JP2003178440A - Master carrier for magnetic transfer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a slave medium from being damaged by easily peeling the slave medium from a master carrier after tightly adhering the master carrier to the slave medium for magnetic transfer in the master carrier for the magnetic transfer. <P>SOLUTION: The master carrier 3 has the irregular pattern of a magnetic substance 32 complying with information on the magnetic transfer on a substrate 31. The protruding part 40 of the irregular pattern has a spherical top face 44. The slave medium 2 is tightly adhered to the top face 44 by following the top face 44 when the slave medium is pressed against the protruding part 40 for the magnetic transfer. Releasing pressure after the magnetic transfer elastically recovers the slave medium 2 to a flat surface, easily peeling the slave medium from the master carrier. A ratio (R/L) of the radius of curvature (R) of the curved surface of the top face 44 to the virtual flat portion length (L) of the top face is set to 150≤R/L≤1,000. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic transfer master carrier carrying transfer information for magnetic transfer to a slave medium. A magnetic transfer method is a method in which a surface of a slave medium having a magnetic recording portion is brought into close contact with a surface of a master carrier having a concavo-convex shape corresponding to transfer information formed by a magnetic material on the surface of a substrate. In this state, a magnetic field for transfer is applied, and a magnetization pattern corresponding to information (for example, a servo signal) carried on the master carrier is transferred and recorded on the magnetic recording portion of the slave medium. This magnetic transfer method is disclosed in, for example,
No. 0-40544, Japanese Patent Laid-Open No. 10-269566, and the like. A master carrier used for magnetic transfer is formed by forming a concave / convex pattern with a magnetic material by subjecting a silicon substrate, a glass substrate, or the like to treatments such as photofabrication, sputtering, and etching. In addition, lithography technology used in semiconductors,
Alternatively, it is considered that a master carrier for magnetic transfer is produced by applying a stamper producing technique used for producing an optical disc stamper. In order to improve the transfer quality in the above magnetic transfer, it is an important issue how the master carrier and the slave medium are closely contacted with each other. That is, if there is poor adhesion, there will be areas where sufficient recording signal intensity cannot be obtained and magnetic transfer does not occur. If magnetic transfer does not occur, signal loss occurs in the magnetic information transferred to the slave medium and the signal quality deteriorates. If the recorded signal is a servo signal, the tracking function cannot be obtained sufficiently, and the read reliability is reduced. Sex is reduced. For this reason, it has been carried out by the above-mentioned prior art or the like to ensure the adhesion between the convex portions of the concave / convex pattern of the master carrier and the slave medium. By the way, in the master carrier as described above, the top surface shape of the convex portion of the concavo-convex pattern is flat, and the slave medium is brought into close contact with the flat top surface. Maintaining sex. On the other hand, since the adhesiveness is good, a large force is required for peeling off the master after the magnetic transfer. For this reason, there is a possibility that the quality of the transferred information is deteriorated because the master carrier arranged at a predetermined position is displaced or the surface of the slave medium is damaged. The present invention has been made in view of such a problem. The master carrier can be peeled off with a small force while ensuring the adhesion between the master carrier and the slave medium. It is an object of the present invention to provide a magnetic transfer master carrier in which there is no risk of occurrence of scratches on the recording surface of a slave medium. The magnetic transfer master carrier of the present invention is a magnetic transfer master carrier having a magnetic material concavo-convex pattern corresponding to information to be transferred. The top surface is formed into a curved surface, and the ratio of the curvature radius (R) of the curved surface to the virtual flat portion length (L) of the top surface (R /
L) is in the range of 150 ≦ R / L ≦ 1000. Here, the “virtual flat portion” is a flat portion surrounded by a line passing through the apex of the curved surface of the top surface and intersecting the plane parallel to the substrate of the master carrier and the extended surface of the side surface around the convex portion. It says the side. Further, the “virtual flat part length” refers to a distance between opposing edges (end edges) of the flat surface. The curved surface may be a spherical surface or a cylindrical column extending in the radial direction or the track direction of the master carrier. The ratio (R / L) of the curvature radius (R) of the curved surface to the virtual flat part length (L) of the top surface is 500 ≦ R / L ≦
