JP3586731B2 - Manufacturing method of glass master for optical disk - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mastering technique for a stamper for an optical disc, and more particularly to a method for producing a glass master for a hybrid CD-R and a hybrid CD-RW.
[0002]
[Prior art]
In an optical disk having pits and grooves, it is desirable that the respective depths are λ / 4n and λ / 8n (λ: reproduction wavelength n: refractive index of the substrate). In order to obtain such an optical disk, it is necessary that the pattern formation of the photoresist on the optical disk master is also different between the pits and the grooves.
[0003]
Conventionally, in order to change the depth of a photoresist pattern, the intensity of a laser to be exposed has been used. That is, a shallow groove is formed with weak laser power, and a deep pit is formed with strong laser power. The depth of the pit is determined by the thickness of the photoresist, but the depth of the groove depends on the laser power, and the depth of the group tends to fluctuate due to the fluctuation of the laser power during exposure, the fluctuation of the focus, and the like. It is also very difficult to control the width of the group.
[0004]
In order to solve such a problem, as shown in FIGS. 4 and 5, a first photoresist layer 52, an intermediate layer 53, and a second photoresist layer 54 are laminated on a glass substrate 51 in this order. The depth of the groove G is controlled by the total thickness of the second photoresist layer 54 (FIG. 4), and the pits P are determined by the total thickness of the first photoresist layer 52, the intermediate layer 53, and the second photoresist layer 54. (FIG. 5) is proposed.
[0005]
For example, in the method of manufacturing a glass master disc disclosed in Japanese Patent Application Laid-Open No. H7-161077, as shown in FIGS. 4 and 5, development of the second photoresist layer 54, etching of the intermediate layer 53, and formation of the first photoresist layer 52 are performed. Grooves G and pits P are formed by patterning in the order of development.
[0006]
[Problems to be solved by the invention]
In the method described in the above publication, grooves G and pits P are formed by performing patterning in the order of development of the second photoresist layer 54, etching of the intermediate layer 53, and development of the first photoresist layer 52.
[0007]
However, in patterning the groove G, only the development of the second photoresist layer 54 or the development of the second photoresist layer 54 and the etching of the intermediate layer 53 are sufficient, and the development of the last first photoresist layer 52 is sufficient. Then, as shown in FIG. 4D, a step 55 (a step at the groove bottom) occurs in the intermediate layer. The step 55 is generated because the development of the second photoresist layer 54 also proceeds while the development of the first photoresist layer 52 is being performed [FIG. 4 (c) and FIG. (D). Such a step portion 55 is not preferable because it causes noise during reproduction or recording of the optical disk.
[0008]
In the method described in the above publication, the sensitivity of the second photoresist layer 54 is higher than the sensitivity of the first photoresist layer 52, so that the pits P are stepped (FIG. 5D). In this case, there is no particular problem, but if the sensitivity of the second photoresist layer 54 is lower than the sensitivity of the first photoresist 52 layer, a new problem arises. That is, if the development width of the first photoresist layer 52 is made equal to or greater than the development width of the second photoresist layer 54 so that the pits P do not become stepped, as shown in FIG. During the development of the photoresist layer 52, the fragments 53a of the intermediate layer 53 that are not dissolved in the developing solution are scattered over the entire surface of the glass master. Such fragments 53a are not preferable because they cause noise during reproduction or recording of the optical disk.
[0009]
The present invention has been made in view of the above problems, and an object of the present invention is to stack a first photoresist layer, an intermediate layer, and a second photoresist layer on a glass substrate in this order, and form an intermediate layer and a second photoresist layer. An optical disk that controls the groove depth by the thickness of the resist layer and controls the depth of the pits by the thickness of the first photoresist layer, the intermediate layer, and the second photoresist layer to form pits and grooves simultaneously It is an object of the present invention to provide a method for producing a glass master, which has no step at the bottom of the groove and in which no fragments of the intermediate layer remain.
