JP2005093045A - Manufacturing method of stamper and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a stamper for manufacturing a recording medium, in which making the recording medium large capacity can be realized by narrowing a track pitch using a simple process. <P>SOLUTION: A photoresist original disk 104, in which a heat accumulating layer 102 having thickness of L is formed on a substrate 101 and a photoresist layer 103, is formed on the heat accumulating layer is irradiated with a laser beam of a far ultraviolet region in a spiral or concentric form with a pitch smaller than the spot diameter of the laser beam, the photoresist layer is exposed, the photoresist layer is developed, and the photoresist original disk, in which a rugged pattern is formed is manufactured. A stamper, in which the rugged pattern of the photoresist original disk is transferred, is manufactured using the photoresist original disk in which the rugged pattern has been formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stamper and a method for manufacturing a recording medium. More specifically, the present invention relates to a recording medium manufacturing method capable of reducing the track pitch and increasing the capacity of the recording medium with a simple process. The present invention relates to a stamper and a recording medium manufacturing method.

  In recent years, in manufacturing an optical recording medium that is widely used as a recording medium, first, a stamper for manufacturing a substrate of the optical recording medium is manufactured.

  That is, first, a photoresist is coated on the surface of a precisely polished and cleaned glass substrate by spin coating to produce a photoresist master having a photoresist layer formed on the glass substrate. . Next, an intensity-modulated laser beam is focused on the photoresist layer according to a predetermined format, and the photoresist layer is exposed to form latent images such as pits and grooves in the photoresist layer. Further, by developing the photoresist layer, the portion where the latent image is formed is removed, and a photoresist master having a concavo-convex pattern such as pits and grooves formed on a glass substrate is produced. Next, the photoresist master on which the concavo-convex pattern is formed is plated, and then the plated portion is peeled off to produce a stamper on which the concavo-convex pattern is transferred.

  A substrate of the optical recording medium is manufactured using the stamper thus manufactured, and the optical recording medium is manufactured.

  In recent years, an increase in the capacity of optical recording media has been demanded, and in order to meet such demands, it is necessary to reduce the size of pits and grooves and the track pitch, and the laser beam is applied to the photoresist layer. It is necessary to reduce the spot size of the laser beam when condensed. Here, the spot size of the laser beam is proportional to a value λ / NA obtained by dividing the wavelength λ of the laser beam by the numerical aperture NA of the objective lens, and therefore, the laser beam spot size when the laser beam is condensed on the photoresist layer. In order to reduce the spot size, it is necessary to shorten the wavelength λ of the laser beam and increase the numerical aperture NA of the objective lens.

  However, since an objective lens having a numerical aperture of 0.90 or more is already used at present, the laser beam when the laser beam is focused on the photoresist layer by increasing the numerical aperture NA of the objective lens. It is difficult to reduce the spot size. On the other hand, when a laser beam in the ultraviolet region with a short wavelength λ is used, not only the cost of optical components is increased, but also the depth of focus is reduced, which makes it difficult to expose the photoresist layer with the laser beam. there were.

On the other hand, Japanese Patent Laid-Open No. 2002-334483 can form a groove that is thinner than the spot size of the laser beam focused on the photoresist layer, and forms a uniform pattern groove with a small track pitch. A method for manufacturing a photoresist master and a stamper that can be used is proposed. In this method, a lower layer made of a non-photosensitive water-soluble resin and an upper layer made of a photoresist are formed on a glass substrate, and an intermediate layer made of an inorganic material not mixed with the lower layer and the upper layer is formed between the lower layer and the upper layer. When the lower layer is etched by optical ozone ashing, the intermediate layer is not etched and serves as a cover. Therefore, the track pitch is narrowed and the height of the mask portion of the photoresist layer is increased. Even when the height is lowered, a stable uneven pattern having no collapse of the edge can be formed in the lower layer.
Japanese Patent Laid-Open No. 2002-334483

  However, the method disclosed in Japanese Patent Application Laid-Open No. 2002-334483 not only needs to form a lower layer, an intermediate layer, and an upper layer on a glass substrate, but also needs to perform an optical ozone ashing treatment. For example, there were problems that the number of processes increased and the cost was increased.

  Accordingly, it is an object of the present invention to provide a recording medium manufacturing stamper and a recording medium manufacturing method capable of realizing a large capacity recording medium by reducing the track pitch by a simple process. Is.

