JP2001143331A - Master disk for optical disk and method for manufacturing master stamper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the disturbance in the edges of grooves formed at a photoresist by interference of light used for exposure when the photoresist on a substrate having a high reflectivity, such as a silicon substrate, is exposed and to prevent the consequent increase of noise. SOLUTION: The master disk for optical disk is obtained by forming an oxidized film 2 of a specified thickness (d) on a silicon substrate surface 1, forming a metallic film 3 on the oxidized film, forming a photoresist film 4 of a thickness of nearly λ/(2×n) on the metallic film, exposing and developing the photoresist film to form desired photoresist patterns, then etching the metallic film of the portions where there are no photoresist films to form patterns, and anisotropically etching the oxidized film with the metallic film formed with the patterns as a mask, thereby removing the metallic film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing an optical disk master and a method for manufacturing a master stamper.

[0002]

2. Description of the Related Art Generally, an optical information recording medium such as an optical disk is manufactured by preparing a master stamper, a mother, and a stamper from a master disc and duplicating a large amount by injection molding. In some cases, a stamper is made directly from the master.

As shown in FIG. 6, a master optical disk is coated with a photoresist film 9 on a glass substrate 8 whose surface is polished (a), and is exposed using a laser beam whose intensity is modulated by an information signal to be recorded. (B), developing to form signal pits or grooves or signal pits and grooves corresponding to the photosensitivity (c). Hereinafter, the signal pits or grooves or the signal pits and grooves are collectively referred to as a desired pattern.

A conductive film 6 of nickel or the like is formed on the surface of the photoresist master 10 by a method such as sputtering (d), nickel is electroformed on the conductive film (e), and nickel is peeled off from the master to form a master. The stamper 7 is manufactured (f).

[0005]

There is an increasing demand for increasing the recording density of optical discs and for recording larger amounts of information. When a high-density optical information medium is manufactured, a method of recording a signal between grooves and between grooves has been proposed (for example, Japanese Patent Application Laid-Open No. 5-282705).

In this case, since signals cannot be recorded on the groove slope, it is necessary to increase the edge inclination angle of the groove and reduce the area of the edge portion.

When a pattern is formed by using a photoresist, the amount of exposure changes continuously between the pattern portion and the surrounding portion, so that the remaining film amount during development also changes continuously around the pit. The groove edge is rounded. Further, the inclination angle of the edge is determined by the performance of the photoresist. However, a photoresist capable of achieving an inclination angle larger than a certain level is not commercially available, and it is difficult to reduce the area of the edge portion.

When a photoresist on a substrate having high reflectivity such as a silicon substrate is exposed, light used for exposure is reflected on the surface of the substrate and interferes with incident light to form an edge of a groove formed in the photoresist. Is disturbed. Even when etching is performed using a photoresist as a mask, the edge of the groove of the master is disturbed due to the disorder of the edge of the resist. The disorder of the edge of the groove increases the noise of the medium when an optical information recording medium is manufactured based on this master.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a low-noise, high-density information medium which solves the above-mentioned problems, reduces the area of the groove edge portion, and eliminates the disturbance of the groove edge. It was done.

[0010]

According to the present invention, in order to solve the above-mentioned problems, an oxide film having a constant thickness is formed on a silicon substrate surface, a metal film is formed on the oxide film, and a metal film is formed on the metal film. Forming a photoresist film having a thickness of approximately λ / (2 × n);
After exposing and developing to form a desired photoresist pattern, etching the metal film in a portion having no photoresist film to form a pattern, and then using the metal film on which the pattern is formed as a mask to form an anisotropic oxide film. Etching
This is achieved by removing the metal film.

Further, an oxide film having a constant thickness d is formed on the surface of the silicon substrate, and (m × λ / 2−N ×
d) / n (m is a minimum positive integer satisfying m × λ / 2> N × d) and a photoresist film having a thickness satisfying m × λ / 2> d × (N + n / R). This is achieved by forming, exposing and developing a desired photoresist pattern, and then performing anisotropic etching of the oxide film in a portion having no photoresist film to remove the photoresist.

