JPS5940338A - Master disk for information storing medium and its production - Google Patents

Abstract

PURPOSE:To obtain a master disk for information storing medium capable of accurate reading and tracking which is suited to mass production, by forming a tracking guide forming layer on a substrate to provide the 1st recessing/projecting part, then laminating an information producing layer to said tracking forming layer to provide the 2nd recessing/projecting part. CONSTITUTION:A tracking guide forming layer 5 is formed by vapor depositing Cr on a substrate 1 and a resist exposure part 4 with 700Angstrom thickness. The part 4 is removed together with the layer 5 on the part 4 to leave the layer 5 at the part touching the substrate 1, and the 1st recessing/projecting part 6 is formed at the part where the part 4 is removed. Then Ni is vapor deposited on the substrate 1 and the part 4 with 700Angstrom thickness to form an information producing layer 7. A tracking guide 12 is formed over the part 6, and a resist layer 8 is formed on the layer 7. The laser light traces the layer 8 on the guide 12, and the quantity of laser light is increased at the position where the 2nd recessing/projecting part is formed. Thus an exposure part 10 is formed to the layer 8. The layer 7 is exposed and etched with the layer 8 used as a mask to obtain a recessing/projecting part 11. Thus it is possible to obtain a master disk having the tracking guide 12 of 700Angstrom and the part 11 corresponding to the information part of 1,400Angstrom depth.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a master disc 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]

As an information storage medium, a computer disc (CD) used for a digital audio disc (DAD) is used.
) and optical video discs, which are in the form of discs or tapes, and are read-only information storage media that can read a variety of information using focused laser light.
Image files and computer output memory (C
Information for recording and playback that is in the shape of a disk or tape, such as those used in OM), and that allows information to be written to and read from the recording layer using focused laser light. Examples include storage media and erasable information storage media.

Such information storage media have a narrow track pitch 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 the track number and sector position indicating the position where information is recorded are recorded in advance, the software for the recording/reproducing device will be easier. (also referred to as a tracking guide with preformatting).

The tracking guide and the signal information pit are formed by unevenness on a flat surface, and the difference in the amount of light reflected therefrom can be read as information. For this reason, the tracking guide is designed to have a depth of, for example, λ/8 (λ is the wavelength of the reading laser beam) so that the track deviation detection signal generated by the diffraction pattern of the light reflected from the guide can be increased and stable tracking can be achieved. (the same applies hereinafter), and is a rectangular groove with a width of approximately 0.6 to 0.8 μm. In addition, the signal information bits are determined by the maximum modulation degree (
The reading laser beam has a depth of λ/4 and a width of λ/4 so that the intensity of the reflected light is the lowest when the laser beam is irradiated directly above the signal information bit. The spot size is set to about 173.

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 image is transferred to the surface of the substrate of the information storage medium through the process.

Incidentally, the following method is known as a method for producing a tracking guide and signal information bits at the stage of manufacturing the master disc. In other words, a photoresist layer is formed on a glass substrate with a polished surface, and a sufficient amount of laser light is irradiated in the areas where signal information bits are to be formed 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 varies 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. Therefore, there was a problem that tracking guides and signal information bits could not be formed with high precision.Also, as described in Japanese Patent Application Laid-open No. 85025-1985,
There is a method of forming multiple photoresist layers with different sensitivities to provide tracking guides and signal information bits, but since photoresists are easily dissolved in solvents, several types of photoresists dissolved in solvents are layered. When applying,
There was a problem in that the underlying photoresist layer was easily attacked. Furthermore, there is a problem in that it is technically difficult to uniformly apply multiple layers of photoresist.

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

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and includes a tracking guide formed with high precision and a signal information bit, thereby enabling accurate reading of information and stable tracking of information storage. The purpose of the present invention is to provide a master disc for an information storage medium that can contribute to mass production of media, and furthermore, to make such a master disc for an information storage medium relatively easy and accurate, thereby improving productivity. It is an object of the present invention to provide a method for manufacturing a master disc for an information storage medium, which can reduce the manufacturing cost.

