JP2013161496A - Information recording medium and pattern forming master - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an information recording medium having dot recording parts disposed with high density in a regular lattice-like arrangement in a circumferential direction on a disk base plate.SOLUTION: The information recording medium includes: a concentric or spiral linear partition region 102a formed in a circumferential direction on a disk-like base plate 101; a linear partition region 102b crossing the tracks; plural cells 103 enclosed by the partition regions; and plural dot recording parts 105 disposed in a lattice-like arrangement. An average distance between the centers of closest dot recording parts in the cells is a. The difference between the length 107 of the inner periphery arc of a cell, which is a boundary between the linear partition region 102a and cells in a track direction, and the length 108 of the outer arc of a cell, which is a boundary between the linear partition region 102b and cells in the track direction, is smaller than a/2.

Description

  The present invention relates to an information recording medium and a method for manufacturing the information recording medium, and more particularly to a high-density information recording medium in which recording / reproduction is performed using near-field light, a magnetic field, or the like.

  In the field of information recording, various researches on optical information recording are underway. As the present optical disk, CD, DVD, Blu-ray disk, etc. are widely used. With further progress in the information recording field, higher density optical memories are being demanded. CDs, DVDs, and Blu-ray discs have achieved high density by reducing the shortest mark lengths to 0.83 μm, 0.40 μm, and 0.15 μm, respectively. However, in the current optical recording system, it is considered difficult to make the recording mark much smaller than this because of the diffraction limit of light.

  In recent years, optical recording methods using near-field light have attracted much attention as a technology that breaks this diffraction limit. This near-field light is light that is generated in a form that is localized in the vicinity when light enters an aperture or fine particle having a size smaller than the wavelength of the light, and the spot diameter formed by the near-field light. Does not depend on the wavelength of the incident light, but is determined by the size of the incident aperture or fine particles.

  Conventionally, many methods have been adopted in which light is incident on a sharpened fiber probe or the like, and near-field light is generated at a minute opening provided at the tip of the fiber probe. However, there is a problem that light use efficiency with respect to incident light is low. It was. In recent years, a near-field light generating element using metal surface plasmon resonance has been proposed as a technique for greatly improving the light utilization efficiency (for example, Patent Document 1). In this technique, a minute metal film is irradiated with light of an appropriate wavelength to induce surface plasmon resonance, and near-field light is generated in the vicinity of the metal film to perform recording / reproduction.

  In order to improve the recording density, many methods for performing stable recording and reproduction by forming a pattern on a substrate in advance (patterned media) have been proposed (for example, Patent Document 2 and Patent Document 3).

  By using these to record finer recording marks, it is possible to realize further higher density and larger capacity of the optical memory.

  In order to record 1-bit information on one dot-shaped recording portion with this patterned medium, it is generally necessary that these dot-shaped recording portions are regularly arranged.

  One method for forming regularly arranged dot-shaped recording portions is a method using photolithography. However, when ultraviolet exposure is performed, ultrafine processing is impossible. In addition, although charged particle beam drawing enables ultra-fine processing, it is unrealistic to form a large number of dot-shaped recording portions in terms of processing cost and processing speed.

  Under such circumstances, a process that applies a phenomenon in which a substance naturally forms a structure, that is, a so-called self-organization phenomenon, has attracted attention. In particular, the process applying the self-organization phenomenon of polymer block copolymer (block copolymer), so-called microphase separation phenomenon, is a fine regular structure having various shapes of several tens to several hundreds of nanometers by a simple coating process. It is an excellent process in that it can be formed.

  This method is described in, for example, Patent Document 3 below, and a solution obtained by dissolving a block copolymer of polymer A and polymer B in a solvent is spin-coated on a substrate, and a coating film obtained thereby is formed. Annealing. The annealing treatment mentioned here is a technique for improving the arrangement regularity of the microphase separation structure of the block copolymer and reducing defects. Specifically, the block copolymer after film formation is maintained in a steady state at a glass transition temperature (Tg) or higher and a decomposition temperature (Td) or lower in vacuum or in an inert gas atmosphere such as argon gas or nitrogen gas. Examples thereof include a method and a method of holding in a solvent atmosphere in which the block copolymer is dissolved. In this way, by appropriately setting various conditions, a substantially spherical or substantially cylindrical island-shaped region made of the polymer B and a sea-like region made of the polymer A can be generated in the coating film. Alternatively, the substantially cylindrical island regions can be regularly arranged, specifically, so that they form a hexagonal lattice. In this method, a dot-shaped recording portion is formed using the array obtained in this way.

