JP2008234774A - Patterned medium, manufacturing method of patterned medium and magnetic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a patterned medium with higher density than before, to provide a manufacturing method of the patterned medium by which the patterned medium can be comparatively easily manufactured and to provide a magnetic recording device using the patterned medium. <P>SOLUTION: After information "0" and "1" are written in a first magnetic recording medium 10 using a magnetic head, the magnetic recording medium is immersed in a liquid in which soft magnetic nano particles 25 are dispersed and the nano particles 25 adhere to the surface of the first magnetic recording medium 10. A stamper having irregularities according to arrangement of the nano particles 25 is manufactured using the first magnetic recording medium 10 with the nano particles 25 adhered thereon and the stamper is pushed to a resist film on a second magnetic recording medium to form the irregularities on the resist film. The surface of the second magnetic recording medium is etched by using the resist film as a mask. Thus the patterned medium having a projecting bit pattern is completed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a patterned medium on which a convex bit pattern for magnetically recording information is formed, a method for manufacturing the patterned medium, and a magnetic recording apparatus using the patterned medium.

  The amount of information processed by a computer has been increasing year by year, and accordingly, a further increase in capacity of a magnetic recording device (hard disk drive) that stores information is required. In recent years, magnetic recording devices have come to be used in video recording equipment such as hard disk video recorders, portable music playback devices, and the like, and these devices are also required to have a large capacity magnetic recording device.

  To increase the capacity of the magnetic recording medium, it is necessary to further improve the recording density of the magnetic recording medium. To improve the recording density of the magnetic recording medium, the S / N ratio (ratio of signal to noise) ) Need to be improved. Reducing the transition noise generated in the magnetic recording medium is one of the most important issues for improving the recording density.

  The transition noise depends on the size of the magnetic particles constituting the recording layer of the magnetic recording medium. The smaller the particle size of the magnetic particles, the smaller the transition noise. However, when the particle size of the magnetic particles is reduced, the thermal stability is lowered, and a phenomenon (so-called thermal fluctuation) occurs in which information is lost even at room temperature or a temperature close thereto. In order to increase the thermal stability, it is known that the recording layer may be formed of a material having high magnetic anisotropy energy. However, when the recording layer of the magnetic recording medium is formed of such a material, a magnetic field necessary for writing information (data) increases, which causes a problem that writing of information becomes difficult.

  In order to solve such problems, a magnetic recording called a patterned medium is used that forms a convex pattern consisting of a single magnetic domain (hereinafter referred to as a bit pattern) on the surface and records information for one bit in one bit pattern. A medium has been proposed. In this type of magnetic recording medium, the volume of the magnetic crystal can be increased as compared with a conventional magnetic recording medium that uses a large number of magnetic crystals to record 1-bit information. It becomes possible to reduce the isotropic energy and to ensure the ease of writing.

  Patent Documents 1 and 2 describe a method for manufacturing a recording medium having a bit pattern. In the methods described in Patent Documents 1 and 2, a stamper having a concavo-convex pattern is manufactured by a lithography technique using an electron beam. Then, the concavo-convex pattern is transferred to the resist film by pressing the stamper against the resist film formed on the recording medium. Thereafter, the surface of the recording medium is etched using the resist film as a mask to form a convex bit pattern on the surface of the recording medium.

In addition, there exists a thing described in the nonpatent literature 1 as a prior art considered to be related to this invention. Non-Patent Document 1 describes a method for producing soft magnetic nanoparticles.
JP 2005-339669 A International Publication Number WO03 / 0195540 S.Sun and H.Zeng "Size-Controlled Synthesis of Magnetite Nanoparticles" J.AM.CHEM. SOC.Vol.124 pp.8204 (2002)

  In order to achieve a recording density much higher than that of a conventional magnetic recording medium in a patterned medium, it is necessary to make the bit pattern size extremely small. For example, in order to achieve a recording density of 1T (tera) bits / square inch, it is necessary to make the size of one bit pattern about 25 nm × 25 nm. At present, there is no means other than an electron beam for drawing a pattern of this size, but it takes a lot of time to draw a pattern with an electron beam on a resist film having a size corresponding to the entire disk surface. For this reason, if a stamper is manufactured by lithography technology using an electron beam, the manufacturing cost of the stamper becomes extremely high. Even if an electron beam is used, it is difficult to form a bit pattern smaller than the above-described size, and it is impossible to cope with a further increase in the density of the magnetic recording medium.

  An object of the present invention is to provide a patterned medium capable of further increasing the density as compared with the prior art, a method for producing a patterned medium capable of producing the patterned medium relatively easily, and a magnetic medium using the patterned medium. It is to provide a recording device.

  According to one aspect of the present invention, a step of recording magnetic information on a first magnetic recording medium, a step of attaching magnetic particles on a region of the first magnetic recording medium on which the magnetic information is recorded, Forming a nonmagnetic film on the first magnetic recording medium to which the magnetic particles are attached; separating the magnetic particles and the nonmagnetic film from the first magnetic recording medium; and Etching the nonmagnetic film using the mask as a mask to form irregularities on the nonmagnetic film, forming a stamper to which the irregularities of the nonmagnetic film are transferred, and a resist formed on the second magnetic recording medium Pressing the stamper against the film to form irregularities on the resist film, etching the second magnetic recording medium using the resist film as a mask, and forming a convex shape on the surface of the second magnetic recording medium Bit putter Patterned media fabrication method and a step of forming is provided.

  In the present invention, after magnetic information is recorded on the first magnetic recording medium, magnetic particles are attached to the surface of the first magnetic recording medium. In this case, the magnetic particles are attracted to the surface of the first magnetic recording medium by the lines of magnetic force emitted from the first magnetic recording medium, and adhere to the location where the magnetic information is recorded.

  Next, after forming a nonmagnetic film on the first magnetic recording medium, the nonmagnetic film is separated from the first magnetic recording medium together with the magnetic particles. Then, the nonmagnetic film is etched using the magnetic particles as a mask, and a concavo-convex pattern corresponding to the arrangement pattern of the magnetic particles is formed in the nonmagnetic film.

