JPH09167336A - Magnetic recording medium and manufacturing method therefor, and magnetic recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flatten the surface of a magnetic recording medium by providing a hard magnetic layer comprising a servo pattern of which film thickness varies in the length direction of the track, in a servo signal recording area on a substrate. SOLUTION: The magnetic recording medium 1 has a non-magnetic substrate 2, a magnetic recording layer 3 made of a first hard magnetic material formed on the substrate 2, and a protection layer 4 covering the magnetic recording layer 3. Also, the medium 1 has the shape of a disk with a shaft hole in the center and has a data signal recording area A and a servo signal recording area B. In the area B of the substrate surface 2, multiple recessed parts 2a of a servo pattern are separately formed, and a servo layer 5 made of hard magnetic material is buried in the recessed parts 2. In this case, the surface of the side facing the magnetic head of the magnetic recording layer 3 is flat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, a method of manufacturing the same, and a magnetic recording apparatus, and more particularly, it has a magnetic pattern for writing servo information (track position information) and a magnetic recording layer for writing data. The present invention relates to a magnetic recording medium, a manufacturing method thereof, and a magnetic recording device having the magnetic recording medium.

[0002]

2. Description of the Related Art In a magnetic disk device, a magnetic recording medium (magnetic disk) is used to increase the magnetic recording density.
The track density tends to be high. In order to realize a high track density, it is necessary to improve the tracking accuracy of the magnetic head. As a means for detecting the track position, a servo surface servo system, a sector servo system,
There are various tracking servo methods such as the beaded servo method.

In these systems, a servo signal written on a magnetic disk is read by a magnetic head, and a head actuator is controlled according to the signal to move the magnetic head to a target track position. As a magnetic recording medium having a structure for recording both servo information and data information, as described in, for example, Japanese Patent Laid-Open No. 2-218016, uneven pits having a magnetically readable structure are formed on the surface of the magnetic recording medium. There is a method of controlling the position of the magnetic head on the basis of the magnetic flux generated at the end of the pit as a tracking signal. A structure in which a magnetic recording layer exists and a structure in which no magnetic recording layer exists on the pit have been proposed.

However, the presence of irregularities on the magnetic recording medium
This hinders the lowering of the flying height of the magnetic head from the magnetic disk, which causes a hindrance when attempting to reduce the flying height to achieve a high recording density. Further, if the surface of the magnetic disk has irregularities, dust easily accumulates in the concave portions. In contrast, JP-A-59-72644 and JP-A-4-34
In Japanese Patent No. 718, a magnetic material pattern (hereinafter referred to as a servo pattern) for recording servo information is formed on a substrate, and a servo pattern and a non-magnetic layer are formed on the substrate.
A magnetic recording medium having a structure in which magnetic recording layers are sequentially formed is described.

Further, Japanese Patent Application Laid-Open No. 4-34718 discloses a method of forming a servo pattern by a lift-off method, which improves the flatness of a magnetic recording layer.

[0006]

However, according to the structure of the servo patterns described in those publications, a non-magnetic layer and a magnetic recording layer are provided between the servo pattern and the magnetic head in addition to the gap due to the head flying. Since it exists, the distance between the servo pattern and the magnetic head becomes long. As a result, the signal magnetic field from the servo pattern received by the magnetic head is weakened, and a servo signal reading error is likely to occur.

Further, when the lift-off method is used when forming a servo pattern, burrs are easily generated at the edge of the servo pattern, which causes a head crash in the low flying area. The present invention relates to a magnetic recording medium capable of more reliably reading a servo signal by a magnetic head and further flattening its surface, and a method of manufacturing a magnetic recording medium capable of further improving the flatness of the surface. It is an object of the present invention to provide a magnetic recording device equipped with such a magnetic recording medium.

[0008]

[Means for Solving the Problems]

(Procedure) As described above with reference to FIGS. 1 and 9, the above-mentioned problems are caused by non-magnetic substrates 2 and 22, magnetic recording layers 3 and 23 on the substrates 2 and 22, and on the substrates 2 and 22. A magnetic recording comprising: a hard magnetic layer which is formed continuously with the magnetic recording layers 3 and 23 in a servo signal recording area and which forms servo patterns 5 and 25 whose film thickness changes in the track length direction. Solve by medium.

In this case, the hard magnetic layer is made of the same material as the magnetic recording layers 3 and 23, and the change amount of the film thickness of the hard magnetic layer in the track length direction is determined by the magnetic recording layers 3 and 23. Is 2.5 times or more the film thickness of As illustrated in FIG. 1, the above-mentioned problems are caused by the servo layer 5 made of a hard magnetic material existing in the servo pattern forming portion on the substrate 2 and the servo layer 5 formed in another area of the servo pattern forming portion. A non-magnetic layer 2 surrounding the layer 5,
The magnetic recording medium is characterized by having a magnetic recording layer 3 made of a hard magnetic material formed on the servo layer 5 and the non-magnetic layer 2. In this case, the surface of the magnetic recording layer 5 facing the magnetic head is flat.

