JP2003196815A - Magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording medium wherein magnetic characteristics of a cell for a data signal storage area are different from magnetic characteristics of at least a partial cell for a tracking servo signal storage area. <P>SOLUTION: The magnetic recording medium is constituted by including a data signal storage area 1035 which has a first magnetic substance cell 1031, and a tracking servo signal storage area 1036 which has a second magnetic substance cell 1034. The first and second magnetic substance cells are isolated from each other by a nonmagnetic substance 1037. The first and second magnetic substance cells 1031 and 1034 are different from each other in magnetic characteristics. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a magnetic recording medium capable of recording and reproducing information.

[0002]

2. Description of the Related Art With the recent dramatic increase in the amount of information,
Information recording devices such as magnetic recording devices are required to have a large capacity. Under such circumstances, a hard disk drive (HDD) is always used as an information recording device for a computer because of its overwhelmingly low cost bit unit price and high data transfer rate as compared with other recording methods. Has been.

In recent years, the recording density of hard disks is 1 annually.
It has achieved an astonishing figure of an increase of 00%, and at the latest experimental level, it is 50 Gb / in ² (7.8 Gb / c).
There is also a report that it recorded m ² ). However, in spite of such a situation, it is desired to further increase the recording density of the hard disk device.

A magnetic recording medium used in a hard disk device is generally disk-shaped (a ring-shaped area is called a track). Then, the tracks are divided into areas in which a plurality of tracking servo signals are stored (hereinafter referred to as "tracking servo signal storage areas"). In the track, the area divided by the tracking servo signal storage area is a data signal area (hereinafter referred to as "data signal storage area").

The movement of the magnetic head for writing or reading data is performed as follows. The servo signal stored in the tracking servo signal storage area is read by the magnetic head, and the head actuator is controlled according to the signal to move the magnetic head to a target position. In order to record the tracking servo signal on the recording medium, generally, after the magnetic recording medium is manufactured, the tracking servo signal is written on the recording medium using a servo writer device.

However, when the track width is reduced to increase the track density (recording density), a high level control of the signal writing position is required, so the servo writer device has a mechanism for performing accurate positioning. It must be provided, and as a result, the price of the servo writer device increases. In addition, since it is necessary to write signals on many tracks in order to increase the track density, the time for writing the tracking servo signal is further increased, and the manufacturing cost is increased.

As described above, it is necessary to form the servo signal area using the servo writer device capable of highly accurate position control after the magnetic recording medium is manufactured, because the magnetic characteristics of the data area and the servo area are the same. It is due to

In order to solve such a problem, FIG.
As shown in FIG. 3, a recess 17 is formed in the substrate 12, the magnetic layer 15 is formed in the recess 17, and the magnetic recording layer 13 is continuously formed on the recess 17, thereby changing the thickness of the magnetic layer. A method of recording a tracking servo signal is disclosed (for example, refer to Patent Document 1).

[0009]

[Patent Document 1] Japanese Patent Application Laid-Open No. 9-167336 (3rd
(Page, Figure 1)

[0010]

Therefore, the present invention is directed to a magnetic recording medium in which the magnetic characteristics of the cells for the data signal storage area are different from the magnetic characteristics of at least a part of the cells for the tracking servo signal storage area. And its manufacturing method.

[0011]

A magnetic recording medium according to the present invention is a data signal storage area having a first magnetic cell,
And a tracking servo signal storage area having a second magnetic substance cell, and the first magnetic substance cell and the second magnetic substance cell are provided.
The magnetic cells are isolated from each other by a non-magnetic material, and the magnetic characteristics of the first magnetic cell and the second magnetic cell are different from each other.

The first and second magnetic substance cells preferably have a columnar shape. The tracking servo signal storage area may include the first magnetic cell. A magnetic recording medium according to the present invention is a magnetic recording medium having a tracking servo signal storage area formed by including a first magnetic substance cell and a second magnetic substance cell, and the first magnetic substance cell And the second magnetic substance cell are separated by a non-magnetic substance, and the first magnetic substance cell and the second magnetic substance cell have different magnetic characteristics from each other.

The magnetic recording medium according to the present invention is a magnetic recording medium having magnetic cells separated from each other by a non-magnetic material, and a minimum unit magnetic recording portion constituted by the magnetic cells is used as a unit. A magnetic signal cell is divided and has a data signal storage area in which a plurality of minimum unit magnetic recording sections are arranged, and a tracking servo signal storage area in which a plurality of minimum unit magnetic recording sections are arranged. The magnetic characteristics of the magnetic cells forming part or all of the minimum unit magnetic recording section arranged in the servo signal storage area constitute the minimum unit magnetic recording section arranged in the data signal storage area. The magnetic characteristic of the magnetic cell is different from that of the magnetic cell.

The first magnetic material cell and the second magnetic material cell are different from each other in, for example, different filled magnetic materials, different cell structures, or different cell volumes. The coercive force of the first magnetic cell is
It is desirable that the coercive force of the second magnetic cell be larger than that of the second magnetic cell. The non-magnetic material is preferably anodized aluminum. Ti, Zr, Hf, Nb, Ta, and M are formed under the recording layer composed of the first and second magnetic cells.
A first layer containing at least one of o, W or Si and a second layer having conductivity may be provided in this order. Since the information can be magnetically written by using the above magnetic recording medium, it can be applied to an information recording device such as a hard disk drive.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) The present invention will be described below with reference to FIG. FIG. 1 shows a schematic sectional view of a magnetic recording medium. Reference numeral 1030 denotes a part of the magnetic recording layer, the first magnetic cell 1031 is used as the data signal area 1035, and the tracking servo signal area 1036 is used.
The second magnetic cell 1034 is used as The first and second magnetic substance cells are isolated from each other by a non-magnetic substance 1037.