[Summary of the invention]

The first invention relates to a master disc for an information storage medium for manufacturing an information storage medium in which information can be read by a focused laser beam, and includes a substrate and a material provided on the substrate that is attached to the surface of the substrate. A tracking guide forming layer having a first uneven portion and a signal information forming layer having a portion laminated on the tracking guide forming layer and having a second uneven portion on the surface of the substrate. This is a master disc for an information storage medium characterized by the following. The second invention is for manufacturing a master of an information storage medium in which information can be read using a focused laser beam, and includes at least the following:
A tracking guide forming layer is provided on the substrate, and a first layer is formed thereon.
an information storage medium characterized by comprising: a first step of forming an uneven portion; and a second step of laminating a signal information forming layer on the tracking guide forming layer and forming a second uneven portion thereon. This is a method of manufacturing the master disc.

[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←) to (f) 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 (&), a photoresist layer 2 is formed on a glass substrate 1 whose surface has been polished by spinner-coating a negative tie photofusist. Then, the photoresist layer 2 is exposed concentrically or spirally with radar light condensed by the objective lens 3 to form a photoresist exposed portion 4. Thereafter, this photoresist layer 2 is developed and fixed, and the portions other than the photoresist exposed areas 4 are removed.

Then, as shown in FIG. 1(b), a tracking guide forming layer 5 is provided on the substrate 1 and the photoresist exposure portion 4 by vacuum evaporating or sputtering Cr to a thickness of 700×. At this time, since the tracking guide forming layer 5 is thinner than the thickness of the photoresist exposed portion 4, the tracking guide forming layer is separated at the side portions of the photoresist exposed portion 4. therefore,
As shown in FIG. 1(c), this photoresist exposure area 4
When dissolved in an organic solvent, the tracking guide forming layer 5 on the photoresist exposure area 4 is also removed, and the substrate 1
There is a tracking guide forming layer 5 in a portion in contact with
The first uneven portion 6 is formed in the portion where the photoresist exposed portion 4 has been removed (such a method is also simply referred to as a lift-off method hereinafter).

Thereafter, as shown in FIG. 1(a), Ni is vacuum-deposited or sputter-deposited to a thickness of 700× on the substrate 1 and the photoresist exposure portion 4 to form a signal information forming layer 7.
will be established. X'r! J1c A tracking guide 12 having the same shape as the first uneven portion 6 is formed above the first uneven portion 6 . Then, a positive photoresist is spinner-coated on the signal information forming layer 7 to form a photoresist layer 8. Then, while the substrate 1 is placed on a turntable and rotated, a laser beam focused by an objective lens 9 is irradiated onto the photoresist layer 8 on the tracking guide 12 to be traced. This tracing is performed by obtaining a track deviation detection signal based on the diffraction pattern of the laser beam reflected from the tracking guide 12. Then, the amount of laser light is increased at the position where the second uneven portion is to be provided in the trace to form a photoresist exposed portion of 1° in the photoresist layer 8.

Then, the photoresist layer 8 is developed and fixed, the photoresist exposed portion 1o is removed, and the signal information forming layer 7 is partially exposed. Thereafter, using the remaining photoresist layer 8 as a mask, the exposed portion of the signal information forming layer 7 is etched and removed, and a second uneven portion 11 is formed in that portion (see FIG. 1 ()). . As the etching solution, it is desirable to use a 37% ferric chloride aqueous solution.

Thereafter, by removing the photoresist layer 8 with an organic solvent, the photoresist layer 8 is removed to a depth of 700 mm as shown in FIG. 1(f).
A master disk for an information storage medium is manufactured, which includes a tracking guide 12 of X and a second concavo-convex portion 11 corresponding to a signal information radius of 1400^ in depth. Note that the depth dimensions of the tracking guide 12 and the second uneven portion 11 are merely examples; for example, the depth 700X corresponds to λA when the wavelength of the reading radar light is λ.

The manufacturing method described above has the following unique effects.

(B) Since the depth dimensions of the first uneven portion and the second uneven portion are regulated by the thicknesses of the tracking guide forming layer and the signal information forming layer, the tracking guide and signal information pits can be formed with high precision. can be formed.

(b) Since the formation processes of the first uneven part and the second uneven part are completely separated, even if the first uneven part is poorly formed, it can be discarded. This eliminates the need to reduce the yield of forming the second uneven portion.

(c) Since the formation process of the first degree unevenness and the second unevenness are completely separate, it is possible to stock a large number of products with only the first degree unevenness formed in advance and use them as required. This makes it possible to adopt a process of quickly manufacturing the master disc.

