JP3168609B2 - Method of manufacturing stamper for optical recording medium and method of manufacturing optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a stamper for an optical recording medium and a method for manufacturing an optical recording medium.

[0002]

2. Description of the Related Art A conventional optical recording medium has been manufactured as follows. First, a positive resist is applied on a glass master and exposed using a laser beam, and then the resist is developed with an alkaline solution. Then, the developed portion is converted into a conductor by forming a vacuum film of nickel, and the conductive portion is used as an electrode to electroform nickel and peel off from the glass master to form a stamper. An optical recording medium has been created by forming a substrate using the stamper and forming a recording layer on the substrate. At this time, the laser used for the exposure is a helium cadmium laser or the like.
It has a wavelength of the order of 0 nanometer, the finest line that can be drawn is about 0.4 micrometer, and no thinner line can be drawn. Therefore, the width of the groove was about 0.4 μm and the track pitch was about 1.6 μm. Then, a laser having a wavelength of about 800 nanometers was used for recording and reproduction of the optical recording medium.

[0003]

However, in the prior art, since grooves and pits for tracking are formed using a helium cadmium laser, cutting can be performed only in accordance with the wavelength of the helium cadmium laser, and substantially zero. Since grooves and pits thinner than .4 micrometers could not be formed, there was no recording / reproducing substrate using laser light having a shorter wavelength using an SHG element or the like.
Naturally, there was a problem that high-density recording had a limit.

Accordingly, the present invention has been made to solve such a problem, and an object thereof is to form a groove or a pit narrower than a groove or a pit corresponding to the wavelength of a helium cadmium laser by using an SHG element. An object of the present invention is to provide an optical disk capable of high-density recording using a wavelength-converted laser beam or the like.

[0005]

According to the present invention, there is provided a step of applying a positive resist on the surface of a master having a smooth surface, a photobleachable resin on the resist, and a light sensitive to the resist. A step of forming a resin layer containing a transparent and water-soluble resin, and a step of exposing and developing the resist to form a desired pattern. The water-soluble resin contains polyvinyl alcohol or polyvinylpyrrolidone. The water-soluble resin contains a nitrone or diazonium salt. The method further comprises a step of molding a stamper for an optical recording medium manufactured by the method for manufacturing a stamper for an optical recording medium as a mold.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram for producing the optical recording medium of the present invention. 1 is a glass master, 2 is a positive resist layer, 3
Is a water-soluble resin layer mixed with a photobleachable resin, which must be transparent at the photosensitive wavelength of the second resist. 4 is an exposed portion, 5 is a pattern, 6 is a nickel film,
7 is a nickel layer, 8 is a stamper, 9 is an amorphous polyolefin substrate, and 10 is a recording layer.

(1) The surface of the glass master is cleaned and hexamethyldisilazane is used to improve the adhesion to the resist. Next, a positive resist 2 is applied, and the solvent of the resist is removed by post-baking. Then, a mixture of a water-soluble resin and a photobleachable resin which are transparent at the photosensitive wavelength of the resist 3 is dissolved in water, applied and dried. Suitable examples of the water-soluble resin used herein include those which are water-soluble, such as polyvinyl alcohol and polyvinyl pyrrolidone, and do not have extra absorption at the photosensitive wavelength of the resist. In this case, the second resist layer and the third water-soluble resin layer must not adhere to each other. Therefore, before applying the third water-soluble resin, the second resist layer and the third water-soluble resin layer must be adhered to each other. The surface may be treated with a silane coupling agent or the like. The number average molecular weight of the water-soluble resin is preferably about 1,000 to 100,000 in consideration of workability, miscibility with the photobleachable resin, and the like. As the water-soluble resin (3), those containing an amine group, an amide group, a carboxyl group, and an OH group are not preferred, and hinder proper development of the resist. Therefore, it is necessary to select a solvent which does not contain a large number of these groups having a large polarity, and use a solvent having a weak polarity such as dioxane or ether. In addition, as an example of the photobleachable resin, a mixture of a water-soluble resin and a nitrone or diazonium salt exhibiting a clear photobleachability at the photosensitive wavelength of a laser may be selected.