  Next, a stamper to which the uneven pattern of the nonmagnetic film is transferred is formed based on the nonmagnetic film. Then, after using this stamper to form a concavo-convex pattern on the resist film on the second magnetic recording medium, the surface (recording layer) of the second magnetic recording medium is etched using the resist film as a mask. In this way, a patterned medium having a convex bit pattern on the surface can be formed.

  In the present invention, the size of the bit pattern of the patterned media depends on the particle size of the magnetic particles. By using magnetic particles having a particle size of about 10 nm, for example, the recording density can be greatly improved as compared with the conventional case.

  In the present invention, the magnetic particles are magnetically attracted onto the first magnetic recording medium on which the magnetic information is recorded, so that the position where the magnetic particles adhere is the magnetic information recorded on the first magnetic recording medium. Dependent. In this case, magnetic information can be recorded on the first magnetic recording medium using a current magnetic head. Therefore, the bit pattern can be easily formed as compared with the conventional method of determining the position of the bit pattern using the electron beam, and the manufacturing cost of the patterned media can be reduced.

  According to another aspect of the present invention, a substrate, a backing layer formed on the substrate, a nonmagnetic intermediate layer formed on the backing layer, and formed on the intermediate layer A recording layer, and a plurality of convex bit patterns formed in a circumferential direction on the surface of the recording layer and constituting a track, wherein the bit pattern is formed of magnetic particles attached to the surface of the magnetic recording medium. There is provided a patterned medium characterized by being formed by transferring a pattern.

  The patterned media according to the present invention is formed by transferring a pattern of magnetic particles having a bit pattern attached to the surface of a magnetic recording medium. Thereby, the manufacturing cost is reduced. In the present invention, the magnetic particles having a particle size of, for example, about 10 nm are used, so that the bit pattern size is larger than that of a conventional patterned medium in which a bit pattern is formed by lithography using an electron beam. The thickness can be reduced. Thereby, the recording density can be improved as compared with the conventional case.

  According to another aspect of the present invention, a magnetic recording medium capable of magnetically recording information, a magnetic head for writing and reading information on the magnetic recording medium, and the magnetic recording medium for the magnetic head Moving means for relatively moving, the magnetic recording medium comprising: a substrate; a backing layer formed on the substrate; a nonmagnetic intermediate layer formed on the backing layer; A recording layer formed on the intermediate layer; and a plurality of convex bit patterns formed in a circumferential direction on the surface of the recording layer to form a track, wherein the bit pattern is a magnetic recording medium There is provided a magnetic recording apparatus formed by transferring a pattern of magnetic particles attached to the surface of the magnetic recording medium.

  As described above, a patterned medium capable of high-density recording can be obtained by forming a bit pattern by transferring a pattern of magnetic particles attached to the surface of the magnetic recording medium. A magnetic recording apparatus according to the present invention uses a patterned medium in which a pattern of magnetic particles attached to the surface of a magnetic recording medium is transferred to form a bit pattern, and information is recorded and recorded on the patterned medium by a magnetic head. Since reproduction is performed, higher density recording is possible as compared with the conventional case.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 6 are schematic views showing a method for manufacturing a patterned medium (magnetic recording medium) according to an embodiment of the present invention.

  In the present embodiment, information is recorded on a first magnetic recording medium using a magnetic head similar to the magnetic head used in the current magnetic recording apparatus (hard disk drive), and the first magnetic recording medium is used. Forming a stamper.

  That is, as shown in FIG. 1, information “0” and “1” is alternately recorded on the first magnetic recording medium 10 at a constant period by using the magnetic head 20. The recording method at this time may be a vertical recording method or an in-plane recording method. Here, an example in which the vertical recording method is adopted will be described. In this case, as shown in FIG. 1, the magnetic recording medium 10 includes a substrate 11, an underlayer 12 laminated on the substrate 11, a soft magnetic backing layer 13, a nonmagnetic intermediate layer 14, and magnetic information. And a recording layer 15 for recording The magnetic head 20 is a single pole head. The single-pole head includes a coil (not shown), a main magnetic pole 21 that emits magnetic lines generated by a current flowing through the coil toward the magnetic recording medium 10, and a return yoke to which the magnetic lines emitted from the main magnetic pole 21 are fed back. 22. The main magnetic pole 21 has a small cross-sectional area, and the return yoke 22 has a large cross-sectional area.

  When recording information on the first magnetic recording medium 10, the information to be recorded on the magnetic head 20 is arranged by arranging the tip of the magnetic head 20 so as to face the first magnetic recording medium 10 as shown in FIG. The signal according to is supplied. Then, the magnetic field lines generated in the main magnetic pole 21 having a small cross-sectional area penetrate the recording layer 15 in the vertical direction toward the backing layer 13. As a result, a portion of the recording layer 15 immediately below the main magnetic pole 21 is magnetized in the direction of the lines of magnetic force.

  The magnetic field lines penetrating the recording layer 15 in the vertical direction pass through the backing layer 13 in the in-plane direction, pass through the recording layer 15 in the vertical direction again, and return to the return yoke 22 having a large cross-sectional area. At this time, since the magnetic flux density is low, the magnetization direction of the recording layer 15 immediately below the return yoke 22 does not change. By moving the first magnetic recording medium 10 relative to the magnetic head 20 in the direction indicated by A in the figure (the direction in which the track extends), the direction of the magnetic lines of force is changed according to the information to be recorded, thereby changing the magnetic field. A magnetization region with a downward magnetization direction and an upward magnetization region can be alternately arranged along the circumferential direction (track extending direction) of the recording medium 10. Here, for convenience of explanation, it is assumed that “0” is written in the magnetization region whose magnetization direction is downward, and “1” is written in the magnetization region whose magnetization direction is upward.

In this way, after information of “0” and “1” is alternately written on the first magnetic recording medium 10, soft magnetic particles having a particle size on the order of several nanometers to several tens of nanometers on the magnetic recording medium 10 ( Hereinafter, simply referred to as “nanoparticles”. As the nanoparticles, for example, particles made of Fe ₃ O ₄ having a particle size of about 10 nm can be used. The nanoparticles are produced by the method described in Non-Patent Document 1, for example. The nanoparticles are dispersed in a dispersion liquid (nanoparticle dispersion liquid) containing a surfactant. A sealed dip coater is used to attach the nanoparticles. After immersing the magnetic recording medium 10 in the dispersion liquid in which the nanoparticles are dispersed, the magnetic recording medium 10 is pulled up into the saturated vapor of the solvent in which the nanoparticles are dispersed at a low speed.

