EP1103047A1 - Pre-engraved substrate for magnetic, magneto-optical or phase transition optical disc, functioning by first surface recording in the lands, manufacturing method and resulting disc - Google Patents

Pre-engraved substrate for magnetic, magneto-optical or phase transition optical disc, functioning by first surface recording in the lands, manufacturing method and resulting disc

Info

Publication number
EP1103047A1
EP1103047A1 EP98941545A EP98941545A EP1103047A1 EP 1103047 A1 EP1103047 A1 EP 1103047A1 EP 98941545 A EP98941545 A EP 98941545A EP 98941545 A EP98941545 A EP 98941545A EP 1103047 A1 EP1103047 A1 EP 1103047A1
Authority
EP
European Patent Office
Prior art keywords
layer
optical
surface layer
support
magneto
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP98941545A
Other languages
German (de)
French (fr)
Inventor
Jean Ledieu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
OTB Group BV
Original Assignee
ODME International BV
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 ODME International BV filed Critical ODME International BV
Publication of EP1103047A1 publication Critical patent/EP1103047A1/en
Withdrawn legal-status Critical Current

Links

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
    • G11B7/26—Apparatus or processes specially adapted for the manufacture of record carriers
    • G11B7/261—Preparing a master, e.g. exposing photoresist, electroforming
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • 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
    • G11B11/105—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 using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
    • G11B11/1055—Disposition or mounting of transducers relative to record carriers
    • G11B11/10576—Disposition or mounting of transducers relative to record carriers with provision for moving the transducers for maintaining alignment or spacing relative to the carrier
    • G11B11/10578—Servo format, e.g. prepits, guide tracks, pilot signals
    • 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
    • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • G11B7/00745—Sectoring or header formats within a track
    • 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
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0938—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following servo format, e.g. guide tracks, pilot signals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/90—Magnetic feature