[0010]
[Means for Solving the Problems]
The method of manufacturing a glass master for an optical disk according to claim 1 (see FIG. 1) includes a first positive photoresist layer 12, an intermediate layer 13 made of an oxide film, and a second positive photoresist layer 14 on a glass substrate 11. In the method of fabricating the masters stacked in this order, the first and second positive-type photoresist layers 12, 14 are irradiated with the first recording light of the amount of light that exposes the first and second positive-type photoresist layers 12, 14. A latent image is formed, and a latent image is formed on the second positive photoresist layer 14 with a second recording light having a light intensity smaller than the first recording light that exposes only the second positive photoresist layer 14. Then, the second positive type photoresist layer 14 is developed (FIG. 1 (b)), and the intermediate layer 13 made of an oxide film is etched (FIG. 1 (c)). The phenomenon of the photoresist layer 12 [FIG. d)], and performs processing in the order of the etching of the intermediate layer 13 made of an oxide film [Fig. 1 (e)].
[0011]
In the method of manufacturing a glass master for an optical disk according to the second aspect (see FIG. 3), a negative photoresist layer 32, an intermediate layer 33 made of an oxide film, and a positive photoresist layer 34 are laminated on a glass substrate 31 in this order. In the method of manufacturing a master disc, a latent image is formed on the negative photoresist layer 32 and the positive photoresist layer 34 by the first recording light having a light amount that exposes the negative photoresist layer 32 and the positive photoresist layer 34. Is formed, and a latent image is formed on the positive photoresist layer 34 with the second recording light having a light intensity smaller than the light intensity of the first light for exposing only the positive photoresist layer 34 [FIG. After that, development of the positive photoresist layer 34 (FIG. 3B), etching of the intermediate layer 33 made of an oxide film (FIG. 3C), etching of the negative photoresist layer 32 Grayed [FIG 3 (d)], and performs processing in the order of the etching of the intermediate layer 33 made of an oxide film [Fig. 3 (e)].
[0012]
In the prior art, patterning after exposure is performed in the order of development of the second photoresist layer, etching of the intermediate layer, and development of the first photoresist layer (FIG. 4). On the other hand, in the method of the first aspect, the development of the second photoresist layer, the etching of the intermediate layer, the development of the first photoresist layer, and the etching of the intermediate layer are performed as described above. Further, in the method of claim 2, as described above, the development of the positive photoresist layer, the etching of the intermediate layer, the etching of the negative photoresist layer, and the etching of the intermediate layer are performed.
[0013]
Therefore, as is clear from the comparison between FIG. 1D and FIG. 1E and the comparison between FIG. 5D and FIG. Steps generated in the intermediate layer and fragments of the intermediate layer spread over the entire surface of the glass master can be eliminated in the final etching step.
[0014]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Example 1 (corresponding to claim 1)
In FIG. 1, TSMR-V3 (manufactured by Tokyo Ohka) is formed as a first positive type photoresist on a glass substrate 11 to a thickness of about 1500 ° by spin coating (formation of a first positive type photoresist layer 12). On top of this, ITO (In ₂ O ₃ —SnO ₂ ) is formed to a thickness of about 50 ° by DC sputtering as an intermediate layer 13 made of an oxide film. Further thereon, TSMR-8900 (manufactured by Tokyo Ohka) is formed as a second positive type photoresist by spin coating to a thickness of about 1500 ° (formation of the second positive type photoresist layer 14).
[0015]
The photoresist disc is exposed at a linear velocity of 1.2 m / s using an Ar laser having a wavelength of 457.8 nm. At this time, pits P are formed with the intensity of the first recording light being 5.0 mW, and grooves G are formed with the intensity of the second recording light being 3.0 mW (FIG. 1A).
[0016]
After the exposure, the second photoresist layer 14 is developed with a developing solution DE-3 (manufactured by Tokyo Ohka) [FIG. 1B], and the oxide film (intermediate layer) 13 is etched with nitric acid or hydrochloric acid [FIG. (C)] Then, the first photoresist layer 12 is developed with a developer DE-3 (manufactured by Tokyo Ohka) [FIG. 1 (d)]. Finally, the oxide film 13 is etched with nitric acid or hydrochloric acid (FIG. 1E).