The above-mentioned problems are as shown in FIG.
A magnetic recording layer 23 formed on the non-magnetic substrate 22, and
A servo layer 25 made of a hard magnetic material formed on the servo pattern forming portion of the magnetic recording layer 23, and a non-magnetic layer 26 formed on the magnetic recording layer 23 in the other area of the servo pattern forming portion. And a magnetic recording medium characterized by having. In this case, the servo layer 25
And a flat surface is formed by each surface of the non-magnetic layer 26 on the side facing the magnetic head.

In the above magnetic recording medium, the servo patterns 5 and 25 are formed of the same material as the magnetic recording layers 3 and 23, and the thickness of the servo layers 5 and 25 is the magnetic recording layers 3 and 23. Is 2.5 times or more the film thickness of In the above magnetic recording medium,
The servo signal recording area B is arranged in each sector area A.

In the above-mentioned magnetic recording medium, the servo pattern forming sections are arranged in a plurality of rows with different phases in the track length direction for each track and within each track. The above-mentioned problem is, as illustrated in FIG. 2, one of the magnetic recording media 1 described above, and a magnetic head H that detects a magnetic field generated from an end portion of the servo layer 5 of the magnetic recording medium 1 as a tracking signal. And a magnetic recording device characterized by having.

The above-mentioned problems are as shown in FIG.
Forming a recess 2a in the servo pattern forming portion of the non-magnetic layer 2 using a resist mask 11, and the recess 2a
A step of forming a servo layer 5 made of a hard magnetic material inside and on the resist mask 11, and by removing the resist mask 11 and leaving the servo layer 5 in the recess 2a, the servo layer 5 is formed in the recess 2a. A step of forming a servo pattern 5p composed of the servo layer 5, and the servo pattern 5p
And a step of flattening the upper surface by polishing or etching, and a step of forming a magnetic recording layer 3 made of a hard magnetic material on the servo pattern 5p and the non-magnetic layer 2. This is solved by a method of manufacturing a magnetic recording medium.

The above-mentioned problems are as shown in FIG.
Forming a recess 2a in the servo pattern forming portion of the non-magnetic layer 2; forming a servo layer 5 made of a hard magnetic material on the non-magnetic layer 2 and in the recess 2a; A step of applying a flattening film 15 on the servo layer 5; a step of continuously etching back the flattening film 15 and the servo layer 5 to leave the servo layer 5 only in the recess 2a; The servo layer 5 in the recess 2a
And a step of forming a magnetic recording layer 3 made of a hard magnetic material on the non-magnetic layer 2 and the method of manufacturing a magnetic recording medium.

The above-mentioned problems are as shown in FIG.
A step of forming a servo layer 16 made of a hard magnetic material on the non-magnetic layer 2, a step of covering a servo pattern forming portion of the servo layer 16 with a mask 17, and a step of covering the servo pattern 16 with the mask 17 of the servo layer 16. A step of ion-implanting a non-magnetic element into the unexposed region and changing the region into a non-magnetic layer 16c, leaving the hard magnetic layer 16 remaining in the servo pattern forming portion as hard magnetic, and removing the mask 17. And a step of forming a magnetic recording layer 3 made of a hard magnetic material on the non-magnetic layer 2 and the servo layer 5, thereby solving the problem.

The above-mentioned problems are, as shown in FIG. 10, a step of forming a hard magnetic layer 31 on the non-magnetic layer 22, and a step of covering a servo pattern forming portion of the hard magnetic layer 31 with a mask 32. By etching and thinning the hard magnetic layer 31 in a region not covered by the mask 32, the thinned portion becomes the magnetic recording layer 23, and the thick hard magnetic layer under the mask 32 is formed. Magnetic layer 3
1 as a servo pattern 25, and the mask 32
Forming a non-magnetic layer 26 on the top and the magnetic recording layer 23, removing the non-magnetic layer 26 on the mask 32 by removing the mask 32, and polishing the servo pattern 25 Or a step of flattening the upper surface by etching, which is solved by the method for manufacturing a magnetic recording medium.

As shown in FIG. 11, the above-mentioned problems are caused by a step of forming a magnetic recording layer 23 made of a hard magnetic material on the non-magnetic layer 22 and a hard magnetic material made on the magnetic recording layer 23. And forming a servo pattern 33 on the servo pattern 33.
And a step of covering the servo layer 34 in a region not covered with the mask 34 with a nonmagnetic element by ion-implanting the nonmagnetic element into the nonmagnetic layer 33a, and hardening the servo layer 33 in the servo pattern forming portion. A magnetic recording medium manufacturing method, characterized in that it has a step of remaining magnetic.

(Operation) Next, the operation of the present invention will be described. According to the present invention, the film thickness of the hard magnetic layer continuously formed on the magnetic recording layer is changed in the servo signal recording region in the track length direction, and the thick portion is applied as a servo pattern.

