JP4401909B2 - Optical recording medium and method for manufacturing optical recording medium - Google Patents

Description

  The present invention relates to an optical recording medium, and more particularly to an optical recording medium that enables high-density recording by making a track pitch close to the recording medium and shortening a recording mark length.

As optical recording media, disk-shaped optical recording media such as CDs and DVDs are well known. However, with the progress of information technology such as multimedia and networking, the amount of information increases dramatically, and optical recording There is an increasing demand for higher density and higher capacity for media.
As a method for increasing the density, there is a method for reducing the area for recording the same amount of information, that is, a method for reducing the recording pits. In order to reduce the recording pit, it is necessary to reduce the light beam diameter and reduce the light spot diameter. The light spot diameter is proportional to λ / NA, where λ is the wavelength and NA is the aperture ratio of the lens. From this relationship, the spot diameter is reduced by decreasing the wavelength or increasing the aperture ratio. Recently, DVDs using light having a wavelength of 0.65 μm have been put into practical use, and development aiming at higher density using light having a wavelength of about 0.4 μm is being actively carried out.

In order to increase the density, it is necessary to simultaneously reduce the recording pits and the pit intervals to further increase the linear recording density and the track density. In order to increase the track density, it is inevitable to decrease the track pitch, but in this case, crosstalk, cross light, or cross erase becomes a problem.
In other words, when the track pitch is reduced, there is a problem of crosstalk that erroneously reads the signal recorded in the adjacent track during playback, and when the signal is recorded / erased, the signal is erroneously recorded in the adjacent track. This causes a problem such as cross-write, or cross-erase that erroneously erases the recording signal of the adjacent track.
Furthermore, when the recording mark length is shortened and the recording density is increased, there is a problem that the influence on the error rate due to the displacement of the recording mark is increased. That is, there arises a problem that the positional deviation of the recording mark becomes relatively large and the signal jitter increases remarkably.

As a method for solving such a problem, for example, a structure in which a recording area formed on a disk substrate is divided for each track, and a material having a lower thermal conductivity than a recording material constituting the recording area is interposed between the tracks. This prevents the rise in temperature at the beam spot of the light beam irradiated during signal recording and erasing from being transmitted to the adjacent tracks, and suppresses the occurrence of cross light and cross erase even when the track pitch is narrow. In addition, a method has been proposed in which a recording area is divided for each recording mark in a track to reduce jitter during signal reproduction (see, for example, Patent Document 1).
However, in order to manufacture a recording medium by this method, it is necessary to use a special technique and means such as photolithography, and there is a problem that the manufacturing cost increases because the processing process is complicated. In addition, since this disk is recorded on the recording layer by direct stimulation of the light beam, it is difficult to prevent cross-writing and cross-erasing of the recording layer in the irradiation spot.

JP 2000-276770 A

  The present invention has been made in view of the above prior art, and suppresses crosstalk, cross-write or cross-erase between adjacent tracks when the track pitch is close, and also reduces the position of the recording mark when shortening the recording mark length. It is an object of the present invention to provide an optical recording medium capable of high-density recording and a simple manufacturing method thereof by reducing the deviation and reducing the influence on the error rate (reducing signal jitter).

  As a result of intensive studies, the inventors of the present invention can solve the above problem by configuring the thermal control region of the optical recording medium by the absorbing portion and the heat insulating portion, and arranging them alternately in contact with the recording layer. And found the present invention. Hereinafter, the present invention will be specifically described.

That is, the present invention relates to an optical recording medium having a thermal control region on a substrate and a recording layer in which optical properties are altered and / or deformed by heat.
The thermal control region includes a light absorbing part that absorbs irradiation light and easily generates heat and a heat insulating part that does not easily generate heat, and the light absorption of the heat insulating part at the wavelength of the irradiated light is that of the light absorbing part. It is smaller than the light absorption , the light absorption part and the heat insulation part are alternately arranged so as to contact the recording layer , and the light absorption part and the heat insulation part are respectively configured in an annular shape or a spiral shape in the radial direction. An optical recording medium characterized by the above.

  The recording layer is preferably bismuth oxide. Furthermore, it is preferable that the light absorption part is made of a compound containing Sb and / or Te.

  And it is preferable that the said heat insulation part consists of a compound containing ZnS, and it is also preferable that it consists of any metal chosen from Ag, Al, or Cu.

  Further, in any one of the optical recording media except for the case where the heat insulating portion is any metal selected from Ag, Al, or Cu, the light absorbing portion and the heat insulating portion in the heat control region are alternately in contact with the recording layer. The heat insulating part having a configuration arranged in (1) is formed in a convex shape on one surface of the light absorbing part.

  Further, in any one of the optical recording media including the case where the heat insulating portion is any metal selected from Ag, Al, or Cu, the light absorbing portion and the heat insulating portion in the thermal control region are alternately in contact with the recording layer. The light-absorbing part having a configuration arranged in (1) is formed in a convex shape on one surface of the heat-insulating part.

  Furthermore, in any one of the optical recording media except for the case where the heat insulating portion is any metal selected from Ag, Al, or Cu, the light absorbing portion and the heat insulating portion in the thermal control region are alternately in contact with the recording layer. The light absorbing portion and the heat insulating portion having the configuration arranged as described above are formed in the same plane.

