JP2002342986A - Master disk for manufacturing optical recording medium, stamper for manufacturing optical recording medium, and method for manufacturing optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical recording medium by which an information pit pattern or a groove pattern can be made fine and to provide a method for manufacturing a master disk and a stamper used therefor. SOLUTION: A resist master disk RD is exposed using enlarging masks MK along a rugged pattern by an electron beam(EB) plotting method in which lump-sum exposure is performed for each predetermined area while reducing the pattern of the enlarging masks. A resist film is developed to obtain the resist master disk in which the resist patterns are formed. The stamper consisting of nickel on which the rugged shape of the obtained resist master disk is transferred is formed. A medium substrate on which the rugged shape of the obtained stamper is transferred is formed, and then an optical recording film and a protective film are formed on the medium substrate.

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 (hereinafter also referred to as an optical disk), and a method for manufacturing an optical recording medium manufacturing master and a stamper used in a process for manufacturing the optical recording medium.

[0002]

2. Description of the Related Art In recent years, with the development of technology for digitally recording video data such as moving images and still images, large-capacity data has been handled.
Optical disk devices such as D and DVD are in the spotlight,
Research for further increasing the capacity is underway.

FIG. 10 is a sectional view of a main part of a conventional optical disk. For example, a groove 13a for dividing a track area is provided on one surface of a light-transparent disk substrate 13 made of, for example, polycarbonate. On this surface, for example, a dielectric film, a recording film, a dielectric film, and a reflection film are provided. Are formed in this order to form the optical recording film 14. The layer configuration and the number of layers of the optical recording film 14 differ depending on the type and design of the recording material. Further, a protective film 15 is formed on the optical recording film 14.

In the above optical disk, when recording or reproducing information, for example, a laser beam is applied to the optical recording film 14 from the disk substrate 13 side. During reproduction of the optical disk, the return light reflected by the optical recording film 14 is received by a light receiving element, a predetermined signal is generated by a signal processing circuit, and a reproduction signal is extracted.

In the optical disk as described above, the optical recording film 14 also has an uneven shape in accordance with the groove 13a provided on one surface of the disk substrate 13.
Divides the track area. Hereinafter, a region protruding toward the protective film 15 side when viewed from the disk substrate 13 is called a land, and a concave region is called a groove, and a land / groove recording method for recording information on both the land and the groove can be applied. It is possible. It is also possible to set only one of the land and the groove as a recording area.

[0006] Further, by forming the concave and convex shape of the disk substrate 13 as pits having a length corresponding to recording data and using an optical recording film as a reflection film such as an aluminum film, a read-only (ROM) type optical disk can be used. You can also.

An increase in the capacity of an optical disk device using the above-described optical disk can be realized by shortening the wavelength of a laser beam used for recording and reproduction of the optical disk device and increasing the numerical aperture (NA) of an objective lens. Also, with the increase in the numerical aperture of the objective lens, the tolerance of the disc tilt in the optical disc device decreases, and in order to keep the coma aberration within the tolerance, the thickness of the upper light-transmitting layer of the optical recording film is set. Need to be made thinner. For example, in the case of a CD, the wavelength of a laser beam is 780 nm, the numerical aperture of an objective lens is 0.5, and the thickness of a light-transmitting disk substrate on the optical recording film is 1.2 m.
m, and in DVD, the laser beam wavelength is 630 n
m, the numerical aperture of the objective lens is 0.6, and the thickness of the light-transmitting disk substrate on the upper layer of the optical recording film is 0.6 mm.
It is used as a substrate having a thickness of mm. As a next-generation optical disk device capable of coping with a further increase in capacity, the laser light wavelength is shortened to a blue to violet region (for example, 400 nm), and the numerical aperture of the objective lens is 0.8 or more (for example, 0.85 )), And the thickness of the protective film for transmitting light in the upper layer of the optical recording film is set to 0.1 mm correspondingly.
An optical disk device using an optical recording medium thinned to the extent has been proposed. Since the light transmitting layer having a thickness of 0.1 mm is insufficient in rigidity, a disk substrate having a thickness of about 1.1 mm is used as a lower layer of the optical recording film.

A method for manufacturing the above optical disk will be described. FIG. 11A is a schematic configuration diagram of a cutting apparatus (exposure apparatus) used in the above manufacturing method.
(B) is a perspective view of a main part. As a light source, for example, a Kr gas (ion) laser GL having an oscillation wavelength of 351 nm is provided.
M, polarizing beam splitter PBS1, mirror M1, lens L1, acousto-optic element AOM, lens L2, mirror M
2. The lens L3, the lens L4, the DCM, the mirror M3, and the objective lens OL are arranged at predetermined positions. The optical elements before the mirror M2 are fixed to a fixed surface plate, while the optical elements after the lens L3 are mounted on a movable table MT. In addition, a resist master RD having a resist film formed on a glass substrate as an exposure target of the cutting apparatus is chucked on an air spindle that can be rotationally driven with high rotational accuracy by a spindle motor.

