KR100617136B1 - Optical record medium - Google Patents

Abstract

The present invention relates to an optical recording medium for recording information as a mechanism for generating a new material having a different reflectance from the surroundings in the recording layer when the laser beam is irradiated. The present invention provides an optical recording medium for recording information as a mechanism for generating a new material having a different reflectance from the surroundings in a recording layer when a laser beam is irradiated, comprising: a substrate; A reflective layer positioned adjacent to the substrate to reflect an incident laser beam; and an information recording layer positioned on the reflection, wherein the information recording layer is one selected from the group consisting of Si, Ge, C, Sn, and Zn. A first recording layer containing 50 atomic% or more of the element as a main element; And a second recording layer containing 50 atomic% or more of Au as a main element. According to the optical recording medium according to the present invention, not only can data be recorded at high density, but also data can be recorded with high recording stability and high recording sensitivity.

Optical recording media, Blu-ray Disc. , Cardinal

Description

Optical Record Medium

1 is a structural diagram showing an embodiment of the structure of an optical recording medium according to the present invention;

2 is a schematic diagram showing one form in which a recording mark is generated when land recording is performed on an optical recording medium according to the present invention;

3 is a schematic diagram showing one form in which a recording mark is generated when groove recording is performed on an optical recording medium according to the present invention;

4 is a schematic diagram showing one form in which a recording mark is generated when the recording sensitivity promoting layer is included in the optical recording medium according to the present invention.

5 is a schematic diagram showing one form in which a recording mark is generated when the first recording layer and the second recording layer are alternately laminated on the information recording layer of the optical recording medium according to the present invention.

6 is a structural diagram showing another embodiment of the structure of the optical recording medium according to the present invention;

FIG. 7 shows the results of measuring recording sensitivity with DC annealing power for each experiment of Table 1. FIG.

8 is a view showing a result of reflectance change of an optical recording medium according to the present invention having a recording layer of Ge (150Å) / Au (50Å) when the thickness combination of the upper dielectric layer and the lower dielectric layer is changed;

9 is a view showing a result of reflectance change of an optical recording medium according to the present invention having a recording layer of Ge (90Å) / Au (30Å) when the thickness combination of the upper dielectric layer and the lower dielectric layer is changed;

FIG. 10 is a view showing the rate of change of reflectivity before and after recording of an optical recording medium according to the present invention having a recording layer of Ge (90Å) / Au (30Å) when the thickness combination of the upper dielectric layer and the lower dielectric layer changes.

FIG. 11 shows waveforms of a laser recording pulse used for data recording of the optical recording medium for performance evaluation of the optical recording medium according to the present invention. FIG.

12 shows the results of an RF eye pattern of an optical recording medium having a combination of Experimental No. 3 in Table 1. FIG.

FIG. 13 is a diagram showing a probability distribution of a signal reproduced from an optical recording medium having a combination of Experiment NO.3 in Table 1. FIG.

<Description of Symbols for Main Parts of Drawing>

10: light transmitting layer 20, 22: lower dielectric layer

30,32: upper dielectric layer 40: separation layer

50: reflective layer 60: substrate

70: record sensitivity promoting layer 90: record mark

100,200: Information recording layer

110,112,210: first recording layer 120,220: second recording layer

The present invention relates to an optical recording medium, and more particularly, to a recordable optical recording medium capable of densely recording data while having high recording stability.

With the advent of the multimedia era comprehensively dealing with video signals, audio signals and computer data information including moving images and still images, package media such as CDs and DVDs and other various disks have already been widely used. Recently, attempts have been made to apply optical recording media as recording media for mobile phones, digital cameras, broadcasting and movies. This trend will be more prominent in the next generation of media.

Such optical recording media include a read-only memory (ROM) and a recordable optical recording medium capable of recording information only once, and a rewritable type capable of repeatedly writing, reading and erasing information. ) There is an optical recording medium.

Among the optical recording media, the reproducing optical recording media have servo, positional information, or fine grooves in the pit shape in the circumferential direction, and a reflective layer is present in the optical recording media. The recording layer material of the recordable type optical record carrier, which is expected to be used for data backup, broadcast, movie collection, etc., may be organic or inorganic. However, when an organic material is used as the recording layer material, problems may occur in long term storage of data recorded on the optical recording medium.

The recording mechanism of a recordable optical recording medium may be a) recording material is burned to produce pit, b) recording material is decomposed, and volume is expanded to produce a pit, or c) the recording layer is melted. And then solidified to form new phases, or d) the formation of new materials by reaction at the interface of the dissimilar material (eg silicide, germanide, antimonide). In addition, the above mechanism may occur in combination. The recording mark is generated by a complex mechanism. When the laser beam is irradiated onto the optical recording medium, the first material and the second material in the recording layer are mixed in a state change to produce a material having different optical characteristics from the surroundings of the recording layer. There is a case. In this case, therefore, data is recorded by the changed optical properties of the recording material, and the recorded data can be read out as a change in reflectance by the changed optical properties before and after recording. In order to occur in the optical recording medium by the complex mechanism described above, the optical recording medium must have a combination of an internal structure in which the mechanism can occur and a recording material suitable for the internal structure.

