JP3964452B2 - Master carrier for magnetic transfer - Google Patents

Description

  The present invention relates to a magnetic transfer master carrier having a pattern-shaped convex portion for transferring information to a magnetic recording medium, and more particularly to a magnetic transfer master carrier for transferring information to a perpendicular magnetic recording medium. It is.

  In general, with the increase in the amount of information, a magnetic recording medium is desired that has a large capacity for recording a large amount of information, is inexpensive, and can read out a necessary portion preferably in a short time and can perform so-called high-speed access. It is rare. For example, a high-density magnetic recording medium (magnetic disk medium) used in a hard disk device or a flexible disk device is known, and in order to realize a large capacity, a magnetic head accurately scans a narrow track width, A so-called tracking servo technique for reproducing a signal with a high S / N ratio plays a major role. In order to perform this tracking servo, a servo signal for tracking, an address information signal, a reproduction clock signal, and the like are recorded in a so-called preformat on the disk at certain intervals.

  As a method for accurately and efficiently performing this preformatting, Patent Documents 1 to 3 disclose a magnetic transfer method in which information such as a servo signal carried by a master carrier is magnetically transferred to a magnetic recording medium.

For this magnetic transfer, a master carrier having a concavo-convex pattern (patterned convex portion) corresponding to information to be transferred to a magnetic recording medium (slave medium) such as a magnetic disk medium is prepared, and the master carrier and the slave medium are brought into close contact with each other. In this state, by applying a transfer magnetic field, a magnetic pattern corresponding to information (for example, a servo signal) carried by the concavo-convex pattern of the master carrier is transferred to the slave medium. Recording can be performed statically without changing the actual position, accurate preformat recording is possible, and the time required for recording is extremely short.
JP 63-183623 A Japanese Patent Laid-Open No. 10-40544 Japanese Patent Application Laid-Open No. 10-269566

  By the way, as the magnetic recording medium, an in-plane magnetic recording medium having an easy axis in the plane of the magnetic layer and a perpendicular magnetic recording medium having an easy axis in the direction perpendicular to the plane of the magnetic layer can be considered. Conventionally, in-plane magnetic recording media have generally been used, and the development of the above-described magnetic transfer technology has been proceeding with a focus on magnetic transfer to the in-plane magnetic recording medium. On the other hand, if a perpendicular magnetic recording medium is used, a further increase in capacity is expected as compared with a longitudinal magnetic recording medium.

  When performing magnetic transfer to a perpendicular magnetic recording medium, it is necessary to apply a magnetic field in a direction perpendicular to the surface of the magnetic layer, and it is considered that there are optimum conditions different from those of the in-plane magnetic recording medium.

  For example, at the time of magnetic transfer to a perpendicular magnetic recording medium, there is a problem that magnetization disturbance is large at the boundary between the magnetization reversal part and the non-reversal part, and the signal quality is not good. This is a problem caused by insufficient convergence of the magnetic flux to the magnetization reversal part, and it has become clear from the analysis by the present inventors that it is a cause of signal quality degradation.

  Also, in perpendicular magnetic transfer, the thickness of the convex pattern formed by the magnetic layer of the master carrier is thin, and the magnetic pole distance generated by passing the magnetic field vertically through this is short (demagnetizing field), and between adjacent convex parts. Since there is no assist that acts to converge the magnetic flux to the convex portion, it is difficult to realize sufficient signal quality only by creating a simple magnetic layer.

  In view of the above circumstances, an object of the present invention is to provide a magnetic transfer master carrier capable of performing good magnetic transfer on a perpendicular magnetic recording medium.

The magnetic transfer master carrier of the present invention is a magnetic transfer master carrier that is formed to transfer information to a magnetic layer of a perpendicular magnetic recording medium and has a pattern-like convex portion having a magnetic layer on the surface. there, between the protrusions, having parallel easy axis of magnetization in the magnetization easy axis of the magnetic layer of the convex portion, a second magnetic layer having a larger coercive force than coercive force of the magnetic layer of the convex portion And the second magnetic layer is previously magnetized in a direction perpendicular to the surface and in a direction opposite to the transfer magnetic field .