[0017]
Since TSMR-V3 has lower sensitivity than TSMR-8900, a step 15 (FIG. 1D) due to the oxide film 13 occurs in the pit portion. Therefore, no fragment of the oxide film 13 is generated during the development of the first photoresist layer 12 (TSMR-V3). However, when developing the first photoresist layer 12 (TSMR-V3) in the groove portion, the first photoresist layer 12 is not exposed because it is not exposed, but the second photoresist layer 14 (TSMR-8900) is not developed. As a result, a step 16 (FIG. 1D) due to the oxide film 13 occurs at the bottom of the groove. Such a step 15 in the pit portion and a step in the groove portion (both of which are part of the oxide film 13) can be eliminated by the final oxide film etching step (FIG. 1E).
[0018]
Example 2 (corresponding to claim 1)
In FIG. 2, TSMR-GP8000 (manufactured by Tokyo Ohka) is formed as a first positive photoresist on a glass substrate 21 by spin coating at about 1500 ° (formation of a first positive photoresist layer 22). On top of this, ITO (In ₂ O ₃ —SnO ₂ ) is formed as an intermediate layer 23 of an oxide film by DC sputtering at about 50 °. Further, TSMR-8900 (manufactured by Tokyo Ohka) is formed thereon as a second positive photoresist by spin coating at about 1500 ° (formation of a second positive photoresist film 24).
[0019]
The photoresist disk is exposed at a linear velocity of 1.2 m / s by an Ar laser having a wavelength of 457.8 nm. At this time, pits P are formed with the intensity of the first recording light being 5.0 mW, and grooves G are formed with the intensity of the second recording light being 3.0 mW (FIG. 2A).
[0020]
After the exposure, the second photoresist layer 24 is developed with a developing solution DE-3 (manufactured by Tokyo Ohka) [FIG. 2 (b)], and then the oxide film (intermediate layer) 23 is etched with nitric acid or hydrochloric acid [FIG. 2 (c)], the first photoresist layer 22 is further developed with a developing solution DE-3 (manufactured by Tokyo Ohka) [FIG. 2 (d)], and finally the oxide film 23 is etched with nitric acid or hydrochloric acid [ FIG. 2 (e)].
[0021]
Since the sensitivity of TSMR-GP8000 is higher than that of TSMR-8900, the development speed of the first photoresist layer 22 (TSMR-GP8000) is faster than that of the second photoresist layer 24 (TSMR-8900). Therefore, the first photoresist layer 22 (TSMR-8900) under the oxide film 23 is also developed, and the oxide film 23 is scattered as fragments 23a (FIG. 2D). Also, when developing the first photoresist layer 22 (TSMR-GP8000) in the groove portion, the first photoresist layer 22 is not developed because it is not exposed, but the second photoresist layer 24 (TSMR-8900) is not developed. Due to the development, a step 25 is formed at the bottom of the groove by the oxide film 23 (FIG. 2D). However, such fragments 23a and step portions 25 of the oxide film 23 can be eliminated in the final oxide film etching step (FIG. 2E).
[0022]
Example 3 (corresponding to claim 2)
In FIG. 3, FHT-332S (manufactured by Fuji Film Orin) is formed on a glass substrate 31 as a negative photoresist by spin coating at about 1500 ° (formation of a negative photoresist layer 32). On top of this, ITO (In ₂ O ₃ —SnO ₂ ) is formed as an intermediate layer 33 of an oxide film by DC sputtering at about 100 °. Further, TSMR-8900 (manufactured by Tokyo Ohka) is formed thereon as a positive photoresist by spin coating at about 1500 ° (formation of a positive photoresist layer 34).
[0023]
The photoresist disk is exposed at a linear velocity of 1.2 m / s by an Ar laser having a wavelength of 457.8 nm. At this time, a groove G is formed with the intensity of the first recording light being 6.0 mW, and a pit P is formed with the intensity of the second recording light being 2.5 mW (FIG. 3A).