The magnetic characteristics of the first magnetic cell and the second magnetic cell are different. The magnetic properties mentioned here are, for example, coercive force, remanent magnetization, magnetic anisotropy, saturation magnetization and the like. The difference in the magnetic characteristics is preferably 10% or more, more preferably 30% or more, further preferably 100% between the first magnetic material cell and the second magnetic material cell.
It is preferable that there is a difference of not less than%. The upper limit of the difference is, for example, 500% or less.

Such a difference in magnetic characteristics can be realized by making the volumes and shapes of the first and second cells different and making the types of magnetic materials arranged in the cells different. Specifically, (i) the structure of the cell itself is different, (ii) the type of magnetic material arranged in the cell is different, (iii) the structure of the cell itself and the magnetic material arranged are also different, etc. Is. The cell structure is a concept including a cell diameter, depth, shape, and volume. When the structures of the first cell and the second cell are the same, the thickness of the recording layer composed of the magnetic cell and the nonmagnetic material can be the same between the two regions.

If the magnetic characteristics are different between the data signal storage area and the tracking servo signal storage area, it is necessary to write the tracking servo signal using the above-mentioned servo writer device after the magnetic recording medium is manufactured. Lost. This point will be described. For example, consider a case where the coercive force of the second cell (tracking servo signal region) is higher than that of the first cell (data signal storage region). Once, a magnetic field is applied to the entire recording layer to magnetize the first and second cells in the first direction. Then the first
If a magnetic field with an intensity that reverses the magnetization of only the cell
The directions of magnetization can be reversed between the first cell and the second cell.

Incidentally, even when a signal is written in the tracking servo signal area, the condition for position control of the servo writer is relaxed. This is because even if the size of the magnetic head is larger than the tracking servo signal area and the magnetic field is applied to the data signal area by the magnetic head when writing the signal, only the second magnetic cell is This is because the directions of the magnetic moments can be aligned.

Further, by separating each magnetic substance cell by a non-magnetic substance, each magnetic substance cell can be magnetically separated and the magnetization transition region can be made clear, so that noise during signal reproduction is reduced. can do.

Although FIG. 1 shows the case where the number of cells in the tracking servo area is two,
This is just an example. For example, the configuration shown in FIG. 2 is also possible. The configuration of the magnetic recording medium according to the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of a structural example of the magnetic recording medium of the present invention. The magnetic recording medium shown in the figure has a data signal storage area formed by arranging a plurality of minimum unit magnetic recording sections,
A magnetic field having a tracking servo signal storage area formed by arranging a plurality of minimum unit magnetic recording sections and constituting a part or all of the minimum unit magnetic recording sections arranged in the tracking servo signal storage area. The body cell is composed of a magnetic cell having a magnetic characteristic different from that of the minimum unit magnetic recording portion arranged in the data signal storage area. The minimum unit magnetic recording portion here is a portion in charge of recording, for example, 1 bit.

In the magnetic recording medium 1030 shown in FIG. 2, an underlayer 1032 is formed on a non-magnetic substrate 1033. The data signal area 1035 corresponds to the first magnetic cell 10
31 includes a tracking servo signal area 10
36 is composed of a combination of the first magnetic substance cell 1031 and the second magnetic substance cell 1034.

All cells are made of non-magnetic material 1037.
The first magnetic substance cell 1031 and the second magnetic substance cell 1034 have different magnetic characteristics from each other. In this way, the magnetic cell 1031,
By separating 1034 by the nonmagnetic material 37, they are magnetically separated from each other, and the magnetization transition region can be made clear. As a result, it is possible to reduce noise during signal reproduction. Further, the base layer 32 is not essential. Of course, the magnetic characteristics of all the magnetic material cells in the tracking servo signal storage area need not be different from the magnetic characteristics of the magnetic material cells in the data signal storage area.

FIG. 3 is a plan view showing a structural example of the magnetic recording medium of the present invention. Each track is composed of a data signal storage area 1035 and a tracking servo signal storage area 1036 in the same manner as a normal magnetic recording medium, and the first magnetic field in the minimum unit magnetic recording unit 1042 forming the data signal storage area 1035. The body cells 1031 are all made of magnetic material having the same magnetic characteristics.

On the other hand, the tracking servo signal storage area 1
A part of the minimum unit magnetic recording unit 104 constituting 036
The second magnetic substance cell 1034 in 5 is made of a magnetic substance material having a magnetic characteristic different from that of the data signal storage area 1035 as shown in FIG.

The tracking servo signal storage area 1
The minimum unit magnetic recording unit 1045 having a magnetic characteristic in 036 different from that of the data signal storage area may be arranged in a staggered pattern across two adjacent recording tracks as shown in FIG. It may be arranged such that the phase is different from that of the signal of the region. How it is arranged depends on the tracking method and is not particularly limited.

Minimum unit magnetic recording unit 1045 or 10
The magnetic cell 1034 or 1031 in 42 may be plural as shown in FIG. 3, or may be one. The shape of the minimum unit magnetic recording portion may be square as shown in FIG. 3, rectangular or circular, and the shape thereof is not particularly limited. In addition, especially in the case of a square or a rectangle, the length of one side is 5 to 200.
About nm is desirable.

Further, although the magnetic substance cells are regularly arranged in this configuration example, they may not be regularly arranged. Further, a part may be regularly arranged.
Tracking servo signal storage area 1036 shown in FIG.
The second magnetic substance cells 1034 in some of the minimum unit magnetic recording units 1045 constituting the
It is preferable to use a material having a higher coercive force than that of the magnetic substance cell 1031 in the minimum unit magnetic recording portion 1042 forming the magnetic field 35.