[0012] Further, the silicon substrate surface has a constant thickness d such that the oxide film thickness and the acrylic film thickness have a relationship of N × d + N ′ × D = m ′ × λ / 2 (m ′ is a positive integer). An oxide film is formed, an acrylic film having a constant thickness D is formed on the surface of the oxide film, a photoresist film having a thickness of approximately λ / 2 × n is formed on the acrylic film, and exposed and developed to a desired thickness. After forming a photoresist pattern, a pattern is formed by etching the acrylic film in a portion without a photoresist film,
Achieved by removing the photoresist.

[0013]

(Embodiment 1) FIG. 1 is a view for explaining a method of manufacturing a master stamper according to Embodiment 1 of the present invention.

An oxide film 2 having a constant thickness d is formed on a silicon substrate 1.
Is formed, and a metal film 3 is formed on the oxide film. On the metal film 3, when a wavelength used for exposure is λ and a refractive index of the photoresist at the wavelength is n, approximately λ / ( 2x
n) and a photoresist is applied by a method such as spin coating to form a photoresist film 4 (a).
Exposure (b) and development are performed to form a desired photoresist pattern (c). The metal film 3 is carved by anisotropic etching using a photoresist as a mask (d), the oxide film 2 is carved by anisotropic etching using a metal film as a mask (e), and the photoresist and the metal film are removed (f). ). The substrate with the desired pattern formed in this way is referred to as master 5.

A conductive film 6 is formed on the master 5 by a method such as sputtering (g), and electroforming is performed using the conductive film 6 as an electrode to form a metal layer of nickel or the like having a thickness of several hundred μm ( h). The master stamper 7 is made by peeling off the portion composed of the conductive film and the metal layer from the substrate and cleaning the surface (i).

An optical information recording medium such as an optical disk is generally manufactured by preparing a mother and a stamper from the master stamper and copying a large amount by injection molding. In some cases, a master stamper is used directly as a stamper, and is mass-produced by injection molding.

As the silicon substrate, a commercially available silicon substrate can be used as it is. In addition, there is no problem even if used after washing.

As a method for oxidizing the surface of the silicon substrate to a certain depth, thermal oxidation is preferable. Thermal oxidation using an oxidation furnace is usually often used in a silicon process, and can oxidize a large number of silicon substrates simultaneously at a constant depth with good reproducibility.

The thickness of the oxide film becomes the desired pattern depth. In the case of recording a signal between the grooves, the thickness of the oxide film is approximately 69 nm when the reproduction wavelength of the optical disk is 650 nm and the refractive index of the optical disk substrate is 1.58.
Is used.

As the metal film, for example, aluminum can be used. What is necessary is just to form by a sputtering method over the board | substrate with which the oxide film was formed. The thickness of the metal film may be greater than a value that can reflect light and is larger than a value obtained by dividing the thickness of the oxide film by the ratio of the etch rate of the oxide film to the etch rate of the metal film when etching the oxide film. Aluminum is desirable because it easily forms a smooth film and can be easily removed by oxidation.

When a photoresist film is formed on a substrate having a high reflectance such as a metal film, when light for exposure is incident on the substrate, the light is reflected on the surface of the metal film, and the reflected light and the incident light interfere with each other. If the thickness of the photoresist is such that the light intensifies on the photoresist surface, the photoresist surface is easily roughened by development, and the edge of the pattern is also roughened. On the other hand, if the photoresist film is formed with a thickness of approximately λ / (2 × n), light is weakened on the photoresist surface, so that the photoresist surface after development is not roughened, and the edge of the pattern can be made smooth. .

By engraving the metal film by anisotropic etching using a photoresist pattern whose surface is not rough and the pattern edge is smooth as a mask, a metal film pattern without disturbance of the groove edge can be formed.

When the oxide film is engraved by anisotropic etching using a metal film having a smooth pattern edge as a mask, the groove edge is not disturbed, the groove edge is not rounded, and the inclination angle of the groove edge is increased. An optical disc master having a small area can be manufactured.