  At this time, the second magnetic layer only needs to be provided between the convex portions, and may be arranged so as to fill the entire concave portion between the convex portions, or in a part of the concave portion between the convex portions. May be arranged only.

The easy axis of magnetization of the convex magnetic layer and the second magnetic layer is perpendicular to the surface of the master carrier, which means that the second magnetic layer is previously magnetized in one direction.

The coercive force of the second magnetic layer is preferably twice the coercive force of the magnetic layer of the perpendicular magnetic recording medium.

  The magnetic transfer master carrier of the present invention has the magnetic layer of the convex portion of the magnetic transfer master carrier and the magnetic layer of the perpendicular magnetic recording medium in close contact with the magnetic layer. This method is suitable for a magnetic transfer method in which a transfer magnetic field is applied in a direction perpendicular to the magnetic layer of the magnetic recording medium to transfer the information to the magnetic layer of the perpendicular magnetic recording medium. Here, the “close contact” includes not only a state in which they are completely in close contact but also includes a state in which they are arranged close to each other at a uniform interval. Specific examples of the perpendicular magnetic recording medium include disk-shaped magnetic recording media such as a hard disk and a flexible disk.

  In the above-described magnetic transfer master carrier of the present invention, the magnetic layer on the convex surface is preferably soft or semi-hard.

  Alternatively, in the magnetic transfer master carrier of the present invention, it is desirable that the magnetic layer on the surface of the convex portion has a coercive force of 1/3 or less of the coercive force of the magnetic layer of the perpendicular magnetic recording medium.

  As the information, for example, a servo signal is suitable.

The master carrier of the present invention, between the projecting portions having a magnetic layer on the surface, larger coercivity than the coercivity of the magnetic layer of the convex portion having parallel easy axis of magnetization in the magnetization easy axis of the magnetic layer of the convex portion comprising a second magnetic layer having, by previously is magnetized in advance transfer magnetic field direction opposite the second magnetic layer, when the magnetic transfer, to enhance the magnetic flux suction effect on the magnetic layer of the surface of the protrusion signals The quality can be improved, the disturbance of magnetization at the boundary between magnetization reversal and non-reversal can be suppressed, and good magnetic transfer can be performed on the perpendicular magnetic recording medium.

  If the information carried by the magnetic transfer master carrier of the present invention is used as a servo signal, the servo signal can be easily and satisfactorily transferred to the perpendicular magnetic recording medium, and the preformatted perpendicular magnetic recording medium can be efficiently manufactured. Is possible.

  In a state where the magnetic transfer master carrier of the present invention and the perpendicular magnetic recording medium are in close contact with each other, a magnetic field for transfer is applied in a direction perpendicular to the track surface of the perpendicular magnetic recording medium to transfer the information to the perpendicular magnetic recording medium. According to the magnetic transfer method for transferring, as described above, good magnetic transfer can be performed because good magnetic flux is sucked into the magnetic layer on the convex surface of the master carrier.

  A perpendicular magnetic recording medium that has been magnetically transferred by the magnetic transfer method described above using the magnetic transfer master carrier of the present invention is a medium having a good information signal, and the information signal is a servo signal. In particular, recording and reproduction can be performed with high accuracy when positioning the magnetic head.

  Hereinafter, embodiments of the present invention will be described in detail. 1 to 4 are partial cross-sectional views of a magnetic transfer master carrier according to an embodiment of the present invention.

  FIG. 1 is a partial sectional view of a magnetic transfer master carrier according to the first embodiment. The master carrier 3 is formed in a disk shape as shown in FIG. 5 described later, and a pattern-like convex portion for transferring information to the slave medium is formed in a donut-shaped region surrounded by a dotted line in the same figure. Yes.