As a result, the distance between the servo pattern and the magnetic head becomes extremely short, so that the servo signal magnetic field read by the magnetic head becomes strong and the occurrence of a read error is prevented. As a structure for changing the film thickness of the hard magnetic layer in the servo signal recording area,
In some cases, a servo layer made of a hard magnetic material is formed on the lower surface of a magnetic recording layer made of a hard magnetic material. In this case, since the servo signal is written in the magnetic recording layer together with the servo layer, the strength of the servo signal magnetic field increases. Further, the servo layer is patterned into a plurality of servo patterns, but if a non-magnetic layer is formed under the magnetic recording layer so as to surround the servo pattern and the facing surface of the magnetic head is flattened, the magnetic layer with a low flying height is formed. Head crash is prevented before it happens.

As the second structure, there is a structure in which a servo layer made of a hard magnetic material is formed on the upper surface of a magnetic recording layer made of a hard magnetic material. In this case, since the servo signal is written in the magnetic recording layer together with the servo layer, the strength of the servo signal magnetic field increases. Further, the servo layer is patterned into a plurality of servo patterns. When the non-magnetic layer is formed on the magnetic recording layer so as to surround the servo pattern, the facing surface of the magnetic head becomes flat.

When the servo layer and the magnetic recording layer are made of the same material, a tracking information magnetic field having the same magnitude as the data signal magnetic field can be obtained if the servo layer is 2.5 times or more the film thickness of the magnetic recording layer. It has been confirmed by experiments that this can be done. That is, the amount of change in film thickness in the servo signal recording area may be 2.5 times or more the film thickness of the magnetic recording layer. If a plurality of such servo patterns are arranged in different rows in a track with different phases, and if a plurality of arrays are arranged with different phases for each track, the waveform difference of the tracking information magnetic field in the track length direction caused by the phase difference will occur. The track position information can be detected by detecting.

In the present invention, as a method of forming such a servo pattern, after the servo pattern is formed by lift-off, the surface is flattened by polishing or etching, so that the flatness of the surface of the magnetic recording medium is secured. It is possible to prevent the occurrence of head crash.
As another method of forming a servo pattern, after forming a recess in the nonmagnetic layer in the area where the servo pattern is formed, a servo layer made of a hard magnetic material and a planarizing film are sequentially formed on the nonmagnetic layer, Then, the flattening film and the servo layer are etched back to leave the servo layer only in the recess to form the servo pattern. According to this method, burrs do not occur, and the flatness of the surfaces of the servo pattern and the nonmagnetic layer is not impaired.

As another method of forming a servo pattern, after forming the servo layer, a non-magnetic element is ion-implanted into a region where the servo pattern is not formed to change the servo layer in the region to a non-magnetic layer, and the remaining layer remains. The servo layer is used as a servo pattern. As a result, flatness is not impaired in the servo pattern and its periphery.

When the structure in which the servo pattern is laminated on the magnetic recording layer is adopted, after forming the hard magnetic layer on the substrate, the region of the hard magnetic layer where the servo pattern is not formed is thinned by etching. In addition, the nonmagnetic layer is arranged in the etched portion. As a result, if the hard magnetic layer that remains thick without being etched is used as the servo pattern, a non-magnetic layer of the same thickness will exist around the servo pattern, so that the servo pattern and its surroundings have flatness. To be done. If the data writing area of the hard magnetic layer is thinned and the thinned layer is used as the magnetic recording layer, the servo pattern and the magnetic recording layer need only be formed once, and the number of film formation steps is small. Become.

[0025]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a partial sectional view of a magnetic recording medium according to the first embodiment of the present invention, and FIG. 2 is a plan view thereof.

In FIG. 1, a magnetic recording medium 1 comprises a non-magnetic substrate 2 made of a glass wafer, a silicon wafer or an aluminum wafer covered with NiP, and CoCr, CoCrPt, CoCrTa formed on the substrate 2. It has a magnetic recording layer 3 made of a first hard magnetic material such as CoNiCr, and a protective layer 4 covering the magnetic recording layer 3. The magnetic recording medium 1 has a disk-like shape having a shaft hole 1a in the center, and has a data signal recording area A and a servo signal recording area B as shown in FIG. As shown in FIG. 2, the servo signal area B has an arc shape corresponding to the swing trajectory of the magnetic head H. This is to reduce the difference in yaw angle between the inner circumference and the outer circumference of the magnetic recording medium 1 when the magnetic head H is swung by the rotary actuator 10b.
When the difference in yaw angle increases, the read signal from the magnetic head H fluctuates.

In the servo signal area B on the surface of the substrate 2, a concave portion 2a having a servo pattern shape as shown in FIG.
Are formed so as to be separated from each other.
A servo layer 5 made of a second hard magnetic material such as Cr, CoCrPt, CoCrTa, CoNiCr is embedded. The servo layer 5 in one recess 2a and the magnetic recording layer 3 thereabove form substantially one servo pattern 5p. In the servo signal area B, the servo layer 5 and the magnetic recording layer 3 are in contact with each other, and the servo information written in the servo layer 5 is also written in the magnetic recording layer 3 thereabove. Therefore, no data is recorded on the magnetic recording layer 3 in the servo signal area B.