Laser light L emitted from gas laser GL
T1 transmits through the electro-optical element EOM and the polarizing beam splitter PBS1, is reflected by the mirror M1, and its traveling direction is bent. At this time, part of the laser light LT1 passes through the mirror M1 and enters the photodiode PD1. The laser light LT1 reflected by the mirror M1 is condensed by the lens L1, returned to parallel light by the lens L2 via the acousto-optic element AOM, reflected by the mirror M2, and bent in the traveling direction. At this time, the laser light LT1
Is transmitted through the mirror M2 and the photodiode PD2
Incident on. Based on the intensity of light received by the photodiode PD1 or the photodiode PD2, feedback is performed on the electro-optical element EOM, and APC (Automatic Power Control) for obtaining a constant output is performed. Further, if necessary, the laser light LT1 is modulated in the acousto-optic element AOM. The laser beam LT1 reflected by the mirror M2 is transmitted through a lens (L3, L3).
The beam diameter is expanded by the beam expander 4), transmitted through the DCM, reflected by the mirror M3, and spotted with a diameter of, for example, 0.3 μm on the resist film of the resist master RD by the objective lens OL. And an exposure area EX is formed.

In the above-mentioned cutting apparatus, the resist master RD is driven to rotate in the spindle direction SD by a spindle motor (not shown), and the laser beam LT1 is transmitted while moving the movable table MT in the radial direction of the resist master RD by a predetermined width. By irradiating the resist film of the resist master RD, pattern exposure of the resist master RD can be performed. For example, in a process of manufacturing a rewritable optical disk such as a phase-change optical disk, an exposure laser beam can be spirally scanned and exposed along a pattern of a track (land / groove) for dividing a recording area. . In the process of manufacturing a read-only (ROM) optical disk, the exposure laser beam can be spirally scanned and exposed while being turned on and off so as to correspond to recording data (information pits).

An auto-focus (A / F) mechanism is provided to make the focal length of the objective lens always coincide with the resist master RD. For example, an off-axis system using a laser diode LD having an oscillation wavelength of 680 nm is applied as an A / F optical system.
680 nm emitted from the laser beam LT2 is reflected by the spectral surface of the polarizing beam splitter PBS2, passes through the quarter-wave plate QWP, is reflected by DCM, and is irradiated onto the resist master RD together with the laser beam LT1. At this time, the focal point of the laser beam LT2 by the objective lens OL is changed to the laser beam L2.
It is made to coincide with the focal plane of T1. The laser beam LT2 is reflected by the resist master RD, and the spot returned through the objective lens is projected onto the spot position detecting element PSD. At this time, the laser beam LT2 is made to enter the optical axis almost parallel to the optical axis from a position slightly distant from the optical axis of the objective lens, and focused on a position slightly distant from the focal point of the laser beam LT1 on the resist master surface. The displacement of the surface of the master from the focal plane on the optical axis is detected as the displacement of the laser beam LT2 on the resist master, and the magnification is detected about 100 times on the spot position detecting element PSD by the principle of optical leverage. . In this manner, the position of the spot on the spot position detecting element PSD is detected, and the displacement of the laser beam LT2 from the return light spot position when the resist master surface coincides with the focal position is defined as a focus error amount.
The A / F servo is performed by feeding back the actuator to the actuator that moves the objective lens up and down, and the laser light LT1 is used.
Is always focused on the resist master. In the A / F optical system, the polarization beam splitters PBS2 and 1 /
The four-wavelength plate QWP is used as a polarization element for efficiently separating the forward path and the return path of the laser light LT2.

An optical disk can be manufactured as follows using the above-described cutting device. First, FIG.
2A, a resist film 1 is formed on a glass substrate 10 as shown in FIG.
A resist master RD on which a film 1 is formed is prepared. The above glass substrate has a diameter of, for example, 200 mm and a thickness of several mm, and the surface is precisely polished. The resist film 11 is formed by spin coating to a thickness of 100 nm using, for example, a photosensitive positive photoresist that is exposed to ultraviolet light. Solvent remaining in the resist film 11 is several tens of degrees Celsius.
Is removed by baking.

Next, the resist film 11 is exposed to light using a cutting device shown in FIGS. 11A and 11B in a pattern for exposing a region to be a groove of the disk substrate.
FIG. 12 shows a development process using an alkali developer or the like.
As shown in (b), a resist film 11a is formed in a pattern that opens a region to be a groove of the disk substrate.

Next, as shown in FIG. 13A, a stamper 12 is formed on the resist film 11a on the glass substrate 10 by, for example, nickel plating. On the surface of the stamper 12, irregularities having a pattern opposite to that of the concave portion 11b of the pattern constituted by the glass substrate 10 and the resist film 11a are transferred, and a convex portion 12a is formed.

Next, as shown in FIG. 13B, the stamper 12 is released from the resist film 11a on the glass substrate 10.

Next, as shown in FIG. 14 (a), the stamper 12 obtained as described above is fixed in a cavity composed of dies (MD1, MD2) to form a die for injection molding.
At this time, the stamper 12 is installed such that the projection forming surface 12a 'faces the inside of the cavity. By injecting a resin such as polycarbonate in a molten state from the injection port I of the mold into the cavity of the above-mentioned injection mold, FIG.
As shown in FIG. 4B, the disk substrate 13 is formed on the concave / convex pattern of the stamper 12. Here, a groove 13 a is formed on the disk substrate 13, the groove 13 a serving as an uneven pattern having a pattern opposite to that of the surface of the stamper 12.

By releasing the mold from the above injection mold,
A disk substrate 13 having a groove 13a formed on the surface as shown in FIG. Next, as shown in FIG. 15B, after dust such as air or nitrogen gas is blown onto the surface of the disk substrate 13 to remove dust, the dielectric film, the recording film, the dielectric An optical recording film 14 having a laminate of a film and a reflective film is formed in this order. Next, as shown in FIG. 15C, a protective film 15 is formed on the optical recording film 14. Above,
An optical disc having the structure shown in FIG. 10 can be manufactured.

