JP2011141949A - Magnetic recording medium, method for manufacturing the same, stamper for imprint lithography, and master of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve yield and quality control of a magnetic recording medium having a discrete track manufactured by imprint lithography. <P>SOLUTION: A magnetic recording layer includes: a recording track pattern released by grooves; and a management information pattern showing binary management information such as a manufacturing number, a management number, a manufacturing date, a manufacturing location, a manufacturer, a manufacturing route, storage capacity, and size. The management information pattern is recorded in neighboring recording tracks. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium having a discrete track, an imprint stamper for forming such a magnetic recording medium, a master for forming the same, and a method of manufacturing a magnetic recording medium using these.

  In recent years, in order to cope with further increase in the density of magnetic recording media, a discrete track medium in which adjacent recording tracks are separated by a groove or a guard band made of a nonmagnetic material to reduce magnetic interference between adjacent tracks. Has attracted attention.

  When manufacturing such a discrete track medium, a magnetic recording layer pattern can be formed by an imprint method using a stamper.

  This stamper can be easily replicated using a resist master obtained by, for example, electron beam drawing of a pattern corresponding to the pattern of the magnetic recording layer. Thereby, a magnetic recording medium can be produced in large quantities at low cost.

  However, in the technique using the master and the stamper as described above, if a defect is found in the manufactured magnetic recording medium, it becomes necessary to track the master and the stamper that are the cause. For this purpose, it has been desired to record management information such as a manufacturing number, a management number, a manufacturing date, a manufacturing place, a manufacturer, a sales route, a storage capacity, and a size on each magnetic recording medium. .

  As a method of recording management information on a magnetic recording medium, there is a method of magnetically transferring management information from a magnetic transfer master carrier. In this method, a concave / convex pattern is provided on a part of the magnetic transfer master carrier. The information corresponding to this is magnetically transferred and recorded on a magnetic recording medium (see, for example, Patent Document 1).

JP 2002-230750 A

  The present invention has been made in view of the above circumstances, and management information suitable for tracking the cause when a defect has occurred in a magnetic recording medium having a discrete track manufactured using an imprint method can be obtained at low cost. The goal is to easily record and improve yield and quality control.

The perpendicular magnetic recording medium of the present invention includes a nonmagnetic substrate and a magnetic recording layer formed on the nonmagnetic substrate,
The magnetic recording layer is at least one selected from the group consisting of a recording track pattern separated by at least grooves, a manufacturing number, a control number, a manufacturing date, a manufacturing location, a manufacturer, a sales route, a storage capacity, and a size. Management information pattern that binarizes and represents management information of
The recording track pattern and the management information pattern are:
Formed by subjecting the surface of the magnetic recording layer and a resist provided on the surface of the magnetic recording layer, having a concave and convex pattern similar to the recording track pattern and the management information pattern, to etching;
A resist having a concavo-convex pattern similar to the recording track pattern and the management information pattern,
After transferring the concavo-convex pattern similar to the recording track pattern formed on the master by electron beam drawing to an imprint stamper, and forming the concavo-convex pattern opposite to the recording track pattern,
A concave / convex pattern opposite to the management information pattern is formed on the resist provided on the stamper using laser drawing, and further etched to form the management information pattern on the stamper, and then on the magnetic recording medium. The concavo-convex pattern similar to the recording track pattern and the management information pattern is transferred to the resist provided on the recording medium, or the concavo-convex pattern similar to the recording track pattern provided on the magnetic recording medium is transferred to the resist. , Obtained by forming a concavo-convex pattern similar to the management information pattern by laser drawing using laser drawing,
The management information pattern is recorded across adjacent recording tracks.

One of the methods for producing a perpendicular magnetic recording medium of the present invention is to form a concavo-convex pattern similar to a recording track pattern, separated by at least grooves, on the master by electron beam drawing,
Using the master, after transferring a concavo-convex pattern opposite to the concavo-convex pattern similar to the recording track pattern to an imprint stamper,
After forming the recording track pattern on the resist provided on the magnetic recording layer using the imprint stamper, the production number, the control number, the production date, the production location, the manufacturer, the sales route, the storage capacity, And forming a concavo-convex pattern similar to the management information pattern represented by binarizing and expressing at least one type of management information selected from the group consisting of size and etching the surface of the magnetic recording layer together with the resist, In the method of manufacturing a magnetic recording medium for forming the recording track pattern and the management information pattern on the surface of the magnetic recording layer,
The management information pattern is recorded across adjacent recording tracks.

Alternatively, another one of the methods for producing a perpendicular magnetic recording medium of the present invention is to form a concavo-convex pattern similar to the recording track pattern separated on at least the groove on the master by electron beam drawing,
Using the master, after transferring a concavo-convex pattern opposite to the concavo-convex pattern similar to the recording track pattern to an imprint stamper,
A resist is formed on the imprint stamper, and at least one type of management information selected from the group consisting of a manufacturing number, a management number, a manufacturing date, a manufacturing location, a manufacturer, a sales route, a storage capacity, and a size is stored. A concave / convex pattern opposite to the management information pattern expressed as a value is formed by laser drawing and etching, and the recording track pattern and the management are formed on the resist provided on the magnetic recording layer using the obtained stamper. In a method of manufacturing a magnetic recording medium, the recording track pattern and the management information pattern are formed on the surface of the magnetic recording layer by transferring a concavo-convex pattern similar to the information pattern and etching the surface of the magnetic recording layer together with the resist. ,
The management information pattern is recorded across adjacent recording tracks.

  By using the present invention, in the unlikely event that a defect is found in a magnetic recording medium obtained by forming a magnetic recording layer pattern by an imprint method using a stamper, management information provided in the magnetic recording medium Can be easily traced. According to the present invention, not only the magnetic recording medium but also the master and the stamper are managed, so that the yield and quality management are greatly improved.

