JP2004110936A - Method of manufacturing optical disk stamper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical disk stamper by which a uniform bit can be formed rapidly in a metal original disk surface. <P>SOLUTION: This method comprises: a process for forming a dye recording layer 101 on a metal original disk 102; a process for forming a pit 104 in the dye recording layer 101 by irradiating the color recording layer with a laser beam 103; a process for forming a metal mask 106 on the pit 104 and the color recording layer 101 in which the pit 104 is formed; a process for removing the dye recording layer and the metal mask 106 formed on the dye recording layer 101; a process for etching the metal original disk 102 using the metal mask 106 formed on the pit 104; and a process for removing the metal mask 106 formed in the pit 104. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an optical disk stamper, and more particularly to a method for manufacturing an optical disk stamper using a dry process.
[0002]
[Prior art]
FIG. 3 is a diagram illustrating a method of manufacturing an optical disk stamper using a conventional wet process used in manufacturing a CD (Compact Disc) or a DVD (Digital Versatile Disc). First, as shown in FIG. 3A, a photoresist is spin-coated on the polished surface of the glass master 302 to form a photoresist layer 301. Next, as shown in FIG. 3 (b), the glass master 302 is mounted on a support such as a rotary table of a master recording device (not shown) and the glass master 302 is rotated while a signal to be recorded on a CD or DVD is generated. The photoresist layer 301 is exposed by irradiating the photoresist layer 301 with the modulated laser beam. Next, as shown in FIG. 3C, the exposed photoresist layer 301 is developed, and the photoresist layer at the position irradiated with the laser beam is removed. Next, as shown in FIG. 3D, a conductive film 305 such as nickel (Ni) is formed on the photoresist layer 301 by using a sputtering method or the like. Next, as shown in FIG. 3E, nickel plating is performed on the conductive film 305 using the conductive film 305 as an electrode. Next, as shown in FIG. 3 (f), the plating layer (plating substrate) 306 formed by the nickel plating is peeled off from the glass master 302, and the back surface (the lower surface in the drawing) of the peeled plating substrate 306 is polished. The stamper 307 is obtained by removing the photoresist layer 302 remaining on the upper surface of the plating substrate 306.
[0003]
Further, as a conventional method for manufacturing an optical disk stamper, there is a method using an ion milling method using argon plasma or the like or a reactive ion etching method (dry process) using carbon tetrachloride (for example, see Patent Document 1).
[0004]
FIG. 2 is a view for explaining a method of manufacturing an optical disk stamper using such a conventional dry process. First, as shown in FIG. 2A, a photoresist is applied to a metal master (stamper base material) 202 made of nickel or SUS (stainless steel) or the like to form a photoresist layer 201. Next, as shown in FIG. 2B, the photoresist layer 201 is exposed by irradiating the photoresist layer 201 with a laser beam modulated with a signal to be recorded on a CD or DVD while rotating the metal master 202. . Next, as shown in FIG. 2C, the exposed photoresist layer 201 is developed, and the photoresist layer 201 in the laser beam irradiation area is removed to expose the metal master 202. Next, as shown in FIG. 2D, the metal master 202 is etched using the photoresist layer 205 in the unexposed area as a mask. As a result, recording pits are formed on the metal master 202 in a region where the photoresist layer 201 has been removed. Next, as shown in FIG. 2E, when the photoresist layer 205 in the unexposed area is removed, the stamper 206 is completed.
[0005]
An optical disk such as a CD or a DVD can be formed by injection molding a resin such as a polycarbonate resin using the stamper 206.
[0006]
[Patent Document 1]
JP-A-3-150738 (page 3-6, FIG. 1)
[0007]
[Problems to be solved by the invention]
In the method of manufacturing an optical disc stamper using the wet process, the plating step shown in FIG. In the plating step for manufacturing the stamper, for example, the glass master prepared in FIG. 3D is immersed in a sulfamic acid electrolytic solution, and a nickel film is deposited on the surface of the glass master by electrolysis to form a nickel stamper. However, it takes 3 to 4 hours or more in some cases to form a deposited film having a thickness (about 0.3 mm) required as a stamper, which is a bottleneck in the optical disc manufacturing process. In addition, stress is generated inside the nickel stamper, and there are various problems such as peeling from the glass master based on the stress and management of the electrolytic solution.
[0008]
In the method of manufacturing an optical disk stamper using the dry process, a metal master is etched using a photoresist layer mask. In the etching of a metal master using a photoresist mask, the etching rate of a photoresist layer serving as a mask is very high, and the etching rate of a metal master serving as an etching target is low.
