrier are brought into close contact with a liquid therebetween.

It is preferable that the liquid has lubricity. This liquid may be applied to the information carrying surface of the master carrier, but it is preferable to apply a liquid having lubricity to the recording surface of the slave medium. The application of the liquid is desirably performed immediately before the contact from the viewpoint of reducing the adhesion of dust.

After the magnetic transfer, it is preferable to release the close contact with the master carrier while moving the slave medium.
The liquid adhering to the surface of the slave medium after the magnetic transfer is removed, or is used without being removed if it has lubricity.

The close contact distance between the recording surface of the slave medium and the information carrying surface of the master carrier due to the interposition of the liquid is 100 n.
m, particularly preferably 2 to 50 nm. A liquid having such a coating thickness is selected, and a liquid having lubricity and a liquid containing a lubricant and other additives are used as necessary.

Before the slave medium is brought into close contact with the master carrier, a cleaning process for removing minute projections or attached dust on the surface is performed as necessary. On the other hand, before the master carrier is brought into close contact with the slave medium, a cleaning process for removing attached dust is performed as necessary.

There is a case where the master carrier is brought into close contact with one side of the slave medium to perform the one-sided sequential transfer, and a case where the master carrier is brought into close contact with both sides of the slave medium to perform the simultaneous double-sided transfer. The slave medium is preferably a hard disk, and is also applicable to a flexible disk. As the magnetic field generating means for applying the transfer magnetic field, an electromagnet device or a permanent magnet device is adopted, and the transfer magnetic field is applied in the track direction from one or both sides of the contact portion between the master carrier and the slave medium while relatively rotating. I do.

In the magnetic transfer method, a master medium is first provided with initial magnetization in which a slave medium is DC-magnetized in the track direction, and a magnetic layer is formed on the slave medium and a fine uneven pattern corresponding to information to be transferred. And magnetic transfer by applying a transfer magnetic field in a direction substantially opposite to the initial DC magnetization direction of the slave medium surface. The information is preferably a servo signal.

[0013]

According to the present invention as described above, when a master carrier having transfer information is brought into close contact with a slave medium and a transfer magnetic field is applied to perform magnetic transfer, the recording surface of the slave medium is By bringing the carrier and the information carrying surface into close contact with a liquid, the contact distance between the two becomes a constant value corresponding to the thickness of the liquid applied over the entire surface, and magnetic transfer can be performed with uniform characteristics and the transfer signal quality can be improved. As a result, the intensity distribution of the reproduction output becomes good, and the tracking function in the case of the servo signal is sufficiently obtained, so that the reliability can be improved.

Further, a meniscus force due to the liquid interposed on the contact surface acts, the contact force between the slave medium and the master carrier is improved, and good adhesion can be secured without excessively increasing the pressing force.

If the liquid has lubricity, lubrication is imparted to the recording surface of the slave medium, so that a lubricant application step in the manufacturing process of the slave medium becomes unnecessary and the process can be simplified.

On the other hand, as described above, the adhesion force is increased due to the interposition of the liquid. However, after the magnetic transfer, if the adhesion between the master medium and the slave medium is released while moving the slave medium, the slave medium and the master medium are separated with a small force. Can be
The workability is improved, the slave medium is prevented from being damaged, and the life of the master carrier is extended.

[0017]

Embodiments of the present invention will be described below in detail. FIG. 1 is a diagram showing a transfer state of a magnetic transfer method according to one embodiment of the present invention. FIG. 2 is a diagram showing a basic process of magnetic transfer. Each drawing is a schematic diagram, and the thickness and the like are shown in proportions different from actual dimensions.

In FIG. 1, at the time of magnetic transfer, the magnetic recording surface of the slave medium 2 is brought into close contact with the information carrying surface of the master carrier 3 via a liquid layer 4 having a uniform thickness of 100 nm or less, and a predetermined pressure is applied. Press with. In a state where the master carrier 3 and the slave medium 2 are in close contact with each other, a magnetic field for transfer is applied by the magnetic field generating means 5 to magnetically transfer and record information such as servo signals.

The liquid layer 4 is preferably formed by dip coating a predetermined amount of liquid on the information carrying surface of the master carrier 3 or the recording surface of the slave medium 2 immediately before the slave medium 2 and the master carrier 3 are brought into close contact with each other. After applying evenly by spin coating, bar coating, etc., the two are brought into close contact and pressed with a predetermined pressure to make the liquid a uniform thickness over the entire surface. In the close contact state, a meniscus force is exerted by the liquid interposed in the close contact surface, the close contact force between the slave medium 2 and the master carrier 3 is increased, and good close contact is achieved without excessive pressing force.

The thickness of the liquid layer 4, that is, the close contact distance between the recording surface of the slave medium 2 and the information carrying surface of the master carrier 3 is 100 nm or less, preferably 2 to 50 nm.
A liquid having a viscosity characteristic having such a thickness is selected. In particular, a liquid having lubricity is preferable, and a liquid containing a lubricant and other additives in a solvent may be used.
For example, examples of the liquid having lubricating properties include silicone oil and an organic solvent containing stearic acid.

The slave medium 2 is preferably a hard disk having a magnetic recording layer formed on both sides. Before the slave medium 2 is brought into close contact with the master carrier 3, a cleaning process for removing minute projections or attached dust on the surface with a glide head, a polishing body or the like is performed. Applied as needed. The present invention is applicable to magnetic transfer to a flexible disk.

The master carrier 3 is formed in a disk shape,
One surface thereof has a transfer information carrying surface formed by a fine uneven pattern (to be described later with reference to FIG. 2). There is a case where the master carrier 3 is brought into close contact with one surface of the slave medium 2 to perform one-side sequential transfer, and a case where the master carrier 3 is brought into close contact with both surfaces of the slave medium 2 to perform simultaneous double-side transfer. Before the master carrier 3 is brought into close contact with the slave medium 2, a cleaning process for removing attached dust is performed as necessary.

The magnetic field generating means 5 for applying a transfer magnetic field includes:
A coil (not shown) is mounted on a core 52 having a gap 51 extending in the radial direction of the master carrier 3 held by the close contact means.
An electromagnet device that generates magnetic lines of force parallel to the track direction (tangential direction of the circumferential track) and a permanent magnet device that generates similar lines of magnetic force are disposed on one or both sides. At the time of applying a magnetic field, the magnetic field generating unit 5 rotates the slave medium 2 and the master carrier 3 integrally.
By applying a transfer magnetic field, the transfer information of the master carrier 3 is magnetically transferred and recorded on the recording surface of the slave medium 2.
The magnetic field generating means 5 may be provided so as to rotate.

After the magnetic transfer is completed, the slave medium 2 and the master carrier 3 are adhered to each other with a large adhesive force due to the interposition of the liquid layer 4.
The slave medium 2 or the master carrier 3 may be damaged. For this reason, after the magnetic transfer, the slave medium 2 is separated so as to be peeled off from the master carrier 3 while being moved so as to rotate or linearly shift in parallel with the master carrier 3, thereby releasing the close contact between the two. Thereby, the slave medium 2 and the master carrier 3 can be separated with a light force, so that the workability is improved, the slave medium 2 is prevented from being damaged, and the life of the master carrier 3 is extended.

The liquid adhering to the recording surface of the slave medium 2 after the magnetic transfer is removed, or the liquid having lubricity is used without being removed. If the liquid has lubricity, the recording surface of the slave medium 2 is provided with lubricity, so that a lubricant application step in the manufacturing process of the slave medium 2 becomes unnecessary and the process is simplified.

According to the above-described embodiment, the liquid layer 4 interposed between the slave medium 3 and the master carrier 3 includes the dust adhered to the slave medium 2 or the master carrier 3. Dust having a size equal to or less than the thickness of 4 exists in this layer 4 and does not affect the adhesion distance, and a uniform adhesion distance can be obtained over the entire surface. When dust having a size exceeding the thickness of the liquid layer 4 is present, the contact distance increases at that portion, but the other portions have the thickness of the layer 4 and are smaller than the contact distance when no liquid is interposed. The variation in the contact distance over the entire surface is reduced, the difference in transfer characteristics during transfer is small, and the difference in the reproduction output of the transfer signal is small.

FIG. 2 is a diagram showing a basic mode of magnetic transfer. (a) shows a case where a magnetic field is applied in one direction and the slave medium 2 is applied.
Is a step of applying a magnetic field in the opposite direction by bringing the master carrier 3 and the slave medium 2 into close contact with each other, and (c) is a view showing a state after magnetic transfer.
The illustration of the liquid layer 4 is omitted.

First, as shown in FIG. 2A, an initial magnetic field Hin is applied to the slave medium 2 in one direction in the track direction to perform initial magnetization (DC demagnetization) in advance. Thereafter, as shown in FIG. 2 (b), the magnetic recording surface of the slave medium 2 is brought into close contact with the information carrying surface of the master carrier 3 in which the magnetic layer 32 is coated on the fine uneven pattern of the substrate 31. The magnetic transfer is performed by applying a transfer magnetic field Hdu in the track direction 2 in a direction opposite to the initial magnetic field Hin. As a result, FIG.
As shown in (1), information according to the pattern of the formation of the contact projections and recesses of the magnetic layer 32 on the information carrying surface of the master carrier 3 is magnetically transferred and recorded on the magnetic recording surface (track) of the slave medium 2. You.

Note that, even when the concave / convex pattern of the substrate 31 of the master carrier 3 is a negative pattern having a concave / convex shape reverse to the positive pattern of FIG. 2, the direction of the initial magnetic field Hin and the direction of the transfer magnetic field Hdu are set to the above-mentioned values. By reversing the direction, similar information can be magnetically transferred and recorded.

When the substrate 31 is made of a ferromagnetic material such as Ni, magnetic transfer can be performed only with the substrate 31 and the magnetic layer 32 (soft magnetic layer) need not be covered. By providing the layer 32, better magnetic transfer can be performed. When the substrate 31 is a non-magnetic material, it is necessary to provide the magnetic layer 32.

When the magnetic layer 32 is coated on the substrate 31 made of a ferromagnetic metal, the influence of the magnetism of the substrate 31 is cut off.
It is preferable to provide a non-magnetic layer between the substrate 31 and the magnetic layer 32. Further, the uppermost layer is coated with a protective film such as diamond-like carbon (DLC), and this protective film improves contact durability and enables magnetic transfer many times. DLC
An Si film may be formed below the protective film by sputtering or the like.

The master carrier 3 will be described. As the substrate 31 of the master carrier 3, nickel, silicon, quartz plate, glass, aluminum, alloy, ceramics, synthetic resin, or the like is used. The formation of the concavo-convex pattern is performed by a stamper method, a photofabrication method, or the like.

In the stamper method, a photoresist is formed on a glass plate (or quartz plate) having a smooth surface by spin coating or the like, and a laser beam (or a laser beam) modulated according to a servo signal while rotating the glass plate is formed. An electron beam (electron beam) is applied to expose a predetermined pattern on the entire surface of the photoresist, for example, a pattern corresponding to a servo signal extending linearly in the radial direction from the center of rotation to each track on a portion corresponding to each frame on the circumference. Thereafter, the photoresist is developed and the exposed portions are removed to obtain a master having an uneven shape due to the photoresist. Next, based on the concave / convex pattern on the surface of the master, plating (electroforming) is performed on the surface to form a Ni substrate having a positive concave / convex pattern, and the Ni substrate is separated from the master. This substrate is used as a master carrier as it is, or a non-magnetic layer, a soft magnetic layer, and a protective film are coated on the concavo-convex pattern as needed to obtain a master carrier.

A second master is prepared by plating the master, and plating is performed using the second master.
A substrate having a negative concavo-convex pattern may be produced. Further, a second master may be plated or pressed with a resin solution and cured to form a third master, and the third master may be plated to form a substrate having a positive concavo-convex pattern. .

On the other hand, after forming a pattern using a photoresist on the glass plate, etching is performed to form a hole in the glass plate, and a master from which the photoresist has been removed is obtained. Thereafter, a substrate is formed in the same manner as described above. You may.

As the material of the substrate made of metal, Ni or a Ni alloy can be used. The plating for forming this substrate can be any of various metal films including electroless plating, electroforming, sputtering, and ion plating. Law is applicable. Depth of uneven pattern on substrate (height of protrusion)
Is preferably in the range of 80 nm to 800 nm, more preferably 150 nm to 600 nm. This concavo-convex pattern is formed long in the radial direction in the case of a servo signal.
For example, the length in the radial direction is preferably from 0.3 to 20 μm, and the length in the circumferential direction is preferably from 0.2 to 5 μm. It is preferable to select a pattern that is longer in the radial direction in this range as a pattern carrying servo signal information. .

The magnetic layer 32 (soft magnetic layer) is formed by depositing a magnetic material by vacuum deposition such as vacuum deposition, sputtering, or ion plating, or by plating. As the magnetic material of the magnetic layer, Co, a Co alloy (C
oNi, CoNiZr, CoNbTaZr, etc.), Fe,
Fe alloys (FeCo, FeCoNi, FeNiMo, F
eAlSi, FeAl, FeTaN), Ni, and Ni alloy (NiFe) can be used. Particularly preferably, F
eCo and FeCoNi. The thickness of the magnetic layer is 50n
m to 500 nm, more preferably 1 to 500 nm.
It is 50 nm to 400 nm. The material of the nonmagnetic layer provided as an underlayer below the magnetic layer may be Cr, CrT
i, CoCr, CrTa, CrMo, NiAl, Ru,
C, Ti, Al, Mo, W, Ta, Nb and the like are used. This nonmagnetic layer can suppress deterioration of signal quality when the substrate is a ferromagnetic material.

Preferably, a protective film such as DLC is provided on the magnetic layer, and a lubricant layer may be provided. More preferably, a DLC film of 5 to 30 nm and a lubricant layer are present as a protective film. Further, an adhesion strengthening layer such as Si may be provided between the magnetic layer and the protective film. The lubricant is used to compensate for the displacement that occurs during the contact process with the slave medium.
Improves durability deterioration such as generation of scratches due to friction.

A resin substrate may be prepared using the master and a magnetic layer may be provided on the surface of the substrate to form a master carrier. As a resin material for the resin substrate, an acrylic resin such as polycarbonate / polymethyl methacrylate, a vinyl chloride resin such as polyvinyl chloride / vinyl chloride copolymer, an epoxy resin, an amorphous polyolefin, and a polyester can be used. Polycarbonate is preferred in terms of moisture resistance, dimensional stability, cost, and the like. If there are burrs on the molded product, they are removed by varnish or polish. Alternatively, the master may be formed by spin coating or bar coating using an ultraviolet curable resin, an electron beam curable resin, or the like. The height of the pattern protrusion of the resin substrate is 50 to
The range of 1000 nm is preferred, more preferably 20 nm.
The range is from 0 to 500 nm.

A magnetic layer is coated on the fine pattern on the surface of the resin substrate to obtain a master carrier. The formation of the magnetic layer
The magnetic material is formed by a vacuum film forming method such as a vacuum evaporation method, a sputtering method, or an ion plating method, or a plating method.

On the other hand, in the photofabrication method, for example, a photoresist is applied to a smooth surface of a flat substrate, and exposure and development using a photomask corresponding to the pattern of the servo signal are performed. Form a pattern. Next, in the etching step, the substrate is etched according to the pattern, and a hole having a depth corresponding to the thickness of the magnetic layer is formed. Next, a vacuum deposition method of a magnetic material,
A magnetic material is formed to a thickness corresponding to the formed holes by a vacuum film forming means such as a sputtering method or an ion plating method or a plating method to the surface of the substrate. Next, the photoresist is removed by a lift-off method, and the surface is polished to remove any burrs and to smooth the surface.

The slave medium 2 will be described. As a slave medium, a coating type magnetic recording medium or a metal thin film type magnetic recording medium is used. Commercially available media such as high-density flexible disks are examples of the coating type magnetic recording media. Regarding the metal thin-film type magnetic recording medium, first, Co, a Co alloy (CoPtCr, CoCr, C
oPtCrTa, CoPtCrNbTa, CoCrB,
CoNi, etc.), Fe, Fe alloys (FeCo, FePt,
FeCoNi) can be used. It is preferable that the magnetic flux density is large and that the magnetic recording medium has magnetic anisotropy in the same direction as the slave medium (in-plane direction for in-plane recording, perpendicular direction for perpendicular) because clear transfer can be performed. It is preferable to provide a non-magnetic underlayer under the magnetic material (on the side of the support) to provide the necessary magnetic anisotropy. It is necessary to match the crystal structure and lattice constant to the magnetic layer. For that purpose, Cr, CrTi, CoCr, CrTa, CrM
o, NiAl, Ru or the like is used.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part in a magnetic transfer method according to one embodiment of the present invention.

FIG. 2 is a diagram showing basic steps of a magnetic transfer method according to an embodiment of the present invention.

[Explanation of symbols]

 2 slave medium 3 master carrier 4 liquid layer 5 magnetic field generating means

Claims (4)

[Claims] 1. A magnetic transfer method in which a master carrier carrying an information signal and a slave medium are brought into close contact with each other and a transfer magnetic field is applied to perform magnetic transfer, wherein a recording surface of the slave medium and an information carrying surface of the master carrier are provided. A magnetic transfer method in which a liquid is interposed between the magnetic transfer layers. 2. The magnetic transfer method according to claim 1, wherein the liquid has lubricity. 3. A recording medium according to claim 1, wherein a liquid having lubricity is applied to a recording surface of said slave medium.
3. The magnetic transfer method according to item 1. 4. The magnetic transfer method according to claim 1, wherein after the magnetic transfer, the close contact with the master carrier is released while moving the slave medium.