As a method of changing the coercive force of the magnetic substance cell as described above, there are a method of changing the volume of the magnetic substance cell and a method of changing the magnetic substance material. Further, instead of changing the coercive force, the easy axis of magnetization is changed, and, for example, a perpendicular magnetic recording material is used as the material of the magnetic material cell forming the data signal storage area, and the magnetic material forming the tracking servo signal storage area is used. There is also a method of distinguishing the tracking servo signal and the data signal by using the cell material as the longitudinal magnetic recording material. That is, it is possible to use changes in various magnetic characteristics (coercive force, remanent magnetization, magnetic anisotropy, etc.) of the magnetic cell as a tracking servo signal.

The difference in the magnetic characteristics is preferably 10% or more, more preferably 30% or more, still more preferably 100, between the first magnetic substance cell and the second magnetic substance cell.
It is preferable that there is a difference of not less than%. The upper limit of the difference is, for example, 500% or less.

The magnetic recording medium according to the present invention is shown in FIG.
It is possible that there are a plurality of magnetic material cells that form the minimum unit magnetic recording portion as shown in FIG. 2, and that there is one magnetic material cell that forms the minimum unit magnetic recording portion. Is also possible. When the minimum unit magnetic recording portion is composed of one magnetic substance cell, it becomes a so-called patterned medium.

Further, in the magnetic recording medium of the present invention, the magnetic characteristic of at least a part of the magnetic substance cells forming the minimum unit magnetic recording portion arranged in the tracking servo signal storage area is the data signal storage. It may be different from the magnetic cell arranged in the region. Of course, the magnetic characteristics of all the magnetic cells arranged in the tracking servo signal storage area may be different from those of the magnetic cells arranged in the data signal storage area.

(Difference in Material) The magnetic characteristics can be changed by changing the kind of the magnetic material filled in the cell as described above. By changing the material of the magnetic substance cell in this way, the magnetic characteristics of the tracking servo signal storage area can be changed freely and largely, so that the difference between the reproduction signals of the tracking servo signal storage area and the data signal storage area can be reduced. It is possible to clarify.

Materials for filling the first and second magnetic cells are, for example, Co, CoCr, FePt, Co.
It can be appropriately selected from Pt, Co / Pd (multilayer film of Co and Pd), and CoCr-based alloy.

In particular, Co or CoCr is used as a filling material for the magnetic material cell in the data signal storage area,
FePt, CoPt, Co / Pd are used as the filling material for the magnetic cell in the tracking servo signal storage area.
By using a material selected from (Co and Pd multi-layered film) or a CoCr alloy, the coercive force of the magnetic cell in the tracking servo signal storage region should be higher than that of the magnetic cell in the data signal storage region. Is preferable because it can

(Difference in Volume) Further, the volume of a part or all of the magnetic substance cells forming the minimum unit magnetic recording portion arranged in the tracking servo signal storage area,
The difference in the magnetic characteristics may be realized by making the volume of the magnetic substance cell constituting the minimum unit magnetic recording portion arranged in the data signal storage area different.

Even in such a method, the magnetic characteristic of the minimum unit magnetic recording portion storing the tracking servo signal can be largely changed. For example, when the magnetic cells are formed of the same magnetic material, the coercive force in the direction perpendicular to the substrate can be increased by configuring the magnetic cells so that the aspect ratio of the magnetic cells is increased.

Further, the coercive force of some or all of the magnetic substance cells forming the minimum unit magnetic recording section arranged in the tracking servo signal storage area is the minimum arranged in the data signal storage area. It may be higher than the coercive force of the magnetic cells forming the unit magnetic recording portion.

With such a structure, by changing the intensity of the DC magnetic field, it is possible to form regions having magnetic domains in opposite directions in the tracking servo signal storage region. The shapes of the first and second magnetic substance cells may be columnar shapes, for example.

(Non-magnetic material for separating cells) It is also a preferable mode that the non-magnetic material separating the magnetic material cells is composed of a layer containing anodized aluminum as a main component. By filling the magnetic material in the pores formed by anodizing a layer containing aluminum as a main component (for example, an aluminum film) formed on the underlayer,
It is possible to provide a recording medium in which magnetic cells are separated by a non-magnetic material.

Anodized aluminum oxide (AlO) is used as a non-magnetic material for separating magnetic cells adjacent to each other.
_x ), an oxide containing silicon oxide (SiO _x ) as a main component, titanium oxide (TiO _x ), magnesium oxide (MgO _x ), tantalum oxide (TaO _x ), zinc oxide (ZnO _x ), and the like. Other oxides of AlN or Si
It is also possible to use a nitride such as N _x , an organic material, or a semiconductor material such as Si or Ge.

(Filling Magnetic Material) As the magnetic material in the magnetic substance cell, it is preferable to use a perpendicular magnetic recording material magnetized in the direction perpendicular to the substrate, but an in-plane magnetic recording material magnetized in parallel to the substrate is used. It can also be used.

As the non-magnetic substrate, a normal magnetic disk substrate such as a glass substrate, an Al substrate, a carbon substrate, a resin substrate, a silicon substrate, or a substrate obtained by coating these with NiP can be used.

The distance between the magnetic cells is in the range of several nm to several 100 nm, preferably 6 to 200 nm. In addition, the aspect ratio, which is the ratio of the height to the width of the magnetic substance cell, is preferably about 1 to 20. Furthermore, the cross-sectional shape of the magnetic substance cell viewed from the upper side of the substrate may be circular, elliptical, or rectangular. The cross-sectional area as viewed from the substrate above the magnetic cell, in the range of several to several 10000 nm ^2, preferably 25~10000nm ^2. Further, when the cross-sectional shape of the magnetic substance cell viewed from the upper side of the substrate is circular, the diameter of the magnetic substance cell is in the range of several nm to several hundred nm, preferably 5 nm to 100 nm.

It is desirable that the material forming the magnetic cell has a large saturation magnetization Ms and a large magnetic anisotropy coefficient Ku. Specifically, a hard magnetic material containing Co as a main component is desirable. For example, Co, Cr, Pt, Ta, Nb, Pd,
A Co-based alloy containing any one element of B, Si, Ti, V, Ru, and Rh or two or more elements is preferable.

