JPH08221808A - Production of optical master disk - Google Patents

Abstract

PURPOSE: To obtain a process for production which improves the quality and productivity of an optical master disk. CONSTITUTION: A first photoresist layer 10, an intermediate layer 11 and a second photoresist layer 12 are formed on a substrate 9. Latent images of pregrooves 16 are formed thereon by a laser beam 14 of low intensity and latent images of prepits 15 are formed by a laser beam 13 of high intensity. At this time, the latent images are formed on the first photoresist layer 10 while evaporating the second photoresist layer 12 and the intermediate layer 11 by the laser beam 13 of the high intensity, thereby the need for removing the intermediate layer 11 by an alkaline soln. and acid soln is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical disc master having prepits and pregrooves having different depths.

[0002]

2. Description of the Related Art At present, an optical disk for reading recorded data by laser light is used as a high density recording medium. There are various types of optical discs, but there is an optical disc in which a pre-groove serving as a guide groove and a pre-pit serving as recording data are formed with different depths.

For example, if the wavelength of the laser beam for reading the recorded data is λ and the refractive index of the protective film that seals the prepits and pregrooves of the optical disc is n, the prepits are
The depth of λ / 4n is formed to maximize the contrast of the reflected light of the laser light for reading the recorded data, and the pre-groove is formed to the depth of λ / 2n to maximize the light intensity of the tracking error. .

Here, a method for manufacturing an optical disk master is shown in FIG.
It will be described below based on. First, a photoresist layer is applied onto the glass substrate 1 by a spin coating method and heated in a clean oven (not shown) to form a photoresist layer on the glass substrate 1 as shown in FIG. 8A. Form 2. Next, as shown in FIG. 8B, the high-intensity laser beam 3 is applied to the photoresist layer 2.
To form a latent image of the pre-pit, and by exposing the laser beam 4 of low intensity to form a latent image of the pre-groove, the exposed photoresist layer 2 is developed with an alkaline solution to expose the exposed portion. By removing
As shown in FIG. 8C, an optical disc master 7 having prepits 5 and pregrooves 6 formed at different depths is obtained.

In the method of manufacturing the optical disc master 7, the depths of the prepits 5 and the pregrooves 6 are made different depending on the intensities of the laser beams 3 and 4. Specifically, the intensity of the low-intensity laser light 4 is 40 to 40 times that of the high-intensity laser light 5.
It is set to 60 (%).

However, as shown in FIG. 9, the exposure depth of the photoresist layer 2 increases with the light intensity of the laser beams 3 and 4. Therefore, the depth of the pre-pit 5 can be accurately controlled as the thickness of the photoresist layer 2.
The depth of the pre-groove 6 varies depending on the intensity of the laser beam 4 and the sensitivity error of the photoresist layer 2.

In order to solve such a problem, a low-sensitivity photoresist layer and a high-sensitivity photoresist layer are sequentially laminated on a glass substrate, and the depth of the pre-groove depends on the thickness of the upper photoresist layer. It is proposed to manage. However, in this case, two photoresist layers having the same solvent are applied in an overlapping manner, so that the two photoresist layers are mixed at the interface and the thickness of the upper photoresist layer is accurately adjusted. It becomes difficult to manage.

Therefore, Japanese Patent Laid-Open Nos. 1-125742 and 2
In the method for manufacturing an optical disk master disclosed in Japanese Patent Laid-Open No. 49230/1990, the intermediate layer is interposed between the two photoresist layers to prevent mixing of the two photoresist layers. In this case, it is necessary to remove the intermediate layer in order to develop and remove the lower photoresist layer.

Therefore, in the manufacturing method disclosed in JP-A-1-125742, the intermediate layer is a metal layer soluble in an alkaline solution, and the intermediate layer is also removed at the same time by an alkaline solution for developing the upper photoresist layer. To do. In addition, JP-A-2-492
In the production method disclosed in JP-A-30, the intermediate layer is a metal layer that is soluble in an acid solution, the upper photoresist layer is developed with an alkaline solution, and then the intermediate layer is removed with an acid solution to remove the lower photo layer. The resist layer is developed with an alkaline solution.

[0010]

In the above-described method for manufacturing an optical disk master, the depth of the pre-groove is accurately controlled by using two photoresist layers, and an intermediate layer is interposed between the two photoresist layers. By doing so, the mixing of the photoresist layer is prevented.