  As a result of intensive studies to achieve the object of the present invention, the present inventor has formed a heat storage layer having a thickness L on a substrate, and a photo resist layer formed on the heat storage layer. When L is less than 78 nm on the resist master, a laser beam in the far ultraviolet region is irradiated with an irradiation energy I satisfying −0.0101L + 1.639 ≦ I ≦ −0.0045L + 1.5507, and the photoresist layer is irradiated A laser beam spot is formed and the photoresist layer is exposed. When L is 78 nm or more, the irradiation energy I satisfying −0.0014L + 0.9581 ≦ I ≦ −0.000009L + 1.2723 and the far ultraviolet region When a laser beam spot is formed on the photoresist layer and the photoresist layer is exposed, the spot of the laser beam is irradiated. The central portion of the region of the photoresist layer exposed by preparative found that areas not dissolved by the developing solution are formed.

  Under such conditions, when the photoresist layer of the photoresist master is irradiated with a laser beam, a region that is not dissolved by the developer is formed in the central portion of the photoresist layer region exposed by the laser beam spot. The reason for this is not necessarily clear, but the intensity in the spot of the laser beam irradiated on the photoresist layer has a Gaussian distribution and the intensity is high in the central part. It is presumed that the resist layer is melted and denatured to form a region that is not dissolved by the developer.

  As a result of further research based on such knowledge, the present inventor has simplified irradiation by irradiating a laser beam spirally or concentrically on the photoresist layer at a pitch less than the spot diameter of the laser beam. With this process, a photoresist master having a fine concavo-convex pattern can be produced. Using the photoresist master having a fine concavo-convex pattern thus formed, a stamper is produced and a recording medium substrate is produced. Thus, it has been found that a stamper and a recording medium for manufacturing a recording medium capable of realizing a large capacity recording medium by narrowing a track pitch can be manufactured.

  The present invention is based on such knowledge. According to the present invention, the object of the present invention is to form a heat storage layer having a thickness L on a substrate, and form a photoresist layer on the heat storage layer. When L is less than 78 nm, the applied photoresist master has an irradiation energy I satisfying −0.0101L + 1.639 ≦ I ≦ −0.0045L + 1.5507 at a pitch less than the spot diameter of the laser beam and far ultraviolet rays. When the photoresist layer is exposed by irradiating a laser beam in a spiral or concentric manner and L is 78 nm or more, −0.0014L + 0.9581 ≦ I ≦ −0.0009L + 1.2723 is satisfied. The photo-resist is irradiated with a laser beam in the far ultraviolet region in a spiral shape or a concentric shape with an irradiation energy I at a pitch less than the spot diameter of the laser beam. Layer is exposed, the photoresist layer is developed to produce a photoresist master having a concavo-convex pattern, and the photoresist master having the concavo-convex pattern is used to form a photoresist master on the surface. This is achieved by a stamper manufacturing method, wherein a stamper to which the uneven pattern is transferred is manufactured.

  In the present invention, the thickness L of the heat storage layer is preferably set to 1 nm to 300 nm, and more preferably 50 nm to 200 nm.

  In this invention, Preferably, the thermal storage layer contains the organic compound which has a light absorptivity.

  In the present invention, the photoresist layer is preferably formed of a photoresist having a novolac resin as a skeleton resin.

  In the present invention, the substrate is preferably formed of a glass substrate.

  The object of the present invention is also that when a heat storage layer having a thickness L is formed on a substrate, and a photoresist master having a photoresist layer formed on the heat storage layer, when L is less than 78 nm, The irradiation energy I satisfying 0.0101L + 1.639 ≦ I ≦ −0.0045L + 1.5507 is irradiated with a laser beam in the far ultraviolet region at a pitch less than the spot diameter of the laser beam spirally or concentrically, When the photoresist layer is exposed and L is 78 nm or more, the irradiation energy I satisfying −0.0014L + 0.9581 ≦ I ≦ −0.000009L + 1.2723 is obtained at a pitch less than the laser beam spot diameter. Irradiate a laser beam in the ultraviolet region in a spiral or concentric manner, expose the photoresist layer, develop the photoresist layer, A photoresist master having a turn formed thereon is prepared, and using the photoresist master having the concavo-convex pattern formed thereon, a stamper on which the concavo-convex pattern of the photoresist master is transferred is prepared. This is achieved by a method for producing a recording medium, wherein a substrate for a recording medium having the concavo-convex pattern of the stamper transferred to the surface is produced using the stamper on which is formed.

