JPH08306080A - Information recording medium and its mold - Google Patents

Abstract

PURPOSE: To maintain the good transfer state of a recording surface in spite of narrowing a track pitch and to make it possible to deal more than sufficiently with high-density recording and to easily and rapidly make duplication. CONSTITUTION: This information recording medium has guide grooves 4 and land parts 5 adjacent to these guide grooves. Recording is executed on the guide grooves 4 or/and the land parts 5. The ratio (L/G) of the width L of the land parts 5 and the width G of the guide grooves 4 is 0.47 to 2.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium (for example, a rewritable magneto-optical disk) and its molding die.

[0002]

2. Description of the Related Art MO (Magnet optical recording) is a so-called rewritable optical disk capable of writing, erasing and reading information by using a laser beam.
In a magneto-optical disc called a system or MD (Mini disc) or a phase change type erasable disc, a guide groove called a groove is formed for tracking,
In some cases, signal pits (for example, address pits) are also formed.

The width and depth of these guide grooves and pits are defined by their respective standards, but the ratio (L / G) of the width L of the land portion to the width G of the groove is the same for any disc.
The land area is wider than 2.0. Moreover, the depth of the groove is λ / 7 to λ / 9 (λ: wavelength of incident light), which is about 1/2 of the depth of the pit, which is λ / 4.

The reason why the land portion is wide is that the transfer is facilitated by widening the concave portion (groove) corresponding to the land portion in the stamper used as a duplication mold when manufacturing the disc. . The reason why the groove is made shallow is that there is a problem of transferability, but since it is originally for tracking, it does not matter if it is shallow (that is, even if the light output is small).

To copy such an optical disc, a CD
It is basically the same as the duplication condition of (Compact disc), but due to the writing and reading functions not found in CD, duplication conditions of the disc substrate are more stringent than the standards. .

However, in an optical disc with an increased recording density, the track pitch becomes narrower than 1.6 μm,
Not only recording on either land or groove,
Recording is also performed on both the land portion and the groove. In such a high density disc, if the groove depth is as shallow as about half of the pit as described above, there is a problem that a sufficient tracking signal cannot be obtained and crosstalk and jitter easily occur.

In order to avoid this, when the groove depth is made equal to the pit depth, if the ratio of the land width to the groove width (L / G) is reduced in response to the narrowing of the track pitch, the land is reduced. The width of the recess (groove) of the stamper corresponding to the portion becomes small, and it becomes difficult for the resin to fill the recess, and the transferability of the land portion tends to be poor. This remarkably occurs especially when transferring by injection molding.

The problem of the transfer failure occurs because the molten resin does not completely fill the deep groove having a narrow width. To solve this problem, it is necessary to raise the mold temperature to increase the fluidity of the resin. It is conceivable that the transfer cannot be performed satisfactorily simply by raising the mold temperature.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a good recording state on a recording surface even if the track pitch is narrowed as a medium for recording on a land portion and / or a guide groove.
To provide an information recording medium (especially an optical information recording medium such as an optical disk) that can sufficiently cope with high-density recording and can be easily duplicated in a short period of time, and a molding die used for manufacturing the same. It is in.

[0010]

As a result of earnest studies on the solution of the above problems, the present inventor has found that if a specific relationship is satisfied between the shapes and sizes of the land portion and the guide groove. Surprisingly, they have found that they can sufficiently cope with the narrowing of the track pitch and the high density of recording, and that the transfer state of the recording surface is remarkably improved, and they have arrived at the present invention.

That is, according to the present invention, in the information recording medium having the guide groove and the land portion adjacent to the guide groove and recording is performed on the guide groove and / or the land portion, the width L of the land portion is provided. And the width G of the guide groove (L / G) is 0.
It relates to an information recording medium characterized in that it is 47 to 2.0.

According to the information recording medium of the present invention, the width ratio (L / G) of the land portion and the guide groove is limited to a specific range of 0.47 to 2.0, which achieves the object of the present invention. Is essential above. This L / G should be 0.50 or more,
60 or more is better, 1.80 or less is good, and 1.60 or less is better.

