CN1905971A - Structure body and method of producing the structure body, medium for forming structure body, and optical recording medium and method of reproducing the same - Google Patents

Abstract

A structure body and method of producing the structure body, medium for forming structure body, and optical recording medium and method of reproducing the same. The producing method of the structure body comprises: a light irradiation step irradiating a medium for forming structure body having a stacked composition containing a light absorption layer which contains a light absorption material, and a thermal reaction layer which contains a thermal reaction material; an etch step etching the medium for forming structure which is irradiated with light. A fine structure body is uniformly produced on a large medium by constructing a medium for forming a structure body as a layered structure where a light absorbing layer for absorbing light to produce heat and a thermal reaction layer for reacting to heat are separated.

Description

Structure, manufacturing method thereof, forming medium, optical recording medium and reproduction method thereof

technical field

The present invention relates to a method for manufacturing a structure, a medium for forming a structure used in the method for manufacturing a structure, a structure obtained by the method for manufacturing a structure, and an optical recorder for recording and reproducing information through the structure (concave-convex pattern) Medium and method for reproducing the optical recording medium.

Background technique

In recent years, playback-only optical recording media (hereinafter also referred to as "ROM discs") composed of microstructures have spread widely, centered on DVD-ROMs. And the development of blue laser high-density ROM disk is also very fast.

The ROM disc records information in a concavo-convex pattern, and is usually manufactured through a complicated process including an original disc production process, a master disc production process, and a replication process.

The mastering process is performed in the order of (1) exposing the photoresist by irradiation with laser beams and electron beams, (2) forming a pattern by developing the resist, and (3) etching the substrate with the resist as a mask. to make the original disc.

In the mastering process, the mastering process is performed in the steps of (1) plating nickel (Ni) on the master and (2) stripping Ni.

In the copying step, a predetermined concave-convex pattern is copied on a resin material by using the master disc as a model.

Trial recording (authoring) is performed for the purpose of confirming and adjusting recording conditions, compression efficiency, coating, and the like in the manufacturing process of the ROM disc. There is a limit in terms of cost to use a ROM disk manufactured through all the steps of the ROM disk manufacturing process for this originality. Therefore, a recording medium having a recording layer containing a phase change material and an organic dye is used as a trial recording medium (hereinafter referred to as "original medium") for easy confirmation of originality. Patent Document 1 and Patent Document 2 disclose such an original medium, for example.

However, the conventional optical recording medium for recording information by the concave-convex pattern has a problem that it is difficult to reproduce fine concave-convex as the density increases. In order to solve this problem, for example, mastering technology of high-density electron beam drawing has been proposed (see Patent Document 3 and Patent Document 4).

However, the sensitivity of the resist to electron beams in the above electron beam drawing is not sufficient, and since the process is performed in a vacuum, the productivity is unavoidably low. In addition, the electron beam drawing device is very expensive and requires a huge initial investment. In addition, maintenance is difficult, and compared with laser beam exposure, the running cost is also high, and the production capacity is low. Therefore, there is a problem that processing costs increase due to an increase in initial investment and an increase in operating costs.

As a means to solve the problem of high processing costs associated with miniaturization, for example, a method of forming a fine concave-convex pattern with a laser beam has been developed. This method is a method of patterning by providing a thermally degraded layer, degrading a region smaller than the beam diameter, and removing the non-degraded region by etching.

For example, Patent Document 5 proposes a method of irradiating a phase change film such as GeSn with laser light to crystallize it, and removing an amorphized portion by etching to form a concave-convex pattern (structure). It also discloses a method of first forming an auxiliary thin film, etching the auxiliary film once to form grooves, and then etching the formed phase change film again. Patent Document 6 discloses a method of forming a concavo-convex pattern (structure) by irradiating a chalcogenide such as GeSbTeSn with laser light to crystallize it and removing the non-crystallized portion by etching.

However, in order to form a structure with good uniformity on a large-area substrate such as an optical disk, it is necessary to have a large difference in etching ratio (etching selectivity) between the portion that becomes the structure and other portions. In the case of a phase change material, the etching selectivity ratio between the crystalline state and the non-crystalline state (amorphous state) is small. Furthermore, there may be an intermediate state between a crystalline state and an amorphous state. Therefore, the methods described in Patent Documents 5 and 6 are difficult to uniformly form microstructures on a large-area medium. In addition, the manufacturing method disclosed in Patent Document 5 requiring two etching steps has a disadvantage of incurring high processing costs.

In Patent Document 7 and Patent Document 8, there is a proposal to irradiate laser light on a heat-sensitive material formed by laminating two metal materials such as Al/Cu to form a reaction part where the two metal materials diffuse each other (the reaction part becomes two kinds of metal materials). Alloy of metal material), a method of forming a structure by removing unreacted parts by etching.

Patent Document 9 discloses a method of forming a structure by irradiating a laser beam to a laminated structure composed of two inorganic materials such as Au/Sn to form a reactive portion where the two materials diffuse each other, and removing the unreacted portion by etching. .

However, in these methods, the film thickness distribution of the two materials that diffuse each other is the composition distribution that becomes part of the structure as it is, and the etching rate varies as long as the composition is different, so it is possible to uniformly form a microstructure for a large-area medium. body is difficult.

In Patent Document 10, there is a proposal to irradiate laser light to a laminated structure of a thermally sensitive layer composed of a light-absorbing thermal conversion layer such as GeSbTe and a chemically amplified resist used in photolithography to modify the thermally sensitive layer. , A method of forming a structure by removing unaltered parts by etching.

However, the material for forming the structure in Patent Document 10 is also a light-absorbing material, and the method of using this light-absorbing material as the material for forming the structure is not suitable for forming a structure with a high depth ratio (pattern height/structure size). Body is not suitable. That is, when forming a structure with a high depth ratio, it is necessary to increase the thickness of the layer forming the structure. However, if the film is thickened, heat will spread within the layer, preventing miniaturization.

Therefore, a structure manufacturing method capable of forming microstructures with simple processing and low cost without using photolithography and an optical recording medium having uniform structures on a large-area medium have not yet been provided, and it is hoped that they will be provided quickly. .

Patent Document 1: Japanese Unexamined Patent Publication No. 11-328738

Patent Document 2: JP-A-2001-126255

Patent Document 3: JP-A-2001-344833

Patent Document 4: JP-A-2003-051437

Patent Document 5: Japanese Unexamined Patent Publication No. 9-115190

Patent Document 6: JP-A-10-97738

Patent Document 7: JP-A-2001-250279

Patent Document 8: JP-A-2001-250280

Patent Document 9: JP-A-2003-145941

Patent Document 10: JP-A-2002-365806

Contents of the invention

The present invention solves the existing problems and in accordance with the above-mentioned desires, and aims to provide a structure-forming medium that forms a structure as a laminated structure of a light-absorbing layer and a heat-reactive layer. A method for producing a structure in which a layer and a heat-reactive layer that reacts with heat to form a structure can be separated to form a microstructure with simple processing and low cost without using photolithography, and a structure used in the method for producing a structure A medium for forming a body, and a structure obtained by the structure manufacturing method.

An object of the present invention is to provide a high-density optical recording medium that can be densified without reducing productivity, can record information in a concave-convex pattern (structure), and can be used appropriately as an original medium.

An object of the present invention is to provide an information reproducing method using the optical recording medium of the present invention.

In order to solve the above-mentioned problems, the inventors of the present invention, as a result of intensive discussions, have found that microstructures can be formed at low cost by simple processing without using photolithography, and in particular, by using a medium for forming structures as a light-absorbing layer and heat The laminated structure of the reaction layer, and the separation of the light absorbing layer that absorbs light and generates heat from the thermally reactive layer that reacts with heat to become a structure can uniformly form microstructures on a large-area medium.

It is also recognized that the present invention is preferably: (1) can form a finer structure by irradiating light without passing through the substrate; The structure can be formed with a high depth ratio (height of the structure/size of the structure) at the same time (3) By using the wet etching method, it is possible to form micro The structure (4) can form a microstructure with low-cost processing and equipment by using laser light as the light and semiconductor laser as the laser light source. Spin to form microstructures at high speed on large area media.

The present invention is based on the above findings of the present inventors, and means for solving the above-mentioned problems are as follows. Right now

<1> The medium for forming a structure has a laminated structure in which at least a light-absorbing layer containing a light-absorbing material and a heat-reactive layer containing a heat-reactive material are laminated.

<2> In the medium for forming a structure as described in <1> above, the thermally reactive layer is located on the uppermost layer of the laminated structure, and the thermally reactive layer contains a material that is transparent to the wavelength of the irradiated light.

<3> In the medium for forming a structure described in any one of <1> to <2> above, the thermally reactive layer contains a mixture of material A and material B, the material A is a silicon compound material, and the material B It is at least one selected from sulfide materials, selenide materials, and fluorine compound materials.

In the structure-forming medium described in any one of <1> to <3> above, the laminated structure of the light-absorbing layer and the heat-reactive layer is formed by reacting the light-absorbing layer that absorbs light and generates heat with heat. By separating the heat-reactive layers that become structures, microstructures can be uniformly formed.

<4> A method for manufacturing a structure, including: a light irradiation step for forming a structure having a laminated structure in which at least a light-absorbing layer containing a light-absorbing material and a heat-reactive layer containing a heat-reactive material are laminated. The medium is irradiated with light; and an etching process is performed on the structure-forming medium irradiated with the light.

The method for producing a structure of the present invention can form a microstructure with simple processing and low cost without using a photolithography method through a photoirradiation step and an etching process. In particular, by using the medium forming the structure as a laminated structure of a light-absorbing layer and a heat-reactive layer, and separating the light-absorbing layer that absorbs light and generates heat from the heat-reactive layer that reacts with heat to become a structure, the The thinning of the layer that absorbs heat and generates heat can suppress the spread of heat by thinning the layer, so that a microstructure can be uniformly formed.

<5> In the structure manufacturing method described in <4> above, the thermally reactive layer is located on the uppermost layer of the laminated structure, and the thermally reactive layer contains a material transparent to the wavelength of the irradiated light. In the structure manufacturing method described in <5>, the thermal reaction layer is disposed on the uppermost layer of the laminated structure and is formed of a light-transmitting material, and at the same time, light is irradiated from the uppermost thermal reaction layer side in the light irradiation step. . By using a material with high translucency for the thermally reactive layer, it is possible to suppress the thermally reactive layer from absorbing light, and the structure is formed only by heat generation of the light absorbing layer, so that the structure can be miniaturized. Since light is incident on the film surface without going through the substrate, the NA of the objective lens can be set large and the light beam can be focused, so the structure can also be miniaturized.

<6> In the structure manufacturing method described in any one of the above <4> to <5>, the heat reactive layer contains a mixture of material A and material B, the material A is a silicon compound material, and the material B is At least one selected from sulfide materials, selenide materials, and fluorine compound materials. In the structure manufacturing method described in <6>, since the etching selectivity ratio between light-irradiated and non-irradiated portions can be increased by using a specific material for the heat-reactive layer, microstructures can be uniformly formed on a large-area medium. . Furthermore, since this material is easy to increase the thickness of the film, it is possible to form a structure having a high depth ratio (structure height/structure size).

<7> In the structure manufacturing method according to any one of the above <4> to <6>, the light irradiation step is to irradiate light from the uppermost thermal reaction layer side.

<8> In the structure manufacturing method according to any one of the above <4> to <7>, the light irradiated in the light irradiation step is laser light.

<9> In the structure manufacturing method described in the above <8>, the laser light source is a semiconductor laser.

<10> The laser irradiation device used in the structure manufacturing method described in <9> above includes a semiconductor laser irradiation device for irradiating laser light onto the structure forming medium, a laser modulation device, and a medium drive device.

In the structure manufacturing method according to any one of <9> and <10>, by using a semiconductor laser as a laser light source, a microstructure can be formed with low-cost processes and equipment.

