JP2010123158A - Magnetic recording medium, method of manufacturing magnetic recording medium and magnetic recording and playback device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording medium which is manufactured in high yield by highly accurately forming all of a pattern shape which comprises magnetic layers by using a highly accurate resist pattern in which servo information having excellent reliability is written. <P>SOLUTION: The magnetic recording medium 50 is constituted so that an annular magnetic recording pattern 51a comprising magnetically separated magnetic layers is provided on a non-magnetic substrate and servo information is magnetically written in the magnetic recording pattern 51a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium used for a hard disk device or the like, a method for manufacturing the magnetic recording medium, and a magnetic recording / reproducing apparatus.

  In recent years, the application range of magnetic recording devices such as hard disk devices has been remarkably increased, and the importance thereof has increased, and the recording density of magnetic recording media used in these devices has been remarkably improved. In particular, since the introduction of MR (magnet resistive) head and PRML technology, the increase in surface recording density has become even more intense. In recent years, GMR (giant magnet resistive) heads and TMR (tunneling magnet resistive) heads have also been introduced. It continues to increase at a rate of about 50% per year. For these magnetic recording media, it is required to achieve higher recording density in the future. For this reason, it is required to increase the coercive force of the magnetic layer, achieve a high signal-to-noise ratio (SNR), and high resolution. ing. In recent years, efforts have been made to increase the surface recording density by increasing the track density as well as improving the linear recording density.

In the latest magnetic recording apparatus, the track density has reached 110 kTPI. However, as the track density is increased, magnetic recording information between adjacent tracks interfere with each other, and the problem that the magnetization transition region in the boundary region becomes a noise source and the SNR is easily lost. This directly leads to a decrease in Bit Error rate, which is an obstacle to improving the recording density.
In order to increase the surface recording density, it is necessary to make the size of each recording bit on the magnetic recording medium finer and ensure as much saturation magnetization and magnetic film thickness as possible for each recording bit. However, when the recording bits are miniaturized, the minimum magnetization volume per bit becomes small, and there arises a problem that the recording data is lost due to magnetization reversal due to thermal fluctuation.

  Also, as the track density is increased, the distance between the tracks becomes closer, and therefore a magnetic recording apparatus is required to have an extremely accurate track servo technology. In order to eliminate the influence from adjacent tracks as much as possible, a method is generally used in which recording is performed widely and playback is performed narrower than during recording. This method can minimize the influence between tracks, but it is difficult to obtain a sufficient reproduction output. Therefore, there is a problem that it is difficult to ensure a sufficient SN ratio (SNR).

  As one of the methods for solving the above-mentioned thermal fluctuation problem and ensuring a sufficient S / N ratio or ensuring a sufficient output, irregularities along the tracks are formed on the surface of the recording medium, and the recording tracks are physically separated. Attempts have been made to increase track density by mechanical or magnetic separation. Such a technique is hereinafter referred to as a discrete track method, and a magnetic recording medium manufactured thereby is referred to as a discrete track medium.

As an example of a discrete track medium, a soft magnetic layer and a ferromagnetic layer are laminated on a nonmagnetic substrate having a plurality of convex portions and a concave portion surrounding each convex portion, and the unevenness reflecting the shape of the nonmagnetic substrate is soft magnetic. There is known a magnetic recording medium in which only a convex portion of a ferromagnetic layer formed on a magnetic layer and a ferromagnetic layer is used as a recording region (see, for example, Patent Document 1).
According to this magnetic recording medium, the occurrence of a domain wall in the soft magnetic layer can be suppressed, so that the influence of thermal fluctuation is difficult to occur, and there is no interference between adjacent signals. Has been.

  Discrete track media are generally formed using a method in which a continuous magnetic layer is formed on a nonmagnetic substrate, a patterned resist layer is formed on the magnetic layer, and the magnetic layer is magnetically separated using this. Has been. In addition, as a method for patterning the resist layer, a photolithography method, a nanoimprint method for transferring a pattern using a stamp to a liquid resist, and the like are used.

  In addition, as a method for manufacturing a discrete track medium, a method of forming a track after forming a magnetic recording medium composed of several thin films, or forming a concavo-convex pattern directly on a substrate surface in advance or on a thin film layer for track formation. There is a method of forming a thin film of a magnetic recording medium after the formation (see, for example, Patent Document 2 and Patent Document 3).

In addition, as a method of manufacturing a discrete magnetic recording medium, by performing ion implantation from outside or laser irradiation, the magnetic characteristics of a desired portion of a continuous magnetic layer on a nonmagnetic substrate can be locally changed. There is also a method for forming a recording track (see, for example, Patent Document 4).
For example, Patent Document 5 discloses a magnetic layer having a region that is not magnetized by ion implantation instead of a gap between lands.
Further, for example, in Patent Document 6, a magnetic layer and an ion buffer layer are formed in this order on a substrate, ions are implanted into the magnetic layer with the ion buffer layer interposed, and heat treatment is performed. A magnetic pattern forming method for modifying the magnetic characteristics of the ion implantation region is disclosed.

Further, for example, Patent Document 7 discloses a step of recording a burst signal by a magnetic head while positioning the magnetic head using a self-servo reference signal, and a position of the magnetic head from the position where the burst signal is recorded. While changing, the burst signal is reproduced by the magnetic head, and the radial position of the magnetic head on the magnetic disk is detected by reproducing the self-servo reference signal, thereby reproducing the position of the magnetic head and the burst signal. There is described a magnetic disk device provided with data track pitch determining means for executing a step of obtaining a relationship with a signal output and a step of determining a data track pitch based on the relationship.
JP 2004-164692 A JP 2004-178793 A JP 2004-178794 A Japanese Patent Laid-Open No. 5-205257 JP 2006-209952 A JP 2006-309841 A Japanese Patent Laid-Open No. 2005-10061

  However, in the conventional method of manufacturing a discrete track medium, since the accuracy of the pattern shape made of magnetically separated magnetic layers is insufficient and the yield is low, the yield is improved by forming the pattern shape of the magnetic layer with high accuracy. There was a need to improve. As a main cause of reducing the accuracy of the pattern shape of the magnetic layer, there is a resist pattern shape defect such as a variation in the thickness of the resist pattern used for forming the pattern shape made of the magnetic layer or edge sag.

  Here, the problem of the conventional magnetic recording medium will be described with reference to FIG. FIG. 4 is a plan view for explaining an example of a conventional discrete type magnetic recording medium, and FIG. 4A is a schematic view showing the whole of the discrete type magnetic recording medium, and FIG. FIG. 4 is an enlarged schematic view showing only a partial area of the discrete magnetic recording medium indicated by a rectangle in FIG.

As shown in FIGS. 4A and 4B, the magnetic recording medium 40 shown in FIG. 4 includes a data area 41 and a servo information area 42 on one surface of a disk-shaped substrate. It is. In FIG. 4A, an area indicated by a line extending radially from the center corresponds to the servo information area 42, and an area between the radial lines corresponds to the data area 41.
A data recording pattern 41a made of a magnetic layer constituting the data area 41 constitutes a magnetic recording track, and has an annular regular shape as shown in FIG. 4B.

As shown in FIG. 4B, the servo information area 42 is provided with a burst information area 43, an address information area 44, and a preamble information area 45.
In the burst information area 43, a burst pattern 43a is formed as burst information for positioning the magnetic head at the center of the magnetic recording track. The burst pattern 43a is made of a magnetic layer constituting the burst information area 43, and has a fine dot shape provided between adjacent magnetic recording tracks.

