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Dokumentenidentifikation EP0905684 21.06.2007
EP-Veröffentlichungsnummer 0000905684
Titel Matrizenplatte für optische Platte und Verfahren zu ihrer Herstellung
Anmelder Samsung Electronics Co., Ltd., Suwon, Kyonggi, KR
Erfinder Ahn, Young-man, Suwon-city, Kyungki-do, KR;
Ro, Myung-do, Kunpo-city, Kyungki-do, KR;
Park, Chang-min Media Part,c/o Samsung El, Suwon-city, Kyungki-do 442-742, KR
Vertreter derzeit kein Vertreter bestellt
DE-Aktenzeichen 69837742
Vertragsstaaten DE, GB, NL
Sprache des Dokument EN
EP-Anmeldetag 11.06.1998
EP-Aktenzeichen 983046202
EP-Offenlegungsdatum 31.03.1999
EP date of grant 09.05.2007
Veröffentlichungstag im Patentblatt 21.06.2007
IPC-Hauptklasse G11B 7/26(2006.01)A, F, I, 20051017, B, H, EP

Beschreibung[en]

The present invention relates to a master disk used for manufacturing an optical disk on which information is recorded, and a method for manufacturing the master disk.

An optical disk such as a compact disk (CD) or a digital versatile disk (DVD) used as a medium for recording and/or reproducing video information, as shown in Figure 1, includes lands 2 each having information pits 2a, and grooves 3 positioned between neighboring lands 2 for defining the lands 2. Recently, much attention has been paid to increasing the capacity of recordable information by forming information pits 3a in the grooves 3 of an optical disk 1.

To manufacture the optical disk 1, a master disk having a recording plane of the same pattern as the optical disk 1 is generally necessary. In other words, as shown in Figure 2, a master disk 10 having lands 31, grooves 33 and information pits 32 and 34, which is of the same pattern as the optical disk 1, is necessary. To manufacture the master disk 10, first, a photoresist capable of being photochemically reacted with a laser beam having a predetermined wavelength is coated on a carefully polished glass substrate 20 to a predetermined thickness, to form a photoresist layer 30. While the substrate 20 is rotated, and simultaneously two laser beams are incident onto the substrate 20, so that the portions of the photoresist layer 30, where the grooves 33 and the information pits 32 and 34 are to be formed, are exposed to the laser beams. Then, the photochemical reaction occurs in the portions exposed to the laser beams. During the exposing process, one laser beam is deflected left and right to expose the portion in which the grooves 33 are to be formed, and the other laser beam exposes the portion where the information pits 32 and 34 are to be formed. Then, the exposed portions are etched and cleaned, thereby finally manufacturing the master disk 10 as shown in Figure 2.

Thereafter, a metal film (not shown) is deposited thinly on the recording plane of the master disk 10 and a metal such as nickel is electrically coated on the metal film to then separate the coated film from the master disk 10. The coated film is used as a stamper in the plastic molding of an optical disk. Such a stamper has surface irregularities exactly opposite to those of the recording plane of the master disk 10. Accordingly, the optical disk manufactured by using the stamper has the lands, grooves and information pits has the same pattern as the master disk.

However, if the master disk is manufactured in the above-described manner, grooves and information pits are both formed in the same photoresist layer. Thus, the boundary between the grooves and information pits becomes ambiguous, and the angles of the side walls of the groove and information pits with respect to the substrate become lower. Therefore, in the optical disk manufactured using the master disk, the boundary between the groove and information pit becomes ambiguous and the side walls of the grooves and information pits have a low angle. Therefore, it is difficult to reproduce the information recorded on the optical disk by a recording/reproducing apparatus, using light diffraction from the boundary between the groove and information pit. Accordingly, the reproduction characteristics of the optical disk are deteriorated. Such a problem becomes serious in a high-definition (HD)-DVD having information tracks at a smaller pitch than the conventional DVD.

A master disk is disclosed in EP-A-0 708 439.

It is an aim of at least preferred embodiments of the present invention to provide an optical-disk master disk with an improved photoresist layer, by which the boundary between grooves and information pits recessed from the grooves is distinctly defined.

It is another aim of the present invention to provide a method for manufacturing an optical-disk master disk, by which the boundary between grooves and information pits recessed from the grooves is distinctly defined.

