JP2007213807A - Magnetic transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transfer a high-quality transfer pattern from a master carrier to a slave medium by magnetic transfer irrespective of the position of a magnetic pattern by the magnetic transfer. <P>SOLUTION: In the magnetic transfer method for applying a transfer magnetic field by bringing the master carrier for magnetic transfer on which a magnetic layer is formed on a part corresponding to information signal on the surface of a substrate into contact with a magnetic recording medium as a slave medium subjected to transfer, the relationship between coercive force H<SB>cs</SB>of the slave magnetic recording medium and the transfer magnetic field is 0.6×H<SB>cs</SB>≤ transfer magnetic field≤1.7×H<SB>cs</SB>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic transfer master carrier used for transferring recorded information to a magnetic recording medium for a large capacity, high recording density magnetic recording / reproducing apparatus, and more particularly to a servo for a large capacity, high recording density magnetic recording medium. The present invention relates to a magnetic transfer master carrier and a transfer method used for recording signals, address signals, other normal video signals, audio signals, data signals, and the like.

With the progress of the use of digital images, the amount of information handled by personal computers is increasing dramatically. As the amount of information increases, there is a need for a magnetic recording medium that records information and has a large capacity, is inexpensive, and has a short recording and reading time.
In high-density recording media such as hard disks and large-capacity removable magnetic recording media such as ZIP (Iomega Corporation), the information recording area is composed of narrow tracks compared to flexible disks, so that narrow track widths can be accurately set. In order to scan a magnetic head and perform signal recording and reproduction at a high S / N ratio, it is necessary to perform accurate scanning using a tracking servo technique.

Therefore, in a large-capacity magnetic recording medium such as a hard disk or a removable magnetic recording medium, a tracking servo signal, an address information signal, a reproduction clock signal, etc. are recorded at a fixed angular interval for one rotation of the disk. The magnetic head reproduces these signals at regular intervals, thereby accurately scanning the track while confirming and correcting the position of the head. These signals are recorded on the magnetic recording medium in advance as a preformat when the magnetic recording medium is manufactured.
Accurate positioning accuracy is required for recording tracking servo signals, address information signals, and reproduction clock signals, etc., and after the magnetic recording medium is installed in the drive, the position is strictly controlled using a dedicated servo recording device. Preformat recording is performed by a magnetic head.

  However, in preformat recording of servo signals, address information signals, and reproduction clock signals by a magnetic head, recording is performed while strictly controlling the position of the magnetic head using a dedicated servo recording device. Takes time. In addition, as the magnetic recording density increases, the amount of signals to be preformatted increases, and more time is required.

Further, due to the spacing between the head and the magnetic recording medium and the expansion of the recording magnetic field due to the shape of the recording head, the magnetization transition at the track end portion where the preformat recording is performed lacks steepness.
Further, at the time of transfer from the magnetic transfer master carrier, the coercive force (Hc) of the recording medium to be transferred is prevented so that the magnetization of the magnetic transfer master carrier is not demagnetized even when excited by an external magnetic field. It is necessary to use one having a coercive force that is three or more times larger than that.
When a planar magnetic material is partially magnetized, the coercive force of the magnetic material used in the recording medium for high density recording is about 159 kA / m (2000 Oe). The coercive force of the carrier was 477 kA / m (6000 Oe) or more, and it was practically impossible to accurately magnetize the magnetic head.

  Therefore, as a recording method for solving such a conventional problem, a magnetic transfer master carrier in which a concavo-convex shape corresponding to an information signal is formed on the surface of a substrate and a ferromagnetic thin film is formed on at least the surface of the concavo-convex shape. Ferromagnetic material that forms the convex surface by contacting the surface with the surface of a sheet-like or disk-like magnetic recording medium on which a ferromagnetic thin film or ferromagnetic powder coating layer is formed, or by applying an AC bias magnetic field or DC magnetic field. There has been proposed a method of recording a magnetization pattern corresponding to an uneven shape on a magnetic recording medium by exciting a material (for example, Patent Document 1).

In this method, a predetermined format is formed on a slave medium by bringing the surface of the convex portion of the master carrier into close contact with a magnetic recording medium to be preformatted, that is, a slave medium, and simultaneously exciting a ferromagnetic material constituting the convex portion. This method is based on transfer, and can be recorded statically without changing the relative position between the master carrier for magnetic transfer and the slave medium, and can be accurately preformatted. ing. In addition, the recording time is extremely short. That is, in the method of recording from the magnetic head described above, normally several minutes to several tens of minutes are required, and the time required for recording becomes longer in proportion to the recording capacity. In this case, the transfer can be completed in 1 second or less regardless of the recording capacity and the recording density.
JP 10-40544 A

However, with such a recording method, when the number of recording sheets is small, high-precision recording is possible. However, when many slave media are preformatted, corner portions of the information recording area of the master carrier for magnetic transfer are used. Or the recording on the slave medium is lost, and it is difficult to record a large number of sheets.
An object of the present invention is to prevent inaccurate servo operation of a slave medium produced by transferring a preformat pattern by applying an external magnetic field with the magnetic transfer master carrier and the slave medium in close contact with each other. Is.

The present invention provides a magnetic transfer in which a magnetic transfer master is applied by contacting a magnetic transfer master carrier having a magnetic layer formed on a portion corresponding to an information signal on the surface of a substrate and a magnetic recording medium as a slave medium that receives the transfer. In the method, the relationship between the coercive force H _cs of the slave magnetic recording medium and the transfer magnetic field is 0.6 × H _cs ≦ transfer magnetic field ≦ 1.7 × H _cs.
This is a magnetic transfer method.
Further, in the above magnetic transfer method, the coercive force H _cs of the magnetic transfer master carrier is 47.7 kA / m (600 Oe) or less, and the coercive force of the slave medium to be transferred is 119 kA / m (1500 Oe) or more. .

By using the magnetic transfer master carrier of the present invention, tracking servo signals, address information signals, and reproduction clocks can be produced in a short time with good productivity on a disk-shaped medium such as a hard disk, a large-capacity removable disk medium, and a large-capacity flexible medium. Preformat recording of signals, etc. can be performed stably with high accuracy many times. Also, in magnetic transfer from a master carrier for magnetic transfer to a slave medium, transfer with a specific strength with respect to H _cs of the slave medium By applying a magnetic field, a slave medium having a high-quality transfer pattern can be obtained regardless of the position and shape of the pattern.

