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WO2000038184A1 - Optical recording medium and method for making same - Google Patents

Optical recording medium and method for making same Download PDF

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Publication number
WO2000038184A1
WO2000038184A1 PCT/FR1999/003203 FR9903203W WO0038184A1 WO 2000038184 A1 WO2000038184 A1 WO 2000038184A1 FR 9903203 W FR9903203 W FR 9903203W WO 0038184 A1 WO0038184 A1 WO 0038184A1
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WO
WIPO (PCT)
Prior art keywords
metal
recording medium
layer
optical recording
optical
Prior art date
Application number
PCT/FR1999/003203
Other languages
French (fr)
Inventor
Bernard Bechevet
Marie-Françoise Armand
Patrick Chaton
Etienne Quesnel
Original Assignee
Commissariat A L'energie Atomique
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Commissariat A L'energie Atomique filed Critical Commissariat A L'energie Atomique
Priority to JP2000590169A priority Critical patent/JP2003511805A/en
Priority to EP99961111A priority patent/EP1141953A1/en
Publication of WO2000038184A1 publication Critical patent/WO2000038184A1/en

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Classifications

    • 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
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/258—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of reflective layers
    • G11B7/2585—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of reflective layers based on aluminium
    • 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
    • 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
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
    • G11B7/2578—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials
    • 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
    • G11B7/26—Apparatus or processes specially adapted for the manufacture of record carriers
    • 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
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
    • G11B2007/25705—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials
    • G11B2007/25713—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials containing nitrogen
    • 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
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
    • G11B2007/25705—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials
    • G11B2007/25715—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials containing oxygen
    • 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
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
    • G11B2007/25705—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials
    • G11B2007/25718—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials containing halides (F, Cl, Br, l)
    • 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
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/253—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates
    • G11B7/2533—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising resins

