JPS5914151A - Original board for information storage medium and its production - Google Patents

Abstract

PURPOSE:To produce a uniform and highly accurate original board for information storage medium in a simple method with high yield and a low cost, by forming simultaneously the depressed/projected parts for both tracking guidance and signal information to said material board which can read the information by means of the laser light. CONSTITUTION:For instance, Te, Al, etc. are vapor deposited to a glass substrate 20 to form a signal information producing layer 23, and a positive photoresist is formed on the layer 23 to obtain a layer 25 which functions as a tracking guidance forming layer 24. Then the laser light 27 is exposed spirally or concentrically by an objective lens 26, and the exposed part 28 is removed after development and fixing. Then Te is vapor deposited to form a light reflecting layer 29 and then to form a depressed part 22 for tracking guidance. Then the substrate is turned, and at the same time the lens 26 is moved in response to the eccentricity of a depressed part 21 which is formed by means of the reflected light given from the layer 29. Then the focal point of the light 27 is traced on the part 22. At the same time, the volume of the light 27 is increased at a part corresponding to a signal information pit in order to remove both layers 29 and 23. Thus the part 21 is formed for the signal information pit. Thus a uniform and highly accurate original board is obtained for an information storage medium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a digital audio disc (
Compact disc (CD) used in DAD)
It is read-only, such as optical video discs, or for recording and playback, such as image files and computer output memory (COM).
The present invention relates to a master disc for an information storage medium used when manufacturing an optical information storage medium in which at least information can be read using a focused laser beam, and a method for manufacturing the same.

[Technical background of the invention and its problems]

Usually, as shown in FIG. 1, an optical recording/reproducing information storage medium 1 that can at least read information using a focused laser beam is used as an information storage medium 1 for the purpose of achieving high density recording of information. In an information recording section 2 formed in an annular shape in 1, tens of thousands of tracks of tracking guides 3 are formed in advance in a spiral or concentric manner. In addition, recently, not only tracking guide 3, but also tracking guide 3
Signal information pit 4 as a signal information area indicating the track number and selector position indicating the position where information is recorded above.
Tracking guides with preformatting are now being developed, which make the software of a playback device or recording/playback device very easy to use by forming the tracking guide in advance.

On the other hand, the information storage medium 1 creates unevenness on the surface in units of pits and reads the difference in the amount of reflected light from there.
As shown in Fig. 2, the tracking guide 3 has a step of λ/8 with respect to the depth h1, that is, the wavelength λ of the reading laser beam, and the signal information guide 3 has a step with a depth of h2, that is, λ/4. It is said that forming pits 4 is appropriate.

Further, the information storage medium 1 having the tracking guide 3 and the signal information pits 4, which have the dimensional relationship as shown in FIGS. 3 and 4, that is, l1<l2, has, for example, FIGS. It is created as shown in f). That is, as shown in FIG. 5(a), a replica disc 11 is produced by plating the surface irregularities of a master disc 10 produced as described below. Next, as shown in (b), an information storage medium substrate 12 having an uneven surface is made using this duplication disk 11, and then a recording layer 13 is formed by vapor depositing metal or the like on the uneven surface of this substrate 12. Then, a master plate 1' of the information storage medium is produced. Then, as shown in (e), the inner and outer diameter portions of this original plate 1' are processed to form the information storage medium 1.

This information storage medium 1 is usually made by bonding two sheets together with inner and outer spacers 14 and 15 interposed therebetween, as shown in (F), to improve rigidity, prevent waviness, etc., and protect the recording layer 13, 13. It will be used in an enhanced state.

As described above, in order to manufacture the information storage medium 1, the master 10 having the uneven portions for the tracking guide and the uneven portions for the signal information pits to be transferred is required.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and an object thereof is to provide a good master disk for an information storage medium having a concavo-convex portion for a tracking guide and a concave-convex portion for a signal information pit, and a method for manufacturing the same. This is what I am trying to do.

[Summary of the invention]

The present invention resides in a master disc that is produced by forming an uneven portion for a tracking guide and then forming an uneven portion for a signal information pit along the uneven portion, and a method for manufacturing the same.