<11> In the method for manufacturing a structure according to any one of <8> to <10> above, the medium is rotated when the structure-forming medium is irradiated with laser light.

<12> The laser irradiation device used in the structure manufacturing method described in <11> above includes a laser irradiation device for irradiating laser light on the structure forming medium, a laser modulation device, a medium rotation device, and a signal detection device.

In the structure manufacturing method according to any one of <11> and <12>, by rotating the structure-forming medium when the structure-forming medium is irradiated with laser light, a microstructure can be formed on a large-area medium at high speed, Can reduce processing cost.

<13> In the structure manufacturing method according to any one of the above <4> to <12>, the etching step is performed by a wet etching method. In the structure manufacturing method described in <13>, microstructures can be formed with low-cost processing and high throughput by using the wet etching method without using a vacuum device.

<14> A structure produced by the method for producing a structure according to any one of the above <4> to <13>.

<15> In the structure described in <14> above, the cross-sectional end face shape of the structure is any one of a substantially vertical shape and a substantially inverted tapered shape.

<16> In the structure described in any one of <14> to <15> above, the structure is a convex structure formed on the surface of the optical recording medium.

<17> An optical recording medium comprising: a substrate, a light-absorbing layer that absorbs light on the substrate to generate heat, and a convex structure next to the light-absorbing layer that contains a material different from that of the light-absorbing layer. The shape structure is formed by the structure production method described in any one of the above <4> to <13>. The optical recording medium described in <17> can be densified without lowering productivity, can record information in a concavo-convex pattern (structure), and can provide a high-density optical recording medium suitable as an original medium at low cost.

<18> An optical recording medium comprising: a substrate, a light-absorbing layer that absorbs light on the substrate to generate heat, a convex structure next to the light-absorbing layer that contains a material different from that of the light-absorbing layer, and A light-transmitting layer having light-transmitting properties on a convex structure formed by the structure manufacturing method described in any one of <4> to <13> above, the light-transmitting layer The surface of the convex structure is covered to form a substantially hemispherical shape. The optical recording medium described in <18> can be densified without lowering productivity, can record information with concavo-convex, and can provide high-density optical recording with concavo-convex information used as an original medium at low cost.

<19> In the optical recording medium according to any one of the above <17> to <18>, the convex structure is substantially columnar.

<20> In the optical recording medium according to any one of the above <17> to <19>, the convex structure is substantially cylindrical, and the diameter of the convex structure changes according to the recording information.

<21> In the optical recording medium according to any one of the above <17> to <20>, the convex structures are substantially cylindrical, and the arrangement of the convex structures in the plane of the optical recording medium is a three-dimensional symmetrical arrangement. .

<22> In the optical recording medium described in any one of the above <17> to <21>, n track columns (n represents an integer greater than or equal to 2) in the radial direction of the optical recording medium are each provided with There is no track row of convex structures.

<23> In the optical recording medium according to any one of the above <17> to <22>, the light absorbing layer contains at least one element selected from Sb, Te, and In.

<24> In the optical recording medium described in any one of the above <17> to <23>, the convex structure contains a mixture of material A and material B, the material A is a silicon compound material, and the material B is At least one selected from sulfide materials, selenide materials, and fluorine compound materials.

<25> In the optical recording medium described in the above <24>, the convex structure contains a mixture of ZnS and SiO ₂ .

<26> In the optical recording medium according to any one of <17> to <25> above, a buffer layer is provided between the substrate and the light-absorbing layer.

<27> A method for reproducing an optical recording medium. The optical recording medium used has: a light-absorbing layer that absorbs reproducing light on a substrate to generate heat; The light-absorbing layer and the convex structure are irradiated with reproduced light from the side of the convex structure and the reflected light flux is detected.

<28> A method for reproducing an optical recording medium. The optical recording medium used has: a light-absorbing layer that absorbs reproducing light on a substrate to generate heat; structure and a light-transmitting layer on the convex structure that is transparent to reproduced light. The light-transmitting layer covers the surface of the convex structure to form a hemisphere. From the side of the light-transmitting layer, the A laminate composed of a light absorbing layer, a convex structure, and a light transmitting layer irradiates reproduced light and detects reflected light flux.

<29> In the method for reproducing an optical recording medium according to any one of <27> to <28> above, the convex structure is substantially columnar.

<30> In the method for reproducing an optical recording medium according to any one of <27> to <29> above, the convex structure is substantially cylindrical, and the diameter of the convex structure changes according to the recording information.

<31> In the method for reproducing an optical recording medium according to any one of the above <27> to <30>, the convex structures are substantially cylindrical, and the convex structures are arranged three times in the plane of the optical recording medium. symmetrical arrangement.

<32> In the method for reproducing an optical recording medium described in any one of the above <27> to <31>, the convex structure is irradiated with reproduction light to simultaneously reproduce a plurality of track rows, and the period of the convex structure is The reflected light flux is detected correspondingly.

<33> In the optical recording medium reproducing method described in any one of the above <27> to <32>, n track columns (n represents an integer greater than or equal to 2) in the radial direction of the optical recording medium each have A track row without a convex structure is provided.

<34> In the method for reproducing an optical recording medium as described in the above <33>, n-1 track rows are simultaneously reproduced and reflected light fluxes are detected.

Description of drawings

FIG. 1 shows an example of the medium for forming a structure of the present invention, which has a medium for forming a structure formed by laminating a substrate, a light-absorbing layer, and a heat-reactive layer in this order;

Fig. 2 shows an example of the medium for forming a structure of the present invention, which has a medium for forming a structure formed by laminating a substrate, a heat-reactive layer, a light-absorbing layer, and a heat-reactive layer in this order;

Fig. 3 shows an example of the medium for forming a structure of the present invention, which has a medium for forming a structure formed by laminating a substrate, a heat-reactive layer, and a light-absorbing layer in this order;

4 is a process diagram showing the light irradiation step in the structure manufacturing method of the present invention, showing (1) the structure forming medium, (2) the state of light irradiation, and (3) the state after light irradiation, respectively, from the top;

Fig. 5 is a process diagram showing the etching process in the structure manufacturing method of the present invention, which respectively shows (1) the state of the medium before etching, (2) the state of etching, and (3) the state after etching;

6 is a process diagram showing the heat treatment process in the structure manufacturing method of the present invention, showing (1) the state before heat treatment, (2) the state after heat treatment, and (3) the state after heat treatment, respectively, from the top;

7 is a process diagram showing the second etching process in the structure manufacturing method of the present invention, which respectively shows (1) the state of the medium before etching, (2) the state of etching, and (3) the state after etching;

Fig. 8 is a process diagram showing the duplication process in the structure manufacturing method of the present invention, which respectively shows (1) the state before duplication, (2) the duplication state, and (3) the media with the unevenness duplicated from the top;

9 is an explanatory view showing an example of the light irradiation step in the structure manufacturing method of the present invention, showing (1) the structure forming medium, (2) the state of light irradiation, and (3) the state after light irradiation;

10 is an explanatory diagram showing an example of the etching process in the method for manufacturing a structure of the present invention, and respectively shows (1) the state of the medium before etching, (2) the state of etching, and (3) the state after etching;

11 is an explanatory view showing an example of laser irradiation equipment used in the structure manufacturing method of the present invention;

12 is an explanatory view showing an example of another laser irradiation facility used in the structure manufacturing method of the present invention;

FIG. 13 is a diagram showing an example of a cross-sectional shape of a structure;

Fig. 14 is a diagram showing an example of the cross-sectional shape of the structure of the present invention;

Fig. 15 is a diagram showing an example of the cross-sectional shape of the structure of the present invention;

FIG. 16 is a diagram showing an example of a laser modulation method;

17 is a SEM (scanning electron microscope) image (stereo view) of the structure of Example 3;

Fig. 18 is the SEM image (stereo view) of the structure of embodiment 4;

Fig. 19 is an explanatory view showing an example of the optical recording medium of the present invention;

20A is an explanatory diagram showing the relationship between the laser beam incident direction and the cross-sectional shape of the medium in an example of the optical recording medium reproducing method of the present invention;

20B is an explanatory diagram showing the relationship between the laser intensity distribution of the incident laser light and the temperature distribution on the surface of the optical recording medium in an example of the optical recording medium reproducing method of the present invention;

Fig. 21 is an explanatory view showing an example of another optical recording medium of the present invention;

Fig. 22 is an explanatory view showing an example of a method for reproducing an optical recording medium according to the present invention;

Fig. 23 is an explanatory view showing an example of the optical recording medium of the present invention;

Fig. 24A is an explanatory view (plan view) showing the arrangement of structures in an example of the optical recording medium reproducing method of the present invention;

Fig. 24B is an explanatory diagram showing changes in the reproduction signal level in an example of the method for reproducing the optical recording medium of the present invention;

Fig. 25 is an explanatory view showing an example of the optical recording medium of the present invention;

Fig. 26A is an explanatory view (plan view) showing the arrangement of structures in an example of the optical recording medium reproducing method of the present invention;

Fig. 26B is an explanatory diagram showing changes in the reproduction signal level in an example of the optical recording medium reproduction method of the present invention;

Fig. 27 is an explanatory diagram showing an example of the optical recording medium of the present invention;

Fig. 28A is an explanatory view (plan view) showing the arrangement of structures in an example of the optical recording medium reproducing method of the present invention;

Fig. 28B is a longitudinal sectional view of the radial direction of the optical recording medium in an example of the optical recording medium reproducing method of the present invention;

Fig. 29 is a plan view showing an example of a conventional structure;

Fig. 30 is a plan view showing an example of the structure of the present invention.

Detailed ways

The method of manufacturing the structure of the present invention includes a photoirradiation step, an etching step, and other steps as necessary.

The structure-forming medium of the present invention is used in the structure production method of the present invention, and has a laminated structure in which at least a light-absorbing layer and a heat-reactive layer are laminated, and if necessary, has other layers.

The structure of the present invention is produced by the structure production method of the present invention.

Details of the medium for forming a structure of the present invention and the structure of the present invention will also be clarified through the description of the structure manufacturing method of the present invention below.

The structure-forming medium has a laminated structure in which at least a light-absorbing layer and a heat-reactive layer are laminated. The light absorbing layer has a function of absorbing irradiated light and generating heat. The heat reaction layer has a function of performing heat reaction by heat generation of the light absorbing layer.

By irradiating the structure-forming medium with light, the light-absorbing layer generates heat and the heat-reactive layer undergoes thermal reaction. Both the light-absorbing layer and the heat-reactive layer may be thermally reacted by light irradiation. The way of thermal reaction is the change of material density, the change of crystal state, the change of composition, the change of surface roughness and so on. Even if it changes in various ways by a thermal reaction, it is sufficient. For example, a high density of the material and a change in the composition of the material may occur simultaneously by a thermal reaction.

The layer structure of the structure-forming medium is not particularly limited as long as it is a laminated structure including a light-absorbing layer and a heat-reactive layer, and can be appropriately selected according to the purpose. For example, it can be set to form a structure with the following layer structure: Use the media.

As the medium structure 1, there can be mentioned a structure-forming medium having a substrate 103, a light-absorbing layer 102, and a heat-reactive layer 101 laminated in this order as shown in FIG. 1 .

As the medium structure 2, there can be mentioned a structure-forming medium having a substrate 103, a thermally reactive layer 101, a light absorbing layer 102, and a thermally reactive layer 101 laminated in this order as shown in FIG. 2 .

As the medium structure 3, there can be mentioned a structure-forming medium having a substrate 103, a thermally reactive layer 101, and a light-absorbing layer 102 laminated in this order as shown in FIG. 3 .

-Thermo-reactive layer-

The material of the thermally reactive layer 101 is not particularly limited as long as it is changed by the heat generation of the light absorbing layer 102, and can be appropriately selected according to the purpose. Examples of materials include silicon compound materials, sulfide materials, selenide materials, fluorine compound materials, and the like.