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Preferred features of the invention will be apparent from the dependent claims, and the description which follows.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:

  • Figure 1 is a perspective view illustrating important parts of an optical disk;
  • Figure 2 is a vertical section view of a conventional master disk for manufacturing the optical disk shown in Figure 1;
  • Figure 3 is a vertical section view of a master disk for manufacturing the optical disk according to the present invention; and
  • Figures 4 through 6 illustrate a method for manufacturing the master disk shown in Figure 3.

Referring to Figure 3, a master disk 100 according to the preferred embodiment of the present invention includes a glass substrate 20, a first photoresist layer 110 formed on the substrate 20, and a second photoresist layer 120 formed on the first photoresist layer 110. The first photoresist layer 110 is formed of a first photoresist capable of being photochemically reacted with a laser beam having a predetermined wavelength, and the second photoresist layer 120 is formed of a second photoresist capable of being photochemically reacted with the same laser beam more sensitively than the first photoresist layer 110.

For example, in the case when the photoresist layers are to be exposed using a laser beam having a wavelength in the range of 350∼430 nm, for example, DNQ-4 (1-oxo-2-diazonaphthoquinone-4-arylsulfonate) capable of being photochemically reacted with the laser beam having a wavelength of 310∼390 nm, may be used as the first photoresist, and DNQ-5 (1-oxo-2-diazonaphthoquinone-5-arylsulfonate) capable of being photochemically reacted with the laser beam having a wavelength of 350∼430 nm, may be used as the second photoresist, thereby forming the first and second photoresist layers 110 and 120. Then, the second photoresist layer 120 is photochemically reacted with the laser beam more sensitively than the first photoresist layer 110. When, as described above, DNQ-4 and DNQ-5 are used as the first and second photoresists, the laser beam preferably has a wavelength in the range of 400∼430 nm, and more preferably 413 nm.

The lands 121 are formed in the second photoresist layer 120, and first information pits 122 recessed from the surface of the lands 121 are formed in the lands 121. Also, grooves 123 are formed in the second photoresist layer 120, each groove 123 being positioned between neighboring lands 121. Second information pits 111 recessed from the bottom surface of the grooves 123 are formed in the first photoresist layer 110.

In the master disk 100 having the aforementioned structure, photoresist layers 110 and 120 having different photochemical reactivities from each other are formed on the substrate 20. The grooves 123 and second information pits 111 are formed in different photoresist layers, respectively. Therefore, unlike in the conventional master disk of Figure 2, in the master disk according to the present invention, the boundary between the grooves 123 and the second information pits 111 is more distinctly defined, and the respective second information pits 111 have inner walls substantially perpendicular with respect to the substrate 20.

If the optical disk 1 (Figure 1) is manufactured by the above-described master disk 100, the boundary between the grooves 3 (Figure 1) and the second information pits 3a (Figure 1) is more distinctly defined also in the optical disk 1. Likewise, the respective second information pits 3a have inner walls substantially perpendicular to each bottom surface of the second information pits 3a. Therefore, when reproducing the information recorded on the optical disk, the second information pits 3a can be clearly detected by an optical pickup incorporated in the recording/reproducing apparatus, thereby improving reproduction characteristics.

In the course of manufacturing the master disk 100, an example of the procedure for forming the grooves 123 and the second information pits 111 will be described in detail with reference to Figures 4 through 6.

First, as shown in Figure 4, the first photoresist is coated on the carefully polished glass substrate 20 to form a first photoresist layer 110. Then, the second photoresist is coated on the first photoresist layer 110 to form a second photoresist layer 120. The substrate 20 is placed at a position where a first laser beam LB1 and a second laser beam LB2 having the same wavelength, e.g., 415 nm, can be incident onto the substrate 20 from the upper side of second photoresist layer 120.

In this embodiment, the first laser beam LB1 and the second laser beam LB2 are generated by the laser diode 50. In other words, the laser beam emitted from the laser diode 50 is split by a beam splitter 61 to then be separated into the first laser beam LB1 and the second laser beam LB2. Modulators 71 and 72 for selectively blocking the respective laser beams LB1 and LB2 are installed along the respective optical paths of the first and second laser beams LB1 and LB2. A deflector 73 for deflecting the second laser beam LB2 along the optical path of the second laser beam LB2 is installed. Reference numeral 62 denotes a beam splitter, and reference numerals 81 and 82 denote mirrors.