Definitions

  • the present invention relates to an optical recording medium and a method for producing this medium.
  • the invention finds an application in the field of recording on optical discs, for example for so-called recordable compact discs, abbreviated CD-R ("Compact Disc Recordable"), or digital recordable versatile discs, abbreviated DVD- R ("Digital Versatile Disc Recordable”) or single writing and multiple reading discs, abbreviated WORM ("Write Once Read Many").
  • CD-R Compact Disc Recordable
  • DVD- R Digital Versatile Disc Recordable
  • WORM Write Once Read Many
  • CD-R compact and recordable (or writable) disc
  • CD-R compact and recordable (or writable) disc
  • the manufacturing technique used today uses a dye polymer ("Dye Polymer”) sensitive to a specific wavelength. When exposed to high power, a reaction occurs in the organic product which makes the exposed area opaque at the wavelength used.
  • a disc of this type generally comprises a transparent substrate in which a spiral track has been formed where the information is written. The product organic is deposited on the entire surface of the disc by spreading with a spinner. A deposit of gold or silver is then made to obtain a reflective layer. Finally, on this stack is deposited a protective resin.
  • the disc is read and written through the substrate.
  • the reflectivity of the organic layer-reflective layer stack is compatible with that of CD and CD-ROM discs (high reflectivity greater than 65%, low reflectivity less than 35%).
  • CD and CD-ROM drives can read CD-Rs, which explains the interest in this type of medium.
  • the object of the present invention is precisely to remedy this drawback by proposing a new optical recording medium compatible with existing readers, that is to say having a high reflectivity before writing and low thereafter.
  • this stack comprises at least one very thin metallic layer and at least one transparent layer.
  • very thin is meant a layer with a thickness of less than about 30 nm.
  • Such metallic layers have surprising properties linked to their very small thickness. These properties, as such, have been described in the article by E. QUESNEL, P. CHATON, 0. LARTIGUE and F. BAUME entitled: "A very thin coating technology for the production of broad band absorbers” published in " Proceedings of Optical Interference Coatings ", Arlington, OSA Technical Digest Series, vol. 9, p. 346-347, 1998.
  • advantage is taken of these properties to produce an optical recording medium.
  • such very thin metallic layers have a reflectivity greater than 65% before any optical irradiation, reflectivity which falls to less than 35% or even to 5-10% after appropriate irradiation. The reflectivity therefore varies well in the direction sought.
  • the support of the invention also has the advantage that its optical properties are largely independent of the wavelength, in a range from 400 to 950 nm. This achromatism is kept for the optical index, which makes it possible to envisage different writing and reading geometries, for example at 45 °. Compatibility with DVD players and later with players using low wavelengths is thus respected. Furthermore, the recording medium of the invention is insensitive to sunlight and resists a temperature above 150 ° C (which is higher than the stability range of the plastic substrate).
  • the writing can be done in one direction or the other because the stacking can be symmetrical.
