JPH07176082A - Stamper for duplicating optical disk and its production and optical disk - Google Patents

Abstract

PURPOSE:To improve the flow property of a resin at the time of molding and to improve packability and transferability by forming the extreme surface of a stamper of a dense film having small specific resistance and high wear resistance. CONSTITUTION:A photoresist film 2 is applied and formed on a glass substrate 1 and thereafter, fine rugged patterns are formed on this photoresist film by exposing with a gas laser and developing. A DLC(diamond-like carbon) film 3 is formed at 500Angstrom thickness by a plasma-CVD method on the optical disk original plate obtd. in such a manner and further, an Ni film 4 of 500Angstrom is formed thereon by a DC sputtering method, by which conducted films having a two-layered structure are formed. The optical master disk has the surface shape reversed with the fine rugged patterns in such a manner and, therefore, the wear of the stamper and the drooping of the fine shape are hardly generated and the life of the stamper is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk duplicating stamper and a method for manufacturing the same, and more particularly to an optical disk. More specifically, the present invention relates to an information recording medium and an optical disk duplicating stamper on which a fine pattern is formed on the recording medium, and a method for manufacturing the same. Regarding optical discs. For example, it is applied to an injection molding die.

[0002]

2. Description of the Related Art As a conventional method for manufacturing a stamper for duplicating an optical disc, a photoresist film is applied on a glass substrate, and a fine pattern having irregularities is formed on the photoresist film by laser exposure and development. A metal-conducting film such as
The method of manufacturing by electroforming is general. As a known document describing a conventional stamper for duplicating an optical disk, there is, for example, Japanese Patent Laid-Open No. 1-301880. This publication has C on the surface of the father stamper.
After applying a release film treatment such as rO ₂ or TiN, a replica is formed by 2P molding, and by using the replica as a master, many child stampers having the same quality as a father can be easily created. is there.

Further, in Japanese Patent Laid-Open No. 63-155445, in order to manufacture information recording masters having different groove depths, two or more types of patterns having different depths are formed on the surface of a base material serving as an information recording master. And a pattern layer on the base material are etched together to form two or more types of patterns having different depths on the base material. It is a thing. Also,
Japanese Patent Laid-Open No. 57-64308 discloses a nickel stamper having a TiN coating film formed on the surface thereof by an ion plating method. Further, JP-A-54-142
The one disclosed in Japanese Patent No. 137 has a SiN coating on the surface of the electroforming mold to improve the releasability and to improve the hardness, scratch resistance and chemical resistance.

FIG. 5 is a block diagram of a conventional stamper for duplicating an optical disk, in which 11 is a stamper and 12 is a hard film. After the stamper 11 is completed, the hard film 12 is formed (added later). By providing the hard film 12, the shape of the fine pattern is changed, and the film thickness distribution of the hard film 12 becomes the pattern shape variation as it is. Therefore, variations in signal characteristics increase, leading to lower yields and higher costs.

[0005]

In the conventional method of manufacturing a stamper for duplicating an optical disc, when a disc is obtained from the stamper by injection molding or the like, a pressure of several tons is applied to the stamper surface at the time of molding, which hinders a long life of the stamper. ing. Also, because the stamper surface is soft (Vickers hardness is 200 to 400 Hv), that is, it is rich in elasticity,
A partial difference occurs in the thermal deformation of the stamper at the time of molding, resulting in uneven transfer of the groove shape and deterioration of the circularity of the groove. The variations in the signal characteristics and the variations in the tracking characteristics cause the recording and reproducing characteristics of the obtained media to be disturbed.

Conventional methods such as forming a nitride film on the surface of the stamper have been used to extend the life of the stamper.
Since the coating is applied to the stamper after completion, the fine pattern of irregularities changes. In addition, variations in the film thickness of the coating result in variations in the shape of the fine pattern. Also, when a disc is obtained from the stamper by an injection molding method or the like, a pressure of several tons is applied to the stamper surface at the time of molding, the stamper is deformed, or the stamper surface is roughened.
The service life of the stamper is kept below 5000. Since the cost of manufacturing one stamper is high, it is necessary to improve the durability of the stamper in consideration of mass production and cost reduction.

The present invention has been made in view of the above circumstances, and therefore, by forming a dense coating having a small specific resistance and a high wear resistance on the outermost surface of the stamper for duplicating an optical disk, the fluidity of the resin during molding is improved. The present invention provides a stamper for duplicating an optical disc, a manufacturing method thereof, and an optical disc, which are capable of mass production of high-quality optical discs having excellent signal quality, improved filling and transferability, and excellent signal quality. Is intended.