[Embodiments of the invention]

An embodiment of the present invention is shown below in FIGS. 6 and 7 (A),
This will be explained with reference to (g) and (c). Figure 6 shows master 10
This master disk 10 has a concave part 21 as an uneven part for signal information bits with a depth of about 1000 to 1300 Å on one side of the substrate 20, and a concave part 21 with a depth of 500 to 70 Å.
It has a configuration in which a concave portion 22 is formed as a concave and convex portion for a tracking guide of about 0 Å.

Finally, with reference to Figure 7 (a), (b), and (c), the master l0
Explain how to create. First, Te, Bi, Se, A
A signal information forming layer 23 with a thickness of about 500 to 700 Å is formed by vapor-depositing L or the like, and then a positive photoresist is spinner coated on top of the signal information forming layer 23 to a thickness of 500 to 700 Å.
After forming a photoresist layer 25 as a tracking guide forming layer 24 of approximately 100 to 300 nm, exposure is performed in a spiral or concentric pattern using a laser beam 27 focused by an objective lens 26, as shown in FIG. 7(A). . Next, the photoresist layer 25 is developed and fixed.
After removing the exposed photoresist portion 28, Te is vacuum-deposited thereon to form a light reflecting layer 29, as shown in FIG. 7(b).

Then, a tracking guide recess 22 whose bottom surface is the surface of the recess of the light reflective layer 29 is formed.

Next, as shown in FIG. 7(c), while rotating the substrate 20, the objective lens 26 is moved using the reflected light from the light reflection layer 29 in accordance with the eccentricity of the tracking guide recess 21 (focusing). (In conjunction with tracking) The focal point of the laser beam 27 is always traced on the tracking guide recess 21, and the intensity of the laser beam 27 is increased in the portion corresponding to the signal information pit to form a light reflecting layer 29 and a signal information forming layer. 23 is removed together with the concave portion 21 for signal information pits having the surface of the substrate 20 as the bottom surface. According to the manufacturing method shown in FIGS. 7(a), 7(b), and 7(c), the following hardening occurs. That is, since the tracking guide forming layer 24 and the signal information forming layer 23 are made of different materials, when one layer is processed to form an uneven shape, the other layer may be adversely affected. It is possible to form uneven shapes independently of each other.

Further, since the thicknesses of the tracking guide forming layer 24 and the signal information forming layer 23 are determined in advance, the depths of the recesses 21 and 22 do not change.

Further, since the signal information forming layer 23 is present between the tracking guide forming layer 24 and the substrate 20, after forming the recesses 22 for tracking guides, the recesses for signal information pits can be formed immediately without any processing. 21 can be formed.

Another advantage is that the depths of the tracking guide recesses 22 and the signal information pit recesses 21 can be freely controlled and varied extremely uniformly and with high precision.

Note that the present invention is not limited to this, and for example, FIGS. 8 to 16
The configuration may be as shown in the figure.

As shown in FIG. 8, the master may be characterized in that at least the tracking guide forming layer is made of a material containing a light-reflecting substance. That is, first, Te, Bi, Se, Ge, Al, etc. are deposited on the substrate 20 in advance to a thickness of 5.
After forming the signal information forming layer 23 with a thickness of approximately 0.00 to 700 Å, Ni or the like is further deposited on this layer to a thickness of 500 to 700 Å.
A tracking guide forming layer 24 having a thickness of approximately 00 Å is formed. Furthermore, a photoresist layer 25 is formed thereon by a spinner coating method. Next, the exposed portion of the photoresist is removed by exposing the photoresist to a laser beam focused in a spiral or concentric manner, and then developing and fixing the photoresist, thereby forming a mask of the photoresist layer 25 as shown in FIG. 8(a).

Then, the tracking guide forming layer 24 is etched in an aqueous ferric chloride solution or by dry etching to form a tracking guide recess 22, and then the photoresist layer 25 is removed.

After that, the whole substrate 20 is rotated and the laser beam 27 is rotated.
The focal point of the laser beam 27 is always traced on the tracking guide recess 21, and the intensity of the laser beam 27 is locally increased to deform the signal information forming layer 23, as shown in FIG. 8(b).
Concave portion 2 for signal information pit whose bottom surface is the surface of the substrate 20
1 may be formed.

The production method shown in FIGS. 8(a) and 8(b) has the following effects. That is, after forming the tracking guide recesses 22 in the tracking guide forming layer 24, the optical device (writing device) for forming the signal information pit recesses 21 directly utilizes the light reflective property of the tracking guide forming layer 24. and can be tracked.