Contrary to this, when L / G exceeds 2.0 as in the conventional case, the transfer state is good, but the land width is too large and the track pitch relatively expands, and the overall recording capacity decreases. However, it is not suitable for high density recording. On the contrary, if L / G is too small, especially less than 0.47, it is good in terms of high-density recording, but the transfer state of the recording surface is deteriorated due to transfer failure during copying.

In the information recording medium of the present invention, the guide groove has a depth equivalent to the height of the land portion, and the width of the guide groove or the land portion is 0.35 to 0.7 μm. This is desirable for maintaining good property.

If the guide groove is formed to a depth equivalent to that of the signal pit, the guide groove can be made sufficiently deep, and the optical output from the guide groove can be increased to obtain a good tracking signal or the like. Crosstalk and jitter can be prevented.

For high density recording, it is desirable that the track pitch is 1.6 μm or less. The recording surface has a mixture of grooves and signal pits or has a pre-groove, and the groove depth is λ / 4 to λ / 9 (λ: incident light) in order to obtain a sufficient tracking signal and the like. Wavelength).

Although the information recording medium of the present invention is actually configured as an optical disk, the glass transition point (Tg) of the molten resin is reduced on the die surface side during molding (copying), and other than that, it is molded. It has a unique layered structure that is lower than the Tg of the region. That is, in such an information recording medium, the glass transition point of the surface region on the side where the guide groove and the land portion are present is lower than the glass transition points of the regions other than the surface region.

The present invention also provides, as a molding die used to manufacture the information recording medium of the present invention, a width L'of a concave or convex portion corresponding to the land portion and a convex or concave portion corresponding to the guide groove. The ratio (L '/ G') to the width G'is 0.47 to 2.0 (preferably 0.50 or more, more preferably 0.60 or more, and preferably 1.80 or less, more preferably 1.60 or less). The present invention also provides a mold for an information recording medium (particularly an optical disc).

Also in this molding die, for the same reason as described above, the convex or concave portion corresponding to the guide groove has the same height or depth as the depth or height of the concave or convex portion corresponding to the land portion. , 0.35 to 0.7 μm in width, and the convex or concave portion corresponding to the guide groove is preferably formed at the same height or depth as the convex or concave portion corresponding to the signal pit.

Further, this mold has a track pitch of
Manufacture an information recording medium having a thickness of 1.6 μm or less, a groove and signal pits mixed with each other or a pre-groove, and a groove depth of λ / 4 to λ / 9 (λ: wavelength of incident light). Is preferably used to

[0021]

Embodiments of the present invention will be described below.

1 to 26 show various embodiments in which the present invention is applied to an optical disk.

The optical disc 1 shown in FIGS. 1 to 4 is a rewritable medium such as an MO or MD that can write, erase and read information, and is an optically transparent disc substrate 2 made of plastic or the like. Grooves or pre-grooves (guide grooves) 4 and lands 5 are formed alternately on the information recording surface 3 in the disk radial direction at a predetermined pitch. The groove 4 is a concave portion when viewed from the light incident side, and the land portion 5 is a convex portion when viewed from the light incident side (hereinafter,
Similar).

The predetermined land portion 5 has a depth λ /
4 (λ: wavelength of incident light 6) address pits 7 are formed, and the groove 4 is formed to a depth equivalent to that of the address pit 7.

Although not shown, this optical disc 1
In the case of a magneto-optical disc, a magnetic film of TbFeCo or the like and a protective film of an ultraviolet curable resin are formed on the recording surface 3.

In the magneto-optical disk, a magneto-optical signal is recorded in the groove 4 or in the land portion 5, and by irradiating the laser beam 6 along the groove 4, recording or reproduction is performed while continuously applying tracking servo. You can do the operation.

In this case, the servo signal is the laser beam 6
Is obtained based on the difference in the amount of return light between the groove 4 and the land portion 5 which are irradiated with. For this reason, the shapes of the groove 4 and the land portion 5 are such that the original recording signal and the servo signal can be sufficiently obtained.

