WO2000031730A1 - Stockage de donnees optiques - Google Patents

Stockage de donnees optiques Download PDF

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Publication number
WO2000031730A1
WO2000031730A1 PCT/GB1999/003916 GB9903916W WO0031730A1 WO 2000031730 A1 WO2000031730 A1 WO 2000031730A1 GB 9903916 W GB9903916 W GB 9903916W WO 0031730 A1 WO0031730 A1 WO 0031730A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
active
radiant energy
data storage
recording material
Prior art date
Application number
PCT/GB1999/003916
Other languages
English (en)
Inventor
Robert Longman
Robert Somekh
Ian Whittingham
Pedro Gago-Sandoval
Original Assignee
Plasmon Limited
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 Plasmon Limited filed Critical Plasmon Limited
Priority to AU12846/00A priority Critical patent/AU1284600A/en
Publication of WO2000031730A1 publication Critical patent/WO2000031730A1/fr

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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
    • G11B7/26—Apparatus or processes specially adapted for the manufacture of record carriers

Definitions

  • the present invention relates to optical data storage and, more particularly but not exclusively, is concerned with a method of initialisation of optical phase change media, for example CD-RW (re-writable Cds) and re-writable DVD (digital video disk) .
  • CD-RW re-writable Cds
  • DVD digital video disk
  • Optical phase change data storage media generally comprise a plastics substrate, such as a polycarbonate disc, which carries an "active" layer sandwiched between two dielectric layers.
  • the active material undergoes reversible phase changes between an amorphous state (which has relatively low reflectivity) and a crystalline state (which has relatively high reflectivity) .
  • the active layer comprises one or more alloys (e.g. an alloy of tellurium, antimony and germanium - Te-Sb-Ge; or an alloy of silver, indium, antimony and tellurium - Ag-In-Sb-Te) which is formed by a physical vapour phase deposition process such as sputter deposition or evaporation to form a data storage layer. This is in the amorphous phase when first formed.
  • a second dielectric layer is then deposited over the recording layer, and a reflector layer is then applied.
  • the reflector layer may be, but is not restricted to being, a metallic layer.
  • a further protective layer is generally formed over the reflective layer, thereby creating what is known in the art as an optical stack.
  • the active material needs to be in the crystalline state; a recorded "spot" is formed by highly localised heating of the material followed by rapid quenching so that the disordered atomic structure is retained.
  • the reflector layer serves as a heat sink which permits this quenching to occur.
  • the active material when first formed as part of the disk structure, is in the amorphous phase, it is necessary first to crystallise the material so that it is ready for use.
  • This process which is termed “initialisation”, is achieved by heating the amorphous active material to a moderate temperature - typically around 400°C for CD-RW materials - and then preventing rapid heat loss so that the material is able to anneal, thus generating the crystalline phase.
  • the temperature and annealing conditions chosen will be selected to match the nature of the active layer .
  • Heating of the data storage layer after the optical stack has been fully assembled can be inefficient due to heat absorption by the reflector layer.
  • a method of fabricating an optical data storage disk using an active recording material of the phase change type characterised in that the active recording material is initialised by means of a radiant energy source which is applied simultaneously to substantially all of the active layer.
  • a method of fabricating an optical data storage disk using an active recording material of the phase change type in which the active recording material is formed by a physical vapour phase deposition process which is followed by the formation of a reflective layer, characterised in that the active recording material is initialised by means of a radiant energy source after deposition of the recording material and before the formation of the reflective layer.
  • initialised refers to the step of transforming the active recording material at least partially from the amorphous to the crystalline state.
  • a characteristic feature of the preferred embodiments of the invention is that the initialisation of the active recording layer does not use a moving laser spot, as with conventional disk manufacture, but instead uses a single pulse - or a series of pulses - of radiant energy which is or are directed over substantially the whole area of the active recording layer simultaneously.
  • the preferred radiant energy source is a xenon flash lamp.
  • the fabrication process of this invention will be carried out using physical vapour phase deposition to generate a plurality of layers sequentially.
  • the preferred sequence of deposited layers will normally be: (a) a first dielectric layer; (b) the active recording material: (c) a second dielectric layer; and (d) the reflective layer.
  • the two dielectric layers are generally made from more than one material, the resultant dielectric layer being deposited as successive layers of different materials.
  • a final protective layer generally a plastics material, can be applied to the disk by a coating process.
  • the initialisation step may be carried out after deposition step (b) and before deposition step (d) in this preferred sequence; or after step (d) and before the protective coating is applied.
  • the presently preferred radiant energy source is a xenon flash light.
  • the xenon flash tube is set to produce pulses of energy of 20 to 100J and having a duration of 1 to 30 ⁇ s. Good results have been obtained using flashes whose duration has been in the range 10 to 20 ⁇ s.
  • a laser may be used instead of a xenon flash light, but this is not currently preferred.