In such a state as shown in Figure 4, the substrate 20 is rotated, and simultaneously the first and second laser beams LB1 and LB2 are incident onto the substrate 20 to expose a desired portion thereof. In other words, the portions where the grooves 123, the first information pits 122 and the second information pits 111 recessed from the grooves 123 are to be formed, are exposed. Then, the photochemical reaction occurs in the exposed portions. While exposing the portions where the grooves 123 are to be formed, as shown in Figure 5, the second laser beam LB2 is repeatedly deflected by the deflector 73 across the width of the groove 123, that is, repeatedly deflected in both sides around the optical axis of the first laser beam LB1, along the direction of the radius of the substrate 20. In such a manner, the exposing time of the portion exposed by the second laser beam LB2 becomes shorter. Thus, the first photoresist layer 110 insensitive to the laser beam LB2 is not exposed but the second photoresist layer 120 sensitive thereto is exposed. By doing so, in the course of exposing the portion where the grooves 123 are to be formed, the first laser beam LB1 is made to be incident onto the substrate 20 through the modulator 71 in the portion where the second information pits 111 are to be formed. In such a manner, the first laser beam LB1 is incident onto the portion of the second photoresist layer 120 photochemically reacted with the second laser beam LB2. In this case, the first laser beam LB1 is incident without being deflected, unlike in the case when the exposure is performed with the second laser beam LB2 being deflected in both sides of the optical axis of the first laser beam LB1. Thus, the exposure time of the to-be-exposed portion becomes longer than that of the portion where the grooves 123 are to be formed. Therefore, the portion of the first photoresist layer 110, where the second information pits 111 are to be formed, as well as the second photoresist layer 120 are exposed by the first laser beam LB1. Thus, the boundary between the exposed portion of the first photoresist layer 110 and the exposed portion of the second photoresist layer 120 becomes distinctly defined. Also, the exposed portion of the second photoresist layer 120 has a substantially rectangular section.

Although not shown in Figure 5, the portion where the first information pits 122 are to be formed is exposed by the first laser beam LB1 or the second laser beam LB2 without being deflected. In this case, since the first information pits 122 are formed in the second photoresist layer 120 having a high sensitivity, the exposure time can be shortened. As described above, when the portions where the grooves 123 and the first information pits 122 are to be formed are exposed, portions where the lands 121 are to be formed between the neighboring portions where the grooves 123 are to be formed, and the portions where the first information pits 122 are to be formed, are contained in the portions where the lands 121 are to be formed.

After completing the exposure procedure, the exposed portions are etched and cleaned to complete the master disk 100 shown in Figure 3 or 6.

In the master disk 100, as described above, the boundary between the exposed portions where the grooves 123 and the second information pits 111 is more distinctly defined, and the exposed portions have a substantially rectangular section. Therefore, the grooves 123 and second information pits 111 are distinctly defined in the boundary therebetween, and the inner walls of the grooves 123 and second information pits 111 slope sharply with respect to the substrate 20 so that they are substantially perpendicular to each other.

Although it has been described that the first laser beam LB1 and the second laser beam LB2 are generated by the laser diode 50, it is also possible that the first laser beam LB1 and the second laser beam LB2 having the same wavelength are generated by two different laser diodes.

The present invention has been particularly shown and described with reference to a preferred embodiment thereof, but various other changes in form and details may be embodied without departing from the scope of the invention.

As described above, a first photoresist layer less sensitive to exposure to a laser beam of a predetermined wavelength and a second photoresist layer more sensitive to the laser beam than the first photoresist layer are sequentially disposed on a substrate. A master disk can be manufactured by selectively exposing and etching the photoresist layers, so that the boundary between the grooves and the second information pits recessed from the grooves becomes distinct, and the grooves and second information pits have inner walls substantially perpendicular to the substrate. Therefore, the reproduction characteristics of an optical disk obtained by the master disk are improved.


Anspruch[de]
Matrizenplatte für optische Platten, die aufweist: ein Substrat (20); und eine Fotoresist-Schicht (30), die Informations-Pits, die darin gebildet sind, besitzt; wobei die Fotoresist-Schicht aufweist: eine erste Fotoresist-Schicht (110), die auf dem Substrat (20) gebildet ist und dazu geeignet ist, fotochemisch mit einem Laserstrahl, der eine vorgegebene Wellenlänge besitzt, in Reaktion gebracht zu werden; eine zweite Fotoresist-Schicht (120), die auf der ersten Fotoresist-Schicht (110) gebildet ist und dazu geeignet ist, dass sie fotochemisch mit demselben Laserstrahl empfindlicher als die erste Fotoresist-Schicht (110) zur Reaktion gebracht werden kann;