  FIG. 2A is a schematic cross-sectional view showing the state of magnetization of the surface of the first magnetic recording medium 10, and FIG. 2B shows the state where the nanoparticles 25 are attached to the surface of the first magnetic recording medium 10. It is a schematic cross section shown. 2A and 2B, reference numerals 15a and 15b denote magnetization regions on the surface of the first magnetic recording medium 10. These magnetization areas 15a and 15b are areas in which information of 1 bit is recorded by the magnetic head, and the white arrows indicate the magnetization directions of the magnetization areas 15a and 15b. An arrow 26 indicates lines of magnetic force emitted from the magnetized regions 15a and 15b.

  When the first magnetic recording medium 10 is immersed in a dilute dispersion in which nanoparticles are dispersed, the lines of magnetic force emitted from the magnetized regions 15a and 15b on the surface of the first magnetic recording medium 10 (see FIG. 2A) As a result, the nanoparticles 25 adhere (see FIG. 2B). At this time, the nanoparticles 25 are preferentially attached to the ends of the lines of magnetic force emitted from the magnetized regions 15a and 15b. In the case of a perpendicular magnetic recording medium, the end point of the magnetic field lines is the center of each magnetization region, and in the case of an in-plane magnetic recording medium, it is the boundary of each magnetization region.

  The nanoparticles 25 adhering to the surface of the first magnetic recording medium 10 form a magnetic domain inside as shown in FIG. 2B, and are the nearest nanoparticles among other nanoparticles having different magnetizations. A magnetic circuit is configured with Therefore, the magnetic field lines are not emitted upward from the nanoparticles 25 attached to the surface of the first magnetic recording medium 10, and other nanoparticles 25 are attracted onto the nanoparticles 25 attached to the surface of the magnetic recording medium 10. There is nothing.

  As described above, after immersing the first magnetic recording medium 10 in the dilute dispersion in which the nanoparticles 25 are dispersed, the magnetic recording medium 10 is pulled up into saturated vapor at a low speed to disperse the nanoparticles adhered to the surface. The liquid can be washed off, and the magnetic recording medium 10 with the nanoparticles 25 attached to the surface by one layer can be obtained. By drying the magnetic recording medium 10 in a vacuum, the nanoparticles 25 attached to the surface of the magnetic recording medium 10 are fixed.

  FIG. 3 is a schematic plan view of the first magnetic recording medium 10 to which nanoparticles are attached as viewed from above. As shown in FIG. 3, the magnetized regions 15a and 15b are rectangles whose longitudinal direction is a direction (hereinafter referred to as “track width direction”) perpendicular to the track extending direction (direction indicated by A in the figure). A plurality (three in the example shown in FIG. 3) of nanoparticles 25 are arranged in a line in the track width direction for each of the magnetized regions 15a and 15b. The interval x between the nanoparticles 25 arranged in the track width direction is related to the molecules of the surfactant layer mixed in the nanoparticle dispersion as will be described later.

  As described above, in the present embodiment, the nanoparticles 25 are attached to the ends of the lines of magnetic force emitted from the magnetized regions 15a and 15b. Further, the nanoparticles 25 are arranged in a line in the track width direction for each of the magnetization regions 15a and 15b. In this case, if the distance y between the nanoparticles 25 in the track extending direction (the direction indicated by A in FIG. 3) is larger than the size of the nanoparticles 25, the nanoparticles 25 attached to the ends of the magnetic field lines are self-assembled. In the meantime, other nanoparticles 25 are attached so as to fill the gaps, and the arrangement of the nanoparticles 25 is disturbed. In order to avoid such a phenomenon, the size of the magnetized regions 15a and 15b and the size of the nanoparticles 25 are set so that the distance y between the nanoparticles 25 attached to the ends of the magnetic field lines is smaller than the size of the nanoparticles 25. It is important to set the size. The sizes of the magnetized regions 15a and 15b are related to the size of the magnetic head (main magnetic pole) used for writing information, the write frequency, the rotational speed of the magnetic recording medium, and the like.

From the viewpoint of securing a high recording density, the occupied area of the nanoparticles 25 (the area when projected onto the surface of the magnetic recording medium 10) is preferably 400 nm ² or less. 2 (a), (b) and FIG. 3, the nanoparticles 25 are assumed to be spherical. However, the shape of the nanoparticles 25 is not limited to a spherical shape, and may be a cylindrical shape or other shapes. Good.

  Next, a stamper is produced using the first magnetic recording medium 10 with the nanoparticles 25 attached to the surface. 4 to 6 are schematic views showing steps from the production of the stamper to the production of the patterned media.

  FIG. 4A is a schematic diagram showing the first magnetic recording medium 10 having nanoparticles 25 attached to the surface. As described above, the nanoparticles 25 are arranged in a line in the track width direction for each magnetization region. On this first magnetic recording medium 10, Si (silicon) or the like is deposited by, for example, sputtering to form a Si film (nonmagnetic film) 31 as shown in FIG. 4B. The thickness of the Si film 31 is, for example, 500 nm. Instead of the Si film 31, an inorganic film made of another material may be formed.

  Next, as shown in FIG. 4C, a glass substrate 32 is bonded on the Si film 31. In the present embodiment, a photocurable resin 33 is used for bonding the glass substrate 32, and a silane coupling agent 34 is applied to each of the bonding surfaces of the Si film 31 and the glass substrate 32.

Next, as shown in FIG. 4D, the magnetic recording medium 10 is peeled from the glass substrate 32. For example, when the nanoparticles 25 are attached to the surface of the magnetic recording medium 10, a surface active agent such as oleic acid is contained in the nanoparticle dispersion. Then, by heating from the magnetic recording medium 10 side, a shearing force is generated due to a difference in thermal expansion coefficient between the magnetic recording medium 10 and the glass substrate 32, and this shearing force is generated by the nanoparticles (Fe ₃ O ₄ ) 25. In addition, the magnetic recording medium 10 can be peeled from the glass substrate 32 by acting on a layer of a surfactant present between the Si film 31 and the magnetic recording medium 10. In this case, the nanoparticles 25 and the Si film 31 remain attached to the glass substrate 32 side.

