JP2001250236A - Optical recording disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems that a signal for detecting a header part is not obtained and timing when a beam enters the header part is not detected when a light beam enters the header part recording a format signal from a data part consisting of a land part and a groove part, in a method for detecting difference signal intensity from a photodetector divided orthogonally to the advancing direction of the beam when a signal from an optical recording disk is detected. SOLUTION: In the optical recording disk having on a substrate at least the land part and the groove part for recording/reproducing and the header part recording format information, recording information at least on the land part and performing recording/reproducing of information, the difference of a height of 3-100 nm is provided between a height of the header part and a height of the land part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rewritable optical recording disk.

[0002]

2. Description of the Related Art An optical recording disk is a portable recording medium capable of large-capacity, high-density recording, and a rewritable medium for recording a moving image or the like as a large-capacity storage file of a computer accompanying the recent increase in multimedia. Demand is rapidly increasing.

A conventional rewritable optical recording disk is generally formed by forming a multilayer film including a recording layer on a plastic disk-shaped substrate obtained by injection molding, and irradiating a laser from the plastic substrate side to perform recording, reproduction, and erasure. I was going.

Further, in recent years, a surface recording / reproducing method for recording / reproducing by bringing an optical head close to a recording film has attracted attention as a means for achieving higher recording.

In this surface recording / reproducing method, it is necessary to bring the optical head close to the optical recording disk. Therefore, instead of irradiating the recording film with the laser beam through the substrate as in the conventional optical recording disk, the recording head does not pass through the substrate. A method of directly irradiating the recording film with a laser beam.

That is, while the structure of the recording film is generally a substrate / first protective film / recording film / second protective film / reflective film in a conventional optical recording disk, near-field optical recording is performed. In this method, recording / reproducing is performed by irradiating a laser beam from the film surface side as a reverse film structure of substrate / reflective film / recording film / protective film (surface recording / reproducing). At this time, it has been proposed to use a floating slider head to bring the recording film and the optical head closer to each other.

[0007]

In detecting a signal from an optical recording disk, a split type detector is generally used, and the difference signal intensity of the photo detector divided perpendicularly to the beam traveling direction is used. In the detection method, when the light beam enters the header portion for recording the format signal from the data portion including the land portion and the groove portion, if the height of the data portion is the same as the height of the header portion, the header portion is detected. Therefore, there is a problem that a timing at which the beam has entered the header section cannot be detected because a signal to be transmitted cannot be obtained.

The present invention has a data portion having a land portion and a groove portion structure involved in recording and reproduction, and a header portion for recording format information, and records and reproduces data by a method of recording information on at least the land portion. An object of the present invention is to provide an optical recording disk capable of detecting the timing of the header section when the optical head enters the header section from the data section by the split type detection method.

[0009]

Means for Solving the Problems In view of the above situation, the present inventors have made intensive studies and as a result, have found that at least a land portion and a groove portion involved in recording and reproduction, and a header portion for recording format information are included. An optical information disk for recording information on at least a land portion and recording / reproducing data by providing a height difference between a height of a header portion and a height of a land portion, thereby providing a detector of a split type detection system. And found that an optical recording disk capable of detecting the timing of the header portion when the optical head entered the header portion from the data portion was obtained, and completed the present invention.

Hereinafter, the present invention will be described in detail.

In the present invention, the difference between the height of the header portion and the height of the land portion is preferably 3 to 100 nm.

If the step is less than 3 nm, a signal intensity capable of detecting the step signal by the split type detector cannot be obtained as a difference between the height of the header and the land, and the timing of entering the header may not be detected. On the other hand, the step is 100 nm
When the value exceeds the above range, it is necessary to correct the defocus of the laser in the data portion and the header portion, and the flying stability of the flying optical head used in the surface recording / reproducing method is deteriorated, which may cause a head crash.

In the present invention, the height of the header portion and the height of the land portion may be different from each other. More specifically, the height of the header portion may be higher than the height of the land portion. Alternatively, the height of the header portion may be lower than the height of the land portion. The height in the present invention refers to a height based on the lowermost part of the groove. When there is no groove portion in the header portion, the height of the header portion is defined as the height based on the lowermost portion of the groove portion in the circumferential direction as viewed from the header portion, and the height may be different from the height of the land portion.