Next, the portion 4 is exposed using a helium cadmium laser and developed to form a pattern 5. Although the development depends on the alkaline solution, it is more preferable to first remove the resin layer obtained by washing with water and mixing a water-soluble resin which is transparent at the photosensitive wavelength of the resist 3 and a photobleachable resin. Thereafter, a nickel film of 6 is formed by vacuum film formation to 100
A 0 angstrom film is formed, and a nickel layer of 0.3 mm is electroformed by using the film-formed portion as an electrode. Before forming the nickel film of No. 6, in order to clean the surface of the stamper, a film having a small grain size when vacuum film forming such as platinum or a platinum alloy may be formed. Then, the inner and outer diameters are processed by peeling from the one glass master and 8
Forming a stamper. Then, the substrate 9 is formed from the amorphous polyolefin using the stamper 8. This 9
The substrate may be formed by injection compression molding using a polycarbonate resin. Further, an optical disk is formed by forming 10 recording layers on 9 substrates. As the recording layer in this case, a magneto-optical recording film made of an alloy of a rare earth metal and a transition metal, an optical phase change type by a mixture of tellurium and tellurium oxide,
Alternatively, various substances such as cyanine can be used.

Next, the second resist will be described. 2
The positive resist layer is prepared by dissolving naphthoquinonediazide and phenol novolak resin in cellosolve acetate, and preferably has high sensitivity to light used for exposure. That is, a high sensitivity helium cadmium laser is used. 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 2
Is less than. The development is carried out with an alkaline solution, but sodium silicate, sodium quaternary alkyl ammonium hydroxide or the like is used. It is also possible to use an organic buffer containing no alkali metal or an alkali buffer comprising a weak acid and a strong base.

Further, it is preferable 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 that has little effect on development and has good compatibility with alkali. Among the anionic surfactants, the molecular weights are compared in consideration of compatibility with the developer and stability. It is desirable to use a material that is large and has high permeability and is stable. 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 and the like.

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

First, as shown in this embodiment, exposure is performed by using a laser cutting machine so that the track pitch and the pit pitch are reduced to half those of the prior art. Conventionally, the track pitch was 1.6 micrometers, which is reduced to 0.8 micrometers. Similarly, the interval of the pit row is halved. Then, development is performed, and a substrate is manufactured by the method described in this embodiment. Observation of the resulting substrate with a scanning electron microscope confirmed that grooves and pit rows having a width of 0.2 μm could be formed. Using the substrate, using an optical disc on which a multilayer film made of platinum and cobalt is formed as a recording layer,
830nm wavelength laser with SHG element 4
When recording and reproduction were performed with an optical system having a wavelength of 15 nanometers, it was possible to achieve a density four times higher than in the past.

The present invention should not be considered to be limited to these embodiments, and various changes can be made without departing from the gist of the present invention.

[0014]

As described above, according to the present invention, grooves and pits narrower than grooves and pits corresponding to the wavelength of a helium cadmium laser, which have not been conventionally possible, are formed.
This has the effect of providing an optical recording medium capable of high-density recording using laser light or the like having a shorter wavelength using an HG element. In addition, a conventionally used laser cutting device using a helium cadmium laser can be used as it is.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass master 2 Positive resist layer 3 Layer which mixed water-soluble resin and photobleachable resin 4 Exposure part 5 Pattern 6 Nickel film 7 Nickel layer 8 Stamper 9 Amorphous polyolefin substrate 10 Recording layer

Claims (4)

(57) [Claims] A step of applying a positive resist on the surface of a master having a smooth surface; a photobleachable resin on the resist; and a water-soluble resin transparent to light to which the resist is exposed. And forming a desired pattern by exposing and developing the resist to form a desired pattern. 2. The method for manufacturing a stamper for an optical recording medium according to claim 1, wherein the water-soluble resin contains polyvinyl alcohol or polyvinyl pyrrolidone. 3. The method for manufacturing a stamper for an optical recording medium according to claim 1, wherein the water-soluble resin contains a nitrone or diazonium salt. 4. A method of manufacturing an optical recording medium, comprising a step of molding a stamper for an optical recording medium manufactured by the method of manufacturing a stamper for an optical recording medium according to claim 1.