In this case, according to the manufacturing method disclosed in Japanese Patent Application Laid-Open No. 1-125742, since the intermediate layer is also removed by the alkaline solution for developing the photoresist layer, there is no concern that the manufacturing process or the used solution will increase. However, it is necessary to lengthen the time for immersing the photoresist layer in the alkaline solution, and the corrosion of the alkaline solution impairs the smoothness of the surface of the upper photoresist layer.

Further, in the manufacturing method disclosed in Japanese Patent Laid-Open No. 2-49230, since the intermediate layer is removed by an acid solution that does not corrode the photoresist layer, the degree to which the smoothness of the surface of the upper photoresist layer is impaired. Is few. However, since it is necessary to sequentially perform development of the upper photoresist layer with an alkaline solution, removal of the intermediate layer with an acid solution, and development of the lower photoresist layer with an alkaline solution, the manufacturing process and the solution used. Will increase and productivity will decrease.

[0013]

According to the first aspect of the present invention,
A first photoresist layer, an intermediate layer, and a second photoresist layer are sequentially formed on a substrate to form a prepit latent image by exposure to high-intensity laser light and exposure to low-intensity laser light. The latent image of the pre-groove is formed by, and the exposed first and second photoresist layers are developed to obtain an optical disc master. When the latent image of 1 is formed, the latent image is formed on the first photoresist layer while evaporating the second photoresist layer and the intermediate layer.

According to a second aspect of the invention, in the first aspect of the invention, the second photoresist layer is pre-developed before the exposure by the laser beam is performed.

According to a third aspect of the invention, in the first aspect of the invention, the second photoresist layer is formed of a photoresist having a lower sensitivity than the first photoresist layer.

According to a fourth aspect of the present invention, in the first aspect of the invention, the first photoresist layer is formed after the reflective layer is formed on the substrate.

According to a fifth aspect of the invention, in the first aspect of the invention, the water-soluble resin layer is formed on the second photoresist layer before the exposure with the laser beam is performed.

[0018]

According to the first aspect of the invention, when the latent image of the prepit is formed by the exposure of the high intensity laser beam, the latent image is formed on the first photoresist layer while evaporating the second photoresist layer and the intermediate layer. Since the image is formed, prepits are formed from the second photoresist layer to the first photoresist layer without removing the intermediate layer with an alkaline solution or an acid solution.

According to the second aspect of the present invention, since the second photoresist layer is pre-developed before the exposure with the laser beam is performed, the developing rate of the second photoresist layer is lowered, and the second photoresist layer is reduced. The expansion of the pre-pit openings formed from the layer to the first photoresist layer is reduced.

According to the third aspect of the present invention, the second photoresist layer is formed of a photoresist having lower sensitivity than the first photoresist layer, so that the exposure sensitivity of the second photoresist layer is lowered, The expansion of the opening of the pre-pit formed from the photoresist layer to the first photoresist layer is reduced.

According to the fourth aspect of the present invention, the first photoresist layer is formed after the reflective layer is formed on the substrate. Therefore, the exposure amount of the second photoresist layer does not increase and the first photoresist layer does not increase. The exposure amount of the resist layer increases, and the difference in groove width in the depth direction of the prepits formed from the second photoresist layer to the first photoresist layer decreases.

According to the fifth aspect of the present invention, since the water-soluble resin layer is formed on the second photoresist layer before the exposure with the laser beam, the second photoresist layer is not exposed excessively, The expansion of the openings of the pre-pits formed from the second photoresist layer to the first photoresist layer is reduced.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

First, in the method of manufacturing the optical disk master 8 of this embodiment, the glass substrate 9 which is a substrate is polished and then washed, and a photoresist (OFPR-800 manufactured by Tokyo Ohka Co., Ltd.) is formed on the surface of the glass substrate 9.
Etc.) is applied by a spin coating method. This glass substrate 9 is heated in a clean oven at 90 (° C.) for 30 minutes only, and the photoresist is dried.
As shown in (a), the first photoresist layer 10 is formed on the glass substrate 9. As shown in FIG. 1B, a metal film of "Ni" is formed on the surface of the first photoresist layer 10 by sputtering, for example, to a film thickness of 100 (Å) to form an intermediate layer 11. To do. Photoresist (OFPR-800 manufactured by Tokyo Ohka Co., Ltd.) is applied to the surface of the intermediate layer 11 by a spin coating method, and a 90
By heating at (℃) for 30 minutes and drying,
As shown in (c), the second photoresist layer 12 is formed.