In the present invention, the step between the header portion and the land portion may be formed by a 2P method or an injection molding method using a stamper having a step structure. Alternatively, the land portion is partially melted by light irradiation, and a height difference from the header portion can be provided.

[0015] The substrate of the present invention is preferably a substrate formed by injection molding.
Any thermoplastic resin can be used as long as it satisfies the characteristics of the optical disc substrate such as transferability. Specific examples include transparent plastics such as polycarbonate, polymethyl methacrylate, and amorphous polyolefin, and so-called super engineering plastics such as polyphenylene sulfide, polyarylate, polyether ketone, and polyether ether ketone.

The recording method of the optical recording disk of the present invention is
bFeCo, DyFeCo, GdTbFeCo, NdD
Any recording method can be used, such as a magneto-optical recording method using a recording film such as yFeCo or a phase change recording method using a recording film such as GeSbTe or AgInSbTe. Not limited.

Also, in the optical recording disk of the present invention,
Information recording should be performed at least on the land,
Further, information may be recorded on the groove.

In addition to the conventional method of recording / reproducing / erasing by irradiating a laser from the substrate side, a surface recording / reproducing method of recording / reproducing / erasing by irradiating a laser from the recording film side or a near-field optical recording Can be used without any problem.

When used in the surface recording / reproducing system or the near-field optical recording system, a lubricating layer is preferably formed on the outermost surface of the optical recording disk because a floating optical head is used.

The lubricating layer can be used if it has lubricating properties such as silicone oil or fluoropolyether-based fluorine oil. Perfluoropolyether and perfluoropolyether derivatives are particularly preferable.

Examples of perfluoropolyether derivatives include alcohol-modified perfluoropolyether, ester-modified perfluoropolyether, isocyanate-modified perfluoropolyether, carboxyl group-modified perfluoropolyether, and piperonyl-modified perfluoropolyether. . The thickness of the lubricating layer of the present invention is 0.1.
It is preferably from 3 to 4.0 nm.

If the thickness is less than 0.3 nm, the protective performance of the lubricating layer is reduced, and the thin film is liable to be scratched. If the thickness exceeds 4.0 nm, the slider head may stick to the disk and cause a crash.

When the optical recording disk of the present invention is applied to a near-field optical recording disk, at least a first protective layer, a magneto-optical recording layer, a second protective layer, a diamond-like carbon (DLC) layer, a lubricating layer Are preferably laminated.

Specifically, after injection molding, AlN, SiN, Ta ₂ O ₅ , ZnS—SiO ₂ are formed on the substrate as a first protective layer.
A transparent dielectric film such as ₂ is formed by a sputtering method or a vacuum evaporation method. TbFeCo, DyFe
A recording layer made of a magneto-optical recording film of Co, GdTbFeCo, NdDyFeCo, or the like is formed by a sputtering method, a vacuum evaporation method, or the like. Further, on this recording layer, Al is used as a second protective layer.
N, SiN, Ta ₂ O to _5, ZnS-SiO ₂ or the like is formed by sputtering or a vacuum evaporation method, or the like formed by a sputtering method DLC film thereon. Further, a recording disk is formed by forming a lubricating layer thereon by a method such as a dip pulling method.

The first protective layer only needs to have a thickness enough to protect the recording layer, and preferably has a thickness of 10 to 100 nm. The recording layer is required to have a thickness such that light does not transmit to the first protective layer, and preferably has a thickness of 30 to 200 nm. In addition to the role of protecting the recording layer, the second protective layer also controls the light absorption efficiency of the recording layer, and also increases the amount of change in reflected light before and after recording and the Kerr rotation angle. For this reason, the thickness of the second protective layer is designed in consideration of the laser wavelength to be used.
0-300 nm is preferred. A between the substrate and the first protective layer
It is also possible to adjust the recording sensitivity by inserting a film having good thermal conductivity such as 1, Al alloy, Au, Ag, etc. as a heat sink.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to only these Examples.

Embodiment 1 A stamper having a track pitch of 0.45 μm in a land portion and a groove portion of a data portion, a groove depth of 65 nm and a header portion being 42 nm lower than a land portion is mounted on a mirror surface of a mold and injection-molded. By the diameter of 130mm,
A polycarbonate substrate having a substrate thickness of 1.2 mm was produced.

Using this substrate, a film was formed on both surfaces of the substrate by a sputtering method in the following manner.

First, Al-3 wt% as a reflection layer is formed on a substrate.
A Cr alloy film (50 nm thick) was formed by DC sputtering. On this, a first protective layer made of SiN is formed by Ar and N
Reactivity R using Si target in mixed atmosphere of ₂
It was formed by the F sputtering method (film thickness: 5 nm). Tb on this
_A magneto-optical recording layer of ₂₀ (Fe ₉₀ Co ₁₀ ) ₈₀ was formed by DC simultaneous sputtering of a Tb target and an Fe ₉₀ Co ₁₀ target (film thickness: 20 nm). In addition, Si
The second protective layer made of N is formed in a mixed atmosphere of Ar and N ₂ by S.
It was formed by a reactive RF sputtering method using an i target (thickness: 30 nm). A DLC layer having a refractive index of 1.85 at 633 nm was formed thereon by a reactive RF sputtering method using a C target in a mixed atmosphere of Ar and CH ₄ (film thickness: 20 nm).

Then, on the other side, the reflection layer, the first protective layer, the magneto-optical recording layer, the second protective layer and the
C layer was formed.

After forming the DLC layer, piperonyl-modified perfluoropolyether (manufactured by Audimont Co., trade name: Fomblin: using a perfluoropolyether solvent (manufactured by Ausimont Co., trade name: Galden SV-70)) A lubricating layer was applied to a thickness of 1.5 nm by pulling up the recording disk from a 0.01 wt% solution of AM2001 ") to complete a near-field magneto-optical recording disk.

The thickness of the lubricating layer is determined by X-ray photoelectron spectroscopy (XP
Calculated by observing the C ₁ S peak intensity using S).

Example 2 A stamper having a track pitch of 0.45 μm in a land portion and a groove portion of a data portion, a groove depth of 65 nm, and a header portion being 90 nm lower than a land portion was attached to a mirror surface of a mold, and a diameter was formed by injection molding. A polycarbonate substrate having a thickness of 130 mm and a thickness of 1.2 mm was prepared, and a film was formed and a lubricant was applied in the same manner as in Example 1 to prepare a near-field magneto-optical recording disk.

COMPARATIVE EXAMPLE 1 A stamper having a track pitch of 0.45 μm between a land portion and a groove portion of a data portion and having no difference in height between a data portion and a header portion was mounted on a mirror surface of a mold, and the diameter was 130 mm and the thickness was 1.2 mm by injection molding. After the polycarbonate substrate was manufactured, film formation and lubricant application were performed in the same manner as in Example 1 to manufacture a near-field magneto-optical recording disk.

Using a near-field magneto-optical recording disk evaluation device having a detector obtained by dividing the near-field magneto-optical recording disk obtained as described above in a direction perpendicular to the beam traveling direction, optical data is transferred from the data section to the header section. When the signal of the header portion when the head entered was observed, in the case of the first and second embodiments, the signal at the time when the optical head entered the header portion could be captured as a difference signal of the split type detector. However, the disc of Comparative Example 1 could not detect the difference signal,
The timing of the header part could not be caught.

Example 3 A stamper having a track pitch of 0.45 μm in a land portion and a groove portion in a data portion and a groove depth of 65 nm and a header portion being 30 nm higher than a land portion is mounted on a mirror surface of a mold and injection-molded. By the diameter of 130mm,
A polycarbonate substrate having a substrate thickness of 1.2 mm was produced.

Using this substrate, a film was formed on both surfaces of the substrate by a sputtering method in the following manner.

