JP2002342987A - Master disk for manufacturing optical recording medium, stamper for manufacturing optical recording medium and method of manufacturing optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical recording medium which is capable of making groove patterns or information bit patterns fine and more particularly making the width of the grooves or information bits narrower and a method of manufacturing a master disk and stamper to be used for the same. SOLUTION: Resist films are formed according to the patterns of the guide grooves segmenting track regions or the patterns of the bits and rugged shapes are formed on a master disk substrate 10. Next, the side walls of the recessed parts 10a of the rugged shapes are formed with side walls 12a to narrow the width of the recessed parts, there by, the master disk is formed. The stamper 13 consisting of nickel, etc., transferred with the rugged shapes of the resultant master disk substrate 10 is formed. The medium substrate transferred with the rugged shapes of the resultant stamper is formed and an optical recording film and 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.

[0003] In a normal configuration of an optical disk apparatus for recording or reproducing an optical disk such as a CD, a light source for irradiating light of a wavelength λ for recording or reproduction, and an optical recording film of an optical recording medium for emitting light emitted from the light source. The optical system includes an optical system including an objective lens (condensing lens) having a numerical aperture of NA and a light receiving element for detecting light reflected from the optical recording film.

[0004] In the reproduction or recording of the optical disk, the spot size φ of the light on the optical recording film is:
Generally, it is given by the following equation (1).

[0005]

## EQU1 ## φ = λ / NA (1)

The spot size φ of the light directly affects the recording density of the optical recording medium, and the smaller the spot size φ, the higher the density of recording and the larger the capacity. That is,
The smaller the light wavelength λ and the larger the numerical aperture NA of the objective lens, the smaller the spot size φ, indicating that high-density recording becomes possible.

For example, in the above-mentioned CD system, the wavelength of the light source is in the near infrared region (about 780 nm), the numerical aperture of the objective lens is about 0.45, and a phase change type recording film is used as the recording film. Further, according to the irregularities formed on the disk substrate, the optical recording film has an irregular shape, and the optical recording film having the irregular shape is a side closer to the irradiation side of the recording or reproducing light. Only the portion of the optical recording film corresponding to the convex portion of the concavo-convex shape (hereinafter referred to as a land L) has a recording area RA
And a concave portion having a concave-convex shape (hereinafter referred to as a groove G) which is farther from the irradiation side of the recording or reproducing light.
In a configuration in which the optical recording film corresponding to the above is not used as the recording area RA, a recording capacity of about 700 MB is realized in the case of an optical disc having a diameter of 120 mm.

[0008] Research on further increasing the density of optical discs is ongoing, for example, in the literature "Optical diss."
k recording using a GaN b
lue-violet laser diode "(I
Chimura et al., Jpn. J. Appl. Phys
s. , Vol. 39 (2000), pp937-94
In 2), a blue-violet semiconductor laser and a numerical aperture of 0.85
There has been proposed a method for realizing a storage capacity exceeding 22 Gbytes on a DVD-size optical disk by using the two-group objective lens.

By the way, when the numerical aperture of the objective lens becomes large, generally, the tolerance of the disk tilt in the optical disk apparatus decreases. Coma W _31, which relative to the inclination angle theta, generated with respect to the optical axis, the document "Aplanatic con
period required to reprod
use jitter-free signalinsin
optical disk system "(Kub
ota et al., Appl. Opt. , Vol. 26 (198
7), pp3961-3973), the following formula (2)
Which is approximately proportional to the cube of the numerical aperture NA and the thickness t of the protective film (the film formed on the optical recording film) of the optical disk. In the equation (2), n is the refractive index of the protective film.

[0010]

(Equation 2)

Therefore, the value of the allowable coma aberration W ₃₁ is defined as λ
In the case of / 4, in the optical disk device with the numerical aperture increased to 0.85, the thickness of the protective film of the optical disk must be reduced to about 0.1 mm in order to ensure the same disk tilt tolerance as the DVD reproducing device. Is required.