Next, as shown in FIG. 1 (d), a high intensity laser beam 13 is exposed to form a latent image of pre-pits on the first photoresist layer 10 and a low intensity laser beam 14 is applied. A pregroove latent image is formed on the second photoresist layer 12 by exposure. At this time, the second photoresist layer 12 and the intermediate layer 11 are evaporated by exposing the first photoresist layer 10 with a high-intensity laser beam 13 that forms a latent image of prepits.

Then, the exposed first and second photoresist layers 10 and 12 are developed with an alkaline solution to remove the exposed portions, so that the pre-pits 15 are formed as shown in FIG. 1 (e). Thus, the optical disk master 8 having the pregroove 16 and the pregroove 16 formed at different depths is obtained. In this optical disk master 8, the depth of the pre-pit 15 is the film thickness of the first and second photoresist layers 10 and 12 and the intermediate layer 11, and the depth of the pre-groove 16 is the depth of the second photoresist layer 12. Film thickness. Therefore, the optical disc master 8
The depths of the pre-pits 15 and the pre-grooves 16 can be accurately controlled, and an optical disc (not shown) can be produced with high quality.

Further, in the method of manufacturing the optical disc master 8 of this embodiment, the second photoresist layer 12 is irradiated with the high-intensity laser beam 13 that exposes the prepits 15 as described above.
And the intermediate layer 11 are evaporated. Therefore, since it is not necessary to remove the intermediate layer 11 with the alkaline solution, the second photoresist layer 12 can be formed by developing the alkaline solution for a long time.
Since the smoothness of the surface is not impaired and there is no need to remove the intermediate layer 11 with an acid solution, there is no decrease in productivity due to an increase in the number of manufacturing processes or used solutions.

Further, in the method of manufacturing the optical disk master 8 of this embodiment, the prepits 15 and the pregrooves 16 are formed by the laser beams 13 and 14 having different intensities, but as shown in FIG. 2, the intermediate layer 11 is evaporated. There is a permissible range of "P _{1 to} P ₂ " for the intensity of the laser beam 13 to be caused, and even if the intensity of the laser beam 13 varies within this permissible range, the pregroove 16
Depth does not change from "d ₁ ". Therefore, the depth of the pre-groove 16 can be controlled extremely accurately, and a high quality optical disc master 8 can be manufactured.

Further, since the intermediate layer 11 is formed by the sputtering method, the intermediate layer 11 can be formed with high accuracy, and the prepits 15 and the pregrooves 16 can be more accurately formed.
And the depth of can be managed.

When the intermediate layer 11 is actually formed of "Ni" having a film thickness of 100 (Å) and high-intensity and low-intensity laser beams 13 and 14 are output by an Ar laser having a wavelength of 458 (nm). The maximum intensity of the low-intensity laser beam 14 forming only the pre-groove 16 was 1.5 (mW), and the minimum intensity of the high-intensity laser beam 13 forming the pre-pit 15 was 2.5 (mW).

Further, the intermediate layer 11 was formed of "Al" having various film thicknesses, and the cross-sectional shape of the prepits 15 formed in each of the layers 10 to 12 by the laser beam 13 was observed. Then, as shown in FIG. 3, when the film thickness of the intermediate layer 11 becomes 300 (Å) or more, the intensity of the laser beam 13 is extremely increased to evaporate the film, so that the second photoresist layer 1
It was found that the groove formed in 2 spreads too much and the photoresist layers 10 and 12 were significantly deteriorated by the heating of the laser beam 13. On the other hand, when the intermediate layer 11 is 50 (Å) or less,
Since it is difficult to make the film thickness uniform, the accuracy of convergence of the laser beams 13 and 14 decreases. Therefore, when the intermediate layer 11 is formed of a metal such as "Al", the film thickness is preferably 50 to 300 (Å).

Since the metal forming the intermediate layer 11 preferably has a low melting point so that it can be easily evaporated by the laser beam 13, for example, a transition metal having a melting point lower than "Cr" is suitable. In particular, it is an alloy of transition metals "A
Since u-Cu ”and“ Ag-Cu ”have lower melting points than simple transition metals, they are suitable as materials for the intermediate layer 11. In addition, metals of 3B to 6B groups have melting points higher than that of transition metals. Since many of them are low, this is also an optimum material for the intermediate layer 11.