More preferably, it is in the range of 900. The magnetic transfer master carrier according to the present invention has a convex top surface of a concavo-convex pattern corresponding to information formed into a curved surface, and the curvature radius (R) of the curved surface and the imaginary surface of the top surface. Since the ratio (R / L) of the flat part length (L) is in the range of 150 ≦ R / L ≦ 1000, the following effects are achieved. That is, when the slave medium is superimposed on the magnetic transfer master carrier of the present invention and pressure is applied to the slave medium for magnetic transfer, the shape of the slave medium is deformed following the surface of the convex portion of the master carrier. In close contact. When the pressure is released after the magnetic transfer, the slave medium spontaneously returns to a flat shape due to the elastic force, and a peeling force acts between the master carrier and the slave medium. Can be peeled off. Accordingly, misalignment of the master carrier and damage to the slave medium are unlikely to occur. As a result, transfer defects can be reduced, the quality of transferred information can be improved, and information based on the magnetization pattern can be accurately reproduced. In particular, when the information is a servo signal, tracking accuracy is improved. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail below. FIG. 1 is a diagram showing an example of a magnetic transfer method using a magnetic transfer master carrier (hereinafter simply referred to as a master carrier) according to one embodiment of the present invention, and FIG. FIG. 1B is a cross-sectional view showing a state where a slave medium and a master carrier are brought into close contact with each other and a magnetic field for transfer is applied, and FIG. 1C is a cross-sectional view showing a magnetic pattern of the slave medium magnetically transferred. Each is shown. The form shown in FIG. 1 is an in-plane recording method. Each figure is a schematic diagram, and the dimensions of each part are exaggerated at a ratio different from the actual one so as to be easily understood. As shown in FIG. 1B, the master carrier 3
Is formed in a disk shape, and has a transfer information carrying surface formed with a fine uneven pattern by a soft magnetic layer 32 corresponding to a servo signal on one side, and a surface opposite to this is held by a holder (not shown) In close contact with the slave medium 2. The outline of the magnetic transfer method by in-plane recording is as follows. First, as shown in FIG. 1A, an initial static magnetic field Hin is first applied to the slave medium 2 in one direction in the track direction to perform initial magnetization (DC demagnetization) in advance. after that,
As shown in FIG. 1B, the slave surface (magnetic recording portion) 33 of the slave medium 2 and the top surface of the convex pattern 32a of the concave / convex pattern that becomes the information carrying surface of the master carrier 3 are brought into close contact with each other. The fine uneven pattern of the substrate 31 of the master carrier 3 is covered with a soft magnetic layer 32 (magnetic material).
Then, magnetic transfer is performed by applying a transfer magnetic field Hdu in the direction opposite to the initial magnetic field Hin in the track direction of the slave medium 2. As shown in FIG. 1C, the transfer magnetic field Hdu is sucked into the soft magnetic layer 32 of the convex pattern 32a and the magnetization of this part is not reversed, and the magnetic field of the other part is reversed.
On the slave surface 33 of the slave medium 2, the master carrier 3
Adhering convex pattern 32a of the soft magnetic layer 32 on the information carrying surface of
And a magnetization pattern corresponding to the formation pattern of the recess space are transferred and recorded along the track direction. In this way, the information recorded on the master carrier 3 is magnetically transferred to the slave medium 2. In order to perform this transfer satisfactorily, it is necessary to flatten the top surface of the convex portion of the concave / convex pattern of the master carrier 3 to improve the adhesion to the slave medium 2. However, although the adhesion is improved, a large force is required to peel off the slave medium 2 from the master carrier 3. For this reason, misalignment of the master carrier 3 positioned on the holder 10 occurs, or the surface of the slave medium 2 is scratched. Therefore, in the present invention, the unevenness is not affected to the extent that there is no problem in terms of signal quality and adhesion. The flatness of the pattern was formed by a curved surface having a very large radius of curvature. As the substrate 31 of the master carrier 3, nickel, silicon, quartz plate, glass, aluminum, alloy, ceramics, synthetic resin or the like is used. The formation of the concavo-convex pattern is performed by a stamper method or the like. The soft magnetic material is formed by depositing a magnetic material by a vacuum film-forming means such as a vacuum deposition method, a sputtering method or an ion plating method, a plating method, or the like. Hereinafter, the uneven pattern of the master carrier 3 of the present invention will be described in detail with reference to FIG. FIG.
