KR20050032302A - Substrate for optical disc, optical disc employing the substrate and method for manufacturing the same, and stamper for manufacturing the substrate and method for making the stamper - Google Patents

Abstract

An optical disk substrate, an optical disk using the optical disk substrate and a method of manufacturing the optical disk, a stamper for manufacturing the optical disk and a method of manufacturing the stamper are provided to extend an information recording area by minimizing a rim area of approximately 1.0mm width. An optical disk substrate comprises an information recording area and a rim area formed with a predetermined width in an edge of the information recording area wherein a height of the rim area is relatively smaller than a height of the information recording area. The rim area comprises a dug portion got dug rectangularly from a same surface as a surface of the information recording area. A width of the rim area is within 1.0mm.

Description

Substrate for optical disc, optical disc employing the substrate and method for manufacturing the same, and stamper for manufacturing the substrate and method for making the stamper}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk substrate capable of providing an information recording medium having improved recording capacity, an optical disk employing the same, and a manufacturing method thereof, and a stamper for manufacturing an optical disk substrate and a manufacturing method thereof. An optical disc substrate, an optical disc employing the same, which reduces the unrecorded rim area and expands the information recording area while ensuring transferability of the outer peripheral part during injection molding, thickness uniformity during spin coating, and an outer mask area. A manufacturing method thereof, a stamper for manufacturing a substrate for an optical disc, and a manufacturing method thereof.

In general, an optical disc is widely used as an information recording medium of an optical pickup apparatus for recording / reproducing information in a non-contact manner. These optical discs are classified into CD, DVD, BD (Blu-ray Disc) and the like according to the information recording capacity.

This optical disc has a standard diameter of 120 mm and 80 mm, and includes an information recording area and a rim area provided at an outer circumference of the information recording area. The rim area is an area required for installing an outer mask during the information recording area forming process, and no information is recorded in this rim area.

CD, DVD, and BD having a diameter of 120 mm are all defined to have a width of 1.5 mm in the rim area. In other words, the rim area is formed at a radius of 58.5 to 60.0 mm when viewed from the center of the optical disc in the circumferential direction.

The size of the optical disk rim area is set in consideration of the transferability of the outer peripheral portion of the substrate, the optical disk thickness uniformity, and the outer mask area during injection molding of the substrate for the optical disk.

In accordance with the light and thin and short and small requirements of the optical disk drive employing the optical disk described above, the diameter of the optical disk is required to be small. When the size is reduced in this way, it is convenient for the user to handle, but there is a problem that the recording capacity is reduced. Therefore, it is necessary to minimize the rim area to maximize the information recording area.

On the other hand, in the conventional optical disc substrate structure, it is difficult to reduce the rim area to 0.5 mm or less in width. Hereinafter, the reason will be described with reference to FIGS. 1 to 6.

Referring to Fig. 1, the conventional optical disc substrate 1 includes an information recording area and a rim area. As described above, the determination of the information recording area and the rim area is determined in consideration of the substrate transferability, the substrate thickness uniformity and the outer mask area.

First, the substrate transferability according to each region will be described. Here, the substrate transferability indicates the degree to which the information pattern recorded on the stamper used for manufacturing the substrate is transferred to the substrate, and the factors that determine the transferability include the depth, length and shape of the information pattern.

2A to 2D each show substrate transferability in the inner region, the 1.5 mm region from the outermost circumference, the 1.0 mm region, and the 0.4 mm region. 2A to 2D, since the substrate has good transferability from the outermost circumference to 0.4 mm region, this substrate transferability is not a barrier to reducing the rim region to approximately 0.5 mm width at the outermost circumference.

3 is a graph showing the degree of thickness uniformity up to a 20 mm radius inside the outermost rotor. This graph shows the result of forming a 0.1 mm-thick light-transmitting layer by curing a resin by spin curing method on a test disk substrate with a radius of 50.8 mm. It is shown.