Since the tracking guide forming layer 24 and the signal information forming layer 23 are made of different materials, when one layer is processed to form an uneven shape, there is little adverse effect on the other layer. It is possible to form uneven shapes independently of each other.

Further, since the thicknesses of the tracking guide forming layer 24 and the signal information forming layer 23 are determined in advance, the depths of the recesses 21 and 22 do not change.

Further, since the signal information forming layer 23 is present between the tracking guide forming layer 24 and the substrate 20, after forming the recesses 22 for tracking guides, the recesses for signal information pits can be formed immediately without any processing. 2l can be formed.

Another advantage is that the depths of the tracking guide recesses 22 and the signal information pit recesses 21 can be freely controlled and varied extremely uniformly and with high precision.

Alternatively, it may be created as shown in FIG.

That is, first, a glass plate whose surface has been polished in advance is placed on the substrate 2.
0, and a tracking guide recess 22 is formed by mechanical cutting such as scratching with a diamond needle on the surface, and then stainless steel is formed to a thickness of about 500 Å by vacuum evaporation on the recess 22 to form a light reflecting layer 29. shall be.

Further, a sufficiently thick photoresist layer 25 is formed thereon by a spinner coating method.

Next, the entire substrate 20 is rotated and the light reflecting layer 29 is rotated.
The focal point of the laser beam 27 is always traced on the tracking guide recess 22 using the reflected light from the ninth
As shown in Figure (a), the light intensity of the laser beam 27 is locally increased to locally expose the positive photoresist layer 25.

At this time, the objective lens 26 moves (focusing) as the substrate 20 moves up and down, and also moves (tracking) as the tracking guide recess 22 shifts.

Next, the photoresist layer 25 is developed and exposed to light, thereby removing the photoresist exposed portion 28 and exposing the light reflecting layer 29.

Then, using the photoresist layer 25 as a mask, the substrate 20 is
When the whole body is immersed in an etching solution (ferric chloride water bath solution), the exposed stainless steel as the light reflecting layer 29 is etched, and the locally diamond-cut substrate 20 is etched as shown in FIG. 9(b). Concave part 2 for tracking guide
2 is exposed. Then, this was used as an etching solution, a mixed solution of 6% hydrofluoric acid and 40% ammonium fluoride (pH 4.
2), the exposed portion of the substrate 20 is etched to form a recess 21 for a signal information pit as shown in FIG. 9(c). Thereafter, the photoresist layer 25' was removed in an organic solvent, and the light reflecting layer 29 made of stainless steel was removed in an aqueous solution of ferric chloride, as shown in FIG. 9(d).
A master disc 10 having a recess 21 for a signal information pit and a recess 22 for a tracking guide may be made as shown in FIG.

In addition to the above-mentioned stainless steel, the light reflecting layer 29 is made of Cu.
(etching solution ferric chloride), Al (etching solution alkaline aqueous solution), etc. In addition to the above-mentioned chemical etching, dry etching can also be used.

The production method shown in FIGS. 9(a), (b), (c), and (d) has the following effects. That is, since the recesses 22 for tracking guides and the recesses 21 for signal information pits are formed in the substrate 20, the manufacturing time per information storage medium is short and the manufacturing cost is low.

In addition, conventionally it was difficult to apply the photoresist layer 25 uniformly and without defects, but with this method, the thickness distribution of the photoresist layer 25 is not so much of a problem, and the shapes of the recesses 22 and 21 can be made uniform and stable. It can be done in this state.

In addition, it is possible to stock a large number of plates in which only the recesses 22 for tracking guides are formed, carry some of them around, and form recesses 21 for signal information pits when and where necessary.

Furthermore, when forming pits 21 for signal information while tracing on concave portions 22 for tracking guides, feedback is applied to the feed of the objective lens. therefore,
It is not necessary to make the objective lens feeding mechanism of the writing device for forming signal information pits with high precision, and the device for forming pits for signal information can be easily made as long as the writing device for tracking formation is made with high precision.

In addition, since the formation processes for the tracking guide recess 22 and the signal information pit recess 21 are separated, manufacturing failures in each process will not affect the other process (in the previous process). This has the effect of discarding unsuccessful items midway through.

Alternatively, it may be created as shown in FIG.

