JP2008226287A - Stamper for optical disk and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a stamper for an optical disk by which a projecting part is formed by only performing condensing and radiating a laser beam, and a development process after condensing and irradiating the laser beam is not needed. <P>SOLUTION: When the laser beam is condensed and irradiated on a phase change layer consisting essentially of a sulfide or an oxide of a transition metal or a mixture thereof, an irradiated region is phase-changed from an amorphous state to a crystalline state and the projecting part is formed by volume increase accompanying the phase change. Thereby, the stamper for the optical disk is formed by forming at least the phase change layer consisting essentially of the sulfide or the oxide of the transition metal or the mixture thereof on a flat substrate and condensing and irradiating the laser beam on the phase change layer corresponding to a signal pattern of the optical disk. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical disc stamper used for producing an optical recording medium such as an optical disc for recording information at high density, and a method for producing the same.

  Today, semiconductor devices, optical devices, magnetic devices, etc. are microfabricated by photolithography technology, and in order to achieve high density and high precision microfabrication, energetic research on light sources, resist materials, and micropattern formation methods Development is underway.

  The fine pattern formation technology by photolithography technology includes various devices such as semiconductor devices such as DRAM and CPU, magnetic devices such as magnetic heads, display devices such as liquid crystal, and optical devices such as optical recording media and light modulation elements. Wide range of production.

  In general, a fine pattern forming method using a photolithography technique is to form various patterns by exposure and development of a resist layer provided on a substrate, and always includes a development processing step.

  A conventional method for forming a fine pattern will be further described by taking an optical disk as an example. An optical disk used as an information recording medium has various formats such as MD, MO, DVD, Blu-ray Disk (registered trademark), and is properly used depending on the application. An optical disc stamper used in any format is generally manufactured by injection molding of a resin material.

  In order to achieve high density optical discs, miniaturization of guide grooves and pre-pits (sometimes referred to simply as pits) formed on an optical disc substrate is being promoted. Fine patterns such as guide grooves and pre-pits of the optical disk substrate are formed by transferring from a corresponding stamper. The photolithography technique described above is used to form this stamper.

  For example, a master stamper for an optical disk substrate is manufactured by condensing and irradiating laser light onto an organic photoresist coated on a glass substrate and exposing and developing the photoresist.

  A metal thin film such as nickel (Ni) or cobalt (Co) is vapor-deposited on this master stamper, a Ni metal electroplating layer is formed using this thin film as an electrode, and this plating layer is peeled off to form a stamper. Then, a resin such as polycarbonate is injection-molded in a mold provided with this stamper to obtain an optical disk substrate having the stamper surface unevenness transferred thereon.

  As described above, the mastering process requires a lot of manufacturing steps, and therefore takes a long time. Furthermore, complicated management operations such as management of resist solution (developer) and concentration management of plating solution are required.

  On the other hand, in Patent Document 1, a phase change metal film is deposited on the photocurable resin layer on which the pregroove is formed by vapor deposition or the like, and a laser beam is irradiated on the metal film to form a convex pattern. However, it is disclosed that this is used as a stamper. That is, by not performing development or plating, management of the resist solution, management of the concentration of the plating solution, and the like become unnecessary.

  On the other hand, when increasing the density, if the wavelength of the laser beam is λ and the numerical aperture of the objective lens that collects the laser beam is NA, the diameter of the spot of the focused laser beam (hereinafter referred to as a light spot) is: It becomes approximately 0.8λ / NA. In order to miniaturize the guide grooves and pre-pits of the optical disc, it is necessary to reduce the diameter of the light spot. To that end, it is necessary to shorten the wavelength λ and increase the NA.

  However, NA of 0.9 or more which is close to the upper limit has already been used, and it is practically difficult to reduce the light spot diameter by further increasing NA. In addition, it is conceivable to set λ to an ultraviolet region shorter than the current state, but if it is an ultraviolet region, the cost of optical components will increase, and in addition, the depth of focus will be reduced, and the conditions of the master exposure machine will become more severe. End up.

  Therefore, in order to improve the processing accuracy while using an existing exposure apparatus and light source, a method using an inorganic resist material that enables heat mode recording instead of conventional photon mode recording has been attempted. Patent Document 2 discloses an inorganic resist material containing an incomplete oxide of a transition metal and a fine pattern forming method using the same.