(Underlayer) In the magnetic recording medium 1030 of the present invention shown in FIG. 2, an underlayer 1032 is provided between the non-magnetic substrate 1033 and the non-magnetic substance 1037. As the material of the underlayer, when the magnetic recording layer is the perpendicular magnetic magnetic material, it is desirable to use the soft magnetic film as the underlayer. A Cr-based or V-based alloy layer may be provided at the interface between the underlayer and the recording layer for the purpose of controlling the crystallinity.
Further, when the non-magnetic material that separates the magnetic cells adjacent to each other is an oxide containing anodized aluminum (AlO _x ) as a main component, a part of the underlayer is made of W, Cu, Ti,
It is desirable to insert a layer containing at least one element selected from Nb, Zn, Ni, Fe, Co and noble metals. However, the underlayer can be omitted.

The layer structure of the perpendicular magnetic recording medium is such that the first layer (eg, Ti, Zr, Hf, Nb,
A layer containing at least one of Ta, Mo, W or Si) and a conductive second layer (eg Cu, a noble metal, an alloy containing Cu, an alloy containing a noble metal, or a layer containing a semiconductor material). It is preferable to adopt a configuration having the layers in order. Here, it is preferable that the first layer has pores connected to the magnetic material cell thereabove, and that portion is also filled with the magnetic material.

Although not shown in the configuration example shown in FIG.
In order to protect the magnetic recording medium by contact with the magnetic head, a protective layer such as amorphous carbon or a lubricant may be provided on the surface of the magnetic recording medium.

FIG. 4 shows an overall plan view of the magnetic recording medium 1030 of the present invention. As shown in FIG. 4, the magnetic recording medium 1030 of the present invention has a data signal storage area 1035 and a tracking servo signal storage area 1036 formed on a substrate at predetermined intervals. Tracking servo signal storage area 1
In 036, magnetic cells having different magnetic characteristics are formed (not shown), and the magnetic head reads the cells to perform tracking. Data signal storage area 103
In 5, the recording / reproducing of the information signal is performed by the magnetic head.

In the tracking servo signal storage area, in addition to the normal tracking servo signal storage area,
It may also include a clock area and an address code area. In the magnetic storage medium of the present invention, the change in the magnetic characteristics of the magnetic cell is used only for recording the tracking servo signal, but the present invention is not limited to this, and it is also used as a read-only magnetic recording pattern (ROM). It goes without saying that you can do it.

(Second Embodiment: Manufacturing Method) Next, a method of manufacturing the magnetic recording medium according to the present invention will be described. An example of the method of manufacturing the magnetic recording medium according to the present invention will be described. Here, in particular, a method of manufacturing a magnetic recording medium using anodized aluminum as a non-magnetic material for separating each magnetic cell will be described. 5 and 6 show the outline of the manufacturing method.

First, as shown in FIG. 5A, a soft magnetic layer as an underlayer 1051 and an electrodeposition underlayer, Cu as an underlayer, etc. are formed on a non-magnetic substrate 1052 made of glass or the like, and are formed thereon. Aluminum or aluminum alloy 1050, which is the source of the non-magnetic material, is formed. It is desirable that the underlying layer 1051 and the aluminum or aluminum alloy 1050 that is the source of the non-magnetic material be formed by a sputtering method or a vapor deposition method.

Next, as shown in FIG. 5B, a stamp having a regularly arranged convex pattern is formed on a hard substrate such as SiC by using electron beam lithography capable of forming a fine pattern in advance.
r) 1053 is pressed onto the aluminum or aluminum alloy surface 1050, and depressions 10 are made on the surface.
54 is formed.

The depression functions as a starting point for forming holes by anodizing treatment. In the region where there is no starting point (flat region), holes are formed at intervals determined by the type and concentration of the electrolytic solution or the anodic oxidation voltage.

Therefore, the convex pattern formed on the stamp 1053 forms cells having different magnetic characteristics from the magnetic cells in the data signal storage area among the magnetic cells in the area for writing the tracking servo signal information. at the place,
No depression is formed (or a depression smaller than the depression of the data signal storage area may be formed). That is, on the surface of the film to be anodized, at least a part of the tracking servo signal region has a recess (second recess) different from the recess (first recess) formed in the data signal storage region.
It is sufficient to provide a dent). The "different depressions" here include depressions having different sizes from the first depressions and depressions having different depression intervals. For example, when the first depression and the second depression have different depths, for example, 1 nm or more and 500 nm or less, preferably 5 nm or less.
It suffices if there is a difference of about 50 nm or more and 50 nm or less. For example,
Even a difference of about 3 nm to 10 nm can be applied if the volume of the magnetic cell can be controlled.

Next, as shown in FIG. 5C, aluminum or aluminum alloy is anodized to form aluminum oxide (anodized alumina) 1 having a plurality of pores formed therein.
Set it to 059.

Here, the anodic oxidation of aluminum will be described. In the anodic oxidation of aluminum or aluminum alloy, the nanohole diameter can be controlled to several nm to several 100 nm, and the interval between the nanoholes can be controlled to a value slightly larger than the nanohole diameter to about 500 nm.
Various acids can be used for the anodization of aluminum or aluminum alloys, but a sulfuric acid solution is used to produce nanoholes with a fine spacing, and a phosphoric acid solution is used to produce nanoholes with a relatively large spacing. An oxalic acid solution is preferable for producing nanoholes having a size of. The diameter of the nanoholes can be enlarged by a method of etching in a solution such as phosphoric acid after anodic oxidation.

In order to form the nanoholes regularly, the method of forming the depression which becomes the starting point of the formation of the nanoholes on the surface of aluminum or aluminum alloy is effective.