The standard of the pre-grooved optical disk shown here may be specifically as follows. MO: ISO / IEC 10089 (130mm), ISO / IE
C 10090 (3.5 inches) MD: Rainbow Book

It should be noted here that the ratio (L / L) of the width L of the land portion 5 and the width G of the groove 4 is based on the present invention.
G) is set to a specific range of 0.47 to 2.0. The "width" in this case is, as clearly shown in FIG.
(Reverse) trapezoidal concave or convex part 1 / the sum of the upper and lower bases
2, that is, the average value of L or G = (W ₁ + W ₂ ) / 2 (hereinafter the same).

By setting L / G in a specific range in this way, the following remarkable effects can be obtained.

(1) In recording on the land portion 5 or the groove 4, sufficient transfer can be obtained even if the track pitch is narrowed (especially, as small as 1.6 μm or less). Recording density up to 6 times can be achieved.

(2) Although the pits and grooves of the optical disc up to now can be formed only by the convex stamper, the concave stamper can be formed without any trouble, and each track is individually separated. It is possible to transfer the mold to a hard disk media.

(3) Not only can the density of ROM discs such as CDs be increased, but it has been possible to use a metal stamper or a metal stamper, but it is also possible to use a mother stamper to shorten the delivery time. Can be expected. For CDs, stamper duplication enables mass production.

Next, these effects will be described in more detail along the disk manufacturing process shown in FIGS.

First, as shown in FIG. 5A, the original glass plate 8 is used.
After uniformly coating the photoresist 9 on the surface of the substrate by spin coating or the like, for example, using a cutting system such as He.
-The cutting beam from the Cd laser is modulated with a cutting signal, the modulated beam is selectively applied to the photoresist 9, and the photoresist 9 is left in a predetermined pattern through a developing process. Master (master)
Is prepared.

That is, in the remaining resist 9, the convex portion 9a corresponds to the land portion 5 and the concave portion 9b corresponds to the groove 4. Then, a pit 9c corresponding to the above-mentioned address pit 7 is formed on the convex portion 9a.

Next, although not shown, a metal film is deposited on the entire surface including the photoresist 9 by electroless plating, vacuum deposition or sputtering. This metal film has an uneven shape that follows the uneven shape of the resist.

Next, as shown by the alternate long and short dash line in FIG.
To wear. Then, the plating layer is peeled off, and the result shown in FIG.
The metal master 10 shown in (B) is produced. This metal master 10 has convex and concave portions 10a and concave portions 10 corresponding to the groove 4, the land portion 5 and the pit 7, respectively, on the concave and convex surface.
b and 10c are formed.

Next, as shown by the alternate long and short dash line in FIG.
To wear. Then, the plating layer is peeled off, and the result shown in FIG.
A mother stamper 11 shown in (C) is manufactured. This mother stamper 11 has concave and convex portions on its concave and convex surface corresponding to the groove 4, the land portion 5 and the pit 7, respectively.
11b and 11c are formed.

Next, as shown by the alternate long and short dash line in FIG.
To wear. Then, the plating layer is peeled off, and the result shown in FIG.
A stamper 12 shown in (A) is manufactured. This stamper
The convex and concave portion 12 has concave portions 12b, 12c corresponding to the groove 4, the land portion 5, and the pit 7, respectively.

Next, a predetermined resin 2 is injection-molded (or press-molded) on the uneven surface of the stamper 12 as shown by the alternate long and short dash line in FIG. 6 (A), and then peeled off as shown in FIG. 6 (B). Then, the disk substrate 2 is manufactured. This substrate 2 is shown in FIG.
2 and FIG. 2, the groove 4 and the land portion 5 are shown.
And pits 7 are formed by transfer from the stamper 12, respectively.

Although not shown, if necessary,
The optical film 1 is completed by laminating a magnetic film, a protective film, a reflective film and the like on the transfer uneven surface of the disk substrate 2.

In order to manufacture the optical disk 1 according to the present invention by the above-mentioned disk manufacturing process, in the stamper 12 as a molding die, the width L'of the concave portion 12b corresponding to the land portion 5 and the convex portion 12a corresponding to the groove 4 are formed. The ratio (L '/ G') to the width G'of the disk is L / G on the disk substrate 2.
The value is set to 0.47 to 2.0, which is consistent with (see FIG. 6 (B)). The definition of L ′ and G ′ here is half of the sum of the upper and lower bases of the (inverse) trapezoidal shape, like the above L and G.
The average value of

By using the stamper 12 whose L '/ G' is 0.47 to 2.0, the recess 12 of the stamper 12 is
Since b has a sufficient width (L '/ G' is 0.47 or more), the land portion 5 can be transferred well.