Definitions

  • Pre-etched substrate for magnetic, magneto-optical or optical phase transition disc operating by recording on the first surface in the lands, its manufacturing process and disc obtained.
  • the invention relates to a pre-etched substrate for a memory disc recordable by a constraint of the magneto-optical or magnetic type or with phase transition. This stress is applied to the first surface of the substrate and not through it as is the case in traditional optical discs. In addition, this constraint will only be applied to the parts of the substrate appearing between the pre-etched areas, these parts being often called "lands" in the state of the art. It also relates to a process for manufacturing this substrate as well as to the recordable memory disc comprising this substrate or obtained by this process.
  • recordable memory disks or floppy disks are widely used, for example, in the computer field as computer hard disks.
  • These discs or floppy disks operate in first surface recording mode and are magnetic discs with optical guided assistance also called optical assisted magnetic discs, magneto-optical discs with optical guided assistance or phase transition optical discs. They are generally composed of a support comprising a peformatting signal and of a mono- or multilayer structure constituting the recordable memory and deposited on this support, after the etching of the preformatting in the support.
  • the monolayer or multilayer structure of the recordable memory comprises a layer in which the information to be stored is recorded.
  • the recording in the recordable layer is done by direct application, on the first surface, that is to say without passing through the support, of the appropriate stress.
  • This constraint can be either a magnetic field, or a thermal energy provided by a light beam, or a combination of a magnetic field and a thermal energy.
  • information is recorded in the recordable layer by creating zones in which the magnetic field is oriented differently (inverted) compared to the magnetic field of other zones and, in discs phase transition optics, the recording is carried out by creating zones in which the material constituting the recordable layer has undergone a phase transformation, that is to say has passed either from an amorphous structure to a crystalline structure, either from a crystal structure to an amorphous structure.
  • the information is then read by detecting either different magnetic fields or differences reflectivity due to the change in structure of the material, respectively.
  • the recordable layer is made of a hard magnetic material or capable of phase transitions.
  • This type of disc makes it possible to achieve very large storage capacities but their performance is still limited by the alteration of the signal / noise ratio of the read signal of the preformate, also called C / N ratio, generated by the deposition of the or layers constituting the recordable memory, on the preformate etched at the start of the substrate manufacturing cycle.
  • the invention aims to overcome this problem by proposing a recordable memory disc of the magneto-optical, magnetic or optical phase transition type having a signal / noise ratio of the read signal of the improved preformate and which is simpler and more simple to manufacture. economical than discs of this type currently manufactured.
  • the invention provides a pre-etched substrate for a memory disc recordable by a constraint of the magneto-optical or magnetic or optical phase transition type which comprises (a) a support having on its surface a layer of a reflective material and making it possible to obtain an optically polished surface, (b) on this layer of reflective material a monolayer or multilayer structure comprising at least one layer which can be recorded by applying a magnetic, magneto type stress on the first surface of the substrate -optical or phase transition optics, the reflective material layer and the absorbent pads mono- or multi structure comprising a succession of grooves and / or pits representing a preformat signal and extending from the surface of the more than 1 • outermost layer of the structure or mono- multi-layers up to a predetermined depth of the layer of reflective material less than the thickness of this layer of reflective material, and (c) optionally a protective layer deposited on and completely covering the last layer of the mono structure - or multi-layers, the side walls of the grooves and / or micro-cuvettes
  • the support and the layer of reflective material and making it possible to obtain a surface with optical polish are composed of different materials.
  • the support could for example be made of glass or aluminum and the layer of reflective material and making it possible to obtain an optically polished surface could for example be made of nickel, or brass, or aluminum, or chromium or titanium nitride. .
  • the support and the layer of reflective material are made of the same material.
  • the support and the layer of reflective material form a single piece.
  • An example of a material which can be used in this second embodiment is aluminum.
  • exemplary materials constituting said at least one recordable layer are Ag-In-Sb-Te, Tb-Fe-Co, Tb-Fe-Cr, Tb-Fe-Co-Cr, Tb-Ge-Sb, Tb-Ge-In, Tb-Ge-Ag, Fe-Cr, Fe-Co or their alloys and mixtures.
  • the invention also relates to a method for manufacturing a pre-etched substrate which comprises:
  • a step carried out in the first place of depositing a mono- or multi-layer structure comprising at least one layer which can be recorded by application to the first surface of the substrate of a stress of the magnetic, magneto-optical or optical transition type phase, on the surface layer of a reflective material and making it possible to obtain an optical polish of a support
  • a step carried out in the second place of etching a succession of grooves and / or microcuvettes representing a signal of preformatting in the monolayer or multilayer structure and in the surface layer of a reflective material, the etching extending from the outermost layer of the monolayer or multilayer structure to a predetermined depth of the surface of reflective material less than the thickness of this surface layer of reflective material
  • an optional step, last performed of depositing a layer protection (11) on the surface of the last layer of the monolayer or multilayer structure.
  • the step of etching the succession of microcuvettes and / or grooves representing a preformatting signal comprises the steps of:
  • the support consists of a material different from that of the surface layer made of a reflective material.
  • the support may be made of glass or aluminum and the surface layer of nickel, or of brass, or of aluminum, or of chromium, or of titanium ni ride.
  • the support of the surface layer of reflective material are made of the same material.
  • the support and the surface layer form a single piece.
  • An example of a material which can be used in these two cases is aluminum.
  • the invention also encompasses the magneto-optical, magnetic or optical phase transition disk which comprises the substrate pre-etched according to the invention or manufactured by the method of the invention.
  • FIG. 1 is an enlarged sectional view of a pre-etched substrate according to the prior art
  • - Figure 2 shows an enlarged sectional view of a pre-etched and recorded substrate of the prior art, that is to say a magneto-optical, magnetic or optical phase transition disc, of the art anterior;
  • - Figure 3 is an enlarged sectional view of an unetched, unregistered substrate according to the invention;
  • FIG. 4 shows an enlarged sectional view of a pre-etched substrate according to the invention
  • FIG. 5 shows an enlarged sectional view of a pre-etched substrate recorded according to the invention, that is to say a memory disc recordable by a constraint of the magnetic, magneto-optical or optical type with phase transition according to l invention
  • FIG. 6 shows an enlarged sectional view of a pre-etched substrate recorded according to the invention and comprising a protective layer.
  • the prior art method for manufacturing a pre-etched substrate consists in etching, by any suitable means, in the surface layer denoted 2, in FIG. 1, of a support denoted 1 in FIG. 1, the desired preformatting signal;
  • This preformatting signal makes it possible to ensure tracking, that is to say the tracking, centering and guiding of the reading laser beam, and possibly may contain address and clock information.
  • the surface layer 2 of the support 1 comprises a succession of grooves and / or microcuvettes or pits denoted 7 in FIG. 1 representing the desired preformatting signal and a succession of flat areas or lands denoted 6 in FIG. 1.
  • the surface layer 2 is made of a reflective material and making it possible to obtain a surface with optical polish.
  • the layer 2 will have the function of making it possible to obtain this surface state but will also always have to perform the function of desired reflectivity.
  • the layer 2 may be deposited, after etching, on the support 1, in which case the layer 2 will be as thin as possible.
  • the surface layer 2 will be present or absent and will be deposited before or after etching.