Referring to the drawings, an optical disk compatible with the above-mentioned shorter wavelength and higher capacity than a higher numerical aperture will be described. FIG. 7A is a schematic perspective view showing how the optical disk is irradiated with light. 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. 7B is a schematic sectional view, and FIG.
FIG. 8C 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 14 made of polycarbonate or the like having a thickness of about 1.1 mm, a groove 14a for dividing a track area is provided.
For example, an optical recording film 15 in which a reflective film, a dielectric film, a recording film, a dielectric film, and the like are stacked in this order is formed. The layer configuration and the number of layers of the optical recording film 15 differ depending on the type and design of the recording material. Further, an optically transparent protective layer 16 having a thickness of 0.1 mm is formed on the optical recording film 15.

When recording or reproducing data on or from the above-mentioned optical disk, the light L such as a laser beam is irradiated by the objective lens OL.
The optical recording film 15 is irradiated with T from the protective layer 16 side. During reproduction of the optical disk, return light reflected by the optical recording film 15 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 above-described optical disk, the optical recording film 15 also has an uneven shape in accordance with the groove 14a provided on one surface of the disk substrate 15, and the groove 14a
Divides the track area. Hereinafter, a region that protrudes toward the protective layer 16 when viewed from the disk substrate 14 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.

The read / write (ROM) type optical disk can be obtained by forming the concave and convex shape of the disk substrate 14 as pits having a length corresponding to recording data and using an optical recording film as a reflective film such as an aluminum film. You can also.

A method for manufacturing the above optical disk will be described. FIG. 8A is a schematic configuration diagram of a cutting apparatus (exposure apparatus) used in the above manufacturing method, and FIG.
FIG. As a light source, for example, an oscillation wavelength of 35
A 1-nm Kr gas (ion) laser GS is provided, and on the optical axis thereof, an electro-optical element EOM, a polarizing beam splitter PBS1, a mirror M1, a lens L1,
Acousto-optic element AOM, lens L2, mirror M2, lens L3, lens L4, DCM, mirror M3, objective lens O
L is arranged at a predetermined position. 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 GS
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. As light.

In the above-described cutting apparatus, the resist master RD is rotationally driven in the spindle direction SD by a spindle motor (not shown), and the laser beam LT1 is fed while the movable table MT is fed by a predetermined width in the radial direction of the resist master RD. 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 always keep the focal length of the objective lens on 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.

Using the above-described cutting device, an optical disk can be manufactured as follows. First, FIG.
A resist film 11 is formed on a glass substrate 10 as shown in FIG.
A resist master RD on which is formed a film 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. Also, the resist film 1
A film 1 is formed by spin coating with a thickness of 100 nm using, for example, a photosensitive positive photoresist which is exposed to ultraviolet rays. The solvent remaining in the resist film 11 is removed by baking at several tens of degrees Celsius.

Next, the resist film 11 is exposed to light using a cutting device shown in FIGS. 8A and 8B in a pattern for exposing a region to be a groove of the disk substrate, and is developed with an alkali developing solution or the like. And FIG. 9 (b)
As shown in FIG. 7, a resist film 11a having a pattern that opens a region to be a groove of the disk substrate is used.

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

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

Next, as shown in FIG. 11 (a), the stamper 13 obtained as described above is fixed in a cavity composed of dies (MD1, MD2) to form an injection mold.
At this time, the stamper 13 is installed such that the projection forming surface 13a '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. 1B, a disk substrate 14 is formed on the concave / convex pattern of the stamper 13. Here, a groove 14 a is formed on the disk substrate 14, the groove 14 a serving as an uneven pattern having a pattern opposite to that of the surface of the stamper 13.

