JPH07201089A - Magneto-optical disk and its manufacture - Google Patents

Abstract

PURPOSE: To laminate a reproducing film and recording film consisting of a TbFeCo alloy by utilizing one target and to simplify production stages by laminating the reproducing film and the recording film between the dielectric films on both upper and lower sides, thereby constituting a magneto-optical disk. CONSTITUTION: The reproducing film 13 of the TbFeCo is deposited by evaporation atop the first dielectric film at a vapor deposition rate higher than the vapor deposition rate of the recording film 14 by utilizing the target of, for example, the TbFeCo which is the alloy film of a rare earth-transition metal. In such a case, the TbFeCo reproducing film 13 is deposited by evaporation under the working pressure, with the electric power lower and higher than the electric power at the time of the vapor deposition of the recording film 14 in such a manner that the axis to effect the perpendicular magnetization of the reproducing film 13 of the TbFeCO is maintained within the plane at ordinary temp. The recording film 14 of the TbFeCo is thereafter deposited by evaporation at the vapor deposition rate lower than the vapor deposition rate of the reproducing film 13 atop the reproducing film 13 in such a manner that the recording film has the perpendicular magnetization by a magnetron system by utilizing the target of the TbFeCo.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk and a method of manufacturing the same, and more specifically, to a TbFeCo reproducing film (reading film) between dielectric films stacked on the upper and lower sides.
ut layer) and TbFeCo recording film (rec)
The present invention relates to a super-resolution magneto-optical disk in which a plurality of ordering layers are stacked and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, a recording medium capable of storing a large amount of information has been gradually developed as the information industry has advanced. As a method of storing information, there are a magnetic recording method and an optical recording method. The magnetic recording method includes a horizontal magnetization method. The horizontal magnetization method demagnetizes a magnetic recording medium.
However, there is a problem that it is not possible to store necessary information at a high density because of the drawback of the (netization). In addition, the demagnetization of the horizontal magnetization method (demagneti)
There is a perpendicular magnetization method as a method for solving the problem of zation). The perpendicular magnetization method is often used in the contact relationship between the magnetic head and the magnetic recording medium, the efficiency and resolution of the magnetic head, mass production of the magnetic recording medium, and the like. Since it has problems, it has not been put to practical use.

Further, in the above optical recording method, a laser beam having an excellent focusing power is focused to 1 μm or less and irradiated on a fine area of the magneto-optical recording medium to heat and physicochemical properties of the optical recording medium. Record the desired information by changing it optically,
The information is read optically. Therefore,
The optical recording method exceeds the recording density limit of the magnetic recording method, and has an extremely high recording density of 10 ⁷ to 10 ⁸ bit / cm ² or more. That is, for example, a rare earth-transition metal alloy film is used as the magneto-optical recording medium, has a considerably large coercive force (Hc) at room temperature, and is not saturated magnetized even in a magnetic field of 30 kOe, but the laser beam is rare earth-transition metal. When focused on the spot portion of the alloy-based alloy film, the temperature of the spot portion rises above the temperature of the peripheral portion to reduce the coercive force of the magnetic film in the rare earth-transition metal alloy film, Even in a magnetic field of several hundred Oe, the part is easily saturated and magnetized to record information.

The magneto-optical recording medium used at present is mainly formed in the shape of a disk, and has a magneto-optical disk (Mage).
netic Optical Disk). Then, in order to record information on the magneto-optical disk at high speed and with high density, physical properties of the recording medium are controlled or super resolution (Super) is set.
A study is being made to improve the recording density by utilizing the reproduction method. The super-resolution reproducing method is a method of electrically reducing the effective beam size of the laser beam of the light source and increasing the recording density by 2 to 4 times. Detection method (Front Aperture Detection: FAD) and rear aperture detection method (R
ear Aperture Detection (RAD). In addition, the front aperture detection method and the rear aperture detection method are all methods of performing reading by utilizing the temperature distribution of the magnetic film existing under the spot when the laser beam is applied to the spot of the magneto-optical disk. In the front aperture detection method, the recorded information is read from the high temperature region of the read-out film in the front region of the spot irradiated by the laser beam, and in the rear aperture detection method, the recorded information is recorded by the laser beam. Regeneration film (Rea) in the area behind the irradiation spot
Dot layer) It is designed to be read from a high temperature region. However, such a super-resolution reproducing method has a disadvantage that it requires a separate external magnetic field for optically masking and is complicated.

