KR20060095607A - High-density information storage medium, method for manufacturing the same, apparatus and method for recording/reproducing the same - Google Patents

Abstract

Disclosed is a high density information storage medium having a small pit size and providing stable tracking, a recording / reproducing apparatus thereof, and a manufacturing method thereof.

The high density information storage medium according to the present invention includes a disc formed with lands and grooves, a first dielectric layer formed on the disc, a recording layer formed of a metal compound on the first dielectric layer, and a second dielectric layer formed on the recording layer. The recording layer is characterized in that a volume change occurs by irradiation of a laser beam to form a predetermined mark.

According to the high-density information storage medium and the manufacturing method thereof according to the present invention, it is possible to provide stable tracking using lands and grooves despite the decrease in the pit size.

Description

High-density information storage medium, method for manufacturing the same, apparatus and method for recording / reproducing the same

1 is a graph showing a push-pull signal at the time of reproduction of an optical recording medium according to the prior art.

Figure 2 is a cross-sectional view showing a layer structure of the information storage medium according to an embodiment of the present invention.

Figure 3 is a cross-sectional view showing a layer structure of the information storage medium according to another embodiment of the present invention.

4 is a view showing a state of irradiating a laser beam to the information storage medium according to the present invention.

5 is a view showing a state in which the volume deformation occurred in the recording layer of the information storage medium according to the present invention.

Figure 6 is a perspective view showing a part of the information storage medium according to the present invention.

7A to 7C show AFM images of mark patterns formed on the recording layer of the information storage medium according to the present invention;

8 is a flow chart showing a method of manufacturing a high density information storage medium according to the present invention.

9 is a view showing an example of an apparatus for recording and / or reproducing an information storage medium according to the present invention;

10 shows another example of an apparatus for recording and / or reproducing an information storage medium according to the present invention.

11 is a view showing a waveform of a push-pull signal detected in an information storage medium according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information storage medium, a method of manufacturing the same, a recording / reproducing apparatus and a method thereof, and more particularly, to a high density information storage medium having a small pit size and providing stable tracking. And to a method.

In general, an optical recording medium is used as an information storage medium of an optical pickup apparatus which performs recording / reproducing of information in a non-contact manner. Recently, due to the development of computer-related industry, the demand for new storage media with greater storage capacity is increasing.

As a method of increasing the recording capacity of such an optical recording medium, there is a method of shortening the wavelength of the recording light source, increasing the numerical aperture of the objective lens, or configuring a plurality of recording layers. Another method of increasing the recording capacity is to reduce the pit size or reduce the track pitch.

For example, a Blu-ray disc currently commercially available has a track pitch of 0.32 µm, a recording capacity of 25 GB, and a shortest recording mark of 150 nm. In order to have a storage capacity of 100 GB, the shortest recording mark is 25 GB. It should be reduced to 37.5 nm, which is a quarter size.

As one of the optical recording media for reducing the pit size and increasing the recording density, an optical recording media having a super-resolution near-field structure (Super-RENS) has been studied. The optical recording medium using the super-resolution near-field structure overcomes λ / 4NA (λ: wavelength of the light source, NA: numerical aperture of the objective lens), which is the limit of the resolution of the reproduction beam, and records as a small mark (or pit) below the resolution. Refers to an information storage medium capable of reproducing predetermined data.

However, the amplitude of the RF signal tends to decrease when the size of the pit is reduced to increase the recording capacity of the optical recording medium. In particular, when the width of the pit becomes smaller than the aperture, the amplitude of the RF signal is greatly reduced, and the carrier-to-noise ratio (C / N) is also very small. That is, according to the prior art, when the size of the pit is reduced to increase the recording capacity of the storage medium, the signal quality is deteriorated.

In addition, in order to record and / or reproduce data on the optical recording medium, the objective lens of the optical pickup unit must be tracked so that the laser beam does not escape from the pit rows. However, in the case of an information storage medium having a high resolution pit, the tracking method using a difference in reflectivity of a conventional pit, for example, a tracking method such as a push-pull method or a differential push-pull, is used. There is a problem that tracking for playback becomes unstable.