In the above-mentioned exposure step, the laser beam for exposure is spirally scanned and exposed while being turned on and off so as to correspond to the recording data, so that the unevenness of the disk substrate 13 is adjusted to the length corresponding to the recording data. By forming the optical recording film with a reflective film such as an aluminum film, the optical recording film is formed as a pit having a read only (RO).
An M) type optical disk can also be manufactured.

When the resist master is exposed in a predetermined pattern by the cutting apparatus shown in FIG. 11, all the mechanical systems are mounted on an air base so as not to be affected by external vibration at the installation place. In this case, the minimum pattern size that can be formed by cutting, that is, the resolving power P generally depends on the laser wavelength λ, the numerical aperture NA of the objective lens, the characteristics of the resist film, and the like, and usually has a value of 0.5 to 0.8. Is expressed by the following equation (1) from the process factor K taking

[0020]

## EQU1 ## P = K (λ / NA) (1)

For example, λ = 351 nm, NA = 0.9,
Substituting K = 0.5 results in P = 0.2 μm, and the groove or L / S (line / space: width of a portion to be left as a pattern and a portion to be removed) at a track pitch of 0.4 μm is 0.2 μm / The pattern of the resist film having a thickness of 0.2 μm is resolved.

[0022]

However, with the rapid progress of information communication and image processing technology in recent years, it is considered that the capacity of an optical disk will be several times larger than the present one in the near future. A storage capacity is required, and in order to achieve this by the same signal processing on one side of a disk having a diameter of 12 cm, it is necessary to form a pit pattern having a minimum pit size of about 0.16 μm. Since the resolution limit of the conventional cutting device is exceeded, a pattern drawing method capable of forming such fine pits or grooves has been demanded.

On the other hand, regarding the size of the optical disk, 12c has been conventionally used for a stationary optical disk device.
Although an optical disk having a diameter of m is used, in recent years, a small-sized optical disk for a portable optical disk device and a small-sized optical disk suitable for carrying have been spotlighted.
Mini-discs of 4 cm diameter, iD format discs of 5 cm diameter for DVD video cameras and digital cameras of 8 cm size have been proposed, and expectations for small-diameter discs are rapidly increasing. Even if the disc diameter becomes smaller, a larger recording capacity is desired. For example, it is expected that a recording capacity equivalent to that of a 4.7 GB DVD will be required in the near future. For example, assuming a small-diameter optical disk of 40mm diameter, with respect to 704Mm ² radius 10~18mm as an effective signal area, the effective signal area of the DVD is a 7445Mm ² radius 24～58Mm, 4 with the small-diameter optical disk of 40mm diameter In order to realize a recording capacity of 0.7 GB, it is necessary to realize a surface density 10 times or more that of a DVD. If the above-mentioned increase in the surface density is uniformly allocated in the track direction and the linear direction, the shortest pit length is DVD The pit length of 126 nm is required for 0.4 μm. Naturally, such fine pits exceed the resolution limit of the above-mentioned conventional cutting device, and cannot be realized using the conventional cutting device.

The present invention has been made in view of the above circumstances, and accordingly, it is an object of the present invention to provide a method of manufacturing an optical recording medium capable of miniaturizing an information pit pattern or a groove pattern, and a method of manufacturing the optical recording medium. An object of the present invention is to provide a method of manufacturing an optical recording medium manufacturing master and a stamper used in a manufacturing process.

[0025]

In order to achieve the above object, a method for producing a master for producing an optical recording medium according to the present invention comprises:
What is claimed is: 1. A method of manufacturing an optical recording medium manufacturing master used for transferring an uneven shape onto a surface of a medium substrate of an optical recording medium, the method comprising: using an enlarged mask along the pattern of the uneven shape; A step of exposing a resist film formed on the master substrate by an electron beam lithography method of exposing a predetermined area at a time while reducing the size, and a step of developing the resist film.

In the method of the present invention for producing a master for producing an optical recording medium, preferably, a mask having a pattern enlarged to four times or more the pattern of the concavo-convex shape is used as the enlarged mask. More preferably, a stencil mask having a pattern drawn by a laser beam recorder is used as the enlargement mask.

In the method for producing a master for producing an optical recording medium according to the present invention, preferably, in the step of exposing the resist film, a region corresponding to the entirety of one optical recording medium is collectively exposed as the predetermined region. I do. More preferably, in the step of exposing the resist film, each time the area corresponding to the entirety of the one optical recording medium is collectively exposed, the exposing area is sequentially moved to correspond to the entirety of the one optical recording medium. The step of collectively exposing a region to be exposed is repeated, and a pattern corresponding to a plurality of optical recording media is exposed on one master.

In the method of manufacturing a master for manufacturing an optical recording medium according to the present invention, preferably, the concave-convex shape is a pattern of a guide groove which divides a track area of the optical recording medium.
Alternatively, preferably, the uneven shape is a pit pattern of the optical recording medium.

The method of manufacturing a master for manufacturing an optical recording medium according to the present invention is a method of manufacturing a master for manufacturing an optical recording medium used to transfer a pattern of guide grooves for dividing a track area or an uneven pattern such as information pits. A method of reducing the size of a pattern of an enlarged mask by using an enlarged mask such as a mask having a pattern magnified four times or more as large as the pattern of the irregular shape, while reducing the pattern of the enlarged mask. The resist film formed on the master substrate is exposed by an electron beam lithography method that collectively exposes a predetermined area such as an area corresponding to the entire recording medium, and then the resist film is developed. Each time a region corresponding to one entire optical recording medium is collectively exposed, the step of sequentially moving the exposure region and repeatedly exposing a region corresponding to the entire one optical recording medium is repeated on one master. It is also possible to expose a pattern corresponding to a plurality of optical recording media.