FIG. 2 is a partially enlarged view of the convex portion 40 showing one convex portion 40 of the concave-convex pattern in an enlarged manner, and FIG.
FIG. 2B is a side view taken along the line A, and FIG. 2B is a side view of the protrusion 40 viewed from A in FIG. The planar shape of the top surface 44 of the convex portion 40 is substantially rectangular, and the top surface 44 is formed into a curved surface. In the embodiment shown in FIG. 2, the curved surface 44 is formed as a part of a spherical surface. The convex portion 40 is formed on the substrate 31 of the master carrier 3. The curvature radius R of the curved surface 44 is set such that R / L is 150 or more and 1000 or less, where L is the length of the virtual flat portion 42 of the convex portion 40. Now, assuming that the slave medium 2 is pressed against the spherical top surface 44 of the convex portion 40, the slave surface 33 of the slave medium 2 is elastically deformed and closely adheres to the shape of the top surface 44. When the pressing force is released after the magnetic transfer, the slave medium 2 is separated from the top surface 44 due to the elasticity of the slave medium 2 itself and returns to the planar shape, so that the peeling is facilitated. As shown in FIG. 2, the top surface 44 is most preferably a part of a spherical surface, but may be a part of the surface of a virtual cylinder extending in a direction parallel to or perpendicular to the track direction T. When the substrate 31 is made of a ferromagnetic material such as Ni, the magnetic transfer can be performed only with the substrate 31 and the soft magnetic layer 32 may not be coated. However, the soft magnetic layer 32 having good transfer characteristics may be formed. By providing, better magnetic transfer can be performed. In that case, the magnetic layer 32 is formed in the same shape as the convex portion 40, following the shape of the convex portion 40 of the substrate 31. Substrate 31
In the case of a non-magnetic material, it is necessary to provide the soft magnetic layer 32. The specific shape of the convex portion has a height of 50 nm to
800 nm, preferably 80 nm to 600 nm. The thickness of the magnetic layer 32 is 50 nm to 500 nm.
It is preferably 80 nm to 300 nm. When this uneven pattern is a servo signal, a convex part on a rectangle 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. The value of the servo signal is to select a value that has a longer shape in the radial direction within this range. It is preferable as a pattern for supporting. A protective film such as diamond-like carbon (DLC) is preferably provided on the soft magnetic layer 32, and a lubricant layer may be provided. Also as a protective film 5
More preferably, a 30 nm DLC film and a lubricant layer are present. Further, an adhesion reinforcing layer such as Si may be provided between the soft magnetic layer 32 and the protective film. The lubricant improves the deterioration of durability such as the occurrence of scratches due to friction when correcting the deviation caused in the contact process with the slave medium 2. Next, a method for producing the master carrier 3 of the present invention will be described. As the substrate 31 of the master carrier 3,
Nickel, silicon, quartz plate, glass, aluminum,
Alloys, ceramics, synthetic resins, etc. are used. The formation of the concavo-convex pattern is performed by a stamper method or the like. In the stamper method, a laser beam (or electron beam) modulated in response to a servo signal is formed by forming a photoresist on a glass plate (or quartz plate) with a smooth surface by spin coating or the like and rotating the glass plate. And a predetermined pattern, for example, a pattern corresponding to a servo signal extending in the radial direction from the center of rotation on each track is exposed on a portion corresponding to each frame on the circumference. At that time, the intensity distribution of the laser beam is changed, and the exposed portion is irradiated so as to form an uneven pattern having a spherical surface.
That is, the portion corresponding to the apex of the spherical surface is irradiated most strongly, and the peripheral portion is irradiated weakly so as not to cause a step. Thereafter, the photoresist is developed, the exposed portion is removed, and a master having a concavo-convex shape by the photoresist is obtained. Next, based on the concavo-convex pattern on the surface of the master, plating (electroforming) is performed on this surface to create a Ni substrate having a positive concavo-convex pattern, which is 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. In addition, a second master is produced by plating the master, and plating is performed using the second master.