By producing a stamper based on this master and producing an optical information recording medium using the stamper, a low-noise, high-density information medium can be produced.

At a film thickness near λ / (2 × n), the intensity of light due to interference is not abrupt, so that even at a film thickness strictly corresponding to 波長 wavelength, the surface is not roughened and the pattern edge can be made smooth. Characteristic can be obtained.

Reactive ion etching (RIE) or inductively coupled plasma etching (ICP) can be used for etching the metal film and the oxide film.

The metal film after the etching can be removed by using, for example, an acid such as hydrochloric acid, nitric acid or sulfuric acid.

It is desirable that the metal film is removed by using an acid, because the exposed portion of the silicon substrate under the oxide film by pattern formation can be simultaneously oxidized.

Since silicon is hardly etched under the conditions for etching the silicon oxide film, the depth of the engraved pattern is determined by the thickness of the oxide film. If the thickness of the oxide film is kept uniform and constant, the depth of the formed pattern can be kept uniform and constant, and the master can be stably mass-produced.

The master 5 manufactured by engraving an oxide film is
The surface and periphery of the pattern are made of an oxide film, while the bottom of the pattern is made of silicon covered with an extremely thin natural oxide film. If a nickel conductive film is formed by a sputtering method in this state, nickel can penetrate the ultra-thin natural oxide film by the energy of the sputtering, and the nickel and silicon are chemically bonded to each other to be strongly bonded, so that the master and the master stamper cannot be separated. Master stamper cannot be manufactured. If the area of the pattern is small, the master and the master stamper can be separated, but nickel at the bottom of the pattern may partially remain on the master and the bottom of the pattern may be roughened.

When the conductive film is formed after oxidizing the surface of the master produced by engraving the oxide film, an oxide film 2 is also formed at the bottom of the pattern, and nickel is not bonded to silicon. Can be peeled off. Further, it is possible to manufacture a high-density information medium in which the bottom of the pattern is not roughened and the noise is small.

When the depth of the desired pattern is thinner than a certain level, the thickness of the oxide film is λ / (2 × 2) where λ is the wavelength used for exposure and N is the refractive index of the oxide film at that wavelength.
N) In some cases, it may be less. In this case, when light for exposure is incident, the light is reflected on the substrate surface and interferes with the reflected light and the incident light, and the light is weakened at a portion where the optical distance from the substrate surface is λ / 2. Is smaller than λ / (2 × N), FIG.
As shown in (a), the first weakening portion is formed not in the oxide film but in the photoresist film thereon.

If the thickness of the photoresist film is not thicker than the value obtained by dividing the oxide film thickness by the etch rate ratio between the photoresist and the oxide film, a pattern cannot be carved in the photoresist film. Therefore, the oxide film thickness is λ / (2 × N)
If the thickness is slightly smaller, there may be a case where two light portions are weakened on the surface and inside of the photoresist film. In this case, the photoresist film thickness is approximately (m × λ / 2−N ×
d) / n (m is the smallest positive integer that satisfies m × λ / 2> N × d) and m × λ / 2 <d × (N + n / R).

When a portion where two lights weaken each other is formed on the surface and inside of the photoresist film, a two-step groove is formed as shown in FIG. Pattern cannot be formed.

As described above, in the method of applying a photoresist on an oxide film, a good pattern cannot be formed depending on the thickness of the oxide film. According to the method, an oxide film having an arbitrary thickness can be formed without any roughness and a pattern with a steep edge can be formed, and a high-density information medium with less noise can be manufactured.

(Embodiment 2) FIG. 3 is a diagram illustrating a method of manufacturing a master stamper according to Embodiment 2 of the present invention.

