KR100225108B1 - Optic-magneto recording medium - Google Patents

Abstract

The present invention relates to a short-wavelength magneto-optical disk, and more particularly, to a magneto-optical recording medium in which a dielectric film, a recording film, an insulating film, and a reflective film are sequentially stacked on a substrate, wherein the recording film is made of NdTbFeCo. And a rare earth-rich type recording layer composed of TbFeCoCr, which shows little decrease in recording / reproducing characteristics and coerciveness even after repeated recording / reproducing cycles, and almost no change in the size of the recording domain.

Description

Short wavelength magneto-optical recording media

1 is a sectional view schematically showing a conventional magneto-optical recording medium.

2 is a sectional view schematically showing a magneto-optical recording medium according to the present invention.

3 is a graph showing a change in recording power for a recording / erase cycle of a magneto-optical recording medium according to the present invention and the prior art.

4 is a graph showing the change of recording / playback characteristics with respect to the recording / erasing cycle of the magneto-optical recording medium according to the present invention and the related art.

5 is a graph showing a change in carrier level for a recording / erasing cycle of a magneto-optical recording medium according to the present invention and the prior art.

* Explanation of symbols for main parts of the drawings

1, 11 substrate 2, 12 dielectric film

3, 13: recording film 4, 14: insulating film

5, 15: reflective film 16: reproduction layer

17: recording layer

The present invention relates to a short-wavelength magneto-optical recording medium, and more particularly, to a magneto-optical recording medium having a structure in which a dielectric film, a recording film, an insulating film, and a reflective film are sequentially stacked on a substrate, wherein the recording film is a recording layer. And a recording layer formed of a rare-earth type (RE-rich type), the recording and reproducing characteristics and the coercivity are hardly reduced even after repeating the recording and reproducing cycle in the short wavelength laser region. The present invention relates to a magneto-optical recording medium having almost no change. Hereinafter, the term magneto-optical recording medium used in the present invention is used interchangeably with the same meaning as the magneto-optical disk.

In general, a recording film of a magneto-optical disk is formed of a thin film in which rare earth elements and transition elements are alloyed, and is a Ferri magnetic material which is a difference between the magnetization values of the sublattices of the rare earth elements and transition elements. The thin film in which the magnetization of the transition element predominates in the recording film is called the transition metal-rich (TM-rich) recording film, and the case in which the magnetization of the rare earth element is superior is called a rare-earth (RE-rich) recording film.

In general, the principle of recording information on a magneto-optical disk uses thermomagnetic characteristics, and the reproduction of information uses magneto-optical characteristics.

The principle of recording information on a magneto-optical disk is to form a vertical magnetization film on a substrate, and to record information by forming a magnetic domain parallel or antiparallel to the vertical direction of the recording film when laser light is irradiated onto the recording film. It is a technique for reproducing and erasing. In other words, when the laser beam integrated on the magneto-optical recording film is irradiated locally, the temperature is raised above the Curie temperature, and the magnetization is lost. It is possible to record information by forming. Also, the reproduction of information uses a Kerr effect, which is that when the incident laser light is reflected on the recording film, the rotation of the polarization plane varies depending on the magnetization state of the recording film. That is, if the polarization plane is rotated + θk when the magnetization is in the upper direction of the recording film, the polarization plane is rotated by -θk when the magnetization is in the downward direction, and the laser beams reflected along the direction of magnetization are 2θk from each other. The polarization plane of is rotated. Reproducing this difference in the photodetector is the principle of reproduction of the magneto-optical disk.

On the other hand, the magneto-optical disk, as shown in FIG. 1, has a dielectric film 2 / recorded on a substrate 1 having an outer diameter of 130 mm (or 90 mm) and grooves formed at intervals of 1.6 mu m. The film 3 / insulation film 4 / reflection film 5 are sequentially stacked by sputtering, and the recording capacity is 10E8 BYTE / cm 2, which is very high.

However, in the conventional magneto-optical disk, the recording film 3 TbFeCo has a large rotation angle when recording and reproducing using the TbFeCo as the recording film 3 and using the laser diode of VKWKD 830 nm (or 780 nm) as the light source. However, when the wavelength is reduced, the rotation angle decreases as the wavelength decreases. When the wavelength is less than 415 nm, which is half the wavelength, the recording and reproduction characteristics are significantly reduced.