In the anodization of aluminum or the like, the places where the depressions are formed are preferentially pores, and the places where the depressions are not formed form pores more slowly than the places where the depressions were formed. Is formed. Therefore, the diameter of the fine pores and the depth of the fine pores are large in the place where the depression is formed, and are small in the place where the depression is not formed. In the above manufacturing method, the anodized sample of FIG.
Anodized aluminum having pores such as C 10
59.

In FIG. 5C, 1055 is a pore (nanohole), and the pore 1055 is larger in diameter and depth than the pore 1155. The method for producing such pores is described in Proceedings No. 48 of the 48th Joint Symposium on Applied Physics in Spring 2001. 3p1332, "Formation of Mosaic Structure in Anodic Oxidized Porous Alumina".

After that, as shown in FIG. 6D, electrodeposition is performed to form hard magnetic particles such as Co. Since the thickness of the anodized aluminum 1059 at the bottom of the pores 1155 where the depressions are not formed in advance is thicker than that of the pores 1055 where the depressions were formed in advance, the voltage at which the magnetic material is electrodeposited is in both pores. Different.

Here, by utilizing the difference, Co, which is a hard magnetic particle, is selectively electrodeposited only on the pores 1055 in which the depressions have been formed at a low electrodeposition potential to form the magnetic substance cell 1056. To do.

Here, as a method of electrodepositing arbitrary pores, a method of forming depressions with a stamp and then performing anodic oxidation has been described, but as disclosed in Japanese Patent Laid-Open No. 2001-9800. A method of electrodepositing arbitrary pores by a method of forming pores having different sizes by using a focused ion beam and anodic oxidation may be used.

Thereafter, the electrodeposition voltage is increased to electrodeposit a magnetic material having a coercive force higher than that of the previously filled magnetic material, so that all the pores are filled with the magnetic material as shown in FIG. 6E. Filled with material, all pores are magnetic cells 105
7, 1058. In this way, the magnetic characteristics of the data signal storage area and the tracking servo signal storage area can be made different by making the materials filled in the cells different.

If it is necessary to further clarify the difference in magnetic characteristics between cells, the following steps may be performed. That is, as shown in FIG. 6F, the filling material is removed to a predetermined depth by polishing or etching. After that, the surface is flattened, and then amorphous carbon is formed as a protective layer on the surface of the medium by a plasma CVD method (not shown).

Further, as shown in FIG. 7A, after applying a strong DC magnetic field to magnetize all the magnetic cells 1058 and 1056 in one direction, as shown in FIG. 7B, a material having a weaker magnetic field and a lower coercive force than that of FIG. 7A. The magnetic recording medium according to the present invention is manufactured by magnetizing only the magnetic cell 1056 in the opposite direction.

In the above manufacturing method, at least a part of the cells (second cell
Of the magnetic substance cell) and the magnetic substance material are different from those of the cell (first magnetic substance cell) in the data signal storage area.

In addition to the above method, the magnetic recording medium according to the present invention has a method in which the pore diameter is made different between the first and second magnetic substance cells, or a metal layer used as an underlayer is used as the first and second metal layers.
It can be realized by a method of making each of them different at the bottom of the magnetic cell.

The pore diameter can be controlled by the arrangement and depth of the pore starting points as described above. Further, after forming the pores of uniform size, only the pores of a predetermined portion may be expanded to control the pore diameter.

In particular, if the metal layers used as the underlayer are made different under the first and second magnetic substance cells, the electrodeposition voltage when the magnetic material is filled in the cells can be changed. Even if the cell sizes are the same, the filling materials can be different.

[0072]

EXAMPLE 1 In this example, the volume of magnetic material cells forming a part of the minimum unit magnetic recording section arranged in the tracking servo signal storage area is arranged in the data signal storage area. The present invention relates to a magnetic recording medium having a volume different from that of a magnetic cell forming a minimum unit magnetic recording unit.

8 and 9 show schematic process diagrams of the manufacturing method of this embodiment. First, a base layer 7012 of Ti having a thickness of 10 nm and Cu having a thickness of 20 nm are formed on a silicon substrate which is a non-magnetic substrate 7011 by a sputter deposition method, and then an Al film 7013 having a thickness of 150 nm is formed by a sputter deposition method. The film was formed to a thickness (FIG. 8A).

Next, the focused ion beam is irradiated onto the aluminum surface at regular intervals to form depressions 7 on the aluminum surface.
014 and 7015 were formed. Here, the ion beam diameter is 30 nm, the ion current is 3 pA, the stay time of the focused ion beam is 10 msec in a part of the data signal storage area and the tracking servo signal storage area, and the focused ion beam is in the remaining tracking servo signal storage area. The staying time was 30 msec (FIG. 8B).

As a result, as shown in FIG. 8B, a large dent 1 was formed on the Al surface of the tracking servo signal storage area where the stay time of the focused ion beam was 30 msec.
5 was formed, and a recess 7014 smaller than that was formed on the Al surface of the data signal storage area and the remaining tracking servo signal storage area. Here, the interval between the depressions 7015 in the data signal storage area is 100 nm, and the minimum unit magnetic recording portion is composed of one magnetic substance cell. The resultant magnetic recording medium has an areal recording density of 6
This corresponds to 5 Gbits / in ² (10 Gbits / cm ² ).

Next, this was treated with an oxalic acid aqueous solution (concentration: 0.
Anodization was performed by applying a voltage of 40 V in 3 mol / l) at 16 ° C. The distance between the alumina nanoholes 7116 and 7016 anodized under these conditions is 100.
nm (FIG. 8C). Next, though not shown in the figure, a phosphoric acid aqueous solution (concentration: 5 wt%) was immersed in the solution at 20 ° C. for 40 minutes to enlarge the pore size. As a result, as shown in FIG. 8C, the nanoholes 7 where the large depressions were formed were formed.
Since the anodic oxidation proceeded preferentially in the volume of 116, the nanohole 701 formed in the place where the small depression was formed
It was larger than the volume of 6.

