JPS5940337A - Master disk for information storing medium and its production - Google Patents

Abstract

PURPOSE:To obtain a master disk for information storing medium capable of accrate reading and tracking which is suited to mass production, by forming the 1st recessing/projecting part, then deleting a part of said part to form the 2nd recessing/projecting part. CONSTITUTION:A photoresist exposure part 4 is formed on a glass substrate 1, and the part 4 remaining after development and fixing is used as a mask to etch 700Angstrom the surface of the substrate 1. Then the part 4 is deleted to obtain a recessing/projecting part 5 of 700Angstrom , and a recessing/projecting part forming layer 6 consisting of a material which has a doping function with heat is formed with 700Angstrom thickness. In other words, a chalcogenite glass layer 7 of As2S3 is formed on the substrate 1, and then a metallic layer 8 is vapor depositied. The layer 6 positioned at the upper part of the part 5 is traced by the laser light while the substrate 1 is turned, and the quantity of the laser light is increased at the position where an information pit is formed to dope the layer 8 to the layer 7. The layer 8 is melted and dipped into an alkali solution, and therefore the layer 6 is removed excepting a chalcogenite glass part 10 to which a metal is doped. Thus, a recessing/projecting part 11 is formed at the upper part of the part 5. These parts 5 and 11 are equivalent to a tracking guide and an information pit respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a master disk for an information storage medium for manufacturing an information storage medium on which information can be written or read using a focused laser beam, and a method for manufacturing the same.

[Technical background of the invention and its problems]

Information storage media are disk-shaped or tape-shaped, such as compact discs (CDs) used in digital audio discs (DAD), and optical video discs, and information is stored using focused laser light. Readable and read-only information storage media, image files and computer output memory (CON)
Information storage for recording and playback, which is in the form of a disk or tape, such as those used in other applications, and can write information to and read information from the recording layer using focused laser light. Examples include media and erasable information storage media.

Such information storage media have narrow track pitches in order to increase the density of information. Therefore, in order to make the optical head follow a predetermined track during reading or writing, a tracking guide consisting of a groove or a convex portion having a step with respect to a flat surface is formed in advance on this type of information storage medium. There is. Furthermore, if a track number indicating a position where information is recorded and a sector position are recorded in advance, the recording/reproducing device can easily perform the installation. A device that is also equipped with a signal information bit consisting of a convex part and a convex part (also called a tracking guide with a 7-ohm tag)
It becomes.

The tracking guide and the signal information bit are formed by unevenness with respect to a flat surface, and the difference in the amount of reflected light therefrom is read as information. For this reason, the tracking guide is designed to have a depth of λ (λ is the wavelength of the reading laser beam), for example, so that the tracking guide can increase the detection signal due to the diffraction pattern of the light reflected from the guide and achieve stable tracking. (The same applies hereafter), and is a rectangular groove with a width of about 0.6 to 0.8 μm. Also, the signal information bit has the maximum modulation degree (when the reading laser beam is irradiated directly above the signal information bit, the intensity of the reflected light from there is the smallest)
The trap is set to have a depth of λ/4 and a width of about 1/6 of the spot size of the reading laser beam.

In order to mass-produce information storage media equipped with such tracking guides and signal information bits, a master disk with unevenness to form the tracking guides and signal information bits is created, and the unevenness of this master disk is modified in various ways. The surface pressure of the substrate of the information storage medium is transferred by the process pressure.

Incidentally, the following methods are known for producing tracking guides and signal information bits at the stage of manufacturing the master disc. That is, on a glass substrate whose surface has been polished, a 7-photoresist layer is formed, and in the areas where signal information bits are to be formed, a sufficient amount of laser light is irradiated to make holes until the substrate is reached, forming a tracking guide. In the areas to be removed, the amount of laser light is reduced and grooves are created halfway into the photoresist layer.

In this way, tracking guides with different depths and signal information bits are formed. However, the sensitivity of the photoresist layer differs depending on the state of the photoresist layer before laser exposure, or it is extremely difficult to control the amount of laser light exposure so that the depth of the tracking guide is uniform everywhere. However, there was a problem in that tracking guides and signal information bits could not be formed with high precision.