Recently, Sharp Co., Ltd. of Japan has developed a super-resolution reproducing method which does not require an external magnetic field, and performs in-plane magnetization at room temperature and perpendicular magnetization at high temperature. The membrane is used to form an exchange-coupled double membrane. That is, when irradiated with a laser beam,
A polar rotation (Polar Kerr) phenomenon occurs at the central part of the spot of the reproducing film high temperature area of the magneto-optical disk, and only the information recorded in the central part of the spot is reproduced, and the recorded information in the area other than the central part is recorded. It won't play. The super-resolution reproducing method is a useful method because it utilizes only the temperature distribution of the recording medium and does not require an initialization magnet used in the aperture detection method or a separate reproducing film necessary for reproducing. In addition, the recording medium is composed of a dual magnetic film of a rare earth and a transition metal, and is formed on the film surface from room temperature at which the magnetization direction of the recording film begins to be disturbed in the magnetic moment direction to the Curie temperature at which the relative permeability becomes "1". It appears perpendicularly, and the magnetization direction of the reproducing film appears parallel to the film surface at room temperature and perpendicularly at high temperature. In this case, when the temperature region where the magnetization direction is perpendicular to the surface becomes sufficiently narrow, the mechanism of the super resolution detection method as shown in FIG. 2 is performed. That is, when the laser beam 1 is focused on the spot of the medium by the objective lens and irradiated, the temperature profile 2 of the reproducing film 4 in the area corresponding to the spot is displayed as a Gaussian distribution curve.
The highest temperature is in the central area of the spot. Therefore, in the reproducing film 4 portion corresponding to the central region of the spot, the magnetization direction becomes vertical and a polar rotation phenomenon occurs, and the magnetization of the recording film 3 in the central region of the spot is transmitted to the reproducing film 4 immediately above. On the other hand, the in-plane magnetization is maintained in the reproducing film 4 in the region other than the spot portion, and the polar rotation phenomenon does not occur. Therefore, the information stored in the recording film 3 is shielded by the in-plane magnetization of the reproducing film 4, Only the information in the central area of the spot irradiated with the laser beam can be read.

[0006]

However, in such a conventional magneto-optical disk, since the reproducing film and the recording film of different materials are vapor-deposited by separate targets, respectively, the reproducing film and the recording film cannot be formed. There is a disadvantage that it is difficult to control the intrinsic properties and the manufacturing process is complicated. In addition, reading power (reading
There was a disadvantage that the power was high.

The inventors of the present invention have made extensive studies in order to solve such problems, and as a result, intend to provide the following magneto-optical disk and its manufacturing method. The object of the present invention is to provide dielectric films between upper and lower sides,
It is an object of the present invention to provide a magneto-optical disk having super resolution and a method for manufacturing the same by stacking a reproducing film and a recording film using a target of TbFeCo made of the same material.

[0008]

An object of the present invention is to provide a substrate, a first dielectric film formed on the upper surface of the substrate to prevent deterioration of characteristics of a reproducing film, and formed on the upper surface of the first dielectric film. A reproducing film for reproducing stored information of the recording film, a recording film formed on the upper surface of the reproducing film for recording information, and a second dielectric film formed on the upper surface of the recording film for preventing characteristic deterioration of the recording film, The second
This is achieved by constructing a magneto-optical disk that includes a reflecting film formed on the upper surface of the dielectric film and reflecting a radiated laser beam to the substrate side.

Another object of the present invention is to stack a first dielectric film on the upper surface of a substrate, stack a reproducing film on the upper surface of the first dielectric film, and reproduce the reproducing film on the upper surface of the reproducing film. The steps of laminating a recording film made of the same material as the film, laminating a second dielectric film on the upper surface of the recording film, and laminating a reflective film on the upper surface of the second dielectric film are sequentially performed. This is achieved by providing a method of manufacturing a magneto-optical disk.

[0010]

A reproducing film having a high evaporation rate and a recording film having a low evaporation rate are laminated between the upper and lower dielectric films with the same material such as TbFeCo so that the reproducing film is horizontally magnetized even at room temperature. , Magneto-optical disks will have super resolution.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, in a magneto-optical disk according to the present invention, a substrate 11 and a lower surface of a reproducing film 13 (generally made of a rare earth transition metal-based magnetic film together with a recording film) are formed on the upper surface of the substrate 11. Is formed on the upper surface of the first dielectric film 12 having no reflectivity in order to prevent the deterioration of the magnetic film by maximizing the magneto-optical signal by blocking the invasion of the impurity gas from the A reproducing film 13 for reading the stored information of the recording film 14 by irradiating it with light at a predetermined temperature, and a reproducing film 13 formed on the upper surface of the reproducing film 13 and having the same material as the material of the reproducing film 13, but the magnetic characteristics are the same. Recording film 14 different from
A second dielectric film 15 which is formed on the upper surface of the recording film 14 and prevents and protects the characteristic deterioration of the upper surface of the recording film 14;
And a reflection film 16 formed on the upper surface of the dielectric film 15 for reflecting the irradiated laser beam to the substrate 11 side.

The method of manufacturing the magneto-optical disk having the above-described structure according to the present invention will be described below. First, for example, the first dielectric film 12 that is not reflected is laminated on a polycarbonate substrate. In this case, the second dielectric film 12 is usually made of silicon nitride (SiN
Although x) is used, it is not limited to the silicon nitride, and other substances can be used. The silicon nitride is
The non-reflected form of Si ₃ N ₄ is used to increase the light transmittance, because the standard refractive index of silicon nitride is 2.03 at a wavelength of 6328Å, and its composition ratio depends on the sputtering conditions. Is not formed uniformly. In addition, RF magnetron sputtering is performed, which is a method effective when depositing an insulator. A target of silicon is deposited to deposit SiNx, and argon (Ar) and nitrogen (N) are deposited under a predetermined pressure and power source. ₂ ) The gas is adjusted to a predetermined ratio and vapor-deposited to maintain the refractive index of the insulator at the standard refractive index.

