JPH07262621A - Optical information recording medium and production of optical information recording medium - Google Patents

Abstract

PURPOSE:To form stable grooves, to easily control each process and to facilitate inprovement in transferring property when a stamper is produced and substrate is molded. CONSTITUTION:In this information recording medium, such a method is used that information is optically recorded and reproduced and that recording is performed in both of the land part and groove part. The format signal necessary on accessing is recorded in both of the land part and groove part. In this method, the one format signal is recorded with laser light when information is recorded in a master disk 15, while the other format signal is written in a recording layer 57 after the recording layer 57 is formed on a medium substrate 56. Thus, format part 53, 58 is formed on both of the land and groove part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium in which information is recorded in both a land portion and a groove portion and an improvement in a method for manufacturing the optical information recording medium.

[0002]

2. Description of the Related Art It is essential to increase the storage capacity of an optical information recording medium, and various methods such as shortening the wavelength of a semiconductor laser have been studied in order to increase the recording density. Up to now, recording has been performed either in the continuous groove (groove) required for tracking or on the land, but recently technology for recording on both the land and the groove has been proposed (Jpn. J. Appl. Phys. Vol. 32 (1993) pp. 5324-5328). The recording density is doubled by this technique.

Optical information recording media are classified into a read-only type in which information is recorded in advance such as a CD and an optical video disc, and a recording type in which information can be recorded by a user. In the recordable medium, the user needs to have a groove that serves as a tracking guide for writing information.
Further, since information is usually managed in units of sectors, sector marks and address signals are also required. In other words, even in a recordable medium, the groove and the preformat signal as described above must be recorded in advance. Recently, a method of recording a groove with one beam and recording a pre-formatted signal on a land with the other beam using a two-beam type master recorder has been performed. A groove portion and an address pit portion are alternately used for a tracking signal so that tracking servo can be stably performed.
No. 8 and Japanese Patent Laid-Open No. 64-79953, various recording methods for group and preformat signals and shapes of grooves and pits have been considered. In the master recording, there is also a method (actual device pre-formatting) in which a format signal is not recorded but a format signal is recorded by an actual drive device in the same manner as normal information recording after the recording medium is completed.

[0004]

When recording a groove and a preformatted signal with two beams, it is not easy to obtain a stable servo signal having a sufficient amplitude due to the influence of crosstalk between the beams, and the preformatted signal is not easily obtained. Some measures must be taken on the signal or detection circuitry. In order to prevent crosstalk between the groove and the address pit of the land, there is also a method in which the groove is cut at the portion where the address pit is present and tracking is performed from the signal of the address pit. However, in order to perform the land / groove recording, it is necessary to record the format signal on both sides, and it is very difficult to control to eliminate the crosstalk between the two beams. The track pitch will continue to become narrower in the future, and the optical system of the beam will put more strain on it.

Further, when the format signals provided in each of the land portion and the groove portion are detected, if the signal amplitude levels are close to each other, a malfunction easily occurs. The present invention has been made in view of the above circumstances, and an object thereof is to produce stable grooves, facilitate control of each process, and further improve transferability when a stamper is produced and a substrate is molded. It is easy to improve, the groove and the land can be used for different purposes, the land and the groove can be surely discriminated at the time of access, and the optical information recording medium and the optical information recording medium which are easily accessible. A manufacturing method is provided.

[0006]

According to the method of the present invention, an area corresponding to an information recording land portion and an information recording groove portion of an optical information recording medium is formed on a master for producing an optical information recording medium, and the land portion is formed. The step of forming an area corresponding to the format section of the optical information recording medium in either one of the areas corresponding to the groove section (for example, the land section), and forming a substrate based on the master having the area formed A step of forming a recording layer on the surface of the substrate; and a step of forming a format part in a recording layer (eg, groove part) in which the format part is not formed among the recording layer of the land part and the recording layer of the groove part. It is a method of manufacturing an optical information recording medium.

The optical information recording medium of the present invention comprises a phase change recording layer (eg Ge, Sb, Te) or a diffusion alloyed recording layer (eg Ge, Sb, Te) and a recording film made of Bi, T.
a recording film made of e), an information recording land portion having a format portion, and an information recording groove portion having a format portion, and the polarities of the amplitude of the format signal of the land portion and the amplitude of the groove portion format signal. Are mutually opposite optical information recording media.