In the method of manufacturing the optical disk master 8 of this embodiment, the photoresist layers 10 and 12 are developed after the exposure of the laser beams 13 and 14 is finished. However, the second photoresist layer 12 is pre-developed before the exposure with the laser beams 13 and 14, and the laser beams 13 and 14 are pre-developed after the pre-development.
It is also possible to execute 14 exposures and execute formal development after completion of this exposure. In this case, the developing speed of the second photoresist layer 12 is reduced, so that the groove width formed here is not widened.

Actually, the intermediate layer 11 is formed of "Ni" with a film thickness of 400 (Å)
When the cross-sectional shape of the pre-pits 15 is observed with and without the pre-development, it is formed on the second photoresist layer 12 when the pre-development is not performed, as shown in FIG. The groove width is widened, and the pre-pit 15 has an unfavorable shape in which the groove width is widened upward as a whole. However, when pre-development is performed, the groove width formed in the second photoresist layer 12 does not unnecessarily widen, and the pre-pit 15 has a preferable shape in which there is little difference in groove width in the depth direction as a whole. became.

Further, in the method of manufacturing the optical disc master 8 of this embodiment, the first and second photoresist layers 10 and 12 are used.
However, the present invention is not limited to the above-mentioned embodiment, and the second photoresist layer 12 has a lower sensitivity than the first photoresist layer 10. It is also possible to form by. In this case, the second photoresist layer 1
Since No. 2 has low sensitivity, the groove width formed by exposure does not widen.

In practice, the intermediate layer 11 is formed with a film thickness of 400 (Å) "N".
i ", and the first photoresist layer 10 is formed of" TSMR-8900 (manufactured by Tokyo Ohka) "which is a medium-resolution and high-sensitivity photoresist, and the second photoresist layer 1 is formed.
2 is "TSMR" which is a high resolution and medium sensitivity photoresist.
-V3 (manufactured by Tokyo Ohka) "and observing the cross-sectional shape of the pre-pit 15, the groove width formed in the second photoresist layer 12 is unnecessary, as in the case of performing the pre-development of FIG. The pre-pit 15 has a preferable shape with a small difference in groove width in the depth direction as a whole.

Next, a second embodiment of the present invention will be sequentially described below with reference to FIGS. 5 and 6. Regarding the method of manufacturing the optical disk master 17 shown in this embodiment, the same parts as those of the method of manufacturing the optical disk master 8 described as the first embodiment are designated by the same names and reference numerals, and detailed description thereof will be omitted. .

First, in the method of manufacturing the optical disc master 17 of the present embodiment, as shown in FIG. 5A, the reflection layer 18 is formed on the surface of the glass substrate 9 by the sputtering method, and then the FIG. ~ (D), the first photoresist layer 10, the intermediate layer 11 and the second photoresist layer 1
2 and are formed in order.

Next, as shown in FIG. 5E, the second photoresist layer 1 is exposed by exposure to the low-intensity laser beam 14.
2 and a latent image of a pre-pit is formed on the first photoresist layer 10 while evaporating the second photoresist layer 12 and the intermediate layer 11 by exposing the latent image of the pre-groove to the laser beam 13 of high intensity. To form.

Then, the exposed first and second photoresist layers 10 and 12 are developed with an alkaline solution to remove the exposed portions, so that the pre-pits 15 are formed as shown in FIG. 5 (f). An optical disk master 17 having a pregroove 16 and a different depth is obtained.

In the method of manufacturing the optical disc master 17 of this embodiment, the reflective layer 18 is provided below the first photoresist layer 10.
Is positioned, the high-intensity laser light 13 for exposing the pre-pit 15 is reflected by the reflecting layer 18, and the exposure of the first photoresist layer 10 is performed without increasing the exposure amount of the second photoresist layer 12. The amount increases. For this reason,
Prepits 1 formed from the second photoresist layer 12 to the first photoresist layer 10 by the laser light 13
5 spreads at the position of the first photoresist layer 10, but does not spread at the position of the second photoresist layer 12. Further, since it is not necessary to unnecessarily increase the intensity of the laser light 13 in order to increase the exposure amount of the first photoresist layer 10, it is possible to reduce the alteration of the photoresist layers 10 and 12 due to the heating of the laser light 13. it can.

Further, since the reflective layer 18 is formed by the sputtering method, the reflective layer 18 can be formed with high accuracy, and the prepit 15 and the pregroove 16 can be more accurately formed.
The shape of and can be managed.

