JP3108962B2 - Manufacturing method of stamper for optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the recording of information using light,
The present invention relates to a method of manufacturing a stamper for an optical recording medium used for an optical recording medium on which reproduction or erasing is performed.

[0002]

2. Description of the Related Art In a conventional mastering process for producing a stamper for an optical recording medium, for example, Japanese Patent Laid-Open Publication No. Hei.
First, as described in 1, a positive resist is applied on a glass master to form a photoresist master, and laser cutting for exposing using a laser beam is performed.
The resist was developed with an alkali solution, and the developed portion was made conductive by vacuum-forming nickel, and nickel was electroformed using the conductive portion as an electrode and peeled off from the glass master to form a stamper. Then, a substrate is formed using the stamper, and a recording layer is formed on the substrate to produce an optical recording medium. As described above, in the related art, after a resist is usually applied, prebaking is performed at a temperature of about 50 ° C. to 90 ° C., and exposure is performed using a focused laser beam. Also, as a method of performing laser cutting after forming a layer other than a resist, J. J. Appl. App
l. Phys. 58 (8), 15 October 1
985, it has been attempted to form a resist layer on an indium oxide layer, and then perform exposure and development to etch the exposed indium oxide layer.

[0003]

However, in the prior art, after the resist is applied, it is prebaked at a temperature of about 50 ° C. to 90 ° C., and the exposure is performed with the condensed laser light as it is. In the meantime, there has been a problem that the surface of the resist is deteriorated by an atmosphere or dust adheres to the resist, which causes an increase in errors of the optical recording medium.

Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to protect a resist surface with a water-soluble resin so that accurate grooves and pits corresponding to exposure can be formed. To reduce errors in optical recording media created using, and to protect the master before applying the resist, and to deteriorate the surface of the master before the resist is applied due to the deterioration of the surface of the master due to the atmosphere or the attachment of dust. It is an object of the present invention to provide a high-performance and high-reliability optical recording medium that does not cause a problem.

[0005]

According to a first method of manufacturing a stamper for an optical recording medium of the present invention, a positive type resist layer (2) is formed on a master (1), and a predetermined resist is formed on the optical recording medium. The pattern is exposed and developed, the surface is made conductive with a metal film (6), and a metal layer (7) is electroformed and peeled off from the master (1). After applying the resist layer (2), a water-soluble resin layer (3) is formed, and after removing the water-soluble resin layer (3) from the top of the water-soluble resin layer (3), the positive mold is removed. The resist layer (2) is exposed to light.

According to a second method of manufacturing a stamper for an optical recording medium of the present invention, a water-soluble resin layer (10) is formed before a positive resist layer 11 is formed on a master (9). After the water-soluble resin layer (10) is removed from the water-soluble resin layer (10), the positive resist layer (11) is applied and exposed.

Further, the above-mentioned water-soluble resin layer (2, 10)
Is characterized in that a substance mainly composed of polyvinylpyrrolidone is used.

[0008]

【Example】

Embodiment 1 The present invention will be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram of a method for manufacturing a stamper for an optical recording medium according to the present invention.

1 is a glass master, 2 is a positive resist layer, 3 is a water-soluble resin layer, 4 is an exposed portion, 5 is a developed portion, 6 is a metal film, 7 is a metal layer, and 8 is a completed light. This is a recording medium stamper.

The surface of the glass master 1 was cleaned and treated with hexamethyldisilazane to improve the adhesion to the resist. Next, a positive resist layer 2 is formed by applying a spin coat method,
The solvent in the resist layer was removed by performing prebaking at about 0 ° C.

Next, a water-soluble resin layer 3 was formed on the surface of the resist layer. The application of the water-soluble resin layer was performed by a method of spin-coating by spreading the water-soluble resin on the resist while rotating the glass master 1 together. However, this coating method could be performed by other methods such as dipping and curtain coating. As the kind of the water-soluble resin, a resin containing polyvinylpyrrolidone as a main material was used.

Thereafter, by heating the glass master, the resist and the water-soluble resin layer were pre-baked, and exposed according to the pattern of the optical recording medium to form an exposed portion 4. This exposure has effects such as protection of the resist layer and prevention of adhesion of dust even after the water-soluble resin layer 3 is removed with pure water or a solvent. As a method for removing the water-soluble resin layer 3, water was applied while rotating the master 1 and then the rotation was increased to drain the water. Also, this exposure is Master 1
Was carried out using a HeCd laser focused while rotating. Then, development was performed using an inorganic or organic alkaline developer to form a developed portion 5. Then, post baking was performed at about 80 ° C. to 90 ° C. In this exposure step, a similar effect was obtained by changing the refractive indices of the resist and the water-soluble resin so that the laser focused on the resist surface. Since a normal resist uses an aromatic novolak resin, a refractive index of more than 1.6 can be obtained. However, when a water-soluble resin is made of an aliphatic resin, a refractive index of 1.4 can be obtained. Was. When the resist is exposed only at the center of the laser beam such that the focal point is located on the surface of the water-soluble resin, it is better that the refractive indices of the resist and the water-soluble resin be as close as possible.