Also, as described in JP-A-48-85025x,
There is a method of forming tracking guides and signal information bits by forming multiple photoresist layers with different sensitivities, but since photoresists do not easily dissolve in solvents, several types of photoresists dissolved in solvents are used. When applying in layers,
There was a problem in that the underlying photoresist layer was eroded and scratched.

There has been a problem in that it is technically difficult to uniformly apply multiple layers of photoresist on a surface.

Additionally, as a result, in the case of conventional master discs for information storage media,
There has been a problem in that it is not possible to mass-produce information storage media that can accurately read information using focused laser light and that can perform stable tracking.

[Purpose of the invention]

The present invention has been devised in view of the above-mentioned circumstances, and includes a precisely formed tracking guide and a signal information pit, thereby enabling accurate information reading and stable tracking. The purpose is to provide a master disc for information storage media that can contribute to the mass production of storage media, and furthermore, it is possible to create master discs for information storage media relatively easily and with high precision, and to improve productivity. It is an object of the present invention to provide a method for manufacturing a master disk for an information storage medium, which can improve the manufacturing cost and reduce the manufacturing cost.

[Summary of the invention]

A first invention provides a master disc for an information storage medium for manufacturing an information storage medium in which information can be read from an uneven part using a focused laser beam, and a substrate on which a first uneven part is formed; It is characterized by comprising a second uneven portion formed by removing a part of the unevenness forming layer provided on the substrate. The second invention is a method for manufacturing a master disc of an information storage medium capable of reading multiple information using a focused laser beam, and at least a first step of forming a first uneven portion on a substrate. , comprising a second step of providing an unevenness forming layer on the substrate, and a sixth step of forming a second unevenness portion by removing a part of the unevenness forming layer. .

[Embodiments of the invention]

Hereinafter, a method for manufacturing a master disc for an information storage medium according to the present invention will be explained with reference to the drawings.

FIGS. 1(α) to 1(d) are cross-sectional views showing the manufacturing method according to the first embodiment of the present invention in the order of steps.

First, as shown in FIG. 1(α), a photoresist layer 2 is formed by spin coating a negative type photoresist on a glass substrate 1 whose surface has been polished. Then, the photoresist layer 2 is exposed concentrically or spirally with a laser beam focused by the objective lens 3 to form a photoresist exposed portion 4.

Thereafter, as shown in FIG. 1(A)K, this photoresist layer 2 is developed and fixed, and the portions of the photoresist other than the exposed portions 4 are removed. Then, using the exposed photoresist portion 4 remaining after development and fixation as a mask, the exposed portion of the surface of the substrate 1 is etched to a depth of 7007 to remove that portion.

It is preferable to use a mixed solution of 6% hydrofluoric acid and 40% ammonium fluoride as the etching solution. Further, after completing the etching, the photoresist exposed portion 4 is removed using an organic solvent. In this way height 7
A first concavo-convex portion 5 having a convex portion of 00A is formed on the substrate 1.

Next, as shown in FIG. 1 <C) f/C, a concavo-convex forming layer 6 made of a set of materials that produces a doping effect due to heat is provided on the substrate 1 to a thickness of 700 Å. Ding, on the substrate 1 1c As2S3 g As25 g3,
A chalcogenide glass layer 7 made of AsSTe-based, As-5-5t-based, etc. is formed, and a metal layer 8 of Cw, Or, etc. is further formed by vacuum evaporation or sputter evaporation.

Then, while the substrate 1 is placed on a turntable and rotated, the laser beam focused by the objective lens 9 is directed to the first
The unevenness forming layer 6 located above the unevenness portion 5 is irradiated and this n is traced. This tracing is performed by obtaining a track deviation detection signal based on the diffraction pattern of the laser beam reflected from the unevenness forming layer 6. Then, at a position in the trace where a signal information bit is to be provided, the amount of laser light is increased to dope the chalcogenide glass layer 7 with the metal of the metal layer 8. In addition, in the figure 1
0 indicates a chalcogenide glass portion doped with metal by laser light as described above.

