JP2000040270A - Manufacturing method of optical disk substrate - Google Patents

Abstract

(57) Abstract: Provided is a method of manufacturing an optical disc which realizes an increase in capacity of an optical disc substrate and a reduction in noise level by enabling high-precision and fine formation of grooves and pits of an optical disc substrate. SOLUTION: After a film 2 made of an organic material is formed on a substrate 1 serving as a mastering master, a pattern of a mask material 3 serving as an etching mask is formed on the organic material film 2 and the organic material film 2 is etched. The mastering master 10 is formed by removing the mask material 3, a metal film 4 a is formed on the mastering master 10, a metal main body 4 b is integrally formed on the metal film 4 a, and then the metal film 4 a and the metal The metal part composed of the main body part 4b is separated from the mastering master 10 to form the metal stamper 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a CD, DVD-RO
It is mainly used for manufacturing optical disk substrates such as M and DVD-RAM.

[0002]

2. Description of the Related Art A conventional method of manufacturing an optical disk substrate will be described below.

[0003] As an example of a conventional optical disk manufacturing method, there is a document (p2
9, 1996) discloses a method for manufacturing a high-density optical disk using the Deep Groove method.
The creation of a mastering master using a dry etching method has been reported.

FIG. 3 shows a conventional example of a process for producing a mastering master using a dry etching method. In FIG. 3, reference numeral 31a denotes a quartz substrate serving as a mastering master disc;
Reference numeral 2 denotes a resist pattern serving as an etching mask, and the mask pattern is formed by exposure and development using a laser cutting machine. 31b is a quartz substrate from which the resist has been removed after dry etching. 34 is N
Ni film 34 formed by sputtering using i stamper
a and a Ni main body 34b formed by an electroforming method. Reference numeral 35 denotes a resin-molded polycarbonate optical disk substrate.

[0005] A process for producing a mastering master using a dry etching method in manufacturing an optical disk substrate will be described below.

First, a 140 nm-thick resist is formed on a quartz substrate 31a by a spin coating method. Next, the resist is exposed to form a groove pattern and a pit pattern by a laser cutting machine, and then developed to obtain a resist pattern 32 (FIG. 3). Next, using the resist pattern 32 as an etching mask, the quartz substrate is etched to a depth of 70 nm by dry etching using a gas containing oxygen and fluorine (for example, a mixed gas of CHF ₃ and O ₂ ), and then the resist is removed. A quartz substrate 31b having surface irregularities is formed (FIG. 3). After cleaning the quartz substrate 31b, a 50 nm-thick Ni film 34a is formed on the quartz substrate 31b by a sputtering method. Next, a thickness of 0.
The Ni body 34b is formed by 4 mm Ni plating (FIG. 3). Thereafter, the Ni portion is peeled off from the quartz substrate 31b to obtain a Ni stamper 34 (FIG. 3). Using the Ni stamper 34 as a mold, a polycarbonate optical disk substrate 35 is resin-molded, a recording film and a protective film are formed on the substrate 35, and the protective substrate is bonded with an adhesive to obtain an optical disk substrate ( Figure 3,).

[0007]

However, in the above-mentioned conventional method, when the Ni stamper 34 is separated from the quartz substrate 31b in which the grooves and pits have been formed by dry etching, the thermal expansion of the quartz substrate 31b and the Ni stamper 34 is performed. The quartz substrate 31b and the Ni stamper 34 rub against each other due to the difference in coefficient and the internal stress of the Ni film 34a, and the difference in hardness between quartz and Ni causes burrs on the stamper surface as shown in FIG. As a result, there is a problem that the shape is transferred to the molded optical disk substrate 35 to form a concave groove Q, and noise occurs in recording and reproduction. Also,
When grooves and pits are formed on a quartz substrate by dry etching, the depth of the grooves and pits is controlled by the processing time of the dry etching. And noise characteristics vary.

As another method of manufacturing an optical disk, a method of forming a Ni stamper directly on a resist pattern formed on a quartz substrate has been conventionally performed, but the resist pattern is formed into a fine pattern for high-density recording. There is a problem that it is difficult to form a corresponding rectangular shape, and since the surface of the patterned resist film is not smooth and rough, noise characteristics are poor and miniaturization is difficult.