  FIG. 1 is a partial sectional view in the circumferential direction of the disk-shaped magnetic transfer master carrier 3 shown in FIG. The master carrier 3 shown in FIG. 1 includes a substrate 3a having a pattern-like convex portion on the surface and a soft magnetic layer 3b formed on the convex portion and in a concave portion between the convex portions. The circumferential width (track width) of the convex portion formed on the substrate 3a is w. The soft magnetic layer 3b formed on the surface of the convex portion of the substrate 3a has a height (thickness) d and a circumferential width w corresponding to the circumferential width of the concavo-convex pattern of the substrate 3a. Here, the ratio R (= d / w) of the height d to the width w of the soft magnetic layer on the surface of the convex portion of the substrate 3a is 0.8 or more and 3 or less.

  The soft magnetic layer formed on the convex surface of the substrate and the soft magnetic layer formed on the concave portion are magnetically coupled. For example, when a magnetic field in the direction from the substrate side to the magnetic layer is applied, the magnetic flux is Since the soft magnetic layer of the concave portion continuously enters the soft magnetic layer of the convex portion, this convex portion is compared with the case where the concave portion has no magnetic coupling with the soft magnetic layer or the concave portion has no soft magnetic layer. The effect of sucking magnetic flux is high.

  As the substrate 3a of the master carrier 3, nickel, silicon, quartz plate, glass, aluminum, ceramics, synthetic resin or the like is used. As the magnetic material of the soft magnetic layer 3b, Co, Co alloy (CoNi, CoNiZr, CoNbTaZr, etc.), Fe, Fe alloy (FeCo, FeCoNi, FeNiMo, FeAlSi, FeAl, FeTaN), Ni, Ni alloy (NiFe) FeCo and FeCoNi are particularly preferable.

  Formation of the pattern-like convex portion (uneven pattern) of the master carrier 3 can be performed using a stamper method used as a method for producing an optical disc master, a photolithography method used in semiconductor production, or the like. Hereinafter, the production of the master carrier will be briefly described.

  First, a photoresist is formed on a glass plate (or quartz plate) with a smooth surface by spin coating or the like, and laser light (or electron beam) modulated in response to a servo signal is irradiated while rotating the glass plate. Then, 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 is exposed to a portion corresponding to each frame on the circumference, and then the photoresist is applied. Development is performed to remove the exposed portion, and a master having a concavo-convex shape by a photoresist is obtained. Next, based on the concavo-convex pattern on the surface of the master, the surface is plated (electroformed) to produce a Ni substrate having a positive concavo-convex pattern and peeled off from the master. The substrate is used as a master carrier as it is, or a soft magnetic layer and a protective film are coated on the concavo-convex pattern as necessary to form a master carrier.

  Alternatively, the master may be plated to produce a second master, and the second master may be used for plating to produce a substrate having a negative uneven pattern. Furthermore, the second master may be plated or a resin solution may be pressed and cured to produce a third master, and the third master may be plated to produce a substrate having a positive uneven pattern. .

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

  As described above, Ni or Ni alloy or the like can be used as the material for the substrate made of metal, and the plating for producing this substrate includes various types including electroless plating, electroforming, sputtering, and ion plating. A metal film forming method can be applied. The convex part height (depth of the concave-convex pattern) of the substrate is preferably in the range of 50 to 800 nm, more preferably 80 to 600 nm. When this uneven pattern is a sample servo signal, a rectangular convex portion that is longer in the radial direction than in the circumferential direction is formed. Specifically, the length in the radial direction is preferably 0.05 to 20 μm, and the circumferential direction is preferably 0.05 to 5 μm. Selecting a value that has a longer shape in the radial direction within this range will carry the servo signal information. As preferred.

  The soft magnetic layer 3b is formed on the concavo-convex pattern of the substrate by using a magnetic material by vacuum deposition such as vacuum deposition, sputtering, ion plating, plating, or the like. The thickness of the soft magnetic layer is preferably in the range of 50 to 500 nm, more preferably 80 to 300 nm. As described above, the ratio R between the thickness d and the width w of the soft magnetic layer on the surface of the convex portion of the substrate is in the range of 0.8 to 3, preferably 0.9 to 2.5.