It is a figure showing an example of the magnetic recording / reproducing apparatus which can apply the magnetic recording medium of this invention. It is a figure for demonstrating an example of the magnetic recording medium based on this invention. It is a figure for demonstrating an example of the magnetic layer pattern used for this invention. It is a figure for demonstrating the cross-section of FIG. It is a figure for demonstrating an example of the manufacturing process of the original disk of this invention. It is a figure for demonstrating an example of the manufacturing process of the stamper for imprint of this invention. It is a figure showing the process of replicating the stamper for imprint of this invention. It is a figure for demonstrating an example of the manufacturing process of the magnetic-recording medium of this invention. It is a figure for demonstrating another example of the imprint stamper which concerns on this invention. It is a figure showing the manufacturing process of another example of the magnetic recording medium of this invention. It is a figure showing another example of the magnetic layer pattern provided in the magnetic recording medium of this invention. It is a figure showing another example of the magnetic layer pattern provided in the magnetic recording medium of this invention. It is a figure showing an example of the magnetic layer pattern which has the management information part by which the DC demagnetization was carried out. It is a figure showing an example of the magnetic layer pattern which has the management information part which performed AC demagnetization. It is a figure showing another example of the magnetic layer pattern which has the management information part by which the DC demagnetization was carried out. It is a figure showing another example of the magnetic layer pattern which has the management information part which gave AC demagnetization.

  The magnetic recording medium of the present invention includes a nonmagnetic substrate and a magnetic recording layer formed on the nonmagnetic substrate, and the magnetic recording layer has at least a recording track pattern and a management information pattern separated by grooves.

  The recording track pattern and the management information pattern are formed by a magnetic layer on a nonmagnetic substrate.

  Further, here, the management information pattern used in the present invention is at least one type of management information selected from a manufacturing number, a management number, a manufacturing date, a manufacturing place, a manufacturer, a sales route, a storage capacity, and a size. This is a binary representation. This management information pattern can be composed of a plurality of magnetic layers separated from each other.

  According to the present invention, in the unlikely event that a defect is found in the manufactured magnetic recording medium, by reading the management information pattern provided in the magnetic recording layer, it is possible to easily remove the master and the stamper that are the cause. Can be tracked.

  Since the management information used in the present invention is binarized, it can be easily read using a normal reading head.

  The management information pattern is preferably provided in the reproducible area. Thus, reading can be easily performed using the reproducing head in the magnetic recording / reproducing apparatus.

  Further, an AC demagnetized pattern can be used as the management information pattern used in the present invention. By using an AC demagnetized pattern, only authorized persons can be set to read the management information, so that confidentiality can be maintained.

  In the magnetic recording medium of the present invention, the magnetic recording layer can be preferably formed by imprinting using a stamper. In this method, the concave / convex shape can be physically and easily transferred by simply pressing a stamper on a member for patterning the magnetic recording layer, for example, a resist, without using a complicated process or apparatus.

  In the magnetic recording medium of the present invention, the management information pattern can be formed in the same process as the recording track pattern or in a different process. When the management information pattern differs for each magnetic recording medium to be manufactured, at least the recording track pattern can be formed by an imprint method using a stamper, and the management information pattern can be formed by another method. On the other hand, when the management information pattern is information common to the magnetic recording medium to be manufactured, by forming both the recording track pattern and the management information pattern by the imprint method using a stamper, the pattern can be further increased in other processes. The number of pattern forming steps can be reduced and the cost can be reduced compared to forming the pattern.

  The imprint stamper according to the present invention is a stamper that is preferably used for forming the magnetic recording layer of the magnetic recording medium with the number of pattern forming steps reduced as much as possible, and is a recording separated by grooves. The track pattern has a concavo-convex pattern opposite to the concavo-convex pattern on the surface of the management information pattern.

  When the imprint stamper of the present invention is used, since the concave / convex pattern opposite to the recording track pattern and the concave / convex pattern opposite to the management information pattern are formed in advance, the management information is formed in the same process as the recording track pattern formation. A pattern can be formed.

  In the imprint stamper of the present invention, the concave / convex pattern opposite to the management information pattern can be formed separately from the formation of the concave / convex pattern opposite to the recording track pattern. It is desirable that the number of processes is small.

  The master of the present invention is a master suitably used for forming the imprint stamper by reducing the number of pattern forming steps as much as possible, and has the same uneven pattern as the management information pattern of the magnetic recording layer And a concave-convex pattern similar to the recording track pattern.

  Since the master of the present invention is provided with a concave / convex pattern similar to the management information pattern in addition to the concave / convex pattern similar to the recording track pattern, when the master of the present invention is used, the concave / convex pattern opposite to the recording track pattern is provided. In the same process as the formation, an uneven pattern opposite to the management information pattern can be formed on the imprint stamper.

  Hereinafter, the present invention will be specifically described with reference to the drawings.

  FIG. 1 shows an example of a magnetic recording / reproducing apparatus to which the magnetic recording medium of the present invention can be applied.

  In this magnetic recording / reproducing apparatus, a disk-shaped magnetic recording medium 71, a head slider 76 including a magnetic head, and a head suspension assembly (suspension 75 and actuator arm 74) that support the head slider 76 are provided inside a housing 70. And a voice coil motor (VCM) 77 and a circuit board.

  The magnetic recording medium 71 is attached to a spindle motor 72 and rotated, and various digital data are recorded by a perpendicular magnetic recording method. The magnetic head incorporated in the head slider 76 is a so-called composite head, and includes a single magnetic pole structure write head and a read head using a shield type MR reproducing element (GMR film, TMR film, etc.). A suspension 75 is held at one end of the actuator arm 74, and the head slider 76 is supported by the suspension 75 so as to face the recording surface of the magnetic recording medium 71. The actuator arm 74 is attached to the pivot 73. A voice coil motor (VCM) 77 is provided at the other end of the actuator arm 74. A head suspension assembly is driven by a voice coil motor (VCM) 77 to position the magnetic head at an arbitrary radial position of the magnetic recording medium 71. The circuit board includes a head IC, and generates a drive signal for a voice coil motor (VCM), a control signal for controlling reading and writing by the magnetic head, and the like.