The average pore diameter of the alumina nanoholes 7116 was about 70 nm. Next, all the anodized alumina nanoholes 7116, 7 prepared in this way
In contrast to 016, Co, which is a ferromagnetic material, was filled in the nanoholes to form a magnetic material cell 7117 having a large magnetic material volume and a magnetic material cell 7017 having a small magnetic material volume (FIG. 9).
D).

For the electrodeposition of Co, an aqueous solution of cobalt (II) sulfate heptahydrate (concentration 0.2 mol / l) and boric acid (concentration 0.3 mol / l) was used at 24 ° C. The electrodeposition is Ag / Ag as a reference electrode in the above solution.
Performed at -5.0V with Cl. Further, this sample was removed by polishing the electrodeposit overflowing on the surface with a 1/4 μm diamond slurry. At this time, the surface r. m. s (root-mean-square) is 1
It was less than or equal to nm.

The magnetic substance cell 71 having a large magnetic substance volume is used.
When the coercive force of No. 17 was measured with a sample vibrating magnetometer, the coercive force in the perpendicular direction to the substrate was 1000 (Oe), and the coercive force in the perpendicular direction of the magnetic body cell 7017 having a small magnetic body volume was 1800 (Oe). Met.

Further, as shown in FIG. 9E, all the magnetic material cells 7117, 7 are added to the magnetic recording medium manufactured as described above.
After magnetizing 017 in a uniform direction, as shown in FIG. 9F, a magnetic field for magnetizing a magnetic cell having a large magnetic volume (a magnetic cell having a small coercive force) 7117 in the opposite direction to the tracking servo signal. Applied to the storage area.

As a result, when the obtained magnetic recording medium was observed with a magnetic force microscope, the magnetic cell 7 having a small pore volume was obtained.
It was confirmed that 017 had a high coercive force and was not inverted. Further, when the magnetization transition region of the magnetization reversal portion in the tracking servo signal storage region was observed by a magnetic force microscope, it was clear as compared with the case where the magnetic cell was not separated by the nonmagnetic material.

Next, when the tracking servo signal was reproduced by using the MR head, the S / N ratio of the reproduced signal was increased by about 15% as compared with the case where the magnetic cell was not separated by the nonmagnetic material.

Further, FIG. 10 shows an arrangement example of the servo patterns in this embodiment. As shown in FIG. 10, immediately after the recording medium is manufactured, the magnetization of part of the magnetic body cells 8026 in the tracking servo signal storage area 8024 is reversed from the magnetization direction of the other magnetic body cells 8027, and The inverted magnetic material cells 8026 are arranged in a zigzag pattern over two adjacent recording tracks.
Note that reference numerals 8023 and 8025 denote data signal storage areas. In this embodiment, the magnetic substance is magnetized in the direction perpendicular to the substrate, but the present invention is not limited to this, and the same effect as when magnetized in the direction parallel to the substrate can be obtained.

Embodiment 2 FIG. 2 is a sectional view of a second embodiment of the magnetic recording medium of the present invention. Similar to the first embodiment, the magnetic recording medium 103 of the present invention.
0 is a non-magnetic substrate 1033 on the silicon substrate, the underlying layer 1032 Ti and Cu, and the non-magnetic material 1037.
Magnetic cell 1 separated by anodized aluminum which is
031 and 1034.

Further, the magnetic cell 1034 and the magnetic cell 1
The volume of the magnetic substance is different from that of 031. Note that 1035 indicates a data signal storage area, 1036 indicates a tracking servo signal storage area, and the magnetic material in the magnetic cell is Co.

FIG. 3 shows a plan view of the magnetic recording medium in this embodiment. In the first embodiment, the minimum unit magnetic recording portion is composed of one magnetic substance cell, but in the present embodiment, four magnetic substance cells 1034 and 1031 (two magnetic substance cells in the track width direction, which are perpendicular to this). 2 magnetic cells in the direction
Minimum unit magnetic recording units 1042 and 1045.

Since the manufacturing method is the same as that of the first embodiment, the description thereof will be omitted. In the magnetic recording medium of this example, the center-to-center distance between adjacent nanoholes was 50 nm and the average hole diameter was 40 nm, and the areal recording density of the resulting magnetic recording medium was 65 Gb.
This corresponds to its / in ² (10 Gbits / cm ² ).

As shown in FIG. 3, each track is composed of a data signal storage area 1035 and a tracking servo signal storage area 1036, as in a normal magnetic recording medium.
The magnetic substance cells 1031 in the minimum unit magnetic recording unit 1042 forming the data signal storage area 1035 are all magnetic substance cells having the same magnetic substance volume.

On the other hand, the tracking servo signal storage area 1
A part of the minimum unit magnetic recording unit 104 constituting 036
The magnetic material cell 1034 in 5 is the data signal storage area 10
The volume of the magnetic material is different from that of the magnetic material cell 1031 in the cell 35. Also here, as in the case of Example 1, the minimum unit magnetic recording portions 1045 constituted by the magnetic substance cells 1034 having different magnetic substance volumes are arranged in a zigzag pattern over two adjacent recording tracks.

Magnetic recording medium 1030 manufactured in this way
Also, the same effect as in Example 1 was obtained. Further, in the present embodiment, the number of magnetic substance cells forming the minimum unit magnetic recording portion is four, but the number is not limited to this.
It may be one or more, preferably two or more.

Embodiment 3 In this embodiment, the material of the magnetic substance cells forming a part of the minimum unit magnetic recording portion arranged in the tracking servo signal storage area is arranged in the data signal storage area. The present invention relates to a magnetic recording medium different from the material of the magnetic cell that constitutes the minimum unit magnetic recording section.

5 and 6 are schematic process diagrams of the manufacturing method of this embodiment. First, an underlying layer 1051 of Ti having a thickness of 10 nm and Cu having a thickness of 20 nm is formed on a silicon substrate which is a non-magnetic substrate 1052 by a sputtering method, and then aluminum 1050 is also formed to a thickness of 150 nm by a sputtering method. Then, a film was formed (FIG. 5A).

Next, by using electron beam lithography, a stamp 1053 having protrusions regularly arrayed only on a part of the data signal storage area and the tracking servo signal storage area is previously formed on the Al surface on the SiC substrate. It was pressed (Fig. 5B). As a result, as shown in FIG. 5B, the recesses 1 at regular intervals are formed only on a part of the Al surface of the data signal storage area and the tracking servo signal storage area.
054 was formed.

Here, the depression 1 in the data signal storage area
The interval of 054 was 100 nm, and the minimum unit magnetic recording portion was composed of one magnetic substance cell. The areal recording density of the resulting magnetic recording medium is 65 Gbits / in ² (10
Gbits / cm ² ). Next, this was placed in an oxalic acid aqueous solution (concentration 0.3 mol / l) at 16 ° C.
A voltage of 40 V was applied to carry out anodization to form anodized alumina nanoholes 1055 and 1155 (FIG. 5).
C).

The interval between the alumina nanoholes anodized under such conditions was 100 nm. Next, it was immersed in a phosphoric acid aqueous solution (concentration: 5 wt%) at 20 ° C. for 30 minutes to expand the pore diameter, and the average pore diameter of the alumina nanoholes 1055 was set to about 80 nm. At this time, the alumina nanoholes (pores) 10 where the depressions were previously formed
In the lower part of 55, since the anodization preferentially proceeded, Cu as the underlayer was exposed and showed good conductivity, but on the other hand, it was formed in the place where the depression was not formed. Further, since the anodized aluminum 1059 remained in the lower part of the alumina nanohole (pore) 1155, the conductivity was low. As a result, by changing the electrodeposition voltage of the magnetic substance filled in each nanohole, it becomes possible to fill each nanohole with a different material.

Next, Co, which is a ferromagnetic material, was filled in a part of the anodized alumina nanohole thus produced. First of all, the nanohole 1055 in the place where the depression was previously formed, that is,
Co was filled in a part of the nanoholes of the data signal storage area and the tracking servo signal storage area to prepare a Co-filled magnetic cell 1056. Here, for the electrodeposition of Co, cobalt (II) sulfate heptahydrate (concentration 0.2 mo
An aqueous solution of 1 / l) and boric acid (concentration 0.3 mol / l) was used at 24 ° C. Electrodeposition was performed at -2.0 V using Ag / AgCl as a reference electrode in the above solution.

Next, CoPt, which has a higher coercive force than Co
The alloy is filled in the alumina nanoholes 1155 formed in the remaining nanoholes where the depressions are not formed,
A CoPt-filled magnetic substance cell 1058 was produced.

Here, for the electrodeposition of CoPt, 6-chloroplatinic acid-6 was added to an aqueous solution of cobalt (II) sulfate heptahydrate (concentration 0.2 mol / l) and boric acid (concentration 0.3 mol / l).
A hydrate (concentration 0.1 mol / l) was added (cobalt sulfate (I
I) 7 hydrate + boric acid): 6 chloroplatinic acid hexahydrate = 1: 1
The mixture obtained in step 2 was used at 24 ° C. The electrodeposition was -5.0 in the above solution using Ag / AgCl as a reference electrode.
I went at V. Further, these samples were polished with 1/4 μm diamond slurry to polish the electrodeposits overflowing on the surface. At this time, Rms on the surface was 1 nm or less.

When the coercive force of the Co-filled magnetic substance cell was measured by a sample vibrating magnetometer, the coercive force was found to be 18
00 (Oe), and the coercive force of the magnetic cell filled with the CoPt alloy was 2500 (Oe).

Next, the magnetic recording medium manufactured in FIGS. 5 and 6 was magnetized by the method shown in FIG. First, after magnetizing all the magnetic cells 1056 and 1058 in a uniform direction, the magnetic cell 105 filled with Co having a small coercive force is used.
A magnetic field for magnetizing 6 in the opposite direction was applied to all regions.

When the resulting magnetic recording medium was observed with a magnetic force microscope, it was confirmed that the magnetization reversal was not performed in the magnetic cell filled with the CoPt alloy having a high coercive force. Further, the magnetization transition in the magnetization reversal region observed by the magnetic force microscope was clear as compared with the case where the magnetic cell was not separated by the nonmagnetic material.

Next, when the tracking servo signal was reproduced by using the MR head, the S / N ratio of the reproduced signal was kept higher than that in the case where the magnetic cell was not separated by the non-magnetic material, and Compared with the method of changing only the depth of the magnetic material cell, that is, the method of changing only the thickness of the magnetic layer, the method of changing the material of the magnetic material is better than the method of changing the S / N of the reproduced signal.
The ratio increased by about 20%.

The arrangement example of the servo patterns in this embodiment is the same as that shown in FIG. As shown in FIG. 10, the magnetization is inverted in a part of the tracking servo signal storage area, and the inverted area is arranged in a zigzag pattern over two adjacent recording tracks. There is.

Embodiment 4 FIG. 11 is a sectional view of a fourth embodiment of the magnetic recording medium of the present invention. In Example 3, the minimum unit magnetic recording portion was composed of one magnetic material cell, but in this embodiment, the minimum unit magnetic recording portion was composed of four magnetic material cells. In FIG. 11, reference numeral 9061 is a data signal recording area, 9060 is a tracking servo signal storage area, 9062 and 9063 are magnetic cells, 9064 is an anodized aluminum which is a non-magnetic material, 9065 is an underlayer of Ti and Cu, and 90.
66 is the silicon of the non-magnetic substrate.