wobei die zweite Fotoresist-Schicht (120) eine Vielzahl von ersten Informations-Pits (122), die darin gebildet sind, besitzt; und

wobei die erste Fotoresist-Schicht (110) eine Vielzahl von zweiten Informations-Pits (111) besitzt, die darin gebildet sind,

wobei Rillen (123) in der zweiten Fotoresist-Schicht (120) gebildet sind, dadurch gekennzeichnet, dass
die zweiten Informations-Pit (111) in der ersten Fotoresist-Schicht (110) in dem Bereich der Rillen (123) in der zweiten Fotoresist-Schicht (120) gebildet sind, und wobei die ersten Informations-Pits (122) in Stegen (121) der zweiten Fotoresist-Schicht (120) zwischen den Rillen (123) gebildet sind.
Verfahren zum Herstellen einer Matrizenplatte für optische Platten, das die Schritte aufweist: Bilden einer ersten Fotoresist-Schicht (110), die dazu geeignet ist, fotochemisch mit einem Laserstrahl, der eine vorgegebene Wellenlänge besitzt, zur Reaktion gebracht zu werden, auf einem Substrat (20); Bilden einer zweiten Fotoresist-Schicht (120), die dazu geeignet ist, fotochemisch mit demselben Laserstrahl, empfindlicher als die erste Fotoresist-Schicht (110), zur Reaktion gebracht zu werden, auf der ersten Fotoresist-Schicht (110); Bereitstellen eines ersten und eines zweiten Laserstrahls (LB1, LB2), die eine vorgegebene Wellenlänge haben; Bestrahlen eines vorgegebenen Bereichs (123) der zweiten Fotoresist-Schicht (120) mit dem zweiten Laserstrahl (LB2); und Bestrahlen eines vorgegebenen Bereichs (111) der ersten Fotoresist-Schicht (110), der sich unter dem bestrahlten Bereich (123) der zweiten Fotoresist-Schicht (120) befindet, mit dem ersten Laserstrahl (LB1); gekennzeichnet durch Bilden dadurch von Rillen in der zweiten Fotoresist-Schicht (12), von zweiten Informations-Pits (111) in der ersten Fotoresist-Schicht (110) in dem Bereich der Rillen (123) und Bilden von ersten Informations-Pits (122) in Stegen (121) der zweiten Fotoresist-Schicht (120) zwischen den Rillen (123). Verfahren nach Anspruch 2, wobei die vorgegebene Wellenlänge in dem Bereich von 400∼430 nm liegt. Verfahren nach Anspruch 3, wobei die vorgegebene Wellenlänge in dem Bereich von 410~415 nm liegt. Verfahren nach einem der Ansprüche 2 bis 4, wobei, während der vorgegebene Bereich (123) der zweiten Fotoresist-Schicht (120) mit dem zweiten Laserstrahl (LB2) bestrahlt wird, der zweite Laserstrahl (LB2) wiederholt in beiden Seiten um die optische Achse des ersten Laserstrahls (LB1) herum abgelenkt wird.
Anspruch[en]
An optical-disk master disk comprising: a substrate (20); and a photoresist layer (30) having information pits formed therein; wherein said photoresist layer comprises: a first photoresist layer (110) formed on the substrate (20) and capable of being photochemically reacted with a laser beam having a predetermined wavelength; a second photoresist layer (120) formed on the first photoresist layer (110) and capable of being photochemically reacted with the same laser beam more sensitively than the first photoresist layer (110); said second photoresist layer (120) having a plurality of first information pits (122) formed therein; and said first photoresist layer (110) having a plurality of second information pits (111) formed therein,