Examples of the silicon compound material include SiO ₂ , SiON, Si ₃ N ₄ and the like. In these materials, the light-irradiated portion is densified by changing the density of the material as the light-absorbing layer heats up as it is irradiated with light. In the etching process, the etching rate of the light-irradiated portion decreases with densification of the material. As a result, the light-irradiated portion can remain as a structure.

Examples of the sulfide material include ZnS, CaS, BaS and the like. In these materials, the light-irradiated portion is densified by changing the density of the material as the light-absorbing layer heats up as it is irradiated with light. And the sulfur is dissociated in the part irradiated with light, and the composition of the material changes. In the etching process, the etching rate of the laser irradiated portion decreases due to the densification of the material and the change in the composition of the material. As a result, the light-irradiated portion can remain as a structure.

As said selenide material, ZnSe, BaSe etc. are mentioned, for example. In these materials, the light-irradiated portion is densified by changing the density of the material as the light-absorbing layer heats up as it is irradiated with light. In addition, selenium is dissociated in the part irradiated by light, and the composition of the material changes. In the etching process, the etching rate of the light-irradiated portion decreases due to the densification of the material and the change in the composition of the material. As a result, the light-irradiated portion can remain as a structure.

As said fluorine compound material, _CaF2 , _BaF2 etc. are mentioned, for example. In these materials, the light-irradiated portion is densified by changing the density of the material as the light-absorbing layer heats up as it is irradiated with light. In addition, fluorine is dissociated in the part irradiated with light to change the composition of the material. In the etching process, the etching rate of the light-irradiated portion decreases due to the densification of the material and the change in the composition of the material. As a result, the light-irradiated portion can remain as a structure.

The heat reactive layer contains a mixture of material A and material B, the material A is a silicon compound material, and the material B is preferably at least one material selected from sulfide materials, selenide materials, and fluorine compound materials.

Examples of the silicon compound material of the material A include SiO ₂ , SiON, Si ₃ N ₄ and the like.

As the said sulfide material of the said material B, ZnS, CaS, BaS etc. are mentioned, for example.

As said selenide material, ZnSe, BaSe etc. are mentioned, for example.

As said fluorine compound material, _CaF2 , _BaF2 etc. are mentioned, for example.

Both of these material A and material B may use a single material, and may use multiple materials.

The mixing ratio of the material A and the material B is preferably such that the material A is in the range of 10-30 mol%, and the material B is in the range of 90-70 mol%.

In the film-forming stage, it is preferable that the material A and the material B are not in a chemically bonded state but exist independently of each other.

In the manufacturing method of the structure of the present invention, the film thickness of the thermally reactive layer corresponds to the height of the structure. Therefore, the film thickness of the thermally reactive layer is set according to the height of the formed structure.

The film-forming method as the material of the thermal reaction layer is not particularly limited, and can be appropriately selected according to the purpose, but sputtering method is preferable. Also in the cathode sputtering method, the RF sputtering method is particularly preferable because it forms a film at room temperature.

The sputtering intermediate electrode used in the sputtering method is preferably an intermediate electrode produced by a firing method. In the state of sputtering the intermediate electrode, it is preferable that the material A and the material B are not chemically bonded but each exists independently. By performing film formation by such a sputtering method, a low-density thin film can be formed at the film formation stage. By using a low-density thin film, the difference in etching ratio between the light-irradiated portion and the non-irradiated portion can be increased, and a structure can be uniformly formed on a large-area substrate.

A mixture of material A and material B using the silicon compound material as material A can form a low-density thin film, and the light-irradiated portion is densified by heat generation from the light-absorbing layer irradiated with light. This can increase the density difference between the light-irradiated portion and the non-irradiated portion, so that the etching selectivity can be increased in the etching process. And dissociation of the structural elements of the material B occurs in the light-irradiated portion. Sulfur dissociates in the case of sulfide materials. Selenium dissociates in the case of a selenide material. In the case of a fluorine compound material, fluorine dissociates. The composition of material B changes by dissociation of elements. The etching selectivity can also be increased by changing the material composition. As a result, the etching selectivity can be increased by both the densification of the material and the change of the material composition, and a microstructure can be uniformly formed on a large-area medium. And since a low-density thin film can be formed in the film-forming stage, a thick film can be formed with low residual stress. Since the thermally reactive layer that becomes the structure can be formed into a thick film, it is possible to form a structure having a higher depth ratio (height of the structure/size of the structure).

-Light absorbing layer-

The material of the light absorbing layer 102 is not particularly limited as long as it is a material that absorbs light and has a heat generating function, and can be appropriately selected according to the purpose, for example, semiconductor materials such as Si, Ge, GaAs can be used; Intermetallic compound materials of low melting point metals such as Sn; materials of Sb, Te, BiTe, BiTn, GaSb, GaP, InP, InSb, InTe, SnSn, etc.; carbide materials of C, SiC, etc.; V ₂ O ₅ , Cr ₂ Oxide materials such as O ₃ , Mn ₃ O ₄ , Fe ₂ O ₃ , Co ₃ O ₄ , CUO, etc.; Nitride materials such as AlN, GaN, etc.; Binary system phase change materials such as SbTe; GeSbTe, InSbTe, BiSbTn, 3-element system phase change materials such as GaSbTn; 4-element system phase change materials such as AgInSbTe.

Among them, a material containing at least one element selected from Sb, Te, and In is particularly desirable.

The film thickness of the light-absorbing layer is not particularly limited, and can be appropriately selected according to the purpose, and is preferably in the range of 2 to 50 nm. If the film thickness is less than 2 nm, it will be difficult to form a thin film and the light absorption efficiency will decrease. If it exceeds 50 nm, thermal diffusion will occur in the light absorbing layer, making it difficult to heat minute regions.

As the substrate 103, glass, quartz, or the like can be used. Also, substrates used in semiconductor manufacturing such as Si and SOI (Silicon on Insulator), aluminum (Al), opaque glass substrates, substrates for HDD (hard disk drives), polycarbonate resins, acrylic resins, and polyene resins can be used. , epoxy resin, vinyl ester resin, polyethylene terephthalate (PET), UV curable resin and other resin substrates.

The manufacturing method of the structure includes a light irradiation step of irradiating the structure forming medium with light, and an etching step of etching the medium. Alternatively, heat treatment may be performed on the formed structure. The medium may be further etched using the formed structure as a mask. It is also possible to copy the unevenness on other media using the formed structure as a model.

4 to 8 show an example of a structure manufacturing method using the structure forming medium shown in FIG. 2 . FIG. 4 shows the light irradiation process, FIG. 5 shows the etching process, FIG. 6 shows the heat treatment process, FIG. 7 shows the second etching process, and FIG. 8 shows the transfer process. The contents of each process are as follows.

In the light irradiation step of FIG. 4 , the upper diagram of FIG. 4 shows a structure forming medium, 101 denotes a heat reactive layer, 102 denotes a light absorbing layer, and 103 denotes a substrate. The middle diagram of FIG. 4 shows the state of light irradiation, and 201 shows the direction of light irradiation. Light is irradiated from the substrate 103 side. The lower diagram of FIG. 4 shows the state after irradiation, and 202 shows a changed part accompanying laser irradiation. The change portion is formed in the thermal reaction layer 101 arranged above and below the light absorbing layer 102 .

The light irradiation step is to irradiate light to a predetermined position of the structure forming medium in order to form the structure. At this time, the light source can be moved, the light source can be fixed and the medium can be moved, or both the light source and the medium can be moved. As a light source, an F ₂ laser with a wavelength of about 157 nm, an ArF laser with a wavelength of about 193 nm, a KrF laser with a wavelength of about 248 nm, or the like can be used. Irradiation with light may also be performed in the atmosphere. It is also possible to place the medium in an airtight container, introduce gas such as nitrogen, oxygen, water vapor, argon, hydrogen, etc., and irradiate the medium with light in a gas environment. In addition, the medium may be placed in a vacuum container and the medium may be irradiated with light in a vacuum.

In the step of irradiating laser light, it is preferable to use a semiconductor laser as a laser light source. The wavelength of the semiconductor laser is preferably 370 to 780 nm, more preferably 390 to 410 nm. Specifically, a GaN-based semiconductor laser is used. By using such a semiconductor laser, a low-cost laser irradiation device can be produced, and the processing cost can be reduced. Semiconductor lasers can modulate the energy level of laser light at high speed. Therefore, structures can be formed at high speed for large-area media. In addition, by using a short-wavelength laser, it is possible to form a minute laser spot and form a minute structure.

When the structure-forming medium is irradiated with laser light, the energy level of the laser light is raised at the position where the structure is formed. That is, the energy level of the laser is periodically modulated between the high energy level and the low energy level corresponding to the structure. When the ratio of the time (pulse amplitude) and period for maintaining the laser power at a high energy level is set as the pulse load rate (pulse amplitude/period), it is best to set the pulse load rate at 10 to 30%. . If the pulse load factor is less than 10%, the ends of the structure will be in a sagging state. This is the cause of insufficient heat generation of the light absorbing layer. If the pulse load factor is greater than 30%, the adjacent structures will be connected. This is to diffuse the heat generated in the light absorbing layer.

When irradiating the structure forming medium with laser light, it is preferable to rotate the medium. The structure-forming medium may be rotated, and the medium may be irradiated with laser light while subjecting the medium to focus servo. It is also possible to rotate the structure forming medium and irradiate the laser light while subjecting the medium to focus servo and tracking servo. As the laser light source, an F ₂ laser with a wavelength of about 157 nm, an ArF laser with a wavelength of about 193 nm, a KrF laser with a wavelength of about 248 nm, etc. can be used. A semiconductor laser is preferably used as the laser light source. The wavelength of the semiconductor laser is preferably 370 to 780 nm, more preferably 390 to 410 nm. Specifically, a GaN-based semiconductor laser is used. By irradiating laser light while rotating the medium at high speed, structures can be formed on a large-area medium at high speed.

FIG. 11 shows an example of the structure of laser irradiation equipment. The laser irradiation device 51 includes a semiconductor laser 511 and an objective lens 512. 513 denotes laser light. The wavelength of the semiconductor laser 511 is 370 to 780 nm. The ideal wavelength is 390-410nm. For example, a GaN-based semiconductor laser is used. The numerical aperture (NA) of the objective lens 512 is set to be 0.5-1.0. The ideal numerical aperture is 0.8 to 0.95. The laser modulation device 52 includes a pulse generation circuit 521 , a laser drive circuit 522 , and a reference signal generation circuit 523 . The pulse generation circuit 521 generates a modulation signal 524 of the laser energy level. And a modulated timing signal 525 is generated. The laser drive circuit 522 generates a laser drive signal 55 based on a modulation signal 524 from the pulse generation circuit. The reference signal generating circuit 523 generates a reference signal 56 for moving the medium drive device based on the modulation timing signal 525 from the pulse generating circuit. 53 is a medium for structure formation, and 54 is a medium drive device. The medium 53 for structure formation is set on the medium drive device 54 .

The structure-forming medium is moved in accordance with the timing of the light emission of the laser light by the above-mentioned laser irradiation device based on the reference signal 56, and a structure is formed on a predetermined portion of the medium.

Fig. 12 shows the structure of other laser irradiation equipment. The equipment includes: a laser irradiation device 61, a laser modulation device 62, a medium rotation device 64, and a signal detection device 65. 63 is a medium for structure formation. 66 represents a laser.