That is, after forming a photoresist layer 25 by uniformly coating a negative photoresist on a substrate 20 made of a glass plate with a polished surface, the photoresist layer 25 is exposed to laser light, developed, and fixed to form a photoresist. Only the exposed portions of the resist are left and Cr is deposited thereon to a thickness of about 700 Å to form the signal information forming layer 24 as shown in FIG. 10(A). Thereafter, when the photoresist layer 25 is removed using an organic solvent, the signal information forming layer 23 on the photoresist layer 25 is also locally removed to form a tracking guide recess 22. Furthermore, a positive photoresist is applied on top of it using a spinner coating method.
A photoresist layer 25 is formed. After that, the entire substrate 20 is rotated and the laser beam 27 is focused by the objective lens 26.
is traced along the tracking guide recess 22 and locally increases the light intensity of the laser beam 27.
A photoresist exposure area 28 is made as shown in Figure 0 (b).

Next, by performing development and fixing, the photoresist exposed portion 28 is removed, and a mask of the photoresist layer 25 is created.

Then, the exposed portion of the substrate 20 is etched to a depth of 5 mm by immersing the substrate 20 in a mixed solution (pH 4.2) of 6% hydrofluoric acid and 40% ammonium fluoride, or by dry etching.
After etching the photoresist layer 25 to a thickness of 00 to 700 Å, the photoresist layer 25 is removed using an organic solvent, and as shown in FIG. A master disc 10 having a concave portion 21 for a signal information pit having a bottom surface as shown in FIG.

In addition to the process shown in FIG. 10(A), a method for forming the recess 22 for the tracking guide is, for example, shown in FIG. 10(A).
D) Or it may be as shown in FIG. 10 (E).

That is, as shown in FIG. 10(d), a tracking guide forming layer 24 is formed by depositing Cu to a thickness of about 500 to 700 Å on a substrate 20, and then cut with a diamond needle 30 to form a recess 22 for a tracking guide. You may. In addition, as shown in FIG. 10 (e), the substrate 20
A tracking guide 9 forming layer 24 having a thickness of 500 to 700 Å is formed by vacuum evaporating Cr thereon, and then a photoresist layer 25 is formed by a spinner coating method, and after being exposed to laser light, it is developed and fixed to form a photoresist layer 24. A mask of the resist layer 25 may be made, and then an etching process may be performed to form the tracking guide recess 22 in the tracking guide forming layer 24. Note that after the etching process, the photoresist layer 25 is removed using an organic solvent.

The production method shown in FIG. 10 (a), (b), (c), (d), and (e) has the following effects. That is, since the thickness of the tracking guide forming layer 24 is fixed, the depth of the tracking guide recess 22 can be made uniform and the depth can be changed by simply forming the tracking guide forming layer 24 to a uniform thickness. It can also be easily done.

In addition, in the process from FIG. 10(B) to FIG. 10(C), since the area other than the formation part of the recess 21 for the signal information pit is masked by the photoresist layer 25, when the recess 21 for the signal information pit is formed by etching. , the shape of the recess 22 for other tracking guides is not changed.

Furthermore, it is difficult to apply the photoresist layer 25 to a uniform thickness and the yield is poor, but with this method, even if the thickness of the photoresist layer 25 is uneven and the overall thickness changes, it is difficult to apply. This has the effect that it does not have a large effect on the above. Alternatively, it may be created as shown in FIG. That is, first, Ag was applied by electroless plating to surface-polished glass, and then a 1.0 mm thick Cr plate (or Cu plate,
N1 plate, etc.) is made and separated from the glass plate, and then the Ag is removed to form the substrate 20. Then, a negative photoresist is applied on this substrate 20 to form a photoresist layer 25.
After forming the photoresist, it is exposed spirally or concentrically, and then developed and fixed, leaving only the exposed areas of the photoresist. Next, Cr is deposited to a thickness of 500 to 70 mm by vacuum deposition.
A tracking guide forming layer 24 is formed as shown in FIG. 11(a). Then, photoresist layer 2
5, the tracking guide layer 24 remaining on the photoresist layer 25 is locally removed to form a tracking guide recess 22.

Next, while rotating the entire substrate 20, the focused laser beam 27 is traced along the tracking guide recess 22, and the intensity of the laser beam is locally increased in some places as shown in FIG. 11(b). The concave portion 2l for the signal information pit may be formed by locally removing the concave portion 2l.