According to the method of manufacturing an optical recording medium master according to the present invention described above, the information pit pattern or groove pattern can be miniaturized by employing the electron beam lithography method in which a predetermined area is exposed all at once. An optical recording medium manufacturing master used in the method for manufacturing an optical recording medium can be manufactured.

In order to achieve the above object, a method of manufacturing a stamper for manufacturing an optical recording medium according to the present invention is directed to a method for manufacturing an optical recording medium used for transferring an uneven shape onto a surface of a medium substrate of an optical recording medium. A method for manufacturing a stamper for use, comprising: using an enlarged mask along the pattern of the uneven shape, forming an electron beam on a master substrate by collectively exposing a predetermined area while reducing the pattern of the enlarged mask. Exposing the exposed resist film, developing the resist film, and forming a stamper to which the uneven shape composed of the developed resist film and the master substrate is transferred.

In the method of manufacturing a stamper for manufacturing an optical recording medium according to the present invention, the stamper is preferably formed of nickel.

In the method of manufacturing a stamper for manufacturing an optical recording medium according to the present invention, an electron beam is used to collectively expose a predetermined area while reducing the pattern of the enlarged mask by using the enlarged mask along the pattern of the uneven shape. The resist film formed on the master substrate is exposed by a drawing method, and the resist film is developed. Next, a stamper made of nickel or the like to which an uneven shape composed of the developed resist film and the master substrate is transferred is formed.

According to the method of manufacturing a stamper for manufacturing an optical recording medium of the present invention, an electron beam lithography method of exposing a predetermined area at a time is employed in the step of preparing a master for transferring the irregular shape of the stamper. Accordingly, a stamper for manufacturing an optical recording medium used in a method for manufacturing an optical recording medium capable of miniaturizing an information pit pattern or a groove pattern can be manufactured.

In order to achieve the above object, a method of manufacturing an optical recording medium according to the present invention is a method of manufacturing an optical recording medium having a medium substrate having a surface onto which a concavo-convex shape is transferred. Exposing a resist film formed on a master substrate by an electron beam lithography method that collectively exposes a predetermined area while reducing the pattern of the enlarged mask by using an enlarged mask along the pattern of A step of developing a film and a step of forming a stamper on which the uneven shape composed of the developed resist film and the master substrate are transferred, and a step of forming a medium substrate on which the uneven shape of the stamper is transferred, A step of forming an optical recording film on the uneven surface of the medium substrate; and a step of forming a protective film on the optical recording film.

In the method of manufacturing an optical recording medium according to the present invention, preferably, in the step of exposing the resist film, each time a region corresponding to the entirety of the one optical recording medium is exposed collectively, The step of moving the area and repeatedly exposing the area corresponding to the entirety of the one optical recording medium is repeated, and the pattern corresponding to a plurality of optical recording media is exposed on one master to form the stamper. Forming a stamper having a pattern corresponding to a plurality of optical recording media, forming a medium substrate having a pattern corresponding to a plurality of optical recording media in the step of forming the medium substrate; From a medium substrate having a pattern corresponding to one optical recording medium, and cutting out each pattern corresponding to one optical recording medium to form a plurality of medium bases to be individual optical recording media. To form.

In the method of manufacturing an optical recording medium according to the present invention, preferably, the step of forming the stamper onto which the irregularities are transferred includes the step of forming the irregularities formed by the developed resist film and the master substrate. The method includes a step of forming the transferred intermediate member, and a step of forming a stamper to which the uneven shape of the intermediate member is transferred.

In the method for producing an optical recording medium of the present invention, a phase-change optical recording film is preferably formed as the optical recording film. Alternatively, preferably, a magneto-optical recording film is formed as the optical recording film. Alternatively, preferably, an optical recording film including an organic dye layer is formed as the optical recording film. Alternatively, preferably, a reflective film is formed as the optical recording film.

In the method of manufacturing an optical recording medium according to the present invention, an enlarging mask is formed along an uneven pattern.
The resist film formed on the master substrate is exposed by an electron beam lithography method in which the pattern of the enlarged mask is collectively exposed for each predetermined area while being reduced, and the resist film is developed. Next, a stamper is formed on which the concavo-convex shape composed of the developed resist film and the master substrate is transferred, and then a medium substrate on which the concavo-convex shape of the stamper is transferred is formed. Next, an optical recording film such as a phase-change optical recording film, a magneto-optical recording film, or a reflective film is formed on the surface of the medium substrate on which the uneven shape is formed, and a protective film is formed thereon.

Each time the area corresponding to the entire optical recording medium is collectively exposed, the step of sequentially moving the exposure area and repeatedly exposing the area corresponding to the entire optical recording medium is repeated. In the step of exposing a pattern corresponding to a plurality of optical recording media on the master and forming a stamper,
Forming a stamper having a pattern corresponding to a plurality of optical recording media, forming a media substrate having a pattern corresponding to a plurality of optical recording media in the step of forming a media substrate, and forming a plurality of optical recording media on the plurality of optical recording media. It is also possible to cut out a medium substrate having a corresponding pattern for each pattern corresponding to one optical recording medium, and form a plurality of medium substrates serving as individual optical recording media. Also, in order to form a stamper to which the uneven shape composed of the developed resist film and the master substrate is transferred, an intermediate member to which the uneven shape is transferred is formed, and the stamper is transferred by transferring the uneven shape. It may be formed.