You may create the board | substrate which has a negative uneven | corrugated pattern. Furthermore, the second master may be plated or a resin solution may be pressed and cured to create a third master, and the third master may be plated to create a substrate having a positive uneven pattern. . The soft magnetic layer 32 is formed by depositing a magnetic material by a vacuum film forming means such as a vacuum deposition method, a sputtering method or an ion plating method, or a plating method. As the magnetic material, Co, Co alloy (CoNi, CoN
iZr, CoNbTaZr, etc.), Fe, Fe alloy (Fe
Co, FeCoNi, FeNiMo, FeAlSi, F
eAl, FeTaN), Ni, Ni alloy (NiFe) can be used. Particularly preferably, FeCo, FeC
oNi. A resin substrate may be prepared using the master, and a soft magnetic layer may be provided on the surface to serve as a master carrier. As the resin material of the resin substrate, acrylic resin such as polycarbonate / polymethyl methacrylate, vinyl chloride resin such as polyvinyl chloride / vinyl chloride copolymer, epoxy resin, amorphous polyolefin, and polyester can be used. Polycarbonate is preferable from the viewpoints of moisture resistance, dimensional stability and price. If there are burrs in the molded product, remove them with burnish or polish. Further, the master may be formed by spin coating or bar coating using an ultraviolet curable resin, an electron beam curable resin, or the like. The height of the pattern protrusion on the resin substrate is 50
Preferably in the range of ~ 1000 nm, more preferably 1
It is the range of 00-500 nm. A soft carrier is coated on the fine pattern on the surface of the resin substrate to obtain a master carrier. The soft magnetic layer is formed by depositing a magnetic material by a vacuum film forming means such as a vacuum deposition method, a sputtering method, or an ion plating method, a plating method, or the like. As the slave medium 2, a disk-shaped magnetic recording medium such as a hard disk or a high density flexible disk having a magnetic recording part (magnetic layer) formed on both sides or one side is used, and the magnetic recording part is a coating type magnetic recording layer. Alternatively, it is composed of a metal thin film type magnetic recording layer. 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 (FeC
o, FePt, FeCoNi).
It is preferable that the magnetic flux density is large and the magnetic anisotropy is the same direction as the magnetic field application direction (in-plane direction for in-plane recording and perpendicular direction for perpendicular recording) because clear transfer can be performed. In order to give necessary magnetic anisotropy under the magnetic material (on the support side), it is preferable to provide a nonmagnetic underlayer. It is necessary to match the crystal structure and lattice constant to the magnetic layer. For that purpose, Cr, CrTi, CoCr,
CrTa, CrMo, NiAl, Ru or the like is used. The slave medium 2 is a master carrier 3.
Before being in close contact with the surface, a cleaning process is performed as necessary to remove minute protrusions or adhering dust on the surface with a glide head, a polishing body, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an example of a magnetic transfer method using a magnetic transfer master carrier according to one embodiment of the present invention, wherein (a) is a cross-sectional view of a slave medium; (B) is a cross-sectional view showing a state in which a slave medium and a master carrier are brought into close contact with each other and a transfer magnetic field is applied, and (c) is a cross-sectional view showing a magnetic pattern of the magnetically transferred slave medium. FIG. 2 is a partially enlarged view showing a convex portion having a curved top surface, one of the concavo-convex patterns, (a) is a cross-sectional view cut along the track direction, and (b) is FIG. 2 (a). ) A
The side view of the convex part seen from each is shown. [Explanation of Symbols] 2 Slave medium 3 Master carrier 31 Substrate 40 Protruding portion 44 Top surface L Virtual flat portion length R Curvature radius

Claims (1)

What is claimed is: 1. A magnetic transfer master carrier having a concavo-convex pattern of a magnetic material corresponding to information to be transferred, wherein a top surface of a convex portion of the concavo-convex pattern is formed into a curved surface, Radius of curvature (R) and virtual flat length (L) of the top surface
The magnetic transfer master carrier, wherein the ratio (R / L) is in the range of 150 ≦ R / L ≦ 1000.