The laser irradiation device 61 includes a laser light source, an objective lens for condensing laser light, and a driver for driving the laser irradiation device. As the laser light source, an F ₂ laser with a wavelength of about 157 nm, an ArF laser with a wavelength of about 193 nm, a KrF laser with a wavelength of about 248 nm, etc. can be used. And the semiconductor laser can also be used. A semiconductor laser is preferably used as the laser light source. The wavelength of the semiconductor laser is preferably 370 to 780 nm, more preferably 390 to 410 nm. Specifically, a GaN-based semiconductor laser is used. The numerical aperture of the objective lens is set to be 0.5 to 1.0. The ideal numerical aperture is 0.8 to 0.95.

The laser modulation device 62 includes a pulse generation circuit 621 , a laser drive circuit 622 , and a reference signal generation circuit 623 . The pulse generation circuit 621 generates a modulation signal 624 of the laser energy level. And a modulated timing signal 625 is generated.

The laser driving circuit 622 generates a laser driving signal 67 based on the modulation signal 624 from the pulse generating circuit. The reference signal generation circuit 623 generates a pulse reference signal 626 based on the modulated timing signal 625 from the pulse generation circuit.

The medium rotating device 64 includes: a spin table 641 for rotating the medium and a reference signal generating circuit 642 . The reference signal generation circuit 642 generates a rotation reference signal 643 according to the signal from the spin table. The spin table is rotated by rotating the rotation reference signal 643 and the pulse reference signal 626 at a synchronous frequency.

The signal detection device 65 includes: a light detector 651 and a servo circuit 652 . A photodetector 651 receives a signal 68 from the medium and generates a focus and tracking error signal 653 . The servo circuit 652 generates the laser irradiation device drive signal 69 based on the error signal.

With the above laser irradiation device, the focus and tracking errors are controlled while the medium is rotated to form a structure on a predetermined portion of the medium.

In the etching process of FIG. 5 , the upper diagram of FIG. 5 shows the shape of the medium before etching, and 202 indicates a portion changed with laser irradiation. The middle diagram of FIG. 5 shows the etching state, and 203 denotes an etching device. The lower diagram of FIG. 5 shows the state after etching, and 204 denotes a structure.

In the etching process, a part of the medium is removed to form a structure. The change portion 202 is formed by thermal reaction of light irradiation as described above. Since the etching rate of the changed portion decreases, a difference in etching rate occurs between the changed portion and the non-changed portion, and the changed portion remains as a structure after etching. In the etching step, at least the heat reactive layer 101 is etched, but both the heat reactive layer 101 and the light absorbing layer 102 may be etched. In addition, etching may be performed on other laminated layers.

A dry etching method can be used as the etching method. As the dry etching method, methods such as RIE (Reactive Ion Etching), ICP (Inductively Coupled Plasma) and sputter etching can be used, for example. The medium is set in a vacuum device and placed in an etching gas environment for a certain period of time to form a structure.

A wet etching method may also be used in the etching step.

FIG. 10 is an explanatory view showing an example of an etching process. The upper figure of FIG. 10 shows the shape of the medium before etching, 101 denotes the thermal reaction layer, 102 denotes the light absorbing layer, and 103 denotes the substrate. 401 represents a portion that changes with laser irradiation. The middle diagram of FIG. 10 shows the etching state, 402 denotes an etching device (etching tank), and 403 denotes an etching solution. The lower diagram of FIG. 10 shows the state after etching, and 404 denotes a structure.

As the wet etching method, a method of immersing in an aqueous acid solution, an aqueous alkali solution, an organic solvent, or the like can be used. A structure can be formed by immersing the medium in the etching solution 403 for a certain period of time to dissolve the portion other than the portion changed by laser irradiation. According to this method, a structure can be formed at low cost without using a vacuum device.

In the manufacturing method of the structure, a mixture of material A and material B using a silicon compound material as material A is used in the heat reactive layer. In the case of this production method, a wet etching method using an aqueous solution containing hydrogen fluoride acid is used in the etching step. The etching solution indicated by 403 in FIG. 10 is an aqueous solution containing hydrogen fluoride acid. An aqueous solution containing hydrofluoric acid selectively dissolves the silicon compound material. Material A, that is, the silicon compound material is dissolved in the light non-irradiated portion. In the mixture of material A and material B, material A is dissolved and material B falls off (lifts off). In the light-irradiated changing portion 401, since material A and material B are densified and the composition of material B is changed, the etching resistance to an aqueous solution containing hydrogen fluoride is improved. Therefore, the changed portion irradiated with light can remain to form a structure. The light-absorbing layer 102 has very high etching resistance to an aqueous solution containing hydrogen fluoride. Therefore, the light absorbing layer functions as an etching stopper layer in the etching process. By having an etch stop layer, a structure can be formed with good uniformity even for a medium having a large area.

As the hydrofluoric acid aqueous solution, it is preferable to use a mixed solution of 50% mass dilute solution and water sold on the market. The mixing ratio <hydrofluoric acid (50% diluted): water> is preferably in the range of 1:4 to 1:50. When the hydrogen fluoride concentration is higher than 1:4, the surface roughness of the light absorbing layer and the heat reactive layer increases. When the hydrogen fluoride acid concentration is dilute than 1:50, the etching time becomes longer and the processing cost becomes higher.

The heat treatment step in FIG. 6 is to heat-treat the formed structure in a gas environment to remove defects in the structure and the medium. And the structural elements are interdiffused between the laminated layers and the structure. Improves the adhesion between the structure and other layers by interdiffusion. The upper diagram of FIG. 6 shows the state of the medium before heat treatment, and 204 denotes a structure. The middle diagram of FIG. 6 shows a heat treatment state, and 205 shows a heat treatment device. The lower diagram of FIG. 6 shows the state after the heat treatment, and 206 shows the state where the structure has been changed by the heat treatment. Heat treatment can also be performed in the atmosphere. It is also possible to place the medium in a closed container and introduce gas such as nitrogen, oxygen, water vapor, argon, hydrogen, etc. into it, and process it in a gaseous environment. Furthermore, it is also possible to place the medium in a vacuum container and process it in a vacuum. High-frequency induction heating can also be performed for heat treatment, and lamp heating can also be performed using a halogen lamp or a xenon lamp as a light source.

In the second etching step of FIG. 7, the medium is further etched using the formed structure as a mask. The upper diagram of FIG. 7 shows the state of the medium before etching, and 204 denotes a structure. The middle diagram of FIG. 7 shows an etching state, and 207 shows an etching device. The lower diagram of FIG. 7 shows the state after etching, and 208 denotes a structure.

A dry etching method can be used as the etching method. As the dry etching method, methods such as RIE (Reactive Ion Etching), ICP (Inductively Coupled Plasma) and sputter etching can be used, for example.

The medium is set in a vacuum device and placed in an etching gas environment for a certain period of time to form a structure. Only the layer 102 directly under the structure 204 may be etched, or the substrate 103 may be etched.

As the etching method, the above-mentioned wet etching method can also be used.

In the copying step of FIG. 8, the unevenness is copied to another medium using the formed structure as a model. The upper diagram of Fig. 8 shows the medium forming the structure to be a model. The middle diagram of FIG. 8 shows the copying state, and 209 shows the medium for copying the unevenness of the structure. The lower diagram of Fig. 8 shows the state after copying. As the transfer method, a compression molding method, an injection molding method, a 2P transfer method (photohardening method and thermosetting method) or the like can be used. Resin materials such as polycarbonate resin, acrylic resin, polyolefin resin, epoxy resin, vinyl ester resin, and ultraviolet curable resin can be used as a medium material for replicating the unevenness of the structure.

The combination of steps shown in FIGS. 4 to 8 can be changed according to the structure and material of the medium for forming a structure shown in FIGS. 1 to 3 . For example, the structure can be formed by combining the following steps.

Formation method 1: Light irradiation process → etching process

Formation method 2: Light irradiation process → etching process → heat treatment process

Formation method 3: Light irradiation process → etching process → heat treatment process → second etching process

Formation method 4: Light irradiation process → etching process → heat treatment process → second etching process → replication process

Formation method 5: Light irradiation process → etching process → replication process

Formation method 6: Light irradiation process → etching process → heat treatment process → replication process

Formation method 7: Light irradiation process → etching process → second etching process → replication process

In the manufacturing method of the structure of the present invention, it is preferable to place the heat-reactive layer on the uppermost layer of the laminated structure and to use a structure-forming medium made of a material having light-transmitting properties at the wavelength of the irradiated light. In the light irradiation step, laser light is irradiated from the uppermost thermal reaction layer side.

FIG. 9 shows an example of a structure manufacturing method. The upper diagram of FIG. 9 shows a structure forming medium, 101 denotes a thermal reaction layer, 102 denotes a light absorbing layer, and 103 denotes a substrate. The thermally reactive layer is the uppermost layer of the laminated structure. It is also possible for the thermally reactive layer to be located on other layers. The middle diagram of FIG. 9 shows the state of light irradiation, and 301 shows the direction of light irradiation. Light is irradiated from the uppermost thermal reaction layer side. That is, it does not irradiate through the substrate. In the following description, it will be referred to as "film surface injection". The aberration caused by the substrate can be suppressed by incident from the film surface. And the NA of the objective lens can be increased to condense the light beam. The change portion 302 is formed on a finer region of the thermal reaction layer by concentrated light energy. The lower diagram of FIG. 9 shows the state after irradiation, and 302 shows the changed part accompanying laser irradiation. The changing portion 302 is formed in the thermal reaction layer 101 disposed above and below the light absorbing layer 102 .

As the thermal reaction layer 101, a material with high light transmittance to the wavelength of the irradiated light is used. Specifically, a material whose light absorption rate with respect to the wavelength of the irradiated light is in the range of 1×10 ^-3 to 1×10 ^-5 is used. Light absorption in the thermally reactive layer can be suppressed by using a material with high light translucency. Since the changed portion 302 can be formed only by heat generation of the light absorbing layer, the changed portion to be a structure can be miniaturized.

The thermal reaction layer can use SiO ₂ , SiON, Si ₃ N ⁴ and other _silicon compound ^materials , ZnS, CaS, BaS and other sulfide materials, ZnS , CaS, BaS and other selenide materials, CaF ₂ , BaF ₂ and other fluorine compound materials. In the manufacturing method, the film thickness of the heat-reactive layer is made to correspond to the height of the structure. That is, the film thickness of the thermally reactive layer is set according to the height of the structure to be formed.

The materials used for other layers and the process of forming the structure are the same as those described above.

(construct)

The structure of the present invention is produced by the structure production method of the present invention.

29 and 30 are plan views showing the shape of the structure.

Fig. 29 shows an example of forming a structure using a phase change material by the methods disclosed in JP-A-9-115190 and JP-A-10-97738.

The structure of the medium for forming the structure is a structure in which a phase change material GeSbTe is laminated on a polycarbonate resin substrate. Irradiate with laser light, and then etch to process the phase change material into a convex shape to form a structure. Etching is performed using an alkaline solution KOH. The etching time was 30 minutes.

2401 in FIG. 29 denotes a structure, that is, a convex phase change material GeSbTe. 2402 indicates the moving direction of the laser beam. 2403 represents the front end of the structure. 2404 represents the back end of the construct. In the case of a phase change material, there can be a difference in etching ratio due to the difference between the crystal phase state and the amorphous state, and a structure can be formed by etching. Generally, the portion remaining as the structure 2401 is in an amorphous state. The other portion 2405 (the portion other than hatched 2401 in FIG. 29 ) is in a crystalline state. The rear end portion 2404 is crystallized in the process of changing the phase change material to an amorphous state by laser irradiation. Therefore, the shape of the structure becomes a crescent shape in which the rear end 2404 is blocked as shown in 2401 of FIG. 29 . In the method of manufacturing a structure using a phase change material, even if the composition of the material is changed, the shape remains the same. Due to the complex shape, the application range is limited. When applied to an optical recording medium described later, the state of intersymbol interference (mutual interference of signals from adjacent marks) is complex, requiring complex and expensive signal processing techniques.