  A protective film such as diamond-like carbon (DLC) having a thickness of 5 to 30 nm is preferably provided on the soft magnetic layer on the convex surface, and a lubricant layer may be further provided. Further, an adhesion reinforcing layer such as Si may be provided between the soft magnetic layer and the protective film. By providing the lubricant, the deterioration of durability such as the occurrence of scratches due to friction when correcting the deviation generated in the contact process with the slave medium is improved.

  2, 3 and 4 are partial sectional views of the magnetic transfer master carrier according to the second to fourth embodiments of the present invention. The master carriers 13 and 23 shown in FIGS. 2 and 3 have substrates 13a and 23a having pattern-like convex portions similar to those of the master carrier 3 of the first embodiment described above, and between the convex surface and the convex portions. It consists of soft magnetic layers 13b and 23b formed in the recesses. In the master carrier 13 of the second embodiment shown in FIG. 2, the concave soft magnetic layer and the convex soft magnetic layer are separated from each other. As long as the distance can be magnetically coupled even if they are separated as described above, the same effect as in the above case can be obtained.

  Further, the master carrier 23 of the third embodiment shown in FIG. 3 has a concave and convex soft magnetic layer formed completely continuously, contrary to that of FIG. In this case, the magnetic flux can be effectively sucked into the soft magnetic layer on the surface of the convex portion.

  The master carriers of the second and third embodiments can be produced by the same method as the master carrier of the first embodiment described above, and if the thickness of the soft magnetic layer formed on the substrate is changed at the time of production, Good.

  The master carrier 33 shown in FIG. 4 includes a flat substrate 33a and a soft magnetic layer 33b formed on the substrate 33a and formed in a concavo-convex pattern. Thus, a flat substrate 33a may be used, and the same effect as in the case of the soft magnetic layer provided along the unevenness of the substrate described in FIGS. 1 to 3 by the convex and concave portions of the soft magnetic layer 33b. Can be obtained. In such a master carrier 33, after a soft magnetic layer 33b having a thickness d is uniformly formed on a substrate 33a, irregularities may be formed in the soft magnetic layer 33b using a photolithography method or the like. Here, the thickness d of the soft magnetic layer 33b on the convex surface corresponds to the thickness from the substrate surface.

  In the master carrier of each embodiment, the ratio R between the thickness d of the soft magnetic layers 13b, 23b, and 33b on the convex portion or constituting the convex portion and the circumferential width w thereof is 0.8 or more and 3 or less.

  Next, an embodiment of a magnetic transfer method for transferring information to a slave medium using the magnetic transfer master carrier of the present invention will be described.

  FIG. 5 is a perspective view showing the slave medium 2 and the master carriers 3 and 4. The slave medium is, for example, a disk-shaped magnetic recording medium such as a hard disk or a flexible disk having a magnetic recording layer formed on both sides or one side. In particular, the direction of easy magnetization of the magnetic recording layer is perpendicular to the recording surface. A perpendicular magnetic recording medium is formed. In the present embodiment, the magnetic recording layers 2b and 2c are respectively formed on both surfaces of a disk-shaped substrate 2a.

  The master carrier 3 is the same as that shown in the first embodiment, and a pattern-like convex portion for the lower recording layer 2b of the slave medium 2 is formed. The master carrier 4 is formed with a pattern-like convex portion for the upper recording layer 2 c of the slave medium 2, which has the same layer structure as the master carrier 3. Taking the master carrier 3 as an example, the pattern-like convex portion is formed in a donut-shaped region surrounded by a dotted line in the figure.

  FIG. 6 is a diagram for explaining the basic steps of this magnetic transfer. FIG. 6 (a) is a step in which a magnetic field is applied in one direction and the slave medium is initially DC magnetized, and (b) is a master carrier and slave. (C) is a view showing a state after magnetic transfer, in which a magnetic field is applied in a direction opposite to the initial DC magnetic field by closely contacting the medium. In FIG. 6, only the lower recording layer 2b side of the slave medium 2 is shown.