wherein grooves (123) are formed in the second photoresist layer (120), characterised in that
the second information pits (111) are formed in the first photoresist layer (110) in the region of said grooves (123) in said second photoresist layer (120), and said first information pits (122) are formed in lands (121) of the second photoresist layer (120) between said grooves (123).
A method for manufacturing an optical-disk master disk comprising the steps of: forming on a substrate (20) a first photoresist layer (110) capable of being photochemically reacted with a laser beam having a predetermined wavelength; forming on the first photoresist layer (110) a second photoresist layer (120) capable of being photochemically reacted with the same laser beam more sensitively than the first photoresist layer (110); providing first and second laser beams (LB1,LB2) having predetermined wavelength; exposing a predetermined portion (123) of the second photoresist layer (120) to the second laser beam (LB2); and exposing a predetermined portion (111) of the first photoresist layer (110), which is under the exposed portion (123) of the second photoresist layer (120), to the first laser beam (LB1); characterised by thereby forming grooves in the second photoresist layer (12), second information pits (111) in the first photoresist layer (110) in the region of said grooves (123) and forming first information pits (122) in lands (121) of the second photoresist layer (120) between said grooves (123). The method according to claim 2, wherein the predetermined wavelength is in the range of 400∼430nm, The method according to claim 3, wherein the predetermined wavelength is in the range of 410∼415 nm. The method according to any of claims 2 to 4, wherein while the predetermined portion (123) of the second photoresist layer (120) is exposed to the second laser beam (LB2), the second laser beam (LB2) is repeatedly deflected in both sides around the optical axis of the first laser beam (LB1).
Anspruch[fr]
Disque-matrice pour disque optique, comprenant : un substrat (20) ; et une couche de résine photosensible (30) ayant des puits d'informations formés en elle ;

dans lequel ladite couche de résine photosensible comprend : une première couche de résine photosensible (110) formée sur le substrat (20) et pouvant être amenée à réagir photochimiquement avec un faisceau laser ayant une longueur d'onde prédéterminée ; une deuxième couche de résine photosensible (120) formée sur la première couche de résine photosensible (110) et pouvant être amenée à réagir photochimiquement avec le même faisceau laser, avec une sensibilité plus élevée que la première couche de résine photosensible (110) ; ladite deuxième couche de résine photosensible (120) ayant une pluralité de premiers puits d'informations (122) formée en elle ; et ladite première couche de résine photosensible (110) ayant une pluralité de deuxièmes puits d'informations (111) formée en elle, dans lequel des gorges (123) sont formées dans la deuxième couche de résine photosensible (120), caractérisé en ce que : les deuxièmes puits d'informations (111) sont formés dans la première couche de résine photosensible (110) dans la région desdites gorges (123) dans ladite deuxième couche de résine photosensible (120), et lesdits premiers puits d'informations (122) sont formés dans des plats (121) de la deuxième couche de résine photosensible (120) entre lesdites gorges (123).
Procédé de fabrication d'un disque-matrice pour disque optique, comprenant les étapes consistant à : former sur un substrat (20) une première couche de résine photosensible (110) pouvant être amenée à réagir photochimiquement avec un faisceau laser ayant une longueur d'onde prédéterminée ; former sur la première couche de résine photosensible (110) une deuxième couche de résine photosensible (120) pouvant être amenée à réagir photochimiquement avec le même faisceau laser, avec une sensibilité plus élevée que la première couche de résine photosensible (110) ; fournir des premier et deuxième faisceaux laser (LB1, LB2) ayant une longueur d'onde prédéterminée ; exposer une portion prédéterminée (123) de la deuxième couche de résine photosensible (120) au deuxième faisceau laser (LB2) ; et exposer une portion prédéterminée (111) de la première couche de résine photosensible (110), qui est en dessous de la portion exposée (123) de la deuxième couche de résine photosensible (120), au premier faisceau laser (LB1) ; caractérisé par les étapes consistant à former des gorges dans la deuxième couche de résine photosensible (12), des deuxièmes puits d'informations (111) dans la première couche de résine photosensible (110) dans la région desdites gorges (123), et à former des premiers puits d'informations (122) dans des plats (121) de la deuxième couche de résine photosensible (120) entre lesdites gorges (123). Procédé selon la revendication 2, dans lequel la longueur d'onde prédéterminée est dans la plage de 400 nm à 430 nm. Procédé selon la revendication 3, dans lequel la longueur d'onde prédéterminée est dans la plage de 410 nm à 415 nm. Procédé selon l'une quelconque des revendications 2 à 4, dans lequel, pendant que la portion prédéterminée (123) de la deuxième couche de résine photosensible (120) est exposée au deuxième faisceau laser (LB2), le deuxième faisceau laser (LB2) est dévié de façon répétée des deux côtés autour de l'axe optique du premier faisceau laser (LB1).






IPC
A Täglicher Lebensbedarf
B Arbeitsverfahren; Transportieren
C Chemie; Hüttenwesen
D Textilien; Papier
E Bauwesen; Erdbohren; Bergbau
F Maschinenbau; Beleuchtung; Heizung; Waffen; Sprengen
G Physik
H Elektrotechnik

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