Next-generation recording media require very high recording densities and data transfer rates. In order to increase the recording density recorded on the optical recording medium, the size of the recording mark in the optical recording medium should be smaller than the present. Therefore, the laser wavelength irradiated on the optical recording medium should be shortened to 450 nm or less, and the numerical aperture should be larger than 0.7. In addition, the data rate must be much higher than the current 30-35 Mbps.

BD (Blu-ray Disc.), One of the next generation recording media, has acceptable jitter within the range of 5.28m / s to 10.56m / s and laser power 3-7mW at 405nm wavelength. Records having the characteristics of must be included in the optical record carrier. In particular, in the recordable optical recording medium having the above characteristics, i) the constrast between the recording mark and the space in the optical recording medium must be large, ii) the recording sensitivity must be high, V) Recorded marks should have mark stability, and v) recording mark noise and recording characteristics including jitter should be satisfactory in the BD system.

In addition, when a laser is irradiated to the optical recording medium to make a recording mark in the optical recording medium, the laser power required to make the recording mark should not be too high.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical recording medium having the characteristics of a BD system, wherein when the laser is irradiated to the optical recording medium, the material in the recording layer of the optical recording medium is deformed and its volume is expanded to generate pit. When the recording layer is melted and then solidified, a new phase is generated, or a mechanism in which a heterogeneous material contained in the recording layer reacts with each other on a contact surface is generated to produce a new material, resulting in a complex recording mark in the optical recording medium. It is to provide an optical recording medium is generated.

It is another object of the present invention to provide an optical recording medium in which recording marks are generated by the above-described mechanism, while satisfying BD characteristics and having a large constrast between mark and space, and recording sensitivity. It is to provide a high optical recording medium.

It is still another object of the present invention to provide an optical recording medium that satisfies BD characteristics and has excellent recording characteristics such as mark stability and jitter of recording marks of the optical recording medium.

It is still another object of the present invention to provide an optical recording medium in which the laser power required for making a recording mark is not too high even if it has the above recording characteristics.

In order to achieve the above object, the present invention provides an optical recording medium for recording information by a mechanism for generating a new material having a different reflectance from the surroundings in a recording layer when a laser beam is irradiated, the optical recording medium comprising: a substrate; A reflective layer positioned adjacent to the substrate to reflect an incident laser beam; and an information recording layer positioned on the reflection, wherein the information recording layer is one selected from the group consisting of Si, Ge, C, Sn, and Zn. A first recording layer containing the above elements; And a second recording layer containing 50 atomic% or more of Au as a main element.

More preferably, the first recording layer contains 50 atomic% or more of one element selected from the group consisting of Si, Ge, C, Sn, and Zn as main elements.

In addition, when the atomic% of Au of the second recording layer is less than 100, the second recording layer may include at least one element selected from the group consisting of Si, Sb, Te, Ge, Al, and Cu as an additional element. . The most preferred proportion of the additive element is at least 0.01 atomic% and less than 50 atomic%. The mechanism generated when the recording mark is generated on the optical recording medium according to the present invention is more pronounced when the first recording layer contains one element selected from the group consisting of Si, Ge, C, Sn, and Zn as a main component, This is because the recording mark of the optical recording medium can be easily generated.

The information recording layer includes at least one first recording layer and at least one second recording layer, wherein the first recording layer and the second recording layer are alternately stacked with each other so that the first recording layer and the second recording layer. It is preferable that the contact surface between them is two or more. In the case of having two or more contact surfaces, the reaction area between the materials of the two recording layers is increased, so that recording marks are easily generated in the thickness direction of the optical recording medium. Further, in order for the recording mark to have a constant reflectivity with respect to the laser beam, the thickness ratio of the first recording layer to the thickness of the second recording layer of the information recording layer is preferably 2 or more.

The information recording layer further includes a recording sensitivity promoting layer including at least one element selected from the group consisting of Sn, Zn, Pb, Bi, Tl, Te, Se, S, Al, Ga, Ge, Cd, I, In. It is desirable to do. The recording sensitivity promoting layer may be located on either of the two contact planes of the first recording layer or the two contact planes of the second recording layer, but is preferably located on the first incident surface of the laser of the information recording layer. The materials included in the recording sensitivity promoting layer have a low melting point, so that when the laser beam is irradiated, the materials react before the materials included in each recording layer, and the latent heat by the reaction supplies a gap required for the reaction of the recording layer. In addition, the laser power required for generating the recording mark can be lowered.

In the optical recording medium according to the present invention, it is preferable to stack the dielectric layer in contact with at least one or more of the surfaces of which the laser beam of the information recording layer is first incident or close to the substrate. The dielectric layer serves to prevent damage to the substrate or plastic cover layer due to the temperature rise of the recording layer according to the above position, or to control the thermal equilibrium of the recording layer by releasing heat generated from the recording layer at an appropriate rate. do.