Furthermore, the present invention has a thermal control region on a substrate and a recording layer whose optical properties change due to alteration and / or deformation due to heat based on light irradiation, and the thermal control region absorbs irradiation light. and a heat insulating portion which does not easily generate heat and the light absorbing portion to easily exothermic, the light absorption of the heat insulating portions in the wavelength of the irradiated light being smaller than the light absorption of the light absorbing portion, the heat insulating portion is the light wherein said light absorbing portion is formed in a convex shape on one side of the absorbent portion heat insulating portion is arranged so as to be in contact with the recording layer alternately, and the heat insulating portion and the light absorbing portion annular or in the radial direction, respectively A method of manufacturing an optical recording medium configured in a spiral shape ,
A step of sequentially laminating a light absorbing layer for a light absorbing portion on the substrate and a thin film for forming a heat insulating portion on one surface thereof;
Irradiating light from the thin film side to modify the thin film to have a predetermined convex shape;
Removing unnecessary portions that are not modified by the light irradiation by etching and forming a convex shape;
Forming a recording layer on the top surface of the etched structure;
The present invention relates to a method for manufacturing an optical recording medium including at least

Furthermore, the present invention has a thermal control region on a substrate and a recording layer whose optical properties change due to alteration and / or deformation due to heat based on light irradiation, and the thermal control region absorbs irradiation light. A light absorbing part that easily generates heat and a heat insulating part that does not easily generate heat, and the light absorption of the heat insulating part is smaller than the light absorption of the light absorbing part at the wavelength of the irradiated light. the heat insulating portion and the light absorbing portion is formed in a convex shape on one surface of the insulating part is arranged so as to be in contact with the recording layer alternately, and the annular heat insulating portion and the light absorbing portion in the radial direction, respectively Or a method of manufacturing an optical recording medium configured in a spiral shape ,
A step of sequentially laminating a heat insulating layer for the heat insulating portion on the substrate and a thin film for forming a light absorbing portion on one surface thereof;
Irradiating light from the thin film side to modify the thin film to have a predetermined convex shape;
Removing unnecessary portions that are not modified by the light irradiation by etching and forming a convex shape;
Forming a recording layer on the top surface of the etched structure;
The present invention relates to a method for manufacturing an optical recording medium including at least

In addition, the present invention further includes a thermal control region and a recording layer on which optical characteristics change due to alteration and / or deformation due to heat based on light irradiation on the substrate, and the thermal control region absorbs irradiation light. A light absorbing portion that easily generates heat and a heat insulating portion that does not easily generate heat, and the light absorption of the heat insulating portion is smaller than the light absorption of the light absorbing portion at the wavelength of the irradiated light, the heat insulating portion and the light absorbing portion together with the heat insulating portion is formed in the same plane are arranged in contact with the recording layer alternately, and the heat insulating portion and the light absorbing portion annular or spiral in the radial direction, respectively A method of manufacturing an optical recording medium configured in a shape ,
A step of sequentially laminating a thin film for forming a heat insulating part on the substrate and a light absorbing thin film;
Irradiating light to the thin film for forming the heat insulating part and the light absorbing thin film to modify the thin film so as to have a predetermined shape;
Etching the portion of the thin film that is not modified by the light irradiation with hydrofluoric acid to remove it;
Crystallizing the light-absorbing thin film on the formed heat insulating portion and removing the thin film with an alkaline solution;
Laminating a thin film for forming a light absorbing portion on the upper surface of the structure on which the heat insulating portion is formed;
A step of amorphizing the portion of the thin film for forming the light absorbing portion to be left amorphous by light irradiation, and removing the thin film in a crystallized state with an alkaline solution;
Forming a recording layer on the upper surface of the formed structure;
The present invention relates to a method for manufacturing an optical recording medium including at least

According to the configuration of the optical recording medium of the present invention, the light absorbing portion that absorbs irradiation light and easily generates heat and the heat insulating portion that does not easily generate heat are arranged so as to contact the recording layer alternately. Accordingly, it is possible to perform thermal control in the temperature rising region, and it is possible to realize a close track pitch and a short recording mark length. Accordingly, it is possible to provide an optical recording medium that can suppress cross write, cross erase, or cross talk between adjacent tracks, reduce recording mark positional deviation, and enable high density recording. Can do.
Further, according to the manufacturing method of the present invention, an optical recording medium can be manufactured without using a special technique or means such as photolithography, and without increasing the manufacturing cost by a simple processing process.

  As described above, the optical recording medium of the present invention includes on the substrate a light absorbing part that absorbs irradiation light and easily generates heat and a heat insulating part that does not easily generate heat, and the light absorbing part and the heat insulating part are alternately arranged. And a thermal control region disposed so as to be in contact with the recording layer, and a recording layer in which optical properties change due to alteration and / or deformation by heat.

  Normally, recording on an optical recording medium is performed along a track formed in the circumferential direction. However, when the track pitch is narrowed, that is, close to it in order to increase the density, the irradiation light is relatively larger than the track width. As a result, the spot diameter increases, and light is irradiated to adjacent tracks other than the predetermined track. In such a state, the temperature of the portion of the adjacent track irradiated with light also rises, and as a result, the information is recorded on the adjacent track (cross write), the information on the adjacent track is erased (cross erase), or Although there is a problem of erroneously reading (crosstalk) the signal recorded on the adjacent track, the temperature rise of the track other than the predetermined track is achieved by providing the thermal control region including the light absorbing portion and the heat insulating portion of the present invention. Is suppressed and the above problem is avoided. The optical recording medium of the present invention will be described in detail below with reference to the drawings.

A configuration example for explaining the optical recording medium of the present invention is shown in a schematic sectional view of FIG. FIG. 1 is a cross-sectional view orthogonal to the track, in which the horizontal direction indicates the radial direction of the optical recording medium, and the direction perpendicular to the paper surface is the track direction.
The optical recording medium is provided with a heat control region 100 in which a heat insulating portion 103 is formed on a surface of a light absorbing portion 102 on a substrate 101 in a convex shape, and the light absorbing portion 102 and the heat insulating portion 103 are alternately arranged in a recording layer. 104 so as to be in contact with 104.

  When the optical recording medium configured as shown in FIG. 1 is irradiated with light, as shown in the schematic diagram of FIG. 2, in the portion where the heat insulating portion 103 is formed, the heat generated in the light absorbing portion 102 is generated by the recording layer 104. Not communicated to. For this reason, a recording mark is not formed on the recording layer 104 in a portion in contact with the heat insulating portion 103, and a recording mark is formed only in a portion of the recording layer 104 in contact with the light absorbing portion 102 sandwiched between the heat insulating portions 103. . As a result, recording, erasing, and reproduction can be performed in a narrow area of a predetermined track, and cross-write, cross-erase, or cross-talk to adjacent tracks can be suppressed. In addition, the displacement of the recording mark can be reduced.