By releasing the mold from the above injection mold,
A disk substrate 14 having a groove 14a formed on the surface as shown in FIG. Next, as shown in FIG. 12 (b), after dust such as air or nitrogen gas is blown onto the surface of the disk substrate 14 to remove dust, the reflection film, the dielectric film, and the recording film are formed by, for example, a sputtering method. ,
The optical recording film 15 having a dielectric film stack is formed in this order. Next, as shown in FIG. 12C, a protective film 15 is formed on the optical recording film 15. Thus, an optical disk having the structure shown in FIG. 7 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 14 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. 8, all the mechanical systems are mounted on an air base so as not to be affected by external vibrations 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 (3) from the process factor K taking

[0029]

P = K (λ / NA) (3)

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

[0031]

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. In order to achieve this with the same signal processing on one side of a disk having a diameter of 12 cm, a groove pattern having a track pitch of 0.4 μm or less is required for a rewritable optical disk. According to the optical disk manufacturing method described above, it is not easy to form a groove pattern having a track pitch of 0.4 μm or less.

In a rewritable optical disk using a magneto-optical recording film or a phase change film, in order to improve the cross erase characteristic at the time of data writing, a deep groove as narrow as possible (narrow), a so-called deep groove shape. Is suitable. In order to form such a fine and deep groove, as can be seen from the above equation (3), the wavelength of the laser beam is reduced and the NA of the objective lens is increased.
However, the NA of the objective lens is almost limited to a value of about 0.9 at present from the viewpoint of lens design / manufacturing accuracy.

The converging spot size W (half width) of the laser beam is, as in the case of the above-described resolution, the laser wavelength λ,
From the numerical aperture NA of the objective lens and the coefficient 0.52 assuming a Gaussian beam, it is approximated by the following equation (4).

[0034]

W = 0.52 × (λ / NA) (4)

For example, when λ = 351 nm and NA = 0.9 are substituted, W = 0.2 μm, and the width of the groove pattern in the resist film cannot be further reduced.
Therefore, for example, at a track pitch of 0.4 μm, 0.1
It is extremely difficult with the current technology to form a fine groove pattern having a width of μm on a resist film having a thickness of 70 nm.

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

[0037]

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:
A method of manufacturing an optical recording medium manufacturing master used for transferring an uneven shape to a surface of a medium substrate of an optical recording medium, the method including: forming an uneven shape on a master substrate; Forming a sidewall for reducing the width of the concave portion.

In the above method of manufacturing a master for producing an optical recording medium according to the present invention, preferably, the step of forming the side wall comprises coating the inside of the recess on the surface of the master substrate on which the uneven shape is formed. Forming a sidewall layer on the entire surface, and etching back the entire surface except for a portion of the sidewall layer in contact with the side wall of the concave portion.

In the method of manufacturing a master for manufacturing an optical recording medium according to the present invention, preferably, the concave and 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.

In the above method of manufacturing a master for producing an optical recording medium according to the present invention, preferably, the step of forming an uneven shape on the master substrate includes the step of forming the uneven shape on the uneven surface of the master substrate. The method includes a step of forming a resist film along a pattern that opens a portion to be a concave portion, and a step of performing anisotropic etching using the resist film as a mask.

In the method of manufacturing a master for manufacturing an optical recording medium according to the present invention, a resist film is formed in accordance with a pattern of a guide groove or a pattern of a pit which divides a track area.
An irregular shape is formed on the master substrate by performing anisotropic etching or the like. Next, the inside of the concave portion is covered on the concave / convex shape forming surface, a sidewall layer is formed on the entire surface, and the entire surface is etched back while leaving the side wall layer in contact with the side wall of the concave portion. Is formed on the side wall of the substrate to reduce the width of the concave portion.

According to the method of manufacturing a master for manufacturing an optical recording medium of the present invention, an optical recording medium can be manufactured by miniaturizing a groove pattern or an information pit pattern, particularly, narrowing the width of the groove or the information pit. The master for producing an optical recording medium used in the method of (1) can be manufactured.

Further, 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 the surface of a medium substrate of an optical recording medium. A method for manufacturing a stamper for use, wherein a step of forming an uneven shape on the master substrate, a step of forming a sidewall that narrows the width of the concave portion on the side wall of the concave portion of the uneven shape, and the uneven shape of the master substrate Forming a transferred stamper.