In addition, to achieve the above object, the present invention provides an optical recording medium for recording information by a mechanism for generating a new material having a different reflectance from the surroundings in the information recording layer when the laser beam is irradiated, the optical recording medium comprising: a substrate; A reflective layer positioned adjacent to the substrate to reflect an incident laser beam; and two or more information recording layers positioned on the reflection; And a separation layer stacked between neighboring information recording layers of the two or more information recording layers, wherein each information recording layer includes at least one element selected from the group consisting of Si, Ge, C, Sn, and Zn. A first recording layer; And a second recording layer containing 50 atomic% or more of Au as a main element.

Therefore, the ratio of the thickness of the first recording layer to the thickness of the second recording layer in any one of the two or more information recording layers of the optical recording medium is equal to the thickness of the first recording layer of the other information recording layer and the second. It is preferable that it is different from the ratio of the thickness of the recording layer. Also, the sum of the thickness of the first recording layer and the thickness of the second recording layer in any one of the two or more information recording layers of the optical recording medium is the first recording layer thickness and the second recording layer of the other information recording layer. It is desirable to differ from the sum of the thicknesses.

In addition, it is preferable that the optical recording medium according to the present invention having the above characteristics is a recordable optical recording medium.

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

Referring to FIG. 1, an embodiment of a structure of an optical recording medium according to the present invention will be described. In an embodiment of the structure of the optical recording medium according to the present invention, the optical recording medium includes a substrate 60, a reflective layer 50, and an information recording layer 100. In addition, it is preferable to further include the light transmitting layer 10 and the dielectric layers (20, 30). The information recording layer 100 includes a first recording layer 110 and a second recording layer 120.

In the optical recording medium, the substrate 60 serves to support the physical shape of the optical recording medium. Ceramic, glass, resin, and the like are generally used for the substrate 60, and it is preferable to use polycarbonate resin as a material. The reflective layer 50 is positioned on the substrate 60, reflects the laser beam incident on the optical recording medium through the light transmitting layer 10, and emits the laser beam toward the light transmitting layer 10. The layer 10 is preferably made of a material with high reflectivity or an alloy with a high reflectivity.

The information recording layer 100 is positioned on the reflective layer 50 and may include two or more recording layers 110 and 120. The recording layer included in the information recording layer 100 is referred to as a first recording layer 110 and a second recording layer 120 for convenience of description. Each material included in the first recording layer 110 and the second recording layer 120 is mixed with each other when irradiated with a laser beam to form a new material, and the new material has a completely different reflectance from the surrounding material. Have The positions of the first recording layer 110 and the second recording layer 120 in the information recording layer 100 of FIG. 1 may be interchanged with each other, and the first recording layer must be positioned on the side of receiving the laser beam first. It is not limited to a structure. The first recording layer 110 may include at least one element selected from the group consisting of Si, Ge, C, Sn, and Zn, and more preferably, in the group consisting of Si, Ge, C, Sn, and Zn. Contains 50 atomic% of the selected element. The second recording layer 120 contains 50 atomic% or more of Au as a main element. In addition, when the atomic% of Au included in the second recording layer 120 is less than 100, the second recording layer 120 may include at least one element selected from the group consisting of Si, Sb, Te, Ge, Al, and Cu. It is preferable to include as an addition element. The preferred addition ratio of the additive element is at least 0.01 atomic% and less than 50 atomic%.

The material of the first recording layer 110 and the material of the second recording layer 120 react with each other at the contact surfaces of the first recording layer 110 and the second recording layer 120 when irradiated with a laser beam. A record mark is generated by the mechanism by which a substance is produced. The material included in each of the recording layers 110 and 120 facilitates the generation of a recording mark, and allows data to be recorded and reproduced under conditions where a BD must be satisfied.

In addition, as an embodiment of the structure of the optical recording medium according to the present invention, it is preferable to stack the dielectric layers 20 and 30 on any one or more of the surfaces of the contact layer of the information recording layer 100. The dielectric layer is preferably made of ZnS-SiO ₂ . When the dielectric layer 20 (hereinafter referred to as the lower dielectric layer) is stacked on the surface of the contact layer of the information recording layer 100 that receives the laser beam first, the lower dielectric layer 20 adjusts the reflectivity and contrast of the optical recording medium. Play a role. In addition, the lower dielectric layer 20 prevents damage to the substrate 60 or the light transmitting layer 10 due to the rise of the temperature of the recording layer. The lower dielectric layer 20 may be stacked to sufficiently perform the above function, and the preferred thickness of the lower dielectric layer 20 is greater than 0 nm and less than 80 nm.

When a dielectric layer (hereinafter referred to as an upper dielectric layer) is stacked on a surface close to the substrate, the upper dielectric layer 30 adjusts the reflectivity and contrast of the optical recording medium. In addition, when the laser beam is irradiated to the recording layer, the upper dielectric layer 30 allows the heat generated in the recording layer to be released to the outside at an appropriate speed so that the thermal distribution of the recording layer is controlled. The upper dielectric layer 30 may be laminated to sufficiently play such a role, and the preferred thickness is greater than 0 nm and less than 50 nm.