The intermediate layer 11 is actually formed of "Ni" having a film thickness of 400 (Å), and the layers 10 to 12 are formed by the laser beam 13 with and without the reflection layer 18. When the cross-sectional shape of the pre-pit 15 is observed, as shown in FIG. 6, when the reflective layer 18 is not provided, the groove width formed in the second photoresist layer 12 expands, but the first The width of the groove formed in the photoresist layer 10 was narrow, and the pre-pit 15 had an unfavorable shape in which the groove width widened upward as a whole. However, when the reflection layer 18 is provided, the groove width formed in the second photoresist layer 12 does not unnecessarily widen, but the first photoresist layer 10
The width of the groove formed in 1 was sufficiently widened, and the pre-pit 15 had a preferable shape with a small difference in groove width in the depth direction as a whole.

Since a material having a high melting point and a high reflectance is preferable as the material of the reflective layer 18, for example, "W" or "Mo" having a melting point higher than that of "Cr" is suitable for the transition metal. Further, if the reflective layer 18 has a small film thickness, a sufficient reflectance cannot be secured, but if the film thickness is unnecessarily large, the manufacturing time and materials are wasted, so 500 to 1000 (Å) is appropriate.

Further, in the method of manufacturing the optical disc master 17 of the present embodiment, the second photoresist layer 12 is pre-developed before the exposure of the laser beams 13 and 14 as described in the modification of the first embodiment. Alternatively, the second photoresist layer 12 can be formed of a photoresist having a sensitivity lower than that of the first photoresist layer 10.

Next, a fourth embodiment of the present invention will be sequentially described below with reference to FIG. Regarding the manufacturing method of the optical disk master 8 shown in this embodiment, the same parts as those of the manufacturing method of the optical disk master 8 described as the first embodiment are denoted by the same names and reference numerals and detailed description thereof will be omitted. .

First, in the method of manufacturing the optical disk master 8 of this embodiment, as shown in FIGS. 7A to 7C, the first photoresist layer 10 and the intermediate layer 11 are formed on the surface of the glass substrate 9.
Then, the second photoresist layer 12 and the second photoresist layer 12 are sequentially formed, and then a water-soluble resin is applied to the surface of the second photoresist layer 12 by spin coating. This is heated in a clean oven at 110 (℃) for 30 minutes,
As shown in, the water-soluble resin layer 19 is formed on the second photoresist layer 12.

Next, as shown in FIG. 7 (e), a latent image of the pre-groove is formed on the second photoresist layer 12 through the water-soluble resin layer 19 by exposure to the low intensity laser beam 14. , The first photoresist layer 10 while evaporating the water-soluble resin layer 19, the second photoresist layer 12, and the intermediate layer 11 by exposure to high-intensity laser light 13.
A latent image of the pre-pit is formed on.

Then, by developing with an alkaline solution, the entire water-soluble resin layer 19 is removed and the exposed portions of the first and second photoresist layers 10 and 12 are removed, as shown in FIG. As shown, an optical disc master 8 having prepits 15 and pregrooves 16 formed at different depths is obtained.

In the method of manufacturing the optical disk master 8 of this embodiment, since the water-soluble resin layer 19 is located above the second photoresist layer 12, the high intensity laser beam 13 for exposing the pre-pits 15 is used. Second photoresist layer 12
Is not excessively exposed, and it is possible to prevent expansion of the groove width formed in the second photoresist layer 12.

In practice, the second photoresist layer 1
2 was provided with a water-soluble resin layer 19 and the cross-sectional shape of the pre-pits 15 formed in each of the layers 10 to 12 was observed by the laser light 13. As a result, as in the case where the preliminary development of FIG. The groove width formed in the resist layer 12 did not unnecessarily widen, and the pre-pit 15 had a preferable shape with little difference in groove width in the depth direction as a whole.

As a material of the water-soluble resin layer 19,
Since it is preferable that it can be easily applied by a spin coating method and removed by a developing solution, for example, polyvinyl alcohol,
Methylcellulose, polyacrylamide, etc. are suitable. Further, if the water-soluble resin layer 19 has a small film thickness, it is not possible to sufficiently prevent the groove width of the pre-pit 15 from being widened, but if the film thickness is unnecessarily thick, the groove width of the pre-pit 15 becomes too narrow. Since it is useless, 200 to 1000 (Å) is appropriate.

In the method of manufacturing the optical disk master 8 of this embodiment, the second photoresist layer 12 has a lower sensitivity than the first photoresist layer 10, as described above as a modification of the first embodiment. It is also possible to form the photoresist and to pre-develop the second photoresist layer 12 before forming the water-soluble resin layer 19.