Figure 3 shows the result of measuring the uniformity over eight places by changing the angle in 45 degrees unit by grasping on one part, and when looking inside the outermost rotor, approximately 0.1mm thickness uniformity in the inner side of approximately 0.9mm radius It can be seen that can be obtained. On the other hand, since the uniformity is sharply changed at the outer circumferential portion than 0.9 mm, it is difficult to manage the rim area within 0.5 mm in the conventional disk substrate structure.

4 is a diagram illustrating a process of depositing a thin film on an information surface of an optical disk substrate. Referring to this, the influence of the outer mask area will be described.

When the thin film 3 used as the reflective film or the recording film is formed on the information surface of the substrate 1 for the optical disk, an outer peripheral mask 7 is required. That is, when the thin film 3 is formed without the outer mask 7, oxygen, moisture, or the like penetrates from the edge portion of the substrate, thereby causing a problem in reliability such as oxidation and corrosion.

Therefore, it is necessary to fix the substrate 1 via the outer circumferential mask 7, and in this case, a rim area corresponding to at least a width corresponding to the outer circumferential mask area for sputtering is required. In addition, in the conventional substrate structure, as shown by reference numeral 3a by the shadow effect of the outer periphery mask 7, the thin film 3 is lifted or uneven. For this purpose, the rim area needs to be larger than the outer mask area as shown in FIG. 5, that is, an area of about 0.84 mm from the outermost part. Therefore, in the case of the conventional optical disk substrate, there is a problem that it is difficult to manage the rim area within 0.5 mm due to the above-mentioned problem of setting the outer mask area.

In addition, referring to FIG. 6, the conventional optical disk forms the light transmitting layer 5 on the thin film 3 by spin coating. At this time, the light transmitting layer 5 is formed convexly as shown in the edge region 5a thereof by surface tension or the like. Due to the formation of this edge region 5a, it is an obstacle to reducing the rim region to 1.5 mm or less.

The substrate for optical disk and the optical disk employing the optical disk configured as described above do not have a problem of substrate transferability in consideration of improving the recording density by minimizing the rim area to within about 0.5 mm. It can be seen that there is a problem in forming the light transmitting layer by region setting and spin coating.

Accordingly, an object of the present invention is to provide a substrate for an optical disk and a method for manufacturing the same, the structure of which is improved to minimize the width of the rim area to within about 1.0 mm.

In addition, another object of the present invention is to provide an optical disk and a manufacturing method thereof having a structure that can prevent the edge portion from convex when forming a thin film by spin coating.

Another object of the present invention is to provide a stamper for manufacturing a substrate for an optical disk and a method of manufacturing the same, wherein the rim area is minimized according to the present embodiment.

In order to achieve the above object, the present invention provides a substrate for an optical disc comprising an information recording area and a rim area having a predetermined width at an edge of the information recording area, wherein the substrate thickness of the rim area is the information recording area. It is characterized by being relatively thinner than the thickness of the substrate.

In addition, an optical disc according to the present invention for achieving the above-mentioned other objects has an information recording area and a rim area formed on the edge of the information recording area with a predetermined width, wherein the substrate thickness of the rim area is the substrate of the information recording area. A substrate that is relatively thinner than the thickness; A thin film formed to a predetermined thickness on a surface on which information of the substrate is recorded; And a light transmitting layer formed on the thin film to have a predetermined thickness and to which light for recording and / or reproducing information is incident.

In addition, the optical disc manufacturing method according to the present invention for achieving the above-described other object, the step of the information recording area and the same surface on which the information is recorded to be formed at a predetermined width on the edge of the information recording area with a predetermined depth Forming a substrate having a forked rim region; Fixing the rim area with an outer mask and depositing a thin film on a surface of the information recording area with a predetermined thickness; And forming a light transmitting layer on which the light for recording and / or reproducing information is incident on the thin film by a spin coating to a predetermined thickness.

In addition, an optical disk substrate manufacturing stamper according to the present invention for achieving the above object further comprises a first stamper shell having a predetermined pattern and hollow corresponding to the information recording area of the substrate for the optical disk; And a second stamper shell protruding from one surface of the first stamper shell so as to correspond to a stepped rim region of the substrate for the optical disk.