In the address information area 44, an address pattern 44a is formed as address information including track information indicating the address of the data area 41 and sector information. The address pattern 44a is made of a magnetic layer constituting the address information area 44, and has an irregular linear shape extending in a direction orthogonal to the data recording pattern 41a.
In the preamble information area 45, a preamble pattern 45a is formed as preamble information used for identifying a portion of the magnetic recording track that moves from the data area 41 to the servo information area 42. The preamble pattern 45a is made of a magnetic layer constituting the preamble information area 45, and has a linear shape with a uniform length extending in a direction orthogonal to the data recording pattern 41a.

  In the magnetic recording medium 40 shown in FIG. 4A, a magnetic head (not shown) that moves in the circumferential direction on the surface prepares to read the preamble information in the preamble information area 45 and read the address information. In the area 42, the address information of the data area 41 is read, the burst information of the burst information area 43 provided on the same circumference is read, the track position is finely adjusted, and then the information is read / written in the data area 41 Be able to.

  As shown in FIG. 4B, the density of each pattern 41a, 43a, 44a, 45a made of a magnetic layer is different in each of the data area 41, the burst information area 43, the address information area 44, and the preamble information area 45. ing. As described above, the magnetic layer of the discrete magnetic recording medium 40 has a complicated shape in which a plurality of pattern shapes having different pitches and pattern widths are mixed.

  In the manufacturing process of the magnetic recording medium 40 shown in FIG. 4, the causes of the defective shape of the resist pattern used when forming the pattern shape made of the magnetic layer are as follows: resist viscosity, resist curing temperature, curing time, humidity, Various patterning conditions, such as exposure time and exposure intensity, can be mentioned. These patterning conditions are appropriately determined according to the pattern shape of the magnetic layer.

However, when the magnetic layer has a complicated shape in which a plurality of pattern shapes are mixed like the magnetic recording medium 40 shown in FIG. 4, the optimum patterning conditions for forming the resist pattern are set as the pattern. It has been difficult to optimize so as not to cause variations in accuracy due to different shapes.
Specifically, for example, if the patterning conditions for forming the resist pattern are determined so as to correspond to the pattern shape of the data recording pattern 41a, the pattern shapes of the burst pattern 43a, the address pattern 44a, and the preamble pattern 45a are incomplete. turn into. If the patterning conditions for forming the resist pattern are determined so as to correspond to the pattern shapes of the burst pattern 43a, the address pattern 44a, and the preamble pattern 45a, the pattern shape of the data recording pattern 41a becomes incomplete.

  Thus, when the magnetic layer has a complicated shape, the patterning conditions for forming the resist pattern cannot be sufficiently optimized, and the magnetic layer formed on the magnetic recording medium cannot be optimized. It is difficult to form a highly accurate resist pattern that can form all the pattern shapes with sufficiently high accuracy. Therefore, in the conventional magnetic recording medium 40 shown in FIG. 4, it is difficult to form all the pattern shapes made of the magnetic layer with high accuracy.

In the magnetic recording medium 40 shown in FIG. 4, a burst pattern 43a, an address pattern 44a, and a preamble pattern 45a made of a magnetic layer are formed in the servo information area 42 as servo information. For this reason, the quality of the servo information read from the magnetic recording medium 40 by the magnetic head changes depending on the accuracy of the pattern shape made of the magnetic layer formed in the servo information area 42.
As described above, in the magnetic recording medium 40 shown in FIG. 4, since it is difficult to form all the pattern shapes made of the magnetic layer with high accuracy, the accuracy of the pattern shape formed in the servo information area 42 is high. In some cases, it was insufficient and high-quality servo information could not be obtained. For this reason, in the magnetic recording medium 40 shown in FIG. 4, there is a possibility that a reading failure or writing failure of the magnetic recording medium 40 by the magnetic head may occur, and it has been required to improve the reliability of the servo information.

The present invention has been made in view of such circumstances, and is written with highly reliable servo information. A resist pattern used when forming a pattern shape made of a magnetic layer is increased. It is an object of the present invention to provide a magnetic recording medium that can be formed with high accuracy and can be manufactured with high yield by forming all pattern shapes made of a magnetic layer with high accuracy using a highly accurate resist pattern.
In addition, according to the present invention, highly reliable servo information is written, a resist pattern can be formed with high accuracy, and the pattern shape of the magnetic layer can be formed with high accuracy using the resist pattern formed with high accuracy. It is an object of the present invention to provide a method for manufacturing a magnetic recording medium with a high yield.
It is another object of the present invention to provide a magnetic recording / reproducing apparatus that includes the magnetic recording medium of the present invention, can obtain highly reliable servo information, and can be manufactured with high yield.

In order to improve the shape defect of the resist pattern and form the pattern shape of the magnetic layer with high accuracy, the inventor has intensively studied as described below.
That is, the present inventor paid attention to the shape of the magnetic layer in consideration of the fact that the magnetic layer of the magnetic recording medium has a complicated shape is the main cause of reducing the accuracy of the resist pattern shape. And repeated examination. As a result, the present inventor has formed the servo information area in the conventional magnetic recording medium by magnetically writing the servo information in the magnetically separated annular magnetic recording pattern where information is read and written. By eliminating the need to form multiple pattern shapes, the magnetic layer shape can be made simple, consisting only of an annular pattern shape, and highly reliable servo information has been written. The present invention has been conceived by finding out that the present invention can be realized.

That is, the present invention adopts the following configuration.
(1) A magnetic recording medium comprising an annular magnetic recording pattern comprising a magnetic layer magnetically separated on a nonmagnetic substrate, wherein servo information is magnetically written in the magnetic recording pattern .
(2) The magnetic recording medium according to (1), wherein the servo information includes at least one selected from burst information, address information, and preamble information.

(3) forming a resist pattern on a magnetic layer provided on a nonmagnetic substrate, and using the resist pattern to form an annular magnetic recording pattern composed of the magnetic layer magnetically separated; And a servo information writing step of magnetically writing servo information to the magnetic recording pattern using a magnetic head.
(4) Before the servo information writing step, a step of magnetically transferring pre-servo information to the magnetic recording pattern using a magnetic transfer master carrier having a pre-servo information pattern on the surface is performed. The magnetic recording according to (3), wherein the servo information is written to the magnetic recording pattern by the magnetic head while the pre-servo information magnetically transferred to the magnetic recording pattern is read by the magnetic head. A method for producing a medium.
(5) The method for manufacturing a magnetic recording medium according to (3) or (4), wherein the pre-servo information is phase difference servo information.

  (6) A magnetic recording / reproducing apparatus comprising a magnetic recording medium and a magnetic head for recording / reproducing information on the magnetic recording medium, wherein the magnetic recording medium is described in (1) or (2) A magnetic recording / reproducing apparatus characterized by the above.

  According to the magnetic recording medium of the present invention, an annular magnetic recording pattern comprising a magnetic layer magnetically separated is provided on a nonmagnetic substrate, and servo information is magnetically written in the magnetic recording pattern. The shape of the magnetic layer can be a simple one consisting only of an annular pattern. Therefore, in the magnetic recording medium of the present invention, there is no need to form a pattern made of a magnetic layer as servo information in the servo information area, and a resist pattern used for forming a pattern shape made of a magnetic layer is formed. A highly accurate resist pattern can be formed by optimizing the patterning conditions. Therefore, in the magnetic recording medium of the present invention, all the pattern shapes formed of the magnetic layer formed on the nonmagnetic substrate can be formed with sufficiently high accuracy using a high-precision resist pattern. As a result, the magnetic recording medium of the present invention can be formed with high yield.

  Further, in the magnetic recording medium of the present invention, since servo information is magnetically written in the magnetic recording pattern, the pattern shape made of the magnetic layer is formed as in the case where the pattern made of the magnetic layer is formed as the servo information. The quality of the servo information does not change depending on the accuracy of the servo information, and high-accuracy servo information with excellent reliability can be written.