This is a stamper 12 as shown in FIG.
When a disk substrate is formed by injection molding or the like using molten resin, the molten resin 13 shown by the alternate long and short dash line gets over each convex portion 12a and each concave portion
This is because it flows so as to sufficiently enter the inside of 12b, is transferred well even in the concave portion 12b, and the land portion 5 is formed faithfully. Since the protrusions 12a and 12d are projected into the resin 13 at the time of molding, their shapes are essentially easy to transfer, and the obtained grooves 4 and pits 7 are formed.
The shape (especially on the bottom side) is faithfully reproduced.

However, if L '/ G' is less than 0.47 and the width of the concave portion 12b of the stamper 12 is too narrow, FIG.
As shown by the chain line in (A), the resin is
13 is not completely filled even by the pressure applied during molding.
As a result, the disk substrate 2 is not manufactured as shown in FIG. 7A, and the height of the obtained land portion 5 becomes low and the shape of the edge thereof is deformed as shown in FIG. 7B. It will be easier. In this case, reading and writing of recorded information will be hindered.

The cause of such a problem is, as shown in FIG. 9, that the flowing molten resin 13 is a recess 12b having a too narrow width.
This is because it is impossible to get inside completely.

As described above, the disc substrate 2 and the optical disc 1 using the same according to the present invention have the above L / G = 0.47 to L / G = 0.47 even when the track pitch is reduced to 1.6 μm or less to increase the density. Since a specific relationship of 2.0 is given to the concave-convex shape of the recording surface, it has a sufficient transfer shape, and can sufficiently cope with a high recording density of 5 to 6 times that of the conventional one. Becomes

Since the depth of the groove 4 is set to be equal to the height of the land portion 5 and the depth of the address pit 7,
Deep enough that the light output from it is high
Tracking servo can be performed well.

Further, the uneven shape of the transfer surface of the stamper 12 to be used, that is, the uneven shape such as L '/ G' = 0.47 to 2.0 is similarly formed in the metal master 10 and the mother stamper 11 other than the stamper 12. ing. Therefore, although the disk substrate 2 shown in FIGS. 1 and 2 and FIG. 6B can be duplicated by transfer from the stamper 12 as described above, it is directly formed by transfer from the metal master 10. Of course, it is possible.

In the conventional optical discs, the grooves and pits were formed by transferring the convex portions of the stamper. However, as long as the specific range of L '/ G' based on the present invention is satisfied, the stamper The recesses can also be sufficiently transferred. Therefore, by transferring such recesses, grooves and pits (these have a cross-sectional shape opposite to those in FIG. 6B) can be formed, and can be diverted to a discrete track type disk or the like.

In this sense, the disk substrate can be directly molded from the mother stamper 11 shown in FIG. 5 (C). In this case, the grooves and pits have the shapes opposite to those in FIG. 6B, but in the mother stamper 11, the width G ′ of the convex portion 11b corresponding to the groove and the width L ′ of the concave portion 11a corresponding to the land portion are set. Is L '/ G' = 0.47-2.0,
For the same reason as described above, the concave portion 11a is sufficiently filled with the resin, so that the uneven shape can be satisfactorily transferred.

As described above, since the molding from the mother stamper 11 is possible, the period required for manufacturing the disk substrate can be shortened and the mass productivity is improved.

10 and 11 exemplify another optical disk 21.

The optical disk 21 according to this example is a high density disk such as a CD, and has a groove (guide groove) on the information recording surface 23 of an optically transparent disk substrate 22 such as plastic.
The land 24 and the land portion 25 are alternately formed in the disk radial direction at a predetermined pitch. The light reflection film of aluminum or the like is omitted in the drawing.

The predetermined land portion 5 has a depth λ /
A signal pit 27 of 4 or λ / 6 (λ: wavelength of incident light 6) is formed, and the groove 24 is formed to a depth equivalent to that of the pit 27.

