JP2000348398A - Magneto-optical recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To integrally execute the magnetical parting between tracks and to inexpensively obtain a high-density recording medium by providing a medium surface with projections for parting respective tracks, forming magnetic layers thereon, irradiating the projections with ion beams and etching the front ends, thereby removing the magnetic layers at the front ends of the projections. SOLUTION: The magneto-optical disk 23 is provided with the projections (guard band parts) 25 for parting the respective tacks on the surface of a polycarbonate substrate 24 and is formed with laminated thin films consisting of the first to third magnetic layers. This magneto-optical disk 23 is placed on a substrate holder rotated by a motor in an ion beam sputtering device from which the air is discharged by an exhaust pump. The projections 25 are thereafter irradiated with the ion beams 23 from an ion source 21, by which the parts 26 to be chipped of the laminated thin films at the front ends of the projections 25 are removed. As a result, the problems of the cross write or cross erase between the adjacent tracks are solved. The magneto-optical disk 23 of an ultra-high density magnetic domain transfer type is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-high-density magneto-optical recording medium utilizing the movement of a domain wall during reproduction and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, a magneto-optical disk has been attracting attention as a rewritable high-density recording medium, but there is an increasing demand for a higher-capacity recording medium by further increasing the recording density of the magneto-optical disk. The linear recording density of an optical disk largely depends on the laser wavelength λ of the reproducing optical system and the numerical aperture NA of the objective lens, and the spatial frequency at the time of signal reproduction is at the limit of about NA / λ. Therefore, in order to realize a higher density in a conventional optical disk, it is necessary to shorten the laser wavelength λ of the reproducing optical system and increase the numerical aperture NA of the objective lens. However, there is a limit in improving the laser wavelength and the numerical aperture of the objective lens. For this reason, several techniques have been proposed to improve the recording density by devising the configuration of the recording medium and the reading method.

For example, the present inventors have disclosed in Japanese Patent Laid-Open No. 6-290.
No. 496 proposes a magneto-optical recording medium capable of reproducing a signal having a period equal to or less than the diffraction limit of light at a high speed without lowering the reproduction signal amplitude, a reproducing method therefor, and a reproducing apparatus therefor. That is, when a temperature distribution is formed in the reproducing layer of the magneto-optical recording medium by a heating means such as a light beam, a distribution is generated in the domain wall energy density, so that the domain wall can be instantaneously moved to a lower domain wall energy. As a result, the reproduced signal amplitude is always constant and the maximum amplitude irrespective of the interval between recorded domain walls (that is, the recording mark length). That is, the inevitable decrease in the reproduction output accompanying the improvement in the linear recording density is greatly improved, and the density can be further increased.

[0004]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 6-290.
According to No. 496, the movement of the domain wall is a phenomenon that occurs on the same track (in the track direction), and it is essential that the magnetic layers be separated (that is, magnetically separated) between the tracks. . As a method of creating such an unclosed magnetic domain (divided domain wall), Japanese Patent Laid-Open No.
No. 290496 proposes a method using a rectangular deep groove substrate and a method of annealing and irradiating the groove portion with a laser to magnetically alter the groove portion. However, the rectangular deep groove substrate has a problem in transferability during molding. In addition, when the annealing treatment is performed, the area of the portion where the magnetic properties are deteriorated by the annealing (the portion where the magnetic layer is deteriorated) depends on the temperature distribution of the laser. There is a possibility that the deteriorated portion of the magnetic layer due to the processing has spread to areas other than the desired track. In this case, there is a problem that the area that can be used as an actual information data section is reduced and the track density is reduced. Further, if the annealing process is performed on the entire surface of the disk, it leads to an increase in the cost of the medium, which is a problem when considering the mass productivity of the medium.

[0005] In addition to the problem of the cross-write and cross-erase between adjacent tracks as the track density is improved not only in the domain wall displacement type magneto-optical recording medium but also in the high-density magneto-optical recording medium and the magnetic recording medium. The division between tracks has become an essential technology. However, at present, there is no established inter-track dividing technology in consideration of mass productivity of the medium.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art and to provide an ultra-high density domain wall displacement type magneto-optical recording medium.