The fine pattern forming method of Patent Document 2 will be described below. Using an incomplete oxide of a transition metal such as WO _x (0.1 <x <0.75) as a resist material, exposure is performed by irradiating a laser beam having a wavelength of 405 nm according to recorded information. Thereafter, when development is performed using a tetramethylammonium hydroxide solution as an alkali developer, an uneven pattern corresponding to the recorded information is formed because there is an etching difference between the exposed portion and the unexposed portion. Since the inorganic resist has a low molecular weight and a clear pattern can be obtained at the boundary between the exposed portion and the unexposed portion, high-precision fine processing is achieved as compared with the organic resist.
Japanese Patent Laid-Open No. 4-82035 JP 2003-315988 A

  However, in the method described in Patent Document 1, it is indispensable that a pregroove is formed in advance on the substrate, and it is formed only from phase pits in a recess having no groove such as CD-ROM, CD, and DVD-ROM. There is a problem that it cannot be applied to the production of a conventional optical disc. In addition, since a metal film is used, a large amount of laser power is required for irradiation, and there is a problem that pits cannot be formed at a high linear velocity.

  Further, the method proposed in Patent Document 2 also has a problem that a developing step with a developer is necessary after laser irradiation, which requires management of the developer and treatment of waste liquid.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method of manufacturing an optical disc stamper that does not require a development processing step using a relatively inexpensive manufacturing apparatus. is there.

  Therefore, as a result of repeated studies, the present inventors formed a phase change layer mainly composed of a transition metal sulfide or oxide or a mixture thereof on a flat substrate, and the phase change. It has been found that when a laser beam is focused and irradiated on the layer, a convex portion is formed in the irradiated region. Then, it was found that the convex portion formed in this way is a fine pattern that can be used as an optical disc stamper. In other words, the present inventors have invented a method of manufacturing an optical disc stamper that can form a convex portion only by focused irradiation and does not require development processing after focused irradiation.

That is, the optical disc stamper according to the present invention is
An optical disc stamper having a convex portion corresponding to a signal pattern of an optical disc,
Having a phase change layer mainly composed of at least a transition metal sulfide or oxide or a mixture thereof on a flat substrate;
The crystal layer of the phase change layer exists in the convex portion, and the amorphous layer of the phase change layer exists in the other region.

An optical disc stamper manufacturing method according to the present invention includes:
Forming a phase change layer mainly composed of at least a transition metal sulfide or oxide or a mixture thereof on a flat substrate;
The phase change layer is focused and irradiated with a laser beam corresponding to the signal pattern of the optical disc, and a convex portion is formed in the irradiated region.

  The manufacturing method of the optical disk stamper according to the present invention can form the convex portion only by the focused irradiation, and does not require the development processing after the focused irradiation.

  Hereinafter, an optical disk stamper and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of a master disc of an optical disc stamper used for producing an optical disc stamper according to the present invention. A phase change layer 102 is formed on a substrate 101.

  As a material of the substrate 101, for example, quartz glass, metal, polyester, acrylic resin, polycarbonate resin, olefin resin, epoxy resin, or the like can be used.

  The phase change layer 102 is mainly composed of a transition metal sulfide or oxide, or a mixture thereof. For example, the phase change layer is formed using a transition metal sulfide such as ZnS, a transition metal oxide such as MoO, WO, ZnO, MnO, AgO, or CoO, or a mixture thereof as a main component. Among these, it is more preferable that ZnS, WO, and MoO are the main components from the viewpoint of volume increase accompanying the phase change.

  Here, the transition metal oxide includes an incomplete oxide shifted in a direction in which the oxygen content is smaller than the stoichiometric composition corresponding to the valence that the transition metal can take.

  The phase change layer 102 can be formed by a conventionally known method such as sputtering, vapor deposition, or CVD. For example, a phase change layer made of MoO, WO, or ZnO can be formed by reactive sputtering in a mixed atmosphere of Ar and oxygen using Mo, W, Zn, or the like made of a simple substance as a sputtering target. At this time, it is also possible to control the degree of oxidation of the incomplete oxide by changing the oxygen gas concentration. Usually, when a film is formed by a sputtering method, an amorphous state is obtained.

Further, from the viewpoint of stabilization, the phase change layer 102 may be added with an oxide such as SiO ₂ that has been conventionally used as a stabilizing additive. In this case, the film can be formed by conventional means such as sputtering.

  The thickness of the phase change layer 102 is not particularly limited, but is preferably 20 nm to 500 nm, and more preferably 30 nm to 300 nm in order to form a convex portion having a height preferable for information recording.