Then, the metal layer 8 is dissolved in a solvent and further immersed in an alkaline solution. As a result, the metal-doped chalcogenide glass portion 1o is left and the other unevenness forming layer 6 is formed.
As shown in FIG. 1(d), the second uneven portion 11 is formed on the upper part of the first uneven portion 5. In the information storage medium master formed in this way, the first uneven portion 5 corresponds to a tracking guide, and the second uneven portion 11 corresponds to a bit for signal information.

The manufacturing method described above has the following unique effects.

(b) The height dimensions of the first uneven portion corresponding to the tracking guide and the second uneven portion corresponding to the signal information bit are regulated by the etching depth and the thickness of the unevenness forming layer. And the second uneven portion can be formed with high precision.

(b) Since the substrate and the unevenness forming layer are made of different materials, the first unevenness formed on the substrate does not change when forming the second unevenness. The second uneven portion can be formed easily and stably.

(c) Since the formation processes of the first uneven part and the second uneven part are completely separated, even if the formation of the first uneven part is defective, by discarding it, the second uneven part can be formed. This eliminates the need to reduce the yield of forming the uneven portions in step 2.

2) Since the forming process of the first uneven part and the second uneven part are completely separated, a large number of discs with only the first uneven part formed are stocked in advance, and the master disk can be used as needed. This makes it possible to adopt a process for rapidly manufacturing.

2) When forming the second uneven part, the uneven forming layer formed on the north 1 uneven part is scientifically traced.
High mechanical precision is not particularly required for the feed mechanism of the objective lens that focuses the laser source, and therefore it is possible to simplify the manufacturing apparatus.

In addition, in the master disc for information storage medium having the above-described structure, the first uneven portion corresponding to the tracking guide and the second uneven portion corresponding to the signal information bit have good shapes and dimensions. Tracking guides with good dimensional accuracy and signal information bits are transferred to information storage media that are mass-produced using this master disk, and as a result, information storage media that can perform accurate information reading and stable tracking. will be able to mass-produce.

Next, a second embodiment of the present invention will be described.

FIGS. 2(α) to 2(d) are cross-sectional views showing the manufacturing method according to the second embodiment of the present invention in order of steps. Detailed description of the steps similar to those in the first embodiment will be omitted. The different step is a first step of forming a first uneven portion on the substrate. In other words, the glass plate 1 whose surface has been polished as shown in Fig. 2 @)K
6 is coated with a positive type photoresist using a spinner to form a photoresist layer 2. Then, the photoresist layer 2 is exposed concentrically or spirally with a laser beam focused by an objective lens 3 to form a photoresist exposed portion 4. Then, by developing and fixing the photoresist layer 2 and removing the photoresist exposed area 4, unevenness is formed there.
A metal layer (not shown) is formed by plating nickel or the like on the glass plate 16, and this layer is peeled off from the glass plate 16 (the peeled plate is referred to as a master plate). The irregularities on the glass plate 13 are reversely transferred to this master plate, and a metal layer (not shown) is formed by plating nickel or the like on the irregular surface of this master plate. It is peeled off from the master plate (the peeled plate is called a mother plate).

The uneven surface of the glass plate 16 is directly transferred to this mother plate, and the uneven surface of this mother plate is further plated with nickel or the like to form a metal layer (not shown) with a thickness of about 1111 mm. 1) is formed, and this is peeled off from the mother plate. What is formed by peeling off in this way is a concavo-convex plate (stamper plate 5), and as shown in FIG. 2(A), concavities and convexities opposite to those on the glass plate are formed.

Through such a process, the first uneven portion 5
A substrate 1 is formed. The subsequent process is almost the same as that of the first embodiment, as shown in FIG.
An uneven portion 5 of Ml corresponding to the tracking guide of A,
An information storage medium master having a height of 140 (M) and second uneven portions 11 corresponding to signal information bits will be manufactured. It is preferable that the material is different from the material, for example, Ag, Ct.
Formed by traps such as L.

The second embodiment can also provide the same effects as the first embodiment.

Next, a sixth embodiment of the present invention will be described.