[0054]

According to the first aspect of the present invention, the first photoresist layer is evaporated while the second photoresist layer and the intermediate layer are vaporized when a latent image of prepits is formed by exposure to high intensity laser light. By forming the latent image on the second layer, it is not necessary to remove the intermediate layer with an alkaline solution, so that the smoothness of the surface of the second photoresist layer is not damaged by the long-term development of the alkaline solution. Since the intermediate layer does not need to be removed with an acid solution, the manufacturing process and the solution used do not decrease and the productivity is not decreased, and the intensity of the laser beam for vaporizing the intermediate layer has an allowable range. You can accurately control the depth of the groove,
A high quality optical disc master can be manufactured.

According to the second aspect of the present invention, the second photoresist layer is pre-developed before the exposure with the laser beam is performed, so that the developing rate of the second photoresist layer can be reduced. Therefore, it is possible to reduce the expansion of the openings of the prepits formed from the second photoresist layer to the first photoresist layer and form the prepits in a good shape.

According to the third aspect of the present invention, the second photoresist layer is formed of a photoresist having a lower sensitivity than the first photoresist layer, so that the exposure sensitivity of the second photoresist layer can be improved. Since it can be made lower than that of the first photoresist layer, it is possible to reduce the expansion of the openings of the prepits formed from the second photoresist layer to the first photoresist layer and form the prepits in a good shape. it can.

According to the fourth aspect of the present invention, the first photoresist layer is formed after the reflective layer is formed on the substrate, so that the exposure amount of the second photoresist layer is not increased. Since the exposure amount of the first photoresist layer can be increased, the difference in the groove width in the depth direction of the prepits formed from the second photoresist layer to the first photoresist layer can be reduced to reduce the prepits. It can be formed into a good shape.

According to the fifth aspect of the present invention, the water-soluble resin layer is formed on the second photoresist layer before the exposure with the laser beam is performed. You can prevent exposure,
It is possible to reduce the expansion of the openings of the prepits formed from the second photoresist layer to the first photoresist layer and form the prepits in a good shape.

[Brief description of drawings]

FIG. 1 is a process chart showing a method for manufacturing an optical disc master according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the intensity of laser light and the depth of a groove formed.

FIG. 3 is a schematic diagram showing the shape of prepits when the thickness of the intermediate layer is changed.

FIG. 4 is a schematic diagram showing the shape of prepits with and without preliminary development.

FIG. 5 is a process drawing showing the method of manufacturing the optical disc master according to the second embodiment.

FIG. 6 is a schematic diagram showing the shape of a prepit with and without a reflective layer.

FIG. 7 is a process drawing showing the method of manufacturing the optical disc master according to the third embodiment.

FIG. 8 is a process drawing showing a method of manufacturing a conventional optical disk master.

FIG. 9 is a characteristic diagram showing the relationship between the intensity of laser light and the depth of a groove formed.

[Explanation of symbols]

 8, 17 Optical disc master 9 Substrate 10 First photoresist layer 11 Intermediate layer 12 Second photoresist layer 13, 14 Laser light 15 Pre-pit 16 Pre-groove 18 Reflective layer 19 Water-soluble resin layer

Claims (5)

[Claims] 1. A first photoresist layer, an intermediate layer, and a second photoresist layer are sequentially formed on a substrate, and a latent image of prepits is formed by exposure to high-intensity laser light, and at the same time, low intensity. In the method for manufacturing an optical disk master, a latent image of a pre-groove is formed by exposure to a laser beam of, and the exposed first and second photoresist layers are developed to obtain an optical disk master. When a latent image of pre-pits is formed by light exposure, the latent image is formed on the first photoresist layer while evaporating the second photoresist layer and the intermediate layer. Optical disc master manufacturing method. 2. The method of manufacturing an optical disk master according to claim 1, wherein the second photoresist layer is pre-developed before the exposure with the laser light. 3. The method of manufacturing an optical disc master according to claim 1, wherein the second photoresist layer is formed of a photoresist having a sensitivity lower than that of the first photoresist layer. 4. The method of manufacturing an optical disk master according to claim 1, wherein the first photoresist layer is formed after the reflective layer is formed on the substrate. 5. The method of manufacturing an optical disk master according to claim 1, wherein a water-soluble resin layer is formed on the second photoresist layer before the exposure with the laser light.