1 is a graph showing a push pull signal during reproduction of an optical recording medium having a resolution of 150 nm monotone pits or less in an optical system having a wavelength of 659 nm and a numerical aperture of 0.6. Here, the reproduction power is 2.2 mW.

Referring to FIG. 1, the push pull signal has a small amplitude of about 1V. For stable tracking, the push-pull signal must have a correct sign and sufficient value. In the conventional tracking method using the difference in reflectance of the pit, when the pit size is reduced to increase the recording capacity of the information storage medium, the push pit is shown in FIG. As described above, even though the push pull signal has a small value and is not tracked or tracked, the signal is unstable.

Accordingly, the present invention has been made to solve the above problems, a high-density information storage medium that can solve the tracking anxiety caused by the reduction in the length and width of the peak to increase the recording density, its recording / reproducing apparatus and An object of the present invention is to provide a method and a manufacturing method thereof.

In addition, the present invention provides a high-density information storage medium having improved recording density without additional cost by using existing lasers and lenses without additional reduction of laser wavelength or using lenses having a high numerical aperture to increase recording density. An object of the present invention is to provide a reproducing apparatus and method, and a manufacturing method thereof.

In order to solve the above technical problem, the high-density information storage medium of the present invention includes a disc formed with lands and grooves, a first dielectric layer formed on the disc, a recording layer formed of a metal compound on the first dielectric layer, and the recording layer on the recording layer. And a second dielectric layer formed, wherein the recording layer has a volume change caused by irradiation of a laser beam to form a predetermined mark.

Method for producing a high-density information storage medium according to the present invention comprises the steps of forming a land and groove for tracking on the disc; Coating a first dielectric layer, a recording layer and a second dielectric layer on the disc; Irradiating a laser beam to the recording layer to generate a predetermined mark by generating a volume change in the recording layer according to a difference in temperature distribution of the portion to which the beam is irradiated.

An apparatus for recording / reproducing an information storage medium having a disc having lands and grooves formed thereon and a recording layer having a predetermined mark formed through a volume change by irradiation of a laser beam, using the lands and grooves Optical pickup for irradiating a laser beam to the medium and detecting a beam reflected from the medium to perform tracking, to record or reproduce data on the information storage medium, and the optical pickup to record or reproduce data on the medium It characterized in that it comprises a control unit for controlling to.

According to another aspect of the present invention, there is provided a method of recording / reproducing an information storage medium, the method including: tracking using lands and grooves formed on the disc of the medium; And recording data on the medium or reading data from the medium by using the volume change caused by the laser beam irradiation on the medium.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

According to the present invention, a high density information storage medium, a recording / reproducing apparatus thereof, and a method of manufacturing the same are used to form a small pit of less than resolution on the disc using a disc having predetermined lands and grooves formed therein, thereby recording density of the information storage medium. It is characterized in that to enable stable tracking using the land and groove while improving.

2 is a cross-sectional view showing the layer structure of the information storage medium 100 according to an embodiment of the present invention.

2, an information storage medium 100 according to an embodiment of the present invention may include a recording layer 110 coated on a disc 105, a dielectric layer 115 coated on the recording layer 110, The conductive metal layer 120 is coated on the dielectric layer 115.

The disc 105 is formed with lands L and grooves G for tracking in advance. As is widely known, lands (L) and grooves (G) can be easily formed in the disc 105.

The recording layer 110 may be formed of an alloy dielectric layer or an alloy layer made of a dielectric and an alloy. Here, the alloy dielectric layer (or alloy layer) may comprise a rare earth metal and a transition metal. Tb may be used as the rare earth metal, and iron (Fe) and cobalt (Co) may be used as the transition metal. That is, preferably, the recording layer 110 is made of TbFeCo.