[0007]

The magneto-optical recording medium of the present invention has a projection formed on its surface to divide each track. After the magnetic layer is formed, the projection is This is a magneto-optical recording medium in which the magnetic layer is separated by removing the magnetic layer at the tip of the projection using a method of irradiating an ion beam using an ion beam sputtering method and etching the tip of the projection. Here, the protrusion is a continuous convex portion formed between adjacent tracks in the circumferential direction of the disk along the tracks.

Further, the magneto-optical recording medium of the present invention has a film configuration disclosed in Japanese Patent Application Laid-Open No. 6-290496, that is, an optical recording medium in which at least first, second and third magnetic layers are sequentially laminated. A magnetic recording medium, wherein the first magnetic layer comprises:
In the vicinity of the ambient temperature, the magnetic layer is a magnetic layer (moving layer and reproducing layer) having a relatively small domain wall coercive force and a large domain wall mobility as compared with the third magnetic layer, and the second magnetic layer is composed of the first magnetic layer and the second magnetic layer. The third magnetic layer is composed of a magnetic layer (switching layer) having a lower Curie temperature than the third magnetic layer. The third magnetic layer is a normal magnetic recording layer (memory layer) having excellent storage stability of magnetic domains. In this case, the effect of dividing the magnetic layer greatly affects the recording / reproducing characteristics.

[0009]

According to the present invention, magnetic separation of the magnetic layer of the magneto-optical recording medium can be performed at once. here,
The surface shape of the medium for realizing the present invention can be achieved by forming the substrate using a conventional manufacturing method (such as injection molding or a glass 2P method), and etching with an ion beam is a conventional technique. Therefore, no special difficult technology is required to realize the present invention. That is, in manufacturing the target medium, the cost is significantly reduced as compared with the annealing process. Also, compared to the annealing process,
In the method of physically etching the protrusion (removing the upper portion of the protrusion), the area of the portion to be etched can be adjusted to be extremely small, so that the effective track area can be maximized. Is advantageous.

The present invention is not limited to the domain wall displacement reproducing type magneto-optical recording medium, but is applicable to any high-density magnetic recording medium for the purpose of reducing cross write and cross erase.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a magneto-optical recording medium of the present invention. A polycarbonate substrate 11 has a rectangular shape in which the cross section of a land is triangular, and the land is a guard for separating a magnetic layer. The band unit 13 is provided. After the laminated thin film 15 such as a magnetic layer is formed on the polycarbonate substrate 11, as shown in FIG.
5) Only the tip 26 is etched. Although an extremely thin thin film is deposited on the land portion (not shown in FIGS. 1 and 2) as compared with the groove portion (track width 12), the magnetic layer is intermittent by etching with the ion beam 22. Magnetic layer (discontinuous magnetic layer), magnetic separation of the magnetic layer is achieved.

FIGS. 3 and 5 show another embodiment of the present invention. In the embodiment shown in FIGS. 1 and 2, a portion of a substrate to be cut (etched) by an ion beam is formed as a projection. The same effect can be obtained. These methods utilize a phenomenon (so-called deburring) in which, when an ion beam is irradiated from the side surface of a protrusion in an ion beam sputtering apparatus, the tip of the protrusion is concentrated and etched.

FIG. 8 is a schematic diagram of an ion beam sputtering apparatus. The magneto-optical disk 83 is fixed to the substrate holder 84 such that the projection-forming portion is on the upper surface (the substrate holder 84 side is the lower surface). The substrate holder 84 is rotated at a constant speed by a motor 85. For the ion source 81,
The magneto-optical disk 83 is disposed vertically, and the ion beam 82
Is almost parallel to the medium (beam incident angle ± 10 ° or less,
Irradiation is preferably performed at a beam incident angle of 0 °).
The etching conditions vary depending on the type and size of the apparatus. For example, when using a bucket type ion source having a beam diameter of 100 mmφ, the beam voltage is set to 400 eV to 1000 eV.
By adjusting the eV and the beam current in the range of 100 mA to 200 mA, it is possible to etch (cut) from the upper part of the protrusion of the disk to a length of about 20 nm in several seconds.