When the wavelength used for exposure is λ and the refractive index of the oxide film at that wavelength is N, the refractive index of the photoresist is n, an oxide film 2 having a thickness d is formed on the surface of the silicon substrate 1. Almost (m × λ / 2−N × d) / n on the oxide film
The photoresist film 11 is applied to a thickness of (m is the smallest positive integer satisfying m × λ / 2> N × d) by a method such as spin coating (a), exposed (b), and developed (b). A desired photoresist pattern is formed (c). Using the photoresist as a mask, the oxide film 2 is engraved by anisotropic etching (d), and the photoresist remaining after the etching is removed to produce the master 12 (e).

The conductive film 6 is formed on the master 12 (f), and electroforming is performed using the conductive film 6 as an electrode to form a metal layer of nickel or the like having a thickness of several hundred μm (g). A portion composed of the conductive film and the metal layer is peeled off from the substrate and the surface is washed to form a master stamper 7 (h).

When an oxide film is formed on a substrate having a high reflectivity such as a silicon substrate and a photoresist film is formed thereon, the silicon oxide film is transparent. The reflected light and the incident light interfere with each other in the silicon oxide film and the photoresist film.

When the thickness of the photoresist is such that light is strengthened on the surface of the photoresist, the surface of the photoresist is easily roughened by development, and the edge of the pattern is also roughened. On the other hand, the photoresist film is almost (m × λ /
When formed with a thickness of 2-N × d) / n (m is a minimum positive integer satisfying m × λ / 2> N × d), light is weakened on the photoresist surface, and thus the photo resist after development is formed. The edge of the pattern can be made smooth without the resist surface being roughened.

If the thickness of the photoresist film is not larger than the value obtained by dividing the thickness of the oxide film by the etch rate ratio between the photoresist and the oxide film, a pattern cannot be carved in the photoresist film.

Assuming that the etch rate ratio is R, the photoresist film thickness must be greater than d / R. If the photoresist film thickness is smaller than d / R, the photoresist film will not be etched during the etching of the oxide film, and the entire oxide film will only be etched. The film cannot be carved.

As in the present embodiment, the thickness of the photoresist is substantially (m × λ / 2−N × d) / n and m × λ
/ 2> d × (N + n / R), the photoresist surface is not roughened, the edges of the pattern are smooth, and the photoresist film thickness is d during etching.
Since the thickness is larger than / R, the pattern can be carved to the bottom of the oxide film, and a desired pattern depth can be obtained.

When the substrate is engraved by anisotropic etching using a photoresist pattern whose surface is not rough and the pattern edge is smooth as a mask, the groove edge is not disturbed, the groove edge is not rounded, and the groove is not rounded. Since the inclination angle of the edge is increased and the area of the edge portion can be reduced, a high-density information medium with low noise can be manufactured.

Since the silicon is hardly etched under the conditions for etching the silicon oxide film, the depth of the engraved pattern is determined by the thickness of the oxide film. If the thickness of the oxide film is kept uniform and constant, the depth of the formed pattern can be kept uniform and constant, and the master can be stably mass-produced.

Master 12 manufactured by engraving an oxide film
Although the surface and periphery of the pattern are made of an oxide film, the bottom of the pattern is made of silicon covered with an extremely thin natural oxide film.

When a nickel conductive film is formed by a sputtering method in this state, nickel penetrates an extremely thin natural oxide film by the energy of sputtering, and nickel and silicon are chemically bonded to each other to form a strong bond, thereby separating the master and the master stamper. And the master stamper cannot be manufactured. If the area of the pattern is small, the master and the master stamper can be separated, but nickel at the bottom of the pattern may partially remain on the master and the bottom of the pattern may be roughened.

When the conductive film is formed after oxidizing the surface of the master manufactured by engraving the oxide film, an oxide film is also formed at the bottom of the pattern, and nickel is not bonded to silicon. It can be peeled off. Further, it is possible to manufacture a high-density information medium in which the bottom of the pattern is not roughened and the noise is small.

(Embodiment 3) FIG. 4 is a diagram illustrating a method of manufacturing a master stamper according to Embodiment 3 of the present invention.