According to the present invention, there is provided a metal stamper manufacturing method and a metal stamper for realizing an increase in the capacity of an optical disk and a reduction in noise level by enabling formation of fine and high-density grooves and pits on an optical disk substrate. It is another object of the present invention to provide an optical disk substrate manufacturing method and an optical disk substrate. Another object of the present invention is to increase the depth accuracy of groove formation and pit formation and to form the groove with high reproducibility.

[0010]

The object of the present invention has been attained by providing the above-mentioned object with the structure described in the appended claims. As a specific example, a film made of an organic material is formed on a substrate serving as a mastering master, and after a pattern of a mask material serving as an etching mask is formed on the organic material film and the organic material film is etched,
Remove the mask material to create a mastering master,
After forming a metal film on the mastering master, a metal main body is integrally formed on the metal film, and then a metal part composed of the metal film and the metal main body is peeled off from the mastering master to form a metal stamper. It is preferable to mold the optical disc substrate with a resin using a metal stamper. In the method for manufacturing an optical disk substrate of the present invention, it is preferable that the thickness of the organic material film is the depth of a groove or a pit in the molded optical disk substrate.

According to this invention, for example, when the metal stamper is peeled off from the mastering master, the low hardness material has a lower hardness than the metal forming the convex portion of the metal stamper. Because it does not generate
It is possible to form grooves and pits of an optical disk substrate with high precision. Further, by making the thickness of the low hardness material the same as the depth of the groove or pit in the molded optical disk substrate, the low hardness material can be etched almost selectively with respect to the substrate, and the groove and pit depth can be reduced. As a result, the in-plane uniformity and the production reproducibility can be improved. As a result, the depth accuracy of the groove formation and the pit formation can be improved, and the optical disc substrate can be produced with good reproducibility.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a metal stamper, a metal stamper manufactured by the method, an optical disk substrate manufacturing method using the metal stamper, and the manufacturing method according to embodiments of the present invention. An optical disk substrate manufactured by the method will be described with reference to the drawings.

(Embodiment 1) In FIG. 1, reference numeral 1 denotes an Si substrate serving as a base material of a master which is a mold material of a metal stamper 4,
Reference numeral 2 denotes a film of an organic material corresponding to a low-hardness material, specifically, an acrylic film formed to a thickness of 100 nm by a spin coating method, 3 denotes a resist material serving as an etching mask, and the mask pattern is laser cutting. It is formed by exposure and development by a machine. 2a is a dry-etched acrylic film. Reference numeral 4 denotes a metal stamper, which comprises a Ni film 4a as a metal film formed by a sputtering method and a Ni body 4b as a metal body formed by an electroforming method, which is a so-called plating method. 5
Is an optical disk substrate made of a resin-molded polycarbonate material.

The method of manufacturing the optical disk substrate configured as described above will be described with reference to FIG.

First, after acrylic resin is dropped on the Si substrate 1, the Si substrate 1 is rotated and the acrylic resin is applied to the entire surface of the Si substrate 1 by the centrifugal force. After the resin material is applied, it is cured by heat treatment and the acrylic film 2 is formed on the Si substrate 1.
Is formed with a thickness of 100 nm. The method of forming the acrylic film 2 is not limited to the spin coating method as long as it can obtain a uniform film thickness. Next, a photoresist film is formed on the acrylic film 2 by a spin coating method, and then the resist material is exposed by a laser cutting machine so as to form a groove pattern and a pit pattern, and then developed. A pattern 3 is obtained (FIG. 1). For example, as disclosed in Japanese Patent No. 2623672, a gas containing oxygen and fluorine, for example, 0
_{After the} unmasked portion 2c of the acrylic film 2 not masked by the resist pattern 3 is etched to a depth of 70 nm by dry etching using a mixed gas of ₂ and CHF ₃ , the resist is removed with a methyl isobutyl ketone solution. Then, by washing with isopropyl alcohol, an acrylic film 2a having surface irregularities is formed (FIG. 1). Thus, the acrylic film 2 on the Si substrate 1
The one on which a is formed is referred to as a mastering master 10. On the Si substrate 1 with the acrylic film 2a, a Ni film 4a is formed to a thickness of 50 nm by a sputtering method. Next, a 0.4 mm thick Ni film was formed on the Ni film 4a by electroforming.
By plating, the Ni main body 4b is integrally formed (FIG. 1,
Then, the Ni portion where the Ni film 4a and the Ni main body 4b are integrally formed is peeled off from the mastering master 10 to obtain the Ni stamper 4 (FIG. 1). In the Ni stamper 4 thus manufactured, a convex portion 4c and a concave portion 4d are formed according to the irregularities of the acrylic film 2a. It should be noted that pits constituting data to be transferred to the optical disk substrate are formed in the convex portion 4c and the concave portion 4d or the convex portion 4c or the concave portion 4d. At this time, a part of the acrylic film 2 may be slightly adhered to the surface of the Ni stamper 4. Therefore, the surface of the Ni stamper 4 is cleaned with plasma by a plasma ashing method using oxygen gas.
The remaining acrylic film is removed. Using this Ni stamper 4 as a mold, a polycarbonate optical disk substrate 5 is resin-molded (FIG. 1). By forming a recording film and a protective film on the substrate 5 and bonding the protective substrate with an adhesive,
An optical disc substrate as a final product is obtained (not shown).

