JPH05189813A - Manufacture of master plate for optical disk - Google Patents

Abstract

(57) [Abstract] [Purpose] A master master for an optical disc having a step of forming a guide groove or a pit together with the guide groove in the resist film by exposing a resist film formed on a substrate to a laser beam for exposure. In the manufacturing method of (1), wide guide grooves and narrow pits are easily formed with good contrast. [Structure] Two or more laser beams 19 and 20 are arranged so as to partially overlap each other in the radial direction of a substrate 21, and the resist film 22 is irradiated with the two or more laser beams 19 and 20 to form a resist film 22. The guide grooves 24 and 25 are formed.
A pit is formed with only one laser beam 19. [Effect] A wide guide groove can be formed by two or more laser beams. It is possible to form narrow pits with only one laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a master master for an optical disc. Specifically, it relates to improvement of a laser exposure process of a resist film applied and formed on a glass substrate in a method of manufacturing a master master for optical disc molding.

[0002]

2. Description of the Related Art On a plastic substrate of an optical disk such as a magneto-optical disk or a CD, a guide groove for guiding a reading laser or a pit for recording information or an address signal is provided. These guide grooves and pits are molded and transferred onto the optical disk substrate by the master master. To manufacture the master master used here,
First, a resist film applied on a glass substrate is exposed by a laser that is narrowed down and developed to form an uneven pattern on the resist film. Next, this pattern is transferred to a metal by the steps of sputtering and plating to form a master master. In the following, in the production of the master master, the guide groove transfer pattern and the pit transfer pattern formed on the resist film by laser exposure of the resist film on the glass substrate are simply referred to as "guide groove" and " It is called "pit".

By the way, the shape of the guide groove and the pit formed on the optical disk is defined by the type of each medium. For example, in a rewritable CD (hereinafter referred to as “CD / MO”) in which data is magneto-optically recorded in the CD format, and in a mini disk in which data is also magneto-optically recorded in the CD format, pits have a width of 0.
U of 45 to 0.7 μm, the width of the guide groove is 1.0 to 1.2 μm, and the depth of λ / 9n to λ / 7n (where n is the refractive index of the medium of the optical disc and λ is the wavelength of the laser at the time of reading). It is defined as a groove with a V-shaped cross section.

Taking the case of polycarbonate, which is the most widely used plastic for disks at present, as an example, since the refractive index n is 1.58 and λ is 780 nm, the depth of the guide groove is 54.8 nm to 70. It becomes 5 nm. Therefore, it is required to form a guide groove having a width much wider than the depth in the resist film for manufacturing the master master. In some cases, it is also required to form pits on the same resist film whose width is less than half the width of the guide groove.

[0005]

In the conventional method for manufacturing a master master, when the guide grooves or pits are formed by laser exposure of the resist film on the glass substrate, the exposure width of the guide grooves or pits exposed by the laser beam. Is controlled by the numerical aperture of the objective lens used for exposure and the intensity of the laser power, but as described above, a guide groove having a width much wider than the depth is formed with good contrast by one laser beam. It's not easy. That is, when the intensity of the laser power is increased to widen the groove width, the unexposed portion between the grooves is exposed due to the proximity effect, and a good contrast between the exposed portion and the unexposed portion cannot be obtained. Occurs. In addition, when an objective lens having a low numerical aperture is used, the laser beam on the substrate is blurred, and good contrast cannot be obtained.

For the same reason, it is not easy to form a guide groove and a pit having a width greatly different from that of the guide groove through a single objective lens with a single laser beam with good contrast.

The present invention solves the above-mentioned problems of the prior art, and by exposing the resist film to laser, a width of 1.0 to 1.2 μm,
A guide groove having a U-shaped cross section with a depth of λ / 9n to λ / 7n (where n is the refractive index of the medium of the optical disk and λ is the wavelength of the laser at the time of reading), or a width of 0.45 with this guide groove.
To provide a method for manufacturing a master disc for an optical disc, which can easily and efficiently form a pit having a U-shaped cross section of about 0.7 μm while ensuring a good contrast between an exposed portion and an unexposed portion. To aim.

[0008]

According to a first aspect of the present invention, there is provided a method of manufacturing a master disc for an optical disk, wherein a resist film formed on a substrate is irradiated with a laser beam to expose the resist film to a width of 1.0. ~ 1.2 μm, depth λ / 9n ~
In a method for manufacturing a master disc for an optical disc, which includes a step of forming a guide groove having a U-shaped cross section of λ / 7n, two laser beams are partially overlapped in a radial direction of the substrate when exposing the resist film. And irradiating the resist film with the two laser beams.

