JPH11259909A - Optical recording medium substrate, optical recording medium, method for manufacturing optical recording medium substrate, and method for manufacturing optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To repeatedly record information on both lands and grooves by providing a second groove which is formed practically in parallel with a first groove at the bottom section of the first groove that is formed in a spiral or concentric circular shape on the main surface and supprssing the heat conduction between the lands and the grooves. SOLUTION: The surface between a land 2 and a groove 3 is formed into a staircase shape in the case of forming the land 2 and the groove 3 on the main surface of a substrate 1 in the production of an optical record medium 4. The form of a recording film 5 formed on the substrate 1 reflects the form of the surface of the substrate 1 and is formed into a staircase shape. Thus, the length of the film 5 which interposes between the land 2 and the groove 3, increases. Since the heat conduction between the land 2 and the groove 3 is practically performed through the film 5, the heat conduction between the land 2 and the groove 3 is suppressed and the erasing by the heat conduction from an adjacent track is prevented in the case that information recordings are repeatedly conducted on both the lands and the grooves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium substrate, an optical recording medium, a method for manufacturing an optical recording medium substrate, and a method for manufacturing an optical recording medium, and more particularly, to both lands and grooves. The present invention relates to an optical recording medium substrate capable of repeatedly recording information, an optical recording medium, a method for manufacturing an optical recording medium substrate, and a method for manufacturing an optical recording medium.

[0002]

2. Description of the Related Art In recent years, optical disks have attracted attention as large-capacity memories. The optical disc is a read-only type such as a CD that can only read information and cannot record information, a one-time write-once type such as a CD-R that can record information only once, and can freely record and erase information. It can be performed and is roughly classified into three types of rewritable type used for an external memory or the like of a computer. Among them, the rewritable type is particularly noted for its wide use.

[0003] Rewritable optical disks mainly include:
There are two types: magneto-optical disks and phase-change optical disks. Of these, the phase-change type optical disc uses a recording film that reversibly changes phase between amorphous and crystalline by irradiation with a laser beam or the like, thereby forming an amorphous recording mark and a crystalline background. The reproduction is performed using the difference in the reflectance between the two. This amorphous state is formed by heating the recording film above its melting point and rapidly cooling it, and the crystalline state is formed by heating the recording film above its crystallization temperature but below its melting point. Therefore, the phase-change type optical disk controls the intensity of the laser beam applied to the recording film,
There is an advantage that information can be freely rewritten.

[0004] The magneto-optical disk and the phase-change optical disk are required to have higher capacities, and a higher recording density is required. Currently, in order to achieve high-density recording of optical discs, researches on shortening a laser wavelength, super-resolution technology, and the like are being advanced, and a mastering technology for shortening a track pitch or a mark pitch is being studied. Further, conventionally, recording was performed only on the groove portion (groove) or only on the bank portion (land) of the disk, but the depth of the groove is optically adjusted to prevent the influence of crosstalk from an adjacent track. This makes it possible to record on both the groove and the land.

However, when land / groove recording is performed, if the track pitch is narrowed, when recording or erasing is performed on either one of the adjacent land and groove portions, the mark recorded on the other track is not reached. It may be erased. This is because the heat of the recording laser is conducted to the surroundings. In order to prevent such undesired erasure of recording, attempts have been made to reduce the diameter of the beam spot and optimize the configuration of the recording film. In such a case, it is difficult to suppress the above-described heat conduction.

When the recording density of an optical disc is increased, especially in a phase-change optical disc, the overwriting is repeated, and the recording / reproducing jitter characteristic tends to decrease. This is because, in a phase-change type optical disk utilizing a difference in reflectance between an amorphous phase and a crystalline phase, the recording film is changed when the recording film is changed between the amorphous phase and the crystalline phase. Is melted and solidified, so that a part of the recording film causes a substance flow by repeating a recording / erasing cycle. For this reason, a part of the recording film slightly moves from its initial position, causing a density variation in the recording film. This is considered as one of the factors that cause the deterioration of the jitter characteristic.