  As shown in FIG. 6A, an initial direct current magnetic field Hin is applied to the slave medium 2 in one direction perpendicular to the track surface in advance to magnetize the magnetic recording layer 2b. Thereafter, as shown in FIG. 6B, the surface of the slave medium 2 on the recording layer 2b side and the surface of the convex surface of the master carrier 3 on the soft magnetic layer 3b side are brought into close contact with each other. Magnetic transfer is performed by applying a transfer magnetic field Hdu in a direction opposite to the initial DC magnetic field Hin in a direction perpendicular to the magnetic field. As a result, as shown in FIG. 6C, information (for example, servo signals) corresponding to the convex pattern of the master carrier 3 is magnetically transferred and recorded on the magnetic recording layer 2b of the slave medium 2. Here, magnetic transfer by the lower master carrier 3 to the lower recording layer 2b of the slave medium 2 has been described. However, as shown in FIG. 5, the upper recording layer 2c of the slave medium 2 is also in close contact with the upper master carrier 4. In the same manner as the lower recording layer, magnetic transfer is performed simultaneously with the lower recording layer.

  Further, even if the concave / convex pattern of the master carrier 3 is a negative pattern having a concave / convex shape opposite to the positive pattern of FIG. 6, the direction of the initial magnetic field Hin and the direction of the transfer magnetic field Hdu are reversed from the above. Similar information can be magnetically transferred and recorded. Note that the initial DC magnetic field and the transfer magnetic field need to adopt values determined in consideration of the coercivity of the slave medium, the relative permeability of the master carrier and the slave medium, and the like.

  As the slave medium 2, a disk-shaped magnetic recording medium such as a hard disk or a high-density flexible disk is used, and a coating type magnetic recording layer or a metal thin film type magnetic recording layer is formed as the magnetic recording layer. Here, a magnetic recording layer having a magnetic anisotropy having an easy magnetization axis in a direction perpendicular to the track surface is used. As the magnetic material of the metal thin film type magnetic recording layer, Co, Co alloy (CoPtCr, CoCr, CoPtCrTa, CoPtCrNbTa, CoCrB, CoNi, etc.), Fe, Fe alloy (FeCo, FePt, FeCoNi) can be used. In order to give the magnetic recording layer the necessary magnetic anisotropy, it is preferable to provide a nonmagnetic underlayer under the magnetic recording layer. This nonmagnetic underlayer needs to match the crystal structure and lattice constant to the magnetic recording layer, and examples of such materials include Ti, Cr, CrTi, CoCr, CrTa, CrMo, NiAl, Ru, and Pd. . In order to stabilize the perpendicular magnetization state of the magnetic layer and to improve the sensitivity during recording and reproduction, it is preferable to provide a backing layer made of a soft magnetic layer below the nonmagnetic underlayer.

  The magnetic recording layer thickness is preferably 10 nm or more and 500 nm or less, and more preferably 20 nm or more and 200 nm or less. The nonmagnetic layer thickness is preferably 10 nm or more and 150 nm or less, and more preferably 20 nm or more and 80 nm or less. Further, the backing layer thickness is preferably 50 nm or more and 2000 nm or less, more preferably 80 nm or more and 400 nm or less.

  Next, the results of a transfer accuracy experiment in magnetic transfer performed using the embodiment of the magnetic transfer master carrier described above will be described.

In the following experiment, as a slave medium, argon was introduced after depressurizing to 1.33 × 10 ^-5 Pa (10 ^-7 Torr) at room temperature using a vacuum film deposition system (Shibaura Mechatronics: S-50S sputtering system). Then, the glass plate is heated to 200 ° C. under the condition of 0.4 Pa (3 × 10 ⁻³ Torr), NiFe is 300 nm as a backing layer made of a soft magnetic layer, Ti is 30 nm as a nonmagnetic underlayer, and magnetic recording A CoCrPt layer of 30 nm was sequentially laminated as a layer, and a 3.5-inch disk-shaped magnetic recording medium having a saturation magnetization Ms: 5.7 T (4700 Gauss) and a coercive force Hcs: 199 kA / m (2500 Oe) was prepared and used.