  FIG. 2 is a diagram for explaining an example of the magnetic recording medium according to the present invention.

  The magnetic recording medium 71 is a so-called discrete track medium, in which a magnetic recording layer formed on a substrate includes a magnetic layer having a predetermined pattern, and data including a magnetic layer pattern forming a recording track in the plane of the magnetic layer. An area 61, a servo area 62 including a magnetic layer pattern used as an address bit and formed between the data areas along the track length direction, and a management information area 63 provided on the inner circumference side of the recording track, for example, Including. These magnetic layer patterns are separated by grooves.

  Further, an underlayer can be provided between the substrate and the magnetic recording layer as necessary.

  As the magnetic recording layer, a perpendicular magnetic recording layer can be preferably used.

  FIG. 3 is a view for explaining an example of the magnetic layer pattern used in the present invention, and FIG. 4 is a view for explaining the sectional structure thereof.

  As shown in FIG. 3, servo areas 20 and data areas 30 are alternately formed along the circumferential direction. The servo area 20 includes areas such as a preamble section 21, an address section 22, and a positioning burst section 23, each formed by a magnetic layer pattern. In addition to these regions, a gap portion may be included, and the order and arrangement of the regions may be different. In the data area 30, recording tracks 31 made of magnetic layer patterns and guard bands 32 made of grooves or nonmagnetic layers are alternately formed along the radial direction. A management information section 33 is formed between the tracks 31. For the sake of convenience, in the micro range as shown in FIG. 3, the radial direction and the circumferential direction are shown to be generally orthogonal, but the servo area is the actuator arm of the head slider when viewed from the whole magnetic disk. In correspondence with the trajectory, an arc shape can be formed as in the servo area 62 shown in FIG. Further, the pattern of the magnetic layer may be different depending on the radial position.

  5 to 8 are views for explaining an example of the manufacturing process of the magnetic recording medium of the present invention.

  First, a method for forming an example of the master disk of the present invention will be described with reference to FIGS. 5 (A) to 5 (C).

  As shown in FIG. 5A, for example, an 8-inch diameter Si wafer 1 can be prepared, and the surface thereof can be treated with, for example, hexamethyldisilazane (HMDS). On the other hand, for example, resist ZEP-520 manufactured by Nippon Zeon Co., Ltd. is diluted twice with anisole and filtered through a 0.2 μm membrane filter to obtain a resist solution. A resist solution is spin-coated on the Si wafer 1 and then pre-baked at 200 ° C. for 3 minutes, for example, to form a resist 2 having a thickness of about 0.1 μm, for example.

  As shown in FIG. 5B, a desired pattern is formed on the resist 2 on the Si wafer 1 using an electron beam lithography apparatus having a ZrO / W thermal field emission type electron gun emitter, for example, under the condition of an acceleration voltage of 50 kV. Can be drawn directly. During drawing, a signal for forming a servo pattern, burst pattern, address pattern, track pattern, and management information pattern, a signal sent to the stage drive system of the drawing apparatus, and an electron beam deflection control signal are generated in synchronization. A signal source can be used. During drawing, for example, the stage can be rotated at a linear velocity of CLV (Constant Linear Velocity) of 700 mm / s, and the stage can also be moved in the radial direction. In addition, it is possible to draw a concentric track area by deflecting the electron beam every rotation. The magnetic signal pattern can be exposed in a radius range of 4 mm to 10.3 mm, and an alignment mark, a recognition mark, and a character pattern can be exposed inside and outside thereof. After exposure, the resist 2 is developed by immersing the Si wafer substrate in a developer such as ZED-N50 (manufactured by Nippon Zeon Co., Ltd.) for 90 seconds, for example, while rotating the Si wafer substrate at 500 rpm with a spin coater. For example, the resist master 5 having a concavo-convex pattern as shown in FIG. 5C is obtained by immersing in (manufactured by Nippon Zeon Co., Ltd.) for 90 seconds for rinsing and then drying by air blow. This concavo-convex pattern has the same concavo-convex pattern as the magnetic layer pattern of the magnetic recording medium to be formed.

  Next, a method for forming an example of an imprint stamper according to the present invention will be described with reference to FIGS. 6 (A) to 6 (C).

  As shown in FIG. 6A, a conductive film 6 made of, for example, Ni can be formed on the resist master 5 by sputtering. Specifically, after using pure nickel as a target and evacuating to 8 × 10 −3 Pa, sputtering was performed for 40 seconds by applying DC power of 400 W in a chamber in which argon gas was introduced and the pressure was adjusted to 1 Pa. The conductive film 6 having a thickness of about 30 nm can be formed.

  As shown in FIG. 6B, the resist master 5 with the conductive film 6 is immersed in, for example, a nickel sulfamate plating solution (NS-160, manufactured by Showa Chemical Co., Ltd.), for example, Ni electroformed for 75 minutes. Thus, the electroformed film 7 having a thickness of about 300 μm can be formed. An example of the electroforming bath conditions is as follows.

Nickel sulfamate: 600 g / L
Boric acid: 40 g / L
Surfactant (sodium lauryl sulfate): 0.15 g / L
Liquid temperature: 55 ° C
pH: 4.0
Current density: 20 A / dm2.

  As shown in FIG. 6C, the electroformed film 7 and the conductive film 6 can be peeled off from the resist master 5 with a resist residue attached. For example, the resist residue can be removed by oxygen plasma ashing. Specifically, for example, plasma ashing can be performed for 20 minutes by applying a power of 100 W in a chamber in which oxygen gas is introduced at 100 ml / min and the pressure is adjusted to 4 Pa. In this way, a father stamper having an uneven pattern obtained by inverting the uneven pattern of the resist master 5 and including the conductive film 6 and the electroformed film 7 is obtained. Thereafter, an imprint stamper 8 is obtained by punching out unnecessary portions of the father stamper with a metal blade. The stamper 8 has, for example, a pattern in which the pattern shown in FIGS. 3 and 4 and the uneven shape thereof are reversed.

