JP2005251308A - Original plate for manufacturing information recording medium, stamper for information recording medium, and information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original plate capable of improving the CN ratio of the information recording medium of a large capacity whose reproducing beam diameter/pitch is 1.3 or larger. <P>SOLUTION: The original plate 1 for manufacturing an information recording medium has a concavo-convex pattern formed on the resist material 3 of the base plate 2. The reproducing beam diameter/track pitch ratio of the information recording medium is 1.3 or larger. Representing the surface roughness of the lands of the above original plate by Rl, and the mirror surface roughness by Rm, the following expression is satisfied: 0.2 nm>Rl-Rm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording medium manufacturing master for manufacturing an information recording medium such as an optical disc, an information recording medium stamper manufactured thereby, and an information recording medium.

Regarding the C / N of the information recording medium and the surface roughness of the pattern, first, the surface roughness Ra (arithmetic mean roughness) of the guide groove bottom of the substrate of the recording medium is defined to be 1 nm or less (and the recording of the guide groove bottom). A technology that defines the layer optical film thickness), a technology that defines the land surface roughness Rms (root mean square roughness) of the land and groove recording medium as 1 nm or less, and the entire surface of the stamper of the recording medium Is known (see, for example, Patent Documents 1 to 3).
Information recording media such as optical disks are mass-produced at low cost by using a metal plate with a guide groove or pit pattern formed on the surface called a stamper as a mold, forming a polycarbonate resin, etc., and giving it a recording material, etc. .
Information recording media such as optical discs have been reduced in pitch, and recording / reproducing apparatuses have also shortened the wavelength of recording / reproducing light to reduce the beam diameter, thereby increasing the capacity of CD-R / RW and DVD ± R / RW.
However, in order to meet the demand for further capacity, the CD-R / RW has a beam diameter of recording / reproducing light and a pitch of the information recording medium that are substantially equal (a region where the intensity of the center of the beam is 1 / e 2). In DVD ± R / RW, the recording / reproducing beam diameter is about 1.2 times the pitch, and it is necessary to further increase the ratio in the next generation and beyond.
As a result, the recording / reproducing light is applied not only to the guide groove in which the signal is recorded but also to the land portion between the guide groove and the guide groove. As a result, the signal quality (carrier / noise ratio; CN ratio) of the information recording medium is greatly influenced by the state of the land portion.
As described above, since the substrate of the information recording medium is transferred from the stamper, and the stamper is transferred from the master, the shape of the substrate is greatly influenced by the shape of the master. As described above, a pattern is formed by forming a resist film on a substrate whose surface is polished to a mirror surface.
Therefore, the bottom of the guide groove is a substrate whose surface is polished to a mirror surface, the land portion is a resist film, and the substrate does not change, so the signal quality of the information recording medium is determined by the quality of the resist film remaining on the land portion. .

The DVD ± R / RW and the like record information in the groove, and land and groove recording media for recording information in both the groove and the land are commercialized by DVD-RAM and the like.
Since land and groove recording media also record information on lands, the amount of information increases by a factor of two for the same track pitch, but the crosstalk from adjacent data increases, so in actuality the groove recording A track pitch of about twice is used.
In the case of this land and groove recording medium, data is also recorded in the land portion, and therefore, when the roughness of the land portion varies, the signal quality of the land portion deteriorates. That is, as in the case of groove recording, the signal quality of the land portion of the information recording medium is determined by the quality of the resist film remaining on the land portion.
In the master exposure of an information recording medium, the pattern of guide grooves or pits needs to be miniaturized as the capacity of the information recording medium increases, so the wavelength of the laser light source has been shortened and the exposure beam diameter has been reduced.
In CD-R / RW, the exposure beam diameter was about 0.3 times the pitch, but in DVD ± R / RW, the exposure beam diameter was about 0.55 times the pitch. There is a need to further increase the ratio.