  FIG. 3 is a schematic diagram in the case where a recording mark is formed by irradiating light onto an optical recording medium having a configuration without a heat insulating portion in FIG. In the case of this configuration, when the collected light 105 is irradiated, the light absorption unit 102 absorbs light, and a temperature in a wide area corresponding to the size of the collected light 105 rises. A recording mark 106 is formed on the corresponding recording layer 104. That is, it is not possible to suppress cross light, cross erase, or cross talk to adjacent tracks.

The respective light absorptions of the light absorbing part that constitutes the thermal control region of the optical recording medium of the present invention and absorbs irradiation light and generates heat easily and the heat insulating part that does not generate heat easily are the wavelength of the irradiated light. It is preferable that the heat insulating part is smaller than the light absorbing part.
As described above, the recording mark is formed in the recording layer in the region in contact with the light absorbing portion by absorbing the light in the light absorbing portion and the temperature rises. Therefore, the recording mark is formed only in a predetermined narrow region. Therefore, it is desirable that the temperature does not increase as much as possible in the heat insulating portion. For this purpose, it is effective to suppress the light absorption in the heat insulating portion and to prevent the temperature from rising. In this way, the recording area can be limited.

Next, materials used for each constituent layer of the optical recording medium of the present invention will be described.
As a material used for the substrate of the present invention, for example, a plastic such as polycarbonate resin or polymethyl methacrylate resin, glass, ceramic, metal, or the like can be used. Note that grooves and pits for controlling tracking may be provided on the surface of the substrate.

  For the recording layer of the optical recording medium of the present invention, a material whose optical properties change due to alteration and / or deformation by heat can be used. As such a material for the recording layer, an oxide such as Bi, Te, Sb, or Se, or a dye material is used. In particular, bismuth oxide is preferably used.

  That is, when bismuth oxide is used for the recording layer, the recording layer can be altered or deformed by heat to form a recording mark, and bismuth oxide absorbs irradiated light because it absorbs light relatively little. The temperature rise by itself is so small that no recording mark is formed. The recording mark can be formed by absorbing the light and increasing the temperature, and transferring the heat to the recording layer made of bismuth oxide. As a result, a recording mark can be formed in a predetermined area, and it is possible to suppress cross-write, cross-erase, cross-talk to adjacent tracks, or to reduce the position deviation of the recording mark.

  In addition, as the light absorbing portion constituting the heat control region of the optical recording medium of the present invention, a material that easily generates heat by absorbing irradiation light can be used. As such a material, a material that efficiently absorbs light and rises in temperature is good. For example, a compound containing a low-melting-point metal material is preferably used, and in particular, a material made of a compound containing Sb and / or Te. Is preferred.

  As a compound containing Sb and / or Te, a binary material such as SbTe, InTe, BiTe, or GaSb, a ternary material such as GeSbTe, InSbTe, BiSbTe, or GaSbTe, or a quaternary material such as AgInSbTe should be used. Can do. Since these materials generate heat when irradiated with laser light having a relatively low power, recording can be performed in an output range that is possible with a semiconductor laser. Further, since recording can be performed with light having a relatively low power, heat can be spread and damaged other than the light absorbing portion, and good recording can be performed.

As the heat insulating part constituting the heat control area of the optical recording medium of the present invention, heat is not easily generated even when the irradiation light is absorbed, and heat generated in the light absorbing part is not transmitted to the recording layer other than the predetermined area. Or a material that prevents heat from spreading adjacently. As such a material, a compound containing ZnS is preferable. For example, a composite compound composed of ZnS and SiO ₂ , a composite compound composed of ZnS and ZnO, a composite compound composed of ZnS, SiO ₂ and ZnO, or a material transparent to ZnS Examples include composite compounds with dielectric materials.

  That is, ZnS (zinc sulfide) has a lower thermal conductivity than the compound containing Sb and / or Te and has a high heat insulation effect. For this reason, since the heat transfer from the heat insulating portion to the recording layer is reduced, the recording layer corresponding to the heat insulating portion can be prevented from being altered or deformed. In other words, recording can be performed in a predetermined narrow area, cross-write, cross-erase and cross-talk to adjacent tracks can be suppressed, or recording mark position deviation can be reduced.

Furthermore, as a heat insulation part which comprises the heat control area | region of the optical recording medium of this invention, depending on the structure (for example, below-mentioned FIG. 4) of the said heat control area | region, either metal chosen from Ag, Al, or Cu is used. It is preferable to use it.
That is, Ag, Al, and Cu have a high thermal conductivity, and the heat in the heat insulating portion is immediately radiated and the temperature does not rise. For this reason, a recording mark can be formed only in a predetermined area of the recording layer, and it is possible to suppress cross write, cross erase, cross talk to adjacent tracks, or to reduce the position deviation of the recording mark.

The optical recording medium of the present invention is mainly composed of a substrate, a recording layer, a light absorbing portion as a heat control region, and a heat insulating portion. For example, a buffer for preventing the substrate from being deformed by the influence of heat. A layer, a sliding layer for improving sliding performance, a lubricating layer for improving lubricity, and the like can be provided. As the buffer layer, a dielectric material (for example, ZnS · SiO ₂ or the like) can be used. Further, diamond-like carbon (DLC) or the like is used as the sliding layer, and fomblin or the like is used as the lubricating layer.

FIG. 4 is a schematic sectional view showing another configuration example of the optical recording medium in the present invention. FIG. 4 is a cross-sectional view orthogonal to the track. The horizontal direction indicates the radial direction of the optical recording medium, and the direction perpendicular to the paper surface is the track direction.
The optical recording medium is provided with a heat control region 100 in which a light absorbing portion 102 is formed on a surface of a heat insulating portion 103 on a substrate 101 in a convex shape, and the light absorbing portion 102 and the heat insulating portion 103 are alternately arranged in a recording layer. 104 so as to be in contact with 104.

With the configuration of FIG. 4, similarly to FIG. 1, the heat generated in the light absorbing portion 102 is not transmitted to the recording layer 104 in the portion where the heat insulating portion 103 is formed. As a result, a recording mark is formed only on the recording layer 104 in a portion in contact with the light absorbing portion 102, and recording, erasing, and reproduction can be performed in a narrow area of a predetermined track, and cross writing, cross erasing, and crossing to an adjacent track are possible. Talk can be suppressed. Alternatively, the displacement of the recording mark can be reduced.
As described above, in the case of this configuration, it is preferable to form the heat insulating portion using any metal selected from Ag, Al, or Cu.