According to the creation method shown in FIG. 11 (a) and (b),
It has the following effects. That is, after forming the tracking guide layer 24 in which the recesses 22 for tracking guides are formed, the recesses 22 are formed using a focused laser beam.
Signal information pits are formed by tracing the top once. Therefore, the process for forming the recesses 21 for signal information pits is very simple, and the recesses 21 can be formed in a short time. Further, the present invention has the effect that the equipment for forming the recesses 21 for signal information pits can be simple. Alternatively, it may be created as shown in FIG. That is, a metal layer or semimetal layer 31 made of Te, Bi, Al, or an alloy containing them is deposited on the substrate 20 to a thickness of 500 to 700 mm by vacuum deposition or sputter deposition.
After forming this, a heat-sublimable organic layer 33 made of a thermosetting resin such as nitrocellulose containing carbon or epoxy containing carbon or an organic dye is further formed on it by spinner coating, and a laser beam is applied to the layer 33. By irradiating in two stages of high and low intensity, only the heat sublimable organic layer 33 is removed and the tracking guide recess 22 is also removed, and both the heat sublimable organic layer 33 and the metal layer or metalloid layer 31 are removed. A recess 21 for a signal information pit may be formed.

The production method shown in FIG. 12 has the following effects. That is, unlike photoresist, the sensitivity to the laser beam 27 does not change depending on the state of being left after forming the photosensitive material layer.

In addition, a heat sublimable organic layer 33 and a metal or semimetal layer 31
Since the sensitivity to be removed by the laser beam 27 is greatly different from that, the depths of the signal information pit recess 21 and the tracking guide recess 22 do not change greatly even if the amount of the laser beam 27 changes somewhat. Moreover, since it is a dry process, manufacturing equipment is simple.

Alternatively, the configuration shown in FIG. 13 may be adopted. That is, a photoresist layer 25 is formed on a substrate 20 made of a light-reflecting photosensitive material by a spinner coating method, and as shown in FIG.
As shown in (a), this photoresist layer 25 is exposed, developed and fixed, and the exposed portion 28 of the photoresist is removed. Furthermore, as shown in FIG. 13(b), using this photoresist layer 25 as a mask, dry etching or chemical etching is performed to a depth of approximately 500 to 700 Å using an etching solution consisting of an aqueous solution of ferric chloride. This forms a recess 22 for a tracking guide. After removing the photoresist layer 25 in an organic solvent, the bottom of the tracking guide recess 22 is appropriately removed by laser processing while rotating with a turntable, as shown in FIG. 13(c), thereby forming signal information pits. You may make it form the recessed part 21 for.

According to the production method shown in FIGS. 13(a), (b), and (c), the following effects are achieved. That is, master 10
In mastering from , since the master 10 itself can be made as a mask, (a) the number of plating steps from master to mother to stamper is reduced. (b) Master 10
Injection (injection molding) using itself as a stamper,
Since compression (compression molding) is possible, the mastering process can be reduced, and transfer defects and defects that tend to occur during the master → mother → stamper process can be eliminated.

In addition, since the master 10 itself has a light reflective characteristic in advance, compared to the case where a glass plate is used as the master 10, after forming the recess 22 for the tracking guide, a light reflective layer is formed to enable tracking focus. This has the effect that it is not necessary to form a

Alternatively, the configuration shown in FIG. 14 may be used. That is, an unevenness forming layer 34 made of Al is formed on the substrate 20 to a thickness of 1000 to 1400 Å by vacuum deposition or sputter deposition, and a photoresist layer 25 is formed thereon by a spinner coating method. And this photoresist layer 2
After exposure to photoresist No. 5, development and fixing are performed to remove the exposed portion of the photoresist as shown in FIG. 14(a). Furthermore, as shown in FIG. 14(b), the unevenness forming layer 34 is etched by placing the photoresist layer 25 as a mask into an etching solution consisting of a 10% concentration sodium hydroxide solution or a 10% concentration potassium hydroxide solution. depth 5
By etching approximately 00 to 700 Å, a recess 22 for a tracking guide is formed.

Next, after removing the photoresist layer 25 in a solvent such as alcohol, as shown in FIG. A recess 21 may also be formed. This figure 14 (a) (b) (
The creation method shown in c) has the following effects. That is, the recesses 21 for signal information pits are formed by simply tracing the recesses 22 with the focused laser beam after forming the recesses 22 for tracking guides, so the recesses 2l
The formation process becomes very easy.

