KR940001238B1 - Optical recording material - Google Patents
Optical recording material Download PDFInfo
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- KR940001238B1 KR940001238B1 KR1019910016669A KR910016669A KR940001238B1 KR 940001238 B1 KR940001238 B1 KR 940001238B1 KR 1019910016669 A KR1019910016669 A KR 1019910016669A KR 910016669 A KR910016669 A KR 910016669A KR 940001238 B1 KR940001238 B1 KR 940001238B1
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- magneto
- layer
- recording medium
- optical recording
- recording
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
- G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
Abstract
Description
제1도(a) 내지 (c)는 일반적인 광자기 기록매체의 구조도.1 (a) to (c) are structural diagrams of a typical magneto-optical recording medium.
제2도는 본 발명에 따른 기록매체의 파장 의존도.2 is a wavelength dependence of a recording medium according to the present invention.
* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
1 : 제1유전체층 2 : 기록층1: first dielectric layer 2: recording layer
3 : 반사층 4 : 기판3: reflective layer 4: substrate
5 : 제2유전체층5: second dielectric layer
본 발명은 광자기 기록매체에 관한 것으로, 특히 단파장의 광원 이용에 적당하도록 하여 기록 밀도를 높이는데 적당하도록 한 광자기 기록매체에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium, and more particularly to an magneto-optical recording medium adapted to increase the recording density by making it suitable for use of a short wavelength light source.
일반적으로 사용되고 있는 광자기 기록매체는 제1도 (a) 내지 (c)에 도시한 바와같이, 기판(4)위에 제1유전체층(1)을 형성하고, 그 위체 기록층(2)을 적층하며, 상기 기록층(2)의 상면에는 반사층(3) 또는 제2유전체층(5)을 형성하거나, 제2유전체층 (5) 및 반사층(3)을 차례로 적층한 구조로 되어 있다.In general, a magneto-optical recording medium used, as shown in FIGS. 1A to 1C, a first dielectric layer 1 is formed on a substrate 4, and the upper recording layer 2 is laminated. On the upper surface of the recording layer 2, the reflective layer 3 or the second dielectric layer 5 is formed, or the second dielectric layer 5 and the reflective layer 3 are laminated in this order.
한편, 광자기 기록은 수직 이방성을 갖는 자성 박막을 이용하여 기록하며, 집속된 레이저 광의 크기 정도의 비트를 만드는 까닭에 고밀도의 기록이 가능한 장점을 가지며, 정보의 기록방법으로는 기록매체의 박막에 레이저 광을 집속시키면, 국부적으로 온도가 올라가고 매체는 보자력이 감소하게 된다.On the other hand, magneto-optical recording records using a magnetic thin film having vertical anisotropy, and has a merit that high density recording is possible because it makes a bit about the size of the focused laser light, and the information recording method is a thin film of a recording medium. Focusing the laser light locally raises the temperature and the coercive force of the medium decreases.
이때 외부장을 가하면 그 방향으로 자성 모멘트가 배열하는 비트가 형성되어 기록되고, 기록된 정보의 판독은 선형 편광된 빛이 매체에 입사하여 자화와 상호작용에 의해 편광면의 회전이 일어나는데, 이때 회전방향은 자화의 방향에 의존하여 자화의 방향이 반대라면 편광면의 회전방향도 반대가 되며 이를 이용하여 1과 0을 판독한다.At this time, when the external field is applied, bits are formed in which the magnetic moments are arranged in the direction, and the recorded information is read. The linearly polarized light is incident on the medium, and the rotation of the polarization plane occurs by interaction with magnetization. The direction depends on the direction of magnetization, and if the direction of magnetization is reversed, the direction of rotation of the polarization plane is also reversed.
이를 자기 광학적 효과라 하는데 특히 막면에서 반사를 이용할 때는 커(kerr) 효과라 하고 원광면의 회전각을 커 회전각이라고 한다.This is called the magneto-optical effect. Especially, when the reflection is used at the film surface, it is called the Kerr effect and the rotation angle of the raw light surface is called the rotation angle.
이 커 회전각은 C/N비 즉, 캐리어 대 노이즈비와 관계가 있는 중요한 값으로, 이는 다이오드의 쇼트 노이즈(Short Noise)만을 고려할 때 Rθ2K에 비례하며, 여기서 R은 반사도이다.This Kerr rotation angle is an important value related to the C / N ratio, that is, the carrier-to-noise ratio, which is proportional to Rθ 2 K, considering only the short noise of the diode, where R is the reflectivity.