(b) When forming the second uneven portion, the top of the first uneven portion is optically traced, so high mechanical precision is particularly required for the movement mechanism of the objective lens that focuses the laser beam. Therefore, it is possible to simplify and downsize the manufacturing equipment.

(e) Since the first uneven portion is formed by the lift-off method, the precision of the edge portion of the first uneven portion is particularly good, and it is therefore possible to form a highly accurate tracking guide.

In addition, in the master disk for information storage medium having the above structure, the first uneven portion and the second uneven portion are formed with high precision, so that the information storage medium mass-produced using this master disk is Tracking guides and signal information pits with good dimensional accuracy are transferred, and as a result, it becomes possible to mass-produce information storage media that can perform accurate information reading and stable tracking.

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

Detailed explanations of steps similar to those in the first embodiment will be omitted. The different steps are the first by the lift-off method.
This is a step of forming uneven portions. That is, the photoresist exposed portion 4 is formed into a trapezoidal shape (cross-sectional shape), and then a tracking guide forming layer 5 is provided on the photoresist exposed portion 4 as shown in FIG.

In this way, a relatively large gap C is formed between the portion of the tracking guide forming layer 50 that is in contact with the substrate 1 and the photoresist exposed portion 4 remaining on the substrate l. The organic solvent for removing the photoresist exposed area 4 remaining on the photoresist exposed area 4 can be easily and quickly penetrated into the photoresist exposed area 4, which in turn makes it possible to improve the efficiency of manufacturing by the lift-off method. Become.

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

FIGS. 3(a) to 3(f) are cross-sectional views showing the manufacturing method according to the third embodiment of the present invention in the order of steps. Detailed description of the steps similar to those in the first embodiment will be omitted. The different process is that both the steps of forming the first uneven portion and the second uneven portion were performed by a lift-off method.

First, as shown in Figure 3), a photoresist layer 2 is formed by spin coating a positive photoresist on a glass substrate 1 whose surface has been polished. Then, the photoresist layer 2 is exposed to light concentrically or irradially to form a photolens 3g light section 4 using a laser beam focused by an objective lens 3. Thereafter, this photoresist layer 2 is developed and fixed, and the photoresist exposed portion 4 is removed.

Then, as shown in FIG. 3(b), KCr is coated on the substrate 1 and the photoresist layer 2 remaining on the substrate to a thickness of 7.
The tracking guide forming layer 5 is provided by vacuum deposition or sputter deposition at 00X. At this time, since the tracking guide forming layer 5 is thinner than the photoresist layer 2, the tracking guide forming layer 5 is divided on the side portions of the photoresist layer 2. Therefore, when this photoresist layer 2 is melted in an organic solvent, the tracking guide forming layer 5 on the photoresist layer 2 is also removed, leaving the tracking guide forming layer 5 in the portion in contact with the substrate 1. uneven part 6
will be formed (see FIG. 3(c)).

Thereafter, as shown in FIG. 3(d)K, a photoresist layer 8 is formed by spinner coating the photoresist again. Then, as in the first embodiment, the first uneven portion 6 is traced with a laser beam focused by the objective lens 9, and the amount of laser light is increased at the position where the second uneven portion is to be provided during this tracing. Then, seven photoresist exposed portions 10 are formed in the photoresist layer 8.

Then, the photoresist layer 8 is developed and fixed, the photoresist exposed area 10 is removed, and as shown in FIG. 3(e), Cr is vacuum-deposited or sputter-deposited to a thickness of 700× to form signal information. Layer 7 is provided. At this time, as in the case shown in FIG. 3(b), only in the portion where the tip portion 10 of the photoresist M is removed,
The signal information forming layer 7 is in direct contact with the first uneven portion 6, and the other portions are located on the remaining photoresist layer 8. Therefore, by dissolving this photoresist layer 8 with an organic solvent, the first uneven portion 6 is formed.
Only the upper signal information forming layer 7 remains, and thereby the second uneven portion 11 is formed. In this way, as shown in FIG. 3(f), the first uneven portion 6 corresponding to the tracking guide with a height of 700
A master disk for an information storage medium is manufactured which includes second uneven portions 11 corresponding to 0X signal information pits.