[0007]

As described above, in a conventional optical disk which records on both lands and grooves, when recording is performed on one track of adjacent lands and grooves, the information is recorded on the other track. Mark may be erased. In addition, in a conventional optical disc that records data on both lands and grooves, recording and
When the erase cycle is repeated, the jitter characteristic deteriorates.

According to the present invention, it is possible to repeatedly record information on both lands and grooves, and when recording information, it is difficult to cause unwanted erasure of already recorded information. When the above is repeated, a substrate for an optical recording medium that is unlikely to cause a decrease in jitter characteristics, an optical recording medium,
An object of the present invention is to provide a method for manufacturing a substrate for an optical recording medium and a method for manufacturing an optical recording medium.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a first groove made of a transparent material and formed on at least one main surface in a spiral or concentric shape, and An optical recording medium substrate comprising a second groove formed at the bottom of one groove substantially parallel to the first groove.

Preferred embodiments of the optical recording medium substrate are described below. (1) The second groove is formed at the center of the bottom of the first groove. (2) The period T from the center of the spiral or the circle to the outer peripheral direction of the first groove formed in the spiral or the concentric circle is 0.
96 μm or more, and a difference W ₁ − between the period T and a width W _{1 at} the bottom of the _first groove and a width W _{2 at} the top of the second groove.
W ₂ satisfies the following inequality.

[0011] _{0.04μm ≦ W 1 -W 2 ≦ T} -0.92μm Also, the present invention is made of a transparent material, a first groove formed on at least one major surface to the spiral shape or concentric A substrate having a second groove formed substantially parallel to the first groove at a bottom portion of the first groove, and formed on a surface of the substrate on which the first and second grooves are formed. The present invention further provides an optical recording medium comprising a recording film containing a material whose reflectance or magnetic properties change reversibly upon irradiation with predetermined light.

Further, the present invention provides a first strip-shaped projection formed in a spiral shape or concentrically, and a top of the first strip-shaped projection substantially parallel to the first strip-shaped projection. On the transfer surface on which the formed second band-shaped protrusions are formed,
Arranging a transparent substrate via a photocurable resin, irradiating light while arranging the transparent substrate on a transfer surface, curing the photocurable resin, and peeling the transparent substrate from the transfer surface Provided is a method for manufacturing a substrate for an optical recording medium, comprising the steps of:

The present invention also provides a first groove made of a transparent material and formed on at least one main surface in a spiral or concentric shape, and a first groove formed on a bottom of the first groove. Forming a substrate having a second groove formed substantially in parallel with the substrate, and irradiating a predetermined light on a surface of the substrate on which the first and second grooves are formed, thereby obtaining a reflectance or A method for manufacturing an optical recording medium, comprising a step of forming a recording film containing a material whose magnetic properties change reversibly.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 shows a cross-sectional view of an optical recording medium substrate according to one embodiment of the present invention. The optical recording medium substrate 1 shown in FIG. 1 is made of a transparent material used for a general optical recording medium substrate, such as polycarbonate or glass.

As shown in FIG. 1, a land 2 and a groove 3 are formed on one main surface of the optical recording medium substrate 1, and a surface between the land 2 and the groove 3 is formed as follows. It is formed in a step shape. The land 2 and the groove 3 are
Each of them is formed in a spiral shape or concentric shape, and FIG. 1 shows a cross section passing through the center of the spiral or circle.

By using the optical recording medium substrate 1 having the above-described shape, for example, an optical recording medium having a structure shown in FIG. 2 can be obtained. FIG. 2 is a sectional view of an optical recording medium according to an embodiment of the present invention. In the optical recording medium 4 shown in FIG. 2, the recording film 5 formed on the substrate 1
Has a shape reflecting the shape of the surface of the substrate 1.
That is, the surface of the recording film 5 between the land 2 and the groove 3 is formed in a stepped shape.