The second hard magnetic material forming the servo layer 5 may be the same as or different from the first hard magnetic material forming the magnetic recording layer 4. In the servo signal recording area B, a stripe-shaped clock signal pattern 7 is embedded in the surface of the substrate 2 as shown in FIG. 2
There is one clock between two clock signal patterns 7,
A plurality of servo patterns 5p are arranged in a matrix between them.

That is, a plurality of servo patterns 5p are arranged in the circumferential direction of the magnetic recording medium 1, that is, in the track length direction at regular intervals, and are constant in the same track length direction in the radial direction of the magnetic recording medium 1. Plural pieces are arranged in a state of being shifted by the amount α. Here, assuming that the plurality of servo layers 5 arranged in the track length direction are one column pattern, the phase difference α occurs in the waveform of the signal magnetic field emitted from two adjacent column patterns as shown in FIG. 3 (b). Become.

In FIG. 3 (a), the servo pattern 5p
The size of is such that two rows can fit in one track width. By detecting such a phase difference α of the servo pattern 5p with the magnetic head, the relative positional relationship between the track position of the magnetic recording medium 1 and the magnetic head H can be known, so that a read signal from the magnetic head H is obtained. Is input to the control circuit 10a.
The magnetic head H is moved to the target position via b.

Next, a method of writing tracking information to the servo pattern 5p will be described. The tracking information is written by using a magnetic head H as shown in FIG. 4A or a permanent magnet P as shown in FIG. 4B. When writing tracking information with the magnetic head H as shown in FIG. 4A, a DC magnetic field is generated from the magnetic head H while the disk-shaped magnetic recording medium 1 is rotated, and the DC magnetic field is applied. Desired servo layer 5
And the magnetic recording layer 3 around it are magnetized in the same direction in the circumferential direction (track length direction). The recording gap length of the magnetic head H when writing a servo signal is preferably wider than the recording gap length when writing data in the magnetic recording layer 3 because a larger magnetic field can be generated.

On the other hand, as shown in FIG. 4 (b), the permanent magnet P
S poles and N poles are arranged along the circumferential direction, and the magnetic recording medium 1 is rotated in this state to magnetize the desired servo pattern 5p and the magnetic recording layer 3 around it in the same direction. In any of the tracking information writing methods, both the servo pattern 5p and the clock signal pattern 7 are magnetized in the same direction along the track length. Even if the data recording area A is magnetized at the same time when the tracking information is written, the tracking information is erased by writing the data.

The tracking information thus written is read through the magnetic head having the magnetoresistive effect element 8 or the inductive element 9, as shown in FIG. 5 (a). In this case, since the substantial thickness of the servo pattern 5p is the sum of the film thickness of the servo layer 5 and the film thickness of the magnetic recording layer 3, the servo pattern 5p can be compared with the case where the servo layer and the magnetic recording layer are separated. The servo magnetic field Hs leaking from the pattern 5p becomes large.

Moreover, as shown in FIG. 5 (a), since the servo pattern 5p is on the same plane as the magnetic recording layer 3, the distance between the magnetic head H and the servo pattern 5p is substantially equal to that of the magnetic head H and the magnetic pattern. Since the distance is equal to the distance of the recording layer 3, the servo magnetic field input to the magnetic head 5 becomes strong and the reading of tracking information becomes more reliable. Next, an experimental result for examining the relationship between the tracking signal output read by the magnetic head and the film thickness of the servo pattern 5p will be shown.

The tracking information is read out as shown in FIG.
As shown in FIG. 5, the servo pattern 5p on the track was run under the reproducing magnetic head H, and the relationship between the tracking signal output and the thickness of the servo pattern 5p was examined. As shown in FIG. The results were obtained. In FIG. 5 (b), the value obtained by normalizing the data signal output obtained in the magnetic recording layer 3 in the data signal recording area A as "1" is shown on the vertical axis, and the film thickness of the magnetic recording layer 3 is " When the number of stacked servo layers 5 is “1”, the film thickness X of the servo layer 5 is X = Nt (where t is the film thickness of the magnetic recording layer).

In FIG. 5 (b), the tracking signal also increased with an increase in the number of servo layers, and an output of the same magnitude as the data signal output was obtained at about 2.5 times. When a concave pit was provided in the magnetic recording layer 3 without providing the servo layer 5, the tracking signal output from that bit was "0.5". In this way, the servo signal output does not become larger than the data signal output unless the servo layer 5 is 2.5 times or more of the magnetic recording layer 3 because the servo layer 5 forming the servo pattern 5p is adjacent to the servo layer 5 This is because it is separated from the layer 5.

Next, the servo pattern of the magnetic recording medium 1 described above is
A method of forming the turn 5p will be described. First example First, as shown in FIG. 6 (a), a resist 1 is formed on the substrate 2.
Servo signal recording area by applying 1 and exposing and developing it
The window 12 is opened in the B servo pattern forming portion.