Also in the third embodiment, substantially the same effects as in the first embodiment can be obtained. In particular, in this embodiment, the first uneven portion can be formed by repeating a similar process called a lift-off method twice. Furthermore, since the tracking guide forming layer and the signal information forming layer are made of the same material, the adhesion strength between both layers can be particularly improved. Figure 4 (a) to explain
) to (f) are sectional views showing the manufacturing method according to the fourth embodiment of the present invention in order of steps.

First, as shown in Fig. 4(,), a set of 92 kinds of substances are mixed or diffused on a glass substrate 1 with a polished surface, which absorbs radiant energy and becomes partially heated. The tracking guide forming layer 5 is made of a substance. For example, As2S3 r As25s3 on the substrate 1
* A chalcogenide glass layer 5A made of As-8-Te type, As-8-3e type, etc. is formed, and a metal layer 5B of Cu, Or, etc. is further formed thereon by vacuum evaporation or suction or ivy evaporation.

Then, as shown in FIG. 4(b) K, the surface of the metal layer 5B is sequentially exposed in a concentric or spiral manner with a laser beam focused by the objective lens 3, and the metal in the exposed area is exposed to the chalcogenide glass below. Layer 5A is doped. In the figure, 5c indicates a chalcogenide glass portion doped with metal as described above. Thereafter, when the whole is immersed in an alkaline solution, the tracking guide forming layer 5 other than the metal-doped chalcogenide glass portion 5C is removed, and as shown in FIG. 4(c), the remaining chalcogenide is removed by the lath portion 5C. A first uneven portion 6 will be formed.

Next, a set of materials is placed on the substrate 1 and the first uneven portions 6 formed as described above, in which two types of materials are mixed or diffused by absorbing radiant energy and becoming partially heated. The signal information forming layer 7 is configured by the following. This is composed of, for example, a chalcogenide glass layer 7A made of the same material as the tracking guide forming layer 5 and a metal layer 7B (see FIG. 4(d)). The surface of the signal information forming layer 7 formed in this way is shaped like the first uneven portion 6.
It has an uneven shape that roughly follows the .

Then, as shown in FIG. 4(e), while the substrate 1 is placed on a turntable and rotated, the laser beam focused by the objective lens 9 is positioned above the first uneven portion 6. The metal layer 7B is irradiated and traced. This tracing is performed by obtaining a track deviation detection signal based on the diffraction pattern of the laser beam reflected from the metal layer 7B.

Then, the amount of laser light is increased at a position in the trace where a signal information pit is to be provided, thereby doping the chalcogenide glass layer 7A with the metal of the metal layer 7B. In the figure, 7C indicates a chalcogenide glass portion doped with metal by laser light as described above.

Then, when this is immersed in an alkaline solution, the metal-doped chalcogenide glass portion 7C is left and the other signal information forming layer 7 is removed, and as shown in FIG. 4(f), the first uneven portion 6 is removed. A second uneven portion 11 is formed on the upper part of. In the information storage medium master disk formed in this manner, the first uneven portion 6 corresponds to a tracking guide, and the second uneven portion 11 corresponds to a pit for signal information. Note that the heights of the first uneven portion 6 and the second uneven portion 11 are uniquely determined by the thicknesses of the chalcogenide glass layer and the metal layer. The second uneven portion 11 has a height of 1400X with respect to the surface of the substrate 1.

The fourth embodiment can also provide substantially the same effects as the first sliding door embodiment. In particular, since the first uneven portion and the second uneven portion are formed by the same process of doping metal, it has the unique effect of being able to shorten the manufacturing line.

(Margin below) Next, a fifth embodiment of the present invention will be described.

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

The different step is to precisely remove the tracking guide forming layer using a laser beam to form the first uneven portion. That is, as shown in FIG. 5(,), a tracking guide forming layer 5 is provided on a polished glass substrate 1 by vacuum deposition or sputter deposition of, for example, Cr to a thickness of 1400×. Then, the tracking guide forming layer 5 is exposed concentrically or spirally with a laser beam focused by the objective lens 3, and the exposed portion is precisely removed to a depth of 1400×, thereby forming the first uneven portion 6.