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 irregular shape is formed on a master substrate, and a sidewall for reducing the width of the concave portion is formed on the side wall of the concave portion having the irregular shape. A stamper made of nickel or the like to which the uneven shape of the master substrate has been transferred is formed.

According to the method of manufacturing a stamper for manufacturing an optical recording medium of the present invention, the optical recording medium can be manufactured by miniaturizing the groove pattern or the information pit pattern, particularly, by narrowing the width of the groove or the information pit. The stamper for manufacturing an optical recording medium used in the manufacturing method of (1) can be manufactured.

Further, in order to achieve the above object, a method for manufacturing an optical recording medium according to the present invention is a method for manufacturing an optical recording medium having a medium substrate having a concave and convex shape transferred onto a surface thereof. Forming a concave-convex shape, forming a sidewall on the side wall of the concave portion of the concave-convex shape to reduce the width of the concave portion, forming a stamper to which the concave-convex shape of the master substrate is transferred, Forming a medium substrate on which the irregularities are transferred, forming an optical recording film on the irregularities forming surface of the medium substrate, and forming a protective film on the optical recording film. Have.

In the method for manufacturing an optical recording medium according to the present invention, preferably, the step of forming the stamper on which the irregular shape of the master substrate is transferred includes the step of transferring the intermediate shape of the master substrate onto which the uneven shape is transferred. A step of forming a 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 irregular shape is formed on the master substrate, and a sidewall for reducing the width of the concave portion is formed on the side wall of the concave portion having the irregular shape.
Next, a stamper to which the concave and convex shape of the master substrate is transferred is formed, and a medium substrate to which the concave and 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. In order to form a stamper on which the irregular shape of the master substrate is transferred,
A stamper may be formed by forming an intermediate member to which the uneven shape is transferred, and transferring the uneven shape.

According to the method for manufacturing an optical recording medium of the present invention described above, it is possible to manufacture an optical recording medium by miniaturizing a groove pattern or an information pit pattern, in particular, by narrowing the width of the groove or the information pit.

[0052]

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.

FIG. 1A is a schematic perspective view showing how the optical disk according to this embodiment is irradiated with light. 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 optical recording film in the optical disc DC is irradiated with light LT such as laser light in a blue to blue-violet region by, for example, an objective lens OL having a numerical aperture of 0.8 or more. 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 14 made of polycarbonate or the like having a thickness of about 1.1 mm, a groove 14a for dividing a track area is provided.
For example, an optical recording film 15 in which a reflective film, a dielectric film, a recording film, a dielectric film, and the like are stacked in this order is formed. The layer configuration and the number of layers of the optical recording film 15 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 layer 16 having a thickness of 0.1 mm is formed on the optical recording film 15.

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 15 is irradiated with T from the protective layer 16 side. During reproduction of the optical disk, return light reflected by the optical recording film 15 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 15 also has an uneven shape in accordance with the groove 14a provided on one surface of the disk substrate 15, and the groove 14a
Divides the track area. Hereinafter, a region that protrudes toward the protective layer 16 when viewed from the disk substrate 14 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 groove pitch is, for example, about 0.4 μm, and the width of the groove is, for example, 0.1 μm.
m, and the depth of the groove is about 70 nm, and the groove has a fine width which has been difficult to form conventionally.

Further, by forming the concave and convex shape of the disk substrate 14 as pits having a length corresponding to the 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 obtained. You can also.

A method for manufacturing the above optical disk will be described. FIG. 8A is a schematic configuration diagram of a cutting apparatus (exposure apparatus) used in the method of manufacturing an optical disk of the present embodiment, and FIG. 8B is a perspective view of a main part. This is a configuration common to that used. For example, a Kr or Ar gas (ion) laser GS having an oscillation wavelength of 351 nm is provided as a light source, and an electro-optical element EOM, a polarization beam splitter PBS1, a mirror M1, a lens L1, a lens L1, and an acousto-optical element AOM are provided on the optical axis as optical elements. , Lens L2, mirror M2, lens L3,
The lens L4, DCM, mirror M3, and objective lens OL are arranged at predetermined positions. The optical element before the mirror M2 is fixed on a fixed surface plate, while the lens L
The third and subsequent optical elements are mounted on the 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 GS
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. As light.