  • the first manufacturing step consists in etching the preformate in the support 1 or the surface layer 2 of this support 1, if the latter is present.
  • the second step of the method of the prior art consists in depositing the mono- or multi-layer structure comprising at least one recordable layer denoted 4 in FIG. 1.
  • a first and optional barrier layer 3 is deposited on the surface layer 2 of the support 1 comprising the successions of pits 7 and lands 6, then layer 4 is deposited which is the recordable layer proper on this barrier layer 3.
  • a second and optional barrier layer 5 is then deposited on the free surface of layer 4.
  • a distinctive characteristic of the pre-etched substrate of the prior art is that the external walls noted 8 in FIG. 1 of the grooves and / or microcuvettes 7 are made of the material constituting the last deposited layer of the monolayer or multilayer structure, here the material constituting layer 5, in contrast to the pre-etched substrate of the invention, as will be seen below.
  • the information to be stored is then recorded in the recordable layer 4 by application of the appropriate stress through the support 1, and in the zones denoted 6 ′ of the recordable layer 4 in FIG. 2 and corresponding to the lands 6 support 1.
  • the recording of the information in the recordable layer 4 is not done through the substrate, that is to say a recording on the first surface.
  • the method of manufacturing a pre-etched substrate according to the invention consists, as illustrated in FIGS. 3 and 4, of depositing first and in a first step the various layers 3, 4 and 5 defined above, on the surface layer 2 of a reflective material and making it possible to obtain an optical surface polish, then after this deposition only, to etch the succession of microcuvettes and / or grooves 7 representing the desired preformatting signal.
  • the walls denoted 8 of the grooves and / or microcuvettes 7, these walls 8 passing through the layers 2, 3, 4 and 5, consist solely of each of the materials constituting the layers 2, 3 , 4 and 5, in these layers 2, 3, 4 and 5, respectively.
  • the surface layer 2 is only present if the reflectivity and / or the surface condition of the support 1 are not satisfactory.
  • the surface layer 2 therefore here also has the function of bringing the desired reflectivity and surface condition to the support 1.
  • the preformatting signal is etched in the layers 3, 4 and 5 and in the surface layer 2 of the support 1, by formation of a succession of pits 7 representing this preformatting and lands signal 6.
  • the depth of the pits 7 is less than the thickness of the layers 2, 3, 4 and 5. This means that the pits 7 and lands 6 are formed only and in a single operation in layers 2, 3, 4 and 5.
  • the etching of the preformate is not deformed by the subsequent deposition of the layers constituting the mono- or multi-layer structure, as in the prior art.
  • This direct etching in these different layers provides a substantial advantage: the signal-to-noise reading ratio of the preformate is substantially improved.
  • An additional advantage of this manufacturing process is its simplification compared to the process of the prior art: with this process the different successive layers 2, 3, 4 and 5 are deposited with better homogeneity because they are each deposited on flat surfaces.
  • yet another advantage of the method for manufacturing the pre-etched substrate of the invention and the pre-etched substrate itself is that they are more economical to implement and to manufacture, respectively. Indeed, in the case where the surface layer 2 is a layer distinct from the support 1, and if a bad recording of the preformatting signal is carried out, only the layers 3, 4, 5 and possibly 2 are to be eliminated, which means that one can simply redeposit on the support 1 a new succession of layers as defined above and proceed to a new etching and / or a new recording. This process is therefore more economical in the event of an incident, since the production of the support 1 represents the most expensive element during the production of a pre-etched substrate.
  • the information to be stored is then recorded in the recordable layer as illustrated in FIG. 5, that is to say on the first surface of the substrate and as in the prior art.
  • the information to be stored in the recordable layer 4 is recorded in the lands 6 of the recordable layer 4.
  • the recordable layer 4 may be made of any suitable material.
  • suitable materials are Ag-ln-Sb-Te, Tb-Fe-Co, Tb-Fe-Cr, Tb-Fe-Co-Cr, Tb-Ge-Sb, Tb-Ge-In, Tb- Ge-Ag, Fe-Cr, Fe-Co or their alloys and mixtures.
  • the support 1 will be made of a material different from the surface layer 2.
  • the surface layer 2 may, for example be made of glass or aluminum and the surface layer 2 may, for example be made of nickel, or of brass, or of aluminum, or of chromium, or of titanium nitride.
  • the support 1 will be made of the same material as the surface layer 2 but the surface layer 2 will have been deposited on the support 1, for example by chemical coating or by spraying, to give the support 1 l 'desired surface finish.
  • the support 1 when the support 1 is made of the same material as the surface layer 2 and this material is reflective and makes it possible to obtain the desired surface state, the support 1 and the surface layer 2 form a single piece. In all cases, the depth of the grooves and / or microcuvettes in the surface layer 2 (independent or forming an integral part of the support 1) will be less than the thickness of this surface layer 2.
  • the actual etching of the preformate can be carried out by any suitable means but in particular by the following process:
  • a layer of photosensitive resin is deposited on the last layer 5 furthest from said support 1.
  • the preformatting signal is recorded, in the form of a latent image, in this layer of photosensitive resin either by the passing of a light beam modulated as a function of the preformatting signal, or, and preferably, by exposure to the photosensitive resin through a mask.
  • this mask can be a holographic mask.
  • the zones of exposed photosensitive resin are eliminated by any appropriate means, which leads to the creation of a series of grooves and / or microcuvettes in the layer of photosensitive resin.
  • these grooves and / or microcuvettes are transferred, for example by chemical etching, in the underlying layers, into the reflective surface layer 2, if present, or the support 1, if the surface layer 2 is part integral with the support 1 but at a depth less than the thickness of the surface layer 2 or of the support 1.
  • the residual photosensitive resin is eliminated by any appropriate means.
  • the pre-etched substrate of the invention and its manufacturing method are not applicable for the manufacture of traditional optical discs due, inter alia, to the position of the reflective layer 6 which makes the etching of the preformat invisible to through the support 1 when the latter is transparent.
  • the substrate of the invention has been described as comprising barrier layers 3 and 5, it may comprise only a recordable layer 4 or also comprise other layers, as required.
  • An example of such an optional additional layer is a so-called substrate protection layer, as shown in FIG. 6 where this protection layer is denoted 11, and which has the function of protecting the substrate against any external aggression of the type exposed to the atmosphere, scratch, etc.
  • This layer 11 will be made of any material that is neutral with respect to the recordable layer 4 and the tracking laser.
  • This additional layer 11 will be deposited before the actual recording of the information to be stored in the recordable layer 4, and this step is part of the process for manufacturing the substrate of the invention.
  • the thickness of this layer 11 can equally be such that the layer 11 will take the form of microcuvettes and / or grooves 7, or such that the layer 11 will completely fill these microcuvettes and / or grooves 7, that is to say will encapsulate the substrate.
  • the support 1 may be made of any suitable material provided that it allows to obtain the necessary surface finish.
  • the recordable layer 4 may be composed of other materials than those mentioned above and which make it possible to obtain a recordable memory as defined in the invention.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Optical Record Carriers (AREA)

Abstract

The invention concerns a pre-engraved substrate for a memory disc recordable by magnetic, magneto-optical or phase transition constraint, its manufacturing method and the resulting disc. Said pre-engraved substrate comprises a support (1) having at its surface a surface film (2) in a reflecting material and enabling to obtain a surface with optical polish and at least a recordable film (4), the surface film (2) and the film (4) comprising a succession of microgrooves and/or pits (7) representing a pre-formatting signal, the walls (8) of said pits and/or microgrooves (7) being formed in each of films (2) and (4) of the material constituting said film. The invention is useful for making magnetic, magneto-optical and phase transition optical discs, used particularly in the field of computers.

