JPH10106047A - Production of optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the high recording density of an optical recording medium by applying a metal plating to a master stamper and performing stripping process to manufacture a mother stamper and transferring the mother stamper thereby forming fine ruggednesses on a substrate. SOLUTION: The mother stamper is manufactured by nickel plating on the master stamper through a strippable film and then stripping nickel. The mother stamper is pressed to be struck to the substrate 30 made of a light transmitting resin to transfer the fine raggedness constituting an information recording layer. After that, in the case of forming a material layer on the raggedness of the substrate 30, a reflection layer 94 is formed, a dielectric layer 92 is formed by adhering on the reflection layer 94 and a phase transition material consisting of GeSbTe alloy is adhered on the dielectric layer 92 as the recording layer. A light transmitting layer 100 is formed thereon though a photosetting resin 3 by 2P method. A phase transition type recording medium is manufactured by using the substrate 30 manufactured by this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical recording medium on which information is recorded or reproduced at least by irradiating a laser beam, particularly an optical recording medium suitable for high density recording.

[0002]

2. Description of the Related Art As an optical recording medium for recording various kinds of information for audio, video, and the like, ROM such as an optical disk, an optical card, a magneto-optical disk, and a phase change optical recording medium for recording or reproducing by light irradiation. (Rea
d Only Memory) type, write-once type, and rewritable type optical recording media are available. In magneto-optical media such as write-once type, rewritable type and magneto-optical or phase change, the phase in which tracking servo signals and the like are recorded Fine irregularities such as pits and pregrooves are formed.

FIG. 20 is a schematic sectional view of a conventional optical recording medium having a single-layer structure.

In this optical recording medium, for example, a transparent material such as polycarbonate or the like having a thickness of, for example, 1.2 mm, a thickness of 0.2 mm or less is used.
At the same time as the production of the substrate 20 having a thickness of 6 mm, the fine unevenness 22 is formed, and the first dielectric layer, the recording layer, and the second
The information recording layer 5 is formed by laminating the material films 4 in this order of the dielectric layer and the reflection film. Further, the information recording layer 5 is formed by laminating, for example, an ultraviolet curable resin to a thickness of several μm to form a protective film 6.

As described above, on the substrate 20 used for this optical recording medium, so-called continuous grooves for tracking servo, that is, fine irregularities 22 are formed.

A method for forming the fine irregularities 22 will be described below.

First, as shown in FIG. 21, a glass master 10 whose surface has been sufficiently polished is placed on a rotating base 80, and the glass master 10 is rotated at a predetermined number of revolutions. A photoresist which becomes alkali-soluble by exposure, that is, a so-called positive resist is supplied from a nozzle 81 and coated on the substrate.

[0008] Next, as shown in FIG.
The photoresist 82 is stretched by rotating 0, and the layer of the photoresist 82 is applied to the entire surface of the glass master 10 as shown in FIG.

Next, as shown in FIG. 24, the photoresist 82 is exposed to a predetermined pattern by a recording laser beam. This exposure is performed along a spiral trajectory at a constant track pitch by sending a recording laser beam in the radial direction of the glass master 10 at equal distances per rotation while rotating the glass master 10.

Next, the glass master 10 is developed with an alkaline developer to remove the exposed portions. In this case, FIG.
As shown in FIG. 5A and as an enlarged view of FIG. 25B, fine irregularities 122 formed by forming through holes are formed in the photoresist 82 on the glass master 10.

As shown in FIG. 26, after the fine irregularities 122 having a predetermined pattern are formed by the photoresist 82, the nickel plating 8 is formed on the glass master 10.
Then, the nickel plating 8 is peeled off, and the fine unevenness 122 is transferred as shown in FIG.
A stamper 18 having 2 is formed.

The stamper 18 is a stamper for transferring fine irregularities constituting an information recording layer formed on a substrate constituting an optical recording medium.

The stamper 18 manufactured as described above
As shown in FIG. 28, the substrate is pressure-bonded onto a substrate 20 made of a light-transmitting resin such as polycarbonate by 2P (photopolymerization) or injection molding, and optical recording is performed as shown in FIG. The fine irregularities 22 forming the information recording layer of the medium are formed.

Thereafter, as shown in FIG. 20, a reflective film made of Al or the like, a material film 4 made of a phase change material, a magneto-optical material or the like is laminated on the fine unevenness 22 of the substrate 20 to form an information recording layer 5.