  The method of manufacturing a magnetic recording medium according to the present invention includes forming a resist pattern on a magnetic layer provided on a nonmagnetic substrate, and using the resist pattern, the annular magnetic layer separated from the magnetic layer. The method includes a step of forming a magnetic recording pattern and a servo information writing step of magnetically writing servo information to the magnetic recording pattern using a magnetic head. There is no need to form a pattern, and the shape of the magnetic layer can be made simple consisting of only an annular pattern shape. Therefore, according to the method for manufacturing a magnetic recording medium of the present invention, a highly accurate resist pattern can be formed under optimum patterning conditions, and a highly accurate magnetic recording pattern is formed using the highly accurate resist pattern. It becomes possible. As a result, a magnetic recording medium can be manufactured with a high yield.

  In the method for manufacturing a magnetic recording medium of the present invention, servo information is magnetically written to the magnetic recording pattern using a magnetic head, so that a magnetic layer is formed as a servo information as in the case of forming a pattern made of a magnetic layer. The quality of the servo information does not change depending on the accuracy of the pattern shape consisting of the above, and a magnetic recording medium on which highly accurate servo information excellent in reliability is written can be obtained.

  In addition, since the magnetic recording / reproducing apparatus of the present invention includes the magnetic recording medium of the present invention, the magnetic head can obtain servo information with excellent reliability and can be manufactured with high yield. .

  Next, the magnetic recording medium, the manufacturing method thereof, and the magnetic recording / reproducing apparatus of the present invention will be described in detail with reference to the drawings. In the drawings referred to in the following description, the sizes, thicknesses, dimensions, and the like of the respective parts shown in the drawings may differ from the dimensional relationships of the actual magnetic recording medium and magnetic recording / reproducing apparatus.

<Magnetic recording medium>
First, the magnetic recording medium of the present invention will be described with an example.
FIG. 1 is a plan view for explaining an example of the magnetic recording medium of the present invention, and FIG. 1A is an enlarged schematic view showing only a partial region of the magnetic recording medium. FIG. 1B is a process diagram for explaining a part of the manufacturing process of the magnetic recording medium shown in FIG. 1A. Only the same area as that shown in FIG. 1A is enlarged. It is an enlarged plan view shown.
FIG. 2I is a cross-sectional view for explaining the cross-sectional structure of the magnetic recording medium shown in FIG. 1, and is an enlarged schematic view of a part of the magnetic recording medium viewed from the radial direction. In FIG. 2I, only the substrate, the magnetic layer, and the protective film layer are shown for ease of explanation. 2A to 2H are process diagrams for explaining a part of the manufacturing process of the magnetic recording medium shown in FIG. 1, which is the same as the region shown in FIG. It is the expanded sectional view which expanded and showed only the field.

A magnetic recording medium 50 shown in FIG. 1A is provided with a data area 51 and a servo information area 52 on a disk-like nonmagnetic substrate 1. The data areas 51 are formed radially on the entire surface of the magnetic recording medium 50 at a predetermined angular interval from the rotation center of the magnetic recording medium 50, and as shown in FIG. The servo information area 52 is used. As shown in FIGS. 1A and 2I, the data area 51 and the servo information area 52 are provided with a magnetic recording pattern 51a composed of the magnetic layer 2 magnetically separated. The magnetic recording pattern 51a of this embodiment has a concave portion 51c and a convex portion 51b, and is adjacent because the magnetic properties of the magnetic layer 2 constituting the concave portion 51c are modified and demagnetized. The convex portions 51b are magnetically separated from each other. The width of the concave portion 51c is preferably about 10 to 100 nm, and the width of the convex portion 51b is preferably about 10 to 200 nm.
Here, the magnetic layer 2 is “magnetically separated” as long as it is magnetically separated at least on the surface of the magnetic layer 2 and may not be separated at the bottom of the magnetic layer 2. .

The magnetic recording pattern 51a has a simple concentric shape with respect to the center of rotation of the disk-shaped magnetic recording medium 50, and has an annular regular shape constituting a magnetic recording track having a width of about 50 nm. Is.
Servo information is magnetically written in the magnetic recording pattern 51 a arranged in the servo information area 52. The servo information written in the servo information area 52 may include at least one selected from burst information, address information, and preamble information. The burst information is information for positioning the magnetic head at the center of the magnetic recording track. The address information is information including track information and sector information indicating the address of the data area 51, and the preamble information is used to identify a location in the magnetic recording track that moves from the data area 51 to the servo information area 52. Information.

  In the present embodiment, a large number of data areas 51 provided on the nonmagnetic substrate 1 are positioned by servo information including burst information, address information, and preamble information written in the magnetic recording pattern 51a of the servo information area 52. Has been. In this embodiment, a magnetic head (not shown) that moves in the circumferential direction on the surface of the magnetic recording medium 50 has a preamble information, address information, and burst information in the corresponding data area 51 in the servo information area 52. The position of the magnetic head with respect to the position of the magnetic recording track formed of the magnetic recording pattern 51 a is finely adjusted using the burst information, and thereafter, the information can be read and written in the data area 51.

  Here, for example, when no information is written in the magnetic recording pattern 51a composed of the magnetic layer 2 separated magnetically, the magnetic recording pattern 51a is used to write servo information using the magnetic head. It is necessary to position the magnetic head in some way in the center of the narrow magnetic recording track. Further, since the magnetic recording pattern 51a constituting the magnetic recording track may be formed eccentrically with respect to the rotation center of the discrete type magnetic recording medium 50, the position of the magnetic head with respect to the magnetic recording track position is finely adjusted as needed. However, it is necessary to align the magnetic head with the center position of the magnetic recording track. In addition, it is necessary to detect the absolute position (coordinates) on the surface of the magnetic recording medium 50 by the magnetic head and to determine the address of the data area 51 based on the detected position.

  Further, in the magnetic recording medium 50 shown in FIG. 1, the magnetic layer 2 is formed on the nonmagnetic substrate 1 and the protective film layer 9 is formed on the magnetic layer 2 as shown in FIG. A lubricating layer (not shown in FIG. 2) is formed on the film layer 9. In this embodiment, the magnetic recording medium provided with the protective film layer and the lubricating layer will be described as an example. However, the protective film layer and the lubricating layer may not be provided.

  The nonmagnetic substrate 1 is made of an Al alloy substrate such as an Al—Mg alloy mainly composed of Al, ordinary soda glass, aluminosilicate glass, crystallized glass, silicon, titanium, ceramics, and various resins. Arbitrary things, such as a board | substrate, can be used. Among these, it is preferable to use a glass substrate such as an Al alloy substrate or crystallized glass or a silicon substrate as the nonmagnetic substrate 1. Moreover, the average surface roughness (Ra) of the nonmagnetic substrate 1 is preferably 1 nm or less, more preferably 0.5 nm or less, and even more preferably 0.1 nm or less.

The magnetic layer 2 is preferably formed from an alloy containing Co as a main component. The magnetic layer 2 may be an in-plane magnetic layer or a perpendicular magnetic layer, but is preferably a perpendicular magnetic layer in order to achieve a higher recording density.
For example, as the magnetic layer 2 for the in-plane magnetic layer, a laminated structure composed of a nonmagnetic CrMo underlayer and a ferromagnetic CoCrPtTa magnetic layer can be used.
Also, for example, as the magnetic layer 2 for the perpendicular magnetic layer, soft magnetic FeCo alloys (FeCoB, FeCoSiB, FeCoZr, FeCoZrB, FeCoZrBCu, etc.), FeTa alloys (FeTaN, FeTaC, etc.), Co alloys (CoTaZr, CoZrNB, CoB) Etc.), an orientation control film such as Pt, Pd, NiCr and NiFeCr provided as necessary, an intermediate film such as Ru provided as necessary, and a 60Co-15Cr-15Pt alloy or 70Co. -5Cr-15Pt-10SiO ₂ alloy can be used as the magnetic layer of the multilayer structure composed of a magnetic film made of.