Description

«Substrat prégravé pour disque magnétique, magnéto-optique ou optique à transition de phase, fonctionnant par enregistrement en première surface dans les lands, son procédé de fabrication et disque obtenu». "Pre-etched substrate for magnetic, magneto-optical or optical phase transition disc, operating by recording on the first surface in the lands, its manufacturing process and disc obtained".
L'invention concerne un substrat prégravé pour un disque à mémoire enregistrable par une contrainte du type magnéto- optique ou magnétique ou à transition de phase. Cette contrainte est appliquée sur la première surface du substrat et non au travers de celui-ci comme c'est le cas dans les disques optiques traditionnels. De plus cette contrainte ne sera appliquée que sur les parties du substrat figurant entre les zones prégravées, ces parties étant souvent appelées « lands » dans l'état de l'art. Elle concerne également un procédé de fabrication de ce substrat ainsi que le disque à mémoire enregistrable comprenant ce substrat ou obtenu par ce procédé .The invention relates to a pre-etched substrate for a memory disc recordable by a constraint of the magneto-optical or magnetic type or with phase transition. This stress is applied to the first surface of the substrate and not through it as is the case in traditional optical discs. In addition, this constraint will only be applied to the parts of the substrate appearing between the pre-etched areas, these parts being often called "lands" in the state of the art. It also relates to a process for manufacturing this substrate as well as to the recordable memory disc comprising this substrate or obtained by this process.
Actuellement les disques ou disquettes à mémoire enregistrable sont largement utilisés par exemple, dans le domaine de 1 ' informatique en tant que disques durs des ordinateurs .At present, recordable memory disks or floppy disks are widely used, for example, in the computer field as computer hard disks.
Ces disques ou disquettes, dans leurs versions les plus évoluées, fonctionnent en mode d'enregistrement de première surface et sont des disques magnétiques avec assistance de guidage optique également appelés disques magnétiques assistés optiques, des disques magnéto-optiques avec assistance de guidage optique ou des disques optiques à transition de phase. Ils sont généralement composés d'un support comportant un signal de péformatage et d'une structure mono- ou multi- couches constituant la mémoire enregistrable et déposée sur ce support, après la gravure du préformatage dans le support.These discs or floppy disks, in their most advanced versions, operate in first surface recording mode and are magnetic discs with optical guided assistance also called optical assisted magnetic discs, magneto-optical discs with optical guided assistance or phase transition optical discs. They are generally composed of a support comprising a peformatting signal and of a mono- or multilayer structure constituting the recordable memory and deposited on this support, after the etching of the preformatting in the support.
La structure mono- ou multi -couches de la mémoire enregistrable comprend une couche dans laquelle les informations à mémoriser sont enregistrées.The monolayer or multilayer structure of the recordable memory comprises a layer in which the information to be stored is recorded.
Dans ce type de mémoire, a contrario des disques optiques classiques, l'enregistrement dans la couche enregistrable se fait par application directe, sur la première surface, c'est- à-dire sans passer au travers du support, de la contrainte appropriée.In this type of memory, in contrast to conventional optical discs, the recording in the recordable layer is done by direct application, on the first surface, that is to say without passing through the support, of the appropriate stress.
Cette contrainte peut être soit un champ magnétique, soit une énergie thermique apportée par un faisceau lumineux, soit une combinaison d'un champ magnétique et d'une énergie thermique. Dans les disques de type magnéto-optique et magnétique, l'enregistrement des informations se fait dans la couche enregistrable par création de zones dans lesquelles le champ magnétique est orienté différemment (inversé) par rapport au champ magnétique des autres zones et, dans les disques optique à transition de phase, l'enregistrement est effectué par création de zones dans lesquelles le matériau constituant la couche enregistrable a subi une transformation de phase, c'est-à-dire est passé soit d'une structure amorphe à une structure cristalline, soit d'une structure cristalline à une structure amorphe.This constraint can be either a magnetic field, or a thermal energy provided by a light beam, or a combination of a magnetic field and a thermal energy. In magneto-optical and magnetic type discs, information is recorded in the recordable layer by creating zones in which the magnetic field is oriented differently (inverted) compared to the magnetic field of other zones and, in discs phase transition optics, the recording is carried out by creating zones in which the material constituting the recordable layer has undergone a phase transformation, that is to say has passed either from an amorphous structure to a crystalline structure, either from a crystal structure to an amorphous structure.
La lecture des informations est alors effectuée par détection soit des champs magnétiques différents soit des différences de réflectivité dues au changement de structure du matériau, respectivement.The information is then read by detecting either different magnetic fields or differences reflectivity due to the change in structure of the material, respectively.
Dans tous les cas, la couche enregistrable est constituée d'un matériau dur magnétique ou susceptible de transitions de phases.In all cases, the recordable layer is made of a hard magnetic material or capable of phase transitions.
Ce type de disques permet d'atteindre des capacités de stockage très importantes mais leurs performances sont encore limitées par l'altération du rapport signal/bruit du signal de lecture du préformat, également appelé rapport C/N, générée par le dépôt de la ou des couches constituant la mémoire enregistrable, sur le préformat gravé au début du cycle de fabrication du substrat.This type of disc makes it possible to achieve very large storage capacities but their performance is still limited by the alteration of the signal / noise ratio of the read signal of the preformate, also called C / N ratio, generated by the deposition of the or layers constituting the recordable memory, on the preformate etched at the start of the substrate manufacturing cycle.
L'invention vise à pallier ce problème en proposant un disque à mémoire enregistrable du type magnéto-optique, magnétique ou optique à transition de phase ayant un rapport signal/bruit du signal de lecture du préformat amélioré et qui est de fabrication plus simple et plus économique que les disques de ce type actuellement fabriqués.The invention aims to overcome this problem by proposing a recordable memory disc of the magneto-optical, magnetic or optical phase transition type having a signal / noise ratio of the read signal of the improved preformate and which is simpler and more simple to manufacture. economical than discs of this type currently manufactured.
A cet effet, l'invention propose un substrat prégravé pour un disque à mémoire enregistrable par une contrainte du type magnéto-optique ou magnétique ou optique à transition de phase qui comprend (a) un support ayant à sa surface une couche en un matériau réflecteur et permettant d'obtenir une surface à poli optique, (b) sur cette couche de matériau réflecteur une structure mono ou multi -couches comprenant au moins une couche enregistrable par application sur la première surface du substrat d'une contrainte du type magnétique, magnéto-optique ou optique à transition de phase, la couche en matériau réflecteur et la structure mono- ou multi -couches comportant une succession de sillons et/ou microcuvettes représentant un signal de préformatage et s ' étendant de la surface de la couche la plus à 1 • extérieur de la structure mono- ou multi -couches jusqu'à une profondeur prédéterminée de la couche en un matériau réflecteur inférieure à l'épaisseur de cette couche en un matériau réflecteur, et (c) optionnellement une couche de protection déposée sur et recouvrant entièrement la dernière couche de la structure mono- ou multi -couches, les parois latérales des sillons et/ou micro-cuvettes étant formées, dans chacune des couches de la couche en un matériau réflecteur et de la structure mono- ou multi -couches, uniquement du matériau constituant ces couches, abstraction faite de la couche de protection précitée.To this end, the invention provides a pre-etched substrate for a memory disc recordable by a constraint of the magneto-optical or magnetic or optical phase transition type which comprises (a) a support having on its surface a layer of a reflective material and making it possible to obtain an optically polished surface, (b) on this layer of reflective material a monolayer or multilayer structure comprising at least one layer which can be recorded by applying a magnetic, magneto type stress on the first surface of the substrate -optical or phase transition optics, the reflective material layer and the absorbent pads mono- or multi structure comprising a succession of grooves and / or pits representing a preformat signal and extending from the surface of the more than 1 • outermost layer of the structure or mono- multi-layers up to a predetermined depth of the layer of reflective material less than the thickness of this layer of reflective material, and (c) optionally a protective layer deposited on and completely covering the last layer of the mono structure - or multi-layers, the side walls of the grooves and / or micro-cuvettes being formed, in each of the layers of the layer of a reflective material and of the mono- or multi-layer structure, only of the material constituting these layers, abstraction made of the aforementioned protective layer.
Selon un premier mode de réalisation du substrat prégravé de l'invention, le support et la couche de matériau réflecteur et permettant d'obtenir une surface à poli optique sont composés de matériaux différents.According to a first embodiment of the pre-etched substrate of the invention, the support and the layer of reflective material and making it possible to obtain a surface with optical polish are composed of different materials.
Le support pourra par exemple être en verre ou en aluminium et la couche de matériau réflecteur et permettant d'obtenir une surface à poli optique pourra par exemple être en nickel, ou en laiton, ou en aluminium, ou en chrome ou en nitrure de titane.The support could for example be made of glass or aluminum and the layer of reflective material and making it possible to obtain an optically polished surface could for example be made of nickel, or brass, or aluminum, or chromium or titanium nitride. .
Selon un second mode de réalisation du substrat prégravé de l'invention, le support et la couche de matériau réflecteur sont constitués du même matériau. Dans ce cas, avantageusement le support et la couche de matériau réflecteur forment une seule pièce.According to a second embodiment of the pre-etched substrate of the invention, the support and the layer of reflective material are made of the same material. In this case, advantageously the support and the layer of reflective material form a single piece.