Further, a liquid photo-curable resin is applied on the information recording layer 5, and the liquid photo-curable resin is stretched by rotating the substrate 20 at a high speed. Is cured to form a protective film 6, whereby a target, for example, a rewritable optical recording medium can be manufactured.

The recording, reading, and rewriting of information on the information recording layer 5 on the optical recording medium are performed by irradiating a laser beam L from the substrate 20 side in FIG.

In this optical recording medium, the stamper 18 is formed by the exposed portion of the photoresist 82 in FIG. 26, and then the stamper 18 is transferred to the substrate 20, that is, the convex portion as viewed from the substrate 20 side shown in FIG. The part 22a becomes a recording part.

In this specification, in the fine irregularities 22 of the substrate 20, a portion finally formed by an exposed portion of the photoresist 82 is named “groove”, and a portion finally formed by an unexposed portion of the photoresist 82 is referred to as “groove”. The formed part is named "land".

[0019]

On the other hand, with the increase in the amount of information recorded on the optical recording medium, it is necessary to increase the recording density, thereby increasing the numerical aperture of the objective lens of the optical pickup. A needs to be as large as possible. Thus, the numerical aperture of the objective lens, N.P. When A is increased, the distance between the objective lens and the information recording layer 5 needs to be selected to be small. In this case, since the inclination tolerance of the optical recording medium decreases, the distance between the information recording layer 5 and the light incident surface is reduced. , That is, the thickness of the light transmitting layer must be sufficiently small, not more than 0.3 mm, for example, desirably about 0.1 mm.

In the above-mentioned conventional optical recording medium,
Light is emitted from the transparent substrate 20 side. That is, in the conventional structure, the substrate 20 becomes a light transmitting layer.
Therefore, it is only necessary to make the substrate 20 thin, but there is a limit in making the substrate 20 thin.

That is, the substrate 20 is made of a light-transmitting resin such as polycarbonate, for example. When the thickness is small, the substrate is likely to be warped due to thermal contraction of the resin immediately after the substrate is manufactured. Therefore, care must be taken in the process of forming the information recording layer and the subsequent application of the protective film.

Therefore, as shown in FIG.
Using a substrate 20 of 2 mm or 0.6 mm,
On the information recording layer, a reflective film 94, a second dielectric layer 92, a recording layer 90, and a first dielectric layer 91 are laminated in the reverse order of the information recording layer of the conventional optical recording medium. To form
On this information recording layer, a light transmitting layer 100 for reading or rewriting information by irradiating light is formed to a thickness of 0.3 mm using a liquid photocurable resin 3 by a method such as the 2P method.
An optical recording medium having a thin and uniform thickness, for example, formed to a thickness of about 0.1 mm has been proposed below.

On the other hand, in the above-described conventional optical recording medium, the recording information is recorded in a convex portion (corresponding to the groove by the above-mentioned name) as viewed from the substrate 20 side shown in FIG. .

However, as shown in FIG.
If information is read or rewritten by irradiating light from the light transmitting layer 100 formed on the side opposite to the 0 side, the recorded information is concave (see FIG. 30) when viewed from the light transmitting layer 100 side. Also in this case, it is recorded in the portion corresponding to the groove by the above naming).

In this case, in FIG. 30, the effective groove width d ₂ for recording / reproduction and rewriting is smaller than the groove width d ₁ of the fine irregularities on the substrate 20. When recording is performed on a groove as described above, when the width of the groove is reduced, the carrier level of the reproduced signal is reduced, and an RF (high frequency) signal is reduced.

In particular, a problem arises when the track pitch is reduced to increase the recording density.

Therefore, as shown in FIG.
It is conceivable that a convex portion viewed from 00 is a portion for recording information.

In the case of adopting the configuration as shown in FIG. 31,
In the recording area, the portion which is convex when viewed from the light transmitting layer 100 side, i.e. in this case, in the land by the nomenclature, the width d ₄ is the effective width than the land width d ₃ of the fine irregularities of the substrate 20 Becomes wider.

However, in this land, the portion of the unexposed portion of the photoresist 82 in FIG. 26 formed by the boundary surface 8L between the photoresist 82 and the Ni plating 8 is transferred to the substrate 20, and the substrate 20 is manufactured. Since the boundary surface 8L is formed at the same time, the boundary surface 8L of this portion is formed by the surface shape of the photoresist 82 and becomes a surface having poor surface properties.