FIG. 7 is a schematic sectional view showing a film configuration of a domain wall displacement reproducing type magneto-optical recording medium as one of the magneto-optical recording media to which the present invention is applied.

On a transparent substrate 71, a first dielectric layer 72,
The magnetic layer 73 and the second dielectric layer 74 are sequentially laminated.

As the transparent substrate 71, for example, glass,
Polycarbonate, polymethyl methacrylate, thermoplastic norbornene-based resin, and the like can be used.

The magnetic layer 73 may be a single layer or a laminate, and is not particularly limited.
Those having the first, second, and third magnetic layers disclosed in 290496 are suitable. That is, the first magnetic layer 7
Numeral 31 is a magnetic layer (moving layer and reproducing layer) having a smaller domain wall coercive force and a larger domain wall mobility than the third magnetic layer near the ambient temperature, and the second magnetic layer 732 is composed of the first magnetic layer. And a magnetic layer (switching layer) having a lower Curie temperature than the third magnetic layer.
Is a magnetic recording layer (memory layer) with excellent storage stability of magnetic domains
It is.

Each magnetic layer is continuously formed by a physical vapor deposition method such as sputtering or vacuum vapor deposition, and the first, second, and third magnetic layers are exchange-coupled or magnetostatically coupled to each other.

As the magnetic layer 731, for example, GdCo
Materials such as rare earth-iron group amorphous alloys having a relatively small magnetic anisotropy, such as garnet, GdFe-based, GdFeCo-based, and TbCo-based alloys, and garnet are preferable.

The magnetic layer 732 is, for example, a Co-based or Fe-based alloy magnetic layer having a Curie temperature of 73%.
1 and a layer having a saturation magnetization smaller than that of the magnetic layer 733 is preferable. Here, the Curie temperature can be adjusted by the addition amount of Co, Cr, Ti, and the like.

As the magnetic layer 733, for example, TbFe
Rare earths such as Co, DyFeCo, TbDyFeCo
It is preferable to use a material which has a large perpendicular magnetic anisotropy and can stably maintain a magnetized state, such as an iron group amorphous alloy or a platinum group-iron group periodic structure film such as Pt / Co and Pd / Co.

The dielectric layers 72 and 74 are not particularly limited, but are preferably made of SiN, SiO ₂ , ZnS or the like. Further, a protective layer 75 made of an ultraviolet resin or the like may be formed on the dielectric layer 74 as necessary. Note that, from the viewpoint of protecting the medium, the dielectric layer 74 and the protective layer 75 are preferably formed after the protrusions are etched with an ion beam.

Observation of the fact that the projections were shaved by the ion beam was performed using a FE-SEM (Field Emission Scannin).
g Electron Microscope). Acceleration voltage is 10
The KV was observed at a magnification of about 40,000. Further, the final shape of the medium after the projections were cut off by the ion beam was confirmed using AFM (Atomic Force Microscopy).

The recording / reproducing characteristics of the magneto-optical recording medium were measured using a Nakamichi standard evaluation device. Wavelength is 680nm, NA
0.6, minimum recording mark length 0.15μm, linear velocity 1.5m
/ Sec.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Embodiment 1 FIG. 1 is a schematic sectional view of a magneto-optical recording medium of the present invention in a disk radial direction, and FIG. 7 is a schematic sectional view showing a layer structure of a film. In FIG. 1, a polycarbonate substrate 11 has a groove width (track width 12) of 0.9 μm, a land portion 13 serving as a projection and a guard band has a land width 13 of 0.3 μm and a land height 14.
Is a 200 nm land & groove substrate.

On the polycarbonate substrate 11, a laminated thin film 15 was formed in the following order. FIG. 7 shows the laminated thin film 15.
In the following description, a 90-nm thick SiN layer 72 is formed as a first dielectric layer (interference layer) on a polycarbonate substrate 71, and then a GdFeC layer is formed as a first magnetic layer (domain wall moving layer).
The r layer 731 is 30 nm, the TbFeCr layer 732 is 10 nm as a second magnetic layer (switching layer), and the TbFeCoCr layer 733 is 8 as a third magnetic layer (memory layer).
0 nm was sequentially formed by sputtering.