The present invention solves the problem of the recording method for transferring the recording information held on the convex portion of the magnetic transfer master carrier having irregularities to the slave medium.
The present inventors have developed a method for transferring magnetic information held on a convex portion of a magnetic transfer master carrier having irregularities by forming magnetization in a part of a high coercive force ferromagnetic material on a conventional plane. Compared to the method of forming a magnetic transfer master carrier, it is an extremely superior method that has features such as being able to transfer in a short time, but the corners of the information recording area are missing or the recording is missing. It was inevitable to do. This is because magnetic layer components such as lubricant on the surface of the slave medium and dust adhere to the projections, causing a gap between the master recording medium and the slave medium, and recording becomes difficult due to spacing loss. I found out that this is the cause. Further, the present inventors have conceived the present invention by finding that the cause of the problem of scratches on the surface of the slave medium is a problem caused by contact with the corners of the convex portions of the master carrier for magnetic transfer.

The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram for explaining a conventional transfer method from a master carrier for magnetic transfer to a slave medium.
A magnetic transfer master carrier 1 is formed with a ferromagnetic thin film 2, and a convex portion 3 formed by preformatting is formed on the surface of the ferromagnetic thin film. When the convex part 3 of the master carrier is brought into close contact with the surface of the slave medium 5 and the excitation magnetic field 6 is applied, the convex part 3 is magnetized in that direction, and the slave medium 5 has the magnetization of the convex part 3 of the master carrier for magnetic transfer. 4, the recording magnetic field 7 is formed, and the slave medium is preformatted.
However, when the transfer is performed a number of times using the magnetic transfer master carrier by such a method, the following problems occur in the magnetic transfer master carrier as shown in FIG.

FIG. 2 is a diagram for explaining the master carrier for magnetic transfer after many times of transfer.
When the transfer is performed a plurality of times using the magnetic transfer master carrier 1, the corner portion 8 of the convex portion 3 may be damaged due to multiple contact with the information recording medium, or the corner portion 8 of the convex portion 3 may The attached solid material 9 is generated due to the displacement of the components of the information recording medium, the displacement of the convex portion, or the dust in the atmosphere.
As a result, the magnetization at the corner of the convex portion is not accurately transferred, the corner of the transferred magnetization is disturbed, or the distance between the convex portion and the slave medium is increased due to the attached solid matter, and recording on the slave medium is performed. It seems that things will be missing.

Such a problem is that when the magnetic transfer master carrier and the slave medium are brought into close contact with each other, when a slight deviation occurs between the two, the slave medium is formed at the corner of the convex portion of the magnetic transfer master carrier. In order to cut the surface, the lubricant or the magnetic layer formed on the surface of the slave medium is scraped off, or a part of the convex portion of the magnetic transfer master carrier is lost.
In view of this, the present invention addresses the structural problem caused by the formation of magnetized irregularities on the magnetic transfer master carrier by constructing a nonmagnetic material between the convex parts made of a ferromagnetic material. They are configured in substantially the same plane.

FIG. 3 is a diagram for explaining a magnetic transfer master carrier of the present invention and a method for transferring recorded information to a slave medium using the same, and shows a cross section in the recording track direction perpendicular to the surface of the magnetic transfer master carrier. FIG.
The magnetic transfer master carrier 1 is formed with a transfer information recording portion 10 made of a ferromagnetic material corresponding to a preformat, and a nonmagnetic portion 11 exists between the ferromagnetic magnetization portions. The transfer information recording part 10 and the nonmagnetic part 11 of the master carrier for magnetic transfer form substantially the same plane.
In the present invention, substantially the same plane means that, specifically, the unevenness, that is, the difference in thickness between the part with the magnetic layer and the part without the magnetic layer is 30 nm or less, preferably 10 nm or less. Means.

The cross-sectional shape perpendicular to the surface of the magnetic transfer master carrier in the present invention is preferably rectangular. If the shape is rectangular, the boundary with the non-magnetic portion is defined by a surface perpendicular to the surface of the magnetic transfer master carrier. Therefore, the transfer magnetic field formed on the slave medium lacks the corners of the information recording area or records. The preformat can be formed with extremely high accuracy. In the present invention, the rectangle includes a square.
The magnetic transfer master carrier of the present invention is brought into close contact with the slave medium 5 and an excitation magnetic field 6 such as a DC magnetic field is applied to excite the transfer information recording unit 10, thereby precisely pre-formatting the slave medium.

  In the description of FIG. 3, the magnetic transfer method for magnetizing the slave medium in the in-plane direction has been described. However, an excitation magnetic field is applied in the vertical direction of the slave medium in a state where the magnetic transfer master carrier and the slave medium are in close contact with each other. Then, it is possible to magnetize the slave medium in the vertical direction.

  In the master carrier for magnetic transfer of the present invention, since there are no irregularities on the surface, the surface of the slave medium may be scraped even if both of them are slightly displaced at the time of close contact, There is no fear that the transfer information recording part of the master carrier for magnetic transfer will be lost, and there will be no problems such as deterioration of the quality of the preformat even if the transfer is performed many times.

Next, a method for producing a magnetic transfer master carrier of the present invention will be described with reference to the drawings.
FIG. 4 is a diagram for explaining the method of manufacturing the magnetic transfer master carrier of the present invention in the order of steps.
As shown in FIG. 4A, a photoresist 22 is applied to a substrate 21 having a smooth surface. The substrate 21 is a plate-like body having a smooth surface such as a non-magnetic metal or alloy such as silicon, quartz plate, glass, aluminum, ceramics, synthetic resin, etc. What has tolerance can be used.
Further, any photoresist can be selected and used in accordance with a process such as etching.

As shown in FIG. 4B, exposure 24 is performed using a photomask 23 corresponding to a preformat pattern.
Next, as shown in FIG. 4C, development is performed to form a pattern 25 corresponding to preformat information on the photoresist 22.
Next, as shown in FIG. 4D, in the etching process, a predetermined depth is formed on the substrate according to the pattern by etching means corresponding to the substrate such as reactive etching, physical etching, etching using an etching liquid, and the like. Hole 26 is formed.
The depth of the hole is a depth corresponding to the thickness of the magnetic layer formed as the transfer information recording portion, but is preferably 20 nm or more and 1000 nm or less. If it is too thick, the spread width of the magnetic field becomes large, which is not desirable.
The hole to be formed is preferably a hole having a uniform depth such that the bottom surface is formed in a plane parallel to the surface of the substrate.
Moreover, it is preferable that the hole has a rectangular cross section in the track direction perpendicular to the surface.