Fig. 30 shows the shape of a structure produced by the method for producing a structure of the present invention. The structure of the medium for structure formation is a structure in which a light absorbing layer AgInSbTe and a heat reactive layer ZnS-SiO ₂ are laminated on a polycarbonate resin substrate. Irradiate with laser light, and then etch to process ZnS-SiO ₂ into a convex shape to form a structure. Etching is performed using a mixed solution of hydrogen fluoride acid and water as an acid solution. The etching time was 20 seconds.

2501 in Fig. 30 denotes a structure, that is, a convex ZnS-SiO ₂ . 2502 is the moving direction of the laser. 2503 is a part other than the structure, which is the surface of the light absorbing layer AgInSbTe. The method of the present invention can form a structure close to a true circle shape. Since it is a simple circle, the application range of the structure is expanded.

When applied to an optical recording medium described later, the state of intersymbol interference (mutual interference of signals from adjacent marks) is simple, and complex signal processing techniques are not required. In addition, the diameter of the structure can be changed according to the recording information, and it can also be applied to a multi-variable recording method.

13 to 15 are schematic sectional views of the structure. Fig. 13 shows a general cross-sectional shape of a structure, and Figs. 14 and 15 show the shape of the structure of the present invention.

The cross-sectional shape of the structure shown in FIG. 13 is shown in JP-A-2001-250279, JP-A-2001-250280, JP-A-2003-145941, and JP-A-2002-365806, which are described as prior art. The cross-sectional shape of a structure produced by the disclosed method of thermally changing a light-absorbing material.

701 in FIG. 13 is a structure. The material is a cyanine pigment which is a recording material of a write-once optical disk. 702 is a light absorbing layer. The material is a phase change material GeSbTe. FIG. 13 shows only the structure and the light-absorbing layer, but there may also be a heat-reactive layer and a substrate that do not form a structure. The wavelength of laser light used to form the structure is 405 nm, and cyanine pigments absorb light of this wavelength. When the heat-reactive material that becomes the structure absorbs light, as shown in FIG. 13 , the cross-sectional shape tends to be a sagging shape.

Fig. 14 and Fig. 15 are the structure shapes of the present invention. There is a case where the end surface of the cross-section of the structure is substantially vertical or substantially inversely tapered. FIG. 14 shows a case where the end surface is substantially in the shape of an inverted taper. 811 is a construct. The material is ZnS-SiO ₂ . 812 denotes a light absorbing layer. The material is a phase change material GeSbTe.

813 in FIG. 14 represents the inclination angle of the cross section of the structure. The wavelength of the laser light used to form the structure is 405 nm, and ZnS-SiO ₂ does not absorb light of this wavelength. A material that does not absorb light is used as the thermally reactive material that becomes the structure, and the cross-sectional shape can be formed as shown in Fig. roughly inverted cone shape as shown.

FIG. 15 shows a case where the end surface is substantially vertical. 801 is a structure. 802 denotes a light absorbing layer. The materials of the structure and the light-absorbing layer are the same as those in FIG. 14 .

903 in FIG. 15 represents the inclination angle of the section. By adjusting the etching conditions, it is possible to form a structure whose end faces are substantially vertical.

14 and 15 describe only the structure and the light-absorbing layer, but there may also be a heat-reactive layer and a substrate that do not form a structure. Since the shape of the ends of the structures is substantially vertical or substantially inverted, it is possible to avoid the problem of connection between adjacent structures when increasing the structure arrangement density.

The structure produced by the production method of the structure of the present invention can be applied in various fields such as optical recording media, biochips, optical crystals, and component separation materials for various electronic devices described below.

(Optical recording medium and reproduction method of optical recording medium)

A first aspect of the optical recording medium of the present invention has a substrate, a light-absorbing layer that absorbs reproducing light on the substrate to generate heat, and a convex structure next to the light-absorbing layer that includes a material different from that of the light-absorbing layer.

The first aspect of the reproducing method of the present invention uses an optical recording medium having a substrate, a light-absorbing layer that absorbs reproducing light on the substrate to generate heat, and a convex structure next to the light-absorbing layer that contains a material different from that of the light-absorbing layer. , and irradiate light from the side of the convex structure to the light absorbing layer and the convex structure and detect changes in reflected light flux.

The second aspect of the optical recording medium of the present invention has: a substrate, a light-absorbing layer that absorbs and reproduces light on the substrate to generate heat, a convex structure next to the light-absorbing layer that contains a material different from that of the light-absorbing layer, and A light-transmitting layer having translucency to reproduced light on the convex structure, the light-transmitting layer covering the surface of the convex structure and forming a substantially hemispherical shape.

The second aspect of the reproducing method of the present invention uses a substrate, a light-absorbing layer that absorbs reproducing light on the substrate to generate heat, a convex structure next to the light-absorbing layer that contains a material different from that of the light-absorbing layer, and On the convex structure, there is a light-transmitting layer that is transparent to reproduced light. The light-transmitting layer covers the surface of the convex structure to form a roughly hemispherical optical recording medium. The laminate composed of the light absorbing layer, the convex structure and the light transmitting layer is irradiated with light and the change of reflected light flux is detected.

The optical recording medium of the present invention is a recording medium for recording and reproducing information by using light. The optical recording medium of the present invention has the following five modes, and there are five reproduction methods corresponding to each of them. The optical recording media of the first to fifth modes and the reproducing methods of the first to fifth modes will be described in order below.

<The Optical Recording Medium of the First Mode and Its Reproducing Method>

The optical recording medium according to the first aspect of the present invention is aimed at achieving higher recording density through super-resolution reproduction.

The optical recording medium includes a substrate, a thin-film light-absorbing layer that absorbs reproduction light on the substrate to generate heat, a convex structure next to the light-absorbing layer, and other layers as necessary.

Fig. 19 shows an example of the structure of the optical recording medium of the first embodiment. In this optical recording medium, a thin-film buffer layer 1302 for protecting the substrate is laminated on a substrate 1301, and a thin-film light-absorbing layer 1303 and a convex structure 1304 next to the light-absorbing layer are laminated thereon. As shown in FIG. 19, each convex structure 1304 is separated in the medium plane.

The material of the substrate 1301 is not particularly limited and can be appropriately selected according to the purpose. For example, glass, ceramics, resin, etc. can be used, and a resin substrate is suitable from the viewpoint of formability and cost. Examples of such resins include polycarbonate resins, acrylic resins, epoxy resins, polystyrene resins, acrylonitrile-styrene copolymers, polyethylene resins, polypropylene resins, silicone resins, fluororesins, ABS resins, Urethane resin, etc. Among them, polycarbonate resins are particularly desirable from the viewpoints of moldability, optical characteristics, and cost.

A pre-groove and a pre-pit for tracking laser light may be provided on the surface of the substrate 1301 .

As the buffer layer 1302, for example, SiO ₂ or a mixture of SiO ₂ and compounds such as ZnS, ZnO, Si ₃ N ₄ , Al ₂ O ₂ , and AlN is preferably used.

The film thickness of the buffer layer is not particularly limited and can be appropriately selected according to the purpose, for example, it is preferably 20 to 100 nm. The buffer layer is provided to suppress thermal diffusion from the light absorbing layer to the substrate. If the thickness of the film is less than 20 nm, the effect of suppressing thermal diffusion may be reduced, and if it exceeds 100 nm, the residual stress of the film may increase, and problems such as media warpage may occur.

The light absorbing layer 1303 preferably contains at least one element selected from Sb, Te, and In. Specifically, binary system materials such as SbTe and InTe, ternary system materials such as GeSbTe and InSbTe, and quaternary system materials such as AgInSbTe are used. In addition, semiconductor materials such as Si and Ge can be used.

The materials constituting these light-absorbing layers 1303 generate heat when irradiated with laser light, and their optical properties such as refractive index and absorption coefficient change. By laminating these materials with the convex structure, the optical characteristics of the region corresponding to the convex structure can be changed by laser irradiation.

Since the material is in an amorphous or polycrystalline state, the residual stress in the thin film is low, so that defects such as cracks can be suppressed despite rapid temperature changes in the optical recording medium manufacturing method of the present invention described later. Utilizing this effect, a fine convex structure can be formed over a large area.

The film thickness of the light-absorbing layer is not particularly limited, and can be appropriately selected according to the purpose, for example, it is preferably in the range of 2 to 50 nm. If the film thickness is less than 2 nm, it will be difficult to form a thin film and reduce the light absorption efficiency. If it exceeds 50 nm, thermal diffusion will occur in the light-absorbing layer, making it difficult to change the optical characteristics of the micro-regions of the light-absorbing layer.

The material of the convex structure 1304 is preferably a mixture of material A and material B. The material A is a silicon compound material, and the material B is preferably a sulfide material, a selenide material, or a fluorine compound material. At least one material selected from .

Examples of the silicon compound material of the material A include SiO ₂ , SiON, Si ₃ N ₄ and the like.

As the said sulfide material of the said material B, ZnS, CaS, BaS etc. are mentioned, for example.

As said selenide material, ZnSe, BaSe etc. are mentioned, for example.

As said fluorine compound material, _CaF2 , _BaF2 etc. are mentioned, for example.

Both of these material A and material B may use a single material, and may use multiple materials.

Among these materials, ZnS-SiO ₂ mixture is preferably used. In addition, insulator materials such as SiO ₂ , ZnS, ZnO, Si ₃ N ₄ , Al ₂ O ₂ , and AlN can also be used alone.

The height of the structure is preferably 10 to 100 nm. If the height is less than 10 nm, the signal intensity may decrease. On the other hand, when the signal strength is increased by increasing the structure, if it is higher than 100 nm, the stability of tracking may decrease.

A resist may be provided on the convex structures 1304 . Silicon compounds such as Si ₃ N ₄ , SiO ₂ , and SiC, or transmissive resins can be used as the resist.

The reproducing method of the first aspect of the present invention uses the optical recording medium of the first aspect, irradiates light from the side of the convex structure 1304 to the laminate composed of the film-like light-absorbing layer 1303 and the convex structure 1304, and detects Changes in reflected luminous flux. 20A and 20B show an example of a playback method. As shown in FIG. 20A , in the reproduction method of the first form, laser light is injected from the side of the convex structure 1304 . 1401 in FIG. 20A indicates the incident direction of laser light. The incident laser light is absorbed by the light-absorbing layer 1303 to heat the light-absorbing layer 1303 . Since the light-absorbing layer and the convex structure are made of different materials, the amount of heat generated directly under the convex structure changes. The optical characteristics of the light-absorbing layer change in time with the convex structure along with the change in the amount of heat generated. 1403 denotes a structure at the center of the laser beam, and 1402 denotes a region where the optical characteristics of the light-absorbing layer change. The reproduction signal and the convex structure change in a time-controlled manner corresponding to the change in the optical characteristics.

FIG. 20B shows the laser intensity distribution 1404 of the incident laser light and the temperature distribution 1405 on the surface of the optical recording medium. As shown in FIG. 2OB, the laser intensity distribution 1404 is a Gaussian distribution. 1402 in FIG. 20B represents the optical constant change region of the light absorbing layer.

When the convex structure 1403 is provided on the surface of the medium, the temperature distribution becomes corresponding to the convex structure 1403, and the temperature is particularly high near the convex structure 1403 located near the center of the light beam. As a result, the optical characteristics immediately below the convex structure 1403 located near the center of the light beam vary greatly. By changing the optical constant of a region smaller than the beam diameter corresponding to the convex structure 1403, the reproduced signal and the convex structure 1403 can be changed in time control even at a period equal to or less than the diffraction limit. Higher density can be achieved by such super-resolution reproduction. 1406 is the threshold value of the temperature at which the optical properties of the light absorbing layer change.

<Optical Recording Medium of Second Mode and Reproducing Method Thereof>

The optical recording medium according to the second aspect of the present invention is aimed at achieving high recording density through super-resolution reproduction and laser beam focusing effect on the medium.