  In this method, the island-like region and the sea-like region are formed using the self-organization phenomenon, so that an extremely fine pattern can be easily formed. However, the previous self-organization phenomenon does not occur from one place in the coating film, but originates from a plurality of places. Under the condition that external regulatory force is not acting, the hexagonal lattice obtained as a result of the self-organization phenomenon starting from a certain location and the result of the self-organization phenomenon originating from another location There is no correlation in the arrangement direction with the obtained hexagonal lattice. Therefore, many regions (hereinafter referred to as grains) having different hexagonal lattice arrangement directions and arrangement regularities are generated in the coating film.

  Therefore, when producing patterned media using the self-organization phenomenon, it is necessary to devise a method for aligning the pattern arrangement direction when forming a self-organized pattern. For example, a method of arranging a block copolymer pattern along a linear step direction existing on the surface of a single crystal is known (Non-Patent Document 1). Thus, in order to align the arrangement direction of self-organized patterns on patterned media, it is considered effective to form a guide pattern with directionality such as a linear groove structure or peak structure on the substrate surface. It has been. When self-organizing pattern formation occurs in the vicinity of these guide patterns, the patterns are arranged along grooves and peaks. Therefore, it is considered that if the concentric or spiral groove or peak pattern is formed in the circumferential direction of the disc (hereinafter referred to as the track direction), the pattern directions of the recording material can be aligned.

  In the case of producing patterned media using the above-mentioned concentric circles or spiral patterns, since the grains grow from random positions on the circumference, they have a regular lattice structure within each grain. However, at the position where adjacent grains grow and collide with each other, there is no lattice alignment consistency between the grains, so that pattern formation occurs at a position deviating from the lattice position, thereby generating a defect. In patterned media using the self-organization phenomenon, such a defect in the arrangement at random positions causes an error in writing and reading.

  Therefore, particles (dots) are formed on a substrate by forming a linear pattern (separation region) so as to surround a plurality of cells, and by self-organizing a self-organizing material in the plurality of cells to form a regular lattice. ) -Like arrangement patterns have been proposed (for example, Patent Document 3).

Japanese Patent No. 4032689 Japanese Patent No. 2584122 Japanese Patent No. 3793040

M.M. J. et al. Fasolka et al. Phys. Rev. Lett. Vol. 79 (1997) p. 3018 P. R. Krauss, et al. , J. et al. Vac. Sci. Technol. B13 (1995), pp. 2850 K. Asaka et al. APS March Meeting, 2000

  However, in the conventional configuration, when the cell and separation region forming method arranges the dot-like arrangement pattern along the circumferential direction, for example, in the same cell, the outer side of the inner side is dot-like recording. Since it is considered that the number of parts arranged on the circumference increases, it is not possible to sufficiently suppress the occurrence of multiple grains and the occurrence of defects in the same cell. In addition, since the separation area is not generally used as a recording area, it is desirable that the number of separation areas is small in order to form a large number of dot-shaped recording portions in terms of increasing the density and capacity of the information recording medium. . On the other hand, if the separation region is insufficient, pattern formation occurs at a position deviated from the lattice position, and a defect occurs.

  The present invention solves the above-described conventional problems. On a disk-shaped substrate, the dot-shaped recording portion produced by utilizing the smallest possible separation region and self-organization phenomenon forms a regular lattice to increase the height. Disclosed is an information recording medium that is arranged in a density and has less irregularity in the arrangement of dot-shaped recording portions and occurrence of defects, and a method for manufacturing the same, and a pattern forming master for manufacturing such an information recording medium and a method for manufacturing the same. For the purpose.

  In order to solve the above-described conventional problems, an information recording medium of the present invention includes at least a linear separation region along a concentric or spiral track direction formed on a disk-shaped substrate, and a linear shape crossing the track. Separation areas, a plurality of cells surrounded by the separation areas, and a plurality of dot-shaped recording portions arranged in a lattice pattern and having an average value in the cell of the distance between the centers of the closest neighbors is a. An information recording medium provided with a length of an arc on the inner peripheral side of the cell (hereinafter referred to as an arc on the inner peripheral side of the cell) and a track direction of the cell, which is a boundary between the linear separation region along the track direction and the cell The difference in the length of the arc on the outer periphery side of the cell (hereinafter referred to as the arc on the outer periphery side of the cell) serving as the boundary between the on-line separation region and the cell is less than a / 2.