한편, 제1도에 도시한 광자기 기록매체에서 기록층(2)의 매체는 희토류-천이 금속의 합금 박막이 주로 사용되는데 희토류 원소로는 Tb, Gd, Dy, Nd등이 있고, 천이 금속으로는 Fe, Co가 이용된다.On the other hand, in the magneto-optical recording medium shown in FIG. 1, an alloy thin film of rare earth-transition metal is mainly used as a medium of the recording layer 2, and rare earth elements include Tb, Gd, Dy, Nd, and the like. Fe and Co are used.
그중에서 TbFeCo가 가장 성능이 우수한 재료로 이용되며, 기판(4)은 활성이 없고 자성이 없거나 작아서 기록매체의 자성을 잃지 않게 해야하며, 재질은 유리, 폴리 카보나이트, PMMA등을 주로 이용하는데 기록판독시 레이저 광이 기판(4)면에서 입사하기 때문에 투명해야 한다.Among them, TbFeCo is used as the material having the best performance. The substrate 4 is inactive and has no magnetic or small size so as not to lose the magnetism of the recording medium. Since the laser light is incident on the surface of the substrate 4, it must be transparent.
한편, 기록층(2)의 보호와 반사, 간섭등의 광학적인 효과를 이용할 수 있도록 하기 위해 유전체층을 상기 기판(4)과 기록층(2) 사이와, 기록층(2)의 위에 적층하며, 이때 이용되는 제1, 제2유전체층(1,5)의 재료로서 Si3N4, AlN등이 있다.On the other hand, a dielectric layer is laminated between the substrate 4 and the recording layer 2 and on the recording layer 2 in order to use the optical effects such as protection, reflection and interference of the recording layer 2, At this time, Si 3 N 4 , AlN, and the like are used as materials of the first and second dielectric layers 1 and 5.
그리고 상기 기록층(2)과 제1, 제2유전제층(1,5)을 스퍼터링 방법을 이용하여 제조하는데, 기록층(2)을 DC 스퍼터링, 제1, 제2유전체층(1,5)은 DC 리액티브( Reactive) 스퍼터링 또는 RF 리액티브 스퍼터링을 이용한다.The recording layer 2 and the first and second dielectric layers 1 and 5 are manufactured using a sputtering method, and the recording layer 2 is DC sputtered and the first and second dielectric layers 1 and 5 DC reactive sputtering or RF reactive sputtering is used.
그러나 상기와 같은 기존 광자기 기록매체는 희토류-천이 금속합금 재료중에 TbFeCo인데, 희토류가 산소 친화력에 큰 문제가 있어 보호막이 있더라도 완벽한 보호를 하지 못할 뿐만 아니라 시간에 따른 열화가 문제가 된다.However, the conventional magneto-optical recording medium as described above is TbFeCo in rare earth-transition metal alloy materials. Rare earth has a big problem in oxygen affinity, and thus does not completely protect even if there is a protective film.
또한 상기 재료는 장파장 광원에서만 큰 신호를 얻을 수 있기 때문에 단파장 대역(400~600nm)에서는 CNR이 작아서 기록 밀도를 높이는데 한계가 있게 된다.In addition, since the material can obtain a large signal only in a long wavelength light source, the CNR is small in the short wavelength band (400 to 600 nm), which limits the recording density.
이에 따라 본 발명은 단파장 영역에서도 높은 커 회전각이 얻어지도록 하며 기록 밀도를 향상시키게 창안한 것으로, 이를 상세히 설명하면 다음과 같다.Accordingly, the present invention has been devised to achieve high Kerr rotation angle even in the short wavelength region and to improve the recording density, which will be described in detail as follows.
본 발명에서는 단파장용 광자기 기록매체로 HdPdCoFe, NdPtCoFe 또는 NdPdPtCoFe가 사용되는데, 이와 관련하여 레이저 광을 집속시켜 기록하는 광자기 기록방법에는 집속된 레이저 광의 크기가 기록된 비트의 크기와 직결되고, 이는 또한 기록밀도와 직접적인 관련이 있는데 접속된 광의 지름은 빛의 회절을 고려하여 λ/NA에 비례하며, 상기 λ는 광원의 파장이고 NA는 렌즈의 곡률이다. 즉, 기록밀도의 측면에서 보면 파장비의 제곱에 비례하게 되는데. 현재 사용되고 있는 광원은 780~830nm의 파장을 가지고 있으며 파장이 반이 되고(~400nm) 렌즈의 곡률이 0.5에서 0.75가 된다면, 기록 밀도는 약 8배 증가하게 된다.In the present invention, HdPdCoFe, NdPtCoFe or NdPdPtCoFe is used as a short-wavelength magneto-optical recording medium. In this regard, in the magneto-optical recording method for focusing and recording laser light, the size of the focused laser light is directly related to the size of the recorded bit. It is also directly related to the recording density. The diameter of the connected light is proportional to [lambda] / NA in consideration of the diffraction of light, where [lambda] is the wavelength of the light source and NA is the curvature of the lens. That is, in terms of recording density, it is proportional to the square of the wavelength ratio. The light source currently used has a wavelength of 780-830 nm, and the wavelength is halved (~ 400 nm), and if the curvature of the lens is 0.5 to 0.75, the recording density increases by about eight times.