In the next generation, a pitch of 0.45 μm or less is being studied. However, the limit of the wavelength of the laser light is about 250 nm due to the limitation of shortening the wavelength of the light source and the wavelength limit of an element such as a polarizer that controls the laser beam.
When the pitch is 0.43 μm, the beam diameter is sufficiently narrow with respect to the pitch as in the case of exposing a DVD at 413 nm, so that the pattern can be exposed without interfering with the adjacent track. However, when the pitch was 0.25 μm, it overlapped with the adjacent track, and a pattern could not be formed.
In the case of a pitch of 0.32 μm, the pattern was formed, but there was an overlap with the adjacent track, so that the land portion was slightly exposed and developed, so that the surface roughness ( It was found that (Ra: centerline average roughness) deteriorated to 0.78 nm, compared to 0.5 nm in the case of a pitch of 0.43 μm.
Since the information recording medium meanders the guide groove for address information and the like, the land width fluctuates, so that the unevenness also fluctuates. As a result, there was a problem that the noise of the guide groove increased and CN deteriorated.
In laser exposure in which the beam diameter is determined by the wavelength of the laser light as described above, the pitch is about 0.32 μm, and it is difficult to form a pattern smaller than that. Therefore, an electron beam master exposure apparatus using an electron beam as a new light source has been studied.
However, the electron beam can be reduced in diameter, but the electron scattering is several μm or more even at an acceleration voltage of 20 KV, and if it is exposed at a pitch of 1 μm or less, the land portion that is not required to be exposed is exposed. As a result, the land portion is developed and the surface roughness is increased, which causes a problem similar to laser exposure.
Japanese Patent No. 2562279 JP-A-10-334517 JP 2002-304775 A

However, Patent Document 1 defines the surface roughness Ra of the guide groove bottom as 1 nm or less. However, as described above, since the guide groove bottom is transferred from the polished glass substrate surface, 0.5 nm is conventionally used. On the other hand, the surface roughness value itself of the guide groove bottom is not novel. Further, this conventional example relates to a CD-R which is less influenced by lands, and there is no description regarding the land surface roughness.
Further, Patent Document 2 defines the land surface roughness Rms as 1 nm or less (expressed in terms of Ra, about 0.7 to 0.8 nm), but as described above, the CN of the recording medium has the land roughness itself. However, it is determined by noise caused by lower frequency fluctuations. Therefore, if the land roughness Rms fluctuates between 0.5 nm and 0.7 nm, CN deteriorates.
Conversely, although details will be described later, it is known that the land surface roughness changes when the development time is changed, and even if the land surface roughness changes, CN does not change. That is, even if the land surface roughness Rms is defined to be 1 nm or less, there is a problem that CN is poor.
Patent Document 3 defines that the surface roughness Ra of the entire surface of the stamper of the recording medium is 0.4 nm or less. Although the surface roughness has never been small, in reality, as described in the specification, quartz glass is dry-etched using the pattern formed on the master as a mask, and the surface roughness is reduced depending on the etching conditions. The stamper is made by reducing the amount and electroforming it.
Not only is it difficult to achieve with conventional processes, it must be said that it is an unnecessary specification. This method not only requires expensive dry etching equipment, but also causes many problems such as the use of expensive synthetic quartz glass, increased process time due to dry etching, and the use of harmful gases such as chlorofluorocarbons that cause environmental problems. There was an inconvenience.
An object of the present invention is to manufacture an information recording medium capable of improving the CN ratio of the information recording medium in a large-capacity information recording medium in which the reproduction beam diameter / pitch is 1.3 or more in consideration of the above-described circumstances. To provide a master.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to an information recording medium manufacturing master in which a concavo-convex pattern is formed on a resist material on a substrate. The recording medium manufacturing master is 0.2 nm> Rl−Rm, where Rl is the surface roughness of the land portion of the master and Rm is the surface roughness of the mirror surface.
The invention according to claim 2 is characterized in that the information recording medium is a groove recording medium in which information is recorded in a groove portion thereof.
The invention according to claim 3 is characterized in that the information recording medium is a land-and-groove recording medium on which information is recorded in both the groove and the land portion. To do.
According to a fourth aspect of the present invention, there is provided an information recording medium stamper manufactured from the information recording medium manufacturing master according to any one of the first to third aspects.
According to a fifth aspect of the present invention, there is provided an information recording medium manufactured by the information recording medium stamper according to the fourth aspect.