Un exemple d'un matériau utilisable dans ce second mode de réalisation est l'aluminium.An example of a material which can be used in this second embodiment is aluminum.
Dans tous les modes de réalisation de l'invention, des matériaux exemplaires constituant ladite au moins une couche enregistrable sont Ag-In-Sb-Te, Tb-Fe-Co, Tb-Fe-Cr, Tb-Fe-Co-Cr, Tb-Ge-Sb, Tb-Ge-In, Tb-Ge-Ag, Fe-Cr, Fe-Co ou leurs alliages et mélanges.In all the embodiments of the invention, exemplary materials constituting said at least one recordable layer are Ag-In-Sb-Te, Tb-Fe-Co, Tb-Fe-Cr, Tb-Fe-Co-Cr, Tb-Ge-Sb, Tb-Ge-In, Tb-Ge-Ag, Fe-Cr, Fe-Co or their alloys and mixtures.
L'invention concerne également un procédé de fabrication d'un substrat prégravé qui comprend :The invention also relates to a method for manufacturing a pre-etched substrate which comprises:
a) une étape réalisée en premier lieu, de dépôt d'une structure mono- ou multi -couches comprenant au moins une couche enregistrable par application sur la première surface du substrat d'une contrainte du type magnétique, magnéto- optique ou optique à transition de phase, sur la couche de surface en un matériau réflecteur et permettant d'obtenir un poli optique d'un support, (b) une étape réalisée en second lieu de gravure d'une succession de sillons et/ou microcuvettes représentant un signal de préformatage dans la structure mono- ou multi -couches et dans la couche de surface en un matériau réflecteur, la gravure s 'étendant de la couche la plus à l'extérieur de la structure mono- ou multi -couches jusqu'à une profondeur prédéterminée de la surface en matériau réflecteur inférieure à l'épaisseur de cette couche de surface de matériau réflecteur, et (c) une étape optionnelle, réalisée en dernier lieu, de dépôt d'une couche de protection (11) sur la surface de la dernière couche de la structure mono- ou multi -couches.a) a step carried out in the first place, of depositing a mono- or multi-layer structure comprising at least one layer which can be recorded by application to the first surface of the substrate of a stress of the magnetic, magneto-optical or optical transition type phase, on the surface layer of a reflective material and making it possible to obtain an optical polish of a support, (b) a step carried out in the second place of etching a succession of grooves and / or microcuvettes representing a signal of preformatting in the monolayer or multilayer structure and in the surface layer of a reflective material, the etching extending from the outermost layer of the monolayer or multilayer structure to a predetermined depth of the surface of reflective material less than the thickness of this surface layer of reflective material, and (c) an optional step, last performed, of depositing a layer protection (11) on the surface of the last layer of the monolayer or multilayer structure.
Selon un mode de mise en oeuvre préféré du procédé de l'invention, l'étape de gravure de la succession de microcuvettes et/ou sillons représentant un signal de préformatage comprend les étapes de :According to a preferred embodiment of the method of the invention, the step of etching the succession of microcuvettes and / or grooves representing a preformatting signal comprises the steps of:
- dépôt d'une couche de résine photosensible sur la couche la plus à l'extérieur de la structure mono- ou multi -couches ;depositing a layer of photosensitive resin on the outermost layer of the monolayer or multilayer structure;
- enregistrement du signal de préformatage sous forme d'image latente dans la couche de résine photosensible par défilement d'un faisceau lumineux ou insolation au travers d'un masque ;- Recording of the preformatting signal in the form of a latent image in the layer of photosensitive resin by passage of a light beam or exposure through a mask;
élimination des zones de résine ainsi transforméeselimination of the resin zones thus transformed
transfert par une gravure appropriée du signal de prêformatage dans les couches constituant la structure mono- ou multi -couches et la couche de surface en un matériau réflecteur du support jusqu'à une profondeur prédéterminée, de la couche de surface en matériau réflecteur, inférieure à l'épaisseur de cette couche de surface en un matériau réflecteur, et ;transfer by an appropriate etching of the preformatting signal into the layers constituting the monolayer or multilayer structure and the surface layer of a reflective material of the support to a predetermined depth, from the surface layer of reflective material, less than the thickness of this surface layer of a reflective material, and;
- élimination de la résine résiduelle.- elimination of the residual resin.
Dans un premier mode de mise en oeuvre du procédé de l'invention, le support est constitué d'un matériau différent de celui de la couche de surface en un matériau réflecteur. Ainsi, le support pourra être en verre ou en aluminium et la couche de surface en nickel, ou en laiton, ou en aluminium, ou en chrome, ou en ni rure de titane.In a first embodiment of the method of the invention, the support consists of a material different from that of the surface layer made of a reflective material. Thus, the support may be made of glass or aluminum and the surface layer of nickel, or of brass, or of aluminum, or of chromium, or of titanium ni ride.
Dans un second mode de mise en oeuvre du procédé de l'invention, le support de la couche de surface en matériau réflecteur sont constitués du même matériau.In a second embodiment of the method of the invention, the support of the surface layer of reflective material are made of the same material.
Avantageusement le support et la couche de surface forment une pièce unique.Advantageously, the support and the surface layer form a single piece.
Un exemple d'un matériau utilisable dans ces deux cas est l'aluminium.An example of a material which can be used in these two cases is aluminum.
L'invention englobe aussi le disque magnéto-optique, magnétique ou optique à transition de phase qui comprend le substrat prégravé selon l'invention ou fabriqué par le procédé de l'invention.The invention also encompasses the magneto-optical, magnetic or optical phase transition disk which comprises the substrate pre-etched according to the invention or manufactured by the method of the invention.
L'invention sera mieux comprise et d'autres caractéristiques, détails et avantages de celle-ci apparaîtront plus clairement au cours de la description détaillée qui suit et qui se réfère aux figures annexées dans lesquelles :The invention will be better understood and other characteristics, details and advantages thereof will appear more clearly during the detailed description which follows and which refers to the appended figures in which:
- la figure 1 est une vue en coupe agrandie d'un substrat prégravé selon l'art antérieur ;- Figure 1 is an enlarged sectional view of a pre-etched substrate according to the prior art;
- la figure 2 représente une vue en coupe agrandie d'un substrat prégravé et enregistré de l'art antérieur, c'est-à- dire d'un disque magnéto-optique, magnétique ou optique à transition de phase, de l'art antérieur ; - la figure 3 est une vue en coupe agrandie d'un substrat non gravé, non enregistré, selon l'invention ;- Figure 2 shows an enlarged sectional view of a pre-etched and recorded substrate of the prior art, that is to say a magneto-optical, magnetic or optical phase transition disc, of the art anterior; - Figure 3 is an enlarged sectional view of an unetched, unregistered substrate according to the invention;
- la figure 4 représente une vue en coupe agrandie d'un substrat prégravé selon l'invention ;- Figure 4 shows an enlarged sectional view of a pre-etched substrate according to the invention;
- la figure 5 représente une vue en coupe agrandie d'un substrat prégravé enregistré selon l'invention c'est-à-dire un disque à mémoire enregistrable par une contrainte du type magnétique, magnéto-optique ou optique à transition de phase selon l'invention ; et- Figure 5 shows an enlarged sectional view of a pre-etched substrate recorded according to the invention, that is to say a memory disc recordable by a constraint of the magnetic, magneto-optical or optical type with phase transition according to l invention; and
- la figure 6 représente une vue en coupe agrandie d'un substrat prégravé enregistré selon l'invention et comportant une couche de protection.- Figure 6 shows an enlarged sectional view of a pre-etched substrate recorded according to the invention and comprising a protective layer.
En se référant à la figure 1, on décrira tout d'abord le procédé de fabrication d'un substrat prégravé selon l'art antérieur ainsi que la structure du substrat prégravé selon l'art antérieur.Referring to Figure 1, we will first describe the method of manufacturing a pre-etched substrate according to the prior art as well as the structure of the pre-etched substrate according to the prior art.
Le procédé de l'art antérieur pour fabriquer un substrat prégravé, comme illustré en figure 1, consiste à graver, par tout moyen approprié, dans la couche de surface notée 2, en figure 1 d'un support noté 1 en figure 1, le signal de préformatage voulu ;The prior art method for manufacturing a pre-etched substrate, as illustrated in FIG. 1, consists in etching, by any suitable means, in the surface layer denoted 2, in FIG. 1, of a support denoted 1 in FIG. 1, the desired preformatting signal;
Ce signal de préformatage, permet d'assurer le tracking, c'est-à-dire le suivi, le centrage et le guidage du faisceau laser de lecture, et éventuellement peut contenir des informations d'adresse et d'horloge. Ainsi, comme représenté en figure 1, la couche de surface 2 du support 1 comporte une succession de sillons et/ou microcuvettes ou pits notés 7 en figure 1 représentant le signal de préformatage voulu et une succession de zones planes ou lands notés 6 en figure 1.This preformatting signal makes it possible to ensure tracking, that is to say the tracking, centering and guiding of the reading laser beam, and possibly may contain address and clock information. Thus, as shown in FIG. 1, the surface layer 2 of the support 1 comprises a succession of grooves and / or microcuvettes or pits denoted 7 in FIG. 1 representing the desired preformatting signal and a succession of flat areas or lands denoted 6 in FIG. 1.
La couche de surface 2 est constituée d'un matériau réflecteur et permettant d'obtenir une surface à poli optique.The surface layer 2 is made of a reflective material and making it possible to obtain a surface with optical polish.
Ce qui signifie que si le support est constitué d'un matériau lui-même réflecteur et qui peut être poli à l'état de surface approprié (poli optique), la couche 2 n'a plus de raison d'être et le préformatage est gravé dans le support lui-même.This means that if the support is made of a material which is itself reflective and which can be polished to the appropriate surface state (optical polish), layer 2 is no longer necessary and the preformatting is engraved in the holder itself.