  Next, when the phase change layer of the master disc of the optical disc stamper is focused and irradiated with laser light, a convex portion is formed in the irradiation region as shown in FIG. 2, and the optical disc stamper can be manufactured. Since the convex portion can be formed only by the focused irradiation, the development processing after the focused irradiation is unnecessary.

  The reason why the convex portions are formed will be described below with reference to FIGS. When the phase change layer 102 is focused and irradiated with laser light, the irradiation region changes from an amorphous state to a crystalline state. If the density is different between the amorphous state and the crystalline state, a volume increase occurs due to a phase change, and a convex portion is formed in a portion that is irradiated and becomes a crystalline state. A portion in which a crystal state is formed (a portion where a convex portion is formed) is shown as a crystal layer 103 in FIG. In addition, in the phase change layer 102 after the focused irradiation, a region other than the crystal layer 103 is shown as an amorphous layer 104 in FIG. That is, in the phase change layer 102 after the focused irradiation, the convex portion is a crystalline layer, and the other region is an amorphous layer.

  Further, when quartz glass, metal, or the like is used as the substrate, these have high thermal conductivity, so that the light energy required for condensing and irradiating laser light to raise the temperature to the convex formation temperature increases. Therefore, as shown in FIG. 3, by providing an intermediate layer 105 made of a material having a lower thermal conductivity than the substrate between the phase change layer (phase change layer) and the substrate, heat dissipation to the substrate can be reduced. Can be prevented.

As the intermediate layer 105, an acrylic resin, an olefin resin, and a resin that can be cured by ultraviolet irradiation can be used in addition to the polycarbonate resin conventionally used for optical disks. For example, a resin material such as an epoxy acrylate resin, a urethane acrylate resin, or a silicon acrylate resin is preferably used. In addition, inorganic materials such as amorphous silicon, silicon dioxide (SiO ₂ ), silicon nitride (SiN), and alumina (Al ₂ O ₃ ) can also be used.

  The intermediate layer 105 can be formed by a conventional means such as a spin coat method.

  The thickness of the intermediate layer 105 is not particularly limited, but is preferably 0.1 μm to 70 μm, more preferably 0.5 μm to 50 μm, in order to prevent heat dissipation of the phase change layer. .

  Further, a phase change layer (projection forming layer) made of a transition metal sulfide or oxide generally has a low absorption rate of ultraviolet light or visible light. For this reason, the light energy required to raise the temperature to the temperature at which the convex portions are formed by condensing and irradiating the laser light may increase. Therefore, a light absorption layer made of a material having a high absorption rate of ultraviolet light or visible light can be provided in contact with the phase change layer (convex portion forming layer).

  The light absorption layer may be provided between the phase change layer and the substrate or on the opposite side of the substrate as long as it is in contact with the phase change layer. Also, as shown in FIG. 4, the phase change layer is composed of two layers, a phase change layer on the substrate side (first phase change layer 106) and a phase change layer on the surface side (second phase change layer 107). Alternatively, the light absorption layer 108 may be formed. Although the intermediate layer 105 shown in FIG. 3 is not provided in FIG. 4, the intermediate layer 105 may be provided on the substrate side as shown in FIG.

  Further, the light absorption layer may have a laminated structure formed of a plurality of layers in addition to a single light absorption layer as shown in FIGS. For example, as shown in FIG. 6, each layer can be provided in the order of a first phase change layer 106, a first light absorption layer 109, a second light absorption layer 110, and a second phase change layer 107.

  The material of the light absorption layer may be any material as long as it has sufficient absorption at the wavelength of the laser light to be used and does not hinder volume change in the phase change layer. Preferably, nitrides such as SiN, AlN, and GeN, oxides such as SiO, AlO, and TaO, oxynitrides such as SiON and AlON (all non-stoichiometric compositions), or a mixture thereof can be used. . In particular, Al or Si nitride, oxide, oxynitride or a mixture thereof is preferable. For example, in the case of a stacked structure as shown in FIG. 6, the first light absorption layer 109 mainly composed of Al nitride, oxide, oxynitride, or a mixture thereof, and Si nitride, oxide In addition, a stacked structure of the second light absorption layer 110 containing oxynitride or a mixture thereof as a main component can be obtained. Moreover, it can be set as the structure where the lamination order from the board | substrate side of these 1st light absorption layers and 2nd light absorption layers was reversed.

  The light absorption layer can be formed over the substrate 101 by a sputtering method, a plasma CVD method, or the like. For example, SiN, AlN, SiO, AlO, SiON, AlON, or a mixture thereof can be selected as a sputtering target, and a film can be formed by sputtering. Further, for example, it can be formed by reactive sputtering using Si or Al as a target and using a mixed gas of Ar gas, oxygen and / or nitrogen.