FIG. 5 is a schematic cross-sectional view showing still another configuration example of the optical recording medium in the present invention. FIG. 5 is a cross-sectional view orthogonal to the track. The horizontal direction indicates the radial direction of the optical recording medium, and the direction perpendicular to the paper surface is the track direction.
The optical recording medium is provided with a thermal control region 100 in which the light absorbing portion 102 and the heat insulating portion 103 are formed on the same plane on the substrate 101, and the light absorbing portion 102 and the heat insulating portion 103 are alternately formed on the recording layer 104. It is arranged to touch.

  With such a configuration, heat generated in the light absorbing portion 102 is not transmitted to the recording layer 104 in the portion where the heat insulating portion 103 is formed. For this reason, the recording mark is formed only on the recording layer 104 in the portion in contact with the light absorbing portion 102 sandwiched between the heat insulating portions 103 as in FIGS. Accordingly, recording, erasing, and reproducing can be performed in a narrow area of a predetermined track, cross writing, cross erasing, and cross talk to an adjacent track can be suppressed, and a recording mark position shift can be reduced.

In the present invention, the light absorbing portion and the heat insulating portion disposed so as to be in contact with the recording layer of the recording medium are each configured in an annular shape or a spiral shape in the radial direction .
The plan view of FIG. 6 schematically shows a state in which the light absorbing portion and the heat insulating portion are formed annularly in the radial direction on the substrate. That is, it shows a state in which the light absorbing portions 102 and the heat insulating portions 103 are alternately provided in a ring shape. In FIG. 6, only the circumference of several cycles is schematically shown, but such a structure is formed from the inner periphery to the outer periphery in an actual optical recording medium. Further, although the recording layer is not shown in the drawing, the recording layer is formed in layers on these structures.
Tracking can also be performed using such a structure. In that case, a substrate without a tracking groove can be used. Although FIG. 6 shows a circumferential structure, a spiral structure from the inner periphery to the outer periphery can be used as well.

In the present invention, the light absorbing portion disposed so as to be in contact with the recording layer of the recording medium can be configured in an island shape in the circumferential direction. The light absorbing portions are arranged in an island shape with regularity at positions adjacent to each other.
The schematic diagram of FIG. 7 shows a cross section (7a) and an arrangement (7b) when the light absorbing portion in the optical recording medium of the present invention is configured in an island shape in the circumferential direction. FIG. 7A shows a cross section of the optical recording medium. The direction parallel to the paper surface is the radial direction of the medium, and the direction perpendicular to the paper surface is the direction along the track.

  In this configuration, the dielectric layer 107 is provided on the substrate 101. The dielectric layer 107 is for preventing the influence of deformation of the substrate due to heat. On the heat insulation part 103, the light absorption part 102 is arranged in an island shape (round part in the figure). The light absorbers 102 are regularly arranged along the track as shown in FIG. 7B. As shown in FIG. 7B, the arrangement may be such that the island-like structures of the light absorbing portions 102 on the adjacent tracks are staggered, but the island-like structures of the adjacent tracks are mutually connected as shown in the schematic diagram of FIG. The structure arrange | positioned adjacently may be sufficient.

  For example, when light for recording is irradiated to the spot position 201, a recording mark is formed in the region of the recording layer 104 formed on the upper surface of the light absorbing portion 102. Since the light intensity in the light spot has a Gaussian distribution, the temperature near the center of the light spot is high (the shaded area in the figure), but the intensity of the portion near the edge of the light spot is not recorded. By adjusting to, recording can be performed only on the recording layer portion. That is, recording is performed only on the region of the recording layer on the light absorbing portion near the center of the light spot. As a result, it is possible to prevent the influence on the adjacent track and to reduce the displacement of the recording mark in the direction along the track. The same effect can be obtained even in a structure in which the arrangement of the light absorbing portion 102 and the heat insulating layer 103 is reversed.

Next, a method for manufacturing an optical recording medium in the present invention will be described.
In the case of the structure shown in FIG. 1, that is, the structure in which the heat insulating portion provided on the substrate is formed in a convex shape on one surface of the light absorbing portion, the following is performed. Although described with reference to the schematic process diagram of FIG. 9, an example in which a buffer layer 1102 is formed between the substrate 1101 and the light absorbing layer 1103 for the light absorbing portion in the drawing is taken as an example. Reference numeral 1104 denotes a thin film for forming a convex heat insulating portion.

  That is, the optical recording medium manufacturing method includes a step of sequentially laminating a light absorbing layer 1103 for a light absorbing portion on a substrate 1101 and a thin film 1104 for forming a heat insulating portion on one surface thereof, and from the thin film 1104 side. A step of modifying the thin film so as to have a predetermined convex shape by irradiating light, a step of removing unnecessary portions not modified by the light irradiation by etching to form a convex shape, and an upper surface of the structure formed by etching Forming a recording layer on the optical recording medium. In FIG. 9, the recording layer forming step is omitted.

  In FIG. 9, (110) shows the process of laminating | stacking the light absorption layer 1103 for light absorption parts on a board | substrate, and the thin film 1104 for forming a heat insulation part on the one surface. (111) indicates a step of modifying the thin film so as to have a predetermined convex shape by irradiating light (laser light) from the thin film side. (112) shows a step of removing an unnecessary portion that is not modified by the light irradiation by etching to form a convex shape.

In the step (111), (1111) indicates the irradiation direction of the laser beam. Laser light is irradiated from the thin film 1104 side for forming a convex shape. Reference numeral 1112 denotes a modified portion by laser light irradiation. Due to the heat generation of the light absorption layer, the material density, crystal state, composition, etc. of the thin film are changed and modified. Reference numeral 1113 denotes a laser beam irradiation method. P1 and P2 indicate laser power levels. The power level is changed by 2 levels. The laser power level is set to a relationship of P1> P2, and the period S and the period T1 held at the P1 level are changed according to the shape to be manufactured.

