JPH0660440A - Production of stamper for optical disk - Google Patents

Abstract

PURPOSE:To obtain such a production method of an optical disk stamper without wet process that enables easy tracking for information recording without using a large-size expensive cutting machine. CONSTITUTION:A film 13 comprising such a material that causes difference in the etching rate by phase change on a substrate 11, and a rugged pattern is formed on this film by using the difference of etching rate due to the phase change. Then a pattern 13a for tracking is recorded in the film comprising the phase transition material and then the area where the pattern is recorded is erased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stamper manufacturing method used for manufacturing various optical disks.

[0002]

2. Description of the Related Art In recent years, optical discs for music software, video software or various information files have been actively manufactured. On the surface of these optical discs, pits or grooves of an information signal are formed in different shapes depending on whether the disc is a read-only disc or a recording / reproducing disc. It is formed when it is poured at a high temperature into the formed metal matrix, that is, a mold provided with a so-called metal stamper, and then cooled and cured. In this way, the metal stamper for forming signal pits or grooves on the optical disc is
Usually, it is manufactured by electroforming method (Actual No. Sho 56-61).
369, JP-A-1-225788, and JP-A-2-196640). Specifically, FIG.
As shown in FIG. 3, a resist 2 is applied on the glass plate 1, exposed by a laser, and then the resist 2 is developed to form a resist pattern 2a (FIG. 9). Then, prior to the electroforming step, a resist pattern 2 is formed to make the surface conductive.
A metal film 3 of nickel or the like is formed on a by a vacuum deposition method or a sputtering method (FIG. 10), and subsequently, a metal is thickly applied on the metal film 3 by an electroforming method to form an electroformed film 4.
Are formed (FIG. 11). After that, as shown in FIG. 12, the glass plate 1 is peeled off, the resist pattern 2a remaining in the metal film 3 is removed, and then the metal is thickened again by electroforming, and peeled off again to form FIG. The metal stamper 5 shown is obtained.

However, the method of manufacturing a metal stamper as described above has a problem that the time required for each process such as exposure, development and electroforming of the resist is long and the manufacturing cost is high. Furthermore, resist coating, development,
Since there are many wet processes such as electroforming, and particularly large-scale manufacturing equipment such as electroforming equipment is required, there are problems in facilities such as the need for power distribution equipment for large power and a large clean room. is there. Moreover, after the electroforming step, post-processing such as trimming, polishing and punching of the inner and outer circumferences of the stamper is required, and a lot of additional equipment for that is required.

Therefore, recently, there has been proposed a method of recording a signal by a heat mode and manufacturing a stamper by utilizing a difference in etching rate between an amorphous phase and a crystalline phase of a film made of a phase change material (special feature: Kaihei 3-12734
No. 2). In this method, the pits or grooves made of the phase change film are formed on the substrate, the electroforming process is not required unlike the conventional method, and the substrate at the time of film formation can be used as it is as the substrate of the stamper. There is an advantage that the process is extremely simplified.

[0005]

However, in this method, since the tracking of the recording head is not corrected with respect to the substrate to be recorded at the time of signal recording, the substrate having excellent flatness and the extremely sophisticated substrate feeding mechanism are used. In addition, the cutting machine becomes large in size, and a high level of maintenance technology and an anti-vibration mechanism are required, so that the entire apparatus becomes expensive.

Therefore, needless to say, the present invention does not require a wet process, and tracking at the time of recording an information pattern on a substrate can be performed very easily, and a cutting machine to be used is small and inexpensive. Therefore, it is an object of the present invention to provide a method for manufacturing a stamper for an optical disc having good productivity as a result.

[0007]

In order to achieve the above object, according to the present invention, a film made of a substance that causes an etching rate difference due to a phase change is formed on a substrate, and the etching due to the phase change is performed. A method for manufacturing a stamper for an optical disk, which has a step of forming irregularities on this film by a rate difference, including a step of recording a tracking pattern on the film made of the phase change material, and a step of erasing the pattern recording portion. Things will be provided.

According to the present invention, a continuous or discrete spiral pattern for tracking is recorded on a phase change film on a substrate surface on which an information signal is to be recorded, and the tracking pattern is recorded. A signal corresponding to a pit is recorded on the phase change film by using it, and at the same time as the recording,
Alternatively, immediately before or immediately after, the tracking pattern is erased so that only the signal corresponding to the pit shape is recorded on the phase change film, and in that state, the portion recorded as the crystalline phase on the phase change film. This is based on the idea that the phase change film is patterned by utilizing the etching rate difference between the amorphous phase and another amorphous phase, and the substrate is etched by using the phase change film as an etching mask.
By the way, indium (I
A substance such as n) -antimony (Sb) cannot be used as a mask as it is because the etching rate for Ar ions or the like is higher than the etching rate for a metal such as Ni that is the substrate. Therefore,
First, a thin film made of a substance having a small etching rate for a physical etching method and a different removal condition from the phase change film is interposed between the substrate and the phase change film. It is preferable to perform a two-step etching process in which the substrate is etched and the substrate is etched using this thin film as a mask.