An acrylic film 14 having a constant thickness is formed on a substrate 13, and a photoresist film 1 is formed on the acrylic film 14.
5 is applied by a method such as spin coating (a), exposed (b), and developed to form a desired photoresist pattern (c). The acrylic film 14 is engraved by anisotropic etching using the photoresist as a mask (d), and the photoresist is removed using a solvent (e). The substrate having the desired pattern formed in this way is called an acrylic master 16.

A conductive film 17 is formed on the acrylic master 16 by electroless plating (fg), and electroforming is performed using the conductive film 17 as an electrode to form a metal layer of nickel or the like having a thickness of several hundred μm ( g). A portion composed of the conductive film and the metal layer is peeled off from the substrate and the surface is washed to form a master stamper 18 (h).

As the master, a substrate in which silicon is formed on a substrate such as glass in addition to a silicon substrate can be used.

As the acrylic, a commercially available thermosetting acrylic, for example, Optmer LC792 manufactured by JSR Corporation can be used. An acrylic film can be formed by applying an optomer to a substrate by spin coating, baking, drying and curing.

When a nickel conductive film is formed by a sputtering method as is usually performed on a master having a pattern formed on an acrylic resin, nickel is strongly bonded to the acrylic resin by the energy of sputtering, and the stamper is peeled off after electroforming. The master stamper cannot be manufactured.

When a nickel conductive film is formed by the electroless plating method, since the nickel does not have high energy at the time of plating, the acrylic and the conductive film are not bonded, and the stamper can be peeled off after the electroforming. A master stamper can be manufactured.

(Embodiment 4) FIG. 5 is a diagram illustrating a method of manufacturing a master stamper according to Embodiment 4 of the present invention.

When the wavelength used for exposure is λ, the refractive index of the oxide film at that wavelength is N, and the refractive index of acrylic is N ′,
The oxide film thickness and the acrylic film thickness are N × d + N ′ × D = m ′ ×
An oxide film 20 having a constant thickness d is formed on the surface of the silicon substrate 19 so as to have a relationship of λ / 2 (m ′ is a positive integer), and an acrylic film 21 having a constant thickness d ′ is formed on the surface of the oxide film 20. A photoresist film 22 having a thickness of approximately λ / 2 × n is applied on the acrylic film 21 by a method such as a spin coating method, where n is the refractive index of the photoresist at that wavelength (a). ), Exposure (b) and development to form a desired photoresist pattern (c). The acrylic film 21 is engraved by anisotropic etching using the photoresist as a mask (d), and the photoresist is removed using a solvent (e). The substrate having the desired pattern formed in this way is called an acrylic master 23.

A conductive film 17 is formed on the acrylic master 23 by electroless plating (f), and electroforming is performed using the conductive film 17 as an electrode to form a metal layer of nickel or the like having a thickness of several hundred μm ( g). A portion composed of the conductive film and the metal layer is peeled off from the substrate and the surface is washed to form a master stamper 18 (h).

When an oxide film is formed on a substrate having high reflectivity such as a silicon substrate and an acrylic film and a photoresist film are formed thereon, the silicon oxide film and the acrylic film are transparent, so that light for exposure is incident. Sometimes, the light is reflected on the silicon surface, and the reflected light and the incident light interfere in the silicon oxide film, the acrylic film, and the photoresist film.

When the thickness of the photoresist is such that the light intensifies on the surface of the photoresist, the surface of the photoresist is easily roughened by development, and the edge of the pattern is also roughened. On the other hand, since the light is weakened on the photoresist surface, the photoresist surface after development is not roughened, and the edge of the pattern can be made smooth.

The thickness of the oxide film and the thickness of the acrylic film are set to N × d + N ′.
When the relation of × D = m ′ × λ / 2 (m ′ is a positive integer) is satisfied, light for exposure is weakened on the acrylic film surface.
When a photoresist is applied thereon with a thickness of approximately λ / 2 × n, light for exposure is weakened on the photoresist surface,
A photoresist pattern with a smooth edge can be obtained.