As described above, when the surface between the land 2 and the groove 3 of the recording film 5 is formed in a step-like manner, the recording medium interposed between the land 2 and the groove 3 is different from the conventional optical recording medium. The length of the membrane 5 increases. Most of the heat conduction between the land 2 and the groove 3 is usually performed via the recording film 5. Therefore, according to the optical recording medium 4, heat conduction between the land 2 and the groove 3 is less likely to occur, and it is possible to prevent unwanted erasure of recording.

When recording on a predetermined track,
Even when a part of the recording film 5 is melted, heat conduction between the land 2 and the groove 3 is unlikely to occur according to the optical recording medium 4, so that a part of the melted recording film moves from the initial position. Movement is prevented. Further, even if a part of the recording film is melted on the land 2 and moves from the initial position, the moving amount is extremely large because the surface between the land 2 and the groove 3 is formed in a stepped shape. Less. Therefore, in the optical recording medium 4, the density is hardly varied in the recording film, so that the jitter characteristic is hardly reduced.

Although the case where the recording film 5 is formed so as to be in contact with the substrate 1 has been described above, a protective film or the like for protecting the recording film 5 may be provided between the recording film 5 and the substrate 1. . FIG. 3 is a sectional view of an optical recording medium according to another embodiment of the present invention. An optical recording medium 10 shown in FIG. 3 is a phase change type optical recording medium, and a dielectric protection film 11, a phase change recording film 12, a dielectric protection film 13, and a metal reflection film are formed on a substrate 1 shown in FIG. It has a structure in which the layers 14 are sequentially stacked. In the optical recording medium 10 shown in FIG. 3, the dielectric protection film 11, the phase change recording film 12, and the dielectric protection film 13 form a recording layer 15. In FIG. 3, the phase-change optical recording medium 10 is illustrated only for the land or the groove area.

FIG. 4 is a sectional view of an optical recording medium according to still another embodiment of the present invention. The optical recording medium 20 shown in FIG.
3 except that a magneto-optical recording film 22 made of a material such as TbFeCo is provided.

The optical recording media 10 and 20 shown in FIGS.
2, a dielectric protection film 11 is provided between the phase change recording film 12 and the substrate 1 and between the magneto-optical recording film 22 and the substrate 1, respectively. Since these dielectric protection films 11 are formed in a shape that reflects the shape of the substrate 1 shown in FIG. 1, the phase change recording film 12 and the magneto-optical recording film 22 are also formed in a shape that reflects the shape of the substrate 1. So, for example,
Even if the dielectric protection film 11 or the like is provided between the phase change recording film 12 or the magneto-optical recording film 22 and the substrate 1, the above-described effects can be obtained.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 5A to 5F, a stamper for manufacturing an optical recording medium substrate was manufactured. 5A to 5F are cross-sectional views schematically illustrating a method of manufacturing a stamper used for manufacturing an optical recording medium substrate according to an embodiment of the present invention.

In manufacturing the stamper, first, FIG.
As shown in (a), the entirety of one main surface of the Si substrate 30 was oxidized to form a SiO ₂ film 31 with a predetermined thickness. The thickness of the SiO ₂ film 31 determines the depth of the groove of the optical recording medium substrate. Next, after a photoresist film 32 is formed on the SiO ₂ film 31 by spin coating, the photoresist film 32 formed on the SiO ₂ film 31 is formed into a predetermined pattern as shown in FIG. To form a latent image 33 on the photoresist film 32. The exposure of the photoresist film 32 was performed using the master recording apparatus shown in FIG.

FIG. 7 schematically shows a master recording apparatus used in the embodiment of the present invention. According to the master recording apparatus 50 shown in FIG. 7, a laser beam emitted from a laser light source 51 such as a Kr laser is corrected in a laser optical axis control system 52 for optical axis fluctuation due to a change in laser temperature or the like.