  Of course, the father stamper thus obtained can be used as an imprint stamper. However, the stamper can be mass-replicated by repeating the electroforming process as described below.

  FIGS. 7A to 7G are diagrams showing a process of duplicating an imprint stamper using the father stamper.

  First, a father stamper 41 as shown in FIG.

  As shown in FIG. 7B, for example, a power of 200 W is applied to the uneven pattern surface of the father stamper 41 for 3 minutes as in the step of removing the resist residue shown in FIG. 6C. Thus, the oxide film 42 can be formed by passivation by an oxygen plasma ashing method. Note that an anodic oxidation method performed by a wet treatment can be substituted for the passivation by the oxygen plasma ashing method.

  Thereafter, as shown in FIG. 7C, in the same manner as the electroforming film forming step shown in FIG. 6B, the upper surface of the father stamper 41 is interposed through the oxide film 42 under the same electroforming bath conditions. Then, the nickel electroformed film 43 can be formed. The thickness of the electroformed film may be 300 μm as in the case of the father stamper, but it can be made thicker or thinner by about 100 μm to distinguish it from the father stamper.

  Thereafter, as shown in FIG. 7D, the electroformed film 43 is peeled from the father stamper 41 to obtain a mother stamper which is an inverted type of the father stamper.

  By repeating the step of obtaining the mother stamper from the father stamper, for example, ten or more mother stampers having the same shape can be obtained.

  Thereafter, similar to the procedure for obtaining the mother stamper 43 from the father stamper 41, as shown in FIG. 7E, an oxide film 44 is passivated on the surface of the mother stamper 43, and further, as shown in FIG. 7F. In addition, by forming and peeling the electroformed film 44, as shown in FIG. 7G, a sun stamper 45 having the same concave and convex pattern shape as the father stamper 41 can be obtained. For example, 100 or more sun stampers can be formed using the 10 or more mother stampers having the same shape. In this manner, a large number of stampers can be duplicated from a single master, and a magnetic recording medium can be mass-produced. Since drawing a pattern on the resist master may require a lot of time, a magnetic recording medium can be manufactured with a high yield by replicating a large amount of stampers.

  FIG. 8A to FIG. 8F are diagrams showing steps of manufacturing an example of the magnetic recording medium of the present invention using the imprint stamper.

  As shown in FIG. 8A, the stamper 8 is ultrasonically cleaned using, for example, acetone for 15 minutes. In order to improve releasability during imprinting, the stamper 8 can be subjected to the following processing. For example, a solution of fluoroalkylsilane CF3 (CF2) 7CH2CH2Si (OMe) 3 (GE Toshiba Silicone Co., Ltd., TSL8233) diluted to 5% with ethanol can be prepared. The stamper 8 is immersed in the obtained solution for 30 minutes, and after the solution is blown off with a blower, annealing can be performed at 120 ° C. for 1 hour.

  On the other hand, the magnetic recording layer 12 can be formed by sputtering on the disk substrate 11 made of, for example, 0.85 inch diameter donut glass. A resist 15 (Rohm and Haas, S1801) can be spin-coated on the magnetic recording layer 12 at a rotational speed of 4000 rpm.

  As shown in FIG. 8B, the stamper 8 can be transferred to the resist 15 by pressing the stamper 8 against the resist 15 on the surface of the disk substrate 11 and pressing at 1800 bar for 1 minute, for example. After the resist 15 having the pattern transferred thereon is irradiated with UV for 5 minutes, it can be baked at 160 ° C. for 30 minutes. In such a concavo-convex formation process by imprinting, a resist residue may remain on the bottom of the pattern concave portion.

  As shown in FIG. 8C, the resist residue at the bottom of the pattern recess can be removed by, for example, RIE using oxygen gas. As shown in FIG. 8D, the magnetic recording layer 12 is etched by Ar ion milling, for example, using the pattern of the resist 15 as a mask. As shown in FIG. 8E, the pattern of the resist 15 can be removed by oxygen RIE.

  Thereafter, a carbon protective layer 13 can be formed on the entire substrate surface including the etched magnetic recording layer 12. Then, a magnetic recording medium as shown in FIG. 8F can be obtained by applying a lubricant (not shown) to the manufactured magnetic disk. Here, the concave portion of the stamper 8 shown in FIG. 8A corresponds to the magnetic portion of the convex portion in the medium shown in FIG.

  Further, the concave portion of the magnetic recording layer can be flattened using a nonmagnetic layer, if necessary.

  In the method for forming an example of the imprint stamper shown in FIGS. 6A to 6C, an example is shown in which a master having a concavo-convex pattern similar to the pattern of the magnetic layer of the magnetic recording medium is used. However, the printing stamper of the present invention can be formed using another process even if the pattern corresponding to the management information pattern is not formed on the master.

  9A to 9E are views for explaining another example of the imprint stamper according to the present invention.

  As shown in FIG. 9A, a stamper body 51 having a concavo-convex pattern obtained by inverting the recording track pattern is prepared.

  Next, as shown in FIG. 9B, a photoresist layer 52 on which a photoresist can be applied can be formed on the stamper body 51. Thereafter, management information can be written into the photoresist layer 52 using laser drawing.

  Then, by performing development processing, as shown in FIG. 9C, unevenness information obtained by inverting the unevenness pattern on the surface of the management information pattern can be formed in the resist layer 52.

  Further, as shown in FIG. 9D, by subjecting the developed stamper body to milling, the exposed and developed portions of the stamper body surface and the resist layer 52 are partly formed. It can be etched. As a result, the management information is transferred as the uneven shape of the stamper.