  According to the present invention, even in a master having a narrow pitch capable of recording a large amount of information, the difference between the land surface roughness and the mirror surface roughness of the master is less than 0.2 nm, so that the land surface roughness variation is small. A master disk can be provided, which makes it possible to create a large-capacity information recording medium with low noise. In addition, since the land roughness variation of the exposed master itself is small, it is possible to create a large-capacity information recording medium with low noise without going through an expensive dry etching apparatus or process.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a first manufacturing process of an information recording medium master according to the present invention. In the first manufacturing process of the master 1, a dyst film 3 is formed on a substrate 2 whose surface is polished to a mirror surface.
FIG. 2 is a diagram showing a second manufacturing process of an information recording medium master according to the present invention. The dying film 3 is irradiated with a laser beam 6 that has been signal-modulated on the basis of recording information by a master exposure apparatus to be exposed.
FIG. 3 is a diagram showing a third manufacturing process of an information recording medium master according to the present invention. Following the second manufacturing process of FIG. 2, by developing this, an optical disc master 1 having a pattern formed on the surface is created.
FIG. 4 is a diagram showing a fourth manufacturing process of an information recording medium master according to the present invention. A conductive film 4 is applied to the surface of the optical disc master 1 created in FIG. 3 to form an electroformed film 5.
FIG. 5 is a diagram showing a fifth manufacturing process of an information recording medium master according to the present invention. A stamper 7 having a pattern formed on the surface is prepared by peeling from the master 1 on which the electroformed film 5 is formed.
An information recording medium such as an optical disk is inexpensive by using a metal plate in which a pattern such as a guide groove or a pit is formed on the surface called a stamper 7 as a mold, forming a polycarbonate resin, etc., and applying a recording material or the like to this. Mass-produced. The stamper 7 is created from the master 1 having a pattern formed on the surface.
The substrate 2 is formed from the stamper 7 and in the case of a rewritable medium, a recording layer such as GeSbTe is formed on the substrate 2, a reflective layer such as Ag is formed, a protective layer is formed, and information that can be recorded and reproduced is recorded. A recording medium is created.
In the case of a non-rewritable medium, a pigment such as phthalocyanine is applied to the substrate 2, a reflective layer such as Ag is attached, and a protective layer is formed to produce an information recording medium.
As described above, the master 1 has a resist film 3 formed on a substrate 2 whose surface is polished to a mirror surface, and a pattern is formed. Therefore, the bottom of the guide groove is the substrate 2 whose surface is polished to a mirror surface. Becomes the resist film 3 and the substrate 2 does not change. Therefore, the signal quality of the information recording medium is determined by the quality of the resist film 3 remaining in the land portion.
In the master exposure of an information recording medium, the pattern of guide grooves or pits needs to be miniaturized as the capacity of the information recording medium increases, so the wavelength of the laser light source has been shortened and the exposure beam diameter has been reduced.
FIG. 6 is a diagram showing the exposure amount distribution in the radial direction when a DVD ± R / RW with a pitch of 0.74 μm is exposed using a Kr laser with a wavelength of 413 nm. As shown in FIG. 6, since the beam diameter is sufficiently narrow with respect to the pitch, the pattern can be exposed without interfering with the adjacent track.
As shown in FIG. 6, even if the pitch is as narrow as 0.6 μm, the pattern can be similarly exposed without interfering with the adjacent track. In the next generation, a pitch of 0.45 μm or less is being studied. However, the wavelength of the laser light is limited to about 250 nm from the limit of shortening the wavelength of the light source and the wavelength limit of an element such as a polarizer that controls the laser light.
As described in the prior art, the information recording medium such as an optical disk has a reduced pitch, and the recording / reproducing apparatus shortens the wavelength of the recording / reproducing light to reduce the beam diameter so that the CD-R / RW, DVD ± R / RW and capacity Has increased.
However, in order to meet the demand for further capacity, the beam diameter of the recording / reproducing light and the pitch of the information recording medium are almost equal in the CD-R / RW (the intensity of the center of the beam is 1 / e ^2). In the case of DVD ± R / RW, the recording / reproducing beam diameter is about 1.2 times the pitch, and it has become necessary to further increase the ratio in the next generation and beyond.