Next, as shown in FIG. 4 (E), the magnetic material is magnetized up to the surface of the substrate with a thickness corresponding to a hole formed by vacuum deposition means such as vacuum deposition, sputtering, ion plating, or plating. A material 27 is formed. As for the magnetic characteristics of the transfer information recording portion, the coercive force (Hc) is 199 kA / m (2500 Oe) or less, preferably 0.40 to 119 kA / m (5 to 1500 Oe), and the saturation magnetic flux density (Bs) is 0. .3T (Tesla) or more, preferably 0.5T or more.
Next, as shown in FIG. 4F, the photoresist is removed by a lift-off method, and the surface is polished to remove any flash and the surface is flattened.
In the above description, the method for forming a hole in the substrate and forming the magnetic material in the formed hole has been described. However, the magnetic material is formed at a predetermined position on the substrate, and the convex portion of the transfer information recording unit. After forming the film, a nonmagnetic material may be formed or filled between the convex portions, and the surfaces of the transfer information recording portion and the nonmagnetic material portion may be flush with each other.

In the present invention, examples of the magnetic material that can be used for the transfer information recording portion include iron, chromium, cobalt, and alloys thereof having a high magnetic flux density. Specific examples include CoPtCr, CoCr, CoPtCrTa, CoPtCrNbTa, CoCrB, CoNi, Fe, FeCo, FePt, FeNi, FeNiMo, CoNb, CoNbZr, FeSiAl, and FeTaN.
Of these, FeCo (70:30), FeNi, FeNiMo (75: 20: 5), CoNb, CoNbZr, FeSiAl, and FeTaN are particularly preferable.
In particular, the magnetic flux density is large, and clear transfer is performed with the magnetic anisotropy in the same direction as the slave medium, for example, in-plane direction in the case of in-plane recording and perpendicular direction in the case of perpendicular recording. It is preferable for this purpose. It is preferable that the magnetic material has fine magnetic particles or an amorphous structure because a sharp edge can be formed.

  In order to form magnetic anisotropy in the magnetic material, it is preferable to provide a nonmagnetic underlayer, and the crystal structure and the lattice constant must be the same as those of the magnetic layer. Specifically, as such an underlayer, Cr, CrTi, CoCr, CrTa, CrMo, NiAl, Ru, or the like can be formed by sputtering.

The master carrier and slave medium for magnetic transfer of the present invention have sufficient hardness by forming a dyanmond-like carbon protective film in the transfer information recording portion so that the transfer information recording portion 10 is not damaged. Preferably, it has a hardness of 10 GPa or more. More preferably, it is 20 GPa. If it is less than 10 GPa, the durability is unfavorable.
The protective film formed on the surface of the magnetic layer of the master carrier for magnetic transfer is a diamond-like carbon protective film made of alkane such as methane, ethane, propane or butane, alkene such as ethylene or propylene, or acetylene. It may be formed by plasma CVD using a carbon-containing compound such as alkyne as a raw material. At this time, it is desirable to apply a negative voltage of 50 to 400 V to the substrate.
The carbon protective film preferably has a thickness of 3 to 30 nm, and more preferably 5 to 10 nm.

Further, it is preferable that a lubricant is present on the carbon protective film. As the lubricant, an organic fluorine compound containing a perfluoroalkyl group or the like is preferably used as the lubricant. The thickness of the lubricant is preferably 1 to 10 nm.
In particular, when a lubricant is provided, it is possible to prevent a decrease in durability due to friction that occurs when the magnetic transfer master carrier and the slave medium come into close contact with each other.

In addition, by preventing dust from adhering to the surface of the magnetic transfer master carrier and damaging the surfaces of the magnetic transfer master carrier and the magnetic recording medium to be transferred, or creating a space between them, It has been found that transcription can be performed accurately.
When a magnetic transfer master carrier having a ferromagnetic layer only on a convex portion is used, a magnetic pattern without disturbance can be transferred onto a slave medium. However, it was found that when the transfer was repeated many times, the transfer pattern had a defect that caused a chip.

Such problems often occur because dust is collected from the surroundings due to charging due to repeated contact between the magnetic transfer master carrier and the slave medium.
That is, since the magnetic transfer master carrier is manufactured using a photolithography technique, the substrate of the magnetic transfer master carrier is etched, vacuumed, such as glass, quartz, or silicon. Materials suitable for film formation below are used.

These substances have low conductivity, and the slave medium is generally formed on a synthetic resin substrate, so that the conductivity is low. For this reason, if the magnetic transfer master carrier is contacted to the slave medium many times, the magnetic transfer master carrier will be charged, and dust from the atmosphere will be caused by static electricity on the convex part of the magnetic transfer master carrier. Or a loss of spacing between the magnetic transfer master carrier and the slave medium, or a defect on the convex portion due to dust adhering to the magnetic transfer master carrier and the slave medium, or The slave medium is damaged.
As a result, the magnetization at the corner of the convex portion is not accurately transferred, the corner portion of the transferred magnetization is disturbed, or the distance between the convex portion and the slave medium is increased by the attached solid matter, and the recording on the slave medium is performed. It seems that it will occur.
Therefore, another magnetic transfer master carrier of the present invention is to form a nonmagnetic conductive layer between the substrate and the magnetic layer, such as dust adhesion caused by charging of the magnetic transfer master carrier. Is the solution.

FIG. 5 is a diagram for explaining a magnetic transfer master carrier of the present invention and a method for transferring recorded information to a slave medium using the same, and shows a cross section in the recording track direction perpendicular to the surface of the magnetic transfer master carrier. FIG.
A conductive layer 12 is formed on the magnetic transfer master carrier 1, and a transfer information recording unit 10 made of a ferromagnetic material corresponding to a preformat is formed on the conductive layer.
The magnetic transfer master carrier of the present invention is brought into contact with the slave medium 5, or an excitation magnetic field 6 such as an AC bias magnetic field or a DC magnetic field is applied to excite the transfer information recording unit 10, thereby precisely preformatting the slave medium. Is done.
Further, as described in FIG. 4, it is preferable to form a carbon protective film on the surface of the transfer information recording portion.