In addition, the magnetic cell 9063 and the magnetic cell 9
062 is different in magnetic material, and here, the magnetic cell 90 is used.
The magnetic material in 62 is a CoPt alloy, and the magnetic substance cell 90
The magnetic material in 63 was Co.

With this structure, the magnetic cell 9
062 and the magnetic cell 9063 have different coercive forces in the direction perpendicular to the substrate. Specifically, when the coercive force of the magnetic body cell 9063 filled with Co was measured by a sample vibrating magnetometer, the coercive force was 1800 (Oe), and the coercive force of the magnetic body cell 62 filled with the CoPt alloy was measured. Magnetic force is 2500 (Oe)
Met.

Since the manufacturing method is almost the same as that of the third embodiment, the description thereof will be omitted. In the magnetic recording medium of this example, the minimum unit magnetic recording portion was composed of four nanoholes with the center distance between adjacent nanoholes being 50 nm. The resultant magnetic recording medium has an areal recording density of 65 Gbits / in ²
This corresponds to (10 Gbits / cm ² ).

The arrangement example of the servo patterns in this embodiment is the same as that shown in FIG. As shown in FIG. 3, immediately after the recording medium is manufactured, the magnetic substance cell 1034 in the minimum unit magnetic recording portion 1045 of the tracking servo signal storage region 1036 is the magnetic substance cell 1031 in the data signal storage region 1035. The minimum unit magnetic recording portions 1045 are magnetized in the opposite direction, and are arranged in a zigzag pattern over two adjacent recording tracks.
The minimum unit magnetic recording unit 1042 in the data signal storage area 1035 is composed of four magnetic cells 1031. Further, here, the magnetization directions of the magnetic cell 1034 and the magnetic cell 1031 are opposite to each other.

The magnetic recording medium manufactured in this manner also had substantially the same effects as in Example 3. Further, in the present embodiment, the number of magnetic substance cells forming the minimum unit magnetic recording portion was set to four, but the number is not limited to this, but one or more, preferably two or more.

[0110]

As described above, according to the present invention, the magnetic recording characteristics of the cells for the data signal storage area and the magnetic characteristics of at least a part of the cells for the tracking servo signal storage area are different from each other. It is possible to provide the medium.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a magnetic recording medium of the present invention.

FIG. 2 is a sectional view showing an example of a magnetic recording medium of the present invention.

FIG. 3 is a diagram showing a part of a configuration example of a magnetic recording medium of the present invention.

FIG. 4 is a plan view showing a part of a configuration example of a magnetic recording medium of the present invention.

FIG. 5 is a cross-sectional process diagram illustrating an example of a method of manufacturing a magnetic recording medium of the present invention.

FIG. 6 is a cross-sectional process diagram illustrating an example of a method of manufacturing a magnetic recording medium of the present invention.

FIG. 7 is a cross-sectional process diagram illustrating an example of a method for manufacturing a magnetic recording medium of the present invention.

FIG. 8 is a sectional process diagram for explaining an example of the method for manufacturing the magnetic recording medium of the present invention.

FIG. 9 is a cross-sectional process diagram illustrating an example of a method of manufacturing a magnetic recording medium of the present invention.

FIG. 10 is a diagram showing a part of a configuration example of a magnetic recording medium of the present invention.

FIG. 11 is a diagram showing a part of a configuration example of a magnetic recording medium of the present invention.

FIG. 12 is a cross-sectional view showing a conventional magnetic recording medium.

[Explanation of symbols]

11 Magnetic Recording Medium 12 Substrate 13 Magnetic Recording Layer 14 Protective Layer 15 Magnetic Layer 17 Recess 1030 Magnetic Recording Medium 1033, 1052, 7011, 8021, 9066
Non-magnetic substrate 1032, 1051, 7012, 9065 Underlayer 1050, 7013 Aluminum (Al) 1054, 7014, 7015 Dimples 1055, 1155, 7016, 7116 Nanoholes (pores) 1031, 1034, 1056, 1057, 1058,
7017, 7117, 8026, 8027, 9062,
9063 magnetic material cell 8022 non-magnetic layer 1037, 9064 non-magnetic material 1042, 1045 minimum unit magnetic recording portion 1053 stamp A, 1035, 8023, 8025, 9061 data signal storage area B, 1036, 8024, 9060 tracking servo signal storage area

Claims (9)

[Claims] 1. A magnetic recording medium comprising a data signal storage area having a first magnetic material cell and a tracking servo signal storage area having a second magnetic material cell,
The first magnetic material cell and the second magnetic material cell are separated by a non-magnetic material, and the first magnetic material cell and the second magnetic material cell have different magnetic characteristics. And a magnetic recording medium. 2. The magnetic recording medium according to claim 1, wherein the first and second magnetic substance cells have a columnar shape. 3. The magnetic recording medium according to claim 1, wherein the first magnetic material cell and the second magnetic material cell have different magnetic materials filled therein. 4. The magnetic recording medium according to claim 1, wherein the first magnetic cell and the second magnetic cell have different cell structures. 5. The magnetic recording medium according to claim 1, wherein the first magnetic cell and the second magnetic cell have different cell volumes. 6. The magnetic recording medium according to claim 1, wherein a coercive force of the first magnetic body cell is larger than a coercive force of the second magnetic body cell. 7. The magnetic recording medium according to claim 1, wherein the tracking servo signal storage area also includes the first magnetic cell. 8. The magnetic recording medium according to claim 1, wherein the non-magnetic material is anodized aluminum. 9. Ti, Zr, Hf, Nb, Ta, under the recording layer composed of the first and second magnetic substance cells,
First containing at least one of Mo, W or Si
2. The magnetic recording medium according to claim 1, wherein said layer and a second layer having conductivity are provided in this order.