Referring to FIGS. 2 and 3, a form in which an optical recording medium according to the present invention is recorded by irradiating a laser beam to the optical recording medium is described as follows. Grooves and lands are formed on the surface of the recording layer of the optical recording medium according to the present invention to serve as a guide of a laser beam irradiated onto the optical recording medium. As shown in FIG. 2, in land groove recording, data is recorded on a convex portion of the recording layers 110 and 120, and a recording mark 90 is formed on a portion of the surface of the recording layers 110 and 120 where the laser beam first touches. Say that.

As shown in FIG. 3, in groove recording, data is recorded in a concave portion of the recording layers 110 and 120, and a recording mark 90 is formed in a portion where the laser beam on the surface of the recording layer later touches. As described above, the optical recording medium according to the present invention can perform both land recording and groove recording.

Referring to FIG. 4, another embodiment of the structure of the optical recording medium according to the present invention will be described. The structure of the optical recording medium according to the present invention is the same as that of FIG. 1, but a recording sensitivity promoting layer 70 may be stacked around or inside the recording layers 110 and 120. The recording sensitivity promoting layer 70 is laminated with a material to which at least one element selected from the group consisting of Sn, Zn, Pb, Bi, Tl, Te, Se, S, Al, Ga, Ge, Cd, I, In is added. It is desirable to. The material that can be added to the recording sensitivity promoting layer 70 has a low melting point and reacts before the material of the recording layers 110 and 120 when irradiated with a laser beam, and latent heat generated due to a change in state during the reaction is The amount of heat required for the reaction of the contacted recording layer 110 or 120 can be supplied. Therefore, when the recording sensitivity promoting layer is laminated on the optical recording medium according to the present invention, the laser power required for generating the recording mark 90 can be reduced. Therefore, the position of the recording sensitivity promoting layer 70 is located on the surface where the laser beams of the recording layers 110 and 120 are first incident or near the substrate, or between the first recording layer 110 and the second recording layer 120. It is possible to locate. However, as shown in FIG. 4, it is most preferable to stack the laser beam of the information recording layer 100 in contact with the first incident surface.

Another embodiment of the structure of the optical recording medium according to the present invention will be described with reference to FIG. 5 includes one or more first recording layers 110 and 112 and one or more second recording layers 120 in the information recording layer 100 of the optical recording medium according to the present invention. The second recording layers 120 may be alternately stacked with each other so that the contact surfaces of the first recording layers 110 and 112 and the second recording layer 120 are two or more in contact with each other. ) And the reaction area between the second recording layer 120 is increased, so that the recording mark 90 can be easily generated in the thickness direction of the optical recording medium, Fig. 5 is a structure of the optical recording medium according to the present invention. In this example, two first recording layers 110 and 112 are stacked on both contact surfaces of the layer 120.

Referring to FIG. 6, another embodiment of the structure of the optical recording medium according to the present invention will be described. An optical recording medium according to the present invention is adjacent to a substrate 60, a reflective layer 50, two or more information recording layers 100 and 200, a separation layer 40 positioned between each recording layer, and each information recording layer 100 and 200. The lower dielectric layers 20 and 22 and the upper dielectric layers 30 and 32 may be stacked. In the information recording layers 100 and 200, recording marks 90 may be formed in the structure and shape described with reference to FIGS. 2 to 5, and the lower dielectric layers 20 and 22 and the upper dielectric layers 30 and 32 are described with reference to FIG. 1. As described above, the lasers of the respective information recording layers 100 and 200 may be laminated by selectively contacting the first incident surface or the surface close to the substrate.

The two or more information recording layers 100 and 200 need not all have the same structure. Therefore, only one information recording layer of the two or more information recording layers 100 and 200 includes at least one first recording layer and at least one second recording layer, and the first recording layer and the second recording layer alternately with each other. The contact surface between the first recording layer and the second recording layer may be two or more stacked. It is also possible to stack or further include the recording sensitivity promoting layer in only one information recording layer.

If there are two or more information recording layers 100 and 200, the sum of the thickness of the first recording layer and the thickness of the second recording layer included in any one of the information recording layers 100 and 200 is different from the information recording layer. The thickness of the first recording layer and the thickness of the second recording layer included in any one of the information recording layers can be different. And the ratio of the thickness of the first recording layer to the thickness of the second recording layer is equal to the thickness of the thickness of the first recording layer and the thickness of the second recording layer included in any one of the information recording layers other than the information recording layer. It is preferable to configure so that it may differ from ratio. That is, the thicknesses of the two information recording layers 100 and 200 are preferably different from each other in terms of transmittance. The reason is that when there are two or more information recording layers 100 and 200 in the optical recording medium, a recording mark is first generated in the information recording layer 100 which receives the laser beam, and then the information recording layer 200 which receives the laser beam for the second time. This is because the laser power can be maintained in a prescribed range so that a recording mark can be made on the information recording layer 200. For example, if the thickness of the information recording layer 110 that receives the laser beam first is a thickness corresponding to 40 to 60% transmittance, the thickness of the information recording layer 200 that receives the second laser beam is 1% or less. It can be comprised by the thickness which has permeability.