Next, as shown in FIG. 5A, the Si film 31 is etched to a depth of 50 nm by reactive ion etching using, for example, CF ₄ as an etching gas using the nanoparticles 25 as a mask. Unevenness is formed. The nanoparticles 25 remaining on the surface of the Si film 31 can be removed by dissolving with diluted hydrochloric acid after the etching.

  Next, as shown in FIG. 5 (b), a metal such as Ni is thick-plated on the Si film 31 (on the lower side in FIG. 5 (b)) to form unevenness corresponding to the unevenness of the Si film 31. The stamper 35 is formed. If necessary, a metal such as Ni may be plated with a thick film, and then a reinforcing plate may be attached to form a stamper. After forming the stamper 35 in this way, the stamper 35 is peeled off from the glass substrate 32 as shown in FIG.

  On the other hand, as shown in FIG. 5D, a second magnetic recording medium 40a serving as a patterned medium is prepared. Here, as the second magnetic recording medium 40a, a perpendicular recording magnetic recording medium having the same structure as that of the first magnetic recording medium 10 used for attaching the nanoparticles 25 is used. Then, a resist is applied on the second magnetic recording medium 40a to form a resist film 47 having a thickness of 20 nm, for example.

  Next, as shown in FIG. 6A, the stamper 35 is pressed against the resist film 47 to transfer the uneven pattern of the stamper 35 to the resist film 47. Thereafter, as shown in FIG. 6B, after removing the stamper 35 from the second magnetic recording medium 40a, the resist film 47 is heated and cured.

  Next, as shown in FIG. 6C, the surface (recording layer) of the second magnetic recording medium 40a is etched using the resist film 47 as a mask. At this time, since a slight amount of resist remains on the magnetic recording medium 40a even in the pattern recesses, the resist residue is first removed by reactive ion etching using oxygen as an etching gas, and then recorded by milling using Ar. Etch the layer. The etching depth at this time is, for example, the same as the thickness of the recording layer. Thereafter, the resist film 47 is removed. In this way, a patterned medium (magnetic recording medium) 40 having a convex bit pattern 45a on the surface of the recording layer is completed.

  FIG. 7 is a schematic cross-sectional view showing the structure of the patterned medium 40 manufactured by the method described above. As shown in FIG. 7, the patterned medium 40 records a substrate 41, an underlayer 42 laminated on the substrate 41, a soft magnetic backing layer 43, a nonmagnetic intermediate layer 44, and magnetic information. And a recording layer 45 to be formed. Bit patterns 45a formed by the above-described method are formed on the surface of the recording layer 45 at a constant pitch. A protective film made of, for example, DLC (Diamond-Like-Carbon) or the like is formed on the recording layer 45, and a lubricating oil thin film is formed thereon.

  FIG. 8 is a schematic plan view showing the relationship between the bit pattern 45a of the patterned medium 40 manufactured by the above-described method and the magnetization regions 15a and 15b of the first magnetic recording medium 10 used for adhesion of the nanoparticles. is there. In FIG. 8, the bit pattern 45a is formed on the surface of the recording layer 45 of the patterned medium 40 (see FIG. 7), and the magnetized regions 15a and 15b are formed on the first magnetic recording medium 10 used for nanoparticle adhesion. The magnetization region is shown (see FIGS. 2 and 3).

  As shown in FIG. 8, the pitch P1 of the bit pattern 45a in the circumferential direction (direction indicated by A in the figure) in the patterned medium 40 of the present embodiment is the first magnetic recording medium 10 used for nanoparticle adhesion. This is the same as the pitch of the magnetized regions 15a and 15b. Therefore, the linear recording density (number of bits per unit length of the track) of the patterned medium 40 of the present embodiment is the same as the linear recording density of the first magnetic recording medium 10 used for attaching the nanoparticles. However, in the patterned medium 40 of the present embodiment, a plurality of (three in the example shown in FIG. 8) bit patterns 45a are formed in the width of one track of the first magnetic recording medium 10 used for attaching the nanoparticles. Exists. These bit patterns 45a constitute different tracks (indicated by a one-dot chain line in FIG. 8).

  That is, the patterned medium 40 manufactured according to the present embodiment has a track density that is several times that of the conventional magnetic recording medium (three times in the example shown in FIG. 8). As described above, according to the present embodiment, the recording density of the magnetic recording medium (patterned medium) can be greatly improved as compared with the conventional magnetic recording medium (general perpendicular recording type magnetic recording medium). .

  Further, in this embodiment, since the position of the bit pattern 45a is determined by utilizing the self-organization of nanoparticles, it is compared with the conventional patterned media manufacturing method that determines the position of the bit pattern using an electron beam. Therefore, the bit pattern can be easily formed, and the time required for manufacturing can be shortened. Thereby, the effect that the manufacturing cost of patterned media can be reduced is also acquired.

  Furthermore, in this embodiment, the size of the bit pattern depends on the size of the nanoparticle, and for example, a nanoparticle having a diameter of about 10 nm can be used. Therefore, the bit pattern is formed by lithography using an electron beam. The density can be further increased compared to the conventional patterned media that forms the film.

(Track pitch control)
By the way, as described above, the track density of the patterned medium 40 manufactured by the method according to the present embodiment is such that the distance x between the nanoparticles 25 aligned in the track width direction on the magnetization regions 15a and 15b of the first magnetic recording medium 10 is determined. (See FIG. 3). The distance x between the nanoparticles 25 is related to the surfactant mixed in the nanoparticle dispersion. That is, when the surfactant is mixed in the nanoparticle dispersion at a ratio to form a monolayer film around the nanoparticles, a monolayer film 26 of the surfactant is formed around the nanoparticles 25 as shown in FIG. Is done. Therefore, the distance x between the nanoparticles 25 is almost twice the film thickness of the monolayer film 26 of the surfactant. In this case, the interval x between the nanoparticles 25 can be arbitrarily set by selecting molecules contained in the surfactant.