  As the signal quality evaluation, the transfer signal of the slave medium was evaluated by an electromagnetic conversion characteristic measuring device (SS-60 manufactured by Kyodo Electronics). An MR head having a reproducing head gap of 0.19 μm, a reproducing track width of 2.0 μm, a recording head gap of 0.4 μm, and a recording track width of 2.6 μm was used as the head. The read signal was frequency-resolved with a spectrum analyzer, and the ratio C / N between the peak intensity (C) of the primary signal and the extrapolated medium noise (N) was measured. The C / N value calculated by recording and reproducing with the head is set to 0 dB, and a relative value ΔC / N is obtained. If this ΔC / N is −2.0 dB or more, it is good (◯), and if it is less than −2.0 dB, it is bad ( X) was evaluated.

  For evaluation of signal omission / adhesion, magnetic developer (Sigma Marker Q manufactured by Sigma High Chemical Co., Ltd.) diluted 10 times is dropped on a slave medium subjected to magnetic transfer, and dried to develop the magnetic transfer signal pattern. Evaluation based on the variation amount of the pattern edge was performed. Specifically, 100 fields of view are randomly observed on the slave medium at a magnification of 50 times with a differential interference microscope, and if there are less than 5 signal omissions within this 100 fields of view (○), 5 or more If so, it was evaluated as defective (×).

The master carrier of Example 1 is a disc in which a convex pattern having a track width of 2.5 μm, a track pitch of 3.0 μm, a bit length of 0.5 μm, and a height of 2.5 μm is formed by lithography in a radial direction of 20 to 40 mm from the center of the disc. A soft magnetic layer having a thickness of 0.5 μm is formed on a quartz substrate on which a convex pattern is formed using FeCo 30 at% as a material by a sputtering method. The sputtering conditions for forming the soft magnetic layer were 25 ° C., the Ar sputtering pressure was 1.5 × 10 ⁻¹ Pa (1.08 mTorr), and the input power was 2.80 W / cm ² . The bit length of 0.5 μm corresponds to the circumferential width w of the convex portion. That is, in the master carrier of Example 1, the soft magnetic layer formed on the convex surface of the substrate has a height (thickness) d = 0.5 μm, a circumferential width w = 0.5 μm, and the ratio R = 1 having a cross section.

  The master carrier of Example 2 has a soft magnetic layer thickness of 1.0 μm in Example 1, and has a cross section of height d = 1.0 μm, circumferential width w = 0.5 μm, and R = 2. It is.

  The master carrier of Example 3 has a soft magnetic layer thickness of 1.4 μm in Example 1, and has a cross section of height d = 1.4 μm, circumferential width w = 0.5 μm, and R = 2.8. It is.

  The master carrier of Comparative Example 1 is obtained by forming a soft magnetic layer having a thickness of 0.5 μm on a flat quartz substrate and then patterning the soft magnetic layer by a lithography technique. Since the soft magnetic layer is not formed in the concave portion, the concave portion and the convex portion are not magnetically coupled. This master carrier has a cross section with a height d = 0.5 μm, a circumferential width w = 0.5 μm, and R = 1.

  The master carrier of Comparative Example 2 is formed by forming a soft magnetic layer on a quartz substrate on which a convex pattern is formed as in Example 1, but the soft magnetic layer is 0.35 μm and has a height d. = 0.35 μm, circumferential width w = 0.5 μm, and R = 0.7.

  The master carrier of Comparative Example 3 is formed by forming a soft magnetic layer on a quartz substrate on which a concavo-convex pattern is formed as in Example 1, but the soft magnetic layer is 2.0 μm and the height d = It has a cross section of 2.0 μm, circumferential width w = 0.5 μm, and R = 4.