According to the method of manufacturing an optical recording medium of the present invention described above, the information pit pattern or groove pattern can be finely formed by adopting the electron beam lithography method in which a predetermined area is collectively exposed in the step of forming the master. Thus, an optical recording medium can be manufactured. In particular, by simultaneously forming a plurality of disk substrates with optical disk patterns, it is possible to improve manufacturing efficiency.

[0042]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present embodiment relates to a method for manufacturing an optical disk as an optical recording medium, and a method for manufacturing a master for manufacturing an optical recording medium and a stamper used in a process of manufacturing the optical recording medium.

First Embodiment FIG. 1A is a schematic perspective view showing a state of light irradiation of an optical disk according to this embodiment. The optical disc D has a substantially disk shape with a center hole CH opened in the center, and is driven to rotate in the drive direction DR. When recording or reproducing information, the objective lens OL having a numerical aperture of 0.8 or more is applied to the optical recording film in the optical disc DC.
Accordingly, light LT such as laser light in a blue to blue-violet region is irradiated and used.

FIG. 1B is a schematic sectional view, and FIG.
FIG. 2C is an enlarged cross-sectional view of a main part of the schematic cross-sectional view of FIG. On one surface of a disk substrate 13 made of polycarbonate or the like having a thickness of about 1.1 mm, a groove 13a for dividing a track area is provided.
For example, an optical recording film 14 in which a reflection film, a dielectric film, a recording film, a dielectric film, and the like are laminated in this order is formed. The layer configuration and the number of layers of the optical recording film 14 differ depending on the type and design of the recording material. The recording film is, for example, a phase change recording film, a magneto-optical recording film, or a recording film containing an organic dye. Further, an optically transparent protective film 15 having a thickness of 0.1 mm is formed on the optical recording film 14.

When recording or reproducing data on or from the above optical disk, light L such as a laser beam is irradiated by the objective lens OL.
The optical recording film 14 is irradiated with T from the protective film 15 side. During reproduction of the optical disk, the return light reflected by the optical recording film 14 is received by a light receiving element, a predetermined signal is generated by a signal processing circuit, and a reproduction signal is extracted.

In the optical disk as described above, the optical recording film 14 also has an uneven shape in accordance with the groove 13 a provided on one surface of the disk substrate 13.
Divides the track area. Hereinafter, a region protruding toward the protective film 15 side when viewed from the disk substrate 13 is called a land, and a concave region is called a groove, and a land / groove recording method for recording information on both the land and the groove can be applied. It is possible. It is also possible to set only one of the land and the groove as a recording area.

Here, the above-mentioned groove pitch is, for example, 1
The width of the land and the groove is about 80 nm, for example, and the groove has a fine width which has conventionally been difficult to form.

Alternatively, a read-only (ROM) type optical disk can be obtained by forming the concave and convex shape of the disk substrate 13 as pits having a length corresponding to the recording data and using an optical recording film as a reflective film such as an aluminum film. You can also. For example, the track pitch is 160 nm and the minimum pit length is 80 nm. For example, EFM plus (e
right-to-fourteen modulati
onplus) format.

In the above-mentioned ROM type optical disk, the size is, for example, 34 mm in diameter, and the effective signal area is 10 mm in radius.
１５15 mm, the area is (15 ²
−10 ² ) × π = 393 mm ² . In addition, EFM
334m with plus format efficiency 0.85
m ² is the effective user area. Minimum pit length 80n
From m, the linear density is 80 × (2/3) = 53.3 nm and the track pitch is 160 nm, so that the areal density is 8528 nm ² / bit. From the above values, 393
A recording capacity value of mm ² / (8528 nm ² /bit)=4.9 GB is obtained, and a recording capacity equivalent to a DVD can be realized with an optical disc having a diameter of 40 mm or less. The above recording capacity is expressed as the capacity per square inch.
It corresponds to 76 Gbit / inch ² .

A method for manufacturing the above optical disk will be described. FIG. 2 is a schematic configuration diagram of a batch reduction transfer type electron beam drawing apparatus (EB stepper) used in the method of manufacturing an optical disc of the present embodiment. In the electron beam column EBC, the electron gun EG, the condenser lens CL, the objective lens OL, and the mask MK are arranged at predetermined positions. As the mask MK, for example, a stencil mask four times or more larger than a pattern to be drawn is used. A resist master RD having a resist film formed on a master substrate such as a silicon substrate is fixed on the XY stage ST in the direction of the electron beam exit of the electron beam column EBC. The electron beam column EBC and the entire XY stage ST are arranged in a high vacuum chamber.

In the electron beam column EBC,
The electron beam EB emitted from the electron gun EG is collimated and converged by the condenser lens CL, and passes through the mask MK. The mask is provided with an opening and a shield in a pattern that is four times or more the size of the pattern to be drawn. Electron beam E passing through the opening
The B component is collimated by the condenser lens CL,
The light is converged and irradiated onto the resist film on the resist master by the objective lens OL. Here, it is preferable to use a silicon substrate as a master substrate of the resist master used in order to prevent charge-up during drawing. As the resist film, a chemically amplified resist other than an acrylic resin-based resist dedicated to an electron beam can be used.
The resist master exposed by the above-mentioned EB stepper can dissolve the resist film in the region irradiated with the electron beam with a dedicated developing solution to form a desired groove pattern or pit pattern unevenness.