  In the description of FIG. 5, the magnetic transfer method for magnetizing the slave medium in the in-plane direction has been described. However, an excitation magnetic field is applied in the vertical direction of the slave medium in a state where the master carrier for magnetic transfer and the slave medium are in contact with each other. Then, it is possible to magnetize the slave medium in the vertical direction.

  In the magnetic transfer master carrier of the present invention, since the nonmagnetic conductive layer exists between the substrate and the magnetic layer, the conductivity of the magnetic transfer master carrier is increased. As a result, even when the slave medium is brought into contact with the magnetic transfer master carrier, a large amount of static electricity is not charged, and dust does not collect in the transfer information recording unit. As a result, no spacing loss occurs and the magnetic transfer master carrier or slave medium is not damaged.

Next, a method for producing a magnetic transfer master carrier of the present invention will be described with reference to the drawings.
FIG. 6 is a diagram for explaining the method of manufacturing the magnetic transfer master carrier of the present invention in the order of steps.
As shown in FIG. 6A, a nonmagnetic conductive layer 32 is formed on a substrate 31 having a smooth surface.
Next, as shown in FIG. 6B, the magnetic layer 33 is formed by forming a magnetic material on the nonmagnetic conductive layer by means of sputtering, vacuum deposition, plating, or the like.
Further, as shown in FIG. 6C, a photoresist 34 is applied on the magnetic layer. As the photoresist, either a positive type or a negative type may be used.

Next, as shown in FIG. 6D, the photoresist 34 is exposed 36 using a photomask 35 corresponding to the preformat pattern.
As shown in FIG. 6E, development is performed to form a resist pattern 37 corresponding to preformat information on the photoresist 34.
Next, as shown in FIG. 6F, the magnetic material is etched according to the resist pattern.

Next, as shown in FIG. 6G, the photoresist is removed to form a transfer magnetic layer 38.
Further, as shown in FIG. 6H, after a protective film 39 for protecting the magnetic layer surface is formed on the magnetic layer for transfer, it is magnetized by applying a uniform magnetic field.
In FIG. 6, the method of manufacturing by removing unnecessary magnetic material from a magnetic layer formed in advance by etching has been described. However, after forming a photoresist pattern on the nonmagnetic conductive layer, the magnetic layer is sputtered or the like. The magnetic layer may be formed in a portion which is formed by the film forming means and is not covered with the photoresist.

  The substrate 31 of the transfer master carrier is a plate-like body having a smooth surface such as a non-magnetic metal or alloy such as silicon, quartz plate, glass or aluminum, ceramics, synthetic resin, etc. Those having resistance to the processing environment such as the above can be used.

Further, as the nonmagnetic conductive layer 32, a nonmagnetic metal layer is preferable, and a layer made of Cr, Ti, Ta, Nb or the like can be exemplified. Further, an alloy made nonmagnetic by forming an alloy with a magnetic metal such as Co, Fe, Ni, etc., a layer made of conductive particles such as carbon black and nonmagnetic metal, and a binder can be used. Of these, Co and Co-based alloys are preferable.
As the nonmagnetic conductive layer, it is preferable to form a layer having a resistivity of 10 ⁷ Ω · cm or less and a conductivity of 10 ⁵ Ω · cm or less, which is more conductive than 10 ⁷ Ω · cm. When the property is small, the antistatic effect cannot be sufficiently obtained. The thickness of the nonmagnetic conductive layer is 10 nm or more, preferably 30 nm or more.

  In the present invention, as the magnetic material that can be used for the magnetic layer, the material used for the transfer information recording portion shown in the description of FIG. 4 can be used. The thickness of the magnetic layer is 20 to 1000 nm, preferably 30 to 500 nm. If it is too thick, the recording resolution decreases.

  In addition, in the method of transferring the magnetic information on the convex portion of the magnetic transfer master carrier having irregularities, it was inevitable that the corners of the information recording area or the lack of recording was unavoidable. There are problems in the surface hardness, flexibility, etc. of the master carrier and slave medium, and it is possible to make significant improvements by improving them.

FIG. 7 is a diagram for explaining a conventional transfer method from a master carrier for magnetic transfer to a slave medium.
The magnetic transfer master carrier 1 is formed with a ferromagnetic thin film 2, and a convex portion 3 formed in accordance with the preformat is formed on the surface of the ferromagnetic thin film. When the convex portion 3 of the master carrier for magnetic transfer is brought into contact with the surface of the slave medium 5 and an excitation magnetic field 6 is applied, a recording magnetic field 7 corresponding to the convex portion 3 of the master carrier is formed on the slave medium 5, thereby forming the slave medium. Is preformatted.
However, if a large number of times of transfer are performed using a magnetic transfer master carrier by such a method, the transferred magnetic recording information may be disturbed in edges or the recording may be lost, making it difficult to transfer a large number of sheets. there were.

  The major cause is that the surface hardness of the magnetic transfer master carrier is insufficient. A magnetic transfer master carrier that does not have sufficient hardness, as the number of times of transfer increases, a part of the transfer pattern of the magnetic transfer master carrier, particularly the edge part, is lost, and the shape of the transfer pattern is lost or disordered. Arise. In addition, fine powder generated from the chipped portion enters between the magnetic transfer master carrier and the slave medium, and a space is created between the two, so that the magnetic field from the magnetic transfer master carrier that is not chipped also spreads. The image becomes unclear.

In the magnetic transfer master carrier 1 shown in FIG. 7, the magnetic layer of the convex portion 3 that is in close contact with the slave medium 5 is formed integrally with the concave portion. Since the distance to the slave medium 5 is relatively short between the concave portion 13 and the convex portion 3, it is inevitable that the leakage magnetic force 14 of the concave portion 13 affects the slave medium, and the transferred magnetic recording information is disturbed. Or, it tends to occur that the recording is missing.
Therefore, in the magnetic transfer master carrier of the present invention, the magnetic layer exists only in the portion to be transferred, does not exist in the other portions where the transfer is not performed, and the magnetic layer having a uniform thickness on the substrate surface. It is preferred that no layer is formed.

FIG. 8 is a diagram for explaining a magnetic transfer master carrier of the present invention and a method for transferring recorded information to a slave medium using the same, and shows a cross section in the recording track direction perpendicular to the surface of the magnetic transfer master carrier. FIG.
The magnetic transfer master carrier 1 is formed with a non-magnetic substrate and a convex transfer information recording portion 10 corresponding to the preformat. A diamond-like carbon protective film 12 is formed on the transfer information recording unit 10, and a lubricant layer 15 is formed on the diamond-like carbon protective film.
The magnetic transfer master carrier of the present invention is closely attached to the slave medium 5 or an excitation magnetic field 6 such as a DC magnetic field is applied to excite the transfer information recording unit 10, so that the slave medium is precisely preformatted.