[0008]

In the master, an area corresponding to the format section of the optical information recording medium is formed on one of the areas corresponding to the land section and the groove section, and after forming the recording layer, the recording layer and the groove section of the land section are formed. Since the format portion is formed in the recording layer (eg, groove portion) in which the format portion is not formed among the recording layers of some portions, the step of forming both format portions is staggered. Therefore, it is possible to create stable grooves, facilitate control of each process, improve transferability when forming stampers and mold substrates, and use grooves and lands for different purposes. Even when accessing, the land and the groove can be reliably discriminated.

[0009]

【Example】

Example 1 An example of the present invention will be described below. Figure 1
Shows schematically an example of one step of the present invention.

(A) A resist 51 is applied to the glass master 15, (b) Next, areas 52a and 53a corresponding to lands and grooves are formed on the master 15, and a format portion is formed in the land corresponding area 52a. The corresponding area 54a is formed. (C) The master 15 is plated to form the stamper 55, and (d) the plastic substrate 56 is formed based on the stamper 55. (E) A recording layer 57 is formed on the substrate 56, and (f) the groove portion 52.
The format portion 58 is formed on the.

The embodiments of the present invention will be described in more detail below. FIG. 2 shows a master recording apparatus for forming a groove and a preformat in the present invention ((a) of FIG. 1,
(Corresponds to (b)). In the figure, the laser beam emitted from the laser light source 1 (for example, Ar laser or Kr
(Laser) is incident on a laser optical axis control system 2 for adjusting the optical axis to cope with fluctuations in the optical axis due to changes in the temperature of the laser. The laser is reflected by the mirror 3 and enters the two-beam splitting polarization beam splitter 4, and is split into a groove recording beam and a format recording beam (for land). Each laser beam is O or E. It is modulated into a laser beam having an arbitrary signal by beam modulation systems 5 and 6 made of O. The laser beam can now be modulated into a format signal. Next, each beam passes through beam shaping systems 7 and 8 composed of pinholes and slits to adjust the beam diameter and shape. Up to this point, the adjustment of each beam has been completed and the optical axis control is performed again at 9 and 10, and then the two beams are guided to the same optical path by the polarization beam combiner 11. To change the recording positions of the two beams, the optical axes may be shifted at 9 and 10. The two beams on the same optical path enter the beam monitor system 12, where the positional relationship of the two beams can be confirmed.
The two beams are further guided to the mirror 13 and the objective lens 1
The optical recording master 15 is focused and irradiated by 4 to record the groove and the format pattern. The optical recording master is coated with photoresist. In the figure, the shaded portion corresponds to the laser light irradiation portion.

After the laser-exposed recording master is developed,
Ag stamper and Ni electroforming are performed, and the stamper is completed after processing the surface and the end (corresponding to (c) in FIG. 1). Resin molding is performed using the stamper, and a substrate of the recording medium (for example, acrylic resin or polycarbonate resin) is manufactured (corresponding to (d) in FIG. 1). In a recording type medium, this substrate is provided with a recording layer that undergoes phase change or diffusion alloying by laser irradiation, for example. Here, an optical disc that can be recorded only with a laser beam will be described as an example.

FIG. 3 is a schematic block diagram of the optical disk drive device. The optical disc 18 is fixed to a spindle motor 19 provided in the drive device and rotated in a predetermined direction. The light emitted from the semiconductor laser 20 passes through the collimator lens 21 and is converted into parallel light. Only the vibration of the light wave parallel to the incident surface passes through the polarization beam splitter 22, and λ / 4
After being circularly polarized through the wave plate 23, it is condensed on the optical disc 18 by the objective lens 24. On the other hand, the light reflected on the optical disk 18 is changed from circularly polarized light to linearly polarized light by the λ / 4 wavelength plate 23, and its traveling direction is bent by 90 degrees by the polarization beam splitter 22. The reflected light is the detection lens 2
It passes through 5 and enters the photodetector 26. The received light is photoelectrically converted and sent as a feedback signal to the signal processing system 27 and the servo system 28. The signal processing system 27 controls various signals at the time of recording and reproducing, while the servo system controls the current flowing through the drive coil 29 to adjust the positions of the objective lens 24 and the optical disk 18, thereby tracking servo focus. Servo is applied. The part surrounded by a dotted line in the drawing is the optical system 30.