Therefore, the land portion has recorded information.
For example, in a reflectivity reproduction type phase change optical recording medium, noise increases and a fluctuation in track pitch causes a fluctuation in width, thereby deteriorating a reproduction signal. In addition, when it is desired to increase the land width, it is difficult to form the groove with a narrow width.

On the other hand, the portion formed by the boundary surface 8G between the glass master 10 and the nickel plating 8 corresponds to the substrate 2
The surface of the groove formed by being transferred to 0 is formed smoothly.

In view of the above, according to the present invention, as the recording information volume of the optical recording medium is increased, the recording density is increased, and the portion having the recording information becomes convex when viewed from the light transmitting layer.

[0033]

According to the present invention, a positive photoresist is applied to a glass master, and after a development process, a master stamper is manufactured by metal plating, and the master stamper is further subjected to metal plating and peeled off. The process is performed an odd number of times to produce a mother stamper, and an optical recording medium is produced by a method of forming fine irregularities on a substrate by transferring the mother stamper.

Further, according to the present invention, a negative type photoresist is applied to a glass master, a metal plating is performed after a developing process, and the resultant is peeled to produce a master stamper. An optical recording medium is manufactured by a method of forming unevenness.

As a result, a higher recording density of the optical recording medium can be realized, and information can be recorded on the convex portions of the fine irregularities constituting the information recording layer, as viewed from the light transmitting layer, and an effective groove can be formed. The width can be widened, so that a large carrier level and RF signal can be obtained even when the track pitch is narrowed.

In particular, when a positive photoresist is used, the surface of the portion having recorded information as viewed from the light transmitting layer can be formed smoothly, and a large carrier level and RF signal can be obtained. Can be.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where the present invention is applied to a disk, that is, a so-called disk-shaped optical disk will be described below. However, the method of the present invention is not limited to such an optical disk or a shape. The present invention can be applied to various optical recording media having an information recording layer having fine irregularities such as a phase change disk, a card shape, and a sheet shape.

An embodiment of the method of the present invention will be described.

In each of the following examples (Examples 1 to 3), as shown in FIG. 1, a reflective film 94 and a recording layer 90 are laminated at least in order on a substrate 30 made of a light-transmitting resin. The light transmission layer 100 having a thickness of 0.3 mm or less is
o Polymerization) method to obtain an optical recording medium having a configuration formed by the method.

(Example 1) First, as described above, the glass master 10 whose surface has been sufficiently polished is rotated at a predetermined number of revolutions, and the glass master 10 is exposed to light to make it alkali-soluble. A photoresist 82, that is, a positive resist is applied.

Then, the glass master 10 is rotated, the photoresist 82 is stretched, and a layer of the photoresist 82 is applied on the glass master 10.

Next, as shown in FIG. 3, the photoresist 82 is exposed to a predetermined pattern by a recording laser beam. At this time, the recording laser light is sent in the radial direction of the glass master 10 at an equal distance per rotation while rotating the glass master 10, thereby performing spiral exposure at a constant track pitch.

Next, the glass master 10 is developed with an alkaline developer to remove the exposed portions, and fine irregularities are formed on the glass master 10, as shown in FIG.

At this time, the portion where the photoresist 82 is exposed and removed by the developing solution is the groove 70, and the portion where the photoresist 82 is not exposed and remains is the land 71.

After the predetermined fine irregularities are formed by the photoresist 82 as described above, as shown in FIG.
Nickel plating 8 is performed on the glass master 10, and then the nickel plating 8 is peeled off as shown in FIG. 6 to produce a master stamper 28. Next, as shown in FIG. 7, the surface of the master stamper 28 is subjected to an acid treatment with a dichromic acid solution, for example, to form a release coating 50 on the master stamper 28.

Next, as shown in FIG. 8, nickel plating 8 is performed on the master stamper 28 with a release film 50 interposed therebetween, and then, as shown in FIG. 9, the nickel is peeled off to produce a mother stamper 38.

The mother stamper 38 manufactured as described above is pressed on a substrate 30 made of a light-transmitting resin such as polycarbonate by, for example, the 2P method as shown in FIG. The fine irregularities 32 to be constituted are transferred.

In the above-described example, the surface of the convex portion 28a of the master stamper 28 shown in FIG. 6 is a smooth surface because it is a contact surface with the glass master 10 and is smooth. The portion becomes a concave portion 38a of the mother stamper 38 as shown in FIG. 9, and this mother stamper 38 is pressed on the substrate 30.
The portion of the fine irregularities 32 formed on the substrate 30 that becomes a projection when viewed from the opposite side of the substrate 30 becomes a smooth surface.