  According to this configuration, when forming a lattice-like pattern that becomes a dot-like recording portion using the self-organization phenomenon, it is possible to suppress the disorder of the lattice arrangement in the cell and the occurrence of defects.

  According to the information recording medium and the method for manufacturing the information recording medium of the present invention, the dot-shaped recording portion produced by utilizing the self-organization phenomenon on the disc-shaped substrate with the smallest possible separation area is provided in the circumferential direction. In addition, an information recording medium can be obtained that is arranged at a high density along the line and in which the disorder of the arrangement of the dot-shaped recording portions and the occurrence of defects are small.

1 is a plan view and an enlarged view of an information recording medium according to Embodiment 1 of the present invention. Sectional drawing between a-a 'of the information recording medium in Embodiment 1 of this invention In Embodiment 1 of the present invention, a plan view of a cell of an example in which a linear separation region crossing a track is approximately 120 ° with respect to a linear separation region along the track direction In the first embodiment of the present invention, the plane of the cell in the example in which the linear separation region crossing the track is formed by a polygonal line along a hexagonal lattice expected to be formed when the self-organization phenomenon is used. Figure In the first embodiment of the present invention, the plane of the cell in the example in which the linear separation region crossing the track is formed with a curve along a hexagonal lattice expected to be formed when the self-organization phenomenon is used. Figure FIG. 2 is a plan view of an example information recording medium in which cells are elongated in the track direction in the first embodiment of the present invention. In Embodiment 1 of this invention, the top view of the information recording medium of the example which elongated the cell to radial direction The top view of the information recording medium of the example which combined the cell from which a dimension mutually differs in Embodiment 1 of this invention Sectional drawing which showed the process of Embodiment 1 of this invention Sectional drawing which showed the process of Embodiment 2 of this invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of application of the present invention is particularly limited in the following description. As long as there is no description which limits invention, it is not restricted to these aspects.

(Embodiment 1)
FIG. 1 is a plan view and an enlarged view of an information recording medium according to Embodiment 1 of the present invention.

  In FIG. 1, a cell 103 is a region surrounded by a linear separation region 102a along the track direction and a linear separation region 102b that crosses the track. In this cell 103, a self-organization phenomenon is utilized. Thus, dot-shaped recording portions 105 arranged in a hexagonal lattice are formed.

  Here, when the patterned cells and the plurality of cells 103 are formed on the circular disk substrate as shown in FIG. 1, the circumference is always longer on the outer circumference side than on the inner circumference side. However, it is necessary to make the arc on the outer peripheral side longer than the inner peripheral side. However, when the difference between the arc length 107 on the inner peripheral side and the arc length 108 on the outer peripheral side is greater than or equal to a / 2 with respect to the distance a106 between the closest dots of the dot-shaped recording unit 105, self-organization The number of dots produced along the outer circumferential arc when using the crystallization phenomenon is more stable by one or more than the number of dots produced along the inner circumferential arc, thereby The probability of occurrence of disorder of arrangement, multiple grains, defects, etc. increases.

  Therefore, if the difference between the arc length 107 on the inner circumference side of the cell 103 and the arc length 108 on the outer circumference side is less than a / 2, the inner circumference side and the outer circumference side in the cell 103 are aligned along the track. Since the number of the dot-shaped recording portions 105 is the same, when arranging the dot-shaped recording portions 105 on the circumference using the self-organization phenomenon, it is possible to suppress the occurrence of disorder of arrangement, multiple grains, defects, and the like. it can.

  Note that the closest dot-to-dot distance a here is an average value of the center-to-center distances of the dot-shaped recording portions that are closest to each other in the cell 103, and is an arc on the inner peripheral side of the cell, an arc on the outer peripheral side of the cell, a track The positional relationship of the separation regions 102a on the line along the direction is as shown in FIG.

  Note that when the linear separation region 102b crossing the track is a line segment substantially perpendicular to the linear separation region 102a along the track direction or a separation region close thereto, both ends of the arc on the inner peripheral side of the cell The relationship between the angle θ104 formed by the two points and the center of the disk and the distance Δr109 from the inner arc to the outer arc of the cell satisfies Δrθ <a / 2, and Δrθ is as large as possible. If the linear separation regions 102a and 102b are formed in the cell 103, the cell 103 in which the dot-like recording portions 105 are arranged is reduced while suppressing the occurrence of disorder of the arrangement and the occurrence of defects and generally reducing the number of the linear regions 102a and 102b which are non-recording materials. The area can be increased.