In addition, a method for manufacturing a stamper for manufacturing a substrate for an optical disc according to the present invention for achieving the above object further comprises the steps of manufacturing a first stamper shell having a predetermined pattern and hollow corresponding to the information recording area of the substrate for the optical disc; ; Coupling a cover plate covering a portion of the first stamper shell to the first stamper shell; Plating-coating an upper portion of the first stamper shell and the cover plate to a predetermined thickness; Removing the cover plate to fabricate a second stamper shell protruding to correspond to the rim area of the substrate for the optical disc; And processing the manufactured first and second stamper shells to have a final stamper shape.

Hereinafter, with reference to the accompanying drawings will be described in detail an optical disk substrate, an optical disk using the same, and a method for manufacturing the same, a substrate manufacturing stamper and a method for manufacturing the same according to an embodiment of the present invention.

Referring to Fig. 7, the optical disc substrate 11 of the present invention includes an information recording area and a rim area formed at a predetermined width at the edge thereof. In addition, the substrate thickness of the rim region is relatively thinner than the total thickness d of the substrate for the optical disc. Here, the substrate thickness of the portion where the information recording area is formed corresponds to the total thickness of the substrate 11 for optical disc.

Preferably, the rim area is a stepped portion 15 formed stepped on the same surface as the surface 12 on which the information of the information recording area is recorded. The step portion 15 has a width a and a depth b, and the width a and depth b can be varied depending on how much the rim area of the optical disc substrate is set.

Here, the width a of the step portion 15 is preferably within 1.0 mm. In addition, the depth b of the stepped portion 15 has a value in the range of approximately 1/100 to 1/3 of the substrate thickness d.

The range of the width a and the depth b is a value determined in consideration of the substrate thickness uniformity and the outer mask area, and by providing the step portion 15 described above, the minimum width limit of the rim area in the conventional optical disc substrate is overcome. The rim area can be formed with a width within 1.0 mm.

The stepped part 15 is not limited to the rectangular shape as shown, and may be modified into other shapes such as round shapes.

8 to 11, an optical disc and a method of manufacturing the same according to an embodiment of the present invention will be described.

Referring to FIG. 8, an optical disc according to the present embodiment includes a thin film formed with a predetermined thickness on a substrate 11 having an information recording area and a rim area, and a surface 12 on which information on the substrate 11 is recorded. 17) and a light transmitting layer 19 formed on the thin film 17.

The substrate 11 has a structure in which the stepped portion 15 forms a rim region, which is the same as the substrate described with reference to FIG. 7, and thus a detailed description thereof will be omitted. The thin film 17 may be set differently by dividing the optical disk into a case where the optical disc is for reproduction only and a case for recording / reproducing. That is, the thin film 17 is a reflecting film for reproduction only, and a recording film such as a phase change layer for recording / reproducing. The structure and material of the reflective film and the recording film itself are well known in the optical disc field, and thus detailed description thereof will be omitted. The light transmitting layer 19 is a layer into which information recording light and / or information reproduction light is incident, and serves to protect the thin film 17.

In the method of manufacturing an optical disk configured as described above, a substrate having an information recording area and a rim area is formed, and a thin film is deposited on one surface of the information recording area, that is, the information recording surface, by a predetermined thickness, followed by spin coating on the thin film. Forming a light transmitting layer to a predetermined thickness.

The substrate forming process will be described in detail with reference to FIG. 9. As shown, an injection machine 40 for preparing a resin is prepared. The injection machine 40 is composed of a movable plate 41 and a fixed plate 45, and a space is formed between the movable plate 41 and the fixed plate 45. And the stamper 30 is installed inside the injection machine 40. The stamper 30 includes a first stamper shell 31 having a predetermined pattern corresponding to the information recording area, and a second stamper shell 35 protruding to correspond to the rim area. In the drawings, the stamper 30 is shown as an example installed inside the fixing plate 45, but this is merely exemplary, and the stamper 30 may be installed inside the movable plate 41.