A format signal is sent to the signal processing system 27, and an optical recording medium which has not been pre-formatted is formatted and recorded by the drive device (corresponding to (f) in FIG. 1).

FIG. 4 shows a simulation result regarding a change in crosstalk value when the depth of the groove is changed. When performing land / groove recording, the biggest problem is the effect of crosstalk on both sides, but if the groove depth is set to an appropriate value, crosstalk should be reduced to such an extent that recording / playback is not affected. You can The conditions are as follows: reflectance of recorded area 1.0%, unrecorded area 20%, laser wavelength 690
nm, NA = 0.60, mark length 0.9 μm, pit pitch 1.6 μm (groove width is almost equal to land width)
And From FIG. 4, it can be seen that the crosstalk is suppressed to the minimum at about 90 nm. Conversely, unless the depth of the groove can be controlled accurately, the effect of crosstalk appears and land / groove recording is impossible.

In the master recording process, the groove,
When the format signal is recorded on both lands, 2
It is very difficult to control the beat power, and the depth of the groove varies, causing crosstalk. Therefore, in this embodiment, the format signal is applied only to the land portion and the groove portion is formed with a continuous groove having a predetermined depth. If a format signal is recorded on the recording layer of the groove portion after the recording medium is completed, land / groove recording can be performed without considering the influence of crosstalk.

Further, by completely changing the format form of the groove and the land, for example, the groove portion can be made a format suitable for audio information, and the land portion can be made a format suitable for image information. .

It is also possible to first form a pre-format of the groove portion on the master and record the format signal of the land portion on the recording layer. (Embodiment 2) FIG. 5 is a sectional view showing an embodiment of the phase change type information recording medium of the present invention. This information recording medium comprises a substrate 31 made of, for example, polycarbonate, Ge, Sb,
A ternary compound layer made of Te is provided as the recording layer 32. The recording layer 32 is crystallized in the unrecorded state, but when the laser beam 37 enters from the substrate side, the recording portion 3
No. 5 changes into an amorphous phase. Recording layer 3
2 are provided with protective layers 33, 33 made of a Si compound or the like on both sides thereof, and Au, for example, is provided between the recording layer 32 and the lower protective layer 33.
A thin semi-transparent layer 36 such as
Etc. are laminated on the reflective layer 34. With this layer structure, a reflectance change occurs in the direction in which the reflectance of the recording medium increases before and after recording, and this change is used for recording. In this recording medium, when the land recording has a format at the time of master recording, this format signal has an amplitude on the low reflectance side. Then, when a format signal is written in the groove portion by the drive device, the format signal in the land portion is generated on the upper side as shown in the reproduction signal level in FIG. That is, the polarities of the amplitude of the format signal of the land part and the amplitude of the format signal of the groove part are opposite to each other. Therefore, the signal levels of both do not overlap. (Embodiment 3) FIG. 7 is a sectional view showing an embodiment of the diffusion alloying type information recording medium of the present invention. This recording medium is, for example, a recording layer 39 of a ternary compound layer of Ge, Sb, and Te and a recording layer 40 of Bi and Te on an acrylic resin substrate 38.
Are stacked, and the recording layer is preferably sandwiched by the protective layer 42.
When this is irradiated with laser light 43, a diffusion alloying reaction occurs between the two recording layers, and a new alloy layer 41 is formed.
At this time, the reflectance of the alloy layer portion as a medium is higher than that of the unrecorded portion. This change in reflectance is used for recording. When a format for recording the master disk is present in the land portion in advance, this format signal has an amplitude on the low reflectance side. Then, when a format signal is written in the groove section by the drive device, a higher level signal is generated as shown in FIG. That is, the polarities of the amplitude of the format signal of the land part and the amplitude of the format signal of the groove part are opposite to each other. Therefore, the signal levels of both do not overlap.

[0019]

【The invention's effect】

(1) When recording on both land and groove,
In the master recording, put the format signal only on the land,
By exposing the groove with a constant power, a stable groove that is not affected by crosstalk can be manufactured.

(2) Since the process of recording the format signal is different for the land portion and the groove portion, it becomes easy to control the optical system for exposing the master and controlling the optical system when recording on the recording layer.

(3) In the master recording, the format signal is recorded only in the land portion or the groove portion,
It becomes easy to improve transferability when a stamper is produced and a substrate is molded.