Thereafter, similarly to the fourth embodiment, a layer is formed on the first uneven portion 6 and the substrate 1 in which two types of substances are mixed or diffused (by absorbing radiant energy and becoming partially heated). The signal information forming layer 7 is composed of the same materials. For example, as shown in FIG. 5(b), this is composed of a chalcogenide glass portion 7A and a metal layer 7B on which Ag, Co, At, or the like is sputter-deposited or vacuum-deposited. Signal information forming layer 7 configured in this way
The surface thereof has a concavo-convex shape substantially along the first concavo-convex portion 6. The thickness of the signal information forming layer 7 is, for example, 700X.

Next, similarly to the fourth embodiment, the laser beam focused by the objective lens 9 is irradiated onto the metal layer 7B located above the first uneven portion 5 and traced (fifth (See figure (c)). During this tracing, unlike the fourth embodiment, the amount of laser light is reduced or blocked at the position where the signal information bit is to be provided, and the amount of laser light is increased in other parts to reduce the amount of the chalcogenide. The glass portion 7A is doped with the metal of the metal layer 7B. In FIG. 5(c), 7C indicates a chalcoke 9 night glass portion doped with metal by laser light as described above.

and solvent (37% ferric chloride solution for Cu,
When the metal layer 7B is dissolved in a 10% sodium hydroxide aqueous solution (for At) and then immersed in an alkaline solution, the other chalconitic glass layer 7A is removed, leaving behind the metal-doped chalcogenide glass portion 7C. As a result, a second uneven portion 11 is partially formed on the uneven portion 6 having the ratio of 1.

By going through such a process, as shown in FIG. 5(d), a second uneven part 11 corresponding to a tracking guide with a depth of 700X and a second uneven part 11 corresponding to a signal information pit with a depth of 1400X are formed. A master disc for an information storage medium having one concavo-convex portion 6 on its surface is manufactured.

The fifth embodiment can also provide substantially the same effects as the first embodiment.

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

FIGS. 6(a) to 6(f) are cross-sectional views showing the manufacturing method according to the sixth embodiment of the present invention in order of steps. Detailed explanations of steps similar to those in the first embodiment will be omitted. The different step is that the tracking guide forming layer is etched to form the first uneven portion. In other words, Fig. 6 (
As shown in a), a tracking guide forming layer 5 is provided on a glass substrate 1 with a polished surface by vacuum evaporation or vine evaporation of Nl. Then, a photoresist layer 2 is formed by spinner coating a Ponotaizo photoresist thereon. Thereafter, the photoresist layer 2 is exposed concentrically or spirally with a laser beam focused by an objective lens 3 to form a photoresist exposed area 4, and this photoresist layer 2 is further developed and fixed to form the photoresist layer 2. Remove the B light section 4. Next, Figure 6(b)
As shown in FIG. 2, using the remaining photoresist layer 2 as a mask, the portion of the tracking guide forming layer 5 exposed from this mask is removed by etching, thereby forming a first uneven portion 6 there. . Note that it is desirable to use a ferric chloride aqueous solution as the etching solution.

After removing the remaining photoresist layer 2 with an organic solvent, a signal information forming layer 7 is provided by the same process as in the first embodiment, and a second uneven portion 11 is formed thereon (sixth (See Figures (c) to (,)). In this embodiment, the signal information forming layer 7 is made of Cu, and the etching solution is 480 fl/! of chromic acid. 1 to which 31 CC of sulfuric acid was added was used. By going through these steps, as shown in FIG. 6(f), a master disc for an information storage medium including a tracking guide 12 and a second uneven part 1 corresponding to a bit for signal information is produced. will be manufactured. In this example, the material combination of the tracking guide forming layer and the signal information forming layer is A.
t and Cu, Cu and Or, stainless steel and Cu or C
It is also possible to combine r with force. Furthermore, as for the etching process, it is also possible to use not only the burr cul etching as in this embodiment, but also a dry process called plasma etching.

The sixth embodiment can also provide substantially the same effects as the first embodiment.

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 using the method have been described, but each master disc is not limited to one manufactured by the method explained in the relevant example. It is also possible to manufacture it by other methods. In addition, the first
By transferring the uneven portion and the second uneven portion, an information storage medium including a tracking guide and a signal information bit is manufactured. Regarding the width of the cross section perpendicular to the direction along , it is also possible to form the first uneven portion and the second uneven portion so that the width of the signal information bit is narrower. In information storage media manufactured using such master discs, the width of the tracking guide is wider than the width of the focal point for signal information, so when reading information, reflections from outside the tracking guide occur. The amount of light reflected from inside the tracking guide is much larger than the amount of light reflected from inside the tracking guide, so it is possible to suppress the conventional decrease in light reflection intensity due to interference between the two-way emitted light. As a result, the light reflection level on the tracking guide becomes high, and it is possible to obtain a large difference in the light reflection level between the light reflection level from the portion of the recording layer that stores signal information bits and other information. By improving the S/N ratio of information reading, accurate information reading becomes possible.