  • the radiant energy is preferably delivered by way of an optical system so as uniformly to illuminate the active recording layer.
  • the radiant energy is advantageously directed through the transparent substrate (e.g. a polycarbonate substrate) to the phase change material constituting the recording layer.
  • the fabrication of the disk takes place in a multistage vacuum chamber, with radiant energy for the initialisation step being applied to the active recording layer in a subchamber of the multistage vacuum chamber.
  • FIGURE 1 shows a schematic cross-section (not to scale) through part of a preferred disk structure in accordance with this invention
  • FIGURE 2a is a transmission electron micrograph
  • FIGURE 2b is a selected area diffraction (SAD) pattern corresponding to the TEM of Fig. 2a;
  • FIGURE 3a is a transmission electron micrograph (TEM) through an optical data storage disk initialised by the method of this invention
  • FIGURE 3b is a selected area diffraction (SAD) pattern corresponding to the TEM of Fig. 3a;
  • FIGURE 4a is a transmission electron micrograph (TEM) through a second optical data storage disk initialised by the method of this invention.
  • FIGURE 4b is a selected area diffraction (SAD) pattern corresponding to the TEM of Fig. 4a.
  • an optical data storage disk comprises a substrate 1, formed of a polycarbonate resin, which serves to support the disk structure.
  • a first dielectric layer 2 Coated onto substrate 1 is a first dielectric layer 2; this is formed of ZnS/Si0 2 containing 20% (molecular %) Si0 2 and is relatively thick (e.g. 150nm).
  • the layer 2 is transparent over the wavelength range used to write and read the disk; it has a high melting point and very low thermal conductivity. It is also stable chemically and has good mechanical strength. The thermal properties and thickness of the layer make it effective at protecting the substrate 1 from damage during writing of data onto the disk.
  • the layer 2 is deposited onto substrate 1 by RF sputtering.
  • Layer 3 is the active recording material which in this example is an alloy of Te-Sb-Ge; and layer 4 is a second dielectric layer of the same composition as layer 2, but much thinner than layer 2.
  • Layer 5 is a metallic reflective layer made of aluminium/chromium containing 2 atomic % Cr. The incorporation of Cr in the Al is beneficial because it prevents grain growth and improves the corrosion resistance and thermal properties of the layer.
  • Layers 3, 4 and 5 are deposited by sputtering.
  • the second dielectric layer 4 is thin enough to permit rapid heat transfer from the active material 3 to the heat sink layer 5 during recording, thereby quenching the recorded spot, which thus becomes an island of amorphous alloy within the crystalline bulk layer.
  • the active material 3 is in the amorphous phase after it has been deposited onto dielectric layer 2.
  • the active material is initialised, in accordance with this invention, by subjecting it to radiant energy after it has been deposited but before the layer 5 is formed.
  • the application of radiant energy can be performed directly after deposition of layer 3; or it can be performed after the second dielectric layer 4 is formed over active layer 3, but before the reflective layer 5 is formed; or it can be performed after both layers 4 and 5 have been deposited over the active layer 3.
  • the radiant energy source may be a xenon flash light (not shown) and the operating conditions selected so as to achieve a temperature sufficient to crystallise the material phase change material . Where the initialisation step is carried out immediately after deposition of the layer 3, deposition of subsequent layers does not interfere with the crystalline phase of the active material 3.
  • Figs. 2-4 illustrate an important advantage of the present invention, namely the generation of a crystalline phase with a relatively fine grain structure. This is evident from a comparison of the relatively coarse grain structure achieved in the prior art (Fig. 2) with the much finer grain structure achieved with the present invention ( Figs . 3 and 4 ) .
  • Figure 2a is a bright field TEM of a conventionally initialised CD-RW disk (using a moving laser spot) in which the recording layer was a Ag-In- Sb-Te alloy.
  • Figure 2b is the corresponding selected area diffraction pattern. The grain structure apparent from Fig. 2a is relatively coarse and irregular; this is also evident from the SAD of Fig. 2b.
  • Figs. 3a and 3b show the results obtained with an identical disk to that of Fig. 2, but manufactured and initialised in accordance with the present invention - the initialisation step taking place prior to the deposition of the reflector layer.
  • the TEM and SAD were obtained after application of the reflective layer and a final protective lacquer coating.
  • Fig. 4 shows the results obtained with a second disk - in this case one having an active (recording) layer of Ge-Sb-Te alloy.
  • the manufacture and initialisation process were carried out as for the samples of Fig. 3, but the TEM in this case was taken before the reflective layer and final protective lacquer coating were added to the structure.
  • the initialisation step in the case of Figs. 3 and 4 was carried out using a Xenon Flash Lamp model QDX15 manufactured by Q-Arc Limited.
  • a single pulse of radiant energy of duration 16 ⁇ s was applied to the disk.
  • the flash was generated by applying a voltage of 3.3kV across a capacitor of 20 ⁇ F capacitance; this resulted in a total energy input of 108J.
  • the energy efficiency of the flash lamp is approximately 50%; consequently the radiant energy emitted was estimated as being 54J.
  • the spacing between the surface of the disk and the flash lamp was 2.0cm; the flash was directed through the transparent polycarbonate substrate layer towards the active layer.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Optical Record Carriers (AREA)
  • Thermal Transfer Or Thermal Recording In General (AREA)