[0024]
After the exposure, the positive photoresist layer 34 is developed with a developing solution DE-3 (manufactured by Tokyo Ohka) [FIG. 3 (b)], and the oxide film (intermediate layer) 33 is etched with nitric acid or hydrochloric acid [FIG. 3 (c)], the negative photoresist layer 32 is etched with a developer DE-3 (manufactured by Tokyo Ohka) [FIG. 3 (d)], and the oxide film 33 is finally etched with nitric acid or hydrochloric acid [ FIG. 3 (e)].
[0025]
Since FHT-332S is a negative photoresist, it becomes insoluble in the developing solution when exposed to the first recording light, but is not exposed to the second recording light and is easily dissolved in the developing solution. Accordingly, in the etching of the negative photoresist layer 32 (FHT-332S), since the etching of the negative photoresist layer 32 is faster than the development of the positive photoresist layer 34 in the portions where the pits are exposed, the oxidation is performed. The negative photoresist layer 32 under the film 33 is etched, and the oxide film 33 is scattered as fragments 33a (FIG. 3D). Further, in the portion where the groove is exposed, the etching of the negative photoresist layer 32 does not occur, and only the positive photoresist layer 34 is developed, and a step 35 of the oxide film 33 is generated at the bottom of the groove [FIG. d)]. Such fragments 33a and the steps 35 can be eliminated by the final oxide film etching step (FIG. 3E).
[0026]
【The invention's effect】
As is apparent from the above description, according to the glass master manufacturing method according to the first and second aspects, the oxide film temporarily occurs in the groove and the entire surface of the glass master temporarily scatters. The oxide film fragments can be eliminated in the oxide film etching step which is the final step of patterning. Therefore, a high-performance optical disk with low noise during reproduction / recording can be manufactured using the glass master manufactured in the present invention.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing the steps of Example 1 of the present invention.
FIG. 2 is an explanatory view showing the steps of Example 2 of the present invention.
FIG. 3 is an explanatory view showing the steps of Example 3 of the present invention.
FIG. 4 is an explanatory view showing a conventional method for producing a glass master and its problems.
FIG. 5 is an explanatory view showing another problem with the manufacturing method of FIG. 4;
[Explanation of symbols]
11, 21, 31 Glass substrate 12, 22 First positive photoresist layer 13, 23, 33 Oxide film (intermediate layer)
14, 24 Second positive photoresist layer 15, 16, 25, 35 Stepped portion 23a, 33a Fragment 32 Negative photoresist layer 34 Positive photoresist layer 51 Glass substrate 52 First photoresist layer 53 Intermediate layer 53a Fragment 54 Second photoresist layer 55 Step G Groove P Pit

Claims (2)

In a method of manufacturing a master in which a first positive photoresist layer, an intermediate layer made of an oxide film, and a second positive photoresist layer are sequentially laminated on a glass substrate, the first and second positive photoresist layers are formed. A latent image is formed on these positive photoresist layers by the first recording light having a light quantity for exposing the second positive photoresist layer, and a light quantity weaker than the light quantity of the first recording light. Forming a latent image on the second positive type photoresist layer with the second recording light, developing the second positive type photoresist layer, etching the intermediate layer composed of an oxide film, and forming the first positive type photoresist. A method of manufacturing a glass master for an optical disk, wherein the processing is performed in the order of the phenomenon described above and the etching of the intermediate layer comprising an oxide film. In a method for manufacturing a master in which a negative photoresist layer, an intermediate layer made of an oxide film, and a positive photoresist layer are laminated in this order on a glass substrate, the light amount of the negative photoresist layer and the positive photoresist layer that is exposed to light is reduced. A latent image is formed on these photoresist layers by the recording light of No. 1 and only the positive type photoresist layer is exposed. After forming a latent image on the layer, processing is performed in the order of development of a positive photoresist layer, etching of an intermediate layer composed of an oxide film, etching of a negative photoresist layer, and etching of an intermediate layer composed of an oxide film. For producing a glass master for an optical disk.

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