The recording signal is recorded as a pit 27, and by irradiating the laser beam 6 along the groove 24,
The playback operation can be performed while continuously applying the tracking servo. In this case, the servo signal is obtained based on the difference in the amount of returned light between the groove 24 and the land portion 25 which are irradiated with the laser beam 6.

The CD standard shown here is CD Recor.
dable: Can be an Orange Book.

It should be noted here that the ratio (L / L) of the width L of the land portion 25 and the width G of the groove 24 is based on the present invention.
G) is set to a specific range of 0.47 to 2.0.

As described above, by setting L / G in a specific range, the same remarkable effect as in the above-described example can be obtained.

FIG. 12 shows a stamper 32 used when molding the optical disk 21. The stamper 32 includes a convex portion 32a corresponding to the groove 24 of the optical disc 21, a concave portion 32b corresponding to the land portion 25, and a convex portion 32 corresponding to the pit 27.
and d are formed respectively.

The ratio (L '/ G') between the width L'of the concave portion 32b and the width G'of the convex portion 32a is set to 0.47 to 2.0, and the land of the disk substrate 22 transferred from the stamper 32 is set. The ratio of the width L of the portion 25 to the width G of the groove 24 is L / G = 0.47.
It will be ~ 2.0.

In this case also, the stamper 32 has L '/
Since G'is specified within the above range, the molten resin is sufficiently filled in the recess 32b during transfer. pit
Since there is a concave portion 32e continuous with the concave portion 32b between the convex portions 32d to be 27, the resin flows also through the concave portion 32e,
The recess 32e can be sufficiently filled and can smoothly enter the recess 32b. In this way, good transfer can be performed with good reproducibility.

On the contrary, if the above L '/ G' is too small and is less than 0.47, the width of the recess 32b becomes too narrow as shown in FIG. 13, and for the same reason as described with reference to FIG.
Insufficient amount of resin filled inside causes transfer failure.

Next, a specific example of the optical disc according to this embodiment will be described in more detail.

Example 1 In the manufacture of the optical disc as shown in FIGS. 1 to 4, various stampers in which the width ratio (L '/ G') between the land and the groove was changed during master cutting (FIG. 5A). Was cut so as to obtain, and various disk substrates were molded by injection molding using these stampers. The molding conditions for the disk substrate are as follows, and Table 1 below shows the land width / groove width (L / G) at the position from the center in the disk radial direction.

<Disc molding conditions> Resin: AD-9000TG (optical disc grade, thermoplastic polycarbonate system, glass transition point 147 ° C) manufactured by Teijin Chemicals Ltd. Injection molding machine: CD30E3ASE (optical disc specification) manufactured by Nissei Plastic Co., Ltd. Resin melting temperature 345 ℃ Disc cooling time 16 seconds Mold surface temperature 128 ℃ ~ 133 ℃ (variable)

[0068] * L / G (= L '/ G')

Then, with respect to the molded disk substrate, a scanning tunneling microscope (hereinafter referred to as STM).
By observing the shape of the land portion, the transfer height (corresponding to the amount of resin filled in the recess of the stamper) there was measured. The results are shown in Fig. 14 (however, the depth of the recess of the stamper is 80 nm).

According to this, even if the variation of STM measurement is taken into account by 5 to 6%, the transfer is remarkably deteriorated when the land width / groove width ratio (L / G) is particularly less than 0.5. On the other hand, when L / G is particularly 0.5 or more, and further 0.6 or more, the transfer amount is increased and the transferability is improved.

As described above, the fact that L / G influences the transferability was first discovered by the present inventor.
The surprising fact was that the transfer amount changed greatly when L / G was around 0.5. Since the transfer amount should be 95% or more (76 nm or more for the stamper recess depth of 80 nm), L /
It is particularly desirable that G is 0.50 or more, and further 0.60 or more.

It was also confirmed that the temperature of the die (stamper) (die surface temperature: hereinafter the same) also affects the transferability. That is, as shown in FIG. 14, the transfer tends to be improved by increasing the mold temperature, and the transferability can be improved by increasing the mold temperature. In this case, L / G ≧ 0.
At 60, the stability of the transfer amount increases.