  The film thickness of the magnetic layer 2 is determined so as to obtain a sufficient head input / output according to the type of magnetic material used for the magnetic layer 2 and the laminated structure. The magnetic layer 2 needs to have a film thickness of a certain degree or more in order to obtain a certain output when reproducing information from the magnetic recording medium 50. However, since various parameters representing the recording / reproducing characteristics of the magnetic recording / reproducing apparatus usually deteriorate as the output increases, it is necessary to set the film thickness of the magnetic layer 2 optimally. Specifically, the thickness of the magnetic layer 2 is preferably 3 nm to 20 nm, and more preferably 5 nm to 15 nm.

As the protective film layer 9, carbonaceous layers such as Diamond Like Carbon, hydrogenated carbon (HxC), nitrogenated carbon (CN), amorphous carbon, silicon carbide (SiC), etc., SiO ₂ , Zr Commonly used protective film layer materials such as ₂ O ₃ and TiN can be used. Further, the protective film layer 9 may be composed of two or more layers.
The thickness of the protective film layer 9 is preferably 10 nm or less. If the thickness of the protective film layer 9 exceeds 10 nm, the distance between the magnetic head and the magnetic layer 2 increases, and there is a risk that sufficient input / output signal strength cannot be obtained.

  Further, it is preferable to form a lubricating layer (not shown) on the protective film layer 9. Examples of the lubricant used for the lubricating layer include a fluorine-based lubricant, a hydrocarbon-based lubricant, and a mixture thereof. The thickness of the lubricating layer is usually 1 to 4 nm.

<Method of manufacturing magnetic recording medium>
Next, as a method for manufacturing the magnetic recording medium of the present invention, the method for manufacturing the magnetic recording medium of this embodiment shown in FIGS. 1A and 2I will be described in detail as an example.
First, as shown in FIG. 2A, a magnetic layer 2 is formed on a disk-like nonmagnetic substrate 1 by sputtering or the like.
Next, as shown in FIG. 2B, a mask layer 3 is formed on the magnetic layer 2. The mask layer 3 can be formed by sputtering or CVD.

The mask layer 3 is made of Ta, W, Ta nitride, W nitride, Si, SiO ₂ , Ta ₂ O ₅ , Re, Mo, Ti, V, Nb, Sn, Ga, Ge, As, and Ni. It is preferable to form with the material containing one or more selected. As the material of the mask layer 3, among the above materials, As, Ge, Sn, and Ga are preferably used, Ni, Ti, V, and Nb are more preferably used, and Mo, Ta, W, and C are used. Most preferred.
By using the mask layer 3 made of the above-mentioned material, the magnetic layer 2 has excellent shielding properties in a process of removing a part of the magnetic layer 2 by ion milling or the like, and the magnetic property of the mask layer 3 is increased. The formation accuracy of the recording pattern 51a can be improved. Furthermore, since the above material can be easily subjected to dry etching (reactive ion etching or reactive ion milling) using a reactive gas such as oxygen gas, the mask layer 3 is formed on the magnetic layer 2. By providing this, it is possible to reduce the residue on the magnetic layer 2 in the step of removing the resist layer described later, and to reduce the contamination of the surface of the magnetic layer 2.

Next, as shown in FIG. 2C, a resist layer 4 is formed on the mask layer 3. The resist layer 4 can be formed by a method of applying a resist on the mask layer 3 by a spin coat method.
The resist layer 4 is preferably made of a resist that is cured by irradiation with radiation. The radiation here is an electromagnetic wave of a broad concept such as heat rays, visible rays, ultraviolet rays, X-rays, gamma rays and the like. Moreover, as a resist hardened | cured by radiation irradiation, the thermosetting resin hardened | cured with a heat ray, the ultraviolet curing resin effective with an ultraviolet-ray, etc. are mentioned, for example. Examples of the ultraviolet curable resin include novolak resins, acrylic esters, and alicyclic epoxies.

  Next, the mask layer 3 and the resist layer 4 are patterned. In order to pattern the mask layer 3 and the resist layer 4, first, as shown in FIG. 2D, the negative pattern of the magnetic recording pattern 51a made of the magnetic layer 2 formed on the nonmagnetic substrate 1 is changed to a resist layer. 4 to form. The negative pattern formed here is a pattern in which a recess is formed in the resist layer 4 in a region corresponding to the separation region (recess 51c) constituting the magnetic recording pattern 51a.

  As a method for forming a negative pattern on the resist layer 4, an ordinary photolithography technique may be used. However, using a method for transferring a pattern shape using a stamp 5 for the resist layer 4 is advantageous in terms of work efficiency. To preferred. As a method for transferring the pattern shape to the resist layer 4 using the stamp 5, for example, as shown by the arrow in FIG. 2D, the pattern is formed by pressing the stamp 5 against the resist layer 4 with a predetermined pressure. There is a method of separating the stamp 5 from the resist layer 4 after the transfer.

  As the stamp 5, a pattern which is a concentric (a plurality of annular) patterns with respect to the center and has a shape corresponding to the magnetic recording pattern 51a is used. The material of the stamp 5 is not particularly limited as long as it has the hardness and durability necessary for transferring the pattern shape. For example, glass, Ni, resin, and the like can be preferably used. Specifically, for example, as the stamp 5, a metal plate with a pattern formed using a method such as electron beam drawing can be used.

In the present embodiment, the material used for the resist layer 4 is a material that is cured by radiation irradiation, and the pattern is transferred to the resist layer 4 at the time of transferring the pattern using the stamp 5 to the resist layer 4. After the step, it is preferable to cure the resist layer 4 by irradiating the resist layer 4 with radiation.
By using such a manufacturing method, the shape of the stamp 5 can be accurately transferred to the resist layer 4. Further, in the step of removing a part of the mask layer 3 which will be described later, it is possible to prevent sagging at the edge portion of the mask layer 3 and to remove a part of the magnetic layer 2 shown in FIG. The masking property of the mask layer 3 can be improved, and the formation accuracy of the magnetic recording pattern 51a can be improved.

Further, in the step of transferring the pattern using the stamp 5 to the resist layer 4 in the manufacturing method of the present embodiment, the resist layer 4 is pressed against the resist layer 4 while the fluidity of the resist layer 4 is high. Alternatively, the resist layer 4 may be cured by irradiating the resist layer 4 with the stamp 5 pressed, and then the stamp 5 may be separated from the resist layer 4. Such a manufacturing method is preferable because the shape of the stamp 5 can be transferred to the resist layer 4 with higher accuracy.
Further, when such a manufacturing method is used, the shape of the stamp 5 can be accurately transferred to the resist layer 4 and a highly accurate resist pattern can be formed, so that the magnetic characteristics of the magnetic layer 2 described later are modified. In this step, the coercive force and residual magnetization of the magnetic layer 2 can be reduced to the utmost, and it is possible to provide a magnetic recording medium having a high surface recording density without blurring of writing during magnetic recording. .

As a method of irradiating the resist layer 4 with radiation while the stamp 5 is pressed against the resist layer 4, for example, a method of irradiating radiation from the opposite side of the stamp 5, that is, the nonmagnetic substrate 1 side, or a material of the stamp 5 As a stamp material, a material that can transmit radiation is selected, a method of irradiating radiation from the stamp 5 side, a method of irradiating radiation from the side surface of the stamp 5, and a radiation having high conductivity with respect to a solid such as heat rays. Alternatively, a method of irradiating radiation by heat conduction from the nonmagnetic substrate 1 can be used.
In particular, UV curable resin is used as a resist material, and glass or resin having excellent UV transmittance is used as a stamp material, and ultraviolet rays are irradiated from the stamp 5 side in a state where the stamp 5 is pressed against the resist layer 4. Thus, it is preferable to cure the resist layer 4.