  Further, if the light absorption layer is too thick, the formation of the convex portion of the phase change layer 106 on the substrate side is hindered, and if it is too thin, light cannot be sufficiently absorbed. Therefore, the thickness is preferably 3 nm to 50 nm, and preferably 5 nm to 20 nm. More preferably.

  By using the stamper thus formed as a master stamper, a metal material such as Ni is deposited on the surface of the master stamper by a plating method or the like, so that a mother stamper having a convex pattern transferred thereon can be manufactured. Furthermore, the mother stamper can be plated to produce a molding stamper having a convex pattern. It is also possible to manufacture a transparent resin stamper by injection molding of a resin material using a mother stamper, and transfer the pattern to an optical disk having a multilayer structure.

  An optical disc stamper and a manufacturing method thereof according to an embodiment of the present invention will be described below with reference to the drawings.

(Example 1)
In Example 1, a master disc of an optical disc stamper having the configuration shown in FIG. 3 was produced. First, on the flat quartz glass substrate 101 having an outer diameter of 130 mm and a thickness of 2 mm, 50 μm of an acrylic ultraviolet curable resin was formed as an intermediate layer 105 by a spin coating method.

  Next, an incomplete oxide of W was formed on the intermediate layer 105 to form the phase change layer 102, and an optical disc stamper master was manufactured. The phase change layer 102 made of an incomplete W oxide was formed by reactive sputtering using a W metal target by introducing a mixed gas of argon and oxygen into a sputtering apparatus evacuated to a predetermined degree of vacuum. At that time, the flow rates of argon and oxygen were 20 sccm and 5 sccm, respectively.

  The film thickness of the produced phase change layer 102 made of an incomplete oxide of W was 200 nm, the absorbance at a wavelength of 405 nm was 20%, and the transmittance was 60%. The absorptance represents the rate of absorption by the film when the incident light energy is 100%, and the transmittance represents the rate of transmission through the film.

  Next, the phase change layer 102 is focused and irradiated with laser light corresponding to the signal pattern of the optical disc from the film surface side using a general exposure apparatus as disclosed in FIG. did. At this time, the wavelength of the laser beam was 405 nm, the exposure condition was a linear velocity of 4.92 m / s, and the laser power was 8 mW.

  As a result, a convex portion corresponding to the irradiated laser power, that is, corresponding to the recorded information was formed. The height of the convex portion was about 50 nm.

  When cross-sectional observation and electron beam diffraction were performed with a transmission electron microscope (TEM), it was confirmed that the region where the convex portion was formed was in a crystalline state, and the region where the convex portion was not formed was in an amorphous state.

  The surface of the optical disk stamper (master) thus obtained was subjected to a conductor treatment with a Ni film, which is performed in a conventional stamper manufacturing process. After that, a Ni film was deposited on the pattern surface of the optical disk stamper by plating, and this was peeled off from the optical disk stamper, followed by predetermined processing to obtain a mother stamper to which the convex pattern of the optical disk stamper was transferred. . Using this mother stamper, a molding stamper having convex portions was produced by a plating method. An optical disk substrate (PC) having an outer diameter of 120 mm was produced by injection molding using this molding stamper.

  An optical disk having a diameter of 120 mm was obtained by forming a reflective film made of Ag alloy and a protective film having a thickness of 0.1 mm on the uneven surface of the substrate of the optical disk.

  When the uneven surface of this optical disk is observed with an SEM, 150 nm long pits, 130 nm wide linear pits and the like are formed in a state corresponding to an actual signal pattern, and the optical disk has a recording capacity of 25 GB. It was confirmed.

Next, the optical disk was read out under the following conditions, the RF signal was obtained as an eye pattern, and signal evaluation was performed.
・ Tracking servo: Push-pull method ・ Modulation: 17PP
-Bit length: 112nm
・ Track pitch: 320nm
Read line speed: 4.92 m / s
・ Reading irradiation power: 0.35mW
The jitter value in the eye pattern subjected to the limit equalization process is a sufficiently low value of 6%, and a good result with no practical problem was obtained as a ROM disk with a recording capacity of 25 GB.

(Example 2)
In this example, a master disc of an optical disc stamper having no intermediate layer 105 as shown in FIG. 1 was produced.