In the above-described 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 sent 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 automatic 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.

Using the above-described cutting device, an optical disk can be manufactured as follows. First, FIG.
A resist film 11 is formed on a glass substrate 10 as shown in FIG.
A resist master RD on which is formed a film 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. Also, the resist film 1
A film 1 is formed by spin coating with a thickness of 100 nm using, for example, a photosensitive positive photoresist which is exposed to ultraviolet rays. The solvent remaining in the resist film 11 is removed by baking at several tens of degrees Celsius.

Next, the resist film 11 is exposed to light using a cutting device shown in FIGS. 8A and 8B in a pattern for exposing a region to be a groove of the disk substrate, and is developed with an alkali developing solution or the like. And FIG. 2 (b)
As shown in FIG. 7, a resist film 11a having a pattern that opens a region to be a groove of the disk substrate is used.

In the above exposure step, for example, the laser wavelength λ = 351 nm and the numerical aperture NA of the objective lens = 0.
9. If the process factor K = 0.5, the equation (3)
, The resolution P = 0.2 μm, and the track pitch is 0.
A 4 μm groove or a resist film pattern of 0.2 μmL / S (line / space: width of a portion to be left as a pattern and a width of a portion to be removed) is 0.2 μm / 0.2 μm, respectively, is resolved.

Next, as shown in FIG. 2C, dry etching is performed using the resist film 11a as a mask, and the pattern of the resist film 11a is transferred to the glass substrate 10 so that the side walls become substantially vertical. A groove 10a having the same pattern as 11a is formed. Here, as an etching gas to be used, for example, a chlorofluorocarbon-based gas (CF ₄ , CHF _3, etc.)
The etching is performed in a so-called reactive ion etching (RIE) mode in which ions of an etching gas generated in the plasma are vertically incident on the glass substrate 10. The groove pattern to be formed has a depth of, for example, 70 nm.
And the pitch and width are 0.4 μm, 0.
2 μm.

Next, as shown in FIG. 3A, a resist film 1 is formed by oxygen plasma treatment or ashing.
Remove 1a.

Next, as shown in FIG. 3B, for example, sputtering in a vacuum or CVD (Chemical Vapor D)
A silicon-based material such as silicon nitride or another material is deposited on the entire surface to a thickness of 50 nm by an eposition method to form a sidewall layer 12. At this time, the film forming conditions are optimized, and the film is formed so as to cover the bottom, side and land of the groove with a uniform film thickness.

Next, as shown in FIG. 3C, the entire surface is etched back in an RIE mode using, for example, a chlorofluorocarbon-based gas, so that the side wall layer is removed while leaving a portion in contact with the side wall of the groove. And the sidewall 12a
To form Side wall 1 formed as described above
Due to the formation of 2a, a groove (groove) 10b having a reduced width is obtained. For example, when the film thickness of the sidewall layer is 50 nm, the width of the sidewall is also 50 nm, and the groove narrowed by the sidewall.
The width of 10b is about 0.1 μm. Since the sidewall layer has been removed until the groove bottom is exposed,
Groove 10b narrowed by sidewall
Remains at about 70 nm.

Next, as shown in FIG. 4A, a stamper 13 is formed on the glass substrate 10 by, for example, nickel plating. On the surface of the stamper 13, irregularities of a pattern opposite to the irregularities of the pattern formed by the glass substrate 10 having the grooves (grooves) 10b narrowed by the sidewalls formed thereon are transferred to form the projections 13a. The groove (groove) 10b narrowed by the sidewall has a width of 0.1 μm, a depth of 70 nm, and a pitch of 0.4 μm.
1 μm, height 70 nm, pitch 0.4 μm.