The laser beam whose optical axis fluctuation has been corrected is
After being reflected by the mirror 53, O modulator 54
The light quantity is controlled in a beam modulation system 54 composed of a and 54b. The E / O modulators 54a and 54b are connected to a format circuit 59, and by controlling the format circuit 59, modulate the incident laser beam into a laser beam having an arbitrary signal such as a format signal. It is possible to

Subsequently, the laser beam passes through a beam shaping system 55 composed of pinholes and slits, and its beam diameter and shape are adjusted. This completes all adjustments of the laser beam. The beam shape of the adjusted laser beam 40 is confirmed by a beam monitor system 56, further guided by a mirror 57, and focused on the photoresist 32 on the Si substrate 30 by the objective lens 58. At this time,
For example, by rotating the Si substrate 30, the S
A spiral or concentric latent image is formed on the photoresist film 32 on the i-substrate 30.

As described above, the photoresist film 32 on the Si substrate 30 is exposed in a predetermined pattern and then developed to obtain the structure shown in FIG. 5C. In addition,
The opening width of the photoresist 32 was controlled so as to match the width of the groove bottom of the optical recording medium substrate.

Next, the SiO ₂ film 31 formed on the Si substrate 30 was subjected to reactive sputter etching using the photoresist film 32 provided with the opening as a mask. In addition, this reactive sputter etching was performed using the sputtering apparatus shown in FIG.

FIG. 8 schematically shows a sputtering apparatus used in the embodiment of the present invention. In performing a normal sputtering by the sputtering apparatus 60 shown in FIG. 8, first, the substrate 30 is fixed to the support 65. Next, after the inside of the chamber 61 is evacuated to a predetermined pressure by the exhaust device 62, the Ar gas contained in the gas supply source 63 is introduced into the chamber 61 while adjusting the flow rate with the cock 64. The inside of the chamber 61 is controlled to a predetermined reduced pressure state by the exhaust amount of the exhaust device 62 and the Ar flow rate. next,
While rotating the column 65, a voltage is applied to the sputter sources 66 and 67 to generate glow discharge. Thereby, the substrate 3
A desired film is formed on 0.

In the present embodiment, the substrate 30 is fixed to the column 65 so that the surface on which the photoresist film 32 is formed faces downward, and a reverse bias is applied to the substrate 30 so that the substrate 30 is formed.
The SiO ₂ film 31 formed on the i-substrate 30 was subjected to reactive sputter etching. Note that the etching rate of Si is much lower than the etching rate of SiO ₂ . Therefore, only the exposed portion of the SiO ₂ film 31 can be selectively etched without etching the Si substrate 30.

After performing the above-described etching process, FIG.
As shown in (d), the photoresist film 32 on the SiO ₂ film 31 was removed. Note that the above etching process is a dry process and has high directivity. Therefore, according to the above method, the edge of the SiO ₂ film 31 can be formed in a steep shape.

Next, as shown in FIG. 5E, a photoresist film 34 is formed on the Si substrate 30 and the SiO ₂ film 31.
Was formed. Further, by the same method as described above,
The photoresist film 34 was exposed using the master recording apparatus 50 shown in FIG. The exposure of the photoresist film 34 is performed by changing the spot diameter of the laser beam to the SiO ₂ film 31.
The width was adjusted so as to be slightly larger than the width of the groove formed in the SiO ₂ film 31, and the tracking control was performed so that the optical axis of the laser beam scanned the center of the groove formed in the SiO ₂ film 31. As a result, a latent image 35 having a predetermined pattern was formed on the photoresist film 34.

Next, the photoresist film 34 was subjected to a development process, and the exposed portions of the photoresist film 34 were removed. As a result, an opening was formed in the photoresist film 34 with a width wider than the opening formed in the SiO ₂ film 31.

Using the photoresist film 34 as a mask, the SiO ₂ film 31 was subjected to the reactive sputter etching. At this time, the vicinity of the opening of the SiO ₂ film 31 is not covered with the photoresist film 34, that is, is exposed. Therefore, the SiO ₂ film 3
The region near the opening 1 is gradually etched from the top to the bottom. Therefore, it is possible to selectively remove only the exposed upper region of the SiO ₂ film 31 by stopping it halfway without performing etching completely.

The SiO ₂ film 31 exposed as described above
5F, the photoresist film 34 remaining on the SiO ₂ film 31 was removed as shown in FIG. Thus, a step-like band-like projection was formed on the surface of the Si substrate 30. Furthermore, this Si
The stamper 70 was manufactured by applying Ni plating to the surface of the substrate 30 on which the SiO ₂ film 31 was provided.

By using the stamper 70 manufactured as described above, for example, as shown in FIGS.
As shown in (1), a molded substrate 1 made of polycarbonate or the like can be manufactured by injection molding or the like. FIGS. 6G and 6H are cross-sectional views schematically illustrating a method for manufacturing a substrate for an optical recording medium according to an embodiment of the present invention.

In the stamper 70, Ni plating is not always necessary. If the molding technique and the performance of the molding machine are improved, the Si substrate 30 having the step-like band-shaped projections may be used as the stamper. It is possible.

FIG. 9 schematically shows the cross-sectional shape of the stamper manufactured as described above. In FIG. 9, the Ni plating layer formed on the surface of the stamper 70 is omitted. The shape and size of the band-shaped protrusion 73 formed on the surface of the stamper 70 shown in FIG. 9 substantially match the shape and size of the groove formed on the surface of the optical recording medium substrate.
Therefore, by controlling the surface shape of the stamper 70, the surface shape of the optical recording medium substrate can be controlled.

It is preferable that the belt-like projection 73 composed of the first belt-like projection 71 and the second belt-like projection formed on the first belt-like projection has the following shape.
That is, the width W ₁ of the upper part of the first band-shaped projection 71 and the second width W ₁
And the difference W ₁ −W _{2 from} the width W ₂ of the bottom of the band-shaped projection 72 of the band-shaped projection 72 satisfies the following inequality.
3 is preferably formed. In the following inequality, the period T is 0.96 μm or more.

0.04 μm ≦ W ₁ −W ₂ ≦ T−0.92 μm As the difference W ₁ −W ₂ between the width W ₁ and the width W ₂ increases, the heat conduction between the land and the groove decreases. be able to. Usually, if the difference W ₁ -W ₂ is 0.04 μm or more,
Heat conduction between the land and the groove can be sufficiently reduced.

However, when the period T is constant,
As the difference W ₁ -W ₂ increases, the width of the land or groove recording area decreases, so that the carrier level decreases and the CN value deteriorates. Usually, when the width of the area where the land or groove recording is performed is 0.4 μm or more, a sufficient carrier level can be obtained.
Generally, the side surfaces of the first and second band-shaped projections 71 are not formed perpendicular to the substrate surface, but occupy an area of about 0.12 μm per cycle in a direction parallel to the substrate surface.

Therefore, when the period T is [0.4 μm × 2 +
0.12 μm + (W ₁ −W ₂ )] or more, that is, when the relationship of W ₁ −W ₂ ≦ T−0.92 μm is satisfied, a sufficient carrier level can be obtained.

In this embodiment, the belt-like projections 73 are formed with the following dimensions. That is, the first upper width W ₁ and the second strip-shaped projections 73 so that the difference between the width W ₂ of the bottom portion of the band-shaped protrusion 72 is 0.06μm band-shaped protrusions 71
Was formed. The period T of the band-shaped projection 73 is 1.2 μm.
m.

The width of the bottom of the first band-shaped projection 71 is 0.69 μm, the width of the top is 0.64 μm,
Is 80 nm, the width of the bottom of the second band-shaped projection 72 is 0.58 μm, the width of the top is 0.51 μm, and the height from the first band-shaped projection 71 is 70 nm.

Next, the band-like projection 73 of the stamper 70
The surface on which was formed was pressed against a glass substrate via an ultraviolet curable resin. While maintaining this state, the ultraviolet curable resin was irradiated with ultraviolet rays from the glass substrate side to cure the ultraviolet curable resin between the stamper 70 and the glass substrate. After curing the ultraviolet curable resin, the stamper 70 and the glass substrate were separated. The cured ultraviolet curable resin was transferred onto the glass substrate without remaining on the stamper 70. As described above, an optical recording medium substrate was manufactured by the 2P method.