Magnetic transfer to the above-mentioned slave medium was performed using the master carrier of each Example and Comparative Example, and signal quality and signal omission / adhesion degree were evaluated, respectively. The results are shown in Table 1.

  As shown in Table 1, as in Examples 1 to 3, the ratio R of the cross-sectional height of the magnetic layer (that is, the thickness of the magnetic layer) of the convex portion of the master carrier to the width in the track direction of the convex portion is 0.8 to 3 In addition, when the concave portion between the convex portions has a soft magnetic layer that is magnetically coupled to the soft magnetic layer on the convex portion surface, good results were obtained in both signal quality and signal omission / adhesion. On the other hand, in the case where there is no magnetic coupling between the concave and convex surfaces as in Comparative Examples 1 to 3, or the ratio R is not in the range of 0.8 or more and 3 or less, Either one was defective.

  Next, a magnetic transfer master carrier according to another embodiment of the present invention will be described with reference to FIG.

  The master carrier 53 shown in FIG. 7 includes a substrate 51 having a patterned uneven portion on the surface and a soft magnetic layer 52 formed on the surface of the uneven portion, and the soft magnetic layer 52 is formed on the protruded portion. The soft magnetic layer 52a and the soft magnetic layer 52b formed in the concave portion between the convex portions are formed while applying a magnetic field Hpr in a direction perpendicular to the surface of the substrate 51. is there.

  The soft magnetic layer 52 is formed by sputtering or the like while applying a magnetic field Hpr in a direction perpendicular to the surface of the substrate 51. By applying the magnetic field Hpr at the time of film formation, the formed soft magnetic layer 52 is oriented in the magnetic field direction and given perpendicular magnetic anisotropy. That is, the easy axis of the soft magnetic layer 52 is substantially perpendicular to the surface of the master carrier 53. The application direction of the magnetic field Hpr is substantially parallel to the application direction of the transfer magnetic field Hdu (see FIG. 6) during magnetic transfer, and the direction may be either the same direction or the opposite direction.

  In this way, if the easy magnetization axis of the soft magnetic layer 52 is set substantially perpendicular to the surface of the master carrier 53, the effect of sucking the magnetic flux when the transfer magnetic field is applied can be improved.

  Next, a magnetic transfer master carrier according to still another embodiment of the present invention will be described.

  A master carrier 63 shown in FIG. 8 includes a substrate 61 having a pattern-like convex portion on the surface, and a soft magnetic layer 62 formed on the convex portion and in a concave portion between the convex portions, and further, the convex portion surface. A magnetic layer 65 is embedded in a recessed region between the soft magnetic layers. Here, the magnetic layer 65 may be directly provided in the recess without providing the soft magnetic layer.

  The magnetic layer 65 has an easy magnetization axis parallel to the easy magnetization axis of the soft magnetic layer 62. If the magnetic layer 65 is magnetized in one direction of the easy axis in advance, when a magnetic field is applied in the direction opposite to the magnetization direction, the magnetic flux is repelled by the magnetization of the magnetic layer 65, forcing the convex portion. Since it enters the soft magnetic layer 62b, the effect of sucking the magnetic flux into the soft magnetic layer 62b of the convex portion is high. Here, the easy magnetization directions of the soft magnetic layer 62 and the magnetic layer 65 are substantially perpendicular to the surface of the master carrier.

  The material of the magnetic layer 65 preferably has a coercive force that is larger than the coercive force of the soft magnetic layer 62 and does not reverse the magnetization by the applied magnetic field during magnetic transfer. Those having a coercive force about twice the coercive force Hcs of the layer are suitable.

  Next, a magnetic transfer method for transferring information to the slave medium 2 using the magnetic transfer master carrier 63 of this embodiment will be described.

  Similar to the magnetic transfer method described above, the master carrier is placed in close contact with or close to the top and bottom of the slave medium 2.