In the step (111), reference numeral 1121 denotes a heat insulating portion having a convex shape. Processing into such a form can be performed by solution etching. In this case, as the etching solution, an aqueous solution containing hydrofluoric acid (hydrofluoric acid) can be used.
The thin film modified in the step (111) is immersed in a hydrofluoric acid solution, and unnecessary portions that are not modified by the light irradiation, so-called unrecorded portions are removed. Etching using such a solution differs in the material density, crystal state, composition, etc. of the thin film between the part modified by light irradiation and the part not modified by non-irradiation. The ratio, that is, the selection ratio increases, and the necessary convex portion remains. Although omitted in FIG. 9, a recording layer (for example, bismuth oxide) whose optical properties change due to heat alteration and / or deformation is formed on the upper surface of the etched structure.

Further, since the material of the thin film for forming the heat-insulating portion having a convex shape is different from the light-absorbing layer for the light-absorbing portion serving as the base, the selection ratio with the base can be increased. Therefore, in a large-area device such as an optical recording medium, a structure having good in-plane uniformity and a convex shape can be created. Therefore, a fine convex structure can be formed in a large area by a maskless process that does not use photolithography.
By the above manufacturing method, an optical recording medium in which cross light and cross erase are suppressed can be manufactured.

Further, in the case of the structure shown in FIG. 4, that is, the structure in which the light absorbing portion 102 provided on the substrate is formed in a convex shape on one surface of the heat insulating portion 103, the process shown in FIG. Done.
That is, the optical recording medium manufacturing method in this case includes a step of sequentially laminating a heat insulating layer for a heat insulating portion on the substrate and a thin film for forming a light absorbing portion on one surface thereof, and a light from the thin film side. To modify the thin film so as to have a predetermined convex shape, to remove unnecessary portions that are not modified by the light irradiation by etching, and to form a convex shape, and to the upper surface of the structure formed by etching A method of manufacturing an optical recording medium including at least a step of forming a recording layer. In FIG. 10, the recording layer forming step is omitted.

In the first step, a heat insulating layer 3103 for the heat insulating portion is laminated on the substrate 3101 and a thin film 3102 for forming a light absorbing portion on one surface thereof, and in the next step, light (laser light) is emitted from the thin film side. Irradiation modifies the thin film to have a predetermined convex shape. In a subsequent process, an unnecessary portion that is not modified by light irradiation, that is, a so-called unrecorded portion, is etched to form a structure that leaves only the modified portion. As an etchant, an acid such as sulfuric acid or nitric acid, an alkaline solution, or the like can be used.
Etching using such a solution differs in the material density, crystal state, composition, etc. of the thin film between the part modified by light irradiation and the part not modified by non-irradiation. The ratio, that is, the selection ratio increases, and the necessary convex portion remains. Although not shown in FIG. 10, a recording layer (for example, bismuth oxide) whose optical properties are changed by heat alteration and / or deformation is formed on the upper surface of the etched structure.

  The laser light irradiation conditions are the same as in FIG. That is, P1 and P2 indicate laser power levels. The power level is changed by 2 levels. The laser power level is set to a relationship of P1> P2, and the period S and the period T1 held at the P1 level are changed according to the shape to be manufactured.

Similarly to FIG. 9 described above, since the material of the thin film for forming the heat-insulating layer for the heat-insulating part serving as the base and the light-absorbing part having the convex shape is different, the selectivity with the base can be increased. . Therefore, in a large-area device such as an optical recording medium, a structure with good in-plane uniformity and a convex shape can be produced. Therefore, a fine convex structure can be formed in a large area by a maskless process that does not use photolithography.
By the above manufacturing method, an optical recording medium in which cross light and cross erase are suppressed can be manufactured.

  Further, in the case of the structure shown in FIG. 5, that is, the structure in which the light absorption parts 102 and the heat insulation parts 103 are alternately formed in the same plane, the process is performed in accordance with the process shown in FIG.

  That is, in the method of manufacturing an optical recording medium, a thin film (abbreviated as a heat insulating part) 4103 for forming a heat insulating part and a light absorbing thin film (abbreviated as a light absorbing layer) 4102 are sequentially laminated on a substrate 4101 (1). And a step (2) of irradiating the thin film for forming the heat insulating portion and the light absorbing thin film with light to modify the thin film so as to have a predetermined shape, and a portion of the thin film not modified by the light irradiation. A step (3) of removing by etching with hydrofluoric acid, a step (4) of crystallizing the light-absorbing thin film on the formed heat insulating portion and removing the thin film with an alkaline solution, and the heat insulating portion A step (5) of laminating a thin film for forming a light absorbing portion on the upper surface of the formed structure, and a portion to be left of the thin film for forming the light absorbing portion is made amorphous by light irradiation to form a crystal A step (6) of removing the thin film in an activated state with an alkaline solution; Forming a recording layer on the structures formed top and (7) including at least manufacturing method.

In the step of modifying the thin film, the thin film for forming the heat insulating portion is modified by changing the density, changing the crystal structure, or the like. Further, in the step of removing the unmodified portion of the thin film by etching with hydrofluoric acid, since the heat insulating portion is dissolved in the etching solution, the light absorption layer is also removed by lift-off. Furthermore, the thin film in the crystallized state on the heat insulating part can be removed with an alkaline solution.
Similarly to the above, this manufacturing method makes it possible to produce an optical recording medium in which cross light and cross erase are suppressed.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples without departing from the gist thereof.

Example 1
An optical recording medium of the present invention having the configuration shown in FIG. 12 was produced.
In FIG. 12, the substrate 101 is made of polycarbonate and has a thickness of 0.6 mm. A dielectric was used as the buffer layer 108. The dielectric is a composite compound of ZnS · SiO ₂ (ZnS: SiO ₂ = 8: 2), and the film thickness is 50 nm. The light absorbing portion 102 is AgInSbTe, and the film thickness is 20 nm. The heat insulating part 103 is a composite compound containing ZnS and SiO ₂ , and the height from the upper surface of the light absorbing part is 50 nm. The track direction period 109 of the convex heat insulating portion is 200 nm. A bismuth oxide layer having a thickness of 10 nm was provided as a recording layer 104 on the upper surface to obtain an optical recording medium.