However, since the resin oligomer (low molecular weight component) is leached on the disk surface, the original glass transition point (147 ° C.) of the resin is lowered to 130 to 135 ° C.

FIGS. 15 and 16 show that for different types of polycarbonate resins, the amount of oligomer (% by weight) is 20 μm or less, especially 10 μm in the surface area of the disk substrate 2.
It is shown that the thickness increases rapidly in the following thickness region 2a,
Correspondingly, the glass transition point Tg of the surface region 2a
Is shown to be decreasing (horizontal axis is logarithmic scale). In FIG. 6B as well, a state where such a low Tg surface region 2a is generated at the time of transfer is shown by a broken line.

In this way, the surface area 2 of the disk substrate 2 is
The Tg of a is almost the same as the mold temperature when the mold temperature is as shown in FIG. Therefore, the pits and grooves are easily deformed. Therefore, if the appropriate upper limit of the mold temperature is around 130 ° C. (lower than Tg) corresponding to the glass transition point Tg of the resin, the land / groove width ratio (L / G) will be good for good transfer. Shows that the lower limit is around 0.5, and it is desirable to set it to 0.5 or higher.

FIG. 20 (A) shows a SEM (scanning electron microscope) photograph of the transfer surface when the disk substrate according to the present invention is molded at a mold temperature of 130 ° C., showing that the transfer is good. I understand. FIG. 20 (B) shows a SEM photograph of the transfer surface of the disk substrate molded at a mold temperature of 120 ° C. The land height is low and the transfer amount is insufficient, but the mold temperature is low. It seems to be from.

Further, FIG. 21 shows an observation image of the transfer surface by the above-mentioned STM, in which the convex portion corresponds to the land portion and the concave portion corresponds to the groove. 22, FIG. 23, FIG. 24, FIG. 25 and FIG.
STM images (cross sections) when G is changed variously are shown. The larger L / G is, the better the land shape is, but the smaller L / G is as shown in FIG. G = 0.3
In 7), the shape of the land part, especially the flatness of the upper surface, is destroyed.

Example 2 As in Example 1, the width ratio of the land portion and the groove portion (L '/
G ') are different stampers, and the groove (recess) is 40 nm deeper than that of Example 1,
Corresponding disc substrates were injection molded in the same manner as in Example 1 using the two types of disc materials shown below. The molding conditions for the disk substrate are as follows, and Table 2 below shows the land width / groove width (L / G) at the position from the center in the disk radial direction.

Resin: (1) Polycarbonate resin AD-9000TG (manufactured by Teijin Chemicals, glass transition point 147 ° C.) (2) Zeonex resin (olefin series) 280R (manufactured by Nippon Zeon, glass transition point 140 ° C.)

[0080] * L / G (= L '/ G')

Then, with respect to the molded disc substrate, the shape of the land portion was observed by STM, and the transfer height there (corresponding to the amount of resin filled in the recess of the stamper).
Was measured. The results are shown in FIGS. 17 and 18 (however, the depth of the recess of the stamper is 120 nm).

According to this, even if the variation in STM measurement is taken into account by 5 to 6%, the land width / groove width ratio (L / G) is less than 0.47 regardless of the type of resin. , While the transfer is significantly deteriorated, L / G is 0.47 or more, especially
It can be seen that when it is 0.6 or more, the transfer amount is increased and the transferability is improved.

Also in this case, the transferability is improved by increasing the mold temperature, and the stability of the transfer amount is increased by L / G ≧ 0.6.

Example 3 The same Zeonex resin as in Example 2 was used, and the mold temperature (115
℃) was made higher than the glass transition point in the same manner,
A disk substrate was molded. About this disk substrate S
When the transfer of the land portion by TM was observed, the results shown in FIG. 19 were obtained.

According to this, the contribution of the resin melting temperature to the transferability is generally low.

From the above-mentioned examples, it is apparent that the groove transfer (molding of the land portion) by injection molding has little factor of the groove depth of the groove of the stamper and depends on the width of the groove. . That is, when the land width / groove width ratio (L / G) is less than 0.47, the transfer amount is remarkably reduced, so L / G should be 0.47 or more.