For this reason, the photoresist mask is lost before the pit having a desired depth is obtained on the metal master, and a pit having a sufficient depth may not be obtained. Further, in the method of manufacturing an optical disk stamper using a dry process, since a number of heat treatment steps are performed until a photoresist mask is manufactured, the metal master may be warped. If the metal master is warped, it becomes difficult to uniformly heat-treat the surface of the metal master, and thus it is difficult to form uniform pits in the surface of the metal master.
[0009]
The present invention has been made in view of these problems, and provides a method of manufacturing an optical disk stamper capable of rapidly forming uniform pits in the surface of a metal master.
[0010]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems.
[0011]
Forming a dye recording layer on the metal master, irradiating the dye recording layer with laser light to form perforated pits in the dye recording layer, and forming the perforated pits in the perforated pit and the perforated pits Forming a metal mask on the dye recording layer; removing the dye recording layer and the metal mask formed on the dye recording layer; and forming the metal master using the metal mask formed in the perforated pit. And a step of removing a metal mask formed in the perforated pit.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a method of manufacturing an optical disc stamper according to an embodiment of the present invention. In the figure, 101 is a dye recording layer, 102 is a metal master made of nickel or the like, 103 is a laser beam, 104 is a holed pit, 105 is a metal film, 106 is a metal mask, and 107 is a stamper. First, as shown in FIG. 1 (a), a pigment is placed on a disk-shaped metal master 102 having an outer diameter of 200 mm and a thickness of 0.3 mm polished to a surface roughness (Ra) of 0.01 μm or less. Is uniformly coated to form a dye recording layer 101. The dye recording layer 101 is made of a cyanine dye, a phthalocyanine dye, an azo dye or the like dissolved in an organic solvent such as ethanol or acetone, has a maximum absorption wavelength near a recording laser wavelength, and has a decomposition temperature (sublimation temperature) of 150 to 400. Those in the range of ° C are desirable. It is desirable that the thickness of the dye recording layer 101 be higher than the height of the metal mask 106 to be formed. The metal master 102 is not limited to pure nickel, but may be a nickel alloy, stainless steel SUS303, or the like.
[0013]
Next, as shown in FIG. 1B, the metal master 102 on which the dye recording layer 101 is formed is attached to an optical disk master recording device or an information recording device, and recording is performed on a CD or DVD while rotating the metal master 102. A laser beam modulated by a signal is applied to the dye recording layer 101 to perform hole recording on the dye recording layer 101, and a perforated pit 104 penetrating through the dye recording layer 101 and reaching the metal master 102 is formed. Note that an argon ion laser or a semiconductor laser can be used as the laser light 103.
[0014]
Next, as shown in FIG. 1C, a metal target is sputtered by a sputtering apparatus to form a metal film 105 on the dye recording layer 101 and in the perforated pits 104. The etching rate of the metal film 105 to be formed is desirably lower than the etching rate of the metal master 102. As a material of the metal film 105, for example, silicon, aluminum, carbon, or the like can be used. Note that the thickness of the metal film 105 to be formed may be determined in consideration of the etching rate of the metal film.
[0015]
Next, as shown in FIG. 1D, the dye recording layer 101 is removed using an organic solvent such as ethanol or acetone. At this time, the metal film 105 on the dye recording layer 101 is also removed at the same time. As a result, a metal mask 106 is formed at a position corresponding to the perforated pit of the metal master 102.
[0016]
Next, as shown in FIG. 1E, the metal master 102 is etched by using an ion beam milling device using argon ions using the metal film 105 as a mask to form signal pits on the metal master 102. Next, the remaining metal mask 106 is removed as shown in FIG. Thus, a stamper 107 including only the metal master 102 can be obtained.
[0017]
The stamper manufactured in this manner is processed into a predetermined size on the inner and outer circumferences, and then mounted on an injection molding machine, and injection molded using a polycarbonate resin as a raw material. Thus, a large number of replicas of optical disks such as CDs and DVDs can be manufactured.
[0018]
Next, this embodiment will be described in more detail. First, as shown in FIG. 1A, a disk-shaped nickel substrate having a thickness of 0.3 mm and an outer diameter of 200 mm is prepared. The surface of the nickel substrate is polished to an average roughness (Ra) of 0.01 μm or less. The surface to be polished may be both surfaces or only one surface.
[0019]
After washing this nickel substrate, it is attached to a spinner device, and a cyanine dye dissolved in tetrafluoropropanol is spin-coated to form a dye recording layer on the polished surface of the nickel substrate. The maximum absorption wavelength of the cyanine dye is 750 nm, and the decomposition temperature is 320 ° C. The concentration of the cyanine dye and the number of revolutions of the spinner device were controlled so that the thickness of the cyanine dye after coating and drying became 150 nm.