In addition, since holes are made until reaching the interface between the unevenness forming layer 34 and the substrate 20 to form the recesses 21 for signal information pits, if the film thickness is uniform when forming the unevenness forming layer 34, the above-mentioned recesses 21 are formed.
The depth of the concave portion 21 is uniform throughout, and even if the amount of laser light changes slightly, the depth of the concave portion 21 does not change and is stable. In addition, if a photoresist is used, when the concave portion 22 for the tracking guide is traced with a focused laser beam, the photoresist layer will be exposed to light even to some extent, but in the case of this method, no photoresist is used and the amount of light is low. When tracing is performed, the effect is that the unevenness forming layer 34 made of a photosensitive material is not exposed to light. Furthermore, the 15th
As shown in the figure and FIG. 16, the recess 21 for the signal information pit and the recess 22 for the tracking guide may be made at the same time.

That is, as shown in FIG. 15, Te, Se, Bi, and Cr are deposited on a substrate 20 made of a glass plate or the like with a polished surface.
, A metal layer or semimetal layer 21 such as Al is formed to a thickness of about 1400 Å by vacuum evaporation, and the laser beam 27 focused by an objective lens 26 is focused on this metal layer or semimetal layer 31 in two stages of intensity. Depth 70 by irradiating
Tracking guide recess 22 and substrate 20 around 0 Å
A recess 21 for a signal information pit may be formed with a depth that reaches the surface of the signal information pit.

The production method shown in FIG. 15 has the following effects. That is, compared to using a photoresist as the photosensitive material on the master 10, (a) the metal layer or semimetal layer 31 can be formed uniformly on the substrate 20, so that the recesses 22 for tracking guides and the recesses 21 for signal information pits can be formed uniformly on the substrate 20.
It is easy to control the depth with high precision. (b) Sensitivity at the time of forming the recesses does not change depending on the state of being left after forming the photosensitive material layer. (c) It can be processed using a completely dry process and requires simple manufacturing equipment. It produces such effects.

Alternatively, it may be created as shown in FIG.

That is, an organic photosensitive material layer 32 such as a thermally sublimable organic material such as carbon-containing nitrocellulose or thermoplastic nac is formed on a substrate 20 such as a glass plate with a polished surface, and the organic photosensitive material layer 32 is The recesses 22 for tracking guides and the recesses 21 for signal information pits may be formed by laser processing in the same manner as in the case of FIG. 15 described above.

The production method shown in FIG. 16 has the following effects. That is, compared to using a photoresist as the photosensitive material on the master 10, (a) the organic photosensitive material layer 32 can be formed uniformly on the substrate 20, so that the recesses 22 for tracking guides and the recesses 21 for signal information pits are Easy to control depth with precision. (b) Sensitivity at the time of forming the recesses does not change depending on the state of being left after forming the photosensitive material layer.

(c) It can be processed using a completely dry process and requires simple manufacturing equipment. It produces such effects. In the above embodiment, it was explained that the side with the larger level difference was used as the signal information pit 4 and the side with the smaller level difference was used as the tracking guide 3, but there is no inherent reason why it is necessary to do so, and it is possible to pass through the plate. The signal information pit 4 is close to the wavelength of the laser beam that is used, and the tracking guide 3 is the depth. In each embodiment, the depth of the last laser-exposed part when creating the master disc is often deep, but if the signal information pit 4 is shallower than the tracking guide 3, it is usually exposed with a strong light intensity to provide signal information. A concave area for the signal information pit can be created by reducing or blocking the light in the area corresponding to pit 4. Since the wavelengths of the laser beam for recording and reproducing the medium l and the laser beam for creating the master disk are usually different, this method can also form the concave portions for the signal information pits with sufficient tracking.

Further, although the tracking guide and the signal information pit are formed from concave portions in the description, it goes without saying that the same objective can be achieved even if the tracking guide and signal information pit are formed from convex portions.

In addition, it goes without saying that the present invention can be modified in various ways without departing from the gist of the present invention.