  Further, the pattern of the resist layer 52 can be removed by, for example, oxygen RIE. In the obtained stamper, as shown in FIG. 9E, a recording track portion 53 and a management information portion 54 can be formed.

  Further, in the manufacturing method of an example of the magnetic recording medium shown in FIGS. 8A to 8F, an example in which a stamper having a concavo-convex pattern formed by inverting the concavo-convex pattern of the magnetic layer pattern of the magnetic recording medium is used. However, in the magnetic recording medium of the present invention, the management information pattern can be formed by another process even if the pattern corresponding to the management information pattern is not formed on the stamper.

  FIGS. 10A to 10D are views showing manufacturing steps of another example of the magnetic recording medium of the present invention.

  First, in the same manner as in the steps shown in FIGS. 8A and 8B, for example, a novolac-type photoresist is applied to the surface of the magnetic recording layer 83 provided on the substrate 84, and the obtained resist 82 is formed. By pressing the stamper 81, the uneven pattern of the stamper 81 can be transferred to the resist 82 as shown in FIG.

  Next, management information can be written on the resist 82 to which the stamper pattern has been transferred, using laser drawing. By developing after laser exposure, an uneven management information pattern can be formed on the resist 82 as shown in FIG.

  Thereafter, similarly to the steps shown in FIGS. 8C and 8D, after removing the residue of the resist 82 by RIE using, for example, oxygen gas, Ar ion milling is performed, for example, to perform FIG. As shown in C), the magnetic recording layer 83 can be etched.

  Further, if necessary, a nonmagnetic layer 85 is formed by applying SOG (spin-on-glass) to the recesses and then vitrifying, and a protective film 86 and a lubricating layer (not shown) are formed. Thus, a magnetic recording medium as shown in FIG.

  In this way, when the management information pattern is formed later on the stamper or magnetic recording medium to which the pattern for the recording track is transferred without using the master, using the photoresist and laser drawing, the laser drawing width is Since the recording track width is usually wider than about 300 nm or less, the management information pattern finally provided on the magnetic recording medium is wider than the recording track or has a configuration extending over a plurality of recording tracks.

  FIG. 11 shows another example of the magnetic layer pattern provided on the magnetic recording medium of the present invention.

  This magnetic layer pattern includes a data area 87 and a management information area 88 provided on the inner circumference side of the data area 87, and further servo areas (not shown) formed alternately with the data areas 87 along the circumferential direction. Have In this magnetic pattern, the width of the management information pattern 89 is larger than the width of each recording track 90.

  Thus, when the track width is wide, there is an advantage that the head can be easily positioned and the management information can be easily accessed. FIG. 12 shows still another example of the magnetic layer pattern provided on the magnetic recording medium of the present invention.

  This magnetic layer pattern includes a data area 57 and a management information area 58 provided on the inner circumference side of the data area 57, and further servo areas (not shown) formed alternately with the data areas 57 along the circumferential direction. Have In this magnetic pattern, a management information pattern 56 is formed across a plurality of recording track patterns 55. In such a case, even if the management information of one track is not readable due to a defect of a magnetic material, the management information of another track can be read, which is advantageous in that it is resistant to errors.

  In the magnetic recording medium of the present invention, the management information section can be demagnetized so that it cannot be accessed by general users.

  An example of a magnetic layer pattern having a management information portion that has been demagnetized by DC is shown in FIG.

  In FIG. 13, management information 98 is described for one track, and a part of servo information 97 for accessing the management information 98 is also illustrated. In the case of FIG. 13, the information is recorded by the nonmagnetic material 92. 91 is a magnetic body. FIG. 13 shows a state where the DC is demagnetized. That is, all the portions of the magnetic body 91 face one direction. Therefore, the magnetic flux changes at the position of the non-magnetic material 92 and can be read as magnetic information from the head.

  An example of a magnetic layer pattern having a management information part subjected to AC demagnetization is shown in FIG.

  The state shown in FIG. 14 is obtained by writing an AC signal equal to or smaller than the minimum bit length of recorded information to the state shown in FIG. Reference numeral 93 denotes an inversion magnetic domain by the written AC signal. By doing so, the signal from both the AC signal and the non-magnetic part is reproduced on the reproducing head, and thus information cannot be read. Before that, the servo signal cannot be read properly, so even tracking is impossible. As described above, when the management information is unnecessary information for a general user, it can be prevented from being read. In order to read this, a person with management authority, such as a person who can access the firmware such as the manufacturer, may demagnetize the management information portion.

  In FIG. 14, for the sake of convenience, a clear AC state is recorded. However, since it is intended to prevent reading, it is not actually necessary to have a clear AC signal as shown. It can be a so-called labyrinth magnetic domain.

  FIG. 15 shows another example of a magnetic layer pattern having a management information part that has been DC demagnetized. FIG. 15 is the same as FIG. 13 except that the management information is recorded by the magnetic part. Reference numerals 94 and 95 denote a non-magnetic material and a magnetic material, respectively.

  The state shown in FIG. 16 is obtained by writing an AC signal equal to or smaller than the minimum bit length of recorded information to the state shown in FIG. In this state, since the magnetic part is AC demagnetized, a sufficient magnetic flux cannot be generated therefrom. Alternatively, some bits generate magnetic flux, but some bits have no magnetic flux. Therefore, in the same manner as described above, not only information cannot be read but also tracking cannot be performed. In FIG. 16, the AC demagnetized magnetic domains are arranged in an orderly manner, but this is only an example and can be formed randomly.

  Hereinafter, materials used for each layer of the magnetic recording medium according to the embodiment of the present invention and a laminated structure of each layer will be described.

<Board>
As the substrate, for example, a glass substrate, an Al alloy substrate, a ceramic substrate, a carbon substrate, a compound semiconductor substrate, a Si single crystal substrate, or the like can be used. Amorphous glass or crystallized glass can be used for the glass substrate. Examples of the amorphous glass include soda lime glass and aluminosilicate glass. Examples of crystallized glass include lithium-based crystallized glass. As the ceramic substrate, a sintered body mainly composed of aluminum oxide, aluminum nitride, silicon nitride or the like, or a fiber reinforced one of these sintered bodies can be used. Examples of the compound semiconductor substrate include GaAs and AlGaAs. The Si single crystal substrate, so-called silicon wafer, may have an oxide film on the surface.

<Soft magnetic underlayer>
When producing a perpendicular magnetic recording medium, a so-called perpendicular double-layer medium having a perpendicular magnetic recording layer on a soft magnetic underlayer (SUL) is used. The soft magnetic underlayer of the perpendicular double-layer medium is provided in order to pass the recording magnetic field from the recording magnetic pole and to return the recording magnetic field to the return yoke disposed in the vicinity of the recording magnetic pole. That is, the soft magnetic underlayer plays a part of the function of the recording head and plays a role of improving the recording efficiency by applying a steep vertical magnetic field to the recording layer.

  For the soft magnetic underlayer, a high magnetic permeability material containing at least one of Fe, Ni, and Co is used. Such materials include FeCo alloys such as FeCo and FeCoV, FeNi alloys such as FeNi, FeNiMo, FeNiCr and FeNiSi, FeAl alloys and FeSi alloys such as FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, FeAlO, and FeTa alloys such as Examples thereof include FeZr alloys such as FeTa, FeTaC, and FeTaN, such as FeZrN.

  For the soft magnetic underlayer, a material having a fine crystal structure such as FeAlO, FeMgO, FeTaN, FeZrN or the like containing Fe at 60 at% or more or a granular structure in which fine crystal particles are dispersed in a matrix can be used.

  As another material of the soft magnetic underlayer, a Co alloy containing Co and at least one of Zr, Hf, Nb, Ta, Ti, and Y can be used. Co is preferably contained at 80 at% or more. When such a Co alloy is formed by sputtering, an amorphous layer is easily formed. Amorphous soft magnetic materials do not have magnetocrystalline anisotropy, crystal defects, and grain boundaries, and thus exhibit very excellent soft magnetism. Further, by using an amorphous soft magnetic material, it is possible to reduce the noise of the medium. Suitable examples of the amorphous soft magnetic material include CoZr, CoZrNb, and CoZrTa-based alloys.

  An underlayer may be further provided under the soft magnetic underlayer in order to improve the crystallinity of the soft magnetic underlayer or the adhesion to the substrate. As the underlayer material, Ti, Ta, W, Cr, Pt, alloys containing these, or oxides or nitrides thereof can be used.

  An intermediate layer made of a non-magnetic material may be provided between the soft magnetic underlayer and the perpendicular magnetic recording layer. The role of the intermediate layer is to block the exchange coupling interaction between the soft magnetic underlayer and the recording layer and to control the crystallinity of the recording layer. As the intermediate layer material, Ru, Pt, Pd, W, Ti, Ta, Cr, Si, an alloy containing these, or an oxide or nitride thereof can be used.

  In order to prevent spike noise, the soft magnetic underlayer may be divided into a plurality of layers and antiferromagnetically coupled by sandwiching Ru having a thickness of 0.5 to 1.5 nm. Alternatively, the soft magnetic layer and a pinning layer made of a hard magnetic film having in-plane anisotropy such as CoCrPt, SmCo, or FePt or an antiferromagnetic material such as IrMn or PtMn may be exchange-coupled. In this case, in order to control the exchange coupling force, a magnetic layer such as Co or a nonmagnetic layer such as Pt may be laminated on the upper and lower sides of the Ru layer.

<Perpendicular magnetic recording layer>
For the perpendicular magnetic recording layer, for example, a material containing Co as a main component, containing at least Pt, optionally containing Cr, and further containing an oxide (for example, silicon oxide or titanium oxide) is used. In the perpendicular magnetic recording layer, the magnetic crystal grains preferably have a columnar structure. In the perpendicular magnetic recording layer having such a structure, the orientation and crystallinity of the magnetic crystal grains are good, and as a result, a signal / noise ratio (S / N ratio) suitable for high-density recording can be obtained. In order to obtain the above structure, the amount of oxide is important. The content of the oxide is preferably 3 mol% or more and 12 mol% or less, and more preferably 5 mol% or more and 10 mol% or less with respect to the total amount of Co, Pt, and Cr. When the content of the oxide in the perpendicular magnetic recording layer is in the above range, the oxide is precipitated around the magnetic particles, and the magnetic particles can be isolated and refined. When the content of the oxide exceeds the above range, the oxide remains in the magnetic particles, the orientation and crystallinity of the magnetic particles are impaired, and further, oxides are deposited above and below the magnetic particles. As a result, the magnetic particles However, a columnar structure penetrating the perpendicular magnetic recording layer vertically is not formed. On the other hand, when the oxide content is less than the above range, isolation and miniaturization of the magnetic particles are insufficient, resulting in an increase in noise during recording and reproduction, and a signal / noise ratio suitable for high density recording ( (S / N ratio) cannot be obtained.

  The Pt content in the perpendicular magnetic recording layer is preferably 10 at% or more and 25 at% or less. When the Pt content is in the above range, the uniaxial magnetic anisotropy constant Ku necessary for the perpendicular magnetic recording layer can be obtained, and the crystallinity and orientation of the magnetic particles are improved, which is suitable for high density recording as a result. Thermal fluctuation characteristics and recording / reproduction characteristics can be obtained. When the Pt content exceeds the above range, a layer having an fcc structure is formed in the magnetic particles, and the crystallinity and orientation may be impaired. On the other hand, if the Pt content is less than the above range, Ku suitable for high density recording, and hence thermal fluctuation characteristics, cannot be obtained.

  The Cr content in the perpendicular magnetic recording layer is preferably 0 at% or more and 16 at% or less, and more preferably 10 at% or more and 14 at% or less. When the Cr content is in the above range, high magnetization can be maintained without lowering the uniaxial magnetic anisotropy constant Ku of the magnetic particles, and as a result, recording / reproducing characteristics suitable for high-density recording and sufficient thermal fluctuation characteristics can be obtained. . When the Cr content exceeds the above range, the Ku of the magnetic particles is reduced, so that the thermal fluctuation characteristics are deteriorated, and the crystallinity and orientation of the magnetic particles are deteriorated. As a result, the recording / reproducing characteristics are deteriorated.

  The perpendicular magnetic recording layer contains one or more additive elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Pt, Cr, and oxide. You may go out. By including these additive elements, it is possible to promote miniaturization of magnetic particles or improve crystallinity and orientation, and to obtain recording / reproduction characteristics and thermal fluctuation characteristics suitable for higher density recording. it can. The total content of these additive elements is preferably 8 at% or less. If it exceeds 8 at%, phases other than the hcp phase are formed in the magnetic particles, so that the crystallinity and orientation of the magnetic particles are disturbed, resulting in recording / reproduction characteristics and thermal fluctuation characteristics suitable for high-density recording. It becomes impossible.

  Other materials for the perpendicular magnetic recording layer include CoPt alloys, CoCr alloys, CoPtCr alloys, CoPtO, CoPtCrO, CoPtSi, and CoPtCrSi. For the perpendicular magnetic recording layer, a multilayer film of Co and an alloy mainly composed of at least one selected from the group consisting of Pt, Pd, Rh, and Ru can be used. In addition, a multilayer film such as CoCr / PtCr, CoB / PdB, or CoO / RhO to which Cr, B, or O is added can be used for each layer of these multilayer films.

  The thickness of the perpendicular magnetic recording layer is preferably 5 to 60 nm, and more preferably 10 to 40 nm. A perpendicular magnetic recording layer having a thickness in this range is suitable for high recording density. If the thickness of the perpendicular magnetic recording layer is less than 5 nm, the reproduction output tends to be too low and the noise component tends to be higher. On the other hand, if the thickness of the perpendicular magnetic recording layer exceeds 40 nm, the reproduction output tends to be too high and the waveform tends to be distorted. The coercive force of the perpendicular magnetic recording layer is preferably 237000 A / m (3000 Oe) or more. When the coercive force is less than 237000 A / m (3000 Oe), the thermal fluctuation resistance tends to be inferior. The perpendicular squareness ratio of the perpendicular magnetic recording layer is preferably 0.8 or more. When the vertical squareness ratio is less than 0.8, the thermal fluctuation resistance tends to be inferior.

<Protective layer>
The protective layer functions to prevent corrosion of the perpendicular magnetic recording layer and to prevent damage to the medium surface when the magnetic head comes into contact with the medium. Examples of the material for the protective layer include materials containing C, SiO2, and ZrO2. The thickness of the protective layer is preferably 1 to 10 nm. When the thickness of the protective layer is in the above range, the distance between the head and the medium can be reduced, which is suitable for high density recording.

<Lubrication layer>
As the lubricant, for example, perfluoropolyether, fluorinated alcohol, fluorinated carboxylic acid and the like can be used.

  According to the master of the present invention, the master pattern corresponding to the management information pattern can be formed in the same process as the master pattern corresponding to the recording track pattern at the time of manufacture, so there is no need to add further processes. , Low cost.

  According to the imprint stamper of the present invention, the stamper concave / convex pattern corresponding to the management information pattern can be formed in the same process as the stamper concave / convex pattern corresponding to the recording track pattern. There is no need to do this, and the cost is low.

  Furthermore, according to the magnetic recording medium of the present invention, when physical transfer is performed by an imprint method using a stamper at the time of manufacturing the magnetic recording layer, at least a concave / convex pattern of a stamper corresponding to a management information pattern, and a recording track Since the concave / convex pattern of the stamper corresponding to both of the patterns can be simultaneously transferred by one stamper, it is not necessary to add a further process and the cost is low.

[Appendix 1. ]
A non-magnetic substrate, and a magnetic recording layer formed on the non-magnetic substrate,
The magnetic recording layer is at least one selected from the group consisting of a recording track pattern separated by at least grooves, a manufacturing number, a control number, a manufacturing date, a manufacturing location, a manufacturer, a sales route, a storage capacity, and a size. Management information pattern that binarizes and represents management information of
The magnetic recording medium is characterized in that the management information pattern is recorded across adjacent recording tracks.

[Appendix 2. ]
The magnetic recording medium according to claim 1, wherein the management information pattern is AC demagnetized.

[Appendix 3. ]
The magnetic recording medium according to claim 1, wherein the management information pattern is provided in a reproducible area.

[Appendix 4. ]
The recording track pattern and the management information pattern are:
Formed by subjecting the surface of the magnetic recording layer and a resist provided on the surface of the magnetic recording layer, having a concave and convex pattern similar to the recording track pattern and the management information pattern, to etching;
A resist having a concavo-convex pattern similar to the recording track pattern and the management information pattern,
After transferring the concavo-convex pattern similar to the recording track pattern formed on the master by electron beam drawing to an imprint stamper, and forming the concavo-convex pattern opposite to the recording track pattern,
A concave / convex pattern opposite to the management information pattern is formed on the resist provided on the stamper using laser drawing, and further etched to form the management information pattern on the stamper, and then on the magnetic recording medium. The concavo-convex pattern similar to the recording track pattern and the management information pattern is transferred to the resist provided on the recording medium, or the concavo-convex pattern similar to the recording track pattern provided on the magnetic recording medium is transferred to the resist. 4. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is obtained by forming a concavo-convex pattern similar to the management information pattern by laser drawing using laser drawing. 5.

[Appendix 5. ]
A concave / convex pattern similar to the recording track pattern separated by at least grooves is formed on the master by electron beam drawing,
Using the master, after transferring a concavo-convex pattern opposite to the concavo-convex pattern similar to the recording track pattern to an imprint stamper,
After forming the recording track pattern on the resist provided on the magnetic recording layer using the imprint stamper, the production number, the control number, the production date, the production location, the manufacturer, the sales route, the storage capacity, And forming a concavo-convex pattern similar to the management information pattern represented by binarizing and expressing at least one type of management information selected from the group consisting of size and etching the surface of the magnetic recording layer together with the resist, In the method of manufacturing a magnetic recording medium for forming the recording track pattern and the management information pattern on the surface of the magnetic recording layer,
The method of manufacturing a magnetic recording medium, wherein the management information pattern is recorded across adjacent recording tracks.

[Appendix 6. ]
A concave / convex pattern similar to the recording track pattern separated by at least grooves is formed on the master by electron beam drawing,
Using the master, after transferring a concavo-convex pattern opposite to the concavo-convex pattern similar to the recording track pattern to an imprint stamper,
A resist is formed on the imprint stamper, and at least one type of management information selected from the group consisting of a manufacturing number, a management number, a manufacturing date, a manufacturing location, a manufacturer, a sales route, a storage capacity, and a size is stored. A concave / convex pattern opposite to the management information pattern expressed as a value is formed by laser drawing and etching, and the recording track pattern and the management are formed on the resist provided on the magnetic recording layer using the obtained stamper. In a method of manufacturing a magnetic recording medium, the recording track pattern and the management information pattern are formed on the surface of the magnetic recording layer by transferring a concavo-convex pattern similar to the information pattern and etching the surface of the magnetic recording layer together with the resist. ,
The method of manufacturing a magnetic recording medium, wherein the management information pattern is recorded across adjacent recording tracks.

[Appendix 7. ]
The method according to claim 5 or 6, wherein the management information pattern is AC demagnetized.

[Appendix 8. ]
The method according to claim 5, wherein the management information pattern is provided in a reproducible area.

  5 ... resist master, 8 ... imprint stamper, 11 ... disk substrate, 12 ... magnetic recording layer, 15 ... resist, 20, 62 ... servo area, 21 ... preamble part, 22 ... address part, 23, 33 ... positioning burst Part, 30, 61 ... data area, 31 ... recording track, 32 ... guard band, 41 ... father stamper, 52 ... photoresist layer, 43 ... mother stamper, 45 ... sun stamper, 53, 57 ... recording track part, 54, 58 ... Management information section, 70 ... Housing, 71 ... Magnetic recording medium, 76 ... Head slider

Claims (5)

A non-magnetic substrate, and a magnetic recording layer formed on the non-magnetic substrate,
The magnetic recording layer is at least one selected from the group consisting of a recording track pattern separated by at least grooves, a manufacturing number, a control number, a manufacturing date, a manufacturing location, a manufacturer, a sales route, a storage capacity, and a size. Management information pattern that binarizes and represents management information of
The recording track pattern and the management information pattern are:
Formed by subjecting the surface of the magnetic recording layer and a resist provided on the surface of the magnetic recording layer, having a concave and convex pattern similar to the recording track pattern and the management information pattern, to etching;
A resist having a concavo-convex pattern similar to the recording track pattern and the management information pattern,
After transferring the concavo-convex pattern similar to the recording track pattern formed on the master by electron beam drawing to an imprint stamper, and forming the concavo-convex pattern opposite to the recording track pattern,
A concave / convex pattern opposite to the management information pattern is formed on the resist provided on the stamper using laser drawing, and further etched to form the management information pattern on the stamper, and then on the magnetic recording medium. The concavo-convex pattern similar to the recording track pattern and the management information pattern is transferred to the resist provided on the recording medium, or the concavo-convex pattern similar to the recording track pattern provided on the magnetic recording medium is transferred to the resist. , Obtained by forming a concavo-convex pattern similar to the management information pattern by laser drawing using laser drawing,
The perpendicular magnetic recording medium, wherein the management information pattern is recorded across adjacent recording tracks.   The perpendicular magnetic recording medium according to claim 1, wherein the management information pattern is AC demagnetized. A concave / convex pattern similar to the recording track pattern separated by at least grooves is formed on the master by electron beam drawing,
Using the master, after transferring a concavo-convex pattern opposite to the concavo-convex pattern similar to the recording track pattern to an imprint stamper,
After forming the recording track pattern on the resist provided on the magnetic recording layer using the imprint stamper, the production number, the control number, the production date, the production location, the manufacturer, the sales route, the storage capacity, And forming a concavo-convex pattern similar to the management information pattern represented by binarizing and expressing at least one type of management information selected from the group consisting of size and etching the surface of the magnetic recording layer together with the resist, In the method of manufacturing a magnetic recording medium for forming the recording track pattern and the management information pattern on the surface of the magnetic recording layer,
The method of manufacturing a perpendicular magnetic recording medium, wherein the management information pattern is recorded across adjacent recording tracks. A concave / convex pattern similar to the recording track pattern separated by at least grooves is formed on the master by electron beam drawing,
Using the master, after transferring a concavo-convex pattern opposite to the concavo-convex pattern similar to the recording track pattern to an imprint stamper,
A resist is formed on the imprint stamper, and at least one type of management information selected from the group consisting of a manufacturing number, a management number, a manufacturing date, a manufacturing location, a manufacturer, a sales route, a storage capacity, and a size is stored. A concave / convex pattern opposite to the management information pattern expressed as a value is formed by laser drawing and etching, and the recording track pattern and the management are formed on the resist provided on the magnetic recording layer using the obtained stamper. In a method of manufacturing a magnetic recording medium, the recording track pattern and the management information pattern are formed on the surface of the magnetic recording layer by transferring a concavo-convex pattern similar to the information pattern and etching the surface of the magnetic recording layer together with the resist. ,
The method of manufacturing a perpendicular magnetic recording medium, wherein the management information pattern is recorded across adjacent recording tracks.   5. The method according to claim 3, wherein the management information pattern is AC demagnetized.

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