When the acrylic film is engraved by anisotropic etching using a photoresist pattern whose photoresist surface is not rough and pattern edges are smooth as a mask, the groove edges are not disturbed, and the groove edges are not rounded. The inclination angle of the groove edge becomes large, so that an optical disk master having a small edge area can be manufactured.

By producing a stamper based on this master and producing an optical information recording medium using the stamper, a low-noise, high-density information medium can be produced.

[0064]

The method for manufacturing an optical disk master according to the present invention comprises:
An oxide film having a constant thickness d is formed on the surface of the silicon substrate, a metal film is formed on the oxide film, and approximately λ /
After a photoresist film having a thickness of (2 × n) is formed and exposed and developed to form a desired photoresist pattern, a pattern is formed by etching a portion of the metal film where there is no photoresist film, and This is achieved by anisotropically etching the oxide film using the patterned metal film as a mask and removing the metal film.

In the light for exposure, the metal is reflected on the surface and interferes in the photoresist film. Photoresist film thickness almost 1
Since the wavelength is set to / 2, the light is weakened on the photoresist surface, and the edge disturbance of the photoresist pattern after development is reduced.

When a metal is carved by anisotropic etching using a photoresist pattern whose surface is not rough and the pattern edge is smooth as a mask, a metal pattern free from disturbance of groove edges can be formed. When the oxide film is anisotropically etched using the metal pattern having no edge disturbance as a mask, the groove edge is not disturbed, the groove edge is not rounded, and the inclination angle of the groove edge is increased. A small optical disc master can be manufactured.

By manufacturing a stamper based on this master and manufacturing an optical information recording medium using the stamper, a low-noise, high-density information medium can be manufactured.

[Brief description of the drawings]

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

FIG. 2 is a schematic view of a photoresist pattern formed on a high-reflectance master.

FIG. 3 is a diagram illustrating a manufacturing process of an optical disc master and a master stamper according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a manufacturing process of an optical disc master and a master stamper according to a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a manufacturing process of an optical disc master and a master stamper according to a fourth embodiment of the present invention.

FIG. 6 is a view for explaining an example of a manufacturing process of a conventional optical disc master and a master stamper.

[Explanation of symbols]

 Reference Signs List 1,19 silicon substrate 2,20 oxide film 3 metal film 4,9,11,15,22 photoresist film 5,12 master 6,17 conductive film 7,18 master stamper 8 glass substrate 10 photoresist master 13 substrate 14, DESCRIPTION OF SYMBOLS 21 Acrylic film 16, 23 Acrylic master 24 Oxide film of λ / 2N thickness 25 Photoresist film of λ / 2n thickness 26 Oxide film thinner than λ / 2N 27 Photoresist film thicker than λ / 2n

Claims (12)