Accordingly, an object of the present invention is to provide a magneto-optical disk having excellent recording and recording / reproducing characteristics due to a large rotation angle at a short wavelength as the recording film is formed of a recording layer and a reproduction layer. .

The magneto-optical recording medium of the present invention for achieving the above object is a magneto-optical recording medium in which a dielectric film, a recording film, an insulating film, and a reflective film are sequentially stacked on a substrate, wherein the recording film is a reproduction layer and rare earth composed of NdTbFeCo. -Made of a recording layer composed of a rich type TbFeCoCr.

Hereinafter, the configuration of the present invention will be described in more detail with reference to the accompanying drawings.

Background Art In the magneto-optical disk, high data transfer speeds and high density are the subjects, and researches are actively conducted in the US, Japan, and Europe. In order to achieve high density of magneto-optical disk, short laser wavelength should be used, and it should be excellent in recording and reproducing characteristics because of large rotation angle at short wavelength.

Therefore, the magneto-optical recording medium of the present invention has a dielectric film 12, a reproduction layer 16 and a recording layer 17 on the substrate 11, as shown in FIG. The recording film 13, the insulating film 14, and the reflective film 15 constituted of the above structure are sequentially stacked.

According to the present invention, the substrate 11 may be any substrate that is commonly used in the manufacture of magneto-optical disks. The dielectric film 12 is made of SiN, and its thickness is 500 to 650 Å. The recording layer 17 uses rare earth-rich type TbFeCoCr, whose thickness is preferably 130 to 200 Å. In addition, the insulating film 14 used in the present invention is SiN, 200-400 GPa thick, the reflecting film 15 is AlTi approximately 400-600 GPa, and the reflective film 15 is AlTi, approximately 400-600 GPa. At this time, when the thickness of the reproduction layer 16 and the recording layer 17 is 80 kPa or less, the magneto-optical characteristic deteriorates, and when the thickness of the reproduction layer 16 and the recording layer 17 is 200 kPa or more, the recording sensitivity becomes worse.

In addition, the recording film 13 of the present invention is composed of a recording layer 17 which is responsible for recording and has a high coercivity value, and a two-layer film of a reproduction layer 16 having a high Kerr rotation angle, and the reproduction layer is Nd _X. Tb _y (Fe _100-Z Co _Z ) _100-xy , 20 ≦ _x ≦ 27, 13 ≦ _y ≦ 18, 10 ≦ z ≦ 30, etc., and a rare earth-rich type of Tb _a Cr _b ( Fe _100-C Co _C ) _100-ab , 26 ≦ a ≦ 32, 3 ≦ b ≦ 8, 10 ≦ c ≦ 30, preferably used. At this time, in the reproduction layer Nd _X Tb _y (Fe _100-Z Co _Z ) _100-xy , when its content x is larger than 27, formation of a recording film having a desired vertical magnetization value is not easy, and when z is larger than 30 In this case, the Curie temperature is increased so that high recording power is required for recording information, resulting in poor recording sensitivity. Further, the recording layer _{Tb a Cr b (Fe 100-} C Co C) is large when the recording film coercive force than that of the content of Tb in the _100-ab b 8 is lower than 4koe coercive force is therefore needed as the recording layer perpendicular magnetic anisotropy properties Is reduced.

On the other hand, the short-wavelength magneto-optical disk of the present invention separates the recording film 13 into the recording layer 17 and the reproduction layer 16, and the recording layer 17 is a layer responsible for vertical magnetic anisotropy, and the reproduction layer 16 ) Is a layer responsible for the magneto-optical effect, which is 80 to 130 각각 each, and has a larger rotation angle in a short wavelength laser than a conventional magneto-optical disk. In addition, since the recording layer 17 is manufactured in the rare earth-rich type, the recording and reproducing characteristics and the recording power are hardly reduced even in the reliability test according to the recording / reproducing cycle, and the size of the predetermined magnetic domain is kept constant. .