[0008]

In order to achieve the above object, the present invention provides (1) a stamper for duplicating an optical disc having a ceramics hard film made of covalent bond or ionic bond on the outermost surface, which is on an optical disc master. Has a surface shape that is the reverse of the fine concavo-convex pattern, or
(2) A photoresist film is formed by coating on a glass substrate,
By laser exposure and development, an optical disk master having an uneven fine pattern on the photoresist film is obtained.
In a method of manufacturing a stamper for duplicating an optical disk, wherein a conductorized film is formed on the surface of the optical disc master and the stamper is electroformed by using the conductorized film as a cathode, the conductorized film comprises a ceramics hard film and a metal conductor film. A two-layer structure, (3) in (2), the conductive film is a conductive ceramics hard film, and
(4) In the above (3), the specific resistance of the conductive ceramics hard film is 50 μΩcm or less, and further,
(5) In (1) above, the ceramic hard film is T
The iN film has a reflectance of 60 at a wavelength of 700 nm of the TiN film.
% Or more, and (6) above (1) to (5)
The optical disk is manufactured by the stamper for duplicating an optical disk described in any of the above.

[0009]

The stamper for duplicating an optical disk according to the present invention has a ceramic hard film formed by covalent bonding or ionic bonding on the outermost surface. After coating and forming a photoresist film on a glass substrate, an uneven fine pattern is formed on the photoresist film by exposing and developing with a gas laser. On the optical disc original plate thus obtained,
A DLC (diamond-like carbon) film is formed, and then a Ni film is formed to form a conductor film having a two-layer structure. As described above, since the surface shape is obtained by reversing the fine concavo-convex pattern on the optical disc master, abrasion of the stamper and sagging of the fine shape are less likely to occur, and the stamper life can be extended.

[0010]

The present invention makes it possible to remarkably improve the quality of a molded optical disk by forming a dense coating having a small specific resistance on the outermost surface of the stamper for duplicating an optical disk. And a manufacturing method thereof. Specific examples will be described below. Embodiment 1 FIGS. 1A to 1E are views showing a manufacturing process of an optical disk duplication stamper according to the present invention. In the figure, 1 is a glass substrate, 2 is a photoresist film, 3 is a DLC film, 4 is Ni.
It is a film.

On the glass substrate 1 shown in FIG. 1A, a photoresist film 2 is formed by coating as shown in FIG. 1B, and thereafter, as shown in FIG. 2C, exposure and development by a gas laser are performed. Thus, an uneven fine pattern is formed on the photoresist film. On the optical disk original plate thus obtained, as shown in FIG.
DLC (diamond-like carbon) film 3 by D method
Is formed to a thickness of 500 Å, and then a Ni film 4 of 500 Å is formed by a DC sputtering method to form a conductor film having a two-layer structure, as shown in FIG. The DLC film is also called an i-C film and has an amorphous structure, which is similar to the diamond film (high hardness Hv3000).
〜5000, low friction coefficient). A stamper was manufactured by electroforming the conductive film as a cathode at a current density of 20.4 A / dm ² and peeling it from the glass substrate.

FIGS. 2 and 3 are diagrams showing the relationship between the total number of surfaces of an optical disk molded from a stamper and the recording and reproducing signal characteristics. In addition to the DLC film, for example, Al ₂ O
A ceramic hard film including oxides such as ₃ , TiO ₂ , nitrides such as BN, Si ₃ N ₄ and AlN, and carbides such as SiC and WC may be used.

Example 2 An optical disk duplicating stamper was manufactured in the same manner as in Example 1. However, as the conductor film, a TiN film which is a conductive hard ceramic film was used. The TiN film was formed by the bias sputtering method. To form a high-quality TiN film, ion bombardment with appropriate energy and irradiation current density is required.
The magnitude of the bias voltage applied to the work side, the discharge voltage,
It was found that the properties of the film formed greatly differ depending on the input power and the distance between the work and the target. That is, as shown in FIG. 4, the reflectance of the film (wavelength 700n in the figure
There is a clear correlation between the resistivity (represented by the reflectance at m) and the specific resistance. Since the increase in the reflectance of the film corresponds to the reduction of the defect level in the film and the densification of the film, it is considered that the carrier density and the mobility are improved and the specific resistance of the film is reduced.

As described above, the TiN film having the reflectance of 60% or more has a low specific resistance applicable to the conductor film of the optical disk original plate, and is a dense fiber containing no voids or the like in the grain boundaries and grains. It is a film with a texture and excellent in hardness and wear resistance. The relationship between the total number of surfaces of an optical disc molded from the stamper using a TiN film as a conductor film and the recording and reproducing signal characteristics is shown in FIGS. 2 and 3 described above. The conductive ceramic hard film may be a nitride or carbide of TiC and a transition metal such as Hf or Zr.

Comparative Example 1 An optical disk duplicating stamper was manufactured in the same manner as in Example 1. However, the conductor film was made of Ni with a thickness of 500Å. The current density during electroforming was 8 A / dm ² . The relationship between the total number of surfaces of the optical disc molded from the stamper and the recording and reproducing signal characteristics is shown in FIGS. 2 and 3.

Comparative Example 2 An optical disk duplicating stamper was manufactured in the same manner as in Comparative Example 1. When the current density during electroforming was set to 20.4 A / dm ² , hydrogen gas was generated on the cathode side, and the stamper surface became uneven. As described above, according to the present invention, since the hard film is formed first, that is, as the conductive film at the time of electroforming, the specific resistance can be made small without spoiling the shape of the fine pattern, so that the high-speed electric conductivity can be obtained. Casting is possible and the process tuft can be shortened.