In the above EB stepper, for example, 8
0 nm L / S (line / space: widths of a portion to be left as a pattern and a portion to be removed are 80 nm / 80 nm, respectively)
Can be exposed at a resolution of, for example, 34 m
A predetermined area such as an area corresponding to an optical disk having a diameter of m can be collectively exposed. In the actual exposure, a scan exposure method is used in which exposure is performed while driving the mask and the resist master in synchronization with each other, and the XY stage ST on which the resist master is mounted is sequentially moved in a stepwise manner to perform exposure with the same mask pattern. Scan exposure can be performed. For example, when a resist master having a diameter of 200 mm is used, an area corresponding to the above-described optical disk having a diameter of 34 mm can be taken as four areas.
Repeat several times.

The mask MK used in the EB stepper is, for example, a stencil mask in which a region corresponding to a pit is etched and opened in a silicon substrate. For example, a pit pattern having a size four times as large as a pattern to be drawn is formed. ing. For example, a pit of 80 nm has a size of 320 nm on a 4 × stencil mask, which is a pattern size that can be easily formed by a normal laser cutting apparatus as shown in FIG.

Using the above-described EB stepper, an optical disk can be manufactured as follows. First, FIG.
A resist film 1 is formed on a silicon substrate 10 as shown in FIG.
A resist master RD on which a film 1 is formed is prepared. The silicon substrate 10 has, for example, a diameter of 200 mm and a thickness of 0.7 mm, and has, for example, a precisely polished surface. The resist film 11 is, for example, a chemically amplified resist in addition to an acrylic resin-based resist dedicated to an electron beam, and is formed to a thickness of several tens to 100 nm by a spin coating method or the like.

Next, using the EB stepper shown in FIG.
The resist film 11 is exposed to an electron beam in a pattern that exposes a region to be a groove or a region to be a pit of the disk substrate, and is subjected to a developing process using a dedicated developing solution.
As shown in FIG. 6, a resist film 11a having a pattern that opens a region to be a groove or a region to be a pit of a disk substrate. By using an EB stepper, the resist film 1
The pattern 1a has, for example, 160 nm and an opening width of 80 n.
m, or a pit pattern having a track pitch of 160 nm and a minimum pit length of 80 nm.

Next, as shown in FIG. 4A, for example, a nickel plating process is performed to form a stamper 12 on the silicon substrate 10 and the resist film 11a. On the surface of the stamper 12, irregularities having a pattern opposite to that of the groove 11b formed by the resist film 11a are transferred, and
a is formed. According to the pattern of the resist film 11a, the pattern of the protrusions 12a has a pitch of 160 nm,
A spiral pattern having a width of 80 nm or a pit pattern having a track pitch of 160 nm and a minimum pit length of 80 nm can be used.

Next, as shown in FIG. 4B, the stamper 12 is released from the silicon substrate 10 and the resist film 11a.

Next, as shown in FIG. 5 (a), the stamper 12 obtained as described above is fixed in a cavity composed of dies (MD1, MD2) to form an injection molding die. At this time, the stamper 12 is installed such that the projection forming surface 12a 'faces the inside of the cavity. By injecting, for example, a resin such as polycarbonate in a molten state from the injection port I of the mold into the cavity of the above-described injection mold, FIG.
As shown in FIG. 2B, the disk substrate 13 is formed on the concave / convex pattern of the stamper 12. Here, the disk substrate 1
3 is transferred with a groove 13a serving as a groove pattern or a pit pattern, which is a concave / convex pattern reverse to the concave / convex pattern on the surface of the stamper 12. According to the pattern of the protrusion 12a of the stamper 12, the pattern of the groove 13a has a pitch of 1
A spiral pattern having a width of 60 nm and a width of 80 nm, or a track pitch of 160 nm and a minimum pit length of 80 nm
nm pit pattern.

By releasing the mold from the above injection mold,
As shown in FIG. 6A, a disk substrate 13 having a groove 13a serving as a groove pattern or a pit pattern formed on the surface is obtained. Next, as shown in FIG.
After dust is removed by blowing a gas such as air or nitrogen gas onto the surface of the disk substrate 13, the optical recording film 14 having a reflective film, a dielectric film, a recording film, and a laminate of dielectric films is formed by, for example, a sputtering method. Are formed in this order. The recording film is, for example, a phase-change optical recording film,
A magneto-optical recording film or a recording film containing an organic dye can be used. Alternatively, in the case of a ROM type optical disk, the optical recording film is formed of a reflective film such as an aluminum film. Next, as shown in FIG.
A protective film 15 is formed on the upper layer 4. Thus, an optical disk having the structure shown in FIG. 1 can be manufactured.

According to the optical disk manufacturing method of the present embodiment, an optical recording medium can be manufactured by miniaturizing an information pit pattern or a groove pattern.
Further, according to the method of manufacturing an optical recording medium manufacturing master and a stamper used in the process of manufacturing an optical disk of the present embodiment, the optical recording medium manufacturing method used in the method of manufacturing an optical recording medium capable of miniaturizing an information pit pattern or a groove pattern is provided. Master disks or stampers can be manufactured.

Second Embodiment This embodiment is substantially the same as the first embodiment,
When performing electron beam exposure using an EB stepper, a pattern corresponding to a plurality of optical disks is exposed on one resist master by step and scan exposure, and a plurality of disk substrates are simultaneously formed.

First, as shown in the perspective view of FIG.
The electron beam EB is emitted from the electron beam column EBC to the resist master RD on which the resist film 11 is formed on the silicon substrate 10, and the step and scan exposure are performed for each area corresponding to one optical disc, and the Exposure area (EXa, EXb, EXc, EX)
d). The above resist master RD is 200m in diameter
If it is m, four optical disks having a diameter of 34 mm can be secured.