When the cross-sectional shape of the thus obtained magneto-optical recording medium was observed by FE-SEM, as shown in the schematic diagram of FIG. 1, the laminated thin film 15 had a groove surface (denoted as track width 12). Had a semi-cylindrical shape, and an extremely thin film (not shown in FIG. 1, but having a film thickness of about 1/5 of the groove portion) at the land portion (projection portion).

Next, the magneto-optical recording medium 83 was etched using the ion beam sputtering apparatus shown in FIG. The magneto-optical recording medium 83 was arranged such that the ion beam 82 was parallel to the upper surface of the substrate (beam incident angle 0 °) with the projection 25 formed portion as the upper surface. The etching conditions were a beam voltage of 650 eV and a beam current of 100 m.
A, The etching time was 30 seconds.

The cross-sectional shape of the medium after ion beam irradiation is F
Observation with an E-SEM revealed that only the projections (lands) were slightly scraped. This means that, as shown in FIG. 2, only the tip 26 of the projection 25 is
This is the result of shaving. The protrusion height after ion beam etching was measured by AFM and found to be about 150 nm. That is, about 50 nm was etched by the ion beam. Subsequently, a 50 nm-thick SiN layer 74 was formed as a second dielectric layer (protective layer) by sputtering, and a 10 μm ultraviolet curable resin was formed as a protective layer 75.

The magneto-optical disk obtained in this manner is applied to a general-purpose optical disk evaluation apparatus, and the mark length is 0.10 μm (linear velocity 1.5 m / sec) by a normal magnetic field modulation method.
Signal 12 (groove surface)
Recorded. The lands were not annealed.

The magneto-optical disk obtained in this manner is referred to as “a domain wall displacement type expansion reproducing method using a temperature gradient of a magnetic layer” (JP-A-6-2904) which has already been proposed by the inventors.
96)], the wavelength was 680 n
m, NA: 0.6, optical system (relative velocity: 1.5 m / s), C / N: 39.5 dB, jitter: 6.0 ns
c was obtained with good reproducibility. The error rate was at a level with no practical problem.

From the above results, the magnetic layer of the magneto-optical disk can be divided at a time by using the batch etching process of the medium protrusions by the ion beam. Further, the domain wall displacement type magneto-optical recording medium obtained in the present invention was confirmed to have the same recording and reproduction characteristics as the magnetic domain wall displacement type magneto-optical recording medium subjected to the annealing treatment. Thus, a high-density magneto-optical recording medium having mass productivity can be provided.

Comparative Example 1 A magneto-optical recording medium was prepared using the same substrate and process as in Example 1 except that the etching step with the ion beam was not performed. Since the etching by the ion beam is not performed, the land height 14 is 20
It remained at 0 nm.

The magneto-optical disk obtained in this manner was subjected to the same evaluation apparatus as in Example 1, and the mark length was 0.10 μm (linear velocity 1.5 m / sec) by the ordinary magnetic field modulation method.
Signal 12 (groove surface)
Recorded. As in the first embodiment, the land surface is not annealed.

The recording track obtained in this way is
The inventor has already proposed a "domain wall displacement type enlargement reproduction method using a temperature gradient of a magnetic layer (Japanese Patent Laid-Open No. 6-290496).
), The wavelength was 680 nm,
In the optical system of A0.6 (the relative speed was 1.5 m / s), the C / N was 37.5 dB and the jitter was 8.5 nsec. The error rate deteriorated about 50 times or more as compared with the first embodiment, which was a practical problem.

From the above results, the medium of this comparative example is shown in FIG.
As shown in the cross-sectional view of the medium, since the tip of the projection (land) was not etched, the magnetic layer was insufficiently divided, so that the C / N and jitter were reduced. Is presumed to have become difficult to obtain.

Example 2 A substrate having the shape shown in FIG. 3 was prepared. That is, in FIG. 3, the polycarbonate substrate 31 has a land width 38 of 0.7 μm, a groove width 32 of 0.7 μm, a guard band width 33 which is a projection and a guard band portion.
Is a land & groove substrate having a protrusion height of 400 nm and a land height of 150 nm.

Using this substrate, the third
3 and the cross-sectional structure thereof was observed by FE-SEM. As shown in the schematic diagram of FIG. 3, the laminated thin film 35 had a semicylindrical shape on both the land surface 38 and the groove surface 32. In addition, the guard band 33 (projection) had an extremely thin film (not shown in FIG. 3, but the film thickness was about 1/5 of the land or groove).

Next, the projections 37 were etched in the same manner as in Example 1 using the ion beam sputtering apparatus shown in FIG. The etching conditions were the same as in Example 1. The cross-sectional shape of the medium after ion beam irradiation
Observation with -SEM revealed that only the projections (lands) were slightly scraped. This means that, as shown in FIG.
This is the result of shaving. The protrusion height 37 after ion beam etching was measured by AFM and found to be about 350 nm. That is, about 50 nm was etched by the ion beam. Subsequently, a second dielectric layer (protective layer) and a protective layer were formed in the same manner as in Example 1.

The magneto-optical disk obtained in this manner is applied to a general-purpose optical disk evaluation apparatus, and a mark length of 0.10 μm (linear velocity of 1.5 m / sec) is obtained by a normal magnetic field modulation method.
Is recorded on the land portion 38. No signal is recorded in the adjacent groove portion. Further, the annealing treatment of the guard band portion is not performed.

The magneto-optical disk obtained in this manner was used in a method of enlarging / reproducing a domain wall displacement type using a temperature gradient of a magnetic layer (JP-A-6-2904).
96)], the wavelength was 680 n
m, NA: 0.6, optical system (relative speed: 1.5 m / s), C / N: 39.0 dB, jitter: 6.3 ns
c was obtained with good reproducibility. The error rate was at a level with no practical problem. Further, when a recording / reproducing experiment was performed in the groove portion in the same manner as in the land portion, almost the same characteristics as those in the land portion were obtained.

From the above results, the magnetic layer of the magneto-optical disk can be separated at a time by using the batch etching step of the medium projections by the ion beam. Further, the domain wall displacement type magneto-optical recording medium obtained in the present invention was confirmed to have the same recording and reproduction characteristics as the magnetic domain wall displacement type magneto-optical recording medium subjected to the annealing treatment. Thus, a high-density magneto-optical recording medium having mass productivity can be provided.

Comparative Example 2 A magneto-optical recording medium was prepared using the same substrate and process as in Example 2 except that the etching step with the ion beam was not performed. Since the etching by the ion beam is not performed, the projection height 37 is 400
nm.

The magneto-optical disk obtained in this manner was subjected to the same evaluation apparatus as in Example 2, and the mark length was 0.10 μm (linear velocity: 1.5 m / sec) by the ordinary magnetic field modulation method.
Are recorded on the land surface 38. As in the second embodiment, no signal is recorded in the adjacent groove portion.
Further, the annealing treatment of the guard band portion is not performed.

The recording track obtained in this way is
The inventor has already proposed a "domain wall displacement type enlargement reproduction method using a temperature gradient of a magnetic layer (Japanese Patent Laid-Open No. 6-290496).
), The wavelength was 680 nm,
In the optical system of A0.6 (the relative velocity was 1.5 m / s), the C / N was 37.0 dB and the jitter was 9.0 nsec. In addition, the error rate deteriorated about 40 times or more as compared with the first embodiment, which was a practical problem. On the other hand, when a recording / reproducing experiment was performed on the groove surface in the same manner as the land surface, the C / N was 38.5 dB, and the jitter was 7.0 nsec.
Was obtained, and the error rate was at a level having no practical problem.

From the above results, the medium of this comparative example is shown in FIG.
As shown in the cross-sectional view of the medium, since the tip of the protruding portion (guard band portion) was not etched, the separation of the magnetic layer was insufficient, and the C / N and jitter particularly at the land portion were reduced. That is, it is presumed that the domain wall movement phenomenon is hardly obtained.