  Recording was performed with a laser beam using the optical recording medium. The laser beam used for recording has a wavelength of 405 nm and the numerical aperture of the objective lens is 0.85. Recording was performed by irradiating light with a pulse width of 50 nsec at a recording power of 4 mW.

  When the recording mark was observed with a scanning electron microscope, the recording mark was formed where the light absorbing portion and the recording layer were in contact. A schematic diagram thereof is shown in FIG. It is the external appearance schematic diagram which observed a part of optical recording medium from the top. Reference numeral 301 denotes an area where the heat insulating portion is below the recording layer. Reference numeral 302 denotes a recording mark. The spot of light was about 400 nm, and recording in a narrow area was possible although it was considerably larger than the period in the track direction.

(Example 2)
The optical recording medium of the present invention having the structure shown in FIG. 7 was produced.
The substrate 101 is made of polycarbonate and has a thickness of 0.6 mm. The dielectric layer 107 is SiN and has a thickness of 50 nm. A composite compound of ZnS · SiO ₂ (ZnS: SiO ₂ = 8: 2) was used for the heat insulating portion 103, and the film thickness was set to 45 nm. An SbTe layer having a thickness of 20 nm was formed in an island shape on the light absorbing portion 102 thereon. Here, the track pitch, that is, the pitch of the island-shaped light absorbing portions is 137 nm. A bismuth oxide film having a thickness of 15 nm was formed thereon as a recording layer.

Recording was performed with a laser beam using the optical recording medium. The laser beam used for recording has a wavelength of 405 nm and the numerical aperture of the objective lens is 0.85. The recording power was 4 mW, and recording was performed by irradiating pulsed light in accordance with the pitch in the direction along the track of the island-shaped light absorber.
A plurality of island-like regions are included in the light spot, but since recording can be performed only near the center of the light spot, a recording mark was formed so as to follow the island-like structure.

(Example 3)
The optical recording medium of the present invention having the structure shown in FIG. 7 was produced.
That is, each constituent layer was formed in the same manner as in Example 2 except that 50 nm thick Ag was used as the heat insulating layer.
Recording was performed with a laser beam using the optical recording medium. The laser beam used for recording has a wavelength of 405 nm and the numerical aperture of the objective lens is 0.85. The recording power was 4 mW, and recording was performed by irradiating pulsed light in accordance with the pitch in the direction along the track of the island-shaped light absorber.
A recording mark was formed on the recording layer corresponding to the shape of SbTe, which is a light-absorbing portion formed in a convex shape, in the recording layer in the portion in contact with Ag.

Example 4
An optical recording medium was manufactured by the method for manufacturing an optical recording medium according to the present invention having the configuration shown in FIG.
That is, the material of the substrate 1101 in FIG. 9 is polycarbonate. The material of the buffer layer 1102 is a composite compound of ZnS · SiO ₂ (ZnS: SiO ₂ = 8: 2), and the film thickness is 50 nm. The material of the light absorption layer 1103 is AgInSbTe, and the film thickness is 20 nm. The material of the thin film 1104 forming the convex heat insulating portion is ZnS · SiO ₂ (ZnS: SiO ₂ = 8: 2). The film thickness of this heat insulating part was 100 nm and was set to λ / 4 (405 nm / 4≈100 nm). Each layer was formed by sputtering. Film formation was performed at room temperature in an Ar atmosphere.
The optical recording medium was manufactured by the process described above. Step (111) and step (112) are as follows.

Step (111) in FIG. 9:
Laser light 1111 was irradiated from the thin film 1104 side for forming a convex heat insulating portion, and the shape of the structure to be manufactured was determined. The wavelength of the used laser light is 405 nm, and the numerical aperture of the objective lens is 0.85. The modified portion 1112 is a portion left as a convex heat insulating portion, and is ZnS · SiO ₂ (ZnS: SiO ₂ = 8: 2). Here, the part to be left as the convex heat insulating part is a part that is transformed into a crystalline phase, and the unnecessary part to be removed is an amorphous phase.

  The processing method for forming the convex shape in the step (111) was performed in accordance with the laser light power level modulation method shown in 1113. The power level was modulated at two levels of P1 = 5 mW and P2 = 0.7 mW. T1 indicates a period during which the P1 level is maintained, that is, a pulse width. S indicates the pulse irradiation timing, that is, the recording cycle. T1 = 15 nsec and S = 57 nsec. Under these conditions, single-period light with a period of 200 nm was irradiated.

Step (112) in FIG. 9:
FIG. 9 (112) shows an etching process. Unnecessary portions of the thin film (ZnS—SiO ₂ ) for forming a convex heat insulating portion after light irradiation were removed and processed into a convex shape. Reference numeral 1121 denotes a convex structure. Unnecessary portions were removed by solution etching. As the etching solution, a mixed liquid of hydrofluoric acid (HF) and water (H ₂ O) was used. A 50% diluted solution was used as hydrofluoric acid. The solution ratio is HF: H ₂ O = 1: 2. The recording medium was immersed in the solution for 10 seconds. After etching, it was immediately washed with water and dried with dry nitrogen or the like. A recording layer was formed on the upper surface of the resulting structure having a convex heat insulating portion.
A recording medium having a convex heat insulating part was produced by the above method. By this method, it is possible to form an optical recording medium composed of a structure having a fine convex heat insulating portion in a large area without a mask.

(Example 5)
An optical recording medium was manufactured by the method for manufacturing an optical recording medium according to the present invention having the configuration shown in FIG.
That is, the material of the substrate 3101 in FIG. 10 is polycarbonate. The material of the light absorption layer 3102 is Sb ₇₅ Te ₂₅ and the film thickness is 20 nm. The material of the heat insulating part 3103 is ZnSSiO ₂ and the film thickness is 50 nm. Each layer was formed by sputtering. Film formation was performed at room temperature in an Ar atmosphere.
The optical recording medium was manufactured by the process described above. Step (311) and step (312) are as follows.

Step (311) in FIG. 10:
Laser light 3111 was irradiated from the thin film 3102 side for forming a convex light absorption portion, and the shape of the structure to be manufactured was determined. The wavelength of the used laser light is 405 nm, and the numerical aperture of the objective lens is 0.85. The modified portion 3112 is a portion that remains as a convex light absorbing portion, and is SbTe. Here, the portion to be left as the convex light absorbing portion is an amorphous phase, and the unnecessary portion is a crystalline phase. The whole is made into a crystalline phase in advance.

  The processing method for forming a convex shape in the step (311) was performed in accordance with the laser light power level modulation method shown in 3113. The power level was modulated at two levels of P1 = 4 mW and P2 = 1.2 mW. T1 indicates a period during which the P1 level is maintained, that is, a pulse width. S indicates the pulse irradiation timing, that is, the recording cycle. T1 = 15 nsec and S = 57 nsec. Under these conditions, single-period light with a period of 200 nm was irradiated.

FIG. 10 (312) shows an etching process. A thin film for forming a convex light absorbing portion after light irradiation, that is, an unnecessary portion of Sb ₇₅ Te ₂₅ was removed and processed into a convex shape. Unnecessary portions were removed by solution etching. An alkaline solution was used as the etching solution. The recording medium was immersed in the solution for 10 seconds. After etching, it was immediately washed with water and dried with dry nitrogen or the like. A recording layer was formed on the upper surface of the obtained structure having a convex light absorbing portion.
A recording medium having a convex light absorbing portion was produced by the above method. By this method, it is possible to form an optical recording medium comprising a structure having a light-absorbing portion having a fine convex shape in a large area without a mask.

(Example 6)
An optical recording medium was manufactured by the method for manufacturing an optical recording medium according to the present invention having the configuration shown in FIG.
That is, the material of the substrate 4101 in FIG. 11 is polycarbonate. The material of the light absorption layer 4102 is Ag ₃ In ₁₁ Sb ₇₅ Te ₁₁ and the film thickness is 20 nm. The material of the heat insulating part 4103 is ZnSSiO ₂ and the film thickness is 50 nm. Each layer was formed by sputtering. Film formation was performed at room temperature in an Ar atmosphere. The optical recording medium was manufactured according to the above-mentioned steps (1) to (7). The outline of the production is as follows.

  In step (1), a thin film (heat insulating part 4103) and a light absorbing thin film (light absorbing layer 4102) for forming a heat insulating part on the substrate are laminated, and in step (2) laser light is projected as shown in the figure. The shape of the structure to be produced was determined by irradiating from the thin film side forming the shaped structure. The wavelength of the used laser light is 405 nm, and the numerical aperture of the objective lens is 0.85.

In this case, the material of the light absorption layer 4102 indicates a portion left as a structure of Ag ₃ In ₁₁ Sb ₇₅ Te ₁₁ . The portion that remains as a structure is an amorphous phase, and the unnecessary portion is a crystalline phase. That is, the whole is made into a crystalline phase in advance, and the portion left as a structure by light irradiation is made an amorphous phase.
The processing method for forming a convex structure in the above process was the same as in Example 4 described above, that is, performed according to the laser light power level modulation method. The power level was modulated at two levels of P1 = 5 mW and P2 = 0.7 mW. T1 indicates a period during which the P1 level is maintained, that is, a pulse width. S indicates the pulse irradiation timing (recording cycle). T1 = 15 nsec and S = 57 nsec. Under these conditions, single-period light with a period of 200 nm was irradiated.

The outline of the steps (3) to (7) was performed as follows. That is, unnecessary portions of the thin film that were not modified by light irradiation were removed and processed into a thin film (Ag ₃ In ₁₁ Sb ₇₅ Te ₁₁ that forms a convex structure. Light absorption formed on the heat insulating portion Unnecessary portions of the thin film were removed by crystallization by light irradiation, followed by solution etching, using an alkaline solution as the etching solution, and immersing the recording medium in the solution for 10 seconds. The light irradiation conditions for the first time were the same except that P1 and P2 in the first time were changed to P1 = 4 mW and P2 = 1.2 mW, respectively.
After etching, it was immediately washed with water and dried with dry nitrogen or the like. A recording layer was formed on the upper surface of the structure in which the obtained light absorbing portions and heat insulating portions were alternately arranged.
By this method, it is possible to form an optical recording medium composed of a structure having a fine light absorbing portion in a large area without a mask.

1 is a schematic cross-sectional view orthogonal to a track showing a configuration example for explaining an optical recording medium of the present invention. It is a schematic diagram for demonstrating the recording mark formed when light is irradiated to the optical recording medium provided with the light absorption part and heat insulation part in this invention. It is a schematic diagram for demonstrating the recording mark formed when light is irradiated to the optical recording medium without a heat insulation part and having only a light absorption part. It is a schematic sectional drawing orthogonal to the track | truck which shows another structural example for demonstrating the optical recording medium of this invention. It is a schematic sectional drawing orthogonal to the track | truck which shows another structural example for demonstrating the optical recording medium of this invention. It is a top view which shows typically the state in which the light absorption part and heat insulation part in the optical recording medium of this invention were each cyclically | annularly formed in the radial direction. It is a schematic diagram which shows the cross section (7a) at the time of comprising the light absorption part in the optical recording medium of this invention in island shape in the circumferential direction, and arrangement | positioning (7b). It is a schematic diagram which shows the state by which the island-like structure of the adjacent track | truck is arrange | positioned adjacent to each other in the optical recording medium of this invention. FIG. 5 is a schematic process diagram for explaining a method of manufacturing an optical recording medium in the present invention. It is a schematic process drawing for demonstrating another manufacturing method of the optical recording medium in this invention. It is a schematic process drawing for demonstrating another manufacturing method of the optical recording medium in this invention. FIG. 3 is a schematic cross-sectional view orthogonal to the track, showing the configuration of the optical recording medium in Example 1. FIG. 2 is a schematic external view of a recording mark of an optical recording medium in Example 1 observed with a scanning electron microscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Thermal control area 101 Substrate 102 Light absorption part 103 Heat insulation part 104 Recording layer