The optical recording medium of the second aspect includes: a substrate, a light-absorbing layer that absorbs reproduction light on the substrate to generate heat, a convex structure next to the light-absorbing layer and having a material different from that of the light-absorbing layer, and a A light-transmitting layer having light-transmittance to reproduced light on the convex structure body, the light-transmittance layer covering the surface of the convex structure body and forming a hemispherical shape.

Fig. 21 shows an example of the structure of the optical recording medium of the second embodiment. In this optical recording medium, a film-shaped buffer layer 1502 for protecting the substrate is laminated on a substrate 1501, and a film-shaped light-absorbing layer 1503, a convex structure 1504 adjacent to the light-absorbing layer, and a light-transmitting layer 1505 are laminated thereon. The light-transmitting layer 1505 covers the surface of the convex structure 1504 and its vertical cross-sectional shape is laminated into a substantially hemispherical shape. As shown, each convex structure 1504 is separated in the media plane.

The substrate 301 has the same structure as the substrate 101 of the first mode optical recording medium, the thin film buffer layer 302 has the same structure as the buffer layer 102 of the first mode optical recording medium, and the thin film light absorbing layer 303 It has the same structure as the light absorbing layer 103 of the optical recording medium of the first embodiment.

As the light-transmitting layer 305, oxides, nitrides, or fluorine compounds having high transmittance to reproduced light can be used. As said oxide, _SiO2 , _{Al2O3 , BiAlO3} , BiGeO, _La2O3 , _{LaAO3 etc.} are mentioned, for example. Examples of the nitride include Si ₃ N ₄ , AlN, and the like. As said fluorine compound, _CaF2 , _BaF2 etc. are mentioned, for example.

The film thickness of the transparent layer should be set according to the height of the structure, at least greater than or equal to the height of the structure. If it is less than the height of the structure, it cannot be hemispherical to imitate the structure. If it is too thick, the manufacturing time will be long and the cost will be increased.

In the reproducing method of the second aspect of the present invention, the optical recording medium of the second aspect is used to irradiate the laminate composed of the film-like light absorbing layer 1503, the convex structure 1504, and the light-transmitting layer 1505 from the side of the light-transmitting layer 1505. light, and detect changes in reflected luminous flux. Fig. 22 shows an example of the reproduction method in the second mode. As shown in FIG. 22 , the reproduction method of the second mode is to inject laser light from the side of the convex structure 1504 . 1601 in FIG. 22 indicates the incident direction of laser light.

In the reproducing method according to the second aspect of the present invention, the incident laser light is absorbed by the light-absorbing layer 1503 to cause the light-absorbing layer 1503 to generate heat. Since the light-transmitting layer 1505 of the optical recording medium of the second mode is laminated into a semicircular longitudinal cross-sectional shape following the convex structure 1504, a part of the laser light is further concentrated by the surface of the medium as shown in the figure. The condensed laser light is absorbed by the light-absorbing layer 1503 and heats up the light-absorbing layer in particular near the convex structure 1603 positioned at the center of the beam. Optical properties such as refractive index and absorption coefficient change due to heat generation. 1602 represents a region where the optical properties of the light absorbing layer change.

Since the light-transmitting layer 1505 whose vertical cross-sectional shape is a semicircular shape is provided in the optical recording medium of the second mode, the light-collecting effect is increased. In the same way as the optical recording medium reproduction method of the second mode, by making the ratio and the convex structure The super-resolution reproduction effect produced by the change of the optical constant in the area of small beam diameter corresponding to the body 1504 increases the signal intensity from the period less than or equal to the diffraction limit, that is, the convex structure body 1504 . As a result, high recording density can be achieved by the laser beam focusing effect and super-resolution effect on the optical recording medium.

<Third Optical Recording Medium and Its Reproducing Method>

The optical recording medium of the third aspect of the present invention aims at increasing the recording density by adding multi-variable recording to the optical recording medium of the first and second aspects.

The optical recording medium of the third aspect has the structure of the optical recording medium of the first aspect and the second aspect, and the convex structure is substantially columnar, and the diameter of the convex structure changes according to the recording information. A cylindrical shape is particularly preferable as the shape of the convex structure. In order to improve the signal quality, it is suitable that the angle of the end of the convex structure is close to a vertical state, that is, a state close to a cylindrical shape. If the angle at the end of the structure is gentle, the adjacent structures will be connected, and the signal quality will be low.

Fig. 23 shows an example of a plan view of the structure of the optical recording medium of the third embodiment. In Fig. 23, 1701 is a light absorbing layer, 1702 is a convex structure, 1703 is a period of a convex structure in the tracking direction, 1704 is a recording track, and 1705 is a diameter of a convex structure.

The optical recording medium of the third mode has a laminated structure and the materials of each layer are the same as those of the optical recording media of the first mode and the second mode. The convex structure 1702 of the optical recording medium of the third aspect is substantially cylindrical. Moreover, the period of the tracking direction of the convex structure 1702 is constant. The diameter 1705 of the convex structure changes according to the recorded information.

The reproducing method of the third aspect of the present invention uses the optical recording medium of the third aspect, irradiates light to the convex structure 1702 whose diameter changes according to the recording information, and detects the change of the reflected luminous flux corresponding to the period of the convex structure 1702 . 24A and 24B show an example of a method for reproducing an optical recording medium according to the third embodiment. Fig. 24A is a diagram showing a plan view of an optical recording medium, and Fig. 24B is a diagram showing signal level changes. In FIG. 24A , 1801 denotes a laser, 1702 denotes a convex structure, 1703 denotes a period of a convex structure, and 1704 denotes a magnetic track. In Fig. 24B, 1811 shows the reproduced signal level sampled with A time control, and 1812 shows the reproduced signal level sampled with H time control.

In the method for reproducing an optical recording medium according to the third aspect, multivariate information is recorded in correspondence with changes in the diameter of the convex structure. The reflected light flux is changed according to the diameter by timedly reflecting the laser light at the central position of the convex structure 1702 . As shown in the figure, by detecting (sampling) the signal level at the timing of the period 1703 of the convex structure, multivariate information corresponding to the diameter change can be judged as the signal level change. The result is increased recording density through multivariate recording.

<Optical recording medium and reproducing method thereof of fourth aspect>

The optical recording medium of the fourth aspect of the present invention is the object of the above-mentioned optical recording medium of the first aspect and the second aspect and the object of increasing the recording density by narrowing the track pitch.

The optical recording medium of the fourth mode is the structure of the optical recording medium of the first mode and the second mode, and the convex structure is substantially columnar, and the arrangement of the convex structures in the surface of the optical recording medium is Is the closest packing arrangement (three-time symmetrical arrangement). A cylindrical shape is particularly preferable as the shape of the convex structure. In order to improve the signal quality, it is suitable that the angle of the end of the convex structure is close to a vertical state, that is, a state close to a cylindrical shape. If the angle at the end of the structure is gentle, the adjacent structures will be connected, and the signal quality will be low.

Fig. 25 shows an example of a top view of the structure of the optical recording medium of the fourth embodiment. In FIG. 25 , 1901 is the light absorbing layer, 1902 is the convex structure, 1903 is the period of the convex structure in the tracking direction, and 1904 is the virtual lattice point of the closest packing arrangement (three-time symmetrical arrangement).

The optical recording medium of the fourth mode has a laminated structure and the materials of each layer are the same as those of the optical recording media of the first mode and the second mode. The convex structure 1902 of the optical recording medium of the fourth mode is cylindrical and has a constant diameter. The arrangement of the convex structures 1902 in the medium plane is the closest packing arrangement (three-time symmetrical arrangement). According to the recording information, there are: lattice points with convex structures 1902 and lattice points without convex structures 1902 .

The reproducing method of the fourth aspect of the present invention uses the optical recording medium of the fourth aspect, irradiates the convex structure 1902 with light to simultaneously reproduce a plurality of tracks, and detects the intensity of the reflected light flux corresponding to the period of the convex structure 1902. Variety.

26A and 26B show an example of the reproduction method in the fourth mode. 26A is a drawing showing a plan view of an optical recording medium, in which 1902 denotes a convex structure, 1903 denotes a period of a convex structure, and 2001 denotes a laser beam. Fig. 26A shows a convex structure for three tracks.

The reproducing method of the fourth aspect of the present invention is to simultaneously reproduce the convex structures 1902 rows of a plurality of tracks (at least 2 or more tracks). Simultaneous reproduction here means including a plurality of convex structure rows within the beam diameter.

Ideally, as shown in FIG. 26B , three rows of convex structures are simultaneously reproduced in the radial direction. A reproduced signal is detected (sampled) at timings A, B, C, D, . . . of convex structure periods 1903 in the track direction.

Fig. 26B is a diagram showing changes in the reproduction signal level. In FIG. 26A , 2011 indicates the reproduced signal level sampled at time A, and 2012 indicates the reproduced signal level sampled at time D. In the laser beam path 2001, there are 7 structures in time control A, 6 structure in time control B, 5 structure in time control C, and 5 structure bodies in time control D. The number of structures is changing. The result is a change in reflected light flux. When the signal is sampled according to the timing of the convex structure period 703, the light beams overlap in the track direction, and one convex structure is detected multiple times. By using signal processing technology (PRML: Partial Response Maximum Likelihood: Partial Response Maximum Likelihood) by detecting multiple times, it is possible to judge the arrangement of structures and whether there is corresponding record information. In this way, by changing the arrangement of the convex structures in the medium plane into a close-packed arrangement (three-time symmetrical arrangement) and simultaneously reproducing a plurality of structures, it is possible to achieve narrow track pitch and high density.

<Fifth Optical Recording Medium and Its Reproducing Method>

The optical recording medium of the fifth aspect of the present invention aims at simultaneously reproducing a plurality of tracks with high precision in addition to the objective of the optical recording medium of the fourth aspect with a narrow track pitch.

The optical recording medium of the fifth mode is the structure of the optical recording medium of the fourth mode, plus every n columns (n represents an integer greater than or equal to 2) in the radial direction of the optical recording medium. Columns of shaped constructs.

Fig. 27 shows an example of a longitudinal cross-sectional view in the radial direction of the optical recording medium of the fifth embodiment. In FIG. 27, 2101 is a substrate, 2102 is a buffer layer, 2103 is a light absorbing layer, 2104 is a convex structure, 2105 is a light-transmitting layer, and 2106 is a track pitch.

The arrangement of the convex structures 2104 in the plane of the optical recording medium of the fifth embodiment is a close-packed arrangement (three-time symmetrical arrangement). In addition, every n columns in the radial direction of the optical recording medium are provided with no convex structure 2104 in the column. It is desirable to provide columns in which no convex structures 2104 exist every four columns. Among the tracks a, b, c, d, and e shown in FIG. 27 , there is no convex structure 2104 in tracks a and e. Therefore, the in-plane convex structures 2104 of the optical recording medium can be dense. As a result, when the light-transmitting layer 2105 is laminated, the dense portions b, c, and d of the convex structure are buried by the film, and the sparse portions a, e can form grooves. With such a structure, a step for tracking can be formed at a predetermined position, so that a narrow track pitch and high density can be achieved by simultaneously reproducing a plurality of convex structures 2104 .

In the reproducing method of the fifth aspect of the present invention, using the optical recording medium of the fifth aspect, the n-1 columns are simultaneously reproduced and the reflected light flux is detected.

28A and 28B show an example of the reproduction method in the fifth mode. Fig. 28A is a drawing showing a plan view of the optical recording medium, and Fig. 28B is a longitudinal sectional view of the optical recording medium in the radial direction. In FIG. 28A, 2104 denotes a convex structure, 2106 denotes a track pitch, and 2201 denotes laser light.