According to a second aspect of the present invention, there is provided a method for manufacturing a master disc for an optical disk, wherein a resist film formed on a substrate is irradiated with a laser beam to expose the resist film so that the U film having a width of 0.45 to 0.7 μm. Pit with a cross section and width 1.0
In the method of manufacturing a master disc for an optical disc, which comprises a step of forming a guide groove having a U-shaped cross section of ˜1.2 μm and a depth of λ / 9n to λ / 7n, two laser beams are used for exposing the resist film. , The substrates are arranged so as to partially overlap each other in the radial direction, and only one laser beam of the two laser beams is applied to the resist film when forming a pit, and the two laser beams are irradiated when forming a guide groove. And irradiating the resist film with the laser beam.

According to a third aspect of the present invention, there is provided a method for manufacturing a master disc for an optical disk, wherein a resist film formed on a substrate is irradiated with a laser beam to expose the resist film so that the U film having a width of 0.45 to 0.7 μm. Pit with a cross section and width 1.0
In the method of manufacturing a master disc for an optical disc, which comprises a step of forming a guide groove having a U-shaped cross section of ˜1.2 μm and a depth of λ / 9n to λ / 7n, a plurality of laser beams are used for exposing the resist film. Arranged on a straight line so that laser beams adjacent to each other in the radial direction of the substrate partially overlap each other, and at the time of pit formation, only one laser beam of the plurality of laser beams is applied to the resist film, When the guide groove is formed, the resist film is irradiated with two or more adjacent laser beams of the plurality of laser beams.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a master disc for an optical disk according to the third aspect, in which three laser beams are arranged, and at the time of forming a pit, one laser beam in the center of the three laser beams is arranged. The resist film is irradiated with only the beam, and the resist film is irradiated with the three laser beams when the guide groove is formed.

[0012]

In the method of manufacturing a master disc for an optical disk according to claim 1, since the two laser beams are arranged so as to partially overlap each other in the radial direction of the substrate, the two laser beams are formed when the guide groove is formed. By irradiating the laser beam of, the wide exposed portion can be formed with good contrast.

In the method of manufacturing a master disc for an optical disk according to a second aspect of the present invention, when the guide groove is formed, a wide exposed portion can be formed with good contrast by the two laser beams as in the method of the first aspect. Yes, again
At the time of forming the pits, by irradiating only one laser beam, it is possible to form a narrow exposed portion with good contrast.

In the method of manufacturing a master disc for an optical disk according to a third aspect of the present invention, since the plurality of laser beams are arranged in a straight line so that a part thereof overlaps in the radial direction of the substrate, the plurality of laser beams are used. A wide exposure portion is formed when exposed, and a narrow exposure portion is formed when exposed by only one of these laser beams with good contrast.

In this case, in particular, by using three laser beams, a wide guide groove can be formed with good contrast, and at the same time, when a pit is formed, it is positioned in the middle of these. By using only the laser beam of the book, the center of the wide guide groove and the center of the narrow pit can be automatically aligned, which is extremely advantageous.

The method for producing a master master for an optical disk according to the present invention is particularly suitable for forming grooves for CD / MO or mini disks, and further for forming grooves and pits.

[0017]

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, a method of manufacturing a master disc for an optical disc according to claim 1 of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram showing an outline of an example of a laser optical system suitable for carrying out the present invention, FIG. 2 is a schematic diagram illustrating a laser exposure process at the time of forming a guide groove, (a) is a sectional view, b) is a plan view.

In FIG. 1, 11 is a laser generator,
Reference numerals 12 and 16 are beam splitters, 13 and 17 are reflecting mirrors, 14 and 15 are optical modulators, and 18 is an objective lens.
The laser beam emitted from the laser generator 11 is converted into two laser beams 1 by the beam splitter 12.
It is divided into 9 and 20. This laser beam 19 and 2
0 undergoes intensity modulation by the optical modulators 14 and 15, respectively. After that, the two laser beams 19 and 20 are reflected by the reflecting mirror 17 and the beam splitter 16 as shown in FIG.
As shown in (a), they are arranged on the glass substrate 21 so as to partially overlap with each other and enter the objective lens 18.

When the laser beams 19 and 20 emitted from the objective lens 18 are applied to the photoresist film 22 coated on the glass substrate 21 as shown in FIG. 2A, the photoresist film 22 is exposed. As a result, exposed portions 24 and 25 as shown in FIG. 2B are formed.

That is, since the exposure is performed by the two laser beams 19 and 20 which partially overlap each other, a wide guide groove is easily formed by the exposure portion 24 by the laser beam 19 and the exposure portion 25 by the laser beam 20. To be done.

Next, with reference to FIG. 3, a method for manufacturing the master disc for an optical disc according to claim 2 of the present invention will be described. 3A and 3B are schematic diagrams for explaining a laser exposure process at the time of forming pits, where FIG. 3A is a sectional view and FIG. 3B is a plan view. 3, members having the same functions as those in FIG. 2 are designated by the same reference numerals.

In the method of claim 2, the method of forming the guide groove is the same as that of the method of claim 1, and it is possible to easily form a wide guide groove. On the other hand, in forming the pit, one of the two laser beams (the laser beam 20 in this embodiment) is used for the optical modulator 15.
Then, only the other laser beam 19 is irradiated as shown in FIG. As a result, as shown in FIG. 3B, a narrow exposed portion (pit) 26 can be easily formed. Note that in FIG. 3B, 27
In a comparative example described later, is a narrow guide groove exposure portion formed only by the laser beam 19.

Next, with reference to FIGS. 4, 5 and 6, a method for manufacturing a master master for optical discs according to a third aspect of the present invention, particularly a method for manufacturing a master master for optical discs according to the fourth aspect, will be described.

FIG. 4 is a schematic view showing an example of a laser optical system suitable for carrying out the present invention, and FIG. 5 is a schematic view for explaining a laser exposure process at the time of forming a guide groove. Sectional drawing, (b) is a top view. 6A and 6B are configuration diagrams for explaining a laser exposure process at the time of forming pits. FIG. 6A is a sectional view and FIG. 6B is a plan view.

In FIG. 4, 11 is a laser generator,
Reference numeral 18 is an objective lens, 31, 32, 37 and 38 are beam splitters, 33 and 39 are reflecting mirrors, and 34, 35 and 36 are optical modulators. The laser beam emitted from the laser generator 11 is split into two laser beams 40 and 41 by the beam splitter 31, and the laser beam 40 is further split into laser beams 42 and 43 by the beam splitter 32. Laser beam 41, 4
2, 43 are intensity-modulated by the optical modulators 34, 35, 36, respectively. After that, 3 laser beams 4
Reference numerals 1, 42 and 43 denote a reflecting mirror 39 and a beam splitter 3
As shown in FIG. 5A, the objective lenses 7 and 38 are arranged on the glass substrate 21 in a straight line in the radial direction of the substrate 21 so that adjacent laser beams partially overlap with each other. It is incident on 18.

When the laser beam 41, 42, 43 emitted from the objective lens 18 is irradiated on the photoresist film 22 applied on the glass substrate 21 as shown in FIG. 5A, the photoresist film 22 is formed. Exposed, Figure 5
The exposed portions 44, 45, 46 are formed as shown in (b).

That is, since the adjacent laser beams are exposed by the three laser beams 41, 42 and 43 which partially overlap each other, the exposure section 44 by the laser beam 41 is exposed.
The guide groove having a wide width can be easily formed by the exposure part 45 exposed by the laser beam 42 and the exposure part 46 exposed by the laser beam 43.

On the other hand, in forming the pit, two of the three laser beams 41, 42 and 43 (in this embodiment, the laser beams 41 and 43 at both ends) are used to form the optical modulator 3.
It is shielded by Nos. 4 and 36, and as shown in FIG. 6A, only one laser beam 42 in the middle is irradiated.

As a result, as shown in FIG. 6B, it is possible to easily form the exposed portion 47 (pit) having a narrow width. Moreover, at this time, this pit and the above-mentioned FIG.
The center of the guide groove formed in (b) can be automatically matched. In FIG. 6B, reference numeral 48 denotes an exposed portion having a narrow width formed only by the laser beam 42.

Specific examples will be described below.

Example 1 Table 1 shows the width and depth of the formed guide groove when the guide groove is formed by exposure using two laser beams by the method shown in FIGS.

Comparative Example 1 For comparison, Table 1 shows the width and depth of the guide groove formed by using one laser beam.

[0034]

[Table 1]

Example 2 By the method shown in FIGS. 1, 2 and 3, two laser beams are used for exposure to form a guide groove, and only one laser beam is used for exposure to form pits. Table 2 shows the widths and depths of the formed guide grooves and pits in the case.

[0036]

[Table 2]

From Tables 1 and 2, according to the method of manufacturing a master disc for an optical disk of the present invention, a guide groove having a width much larger than the depth and a pit having a width equal to or less than half the width of the guide groove are excellent. It is clear that the contrast can be formed.

[0038]

As described in detail above, according to the method of manufacturing the master master for an optical disc of the first aspect, the width of 1.0 to 1.
A guide groove having a width of 2 μm and a U-shaped cross section having a depth of λ / 9n to λ / 7n and having a very wide width with respect to the depth can be easily formed with good contrast.