  • the subject of the present invention is an optical recording medium comprising a substrate supporting a stack of layers comprising a metal layer of thickness less than about 30 nm capable of having a reflectivity greater than about 65% before optical irradiation and less than about 35% after appropriate optical irradiation and at least one transparent layer.
  • the material of the transparent layer (s) is an oxide, or a nitride or a fluoride of the metal of the metal layer.
  • the very thin metal layer is surrounded by two transparent layers.
  • a stack of alternately metallic and transparent layers can be formed.
  • the metal of the metal layer is advantageously taken from the group consisting of aluminum, titanium, zirconium, tungsten, molybdenum, hafnium and their alloys.
  • the present invention also relates to a method for producing the support which has just been defined. According to this method, a stack is formed on a substrate of at least one metal layer of thickness less than approximately 30 nm and capable of having a reflectivity greater than approximately 65% before optical irradiation and less than approximately 35% after appropriate optical irradiation and at least one transparent layer, by sputtering.
  • the gas used for sputtering is advantageously taken from the group consisting of oxygen, nitrogen and fluorine, the metal compound then being respectively an oxide, a nitride or a fluoride of the metal.
  • Figure 1 shows a recording medium according to the invention
  • FIG. 1 shows a transparent substrate 10 (for example made of glass or plastic) under which a spiral groove has been formed by any suitable means.
  • a stack of layers is deposited on this spiral relief.
  • this stack comprises a metallic layer 20, framed by two transparent layers 21 and 22.
  • the metallic layer 20 can be made of aluminum and the transparent layers 21, 22 made of alumina (Al 2 0 3 ).
  • the thickness of the metal layer 20 is less than 30 nm and, for example, of the order of 10 nm (tests have been carried out by the Applicant at 27 nm, 15 nm and 7.5 nm).
  • the thickness of the transparent layers 21, 23 can be greater and for example of the order of 50 to 100 nm.
  • FIG. 2 shows a top view of a recording area (or point) 32 obtained by irradiation by means of a light source, for example a laser diode.
  • a light source for example a laser diode.
  • the reflectivity falls below 35% while without irradiation, the bottom 33 of the runway 12 has a reflectivity greater than 65%. The discrimination between written and unwritten areas is therefore easy.
  • FIG. 3 shows the reflectivity of the stack as a function of the wavelength ⁇ expressed in nanometer, in the case of a 10 nm layer of aluminum surrounded by two layers of alumina (A1 2 0 3 ) 50 nm thick.
  • Curve 40 corresponds to the reflectivity of the stack outside the written area (zoe 33 in FIG. 2) and curve 42 to the reflectivity of a written area (32).
  • the first is in the range of 65 to 70% and the second in the range of 5 to 10%.
  • the range in which these reflectivities present such values is very wide since it goes substantially from 400 nm to 950 nm.
  • the Applicant has thus produced recording media under the following conditions:

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Optical Record Carriers And Manufacture Thereof (AREA)
  • Manufacturing Optical Record Carriers (AREA)

Abstract

The invention concerns an optical recording medium and a method for making said medium, characterised in that said medium comprises a stack of layers (20, 21, 22) including at least a very thin metal layer (20) and at least a transparent layer (21, 22). The metal layer (20) can be in aluminium and the transparent layers (21, 22) in alumina. The invention is useful for making optical recording discs.