Example 3 A magneto-optical disk was prepared using a substrate having a cross section as shown in FIG. That is, in FIG. 5, the polycarbonate substrate 51 has a land width 53 of 0.6 μm, a groove width 52 of 0.6 μm, and a taper width 58 of 0.1 μm.
m, a land and groove substrate having a protrusion height 57 of 40 nm and a groove depth of 150 nm.

Using this substrate, the third
When the cross-sectional structure was observed by FE-SEM, the laminated thin film 35 had a semi-cylindrical shape on the groove surface 52 and a land shape 53 on the land surface 53, as shown in the schematic diagram of FIG. It had a semi-cylindrical shape in which the protrusions were formed at both ends of the track. At the taper portion 58, an extremely thin film (not shown in FIG. 5, but having a thickness of about 1/5 of the land or groove portion) was formed.

Next, using the ion beam sputtering apparatus shown in FIG. 8, the projection 57 was etched in the same manner as in the first embodiment. The etching condition is a beam voltage of 6
50 eV, beam current 100 mA, etching time 1
5 seconds.

The cross-sectional shape of the medium after ion beam irradiation is F
Observation with an E-SEM revealed that only the projections (lands) were slightly scraped. This means that, as shown in FIG. 6, only the tip 66 of the projection 65 is
This is the result of shaving. The AFM measured (groove depth 54 + projection height 57 + thickness of the laminated thin film 55) before and after the ion beam etching.
m, about 365 nm after the ion beam. That is, about 25 nm was etched by the ion beam. Subsequently, a second dielectric layer (protective layer) and a protective layer were formed in the same manner as in Example 1.

The magneto-optical disk obtained in this manner is applied to a general-purpose optical disk evaluation apparatus, and the mark length is 0.10 μm (linear velocity 1.5 m / sec) in a normal magnetic field modulation system.
Is recorded on the land portion 38. No signal is recorded in the adjacent groove portion. Further, the annealing treatment of the guard band portion is not performed.

The magneto-optical disk obtained in this manner is referred to as “a domain wall displacement type expansion reproduction method using a temperature gradient of a magnetic layer” (JP-A-6-2904), which has already been proposed by the inventors.
96)], the wavelength was 680 n
m, NA: 0.6, optical system (relative speed: 1.5 m / s), C / N: 38.8 dB, jitter: 6.5 ns
c was obtained with good reproducibility. The error rate was at a level with no practical problem. Further, when a recording / reproducing experiment was performed in the groove portion in the same manner as in the land portion, almost the same characteristics as in the land portion were obtained.

From the above results, the magnetic layer of the magneto-optical disk can be divided at a time by using the batch etching process of the medium protrusions by the ion beam. Further, the domain wall displacement type magneto-optical recording medium obtained in the present invention was confirmed to have the same recording and reproduction characteristics as the magnetic domain wall displacement type magneto-optical recording medium subjected to the annealing treatment. Thus, a high-density magneto-optical recording medium having mass productivity can be provided.

Comparative Example 3 A magneto-optical recording medium was produced using the same substrate and process as in Example 3, except that the etching step with the ion beam was not performed. Since the etching by the ion beam was not performed, (groove depth 54 + projection height 57 + thickness of the laminated thin film 55) was still 390 nm.

The magneto-optical disk obtained in this manner was subjected to the same evaluation apparatus as in Example 3, and a mark length of 0.10 μm (linear velocity of 1.5 m / sec) was obtained by a normal magnetic field modulation method.
Are recorded on the land surface 38. As in the third embodiment, no signal is recorded in the adjacent groove portion.
Further, the annealing process of the tapered portion (guard hand portion) is not performed.

The recording track obtained in this way is
The inventor has already proposed a "domain wall displacement type enlargement reproduction method using a temperature gradient of a magnetic layer (Japanese Patent Laid-Open No. 6-290496).
), The wavelength was 680 nm,
In the optical system of A0.6 (the relative speed was 1.5 m / s), the C / N was 36.5 dB, and the jitter was 9.5 nsec. In addition, the error rate deteriorated about 50 times or more as compared with the third embodiment, which was a practical problem. On the other hand, when a recording / reproducing experiment was performed on the groove surface in the same manner as the land surface, the C / N was 38.0 dB, and the jitter was 7.5 ns.
c was obtained, and the error rate was at a level having no practical problem.