  Next, the resist layer 8 remaining after the negative pattern shown in FIG. 2D is formed and the mask layer 3 in the region corresponding to the concave separation region (the concave portion 51c) of the magnetic recording pattern 51a are removed. As a result, as shown in FIG. 2E, a mask composed of the mask layer 3 remaining in the region to be the convex portion 51b on the magnetic layer 2 and the resist pattern 4a which is the patterned resist layer 4 is formed. Is done.

The resist layer 8 remaining after the negative pattern is formed using the stamp 5 can be removed by dry etching such as reactive ion etching or ion milling.
The thickness of the resist layer 8 remaining after the negative pattern is formed is preferably in the range of 0 to 10 nm. By setting the thickness of the resist layer 8 in the above range, in the step of removing the mask layer 3 in the region corresponding to the concave separation region (recessed portion 51c) of the magnetic recording pattern 51a, the edge portion of the mask layer 3 is sagged. It can be prevented from occurring, and the shielding property of the mask layer 3 in the step of removing a part of the magnetic layer 2 shown in FIG. 2 (f) can be improved, and the formation accuracy of the magnetic recording pattern 51a can be improved.
Further, the mask layer 3 in a region corresponding to the concave separation region (recess 51c) of the magnetic recording pattern 51a can be removed by dry etching such as reactive ion etching or ion milling, for example.

  Next, as shown in FIG. 2F, the surface layer portion of the magnetic layer 2 in the region to be the concave separation region (the concave portion 51c) in the magnetic recording pattern 51a exposed by removing the mask layer 3 is 0.1 nm to For example, ion milling is performed with a milling ion 6 at a depth d in the range of 15 nm. Here, the depth d for removing a part of the surface layer of the magnetic layer 2 is preferably in the range of 0.1 nm to 15 nm, and more preferably in the range of 1 to 10 nm. If the depth d for removing the surface layer of the magnetic layer 2 is smaller than 0.1 nm, the effect of removing the magnetic layer 2 may not be sufficiently obtained. On the other hand, if the depth d for removing the surface layer of the magnetic layer 2 is greater than 15 nm, the surface smoothness of the magnetic recording medium 50 deteriorates, and the flying characteristics of the magnetic head in the magnetic recording / reproducing apparatus using the magnetic recording medium 50 May be reduced.

  When a part of the surface layer of the magnetic layer 2 is removed before the step of modifying the magnetic characteristics of the magnetic layer 2 exposed by removing the mask layer 3 as in this embodiment, the surface layer of the magnetic layer 2 is removed. The contrast of the magnetic recording pattern 51a becomes clearer and the S / N of the magnetic recording medium 50 can be improved as compared with the case where the magnetic characteristics of the magnetic layer 2 are modified without removing a part thereof. The reason is that by removing a part of the surface layer of the magnetic layer 2, the surface of the magnetic layer 2 exposed by removing the mask layer 3 is cleaned and activated, so that the magnetic characteristics of the magnetic layer 2 are improved. The reactivity of the reactive plasma and reactive ions with the magnetic layer 2 during the modification is improved, and defects such as vacancies are introduced into the surface layer of the magnetic layer 2 to modify the magnetic properties of the magnetic layer 2. This is probably because reactive ions easily enter the magnetic layer 2 through defects in the surface layer.

Next, as shown in FIG. 2 (f), the magnetic layer 2 in the region 7 where the surface layer portion has been removed is exposed to reactive plasma or reactive ions to modify the magnetic properties of the magnetic layer 2. The region in which the magnetic characteristics of the magnetic layer 2 are modified is a region that magnetically separates the plurality of magnetic recording tracks formed of the magnetic recording pattern 51a.
Here, the modification of the magnetic layer 2 for forming the magnetic recording pattern 51a partially changes the magnetic characteristics such as coercive force and residual magnetization of the magnetic layer 2 in order to pattern the magnetic layer 2. Means that. In the present embodiment, by modifying the magnetic layer 2, the coercive force of the magnetic layer 2 is reduced and the residual magnetization is reduced.

Examples of the reactive plasma used when modifying the magnetic properties of the magnetic layer 2 include inductively coupled plasma (ICP) and reactive ion plasma (RIE).
Inductively coupled plasma is a high-temperature plasma obtained by applying a high voltage to a gas to generate plasma and generating Joule heat due to eddy currents by a high-frequency fluctuating magnetic field inside the plasma. Inductively coupled plasma has a high electron density, and can improve the magnetic properties of a magnetic film having a large area with high efficiency compared to the case of using a conventional ion beam.

The reactive ion plasma is a highly reactive plasma in which a reactive gas such as O ₂ , SF ₆ , CHF ₃ , CF ₄ , or CCl ₄ is added to the plasma. By using the reactive ion plasma, the modification of the magnetic properties of the magnetic film 2 can be realized with higher efficiency.
Examples of the reactive ions that modify the magnetic properties of the magnetic layer 2 include the reactive ions existing in the inductively coupled plasma and the reactive ion plasma described above.

  The method for manufacturing a magnetic recording medium of the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, a magnetic layer magnetically separated is formed by modifying a part of the surface layer of the magnetic layer 2, but the magnetic layer is physically processed to form a recess in the magnetic layer. After forming and filling the recess with a nonmagnetic material, a magnetic layer magnetically separated may be formed by a method of smoothing the surface of the magnetic recording medium.

  After modifying the magnetic characteristics of a part of the magnetic layer 2 in this way, the resist pattern 4a and the mask layer 3 provided on the magnetic layer 2 are removed as shown in FIG. The resist pattern 4a and the mask layer 3 are preferably removed using a technique such as dry etching, reactive ion etching, ion milling, or wet etching.

  After removing the resist pattern 4a and the mask layer 3, the magnetic layer 2 is irradiated with an inert gas 11 such as Ar as shown in FIG. It is preferable to remove by etching. Thus, even if the surface of the magnetic layer 2 is roughened by modifying a part of the magnetic characteristics of the magnetic layer 2, the surface of the roughened magnetic layer 2 is removed. be able to.

Next, as shown in FIG. 2 (i), it is preferable to form a protective film layer 9 on the magnetic layer 2. Usually, the protective film layer 9 is formed by sputtering or CVD.
Furthermore, it is preferable to form a lubricating layer (not shown) on the protective film layer 9.

  Subsequently, the preservo information is magnetically transferred to the magnetic recording pattern 51a of the magnetic recording medium 50 using the magnetic transfer master carrier. The pre-servo information is information that enables the magnetic head to be positioned at the center of the magnetic recording track composed of the magnetic recording pattern 51a of the magnetic recording medium 50, and the magnetic head determines the absolute position of the magnetic head on the surface of the magnetic recording medium 50. This is information that can be detected.

In the present embodiment, as shown in FIG. 1B, by forming a phase difference servo information pattern 55a as a pre-servo information pattern in the magnetic recording pattern 51a of the data area 51 of the magnetic recording medium 50, pre-servo information is obtained. The phase difference servo information was magnetically transferred. In FIG. 1B, the magnetic recording pattern 51a provided in the data area 51 and the servo information area 52 is not shown for easy understanding of the drawing.
The phase difference servo information is a magnetic head in the magnetic recording track of the magnetic recording pattern 51a based on the phase of an intermittent signal determined by the linear pattern interval of the phase difference servo information pattern 55a that changes in the radial direction of the magnetic recording medium 50. This is information for detecting the position of.
In this embodiment, the phase difference servo pattern is formed as the pre-servo information. However, the pre-servo information is not limited to the phase difference servo pattern, and the accurate position to the track position formed on the magnetic recording medium is not limited. Any servo pattern other than the phase difference servo pattern can be used as pre-servo information as long as it is a servo pattern that does not require alignment and can be easily aligned.