  In the present invention, the thickness L of the heat storage layer is preferably set to 1 nm to 300 nm, and more preferably 50 nm to 200 nm.

  In this invention, Preferably, the thermal storage layer contains the organic compound which has a light absorptivity.

  In the present invention, the photoresist layer is preferably formed of a photoresist having a novolac resin as a skeleton resin.

  In the present invention, the substrate is preferably formed of a glass substrate.

  According to the present invention, it is possible to provide a recording medium manufacturing stamper and a recording medium manufacturing method capable of realizing a large recording medium capacity by narrowing a track pitch by a simple process. .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  1 to 7 are process diagrams of a stamper manufacturing method for manufacturing a disk-shaped optical recording medium according to a preferred embodiment of the present invention.

  In producing an optical recording medium, first, a photoresist master is produced.

  That is, as shown in FIG. 1, first, a precisely polished disc-shaped glass substrate 101 is prepared, a coupling agent is applied to the surface of the glass substrate 101, and further, an organic compound having light absorption properties. Is applied uniformly by a spin coating method to form a coating film.

  Thereafter, the coating film is baked at a predetermined temperature for a predetermined time, and the heat storage layer 102 having a predetermined thickness L is formed on the glass substrate 101.

  Here, the thickness of the heat storage layer 102 is preferably set to 1 nm to 300 nm, and more preferably 50 nm to 200 nm.

  As the organic compound having light absorptivity contained in the heat storage layer 102, it is preferable to use at least one compound selected from the group consisting of a photoinitiator, a photoinitiator assistant, and a dye. Generally, a photoinitiator is an organic compound that is used together with a photocurable resin and generates radicals by absorbing light such as ultraviolet rays. In addition, the photoinitiator does not activate itself by ultraviolet irradiation, but when used in combination with the photoinitiator, the initiation of the reaction is promoted and the curing reaction is more efficient than when the photoinitiator is used alone. Can be advanced.

  The photoinitiator generates radicals and decomposes, but since the photoinitiator is stable, it is more preferable to use a photoinitiator in combination. As the photoinitiator auxiliary, aliphatic or aromatic amines are mainly used. As photoinitiators, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy) It is preferable to use at least one compound selected from isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate and the like, and among these, it is particularly preferable to use a benzophenone compound.

  In preparing the coating liquid for forming the heat storage layer 102, an organic compound having a light absorptivity is dissolved in a solvent. At this time, a thermally crosslinkable compound can be contained as necessary. Furthermore, if necessary, various additives such as an adhesion assistant, a light absorber, and a surfactant that improve the adhesion to the photoresist layer may be added to the coating solution.

  Next, a photoresist having a skeleton resin such as a novolac resin or polystyrene resin is uniformly applied to the surface of the heat storage layer 102 by a spin coating method, and a photoresist layer having a predetermined thickness is formed on the heat storage layer 102. 103 is formed.

  The thickness of the photoresist layer 103 is not particularly limited, but is set in consideration of the height of the groove to be finally formed on the substrate of the optical recording medium described later.

  Thus, a photoresist master 104 in which the heat storage layer 102 and the photoresist layer 103 are laminated on the glass substrate 101 is manufactured.

  Next, as shown in FIG. 2, the photoresist master 104 is irradiated with a laser beam 120 to expose the photoresist layer 103.

  As the laser beam 120, a laser beam in the far ultraviolet region, particularly a laser beam 120 having a wavelength λ of 248 nm to 266 nm is used.

  As shown in FIG. 2, the laser beam 120 is focused on the photoresist layer 103 by the objective lens 130, and the photoresist layer 103 is exposed by the laser beam 120.

  In the present embodiment, when the thickness L of the heat storage layer 102 of the photoresist master 104 is less than 78 nm, the laser beam is irradiated with an irradiation energy I satisfying −0.0101L + 1.639 ≦ I ≦ −0.0045L + 1.5507. 120 is irradiated to the photoresist layer 103 of the photoresist master 104, and when the thickness L of the heat storage layer 102 of the photoresist master 104 is 78 nm or more, −0.0014L + 0.9581 ≦ I ≦ −0.0009L + 1. .2723 is irradiated with the laser beam 120 to the photoresist layer 103 of the photoresist master 104.