After that, as shown in FIG. 6B, the portion of the substrate 2 exposed from the window 12 of the resist 11 is etched to form a concave portion 2a on the upper portion thereof. As the etching method, there are ion milling, sputter etching, chemical etching, and the like. When a physical etching method (PVD method) such as ion milling is used, the recess 2a is used.
It is necessary to secure an appropriate ion irradiation angle because there is a possibility that burrs will occur at the periphery of the.

When a silicon wafer is used as the substrate 2, burrs do not occur because reactive ion etching can be applied. Next, as shown in FIG. 6 (c),
Servo layer 5 made of CoCrPt is sputtered 5
When the resist 11 is formed to a thickness of 250 nm and then the resist 11 is removed with a solvent, the servo layer 5 is formed only in the recess 2a of the substrate 2.
Remains.

Subsequently, mechanical polishing or ion milling,
The substrate 2 and the servo layer 5 are flattened by using sputtering or the like. By this flattening, the recording surface of the magnetic recording medium 1 facing the magnetic head is flattened, so that there is no possibility that the magnetic head flying above the recording surface or sliding on the recording surface is destroyed by the protrusion. After such a flattening step, the magnetic recording layer 3 made of CoCrPt covering the servo layer 5 and the substrate 2 is formed.
Is formed to a thickness of 5 to 100 nm by sputtering, and a protective film 4 is further formed thereon to complete the magnetic recording medium having the structure shown in FIG. 1 (a).

Second Example First, the recess 2a is formed on the substrate 2 as shown in FIG. 7A by the same method as the first example. Next, as shown in FIG. 7 (b), a servo layer 5 made of CoCrPt is formed on the upper surface of the substrate 2 and in the recess 2a by sputtering to a thickness of 5 to 250 nm,
Subsequently, a photoresist 15 is applied on the hard magnetic material 14.

Thereafter, as shown in FIG. 7C, the photoresist 15 and the servo layer 5 are etched by ion milling or sputter etching, and when the surface of the substrate 2 is exposed, the servo layer 5 is removed. Remain only in the recess 2a. In this case, since the upper surface of the servo layer 5 in the recess 2a and the upper surface of the substrate 2 are flat, mechanical polishing or the like is unnecessary.

After this, as shown in FIG. 7D, a magnetic recording layer 3 made of CoCrPt is formed on the servo layer 5 and the substrate 2 by sputtering to a thickness of 5 to 100 nm, and further,
The protective film 4 is formed thereon. A servo pattern 5p is formed by the servo layer 5 remaining in the recess 2a and the magnetic recording layer 3 thereon. Third Example Servo pattern 5a formed by the steps of the first example and the second example described above, and the concave portion 2 formed on the surface of the non-magnetic substrate 2
Although embedded in a, the servo pattern and the nonmagnetic layer may be formed on the substrate 2 by the manufacturing process described below.

First, as shown in FIG. 8A, a hard magnetic layer 16 of CoCrPt is formed on the substrate 2 to a thickness of 5 to 250 nm. Next, as shown in FIG. 8 (b), a resist 17 is applied on the hard magnetic layer 16 and exposed and developed to expose the hard magnetic layer 16 in the area excluding the servo pattern arrangement portion. .

After this, as shown in FIG. 8C, chromium (C) is formed on the hard magnetic layer 16 in the region not covered by the resist 17.
When r) is ion-implanted, the hard magnetic layer 16 in the ion-implanted region becomes Cr-rich and becomes more amorphous, so that it changes to the non-magnetic layer 16a. Then, the hard magnetic layer 16 remaining in the servo pattern arrangement portion under the resist 17 is used as the servo pattern 5p.

Since the hard magnetic layer 16 is not roughened by the ion implantation, the flattening process is unnecessary. Next, as shown in FIG. 8D, after removing the resist 17, the magnetic recording layer 3 made of CoCrPt is formed by sputtering.
The servo pattern 5a and the nonmagnetic layer 16a are formed with a thickness of about 100 nm. Further, when the protective film 4 is formed on the magnetic recording layer 3, the magnetic recording medium is completed.

Also in this structure, the plurality of servo patterns 5p come into contact with the magnetic recording layer 3. In this embodiment, a nonmagnetic layer may be formed on the surface of the substrate, and the nonmagnetic layer may be provided with a recess. (Second Embodiment) In the first embodiment, the magnetic recording layer is formed on the servo layer, but the vertical relationship may be reversed. Therefore, that embodiment will be described below.

FIG. 9 is a partial cross-sectional view of the magnetic recording medium according to the second embodiment of the present invention. The plane is the same as that shown in FIG. In FIG. 9, the magnetic recording medium 21
Is a non-magnetic substrate 22 such as a glass wafer, a silicon wafer, or an aluminum wafer covered with NiP.
And CoCr, CoCrPt, CoCrTa formed on the substrate 22,
A magnetic recording layer 23 made of CoNiCr or the like, a non-magnetic layer 26 made of Cr, Ta, Ti, W, SiO ₂ or the like covering the magnetic recording layer 23, and surrounded by an inside 26 of the non-magnetic layer on the magnetic recording layer 23. CoCr, CoCr
A plurality of servo layers 25 made of Pt, CoCrTa, CoNiCr, etc.,
The protective layer 24 covers the servo layer 25 and the nonmagnetic layer 26. The servo pattern 25p is formed by the servo layer 25 and the magnetic recording layer 23 formed thereon.
Is configured.

The magnetic recording medium 21 has the same annular shape as that of the first embodiment. As in FIG. 2, the clock signal pattern 27 is formed in the servo signal area B, and the servo pattern 25 arranged between the two clock signal patterns 27 has the same arrangement as that of the first embodiment. Even in such a servo pattern 25p, the tracking information writing method is the same as that in the first embodiment. Further, the tracking information written in the servo pattern 25p will be read via the magnetic head.

In this case, the magnetic head reads the magnetic field emitted from the servo pattern 25p as tracking information. Moreover, since the servo layer 25 and the magnetic recording layer 23 form one servo pattern 25p, the tracking signal magnetic field becomes stronger than that of the completely isolated conventional servo pattern. Further, since the non-magnetic layer 26 is embedded around the servo pattern 25, the distance between the servo pattern 25 and the magnetic head is the sum of the flying height of the magnetic head and the film thickness of the protective layer 24. As a result, the servo magnetic field input to the magnetic head becomes large, and the reading of tracking information becomes reliable.

In the magnetic recording medium 21 of this embodiment, if the servo pattern 25p is too thick, the non-magnetic layer 26 around it is also thick, and the distance between the magnetic recording layer 23 and the magnetic head is too large. Therefore, when the servo layer 25 and the magnetic recording layer 23 are formed of the same material, the film thickness of the servo layer 25 is smaller than the film thickness of the magnetic recording layer 23 from the experimental result of FIG. 5B. It is preferable to set it to be about 5 times.

Also in this embodiment, since the nonmagnetic layer 26 is embedded around the servo layer 25, the flatness of the recording surface of the magnetic recording medium 21 is sufficiently ensured. Even in this embodiment, no data is recorded on the magnetic recording layer 23 in the servo signal area B shown in FIG. Next, the method of forming the servo pattern of the magnetic recording medium 21 will be described as an example.

First Example First, as shown in FIG. 10A, CoCrPt was formed on the substrate 22.
The hard magnetic layer 31 of 5 to 250 nm by sputtering
Formed to a thickness of Subsequently, a resist 32 is applied on the hard magnetic layer 31, and the resist 32 is exposed and developed to obtain
The hard magnetic layer 23 in the area excluding the portion where the servo pattern is formed is exposed.

After that, as shown in FIG. 10B, the film thickness of the hard magnetic layer 31 not covered with the resist 32 is 5-10.
A thin layer is formed by etching until it becomes 0 nm. As a result, the film thickness of the hard magnetic layer 31 in the tracking pattern forming portion becomes thicker than other regions. The hard magnetic layer 31 in the thick portion serves as the servo pattern 25, and the thin portion serves as the magnetic recording layer 23.

As the etching method, there are ion milling, sputter etching, chemical etching and the like, but a physical etching method (P
VD method) is used. Next, as shown in FIG. 10 (c), a non-magnetic layer 26 made of Cr is entirely sputtered for 5 to 1 by sputtering.
When the resist 32 is formed to a thickness of 00 nm and then the resist 32 is peeled off with a solvent, the nonmagnetic layer 26 remains only in a region not covered with the resist 32. Then, the periphery of the servo layer 25 patterned by the nonmagnetic layer is embedded.

When the burr of the non-magnetic layer 26 remains around the servo layer 25 after the resist 32 is peeled off, the burr is removed by mechanical polishing, ion milling, sputtering or the like and the servo layer is removed. 25 and the non-magnetic layer 2
It is necessary to make each surface of No. 6 flat. After the flattening step, the protective film 24 is formed on the non-magnetic layer 26 and the servo layer 25 to complete the magnetic recording medium having the structure shown in FIG.

Second Example First, as shown in FIG. 11A, a magnetic recording layer 23 made of CrCoPt and a hard magnetic layer 33 made of CrCoPt were formed on a substrate by sputtering to a thickness of 5 to 100 nm and a thickness of 5 to 250 nm, respectively. To form. Next, as shown in FIG. 11 (b), by applying a resist 34 and exposing and developing it,
The magnetic recording layer 23 in the area excluding the tracking pattern forming portion is exposed.

Thereafter, as shown in FIG. 11C, chromium (Cr) is ion-implanted into the hard magnetic layer 33 layer in the region not covered with the resist 34, and the ion-implanted region is changed to the nonmagnetic layer 33a. . The depth of ion implantation in this case is controlled by adjusting the ion acceleration energy. As a result, the hard magnetic layer 33 and the magnetic recording layer 23 existing below the resist 34 form a servo pattern 25p.

Since the hard magnetic layer 34 is not roughened by the ion implantation, the flattening process is unnecessary. Next, after removing the resist 34 with a solvent, as shown in FIG.
As shown in (d), the servo pattern 25p and the non-magnetic layer 3
The magnetic recording medium is completed by forming the protective film 24 that covers 3a.

In this embodiment, a nonmagnetic layer may be formed on the surface of the substrate.

[0061]

As described above, according to the present invention, the film thickness of the hard magnetic layer continuously formed on the magnetic recording layer is changed in the track length direction in the servo signal recording region to increase the film thickness. Since the part is applied as a servo pattern, the distance between the servo pattern and the magnetic head becomes extremely short,
The magnetic field of the servo signal read by the magnetic head becomes strong, and the occurrence of read errors can be prevented.

As a structure for changing the film thickness of the hard magnetic layer in such a servo signal recording area, firstly, a structure in which a servo layer made of a hard magnetic material is superposed on the lower surface of a magnetic recording layer made of a hard magnetic material. Since, since the servo signal is written in the magnetic recording layer together with the servo layer, the strength of the servo signal magnetic field can be increased. Further, the servo layer is patterned into a plurality of servo patterns, and a nonmagnetic layer is formed under the magnetic recording layer so as to surround the servo pattern to flatten the facing surface of the magnetic head. Therefore, it is possible to prevent a magnetic head crash from a low flying height.

Further, as the second structure, since the structure in which the servo layer made of the hard magnetic material is superposed on the upper surface of the magnetic recording layer made of the hard magnetic material is adopted, the servo signal is written in the magnetic recording layer together with the servo layer. Therefore, the strength of the servo signal magnetic field can be increased. The servo layer is patterned into a plurality of servo patterns. Since the nonmagnetic layer is formed on the magnetic recording layer so as to surround the servo pattern, the facing surface of the magnetic head can be flattened.

When the servo layer and the magnetic recording layer are made of the same material, the tracking information magnetic field having the same magnitude as the data signal magnetic field can be obtained if the servo layer is 2.5 times or more the film thickness of the magnetic recording layer. It has been confirmed by experiments that this can be done. That is, the amount of change in film thickness in the servo signal recording area may be 2.5 times or more the film thickness of the magnetic recording layer. If a plurality of such servo patterns are arranged in different rows in a track with different phases, and if a plurality of arrays are arranged with different phases for each track, the waveform difference of the tracking information magnetic field in the track length direction caused by the phase difference will occur. The track position information can be detected by detecting.

In the present invention, as a method for forming such a servo pattern, after the servo pattern is formed by lift-off, the surface is flattened by polishing or etching, so that the flatness of the surface of the magnetic recording medium is secured. it can. As another method of forming a servo pattern, after forming a recess in the nonmagnetic layer in the area where the servo pattern is formed, a hard magnetic layer and a planarization film are sequentially formed on the nonmagnetic layer, and then the planarization is performed. By etching back the film and the hard magnetic layer, the hard magnetic layer is left only in the recess to form the servo pattern. According to this method, burrs do not occur, and the flatness of the surfaces of the servo pattern and the nonmagnetic layer is not impaired.

As another method for forming a servo pattern, after forming a hard magnetic layer, a nonmagnetic element is ion-implanted into a region where the servo pattern is not formed to change the hard magnetic layer in that region to a nonmagnetic layer. The remaining hard magnetic layer is used as a servo pattern. As a result, flatness is not impaired in the servo pattern and its periphery.

In the case of adopting the structure in which the servo pattern is superposed on the upper surface of the magnetic recording layer, an area of the thick hard magnetic layer in which the servo pattern is not formed is thinned by etching, and the hard magnetic layer is formed in the etched area. The nonmagnetic layers are stacked. This ensures the flatness of the servo pattern and its surroundings, and
The servo pattern and the magnetic recording layer can be formed at once, and the number of film forming steps can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic recording medium according to a first embodiment of the present invention.

FIG. 2 is a plan view of a magnetic recording medium according to an embodiment of the present invention.

FIG. 3 (a) is a plan view showing the arrangement of servo patterns in the magnetic recording medium according to the embodiment of the present invention, and FIG. 3 (b).
FIG. 6 is a waveform diagram showing an example of a tracking signal obtained by reading the servo pattern with a magnetic head.

FIGS. 4A and 4B are perspective views showing a method of writing a tracking signal on a magnetic recording medium according to an embodiment of the present invention.

FIG. 5A is a sectional view showing a method of reading a tracking signal from a magnetic recording medium according to an embodiment of the present invention,
FIG. 5B is a characteristic diagram showing the relationship between the tracking signal and the curtain thickness of the servo pattern.

FIG. 6 is a cross-sectional view showing the first manufacturing method of the magnetic recording medium of the first embodiment of the present invention.

FIG. 7 is a sectional view showing a second manufacturing method of the magnetic recording medium according to the first embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a third manufacturing method of the magnetic recording medium of the first embodiment of the present invention.