As described above, it was first discovered by the present inventor that L / G affects the transferability.
The surprising fact was that the transfer amount changed greatly when L / G was around 0.47. However, if this width ratio is too large, the recording capacity of the disc as a whole will be small, so 2.0 or less (preferably 1.80 or less, and further
1.60 or less).

When comparing the data of FIGS. 17 and 18,
Regarding the polycarbonate resin and the Zeonex resin, at the same mold temperature (for example, 130 ° C.), the Zeonex resin transfers even if the land width / groove width ratio = 0.47 or less. This is because the original glass transition points of polycarbonate resin and Zeonex resin differ by about 10 ° C (Tg of polycarbonate resin = 147 ° C, Tg of Zeonex resin).
= 140 ℃). However, the mechanical characteristics of SKEW
Since the value (warp) cannot be used as an optical disc if it exceeds the CD specification (0.6 degrees), in consideration of this, a resin of a type that has a low glass transition point and the heat deformation temperature does not relatively drop too much. It is desirable to select.

On the other hand, the width of the land (or groove) is, as shown in Table 3 below, in Zones 1 to 9 in Examples 1 to 3 as well.
0.35 μm or more up to (L / G = 0.50 or L / G ≧ 0.47), and in zone 10 (L / G <0.50, L / G <0.47)
It is 0.35 μm or less.

[0090]

The land width, that is, the groove width of the stamper is also an important factor, and even if the groove width is narrow, transfer is difficult for the above-mentioned reason.
The ratio is preferably the following, and it is desirable to satisfy L / G = 0.47 to 2.0 under this condition. This is because a narrow groove and a wide groove engraved on a flat plate have different amounts of infiltration of viscous fluid, and the former is less likely to intrude.

Although the present invention has been described with reference to the embodiments, the embodiments described above can be further modified based on the technical idea of the present invention.

For example, under the condition that the width ratio (L / G) is set within the range according to the present invention, the track pitch (preferably 1.6 μm or less) is changed variously, and the groove depth is also λ / It may be changed in the range of 4 to λ / 9 (λ: wavelength of incident light).

The mold to which the present invention can be applied is not limited to the stamper but may be a metal master or a mother stamper.

As is well known, the transfer surface of the optical disk may have a shape corresponding to the MO having a pre-groove or the like, including the above-mentioned example in which grooves and pits are mixed. Recording can be performed on at least one of the groove and the land.

[0096]

As described above, according to the present invention, the ratio (L / G) of the width L of the land portion to the width G of the guide groove is specified to be 0.47 to 2.0. In recording, even if the track pitch is narrowed (especially even if it is as small as 1.6 μm or less), sufficient transfer can be obtained, and a high recording density can be achieved by combining with the signal compression technology.

Further, the medium can be produced without any trouble even with a concave mold, and the range of usable molds can be expanded.

[Brief description of drawings]

FIG. 1 is a cutaway enlarged perspective view of a main part of an optical disc according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of the optical disc.

FIG. 3 is a schematic plan view of the optical disc.

FIG. 4 is a schematic diagram for explaining a recording surface shape of the optical disc.

FIG. 5 is an enlarged cross-sectional view of an essential part showing the method of manufacturing the substrate of the optical disc in the order of steps.

FIG. 6 is an enlarged sectional view of an essential part showing the method of manufacturing the substrate of the optical disc in the order of steps.

FIG. 7 is an enlarged cross-sectional view of an essential part showing a transfer failure state of the method for manufacturing the substrate of the optical disc.

8A and 8B are an enlarged perspective view and a cross-sectional view of an essential part of a stamper used for manufacturing a substrate of the optical disc.

FIG. 9 is an enlarged cross-sectional view of a main part of a stamper used for manufacturing a substrate of the optical disc.

FIG. 10 is a cutaway enlarged perspective view of a main part of another optical disc according to the present invention.

FIG. 11 is an enlarged cross-sectional view of a main part of the optical disc.

FIG. 12 is a cutaway enlarged perspective view of a main part of a stamper used for manufacturing a substrate of the optical disc.