Next, as shown in FIG. 4B, the stamper 13 is released from the resist film 11a on the glass substrate 10.

Next, as shown in FIG. 5A, the stamper 13 obtained as described above is fixed in a cavity formed by the dies (MD1 and MD2) to form an injection mold. At this time, the stamper 13 is installed such that the projection forming surface 13a '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 (b), a disk substrate 14 is formed on the concave / convex pattern of the stamper 13. Here, the disk substrate 1
4 is transferred to a groove (groove) 14a which is formed in a pattern opposite to that of the surface of the stamper 13. Since the convex portion had a width of 0.1 μm, a height of 70 nm, and a pitch of 0.4 μm, the width of the groove (groove) 14 a was 0.1 μm.
The depth is 70 nm and the pitch is 0.4 μm.

By releasing the mold from the above injection mold,
As shown in FIG. 6A, a disk substrate 14 having a groove (groove) 14a formed on the surface is obtained. Next, FIG.
As shown in (b), after dust such as air or nitrogen gas is blown onto the surface of the disk substrate 14 to remove dust,
For example, by a sputtering method or the like, a reflective film, a dielectric film, a recording film, and an optical recording film 15 having a laminate of dielectric films.
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. Next, FIG.
As shown in (1), a protective film 15 is formed on the optical recording film 15. Thus, an optical disk having the structure shown in FIG. 7 can be manufactured.

In the above exposure step, the exposure laser beam 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 14 can be 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.

According to the optical disk manufacturing method of the present embodiment, an optical recording medium can be manufactured by miniaturizing a groove pattern or an information pit pattern, in particular, reducing the width of the groove or the information pit. In addition, according to the method for manufacturing the master and stamper for manufacturing an optical recording medium used in the process of manufacturing the optical disc of the present embodiment, the groove pattern or the information pit pattern is miniaturized, particularly, the width of the groove or the information pit is reduced. An optical recording medium manufacturing master or a stamper used in the method for manufacturing an optical recording medium that can be used can be manufactured.

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. As the sidewall for reducing the width of the groove of the master, various materials other than silicon nitride can be used as long as the material can be a member for reducing the width of the groove. In addition, various changes can be made without departing from the scope of the present invention.

[0077]

According to the master for producing an optical recording medium and the method for producing a stamper used in the process of producing an optical disk according to the present invention, the groove pattern or the information pit pattern can be miniaturized, in particular, the width of the groove or the information pit can be reduced. An optical recording medium manufacturing master or a stamper used in the method for manufacturing an optical recording medium that can be manufactured by the method can be manufactured.

According to the optical disk manufacturing method of the present invention,
An optical recording medium can be manufactured by miniaturizing a groove pattern or an information pit pattern, in particular, reducing the width of the groove or the information pit.

[Brief description of the drawings]

FIG. 1A is a schematic perspective view showing a state of light irradiation on an optical disc according to an 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.

FIGS. 2A and 2B are cross-sectional views illustrating a manufacturing process of an optical disk manufacturing method according to an embodiment of the present invention. FIG. 2A illustrates a process up to forming a resist master, and FIG. 2B illustrates pattern processing of a resist film. (C) shows the process up to the step of forming a groove in the glass substrate.

FIG. 3 is a sectional view showing a step subsequent to that of FIG. 2;
(A) shows up to the step of removing the resist film, (b) shows up to the step of forming a sidewall layer, and (c) shows up to the step of forming a sidewall.

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.

7A is a schematic perspective view showing a state of light irradiation of an optical disc according to a conventional example, FIG. 7B is a schematic cross-sectional view, and FIG. 7C is FIG. It is sectional drawing which expanded the principal part of the schematic sectional drawing of b).

FIG. 8A shows a cutting apparatus (exposure apparatus).
FIG. 8B is a perspective view of a main part.

9A and 9B are cross-sectional views illustrating a manufacturing process of a method of manufacturing an optical disk according to a conventional example, in which FIG. 9A illustrates a process up to forming a resist master and FIG. 9B illustrates a process up to a process of patterning a resist film. Show.