Description

SUPPORT D'ENREGISTREMENT OPTIQUE ET PROCEDE DE REALISATION DE CE SUPPORT OPTICAL RECORDING MEDIUM AND METHOD FOR PRODUCING THE SAME
DESCRIPTIONDESCRIPTION
Domaine techniqueTechnical area
La présente invention a pour objet un support d'enregistrement optique et un procédé de réalisation de ce support. L'invention trouve une application dans le domaine de l'enregistrement sur disques optiques, par exemple pour les disques dits compacts enregistrables, en abrégé CD-R ("Compact Disc Recordable" ) , ou les disques polyvalents numériques enregistrables, en abrégé DVD-R ("Digital Versatile Disc Recordable") ou les disques à une seule écriture et plusieurs lectures, en abrégé WORM ("Write Once Read Many") .The present invention relates to an optical recording medium and a method for producing this medium. The invention finds an application in the field of recording on optical discs, for example for so-called recordable compact discs, abbreviated CD-R ("Compact Disc Recordable"), or digital recordable versatile discs, abbreviated DVD- R ("Digital Versatile Disc Recordable") or single writing and multiple reading discs, abbreviated WORM ("Write Once Read Many").
Etat de la technique antérieure Le disque dit compact et enregistrable (ou inscriptible) , en abrégé CD-R, est maintenant produit industriellement et rencontre un grand succès commercial (production prévue pour 1998 : 400 millions de disques, ce qui représente un doublement par rapport à 1997) . La technique de fabrication utilisée aujourd'hui utilise un polymère à colorant ("Dye Polymer") sensible à une longueur d'onde bien déterminée. Par insolation à forte puissance, une réaction se produit dans le produit organique qui rend la zone insolée opaque à la longueur d'onde utilisée. Un disque de ce type comprend en général un substrat transparent dans lequel a été formée une piste spiralée où sont inscrites les informations. Le produit organique est déposé sur toute la surface du disque par étalement à la tournette. Un dépôt d'or ou d'argent est ensuite effectué pour obtenir une couche réfléchissante. Enfin, sur cet empilement est déposée une résine de protection.State of the prior art The so-called compact and recordable (or writable) disc, abbreviated to CD-R, is now produced industrially and has met with great commercial success (production planned for 1998: 400 million discs, which represents a doubling compared to to 1997). The manufacturing technique used today uses a dye polymer ("Dye Polymer") sensitive to a specific wavelength. When exposed to high power, a reaction occurs in the organic product which makes the exposed area opaque at the wavelength used. A disc of this type generally comprises a transparent substrate in which a spiral track has been formed where the information is written. The product organic is deposited on the entire surface of the disc by spreading with a spinner. A deposit of gold or silver is then made to obtain a reflective layer. Finally, on this stack is deposited a protective resin.
Le disque est lu et écrit à travers le substrat. La réflectivité de l'empilement couche organique-couche réfléchissante est compatible avec celle des disques CD et CD-ROM (réflectivité forte supérieure à 65%, réflectivité faible inférieure à 35%). Ainsi, les lecteurs de CD et CD-ROM peuvent-ils lire les CD-R, ce qui explique l'intérêt pour ce type de support.The disc is read and written through the substrate. The reflectivity of the organic layer-reflective layer stack is compatible with that of CD and CD-ROM discs (high reflectivity greater than 65%, low reflectivity less than 35%). Thus, CD and CD-ROM drives can read CD-Rs, which explains the interest in this type of medium.
Cette technique ne va cependant pas sans poser des problèmes. Le produit organique est sensible à la lumière et vieillit. De plus, un problème de compatibilité en longueur d'onde peut se poser selon les différents types de disque. En effet, les disques DVD travaillent avec une longueur d'onde de 650 nm, et les disques CD-R ne peuvent pas être lus dans les lecteurs correspondants. C'est la raison pour laquelle beaucoup de laboratoires travaillent à remplacer le produit organique par un produit inorganique du type à changement de phase (par exemple des chalcogénures ou encore des alliages de ZnO, Ga20, GeO, etc...). Cependant, un problème essentiel reste à résoudre qui est celui d'obtenir un support à forte réflectivité avant écriture. En effet, tous ces produits inorganiques à changement de phase présentent une réflectivité intrinsèque faible, qui est rendue forte par chauffage ou destruction de la couche active. Les zones inscrites présentent alors une réflectivité forte, ce qui est l'inverse des CD-R organiques et des CD et CD-ROM. Il y a donc incompatibilité avec les lecteurs existants.This technique is not without problems, however. The organic