After the development, a nickel film is formed by vacuum film formation at a thickness of about 400 to 2000 ° to form a metal film 6, and the nickel layer which is the metal layer 7 is formed from the metal layer 6 using the metal film 6 as an electrode. Electroformed about 0.3 mm. Then, the stamper 8 was formed by peeling off the glass master 1 and processing the inner and outer diameters. Vacuum film formation includes vapor deposition, sputtering, CVD, ion plating and the like, and all have the same effect. As the electroforming method, a method such as electroless plating could be used in addition to electrolytic plating using a sulfamic acid-based additive.

Next, a substrate was formed by using the stamper 8 by injection molding, injection compression molding, a photopolymer method, or the like, using a polycarbonate resin, an amorphous polyolefin, or another resin.

Further, an optical disk was prepared by forming a recording layer on the substrate. In this case, as the recording layer, various types such as a magneto-optical recording film made of an alloy of a rare earth metal and a transition metal, an optical phase change type in which tellurium and tellurium oxide are mixed, or a layer using a dye such as cyanine can be used. It was possible.

Next, the resist used in this embodiment will be described. The positive type resist layer 2 uses a naphthoquinonediazide type, a phenol novolak resin type, and a solvent mainly containing ethylcellosolve acetate as a main solvent. However, the solvent is not limited to xylene, acetic acid, and the like. What added several tens% of butyl etc. may be sufficient. The sensitizer of the resist is preferably one having high sensitivity to light used for exposure. That is, HeCd
High sensitivity was used at the wavelength of the laser. In order to improve the resolution of the resist, it is preferable to use a phenol novolak resin synthesized so that the molecular weight dispersion (weight average molecular weight / number average molecular weight) is less than 3. More preferably, it was less than 2. The development was performed with an alkali solution, but a sodium silicate system, a sodium phosphate system, a buffer solution thereof, a quaternary alkyl ammonium hydroxide, or the like could be used.

Further, it was better to add a surfactant to this developer in order to measure the uniformity of development. The surfactant to be added is preferably an anionic surfactant having a small inhibitory effect on development and having good compatibility with the alkali of the developing solution. Among the anionic surfactants, the compatibility with the developing solution and stability are taken into consideration. Those having a relatively high molecular weight and high permeability and being stable were preferred. Examples thereof include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acyl amino acids and salts thereof, N-acylmethyl taurine salts, alkyl sulfate polyoxyalkyl ether sulfates, Alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate, lauryl alcohol sulfate, alkyl phenol type phosphate, alkyl type phosphate, alkyl allyl sulfonate, etc. There was an effect.

(Embodiment 2) Next, FIG. 2 will be described.
9 is a glass master, 10 is a water-soluble resin layer, 11 is a positive resist layer, 12 is an exposed portion, 13 is a developed portion,
Reference numeral 4 denotes a metal film, 15 denotes a metal layer, and 16 denotes a stamper for an optical recording medium.

A water-soluble resin layer 10 was formed on a glass master 9 by spin coating or dipping. A positive resist layer 11 was formed thereon by spin coating. In this case, the water-soluble resin layer 10 may be peeled off with water before the positive resist layer 11 is formed.
This has the effect of protecting the master and preventing dust from adhering.
Then, when the resist layer 11 was exposed while rotating the master 9, an exposed portion 12 was formed. And this exposed part 1
By developing 2, a developing portion 13 was formed. Thereafter, a metal film 14 was formed on the developed portion by vacuum film formation. Here, the metal layer 14 was a two-layer film of a silver-copper alloy film and a nickel film. Then, the metal layer 15 was electroformed. Here, nickel was plated as the metal layer 15. Then, the stamper 16 for an optical recording medium was formed by peeling off the master 9, processing the inner and outer peripheral portions, and polishing the back surface.

(Embodiment 3) Here, a comparison with a conventional method will be described. When a water-soluble resin layer is not formed as in the conventional case, many defects are generated due to various factors during the process. However, in the method according to the present invention, since the water-soluble resin is present until immediately before the resist coating, the conductivity of the surface is maintained by the moisturizing force, and the desorption of dust is easy.

Next, a case where an optical recording medium is manufactured using the optical recording medium stamper manufactured by the method according to the present invention will be described.

First, as shown in the present embodiment, exposure was performed using a laser cutting machine so that the track pitch and the pit pitch were reduced to half those of the prior art. Conventionally, the track pitch was 1.6 μm.
m. The interval of the pit row was also reduced by half. Then, development was performed, and a substrate was manufactured by the method described in this example. Using an optical disk on which a multilayer film made of platinum and cobalt is formed as a recording layer using the substrate, 83
When recording / reproducing was performed using an optical system in which a laser having a wavelength of 0 nm was converted to a wavelength of 415 nm by an SHG element, the error occurrence rate was reduced to one-tenth that of an optical recording medium prepared by a conventional method.