FIG. 9 is a sectional view of a magnetic recording medium according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view showing the first manufacturing method of the magnetic recording medium of the second embodiment of the present invention.

FIG. 11 is a sectional view showing a second manufacturing method of the magnetic recording medium according to the second embodiment of the present invention.

[Explanation of symbols]

 1, 21 Magnetic recording medium 2, 22 Substrate 3, 23 Magnetic recording layer 4, 24 Protective layer 5, 25 Servo layer 5p, 25p Servo pattern 26 Non-magnetic layer A Data signal recording area B Servo signal recording area

(72) Inventor Yoshio Koshikawa 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Hiroshi Maeda 1015, Kamedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (15)

[Claims] 1. A non-magnetic substrate, a magnetic recording layer on the substrate, a servo signal recording region on the substrate, which is formed continuously with the magnetic recording layer, and the thickness of which changes in the track length direction. A magnetic recording medium having a hard magnetic layer forming a servo pattern. 2. The hard magnetic layer is made of the same material as the magnetic recording layer, and the amount of change in the film thickness of the hard magnetic layer in the track length direction is 2.
The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a ratio of 5 times or more. 3. A servo layer made of a hard magnetic material existing in a servo pattern forming part on a substrate, a non-magnetic layer formed in another region of the servo pattern forming part and surrounding the servo layer, and the servo. And a magnetic recording layer made of a hard magnetic material formed on the non-magnetic layer. 4. The magnetic recording medium according to claim 3, wherein the surface of the magnetic recording layer facing the magnetic head is flat. 5. A magnetic recording layer formed on a non-magnetic substrate, a servo layer made of a hard magnetic material formed in a servo pattern forming portion on the magnetic recording layer, and on the magnetic recording layer. A magnetic recording medium having a non-magnetic layer formed in another region of the servo pattern forming portion. 6. The magnetic recording medium according to claim 5, wherein a flat surface is formed by the surfaces of the servo layer and the non-magnetic layer on the side facing the magnetic head. 7. The servo layer is formed of the same material as the magnetic recording layer, and the thickness of the servo layer is 2.5 times or more the thickness of the magnetic recording layer. Item 3. The magnetic recording medium according to Item 3 or 5. 8. The magnetic recording medium according to claim 3, wherein the servo signal recording area is arranged for each sector area. 9. The magnetic recording medium according to claim 3, wherein the servo pattern forming portions are arranged in a plurality of columns with different phases in the track length direction for each track and within each track. . 10. A magnetic recording medium according to claim 1, and a magnetic head for detecting a magnetic field generated from an end of the servo layer of the magnetic recording medium as a tracking signal. Characteristic magnetic recording device. 11. A step of forming a concave portion in a servo pattern forming portion of a non-magnetic layer using a resist mask, a step of forming a servo layer made of a hard magnetic material in the concave portion and on the resist mask, and the resist. Peeling the mask to leave the servo layer in the recess to form a servo pattern of the servo layer in the recess; flattening the upper surface of the servo pattern; And a step of forming a magnetic recording layer made of a hard magnetic material on the non-magnetic layer. 12. A step of forming a concave portion in a servo pattern forming portion of a non-magnetic layer; a step of forming a servo layer made of a hard magnetic material on the non-magnetic layer and in the concave portion; A step of applying a planarizing film on the layer, a step of continuously etching back the planarizing film and the servo layer to leave the servo layer only in the recess, and a step of forming the servo layer in the recess. And a step of forming a magnetic recording layer made of a hard magnetic material on the non-magnetic layer. 13. A step of forming a servo layer made of a hard magnetic material on a non-magnetic layer, a step of covering a portion of the servo layer where a servo pattern is formed with a mask, and a portion of the servo layer not covered by the mask. A step of ion-implanting a non-magnetic element into the area to change the area into a non-magnetic layer; a step of removing the mask; and a magnetic recording layer made of a hard magnetic material on the non-magnetic layer and the servo layer. A method of manufacturing a magnetic recording medium, comprising: 14. A step of forming a hard magnetic layer on a non-magnetic layer, a step of covering a servo pattern forming portion of the hard magnetic layer with a mask, and a step of covering the hard magnetic layer in an area not covered by the mask. A step of forming a thin magnetic layer by etching to form a magnetic recording layer, and forming a thick hard magnetic layer below the mask into a servo pattern; and A step of forming a non-magnetic layer thereon, a step of removing the non-magnetic layer on the mask by removing the mask, and a step of flattening the upper surface by polishing or etching the servo pattern. A method of manufacturing a magnetic recording medium, comprising: 15. A step of forming a magnetic recording layer made of a hard magnetic material on a non-magnetic layer; a step of forming a servo layer made of a hard magnetic material on the magnetic recording layer; Magnetic recording comprising: a step of covering a servo pattern forming portion with a mask; and a step of ion-implanting a nonmagnetic element into the servo layer in a region not covered by the mask to change the region into a nonmagnetic layer. Medium manufacturing method.