The protruding portion when viewed from the opposite side of the substrate 30 corresponds to the exposed and removed portion in FIG. 3, that is, the groove portion, and information is recorded on this portion. .

Thereafter, when a material film is formed on the fine irregularities 32 on the substrate 30, a reflective film 94 is formed to a thickness of 60 nm by Al sputtering or the like.
A second dielectric layer 92 of a mixture of ZnS and SiO ₂ having a thickness of 18 nm is formed on the reflective film 94, and a G layer having a thickness of 24 nm is formed on the second dielectric layer 92 as a recording layer.
A phase change material consisting of an eSbTe alloy is deposited.

Then, a light-transmitting layer 100 having a thickness of 0.1 mm is formed thereon with a light-curing resin 3 interposed therebetween by a 2P method.

In the optical recording medium having such a configuration, the optical characteristics, such as the reflectance, are set by the multiple interference effect of the recording layer 90, the reflection film 94, and the first and second dielectric layers 91 and 92. In addition, in particular, there is a characteristic that thermal characteristics can be set by the reflection film 94 and the second dielectric layer 92.

When a phase-change optical recording medium was produced using the substrate 30 produced as described above, this optical recording medium had a recording laser power of 6 mW, an erasing laser power of 2.7 mW, and a reproducing laser power of 0.2 mW. When an information signal was recorded on the groove portion under the conditions of 5 mW, a linear velocity of 3 m / s, and a mark length of 0.33 μm, and reproduction was performed, the C / N ratio became 50 dB or more.

On the other hand, when an information signal was recorded in the groove portion under the same conditions using the optical recording medium having the conventional structure shown in FIG. 30 and reproduction was performed, the C / N ratio was 53 dB. That is, it is understood that the optical recording medium manufactured by the method of the present invention has an excellent carrier level as compared with the conventional optical recording medium.

Using an optical recording medium having the conventional structure shown in FIG. 31, a land portion (land width 0.35 μm) was used.
When an information signal was recorded on the optical recording medium and the reproduction was performed under the same other conditions, the noise level was increased by 1.5 dB and the track pitch unevenness was increased as compared with the optical recording medium manufactured by the method of the present invention.

That is, by using the optical recording medium manufactured by the method of the present invention, a large carrier level and an RF signal can be obtained even when the track pitch is narrowed. Further, the noise level could be reduced, and as a result, the signal could be reproduced with a high C / N ratio.

In the above-described first embodiment, the transfer of the fine irregularities constituting the information recording layer of the optical recording medium was performed by using the mother stamper 38 which was produced through one transfer from the master stamper 28. Master stamper 2
8 may be subjected to a step of applying an Ni plating and peeling it an odd number of times.

Next, another example in which a positive photoresist is used will be described.

(Example 2) A master stamper 28 is manufactured by the same method as in the above (Example 1), as shown in FIGS.

Next, as shown in FIG. 11, the liquid photo-curable resin 3 is applied on the master stamper 28 and stretched.
The glass plate 40 is pressed, the fine irregularities formed on the master stamper 28 are transferred, the ultraviolet light is irradiated, and the liquid photo-curable resin 3 is cured, as shown in FIG.
The glass stamper 48 is manufactured by peeling off the master stamper 28.

Next, as shown in FIG. 13, the surface of the glass stamper 38 on which the fine irregularities are formed is irradiated with strong ultraviolet rays having a wavelength of about 200 nm.

By irradiating ultraviolet rays in this way,
The surface properties of the glass stamper 38 can be improved, and the peelability can be improved.

As shown in FIG. 14, the glass stamper 48 manufactured as described above is
The substrate is pressure-bonded onto a substrate 30 made of a light-transmitting resin such as polycarbonate, and finally the fine irregularities 32 constituting the information recording layer of the optical recording medium are transferred. In the example described above, the convex portion 28a of the master stamper 28 shown in FIG.
Since it is a contact surface with 0, it is smooth, and the convex portion of this master stamper 28 becomes a concave portion 48a of the glass stamper 48 as shown in FIG. The portion of the fine unevenness 32 formed on the substrate 30 that becomes a projection when viewed from the opposite side of the substrate 30, that is, the information reading side, is a smooth surface.