Thus, according to the method of claim 1, C
The wide guide groove required for the D / MO or the mini disk can be formed with good contrast. Moreover,
When forming the wide guide groove, it is not necessary to particularly increase the laser power, so that the land portion also remains uniform.

According to the method of manufacturing a master disc for an optical disk of claim 2, the width of 0.45 to 0.
It is possible to easily form a pit having a U-shaped cross-sectional shape of 7 μm and having a width equal to or less than half the width of the guide groove with good contrast.

According to the method of manufacturing a master disc for an optical disk of claim 3, a guide groove having a wider width and a pit having a narrower width can be easily formed with good contrast.

As described above, also by the methods of claims 2 and 3, it is possible to form the wide guide groove and the narrow pit required for the CD / MO or the mini-disc with good contrast. Moreover, since it is not necessary to increase the laser power particularly when forming the wide guide groove, the land portion remains uniformly.

According to the method of manufacturing a master disc for an optical disk of claim 4, a wide guide groove and a narrow pit can be easily formed by automatically matching their centers. ..

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a laser optical system suitable for carrying out the present invention.

2A and 2B are schematic diagrams illustrating a laser exposure process when forming a guide groove, in which FIG. 2A is a sectional view and FIG. 2B is a plan view.

3A and 3B are schematic diagrams illustrating a laser exposure process at the time of forming pits, in which FIG. 3A is a sectional view and FIG. 3B is a plan view.

FIG. 4 is a configuration diagram showing an outline of an example of a laser optical system suitable for implementing the present invention.

5A and 5B are schematic diagrams for explaining a laser exposure process when forming a guide groove, in which FIG. 5A is a sectional view and FIG. 5B is a plan view.

6A and 6B are schematic diagrams illustrating a laser exposure process at the time of forming pits, in which FIG. 6A is a sectional view and FIG. 6B is a plan view.

[Explanation of symbols]

11 Laser generator 12, 16, 31, 32, 37, 38 Beam splitter 13, 17, 33, 39 Reflector 14, 15, 34, 35, 36 Optical modulator 18 Objective lens 19, 20, 41, 42, 43 Laser beam 21 Glass substrate 22 Photoresist film 24, 25, 26, 44, 45, 46, 47 Exposure unit

Claims (4)

[Claims] 1. A resist film formed on a substrate is irradiated with a laser beam for exposure to expose the resist film to a width of 1.0 to 1.2 μm and a depth of λ / 9n to λ / 7n.
(Where n is the refractive index of the medium of the optical disc, λ is the wavelength of the laser at the time of reading), in the method for producing a master disc for an optical disc having a step of forming a guide groove having a U-shaped cross section, in exposing the resist film, A method for manufacturing a master disc for an optical disk, comprising arranging two laser beams so that a part of the laser beams overlap each other in a radial direction of the substrate, and irradiating the resist film with the two laser beams. 2. A resist film formed on a substrate is irradiated with a laser beam for exposure to expose a pit having a U-shaped cross section having a width of 0.45 to 0.7 μm and a width of 1.0 to 1 on the resist film. Master for optical disk having a step of forming a guide groove having a U-shaped cross section of 0.2 μm and a depth of λ / 9n to λ / 7n (where n is the refractive index of the medium of the optical disk and λ is the laser wavelength at the time of reading) In the method of manufacturing a master, in exposing the resist film, two laser beams are arranged so that a part thereof overlaps in the radial direction of the substrate, and one of the two laser beams is formed at the time of pit formation. 2. The method for producing a master disc for an optical disc, wherein the resist film is irradiated with only the laser beam of 1) and the resist film is irradiated with the two laser beams when the guide groove is formed. 3. A pit having a U-shaped cross section having a width of 0.45 to 0.7 μm and a width of 1.0 to 1 are formed on the resist film formed by irradiating a laser beam on the substrate to expose the resist film. Master for optical disk having a step of forming a guide groove having a U-shaped cross section of 0.2 μm and a depth of λ / 9n to λ / 7n (where n is the refractive index of the medium of the optical disk and λ is the laser wavelength at the time of reading) In the method of manufacturing a master, in exposing the resist film, a plurality of laser beams are arranged in a straight line in a radial direction of the substrate so that adjacent laser beams partially overlap each other, and when the pits are formed, the plurality of laser beams are arranged. Of the laser beams, the resist film is irradiated with only one laser beam, and two or more adjacent laser beams among the plurality of laser beams are formed at the time of forming the guide groove. Method for producing a master template for the optical disk, which comprises irradiating the resist film. 4. The method according to claim 3, wherein three laser beams are arranged, and at the time of forming a pit, only one central laser beam of the three laser beams is irradiated to the resist film for guiding. A method for producing a master master for an optical disc, wherein the resist film is irradiated with the three laser beams when forming a groove.