[Claims] An oxide film having a predetermined thickness d is formed on a surface of a silicon substrate, a metal film is formed on the oxide film, a photoresist film is formed on the metal film, and exposed and developed to form a desired photo-resist. After forming a resist pattern, after etching the metal film in a portion without a photoresist film to form a pattern, anisotropically etching the oxide film using the metal film on which the pattern is formed as a mask, A method of manufacturing an optical disk master to be removed, wherein a thickness of a photoresist is approximately λ / (2 × n), where λ is a wavelength used for exposure and a refractive index of the photoresist at the wavelength is n. A method for manufacturing a master optical disc, comprising: 2. An oxide film having a constant thickness d is formed on the surface of a silicon substrate, a metal film is formed on the oxide film, and the wavelength used for exposure on the metal film is λ, and the photo- Assuming that the refractive index of the resist is n, a photoresist film having a thickness of approximately λ / (2 × n) is formed, and is exposed and developed to form a desired photoresist pattern. An optical disc master manufactured by etching a film to form a pattern, anisotropically etching an oxide film using the metal film on which the pattern is formed as a mask, and removing the metal film. 3. An oxide film having a predetermined thickness d is formed on the surface of the silicon substrate, a metal film is formed on the oxide film, a photoresist film is formed on the metal film, and exposed and developed to form a desired photo-resist. After a resist pattern is formed, a pattern is formed by etching the metal film in a portion where there is no photoresist film, and then the oxide film is anisotropically etched using the metal film on which the pattern is formed as a mask to form a metal film. A method for manufacturing a master optical disc to be removed, wherein λ is the wavelength used for exposure, N is the refractive index of the oxide film at that wavelength, n is the refractive index of the photoresist, and the etch rate ratio between the photoresist and the oxide film. Is R, m × λ / 2 <d × (N + n
2. The method according to claim 1, wherein the relationship of / R) is satisfied. 4. An oxide film having a constant thickness d is formed on the surface of the silicon substrate, a photoresist film is formed on the oxide film, and exposed and developed to form a desired photoresist pattern. A method for manufacturing an optical disc master, wherein anisotropic etching is performed on an oxide film in a non-existent portion and a photoresist is removed, wherein a wavelength used for exposure is λ, a refractive index of the oxide film at the wavelength N, and a refractive index of the photoresist. When the rate is n and the etch rate ratio between the photoresist and the oxide film is R, the oxide film thickness is λ / (2 × N) or more, and the photoresist film thickness is almost (m × λ / 2−N × d) / n
(M is a minimum positive integer that satisfies m × λ / 2> N × d), and m × λ / 2> d × (N + n / R) Master disc manufacturing method. 5. The method according to claim 1, wherein an oxide film is formed on the silicon substrate by thermal oxidation. 6. A desired photoresist is formed by forming an oxide film having a constant thickness on the surface of a silicon substrate, forming a metal film on the oxide film, forming a photoresist film on the metal film, exposing and developing. After the pattern is formed, the metal film in the portion without the photoresist film is etched to form the pattern, and then the oxide film is anisotropically etched using the metal film on which the pattern is formed as a mask to remove the metal film. And forming a conductive film after oxidizing the surface, followed by electroforming. 7. The method according to claim 1, wherein the metal film is removed using an acid. 8. An acrylic film having a predetermined thickness is formed on the surface of a silicon substrate, a photoresist film is formed on the acrylic film, and a desired photoresist pattern is formed by exposure and development. Forming a pattern by etching the acrylic film, removing a photoresist, forming a conductive film by electroless plating, and electroforming. 9. An acrylic film having a predetermined thickness is formed on the surface of a silicon substrate, a photoresist film is formed on the acrylic film, and a desired photoresist pattern is formed by exposure and development. Forming a pattern by etching the acrylic film, removing a photoresist, forming a conductive film by electroless plating, and electroforming. 10. An oxide film having a certain thickness d is formed on the surface of the silicon substrate, an acrylic film having a certain thickness D is formed on the surface of the oxide film, and a photoresist film is formed on the acrylic film. Forming a desired photoresist pattern, and then etching the acrylic film in a portion having no photoresist film to form a pattern, and removing the photoresist, wherein the wavelength used for exposure is Is λ, the refractive index of the oxide film at that wavelength is N, the refractive index of the acrylic is N ′, and the refractive index of the photoresist is n, and the oxide film thickness and the acrylic film thickness are N × d + N ′ × D.
= M ′ × λ / 2 (m ′ is a positive integer), and the photoresist film thickness is approximately λ / 2 × n. 11. An oxide film having a certain thickness d is formed on the surface of the silicon substrate, an acrylic film having a certain thickness D is formed on the surface of the oxide film, and a photoresist film is formed on the acrylic film. After forming the desired photoresist pattern, the acrylic film in the portion without the photoresist film is etched to form a pattern, and the photoresist is removed. Assuming that λ, the refractive index of the oxide film at that wavelength N, the refractive index of the acrylic is N ′, and the refractive index of the photoresist is n, the oxide film thickness and the acrylic film thickness are N × d + N ′ × D =
An optical disc master having a relationship of m ′ × λ / 2 (m ′ is a positive integer) and a photoresist film thickness of approximately λ / 2 × n. 12. The method according to claim 1, wherein aluminum is used as the metal film.