  For example, when oleic acid is used as the surfactant, the distance x between the nanoparticles 25 in the track width direction is about 4.5 nm. Further, when heptacosanoic acid is used as the surfactant, the distance x between the nanoparticles 25 in the track width direction is about 6.5 nm. In this manner, the interval (pitch) between tracks of the patterned medium (magnetic recording medium) 40 can be adjusted.

(Tracking control area)
As described above, when information of “0” and “1” is alternately recorded on the first magnetic recording medium 10, the nanoparticles are arranged in a line in the track extending direction (circumferential direction). Here, when information of “0” or “1” is partially continued, the arrangement of the nanoparticles changes. Tracking control using changes in the arrangement of the nanoparticles will be described below.

  FIG. 10 shows an example in which the order of “0” and “1” is changed at the position indicated by the arrow B. As a result, on the surface of the magnetic recording medium 10, the magnetized regions 15a in which “0” is recorded are adjacent to each other. When the magnetized regions 15a having the same magnetization direction are arranged next to each other as described above, all the nanoparticles 25 attached to the magnetized regions 15a are magnetized in the same direction. Therefore, the nanoparticles 25 attached to the magnetized regions 15a are arranged so that the mutual distance becomes maximum by self-organization. As a result, as shown in FIG. 10, the arrangement of the nanoparticles 25 is shifted by ½ pitch with the position indicated by the arrow B as the boundary.

  Thus, the bit pattern corresponding to the part where the arrangement of the nanoparticles 25 is shifted can be used for tracking control. FIG. 11 is a schematic diagram showing a patterned medium (magnetic recording medium) provided with a tracking control area 50. As shown in FIG. 10, by shifting the arrangement of nanoparticles by 1/2 pitch, as shown in FIG. 11, the bit pattern 45a is arranged in two rows across the center axis of the track (shown by a one-dot chain line in FIG. 11). Arranged tracking control regions 50 are formed.

  In a patterned medium having such a tracking control region 50, tracking control of the magnetic head can be easily performed. Here, it is assumed that the same information (“0” or “1”) is recorded in all the bit patterns 45 a in the tracking control area 50. In this case, in the tracking control area 50, when the magnetic head moves on the central axis of the track (indicated by a one-dot chain line in the figure), the output of the magnetic head is minimized. Conversely, by controlling the position of the magnetic head so that the output of the magnetic head is minimized in the tracking control area 50, the magnetic head can be disposed on the central axis of the track. When recording or reproducing information with respect to the patterned medium, it is important to perform tracking control in this manner and arrange the magnetic head on the central axis of the track.

  As shown in FIG. 12, the magnetization directions of the two bit patterns 45a opposed across the central axis of the track may be reversed. In FIG. 12, a bit pattern in which “0” is written is indicated by a black circle, and a bit pattern in which “1” is written is indicated by a cross. In this way, when the two bit patterns 45a having opposite magnetization directions are arranged opposite to each other with the central axis of the track interposed therebetween in the tracking control region 50, when the magnetic head is positioned on the central axis of the track, The magnetic field lines emitted from the two bit patterns 45a cancel each other, and the reproduction signal is not output from the magnetic head. Therefore, by controlling the position of the magnetic head so that the reproduction signal is not output in the tracking region 50, the magnetic head can be arranged on the central axis of the track.

  When writing information to the bit pattern 45a, a magnetic head (indicated by a broken line in FIG. 12) in which the write head is arranged obliquely with respect to the track is used to invert “0” and “1” for each bit. Thereby, as shown in FIG. 12, a patterned medium in which the magnetization directions of the bit patterns 45a adjacent to each other in the track extending direction and the track width direction are reversed can be manufactured.

(Magnetic recording device)
FIG. 13 is a plan view showing a magnetic recording apparatus (magnetic disk apparatus) according to an embodiment of the present invention.

  The magnetic recording device 60 includes a disc-shaped patterned medium (magnetic recording medium) 61, a spindle motor (not shown) that rotates the patterned medium 61, a magnetic head 62, and a magnetic head 62 in the casing. The suspension 63 to be supported, the actuator 64 for driving and controlling the suspension 63 in the radial direction of the patterned medium 61, the spindle motor and the actuator 64 are driven and controlled, and information is written to the patterned medium 61 via the magnetic head 62. And an electronic circuit 65 that performs reading.

  The magnetic head 62 includes a writing element (inductive head) that converts an electric signal into a magnetic signal and a reading element (magnetoresistance effect element) that converts a magnetic signal into an electric signal. The patterned medium 61 has the structure shown in FIG. 7, and a bit pattern for recording information and a bit pattern for tracking control (see FIG. 11) are provided on the surface thereof. Further, a protective film and a lubricating oil thin film are provided on the surface of the patterned medium 61.

  When the patterned medium 61 is rotated at a high speed by the spindle motor, the magnetic head 62 slightly floats from the surface of the patterned medium 61 due to the air flow generated by the rotation of the patterned medium 61. In this state, the magnetic head 62 is moved in the radial direction of the patterned medium 61 by the actuator 64, and information is written to or read from the patterned medium 61.

  Hereinafter, an embodiment in which the patterned media according to the present invention is actually manufactured will be described with reference to FIGS.

Example 1
First, as a first magnetic recording medium 10 to which nanoparticles were attached, a perpendicular recording type magnetic recording medium capable of recording information with a surface density of 100 Gbit / in 2 was prepared. Then, information “0” and “1” was alternately recorded on the entire surface of the recording layer of the magnetic recording medium 10 using a write head (magnetic head 20) having a core width (main magnetic pole width) of 100 nm (FIG. 1, see FIG. Thereafter, the magnetic recording medium 10 was washed using a fluorocarbon solvent FC-77 (manufactured by 3M), and the lubricating film applied to the surface of the magnetic recording medium 10 was removed.