In the playback method of the fifth aspect of the present invention, no convex structures 2104 exist in tracks a and e. A push-pull type or a differential push-pull type is used as the tracking method. Diffracted light and reflected light from the groove portions a, e are detected by photodiodes bisected in the track direction and a push-pull signal is generated. The push-pull signal is used as the error signal of the tracking servo.

In the reproducing method of the fifth aspect, by generating push-pull signals from the diffracted light and reflected light from the convex structures a and e, the laser can track the convex structures b, c, and d and simultaneously reproduce three columns. Narrow track pitch and high density can be achieved by simultaneously reproducing multiple structures.

The manufacturing method of the optical recording medium of the present invention includes, for example, at least: a lamination process, which at least laminates a film-shaped light-absorbing layer and a film material that becomes a convex structure on a substrate to form a laminate; The layered body is irradiated with light from the side of the shaped structure to record information; the step of forming the convex structure is to remove the unrecorded portion to form the convex structure, and other steps are included as necessary.

The lamination step and the convex structure forming step can be performed according to the method of manufacturing the structure.

Various vapor phase growth methods can be used as the method for forming the laminate thin film, for example, vacuum deposition method, sputtering method, plasma CVD method, CVD method, ion coating method, electron beam deposition method and the like. Among them, the sputtering method is excellent in terms of mass productivity, film quality, and the like.

According to the manufacturing method of the optical recording medium of the present invention, a fine convex structure can be formed in a large area without a mask.

The present invention will be described in detail by way of examples below. However, this invention is not limited to an Example.

(Example 1)

The medium for structure formation was produced as follows.

The medium for structure formation shown in FIGS. 1 to 3 was produced. The film forming method is cathode sputtering method. The material, film thickness and main film-forming conditions of cathode sputtering method of each layer are shown in Table 1.

[Table 1] media structure Figure's serial number Function material film thickness sputter target gas environment Vacuum RF input power 1 figure 1 101 heat reactive layer SiON 50nm Si O2+N2 1mTorr 1.5kW 102 light absorbing layer Ge 10nm Ge Ar 1mTorr 0.5kW 103 Support substrate Glass 0.6mm - - - - 2 figure 2 101 heat reactive layer ZnS-SiO ₂ 100nm ZnS-SiO ₂ Ar 1mTorr 1.5kW 102 light absorbing layer AgInSbTe 10nm AgInSbTe Ar 1mTorr 0.3kW 101 heat reactive layer ZnS-SiO ₂ 50nm ZnS-SiO ₂ Ar 1mTorr 1.5kW 103 Support substrate polycarbonate 0.6mm - - - - 3 image 3 102 light absorbing layer SiC 5nm SiC Ar 1mTorr 1.5kW 101 heat reactive layer CaF2 60nm CaF2 Ar 1mTorr 0.3kW 103 Support substrate quartz 0.6mm - - - -

(Example 2)

The structure shown in FIG. 1 was used as the medium for structure formation. The layer structure is glass substrate/Ge/SiON. The film-forming conditions of each layer are shown in Table 1. A structure was formed on this structure forming medium as follows.

The formation of the structure is carried out in the order of the light irradiation step ( FIG. 4 )→the etching step ( FIG. 5 ).

A laser irradiation device shown in FIG. 12 was used in the light irradiation step. The laser irradiation device 61 includes a semiconductor laser. The wavelength of the laser is 405nm. Objective lens NA is 0.65. The structure forming medium shown in FIG. 1 is irradiated with laser light from the side of the substrate 103 . As shown in FIG. 16, the laser beam is pulse-modulated by the laser modulation device 62. Energy level P1 is 10mW and P2 is 3mW. The pulse width T is 24nsec. The pulse period S is 143nsec. The media is rotated by the media rotation device 64 . The rotation speed is 3.5 m/sec. The periodic change portion 202 is formed on the thermal reaction layer SiON by the above method.

In the etching process, the etching is performed by the RIE method. The treatment is performed by the oxide etching gas CF ₄ . The processing pressure is 1mTorr, and the input power is 200W. The structure 204 is formed by removing the portion other than the portion changed by the laser irradiation by the RIE method.

A structure is formed by the above method. The cross-sectional shape of the structure was the shape shown in FIG. 13 . The period of the structure is 500 nm, and the size (diameter) is 250 nm. The changed portion remains without being etched, and a convex structure can be formed.

(Example 3)

The structure shown in FIG. 2 was used as the medium for structure formation. The layer structure is polycarbonate resin substrate/ZnS-SiO ₂ /AgInSbTe/ZnS-SiO ₂ . The film-forming conditions of each layer are shown in Table 1. Constructs are formed on this medium. The optical absorptivity of ZnS-SiO ₂ with respect to a laser wavelength of 405 nm is 6×10 ^-4 .

The formation of the structure is performed in the order of the light irradiation step ( FIG. 9 )→the etching step ( FIG. 10 ).

A laser irradiation device shown in FIG. 12 was used in the light irradiation step. The laser irradiation device 61 includes a semiconductor laser. The wavelength of the laser is 405nm. Objective lens NA is 0.85. Laser light was irradiated from the ZnS-SiO ₂ side of the uppermost layer to the medium film surface for structure formation shown in FIG. 2 . As shown in FIG. 16, the laser beam is pulse-modulated by the laser modulation device 62. Energy level P1 is 4mW and P2 is 1mW. The pulse width T is 19nsec. The pulse period S is 11nsec. The pulse duty ratio (pulse width/pulse period) was 17%. The media is rotated by the media rotation device 64 . The rotation speed is 3.5 m/sec. Periodic variation portions 302 were formed on the thermally reactive layer ZnS-SiO ₂ by irradiating laser pulses as shown in FIG. 16 .

Etching is performed by wet etching. The etching solution 402 is a hydrogen fluoride (HF) aqueous solution (HF:H ₂ O=1:2). Immerse the media in the HF solution for 10 seconds. The structures 403 are formed by etching with an HF solution.

A structure is formed by the above method. The shape of the structure is the inverted cone shape shown in FIG. 14 . The period of the structure is 400 nm, and the size (diameter) of the structure is 250 nm.

FIG. 17 shows the formed structure as an SEM image. A structure with a uniform shape can be formed on a large-area medium with a diameter of 12 cm.

(Example 4)

The structure shown in FIG. 2 was used as the medium for structure formation. The layer structure is polycarbonate resin substrate/ZnS-SiO ₂ /AgInSbTe/ZnS-SiO ₂ . The material, film thickness, and film-forming conditions of each layer are shown in Table 2. The optical absorptivity of ZnS-SiO ₂ with respect to a laser wavelength of 405 nm is 6×10 ^-4 .

[Table 2] drawing number serial number Function material film thickness sputter target gas environment Vacuum RF input power figure 2 101 heat reactive layer ZnS-SiO ₂ 200nm ZnS-SiO ₂ Ar 1mTorr 1.5kW 102 light absorbing layer AgInSbTe 10nm AgInSbTe Ar 1mTorr 0.3kW 101 heat reactive layer ZnS-SiO ₂ 50nm ZnS-SiO ₂ Ar 1mTorr 1.5kW 103 Support substrate polycarbonate 0.6mm - - - -

The formation of the structure is performed in the order of the light irradiation step ( FIG. 9 )→the etching step ( FIG. 10 ).

A laser irradiation device shown in FIG. 12 was used in the light irradiation step. The laser irradiation device 61 includes a semiconductor laser. The wavelength of the laser is 405nm. Objective lens NA is 0.85. The laser beam is injected into the film surface from the ZnS-SiO ₂ side of the uppermost layer. As shown in FIG. 16, the laser beam is pulse-modulated by the laser modulation device 62. Energy level P1 is 5mW and P2 is 1.4mW. The pulse width T is 10nsec. The pulse period S is 58nsec. The pulse duty ratio (pulse width/pulse period) was 17%. The media is rotated by the media rotation device 64 . The rotation speed is 3.5 m/sec. Periodic variation portions 302 were formed on the thermally reactive layer ZnS-SiO ₂ by irradiating laser pulses as shown in FIG. 16 .

Etching is performed by wet etching. The etching solution 402 is an aqueous solution of hydrogen fluoride (HF) (HF:H ₂ O). Immerse the media in the HF solution for 10 seconds. The structures 403 are formed by etching with an HF solution.

A structure is formed by the above method. The cross-sectional shape of the structure was the vertical shape shown in FIG. 15 . The period of the structure is 300 nm, the height is 200 nm, and the size (diameter) is 200 nm. The depth ratio (height/diameter) is 1. FIG. 18 shows the formed structure as an SEM image. A structure with a uniform shape can be formed on a large-area medium with a diameter of 12 cm.

(Example 5)

An optical recording medium having the structure shown in Fig. 19 was produced.

The material of the substrate 1301 is polycarbonate, and its thickness is 0.6 mm.

The material of the buffer layer 1302 is ZnS-SiO ₂ , and its film thickness is 50 nm. Film formation was performed by sputtering. The composition of the sputtering target was ZnS 80% mol, SiO ₂ 20% mol.

The material of the light absorbing layer 1303 is AgInSbTe, and its film thickness is 20 nm. The convex structure 1304 contains ZnS and SiO ₂ , the height of the convex structure from the top of the light absorbing layer is 50 nm, and the track period 1305 thereof is 200 nm.

The manufacturing method of the optical recording medium is shown with reference to FIGS. 9 , 10 , and 16 .

First, each layer is formed in the lamination process shown in the upper diagram of FIG. 9 . The substrate 101 is made of polycarbonate resin. The buffer layer 101 uses ZnS-SiO ₂ , and its film thickness is 50 nm. Film formation was performed by sputtering. The composition of the sputtering target was ZnS 80% mol, SiO ₂ 20% mol. The light absorbing layer 103 is AgInSbTe, and its film thickness is 20 nm. The thin film 101 that becomes the convex structure is ZnS—SiO ₂ , and the film thickness is 50 nm. Film formation was performed by sputtering. The composition of the sputtering target was ZnS 80% mol, SiO ₂ 20% mol. The conditions of the cathode sputtering method for each layer are that the film forming temperature is room temperature, and the film forming environment is argon.

Then, in the recording process shown in FIG. 9, laser light 301 is irradiated from the side of the film forming the convex structure to record information. The laser wavelength used in the recording is 405 nm, and the numerical aperture of the objective lens is 0.85.

As shown in FIG. 16, recording is performed by the energy level modulation method of laser light. The energy level is modulated with the double standard of P1=5mW and P2=0.7mW. The pulse width T is 15nsec. The pulse period S is 57nsec. The pulse duty ratio (pulse amplitude/pulse period) was 26%. A single-cycle signal with a period of 200 nm was recorded under these conditions.

Fig. 10 shows the etching process. After the information is recorded, the unrecorded part of ZnS-SiO ₂ is removed and processed into a convex shape. 401 is a recording portion of ZnS-SiO ₂ . 402 represents an etching groove. 403 represents an etching solution. 404 represents ZnS-SiO ₂ processed into a convex shape. The etching solution 403 uses a mixed solution of hydrofluoric acid (HF) and water (H ₂ O). Use a 50% dilute solution of hydrofluoric acid. The solution ratio is HF:H ₂ O=1:10. The recording medium was immersed in the solution for 10 seconds. Immediately after etching, it is washed with water and dried with dry nitrogen or the like. An optical recording medium having a convex structure was produced by the above method.

The convex structure of the optical recording medium is reproduced by the method shown in Fig. 20A and Fig. 20B.

Using an objective lens with a numerical aperture of 0.85 and a laser with a wavelength of 405 nm, the reproduction power was set to be 1.5 mW. The resolution limit period (λ/2NA) of this optical system is 238 nm. The optical recording medium having the structure shown in Fig. 19 is reproduced by the method shown in Figs. 20A and 20B. That is, light is irradiated from the convex structure side and changes in reflected light flux are detected. As a result, information corresponding to a period of 200nm less than or equal to the resolution limit period can be detected.