The portion which becomes a projection when viewed from the opposite side of the substrate 30 corresponds to the portion where the photoresist has been exposed and removed in FIG. 3, that is, the groove portion, and information recording is performed on this portion. Is made.

Thereafter, A is set in the same manner as in the above example.
The reflection film 94, the second dielectric layer 92, the recording layer 90, the first dielectric layer 91, and the light transmitting layer 100 are formed by sputtering or the like, and an optical recording medium is manufactured.

When a phase-change optical recording medium was produced using the substrate 30 produced as described above, this optical recording medium had a recording laser power of 6 mW, an erasing laser power of 2.7 mW, and a reproducing laser power of 0.2 mW. When an information signal was recorded on the groove portion under the conditions of 5 mW, a linear velocity of 3 m / s, and a mark length of 0.33 μm, and reproduction was performed, the C / N ratio became 50 dB or more.

On the other hand, using the optical recording medium having the conventional structure shown in FIG. 30 and recording and reproducing information signals in the groove portion under the same conditions, the C / N ratio was 53 dB.
It became. That is, it is understood that the optical recording medium manufactured by the method of the present invention has an excellent carrier level as compared with the conventional optical recording medium.

An information signal was recorded on the land (land width 0.35 μm) using the optical recording medium having the conventional structure shown in FIG. 31 and reproduction was performed under the same other conditions. As compared with the optical recording medium manufactured by the method of the present invention, the noise level was increased by 1.5 dB, and the track pitch unevenness was increased.

That is, by using the optical recording medium manufactured by the method of the present invention, a large carrier level and an RF signal can be obtained even when the track pitch is narrowed. Further, the noise level could be reduced, and as a result, the signal could be reproduced with a high C / N ratio.

Further, in the above (Example 2), a glass plate is used, but other resins such as polycarbonate and acrylic may be used.

Next, an example in which a negative photoresist is used will be described.

(Example 3) In a state where the glass master 10 whose surface has been sufficiently polished is rotated at a predetermined number of revolutions, the exposed portion of the glass master 10 becomes insoluble in a developing solution. A resist 83, that is, a negative resist, for example, “OMR-83” manufactured by Tokyo Ohka Kogyo Co., Ltd. is applied.

Then, the glass master 10 is rotated, the photoresist 83 is stretched, and a layer of the photoresist 83 is laminated on the glass master 10.

Next, as shown in FIG.
The negative type photoresist 83 is exposed to a predetermined pattern by the recording laser beam condensed in step (1).

Next, the glass master 10 is developed with a developing solution.
The exposed portion (groove) 83a is left. By doing so, fine irregularities are formed on the glass master 10 as shown in FIG.

As described above, after predetermined fine irregularities are formed by the negative photoresist 83, as shown in FIG. 17, nickel plating 8 is performed on the glass master disk 10,
Thereafter, as shown in FIG. 18, the nickel is peeled off, and a master stamper 58 is manufactured.

As shown in FIG. 19, the master stamper 58 manufactured as described above is mounted on a substrate 3 made of a light-transmitting resin such as polycarbonate by a 2P method, for example.
Then, the fine irregularities 32 constituting the information recording layer of the optical recording medium are transferred.

Thereafter, the fine irregularities 32 on the substrate 30
l The reflective film 94 is formed to a thickness of 60 nm by sputtering or the like.
18 nm thick ZnS and S are formed on the reflective film 94.
A _second dielectric layer 92 of a mixture of iO ₂ is deposited.

On the second dielectric layer 92, a phase change material made of a GeSbTe alloy having a thickness of 24 nm is applied as a recording layer.
A 1 mm light transmitting layer 100 is formed by a 2P method.

When a phase change type optical recording medium is manufactured using the substrate 30 manufactured as described above, the recording laser power is 6 mW and the erasing laser power is 2.7 m.
When an information signal was recorded in the groove portion under the conditions of W, a reproduction laser power of 0.5 mW, a linear velocity of 3 m / s, and a mark length of 0.33 μm, and reproduction was performed, the C / N ratio was 50 dB.
That's all.

On the other hand, when an information signal was recorded on the groove portion under the same conditions using the optical recording medium having the conventional structure shown in FIG. 30 and reproduction was performed, the C / N ratio was 53 dB. That is, it is understood that the optical recording medium manufactured by the method of the present invention has an excellent carrier level as compared with the conventional optical recording medium.