As shown in FIG. 1B, the phase difference servo information pattern 55 a is formed on the magnetic recording pattern 51 a in the pre-servo information area 55 of the magnetic recording medium 50. The pre-servo information area 55 is an area in contact with one of the boundaries with the servo information area 52 arranged on both sides of the data area 51 in the circumferential direction. Although the number of pre-servo information areas 55 is not particularly limited, for example, 255 positions can be provided in the radial direction.
As shown in FIG. 1B, the phase difference servo information pattern 55a is composed of a plurality of linear patterns formed to be inclined in a direction intersecting the circumferential direction and the radial direction. The inclination direction of the plurality of linear patterns constituting the phase difference servo information pattern 55a is the direction of the in-line angle of the magnetic head (the angle between the line connecting the magnetic head and the pivot (rotation center of the magnetic head) and the head slider). The magnetic head is slightly inclined with respect to the direction of the skew angle of the magnetic head (the inclination angle of the magnetic head with respect to the circumferential direction). Further, the interval between the linear patterns is uniform in the circumferential direction of the magnetic recording medium 50, but is different in the radial direction of the magnetic recording medium 50, and gradually increases from the center toward the outside. .

In the present embodiment, a magnetic transfer master carrier having a phase difference servo information pattern that is a pre-servo information pattern on the surface in contact with the magnetic recording medium 50 is used. On the master carrier for magnetic transfer, a pattern shape corresponding to the phase difference servo information pattern 55a shown in FIG. 1B provided on the magnetic recording medium 50 is imprinted as a phase difference servo information pattern.
The material of the master carrier for magnetic transfer is not particularly limited as long as it has the hardness and durability necessary for magnetically transferring the pattern shape of the phase difference servo information pattern to the magnetic recording medium 50. Si, glass, ceramics, or Ni can be preferably used.

A method for imprinting the phase difference servo information pattern on the surface of the magnetic transfer master carrier is not particularly limited, but the phase difference servo information pattern of the magnetic recording medium 50 is formed on the material to be the magnetic transfer master carrier by a thin film forming technique. A method of embedding a soft magnetic material made of a high magnetic permeability material such as FeCo or CoNi or a ferromagnetic material made of FePt or the like in a shape corresponding to 55a can be used.
The soft magnetic material or the ferromagnetic material embedded in the surface of the magnetic transfer master carrier may be embedded so as to be the same height as the surface of the magnetic transfer master carrier, or the soft magnetic material may be embedded in the surface of the magnetic transfer master carrier. After embedding the body and the ferromagnetic body, the surface on the side in contact with the magnetic recording medium 50 is precisely polished as necessary, and the surface of the magnetic transfer master carrier and the embedded soft magnetic body or ferromagnetic body The height may be the same height.

Further, the method of imprinting the phase difference servo information pattern on the surface of the magnetic transfer master carrier may be a method of forming on a metal plate made of nickel or the like using a method such as electron beam drawing.
Further, a lubricating layer formed by applying a lubricant may be provided on the surface of the magnetic transfer master carrier on the side in contact with the magnetic recording medium 50.

In the present embodiment, since the phase difference servo information is used as the pre-servo information magnetically transferred to the magnetic recording pattern 51a of the magnetic recording medium 50, the pre-servo information pattern formed on the surface of the magnetic transfer master carrier is shown in FIG. A phase difference servo information pattern corresponding to the phase difference servo information pattern 55a shown in 1 (b) is formed.
The phase difference servo information pattern 55a magnetically transferred to the magnetic recording pattern 51a has a simple shape composed of a plurality of linear patterns formed to be inclined in the direction intersecting the circumferential direction and the radial direction. In addition, the magnetic recording pattern 51 a has an annular shape that is simple concentric with respect to the rotation center of the magnetic recording medium 50. For this reason, in this embodiment, the alignment of the magnetic transfer master carrier and the magnetic recording medium 50 can be performed only by aligning the center of the magnetic transfer master carrier with the center of the magnetic recording medium 50, and the magnetic There is no need to align the recording medium 50 in the circumferential direction. Therefore, when the pre-servo information (phase difference servo information) is magnetically transferred to the magnetic recording pattern 51a of the magnetic recording medium 50, the magnetic recording pattern 51a and the phase difference servo information pattern formed on the surface of the magnetic transfer master carrier are used. There is no need for alignment. Therefore, when the phase difference servo information is used as the preservo information, the preservo information can be easily magnetically transferred to the magnetic recording pattern 51a of the magnetic recording medium 50 using the magnetic transfer master carrier.

In this embodiment, in order to magnetically transfer the phase difference servo information to the magnetic recording pattern 51a of the magnetic recording medium 50 using the magnetic transfer master carrier, first, the position of the magnetic transfer master carrier with respect to the magnetic recording medium 50 is determined. The surfaces of the magnetic recording medium 50 and the magnetic transfer master carrier are brought into contact with each other. A DC magnetic field is applied in a direction perpendicular to the contact surface between the magnetic recording medium 50 and the magnetic transfer master carrier from the back side of the magnetic transfer master carrier. As a result, a phase difference servo information pattern 55a is formed in the magnetic recording pattern 51a of the pre-servo information area 55 of the magnetic recording medium 50, and the phase difference servo information is transferred from the magnetic transfer master carrier to the magnetic recording pattern 51a of the magnetic recording medium 50. Magnetically transferred.
The magnetic transfer master carrier used in this embodiment does not need to have magnetism. When the magnetic transfer master carrier is a magnetically permeable material, a magnetic field is applied from the back side of the magnetic transfer master carrier while the magnetic transfer master carrier is in contact with the surface of the magnetic recording medium 50. As a result, the phase difference servo information pattern formed on the magnetic transfer master carrier can be transferred to the magnetic recording pattern 51 a of the magnetic recording medium 50.

Next, pre-servo information (phase difference servo information) magnetically transferred to the magnetic recording pattern 51a of the magnetic recording medium 50 is read into the magnetic head, and at the same time, the servo of the same magnetic recording track as the pre-servo information read by the magnetic head is read. Servo information including at least one selected from burst information, address information, and preamble information is magnetically written into the magnetic recording pattern 51a in the information area 52. That is, by causing the magnetic head to read pre-servo information, the magnetic head can detect its absolute position on the surface of the magnetic recording medium 50 based on the pre-servo information, and the magnetic head is located at the center of the magnetic recording track formed of the magnetic recording pattern 51a. And servo information is written in the servo information area 52 on the surface of the magnetic recording medium 50.
Note that when writing servo information to the magnetic recording pattern 51a, a known servo writer having a magnetic head can be used.

In this embodiment, after servo information is written in the magnetic recording pattern 51a, the phase difference servo information pattern 55a imprinted in the pre-servo information area 55 of the magnetic recording medium 50 is erased, and the pre-servo information ( It is preferable to delete the phase difference servo information). As a result, the magnetic recording pattern 51 a in the pre-servo information area 55 can be used as the data area 51.
The pre-servo information is used when servo information is written to the magnetic recording pattern 51a, and is unnecessary after the servo information is written to the magnetic recording pattern 51a. For this reason, as described above, after servo information is written in the magnetic recording pattern 51a, the preservo information magnetically transferred to the magnetic recording pattern is erased, so that an area usable as the data area 51 on the magnetic recording medium 50 is obtained. Although it is preferable to make it wide, it is not necessary to erase the pre-servo information in order to simplify the manufacturing process.
In this way, the discrete magnetic recording medium 40 shown in FIGS. 1 to 3 is manufactured.