Abstract

L'invention concerne un procédé de fabrication et d'initialisation de la couche d'enregistrement d'un disque de stockage de données optiques à changement de phase. L'étape d'initialisation peut s'effectuer pendant ou après la fabrication du disque, et est caractérisée en ce que la totalité de la couche active est exposée simultanément à un rayonnement, de préférence au moyen d'une lampe au xénon. On obtient ainsi une structure à grains plus fins dans la structure microcristalline de la couche d'enregistrement que dans l'état actuel de la technique.
PCT/GB1999/003916 1998-11-24 1999-11-24 Stockage de donnees optiques WO2000031730A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU12846/00A AU1284600A (en) 1998-11-24 1999-11-24 Optical data storage

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9825740.5 1998-11-24
GBGB9825740.5A GB9825740D0 (en) 1998-11-24 1998-11-24 Optical data storage

Publications (1)

Publication Number Publication Date
WO2000031730A1 true WO2000031730A1 (fr) 2000-06-02

Family

ID=10842960

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1999/003916 WO2000031730A1 (fr) 1998-11-24 1999-11-24 Stockage de donnees optiques

Country Status (3)

Country Link
AU (1) AU1284600A (fr)
GB (1) GB9825740D0 (fr)
WO (1) WO2000031730A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1118988A1 (fr) * 1999-07-12 2001-07-25 Matsushita Electric Industrial Co., Ltd. Support d'enregistrement d'information optique et procede d'initialisation correspondant
EP1170740A2 (fr) * 2000-06-23 2002-01-09 Memex Optical Meida Solutions AG Méthode et dispositif pour la fabrication d'un support d'enregistrement à changement de phase

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62250533A (ja) * 1986-04-23 1987-10-31 Toshiba Corp 光デイスクの初期結晶化方法
JPH0229953A (ja) * 1988-07-18 1990-01-31 Nec Corp 相変化型光ディスク用初期化方法および装置
US4916048A (en) * 1983-04-01 1990-04-10 Noboru Yamada Optical recording medium and method of optical recording and erasing using medium
JPH0335424A (ja) * 1989-07-03 1991-02-15 Hitachi Ltd 光ディスク記録膜の結晶化方法および装置
EP0790603A1 (fr) * 1996-02-16 1997-08-20 Matsushita Electric Industrial Co., Ltd Méthode et appareil pour initialiser un milieu d'enregistrement optique
US5684778A (en) * 1994-09-27 1997-11-04 Matsushita Electric Industrial Co., Ltd. Initialization process for a phase change recording medium with a zero level drop in flash light emission

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4916048A (en) * 1983-04-01 1990-04-10 Noboru Yamada Optical recording medium and method of optical recording and erasing using medium
JPS62250533A (ja) * 1986-04-23 1987-10-31 Toshiba Corp 光デイスクの初期結晶化方法
JPH0229953A (ja) * 1988-07-18 1990-01-31 Nec Corp 相変化型光ディスク用初期化方法および装置
JPH0335424A (ja) * 1989-07-03 1991-02-15 Hitachi Ltd 光ディスク記録膜の結晶化方法および装置
US5684778A (en) * 1994-09-27 1997-11-04 Matsushita Electric Industrial Co., Ltd. Initialization process for a phase change recording medium with a zero level drop in flash light emission
EP0790603A1 (fr) * 1996-02-16 1997-08-20 Matsushita Electric Industrial Co., Ltd Méthode et appareil pour initialiser un milieu d'enregistrement optique

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 012, no. 125 (P - 691) 19 April 1988 (1988-04-19) *
PATENT ABSTRACTS OF JAPAN vol. 014, no. 183 (P - 1035) 12 April 1990 (1990-04-12) *
PATENT ABSTRACTS OF JAPAN vol. 015, no. 172 (P - 1197) 30 April 1991 (1991-04-30) *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1118988A1 (fr) * 1999-07-12 2001-07-25 Matsushita Electric Industrial Co., Ltd. Support d'enregistrement d'information optique et procede d'initialisation correspondant
EP1118988A4 (fr) * 1999-07-12 2005-11-16 Matsushita Electric Ind Co Ltd Support d'enregistrement d'information optique et procede d'initialisation correspondant
EP1170740A2 (fr) * 2000-06-23 2002-01-09 Memex Optical Meida Solutions AG Méthode et dispositif pour la fabrication d'un support d'enregistrement à changement de phase
EP1170740A3 (fr) * 2000-06-23 2003-01-08 Pfeiffer Vacuum Systems (International) AG Méthode et dispositif pour la fabrication d'un support d'enregistrement à changement de phase
US6683275B2 (en) 2000-06-23 2004-01-27 Memex Optical Media Solutions Ag Method and apparatus for fabricating phase-change recording medium

Also Published As

Publication number Publication date
AU1284600A (en) 2000-06-13
GB9825740D0 (en) 1999-01-20

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