Experimental conditions and results for one embodiment of the optical recording medium according to the present invention described above will be described. First, the structure and recording material of the optical recording medium used in the experiment will be described as follows.

The optical recording medium used in the experiment had a donut shape having an inner diameter of 15 mm, an outer diameter of 120 mm, and a thickness of 1.1 mm, and the substrate had a track pitch of 0.32 μm having lands and grooves. . The substrate of the optical recording medium is made of polycarbonate, and a reflective layer made of Ag alloy on the substrate, an upper dielectric layer made of ZnS-SiO ₂ , a second recording layer, The multilayer thin film is laminated in the order of one recording layer, the lower dielectric layer consisting of ZnS-SiO ₂ . Then, a light transmitting layer is bonded to the 80 μm polycarbonate cover sheet with a 20 μm PSA adhesive on the lower dielectric layer.

The conditions of the experiment for one embodiment of the optical recording medium according to the present invention are as follows. In this experiment, the linear linear velocity of the optical recording medium was 5.28 m / s, and the measurement position of the optical recording medium was 30 mm at the inner circumference. Data was recorded on the optical recording medium to be groove grooved (In groove recording). The wavelength of the laser beam used was set to 408 nm and the readout power was set to 35 mW. In addition, Pulstec Co., Ltd. ODU-1000 was used as the evaluation equipment.

The reflective layer on the substrate of the optical recording medium used in the experiment was laminated with a Ag alloy having a thickness of 70 nm, and the upper dielectric layer (ZnS-SiO ₂ ), the second recording layer, the first recording layer, and the lower dielectric layer (ZnS-SiO) thereon. ₂ ) were laminated in order with different thicknesses, respectively.

Referring to Table 1, the combination of materials of each recording layer and the experimental results according to the thickness of the optical recording medium configured as described above are as follows.

 Experiment NO. Ge thickness (first recording layer) (Å) Au thickness (second recording layer) (Å) Lower dielectric layer thickness (Å) Top dielectric layer thickness (Å) 8T modula-tion (I8 _pp / I8 _H ) (%)  Judgment DC annea-ling power (mW)  Judgment Saturated power range (ΔmW)  judgment mark stab-ility   One   150   50   680   180   25  △   2.7  △   3.5  △   ○   2   150   50   460   180  73 → 50  ○   5.0  △   3.0  △   △   3   90   30   460   180   50  ◎   1.3  ○   1.75  ○   △

Experiment NO. 1 and experiment NO. 2 and experiment NO. The first recording layer-second recording layer 3 contains 50 atomoic% or more of Ge-Au as a main component. The lower dielectric layer and the upper dielectric layer are made of ZnS-SiO ₂ . Experiment No. 1 is a case where the upper dielectric layer-second recording layer-first recording layer-lower dielectric layer is laminated to a thickness of 180 mW-50 mW-150 mW-680 mW, respectively. Experiment NO. 2 is experiment NO. Each layer is laminated with the same thickness as 1, but the thickness of the lower dielectric layer is laminated at 460 Å. Experiment NO. 3 is experiment NO. Each layer is laminated to the same thickness as 2, except that the thicknesses of the first recording layer and the second recording layer are 90 [mu] s and 30 [mu] s, respectively. As described above, since the ratio of the thickness of the first recording layer to the thickness of the second recording layer is preferably two or more, in each experiment, the ratio of the thickness of the first recording layer to the thickness of the second recording layer is laminated so as to be three. It was.

  The evaluation criteria for each experimental combination were the difference in reflectance of the optical recording medium, the magnitude of DC annealing power, saturated power range and mark stability for 8T modulation. Experimental combinations that showed good results among the criteria according to each criterion in Table 1 are circled in the right column of the evaluation criteria (the corresponding column for mark stability).

First, the difference in reflectivity of the optical recording medium for 8T modulation indicates the optical contrast between the space and the mark required by the optical recording medium. That is, the difference between the highest reflectance value and the lowest reflectance value for the 8T modulation pulse of the laser beam is divided by the highest reflectance value, and is expressed as a percentage (%) value. The difference in reflectance with respect to the 8T modulation pulse of the laser beam is the first criterion for determining the optical recording medium, and the difference in reflectance is large enough to be suitable as the optical recording medium. In this experiment, the difference in reflectivity for 8T modulation pulses was determined by experiment NO. 2 and experiment NO.3 were the most turned on, and experiment NO.2 had some changes in the above values.

DC annealing power is a criterion for indirectly confirming whether an optical recording medium having an optimized structure can be recorded at a specified recording power (Pw). BD, a next-generation optical recording medium, should generate a recording mark within a laser recording power in the range of 3 to 6 mW for 1X speed and 3 to 7 mW for 2X. In order to confirm this indirectly, the power at which the change of the first recording layer and the second recording layer starts to be measured is measured, and if the measured power is within 3 mW, it is determined that the optical recording medium has an appropriate recording sensitivity to the prescribed laser power. It was. When explaining the experimental method of DC annealing power specifically as an evaluation criteria are as follows. First, a laser beam of space power Ps (mW) is irradiated to the optical recording medium. The pulse of the laser beam is not a multi pulse type but a single pulse type. When the laser beam is irradiated, the laser power at which the magnitude of the original reflectivity of the optical recording medium starts to change on the oscilloscope is measured. The magnitude of the measured laser power is the value of DC annealing power. In this experiment, the most optimized optical recording medium was evaluated if DC annealing power was less than 2.5mW. As a result of the evaluation criteria, Experimental NO.3 showed the best record sensitivity than Experimental NO.1 and Experimental NO.2. Therefore, it can be seen that the thickness of the recording layer rather than the thickness of the dielectric layer affects the recording sensitivity, and it is preferable that the recording layer is thin in terms of recording power.

Saturated power range is a criterion for indirectly confirming the temperature range from when the recording layer begins to react and gradually increases the reaction area in the thickness direction of the optical recording medium until the entire thickness of the recording layer reacts. If the value of the saturated power range is large, the power range of the laser to obtain optimized recording characteristics may deviate from the specified specification even if the temperature at which the reaction actually starts is low. In addition, in the intermediate temperature range, the reflectivity characteristic of the optical recording medium is changed so much that it is difficult to control the recording. That is, the reflectivity of the optical recording medium with respect to the laser power when recording to the optical recording medium should change rapidly in a narrow laser power range. Therefore, in order to select the thickness combination of each layer in which the temperature change of the recording layer is completed in the narrow laser power range, the thickness combination of each layer in which the saturated power range is smaller than 2 mW was determined as the most appropriate combination. In the above experiment, the experiment NO. 3 shows the best result, and in combination of the thicknesses of the layers of the experiment NO.

Mark stability as a criterion of the experiment is an item that determines whether the record mark can be maintained for a long time without change over time. When the recording mark is formed by the 8T modulation laser pulse on the optical recording medium, the size of the recording mark should be maintained without increasing or decreasing with time under the influence of the laser beam of the readout power or the room temperature. Mark stability of the optical recording medium according to the present invention is generally satisfactory, but experiment No. 1 is evaluated as the best thickness combination.

FIG. 7 is a graph showing the results of measuring DC annealing power values for optical recording media having the thickness combinations of experiments No. 1, 2 and 3 shown in Table 1. FIG. As described above, each layer thickness combination of Experiment No. 3 showed the best recording sensitivity. That is, each layer thickness combination of Experiment O.3 expresses the reflected signal at the smallest DC annealing power.

8 shows optical recording according to the thickness of upper and lower dielectric layers when the thickness combination of the first recording layer / second recording layer in the information recording layer of the optical recording medium is Ge (150 s) / Au (50 s) and the reflective layer is 700 s. It is the result of a simulation showing the reflectance (%) of the medium.

9 shows optical recording according to the thickness of upper and lower dielectric layers when the thickness combination of the first recording layer / second recording layer in the information recording layer of the optical recording medium is Ge (90 이) / Au (30Å) and the reflecting layer is 700 반사. It is the result of a simulation showing the reflectance (%) of the medium.

According to the results of FIGS. 8 and 9, it can be seen that the lower dielectric layer (horizontal axis of FIGS. 8 and 9) can adjust the reflectivity and contrast sufficient to the optical recording medium up to about 80 nm (800 μs). Since the reflectivity according to the thickness of the dielectric layer has a periodicity, a phenomenon in which the reflectivity of a thin thickness below that of 80 nm or more is repeated again. Too thick a dielectric layer can also thermally affect the information recording layer, which may have undesirable effects. Therefore, the thickness of the lower dielectric layer is preferably 80 nm or less. If the thickness of the upper dielectric layer along the vertical axis of FIGS. 8 and 9 is 50 nm or more, there is a high possibility that the contrast becomes low. In addition, if the upper dielectric layer is too thick, heat generated in the recording layer may not be discharged well, and thus the shape of the recording mark may not be adjusted well, and the length of each mark may not be adjusted well. Therefore, the thickness of the upper dielectric layer is preferably 50 nm (500 GPa) or less.

Fig. 10 shows the pre-recording according to the thickness of the upper and lower dielectric layers when the thickness combination of the first recording layer / second recording layer in the information recording layer of the optical recording medium is Ge (150Å) / Au (50Å) and the reflective layer is 700Å. The difference between the reflectivity and the reflectance of the recording mark after recording is expressed as a percentage (%) divided by the reflectivity before recording. In Fig. 10, the negative part of the blue system indicates that the reflectivity after recording is greater. That is, the portion indicates that the reflectance of the recording mark is greater, indicating that the polarity of the reproduction signal can be changed due to the combination of upper and lower dielectric layers.