  Note that the linear separation region 102b that crosses the track further prevents the occurrence of disorder of the arrangement and defects, and therefore, the line segment along the hexagonal lattice that is expected to be formed when the self-organization phenomenon is used. It is desirable to form with a polygonal line or a curved line. For example, the linear separation region 102b crossing the track may be formed to be approximately 60 ° or 120 ° with respect to the linear separation region 102a along the track direction. FIG. 2 shows a case where the linear separation region 102b crossing the track is approximately 120 ° with respect to the linear separation region 102a along the track direction. Moreover, although the example of a broken line and a curve along a hexagonal lattice expected to be formed when the self-organization phenomenon is used is shown in FIGS. 3 and 4, the present invention is not limited to this. Even in this case, there is a relationship between the angle θ104 formed by the two points on both ends of the arc on the inner circumference side of the cell and the center of the disk and the distance Δr109 from the arc on the inner circumference side to the arc on the outer circumference side of the cell. It is desirable to form the linear separation regions 102a and 102b so that Δrθ <a / 2 is satisfied and Δrθ is as large as possible.

  In the above case, the cell 103 only needs to be formed so as to satisfy Δrθ <a / 2. As shown in FIG. 5, the cell 103 is elongated in the track direction, and the number of separation regions on the line along the track direction. In addition, the linear separation region that crosses the track may be reduced, or the cell 103 may be elongated in the radial direction as shown in FIG. 6 to reduce the number of separation regions on the line along the track direction. The number of linear separation regions that traverse may be increased. Alternatively, as shown in FIG. 7, cells having different dimensions may be combined while satisfying Δrθ <a / 2. However, the present invention is not limited to these.

  For the production of a specific information recording medium, first, a recording layer 801 made of a recording material is formed on the disk substrate 101 (FIGS. 8A and 8B). On this recording layer, a control film 102 for forming a linear separation region having a groove structure, a peak structure, or a chemical pattern for controlling the arrangement of the self-organizing material is formed (FIG. 8C). . The linear separation regions 102a and 102b are patterned on the control film 102 by lithography as described above (FIG. 8D). After the self-organizing materials 802a and 802b are formed in the cells 103 or on the linear separation regions surrounded by the linear separation regions 102a and 102b, the self-organization materials 802a and 802b are formed by annealing or the like. Are regularly arranged (FIG. 8E).

  The material of the substrate 101 is not particularly limited in the present invention. However, in consideration of surface smoothness and availability, a silicon wafer or a glass substrate is desirable. The substrate 101 may be subjected to hydrophilic / hydrophobic surface treatment or various films may be formed as necessary.

  The recording layer 801 uses a phase change material in (Example 1) to be described later, but may be a magnetic material that can be magnetically recorded, and can change a physical state, and this state is changed to some physical phenomenon. In the present invention, there is no particular limitation as long as it can be a recording layer of an information recording medium that can be read using the above.

  Any material can be used for the control film as long as the structure can be formed by lithography without destroying the recording layer, and any damage can be caused by the film formation of the self-organized material and the regular alignment process. Is used, but is not particularly limited in the present invention.

  For the lithography of the control film, there are a method using a scanning probe such as optical lithography, electron beam lithography, atomic force microscope, scanning tunneling microscope, and near-field light microscope, and nanoimprint lithography (for example, Non-Patent Document 2). Although used, it is not particularly limited in the present invention.

As the self-organizing material, block copolymers, fine particles having a diameter of several nm to several tens of nm made of a polymer or metal are used. When using block copolymers, use materials with different etching resistance to processing means such as RIE of two or more types of blocks to be formed, or use one that can be removed by any method. Is preferred. For example, when a block copolymer made of polystyrene and polymethyl methacrylate is used, the etching resistance to reactive ion etching (RIE) using CF ₄ as an etchant is higher than that of polymethyl methacrylate. It has been reported that it is possible to selectively scrape only the portion of the recording layer on the underlayer (for example, Non-Patent Document 3). Further, when a block copolymer made of polystyrene and polybutadiene is used, development processing is possible so that only polystyrene blocks remain by ozone treatment.

  The above block copolymer is an example of an AB type diblock copolymer having a structure in which two types of polymer chains of the polymer A and the polymer B are bonded, but may be an ABA type triblock copolymer, Or the block copolymer which four or more types of polymer chains couple | bonded may be sufficient.

  In the case of a block copolymer having three or more polymer chains, the arrangement of these polymer chains may not be a linear arrangement but may be an arrangement having a branched structure. What is necessary is just to select the optimal thing in obtaining the shape of the target micro phase-separation structure.

  As the polymer chain constituting such a block copolymer, in addition to the polystyrene, polybutadiene, polymethyl methacrylate, for example, polyethylene oxide, polyhydroxystyrene, polyvinylpyridine, polydimethylsiloxane, polybutyl methacrylate, polybutyl acrylate, polyethylene , Polyisoprene, polyethylethylene, polyferrocenylsilane, polyferrocenyldimethylsilane and the like, but are not limited to this in the present invention.

  When a block copolymer is used, it is preferable to use molecules having a component ratio that forms a micelle structure or a cylinder structure on the substrate surface. As a result, it is possible to form circular dot-shaped recording portions that are separated from each other and regularly arranged.

  The block copolymer can be formed into a film by diluting with a suitable solvent such as benzene and toluene, and then by spin coating, dipping, spraying, ink jetting, or the like. However, in the present invention, the dilution solvent and the construction method are not particularly limited. Phase separation of the block copolymer into a highly self-organized regular array can be obtained by performing the following annealing treatment. As the annealing treatment, the block copolymer after film formation is maintained in a steady state at a glass transition temperature (Tg) or higher and a decomposition temperature (Td) or lower in a vacuum or in an inert gas atmosphere such as argon gas or nitrogen gas. Examples thereof include a method and a method of holding in a solvent atmosphere in which the block copolymer is dissolved. However, the present invention is not limited to this method.

  When using fine particles with a diameter of several nanometers to several tens of nanometers made of polymer, metal, etc., the solution in which the fine particles are dispersed is spread on the substrate on which the linear separation region is formed, dried, and the solvent is removed. By removing fine particles excessively adsorbed with a simple solvent, a self-organized ordered array can be produced. It is also possible to form a regular array by adsorbing the fine particles to the substrate by immersing the substrate in a solution in which the fine particles are dispersed for a certain period of time. However, the present invention is not limited to this method.

  When the block copolymer is selectively removed as described above to remove the micelle structure or the cylinder structure portion (island portion 802a) (FIG. 8F), the SOG (spin on glass) is removed after the selective removal. A film 803 is formed (FIG. 8G), and the self-organized material (sea-like portion) 802b and the linear separation regions 102a and 102b remaining by RIE are cut using the SOG 803 as a mask (FIG. 8H). Further, by cutting the underlying recording layer, a desired regularly arranged dot-shaped recording portion can be formed (FIG. 8I). Here, as an example, a method of inverting a pattern using SOG is given as an example, but the present invention is not limited to this method.

On the other hand, when the micelle structure or the cylinder structure portion is selectively removed from the block copolymer, or when fine particles having a diameter of several nm to several tens of nm made of polymer or metal are used, RIE or an appropriate solvent is used. After removing the control film, a desired regular array of dot-shaped recording portions can be formed by scraping the underlying recording layer by RIE or the like using the self-organizing material as a mask. In order to cut the recording layer with a higher aspect ratio, a hard mask layer such as SiO ₂ or Si is formed between the recording layer and the self-organizing material, and the regular arrangement pattern of the self-organizing material is hard masked by RIE or the like. It is also effective to process the recording layer after transfer to the layer. Since SiO ₂ , Si, and SOG can be etched with a high aspect ratio by RIE, the recording layer can be etched with a higher aspect ratio by using this as a mask. However, the present invention is not limited to this method.

  After the dot-shaped recording portion 105 is formed, the recording material of the dot-shaped recording portion 105 is covered with a non-recording material 804 and polished to produce a recording medium (FIG. 8I). Further, it is possible to use the dot-shaped recording portion as it is without coating or polishing, and the present invention is not limited to this method.

  As described above, an information recording medium having dot-shaped recording portions regularly arranged in a hexagonal lattice pattern at high density along the circumferential direction on a circular disk substrate can be obtained.