Par ailleurs, si le support 1 est formé d'un matériau réflecteur mais qui n'a pas l'état de surface requis, la couche 2 aura pour fonction de permettre d'obtenir cet état de surface mais devra toujours également assurer la fonction de réflectivité voulue. De la même façon, si le support 1 a l'état de surface requis mais n'est pas réflecteur, la couche 2 pourra être déposée, après gravure, sur le support 1, auquel cas la couche 2 sera aussi fine que possible.Furthermore, if the support 1 is formed of a reflective material but which does not have the required surface state, the layer 2 will have the function of making it possible to obtain this surface state but will also always have to perform the function of desired reflectivity. Likewise, if the support 1 has the required surface condition but is not reflective, the layer 2 may be deposited, after etching, on the support 1, in which case the layer 2 will be as thin as possible.
Autrement dit, dans l'art antérieur, selon la réflectivité et l'état de surface atteignable pour le support 1, la couche de surface 2 sera présente ou absente et sera déposée avant ou après gravure.In other words, in the prior art, depending on the reflectivity and the attainable surface state for the support 1, the surface layer 2 will be present or absent and will be deposited before or after etching.
Dans tous les cas, dans le procédé de l'art antérieur, la première étape de fabrication consiste à graver le préformat dans le support 1 ou la couche de surface 2 de ce support 1, si cette dernière est présente.In all cases, in the process of the prior art, the first manufacturing step consists in etching the preformate in the support 1 or the surface layer 2 of this support 1, if the latter is present.
Ensuite la deuxième étape du procédé de l'art antérieur consiste à déposer la structure mono- ou multi -couches comprenant au moins une couche enregistrable notée 4 en figure 1.Then the second step of the method of the prior art consists in depositing the mono- or multi-layer structure comprising at least one recordable layer denoted 4 in FIG. 1.
Ainsi, comme illustré en figure 1, une première et optionnelle couche barrière 3 est déposée sur la couche surface 2 du support 1 comportant les successions de pits 7 et lands 6, puis on dépose la couche 4 qui est la couche enregistrable proprement dite sur cette couche barrière 3. Une seconde et optionnelle couche barrière 5 est ensuite déposée sur la surface libre de la couche 4.Thus, as illustrated in FIG. 1, a first and optional barrier layer 3 is deposited on the surface layer 2 of the support 1 comprising the successions of pits 7 and lands 6, then layer 4 is deposited which is the recordable layer proper on this barrier layer 3. A second and optional barrier layer 5 is then deposited on the free surface of layer 4.
Une caractéristique distinctive du substrat prégravé de l'art antérieur est que les parois externes notées 8 en figure 1 des sillons et/ou microcuvettes 7 sont constituées du matériau constituant la dernière couche déposée de la structure mono- ou multi -couches, ici le matériau constituant la couche 5, a contrario du substrat prégravé de l'invention, comme on le verra ci -après.A distinctive characteristic of the pre-etched substrate of the prior art is that the external walls noted 8 in FIG. 1 of the grooves and / or microcuvettes 7 are made of the material constituting the last deposited layer of the monolayer or multilayer structure, here the material constituting layer 5, in contrast to the pre-etched substrate of the invention, as will be seen below.
Comme illustré en figure 2, on enregistre ensuite les informations à mémoriser dans la couche enregistrable 4 par application de la contrainte appropriée au travers du support 1, et dans les zones notées 6' de la couche enregistrable 4 en figure 2 et correspondant aux lands 6 du support 1.As illustrated in FIG. 2, the information to be stored is then recorded in the recordable layer 4 by application of the appropriate stress through the support 1, and in the zones denoted 6 ′ of the recordable layer 4 in FIG. 2 and corresponding to the lands 6 support 1.
Cet enregistrement par application de la contrainte notée 9 dans les figures mène à la création de zones 10 d'orientation magnétique différente des autres zones de la couche enregistrable 4 ou à la création de zones 10 de structure «cristalline» différente des autres zones de la couche enregistrable 4.This recording by application of the constraint noted 9 in the figures leads to the creation of orientation zones 10 magnetic different from the other zones of the recordable layer 4 or to the creation of zones 10 of “crystalline” structure different from the other zones of the recordable layer 4.
Il faut noter ici que l'enregistrement des informations dans la couche enregistrable 4 ne se fait pas au travers du substrat, c'est-à-dire est un enregistrement en première surface.It should be noted here that the recording of the information in the recordable layer 4 is not done through the substrate, that is to say a recording on the first surface.
En raison des dépôts successifs de ces différentes couches, 3, 4, et 5 une déformation du signal de préformatage se produit, ce qui nuit au rapport signal/bruit.Due to the successive deposits of these different layers, 3, 4, and 5, a deformation of the preformatting signal occurs, which affects the signal / noise ratio.
En contraste à ce procédé de fabrication d'un substrat prégravé de l'art antérieur, le procédé de fabrication d'un substrat prégravé selon l'invention consiste, comme illustré aux figures 3 et 4, à déposer d'abord et dans une première étape les différentes couches 3, 4 et 5 définies ci -dessus, sur la couche de surface 2 en un matériau réflecteur et permettant d'obtenir un poli optique de surface, puis après ce dépôt seulement, à graver la succession de microcuvettes et/ou sillons 7 représentant le signal de préformatage voulu.In contrast to this method of manufacturing a pre-etched substrate of the prior art, the method of manufacturing a pre-etched substrate according to the invention consists, as illustrated in FIGS. 3 and 4, of depositing first and in a first step the various layers 3, 4 and 5 defined above, on the surface layer 2 of a reflective material and making it possible to obtain an optical surface polish, then after this deposition only, to etch the succession of microcuvettes and / or grooves 7 representing the desired preformatting signal.
Ainsi, apparait ici la différence par rapport au procédé de fabrication d'un substrat prégravé selon l'invention : les différentes couches constituant le substrat prégravé sont déposées, avant gravure, sur la couche de surface 2 du support 1.Thus, the difference appears here compared to the process for manufacturing a pre-etched substrate according to the invention: the different layers constituting the pre-etched substrate are deposited, before etching, on the surface layer 2 of the support 1.
Comme montré aux figures 4 et 5, apparaît également la différence structurelle entre le substrat prégravé de l'invention et celui de l'art antérieur : les parois notées 8 des sillons et/ou microcuvettes 7, ces parois 8 traversant les couches 2, 3, 4 et 5, sont constituées uniquement de chacun des matériaux constituant les couches 2, 3, 4 et 5, dans ces couches 2, 3, 4 et 5, respectivement.As shown in Figures 4 and 5, there is also the structural difference between the pre-etched substrate of the invention and that of the prior art: the walls denoted 8 of the grooves and / or microcuvettes 7, these walls 8 passing through the layers 2, 3, 4 and 5, consist solely of each of the materials constituting the layers 2, 3 , 4 and 5, in these layers 2, 3, 4 and 5, respectively.
Par ailleurs, comme dans le cas du substrat prégravé et du procédé de l'art antérieur, la couche de surface 2 n'est présente que si la réflectivité et/ou l'état de surface du support 1 ne sont pas satisfaisants. La couche de surface 2 a donc ici également la fonction d'amener la réflectivité et l'état de surface voulu au support 1.Furthermore, as in the case of the pre-etched substrate and of the method of the prior art, the surface layer 2 is only present if the reflectivity and / or the surface condition of the support 1 are not satisfactory. The surface layer 2 therefore here also has the function of bringing the desired reflectivity and surface condition to the support 1.
En revenant au procédé de fabrication de l'invention, et comme montré en figure 4 le signal de préformatage est gravé dans les couches 3, 4 et 5 et dans la couche 2 de surface du support 1, par formation d'une succession de pits 7 représentant ce signal de préformatage et de lands 6. Comme montré en figure 4, la profondeur des pits 7 est inférieure à l'épaisseur des couches 2, 3, 4 et 5. Cela signifie que les pits 7 et lands 6 sont formés uniquement et en une seule opération dans les couches 2 , 3 , 4 et 5.Returning to the manufacturing process of the invention, and as shown in FIG. 4, the preformatting signal is etched in the layers 3, 4 and 5 and in the surface layer 2 of the support 1, by formation of a succession of pits 7 representing this preformatting and lands signal 6. As shown in FIG. 4, the depth of the pits 7 is less than the thickness of the layers 2, 3, 4 and 5. This means that the pits 7 and lands 6 are formed only and in a single operation in layers 2, 3, 4 and 5.
Ainsi, la gravure du préformat n'est pas déformée par le dépôt postérieur des couches constituant la structure mono- ou multi -couches, comme dans l'art antérieur.Thus, the etching of the preformate is not deformed by the subsequent deposition of the layers constituting the mono- or multi-layer structure, as in the prior art.
Cette gravure directe dans ces différentes couches procure un avantage substantiel : le rapport signal/bruit de lecture du préformat en est amélioré de façon substantielle. Un avantage supplémentaire de ce procédé de fabrication est sa simplification par rapport au procédé de l'art antérieur : avec ce procédé les différentes couches successives 2, 3, 4 et 5 sont déposées avec une meilleure homogénéité car déposées chacune sur des surfaces planes.This direct etching in these different layers provides a substantial advantage: the signal-to-noise reading ratio of the preformate is substantially improved. An additional advantage of this manufacturing process is its simplification compared to the process of the prior art: with this process the different successive layers 2, 3, 4 and 5 are deposited with better homogeneity because they are each deposited on flat surfaces.
Dans tous les cas , encore un autre avantage du procédé de fabrication du substrat prégravé de l'invention et du substrat prégravé lui-même, est qu'ils sont plus économiques à mettre en oeuvre et à fabriquer, respectivement. En effet, dans le cas où la couche de surface 2 est une couche distincte du support 1, et si un mauvais enregistrement du signal de préformatage est effectué, seules les couches 3, 4, 5 et éventuellement 2 sont à éliminer, ce qui signifie que l'on peut redéposer simplement sur le support 1 une nouvelle succession de couches telles que définies ci -dessus et procéder à une nouvelle gravure et/ou un nouvel enregistrement. Ce procédé est donc plus économique en cas d'incident, car la fabrication du support 1 représente l'élément le plus coûteux lors de la fabrication d'un substrat prégravé.In any case, yet another advantage of the method for manufacturing the pre-etched substrate of the invention and the pre-etched substrate itself, is that they are more economical to implement and to manufacture, respectively. Indeed, in the case where the surface layer 2 is a layer distinct from the support 1, and if a bad recording of the preformatting signal is carried out, only the layers 3, 4, 5 and possibly 2 are to be eliminated, which means that one can simply redeposit on the support 1 a new succession of layers as defined above and proceed to a new etching and / or a new recording. This process is therefore more economical in the event of an incident, since the production of the support 1 represents the most expensive element during the production of a pre-etched substrate.