FIGS. 6(α) to 6(C) are ttcm cross-sectional views of the manufacturing method according to the sixth embodiment of the present invention in the order of steps.

First, as shown in FIG. 5(α)K, the surface of the glass substrate 1 whose surface has been polished is cut concentrically or spirally with a mechanical cutting blade, for example, a diamond needle 15, to form the first uneven portion 5. do. This first uneven portion 5
The depth is, for example, 700 A, which corresponds to λ/4 where λ is the wavelength of the reading laser beam.

Then, as shown in FIG. 6<h>, Cr is deposited on the substrate 1.
The unevenness forming layer 6 is formed by vacuum evaporation to a fc thickness of 700A. At this time, since the surface of the unevenness forming layer 6 follows the unevenness shape VC of the surface of the substrate 1, a tracking guide having the same shape and dimensions as the first unevenness part 5 is placed above the first unevenness part 5. 16 will be formed. Then, a positive type photoresist is spinner coated on the surface of the unevenness forming layer 6 to form a photoresist layer 2. Thereafter, while tracing the tracking guide 16, a laser beam focused by the objective lens 3 is exposed at a position where a signal information pit is to be provided, thereby forming a photoresist exposed portion 4. Then, this photoresist layer 2 is developed and fixed, and the exposed portion of the photoresist is removed. Using the photoresist layer 2 thus left as a mask, the exposed portion of the unevenness forming layer B is cut to a depth of 1400 mm. ! Etch by f and remove that part.

After etching, the photoresist layer 2 is removed using an organic solvent, and as shown in FIG.
0. A master disk for an information storage medium having second uneven portions 11 of f is manufactured.

The third embodiment can also provide the same effects as the first embodiment.

Next, a fourth embodiment of the present invention will be described.

FIGS. 4(α) to 4(C) are cross-sectional views showing the manufacturing method according to the fourth embodiment of the present invention in the order of steps. Detailed explanations of steps similar to those in the sixth embodiment will be omitted.

A different process is that the photosensitive substrate is exposed to laser light, and that portion is precisely removed to form the first uneven portion. That is, the surface of a polished glass plate (not shown) is plated with KNi to a thickness of about 1 inch, and then this plated layer is peeled off from the glass plate (not shown), and this is used as a substrate 1. Then, as shown in FIG. 4(a), the substrate 1 is placed on a turntable and rotated, and the surface of the substrate 1 is exposed concentrically or spirally with a laser beam focused by an objective lens 6. By doing so, the portions are successively precisely removed to form the first uneven portion 5 having a depth of 700A.

The subsequent steps are almost the same as those of the sixth embodiment, as shown in FIG. 4(b)K, and finally, as shown in FIG. 4(C), a tracking guide 16 with a depth of 700A is formed. A master disc for an information storage medium is manufactured which is provided with second uneven portions 11 having a depth of 1400.4 and corresponding to pits for signal information. Note that the unevenness forming layer 6 in this case is desirably made of a material different from that of the substrate 1, and is formed of, for example, Cu.

Therefore, the fourth embodiment can also provide substantially the same effects as the first embodiment. In particular, since the first uneven portion can be formed by precision removal using a laser beam, the manufacturing process can be extremely simplified.

Next, a fifth embodiment of the present invention will be described.

FIGS. 5(α) to 5(C) are cross-sectional views showing the manufacturing method according to the fifth embodiment of the present invention in the order of steps. Detailed explanations of steps similar to those in the first embodiment will be omitted.