An information signal was recorded on the land (land width: 0.35 μm) using the optical recording medium having the conventional structure shown in FIG. 31 and reproduction was performed under the same other conditions. As compared with the optical recording medium manufactured by the method of the present invention, the noise level was increased by 1.5 dB, and the track pitch unevenness was increased.

That is, by using the optical recording medium manufactured by the method of the present invention, a large carrier level and an RF signal can be obtained even when the track pitch is narrowed. Further, the noise level could be reduced, and as a result, the signal could be reproduced with a high C / N ratio.

In the above (Examples 1 to 3), information can be recorded on the convex portions of the fine irregularities constituting the information recording layer, as viewed from the light transmitting layer 100, so that the effective groove width is obtained. It has been found that a large carrier level and a large RF signal can be obtained even when the track pitch is narrowed.

In particular, when a positive type photoresist is used, the surface of the portion having recorded information as viewed from the light transmitting layer 100 can be formed smoothly.
Noise was reduced, and a large carrier level and RF signal were obtained.

The above-described optical recording medium is provided on a substrate 30.
Although an example in which the reflective film 94, the second dielectric layer 92, the recording layer 90, and the first dielectric layer 91 are sequentially stacked has been described, the present invention is not limited to this example, and as shown in FIG. Then, a recording layer 90 is laminated on the reflective film 94, and the recording layer 90
The light transmission layer 100 may be provided on the light transmission layer 100 via the light transmission resin 3.

In the above-described example, the substrate 30 is made of a light-transmitting resin such as polycarbonate. Alternatively, a transparent material such as glass, acrylic resin, or polyolefin resin may be used.

The method for forming the fine irregularities 32 constituting the information recording layer on the substrate 30 is also described in the above 2P.
In addition to the method, a spinner method, an injection molding method and the like can be mentioned.

The recording layer 90 can also be composed of chalcogenite, that is, a chalcogen compound or chalcogen alone.

For example, each of Te and Se alone, and these chalcogenites such as GeSbTe, GeTe and InS
bTeAg, InSeTlCo, InSbSe, Bi ₂
Chalcogenite-based materials such as Te ₃ , BiSe, Sb ₂ Se ₃ , and Sb ₂ Te ₃ can be used.

The first and second dielectric layers 91 and 92 are nitrides, oxides, and sulfides of metals such as Al and Si and metalloid elements. For example, AlN, Si
_{3 N 4, SiO 2, Al} 2 O 3, ZnS, may be used MgF ₂ or the like.

However, the condition is that these materials have no absorption in the semiconductor laser region.

The reflection film 94 has a thermal conductivity of 0.0004 to
A metal element, a metalloid element, a semiconductor element, a compound thereof, or a mixture thereof having a value of 2.2 (J / (cm · K · s)) can be used.

The optical system of the optical disk drive used in the above embodiment has a laser wavelength λ = 635 nm and a numerical aperture NA of the objective lens = 0.8.

According to the present invention, a positive type photoresist is applied to a glass master, a metal plate is applied after a development treatment step, and the resultant is peeled to produce a master stamper. This step is performed an odd number of times to produce a mother stamper, and an optical recording medium is produced by using this mother stamper to form fine irregularities on a substrate.

Further, according to the present invention, a negative type photoresist is applied to a glass master, and after a development process, metal plating is performed. The metal plate is peeled off to produce a master stamper. An optical recording medium is manufactured by a method of forming irregularities.

As a result, a high recording density of the optical recording medium can be realized, and information can be recorded on the convex portions of the fine irregularities constituting the information recording layer, as viewed from the light transmitting layer, and an effective groove can be formed. The width could be widened, so that a large carrier level and RF signal could be obtained even when the track pitch was narrowed.

In particular, when a positive photoresist is used, the surface of the portion having recorded information as viewed from the light transmitting layer can be formed smoothly, and a large carrier level and RF signal can be obtained. Was completed.

[0099]

According to the present invention, a high recording density of an optical recording medium can be realized, and information can be recorded on the convex portions of the fine irregularities constituting the information recording layer when viewed from the light transmitting layer. As a result, the effective groove width can be widened, whereby a large carrier level and RF signal can be obtained even when the track pitch is narrowed.

In particular, when a positive type photoresist is used, the surface of the portion having recorded information as viewed from the light transmitting layer can be formed smoothly, and a large carrier level and RF signal can be obtained. Was completed.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an optical recording medium manufactured by the method of the present invention.

FIG. 2 is a schematic sectional view of an optical recording medium manufactured by the method of the present invention.