product is sensitive to light and ages. In addition, a wavelength compatibility problem may arise according to the different types of disc. Indeed, DVD discs work with a wavelength of 650 nm, and CD-R discs cannot be read in the corresponding players. This is the reason why many laboratories are working to replace the organic product with an inorganic product of the phase change type (for example chalcogenides or even alloys of ZnO, Ga 2 0, GeO, etc.). However, an essential problem remains to be solved which is that of obtaining a medium with high reflectivity before writing. Indeed, all of these inorganic phase change products have a low intrinsic reflectivity, which is made strong by heating or destroying the active layer. The inscribed areas then have a high reflectivity, which is the reverse of organic CD-Rs and CD and CD-ROM. There is therefore incompatibility with existing readers.
La présente invention a justement pour but de remédier à cet inconvénient en proposant un nouveau support d'enregistrement optique compatible avec les lecteurs existants, c'est-à-dire présentant une réflectivité élevée avant écriture et faible ensuite.The object of the present invention is precisely to remedy this drawback by proposing a new optical recording medium compatible with existing readers, that is to say having a high reflectivity before writing and low thereafter.
Exposé de 1 ' invention Ce but est atteint, selon l'invention, grâce à l'utilisation d'un empilement de couches particulier. Selon l'invention, cet empilement comprend au moins une couche métallique très mince et au moins une couche transparente. Par "très mince", on entend une couche d'épaisseur inférieure à environ 30 nm. De telles couches métalliques présentent des propriétés surprenantes liées à leur très faible épaisseur. Ces propriétés, en tant que telles, ont été décrites dans l'article de E. QUESNEL, P. CHATON, 0. LARTIGUE et F. BAUME intitulé : "A very thin coating technology for the production of broad band absorbers" publié dans "Proceedings of Optical Interférence Coatings", Tucson, OSA Technical Digest Séries, vol. 9, p. 346-347, 1998. Selon l'invention, on tire profit de ces propriétés pour réaliser un support d'enregistrement optique. En effet, de telles couches métalliques très fines présentent une réflectivité supérieure à 65% avant toute irradiation optique, réflectivité qui tombe à moins de 35% voire à 5-10% après irradiation appropriée. La réflectivité varie donc bien dans le sens recherché.Disclosure of the invention This object is achieved, according to the invention, through the use of a particular stack of layers. According to the invention, this stack comprises at least one very thin metallic layer and at least one transparent layer. By "very thin" is meant a layer with a thickness of less than about 30 nm. Such metallic layers have surprising properties linked to their very small thickness. These properties, as such, have been described in the article by E. QUESNEL, P. CHATON, 0. LARTIGUE and F. BAUME entitled: "A very thin coating technology for the production of broad band absorbers" published in " Proceedings of Optical Interference Coatings ", Tucson, OSA Technical Digest Series, vol. 9, p. 346-347, 1998. According to the invention, advantage is taken of these properties to produce an optical recording medium. Indeed, such very thin metallic layers have a reflectivity greater than 65% before any optical irradiation, reflectivity which falls to less than 35% or even to 5-10% after appropriate irradiation. The reflectivity therefore varies well in the direction sought.
Le support de l'invention présente en outre l'avantage que ses propriétés optiques sont largement indépendantes de la longueur d'onde, dans une plage allant de 400 à 950 nm. Cet achromatisme est conservé pour l'indice optique, ce qui permet d'envisager des géométries d'écriture et de lecture différentes, par exemple à 45°. Ainsi, la compatibilité avec les lecteurs de DVD et, plus tard, avec des lecteurs utilisant des longueurs d'onde basses est-elle respectée. Par ailleurs, le support d'enregistrement de l'invention est insensible à la lumière du soleil et résiste à une température supérieure à 150°C (ce qui est supérieur au domaine de stabilité du substrat plastique) .The support of the invention also has the advantage that its optical properties are largely independent of the wavelength, in a range from 400 to 950 nm. This achromatism is kept for the optical index, which makes it possible to envisage different writing and reading geometries, for example at 45 °. Compatibility with DVD players and later with players using low wavelengths is thus respected. Furthermore, the recording medium of the invention is insensitive to sunlight and resists a temperature above 150 ° C (which is higher than the stability range of the plastic substrate).