Further, the noise can be reduced even when a rare earth transition metal based recording film is used. For example, examples of rare earth elements include Ce, Pr, Nd, Sm, Eu, and G.
one or more metals selected from d, Tb, Dy, Ho, Er, Tm, Yb and Lu, and F as a transition metal
e, one or two or more metal films selected from Co, Ni, or Be, B, C, N, Mg,
Al, Si, P, Sc, Ti, V, Cr, Mn, Cu,
Zn, Ga, Ge, As, Se, La, Y, Zr, N
b, Mo, Tc, Ru, Rh, Pd, Ag, Cd, I
n, Sn, Sb, Te, Hf, Ta, W, Re, Os,
A film composed of a single layer or a multilayer film of one or more metals selected from Ir, Pt, Au, Pb, Bi, and Po could be used. Examples of the multilayer film include a combination of a film having perpendicular magnetic anisotropy and a film having a large Kerr rotation angle at the reproduction wavelength, a film having a large Kerr rotation angle between the films having perpendicular magnetic anisotropy, or a transparent film. A film in which the recording layer is sandwiched by the protective layer and a reflective film mainly composed of Al, Ti, Ag, Pt, and Au having high reflectivity may be considered, and the same effect was actually obtained. . In this case, the track pitch was set to 1.6 μm, but the present invention is not limited to this. A similar effect was obtained when the track pitch was about 1.0 μm to 1.6 μm or more.

When the stamper for an optical recording medium produced by the conventional method and the stamper for the optical recording medium produced by the method of the present invention were observed with an atomic force microscope, the stamper for an optical recording medium of the present invention was It was observed that the surface unevenness was reduced as compared with the method, whereby the recording signal noise was reduced, and the performance of the optical recording medium could be improved.

In this embodiment, for example, an example in which a HeCd laser is used as a light source for exposing a resist has been described.
Similar results were obtained when a HeCd laser having a wavelength of 448 nm or 325 nm, an Ar laser, a laser using an SHG element, or the like was used. In this embodiment, an example using a water-soluble resin mainly composed of polyvinylpyrrolidone has been described, but the present invention is not limited to this. Acrylic acid type, alginic acid type, carboxymethylcellulose type, vinyl acetate type, etc. may be used, but the viscosity tends to increase when dissolved in water. The lower ones were easier to apply. Similar results were obtained by adding a surfactant to ensure the moisture retention of these water-soluble resins. As the surfactant, in addition to the anionic surfactant described in Example 1, a nonionic surfactant,
An amphoteric surfactant or the like can be used, and similar results were obtained in an actual experiment.

It should be noted that the present invention should not be considered to be limited to only these embodiments, and various changes in each section of the embodiments are possible without departing from the gist of the present invention.

[0027]

As described above, according to the present invention, the surface of the master and / or the resist layer is protected by a water-soluble resin so that accurate grooves and pits corresponding to the exposure can be formed. This has the effect of reducing errors in the created optical recording medium and providing an optical recording medium with high performance and high reliability.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a method for manufacturing a stamper for an optical recording medium of the present invention.

FIG. 2 is a conceptual diagram illustrating a method for manufacturing a stamper for an optical recording medium of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 glass master 2 positive resist layer 3 water-soluble resin layer 4 exposed part 5 developed part 6 metal film 7 metal layer 8 stamper for optical recording medium 9 glass master 10 water-soluble resin layer 11 positive resist layer DESCRIPTION OF SYMBOLS 12 Exposure part 13 Developed part 14 Metal film 15 Metal layer 16 Stamper for optical recording media

Claims (5)

(57) [Claims] 1. A positive resist layer (2) is formed on a master (1), exposed and developed to a predetermined pattern of an optical recording medium, and the surface is made conductive with a metal film (6). A water-soluble resin layer (3) is formed after applying the resist layer (2) on an optical recording medium stamper (8) formed by electroforming the layer (7) and peeling the layer from the master (1). And a step of exposing the positive resist layer (2) from above or after removing the water-soluble resin layer (3). Production method. 2. A positive resist layer 1 on a master (9).
Forming a water-soluble resin layer (10) before forming 1 and on the water-soluble resin layer (10) or the water-soluble resin layer (10).
And then applying and exposing the positive resist layer (11) to the stamper for an optical recording medium. 3. The water-soluble resin layer (2, 10)
3. The method for producing a stamper for an optical recording medium according to claim 1, wherein a substance mainly comprising polyvinylpyrrolidone is used. 4. The method for producing a stamper for an optical recording medium according to claim 1, wherein the water-soluble resin layer is formed by applying a water-soluble resin onto the resist by a spin coating method. 5. The method for producing a stamper for an optical recording medium according to claim 2, wherein the water-soluble resin layer is formed by applying a water-soluble resin onto the master by spin coating or dipping.