FIG. 13 is a cutaway enlarged perspective view of a main part of another stamper used for manufacturing the substrate of the optical disc.

FIG. 14 is a graph showing transferability according to a land width / groove width ratio (L / G) of a substrate of an optical disc.

FIG. 15 is a graph showing the relationship between the thickness of the surface layer of the optical disc and the amount of oligomer.

FIG. 16 is a graph showing the relationship between the thickness of the surface layer of the optical disc and the glass transition point (Tg).

FIG. 17 is a graph showing transferability according to a land width / groove width ratio (L / G) of a substrate of another optical disc.

FIG. 18 is a graph showing transferability according to a land width / groove width ratio (L / G) of a substrate of another optical disc.

FIG. 19 is a graph showing a resin melting temperature and transferability according to a land width / groove width ratio (L / G) of a substrate of still another optical disk.

FIG. 20 is a sketch diagram of an SEM photograph showing a transferred state of the surface of the optical disc.

FIG. 21 is an STM image of the surface of the optical disc.

FIG. 22 is a graph showing the surface properties of an optical disc.

FIG. 23 is a graph showing the surface properties of another optical disc.

FIG. 24 is a graph showing the surface properties of another optical disc.

FIG. 25 is a graph showing the surface properties of another optical disc.

FIG. 26 is a graph showing the surface properties of still another optical disc.

[Explanation of symbols]

 1 ... Optical disc 2, 22 ... Substrate 2a ... Surface area 3, 23 ... Information recording surface 4, 24 ... Groove 5, 25 ... Land portion 6 ... Incident light 7, 27 ... Address pit 8 ... Master (master) 9 ... Photoresist 9a, 10a, 11b, 12a, 12d, 32a, 32d ... Convex portion 9b, 9c, 10b, 10c, 12b, 12c, 32b: Recess 10: Metal master 11: Mother stamper 12, 32 ... Stamper 13: Resin G, G '... Groove width L, L' ... Land width

Claims (11)

[Claims] 1. An information recording medium having a guide groove and a land portion adjacent to the guide groove, wherein a width L of the land portion and the guide groove are provided in the guide groove and / or an information recording medium in which recording is performed on the land portion. An information recording medium having a ratio (L / G) to the width G of 0.47 to 2.0. 2. The guide groove has a depth equivalent to the height of the land portion, and the width of the guide groove or the land portion is 0.35 to 0.7 μm.
The information recording medium according to claim 1, which is m. 3. The information recording medium according to claim 1, wherein the guide groove is formed to a depth equivalent to that of the signal pit. 4. The track pitch is 1.6 μm or less,
Grooves and signal pits are mixed or there is a pre-groove, and the groove depth is λ / 4 to λ / 9.
The information recording medium according to claim 1, wherein (λ: wavelength of incident light). 5. The information recording medium according to claim 1, wherein the glass transition point of the surface region on the side where the guide groove and the land are present is lower than the glass transition point of the region other than the surface region. 6. The optical disk according to claim 1, which is configured as an optical disk.
The information recording medium described in. 7. A mold used for manufacturing an information recording medium having a guide groove and a land portion adjacent to the guide groove, and recording is performed on the guide groove and / or the land portion, The width L'of the concave or convex portion corresponding to the land portion
And the ratio (L '/ G') of the width G'of the convex or concave portion corresponding to the guide groove is 0.47 to 2.0,
Mold for information recording medium. 8. The convex or concave portion corresponding to the guide groove is formed to have a height or depth equivalent to the depth or height of the concave or convex portion corresponding to the land portion and a width of 0.35 to 0.7 μm. The molding die according to claim 7. 9. The mold according to claim 7, wherein the convex or concave portion corresponding to the guide groove is formed at the same height or depth as the convex or concave portion corresponding to the signal pit. 10. The track pitch is 1.6 μm or less,
Grooves and signal pits are mixed or there is a pre-groove, and the groove depth is λ / 4 to λ / 9.
The mold according to claim 1, which is used for manufacturing an information recording medium having (λ: wavelength of incident light). 11. Used to manufacture an optical disc,
The mold according to claim 1.