In the description of FIG. 8, the magnetic transfer method for magnetizing the slave medium in the in-plane direction has been described. However, an excitation magnetic field is applied in the vertical direction of the slave medium in a state where the master carrier for magnetic transfer and the slave medium are in contact with each other. Then, it is possible to magnetize the slave medium in the vertical direction.
Further, the slave medium in contact with the magnetic transfer master carrier preferably has a surface hardness of 1 GPa or more, more preferably 2 GPa or more, and a diamond-like carbon protective film is formed in the same manner as the magnetic transfer master carrier. Those are preferred.
The slave medium has a high surface hardness so as not to cause scratches due to the close contact of the magnetic transfer master carrier, and has flexibility so as to be sufficiently in close contact with the magnetic transfer master carrier. It is preferable.

  In the slave medium that can be used in the present invention, a synthetic resin film is preferably used as a substrate, and specific examples thereof include polyethylene terephthalate, polyethylene naphthalate, aramid, polyimide, polyphenylene benzbisoxazal, and the like.

In the case where the magnetic layer formed on the slave medium is composed of a ferromagnetic metal thin film, a magnetic recording medium having a high recording density can be obtained, but a composition in which a ferromagnetic metal powder is dispersed in a binder is preferable. You may have a magnetic layer formed by apply | coating. In that case, the thing of predetermined | prescribed hardness can be obtained by adjusting the kind or quantity of the abrasive | polishing agent mixed in the composition used for formation of a magnetic layer.
When the slave medium is a ferromagnetic metal thin film, it is preferable to form a dyanmond-like carbon protective film on the surface of the magnetic layer and further form a lubricant layer.

Next, the surface hardness of the present invention will be described. The surface hardness of the present invention is expressed in microhardness.
In a measurement method in which pressure is applied to the magnetic transfer master carrier with a large load as in the usual Vickers and Knoop hardness measurement, a preferable hardness range could not be found.
Hardness is measured by a method that detects force and displacement with high sensitivity, using a change in capacitance that accompanies electrode movement, where a pick-up electrode with an indenter is placed between the two electrode plates. it can.
The measurement was performed using a triangular pyramid shape with a diamond tip ridge angle of 90 degrees and a tip curvature radius of 35 to 50 nm, pushing at a pushing load of 5 μN at a pushing speed of 2 to 4 nm / sec, applying a pressure of up to 5 μN, and then gradually returning the pressure. . The value obtained by dividing the maximum load 5 μN at this time by the projected area of the indenter contact portion is taken as the hardness.
The projected area is obtained by an indentation test. One-third of the unloading curve of the depth-weighted curve is linearly approximated and the point intersecting the depth axis is defined as the contact depth of the indenter contact portion. As a function of

A master carrier and transfer method suitable for transfer could not be found with the hardness measured up to the inside of the medium (100 nm or more) by applying a large load as in ordinary Vickers and Knoop hardness measurements.
Specifically, measurement is possible using TRIBOSCOPE (HYSITRON) or the like.

Next, a method for producing a magnetic transfer master carrier of the present invention will be described with reference to the drawings.
FIG. 9 is a diagram for explaining the method of manufacturing the magnetic transfer master carrier of the present invention in the order of steps.
As shown in FIG. 9A, a nonmagnetic conductive layer 32 is formed on a substrate 31 having a smooth surface.
Next, as shown in FIG. 9B, the magnetic layer 33 is formed by forming a magnetic material on the nonmagnetic conductive layer by means of sputtering, vacuum evaporation, plating, or the like.
Further, as shown in FIG. 9C, a photoresist 34 is applied on the magnetic layer. As the photoresist, either a positive type or a negative type may be used.

Next, as shown in FIG. 9D, the photoresist 34 is exposed 36 using a photomask 35 corresponding to the preformat pattern.
As shown in FIG. 9E, development is performed to form a resist pattern 37 corresponding to preformat information on the photoresist 34.
Next, as shown in FIG. 9F, the magnetic material is etched according to the resist pattern.
Next, as shown in FIG. 9G, the photoresist is removed to form a transfer magnetic layer 38.
Furthermore, as shown in FIG. 9H, a uniform magnetic field is applied to the transfer magnetic layer after forming the diamond-like carbon protective film 39 on the surface of the magnetic layer and then providing the lubricant layer 40. Magnetize.

  In FIG. 9, the method of manufacturing by removing unnecessary magnetic material from a magnetic layer formed in advance by etching has been described. However, after forming a photoresist pattern on the nonmagnetic conductive layer, the magnetic layer is sputtered or the like. The magnetic layer may be formed in a portion that is formed by the film forming means and is not covered with the photoresist.

  In addition, when a magnetic field for transfer is applied from the outside by using the magnetic transfer master carrier described in the above description and the magnetic field for transfer is applied from the outside, a portion where the transfer is unstable and the signal quality is reduced occurs. In addition to the influence of the shape of the magnetic layer of the transfer master carrier and the dust adhering to the projections, it was found that the signal quality deteriorates because the magnetic field applied during transfer is not appropriate. .

In magnetic transfer from a master carrier to a slave carrier, when an external magnetic field higher than the slave's Hc is applied, all the magnetization states of the slave are magnetized in the applied direction, so that the pattern to be originally transferred is not recorded. It was generally considered. For example, Japanese Patent Laid-Open No. 10-40544 also describes that paragraph number 0064 preferably has a coercive force equal to or less than that of the magnetic recording medium.
However, it has been clarified that when the transfer is performed by such a method, the information signal quality may be poor, and the servo operation may be inaccurate.

FIG. 10 illustrates the transfer of the preformat pattern on the magnetic transfer master carrier. FIG. 10A is a plan view schematically illustrating the magnetic layer surface of the magnetic transfer master carrier, and FIG. 10B is a cross-sectional view illustrating the transfer process.
A preformat area 52 and a data area 53 in which patterns of tracking servo signals and address signals to be transferred are formed are formed in a predetermined area of the track of the magnetic transfer master carrier 51. Since the preformat information can be transferred as recording information 57 to the slave medium side by applying a transfer external magnetic field 56 in the track direction 55 with the slave medium 54 and the slave medium 54 in close contact with each other, the slave medium can be manufactured efficiently. Is something that can be done.

However, it has been clarified that when the transfer is performed by such a method, the information signal quality may be poor, and the servo operation may be inaccurate. This is because when the magnetic transfer master carrier is transferred to the slave medium, the portion in contact with the slave medium has a lot of magnetic fields entering the pattern portion of the magnetic transfer master carrier. It is considered that even if a transfer magnetic field higher than H _cs is applied, it does not reverse.
Moreover, the intensity of the magnetic field for transfer has a preferable magnitude, and a slave medium with high signal quality can be obtained by applying a magnetic field for transfer having a specific relationship strength as compared with the coercive force H _cs of the slave carrier. Can do.

In order to realize clear transfer in any transfer pattern, the slave medium is initially set in one direction with a sufficiently large magnetic field in comparison with H _cs of the slave medium, at least H _cs , preferably at least 1.2 times H _cs. The magnetic field for transfer is 0.6 × H _cs ≦ transfer magnetic field ≦ 1.7 × H _cs.
The direction can be realized by applying the direction opposite to the direction of the initial direct current magnetization.
When the transfer magnetic field is smaller than 0.6 times the coercive force H _{cs of the} slave medium, the pattern cannot be transferred. When the magnetic field for transfer is larger than 1.7 times the H _cs , the pattern is It will be magnetized regardless.
The strength of the transfer magnetic field is more preferably 0.9 H _{cs to} 1.4 H _cs , and still more preferably 1.0 H _{cs to} 1.3 H _cs .

The coercivity H _cs of the magnetic transfer master carrier is preferably 47.7 kA / m (600 Oe) or less, and the coercivity of the slave medium to be transferred is preferably 119 kA / m (1500 Oe) or more. If the coercive force H _cs is too large, a large transfer magnetic field is required, and a huge magnetic field generator is required, so 47.7 kA / m (600 Oe) or less is preferable. Further, since the high-density magnetic recording cannot be performed if the coercive force H _cs of the slave medium is small, it is preferably 119 kA / m (1500 Oe) or more.

When transferring the magnetic recording information from the magnetic transfer master carrier to the slave medium, it is preferable that the magnetic transfer master carrier and the slave medium are in close contact, and the close contact is a non-magnetic material such as an aluminum plate with a rubber plate interposed therebetween. It is preferable to apply pressure from above, and it is effective to superimpose the magnetic transfer master carrier and the slave medium and suck the air interposed therebetween under reduced pressure.
In addition, the magnetic transfer master carrier of the present invention is not limited to the transfer of magnetic recording information to a disk type magnetic recording medium such as a hard disk or a large capacity removal type magnetic recording medium, but also a card type magnetic recording medium and a tape type magnetic recording medium. It can be used for transfer of magnetic recording information to.

  Further, in the present invention, the magnetic transfer from the magnetic transfer master carrier to the slave medium has been described by taking the preformat as an example. However, the present invention is not limited to the preformat and can be similarly applied to transfer of arbitrary magnetic recording information. It is possible to accurately transfer a large amount of magnetic recording information in a short time.

  Also, the positional relationship between the magnetic transfer master carrier and the slave medium at the time of transfer may be either above or below, and the close contact method is a method of placing and pressing the slave medium on the fixed magnetic transfer master carrier. Or a method of adhering by suction of air.

Hereinafter, the present invention will be described with reference to examples of the present invention.
Example 1-1
(Preparation of master carrier for magnetic transfer)
Photoresist was applied to the surface of a 6-inch diameter silicon substrate, exposed using a mask, and then developed to form a resist pattern.
Next, holes having a uniform depth were formed in the silicon substrate to a depth of 200 nm by reactive ion etching. Next, a chromium underlayer was formed to a thickness of 30 nm by sputtering, and FeCo was formed to a thickness of 200 nm on the underlayer. Next, after removing the photoresist by lift-off, the surface was polished with a polishing tape to obtain a master carrier for magnetic transfer. The coercive force Hc of the obtained ferromagnetic material was 15.9 kA / m (200 Oe).

(Production of slave media)
In the slave medium, a CrTi alloy is formed as a base layer with a thickness of 60 nm on a polyimide substrate having a thickness of 75 μm, and a CoCrPt thin film is formed as a recording layer with a thickness of 30 nm as a recording layer thereon. A carbon protective film having a thickness of 10 nm was formed by CVD using a mixed gas of methane / argon. A fluorine-based lubricant was applied on the carbon protective film with a thickness of 2 nm. The coercive force Hc of the obtained ferromagnetic material was 199 kA / m (2500 Oe).

(Transcription test method)
The obtained magnetic transfer master carrier was cut into a square of 50 mm × 20 mm, and a magnetic medium of 477 kA / m (6000 Oe) was applied in advance to directly magnetize the slave medium in close contact with the magnetic transfer master carrier. Magnetic recording information was transferred from the magnetic transfer master carrier to the slave medium by applying an excitation magnetic field of 183 kA / m (2300 Oe) in the direction opposite to the magnetization direction of the slave medium.
In the slave medium, a CrTi alloy is formed as a base layer with a thickness of 60 nm on a polyimide substrate having a thickness of 75 μm, and a CoCrPt thin film is formed as a recording layer with a thickness of 30 nm as a recording layer thereon. A carbon protective film having a thickness of 10 nm was formed by CVD using a mixed gas of methane / argon. A fluorine-based lubricant was applied on the carbon protective film with a thickness of 2 nm.
The magnetic transfer master carrier and the slave medium were pressed from above the aluminum plate with a rubber plate interposed therebetween. Even after 10,000 transfers, the master carrier for magnetic transfer was not damaged, and high-quality transfer could be performed.

Comparative Example 1-1
(Preparation of master carrier for magnetic transfer)
Photoresist was applied to the surface of the silicon substrate, and a pattern was formed by exposure using a mask.
Next, a hole having a uniform depth is formed in the silicon substrate to a depth of 200 nm by reactive ion etching, the photoresist is removed, and then a chromium underlayer is formed in a thickness of 30 nm by sputtering. On the ground layer, FeCo was deposited to a thickness of 200 nm to form an uneven magnetic layer. The coercive force Hc of the obtained ferromagnetic material was 180 Oe.

(Transcription test method)
When the transfer test of the obtained magnetic transfer master carrier was performed 10,000 times in the same manner as in Example 1, the corners of the magnetic transfer master carrier were missing as shown in FIG. Something happened.

Example 2-1
(Preparation of master carrier for magnetic transfer)
After forming CrTi on a glass substrate to a thickness of 60 nm by sputtering, a magnetic film having a coercive force (Hc) of 8.0 kA / m (100 Oe) and a composition of Fe: Co = 80: 20 is sputtered to a thickness of 200 nm. Provided.
Next, a photoresist was applied, exposed and developed using a preformat photomask to form a resist pattern.
Next, after etching the magnetic layer with a 50 wt% ferric chloride solution, the photoresist was removed, and a mixed gas of methane and argon in a volume ratio of 1: 1 was vented to 0.267 Pa ( A high-frequency plasma was generated at a vacuum degree of 2 × 10 ⁻³ Toor, and a negative voltage of 200 V was applied to the substrate to form a carbon protective film with a thickness of 5 nm.

(Production of slave media)
A CrTi film having a thickness of 60 nm is formed on a polyimide substrate having a thickness of 75 μm by sputtering, and a CoPtCrtTa film having a coercive force (Hc) of 159 kA / m (2000 Oe) is formed to a thickness of 30 nm by sputtering. Formed. The obtained slave medium was DC magnetized at 477 kA / m (6000 Oe).

(Transcription test method)
The magnetic surface of the master carrier for magnetic transfer is superimposed on the magnetic surface of the obtained slave medium, and a magnetic field in the direction opposite to the magnetization of the slave medium is applied to 151 kA / m (1900 Oe) to make the magnetization of the master carrier for magnetic transfer slave. Transfer to the medium, change the master carrier, observe the state of the magnetic pattern transferred to the slave medium after 10,000 transfers, using a magnetic force microscope (MFM), and damage the surface of the master carrier for magnetic transfer with an optical microscope Was observed. A good transfer pattern was observed on the surface of the slave medium, and when the damage state of the surface of the master carrier was observed, there was almost no defect in the transferred image.

Comparative Example 2-1
(Preparation of master carrier for magnetic transfer)
A magnetic layer was formed in the same manner as in Example 2-1 except that a CoCr film of Hc 16.0 kA / m (200 Oe) was directly formed on a glass substrate by sputtering to a thickness of 200 nm. did.
(Transcription test method)
The obtained magnetic transfer master carrier was subjected to a transfer test and observed in the same manner as in Example 1. As a result, the transfer pattern was missing from the 200th slave medium.

Example 3-1.
(Preparation of master carrier for magnetic transfer)
After forming CrTi with a thickness of 60 nm as a base layer on a glass substrate, a magnetic film having a composition of Fe: Co = 80: 20 with a coercive force (Hc) of 8.0 kA / m (100 Oe) is sputtered to 200 nm. Provided in thickness.
Next, a photoresist was applied, exposed and developed using a preformat photomask to form a resist pattern.
Next, after etching the magnetic layer with a 50 wt% ferric chloride solution, the photoresist was removed, and a mixed gas of methane and argon in a volume ratio of 1: 1 was vented to 0.267 Pa ( A high-frequency plasma was generated at a vacuum degree of 2 × 10 ⁻³ Toor and a negative voltage of 200 V was applied to the substrate to form a carbon protective film with a thickness of 10 nm.

  Using TRIBOSCOPE (HYSITRON), the obtained master carrier for magnetic transfer was pushed in at a pushing speed of 3 nm / second with a pushing load of 5 μN using a triangular pyramid shape with a diamond tip ridge angle of 90 degrees and a tip radius of curvature of up to 5 μN. Then, gradually return the pressure. The maximum load at this time, 5 μN, was divided by the projected area of the indenter contact portion to obtain the hardness, which was 30 GPa.

(Production of slave media)
A CrTi film having a thickness of 60 nm is formed on a polyimide substrate having a thickness of 75 μm by sputtering, and a CoPtCrTa film having a coercive force (Hc) of 159 kA / m (2000 Oe) is formed by sputtering to a thickness of 30 nm. Formed.
Next, a diamond-like carbon protective film was formed by sputtering, and when the surface hardness of the obtained slave medium was measured under the same measurement conditions as the magnetic transfer master carrier, it was 20 GPa. Next, direct current magnetization was performed at 477 kA / m (6000 Oe).

(Transcription test method)
The slave medium and the magnetic transfer master carrier were brought into close contact with each other, and an external magnetization of 151 kA / m (1900 Oe) was applied in a direction opposite to the magnetization of the slave medium. Adhesion between the magnetic transfer master carrier and the slave medium was pressurized from above the aluminum plate with a rubber plate in between. The state of the magnetization pattern transferred to the slave medium after 10000 transfers after changing the master carrier was observed with a magnetic force microscope (MFM), and the surface damage state of the master carrier for magnetic transfer was observed with an optical microscope. A good transfer pattern was observed on the surface of the slave medium, and when the damage state of the surface of the master carrier was observed, almost no chipping was observed.

Comparative Example 3-1
A magnetic transfer master carrier and a slave medium were prepared in the same manner as in Example 3-1, except that the carbon protective film was not formed. When the state was observed, chipping was observed in the magnetic transfer master carrier, and chipping was also observed in the transfer pattern.

Example 4-1
(Production of master carrier)
In a vacuum film forming apparatus, the pressure was reduced to 1.33 × 10 ⁻⁵ Pa (10 ⁻⁷ Torr) at room temperature, and then argon was introduced to obtain 0.40 Pa (3 × 10 ⁻³ Torr). A magnetic film having a composition of Fe: Co = 80: 20 having a thickness of 200 nm was formed on a silicon substrate to obtain a master carrier.
The coercive force H _cs was 8.0 kA / m (100 Oe), and the magnetic flux density Bs was 28.9 T (23000 Gauss).
Etching formed an array pattern of 10 μm lines and spaces of 10 pairs—100 μm spaces—10 μm lines and spaces of 10 pairs.

(Production of slave media)
In a vacuum film forming apparatus, the pressure was reduced to 1.33 × 10 ⁻⁵ kPa (10 ⁻⁷ Torr) at room temperature, and then argon was introduced to obtain 0.40 Pa (3 × 10 ⁻³ Torr). The glass plate was heated to 200 ° C. to form a CrTi film having a thickness of 60 nm. Further, after forming a CoPtCr film having a thickness of 30 nm, a diamond-like carbon (DLC) protective film having a thickness of 10 nm was formed as a slave medium. The saturation magnetic flux density Bs was 0.45 T (4500 Gauss). Next, initial direct current magnetization was applied to the slave medium in advance in a direction opposite to a transfer magnetic field described later at 0.4 T (4000 Gauss).