Normally, a rare earth transition metal alloy used as a recording medium for a magneto-optical disk has an axis for perpendicular magnetization formed on a thin film surface of 200 Å or more, so that information can be perpendicularly recorded and reproduced. However, the pressure of the thin film is 20
If it is 0 Å or less, the magnetic anisotropy that tends to maintain the magnetic properties horizontal to the film surface increases, so that there is a drawback that perpendicular magnetization is not performed well. Therefore, in the present invention, a rare earth-transition metal alloy is formed on two magnetic films having different mutual properties, and a domain wall between the magnetic films is formed.
wall) Control film for reducing energy (contr)
ol layer). That is, a reproducing film and a recording film are formed as two magnetic films having different mutual properties, and the reproducing film plays the role of the adjusting film so as not to be exchange-coupled with the recording film, thereby achieving super resolution. It is a thing. Therefore, a target of TbFeCo, which is an alloy film of rare earth-transition metal, is used, and TbFe is deposited at a deposition rate higher than that of the recording film 14 described later.
A reproduction film 13 of Co is deposited on the upper surface of the first dielectric film 12. In this case, in order to maintain the axis of the perpendicular magnetization of the TbFeCo reproducing film 13 at room temperature in the plane, the TbFeCo of TbFeCo is supplied at a power lower and higher than the working pressure and power at the time of vapor deposition of the recording film 14 described later. The reproduction film 13 is deposited.
Moreover, the horizontal magnetization component of the TbFeCo reproducing film 13 is TbF.
It is formed by a mechanism different from the in-plane magnetization that occurs when the thickness of the eCo film becomes thinner than 100 Å.
The characteristics of the reproduction film are controlled by adjusting the sputtering rate of the reproduction film so that the horizontal magnetization is maintained at room temperature even when the reproduction film has a large thickness of 0 Å or more.

Then, a TbFeCo recording film 14 is formed on the upper surface of the reproducing film 13 at a deposition rate lower than that of the reproducing film 13 so that the recording film has a perpendicular magnetization by a magnetron method using a TbFeCo target. Vapor deposition. Then, a second dielectric film 15 of SiNx is vapor-deposited on the upper surface of the recording film 14 to a predetermined thickness, and then a reflective film 16 of aluminum Al or an aluminum alloy is coated on the upper surface of the second dielectric film 15. The magneto-optical disk layering process is completed.

[0015]

As described above, in the magneto-optical disk and the manufacturing method thereof according to the present invention, TbFeCo is used.
Since a magneto-optical disk is constructed by laminating a reproducing film and a recording film of a series alloy between upper and lower dielectric films, the storage information of the recording film has a low read power.
There is an effect that can be reproduced in. Moreover, since the perpendicular magnetic anisotropy energy of the terbium Tb-based alloy is higher than that of the Gd-based alloy at high temperature, the CNR of the read power is increased, and the reproducing film and the recording are performed using one target. By stacking the films, the manufacturing process of the magneto-optical disk can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a magneto-optical disk according to the present invention.

FIG. 2 is an explanatory diagram of a super resolution reading method for a conventional magneto-optical disk.

[Explanation of symbols]

 11 ... Substrate 12 ... First Dielectric Film 13 ... Reproducing Film 14 ... Recording Film 15 ... Second Dielectric Film 16 ... Reflective Film

Claims (6)

[Claims] 1. A magneto-optical disk comprising: a substrate; a first dielectric film formed on the upper surface of the substrate to prevent deterioration of characteristics of a reproducing film; and a storage of a recording film formed on the upper surface of the first dielectric film. A reproducing film for reproducing information, a recording film formed on the upper surface of the reproducing film for recording information, a second dielectric film formed on the upper surface of the recording film for preventing characteristic deterioration of the recording film, and the second dielectric film. A magneto-optical disk comprising: a reflecting film formed on the upper surface of the body film and reflecting the irradiated laser beam toward the substrate. 2. The recording film and the reproducing film are made of TbFeCo.
The magneto-optical disk according to claim 1, which is formed by laminating a series alloy. 3. The reproducing film is such that the axis of perpendicular magnetization of the reproducing film is maintained in-plane at room temperature.
2. A magneto-optical disk as described in 2 above. 4. A method of manufacturing a magneto-optical disk, comprising: laminating a first dielectric film on a substrate upper surface; laminating a reproducing film on the first dielectric film upper surface; and forming a reproducing film on the upper surface of the reproducing film. Stacking recording films of a material similar to that of the reproduction film,
Stacking a second dielectric film on the upper surface of the recording film, and
A method of manufacturing a magneto-optical disk, which comprises sequentially laminating an opposite film on an upper surface of a dielectric film. 5. The method of manufacturing a magneto-optical disk according to claim 4, wherein the recording film and the reproducing film are stacked by sputtering using a TbFeCo target made of the same material. 6. The method of manufacturing a magneto-optical disk according to claim 4, wherein the reproduction film is sputtered at a deposition rate higher than the deposition rate of the recording film.