FIG. 7 is a diagram showing a case where the reproduction beam diameter / pitch = 1. FIG. 8 is a diagram showing a case where the reproduction beam diameter / pitch = 1. As a result, the recording / reproducing light is applied not only to the guide groove where the signal is recorded but also to the land portion between the guide groove and the guide groove.
FIG. 9 is a diagram showing the exposure dose distribution in the radial direction at pitches of 0.43 μm, 0.32 μm, and 0.25 μm when the wavelength is 257 nm. When the pitch is 0.43 μm, the beam diameter is sufficiently narrow with respect to the pitch as in the case of exposing a DVD at 413 nm, so that the pattern can be exposed without interfering with the adjacent track.
However, as described above, at a pitch of 0.25 μm, it overlapped with an adjacent track, and a pattern could not be formed. In the case of a pitch of 0.32 μm, the pattern could be formed, but the land portion was exposed to light because of the overlap with the adjacent track, and developed.
As a result, it was found that the surface roughness (Ra: centerline average roughness) of the land portion deteriorated to 0.78 nm as compared to 0.5 nm when the pitch was 0.43 μm. Land roughness occurs when the resist film is slightly exposed and developed.
When developing a resist film, low molecular weight particles that are easily dissolved dissolve first, and then other high molecular weight particles dissolve thereafter. Therefore, at the initial stage of development, particles of about 10 to 100 nm (called grains) are formed on the resist surface. Unevenness occurs in the form that appears in
Since the fine development by the fine exposure caused by the overlapping of the exposure beams hits the initial stage of the development, the land roughness occurs in the form that grains of about 10 to 100 nm appear on the resist surface.
Since the reproduction beam diameter is 400 nm or more even when the wavelength is 405 nm, if the above-mentioned roughness is uniform, it does not appear directly as noise in the reproduction signal. However, since the information recording medium meanders the guide groove for address information or the like, the land width fluctuates, so that the unevenness also fluctuates.

The principle of the present invention will be described. The surface roughness of the master 1 varies depending on the material of the resist film 3, the surface roughness of the substrate 2, the developer type, the development time, and the like. In addition, as described above, the exposure beam diameter / pitch, beam blur, and other factors resulting from exposure change.
However, the material of the resist film 3, the surface roughness of the substrate 2, the developer type, the development time, and the like change the absolute value of the surface roughness, but do not necessarily change in the surface, and as a result information recording Does not increase media noise.
FIG. 10 is a diagram showing the result of measuring the surface roughness after exposing the guide groove with an exposure apparatus, developing the film in 30 to 240 seconds. As shown in FIG. 10, a guide groove having a wavelength of 257 nm and a beam diameter of 0.27 μm is exposed to a guide groove having a pitch of 0.43 μm, and development is usually performed in 60 seconds, and development is performed in 30 to 240 seconds. Was measured.
Further, an information recording medium is prepared from the master 1 as in the conventional example, a single pulse is recorded on the medium by a drive device, and the CN ratio of the reproduction signal is measured (reproduction wavelength 405 nm, reproduction beam diameter 0.58 μm, beam diameter /Pitch=1.35).