(Embodiment 2)
A pattern forming master having a concavo-convex shape may be produced by a method using a self-organizing material, and the pattern may be transferred to a disk substrate by a nanoimprint lithography method using this master. In this case, first, a control film 102 for forming a groove structure for controlling the arrangement of the self-organizing material or a linear separation region having a chemical pattern is formed on the substrate 901 serving as a master (FIG. 9). (A) (B)). However, the substrate serving as the master is not limited in the present invention. The linear separation regions 102a and 102b are patterned on the control film 102 by lithography (FIG. 9C). The patterning here is performed in the same manner as in the first embodiment. Self-assembled materials 802a and 802b are deposited in the plurality of cells 103 surrounded by the linear separation regions 102a and 102b or on the linear separation regions 102a and 102b, and are then regularly arranged by annealing or the like. (FIG. 9D).

  Thereafter, in the same manner as in the first embodiment, the substrate is etched by using the self-assembled material or the self-assembled material and the control film, or SOG substituted with the self-assembled material as a mask to form the master (see FIG. 9 (E) (F)). In order to increase the aspect ratio, a hard mask layer as described in Embodiment Mode 1 may be used, and the present invention is not limited to this method.

  A film 902 made of an appropriate resist material serving as a mask is formed on the disk substrate 101 on which a film to be the recording layer 801 is formed, and the master is pressed while being heated, irradiated with ultraviolet rays, or both (FIG. 9G). Then, the pattern is transferred to the resist (FIG. 9H). Based on the transferred pattern, a dot-shaped recording portion is formed by etching (FIG. 9I). In order to increase the aspect ratio, a hard mask layer as described in Embodiment Mode 1 may be used, and the present invention is not limited to this method. Thereafter, an information recording medium is manufactured in the same manner as in the first embodiment (FIG. 9J).

Example 1
An example of manufacturing an information recording medium according to the method of the present invention will be described.

A recording material having a film thickness of about 50 nm, here a Ge ₁₀ Sb ₉₀ film, which is a phase change material, was formed on a glass disk substrate. A resist having a novolac resin as a base resin was spin-coated on the Ge ₁₀ Sb ₉₀ film. The resist was processed by exposure and development with an aqueous solution of TMAH by photolithography, and a resist pattern corresponding to the separation region was formed by baking the resin at 150 ° C. to cure the resin. A solution in which only 2 parts by weight of polystyrene (PS) -polymethyl methacrylate (PMMA) block copolymer (molecular weight PS = 65000, PMMA = 13500) was dissolved in ethyl cellosolve acetate was prepared. The block copolymer was embedded in the cell by spin coating the solution onto the sample. The sample was annealed in vacuum at 150 ° C. for 30 hours to order the block copolymer. As a result, a structure in which island-like PMMA particles were surrounded by a sea-like PS portion was formed. This sample was subjected to RIE using CF ₄ gas at an output of 100 W, 30 sccm, and 0.1 Torr. Under this condition, PMMA was selectively etched, leaving a sea-like PS. Thereafter, SOG was formed, and ashing was performed using O ₂ gas to remove PS and the resist. Thereafter, the recording material was etched by performing Ar ion milling using SOG as a mask to obtain a dot-shaped recording portion of Ge ₁₀ Sb ₉₀ regularly arranged in a desired hexagonal lattice shape.

(Example 2)
Next, an example in which an information recording medium is manufactured by a nanoimprint lithography method using a master will be described. First, a SiO ₂ film having a thickness of about 50 nm was formed on a silicon disk substrate. A resist was spin-coated, and the SiO ₂ film was etched by photolithography and RIE until it reached the silicon substrate to form an isolation region that defined the cell. Thereafter, the resist pattern was removed by ashing. A block copolymer of polystyrene (PS) -polybutadiene (PB) block copolymer (molecular weight PS = 30000, PB = 120,000) in a cell is spin-coated and annealed to form a block copolymer. Were regularly arranged to form an island-shaped portion composed of PS and a sea-shaped portion composed of PB. The block copolymer was treated with ozone and then washed with water to remove PB, and then SOG was formed to fill the sea part. Thereafter, PS was removed by RIE, and the silicon substrate was etched using SiO ₂ and SOG as a mask to form a master having a hexagonal arrangement.

A Ge ₁₀ Sb ₉₀ film of 50 nm was formed on a glass disk substrate, and a resist was spin-coated. The above master was pressed against this glass disk substrate while being heated at 200 ° C., and then peeled off. Thereafter, the resist and the Ge ₁₀ Sb _{90 corresponding} to the concave portions are etched by Ar ion milling, and the remaining resist is removed by ashing, thereby obtaining a dot-shaped recording portion of Ge ₁₀ Sb ₉₀ regularly arranged in a hexagonal lattice shape. .