In this embodiment, the substrate for an optical recording medium is manufactured by the 2P method as described above, but the substrate for an optical recording medium may be manufactured by ordinary injection molding. However, when the optical recording medium substrate is manufactured using the 2P method,
Good transferability can be obtained as compared with the case of manufacturing by injection molding. Therefore, by using the 2P method, the effect of the present invention becomes more remarkable.

Next, using the optical recording medium substrate, a phase change type optical recording medium 10 shown in FIG. 3 was produced by a sputtering apparatus 60 shown in FIG. That is, a dielectric protection film 11 made of SiO ₂ , a phase change type recording film 12 made of GeSbTe,
A dielectric protection film 13 made of O ₂ and a metal reflection layer 14 were sequentially laminated. The optical recording medium of the phase change type manufactured in this manner is referred to as a disk A.

Further, a stamper similar to the stamper 70 shown in FIG. 9 was manufactured except that no step was formed on the side surface of the band-shaped projection. That is, the belt-like projection is formed by the method described with reference to FIGS.
A stamper was manufactured by performing an i-plating process.

Using this stamper, a phase-change optical recording medium was manufactured in the same manner as described above. The optical recording medium of the phase change type manufactured in this manner is referred to as a disk B. Regarding the overwrite characteristics of the discs A and B produced as described above, a test DV capable of recording / reproducing
D-RAM drive (wavelength: 650 nm, NA: 0.
It evaluated using 6). This test DVD-RA
The M drive can change the recording pulse pattern. FIG. 10 shows the test results.

FIG. 10 is a graph showing overwrite characteristics of the optical recording medium according to the embodiment of the present invention. In FIG. 10, the horizontal axis represents the number of overwrites (times), and the vertical axis represents the jitter value (%).

As shown in this graph, the jitter value of the disk B is lower until the number of overwrites is about 10,000, but the jitter value of the disk B sharply increases when the number of overwrites exceeds 30,000. To increase. On the other hand, the increase in the jitter value of the disk A is more moderate than that of the disk B. That is, the disc A has a larger number of overwrites at which reproduction is impossible than the disc B.

After recording predetermined information on the lands of the disks A and B, overwriting was repeatedly performed on the grooves. After that, when the information recorded on the land was reproduced, a part of the information recorded on the land was erased on the disk B, whereas the information recorded on the land was erased on the disk A. I never did.

The phase-change type optical recording medium has been described above. However, the magneto-optical recording medium is configured in the same manner as the phase-change type optical recording medium except that the material used for the recording film is different, and the recording method is almost the same. It is. Therefore, the same effect as that described with respect to the phase-change type optical recording medium can be obtained in the magneto-optical recording medium.

[0054]

As described above, according to the present invention,
Since the surface between the land and the groove of the optical recording medium substrate is formed in a step shape, the recording film formed thereon is also formed in the same shape. Therefore, in the optical recording medium of the present invention, the length of the recording film interposed between the land and the groove is longer than that of the conventional optical recording medium, and heat conduction between the land and the groove hardly occurs. Therefore, according to the present invention, it is possible to repeatedly record information on both lands and grooves, and when recording information, it is difficult to cause unwanted erasure of already recorded information. A substrate, an optical recording medium, a method of manufacturing an optical recording medium substrate, and a method of manufacturing an optical recording medium are provided.

In the optical recording medium of the present invention, since heat conduction between the land and the groove hardly occurs, a part of the recording film melted during recording is prevented from moving from the initial position. . Furthermore, even if a part of the recording film is melted on the land and moves from the initial position, the amount of movement is very small because the surface between the land and the groove is formed in a step shape. Therefore, according to the present invention, when the recording / erasing cycle is repeated, the optical recording medium substrate, optical recording medium,
A method for manufacturing a substrate for an optical recording medium and a method for manufacturing an optical recording medium are provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical recording medium substrate according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an optical recording medium according to one embodiment of the present invention.