Next, as shown in the perspective view of FIG.
The resist film patterns (11aA, 11aB, 11aC,
11aD).

Next, as shown in the perspective view of FIG. 8 (a1) and the sectional view (a2) corresponding to the AA ′ section in FIG. 8 (a1), the above-mentioned resist master is subjected to nickel plating or the like. The stamper 12 to which the concave and convex pattern of the resist master is transferred is formed, and the mold is released from the resist master. The stamper 12 has a convex pattern (1) serving as four optical disks.
2aA, 12aB, 12aC, 12aD) are transferred.

Next, as shown in FIG. 8 (b), the stamper 12 obtained above is fixed in a cavity composed of dies (MD1, MD2), and a mold for injection molding is formed. Inside, a resin such as polycarbonate in a molten state is injected from the injection port I of the mold.

By the above-described injection molding, groove patterns (fourth optical disc) as shown in the perspective view of FIG. 9A1 and the cross-sectional view of FIG. 13aA, 13aB, 13aC, and 13aD) are formed on the disk substrate 13.

A plurality of medium substrates (13A, 13B, 13C, 13D) are cut out from the disk substrate 13 by using a high-output laser or the like for each pattern corresponding to one optical disk. I do. In the subsequent steps, as in the first embodiment, an optical recording film is formed and a protective film is formed to obtain a desired optical disk.

According to the method for manufacturing an optical disk of the present embodiment, an optical recording medium can be manufactured by miniaturizing an information pit pattern or a groove pattern, as in the first embodiment. Since four disk substrates can be obtained by one molding from the stamper, four times the productivity of the conventional one can be achieved in the molding process.

The present invention is not limited to the above embodiment. For example, the layer configuration of the optical recording film is not limited to the configuration described in the embodiment, but may be various structures according to the material of the recording film. In addition to a phase change type optical recording medium, the present invention can be applied to a magneto-optical recording medium and an optical disk medium using an organic dye material. In addition, various changes can be made without departing from the scope of the present invention.

[0070]

According to the method of manufacturing an optical recording medium manufacturing master and a stamper used in the process of manufacturing an optical disk of the present invention and the method of manufacturing an optical disk using the same, for example, an information pit pattern or a groove pattern can be A master or stamper for manufacturing an optical recording medium used in a method for manufacturing an optical recording medium that can be manufactured by miniaturizing the length or width to a size of 100 nm or less can be manufactured, and 50 Gbit / in.
An optical disk having a surface density of ch ² can be manufactured. Further, for example, it is possible to manufacture a small-diameter optical disk having a diameter of 40 mm or less with a higher productivity than before.

[Brief description of the drawings]

FIG. 1A is a schematic perspective view showing a state of light irradiation of an optical disc according to a first embodiment of the present invention.
1B is a schematic sectional view, and FIG. 1C is an enlarged sectional view of a main part of the schematic sectional view of FIG.

FIG. 2 is a collective reduction transfer type electron beam writing apparatus (EB)
It is a schematic block diagram of a (stepper).

FIGS. 3A and 3B are cross-sectional views showing a manufacturing process of an optical disk manufacturing method according to the first embodiment of the present invention. FIG. 3A shows a process until a resist master is formed, and FIG. The steps up to the processing are shown.

FIG. 4 is a sectional view showing a step subsequent to that of FIG. 3;
(A) shows up to the step of forming the stamper, and (b) shows the step up to the step of releasing the stamper.

FIG. 5 is (a) a schematic view and (b) a cross-sectional view of an injection molding step showing a step subsequent to FIG.

FIG. 6 is a sectional view showing a step subsequent to that of FIG. 5;
(A) shows up to the step of forming a disk substrate, (b) shows up to the step of forming an optical recording film, and (c) shows up to the step of forming a protective film.

FIGS. 7A and 7B are diagrams showing a manufacturing process of an optical disk manufacturing method according to a second embodiment of the present invention, wherein FIG. 7A is a perspective view of a process of pattern exposure of a resist master, and FIG. FIG. 4 is a perspective view of a resist master obtained by the above method.

FIG. 8 is a sectional view showing a step subsequent to that of FIG. 7;
(A1) and (a2) are a perspective view and a sectional view of the obtained stamper, and (b) is a schematic sectional view of an injection molding process.

FIG. 9 is a sectional view showing a step subsequent to that of FIG. 8;
(A1) and (a2) are a perspective view and a sectional view of the obtained disk substrate, and (b) is a perspective view of an individual disk substrate obtained by cutting.

FIG. 10 is a schematic sectional view of an optical disc according to a conventional example.

11A is a schematic configuration diagram of a cutting apparatus (exposure apparatus), and FIG. 11B is a perspective view of a main part.

FIG. 12 is a cross-sectional view showing a manufacturing process of an optical disk manufacturing method according to a conventional example, in which (a) shows a process up to forming a resist master and (b) shows a process up to a process of patterning a resist film. Show.

13 is a cross-sectional view showing a step that follows the step shown in FIG. 12; FIG. 13 (a) shows the steps up to the step of forming the stamper, and FIG. 13 (b) shows the steps up to the step of releasing the stamper.

FIG. 14 is (a) a schematic view and (b) a cross-sectional view of an injection molding step showing a step subsequent to FIG.

15 is a cross-sectional view showing a step that follows the step shown in FIG. 14; FIG.
(B) shows up to the step of forming the optical recording film, and (c) shows the step up to the step of forming the protective film.