From the above results, the medium of this comparative example is shown in FIG.
As shown in the cross-sectional view of the medium, since the protruding portion tip 66 was not etched, the magnetic layer was insufficiently divided, and the C / N and jitter particularly at the land portion were reduced. It is presumed that it became difficult to obtain the phenomenon of movement.

[0060]

As described above, according to the magneto-optical recording medium and the method of manufacturing the same of the present invention, magnetic separation between tracks can be performed at once, and a high-density recording medium (for example, The domain wall displacement type magneto-optical recording medium disclosed in Japanese Unexamined Patent Publication No. 6-290496) can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a magneto-optical recording medium according to the present invention (Example 1).

FIG. 2 is a schematic view showing a state where the magneto-optical recording medium (Example 1) of the present invention is etched by an ion beam.

FIG. 3 is a schematic cross-sectional view of one example (Example 2) of the magneto-optical recording medium of the present invention.

FIG. 4 is a schematic view showing a state where a magneto-optical recording medium (Example 2) of the present invention is etched by an ion beam.

FIG. 5 is a schematic diagram of a section of a magneto-optical recording medium according to an embodiment (Example 3) of the present invention.

FIG. 6 is a schematic diagram showing a state where a magneto-optical recording medium (Example 3) of the present invention is etched by an ion beam.

FIG. 7 is a cross-sectional configuration diagram of a magneto-optical recording medium according to the present invention.

FIG. 8 is a schematic diagram of an ion beam sputtering apparatus for etching a surface projection of one example (Example 3) of the magneto-optical recording medium of the present invention.

[Explanation of symbols]

11, 24, 31, 44, 51, 64 Polycarbonate substrate 12 Track width 13, 33 Guard band width 14 Land height 15, 35, 55 Laminated thin film 16, 23, 36, 43, 56, 83 Magneto-optical disk 21, 41 , 61, 81 Ion source 22, 42, 62, 82 Ion beam 25, 45, 65 Projection 26, 46, 66 Portion cut by ion beam 32, 52 Groove width 38, 53 Land width 34 Land height 37 Projection height 54 groove depth 57 projection height 58 taper width 71 transparent substrate 73 magnetic layer 731 first magnetic layer (reproducing layer) 732 second magnetic layer (switching layer) 733 third magnetic layer (memory layer) 72, 74 Dielectric layer 75 Protective layer (ultraviolet curing resin) 86 Shutter 84 Substrate holder 85 Motor

Claims (4)

[Claims] 1. A magneto-optical recording medium having projections between tracks on a medium surface, wherein a part of the projections is cut off at one time. 2. The magneto-optical recording medium according to claim 1, wherein said magneto-optical recording medium is a magneto-optical recording medium in which at least first, second, and third magnetic layers are sequentially laminated. The magnetic layer comprises a magnetic layer having a smaller domain wall coercive force and a larger domain wall mobility than the third magnetic layer at a temperature, and the second magnetic layer includes the first magnetic layer and the third magnetic layer. 2. The magneto-optical recording medium according to claim 1, comprising a magnetic layer having a lower Curie temperature, wherein the third magnetic layer is a perpendicular magnetization film. 3. A method of manufacturing a magneto-optical recording medium having projections between tracks on a medium surface, wherein a side of the magneto-optical recording medium is irradiated with an ion beam to form a part of a magnetic layer of the magneto-optical recording medium. A method for manufacturing a magneto-optical recording medium, comprising: 4. The magneto-optical recording medium is a magneto-optical recording medium in which at least a first, a second, and a third magnetic layer are sequentially laminated, wherein the first magnetic layer has a temperature near an ambient temperature. The magnetic layer comprises a magnetic layer having a smaller domain wall coercive force and a larger domain wall mobility than the third magnetic layer at a temperature, and the second magnetic layer includes the first magnetic layer and the third magnetic layer. 4. The method according to claim 3, comprising a magnetic layer having a lower Curie temperature, wherein the third magnetic layer is a perpendicular magnetization film.