In order to secure a space corresponding to the formation of the substrate 11 to be formed, a cavity ring 47 surrounding the circumference of the space in which the substrate 11 is to be formed is placed in the space between the movable plate 41 and the fixed plate 45. Prepare.

Subsequently, the resin 11a is injected into the internal space through the injection hole 44 of the injection machine 40 and cured to form an information recording area and a rim area. The substrate (11 in FIG. 7) is completed by forming (13 in FIG. 7). In this way, the formed substrate is formed with a rim region stepped, the same as the substrate described with reference to Figure 7 will not be described in detail.

The thin film forming process will be described with reference to FIGS. 10 and 11. First, the outer circumferential mask 21 is mounted on the stepped portion 15 forming the rim region of the substrate 11. The outer circumferential mask 21 presses the outer circumference of the substrate 11 and is formed in the rim region formed stepped as described above, thereby reducing interference with the information recording region of the substrate 11. Subsequently, a thin film 17 is deposited to a predetermined thickness on the information recording surface 12 of the substrate 11 completed through the sputtering process. The material and function of the thin film 17 serves as a reflective film or a recording film depending on the type of optical disk. Here, since the material and function of the thin film 17 itself are well known, detailed description thereof will be omitted.

As described above, the step portion 15 is provided on the substrate 11 and the outer mask 21 is provided on the step portion 15 to eliminate the shadow effect caused by the outer mask 21. Can be minimized. Therefore, it is possible to fundamentally solve the limitation of the rim area management according to the outer mask area setting, so that the rim area can be managed within 1.0 mm and preferably within 0.5 mm.

Referring to FIG. 8, the light transmitting layer 19 is formed to have a predetermined thickness by spin coating on the thin film 17. Since the rim region is formed stepped, the surface tension at the edge portion during spin coating, etc. Even under the influence of the edges, the edges do not become convex. Therefore, when forming the light transmitting layer through spin coating, the rim area can be reduced to 1.5 mm or less.

On the other hand, the optical disk substrate is a step of forming the rim area stepped to a width of less than 1.0mm in the prior art is difficult, so a new type of stamper is required to form it.

Hereinafter, an optical disk substrate manufacturing stamper and a method of manufacturing the same according to an embodiment of the present invention will be described in detail.

Referring to FIG. 12F, the stamper 30 for manufacturing an optical disc substrate according to the embodiment of the present invention includes a first stamper shell 31 and a second stamper shell 32. The first stamper shell 31 has a predetermined pattern (not shown) corresponding to the information recording area of the substrate for the optical disk, and a hollow 31c corresponding to the resin injection hole (44 in FIG. 9). The second stamper shell 32 is formed to protrude on one surface of the first stamper shell 31 and has a shape corresponding to a stepped rim area of the substrate for the optical disc.

The stamper for an optical disk substrate thus constructed is manufactured through the order as shown in Figs. 12A to 12E. Hereinafter, a method of manufacturing a stamper will be described in order of manufacture.

First, a first stamper shell 31a having a predetermined pattern and a hollow corresponding to the information recording area of the substrate for an optical disc is produced.

More specifically, as shown in Fig. 12A, a master glass 51 on which information is recorded is prepared. As shown in FIG. 12B, the first stamper shell is coated to a predetermined thickness by plating the upper surface of the master glass 51. Here, the plating coating is made through electroplating or electroless plating using nickel. Subsequently, the first stamper shell 31a is separated from the master glass 51, and the information surface on the stamper information area of the first stamper shell 31a is coated with a protective film 53 as shown in FIG. 12C. After polishing the surface on which the information of the first stamper shell is not formed, selecting and punching the center of the first stamper shell 31a to form a hollow 31b, and then removing the protective film 53. Then, the first stamper shell 31a is completed.