[Explanation of symbols]

10 ... Silicon (glass) substrate, 11, 11a, 11a
A, 11aB, 11aC, 11aD ... resist film, 12
... Stamper, 12a, 12aA, 12aB, 12aC,
12aD: convex portion, 12 ': convex portion forming surface, 13: disk substrate, 13A, 13B, 13C, 13D: cut-out disk substrate, 13a: groove, 13aA, 13aB, 13
aC, 13aD: groove pattern, 13 ': molten resin, 14
... optical recording film, 15 ... protective film, AOM ... acousto-optic element,
CH: Center hole, CL: Condenser lens, DC:
Optical disk, DR: drive direction, EB: electron beam,
EBC: electron beam column, EG: electron gun, EOM: electro-optical element, EX, EXa, EXb, EXc, EXd ...
Exposure area, GL: gas laser, I: injection port, L1, L
2, L3, L4 ... lens, LT, LT1, LT2 ... (laser) light, M1, M2, M3 ... mirror, MD1, MD2
... Mold, MK ... Mask, MT ... Movable table, OL ... Objective lens, PBS1, PBS2 ... Polarizing beam splitter, PD1, PD2 ... Photodiode, PSD ... Spot position detecting element, QWP ... 1/4 wavelength plate, RD ... Resist master, SD: spindle direction, ST: XY stage.

Claims (16)

[Claims] 1. A method for producing an optical recording medium manufacturing master used for transferring an irregular shape onto a surface of a medium substrate of an optical recording medium, the method comprising using an enlarged mask along the irregular pattern.
An optical recording medium comprising: a step of exposing a resist film formed on a master substrate by an electron beam lithography method of collectively exposing a predetermined area while reducing the pattern of the enlarged mask; and a step of developing the resist film Manufacturing method of master for production. 2. The method for manufacturing an optical recording medium manufacturing master according to claim 1, wherein a mask having a pattern magnified four times or more as large as the concavo-convex pattern is used as the magnifying mask. 3. The method according to claim 2, wherein a stencil mask having a pattern drawn by a laser beam recorder is used as the enlargement mask. 4. In the step of exposing the resist film,
2. The method according to claim 1, wherein an area corresponding to an entire optical recording medium is collectively exposed as the predetermined area. 5. In the step of exposing the resist film,
Each time the area corresponding to the entire one optical recording medium is collectively exposed, the step of sequentially moving the exposure area and repeatedly exposing the area corresponding to the entire optical recording medium is repeated. 5. The method according to claim 4, wherein a pattern corresponding to a plurality of optical recording media is exposed thereon. 6. The method according to claim 1, wherein the uneven shape is a pattern of a guide groove for dividing a track area of the optical recording medium. 7. The method according to claim 1, wherein the uneven shape is a pattern of pits of the optical recording medium. 8. A method for manufacturing a stamper for manufacturing an optical recording medium, which is used to transfer an uneven shape to a surface of a medium substrate of an optical recording medium, comprising: using an enlarged mask along the pattern of the uneven shape;
A step of exposing a resist film formed on the master substrate by an electron beam lithography method of collectively exposing a predetermined area while reducing the pattern of the enlarged mask, a step of developing the resist film, Forming a stamper on which a concavo-convex shape composed of a resist film and a master substrate is transferred, the method comprising the steps of: 9. The method of manufacturing an optical recording medium according to claim 8, wherein said stamper is formed of nickel. 10. A method for manufacturing an optical recording medium having a medium substrate having an uneven shape transferred to a surface thereof, the method comprising: using an enlarged mask along a pattern of the uneven shape;
A step of exposing a resist film formed on a master substrate by an electron beam lithography method of collectively exposing a predetermined area while reducing the pattern of the enlarged mask, a step of developing the resist film, and a step of developing the developed resist A step of forming a stamper on which the concavo-convex shape composed of the film and the master substrate has been transferred; a step of forming a medium substrate on which the concavo-convex shape of the stamper has been transferred; A method for manufacturing an optical recording medium, comprising: forming an optical recording film; and forming a protective film on the optical recording film. 11. In the step of exposing the resist film, every time a region corresponding to the entirety of the one optical recording medium is collectively exposed, the exposure area is sequentially moved to correspond to the entirety of the one optical recording medium. The step of collectively exposing regions to be exposed is repeated, and a pattern corresponding to a plurality of optical recording media is exposed on one master, and the step of forming the stamper has a pattern corresponding to a plurality of optical recording media. Forming a stamper; forming a medium substrate having a pattern corresponding to a plurality of optical recording media in the step of forming the medium substrate; 11. The production of the optical recording medium according to claim 10, wherein the optical recording medium is cut out for each pattern corresponding to one optical recording medium, and a plurality of medium substrates serving as individual optical recording media are formed. Method. 12. A step of forming a stamper to which the irregular shape is transferred, the step of forming an intermediate member having the transferred concave and convex shape formed of the developed resist film and a master substrate; 11. A method of manufacturing an optical recording medium according to claim 10, comprising a step of forming a stamper to which the concave and convex shapes are transferred. 13. The method according to claim 10, wherein a phase-change optical recording film is formed as the optical recording film. 14. The method for manufacturing an optical recording medium according to claim 10, wherein a magneto-optical recording film is formed as said optical recording film. 15. The method for manufacturing an optical recording medium according to claim 10, wherein an optical recording film including an organic dye layer is formed as said optical recording film. 16. The method for manufacturing an optical recording medium according to claim 10, wherein a reflection film is formed as said optical recording film.