First, Al-3 wt% as a reflection layer is formed on a substrate.
A Cr alloy film (50 nm thick) was formed by DC sputtering. On this, a first protective layer made of SiN is formed by Ar and N
Reactivity R using Si target in mixed atmosphere of ₂
It was formed by the F sputtering method (film thickness: 5 nm). Tb on this
_A magneto-optical recording layer of ₂₀ (Fe ₉₀ Co ₁₀ ) ₈₀ was formed by DC simultaneous sputtering of a Tb target and an Fe ₉₀ Co ₁₀ target (film thickness: 20 nm). In addition, Si
The second protective layer made of N is formed in a mixed atmosphere of Ar and N ₂ by S.
It was formed by a reactive RF sputtering method using an i target (thickness: 30 nm). A DLC layer having a refractive index of 1.85 at 633 nm was formed thereon by a reactive RF sputtering method using a C target in a mixed atmosphere of Ar and CH ₄ (film thickness: 20 nm).

Next, on the other side, the reflection layer, the first protective layer, the magneto-optical recording layer, the second protective layer, and the
C layer was formed.

After forming the DLC layer, piperonyl-modified perfluoropolyether (trade name: Fomblin: trade name, manufactured by Ausimont) using a perfluoropolyether solvent (trade name: Galden SV-70, trade name, manufactured by Ausimont) A lubricating layer was applied to a thickness of 1.5 nm by pulling up the recording medium from a 0.01 wt% solution of AM2001 ") to complete a near-field magneto-optical recording disk.

The thickness of the lubricating layer is determined by X-ray photoelectron spectroscopy (XP
Calculated by observing the C ₁ S peak intensity using S).

Example 4 A stamper having a track pitch of 0.45 μm in a land portion and a groove portion of a data portion, a groove depth of 65 nm, and a header portion 85 nm higher than a land portion was attached to a mirror surface of a mold, and a diameter was formed by injection molding. A polycarbonate substrate having a thickness of 130 mm and a substrate thickness of 1.2 mm was prepared, and a near-field magneto-optical recording disk was prepared by forming a film and applying a lubricant in the same manner as in Example 3.

Example 5 A stamper having a track pitch of 0.45 μm between the land portion and the groove portion of the data portion and having no difference in height between the land portion and the header portion was mounted on a mirror surface of a mold. After preparing a 2 mm polycarbonate substrate, UV light from a high pressure mercury lamp was 365 nm.
Irradiation was performed with an integrated light amount of 1500 mJ / cm ^{2 in} conversion.

After the UV irradiation, the height of the land portion and the header portion was measured by AFM.

Using this substrate, a near-field magneto-optical recording disk was manufactured by forming a film and applying a lubricant in the same manner as in Example 1.

Comparative Example 2 A near-field magneto-optical recording disk was produced by using the injection-molded substrate of Example 5 without UV irradiation and performing film formation and lubricant application in the same manner as in Example 3.

Using a near-field magneto-optical recording disk evaluation device having a detector obtained by dividing the near-field magneto-optical recording disk obtained as described above in a direction perpendicular to the beam traveling direction, optical data is transferred from the data section to the header section. When the signals of the header portion when the head entered were observed, in the case of Examples 3, 4 and 5, the signal at the time when the optical head entered the header portion could be captured as a difference signal of the split type detector. However, the disc of Comparative Example 2 could not detect the difference signal,
The timing of the header part could not be caught.

[0048]

According to the present invention, it is possible to obtain an optical recording disk capable of detecting the timing of the header portion when the optical head enters the header portion from the land portion by the split detection method.

Claims (8)

[Claims] An information processing apparatus comprising: a substrate having at least a land portion and a groove portion related to recording / reproducing, and a header portion for recording format information; An optical recording disk to be performed, wherein the height of a header portion and the height of a land portion are different. 2. The optical recording disk according to claim 1, wherein the height of the header portion is higher than the height of the land portion. 3. The optical recording disk according to claim 1, wherein the height of the header portion is lower than the height of the land portion. 4. The optical recording disk according to claim 1, wherein said substrate is a substrate formed by injection molding a thermoplastic resin. 5. The optical recording disk according to claim 1, wherein information is recorded on both a land portion and a groove portion. 6. The difference in height between the header portion and the land portion is as follows:
The optical recording disk according to any one of claims 1 to 5, wherein the thickness is 3 to 100 nm. 7. The optical recording disk according to claim 1, wherein the recording method is a surface recording / reproducing method. 8. The optical recording disk according to claim 1, wherein a recording method is a near-field optical recording method.