〔Effect of the invention〕

As explained above, in the present invention, since the concavo-convex portion for the signal information pit and the concave-convex portion for the tracking guide are made at the same time, it is easier to work with and can be produced at a lower cost than when they are formed separately. This has the effect of making it possible to

Further, the present invention provides a master disk for manufacturing an information storage medium in which at least information can be read by laser light, in which a signal information forming layer is formed on a substrate with uneven parts for signal information pits, and a signal information forming layer is formed on the substrate. This structure includes a tracking guide forming layer in which an uneven portion for a tracking guide is formed. Therefore, since the tracking guide forming layer and the signal information forming layer are provided separately, when the tracking guide forming layer or the signal information forming layer is processed to form an uneven shape, there is less chance of adverse effects on the other layer, and It is possible to form an uneven shape with high precision.

Since the thicknesses of the tracking guide forming layer and the signal information forming layer are determined in advance, the depths of the tracking guide recess and the signal information pit recess rarely change.

Since the signal information formation layer is already present between the tracking guide formation layer and the substrate, after forming the recesses for the tracking guide, the recesses for the signal information pits can be formed immediately without any processing. can significantly improve performance.

It is possible to freely control and change the depths of the tracking guide recesses and the signal information pit recesses extremely uniformly and with high precision. Further, in the present invention, a master disc is produced by forming an uneven part for a tracking guide and then forming an uneven part for a signal information pit along this uneven part. Therefore, keep a large stock of boards with only uneven parts for tracking guides, and carry some with you.
Concave and convex portions for signal information pits can be formed later when and where necessary.

In addition, when forming the concave and convex portions for signal information pits while tracing the concave and convex portions for the tracking guide, we use the reflected light from the concave and convex portions for the tracking guide to feed back the focused laser beam to the tracking guide. Can be traced on uneven surfaces. In other words, since feedback is always applied to the feeding of the objective lens, the recording device for forming signal information pits does not require high mechanical precision for the objective lens feeding mechanism and can be used at low cost.
And it's easy to make.

In addition, since the processes for forming the uneven parts for tracking guides and the uneven parts for signal information pits are completely separated, manufacturing failures in each process will not affect the other manufacturing process. . In other words, by discarding the parts that failed in the process of forming the uneven part for the tracking guide, the yield does not decrease in the process of forming the uneven part for the signal information pit, and the process of forming the uneven part for the tracking guide is completely completed. This has the effect that uneven portions for signal information pits can be formed.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view of an information storage medium, FIG. 2 is a schematic vertical side view showing an enlarged main part, FIG. 3 is a schematic plan view, and FIG. 4 is a schematic plan view of a different information storage medium. A schematic plan view showing an enlarged view of the main parts; FIGS.
FIG. 6 is a partially omitted and enlarged schematic longitudinal cross-sectional side view of one embodiment of the master disc of the present invention, FIGS. (a), (b) to FIG. 16 are explanatory diagrams showing different methods of creating master discs. 1... Information storage medium, 3... Tracking guide,
4... Signal information pit, 10... Master, 20...
Substrate, 2l... Concavity for signal information pit, 22...
Concave portion for tracking guide, 23... Signal information forming layer, 24... Tracking guide forming layer. Applicant's agent Patent attorney Takehiko Suzue

Claims (7)

[Claims] (1) An information storage medium characterized in that an uneven portion for a tracking guide and an uneven portion for a tracking guide are simultaneously created in a master disk for manufacturing an information storage medium in which at least information can be read by a laser beam. Manufacturing method of master disc. (2) The method for manufacturing a master disk for an information storage medium according to claim 1, characterized in that at least two types of recesses having different depths are formed by changing the amount of laser light. (3) In a master disk for manufacturing an information storage medium in which at least information can be read by a laser beam, a substrate, a signal information forming layer provided on the substrate and having concavo-convex portions for signal information pits; 1. A master disc for an information storage medium, comprising: a tracking guide forming layer provided on the signal information forming layer and having an uneven portion for a tracking guide. (4) The master disk for an information storage medium according to claim 3, wherein the tracking guide forming layer is made of a material containing a light reflective substance. (5) After forming an uneven part for a tracking guide on a master disk for manufacturing an information storage medium that can read at least information with a laser beam, an uneven part for a signal information pit is formed along the uneven part for a tracking guide. 1. A method of manufacturing a master disc for an information storage medium, the method comprising: forming a master disc for an information storage medium. (6) A method for manufacturing a master disk for an information storage medium according to claim 5, characterized in that the uneven portions for signal information pits are formed on the substrate itself. (7) A method for manufacturing an information storage medium master according to claims 5 and 6, characterized in that the uneven portion is formed by laser processing.