Enfin, l'écriture peut s'effectuer dans un sens ou dans l'autre car l'empilement peut être symétrique.Finally, the writing can be done in one direction or the other because the stacking can be symmetrical.
De façon plus précise, la présente invention a pour objet un support d'enregistrement optique comprenant un substrat supportant un empilement de couches comprenant une couche métallique d'épaisseur inférieure à environ 30 nm apte à présenter une réflectivité supérieure à environ 65% avant irradiation optique et inférieure à environ 35% après irradiation optique appropriée et au moins une couche transparente.More specifically, the subject of the present invention is an optical recording medium comprising a substrate supporting a stack of layers comprising a metal layer of thickness less than about 30 nm capable of having a reflectivity greater than about 65% before optical irradiation and less than about 35% after appropriate optical irradiation and at least one transparent layer.
De préférence, le matériau de la (des) couche (s) transparente (s) est un oxyde, ou un nitrure ou un fluorure du métal de la couche métallique.Preferably, the material of the transparent layer (s) is an oxide, or a nitride or a fluoride of the metal of the metal layer.
Selon un mode de réalisation, la couche métallique très mince est encadrée par deux couches transparentes.According to one embodiment, the very thin metal layer is surrounded by two transparent layers.
Selon un autre mode de réalisation, on peut constituer un empilement de couches alternativement métalliques et transparentes.According to another embodiment, a stack of alternately metallic and transparent layers can be formed.
Le métal de la couche métallique est avantageusement pris dans le groupe constitué par l'aluminium, le titane, le zirconium, le tungstène, le molybdène, l'hafnium et leurs alliages.The metal of the metal layer is advantageously taken from the group consisting of aluminum, titanium, zirconium, tungsten, molybdenum, hafnium and their alloys.
La présente invention a également pour objet un procédé de réalisation du support qui vient d'être défini. Selon ce procédé, on forme sur un substrat un empilement d'au moins une couche métallique d'épaisseur inférieure à environ 30 nm et apte à présenter une réflectivité supérieure à environ 65% avant irradiation optique et inférieure à environ 35% après irradiation optique appropriée et d'au moins une couche transparente, par pulvérisation cathodique.The present invention also relates to a method for producing the support which has just been defined. According to this method, a stack is formed on a substrate of at least one metal layer of thickness less than approximately 30 nm and capable of having a reflectivity greater than approximately 65% before optical irradiation and less than approximately 35% after appropriate optical irradiation and at least one transparent layer, by sputtering.
On peut procéder avantageusement par pulvérisation cathodique d'un métal, pour obtenir la couche métallique très mince, et par pulvérisation cathodique du même métal en présence d'un gaz pour obtenir laIt is advantageous to proceed by sputtering a metal, to obtain the very thin metallic layer, and by sputtering the same metal in the presence of a gas to obtain the
(les) couche (s) transparente (s) , qui est (sont) alors en un composé dudit métal.(the) transparent layer (s), which is (are) then made of a compound of said metal.
Le gaz utilisé pour la pulvérisation cathodique est avantageusement pris dans le groupe constitué par l'oxygène, l'azote et le fluor, le composé du métal étant alors respectivement un oxyde, un nitrure ou un fluorure du métal.The gas used for sputtering is advantageously taken from the group consisting of oxygen, nitrogen and fluorine, the metal compound then being respectively an oxide, a nitride or a fluoride of the metal.
Brève description des dessins - la figure 1 montre un support d'enregistrement conforme à l'invention ;Brief description of the drawings - Figure 1 shows a recording medium according to the invention;
- la figure 2 montre un détail des pistes d'enregistrement en vue de dessus ;- Figure 2 shows a detail of the recording tracks in top view;
- la figure 3 montre les variations de réflectivité d'un tel support en fonction de la longueur d'onde. Description détaillée de modes particuliers de réalisation- Figure 3 shows the reflectivity variations of such a support as a function of the wavelength. Detailed description of particular embodiments