(4) By changing the type of the format signal to be written to the recording layer from the format signal used for recording the master disc (the polarities of the amplitude of the land format signal and the amplitude of the groove format signal are opposite to each other). That is, the groove portion and the land portion can be used for different purposes, and the land portion and the groove portion can be surely discriminated even at the time of access.

(5) Since the format of the groove portion is recorded on the master disc and the format of the land portion is performed by the actual drive device, a clear difference can be given to the reproduced signal levels of both format signals, so that it is easy to access. Become.

[Brief description of drawings]

FIG. 1 is an explanatory view sequentially showing an example of steps of a method of the present invention.

FIG. 2 is a diagram showing a master recording device that forms a groove and a preformat.

FIG. 3 is a schematic configuration diagram of an optical disk drive device.

FIG. 4 is a diagram showing a simulation result regarding a change in crosstalk value when a groove depth is changed.

FIG. 5 is a sectional view showing an embodiment of the phase change type information recording medium of the present invention.

FIG. 6 is a diagram showing format signal levels of a land portion and a groove portion in the phase change type information recording medium of the present invention.

FIG. 7 is a sectional view showing an embodiment of a diffusion alloying type information recording medium of the present invention.

FIG. 8 is a diagram showing format signal levels of a land portion and a groove portion in the diffusion alloying type information recording medium of the present invention.

[Explanation of symbols]

1 ... Laser light source, 2 ... Optical axis control system, 3, 13 ... Reflecting mirror, 4 ... Polarization beam splitter, 5, 6 ... Beam modulator, 7, 8 ... Beam shaper, 9, 10 ... Optical axis control system, 1
1 ... Polarized beam combiner, 12 ... Beam monitor system,
14 ... Objective lens, 15 ... Recording master, 18 ... Optical disc, 19 ... Spindle motor, 20 ... Semiconductor laser, 2
1 ... Collimating lens, 22 ... Polarized beam splitter,
23 ... λ / 4 plate, 24 ... Objective lens, 25 ... Detection lens, 26 ... Photoreceiver, 27 ... Signal processing system, 28 ... Servo system, 29 ... Drive coil, 30 ... Optical system, 31 ... Substrate, 3
2 ... Recording layer, 33 ... Protective layer, 34 ... Reflective layer, 35 ... Recording part, 36 ... Semitransparent layer, 37 ... Laser beam, 38 ... Substrate,
39 ... 1st recording layer, 40 ... 2nd recording layer, 41 ... Alloy layer,
42 ... Protective layer, 43 ... Laser light, 51 ... Resist, 52
... land portion, 53 ... groove portion, 54 ... land portion format portion, 55 ... stamper, 56 ... substrate, 57 ... recording layer, 58 ... groove portion format portion.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G11B 7/26 7215-5D 20/12 9295-5D

Claims (7)

[Claims] 1. An information recording land section having a format section and an information recording groove section having a format section, wherein the polarities of the amplitude of the format signal of the land section and the amplitude of the groove section format signal are opposite to each other. An optical information recording medium. 2. The optical information recording medium according to claim 1, further comprising a phase change recording layer. 3. The phase change recording layer is made of Ge, Sb, Te
The optical information recording medium according to claim 1, further comprising: 4. The optical information recording medium according to claim 1, further comprising a diffusion alloyed recording layer. 5. The diffusion alloyed recording layer comprises Ge, Sb,
The optical information recording medium according to claim 1, comprising a recording film made of Te and a recording film made of Bi, Te. 6. An optical information recording medium forming master is provided with an area corresponding to an information recording land portion and an information recording groove portion of the optical information recording medium, and an area corresponding to a format portion of the land portion. A step of forming one of the areas corresponding to the format section of the groove section, a step of forming a substrate on the basis of the master having formed the area, and forming a recording layer on the surface of the formed substrate; A method of manufacturing an optical information recording medium, comprising a step of forming a format part in a recording layer in which the format part is not formed among the recording layer and the recording layer of the groove part. 7. A step of forming an area corresponding to a format portion of an information recording land portion of an optical information recording medium on a master for making an optical information recording medium, and a substrate is formed on the basis of the master on which the area is formed. A method of manufacturing an optical information recording medium, comprising: a step of forming a recording layer on the surface of the formed substrate; and a step of forming a format part in the recording layer of the groove part.