Subsequently, a process of coupling the cover plate 55 covering a part of the first stamper shell 31a to the first stamper shell 31a is performed. Looking at this process, a cover plate 55 having a predetermined protrusion 55a in the center is prepared. In addition, the cover plate 55 is installed to cover a part of the first stamper shell 31a while the first stamper shell 31a is installed on the plating mounts 57 and 59. That is, the projection 55a is coupled to the hollow 31b of the first stamper shell 31a so that the cover plate 55 is an area of the first stamper shell 31a corresponding to the information recording area of the substrate. Cover it.

Subsequently, after performing a process of plating the upper portion of the first stamper shell 31a and the cover plate 55 to a predetermined thickness, the cover plate 55 and the plating mounts 57 and 59 are removed. A second stamper shell 32a is formed to protrude so as to correspond to the rim region of the optical disk substrate.

Subsequently, the fabricated first and second stamper shells 31a and 32a are processed to have final stamper shapes 31 and 32. This process again coats a protective film (not shown) on the information surface of the first stamper shell 31a, and punches the inner and outer circumferences of the first and second stamper shells 31a and 32a to form a hollow 31c. As shown in FIG. 2, the unnecessary outer peripheral part is removed and the protective film is removed.

Through the process as described above, it is possible to produce a stamper corresponding to the stepped portion of the substrate having a width within approximately 1.0 mm and a value ranging from 1/00 to 1/3 with respect to the substrate thickness for the optical disk.

The optical disk and the substrate according to the embodiment of the present invention configured as described above change the shape of the rim area so that the shadow effect in the plating process after setting the outer mask is not affected. In addition, the projection is not formed when forming the light transmitting layer by spin coating. Therefore, the rim area can be reduced to a width smaller than 1.5 mm to expand the recording area.

Therefore, in the case of maintaining the same diameter and size as a normal optical disc, there is an advantage that the recording capacity can be increased as the width of the rim area is reduced. In addition, it is possible to easily cope with miniaturization of the optical disc.

In addition, a second stamper shell corresponding to the substrate may be manufactured by using a stamper for manufacturing an optical disc substrate and a manufacturing method thereof according to an embodiment of the present invention configured as described above, thereby minimizing the rim area. There is an advantage that can be easily manufactured.

1 is a schematic cross-sectional view showing a substrate for a conventional optical disk.

2A to 2D each show substrate transferability in each of an inner region, a 1.5 mm region, an 1.0 mm region and a 0.4 mm region from the innermost region, the outermost circumference of the substrate for a conventional optical disk;

3 is a graph showing thickness uniformity from the outermost periphery of the conventional optical disk to the inner diameter.

Figure 4 is a schematic cross-sectional view showing a thin film deposition process on a substrate for a conventional optical disk.

5 is a view showing a deposited outer circumference mask area of a conventional optical disk.

6 is a schematic cross-sectional view showing a portion of a conventional optical disk.

7 is a schematic cross-sectional view and a partially enlarged view showing a substrate for an optical disk according to an embodiment of the present invention.

8 is a schematic cross-sectional view showing a portion of an optical disk according to an embodiment of the present invention.

9 is a schematic cross-sectional view showing a substrate manufacturing process for an optical disk according to an embodiment of the present invention.

10 and 11 are schematic cross-sectional views showing a thin film deposition process on an optical disk substrate according to an embodiment of the present invention.

12A to 12F are schematic views showing a stamper manufacturing process for manufacturing a substrate for an optical disc according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

11 ... substrate for optical disc 15 ...