As described above, according to this embodiment, it is possible to finely process the uneven surface of the mastering master 10 so that the bottom and top surfaces (surfaces other than the side surfaces of the grooves and pits) are smooth, and , The surface of the mastering master 10 is N
Since the acrylic is lower in hardness than Ni of the i stamper 4, no scratches or burrs are generated on the surface of the Ni stamper 4 when the Ni stamper 4 is peeled off, and fine formation of grooves and pits of the optical disc substrate 5 is prevented. By doing so, it is possible to increase the capacity of the optical disk and reduce the noise level.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be specifically described with reference to FIG.

In FIG. 2, the difference from the first embodiment is that the acrylic film 2 is formed by setting the coating film thickness to the depth of the grooves and pits. Are identical.

Referring to FIG. 2, a description will be given of a manufacturing process of the method for manufacturing the optical disk substrate configured as described above.

First, acrylic is applied on the Si substrate 1 by a spin coating method, and then cured by heat treatment to cure the Si substrate 1.
An acrylic film 2 is formed thereon with a thickness of 70 nm which is the same as the design depth of the grooves and pits. Next, a photoresist film made of a resist material is formed on the acrylic film 2 by a spin coating method, and then the resist material is exposed by a laser cutting machine to form a groove pattern and a pit pattern, and then developed. A resist pattern 3 made of a resist material is obtained (FIG. 2). Next, using the resist pattern 3 as an etching mask, the non-mask portion 2c of the acrylic film 2 is etched by dry etching using an oxygen-based gas to a depth substantially equal to the level of the smooth surface 1a of the underlying Si substrate 1. After that, the resist material 3 is removed with a methyl isobutyl ketone solution and then washed with isopropyl alcohol to form a pattern 2b of the acrylic film 2 (FIG. 2). Subsequent steps of manufacturing the optical disk substrate (FIGS. 2 to) are the same as those of the first embodiment (FIGS. 1 to). As described above, the reason that an oxygen-based gas is used is that the gas containing fluorine atoms erodes Si of the substrate 1 and the smooth surface 1
This is because a becomes rough.

As described above, according to the present embodiment, since the surface of the mastering master 10 is acrylic having a hardness lower than that of Ni of the Ni stamper 4, the surface of the Ni stamper 4 is removed when the Ni stamper 4 is peeled off. The generation of scratches and burrs does not occur, and the formation of the grooves and pits of the optical disk substrate 5 can be finely performed, thereby increasing the capacity of the optical disk and reducing the noise level. Also, by using an oxygen-based gas containing no fluorine gas, the underlying Si
By selectively etching only the acrylic film 2 without eroding the substrate 1, as shown in FIG.
The top surface 4e of the projection 4c of the stamper 4 can be made smooth. In addition, the depth of the grooves and pits of the optical disk substrate to be formed by the selective etching can be defined by the thickness of the acrylic film formed by coating, and the uniformity and reproducibility of the etching time and the etching rate can be determined. Processing can be performed without being affected by variations, and the depth accuracy of groove formation and pit formation can be increased within the disk surface with high reproducibility.