Next, the jitter evaluation result of the optical recording medium according to the present invention having the structure described in Experiment NO.3 of Table 1 will be described. First, as the jitter measurement condition of the optical recording medium according to the present invention, the channel bit clock was set to 66 MHz, and the linear linear velocity of the optical recording medium was 5.28 m / s. The disc capacity of the optical recording medium was 23.3 gigabytes (GB / each recording layer; single side) for each information recording layer, and Yokogawa TA520 was used as the jitter measuring equipment. The number of experimental sampling for jitter measurement was performed 30,000 times, and the measurement position of the optical recording medium was selected to be 30 mm from the inner circumference of the optical recording medium, and both land recording and groove recording were performed on the optical recording medium. In addition, the wavelength of the recording laser beam for the optical recording medium (Laser Wavelength) of 408nm was used.

Fig. 11 shows the waveform of the laser recording pulse used for data recording of the optical recording medium according to the present invention described above. The recording power Pw of the laser pulse used for recording the optical recording medium has a size of 4.1 mW, the space power Ps of 1.0 mW, and the base power Pb of 0.4 mW. The laser recording pulses have random multi-pulses of 2T to 6T, and the recording was performed by modulating the pulses so as to be N-1 divided pulses for each recording pulse.

Referring to Fig. 12, the eye pattern of the optical recording medium according to the present invention having each layer combination of Experiment No. 3 will be described. In Experiment NO. 3, the upper dielectric layer-second recording layer-first recording layer-lower dielectric layer were laminated to a thickness of 180 Å-30 Å-90 Å-460 각각, respectively. As can be seen in FIG. 10, a signal reproduced when a laser beam is irradiated onto an optical recording medium having the thickness of each recording layer and the thickness of the upper dielectric layer and the lower dielectric layer has a low to high polarity (LTH). FIG. 12 shows an eye pattern of RF when the laser pulse of FIG. 11 is irradiated on the optical recording medium combined with the thickness, and it can be seen that the eye pattern is a clear and clear eye pattern of RF. have. Therefore, the ratio of jitter due to the point where the conversion point of the reproduction signal does not coincide with the change point of the original signal is small, so that it can be used as an optical recording medium suitable as a BD.

FIG. 13 shows a probability distribution over time of a reproduction signal. In this distribution, the standard deviation (σ) divided by the reference clock (1T) of the laser beam (σ / T) was found to be 5.6%. The narrower the standard deviation is, the better the optical recording medium is. In general BD, less than 6.5% is considered a suitable optical recording medium. Therefore, it can be seen that the optical recording medium according to the present invention can satisfactorily satisfy the BD system.

The superiority of the performance of the optical recording medium according to the present invention was seen when there was only one information recording layer, but this was also the case when two or more information recording layers were included. One or more recording layers of the two or more information recording layers may be combined with the above-described constituent materials in thickness ratio, sum of thickness, and the like, which belong to the technical idea of the present invention. In addition, the technical idea of the present invention can be easily modified by those skilled in the art and this also belongs to the technical idea of the present invention.

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

First, the optical recording medium according to the present invention generates a recording mark as a mechanism for generating a new material by reacting the materials of the recording layer with each other. The optical recording medium having the recording material according to the present invention satisfies the BD system. An optical recording medium having a very high recording density and a data transmission rate can be provided.

Secondly, according to the optical recording medium having a combination of recording materials according to the present invention, even when data is recorded at a high density, a large constrast between a mark and a space and a high recording sensitivity are high. An optical recording medium can be provided.

Third, according to the optical recording medium having a combination of recording materials according to the present invention, the laser power required to make a recording mark while satisfying the BD system and excellent in mark stability and recording characteristics of the recording mark of the optical recording medium. There is an advantage that does not raise.

Claims (28)