When the beam is irradiated, the recording layer 110 absorbs heat to cause a volume change in the portion to which the beam is irradiated. That is, the recording layer 110 causes chemical and physical reactions in the irradiated area due to the difference in local temperature distribution according to the irradiation of the beam, thereby causing a volume change.

The dielectric layer 115 may be formed of a metal oxide such as ZnS-SiO ₂ .

The conductive metal layer 120 is coated on the dielectric layer 115 to a thickness that can be conductive. Here, the conductive metal layer 120 may be formed of any one of Cu, Ni, Fe, Co.

3 is a cross-sectional view showing the layer structure of the information storage medium 100 according to another embodiment of the present invention.

As shown in FIG. 3, the information storage medium 100 may have first and second dielectric layers 107 and 113 formed on and under the recording layer 110. The information storage medium 100 according to another embodiment of the present invention is identical to the information storage medium 100 shown in FIG. 2 except for the plurality of first and second dielectric layers 107 and 113, and thus, the detailed description thereof. Is omitted.

4 is a view showing a state in which a laser beam is irradiated to the information storage medium 100 according to the present invention. 4 illustrates a case where a laser beam is irradiated to any one of lands or grooves of the information storage medium 100 shown in FIG. 3.

As shown in FIG. 4, a laser beam is irradiated onto the information storage medium 100 while rotating the information storage medium 100 to record predetermined data on the information storage medium 100. Here, the laser beam is focused on the recording layer 110 through the objective lens OL. As shown, the temperature distribution according to the irradiation area of the laser beam shows a Gaussian distribution, whereby the temperature of the central portion A of the laser beam is higher than its periphery.

Specifically, when the laser beam having a numerical aperture NA of 0.65 and a wavelength of 405 nm is irradiated to the information storage medium 100, when the temperature near the center of the laser beam rises above the critical temperature, the first and second dielectric layers The decomposition of ZnS-SiO ₂ constituting (107,113) occurs to generate S and O ₂ . The S and O ₂ diffuse into the recording layer 110, and the volume change occurs in the recording layer 110 due to a local gas pressure increase.

Referring to FIG. 5 showing a state where volume deformation occurs in the recording layer 110 of the information storage medium according to the present invention, the mark 125 for recording predetermined data in the recording layer 110 due to the volume change. Is formed. The volume change in the recording layer 110 also causes a volume change in the upper and lower first and second dielectric layers 107 and 113 in contact with the recording layer 110.

According to the above method, since the volume change occurs only in the portion A of the portion where the laser beam is irradiated to rise above the predetermined threshold temperature, that is, the volume change occurs only in a portion of the irradiated laser beam, the mark 125 ) Can be reduced in size. Therefore, the recording capacity of the information storage medium can be increased.

6 is a perspective view showing a part of an information storage medium according to the present invention in which a mark is recorded using the volume change. In FIG. 6, the case where predetermined mark pattern is formed in both the land L and the groove G is shown. However, it is obvious that the mark can be formed only on the groove G or the land L without being limited to the illustrated one.

Referring to FIG. 6, a predetermined mark is formed on the recording layer 110 between the first dielectric layer 107 and the second dielectric layer 113 due to the volume change caused by the laser beam irradiation. As described above, in the information storage medium according to the present invention, since a volume change occurs only in a part of the irradiated laser beam, a small size mark may be formed.

In addition, the information storage medium according to the present invention has a high density recording capacity by using the volume change, while using lands (L) and grooves (G) formed on the disc 105 during recording and / or playback. By tracking, stable tracking is possible even through a push-pull tracking technique according to the related art.

7A to 7C illustrate AFM (Atomic Force Microscopy) images of the mark pattern formed on the recording layer 110 of the information storage medium according to the present invention.

7A to 7C, the image on the left is a plan view of the mark maton formed in the recording layer 110 as viewed from above, and the graph on the right is a sectional view along the dotted line of the image on the left. 7A to 7C show mark patterns formed by incident laser beams having frequencies of 15 MHz, 18.75 MHz, and 30 MHz, respectively.

Referring to FIGS. 7A to 7C, marks are formed on the recording layer 110 having diameters of 100 nm, 80 nm, and 50 nm, and heights of 65 nm, 45 nm, and 35 nm, respectively. Considering that the shortest recording mark is 150 nm in a conventional Blu-ray disc having a recording capacity of 25 GB, the information storage medium according to the present invention can increase the recording capacity because a small size mark is formed. .

On the other hand, the method of forming the mark pattern using the volume change of the recording layer 110 can be applied not only to a ROM substrate having a pit dedicated for reproduction, but also to a rewritable disc capable of recording / reproducing.

8 is a flowchart illustrating a method of manufacturing a high density information storage medium according to the present invention.

First, lands and grooves for tracking are formed on the original plate (200).

A first dielectric layer is formed on the disc on which the lands and grooves are formed, a recording layer is coated on the first dielectric layer, and a second dielectric layer is coated on the recording layer (210). In the case where the information storage medium according to the present invention is used as a master for fabricating another information storage medium, a stamper may be formed by further coating a conductive metal layer and a plating layer on the second dielectric layer.

The laser beam is irradiated to the first dielectric layer, the recording layer, and the second dielectric layer to cause a volume change (220). As described above, the metal and the gas are decomposed in the dielectric layer by the irradiation of the laser beam, and the decomposed metal and the gas are diffused in the recording layer, thereby causing a local change in the gas pressure, which causes a volume change in the recording layer. To form a mark. The volume change in the recording layer also changes the volume of the first dielectric layer and the second dielectric layer which are in contact with the recording layer up and down. The mark resulting from this volume change is used as a pattern for recording predetermined data.

When a mark corresponding to predetermined data is recorded by irradiating a laser beam, tracking is performed using lands and grooves formed on the original plate. In the case of reproducing the information storage medium, tracking is performed by using the lands and grooves, so that stable tracking is possible as compared with conventional tracking by the difference in reflectance of the pit.

9 and 10 illustrate an example of a recording / reproducing apparatus for recording data on or reproducing data from an information storage medium according to the present invention.

Referring to FIG. 9, an apparatus for recording / reproducing an information storage medium according to the present invention includes an optical pickup 300, a recording / reproducing signal processor 400, and a controller 500.

The optical pickup 300 is a portion for detecting a beam reflected after irradiating a reproduction beam to the information storage medium (D) according to the present invention, the recording / reproduction signal processing unit 400 is detected by the optical pickup 300 The control unit 500 controls the operation of each component of the recording / reproducing apparatus.

Specifically, the optical pickup 300 is parallel to the light source 310 for irradiating the beam, the diffraction element 330 for spectroscopy the beam irradiated from the light source 310, the beam passing through the diffraction element 330 The collimating lens 52, the beam splitter 340 for converting the propagation path of the incident beam, and the objective lens for focusing the beam passing through the beam splitter 340 to the information storage medium (D) according to the present invention. Include.

The beam emitted from the light source 310 is split into the first beam and the second beam through the diffraction element 330. The power of the first beam and the second beam may be adjusted by changing the diffraction pattern of the diffraction element 330.

In addition, the optical pickup 300 is a land and a groove formed in the information storage medium (D) as described above, in order to track the objective lens of the optical pickup unit so that the laser beam for recording and / or reproduction does not deviate from the pit row. Use wealth.

The first and second beams reflected from the information storage medium D are reflected by the beam splitter 54 and received by the photodetector 360. The first and second beams received by the photodetector 360 are converted into electrical signals and output as reproduction signals through the signal processor 400.

The signal processor 400 amplifies the first beam signal photoelectrically converted through the photodetector 360 by the amplifier 410, and compensates for the time delay through the compensator 620. . The reproduction signal of the first beam and the reproduction signal of the second beam are computed through an operation unit 430, output as an RF signal through channel 1 (Ch1), and a push-pull for tracking through channel 2 (Ch2). It is output as a signal.

The controller 500 controls the optical pickup 300 to irradiate a beam of appropriate power to reproduce the mark recorded on the information storage medium according to the present invention. In addition, the controller 500 performs focusing servo and tracking servo by using the RF signal and the push-pull signal.

The recording and / or reproducing apparatus shown in FIG. 9 includes a diffraction element for generating the first and second beams, but as shown in FIG. 10, an independent first light source for irradiating the first and second beams. 380a and a second light source 380b may be provided, respectively. In FIG. 10, the first and second light sources 380a and 380b are configured as one packaged optical module.

However, the first and second light sources 380a and 380b may be independently configured without packaging, and the first and second light sources 380a and 380b may be disposed at different positions. In this case, a diffraction element may be provided. There is no need to do it.

In addition, the recording / reproducing apparatus shown in FIG. 10 includes a first light detector 370a for receiving a beam emitted from the first light source 380a and reflected from the information storage medium D, and the second light source. And a photodetector 370 having a second photodetector 370b for receiving a beam emitted from 380b and reflected from the information storage medium D.

Any one of the beams in FIGS. 9 and 10 may be used as a beam for recording / reproducing an information storage medium according to the present invention, and the other one may be used for detecting a tracking signal. As described above, when the tracking signal is detected, by using lands and grooves formed on the original plate of the information storage medium according to the present invention, a tracking signal of sufficient size can be obtained despite the small mark size.

11 illustrates waveforms of a push-pull signal detected by an information storage medium according to the present invention.

The information storage medium according to the present invention uses lands and grooves formed in the disc. Accordingly, as shown in FIG. 11, the information storage medium according to the present invention can obtain a push-pull signal having a sufficiently large amplitude, thereby enabling stable tracking.

As such, it will be understood by those skilled in the art that the present invention may be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

According to the high-density information storage medium, the recording / reproducing apparatus, and the manufacturing method thereof according to the present invention, it is possible to provide stable tracking by using lands and grooves despite the decrease in the pit size.

In addition, the present invention enables the production of a high-density information storage medium by using a conventional optical system as it is, it is possible to prevent an increase in the production cost in the production of a high-density information storage medium.

Claims (7)

In the information storage medium, A disc having lands and grooves formed thereon, a first dielectric layer formed on the disc, a recording layer formed of a metal compound on the first dielectric layer, and a second dielectric layer formed on the recording layer, The recording layer has a high density information storage medium, characterized in that the volume change occurs by irradiation of a laser beam to form a predetermined mark. The method of claim 1, The volume change is caused by diffusion of metal and gas decomposed in the first and second dielectric layers into the recording layer by irradiation of a laser beam. The method of claim 1, And the recording layer is made of a rare earth transition metal. In the method of manufacturing the information storage medium, Forming lands and grooves for tracking on the disc; Coating a first dielectric layer, a recording layer and a second dielectric layer on the disc; Irradiating a laser beam to the recording layer to generate a predetermined mark by generating a volume change in the recording layer according to a difference in temperature distribution of the portion to which the beam is irradiated. The method of claim 4, wherein Wherein the volume change is caused by diffusion of metal and gas decomposed in the first dielectric layer and the second dielectric layer into the recording layer by irradiation of a laser beam. An information storage medium recording / reproducing apparatus having an original plate having lands and grooves formed thereon, and a recording layer having a predetermined mark formed through a volume change by irradiation of a laser beam, An optical pickup for performing tracking using the lands and grooves, irradiating a laser beam to the medium and detecting a beam reflected from the medium to record or reproduce data on the information storage medium; And a control unit for controlling to record or reproduce data on the medium. In the recording / reproducing method of the information storage medium, Performing tracking using lands and grooves formed on the disc of the medium; And And recording data to or reading data from the medium by using a volume change caused by irradiation of a laser beam to the medium.

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