  According to the inventor's research, a heat storage layer 102 having a thickness L is formed on a substrate 101, and a photoresist master 104 in which a photoresist layer 103 is formed on the heat storage layer 102, the heat storage layer 102 is formed. When the thickness L is less than 78 nm, the laser beam 120 in the far ultraviolet region is irradiated with the irradiation energy I satisfying −0.0101L + 1.639 ≦ I ≦ −0.0045L + 1.5507, and the photoresist layer 103 is irradiated on the photoresist layer 103. When a spot of the laser beam 120 is formed to expose the photoresist layer 103, and the thickness L of the heat storage layer 102 is 78 nm or more, −0.0014L + 0.9581 ≦ I ≦ −0.000009L + 1.2723 is satisfied. A laser beam 120 in the far ultraviolet region is irradiated with the irradiation energy I, and a spot of the laser beam 120 is formed on the photoresist layer 103. When the photoresist layer 103 is exposed, a region 103Y that is not dissolved by the developer is formed in the central portion of the region 103X of the photoresist layer 103 exposed by the spot of the laser beam 120. Has been issued.

  Under such conditions, when the laser beam 120 in the far ultraviolet region is irradiated onto the photoresist layer 103 of the photoresist master 104, the central portion of the region 103X of the photoresist layer 103 exposed by the spot of the laser beam 120 is applied. The reason why the region 103Y not dissolved by the developer is formed is not necessarily clear, but the intensity in the spot of the laser beam 120 irradiated to the photoresist layer 103 has a Gaussian distribution, and the intensity is in the central portion. Therefore, it is presumed that in the central portion of the spot of the laser beam 120, the photoresist layer 103 is melted and deteriorated to form a region 103Y that is not dissolved by the developer.

  Specifically, the photoresist master 104 is set on a turntable (not shown) of an exposure apparatus, and the irradiation position of the laser beam 120 is shifted in the radial direction of the photoresist master 104 while rotating the turntable. Let As a result, the laser beam 120 is spirally irradiated on the surface of the photoresist layer 103 of the photoresist master 104, and the photoresist layer 103 is exposed spirally.

  In this embodiment, with the rotation of the photoresist master 104, the irradiation position of the laser beam 120 is shifted in the radial direction of the photoresist master 104 at a pitch less than the spot diameter 103X of the laser beam 120. It is configured.

  As a result, as shown in FIG. 2, the region 103 </ b> Z on both sides of the region 103 </ b> Y of the photoresist layer 103 irradiated with the laser beam 120 is irradiated with the laser beam 120 again after one rotation of the photoresist master 104. Then, a region 103Y that is not dissolved by the developer is formed on the opposite side of the region 103Z from the side where the region Y is already formed, and the region 103Z is formed adjacent to the region 103Y.

  Thus, when the entire surface of the photoresist master 104 is exposed by the laser beam 120, the regions 103Y and the regions 103Z are alternately formed along the radial direction on the photoresist master 104.

  Therefore, by exposing the photoresist master 104 with the laser beam 120 while shifting the irradiation position of the laser beam 120 at a pitch less than the spot diameter 103X of the laser beam 120, the pitch less than the spot diameter of the laser beam 120 is obtained. Thus, it is possible to form the region 103Y that is not dissolved by the developer in the photoresist master 104.

  Next, as shown in FIG. 3, the entire surface of the photoresist layer 103 is exposed. When exposing the entire surface of the photoresist layer 103, a UV lamp 121 having a wavelength of 254 nm is used.

  Further, the photoresist master 104 is developed. As a result, as shown in FIG. 4, the photo resist layer 103 is removed from the photo resist master 104 except for the region 103 Y that is not dissolved by the developer, and the photothermographic pattern 102 is formed on the surface of the heat storage layer 102. A resist master 104 is produced.

  Next, the photoresist master 104 is subjected to electroless plating, and as shown in FIG. 5, an electroless nickel layer 105 is formed on the concavo-convex pattern.