FIG. 3 is a view showing a manufacturing process of an optical recording medium according to the method of the present invention.

FIG. 4 is a view showing one manufacturing process of an optical recording medium according to the method of the present invention.

FIG. 5 shows a state diagram in which nickel plating is performed on a glass master.

FIG. 6 shows a state diagram in which a nickel stamp is peeled off to produce a master stamper.

FIG. 7 shows a state diagram in which a release coating is applied to a master stamper.

FIG. 8 shows a state where a nickel stamp is applied to a master stamper.

FIG. 9 shows a view in which the mother stamper is peeled off.

FIG. 10 shows a state diagram in which fine irregularities are transferred to a substrate of an optical recording medium by a stamper.

FIG. 11 shows a manufacturing process diagram of a glass stamper.

FIG. 12 shows a manufacturing process diagram of a glass stamper.

FIG. 13 shows a manufacturing process diagram of a glass stamper.

FIG. 14 is a diagram showing a state in which fine irregularities are transferred to a substrate of an optical recording medium by a glass stamper.

FIG. 15 is a manufacturing process diagram of an optical recording medium when a negative photoresist according to the method of the present invention is used.

FIG. 16 shows the glass substrate after the development processing of the negative photoresist has been performed.

FIG. 17 shows a state where nickel plating is performed on a glass substrate.

FIG. 18 shows a state where nickel plating on a glass substrate is peeled off.

FIG. 19 shows a state diagram in which fine irregularities are transferred to a substrate of an optical recording medium by a master stamper.

FIG. 20 is a schematic sectional view of a conventional optical recording medium having a single-layer structure.

FIG. 21 is a diagram showing a manufacturing process of an optical recording medium master.

FIG. 22 shows a manufacturing process diagram of an optical recording medium master.

FIG. 23 shows a manufacturing process diagram of an original master of an optical recording medium.

FIG. 24 shows a manufacturing process diagram of an optical recording medium master.

FIG. 25 shows a schematic perspective view of a master after exposure. B shows an enlarged view of fine irregularities formed on the master after exposure.

FIG. 26 is a schematic cross-sectional view showing a state where nickel plating has been applied to a master after exposure.

FIG. 27 is a schematic sectional view of a stamper.

FIG. 28 shows a state diagram in which fine irregularities are transferred to a substrate of an optical recording medium by a stamper.

FIG. 29 is a schematic sectional view of a substrate on which fine irregularities are formed by a stamper.

FIG. 30 is a schematic cross-sectional view of an optical recording medium having information recording in a groove portion and reading information from a light transmitting layer side.

FIG. 31 is a schematic cross-sectional view of an optical recording medium having information recording on a land portion and reading information from a light transmitting layer side.

[Explanation of symbols]

3 Liquid photocurable resin, 20, 30 Substrate 22, 3
2,122,222 Fine irregularities, 4,94 Reflective film, 5
Information recording layer, 6 protective film, 8 nickel plating, 8G
Interface between glass master and Ni plating, interface between 8L photoresist and Ni plating, 10 glass master, 1
8 stamper, 22, 32 fine irregularities, 22a convex portion, 28, 58 master stamper, 28a convex portion of master stamper, 38 mother stamper, 38
a recess, 40 glass plate, 48 glass stamper, 4
8a convex part of glass stamper, 50 release coating, 70
Groove, 71 land, 80 rotating base, 81 nozzle, 82 positive photoresist, 83 negative photoresist, 83a exposed part, 85 objective lens, 90
Recording layer, 91 first dielectric layer, 92 second dielectric layer, 100 light transmitting layer

Claims (3)

[Claims] 1. A positive photoresist is applied to a glass master, and after a development process, metal plating is performed. The metal plate is peeled off to produce a master stamper. The master stamper is further plated with metal and peeled. A method for producing an optical recording medium, comprising performing a step an odd number of times to produce a mother stamper, and forming fine irregularities on a substrate by transferring the mother stamper. 2. The transfer of the master stamper,
2. The optical recording medium according to claim 1, wherein a glass stamper is produced by a photopolymerization method, a surface treatment is performed on the glass stamper, and fine irregularities are formed on the substrate by the glass stamper transfer. Method. 3. A negative type photoresist is coated on a glass master, and after a development process, metal plating is performed. The metal plate is peeled off to form a master stamper, and fine irregularities are formed on the substrate using the master stamper. A method for manufacturing an optical recording medium, comprising: