KR100628100B1 - Optical record medium of high resolution - Google Patents

Abstract

The present invention relates to a super resolution optical recording medium. The present invention relates to a super resolution optical recording medium in which a plurality of layers are stacked on a substrate to generate a mark below a diffraction limit of light, and to record. A recording layer formed by Mo, Te, O, and a third metal element; And a reproducing layer including any one of a nonlinear optical material, a thermochromic material, and a phase change material to enable super resolution when light is irradiated onto the recording layer. It provides a maritime optical recording medium. According to the super-resolution optical recording medium according to the present invention, since the recording mark is not generated in a large bubble-like bulge but the shape of the mark is generated uniformly, the super-resolution optical recording medium can have good reproduction signal quality. In addition, the recording can be stored for a long time in the recording layer.

Super Resolution, Optical Recording Media

Description

Optical record medium of high resolution

1 is a cross-sectional view showing a constituent material and a cross-sectional structure of a conventional optical recording medium

2 is a cross-sectional view showing a constituent material and a cross-sectional structure of an embodiment of an optical recording medium according to the present invention.

Figure 3 is a cross-sectional view showing a constituent material and a cross-sectional structure of another embodiment of an optical recording medium according to the present invention

Figure 4 is a cross-sectional view showing a constituent material and a cross-sectional structure of another embodiment of an optical recording medium according to the present invention

<Description of Symbols for Main Parts of Drawing>

10: substrate 20: reflective layer

30a, 30b, 30c, 30d: dielectric layer

40: light transmitting layer

50: recording layer 60, 60a, 60b: reproduction layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super resolution optical recording medium, and more particularly, to a super resolution optical recording medium for recording with a mark below a diffraction limit of light, and irradiating light to the optical recording medium. It is about.

 Representative examples of optical recording media that are currently developed or commercialized include digital versatile discs (DVDs) using red lasers and BD (Blu-ray discs; BDs) using blue lasers for recording and playback. . The storage capacity of the optical recording medium is 4.7 gigabytes (GB) or less, and the DVD class is about 25 GB. Optical recording media can record more than 100GB in one CD size after 2005, and terabytes (TB) or more in one CD size after 2010. However, in order to store high-density digital video as signal flow information, an information storage medium capable of storing a capacity of 20 GB or more and recording information according to a data transmission speed of 25 Mbps or more is required.

Currently, multi-functional information storage technology is being developed in various forms in various multimedia environments. Among them, the optical recording medium can be attached to and detached from the playback apparatus and can store a large amount of information. In addition, since random access to recording is possible during reproduction, reliability of recorded data is maintained, and cost is low, it is the most popular among various information storage methods.

The optical recording medium must be able to reduce the size of the recording pit to increase the recording density. To reduce the recording pit, the incident laser beam size should be reduced, which is proportional to the laser wavelength (λ) and inversely proportional to the objective aperture numerical aperture (NA) (d∝λ / NA, where d is the laser Beam size, λ wavelength, NA is the numerical aperture of the lens). Therefore, the wavelength of the laser beam has been reduced or the numerical aperture has been increased to reduce the size of the laser beam. In order to obtain a high density storage medium, a short wavelength laser must be used for recording and reproducing. However, achieving high density recordings using short wavelength lasers (blue lasers (405 nm)) and high numerical apertures (NA = 0.85) has almost reached the theoretical limit and new technologies are needed to achieve higher storage capacities. . Therefore, it is an optical recording medium that is compatible with existing CD and DVD players and can store high density information hundreds of times higher than the initial CD storage capacity of 650MB. There is a new research trend.

Such a super resolution optical recording medium is expected to increase the storage density by dramatically reducing the recording mark size while using the existing laser optical pickup system. In the conventional write once read many (WORM) super-resolution optical recording media, recording marks are formed in the recording layer in a bubble form. The bubble mark is formed by separating a nano-sized metal particles (eg, Pt) and a combination of oxygen or nitrogen into nanoparticles at a specific temperature or more. It is also known to reproduce small marks by forming an aperture of a small size below the diffraction limit using a material having nonlinear optical properties or thermal behavior.

Referring to Fig. 1, the structure of a conventional super resolution optical recording medium will be described. 1 shows a cross-sectional structure of a conventional super resolution optical recording medium. The conventional super resolution optical recording medium includes a substrate 10, a reflective layer 20, dielectric layers 30a, 30b, 30c, a light transmitting layer 40, a recording layer 50, and a reproduction layer 60. The laser beam is incident on the optical recording medium through the light transmitting layer 40, reaches the reflective layer 20, and is reflected back.

In the conventional recording super resolution optical recording medium, PtOx (oxide of Pt) is used as the material of the recording layer 50. However, when a laser beam is irradiated to a conventional optical recording medium including the above-described constituent material, a bubble-shaped mark having a large swelling is formed. In addition, the bubble shape mark has a problem that the signal quality is not good because the shape of the bubble mark is uneven.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a super-resolution optical recording medium which does not generate large bubble-like swelling and has a uniform shape of a mark, which can have a good reproduction signal quality. To provide.

It is another object of the present invention to provide a super resolution optical recording medium comprising a material in which a recording can be stored for a long time in the recording layer of the super resolution optical recording medium.

In order to achieve the above object, the present invention stacks a plurality of layers on a substrate to generate and record a mark below the diffraction limit of light, and super-resolution optical recording to reproduce the record by irradiating light to the mark. Claims: 1. A medium comprising: a recording layer formed of tellurium (Te), oxygen (O), and a third metal element; And a reproducing layer including any one of a nonlinear optical material, a thermochromic material, and a phase change material to enable super resolution when light is irradiated onto the recording layer. It provides a maritime optical recording medium.

The third metal element of the recording layer is silver (Ag), gold (Au), tungsten (W), manganese (Mn), platinum (Pt), titanium (Ti), zirconium (Zr), bromine (B). ), Chromium (Cr), Iron (Fe), Cobalt (Co), Nickel (Ni), Palladium (Pd), Antimony (Sb), Tantium (Ta), Aluminum (Al), Idium (ln) It is preferably at least one element selected from the group consisting of (Cu), tin (Sn), zinc (Zn), and bis (Bi). When the third metal element is added to the tellurium (Te) and the oxygen (O) included in the recording layer, good recording characteristics can be obtained because the recording mark is not generated in a large bubble form.

The content ratio of O contained in the recording layer is preferably 25 atomic% or more and 60 atomic% or less. The third metal element added to Te and O in the recording layer is preferably 1 atom% or more and 35 atom% or less.

In addition, the thickness of the recording layer is preferably 1 nm or more and 30 nm or less.

The regeneration layer is preferably formed of at least one element selected from the group consisting of germanium (Ge), antimony (Sb), and tellurium (Te).

The reproduction layer may be stacked at any one or more positions close to the substrate or far from the substrate with respect to the recording layer. When the regeneration layer is laminated at the position, the thickness of the regeneration layer is preferably 3 nm or more and 200 nm or less.

Dielectric layers may be laminated on both contact surfaces of the recording layer. In addition, the optical recording medium is preferably a write-once type (WORM) optical recording medium.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention which can achieve the above object will be described.

An embodiment of a super resolution optical recording medium according to the present invention will be described with reference to FIG. 2.

One embodiment of the super-resolution optical recording medium according to the present invention is a disk shape having an outer diameter of about 120 mm and a thickness of about 1.2 mm, and has a reflective layer 20, a dielectric layer 30a, a recording layer 50, The dielectric layer 30b, the regeneration layer 60, the dielectric layer 30c, and the light transmitting layer 40 can be stacked in this order. The wavelength of the laser beam used in the super-resolution optical recording medium is between 380 and 450 nm, preferably about 405 nm. ) To record or play back. In the case of recording and reproducing data on the optical recording medium, an objective lens having a numerical aperture of 0.7 or more, preferably about 0.85, is used, whereby the beam spot of the laser beam on the recording layer is about 0.4 mu m in size.

The substrate 10 uses a disk-shaped substrate of about 0.6 to 1.1 mm in order to secure the thickness of the optical recording medium. The surface of the substrate 10 is helically formed with grooves and lands for guiding the laser from the center to the outer circumferential direction or vice versa. As a constituent material of the substrate 10, various materials such as glass, ceramic, resin, etc. can be used, but they are light, have good injection properties, and have low birefringence when the laser is incident, resulting in a carrier-to-noise ratio (CNR). Use polycarbonate with great properties. It is preferable to use the injection molding method using a stamper for the production of the substrate, but other methods such as the photopolymer method may be possible.

The reflective layer 20 reflects the laser beam incident from the light transmitting layer 40 so that the laser beam is emitted to the light transmitting layer 40 again. Magnesium, aluminum, titanium, chromium, iron, cobalt, nickel, copper, zinc, germanium, silver, platinum, and the like may be used as constituent materials of the reflective layer 20. In order to obtain a high reflectivity among these, it is preferable to use metal materials, such as aluminum, gold, silver, copper, or its alloy. In the super resolution optical recording medium according to the present invention, it is not necessary to provide the reflective layer 20 therein. However, if the reflective layer 20 is provided, the reflectance of the incident laser beam is secured, and thus a high reproduction signal (C / N ratio) can be obtained by the multi-interference effect during optical recording and reproduction. It is preferable that it is 5-300 nm, and, as for the thickness of the said reflection layer 20, it is more preferable that it is 20-200 nm. When the thickness of the reflective layer 20 is less than 5 nm, the above effects cannot be sufficiently obtained, whereas when the thickness of the reflective layer 20 is 300 nm or more, the surface property of the reflective layer 20 is not only lowered, but the deposition time is longer and productivity is lowered. There is a disadvantage.

The dielectric layers 30a, 30b, and 30c serve to physically or chemically protect the recording layer 50 and the reproduction layer 60 positioned between the dielectric layers 30a, 30b, and 30c, and are recorded on the optical recording medium. Prevent deterioration of information. The material of the dielectric layers 30a, 30b, 30c is not particularly limited as long as it is a transparent dielectric which transmits the laser beam to the wavelength region of the laser beam used in recording and reproduction. For example, oxides, emulsions, nitrides or combinations thereof can be used as the main component. However, from the viewpoint of preventing heat deformation of the substrate 10 and the like and protecting characteristics of the recording layer 50, Al ₂ O ₃ , AlN, ZnO, ZnS, GeN, GeCrN, CeO ₂ , SiO, SiO ₂ , Si _{3 N 4, SiC, La 2} O 3, TaO, it is preferable to use an oxide, sulfide, nitride, etc., or a mixture thereof, such as TiO _2, such as aluminum, silicon, cerium, titanium, zinc, tantalum. More preferably, a mixture of ZnS and SiO ₂ is used. When using a mixture of ZnS and SiO ₂ molar ratio of ZnS and SiO ₂ it is particularly preferably set to about 80:20. The material of each dielectric layer 30a or 30b or 30c may be the same as each other, or may be composed of different materials if included in the material. Although the thickness of each dielectric layer 30a, 30b, 30c does not need to be specifically limited, It is preferable to set it as 3-200 nm. When the thickness of the dielectric layers 30a, 30b, and 30c is less than 3 nm, it may be difficult to obtain the effects of the dielectric layer. If the thickness of the dielectric layer is more than 200 nm, the deposition time may be long and productivity may be deteriorated. This is because cracks may occur depending on the stress.

The recording layer 50 is a layer on which recording marks are formed, and in the case of a WORM optical recording medium, irreversible recording marks are formed. When a laser having a predetermined power is irradiated onto the recording layer 50, the two constituent materials are partially or wholly mixed to form a recording mark on the recording layer 50. In addition, recording and reproduction are possible by the difference in reflectance between the recording mark and the portion not irradiated with the laser beam.

The optical recording medium according to the present invention includes tellurium (Te) and oxygen (O) as constituents of the recording layer 50. When TeOx (oxide of Te) is used as a main component of the recording layer, the intensity of the laser light is raised in an amorphous state after film formation without performing an initialization process such as a laser anneal process on the recording layer 50. When changed and irradiated, a mark of crystalline form can be formed. Since the above process is an irreversible process, it becomes an important characteristic of the write once type recording medium which cannot be corrected or erased. The recording film is also preferable in terms of production cost because the recording film has high moisture resistance and high reliability in recording and holding against environmental changes, and the recording material enables recording with a single layer film. However, using TeOx for the recording layer requires some time until crystallization of the recording film by laser irradiation is sufficient for the recording layer 50, which may be inappropriate as a recording medium for which high-speed response is required. Therefore, in order to compensate for the above drawback, a third element (M) is added to TeOx. The third element (M) is silver (Ag), gold (Au), tungsten (W), manganese (Mn), platinum (Pt), titanium (Ti), zirconium (Zr), bromine (B), Chromium (Cr), Iron (Fe), Cobalt (Co), Nickel (Ni), Palladium (Pd), Antimony (Sb), Tantium (Ta), Aluminum (Al), Idium (ln), Cooper It is preferably at least one element selected from the group consisting of (Cu), tin (Sn), zinc (Zn), and bis Earth (Bi). The additive element (M) may promote the growth of the Te crystals to form the grains of Te-M at high speed. Therefore, the material contained in the recording layer 50 can be crystallized at high speed to record, and high speed response can be obtained. In addition, the elements added to Te and O included in the recording layer 50 are metal materials, so that bulging of the recording marks is not largely generated, and the recording marks can be stored for a long time.

In order to sufficiently obtain the above effects, the content of O contained in the recording layer is preferably 25 atomic% or more and 60 atomic% or less. The proportion of elements added to Te and O in the recording layer is preferably 1 atom% or more and 35 atom% or less.

Although the thickness of the recording layer 50 is not particularly limited, in order to sufficiently suppress the noise level of the reproduction signal, to ensure sufficient recording sensitivity, and to sufficiently increase the reflectance change before and after recording, the thickness of each layer is 1 to 30 nm. It is preferable to form in the range.

The regeneration layer 60 includes a material that enables super resolution, and the constituent material used for the regeneration layer 60 is a nonlinear optical material or a thermochromic material whose optical properties change depending on a temperature distribution. Or a phase change material may be used. As the material of the regeneration layer, a material containing at least one of Ge, Sb, and Te may be used. The reproduction layer 60 may be above, below, or both of the recording layer 50 when viewed in the stacking order from the substrate in the direction in which the laser beam is incident. The thickness of the regeneration layer 60 does not need to be particularly limited, but is preferably 3 to 200 nm in order to sufficiently obtain an optical change rate during regeneration while sufficiently generating a super resolution phenomenon.

In order to form the reflective layer 20, the dielectric layers 30a, 30b, 30c, the recording layer 50, and the reproduction layer 60, an image growth method using chemical species contained in the constituent materials of the above-described layers may be used. For example, a sputtering method or a vacuum deposition method can be used, and sputtering method is more preferable.

The light transmissive layer 40 constitutes an incident surface of the laser beam and is a layer which becomes an optical path of the laser beam, and the thickness thereof is preferably about 100 μm to 0.6 mm. The material of the light transmitting layer 40 is not particularly limited as long as the light transmittance is sufficiently high in the wavelength range of the laser beam for recording and reproduction, and the acrylic or epoxy ultraviolet curable resin may be used as the light transmitting layer 40. It is preferable to use as a constituent material of. Alternatively, a light-transmissive sheet made of a light-transmissive resin and various adhesives or pressure-sensitive adhesives may be used.

Referring to Figure 3, another embodiment of a super resolution optical recording medium according to the present invention will be described. FIG. 3 shows a cross-sectional structure of the super resolution optical recording medium as shown in FIG. 2, but shows that the positions of the recording layer 50 and the reproduction layer 60 are changed. As described above, the recording layer 50 and the reproduction layer 60 are positioned closer to the substrate 10 than the reproduction layer 60 when viewed in the direction in which the laser beam is incident from the substrate 10. The reproduction layer 60 may be located closer to the substrate 10 than the recording layer 50.

4 shows a cross-sectional structure of another embodiment of a super resolution optical recording medium according to the present invention. In FIG. 4, the recording layer 50 is located closer to the light transmitting layer 40 than to one reproduction layer 60a and closer to the substrate 10 than to another reproduction layer 60b. In addition, both surfaces of each recording layer 50 and the reproduction layers 60a and 60b can be stacked in contact with the dielectric layers 30a, 30b, 30c and 30d, respectively.

It is easy for a person skilled in the art to change or modify the present invention from the present specification. Thus, although an embodiment of the present invention has been described above clearly, various modifications thereof should be made without departing from the spirit and the scope of the invention.

The effects of the super resolution optical recording medium according to the present invention described above are as follows.

First, according to the super-resolution optical recording medium according to the present invention, since the recording mark is not generated with a large bubble-like bulge but the shape of the mark is uniformly produced, the super-resolution optical recording medium can have good reproduction signal quality. have.

Secondly, according to the super-resolution optical recording medium according to the present invention, recording can be stored for a long time in the recording layer.

Claims (11)

In a super-resolution optical recording medium in which a plurality of layers are stacked on a substrate to generate a mark below a diffraction limit of light, and to record, and to reproduce the record by irradiating light to the mark. A recording layer formed by tellurium (Te), oxygen (O), and a third metal element; And A super-resolution comprising a non-linear optical material, a thermochromic material, or a phase change material, and a reproducing layer to enable super resolution when light is irradiated onto the recording layer. Optical record carrier. The method of claim 1, The third metal element of the recording layer is silver (Ag), gold (Au), tungsten (W), manganese (Mn), platinum (Pt), titanium (Ti), zirconium (Zr), bromine (B). ), Chromium (Cr), Iron (Fe), Cobalt (Co), Nickel (Ni), Palladium (Pd), Antimony (Sb), Tantium (Ta), Aluminum (Al), Idium (ln) , At least one element selected from the group consisting of (Cu), tin (Sn), zinc (Zn), and bis (Bi). The method of claim 2, And the content ratio of the third metal element in the recording layer is 1 atom% or more and 35% or less. The method of claim 1, A super-resolution optical recording medium, characterized in that the content rate of the oxygen (O) element in the recording layer is 25 atomic% or more and 60 atomic% or less. The method of claim 1, The reproduction layer is a super-resolution optical recording medium, characterized in that formed of at least one element selected from the group consisting of germanium (Ge), antimony (Sb), tellurium (Te). The method of claim 1, And the recording layer has a thickness of 1 nm or more and 30 nm or less. The method of claim 1, And the reproduction layer is laminated at any one or more positions close to the substrate or far from the substrate with respect to the recording layer. The method of claim 1, And the reproducing layer has a thickness of 3 nm or more and 200 nm or less. The method of claim 1, The super resolution optical recording medium further comprises a reflective layer positioned in contact with the substrate and reflecting and emitting a laser beam incident on the super resolution optical recording medium. The method of claim 1, And said super resolution optical recording medium comprises a dielectric layer laminated on both contact surfaces of the recording layer. The method of claim 1, The optical recording medium is a super-resolution optical recording medium, characterized in that the write-once optical recording medium.

Images