[0017]

【The invention's effect】

(1) Effect corresponding to claim 1: Since the stamper for optical disk duplication according to claim 1 has a ceramics hard film on the outermost surface thereof, the surface hardness is high and wear of the stamper due to cavitation of resin flow and sagging of fine shape. Is less likely to occur, and therefore the stamper life can be set longer. In addition, since the ceramic hard film is chemically stable,
The resin has good fluidity and filling properties, and there is no adhesion of resin products during molding. As a result, it is possible to mass-produce high-quality optical disks with high yield. Conventionally, a stamper to which a ceramics hard film is post-applied in the final step has a drawback that the surface uneven pattern shape is changed by the film thickness of the ceramics hard film, but the stamper according to the present invention is a fine optical disc master. Since it has a surface shape in which such a concavo-convex pattern is extremely faithfully transferred, it is possible to mass-produce an optical disk having a stable reproduction signal quality and a high quality, which has not been available in the past. (2) Effect corresponding to claim 2: In the method for manufacturing a stamper for optical disk duplication according to claim 2, since the conductorized film has a two-layer structure of ceramics hard film / metal conductor film, the surface of the stamper is hardened by ceramics. It is possible to manufacture a stamper having a film and having a surface shape in which the fine concavo-convex pattern of the optical disk master is extremely faithfully transferred. (3) Effect corresponding to claim 3: In the method for manufacturing a stamper for optical disk duplication according to claim 3, since the conductorized film is a conductive ceramics hard film, the ceramics hard film is provided on the surface of the stamper and the fineness of the master disk of the optical disc is obtained. It is possible to manufacture a stamper having a surface shape in which a very uneven pattern is extremely faithfully transferred. Moreover, in the present invention, since the electroconductive ceramics hard film is directly electroformed as the cathode, it is possible to further shorten the process as compared with the invention of claim 2. (4) Effect corresponding to claim 4: In the method for manufacturing a stamper for optical disk duplication according to claim 4, since the specific resistance of the conductive ceramics hard film, which is a conductive film, is 50 μΩcm or less, high-speed electroforming is possible and The time required for manufacturing can be shortened. (5) Effect corresponding to claim 5: In the optical disk duplicating stamper according to claim 5, since the ceramic hard film is a TiN film having a reflectance of 60% or more at a wavelength of 700 nm, the specific resistance of the film is as low as ~ 100 µΩcm, and the optical disk It can be used as a conductor film of a master and can be directly electroformed as a cathode. Further, since the film has a high degree of compactness corresponding to the reflectance, the film has high hardness and wear resistance, and the stamper life can be set long. In addition, the TiN film has good resin fluidity and filling properties,
Since there is no adhesion of resin products during molding, it is possible to mass-produce high-quality optical disks with good yield. (6) Effect corresponding to claim 6: The optical disk according to claim 6 has a surface shape in which the fine concavo-convex pattern of the optical disk master is very faithfully transferred, and the resin has excellent fluidity and filling properties. Since it is molded by the method described above, it is possible to mass-produce an optical disk with stable reproduction signal quality and high quality, which has never been achieved.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a method of manufacturing an optical disk duplication stamper according to the present invention.

FIG. 2 is a diagram showing a relationship between the total number of surfaces of an optical disc according to the present invention and recording / reproducing signal characteristics.

FIG. 3 is a diagram showing the relationship between the total number of surfaces of an optical disc according to the present invention and the recording and reproduction signal characteristics.

FIG. 4 is a diagram showing the relationship between the reflectance and the specific resistance of the TiN film in the present invention.

FIG. 5 is a block diagram of a conventional optical disk duplicating stamper.

[Explanation of symbols]

1 ... Glass substrate, 2 ... Photoresist film, 3 ... DLC
Membrane, 4 ... Ni membrane.

Claims (6)

[Claims] 1. A stamper for duplicating an optical disc having a ceramics hard film made of a covalent bond or an ionic bond on the outermost surface, wherein the optical disc master has a surface shape obtained by inverting a fine concavo-convex pattern. For stamper. 2. A photoresist film is coated and formed on a glass substrate, and laser exposure and development are performed to obtain an optical disc master having an uneven fine pattern on the photoresist film, and then the surface of the optical disc master. In a method of manufacturing a stamper for duplicating an optical disk, wherein a conductorized film is formed on a substrate, and the stamper is electroformed by using the conductorized film as a cathode, the conductorized film comprises a ceramics hard film and a metal conductor film.
A method for manufacturing a stamper for optical disk duplication, which has a layered structure. 3. The method of manufacturing a stamper for duplicating an optical disk according to claim 2, wherein the conductive film is a conductive ceramics hard film. 4. The method for manufacturing a stamper for optical disk duplication according to claim 3, wherein the specific resistance of the conductive ceramic hard film is 50 μΩcm or less. 5. The stamper for optical disk duplication according to claim 1, wherein the ceramics hard film is a TiN film, and the reflectance of the TiN film at a wavelength of 700 nm is 60% or more. 6. An optical disc manufactured by the stamper for optical disc duplication according to claim 1. Description: