JPH09274744A - Production of metal master disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent defects in a metal master disk and to obtain an information face having good flatness by forming an information pattern in a metal layer having no conductive thin film. SOLUTION: A conductive layer 3 is formed on the surface of a thin film 2 and energized by using the layer 3 as an electrode for plating to precipitate metal nickel on the surface of the layer 3 and to form a metal layer 4. The surface of the metal layer 4 is polished, on which a light attenuating film 5 is formed, and a thin film 6 is formed on the film 5 and exposed with irradiation of laser beams for information recording. After recording, the information pattern is formed on the thin film 6. Then the light attenuating film 5 and the thin film 6 are removed and the metal layer 4 is peeled from the glass master disk 1 to obtain a master stamper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal master used for manufacturing read-only, write-once, rewritable optical disks and the like.

[0002]

2. Description of the Related Art FIG. 3 is a process diagram showing each step of a conventional metal master manufacturing method. Although there are various names of metal masters here, we will call them master stampers, mother stampers, stampers, and those made by plating the master stamper are those made by plating the mother stamper and mother stamper. I will decide.

Polishing the surface of the glass master 31 which is a substrate,
Cleaning is carried out (a), and the surface of the glass master 31 is polished until defects such as scratches and chips are almost eliminated (b). Then, a photoresist is spin-coated to form a photoresist layer 32 (C). At this time, the adhesive force between the glass master 31 and the photoresist layer 32 is formed by forming a photoresist layer 32 after depositing a metal film such as chromium on the glass master 31 or applying an organic primer material. Are strengthened, but the illustration is omitted. Further, although a pre-baking step for resist stabilization is included, the illustration is omitted.

Then, the glass master 31 is placed on a turntable of a laser cutting machine (not shown).
The glass master 31 is rotationally controlled, and the photoresist layer 32 of the glass master 31 is irradiated with a laser beam to be exposed to record information in a spiral shape or a concentric circle shape (d).

The latent image of the photoresist layer 32 of the glass master 31 on which information is recorded becomes a depression called a pit due to development (e). Thereby, an information pattern is formed on the photoresist layer 32. Next, in order to perform electroforming (hereinafter referred to as plating) for forming a stamper, the surface needs to be electrically conductive, but since the photoresist layer 32 is non-conductive, the surface is made conductive.

[0006] For this conversion into a conductor, vapor deposition or sputtering, which is a metal coating method in vacuum, is used. The conductive layer 33 is formed using such a method (f). Conductive layer 33
Master stamper 34 using nickel as an electrode
To form (g). After removing the master stamper 34 from the glass master 31, the photoresist is removed (H), and nickel plating is performed using the master stamper 34 to produce a mother stamper 35 (R).

The mother stamper 35 is separated from the master stamper 34 (No), and nickel stamping is performed using the mother stamper 35 to produce the stamper 36 (Le). The stamper 36 is peeled off from the mother stamper 35 (wo), the surface other than the recorded information surface of the stamper 36 is polished, and the inner and outer peripheries are mechanically processed to produce the stamper 36 (wa).

However, in the method of manufacturing a metal master as described above, the time required for each step such as photoresist coating, exposure, development, formation of a thin film which is a conductive layer, and plating is long, and any one of them is required. When there is a process defect in a part, there is a problem that it is necessary to start over from the first process.
Generally, the process in which the defects are most likely to occur is the plating process. In order to solve such a problem, an invention in which a plating process is performed in the preceding stage is disclosed in, for example, Japanese Patent Laid-Open No. 5-23415.
No. 3 discloses this.

FIG. 4 is a process diagram showing a method of manufacturing a metal master according to the prior art disclosed in the above publication. The surface of the glass master 41 which is the substrate is polished and washed (A), and the surface of the glass master 41 is polished until there are almost no defects such as scratches and chips (B). Next, a photoresist is spin-coated to form a photoresist layer 42 (C).

Next, in order to make the photoresist layer 42 a conductor, a thin film 43 is formed by vapor deposition or sputtering (D). Using this thin film 43 as an electrode, a Ni plating film 44 is formed by plating (E). Next, this Ni
The plating film 44 and the thin film 43 are separated from the photoresist layer 42 (F), and the photoresist is spin-coated on the thin film 43 of the Ni plating film 44 to form a photoresist layer 45 (G).

Then, the Ni plating film 44 is placed on a turntable of a laser cutting machine (not shown). The Ni-plated film 44 is controlled in rotation, and the photoresist layer 45 of the Ni-plated film 44 is irradiated and exposed with a laser beam to record information in a spiral or concentric circle (H).

The latent image of the photoresist layer 45 of the Ni-plated film 44, on which information is recorded, becomes a depression called a pit due to development. As a result, an information pattern is formed on the photoresist layer 45. Next, the photoresist layer 45 is baked (I) in order to evaporate and harden the solvent and the like, and dry etching is performed to perform the Ni plating film 4
A pit, which is a depression, and a groove, which is a groove, are provided on 4 (J).

Then, the remaining photoresist layer 4
Solvent cleaning and ashing are performed to remove 5 (K). Next, after polishing the surface of the Ni plating film 44 that is not the recorded information surface, the inner and outer peripheries are mechanically processed to form a stamper (L). In this method, since the recording step is performed after the plating step, the plating step and the recording step can be independent, and there is an advantage that parallel processing can be performed.

[0014]

However, the conductive thin film is formed here by the sputtering method or the vacuum deposition method, and the Ni plated film is formed by the plating. Due to this, there is a difference in density between the Ni-plated film and the conductive thin film,
Poor adhesion. That is, the thin film is easily separated from the Ni plating film. Although the information surface of the stamper obtained by this method is a conductive thin film, the thin film is peeled off in the process of peeling from the substrate or the process of removing the resist, and unevenness other than the information pattern is generated on the information surface of the stamper, so that the metal master is not formed. It has the drawback of being a good product.

Before separating the mirror surface stamper from the substrate, the thin film is in contact with the photoresist, and the flatness of the surface of this photoresist is not high. This is due to uneven coating when spin coating the photoresist. Since the surface of the photoresist having a low flatness is the surface to be transferred to the metal master, the surface of the metal master having the information pattern has a drawback that the flatness is not high.

[0016]

In order to solve the above-mentioned problems, the invention according to claim 1 forms a metal layer on a substrate,
A thin film of a thermally sublimable substance or a photoresist is formed on the metal layer, the thin film is irradiated with laser light to form an information pattern, and the same information pattern as the information pattern is formed on the metal layer. The layer is a metal master.

The invention according to claim 2 is characterized in that, in the method for producing a metal master according to claim 1, an optical attenuation film is formed between the metal layer and the thin film.

Further, the invention according to claim 3 is the method for producing a metal master according to any one of claims 1 and 2, wherein the thermal sublimation substance or photo having a groove and / or a hole between the substrate and the metal layer. It is characterized in that a thin film of resist is formed.

According to the first aspect of the present invention, the stamper having a surface with good flatness can be manufactured by forming the information pattern on the metal layer which is directly polished by the polishing and washing process capable of obtaining a good quality surface. In addition, since a metal layer formed by plating, rather than a conductive layer formed by sputtering, can be used as the stamper surface, the surface of the stamper that is the conductive layer is peeled off, which causes unevenness other than the information pattern on the information surface. No defects will occur.

According to the second aspect of the invention, it is possible to prevent the influence of the laser beam light reflected on the metal layer on the glass master disk on the pit formation.

According to the third aspect of the present invention, peeling of the conductive layer due to plating stress or the like can be prevented, and peeling defects between the substrate and the conductive layer can be reduced during plating.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a process diagram showing each step of the method of manufacturing a metal master according to the present invention. The glass master 1 as a substrate is placed on a glass master polishing device (not shown) (a), and is polished with an abrasive material such as cerium oxide (CeO2) to remove fine scratches on the glass surface, and the polishing is completed. After that, the glass master is washed to remove the abrasive (b). In addition to the above mechanical polishing, the polishing method includes chemical polishing by cleaning with a chemical, electrolytic polishing, electroless polishing,
There is physical polishing using sputtering.

After the surface of the glass master 1 has a high flatness, a first thin film 2 which is a thin film of a thermally sublimable substance or a photoresist is formed on the surface of the glass master 1 (c). The first thin film 2 is provided with pits which are depressions and grooves which are groove portions in order to prevent peeling due to plating stress during plating. In this embodiment, the first thin film 2 was irradiated with a laser beam to be exposed (d) and developed to form pits and grooves (e).

When the glass master 1 and the first thin film 2 are adhered, a metal film such as chromium is vapor-deposited or an organic primer material is applied to strengthen the adhesive force between the glass master 1 and the first thin film 2. However, the illustration is omitted. Examples of the thin film of the thermally sublimable substance include chalcogenides such as Te-based substances, inorganic substances such as oxides and sulfides thereof, and organic substances such as nitrocellulose and cyanine dyes. This thermally sublimable substance has an advantage that pits are formed by sublimation without development.

Next, the conductive layer 3 is formed on the surface of the first thin film 2 (f). Since the surface of this first thin film 2 is a non-conductor,
The surface of the first thin film 2 is converted to a conductor in order to perform plating for forming a metal master. The specific method of forming the conductor is as described above.

When the conductive layer 3 is used as an electrode and immersed in a bath of nickel sulfamate (Ni (NH2SO3) 2) or the like, and another electrode is used to conduct electricity, nickel metal is left on the surface of the conductive film 3. It is deposited and plated to form the metal layer 4 (g). And plating is this metal layer 4
Is plated until a predetermined thickness is obtained.

When the metal layer 4 has a predetermined thickness, the plating is finished, and the surface of the metal layer 4 is polished and washed (h). The surface of the metal layer 4 is a surface that is in direct contact with a master stamper or an information recording medium injection-molded as a stamper, and high flatness is achieved by polishing the surface of the metal layer 4. In the conventional stamper manufacturing method, such a high flatness cannot be obtained because the surface directly contacting the information recording medium is the surface to which the coating unevenness of the photoresist has been transferred.

A light attenuation film 5 is formed on the surface of the metal layer 4 whose surface has been polished (i). The light attenuating film 5 is provided to reduce the reflection of the light beam from the metal surface, and specifically, a metal oxide, a metal nitride, a chalcogenide and an organic resin coating film (for example, AZ-BARLI of IBM / Hoechist).
Etc. are suitable. Since the reflection of the light beam from the metal surface makes the pits rectangular, it is useful to form the light attenuating film 5 when it is desired to form pits other than rectangular. A photoresist or a thermally sublimable substance is spin-coated on the light attenuating film 5 to form a second thin film 6 which is a thermally sublimable thin film or a photoresist (j). This is placed on a cutting machine, and a laser beam is irradiated to perform exposure for recording information (k).

After the recording is completed, the latent image of the second thin film 6 appears as depressions called pits due to development. As a result, the information pattern is formed on the second thin film 6. Baking is performed to cure the second thin film 6 and to remove the solvent and the like (1). After that, dry etching is performed to form an information pattern on the stamper (m). The dry etching is performed by previously determining the time when the pit depth of the stamper reaches a predetermined depth by an experiment or the like.

To remove the remaining second thin film 6, solvent cleaning and ashing are performed. Further, in order to remove the light attenuating film 5, dry etching is performed while changing the etching rate. As a result, the light attenuation film 5 and the second thin film 6 are removed (n). Next, the metal layer 4 is peeled from the glass master 1 (o), the inner and outer diameters are processed (p), and the master stamper or stamper is finally obtained.

In this embodiment, the first thin film 2 was formed between the glass master 1 and the conductive layer 3 to prevent peeling, but the present invention can be carried out without using the first thin film 2. Another embodiment of the present invention based on this idea will be described with reference to the drawings. FIG. 2 is a process diagram showing each process of a metal master manufacturing method according to another embodiment of the present invention. The glass master 1 as a substrate is placed on the glass master polishing device (1),
Polishing is performed using an abrasive, and after the polishing is finished, the glass master is washed to remove the abrasive (2).

Thus, the first thin film 2 such as a photoresist or a heat sublimable substance is formed on the surface of the glass master 1 (3). The first thin film 2 is provided to prevent peeling due to plating stress or the like. The first thin film 2 was provided with pits or grooves as grooves, and the first thin film 2 was irradiated with a laser beam to be exposed (4) and developed to form pits and grooves (5).

Next, the first thin film 2 is baked to evaporate and cure the solvent and the like, and then dry etching is performed to form pits which are depressions and grooves which are grooves (6). Then, solvent cleaning and ashing are performed to remove the remaining first thin film 2 (7).

Next, the conductive layer 3 is formed on the surface of the glass master 1 (8). Since the surface of the glass master 1 is a non-conductor, the surface of the glass master 1 is made conductive in order to perform the plating for making the metal master. This conductorization is as described above. Next, when this conductive layer 3 is used as an electrode and immersed in a bath of nickel sulfamate or the like and electricity is applied using another electrode, nickel metal is deposited on the surface of the conductive film 3 to perform plating, Thereby, the metal layer 4 is formed (9). Then, the plating is performed until the metal layer 4 has a predetermined thickness.

When the metal layer 4 has a predetermined thickness, the plating is finished, and the surface of the metal layer 4 is polished and washed (10).
The surface of the metal layer 4 is a surface that is in direct contact with a master stamper or an information recording medium injection-molded as a stamper, and high flatness is achieved by polishing the surface of the metal layer 4. In the conventional stamper manufacturing method, such a high flatness cannot be obtained because the surface directly contacting the information recording medium is the surface to which the coating unevenness of the photoresist has been transferred.

A light attenuating film 5 is formed on the surface of the metal layer 4 whose surface has been polished (11). A photoresist is spin-coated on the light-attenuating film 5 to form a second thin film 6 which is a thermally sublimable thin film or a photoresist thin film (12). This is placed on a cutting machine and irradiated with a laser beam to perform exposure for recording information (13).

After the recording is completed, the latent image on the second thin film 6 appears as depressions called pits due to development. As a result, the information pattern is formed on the second thin film 6. The second thin film 6 is baked (14). After that, dry etching is performed to create an information pattern on the stamper (1
5). The dry etching is performed by previously determining the time when the pit depth of the stamper reaches a predetermined depth by an experiment or the like.

To remove the remaining second thin film 6, solvent cleaning and ashing are performed. Further, dry etching for removing the light attenuating film 5 is performed. As a result, the light attenuation film 5 and the second thin film 6 are removed (16). Next, the metal layer 4 is peeled off from the glass master 1 (17), and the inner and outer diameters are processed (1
8) Finally, a master stamper or a stamper is used.

In the present embodiment, when the pit is formed on the second thin film 6, if the turntable is rotated in the reverse direction, the formed information pattern is reversed, so that the metal master becomes a mother stamper. However, in this case, it is necessary to use a negative photoresist so that when the photoresist is developed, the latent image is projected instead of being hollow. A stamper can be manufactured by performing plating using this mother stamper. As described above, the metal master according to the present invention is applicable not only to the master stamper, the mother stamper or the stamper but also to all metal master manufacturing methods.

Further, in the present invention, when the process is defective, it is not necessary to perform it from the beginning. For example, the steps from (a) to (h) in FIG. 1 and the steps from (i) to (p) can be independent, and parallel processing can be performed at the same time. Thus, even if there is a defect in the process, the time required for the process to be redone can be shortened. For example, even if a defect occurs in the plating process of FIG. 1 (f), if a glass master having a metal layer is made in consideration of the defect, the delay due to the defect of the plating process can be avoided.

Further, in the present embodiment, the present invention can be carried out by using a metal plate having a predetermined thickness instead of the formation using the glass master disk 1, the first thin film 2, the conductive layer 3 and the metal layer 4. is there. In this case, from (a) to (g) in FIG.
The steps (1) to (9) in FIG. 2 can be omitted.

Further, in the present embodiment, the first thin film 2 was provided on the glass master 1 to improve the adhesiveness, but the first thin film 2 was not formed and the steps (c) and (d) shown in FIG. 1 were performed. ),
(E), the steps (3), (4), and
It is also possible to omit steps (5), (6), and (7), directly form a conductive layer in direct contact with a substrate having no groove or hole, and subsequently manufacture a metal master in the same step.

[0043]

When the metal master according to the present invention is used, an information pattern is formed on a metal layer having no conductive thin film, so that the conductive thin film is peeled off from the metal layer so that information is recorded on the information surface of the stamper. It is possible to eliminate defects in the metal master that are caused by unevenness other than the pattern.

Further, by directly polishing the metal master, it is possible to prevent the flatness of the information surface from being lowered due to the uneven coating of the photoresist, and it is possible to manufacture the metal master having the information surface having good flatness.

[Brief description of drawings]

FIG. 1 is a process drawing showing each process of a metal master manufacturing method according to the present invention.

FIG. 2 is a process drawing showing each process of a metal master manufacturing method according to another embodiment of the present invention.

FIG. 3 is a process drawing showing each process of a metal master manufacturing method according to a conventional technique.

FIG. 4 is a process diagram showing a method of manufacturing a metal master according to a conventional technique disclosed in Japanese Patent Laid-Open No. 5-234153.

[Explanation of symbols]

 1 Glass Master 2 First Thin Film 3 Conductive Layer 4 Metal Layer 5 Optical Attenuation Film 6 Second Thin Film

Claims (3)

[Claims] 1. A metal layer is formed on a substrate, a thin film of a thermally sublimable substance or a photoresist is formed on the metal layer, and the thin film is irradiated with laser light to form an information pattern. A metal master manufacturing method, wherein the same information pattern is formed on the metal layer, and the metal layer is used as a metal master. 2. The method of manufacturing a metal master according to claim 1, wherein an optical attenuation film is formed between the metal layer and the thin film. 3. The method of manufacturing a metal master according to claim 1, further comprising forming a thin film of a thermally sublimable substance or a photoresist having a groove and / or a hole between the substrate and the metal layer. A feature of the method for producing a metal master.