[0020]
Next, as shown in FIG. 1 (b), the nickel substrate on which the dye recording layer was formed was mounted on a recorder equipped with an optical head incorporating a semiconductor laser having a wavelength of 780 nm, and a signal to be recorded on a CD was recorded. The recording was performed by irradiating the dye recording layer with a laser beam modulated by EFM (EFM modulation). The recording power of the laser beam was 12 mW. At this time, the dye recording layer irradiated with the laser light was decomposed and sublimated to form a perforated pit corresponding to the laser irradiation time.
[0021]
Next, as shown in FIG. 1C, the nickel substrate on which the recording was performed was mounted on a sputtering apparatus, and a silicon film as a metal film was formed on the dye recording layer. At this time, vacuum was drawn so as to be 1 × 10 ⁻³ Pa or less, and a silicon (Si) film was formed using argon as a sputtering gas. The degree of vacuum of the vacuum chamber after introducing the argon gas was set to 0.4 Pa. The splatter rate of silicon is very low at 0.4 atoms / ion with respect to nickel at 1.2 atoms / ion. For this reason, the thickness of the silicon film to be formed is set to 50 nm in consideration of the sutter rate of silicon. The silicon film was formed in the perforated pit formed by irradiating the laser beam and on the dye recording layer left on the nickel substrate.
[0022]
Next, as shown in FIG. 1D, the nickel substrate is attached to the spinner again, and acetone is sprayed on the entire surface of the nickel substrate while rotating. As a result, the dye recording layer remaining on the nickel substrate was dissolved, and at the same time, the silicon film on the dye recording layer was removed. Further, the nickel substrate was rotated at a high speed to dry the acetone remaining on the nickel substrate.
[0023]
Next, as shown in FIG. 1 (e), a nickel substrate was mounted on an ion beam milling apparatus, evacuated to 5 × 10 ⁻⁴ Pa or less, and etched using argon ions using a silicon film as a mask to obtain nickel. A 110 nm concave portion, which is a signal pit search for a CD, was formed in the substrate. Next, as shown in FIG. 1F, the remaining silicon film was removed. As a result, a CD stamper directly formed from the nickel substrate could be obtained. The production time of the stamper according to this method is approximately 2 hours, and the stamper can be produced in approximately 1/2 the time of the conventional wet process shown in FIG.
[0024]
Using the stamper thus manufactured, a target CD was manufactured through the respective steps of injection molding, aluminum reflection film formation, and UV protection film coating, which are normal CD manufacturing steps. Next, this CD was mounted on a CD inspection machine, and the block error and the 3T jitter, which are evaluation items of the CD performance, were measured. The block error was 10 or less, and the 3T jitter was 25 ns or less. That is, the condition that the standard value is 210 block errors or less and the 3T jitter is 35 ns or less was sufficiently satisfied.
[0025]
As a comparative example, when the block error and 3T jitter of a CD manufactured using the CD stamper of the manufacturing method shown in FIG. 2 were measured, the block error was 200 to 300, and the 3T jitter was 40 ns or less. I was not satisfied.
[0026]
According to the present embodiment, a cyanine dye is used for the dye recording layer. The cyanine dye can be easily and uniformly formed on a substrate by spin coating. Further, since it is not necessary to perform heat treatment (pre-bake and post-bake) after film formation like a photoresist film, the metal master does not warp. Therefore, non-uniform heat treatment due to warpage is not applied to the metal master.
Therefore, an optical disk having a uniform pit shape can be manufactured. Further, the dye recording layer can be easily removed with a solvent such as acetone, and the manufacturing process can be simplified.
[0027]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a method of manufacturing an optical disk stamper capable of rapidly forming uniform pits in the surface of a metal master.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a method for manufacturing an optical disc stamper according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a method of manufacturing an optical disk stamper using a conventional dry process.
FIG. 3 is a diagram illustrating a method for manufacturing an optical disk stamper using a conventional wet process.
[Explanation of symbols]
101 Dye recording layer 102 Metal master 103 Laser beam 104 Perforated pit 105 Metal film 107 Stamper

Claims (2)

A step of forming a dye recording layer on the metal master,
Irradiating the dye recording layer with laser light to form perforated pits in the dye recording layer,
Forming a metal mask in the perforated pits and on the dye recording layer in which the perforated pits are formed,
Removing the metal mask formed on the dye recording layer and the dye recording layer, and etching the metal master using a metal mask formed in the perforated pits,
Removing the metal mask formed in the perforated pits. 2. The method according to claim 1, wherein the dye recording layer formed on the metal master comprises a cyanine dye.

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