Next, nanoparticles 25 were attached to the surface of the magnetic recording medium 10 using a sealed dip coater (see FIG. 4A). As the nanoparticles 25, Fe ₃ O ₄ particles having a particle size of 9 nm were used, and the nanoparticles 25 were dispersed in an octane dispersion at a rate of 0.1 mg / mL (milliliter) to obtain a nanoparticle dispersion. The magnetic recording medium 10 was immersed in the nanoparticle dispersion for 1 minute and then pulled up at a speed of 50 mm / min. In addition, oleic acid as a surfactant is added to the octane dispersion at a mass that is 1/3 of the nanoparticles (Fe ₃ O ₄ particles).

  After the nanoparticles 25 were attached to the surface of the first magnetic recording medium 10 in this way, drying was performed in a vacuum for 24 hours. When the adsorption state of the nanoparticles 25 after drying was observed using an atomic force microscope (AFM), seven nanoparticles 25 were arranged at intervals of 4.5 nm in the radial direction of the magnetic recording medium 10 for each magnetization region. It was confirmed that

  Next, a Si film 31 having a thickness of 500 nm was formed on the magnetic recording medium 10 to which the nanoparticles 25 adhered by sputtering (see FIG. 4B). Then, the silane coupling agent 34, the photocurable resin 33, and the silane coupling agent 34 were formed in order on the Si film 31, and the glass substrate 32 was adhered thereon (see FIG. 4C).

  Next, the magnetic recording medium 10 to which the glass substrate 32 was bonded was heated to 100 ° C. from the magnetic recording medium 10 side. Thereby, a shearing force is generated due to a difference in thermal expansion coefficient between the magnetic recording medium 10 and the glass substrate 32, and this shearing force exists between the nanoparticles 25 and the Si film 31 and the magnetic recording medium 10. Working on the acid layer, the magnetic recording medium 10 and the glass substrate 32 could be separated. In this case, the nanoparticles 25 and the Si film 31 are separated from the magnetic recording medium 10 while being attached to the glass substrate 32 (see FIG. 4D).

Next, the Si film 31 was etched to a depth of about 50 nm using the nanoparticles (Fe ₃ O ₄ ) 25 as a mask to form irregularities on the surface of the Si film 31 (see FIG. 5A).

  Next, a Ni film was thickly plated on the Si film 31 to form a stamper 35 (see FIG. 5B). Thereafter, the stamper was separated from the Si film (glass substrate) (see FIG. 5C).

  On the other hand, a second magnetic recording medium 40a serving as a patterned medium was prepared. The second magnetic recording medium 40 a includes a substrate 41, a base film 42 laminated on the substrate 41, a soft magnetic backing layer 43, an intermediate layer 44, and a recording layer 45. A resist was applied on the magnetic recording medium 40a (on the recording layer) to form a resist film 47 having a thickness of about 20 nm (see FIG. 5D). Thereafter, the stamper 35 was pressed onto the resist film 47 to transfer the uneven pattern of the stamper 35 to the resist film 47 (see FIG. 6A).

  Next, after the stamper 35 was removed from the resist film 47, the resist film 47 was thermally cured (see FIG. 6B). Then, the surface (recording layer) of the magnetic recording medium 40a was etched using the resist film 47 as a mask, and then the resist film 47 was removed (see FIG. 6C). In this way, the patterned medium 40 of Example 1 was completed (see FIG. 7).

  When the surface of the completed patterned medium 40 was observed, it was confirmed that a circular bit pattern 45a having a diameter of about 10 nm was formed on the surface. Further, it was confirmed that the arrangement state of the bit pattern 45a was the same as the arrangement state of the nanoparticles 25 attached on the magnetic recording medium 10.

(Example 2)
A magnetic recording medium (patterned medium) was produced in the same manner as in Example 1 using heptacosanic acid having a molecular length of about 1.5 times that of oleic acid as a surfactant to be mixed with the nanoparticle dispersion. As a result, it was confirmed that a circular bit pattern having a diameter of about 10 nm was formed in which 6 pieces were arranged at intervals of about 6.5 nm in the radial direction of the patterned medium.

(Example 3)
First, as a first magnetic recording medium 10 to which nanoparticles were attached, a perpendicular recording type magnetic recording medium capable of recording information with a surface density of 100 Gbit / in 2 was prepared. Then, using a write head (magnetic head 20) having a core width (main magnetic pole width) of 100 nm, information for one track (one round) was recorded at a position of a radius of 20 mm from the center of the magnetic recording medium 10. . At this time, information was basically recorded in a pattern in which the magnetization directions were alternately reversed, but the magnetization directions of adjacent magnetic domains were made the same at a rate of one place per 1 mm.

Then, in the same manner as in Example 2, heptacosanoic acid was mixed as a surfactant, and a nanoparticle dispersion liquid in which nanoparticles having a particle size of 9 nm (Fe ₃ O ₄ particles) were added at a rate of 0.1 mg / mL was magnetically added. The recording medium 10 was immersed for 1 minute. Thereafter, the magnetic recording medium 10 was pulled up from the nanoparticle dispersion at a speed of 50 mm / min, and then dried in a vacuum for 24 hours.

  When the adsorption state of the nanoparticles 25 after drying was observed using an atomic force microscope (AFM) and a magnetic force microscope (MFM), the arrangement of the nanoparticles 25 was shifted by 1/2 pitch as shown in FIG. The area was confirmed to exist. That is, there are a region in which five rows of nanoparticles 25 are arranged at intervals of about 7 nm and a region in which six rows of nanoparticles 25 are arranged at intervals of about 7 nm, with a boundary where the magnetization directions of adjacent recording bits are the same. Confirmed to do.

  Thereafter, in the same manner as in Example 1, a stamper 35 is formed using the magnetic recording medium 10 to which the nanoparticles 25 are adhered, and a concave / convex pattern on the surface of the stamper 35 is used as a patterned medium. Transferred to the resist film 41 formed thereon. Next, the surface (recording layer) of the magnetic recording medium 40a was etched using the resist film 41 as a mask, and then the resist film 47 was removed (see FIG. 6C). Thereafter, a carbon protective film was formed on the recording layer to obtain a patterned medium 40. In this way, the patterned medium 40 of Example 3 was completed.

Example 4
Writing was performed on the bit pattern 45a of the patterned medium 40 created in Example 3 using a single pole head. As shown in FIG. 15, information is written in a pattern in which the magnetization direction is alternately reversed with respect to the central bit pattern 45a in the portion where the bit pattern 45a is arranged in five rows, and in the portion where the six rows are arranged, Writing was performed on the two bit patterns 45a in the center so that the magnetization directions were all upward, thereby forming a tracking control region. In FIG. 15, the bit pattern 45a whose magnetization direction is upward is indicated by a cross, and the bit pattern 45a whose magnetization direction is downward is indicated by a black circle.

  Separately, a read magnetic head is prepared, and when a bit pattern 45a having an upward magnetization direction is continuous, a tracking operation is performed to adjust the position of the magnetic head so that the read output is minimized. The center line of this read head was aligned with the center line of one column at the center where five rows of bit patterns 45a were arranged, and reading was attempted at a linear velocity of 10 mm / sec. As a result, it was confirmed that the reproducing operation was normally performed for 60 minutes and the tracking control was working effectively.

(Example 5)
Writing was performed on the bit pattern 45a of the patterned medium 40 created in Example 3 using a single pole head. At this time, writing was performed by tilting the single pole head by 45 degrees with respect to the traveling direction. As a result, as shown in FIG. 16, writing is performed so that the magnetization direction is all upward with respect to the bit pattern of one column at the center of the portion where the bit patterns 45a are arranged in five rows, and six rows are arranged. With respect to the portion, it was possible to write in the central two bit patterns 45a in a pattern in which the magnetization directions of the adjacent bit patterns 45a are opposite to each other. In FIG. 16 as well, the bit pattern 45a whose magnetization direction is upward is indicated by a cross, and the bit pattern 45a whose magnetization direction is downward is indicated by a black circle. The two bit patterns 45a in the center of the 6-lined portion constitute the tracking control area.

  Separately, a read magnetic head is prepared, and when it is not determined that the bit pattern 45a having the upward magnetization direction is continuous, a tracking operation is performed to adjust the position of the magnetic head so that the read output is minimized. . The center line of this read head was aligned with the center line of one central column where five bit patterns 45a were arranged, and reading was attempted at a linear velocity of 10 mm / sec. As a result, it was confirmed that the reproducing operation was normally performed for 60 minutes and the tracking control was working effectively.

  Hereinafter, various aspects of the present invention will be collectively described as supplementary notes.

(Appendix 1) Recording magnetic information on a first magnetic recording medium;
Attaching magnetic particles on a region of the first magnetic recording medium on which the magnetic information is recorded;
Forming a nonmagnetic film on the first magnetic recording medium to which the magnetic particles are attached;
Separating the magnetic particles and the nonmagnetic film from the first magnetic recording medium;
Etching the nonmagnetic film using the magnetic particles as a mask to form irregularities in the nonmagnetic film;
Forming a stamper to which the irregularities of the non-magnetic film are transferred;
Pressing the stamper against a resist film formed on the second magnetic recording medium to form irregularities on the resist film;
Etching the second magnetic recording medium using the resist film as a mask, and forming a convex bit pattern on the surface of the second magnetic recording medium. .

  (Additional remark 2) The said 2nd magnetic recording medium is a magnetic recording medium of a perpendicular recording system, The manufacturing method of the patterned media of Additional remark 1 characterized by the above-mentioned.

(Supplementary note 3) The method for producing a patterned medium according to supplementary note 1, wherein a projected area of the magnetic particles is 400 nm ² or less.

  (Supplementary note 4) The method for manufacturing a patterned medium according to supplementary note 1, wherein “0” and “1” are alternately recorded in the circumferential direction as the magnetization information on the first magnetic recording medium. .

  (Supplementary Note 5) The first magnetic recording medium records “0” and “1” alternately in the circumferential direction as the magnetization information, and either “0” or “1” is recorded in a predetermined area. The method for producing a patterned medium according to appendix 1, wherein recording is performed continuously.

  (Additional remark 6) The said magnetic particle is made to adhere on the said 1st magnetic recording medium in the state disperse | distributed to the dispersion liquid containing surfactant, The manufacturing method of the patterned media of Additional remark 1 characterized by the above-mentioned.

  (Additional remark 7) The manufacturing method of the patterned media of Additional remark 6 characterized by making the dispersion liquid which disperse | distributed the said magnetic particle adhere on said 1st magnetic recording medium using a sealing dip coater.

(Appendix 8) a substrate;
A backing layer formed on the substrate;
A nonmagnetic intermediate layer formed on the backing layer;
A recording layer formed on the intermediate layer;
A plurality of convex bit patterns formed side by side in the circumferential direction on the surface of the recording layer and constituting tracks.
A patterned medium, wherein the bit pattern is formed by transferring a pattern of magnetic particles attached to the surface of a magnetic recording medium.

(Supplementary note 9) The patterned medium according to supplementary note 8, wherein the size of the bit pattern is 400 nm ² or less.

  (Supplementary note 10) The patterned medium according to supplementary note 8, wherein the track has a region in which the bit patterns are arranged in one column and a region in which the bit patterns are arranged in two columns.

  (Additional remark 11) In the area | region where the said bit pattern was located in 2 rows, all the magnetization directions of those bit patterns are the same, The patterned media of Additional remark 10 characterized by the above-mentioned.

  (Additional remark 12) The patterned media of Additional remark 10 characterized by the magnetization direction of an adjacent bit pattern being reverse in the area | region where the said bit pattern was located in 2 rows.

(Supplementary note 13) a magnetic recording medium capable of magnetically recording information;
A magnetic head for writing and reading information to and from the magnetic recording medium;
Moving means for moving the magnetic recording medium relative to the magnetic head;
The magnetic recording medium includes a substrate, a backing layer formed on the substrate, a nonmagnetic intermediate layer formed on the backing layer, a recording layer formed on the intermediate layer, A plurality of convex bit patterns formed side by side in the circumferential direction on the surface of the recording layer and constituting a track, and the bit pattern transfers a pattern of magnetic particles attached to the surface of the magnetic recording medium. A magnetic recording apparatus characterized by being formed.

(Supplementary note 14) The magnetic recording apparatus according to supplementary note 13, wherein the size of the bit pattern of the magnetic recording medium is 400 nm ² or less.

  (Supplementary note 15) The magnetic recording according to supplementary note 13, wherein the track of the magnetic recording medium has a region in which the bit patterns are arranged in one row and a region in which the bit patterns are arranged in two rows. apparatus.

  (Supplementary note 16) The magnetic recording apparatus according to supplementary note 15, wherein in the region where the bit patterns are arranged in two columns, the magnetization directions of the bit patterns are all the same.

  (Supplementary note 17) The magnetic recording apparatus according to supplementary note 15, wherein in the region where the bit patterns are arranged in two columns, the magnetization directions of adjacent bit patterns are opposite.

  (Supplementary note 18) The magnetic recording according to supplementary note 15, wherein tracking control is performed so that a reproduction signal from the magnetic head is minimized in an area where the bit patterns of the magnetic recording medium are arranged in two rows. apparatus.

FIG. 1 is a schematic diagram showing a method for manufacturing a patterned medium according to an embodiment of the present invention, and is a diagram showing a process of writing information to a first magnetic recording medium. FIG. 2 is a schematic diagram showing a method for producing a patterned medium according to an embodiment of the present invention, in which the state of magnetization of the surface of the first magnetic recording medium and the magnetic particles attached to the surface of the first magnetic recording medium FIG. FIG. 3 is a schematic view showing a method for producing a patterned medium according to an embodiment of the present invention, and is a view showing a state where the first magnetic recording medium with nanoparticles attached is viewed from above. FIG. 4 is a schematic diagram illustrating a method for manufacturing a patterned medium according to an embodiment of the present invention, and is a diagram (part 1) illustrating steps from manufacturing a stamper to manufacturing patterned media. FIG. 6 is a schematic diagram illustrating a method for manufacturing a patterned medium according to the embodiment of the present invention, and is a diagram (part 2) illustrating a process from the production of a stamper to the manufacture of a patterned medium. FIG. 6 is a schematic diagram illustrating a method for manufacturing a patterned medium according to the embodiment of the present invention, and is a diagram (part 3) illustrating steps from the production of the stamper to the manufacture of the patterned medium. FIG. 7 is a schematic cross-sectional view showing the structure of the patterned media manufactured by the method according to the embodiment of the present invention. FIG. 8 is a schematic plan view showing the relationship between the bit pattern of the patterned medium manufactured by the method according to the embodiment of the present invention and the magnetization region of the first magnetic recording medium used for attaching the nanoparticles. . FIG. 9 is a schematic diagram showing a single layer film of a surfactant around the nanoparticles attached to the surface of the first magnetic recording medium. FIG. 10 is a schematic diagram showing the arrangement of nanoparticles when the order of “0” and “1” is changed at a predetermined location. FIG. 11 is a schematic diagram showing an example of a patterned medium (magnetic recording medium) provided with a tracking control area. FIG. 12 is a schematic diagram showing another example of a patterned medium (magnetic recording medium) provided with a tracking control area. FIG. 13 is a plan view showing a magnetic recording apparatus (magnetic disk apparatus) according to an embodiment of the present invention. FIG. 14 is a schematic diagram showing nanoparticles adhering to the surface of the first magnetic recording medium, and is a diagram showing a region where the arrangement of nanoparticles is shifted by ½ pitch. FIG. 15 is a schematic diagram illustrating an example of a patterned medium provided with a tracking control area. FIG. 16 is a schematic diagram illustrating another example of a patterned medium provided with a tracking control region.

Explanation of symbols

10: First magnetic recording medium,
11, 41 ... substrate,
12, 42 ... Underlayer,
13, 43 ... soft magnetic backing layer,
14, 44 ... intermediate layer,
15, 45 ... recording layer,
15a, 15b ... magnetized region,
20, 62 ... Magnetic head 21 ... Main pole,
22 ... Return yoke,
25 ... nanoparticle (magnetic particle),
26: Monolayer film of surfactant,
31 ... Si film,
32 ... Glass substrate,
33 ... light curable resin,
34. Silane coupling agent,
35 ... Stamper,
40, 61 ... patterned media,
40a ... second magnetic recording medium,
45a ... bit pattern,
47. Resist film,
50: Tracking control area,
60 ... Magnetic recording device,
63 ... Suspension,
64 ... Actuator,
65: Electronic circuit.

Claims (5)

Recording magnetic information on the first magnetic recording medium;
Attaching magnetic particles on a region of the first magnetic recording medium on which the magnetic information is recorded;
Forming a nonmagnetic film on the first magnetic recording medium to which the magnetic particles are attached;
Separating the magnetic particles and the nonmagnetic film from the first magnetic recording medium;
Etching the nonmagnetic film using the magnetic particles as a mask to form irregularities in the nonmagnetic film;
Forming a stamper to which the irregularities of the non-magnetic film are transferred;
Pressing the stamper against a resist film formed on the second magnetic recording medium to form irregularities on the resist film;
Etching the second magnetic recording medium using the resist film as a mask, and forming a convex bit pattern on the surface of the second magnetic recording medium. .   The patterned medium manufacturing method according to claim 1, wherein the second magnetic recording medium is a perpendicular recording magnetic recording medium. The method for producing patterned media according to claim 1, wherein the projected area of the magnetic particles is 400 nm ² or less. A substrate,
A backing layer formed on the substrate;
A nonmagnetic intermediate layer formed on the backing layer;
A recording layer formed on the intermediate layer;
A plurality of convex bit patterns formed side by side in the circumferential direction on the surface of the recording layer and constituting tracks.
A patterned medium, wherein the bit pattern is formed by transferring a pattern of magnetic particles attached to the surface of a magnetic recording medium. A magnetic recording medium capable of magnetically recording information;
A magnetic head for writing and reading information to and from the magnetic recording medium;
Moving means for moving the magnetic recording medium relative to the magnetic head;
The magnetic recording medium includes a substrate, a backing layer formed on the substrate, a nonmagnetic intermediate layer formed on the backing layer, a recording layer formed on the intermediate layer, A plurality of convex bit patterns formed side by side in the circumferential direction on the surface of the recording layer and constituting a track, and the bit pattern transfers a pattern of magnetic particles attached to the surface of the magnetic recording medium. A magnetic recording apparatus characterized by being formed.

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