(Example 6)

An optical recording medium having the structure shown in Fig. 21 was produced.

The material of the substrate 1501 is polycarbonate resin, and its thickness is 0.6 mm. The material of the buffer layer 1502 is ZnS-SiO ₂ , and its film thickness is 50 nm. SbTe was used as a material of the light absorbing layer 1503, and its film thickness was 20 nm. The convex structure 1504 contains ZnS and SiO ₂ , the height of the convex structure from the top of the light absorbing layer is 70 nm, and the track period 1506 thereof is 200 nm. SiON was used as a material for the light-transmitting layer 1506, and its film thickness was 150 nm.

The manufacturing method of the above-mentioned optical recording medium is as follows. The production method of the convex structure is the same as in Example 5. The light-transmitting layer 1505, that is, SiON, is laminated after the convex structure is produced. Film formation was performed by sputtering. The film-forming temperature was room temperature. The sputtering target is Si used. The film forming environment is a mixed environment of oxygen and nitrogen.

The convex structure of the optical recording medium was reproduced by the method shown in FIG. 22 .

Using an objective lens with a numerical aperture of 0.85 and a laser beam with a wavelength of 405 nm, the reproduction power was set to be 1.0 mW. The resolution limit period (λ/2NA) of this optical system is 238 nm. The optical recording medium having the structure shown in Fig. 21 is reproduced by the method shown in Fig. 22 . That is, light is irradiated from the light-transmitting layer side and changes in reflected light flux are detected. As a result, information corresponding to a period of 200nm less than or equal to the resolution limit period can be detected.

(Example 7)

Cylindrical convex structures were arranged as shown in FIG. 23, and an optical recording medium having a layered structure made of the same materials as in Example 5 was fabricated.

The recording period 1703 in the track direction is 250 nm, the track pitch 1706 is 320 nm, and the diameter of the convex structure is changed according to the recording information. The maximum diameter 1705 of the convex structure is 250 nm, and the diameter is changed in 8 steps including the case where there is no convex structure.

The convex structure of the optical recording medium is reproduced by the method shown in Fig. 24A and Fig. 24B.

Using an objective lens with a numerical aperture of 0.85 and a laser with a wavelength of 405 nm, the reproduction power was set to be 1.5 mW. The resolution limit period (λ/2NA) of this optical system is 238 nm. Figure 24A shows the marker configuration. 1702 denotes a convex structure, 1703 denotes a recording cycle, and 1704 denotes a beam moving direction. Fig. 24B shows changes in the reproduced signal level. 1811 is the signal level sampled with the A time control in FIG. 24A , and 1812 is the signal level sampled with the H time control in FIG. 24A . By time-controlling the signal sampling at the cycle 1703 of the convex structure, it is possible to detect a reproduced signal whose signal level changes in eight steps according to the diameter. By the structure and reproducing method of the above optical recording medium, it is possible to reproduce multivalued information of 8 variable levels.

(Embodiment 8)

Cylindrical convex structures were arranged as shown in FIG. 25, and an optical recording medium having a layered structure made of the same material as in Example 5 was fabricated.

The recording period 1903 in the track direction is 137nm, the track pitch 1906 is 119nm, and the diameter 1905 of the convex structure is constant at 60nm. Fig. 26A shows the relationship between the arrangement of convex structures and the reproduction signal level. Fig. 27 shows the shape of the cross section of the medium. 26A and 26B are medium plan views showing the relationship between convex structure arrays and laser beams.

As shown in the cross-sectional view of the medium in FIG. 27, tracks (a, e) without convex structures are provided every four tracks. Steps every three tracks are formed by laminating the light-transmitting layer 1205 . As shown in FIG. 23, three tracks b, c, and d are reproduced simultaneously. As shown in Figure 26A, the signal is timedly sampled with a period 1903 of the convex structures. At this time, the signal level is changed according to the number of convex structures included in the beam path 2001 . Fig. 26B shows changes in signal levels. The signal level 2011 represents the signal level sampled at the A timing in FIG. 26A , and the signal level 2012 represents the signal level sampled at the D timing in FIG. 26A . In the beam path, there are states from a state A including seven convex structures to a state in which no convex structures exist (not shown in the figure). As a result, a reproduced signal whose signal level changes in 14 steps can be detected. In this way, by changing the arrangement of the convex structures in the medium plane into a close-packed arrangement (three-time symmetrical arrangement) and simultaneously reproducing a plurality of structures, it is possible to achieve narrow track pitch and high density.

The structure produced by the structure manufacturing method of the present invention can uniformly form microstructures on a large-area medium, and has a high depth ratio (the height of the structure/the size of the structure). Needless to say, the optical recording medium can also be used on a large-area medium. Applications in various fields such as biomimetic functional chips, lithographic crystals, and component separation materials for various electronic devices.

The optical recording medium of the present invention can be suitably used as various optical recording media, especially original media.

Claims (34)

1, a kind of tectosome forms and uses medium, it is characterized in that, has the laminated at least laminate structures that contains the light absorbing zone of light absorbing material and contain the reactable layer of thermal response material.

2, tectosome as claimed in claim 1 forms and uses medium, it is characterized in that described reactable layer is positioned at the superiors of described laminate structures, and this reactable layer contains the material that the irradiation light wavelength is had light transmission.

3, tectosome as claimed in claim 1 or 2 forms and uses medium, it is characterized in that, described reactable layer contains the mixture of materials A and material B, described materials A is the silicon compound material, and described material B is select from sulfide material, selenide material and fluorine compounds material at least a.

4, a kind of manufacture method of tectosome is characterized in that, comprising: operation is penetrated in illumination, to having the laminated at least light absorbing zone of light absorbing material and the tectosome formation medium irradiates light of the laminate structures of the reactable layer that contains the thermal response material of containing; Etching work procedure carries out etching and processing to the tectosome formation that this illumination was penetrated with medium.

5, the manufacture method of tectosome as claimed in claim 4 is characterized in that, described reactable layer is positioned at the superiors of laminate structures, and this reactable layer contains the material that the irradiation light wavelength is had light transmission.

6, as the manufacture method of claim 4 or 5 described tectosomes, it is characterized in that, described reactable layer contains the mixture of materials A and material B, described materials A is the silicon compound material, and described material B is select from sulfide material, selenide material and fluorine compounds material at least a.

As the manufacture method of each described tectosome of claim 4～6, it is characterized in that 7, the reactable layer side irradiates light of operation from the superiors penetrated in illumination.

As the manufacture method of each described tectosome of claim 4～7, it is characterized in that 8, the only laser that operation is shone is penetrated in illumination.

9, the manufacture method of tectosome as claimed in claim 8 is characterized in that, LASER Light Source is a semiconductor laser.

10, the manufacture method of tectosome as claimed in claim 9 is characterized in that, adopts such laser irradiation device: it comprises to semiconductor laser irradiation unit, Laser Modulation device and the medium drive of tectosome formation with the medium irradiating laser.

11, as the manufacture method of each described tectosome of claim 8～10, it is characterized in that, when tectosome forms with the medium irradiating laser, make this medium rotation.

12, the manufacture method of tectosome as claimed in claim 11, it is characterized in that, adopt such laser irradiation device: it comprises to laser irradiation device, Laser Modulation device, medium whirligig and the signal supervisory instrument of tectosome formation with the medium irradiating laser.

As the manufacture method of each described tectosome of claim 4～12, it is characterized in that 13, etching work procedure is to be undertaken by wet etching.

14, a kind of tectosome is characterized in that, its manufacture method by each described tectosome of claim 4～13 is made.

15, tectosome as claimed in claim 14 is characterized in that, the end surface shape of tectosome section is approximate vertical and any of back taper shape roughly.

As claim 14 or 15 described tectosomes, it is characterized in that 16, tectosome is the convex tectosome that forms on the surface of optical recording media.

17, a kind of optical recording media, it is characterized in that, comprise: substrate, absorb light and the light absorbing zone that generates heat and be right after this light absorbing zone and contain convex tectosome with this light absorbing zone unlike material on this substrate, this convex tectosome forms by the manufacture method of each described tectosome of claim 4～13.

18, a kind of optical recording media, it is characterized in that, comprise: substrate, the light absorbing zone that generates heat absorbing light on this substrate, be right after this light absorbing zone and contain with the convex tectosome of this light absorbing zone unlike material and this convex tectosome on light is had light transmission photic zone, this convex tectosome forms by the manufacture method of each described tectosome of claim 4～13, and described photic zone covers the surface of described convex tectosome and forms roughly hemispherical.

As claim 17 or 18 described optical recording medias, it is characterized in that 19, the convex tectosome is a cylindricality roughly.

20, as each described optical recording media of claim 17～19, it is characterized in that the convex tectosome is a substantial cylindrical, and the diameter corresponding record information change of this convex tectosome.

21, as each described optical recording media of claim 17～20, it is characterized in that the convex tectosome is a substantial cylindrical, and this convex tectosome is arranged as symmetric arrays three times in the optical recording media face.

As each described optical recording media of claim 17～21, it is characterized in that 22, on each of n magnetic track row on the radial direction of optical recording media the magnetic track row that do not have the convex tectosome are set, wherein, n represents the integer more than or equal to 2.

As each described optical recording media of claim 17～22, it is characterized in that 23, light absorbing zone contains at least a element of selecting from Sb, Te, In.

24, as each described optical recording media of claim 17～22, it is characterized in that, the convex tectosome contains the mixture of materials A and material B, described materials A is the silicon compound material, and described material B is select from sulfide material, selenide material and fluorine compounds material at least a.

25, optical recording media as claimed in claim 24 is characterized in that, the convex tectosome contains ZnS and SiO ₂Mixture.

26, as each described optical recording media of claim 17～25, it is characterized in that between substrate and light absorbing zone, having cushion.

27, a kind of reproducting method of optical recording media is characterized in that, adopts such optical recording media: it has on substrate the light absorbing zone that absorbs playback light and generate heat and is right after this light absorbing zone and contains convex tectosome with this light absorbing zone unlike material,

From this described light absorbing zone of convex tectosome side direction and convex tectosome irradiation playback light, detection of reflected luminous flux.

28, a kind of reproducting method of optical recording media, it is characterized in that, adopt such optical recording media: it has the light absorbing zone that generates heat absorbing playback light on the substrate, be right after this light absorbing zone and contain with the convex tectosome of this light absorbing zone unlike material and this convex tectosome on playback light is had light transmission photic zone, this photic zone covers described convex tectosome surface and forms roughly hemispherical

From the lamilated body irradiation playback light that this photic zone side direction is made of described light absorbing zone, convex tectosome and photic zone, detection of reflected luminous flux.

As the reproducting method of claim 27 or 28 described optical recording medias, it is characterized in that 29, the convex tectosome is a cylindricality roughly.

As the reproducting method of each described optical recording media of claim 27～29, it is characterized in that 30, the convex tectosome is a substantial cylindrical, and the diameter corresponding record information change of this convex tectosome.

As the reproducting method of each described optical recording media of claim 27～30, it is characterized in that 31, the convex tectosome is a substantial cylindrical, and this convex tectosome is arranged as symmetric arrays three times in the optical recording media face.

32, as the reproducting method of each described optical recording media of claim 27～31, it is characterized in that, to convex tectosome irradiation playback light and a plurality of magnetic tracks row are reproduced simultaneously, to cycle that should the convex tectosome and the detection of reflected luminous flux.

33, as the reproducting method of each described optical recording media of claim 27～32, it is characterized in that, each of n magnetic track row is provided with the magnetic track row that do not have the convex tectosome on the radial direction of optical recording media, and wherein, n represents the integer more than or equal to 2.

34, the reproducting method of optical recording media as claimed in claim 33 is characterized in that, makes n-1 magnetic track row reproduce the detection of reflected luminous flux simultaneously.

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