  The information recording medium and the method for manufacturing the information recording medium according to the present invention are useful for improving the recording density of the information recording medium.

DESCRIPTION OF SYMBOLS 101 Disc-shaped board | substrate 102 Control film | membrane 102a Linear separation area | region 102b along a track direction 102b Linear separation area | region crossing a track | truck 103 Cell 104 The angle (theta) which the both ends of the circular arc of the inner peripheral side of a cell and the center of a disk make
105 Dot-shaped recording part 106 Distance between closest dots a
107 Length of arc on the inner peripheral side of the cell 108 Length of arc on the outer peripheral side of the cell 109 Distance Δr from the arc on the inner peripheral side of the cell to the arc on the outer peripheral side
110 Arc on the inner circumference side of the cell 111 Arc on the outer circumference side of the cell 801 Recording layer 802a Self-organizing material (island-like part)
802b Self-assembled material (sea-like part)
803 SOG (spin on glass)
804 Non-recording material 901 Substrate serving as a master 902 Resist

Claims (14)

  A linear separation region along a concentric or spiral track direction formed on a disk-shaped substrate, a linear separation region crossing the track, a plurality of cells surrounded by these separation regions, and a lattice An information recording medium comprising a plurality of dot-shaped recording portions having an average value within a cell of the distance between centers of the closest ones, and a line separation region and cells along the track direction. The arc of the outer circumference of the cell (the arc of the inner circumference of the cell (hereinafter referred to as the arc of the inner circumference of the cell) and the line separation region along the track direction of the cell and the cell) Hereinafter, an information recording medium characterized in that the difference in length of the arc on the outer peripheral side of the cell is less than a / 2.   The information recording medium according to claim 1, wherein the plurality of dot-shaped recording portions form a hexagonal lattice.   The information recording medium according to claim 1, wherein a linear separation region crossing the track is formed so as to cross the track substantially perpendicularly.   4. The information recording medium according to claim 3, wherein a plurality of linear separation regions crossing the track are formed radially in a straight line from the inner periphery to the outer periphery of the disk-shaped substrate.   The linear separation region crossing the track is formed by a line segment, a broken line, or a curve along a hexagonal lattice that is expected to be formed when the self-organization phenomenon is used. An information recording medium according to any one of the above.   The information recording medium according to any one of claims 1 and 2, wherein a linear separation region crossing the track is formed so as to be approximately 60 ° or 120 ° with respect to the linear separation region along the track direction.   The relationship between the angle θ between the two points on both ends of the arc on the inner circumference side of the cell and the center of the disk and the distance Δr from the arc on the inner circumference side to the arc on the outer circumference side satisfies Δrθ <a / 2. The information recording medium according to claim 1, wherein a linear separation region is formed as described above.   A linear separation region formed on a substrate along a concentric or spiral track direction, a linear separation region crossing the track, and a plurality of cells surrounded by the separation regions, arranged in a lattice pattern And a pattern forming master having a plurality of dot-like irregularities such that the average value of the distance between the centers of the closest ones in the cell is a, the length of the arc on the inner peripheral side of the cell and the outer periphery of the cell A pattern forming master having a difference in arc length on the side of less than a / 2.   The pattern forming master according to claim 8, wherein the plurality of dot-like irregularities form a regular hexagonal lattice.   10. The pattern forming master according to claim 8, wherein a linear separation region that crosses the track is formed so as to cross the track substantially vertically.   The pattern forming master according to claim 10, wherein a plurality of linear separation regions crossing the track are formed radially in a straight line from the inner periphery to the outer periphery of the track.   The linear separation region that crosses the track is formed by a line segment, a broken line, or a curve along a hexagonal lattice that is expected to be formed when the self-organization phenomenon is used. The pattern forming master according to crab.   10. The pattern forming master according to claim 8, wherein the linear separation region crossing the track is formed to be approximately 60 ° or 120 ° with respect to the linear separation region along the track direction.   The relationship between the angle θ between the two points on both ends of the arc on the inner circumference side of the cell and the center of the disk and the distance Δr from the arc on the inner circumference side to the arc on the outer circumference side satisfies Δrθ <a / 2. The pattern forming master according to claim 8, wherein a linear separation region is formed as described above.