In the above embodiment, a resin material containing acrylic as a main component is used as the organic film. However, an organic resin such as polyimide may be used, and the material is not limited to these. A low-hardness material that is softer than the metal stamper and that has a hardness enough to withstand the shape of the metal stamper and prevent deformation of the convex portion of the metal stamper when peeled off from the metal stamper The same effect can be obtained by using. On the other hand, Ni is exemplified as the metal forming the metal stamper, but the metal is not limited to Ni. In other words, any material can be used as long as it can exhibit the function as a stamper and has a hardness that does not cause deformation of the projection when the low-hardness material is peeled off, or a material similar to other metals.

In the above embodiment, the Si substrate 1 is used as the substrate of the mastering master 10. However, the present invention is not limited to this, and a substrate having a smooth surface such as a quartz substrate or a glass substrate may be used.

[0024]

As described above, according to the present invention, a pattern for forming an uneven portion on a metal stamper is formed on a substrate of a mastering master using a low-hardness material. When the metal stamper having a low thickness is peeled off from the mastering master, scratches and burrs are not generated on the surface of the metal stamper. Therefore, it is possible to form grooves and pits of the optical disk substrate formed by using the metal stamper with high precision and fineness, thereby increasing the capacity of the optical disk substrate and reducing the noise level. The depth accuracy of the optical disk can be increased within the disk surface, and an optical disk substrate can be manufactured with good reproducibility.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a manufacturing process of an optical disc substrate according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a manufacturing process of an optical disk substrate according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of a conventional optical disc substrate.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 organic material film 3 resist material 4 metal stamper 4a metal film 4b metal main body 5 optical disk substrate 10 mastering master

Claims (13)

[Claims] 1. A film made of a low-hardness material is formed on a substrate serving as a master, and a pattern of a mask material serving as an etching mask is formed on the low-hardness material film, and is not masked by the mask material. After etching at least a part of the non-mask portion of the low hardness material along the thickness direction of the substrate, the mask material is removed to produce the master, a metal part is formed on the master, and then the The metal part was peeled off from the master to produce a metal stamper,
The method of manufacturing a metal stamper, wherein the low-hardness material is a material having a hardness low enough to prevent the deformation of the protrusion when the metal stamper is separated from the metal in the protrusion of the metal stamper. Method. 2. The non-mask portion of the low-hardness material is entirely removed along the thickness direction of the substrate to expose a smooth surface of the substrate, and a smooth top surface of the projection is formed on the surface. The method for manufacturing a metal stamper according to claim 1, wherein the metal stamper is formed. 3. The film thickness of the low-hardness material formed on the substrate of the master corresponds to the depth of a groove or a pit in an optical disk substrate manufactured by using the metal stamper. The method for producing a metal stamper according to the above. 4. The method for manufacturing a metal stamper according to claim 1, wherein the low hardness material is an organic material. 5. The method for manufacturing a metal stamper according to claim 4, wherein the removal of the non-mask portion is performed by dry etching of a gas containing oxygen. 6. The method for manufacturing a metal stamper according to claim 4, wherein the removal of the non-mask portion is performed by dry etching of a gas obtained by adding a gas containing fluorine to a gas containing oxygen. 7. The method for manufacturing a metal stamper according to claim 4, wherein said low-hardness material is a resin material containing polyimide as a main component. 8. The method for manufacturing a metal stamper according to claim 4, wherein said low hardness material is a resin material containing acrylic as a main component. 9. The method according to claim 1, wherein the substrate is made of Si or quartz. 10. The metal part of the metal stamper,
2. A Ni film is formed on the substrate having the pattern of the master by the sputtering method, and then a Ni main body is formed on the Ni film by a Ni electroforming method.
10. The method for producing a metal stamper according to any one of claims 9 to 9. 11. A metal stamper manufactured by using the method for manufacturing a metal stamper according to claim 1. Description: 12. A method for manufacturing an optical disk substrate, comprising forming a resin using the metal stamper according to claim 11. 13. An optical disk substrate formed by resin molding according to the method for manufacturing an optical disk substrate according to claim 12.