Sur la figure 1, on voit un substrat 10 transparent (par exemple en verre ou en plastique) sous lequel une gorge spiralee a été formée par tout moyen approprié. Sur ce relief spirale est déposé un empilement de couches. Dans le mode de réalisation illustré, cet empilement comprend une couche métallique 20, encadrée par deux couches transparentes 21 et 22. La couche métallique 20 peut être en aluminium et les couches transparentes 21, 22 en alumine (Al203) . L'épaisseur de la couche métallique 20 est inférieure à 30 nm et, par exemple, de l'ordre de 10 nm (des tests ont été effectués par le Demandeur à 27 nm, 15 nm et 7,5 nm) . L'épaisseur des couches transparentes 21, 23 peut être plus importante et par exemple de l'ordre de 50 à 100 nm.FIG. 1 shows a transparent substrate 10 (for example made of glass or plastic) under which a spiral groove has been formed by any suitable means. A stack of layers is deposited on this spiral relief. In the illustrated embodiment, this stack comprises a metallic layer 20, framed by two transparent layers 21 and 22. The metallic layer 20 can be made of aluminum and the transparent layers 21, 22 made of alumina (Al 2 0 3 ). The thickness of the metal layer 20 is less than 30 nm and, for example, of the order of 10 nm (tests have been carried out by the Applicant at 27 nm, 15 nm and 7.5 nm). The thickness of the transparent layers 21, 23 can be greater and for example of the order of 50 to 100 nm.
Sous cet empilement, on trouve éventuellement une couche 30 de résine de protection. Les pistes dans lesquelles l'information peut être enregistrées sont référencées 12.Under this stack, there is possibly a layer 30 of protective resin. The tracks in which the information can be recorded are referenced 12.
La figure 2 montre en vue de dessus une zone (ou point) 32 d'enregistrement obtenue par irradiation au moyen d'une source lumineuse, par exemple une diode laser. Dans une telle zone 32, la réflectivité tombe en dessous de 35% alors que sans irradiation, le fond 33 de la piste 12 présente une réflectivité supérieure à 65%. La discrimination entre zones écrites et zones non écrites est donc aisée.FIG. 2 shows a top view of a recording area (or point) 32 obtained by irradiation by means of a light source, for example a laser diode. In such an area 32, the reflectivity falls below 35% while without irradiation, the bottom 33 of the runway 12 has a reflectivity greater than 65%. The discrimination between written and unwritten areas is therefore easy.
La figure 3 montre la réflectivité de l'empilement en fonction de la longueur d'onde λ exprimée en nanomètre, dans le cas d'une couche de 10 nm d'aluminium encadrée par deux couches d'alumine (A1203) de 50 nm d'épaisseur. La courbe 40 correspond à la réflectivité de l'empilement hors zone écrite (zoe 33 sur la figure 2) et la courbe 42 à la réflectivité d'une zone écrite (32). On voit que la première est de l'ordre de 65 à 70% et la seconde de l'ordre de 5 à 10%. De plus, la plage dans laquelle ces réflectivités présentent de telles valeurs est très large puisqu'elle va sensiblement de 400 nm à 950 nm.FIG. 3 shows the reflectivity of the stack as a function of the wavelength λ expressed in nanometer, in the case of a 10 nm layer of aluminum surrounded by two layers of alumina (A1 2 0 3 ) 50 nm thick. Curve 40 corresponds to the reflectivity of the stack outside the written area (zoe 33 in FIG. 2) and curve 42 to the reflectivity of a written area (32). We see that the first is in the range of 65 to 70% and the second in the range of 5 to 10%. In addition, the range in which these reflectivities present such values is very wide since it goes substantially from 400 nm to 950 nm.
Pour réaliser le support de l'invention, on procède avantageusement par pulvérisation cathodique du matériau métallique, à la fois pour réaliser la couche métallique et la ou les couche (s) transparente (s) .To carry out the support of the invention, one advantageously proceeds by cathodic sputtering of the metallic material, at the same time to realize the metallic layer and the transparent layer (s).
Le Demandeur a ainsi réalisé des supports d'enregistrement dans les conditions suivantes :The Applicant has thus produced recording media under the following conditions:
- Machine de pulvérisation : SCM 600 à 3 postes de pulvérisation, - Substrat en verre de 120 mm de diamètre et 1,2 mm d'épaisseur,- Spraying machine: SCM 600 with 3 spraying stations, - Glass substrate 120 mm in diameter and 1.2 mm thick,
- Matériau transparent : A1203 d'indice optique 1,6,- Transparent material: A1 2 0 3 with optical index 1.6,
- Métal : aluminium d'épaisseur 10 nm et d'indice 2,66 à (λ=780 nm) ,- Metal: aluminum 10 nm thick and index 2.66 to (λ = 780 nm),
- Réflectivité de l'empilement avant écriture à 780 nm supérieure à 60%,- Reflectivity of the stack before writing at 780 nm greater than 60%,
- Puissance d'écriture : entre 10 mW et 20 mW,- Write power: between 10 mW and 20 mW,
- Rapport signal sur bruit à 2,4 m/s de vitesse de défilement, 1 MHz et 200 ns d'impulsion : supérieur à 46 dB. - Signal-to-noise ratio at 2.4 m / s of frame rate, 1 MHz and 200 ns of pulse: greater than 46 dB.

Claims

REVENDICATIONS
1. Support d'enregistrement optique comprenant un substrat supportant un empilement de couches comprenant une couche métallique (20) d'épaisseur inférieure à environ 30 nm apte à présenter une réflectivité supérieure à environ 65% avant irradiation optique et inférieure à environ 35% après irradiation optique appropriée et au moins une couche transparente (21, 22) .1. Optical recording medium comprising a substrate supporting a stack of layers comprising a metal layer (20) of thickness less than approximately 30 nm capable of having a reflectivity greater than approximately 65% before optical irradiation and less than approximately 35% after appropriate optical irradiation and at least one transparent layer (21, 22).
2. Support d'enregistrement optique selon la revendication 1, dans lequel le matériau de la (des) couche (s) transparente (s) (21, 22) est un oxyde, ou un nitrure ou un fluorure du métal de la couche métallique .2. The optical recording medium according to claim 1, in which the material of the transparent layer (s) (21, 22) is an oxide, or a nitride or a fluoride of the metal of the metallic layer. .
3. Support d'enregistrement optique selon la revendication 1, dans lequel la couche métallique (20) est encadrée par deux couches transparentes (21, 22).3. Optical recording medium according to claim 1, in which the metal layer (20) is framed by two transparent layers (21, 22).
4. Support d'enregistrement optique selon la revendication 1, dans lequel l'empilement comprend une alternance de couches métalliques (20) et de couches transparentes (21, 23) .4. The optical recording medium according to claim 1, in which the stack comprises alternating metallic layers (20) and transparent layers (21, 23).
5. Support d'enregistrement optique selon la revendication 1, dans lequel le métal de la couche métallique (20) est pris dans le groupe constitué par l'aluminium, le titane, le zirconium, le tungstène, le molybdène, l'hafnium et leurs alliages. 5. Optical recording medium according to claim 1, in which the metal of the metallic layer (20) is taken from the group consisting of aluminum, titanium, zirconium, tungsten, molybdenum, hafnium and their alloys.
6. Support d'enregistrement optique selon l'une quelconque des revendications 1 à 5, caractérisé en ce qu'il présente la forme d'un disque avec une piste d'enregistrement (12).6. Optical recording medium according to any one of claims 1 to 5, characterized in that it has the shape of a disc with a recording track (12).
7. Disque optique enregistrable (CD-R), caractérisé en ce qu'il comprend un support selon la revendication 6.7. Recordable optical disc (CD-R), characterized in that it comprises a support according to claim 6.
8. Disque optique polyvalent numérique enregistrable (DVD-R), caractérisé en ce qu'il comprend un support selon la revendication 6.8. Recordable digital versatile optical disc (DVD-R), characterized in that it comprises a support according to claim 6.
9. Disque optique à une seule écriture et à plusieurs lectures (WORM) , caractérisé en ce qu'il comprend un support selon la revendication 6.9. Optical disc with a single writing and with several readings (WORM), characterized in that it comprises a support according to claim 6.
10. Procédé de réalisation d'un support d'enregistrement optique conforme à la revendication 1, caractérisé en ce qu'on forme sur un substrat (10) un empilement d'au moins une couche métallique d'épaisseur inférieure à 30 nm et apte à présenter une réflectivité supérieure à environ 65% avant irradiation optique et inférieure à environ 35% après irradiation optique appropriée (20) et d'au moins une couche transparente (21, 22), par pulvérisation cathodique.10. A method of producing an optical recording medium according to claim 1, characterized in that a stack of at least one metal layer with a thickness of less than 30 nm and suitable for forming on a substrate (10) is formed. having a reflectivity greater than about 65% before optical irradiation and less than about 35% after appropriate optical irradiation (20) and at least one transparent layer (21, 22), by sputtering.
11. Procédé selon la revendication 10, dans lequel on procède par pulvérisation cathodique d'un métal pour obtenir la couche métallique (20) et par pulvérisation cathodique du même métal en présence d'un gaz pour obtenir la (les) couche (s) transparente (s) (21, 22), qui est (sont) alors en un composé dudit métal. 11. The method of claim 10, wherein it is carried out by sputtering a metal to obtain the metal layer (20) and by sputtering the same metal in the presence of a gas to obtain the layer (s). transparent (s) (21, 22), which is (are) then in a compound of said metal.
12. Procédé selon la revendication 11, dans lequel le gaz utilisé pour la pulvérisation cathodique est pris dans le groupe constitué par l'oxygène, l'azote et le fluor, le composé du métal étant alors respectivement un oxyde, un nitrure, ou un fluorure du métal.12. The method of claim 11, wherein the gas used for sputtering is taken from the group consisting of oxygen, nitrogen and fluorine, the metal compound then being respectively an oxide, a nitride, or a metal fluoride.
13. Procédé selon la revendication 10, dans lequel on pulvérise au moins un métal pris dans le groupe constitué par l'aluminium, le titane, le zirconium, le tungstène, le molybdène, l'hafnium. 13. The method of claim 10, wherein spraying at least one metal taken from the group consisting of aluminum, titanium, zirconium, tungsten, molybdenum, hafnium.
PCT/FR1999/003203 1998-12-22 1999-12-20 Optical recording medium and method for making same WO2000038184A1 (en)

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FR9816251A FR2787619B1 (en) 1998-12-22 1998-12-22 OPTICAL RECORDING MEDIUM AND METHOD FOR PRODUCING THE SAME

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JPS6411890A (en) * 1987-07-07 1989-01-17 Nec Corp Optical recording medium
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FR2787619B1 (en) 2001-08-17

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