Claims (10)

In an optical recording medium having a thermal control region on a substrate and a recording layer whose optical characteristics change due to alteration and / or deformation due to heat, the thermal control region absorbs irradiation light and easily generates heat. easily generates heat without a heat insulating portion, wherein the light absorption of the heat insulating portions in the wavelength of the irradiated light being smaller than the light absorption of the light absorbing portion, the heat insulating portion is convex on one surface of the light absorbing portion and wherein said light absorbing portion is formed in a shape heat insulating portion is arranged so as to be in contact with the recording layer alternately, and the heat insulating portion and the light absorbing portion is formed in an annular or spiral-shaped in the radial direction, respectively An optical recording medium characterized by the above . In an optical recording medium having a thermal control region on a substrate and a recording layer whose optical characteristics change due to alteration and / or deformation due to heat, the thermal control region absorbs irradiation light and easily generates heat. easily generates heat without a heat insulating portion, wherein the light absorption of the heat insulating portions in the wavelength of the irradiated light being smaller than the light absorption of the light absorbing portion, the light absorbing portion is convex on one surface of the insulating part and wherein said light absorbing portion is formed in a shape heat insulating portion is arranged so as to be in contact with the recording layer alternately, and the heat insulating portion and the light absorbing portion is formed in an annular or spiral-shaped in the radial direction, respectively An optical recording medium characterized by the above . In an optical recording medium having a thermal control region on a substrate and a recording layer whose optical characteristics change due to alteration and / or deformation due to heat, the thermal control region absorbs irradiation light and easily generates heat. And a heat insulating part that does not easily generate heat, and the light absorption of the heat insulating part is smaller than the light absorption of the light absorbing part at the wavelength of the irradiated light, and the light absorbing part and the heat insulating part are in the same plane. wherein said light absorbing portion while being formed are formed insulating part is arranged so as to be in contact with the recording layer alternately, and the heat insulating portion and the light absorbing portion is configured in an annular or spiral-shaped in the radial direction, respectively An optical recording medium. The optical recording medium according to claim 1, wherein the recording layer is bismuth oxide. The optical recording medium according to claim 1, wherein the light absorbing portion is made of a compound containing Sb and / or Te. The optical recording medium according to claim 1 or 3 wherein the heat insulating portion is characterized by comprising a compound containing ZnS. The optical recording medium according to claim 2 , wherein the heat insulating portion is made of any metal selected from Ag, Al, and Cu. On the substrate, there is a heat control region and a recording layer whose optical properties change due to alteration and / or deformation due to heat based on light irradiation, and the heat control region absorbs light and absorbs light easily. and a parts and easily generates heat without the heat insulating portion, wherein the light absorption of the heat insulating portions in the wavelength of the irradiated light being smaller than the light absorption of the light absorbing portion, the heat insulating portion on a surface of the light absorbing portion wherein said light absorbing portion is formed in a convex heat-insulating portions are arranged so as to be in contact with the recording layer alternately, and the heat insulating portion and the light absorbing portion is configured in an annular or spiral-shaped in the radial direction, respectively An optical recording medium manufacturing method comprising:
A step of sequentially laminating a light absorbing layer for a light absorbing portion on the substrate and a thin film for forming a heat insulating portion on one surface thereof;
Irradiating light from the thin film side to modify the thin film to have a predetermined convex shape;
Removing unnecessary portions that are not modified by the light irradiation by etching and forming a convex shape;
Forming a recording layer on the top surface of the etched structure;
A method for producing an optical recording medium comprising at least On the substrate, there is a heat control region and a recording layer whose optical properties change due to alteration and / or deformation due to heat based on light irradiation, and the heat control region absorbs light and absorbs light easily. and a parts and easily generates heat without the heat insulating portion, wherein the light absorption of the heat insulating portions in the wavelength of the irradiated light being smaller than the light absorption of the light absorbing portion, on one surface of the light absorbing portion heat insulating portion wherein said light absorbing portion is formed in a convex heat-insulating portions are arranged so as to be in contact with the recording layer alternately, and the heat insulating portion and the light absorbing portion is configured in an annular or spiral-shaped in the radial direction, respectively An optical recording medium manufacturing method comprising:
A step of sequentially laminating a heat insulating layer for the heat insulating portion on the substrate and a thin film for forming a light absorbing portion on one surface thereof;
Irradiating light from the thin film side to modify the thin film to have a predetermined convex shape;
Removing unnecessary portions that are not modified by the light irradiation by etching and forming a convex shape;
Forming a recording layer on the top surface of the etched structure;
A method for producing an optical recording medium comprising at least On the substrate, there is a heat control region and a recording layer whose optical properties change due to alteration and / or deformation due to heat based on light irradiation, and the heat control region absorbs light and absorbs light easily. and a parts and easily generates heat without the heat insulating portion, wherein the light absorption of the heat insulating portions in the wavelength of the irradiated light being smaller than the light absorption of the light absorbing portion, the heat insulating portion and the light absorbing portion in the same plane wherein said light absorbing portion is formed in a heat insulating portion is arranged so as to be in contact with the recording layer alternately, and an optical recording constructed heat insulating portion and the light absorbing portion in the annular or spiral-shaped in the radial direction, respectively A method for producing a medium, comprising:
A step of sequentially laminating a thin film for forming a heat insulating part on the substrate and a light absorbing thin film;
Irradiating light to the thin film for forming the heat insulating part and the light absorbing thin film to modify the thin film so as to have a predetermined shape;
Etching the portion of the thin film that is not modified by the light irradiation with hydrofluoric acid to remove it;
Crystallizing the light-absorbing thin film on the formed heat insulating portion and removing the thin film with an alkaline solution;
Laminating a thin film for forming a light absorbing portion on the upper surface of the structure on which the heat insulating portion is formed;
A step of amorphizing the portion of the thin film for forming the light absorbing portion to be left amorphous by light irradiation, and removing the thin film in a crystallized state with an alkaline solution;
Forming a recording layer on the upper surface of the formed structure;
A method for producing an optical recording medium comprising at least

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