FIG. 3 is a sectional view showing an optical recording medium according to another embodiment of the present invention.

FIG. 4 is a sectional view showing an optical recording medium according to still another embodiment of the present invention.

FIGS. 5A to 5F are cross-sectional views schematically illustrating a method of manufacturing a stamper used for manufacturing a substrate for an optical recording medium according to an embodiment of the present invention.

FIGS. 6G and 6H are cross-sectional views schematically illustrating a method for manufacturing an optical recording medium substrate according to an embodiment of the present invention.

FIG. 7 is a diagram schematically showing a master recording apparatus used in an embodiment of the present invention.

FIG. 8 is a diagram schematically showing a sputtering apparatus used in an embodiment of the present invention.

FIG. 9 is a diagram schematically showing a cross-sectional shape of a stamper used for manufacturing an optical recording medium according to the embodiment of the present invention.

FIG. 10 is a graph showing overwrite characteristics of the optical recording medium according to the example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Land 3 ... Groove 4, 10, 20 ... Optical recording medium 5 ... Recording film 11, 13 ... Dielectric protection film 12 ... Phase change recording film 14 ... Metal reflection layer 15 ... Recording layer 22 ... Magneto-optical recording film 30 ... Si substrate 31 ... SiO ₂ film 32 ... photo-resist film 33, 35 ... latent image 40 ... laser beam 50 ... master recording apparatus 51 ... laser light source 52 ... laser optical axis control system 53, 57 ... mirror 54 ... Beam modulation systems 54a, 54b ... E. O modulator 59 ... format circuit 55 ... beam shaping system 56 ... beam monitor system 58 ... objective lens 60 ... sputtering device 61 ... chamber 65 ... support column 62 ... exhaust device 63 ... gas supply source 64 ... cock 66, 67 ... sputter source 70 … Stampers 71-73… Strips

Claims (6)

[Claims] 1. A first groove formed of a transparent material and formed in a spiral or concentric shape on at least one main surface, and substantially parallel to the first groove at a bottom of the first groove. A substrate for an optical recording medium, comprising a second groove formed in the substrate. 2. The optical recording medium substrate according to claim 1, wherein the second groove is formed at the center of the bottom of the first groove. 3. A period T from the center to the outer periphery of the spiral or circle of the first groove formed in the spiral or concentric shape.
Is 0.96 μm or more, and the period T, the width W ₁ of the bottom of the first groove and the second
_3. The difference W ₁ −W _{2 from} the width W ₂ of the upper portion of the groove satisfies the following inequality:
3. The substrate for an optical recording medium according to claim 1. 0.04 μm ≦ W ₁ −W ₂ ≦ T−0.92 μm 4. A first groove made of a transparent material and formed in at least one main surface in a spiral or concentric shape;
A substrate having a second groove formed substantially parallel to the first groove at a bottom of the first groove;
And a recording film formed on the surface on which the second groove is formed and containing a material whose reflectance or magnetic characteristics change reversibly by irradiating a predetermined light. Medium. 5. A first band-shaped projection formed in a spiral or concentric shape, and a first band-shaped projection formed on a top of the first band-shaped projection substantially in parallel with the first band-shaped projection. Disposing a transparent substrate via a photo-curable resin on the transfer surface on which the second belt-shaped protrusions are formed; and irradiating light while arranging the transparent substrate on the transfer surface to thereby form the photo-curable resin. And a step of peeling the transparent substrate from a transfer surface. 6. A first groove made of a transparent material and formed on at least one main surface in a spiral or concentric shape;
Forming a substrate having a second groove formed substantially parallel to the first groove at a bottom of the first groove; and forming first and second grooves of the substrate. A method for manufacturing an optical recording medium, comprising a step of forming a recording film containing a material whose reflectance or magnetic properties change reversibly by irradiating a surface with predetermined light.