본 발명의 광자기 기록매체를 제조하는 방법은 주로 스퍼터링 방법을 이용하며 기록층(2)이 금속이므로 DC 스퍼터링을 이용하는데, 타겟을 기록층(2)의 조성과 같은 조성으로 하여 제조하거나 각각의 재료를 타겟으로 하여 코스퍼터링(Co-Sputtering)으로 제조하며 합금 타겟을 이용하기도 한다.The method of manufacturing the magneto-optical recording medium of the present invention mainly uses a sputtering method, and since the recording layer 2 is a metal, DC sputtering is used. The target is manufactured by the same composition as that of the recording layer 2, or It is manufactured by co-sputtering using a material as a target, and an alloy target is also used.
한편, 본 발명의 기록층(2)은 재료로서 ND가 포함되어 있는데, 이는 희토류계의 원소로서 산소 친화력이 크기 때문에 보호막이 필요하며,이 보호막은 상기 기록층( 2)을 보호하는 역할뿐만이 아니라 계면에서의 간섭등을 일으키기 때문에 자기 광학적 효과를 크게 하기도 한다.On the other hand, the recording layer 2 of the present invention contains ND as a material, which requires a protective film because of its high oxygen affinity as a rare earth element, and this protective film not only protects the recording layer 2, The magneto-optical effect may be increased because it causes interference at the interface.
이 보호막으로는 제1, 제2유전체층(1,5)을 이용하게 되는데, AlN, Sl3N4의 제1, 제2유전체층(1,5)의 제작 방법은 리액티브 스퍼터링을 이용하며, 스퍼터링층 진공실에 질소를 아르곤과 같이 주입한다.As the passivation layer, first and second dielectric layers 1 and 5 are used. A method of manufacturing the first and second dielectric layers 1 and 5 of AlN and Sl 3 N 4 is made by using reactive sputtering. Nitrogen is injected with argon into the layer vacuum chamber.
따라서 본 발명에 의해 단파장 대역의 레이저 디스크에서 광원의 파장이 만으로 되고(800nm → 400nm), 렌즈의 곡률이 0.5 → 0.75가 되어 기록밀도가 8배로 증가하게 된다. 또한 제2도에 도시한 바와같이 본 발명의 기록매체는 단파장 대역에서 높은 커 회전각을 보이며 이는 단파장 영역에서 큰신호를 낼 수 있음을 의미하고, 높은 기록밀도의 매체로서 적합하게 되고, 또한 Nd는 산소 친화력은 크지만 Pd나 Pt는 화학적으로 극히 안정되어 있고 이들의 대부분이 조성을 차지하기 때문에 화학적으로 안정된 상태로 만들수 있다.Therefore, according to the present invention, the wavelength of the light source is only (800 nm? 400 nm) in the laser disk of the short wavelength band, and the curvature of the lens is 0.5 → 0.75, which increases the recording density by eight times. Also, as shown in FIG. 2, the recording medium of the present invention exhibits a large rotation angle in the short wavelength band, which means that a large signal can be output in the short wavelength region, and is suitable as a medium having a high recording density. Although the oxygen affinity is high, Pd or Pt are chemically extremely stable and most of them take up the composition, which makes them chemically stable.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019910016669A KR940001238B1 (en) | 1991-09-25 | 1991-09-25 | Optical recording material |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019910016669A KR940001238B1 (en) | 1991-09-25 | 1991-09-25 | Optical recording material |
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| Publication Number | Publication Date |
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| KR930006665A KR930006665A (en) | 1993-04-21 |
| KR940001238B1 true KR940001238B1 (en) | 1994-02-18 |
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| KR1019910016669A KR940001238B1 (en) | 1991-09-25 | 1991-09-25 | Optical recording material |
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| US6675383B1 (en) | 1997-01-22 | 2004-01-06 | Nielsen Media Research, Inc. | Source detection apparatus and method for audience measurement |
| CA2658979A1 (en) | 2006-07-12 | 2008-01-17 | Arbitron Inc. | Methods and systems for compliance confirmation and incentives |
| US9124769B2 (en) | 2008-10-31 | 2015-09-01 | The Nielsen Company (Us), Llc | Methods and apparatus to verify presentation of media content |
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