In an optical recording medium for recording information by a mechanism for generating a new material having a different reflectance from the surroundings in the recording layer when the laser beam is irradiated, Board; A reflective layer positioned adjacent to the substrate to reflect an incident laser beam; and An information recording layer located on the reflection; The information recording layer includes a first recording layer including one or more elements selected from the group consisting of Si, Ge, C, Sn, and Zn; And An optical recording medium comprising a second recording layer containing 50 atomic% or more of Au as a main element. In an optical recording medium for recording information by a mechanism for generating a new material having a different reflectance from the surroundings in the recording layer when the laser beam is irradiated, Board; A reflective layer positioned adjacent to the substrate to reflect an incident laser beam; and An information recording layer located on the reflection; The information recording layer comprises: a first recording layer containing at least 50 atomic% of one element selected from the group consisting of Si, Ge, C, Sn, and Zn as main elements; And An optical recording medium comprising a second recording layer containing 50 atomic% or more of Au as a main element. The method of claim 2, When the atomic% of Au of the second recording layer is less than 100, the second recording layer includes at least one element selected from the group consisting of Si, Sb, Te, Ge, Al, and Cu as an additional element. Optical record carrier. The method of claim 3, wherein The ratio of the added element is 0.01 atomic% or more and less than 50 atomic%. The method of claim 2, The information recording layer includes at least one first recording layer and at least one second recording layer, wherein the first recording layer and the second recording layer are alternately stacked with each other so that the first recording layer and the second recording layer. Optical recording medium, characterized in that the contact surface between the two or more. The method of claim 2, And the thickness ratio of the first recording layer to the thickness of the second recording layer is two or more. The method of claim 2, The information recording layer further includes a recording sensitivity promoting layer including at least one element selected from the group consisting of Sn, Zn, Pb, Bi, Tl, Te, Se, S, Al, Ga, Ge, Cd, I, In. An optical recording medium, characterized in that. The method of claim 7, wherein And the recording sensitivity promoting layer stacks the laser beam of the first recording layer in contact with at least one of the first incident surface or the surface close to the substrate. The method of claim 7, wherein And the recording sensitivity promoting layer stacks the laser beam of the second recording layer in contact with at least one of the first incident surface or the surface close to the substrate. The method of claim 2, And stacking the laser beam of the information recording layer in contact with at least one of the first incident surface or the surface close to the substrate in contact with the dielectric layer. The method of claim 10, And a dielectric layer having a thickness of more than 0 nm and not more than 80 nm when the dielectric layer is laminated on the contact surface where the laser of the information recording layer is incident first. The method of claim 10, And a thickness of the dielectric layer is greater than 0 nm and less than or equal to 50 nm when the dielectric layer is laminated on the near contact surface of the substrate among the contact layer surfaces of the information recording layer. The method according to claim 1 or 2, And the optical recording medium is a recordable optical recording medium. In an optical recording medium for recording information by a mechanism for generating a new material having a different reflectance from the surroundings in the information recording layer when the laser beam is irradiated, Board; A reflective layer positioned adjacent to the substrate to reflect an incident laser beam; and Two or more information recording layers positioned on the reflections; And A separation layer laminated between the information recording layers adjacent to each other among the two or more information recording layers, Each information recording layer comprises: a first recording layer including at least one element selected from the group consisting of Si, Ge, C, Sn, and Zn; And  An optical recording medium comprising a second recording layer containing 50 atomic% or more of Au as a main element. In an optical recording medium for recording information by a mechanism for generating a new material having a different reflectance from the surroundings in the information recording layer when the laser beam is irradiated, Board; A reflective layer positioned adjacent to the substrate to reflect an incident laser beam; and Two or more information recording layers positioned on the reflections; And A separation layer laminated between the information recording layers adjacent to each other among the two or more information recording layers, Each of the information recording layers includes: a first recording layer containing at least 50 atomic% of one element selected from the group consisting of Si, Ge, C, Sn, and Zn as a main element; And An optical recording medium comprising a second recording layer containing 50 atomic% or more of Au as a main element. The method of claim 15, When the atomic% of Au of the second recording layer included in any one of the two or more information recording layers is less than 100, the second recording layer is Sn, Zn, Pb, Bi, Tl, Te, Se, An optical recording medium comprising at least one element selected from the group consisting of S, Al, Ga, Ge, Cd, I and In as an additional element. The method of claim 16, The ratio of the added element is more than 0.01 atomic% and less than 50 atomic% optical recording medium. The method of claim 15, And the thickness ratio of the first recording layer to the thickness of the second recording layer included in any one of the two or more information recording layers is two or more. The method of claim 15, A first ratio of the thickness of the first recording layer and the second recording layer included in any one of the two or more information recording layers to the information recording layer of any other information recording layer except for the information recording layer. And a ratio of the thickness of the recording layer to the thickness of the second recording layer. The method of claim 15, The sum of the thickness of the first recording layer and the thickness of the second recording layer included in any one of the two or more information recording layers is included in the information recording layer of any one of the other information recording layers except the information recording layer. And the sum of the thickness of the first recording layer and the thickness of the second recording layer. The method of claim 15, Any one of the at least two information recording layers includes at least one first recording layer and at least one second recording layer, wherein the first recording layer and the second recording layer are alternately stacked with each other to form the first recording layer. And the contact surface between the first recording layer and the second recording layer is two or more. The method of claim 15, Any one of the two or more information recording layers includes at least one element selected from the group consisting of Sn, Zn, Pb, Bi, Tl, Te, Se, S, Al, Ga, Ge, Cd, I, In. An optical recording medium further comprising a recording sensitivity promoting layer comprising. The method of claim 22, And the recording sensitivity promoting layer stacks the laser beam of the first recording layer in contact with at least one of the first incident surface or the surface close to the substrate. The method of claim 22, And the recording sensitivity promoting layer stacks the laser beam of the second recording layer in contact with at least one of the first incident surface or the surface close to the substrate. The method of claim 15, And stacking the laser beam of any one of the two or more information recording layers in contact with at least one surface of the first incident surface or a surface close to the substrate in contact with the dielectric layer. The method of claim 25, And a dielectric layer having a thickness of more than 0 nm and not more than 80 nm when the dielectric layer is laminated on the contact surface where the laser of the information recording layer is incident first. The method of claim 25, And a thickness of the dielectric layer is greater than 0 nm and less than or equal to 50 nm when the dielectric layer is laminated on the near contact surface of the substrate among the contact layer surfaces of the information recording layer. The method according to claim 14 or 15, And the optical recording medium is a recordable optical recording medium.

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