  FIG. 9 is a diagram for explaining the basic steps of this magnetic transfer. FIG. 9A shows a step of applying a magnetic field in one direction to initial DC magnetization of the slave medium, and FIG. 9B shows a master carrier. (C) is a diagram showing a state after magnetic transfer, in which a magnetic field is applied in a direction opposite to the initial DC magnetic field by closely contacting the slave medium. In FIG. 9, only the lower recording layer 2b side of the slave medium 2 is shown.

  As shown in FIG. 9A, an initial direct current magnetic field Hin is applied to the slave medium 2 in one direction perpendicular to the track surface in advance, thereby magnetizing the magnetic recording layer 2b. Thereafter, as shown in FIG. 9B, the surface on the recording layer 2b side of the slave medium 2 and the surface of the master carrier 63 provided with the magnetic layer 65 previously magnetized in one direction perpendicular to the surface are in close contact with each other. Then, a transfer magnetic field Hdu is applied in a direction opposite to the initial DC magnetic field Hin in the direction perpendicular to the track surface of the slave medium 2 (this is also the direction opposite to the magnetization direction of the magnetic layer 65 of the master carrier 63). Then, magnetic transfer is performed. As a result, as shown in FIG. 9C, information (for example, servo signals) corresponding to the convex pattern of the master carrier 63 is magnetically transferred and recorded on the magnetic recording layer 2b of the slave medium 2. Here, the magnetic transfer by the lower master carrier 63 to the lower recording layer 2b of the slave medium 2 has been described. However, the upper recording layer 2c of the slave medium 2 is also in close contact with the upper master carrier and is the same as the lower recording layer. Thus, magnetic transfer is performed simultaneously with the lower recording layer.

  In this way, the magnetic layer 65 provided in the concave portion between the convex portions of the master carrier is previously magnetized in the direction opposite to the direction in which the transfer magnetic field is applied, so that the magnetic layer 65 on the magnetic flux when the transfer magnetic field is applied The convergence effect on the soft magnetic layer 62 can be improved, and good magnetic transfer can be performed.

  Note that the initial DC magnetic field and the transfer magnetic field need to adopt values determined in consideration of the coercivity of the slave medium, the relative permeability of the master carrier and the slave medium, and the like.

1 is a partial cross-sectional view of a magnetic transfer master carrier according to a first embodiment of the present invention. Partial sectional view of a magnetic transfer master carrier according to a second embodiment of the present invention Partial sectional view of a magnetic transfer master carrier according to a third embodiment of the present invention Partial sectional view of a magnetic transfer master carrier according to a fourth embodiment of the present invention Perspective view showing slave medium and master carrier Diagram showing the basic steps of the magnetic transfer method Partial sectional view of a magnetic transfer master carrier according to another embodiment of the present invention FIG. 6 is a partial cross-sectional view of a magnetic transfer master carrier according to still another embodiment of the present invention. The figure which shows the basic process of the magnetic transfer method using the master carrier for magnetic transfer shown in FIG.

Explanation of symbols

2 Slave medium 2a Substrate 2b, 2c Magnetic layer (magnetic recording layer)
3, 4 Master carrier 3a, 4a Substrate 3b, 4b Soft magnetic layer
51 PCB
52 Soft magnetic layer
53 Master carrier
61 substrate
62 Soft magnetic layer
63 Master carrier
65 Magnetic layer

Claims (3)

A master carrier for magnetic transfer, which is formed to transfer information to a magnetic layer of a perpendicular magnetic recording medium and has a pattern-like convex portion having a magnetic layer on the surface,
Between the convex portions, having parallel easy axis of magnetization in the magnetization easy axis of the magnetic layer of the convex portion, a second magnetic layer having a larger coercive force than coercive force of the magnetic layer of the convex portion is disposed, The magnetic transfer master carrier, wherein the second magnetic layer is previously magnetized in a direction perpendicular to the surface and in a direction opposite to the transfer magnetic field . It said second-holding force of the magnetic layer, the claim 1 for magnetic transfer master carrier, wherein the twice the coercive force of the magnetic layer of the perpendicular magnetic recording medium. 3. The magnetic transfer master carrier according to claim 1, wherein the information is a servo signal.

Images