〔Effect of the invention〕

As is clear from the above description, in the master disc for information storage medium 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 performed. Furthermore, in the method for manufacturing a master for an information storage medium of the present invention, a tracking guide and a signal information bit are used. It has excellent effects such as being able to form the film with high precision and relatively easily, and thus improving productivity and reducing manufacturing costs.

[Brief explanation of drawings]

Figures 1(,) to (f) are cross-sectional views showing the manufacturing method according to the first embodiment of the present invention in order of steps, and Figure 2 shows some steps of the manufacturing method according to the second embodiment of the present invention. Cross-sectional view shown in Figure 3 (
, ) to (f) are cross-sectional views showing the manufacturing method according to the third embodiment of the present invention in order of steps, and FIGS. 4(a) to (f) are sectional views showing the manufacturing method according to the fourth embodiment of the present invention in order of steps 5(a) to 5(d) are sectional views showing the manufacturing method according to the fifth embodiment of the present invention in order of steps, and FIGS. 6(a) to 6(f) are sectional views showing the manufacturing method according to the sixth embodiment of the present invention. It is sectional drawing which shows the manufacturing method which is an Example in order of process. DESCRIPTION OF SYMBOLS 1... Substrate, 5... Tracking guide formation layer, 6
. . . first uneven portion, 7 . . . signal information forming layer, 11.
...Second uneven portion.

Claims (8)

[Claims] (1) In a master disc for an information storage medium used to manufacture an information storage medium that can read information using a focused laser beam, a substrate and a material provided on the substrate that is attached to the optical surface of the substrate. a tracking guide forming layer having a first uneven portion; and a portion laminated on the tracking guide forming layer;
1. A master disc for an information storage medium, comprising: a signal information forming layer having concavities and convexities. (2) When manufacturing a master disc of an information storage medium in which information can be read using a focused laser beam, at least a tracking guide forming layer is provided on a substrate and a first uneven portion is formed thereon. and a second step of laminating a signal information forming layer on the tracking guide forming layer and forming a second uneven portion thereon. Method. (3) In the first step, a mask corresponding to the first uneven portion is formed on the substrate, a tracking guide forming layer is further provided thinly than this mask, and then the mask is removed to form a mask on the substrate. The master disc for an information storage medium according to claim 2, wherein a tracking guide forming layer that is in contact with remains, and the first uneven portion is formed based on the remaining tracking guide forming layer. manufacturing method. (4) In the first step, the tracking guide forming layer is formed of a set of materials in which 92 different materials are mixed or diffused by absorbing radiant energy and becoming partially heated; 3. The method of manufacturing an information storage medium master according to claim 2, wherein the first uneven portion is formed by irradiating the guide forming layer with a laser beam. (5) In the first step, the entire first uneven portion is formed by etching the tracking guide forming layer provided on the substrate, and the master disk for information storage medium according to claim 2, wherein the first uneven portion is entirely formed. manufacturing method. (6) The second step includes completely forming a mask corresponding to the second uneven portion on the substrate and the first uneven portion, further providing a signal information forming layer thinner than this mask, and then removing the mask. As a result, the signal information forming layer in contact with the first uneven portion remains, and the second uneven portion is formed based on the remaining signal information forming layer. 2. The method for manufacturing a master disc for an information storage medium according to item 2. (7) In the second step, the signal information forming layer is constituted by a set of materials in which 92 different materials are mixed or diffused by absorbing radiant energy and becoming partially heated, and the signal information forming layer is Claim 2, characterized in that the second uneven portion is formed by irradiating the information forming layer with a laser beam.
A method for manufacturing a master disc for an information storage medium as described in 2. (8) In the second step, the second uneven portion is formed by etching the signal information forming layer provided on the substrate and the first uneven portion. A method for manufacturing a master disk for an information recording medium. (Margin below)