  Further, using the electroless nickel layer 105 as an electrode, the photoresist master 104 is subjected to an electrolytic plating process, and an electrolytic nickel layer 106 is formed on the electroless nickel layer 105 as shown in FIG. The

  Next, the laminate in which the heat storage layer 102, the photoresist layer 103, the electroless nickel layer 105, and the electrolytic nickel layer 106 are laminated is peeled off from the glass substrate 101. Further, the laminated body peeled off from the glass substrate 101 is a strong alkali. The photoresist layer 103 and the heat storage layer 102 are dissolved and removed by being immersed in the liquid, and the electroless nickel layer 105 and the electrolytic nickel layer 106 are laminated as shown in FIG. Then, the stamper 107 to which the uneven pattern of the photoresist master 104 is transferred is produced.

  Here, the concavo-convex pattern formed on the stamper 107 corresponds to the negative pattern of the concavo-convex pattern of the photoresist master 104 because the concavo-convex pattern of the photoresist master 104 is transferred.

  8 and 9 are process diagrams of a method for manufacturing an optical recording medium according to a preferred embodiment of the present invention.

  In manufacturing the optical recording medium, first, as shown in FIG. 8, after the stamper 107 is set in the injection mold 201, a resin such as polycarbonate is poured into the mold 201. Cured.

  As a result, the concave / convex pattern of the stamper 106 is transferred to the resin, and the substrate 108 for an optical recording medium having the concave / convex pattern of the stamper 106 transferred to the surface is manufactured.

  Furthermore, as shown in FIG. 9, an information layer 109 including a dielectric film, a recording film, a reflective film, a protective film, and the like is formed on the surface of the substrate 108 for an optical recording medium, so that write-once or rewritable light A recording medium 110 is manufactured, and a multilayer film 109 including a reflective film, a protective film, and the like is formed, and a ROM type optical recording medium 110 is manufactured.

  According to the present embodiment, the substrate 101, the heat storage layer 102 formed on the surface of the substrate 101, the photoresist master 104 including the photoresist layer 103 formed on the surface of the storage heat layer 102, and the exposure apparatus The irradiation position of the laser beam 120 is shifted in the radial direction of the photoresist master 104 at a pitch smaller than the spot diameter 103X of the laser beam 120 while rotating the turntable, and the far ultraviolet is rotated. The photoresist layer 103 of the photoresist master 104 is exposed by the laser beam 120 in the region. When the thickness L of the heat storage layer 102 is less than 78 nm when the photoresist layer 103 is exposed, −0.0101L + 1 639 ≦ I ≦ −0.0045L + 1.5507, the irradiation energy I satisfying When the photoresist layer 103 is irradiated with the beam 120, and the thickness L of the heat storage layer 102 is 78 nm or more, the irradiation energy I satisfies −0.0014L + 0.9581 ≦ I ≦ −0.000009L + 1.2723, The photoresist layer 103 is irradiated with the laser beam 120 to form a region 103Y that is not dissolved by the developer in the central portion of the region 103X of the photoresist layer 103 exposed by the spot of the laser beam 103. Since the concavo-convex pattern is formed on the surface, the region 103Y that is not dissolved by the developer can be formed on the photoresist master 104 at a pitch less than the spot diameter of the laser beam 120. Therefore, the wavelength of the laser beam 120 A laser beam 120 having a short λ or a numerical aperture N A stamper 107 that can realize a large capacity of the optical recording medium 110 by reducing the track pitch by a simple process without reducing the spot size of the laser beam by using the objective lens 130 having a large A. This makes it possible to manufacture a large-capacity optical recording medium 110.

  The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above-described embodiment, after exposing the photoresist layer 103 of the photoresist master 104 with the laser beam 120 in the far ultraviolet region, the entire surface of the photoresist layer 103 is applied using the UV lamp 121 having a wavelength of 254 nm. Although the exposure is performed, it is not always necessary to expose the entire surface of the photoresist layer 103 of the photoresist master 104 after the exposure with the laser beam 120 in the far ultraviolet region.

  In the above embodiment, the optical recording medium 110 is manufactured using the stamper 107. However, the recording medium of the present invention is not limited to the optical recording medium. Can also be applied to the production of magnetic recording media such as discrete track media and magneto-optical recording media. Furthermore, the recording medium is not limited to a disk shape, and may be a card-type recording medium, and the present invention is also applicable when manufacturing a recording medium having concentric tracks or linear tracks. can do.