Hereinafter, each manufacturing process of the optical disk stamper of the present invention will be described in detail with reference to the accompanying drawings.

First, as shown in FIG. 1, the first thin film 12 is formed on the polished surface of the substrate 11. This thin film 12 is the base 1
It is necessary to select a material that functions as a mask in the physical etching of No. 1, that is, has a small etching rate for the physical etching. Specifically, materials that are vaporized by reaction with halogen or oxygen, such as Si, SiO ₂ , Si ₃ N ₄ , Al, Mo, Cr,
An inorganic material such as W or Nb or an organic material such as PMMA or PVA is used, and these materials are deposited by a vacuum deposition method, a sputtering method, a spin coating method, or the like. At this time, the thickness of the thin film 12 determines the depth of the pit or the groove, and thus must be strictly controlled.

Next, a second thin film (hereinafter referred to as "phase change film") 13 made of a phase change material is formed on the first thin film 12 (FIG. 2). This phase change substance causes a phase change by irradiation with a laser or the like, and the etching rate of the irradiated portion is smaller than that of the non-irradiated portion. Specific examples include those used for optical recording media.
An inorganic compound composed of a combination of elements such as Te, Se, Ge, In and Sb is suitable. This thin film 13 is also formed by a vacuum deposition method or a sputtering method, and its thickness is preferably about 0.05 to 0.15 μm.

Then, a tracking pattern 13a is recorded on the phase change film 13 (FIG. 3). In the recording method for this purpose, for example, a glass mask 15 in which a metal is spirally patterned is placed close to the phase change film 13, and a heat ray pulse is irradiated through the opening 15a of the glass mask 15 to form the phase change film. 13 causes a phase change along the pattern of the glass mask 15. Since the reflectance changes in this phase change portion, this can be used as a tracking signal when an information signal is recorded between the spiral phase change patterns 13a. A laser beam or a flash lamp is used as the heat ray pulse. On the other hand, the alignment of the substrate 11 and the glass mask 15 is performed by controlling the position of the substrate 11 and the glass mask 15 by processing an image using light having an intensity that does not cause a phase change.

Thereafter, a signal from the spiral continuous pattern thus recorded is used as a tracking signal to form, for example, a pit-shaped pattern 16 on the phase change film 13 to obtain an information signal pattern (FIG. 4). The method of forming the pit-shaped pattern 16 uses a simple laser light source such as a semiconductor laser (wavelength 830 nm) or a He-Ne laser (wavelength 630 nm) to apply laser light to a required position of the phase change film 13. By irradiating,
Cause a phase change. At this time, the previously recorded spiral continuous linear phase change pattern 13a is erased. This erasing method is performed, for example, by irradiating short-wavelength pulsed light with an erasing optical head.
Since the etching rate of the phase change film 13 in which the phase change occurs is smaller than that of the other parts, the Ar ion is irradiated on the film surface of the thin film 13 for etching. Then, only the phase change portion is left and other portions are removed. In this etching step, the first thin film 12 remains without being removed because the etching rate for physical etching is very small.

The thin film 12 is etched using the pit-shaped pattern 16 formed on the thin film 13 as a mask as described above (FIG. 5). As this etching method,
A plasma etching method using a reactive gas is used.
As the reactive gas at this time, CF ₄ , CHF ₃ , SF ₆ , CCl ₄ , O ₂ or the like may be appropriately selected depending on the substance forming the thin film 12. After this process, the base 11
The pit-shaped patterns 16 and 16a having a two-layer structure of the thin film 12 and the thin film 13 are formed on the top.

Then, the substrate 11 is etched by irradiating the film surface with Ar ions again. At this time, of the pit-shaped patterns 16 and 16a having the two-layer structure, the upper thin film 1
3 is easily removed, but the lower thin film 12 has a small etching rate for physical etching.
Without being removed, it functions as a mask for the substrate 11 and the surface of the substrate 11 can be etched to form a pit-shaped pattern 17 (FIG. 6).

Finally, by the above-mentioned reactive etching,
The thin film 12 is removed to obtain an optical disk stamper 18 made of a single metal (FIG. 6).

[0017]

EXAMPLES Specific examples of the present invention will be described below.

On a Ni substrate having a smooth surface and a thickness of 1 mm,
SiO ₂ was deposited to a thickness of 0.1 μm by the sputtering method. Then, on the SiO ₂ film in the same chamber, In
-Sb was deposited to a thickness of 0.1 μm by a sputtering method, and this substrate was heat treated at 250 ° C.
The -Sb film was crystallized. Next, pitch 1.6 μm,
A glass mask having a spiral pattern with a line-to-line aperture width of 0.5 μm was placed on the nickel substrate, and the entire surface was scanned with a YAG laser pulse to record the spiral pattern on the phase change film. Next, this spiral
An information signal was recorded between the spiral pattern lines using the pattern as a tracking signal, and the spiral patterns were sequentially erased by another optical head. The recording of the information signal is performed by irradiating a semiconductor laser pulse having a wavelength of 830 μm, and a phase change portion is locally formed on the In—Sb film.
The In—Sb film was placed in an etching tank and plasma-etched. Furthermore, C in the same plasma etching tank
F ₄ gas was introduced to carry out reactive plasma etching of the SiO ₂ film. After that, Ar gas is again introduced into the same plasma etching tank to perform Ni-based plasma etching, and finally CF ₄ gas is introduced again to leave the residual S.
By removing the iO ₂ film, a stamper for an optical disk was completed.

In the above process, the time required for manufacturing can be shortened by about 80% as compared with the case where the conventional wet process is included. Furthermore, since the tracking at the time of recording information can be performed by an extremely simple method, a large and expensive cutting machine as in the past is not required, and the productivity is extremely improved. Further, since the finally obtained stamper is formed of a single metal, the stamper life is about 100, compared with the conventional one in which pits or grooves are formed by the phase change film on the substrate. It was confirmed to be doubled. Furthermore, unlike the conventional method, there is an advantage in that post-processing such as trimming, polishing, punching of the inner and outer circumferences is not required at the end.

[0020]

As is clear from the above description, according to the method of manufacturing an optical disk stamper of the present invention, a high quality stamper can be obtained and a phase change film is used for forming an information pattern. In addition, since the pattern is formed directly on the metal substrate by dry etching, all steps can be performed by the dry process.
Further, since the tracking at the time of recording the signal can be performed extremely easily, the cutting device can be particularly downsized and simplified. Moreover, since the obtained stamper is a metal-integral type and does not require an adhesive layer, it is free from defects such as peeling and can have a long life. Therefore, the method of manufacturing an optical disk stamper of the present invention is extremely useful in the field of manufacturing optical disks for music, video and various information.

[Brief description of drawings]

FIG. 1 is a method 1 for manufacturing an optical disk stamper of the present invention.
It is sectional drawing which shows a process.

FIG. 2 is a first method of manufacturing an optical disk stamper of the present invention.
It is sectional drawing which shows a process.

FIG. 3 is a first method of manufacturing an optical disk stamper of the present invention.
It is sectional drawing which shows a process.

FIG. 4 is a first method of manufacturing an optical disk stamper of the present invention.
It is sectional drawing which shows a process.

FIG. 5 is a first method of manufacturing an optical disk stamper of the present invention.
It is sectional drawing which shows a process.

FIG. 6 is a first method of manufacturing an optical disk stamper of the present invention.
It is sectional drawing which shows a process.

FIG. 7 is a first method of manufacturing an optical disk stamper of the present invention.
It is sectional drawing which shows a process.

FIG. 8 is a cross-sectional view showing one step of a conventional method for manufacturing an optical disk stamper.

FIG. 9 is a cross-sectional view showing one step of a conventional method for manufacturing an optical disk stamper.

FIG. 10 is a first method of manufacturing a conventional optical disk stamper.
It is sectional drawing which shows a process.

FIG. 11 is a first method of manufacturing a conventional optical disk stamper.
It is sectional drawing which shows a process.

FIG. 12 is a first method of manufacturing a conventional optical disk stamper.
It is sectional drawing which shows a process.

FIG. 13 is a first method for manufacturing a conventional optical disk stamper.
It is sectional drawing which shows a process.

[Explanation of symbols]

11 Base 12 First thin film (thin film made of a substance that reacts and vaporizes) 13 Second thin film (thin film made of a phase change substance) 13a Spiral phase change pattern 15 Glass mask 15a Glass mask opening 16 Pit or groove pattern 16a Pit or groove pattern 18 Stamper

Claims (1)

[Claims] 1. A method for manufacturing a stamper for an optical disk, comprising a step of forming a film made of a substance that causes an etching rate difference due to a phase change on a substrate and forming irregularities on the film due to the etching rate difference due to the phase change. 9. A method of manufacturing an optical disk stamper, comprising the steps of: recording a tracking pattern on a film made of the phase change material; and erasing the pattern recording portion.