10 is a cross-sectional view showing a step subsequent to that of FIG. 9, in which (a) shows a step until a stamper is formed, and (b) shows a step until the stamper is released.

FIG. 11 is (a) a schematic view and (b) a cross-sectional view of an injection molding step showing a step continued from FIG.

FIG. 12 is a sectional view showing a step that follows the step shown in FIG. 11;
(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 disk substrate, 10a groove, 10b groove narrowed by sidewall, 11, 11a resist film,
12 ... sidewall layer, 12a ... sidewall,
13 ... stamper, 13a ... convex part, 13 '... convex part forming surface,
14 disk substrate, 14a groove, 14 'molten resin,
Reference numeral 15: optical recording film, 16: protective film, AOM: acousto-optic element, CH: center hole, DC: optical disk, DR: drive direction, EOM: electro-optic element, GL: gas laser, I: injection port, L1, L2 L3, L4 ... Lens, L
T, LT1, LT2 ... (laser) light, M1, M2, M3
… Mirror, MD1, MD2… Mold, MT… Movable table, OL… Objective lens, PBS1, PBS2… Polarizing beam splitter, PD1, PD2… Photodiode, P
SD: spot position detecting element, QWP: 1/4 wavelength plate,
RD: resist master, SD: spindle direction.

Claims (13)

[Claims] 1. A method for 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: forming an uneven shape on a master substrate; Forming a sidewall on the side wall of the concave portion to reduce the width of the concave portion. 2. The step of forming the sidewall includes the steps of: forming a sidewall layer on the entire surface of the master substrate on which the concave-convex shape is formed by covering the inside of the concave portion; A step of etching back the entire surface except for a part of the side wall layer in contact with the part.
3. The method for producing a master for producing an optical recording medium according to item 1. 3. The method according to claim 1, wherein the concave and convex shape is a pattern of a guide groove which divides a track area of the optical recording medium. 4. The method according to claim 1, wherein the uneven shape is a pattern of pits of the optical recording medium. 5. The step of forming an uneven shape on the master substrate includes the step of forming a resist film on the surface on which the uneven shape is formed of the master substrate along a pattern that opens a portion to be a concave portion of the uneven shape. 2. The method according to claim 1, further comprising the step of performing anisotropic etching using the resist film as a mask. 6. A method of manufacturing a stamper for manufacturing an optical recording medium, which is used for transferring an uneven shape onto a surface of a medium substrate of an optical recording medium, the method comprising: forming an uneven shape on a master substrate; A method for manufacturing a stamper for manufacturing an optical recording medium, comprising: a step of forming a sidewall on the side wall of the concave portion to reduce the width of the concave portion; 7. The method according to claim 6, wherein the stamper is formed of nickel. 8. A method for manufacturing an optical recording medium having a medium substrate having an uneven shape transferred to a surface thereof, the method comprising: forming an uneven shape on a master substrate; and forming a width of the uneven portion on a side wall of the uneven portion. Forming a sidewall on which the concave and convex shapes of the master substrate are transferred; forming a medium substrate on which the concave and convex shapes of the stamper are transferred; A method for manufacturing an optical recording medium, comprising: a step of forming an optical recording film on the surface on which the uneven shape is formed; and a step of forming a protective film on the optical recording film. 9. The step of forming a stamper to which the irregular shape of the master substrate is transferred, the step of forming an intermediate member to which the uneven shape of the master substrate is transferred, 9. The method for manufacturing an optical recording medium according to claim 8, comprising a step of forming a transferred stamper. 10. The method for manufacturing an optical recording medium according to claim 8, wherein a phase-change optical recording film is formed as said optical recording film. 11. The method for manufacturing an optical recording medium according to claim 8, wherein a magneto-optical recording film is formed as said optical recording film. 12. The method according to claim 8, wherein an optical recording film including an organic dye layer is formed as the optical recording film. 13. The method according to claim 8, wherein a reflection film is formed as the optical recording film.