(Magnetic transfer test method)
The H _cs 199 kA / m (2500 Oe) slave medium (A) and the Zip 100 (Iomega) medium (B) (H _cs : 127 kA / m (1600 Oe)) prepared above and the master carrier are in close contact with each other. The magnetic field for transfer shown in 1 and Table 2 was applied in the direction opposite to the magnetization of the slave medium. The magnetic transfer master carrier and the slave medium were pressed from above the aluminum plate with a rubber plate in between.
The shape of the magnetized pattern of the obtained slave medium was measured by the following magnetic development method.

(Magnetic development method)
The magnetic developer (Sigma Marker Q made by Sigma High Chemical) was diluted 10 times, dropped onto the slave medium, dried, and the length of the developed pattern line in the cross-sectional direction was measured with a microscope. The results are shown in Table 1. And in Table 2. In addition, a measurement is performed about 10 samples and the average value is shown.

Table 1
Slave medium Coercive force Transfer ratio with H _cs Magnetic development
H _cs magnetic field strength Section length
(KA / m) (kA / m) (Relative ratio)
A 199 59.7 0.3 0.0
99.5 0.5 0.0
119 0.6 0.3
159 0.8 0.6
179 0.9 0.8
199 1.0 1.0
219 1.1 1.0
239 1.2 1.0
259 1.3 1.0
279 1.4 0.9
298 1.5 0.6
318 1.6 0.3
398 2.0 0.0

Table 2
Slave medium Coercive force Transfer ratio with H _cs Magnetic development
H _cs magnetic field strength Section length
(KA / m) (kA / m) (Relative ratio)
B 127 39.8 0.3 0.0
55.7 0.4 0.0
79.6 0.6 0.3
95.5 0.8 0.8
111 0.9 0.9
127 1.0 1.0
143 1.1 1.0
159 1.3 1.0
187 1.5 0.9
199 1.6 0.6
219 1.7 0.4
239 1.9 0.1
279 2.2 0.0

By using the magnetic transfer master carrier of the present invention, tracking servo signals, address information signals, and reproduction clocks can be produced in a short time with good productivity on a disk-shaped medium such as a hard disk, a large-capacity removable disk medium, or a large-capacity flexible medium. Preformat recording of signals, etc. can be performed stably with high accuracy and many times. Also, in magnetic transfer from a master carrier for magnetic transfer to a slave medium, transfer with a specific strength to H _cs of the slave medium By applying a magnetic field for use, a slave medium having a high-quality transfer pattern can be obtained regardless of the position and shape of the pattern.

FIG. 1 is a diagram for explaining a conventional transfer method from a master carrier for magnetic transfer to a slave medium. FIG. 2 is a diagram for explaining the master carrier for magnetic transfer after many times of transfer. FIG. 3 is a diagram for explaining a magnetic transfer master carrier of the present invention and a method for transferring recorded information to a slave medium using the same, and shows a cross section in a recording track direction perpendicular to the surface of the magnetic transfer master carrier. FIG. FIG. 4 is a diagram for explaining the method of manufacturing the magnetic transfer master carrier of the present invention in the order of steps. FIG. 5 is a diagram for explaining a magnetic transfer master carrier of the present invention and a method for transferring recorded information to a slave medium using the same, and shows a cross section in the recording track direction perpendicular to the surface of the magnetic transfer master carrier. FIG. FIG. 6 is a diagram for explaining the method of manufacturing the magnetic transfer master carrier of the present invention in the order of steps. FIG. 7 is a diagram for explaining a conventional transfer method from a master carrier for magnetic transfer to a slave medium. FIG. 8 is a diagram for explaining a magnetic transfer master carrier of the present invention and a method for transferring recorded information to a slave medium using the same, and shows a cross section in the recording track direction perpendicular to the surface of the magnetic transfer master carrier. FIG. FIG. 9 is a diagram for explaining the method of manufacturing the magnetic transfer master carrier of the present invention in the order of steps. FIG. 10 is a diagram for explaining the transfer of the pattern for preformatting from the magnetic transfer master carrier.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Master carrier for magnetic transfer, 2 ... Ferromagnetic thin film, 3 ... Convex part, 4 ... Magnetization, 5 ... Slave medium, 6 ... Excitation magnetic field, 7 ... Recording magnetic field, 8 ... Corner | angular part, 9 ... Adhering solid substance, 10 DESCRIPTION OF SYMBOLS ... Transfer information recording part, 11 ... Nonmagnetic part, 12 ... Diamond-like carbon protective film, 13 ... Recessed part, 14 ... Leakage magnetic force, 15 ... Lubricant layer, 21 ... Substrate, 22 ... Photoresist, 23 ... Photomask, 24 ... exposure, 25 ... pattern, 26 ... hole, 27 ... magnetic material,
DESCRIPTION OF SYMBOLS 12 ... Conductive layer, 31 ... Substrate, 32 ... Nonmagnetic conductive layer, 33 ... Magnetic layer, 34 ... Photoresist, 35 ... Photomask, 36 ... Exposure, 37 ... Resist pattern, 38 ... Magnetic layer for transfer, 39 ... Protective film, 40 ... Lubricant layer, 51 ... Master carrier for magnetic transfer, 52 ... Preformat area, 53 ... Data area, 54 ... Slave medium, 55 ... Track direction, 56 ... External magnetic field for transfer, 57 ... Recording information

Claims (2)

In a magnetic transfer method of applying a magnetic field for transfer by contacting a magnetic transfer master carrier having a magnetic layer formed on a portion corresponding to an information signal on the surface of a substrate and a magnetic recording medium as a slave medium to be transferred, the slave The relationship between the coercive force H _cs of the magnetic recording medium and the magnetic field for transfer is
0.6 × H _cs ≦ transfer magnetic field ≦ 1.7 × H _cs
A magnetic transfer method characterized by the above. 2. The coercive force H _cs of the magnetic transfer master carrier is 47.7 kA / m (600 Oe) or less, and the coercive force of the slave medium receiving the transfer is 119 kA / m (1500 Oe) or more. Magnetic transfer method.

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