L'enregistrement des informations à mémoriser se fait ensuite dans la couche enregistrable comme illustré en figure 5 c'est-à-dire sur la première surface du substrat et comme dans l'art antérieur.The information to be stored is then recorded in the recordable layer as illustrated in FIG. 5, that is to say on the first surface of the substrate and as in the prior art.
On obtient alors le disque à mémoire enregistrable, du type magnétique, magnéto-optique ou optique à transition de phase, illustré en figure 5 et constitué (a) d'un support 1 ayant une couche de surface (2) en un matériau réflecteur et permettant d'obtenir l'état de surface approprié et (b) de la succession de couches 3, 4, 5, les couches 3 et 5 étant optionnelles, dans lesquelles les pits 7 ont été gravés en une seule et même opération.This gives the recordable memory disc, of the magnetic, magneto-optical or optical phase transition type, illustrated in FIG. 5 and consisting of (a) a support 1 having a surface layer (2) made of a reflective material and to obtain the appropriate surface finish and (b) the succession of layers 3, 4, 5, layers 3 and 5 being optional, in which the pits 7 have been etched in a single operation.
Comme dans le procédé de l'art antérieur, avec le substrat prégravé de l'invention, l'enregistrement des informations à mémoriser dans la couche enregistrable 4 est effectué dans les lands 6 de la couche enregistrable 4.As in the method of the prior art, with the pre-etched substrate of the invention, the information to be stored in the recordable layer 4 is recorded in the lands 6 of the recordable layer 4.
La couche enregistrable 4 pourra être constituée de tout matériau approprié. Des exemples des matériaux appropriés sont les composés Ag-ln-Sb-Te, Tb-Fe-Co, Tb-Fe-Cr, Tb-Fe-Co- Cr, Tb-Ge-Sb, Tb-Ge-In, Tb-Ge-Ag, Fe-Cr, Fe-Co ou leurs alliages et mélanges.The recordable layer 4 may be made of any suitable material. Examples of suitable materials are Ag-ln-Sb-Te, Tb-Fe-Co, Tb-Fe-Cr, Tb-Fe-Co-Cr, Tb-Ge-Sb, Tb-Ge-In, Tb- Ge-Ag, Fe-Cr, Fe-Co or their alloys and mixtures.
Dans un premier mode de réalisation le support 1 sera constitué d'un matériau différent de la couche de surface 2.In a first embodiment, the support 1 will be made of a material different from the surface layer 2.
Il pourra par exemple être en verre ou en aluminium et la couche de surface 2 pourra, par exemple être en nickel, ou en laiton, ou en aluminium, ou en chrome, ou en nitrure de titane.It may for example be made of glass or aluminum and the surface layer 2 may, for example be made of nickel, or of brass, or of aluminum, or of chromium, or of titanium nitride.
Dans un second mode de réalisation, le support 1 sera constitué du même matériau que la couche de surface 2 mais la couche de surface 2 aura été déposée sur le support 1, par exemple par revêtement chimique ou par pulvérisation, pour donner au support 1 l'état de surface voulu.In a second embodiment, the support 1 will be made of the same material as the surface layer 2 but the surface layer 2 will have been deposited on the support 1, for example by chemical coating or by spraying, to give the support 1 l 'desired surface finish.
Egalement, lorsque le support 1 est constitué du même matériau que la couche de surface 2 et que ce matériau est réflecteur et permet d'obtenir l'état de surface voulu, le support 1 et la couche de surface 2 forment une pièce unique. Dans tous les cas, la profondeur des sillons et/ou microcuvettes dans la couche de surface 2 (indépendante ou faisant partie intégrante du support 1) sera inférieure à l'épaisseur de cette couche de surface 2.Also, when the support 1 is made of the same material as the surface layer 2 and this material is reflective and makes it possible to obtain the desired surface state, the support 1 and the surface layer 2 form a single piece. In all cases, the depth of the grooves and / or microcuvettes in the surface layer 2 (independent or forming an integral part of the support 1) will be less than the thickness of this surface layer 2.
Dans le procédé de l'invention et avec le substrat de l'invention, la gravure proprement dite du préformat peut être réalisée par tout moyen approprié mais en particulier par le procédé suivant :In the process of the invention and with the substrate of the invention, the actual etching of the preformate can be carried out by any suitable means but in particular by the following process:
Sur le substrat non gravé tel que décrit ci -dessus et représenté en figure 3, on dépose sur la dernière couche 5 la plus éloignée dudit support 1, une couche de résine photosensible.On the non-etched substrate as described above and shown in FIG. 3, a layer of photosensitive resin is deposited on the last layer 5 furthest from said support 1.
Ensuite, le signal de préformatage est enregistré, sous forme d'image latente, dans cette couche de résine photosensible soit par défilement d'un faisceau lumineux modulé en fonction du signal de préformatage, soit, et de préférence, par insolation de la résine photosensible au travers d'un masque. En particulier, ce masque peut être un masque holographique.Then, the preformatting signal is recorded, in the form of a latent image, in this layer of photosensitive resin either by the passing of a light beam modulated as a function of the preformatting signal, or, and preferably, by exposure to the photosensitive resin through a mask. In particular, this mask can be a holographic mask.
Puis, les zones de résine photosensible insolées sont éliminées par tout moyen approprié ce qui mène à la création d'une série de sillons et/ou microcuvettes dans la couche de résine photosensible.Then, the zones of exposed photosensitive resin are eliminated by any appropriate means, which leads to the creation of a series of grooves and / or microcuvettes in the layer of photosensitive resin.
Ensuite, ces sillons et/ou microcuvettes sont transférés, par exemple par gravure chimique, dans les couches sous-jacentes, jusque dans la couche de surface 2 réflectrice, si présente, ou le support 1, si la couche de surface 2 fait partie intégrante du support 1 mais à une profondeur inférieure à l'épaisseur de la couche de surface 2 ou du support 1.Then, these grooves and / or microcuvettes are transferred, for example by chemical etching, in the underlying layers, into the reflective surface layer 2, if present, or the support 1, if the surface layer 2 is part integral with the support 1 but at a depth less than the thickness of the surface layer 2 or of the support 1.
En final, la résine photosensible résiduelle est éliminée par tout moyen approprié.In the end, the residual photosensitive resin is eliminated by any appropriate means.
On notera également que le substrat prégravé de l'invention ainsi que son procédé de fabrication ne sont pas applicables pour la fabrication de disques optiques traditionnels en raison, entre autres, de la position de la couche réflectrice 6 qui rend la gravure du préformat invisible à travers le support 1 lorsque celui-ci est transparent.It will also be noted that the pre-etched substrate of the invention and its manufacturing method are not applicable for the manufacture of traditional optical discs due, inter alia, to the position of the reflective layer 6 which makes the etching of the preformat invisible to through the support 1 when the latter is transparent.
Bien entendu, l'invention n'est nullement limitée aux modes de réalisation décrits et illustrés qui n'ont été donnés qu'à titre d'exemples.Of course, the invention is in no way limited to the embodiments described and illustrated which have been given only by way of examples.
Ainsi, alors que dans la description qui précède, le substrat de l'invention a été décrit comme comportant des couches barrière 3 et 5, il peut ne comporter qu'une couche enregistrable 4 ou encore comporter d'autres couches, selon les besoins. Un exemple d'une telle couche optionnelle supplémentaire est une couche dite de protection du substrat, comme représenté en figure 6 où cette couche de protection est notée 11, et qui a pour fonction de protéger le substrat contre toute agression extérieure du type exposition à l'atmosphère, rayure, etc. Ainsi la durée de vie du substrat est prolongée. Cette couche 11 sera en tout matériau neutre vis-à-vis de la couche enregistrable 4 et du laser de tracking. Cette couche supplémentaire 11 sera déposée avant l'enregistrement proprement dit des informations à mémoriser dans la couche enregistrable 4, et cette étape fait partie du procédé de fabrication du substrat de l'invention. L'épaisseur de cette couche 11 pourra indifféremment être telle que la couche 11 épousera la forme de microcuvettes et/ou sillons 7, ou telle que la couche 11 remplira complètement ces microcuvettes et/ou sillons 7 c'est-à-dire encapsulera le substrat.Thus, while in the foregoing description, the substrate of the invention has been described as comprising barrier layers 3 and 5, it may comprise only a recordable layer 4 or also comprise other layers, as required. An example of such an optional additional layer is a so-called substrate protection layer, as shown in FIG. 6 where this protection layer is denoted 11, and which has the function of protecting the substrate against any external aggression of the type exposed to the atmosphere, scratch, etc. Thus the life of the substrate is extended. This layer 11 will be made of any material that is neutral with respect to the recordable layer 4 and the tracking laser. This additional layer 11 will be deposited before the actual recording of the information to be stored in the recordable layer 4, and this step is part of the process for manufacturing the substrate of the invention. The thickness of this layer 11 can equally be such that the layer 11 will take the form of microcuvettes and / or grooves 7, or such that the layer 11 will completely fill these microcuvettes and / or grooves 7, that is to say will encapsulate the substrate.
De même, le support 1 pourra être constitué de tout matériau approprié à condition qu'il permette d'obtenir l'état de surface nécessaire.Similarly, the support 1 may be made of any suitable material provided that it allows to obtain the necessary surface finish.
Egalement, la couche 4 enregistrable pourra être composée d'autres matériaux que ceux cités précédemment et qui permettent d'obtenir une mémoire enregistrable comme définie dans l'invention.Also, the recordable layer 4 may be composed of other materials than those mentioned above and which make it possible to obtain a recordable memory as defined in the invention.
C'est dire que l'invention comprend tous les équivalents techniques des moyens décrits ainsi que leurs combinaisons si celles-ci sont effectuées selon son esprit. This means that the invention includes all the technical equivalents of the means described as well as their combinations if these are carried out according to the spirit.