FIG. 11 is a diagram showing the exposure amount distribution in the radial direction at pitches of 0.32 μm, 0.43 μm, and 0.60 μm when the wavelength is 350 nm. Both the land surface roughness and the mirror surface roughness increase with the development time, but the CN ratio hardly changes.
However, when a guide groove having a pitch of 0.32 μm was exposed with the same exposure apparatus, the surface roughness of the mirror surface was the same, but the land portion was deteriorated by 0.18 nm in Ra, and the CN ratio was also deteriorated by 4.3 dB (reproduction wavelength: 405 nm). , Reproduction beam diameter 0.44 μm, beam diameter / pitch = 1.38).
As shown in FIG. 9, when the pitch is 0.43 μm, the beam diameter is sufficiently narrow with respect to the pitch, so that the pattern can be exposed without interfering with the adjacent track.
However, in the case of a pitch of 0.32 μm, since there is an overlap with the adjacent track, the land portion is slightly exposed and developed, whereby the surface roughness of the land portion (Ra: center line average roughness). Worsened.
Further, a guide groove having a wavelength of 350 nm and a beam diameter of 0.27 μm was exposed to a guide groove having a pitch of 0.43 μm, and the CN ratio of the reproduction signal was similarly measured (reproduction wavelength of 405 nm, reproduction beam diameter of 0.58 μm, beam diameter / When the pitch was 1.35), the land roughness was equivalent to 240-second development, but the mirror surface roughness was 0.18 nm smaller due to the difference in resist material, and the CN ratio was deteriorated by 2.4 dB.
In this case, as shown in FIG. 11, when a pitch of 0.43 μm is exposed with an exposure apparatus having a wavelength of 350 nm and a beam diameter of 0.27 μm, the surface roughness of the land portion deteriorates due to overlap with adjacent tracks.
If only the value of the land surface roughness is seen, the occurrence of land roughness due to exposure is not known, but the occurrence of land roughness due to exposure becomes clear by taking the difference from the mirror surface roughness.
As described above, the resist material, the surface roughness of the substrate, the developer type, the development time, and the like change the surface roughness of the entire surface, but do not necessarily change in the surface and do not increase the noise of the information recording medium as a result. .
On the other hand, the surface roughness caused by exposure varies in the plane, so that substrate noise is increased and CN is deteriorated. The relationship between land roughness and noise in various exposure apparatuses will be described.

FIG. 12 is a diagram showing the relationship between land roughness and noise in various exposure apparatuses. As is apparent from this data, the noise is not determined by the roughness of the land portion, but deteriorates when the difference between the roughness of the mirror surface and the roughness of the land portion becomes large.
FIG. 13 is a diagram for explaining the difference between the roughness Ra of the mirror surface and the roughness Ra of the land portion. As apparent from FIG. 13, when the difference between the roughness Ra of the mirror surface and the roughness Ra of the land exceeds 0.2 nm, CN deteriorates.
That is, the variation in the surface roughness of the land surface affects the reproduction signal of the information recording medium. In a large-capacity information recording medium in which the reproduction beam diameter / pitch is 1.3 or more, the difference between the mirror surface roughness Ra and the land portion roughness Ra of the master for producing the information recording medium is 0.2 nm or less. Thus, the CN of the reproduction signal of the information recording medium can be improved.
The 1st and 2nd Example of this invention is shown. Using an exposure apparatus having a wavelength of 257 nm and a beam diameter of 0.27 μm, 300 UV deep UV resist coated on a glass substrate was exposed and developed for 60 seconds to form guide grooves having a pitch of 0.43 μm and a width of 0.18 μm.
When the surface roughness was measured with an atomic force microscope AFM, the mirror surface had Ra = 0.5 nm, the land portion had Ra = 0.6 nm, and the difference between the mirror surface roughness Ra and the land portion roughness Ra was 0. .10 nm.
Similarly, after exposure, development was performed for 240 seconds to form a guide groove having a pitch of 0.43 μm and a width of 0.18 μm, and when the surface roughness was measured by an atomic force microscope AFM, the mirror surface had Ra = 0.63 nm. In the land portion, Ra = 0.76 nm, and the difference between the mirror surface roughness Ra and the land portion roughness Ra was 0.11 nm.
A stamper is produced from this master by the same method as before, a substrate is formed from this stamper, a GeSbTe recording layer is formed on these substrates, an Ag reflective layer is formed, a protective layer is formed, and recording / reproduction is performed. A possible information recording medium was created.
When a single pulse was recorded on this medium with a drive device having a wavelength of 405 nm and an objective lens NA = 0.65, and the CN ratio of the reproduction signal was measured, both 60 seconds development and 240 seconds development were good at 54.6 dB and 54.7 dB. Results were obtained.