17 ... thin 30 ... stamper

31 ... 1st stamper shell 32 ... 2nd stamper shell

40 ... injection machine 47 ... cavity ring

53 ... shield 55 ... cover plate

Claims (19)

A substrate for an optical disc comprising an information recording area and a rim area formed at a border of the information recording area with a predetermined width, And the rim area thickness is relatively thinner than the substrate thickness of the information recording area. The method of claim 1, wherein the rim area, And a stepped portion formed stepped to a predetermined depth on the same surface on which the information in the information recording area is recorded. The depth of the stepped portion, And a range of 1/100 to 1/3 of the thickness of the substrate of the information recording area. The method according to any one of claims 1 to 3, And the width of the rim area is within 1.0 mm. A substrate having an information recording area and a rim area having a predetermined width at an edge of the information recording area, wherein a substrate thickness of the rim area is relatively thinner than a substrate thickness of the information recording area; A thin film formed to a predetermined thickness on a surface on which information of the substrate is recorded; And a light transmitting layer formed on the thin film to have a predetermined thickness and to which light for recording and / or reproducing information is incident. The method of claim 5, wherein the rim area, And a stepped portion formed stepped to a predetermined depth on the same surface on which the information is recorded. The depth of the stepped portion, And a range of 1/100 to 1/3 of the thickness of the substrate of the information recording area. The method according to any one of claims 5 to 7, And the width of the rim area is within 1.0 mm. The method according to any one of claims 5 to 7, And the thin film is a reflective film or a recording film on which information is recorded and reproduced. Forming a substrate having an information recording area and a rim area which is formed at a predetermined width at an edge of the information recording area and is formed at a predetermined depth on the same surface as the surface on which information is recorded; Fixing the rim area with an outer mask and depositing a thin film on a surface of the information recording area with a predetermined thickness; And forming a light transmitting layer through which light for recording and / or reproducing information is incident on the thin film by spin coating to a predetermined thickness. The method of claim 10, wherein the forming of the substrate comprises: Preparing an injection machine having a movable plate and a fixed plate, for injecting resin into the space between the movable plate and the fixed plate; Installing a stamper on one surface of the fixed plate or the movable plate, the stamper comprising a first stamper shell having a predetermined pattern corresponding to the information recording area and a second stamper shell protruding to correspond to the rim area; And forming an information recording area and a rim area through resin injection and curing in the cavity. The step depth of claim 11, wherein And a range of 1/100 to 1/3 of the substrate thickness of the information recording area. The method according to any one of claims 10 to 12, And the width of the rim area is within 1.0 mm. The method according to any one of claims 10 to 12, And the thin film is a reflective film or a recording film on which information is recorded and reproduced. A first stamper shell having a predetermined pattern and a hollow corresponding to the information recording area of the substrate for the optical disc; And a second stamper shell protruding from one surface of the first stamper shell so as to correspond to a stepped rim area of the substrate for the optical disk. Manufacturing a first stamper shell having a predetermined pattern and a hollow corresponding to the information recording area of the substrate for an optical disk; Coupling a cover plate covering a portion of the first stamper shell to the first stamper shell; Plating-coating an upper portion of the first stamper shell and the cover plate to a predetermined thickness; Removing the cover plate to produce a second stamper shell protruding to correspond to the rim area of the substrate for the optical disc; And processing the fabricated first and second stamper shells to have a final stamper shape. The method of claim 16, wherein the manufacturing of the first stamper shell, Preparing a master glass on which information is recorded; Coating a first stamper shell to a predetermined thickness by plating the upper surface of the master glass; Separating a first stamper shell from the master glass; Protective coating the information surface of the first stamper shell; Polishing a surface on which the information of the first stamper shell is not formed; Selecting and punching a center of the first stamper shell to form a hollow; Removing the protective film; Stamper manufacturing method for manufacturing an optical disk substrate comprising a. The method of claim 16 or 17, wherein the step of joining the cover plate, Preparing a cover plate having a predetermined protrusion at the center thereof, and coupling the protrusion to the hollow of the first stamper shell so that the cover plate covers an area of the first stamper shell corresponding to the information recording area of the substrate. Stamper manufacturing method for manufacturing an optical disk substrate characterized in that. 18. The method of claim 16 or 17, wherein the step of making the first and second stamper shells have a final stamper shape, Coating a protective film on the information surface of the first stamper shell again; Punching an inner circumference and an outer circumference of the first and second stamper shells; Removing the protective film; Stamper manufacturing method for manufacturing an optical disk substrate comprising a.