FIG. 1 is a process diagram of a stamper manufacturing method according to a preferred embodiment of the present invention. FIG. 2 is a process diagram of a stamper manufacturing method according to a preferred embodiment of the present invention. FIG. 3 is a process diagram of a stamper manufacturing method according to a preferred embodiment of the present invention. FIG. 4 is a process diagram of a stamper manufacturing method according to a preferred embodiment of the present invention. FIG. 5 is a process diagram of a stamper manufacturing method according to a preferred embodiment of the present invention. FIG. 6 is a process diagram of a stamper manufacturing method according to a preferred embodiment of the present invention. FIG. 7 is a process diagram of a stamper manufacturing method according to a preferred embodiment of the present invention. FIG. 8 shows the steps of a method for manufacturing an optical recording medium according to a preferred embodiment of the present invention. FIG. 9 shows the steps of a method for manufacturing an optical recording medium according to a preferred embodiment of the present invention.

Explanation of symbols

101 Glass substrate 102 Thermal storage layer 103 Photoresist layer 103X Laser beam spot 103Y Region of the photoresist layer not dissolved by the developer 104 Photo resist master 105 Electroless nickel layer 106 Electrolytic nickel layer 107 Stamper 108 Substrate 109 for optical recording medium Information Layer (multilayer film)
110 Optical Recording Medium 120 Laser Beam 121 UV Lamp 201 Injection Mold

Claims (8)

A heat storage layer having a thickness L is formed on the substrate, and on a photoresist master having a photoresist layer formed on the heat storage layer, when L is less than 78 nm, −0.0101L + 1.639 ≦ I ≦ The photoresist layer is exposed by irradiating a laser beam in the far ultraviolet region spirally or concentrically with an irradiation energy I satisfying −0.0045L + 1.5507 at a pitch less than the spot diameter of the laser beam, When L is 78 nm or more, a laser beam in the far-ultraviolet region is spirally irradiated with an irradiation energy I satisfying −0.0014L + 0.9581 ≦ I ≦ −0.000009L + 1.2723 at a pitch less than the spot diameter of the laser beam. The photoresist layer is exposed to light, and the photoresist layer is developed to form a photolithographic pattern having a concavo-convex pattern. To produce a resist master, the concavo-convex pattern using the photoresist master disk is formed, on the surface, a manufacturing method of a stamper for the uneven pattern of the photoresist master is characterized in that to produce the stamper has been transferred. 2. The stamper manufacturing method according to claim 1, wherein a thickness L of the heat storage layer is set to 1 nm to 300 nm. 3. The stamper manufacturing method according to claim 2, wherein a thickness L of the heat storage layer is set to 50 nm to 200 nm. The substrate is formed of a glass substrate, the heat storage layer includes an organic compound having a light absorption property, and the photoresist layer is formed of a photoresist having a novolac resin as a skeleton resin. The method for manufacturing a stamper according to any one of claims 1 to 3. A heat storage layer having a thickness L is formed on the substrate, and on a photoresist master having a photoresist layer formed on the heat storage layer, when L is less than 78 nm, −0.0101L + 1.639 ≦ I ≦ The photoresist layer is exposed by irradiating a laser beam in the far ultraviolet region spirally or concentrically with an irradiation energy I satisfying −0.0045L + 1.5507 at a pitch less than the spot diameter of the laser beam, When L is 78 nm or more, a laser beam in the far-ultraviolet region is spirally irradiated with an irradiation energy I satisfying −0.0014L + 0.9581 ≦ I ≦ −0.000009L + 1.2723 at a pitch less than the spot diameter of the laser beam. The photoresist layer is exposed to light, and the photoresist layer is developed to form a photolithographic pattern having a concavo-convex pattern. A stamper having a concavo-convex pattern formed thereon is prepared by using the photoresist master having the concavo-convex pattern formed thereon to produce a stamper having the concavo-convex pattern of the photoresist master transcribed on the surface. A method for producing a recording medium, comprising: producing a substrate for a recording medium on which the uneven pattern of the stamper is transferred. 6. The method of manufacturing a recording medium according to claim 5, wherein a thickness L of the heat storage layer is set to 1 nm to 300 nm. The method for manufacturing a recording medium according to claim 6, wherein a thickness L of the heat storage layer is set to 50 nm to 200 nm. The substrate is formed of a glass substrate, the heat storage layer includes an organic compound having a light absorption property, and the photoresist layer is formed of a photoresist having a novolac resin as a skeleton resin. The method for manufacturing a recording medium according to claim 5.

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