The 1st comparative example with respect to this invention is shown. An exposure apparatus having a wavelength of 350 nm and a beam diameter of 0.36 μm exposes 300 μm of UV resist applied on a glass substrate, develops it for 60 seconds, and guides the same as in the above embodiment with a pitch of 0.43 μm and a width of 0.18 μm. A groove was formed.
When the surface roughness was measured by an atomic force microscope AFM, Ra = 0.45 nm for the mirror surface, Ra = 0.74 nm for the land portion, and the difference between the mirror surface roughness Ra and the land portion roughness Ra was 0. It was 29 nm.
When an information recording medium was prepared from this master in the same manner as in the example, and the CN ratio of the reproduction signal was measured in the same manner as in the example, the CN was deteriorated by 2.4 dB compared to the above example, which was 52.3 dB.
Example 1 and Comparative Example 1 are cases where the reproduction beam diameter is 0.58 μm, the pitch is 0.43 μm, and the reproduction beam diameter / pitch is 1.35. For other Examples and Comparative Examples, FIG.
3 shows a third embodiment according to the present invention. A 250-nm electron beam resist was applied to a Si substrate, exposed to an electron beam diameter of 50 nm, an acceleration voltage of 1 KV, and developed for 60 seconds to form a groove having a pitch of 0.32 μm and a width of 0.13.
When the surface roughness was measured by an atomic force microscope AFM, the mirror surface was Ra = 0.5 nm, the land portion was Ra = 0.5 nm, and there was no difference between the mirror surface roughness Ra and the land portion roughness Ra. .
A stamper is created from this master by the same method as before, a substrate is formed from this stamper, a GeSbTe recording layer is formed on this substrate, an Ag reflection layer is formed, a protective layer is formed, and recording / reproduction is possible. A new information recording medium.
When a single pulse was recorded on this medium with a drive device having a wavelength of 405 nm and an objective lens NA = 0.85, and the CN ratio of the reproduction signal was measured, a favorable result of 54.6 dB was obtained.

The 2nd comparative example with respect to this invention is shown. An exposure apparatus having a wavelength of 257 nm and a beam diameter of 0.27 μm exposes a Deep UV resist 250 mm coated on a glass substrate, develops it for 60 seconds, and guides the same as in Example 2 with a pitch of 0.32 μm and a width of 0.13 μm. A groove was formed.
When the surface roughness was measured by an atomic force microscope AFM, the mirror surface had Ra = 0.5 nm, the land portion had Ra = 0.78 nm, and the difference between the mirror surface roughness Ra and the land portion roughness Ra was 0. 28 nm.
When an information recording medium was created from this master in the same manner as in the example, and the CN ratio of the reproduction signal was measured in the same manner as in the example, the CN deteriorated by 3.4 dB compared to the example, which was 50.3 dB. In Example 2 and Comparative Example 2, the reproduction beam diameter is 0.44 μm, the pitch is 0.32 μm, and the reproduction beam diameter / pitch is 1.38. For other examples and comparative examples, FIG. 12 can be referred to.
Example 4 according to the present invention will be described. With an exposure apparatus having a wavelength of 257 nm and a beam diameter of 0.27 μm, the Deep UV resist 450 mm coated on the glass substrate was exposed and developed for 60 seconds to form guide grooves having a pitch of 0.43 μm and a width of 0.215 μm.
When the surface roughness was measured with an atomic force microscope AFM, the mirror surface had Ra = 0.5 nm, the land portion had Ra = 0.6 nm, and the difference between the mirror surface roughness Ra and the land portion roughness Ra was 0. .10 nm. Incidentally, the groove was 0.34 nm.
A stamper is produced from this master by the same method as before, a substrate is formed from this stamper, a GeSbTe recording layer is formed on these substrates, an Ag reflective layer is formed, a protective layer is formed, and recording / reproduction is performed. A possible information recording medium was created.
When a single pulse was recorded on the land portion with a drive device having a wavelength of 405 nm and an objective lens NA = 0.65 on this medium, and the CN ratio of the reproduction signal was measured, 60 seconds development and 240 seconds development were good at 53.5 dB. Results were obtained.