  As the phase change layer 102, an incomplete oxide of W, which is the same phase change material as in Example 1, was used. The phase change layer 102 made of an incomplete oxide of W was produced by the same method as in Example 1. The film thickness was 150 nm, the absorbance at a wavelength of 405 nm was 20%, and the transmittance was 70%.

  Next, the same information as in Example 1 was recorded using the same exposure apparatus as in Example 1. The exposure conditions at this time were a linear velocity of 4.92 m / s and a power of 12 mW. As a result, a convex portion corresponding to the recorded information was formed, and its height was about 50 nm.

  Further, an optical disk substrate was produced from the obtained optical disk stamper by the same method as in Example 1, and an Ag alloy reflective film and a 0.1 mm protective film were formed on the optical disk substrate to produce an optical disk. When this optical disk was subjected to signal evaluation in the same manner as in Example 1, a jitter of 6%, which is practically acceptable, was obtained.

(Example 3)
In this example, a master disc of an optical disc stamper having a configuration as shown in FIG. 6 was produced. That is, the substrate 101, the intermediate layer 105, the first phase change layer 106, the first light absorption layer 109, the second light absorption layer 110, and the second phase change layer 107 are sequentially stacked to form an optical disc stamper. A master was produced.

  First, an ultraviolet curable resin layer 105 having a thickness of 50 μm was formed on a flat quartz glass disc 101 having an outer diameter of 130 mm and a thickness of 2 mm.

On the intermediate layer 105, a ZnS and SiO ₂ mixture having a molar ratio of ZnS and SiO ₂ of 4: 1 was deposited by sputtering to form a phase change layer 106 on the substrate side.

  On the first phase change layer 106, 5 nm of SiON was deposited to form the first light absorption layer 109. The first light absorption layer 109 was formed by a reactive sputtering method using a mixed gas of Ar, oxygen, and nitrogen using a Si target. At this time, the gas flow rates of Ar, oxygen, and nitrogen were 46 sccm, 1.5 sccm, and 2.5 sccm, respectively.

  On the first light absorption layer 109, 5 nm of AlON was deposited to form the second light absorption layer 110. The second light absorption layer 110 was formed by a reactive sputtering method using a mixed gas of Ar, oxygen and nitrogen using an Al target. At this time, the gas flow rates of Ar, oxygen, and nitrogen were 44.5 sccm, 2.5 sccm, and 3.0 sccm, respectively.

On the second light absorbing layer 110, ZnS and SiO ₂ molar ratio of 4: a mixture of ZnS and SiO ₂ is 1 to 50nm by a sputtering method to form a second phase change layer 107.

  Next, the phase change layer having the light absorption layer in between was irradiated with laser light using the same exposure apparatus as in Example 1. At this time, the wavelength of the laser beam was 405 nm, the exposure condition was a linear velocity of 4.92 m / s, and the laser power was 10 mW.

  As a result, as shown in FIG. 5, a convex portion corresponding to the irradiated laser power, that is, corresponding to the recorded information was formed. The height of the convex portion was about 50 nm.

Was subjected to transmission electron microscopy (TEM) by cross-sectional observation and electron beam diffraction, the molar ratio of the area having a convex portion formed ZnS and SiO ₂ is 4: 1 mixture of ZnS and SiO ₂ is is in a crystalline state It was found that the region where no convex portion was formed was in an amorphous state.

  Further, an optical disk substrate was produced from the obtained optical disk stamper by the same method as in Example 1, and an Ag alloy reflective film and a 0.1 mm protective film were formed on the optical disk substrate to produce an optical disk. When this optical disk was subjected to signal evaluation in the same manner as in Example 1, a jitter of 6%, which is practically acceptable, was obtained.

  Further, when the uneven surface of this optical disk was observed with an SEM, the pits were formed in a state in which pits having a length of 150 nm, linear pits having a width of 130 nm, and the like correspond to actual signal patterns, and an optical disk having a recording capacity of 25 GB. It was confirmed that

Example 4
The master disk of the optical disc stamper produced in Example 3 was continuously irradiated with laser light from the film surface side using the exposure apparatus used in Example 1 to form continuous linear convex portions.

  The laser power at this time was 7.5 mW in DC. The height of the convex portion was about 20 nm.

  Further, an optical disk substrate was manufactured from the obtained optical disk stamper by the same method as in Example 1, and a Si 5 nm reflective film and a 0.1 mm protective film were formed on the optical disk substrate to manufacture an optical disk. When this optical disk was subjected to signal evaluation in the same manner as in Example 1, a jitter of 6%, which is practically acceptable, was obtained.

  The optical disc stamper and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

This is a master disc for optical disc stampers. 2 is an optical disc stamper obtained after condensing and irradiating laser light onto the master disc of the optical disc stamper shown in FIG. 1 is a master disc of an optical disc stamper having an intermediate layer. 1 is a master disc of an optical disc stamper having a light absorption layer. This is a master disc of an optical disc stamper having an intermediate layer and a light absorption layer. This is a master disk of an optical disc stamper having a light absorption layer composed of an intermediate layer and two layers.

Explanation of symbols

101: substrate 102: phase change layer 103: crystalline layer 104: amorphous layer 105: intermediate layer 106: first phase change layer 107: second phase change layer 108: light absorption layer 109: first light absorption layer 110 : Second light absorption layer

Claims (20)

An optical disc stamper having a convex portion corresponding to a signal pattern of an optical disc,
A phase change layer mainly comprising at least a transition metal sulfide or oxide or a mixture thereof on a flat substrate;
The optical disc stamper, wherein the convex portion is a crystal layer of the phase change layer and the other region is an amorphous layer of the phase change layer.   The optical disk stamper according to claim 1, further comprising an intermediate layer having a lower thermal conductivity than the flat substrate between the flat substrate and the phase change layer.   The optical disc stamper according to claim 2, wherein the intermediate layer is made of a resin material.   4. The optical disk stamper according to claim 3, wherein the resin material is made of a material selected from polycarbonate resin, acrylic resin, and ultraviolet curable resin.   5. The optical disc stamper according to claim 1, wherein a light absorption layer is provided in contact with the phase change layer.   6. The optical disk stamper according to claim 5, wherein the light absorbing layer is mainly composed of an oxide or nitride of Al or Si, nitride, oxynitride, or a mixture thereof.   The light absorption layer includes a first light absorption layer mainly composed of an oxide, nitride, oxynitride, or mixture of Al, and an oxide, nitride, oxynitride, or these of Si. 6. The optical disk stamper according to claim 5, wherein the optical disk stamper has a laminated structure of a second light absorption layer mainly composed of a mixture.   The optical disc stamper according to any one of claims 1 to 7, wherein the transition metal is at least one of Zn, Mo, and W.   The phase change layer is an oxide of Mo or W, and is mainly composed of an incomplete oxide shifted in a direction in which the oxygen content is smaller than the stoichiometric composition corresponding to the valence that these metals can take. The optical disk stamper according to claim 8, wherein the optical disk stamper is used. The optical disk stamper according to claim 8, wherein the phase change layer is made of ZnS or a mixture of ZnS and SiO ₂ . Forming a phase change layer mainly composed of at least a transition metal sulfide or oxide, or a mixture thereof on a flat substrate;
A method of manufacturing an optical disc stamper, comprising: condensing and irradiating laser light corresponding to a signal pattern of an optical disc on the phase change layer, and forming a convex portion in the irradiated region.   12. The method of manufacturing an optical disk stamper according to claim 11, further comprising an intermediate layer having a lower thermal conductivity than the substrate between the flat substrate and the phase change layer.   13. The method for manufacturing an optical disc stamper according to claim 12, wherein the intermediate layer is made of a resin material.   14. The method for manufacturing an optical disc stamper according to claim 13, wherein the resin material is made of a material selected from polycarbonate resin, acrylic resin, and ultraviolet curable resin.   15. The method of manufacturing an optical disc stamper according to claim 10, wherein a light absorption layer is provided in contact with the phase change layer.   16. The method for manufacturing an optical disc stamper according to claim 15, wherein the light absorption layer is mainly composed of an oxide or nitride of Al or Si, nitride, oxynitride, or a mixture thereof.   The light absorption layer includes a first light absorption layer mainly composed of an oxide, nitride, oxynitride, or mixture of Al, and an oxide, nitride, oxynitride, or these of Si. 16. The method for manufacturing a stamper for an optical disk according to claim 15, wherein the optical disk stamper has a laminated structure of a second light absorption layer mainly composed of a mixture.   18. The method for manufacturing an optical disc stamper according to claim 10, wherein the transition metal is at least one of Zn, Mo, and W.   The phase change layer is an oxide of Mo or W, and is mainly composed of an incomplete oxide shifted in a direction in which the oxygen content is smaller than the stoichiometric composition corresponding to the valence that these metals can take. The method for manufacturing an optical disc stamper according to claim 18, wherein: The phase change layer, ZnS or ZnS and manufacturing method of a stamper for an optical disc according to claim 18, characterized in that a mixture of SiO _2.

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