The different process is a step of providing an unevenness forming layer on a substrate on which a first unevenness is formed, and forming a second unevenness thereon. That is, in the same manner as in the first embodiment, the concavo-convex portion 5 of Vczi is formed on the glass substrate 1, and as shown in FIG.
A photosensitive layer 18 is formed by vacuum evaporation using No. 2000.4. Then, while the substrate 1 is placed on a turntable and rotated, a laser beam focused by the objective lens 9 is irradiated onto the photosensitive layer 18 located above the first uneven portion 5. Let it be traced. Then, the light intensity of the laser beam is increased to partially remove the photosensitive layer 18 at a position in the trace where a signal information bit is to be provided. After that, Figure 5 (A) [
The unevenness forming layer 6 is formed by ivy vapor deposition. At this time, the unevenness forming layer 6 is divided by holes formed by partially removing the photosensitive layer 18. Then, the photosensitive layer 18 along with the substrate is dissolved in an alkaline aqueous solution such as IJ Mu aqueous solution or calcium hydroxide aqueous solution, and the unevenness forming layer 6 in contact with the upper part of the photosensitive layer 18 is also dissolved. It will be removed. In addition, the unevenness forming layer 6 formed in contact with the first unevenness portion 5
remains, the first uneven portion 5 corresponding to a tracking guide trap with a height of 700A, and a height of 1400A. A master disk for an information storage medium is manufactured, which includes second uneven portions 11 corresponding to signal information pits. Note that the photosensitive layer 18
can also be formed from other metals, metalloids, or heat-sublimable organic materials (eg, carbon-containing nitrocellulose).

The fifth embodiment can also provide substantially the same effects as the first embodiment. In particular, since no photoresist is used in the photosensitive layer or the unevenness forming layer, the sensitivity of these layers to laser light does not change, which has the unique effect of making it easier to improve processing accuracy.

It should be noted that the above embodiment is merely an example, and it goes without saying that various modifications can be made within the scope of the gist of the present invention.

In particular, in each example, one manufacturing method and a master disc for an information storage medium manufactured by the method have been described, but each master disc was manufactured by the method described in the relevant example.
The present invention is not limited to the above method, and may be produced by other methods.

〔Effect of the invention〕

As is clear from the above explanation, in the information storage medium master disc of the present invention, the tracking guide and the signal information bit are formed with high precision, so that accurate information reading and stable tracking can be achieved. It has excellent effects such as being able to contribute to the mass production of information storage media that can perform This method has excellent effects such as being able to form pits with high precision and relatively easily, thereby improving productivity and reducing manufacturing costs.

[Brief explanation of drawings]

FIGS. 1(α) to (d) are cross-sectional views showing the manufacturing method according to the first embodiment of the present invention in order of steps, and FIGS. 2(α) to (d) are sectional views showing the manufacturing method according to the second embodiment of the present invention. 6(α) to (C) are sectional views showing the manufacturing method according to the sixth embodiment of the present invention in the order of steps; FIGS. 4(α) to (C) are 5(a) to (C) are cross-sectional views showing the manufacturing method according to the fifth embodiment of the present invention in the order of steps. FIGS. DESCRIPTION OF SYMBOLS 1... Substrate, 5... 1st uneven|corrugated part, 6...
- Unevenness forming layer, 11... second unevenness part. Agent Patent Attorney Tadashi Misawa Yoshitou 2

Claims (6)

[Claims] (1) In a master disc for an information storage medium for manufacturing an information storage medium in which information can be read from the uneven portion by a focused laser beam, a substrate on which the first uneven portion is formed; A master disk for an information storage medium, comprising a second uneven portion formed by removing a part of an unevenness forming layer provided on a substrate. (2) In order to manufacture a master of an information storage medium from which information can be read using the focused laser light pressure, at least a first step of forming a first uneven portion on a substrate; An information storage medium master comprising: a second step of providing an unevenness forming layer on a substrate; and a third step of forming a second unevenness portion by removing a part of the unevenness forming layer. Production method. (3) In the first step, a metal is plated on a concavo-convex plate having concavo-convex portions corresponding to the first concavo-convex portions of the surface IIC, and a plating layer obtained by peeling n from the concavo-convex plate is applied to the plated layer. 3. The method of manufacturing a master disk for an information storage medium according to claim 2, wherein the substrate is provided with one uneven portion. (4) The method for manufacturing an information storage medium master according to claim 2, wherein in the first step, the first uneven portion is formed by mechanically cutting the substrate. (5) The method for manufacturing an information storage medium master according to claim 2, wherein in the first step, the first uneven portion is formed by partially etching the substrate. (6) Information according to claim 2, characterized in that in the first step, the first uneven portion is formed by removing a part of the surface of the flat substrate using a focused laser beam. A method for manufacturing a master disc for storage media.