In the above-described embodiments, the case where a pre-servo information pattern imprinted is used as an example of the magnetic transfer master carrier. However, as the magnetic transfer master carrier, a preamble pattern, an address pattern, a burst is used. You may use what the pattern was stamped. In this case, it is not necessary to magnetically write servo information to the magnetic recording pattern 51a in the servo information area 52 by the magnetic head, and the manufacturing process can be simplified.
However, when a magnetic transfer master carrier with a preamble pattern, an address pattern, or a burst pattern is used, in order to perform magnetic transfer, the magnetic transfer master carrier must be spaced from the pattern on the magnetic transfer master carrier. It is necessary to perform alignment to match the position with the annular magnetic recording pattern 51a formed concentrically. For this reason, when using a master pattern with a preamble pattern, an address pattern, or a burst pattern as a magnetic transfer master carrier, compared with using a pre-servo information pattern as a magnetic transfer master carrier. The alignment for magnetic transfer becomes technically difficult, and the accuracy of alignment of the magnetic transfer master carrier with respect to the magnetic recording medium 50 may be insufficient.

The magnetic recording medium 50 of the present embodiment is provided with an annular magnetic recording pattern 51a composed of a magnetic layer 2 magnetically separated on a nonmagnetic substrate 1, and servo information is magnetically written in the magnetic recording pattern 51a. Therefore, the shape of the magnetic layer 2 can be made simple only consisting of an annular pattern shape.
Therefore, in the magnetic recording medium 50 of this embodiment, it is not necessary to form a pattern made of a magnetic layer as servo information in the servo information area. Therefore, it is possible to optimize the patterning conditions for forming the resist pattern 4a used when forming the pattern shape made of the magnetic layer 2, and to form the resist pattern 4a with high accuracy. As a result, all the pattern shapes formed of the magnetic layer 2 formed on the nonmagnetic substrate 1 can be formed with sufficiently high accuracy and high yield using a high-precision resist pattern.

  Further, in the magnetic recording medium 50 of the present embodiment, servo information is magnetically written in the magnetic recording pattern 51a, so that the servo information is formed from the magnetic layer as in the case where a pattern made of a magnetic layer is formed. The quality of the servo information does not change depending on the accuracy of the pattern shape, and the servo information with high accuracy and excellent reliability is written.

Further, in the method of manufacturing the magnetic recording medium 50 according to the present embodiment, a resist pattern 4a is formed on the magnetic layer 2 provided on the nonmagnetic substrate 1, and magnetically separated using the resist pattern 4a. The method includes a step of forming an annular magnetic recording pattern 51a made of layer 2 and a servo information writing step of magnetically writing servo information to the magnetic recording pattern 51a using a magnetic head. It is not necessary to form a pattern made of a magnetic layer as information, the resist pattern 4a can be formed under optimum patterning conditions, and a highly accurate resist pattern 4a can be formed.
Therefore, according to the method for manufacturing the magnetic recording medium 50 of the present embodiment, the high-precision resist pattern 4a can be used to form the high-precision magnetic recording pattern 51a, which can be manufactured with high yield.

  Further, in the method of manufacturing the magnetic recording medium 50 of the present embodiment, before magnetically writing servo information to the magnetic recording pattern 51a, a magnetic recording pattern is obtained using a magnetic transfer master carrier having a preservo information pattern on the surface. In the step of magnetically transferring the pre-servo information to the magnetic recording pattern 51a and performing the magnetic transfer of the pre-servo information to the magnetic recording pattern 51a, the magnetic head uses the magnetic head to read the pre-servo information magnetically transferred to the magnetic recording pattern 51a. Since the servo information is written in the recording pattern 51a, the servo information can be written into the magnetic recording pattern 51a easily and at high speed more easily than in the case where the pre-servo information is not magnetically transferred to the magnetic recording pattern 51a. .

Further, in the method for manufacturing the magnetic recording medium 50 of the present embodiment, since the pre-servo information is phase difference servo information, a plurality of linear patterns formed by being inclined in the direction intersecting the circumferential direction and the radial direction are used. Magnetic transfer of the pre-servo information to the magnetic recording pattern by magnetically transferring the phase difference servo information to the magnetic recording pattern 51a using a magnetic transfer master carrier having a phase difference servo information pattern having a simple shape Can do.
For this reason, the alignment of the magnetic transfer master carrier and the magnetic recording medium 50 can be performed only by aligning the center of the magnetic transfer master carrier with the center of the magnetic recording medium 50, and the magnetic transfer master carrier is used. Thus, the pre-servo information can be easily magnetically transferred to the magnetic recording pattern 51a of the magnetic recording medium 50.

<Magnetic recording / reproducing device>
Next, an example of the magnetic recording / reproducing apparatus of the present invention will be described.
FIG. 3 is a schematic perspective view showing a hard disk drive as an example of the magnetic recording / reproducing apparatus of the present invention. The hard disk drive shown in FIG. 3 includes a discrete magnetic recording medium 50 shown in FIG. 1, a medium driving unit 34 that drives the magnetic recording medium 50 in the recording direction, a magnetic head 27 that includes a recording unit and a reproducing unit, A head drive unit 28 for moving the magnetic head 27 relative to the magnetic recording medium 50, and a recording / reproducing signal system 29 (recording / reproducing signal processing) for performing signal input to the magnetic head 27 and output signal reproduction from the magnetic head 27 Means).

  Since the hard disk drive of the present embodiment includes the discrete magnetic recording medium 50 shown in FIG. 1, the magnetic head 27 can obtain highly reliable servo information and can be manufactured with high yield. It will be a thing.

Hereinafter, the present invention will be specifically described with reference to examples.
(Example)
First, a disk-shaped hard disk (HD) glass substrate was placed in a vacuum chamber and evacuated to 1.0 × 10 ⁻⁵ Pa or less. As a glass substrate, a _{Li 2 Si 2 O 5, Al} 2 O 3 -K 2 O, Al 2 O 3 -K 2 O, MgO-P 2 O 5, Sb 2 O 3 -ZnO constituents It was made of crystallized glass and had an outer diameter of 65 mm, an inner diameter of 20 mm, and an average surface roughness (Ra) of 2 angstroms.

Using a DC sputtering method, a backing layer made of FeCoB soft magnetic film, an intermediate layer made of Ru, and a magnetic film made of 70Co-5Cr-15Pt-10SiO ₂ alloy are laminated in this order on the glass substrate. A magnetic layer was formed. Subsequently, a sputtering method is used to stack a mask layer made of Ta on the magnetic layer, and a resist is applied on the mask layer by a spin coating method to form a resist layer made of a novolak resin that is an ultraviolet curable resin. did.
The thicknesses of the respective layers were a backing layer 60 nm, an intermediate layer 10 nm, a magnetic film 15 nm, a mask layer 60 nm, and a resist layer 100 nm.

Next, a stamp made of glass having an ultraviolet transmittance of 95% or more on which a pattern corresponding to the magnetic recording pattern of the magnetic recording medium is formed is pressed against the resist layer at a pressure of 1 MPa (about 8.8 kgf / cm ² ). The pattern was transcribed. Subsequently, ultraviolet rays having a wavelength of 250 nm were irradiated from the top of the stamp for 10 seconds to cure the resist layer. Thereafter, the stamp was separated from the resist layer.
The negative pattern of the resist layer corresponding to the magnetic recording pattern transferred in this way was an annular shape having a convex portion width of 120 nm and a concave portion width of 60 nm.

Next, the resist layer remaining in the recess after the negative pattern was formed was removed by dry etching. Dry etching conditions were O ₂ gas of 40 sccm, pressure of 0.3 Pa, high-frequency plasma power of 300 W, DC bias of 30 W, and etching time of 10 seconds.
Thereafter, the mask layer in the region corresponding to the concave separation region of the magnetic recording pattern exposed by removing the resist layer was removed by dry etching. The dry etching conditions were CF ₄ gas 50 sccm, pressure 0.6 Pa, high frequency plasma power 500 W, DC bias 60 W, and etching time 30 seconds. As a result, a mask composed of a mask layer remaining in a region to be a convex portion on the magnetic layer and a resist pattern which is a patterned resist layer was formed.