The 3rd comparative example with respect to this invention is shown. With an exposure apparatus having a wavelength of 350 nm and a beam diameter of 0.36 μm, a UV resist 450 mm coated on a glass substrate is exposed, developed for 60 seconds, and a guide groove similar to the embodiment having a pitch of 0.43 μm and a width of 0.215 μm Formed.
When the surface roughness was measured by an atomic force microscope AFM, Ra = 0.45 nm for the mirror surface, Ra = 0.74 nm for the land portion, and the difference between the mirror surface roughness Ra and the land portion roughness Ra was 0. It was 29 nm. Incidentally, the groove was 0.34 nm.
When an information recording medium was prepared from this master in the same manner as in the example, and the CN ratio of the reproduction signal was measured in the same manner as in the example, the CN deteriorated by 2.1 dB compared to the example, which was 51.4 dB.
In Example 1 and Comparative Example 1, the reproduction beam diameter is 0.58 μm, the pitch is 0.43 μm, and the reproduction beam diameter / pitch is 1.35.
In the above-described embodiments, the rewritable medium using the phase change recording film as the recording material has been described. However, it can be applied to a recording medium using a dye as the recording material.

The figure which shows the 1st manufacturing process of the master for information recording media by this invention. The figure which shows the 2nd manufacturing process of the master for information recording media by this invention. The figure which shows the 3rd manufacturing process of the master for information recording media by this invention. The figure which shows the 4th manufacturing process of the master for information recording media by this invention. The figure which shows the 5th manufacturing process of the master for information recording media by this invention. The figure which shows exposure amount distribution of the radial direction at the time of exposing DVD +/- R / RW with a pitch of 0.74 micrometer using Kr laser with a wavelength of 413 nm. The figure which shows the case where reproduction beam diameter / pitch = 1. The figure which shows the case where reproduction beam diameter / pitch = 1. The figure which shows exposure amount distribution of the radial direction in pitch 0.43 micrometer, 0.32 micrometer, and 0.25 micrometer in the case of wavelength 257nm. The figure which shows the result of having exposed the guide groove with the exposure apparatus, developing in 30 to 240 seconds, and measuring the surface roughness. The figure which shows exposure amount distribution of the radial direction in pitch 0.32 micrometer, 0.43 micrometer, and 0.60 micrometer in the case of wavelength 350nm. The figure which shows the relationship between the land roughness and noise in various exposure apparatuses. The figure explaining the difference of the roughness Ra of a mirror surface, and the roughness Ra of a land part.

Explanation of symbols

1 Master 2 Substrate 4 Resist film 6 Laser beam (exposure device)
7 Stamper

Claims (5)

  In an information recording medium manufacturing master having a concavo-convex pattern formed on a resist material on a substrate, the reproduction beam diameter / track pitch of the information recording medium is 1.3 or more, and the surface roughness of the land portion of the master is Rl. A master for producing a recording medium, wherein 0.2 nm> Rl−Rm, where Rm is the surface roughness of the mirror surface.   2. The recording medium manufacturing master according to claim 1, wherein the information recording medium is a groove recording medium in which information is recorded in a groove portion thereof.   2. The recording medium manufacturing master according to claim 1, wherein the information recording medium is a land-and-groove recording medium in which information is recorded in both the groove and the land portion.   An information recording medium stamper manufactured from the information recording medium manufacturing master according to any one of claims 1 to 3.   An information recording medium manufactured from the information recording medium stamper according to claim 4.

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