Hereinafter, the effects of the present invention will be described in more detail with reference to Example 1 and 1, but the scope of the present invention is not limited to the following examples.

Example 1

The dielectric film 12, the regeneration layer 16, the recording layer 17, the insulating film 14 and the reflective film 15 are sequentially formed on the polycarbonate substrate 11 by a DC magnetron method. Magneto-optical disks were prepared.

At this time, the dielectric film 12 is made of 600 ns of SiN and the insulating film 14 is made of SiN, and the 200 ns reflective film 15 is made of Al-Ti with a thickness of 400 ns. In the manufacturing of SiN, a DC reactive magnetron sputtering method using a mixed gas of Ar and N2 was used, and the regeneration layer 16, the recording layer 17, and the reflective film 15 were DC magnetrons using Ar gas. And a thickness of 100 kPa, 150 kPa, and 400 kPa, respectively, and the regeneration layer 16 is 22atm% Nd, 15atm% Tb, 50atm% Fe, and 13atm% Co on the basis of atm%, and the recording layer is rare earth. -Rich type TbFeCoCr was prepared with 28.0atm% Tb, 53.0atm% Co, and 5.5atm% Cr on the basis of atm%. The initial vacuum during the thin film manufacturing was about 3 × 10E-7 mbar, the target size used was 2 inches in diameter, and the thin film was manufactured by rotating the substrate at a speed of 20 rpm to improve the uniformity in forming the thin film. It was.

Comparative Example 1

A thin film was manufactured in the same manner as in Example 1 except that the reproduction layer and the recording layer were formed of TbFeCo of transition metal-rich.

The magnetic properties of the thin films prepared in Example 1 and Comparative Example 1 were measured using a vibrating sample magnetometor (VSM), and FIG. 3 shows the change in recording power with respect to the number of times of repeated recording and reproducing of the disc. FIG. 4 shows the recording / playback characteristics with respect to the number of repetitive reproductions of the disc, and FIG. 5 shows the change of the carrier level with respect to the number of repetitions of the recording / reproduction.

From FIG. 3, the recording power gradually decreases to 3mw until the number of times of recording / erasing of the thin film of the comparative example reaches 10 ⁴ , and the recording power decreases rapidly. In the thin film of the present invention, the recording power is maintained at 4mw or more. the so recorded were the power reduction in the almost open, the fourth from the road, the conventional transition metal-case of TbFeCo of a rich type, repeat number of times in the recording and reproducing characteristics in the following iteration of disk playbacks 10 ² about 44dB of 10 ⁴ In this case, the recording and reproducing characteristics are remarkably reduced by about 37 dB. In the present invention, the recording and reproducing characteristics are maintained at about 45 dB even after 10 ⁴ cycles. In addition, from FIG. 5, it can be seen that as the number of times of recording and reproducing the thin film of the present invention is smaller than the thin film manufactured according to the conventional method, the decrease of the carrier level is smaller, which is superior.

Claims (5)

A magneto-optical recording medium in which a dielectric film, a recording film, an insulating film, and a reflective film are sequentially stacked on a substrate, wherein the recording film is formed of a reproduction layer composed of NdTbFeCo and a recording layer composed of rare earth-rich type TbFeCoCr. Short-wavelength magneto-optical recording media. The short-wavelength magneto-optical recording medium according to claim 1, wherein the reproduction layer has a thickness of 80 to 130 kHz. The short-wavelength magneto-optical recording medium according to claim 1, wherein the recording layer has a thickness of 130 to 200 microseconds. The short wavelength of claim 1, wherein the regeneration layer is composed of Nd _X Tb _y (Fe _100-Z Co _Z ) _100-xy , 20 ≦ _x ≦ 27, 13 ≦ _y ≦ 18, and 10 ≦ z ≦ 30. Magneto-optical recording medium. 2. The short wavelength of claim 1, wherein the recording layer comprises Tb _a Cr _b (Fe _100-C Co _C ) _100-ab , 26 ≦ a ≦ 32, 3 ≦ b ≦ 8, and 10 ≦ c ≦ 30. Magneto-optical recording medium.