Thereafter, the surface layer portion of the magnetic layer exposed by removing the mask layer was removed by ion milling. Ar ions were used for ion milling. The amount of ions in ion milling was 5 × 10 ¹⁶ atoms / cm ² and the acceleration voltage was 20 keV. The depth of the surface layer of the magnetic layer removed by ion milling was 0.1 nm.

Next, the magnetic layer in the region where the surface layer portion was removed was exposed to reactive plasma to modify the magnetic properties of the magnetic layer. For this reactive plasma treatment, an inductively coupled plasma apparatus NE550 manufactured by ULVAC was used. As the gas and conditions used for generating plasma, 90 cc / min of O ₂ was used, the input power for generating plasma was 200 W, the pressure in the apparatus was 0.5 Pa, and the magnetic layer was treated for 300 seconds.

After modifying the magnetic properties of the magnetic layer, the resist pattern and the mask layer provided on the magnetic layer were removed by dry etching to expose the magnetic recording pattern.
Thereafter, a protective film layer made of carbon and having a thickness of 5 nm was formed on the exposed surface of the magnetic recording pattern by a CVD method. Subsequently, a lubricant was applied on the protective film layer to form a lubricant layer.

  Subsequently, by using the magnetic transfer master carrier, a phase difference servo information pattern is formed on the magnetic recording pattern of each preservo information area provided in 255 radial directions of the magnetic recording medium, thereby obtaining the position of the preservo information. The phase difference servo information was magnetically transferred. The phase difference servo information pattern is composed of a linear pattern formed with a slight inclination with respect to the direction of the skew angle of the magnetic head (the inclination angle of the magnetic head with respect to the circumferential direction), and the width of the linear pattern. Was about 2 μm.

  As the master carrier for magnetic transfer, one formed by the following method was used. That is, after forming a phase difference servo information pattern consisting of a recess having a depth of 0.2 μm on one main surface of a non-magnetic substrate made of Si by using a photolithography technique and an etching technique, phase difference servo information is obtained. A ferromagnetic layer made of FePt was formed on the surface where the pattern was formed by sputtering, and the surface was etched and flattened.

  Then, by aligning the center of the magnetic transfer master carrier with the center of the magnetic recording medium, the position of the magnetic transfer master carrier with respect to the magnetic recording medium is aligned, and the magnetic transfer master carrier is placed on the surface of the magnetic recording medium. A direct-current magnetic field was applied in a direction perpendicular to the contact surface between the magnetic recording medium and the magnetic transfer master carrier from the back side of the magnetic transfer master carrier using a magnetic field applying device. As a result, a phase difference servo information pattern is formed on the magnetic recording pattern in the pre-servo information area of the magnetic recording medium, and the phase difference servo information is magnetically transferred as pre-servo information from the magnetic transfer master carrier to the magnetic recording pattern of the magnetic recording medium. It was.

  After that, the magnetic recording medium on which the phase difference servo information is magnetically transferred is installed in the servo writer, and the phase difference servo information read by the magnetic head is simultaneously read while the phase difference servo information is read by the magnetic head of the servo writer. Magnetic information on the magnetic recording pattern of the servo information area of the magnetic recording track includes preamble information (width about 0.5 μm), address information (width about 1 μm), and burst information (width about 0.5 μm) in this order as servo information. I wrote. Thereafter, the phase difference servo information was magnetically erased, and the pre-servo information area, which was the area where the phase difference servo information was written, was used as the data area.

The magnetic recording medium produced by the above method was measured for coercive force, electromagnetic conversion characteristics (SNR and 3T-squash), and head flying height (glide avalanche).
Evaluation of electromagnetic conversion characteristics was performed using a spin stand. As the magnetic head for evaluation, a perpendicular recording head for recording and a TuMR head (Tunneling Magneto Resistive head) for reading were used, and the SNR value and 3T-squash when a 750 kFCI signal was recorded were measured. Here, 3T-squash (three-track squash) means that after recording a signal on the center track, the signal is recorded on both sides of the center, and the signal intensity (ratio of the center track before and after recording the signal on both sides) (%)).

As a result, the magnetic recording medium manufactured by the above method had an SNR of 13.5 dB and a 3T-squash of 85%, and was excellent in electromagnetic conversion characteristics.
The coercive force was 3800 (Oe), and the head flying height was 6 nm.

  According to the present invention, it is possible to manufacture a magnetic recording medium having a magnetic recording pattern with a high manufacturing yield.

FIG. 1 is a plan view for explaining an example of the magnetic recording medium of the present invention, and FIG. 1A is an enlarged schematic view showing only a partial region of the magnetic recording medium. FIG. 1B is a process diagram for explaining a part of the manufacturing process of the magnetic recording medium shown in FIG. 1A. Only the same area as that shown in FIG. 1A is enlarged. It is an enlarged plan view shown. FIG. 2I is a cross-sectional view for explaining the cross-sectional structure of the magnetic recording medium shown in FIG. 1, and is an enlarged schematic view of a part of the magnetic recording medium viewed from the radial direction. 2A to 2H are process diagrams for explaining a part of the manufacturing process of the magnetic recording medium shown in FIG. 1, which is the same as the region shown in FIG. It is the expanded sectional view which expanded and showed only the field. FIG. 3 is a schematic perspective view showing a hard disk drive as an example of the magnetic recording / reproducing apparatus of the present invention. FIG. 4 is a plan view for explaining an example of a conventional discrete type magnetic recording medium, and FIG. 4A is a schematic view showing the whole of the discrete type magnetic recording medium, and FIG. FIG. 4 is an enlarged schematic view showing only a partial area of the discrete magnetic recording medium indicated by a rectangle in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Nonmagnetic substrate, 2 ... Magnetic layer, 3 ... Mask layer, 4 ... Resist layer, 4a ... Resist pattern, 5 ... Stamp, 6 ... Milling ion, 8 ... Resist layer, 9 ... Protective film layer, 11 ... Inactive Gas 27, magnetic head, 28 head drive unit, 29 recording / reproduction signal system, 34 medium drive unit, 40, 50 magnetic recording medium, 41, 51 data area, 41a data recording pattern, 42, 52 ... servo information area, 43 ... burst information area, 43a ... burst pattern, 44 ... address information area, 44a ... address pattern, 45 ... preamble information area, 45a ... preamble pattern, 51a ... magnetic recording pattern, 51b ... convex, 51c ... recess, 55 ... pre-servo information area, 55a ... phase difference servo information pattern.

Claims (6)

An annular magnetic recording pattern comprising a magnetic layer magnetically separated on a nonmagnetic substrate is provided,
A magnetic recording medium, wherein servo information is magnetically written on the magnetic recording pattern.   The magnetic recording medium according to claim 1, wherein the servo information includes at least one selected from burst information, address information, and preamble information. Forming a resist pattern on a magnetic layer provided on a nonmagnetic substrate, and using the resist pattern to form an annular magnetic recording pattern composed of the magnetic layer magnetically separated; and
And a servo information writing step of magnetically writing servo information to the magnetic recording pattern using a magnetic head. Before the servo information writing step, using a magnetic transfer master carrier having a pre-servo information pattern on the surface, performing a step of magnetically transferring pre-servo information to the magnetic recording pattern,
2. The servo information writing step, wherein the servo information is written to the magnetic recording pattern by the magnetic head while the pre-servo information magnetically transferred to the magnetic recording pattern is read by the magnetic head. 4. A method for producing a magnetic recording medium according to item 3.   5. The method of manufacturing a magnetic recording medium according to claim 3, wherein the pre-servo information is phase difference servo information. A magnetic recording / reproducing apparatus comprising a magnetic recording medium and a magnetic head for recording / reproducing information on the magnetic recording medium,
A magnetic recording / reproducing apparatus, wherein the magnetic recording medium is the magnetic recording medium according to claim 1.

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