Claims

REVENDICATIONS
1. Substrat prégravé pour disques à mémoire enregistrable par une contrainte du type magnéto-optique ou magnétique ou optique à transition de phase,1. Pre-etched substrate for memory discs recordable by a magneto-optical or magnetic or optical phase transition type constraint,
caractérisé en ce qu'il comprend :characterized in that it comprises:
(a) un support (1) ayant une couche de surface (2) en un matériau réflecteur et permettant d'obtenir une surface à poli optique,(a) a support (1) having a surface layer (2) made of a reflective material and making it possible to obtain a surface with optical polish,
(b) une structure mono- ou multi -couches comprenant au moins une couche enregistrable (4) par application sur la première surface du substrat d'une contrainte (9) du type magnétique, magnéto-optique ou optique à transition de phase, la couche de surface (2) et la structure mono- ou multi -couches comportant une succession de sillons et/ou microcuvettes (7) représentant un signal de préformatage et s 'étendant de la surface de la couche la plus à l'extérieur de la structure mono- ou multi -couches jusqu'à une profondeur prédéterminée, de la couche de surface (2), inférieure à l'épaisseur de cette couche de surface (2) , et(b) a mono- or multi-layer structure comprising at least one recordable layer (4) by application on the first surface of the substrate of a stress (9) of the magnetic, magneto-optical or optical phase transition type, the surface layer (2) and the monolayer or multilayer structure comprising a succession of grooves and / or microcuvettes (7) representing a preformatting signal and extending from the surface of the outermost layer of the mono- or multi-layer structure up to a predetermined depth, of the surface layer (2), less than the thickness of this surface layer (2), and
(c) optionnellement, une couche (11) de protection déposée sur la surface de la couche la plus à l'extérieur de la structure mono- ou multi -couches gravée,(c) optionally, a protective layer (11) deposited on the surface of the outermost layer of the engraved monolayer or multilayer structure,
et en ce que : les parois latérales des sillons et/ou microcuvettes (7) sont formées, dans chacune des couches constituées par la couche de surface (2) et la structure mono- multi -couches, uniquement du matériau constituant ces couches, abstraction faite de la couche de protection (11) .and in that : the side walls of the grooves and / or microcuvettes (7) are formed, in each of the layers constituted by the surface layer (2) and the monolayer structure, only of the material constituting these layers, apart from the layer of protection (11).
2. Substrat prégravé selon la revendication 1, caractérisé en ce que le support (1) et la couche de surface (2) sont composés de matériaux différents.2. Pre-etched substrate according to claim 1, characterized in that the support (1) and the surface layer (2) are composed of different materials.
3. Substrat prégravé selon la revendication 2, caractérisé en ce que le support (1) est en verre ou en aluminium et la couche de surface (2) est en nickel, ou en laiton, ou en aluminium, ou en chrome, ou en nitrure de titane.3. Pre-etched substrate according to claim 2, characterized in that the support (1) is made of glass or aluminum and the surface layer (2) is made of nickel, or brass, or aluminum, or chrome, or titanium nitride.
4. Substrat prégravé selon la revendication 1, caractérisé en ce que le support (1) et la couche de surface (2) sont constitués du même matériau.4. Pre-etched substrate according to claim 1, characterized in that the support (1) and the surface layer (2) are made of the same material.
5. Substrat prégravé selon la revendication 4, caractérisé en ce que le support (1) et la couche de surface (2) forment une seule pièce.5. Pre-etched substrate according to claim 4, characterized in that the support (1) and the surface layer (2) form a single piece.
6. Substrat prégravé selon la revendication 4 ou 5, caractérisé en ce que ledit matériau est de l'aluminium.6. A pre-etched substrate according to claim 4 or 5, characterized in that said material is aluminum.
7. Substrat prégravé selon l'une quelconque des revendications précédentes, caractérisé en ce que le matériau constituant ladite au moins une couche enregistrable (4) sont choisis dans le groupe constitué par Ag-In-Sb-Te, Tb-Fe-Co, Tb-Fe-Cr, Tb-Fe-Co-Cr, Tb-Ge-Sb, Tb-Ge-In, Tb-Ge-Ag, Fe-Cr, Fe-Co et leurs alliages et mélanges. 7. Pre-etched substrate according to any one of the preceding claims, characterized in that the material constituting said at least one recordable layer (4) are chosen from the group consisting of Ag-In-Sb-Te, Tb-Fe-Co, Tb-Fe-Cr, Tb-Fe-Co-Cr, Tb-Ge-Sb, Tb-Ge-In, Tb-Ge-Ag, Fe-Cr, Fe-Co and their alloys and mixtures.
8. Procédé de fabrication d'un substrat prégravé pour disque magnétique, magnéto-optique ou optique à transition de phase caractérisé en ce qu'il comprend :8. Method for manufacturing a pre-etched substrate for a magnetic, magneto-optical or optical disc with phase transition, characterized in that it comprises:
(a) une étape, réalisée en premier lieu, de dépôt d'une structure mono- ou multi -couches comprenant au moins une couche enregistrable (4) par application sur la première surface du substrat d'une contrainte du type magnétique, magnéto-optique ou optique à transition de phase, sur une couche de surface (2) , en un matériau réflecteur et permettant d'obtenir une surface à poli optique, d'un support (1),(a) a step, first carried out, of depositing a monolayer or multilayer structure comprising at least one recordable layer (4) by applying to the first surface of the substrate a stress of the magnetic, magneto- type optical or optical phase transition, on a surface layer (2), in a reflective material and making it possible to obtain a surface with optical polish, of a support (1),
(b) une étape réalisée en second lieu de gravure d'une succession de sillons et/ou microcuvettes (7) représentant un signal de préformatage, dans la structure mono- multi -couches et la couche de surface (2) ,(b) a step carried out in the second place of etching a succession of grooves and / or microcuvettes (7) representing a preformatting signal, in the mono-multilayer structure and the surface layer (2),
la gravure s 'étendant de la couche la plus à l'extérieur de la strucuture mono- ou multi -couches jusqu'à une profondeur prédéterminée de la couche de surface (2) inférieure à l'épaisseur de cette couche de surface (2), etthe etching extending from the outermost layer of the monolayer or multilayer structure to a predetermined depth of the surface layer (2) less than the thickness of this surface layer (2) , and
(c) une étape optionnelle réalisée en dernier lieu de dépôt d'une couche de protection (11) sur la surface de la dernière couche de la structure mono- ou multi -couches.(c) an optional step carried out as the last step of depositing a protective layer (11) on the surface of the last layer of the monolayer or multilayer structure.
9. Procédé selon la revendication 8, caractérisé en ce que l'étape (b) de gravure de la succession de sillons et/ou microcuvettes (7) comprend les étapes de : - dépôt d'une couche de résine photosensible sur la couche la plus à l'extérieur de la structure mono- ou multi-couches ;9. Method according to claim 8, characterized in that the step (b) of etching the succession of grooves and / or microcuvettes (7) comprises the steps of: depositing a layer of photosensitive resin on the outermost layer of the mono- or multi-layer structure;
- enregistrement du signal de préformatage sous la forme d'image latente dans cette couche de résine photosensible par défilement d'un faisceau lumineux ou insolation au travers d'un masque ;- Recording of the preformatting signal in the form of a latent image in this layer of photosensitive resin by passage of a light beam or exposure through a mask;
- élimination des zones de résine ainsi transformées- elimination of the resin zones thus transformed
transfert par une gravure appropriée du signal de préformatage dans les couches de la structure mono- ou multi- couches et de la couche de surface (2) jusqu'à une profondeur prédéterminée de la couche de surface (2) inférieure à l'épaisseur de cette couche de surface (2) ; et - élimination de la résine résiduelle.transfer by appropriate etching of the preformatting signal in the layers of the mono- or multilayer structure and of the surface layer (2) to a predetermined depth of the surface layer (2) less than the thickness of this surface layer (2); and - elimination of the residual resin.
10. Procédé selon la revendication 8 ou 9, caractérisé en ce que le support (1) est constitué d'un matériau différent de celui de la couche de surface (2) .10. Method according to claim 8 or 9, characterized in that the support (1) consists of a material different from that of the surface layer (2).
11. Procédé selon la revendication 8 ou 9, caractérisé en ce que le support (1) et la couche de surface (2) sont constitués du même matériau.11. Method according to claim 8 or 9, characterized in that the support (1) and the surface layer (2) are made of the same material.
12. Procédé selon la revendications 11, caractérisé en ce que le support (1) et la couche de surface (2) forment une pièce unique.12. Method according to claim 11, characterized in that the support (1) and the surface layer (2) form a single piece.
13. Disque magnéto-optique, magnétique ou optique à transition de phase, comprenant le substrat prégravé selon l'une quelconque des revendications 1 à 7 ou obtenu par le procédé selon l'une quelconque des revendications 8 à 12. 13. Magneto-optical, magnetic or optical phase transition disk, comprising the substrate pre-etched according to any of claims 1 to 7 or obtained by the process according to any of claims 8 to 12.
EP98941545A 1998-08-05 1998-08-05 Pre-engraved substrate for magnetic, magneto-optical or phase transition optical disc, functioning by first surface recording in the lands, manufacturing method and resulting disc Withdrawn EP1103047A1 (en)

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JP3924301B2 (en) * 2005-02-01 2007-06-06 Ｔｄｋ株式会社 Magnetic recording medium and magnetic recording / reproducing apparatus
US20070147348A1 (en) * 2005-12-23 2007-06-28 Tingting Lu Methods, systems, and computer program products for providing location information for VoIP emergency calling
US7719793B2 (en) * 2005-12-28 2010-05-18 Hitachi Global Storage Technologies Netherlands B.V. Circumferentially patterned disk for longitudinal and perpendicular recording
AU2008219354B2 (en) 2007-09-19 2014-02-13 Viavi Solutions Inc. Anisotropic magnetic flakes

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JP2511147B2 (en) * 1989-07-06 1996-06-26 パイオニア株式会社 optical disk
FR2726116B1 (en) * 1994-10-21 1996-11-29 Atg Cygnet PREFORMED REWRITE OPTICAL DISC, AND MANUFACTURING METHOD
US5518788A (en) 1994-11-14 1996-05-21 Minnesota Mining And Manufacturing Company Antistatic hard coat incorporating a polymer comprising pendant fluorinated groups
JPH08203126A (en) * 1995-01-27 1996-08-09 Nec Corp Optical information recording medium, optical information reproducing method, and optical information recording, reproducing and erasing method
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